Dissertations / Theses: 'Endocrine resistance'

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Tewari, Nilanjana. "Mechanisms underlying obesity-related insulin resistance." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/34081/.

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This thesis investigates the effect of body composition on insulin resistance and the impact of supplementation with nutritional support or carbohydrate treatment. Insulin resistance occurs as a response to a number of stressors, including surgery. However, the mechanism underlying the development of insulin resistance is as yet unclear. Adipose tissue distribution appears to play a role in the development of insulin resistance and obesity-related complications. In obese and non-obese patients undergoing open abdominal surgery who received preoperative carbohydrate or placebo, there was a significant fall in perioperative insulin sensitivity and changes in the expression of genes relating to carbohydrate and fat oxidation. There was no influence of perioperative carbohydrate or obesity on change in insulin sensitivity. Patients undergoing neoadjuvant chemotherapy for oesophageal cancer underwent pre and post chemotherapy assessment of insulin sensitivity and body composition. There was a significant reduction in insulin sensitivity despite minimal change in body composition and adequate nutritional intake. These studies have provided further information about the optimal methods for assessment of insulin sensitivity and body composition as well as an insight into mechanisms underlying the association between body composition and insulin sensitivity.

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Ertefai, Benyamin. "Resistance mechanisms during endocrine treatment in breast cancer." Thesis, Cardiff University, 2016. http://orca.cf.ac.uk/95393/.

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Prolonged endocrine therapy is the mainstay of treatment for ER+ breast cancer patients. However, resistance develops in many patients which leads to more aggressive disease. Understanding the mechanisms of acquired resistance that emerge as a consequence of prolonged endocrine treatment remains critical. This study aimed to use gene expression profiling to discover induced mechanisms shared by a panel of MCF7-derived acquired resistant cells that underpin endocrine resistant growth. The in vitro panel represents resistance to oestrogen deprivation, tamoxifen or fulvestrant and includes long-term (3year) models to better-mimic clinical endocrine exposure. Affymetrix 1.0ST microarrays detected 572 genes induced in all resistant models versus MCF7. Over-represented ontologies, pathways and functional classification for these genes revealed induction of oxidative phosphorylation (OxPhos) and TCA cycle enzymes in the resistant models, a finding further confirmed by mass spectrometry. Increased oxygen consumption, NADH dehydrogenase and/or cytochrome C oxidase activity was detected in resistant cells, and targeting with OxPhos inhibitors Metformin or Antimycin A confirmed growth-dependency on OxPhos. Western blotting for AMPK (energy sensor) activity and its downstream anabolic targets (ACC, mTOR/P70S6K) showed Metformin reduced fatty acid and protein synthesis in growth-sensitive endocrine resistant cells. In silico analysis inferred clinical relevance since many TCA/OxPhos genes associated with earlier relapse in ER+ and/or tamoxifen treated patients. Monitoring basal glycolysis (extracellular lactate) and growth impact of 2DG or glutamine restriction demonstrated glycolysis and glutaminolysis also contribute to endocrine resistance. The microarrays furthermore revealed that metabolic kinases PCK2, ALDH18A1 and PFKFB2, and components of cell response to Zn were commonly-induced which may additionally help endocrine resistant growth. This study has revealed increased OxPhos arises as a consequence of prolonged endocrine treatment and is a key bioenergetic pathway sustaining resistance. Since resistant growth is Metformin-sensitive, such targeting of this energy pathway (alongside further antihormones or glycolysis/glutaminolysis inhibitors) could help treat resistance.

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McNeil, Catriona Mairi Garvan Institute of Medical Research Faculty of Medicine UNSW. "Downstream targets of the oestrogen receptor and endocrine resistance." Publisher:University of New South Wales. Garvan Institute of Medical Research, 2008. http://handle.unsw.edu.au/1959.4/41025.

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The transcription factor c-Myc is an early downstream target of oestrogen action in breast cancer cells in culture and it has been speculated that aberrant c-Myc expression may mediate antioestrogen resistance. However, studies of c-Myc protein expression as either a prognostic or predictive marker in human breast cancer have been limited and contradictory, as have been studies of c-Myc expression during breast cancer evolution. In order to assess the relationship between c-Myc protein expression and outcome from breast cancer, a representative cohort of 292 women with invasive ductal carcinoma (IDC) and linked clinicopathological data was assembled and tissue microarrays (TMA) generated from the archived breast cancer specimens. Detailed assessments of the expression of cyclin D1, cyclin E, p21WAF1/Cip1 and p27Kip1 were also conducted and analysed in relation to c-Myc expression using immunohistochemistry. Changes in c-Myc protein expression in a TMA model of breast cancer evolution were also conducted. Finally the cell-cycle effects of low-level constitutive c-Myc expression and high-level inducible c-Myc expression were evaluated in MCF-7 cells in vitro. Key novel results obtained were that c-Myc protein expression changed from preferentially nuclear to preferentially cytoplasmic during the evolution of breast cancer. In women with early invasive breast carcinoma, a "high-risk" cytoplasmic predominant c-Myc expression pattern was defined (~13% of cases) that independently predicted for poor outcome generally, among ER positive cases and in ER postive cases treated with endocrine therapy. In vitro studies confirmed that c-Myc overexpression was associated with resistance to the anti-proliferative effects of anti-oestrogens with persistence of both cyclin D1-cdk4 and cyclin E-cdk2 activities in the face of anti-oestrogen treatment. Further novel findings were that high cyclin D1 expression (upper 10% of expressors) was an independent predictor of poor outcome among ER positive breast cancer cases. Amongst ER + PR positive cases, both "high-risk" c-Myc expression and high level cyclin D1 expression were independent predictors of poor outcome. In summary, these data indicate that aberrant expression of the cell cycle proteins c-Myc and cyclin D1 may result in poor breast cancer outcomes in hormone receptor positive breast cancer and reinforces the importance of the cell cycle as a potential site of therapeutic manipulation in endocrine-resistant breast cancer.

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Moore, Kate. "Collateral resistance to oestrogen and erbB receptor activated growth in endocrine resistant breast cancer." Thesis, University of Edinburgh, 2007. http://hdl.handle.net/1842/24993.

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A panel of breast cancer cell lines (MIII, LCC1, LCC2, LCC9, LY2) derived from the MCF-7 breast cancer cell line with varying oestrogen and anti-oestrogen insensitivity (termed ‘resistant’) was used as a model to determine signalling pathways which may contribute to the development of this insensitivity. 17β-oestradiol (E₂) only significantly stimulated growth in MCF-7, MIII and LCC1 cell lines. Resistant cells were insensitive to growth factors, while MCF-7 cells remained responsive. MIII and LCC1 cells retained some tamoxifen sensitivity, while the remaining cell lines were unaffected. ERα expression was determined and ‘cross-talk’ was investigated by monitoring ERα activation via phosphorylation of serine residues 118 and 167 (P-S118/167) using western blotting. MIII, LCC1 and LCC2 cell lines expressed more ERα than MCF-7 cells, which may account for elevated basal growth in these lines. The remaining cell lines expressed similar ERα levels to MCF-y cells, hence another mechanism must account for elevated basal growth in these cells. ERα was subject to E₂ ‘turnover’ in all cells, indicating all cells contain functional ERα. ERα activation was then elucidated by observing P-S-118 and P-S167. Of interest, E₂ significantly enhanced P-S118 in LCC1 cells to a greater extent than MCF-7cells. Little or no P-S117 was observed in LCC9 cells irrespective of treatment. LCC1 and LCC9 cell lines were further investigate in comparison to MCF-7 cells as they displayed a progressive loss of E₂and anti-E₂sensitivity. No differences in P-S167 expression were observed between cell lines subject to control or E₂ treatment; HRGβ enhanced P-S167 to an equal extent in all cells. To investigate which upstream molecules may account for the changes in P-S118, the expression and activation of Akt, MEK and ERK were determined. Total levels of all three proteins were equivalent in all cells. Akt was significantly constitutively phosphorylated in the resistant cell lines compared to MCF-7 cells, suggesting this pathway is important in the development of resistance. TGFα and HRGβ significantly enhanced P-Akt in al three cell lines to a similar extent. HRGβ enhanced P-MEK in MCF-7, LCC1 and LCC9 cell lines, but this diminished as resistance progressed, suggesting a reduction in the involvement of this pathway. However, expression of P-ERK, which is downstream of MEK, was equivalent across all three cell lines, indicating that P-ERK was not responsible for endocrine resistance in this model. The novel recombinant humanised anti-erbB2 monoclonal antibody 2C4 (2C4) inhibited growth factor enhanced proliferation in MCF-7 cells via diminished P-Akt and PERKI/II activation. 2C4 significantly reduced HRGβ-enhanced P-Akt and P-ERKI/II in the resistant cell lines indicating these pathways may be partially responsible for some growth of these cells.

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Burmi, Rajpal Singh. "Identification of genes associated with endocrine resistance in breast cancer." Thesis, Cardiff University, 2006. http://orca.cf.ac.uk/55621/.

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Resistance to tamoxifen, Faslodex and oestrogen-deprivation represents a major hurdle in breast cancer management, and determining the underlying factors driving resistant growth may improve treatment and prognosis. Expression microarrays (Atlas Plastic Human 12K Microarrays GeneSifter software) were used to identify genes altered in breast cancer models with acquired resistance to tamoxifen (TamR) or Faslodex (FasR) versus their parental MCF-7 cell line through cluster analysis, t-testing and ontological examination. Selected genes were verified by PCR, Western blotting and immunocytochemistry. Alongside known breast cancer-related genes (PEA3, vitronectin), two novel genes increased in resistance were the securin/cell-cycle regulator Pituitary Tumour-Transforming Gene-1 (PTTG1) (p=0.013 and p=0.013 in TamR and FasR cells respectively), and GDNF receptor-a3 (GFRa3) (p=0.014 in TamR cells) that promotes cell survival signalling via its coreceptor RET. Increased levels of PTTG1, GFRa3, or their family members were observed in further endocrine resistant states, including an additional faslodex-resistant model that has progressed to a highly-aggressive state (FasR-Lt) and cells resistant to oestrogen-deprivation (X-MCF-7). PTTG1 and GFRa3 induction in response to an anti-EGFR agent in the resistant models implicated these genes in limiting its growth inhibitory effect, and GFR<x3 ligand (arternin) was shown to overcome anti-EGFR response (78% growth recovery). mRNA studies in clinical disease revealed a significant association of PTTG1 with lymph node spread (p=0.001), high tumour grade (p=0.001) and proliferation (p<0.001), while GFRa3 was enriched in ER-negative tumours (p=0.01), showing loss of tubular differentiation (p=0.04) and expressing EGFR (p=0.013), profiles implying roles in clinical resistance and aggressive tumour behaviour. Promisingly, PTTG1 or GFRo3 siRNA significantly reduced cell growth (by 72% p=0.003 and 81% p=0.004 respectively), proliferative capacity (by 23% p<0.001 and 32% p<0.001 respectively) and induced apoptosis (by 43% p=0.05 and 103% p=0.05 respectively) in resistant models. Cumulatively, these data indicate PTTG1 and GFRa3 may provide useful biomarkers and perhaps new therapeutic targets for multiple resistant states.

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Atefi, Mohammad Sadegh. "Estrogen receptor signaling and mechanism of resistance to endocrine therapy." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1581647181&sid=19&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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Wallace, I. R. "The influence of dietary and endocrine factors on insulin resistance." Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.677846.

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Insulin resistance is a characteristic feature of type 2 diabetes mellitus (DM ) and is associated with increased cardiovascular disease. This thesis presents one randomised controlled trial and two cross-sectional analyses, examining the influence of fruit and vegetable consumption and endocrine factors (se~ hormone binding globulin and vitamin D) on insulin resistance. After a 4 week diet of 1-2 portions fruit and vegetables per day, 105 overweight (8MI 27 - 35kg/m2), nondiabetic subjects at elevated cardiovascular disease risk (>20% 1 O-year CVD risk), were randomised to follow a diet of 1-2,4 or 7 or more portions fruit and vegetables per day for the 12-week intervention. Insulin resistance was assessed pre and post intervention using a two-step euglycaemic hyperinsulinaemic clamp. In the cross-sectional analyses, baseline clamp assessments were correlated with sex hormone binding globulin concentration and with vitamin D concentration respectively. Increasing fruit and vegetable consumption was not associated with a change in insulin resistance. Sex hormone binding globulin concentration was inversely correlated with insulin resistance, independent of androgen concentrations and adiposity in the subgroup of 28 postmenopausal women. No association was demonstrated in men. Vitamin D was not associated with insulin resistance. In overweight people at high risk of cardiovascular disease, increased fruit and vegetable intake has no effect on insulin resistance. Weight was maintained in our study and it is possible that alterations in weight have a greater impact on insulin resistance than dietary composition. We suggest that beneficial effects of fruit and vegetable consumption are not mediated by change in insulin resistance. We demonstrate an inverse association between sex hormone binding globulin concentration and insulin resistance, primarily peripheral insulin resistance. We demonstrate no association between vitamin D and insulin resistance and suggest that an association between vitamin D and type 2 DM may be mediated via effects on insulin secretion.

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Chen, Chun. "Systems Biology Study of Breast Cancer Endocrine Response and Resistance." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/51965.

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As a robust system, cells can wisely choose and switch between different signaling programs according to their differentiation stages and external environments. Cancer cells can hijack this plasticity to develop drug resistance. For example, breast cancers that are initially responsive to endocrine therapy often develop resistance robustly. This process is dynamically controlled by interactions of genes, proteins, RNAs and environmental factors at multiple scales. The complexity of this network cannot be understood by studying individual components in the cell. Systems biology focuses on the interactions of basic components, so as to uncover the molecular mechanism of cell physiology with a systemic and dynamical view. Mathematical modeling as a tool in systems biology provides a unique opportunity to understand the underlying mechanisms of endocrine response and resistance in breast cancer. In Chapter 2, I focused on the experimental observations that breast cancer cells can switch between estrogen receptor α (ERα) regulated and growth factor receptor (GFR) regulated signaling pathways for survival and proliferation. A mathematical model based on the signaling crosstalk between ERα and GFR was constructed. The model successfully explains several intriguing experimental findings related to bimodal distributions of GFR proteins in breast cancer cells, which had been lacking reasonable justifications for almost two decades. The model also explains how transient overexpression of ERα promotes resistance of breast cancer cells to estrogen withdrawal. Understanding the non-genetic heterogeneity associated with this survival-signaling switch can shed light on the design of more efficient breast cancer therapies. In Chapter 3, I utilized a novel strategy to model the transitions between the endocrine response and resistance states in breast cancer cells. Using the experimentally observed estrogen sensitivity phenotypes in breast cancer (sensitive, hypersensitive, and supersensitive) as example, I proposed a useful framework of modeling cell state transitions on the energy landscape of breast cancer as a dynamical system. Grounded on the most possible routes of transitions on the breast cancer landscape, a state transition model was developed. By analyzing this model, I investigated the optimum settings of two intuitive strategies, sequential and intermittent treatments, to overcome endocrine resistance in breast cancer. The method used in this study can be generalized to study treatment strategies and improve treatment efficiencies in breast cancer as well as other types of cancer.
Ph. D.

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Bokhari, Ali, Sathvika Gaddam, and Deepika 7471363 Nallala. "A Case of Compensated Thyroid Hormone Resistance." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/asrf/2019/schedule/50.

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INTRODUCTION Impaired sensitivity to thyroid hormone is described as any process that interferes with the effectiveness of thyroid hormone and includes defects in thyroid hormone action, transport, or metabolism. Here we present a case of a 60-year-old man with resistance to thyroid hormone (RTH), the most common form of impaired sensitivity. CASE A 60-year-old male presented to the endocrinology clinic with complaints of fatigue, decreased concentration, and impaired memory. He denied neck swelling, neck pain, peripheral edema, or any significant changes in weight, temperature sensitivity, bowel habits, and mood. His family history was significant for difficult to control thyroid disease in his brother and son. Thyroid exam was normal. Seven years ago, he was diagnosed with hypothyroidism of undetermined etiology with an elevated Thyroid Stimulating Hormone (TSH) and started on Levothyroxine. TSH was within normal limits in the first 3 years of therapy but TSH and free T4 remained high since then. MRI of the brain could not be done to rule out TSH secreting adenoma as he had pieces of metal in his face. In the absence of overt signs or symptoms of hyperthyroidism except atrial fibrillation, and a normal alpha subunit, IGF1, and prolactin, a TSH secreting adenoma is considered less likely. Levothyroxine was stopped and thyroid hormone levels were rechecked in 1 month that revealed elevated TSH with normal T3 and T4, representing compensated RTH. Genetic counseling was provided to the patient but he refused genetic testing. DISCUSSION The incidence of RTH is approximately 1 in 50,000 live births. In approximately 85 percent of cases it is due to mutations in the gene encoding the thyroid hormone receptor beta (TR-beta), while the other 15% are yet to be determined. It is characterized by reduced responsiveness of target tissue to thyroid hormones. The hallmark of RTH is the paucity of signs and symptoms of thyroid dysfunction despite the presence of high serum T4 and T3 concentrations. Clinical features include goiters, hyperactivity, and tachycardia. It can be diagnosed after other causes of hyperthyroxinemia are ruled out and confirmed with genetic testing.

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Sadler, Amanda J. "Identification of novel genes associated with endocrine resistance in breast cancer." Thesis, University of Reading, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485503.

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The overall aims of this project were to identify rnRNAs overexpressed or underexpressed as MCF7 human breast cancer cells progress to growth pathways independent of oestrogen and resistant to the antioestrogen, fulvestrant. Growth of oestrogen maintained and long-term oestrogen deprived MCF7,cells with or without la-8M l7p-oestradiol for 7 days enabled the comparison of expression profiles to identify a number of oestrogen regulated genes, in addition to a number of genes differentially expressed in long-term oestrogen deprived cells compared to cells which had been deprived of oestrogen for just? days. Comparison of expression profiles for oestrogen maintained and oestrogen deprived cells following long-term exposure to fulvestrant revealed large alterations in a number of gene expression levels, particularly in the oestrogen maintained cells. Adrenomedullin may have a role in tumour survival and angiogenesis and consistent upregulation of adrenomedulin mRNA was observed during progression to oestrogen insensitivity in duplicate microarray experiments. Real-time RTPCR was able to confirm the increase in mRNA levels in long-term oestrogen deprived cells. Immunofluorescent staining using a monoclonal antibody specific for adrenomedullin showed an increase in the amount of protein in long-term oestrogen deprived cells. Following short and long-term treatment with tamoxifen and fulvestrant the abundance of adrenomedullin rnRNA was increased in oestrogen maintained cells but not in the long-term oestrogen deprived cells. Real time RT-PCR analysis of the GAiA family of transcription factors revealed a reciprocal relationship between GATA3 and GATA6 in ER positive cells and ER negative cells where GATA6 showed highest expression in the ER negative cells and GATA3 was highly expressed in the ER positive cells. Changes were observed in levels of all six of the GATA factors following long-term oestrogen deprivation indicating a functional role for these transcription factors in progression to endocrine resistance. Many potential targets have been identified by the use of microarrays but further validation of cell lines and tumour samples is required to examine the importance of these as possible markers of endocrine resistance in breast tumours.

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Boone, Carleigh. "Endocrine and Contralateral Muscle Responses to Short-term Unilateral Resistance Training." Master's thesis, University of Central Florida, 2014. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6248.

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PURPOSE: The purpose of this study was to examine the effects of short-term lower body unilateral resistance training on hormonal, muscle morphological, and performance measures in young men. METHODS: Seventeen healthy, untrained young men (Age: 22.8 ± 3.7 y; BMI: 26.5 ± 4.9 kg/m2) were randomly assigned to one of two groups (UT: 22.9 ± 4.6 y, 25.3 ± 4.2 kg/m2; CON: 24.0 ± 4.6 y, 27.7 ± 5.1 kg/m2). Resistance training consisted of 4 weeks of unilateral lower body and bilateral upper body exercises on 3 days per week. Each training session entailed unilateral countermovement jumps (3 ± 8), unilateral leg press (LP), bilateral chest press (CP), unilateral leg extension (LE), and bilateral low row (LR). Strength exercises were performed for 3 sets of 8-10 repetitions; lower body exercises were performed with the dominant leg only. Muscle thickness (MT), pennation angle (PA), cross-sectional area (CSA), and echo-intensity (EI) of the vastus lateralis (VL) and rectus femoris (RF) muscles of both legs was assessed via ultrasound. Fascicle length (FL) was calculated as [MT / sin(PA)]. Maximal dynamic unilateral LP and LE strength was assessed during one-repetition maximum (1RM) testing; CP and LR 1RM strength was estimated as [repetition weight/(1.0278-0.0278)(reps)]. Maximal isometric knee extensor strength was isolaterally assessed via maximal voluntary contraction (MVC) testing. Mean and peak power output (Watts) was quantified during unilateral countermovement jumps via accelerometry. Fasting concentrations of total testosterone and growth hormone were obtained at baseline (PRE), immediately post (IP), 30-minutes post (30P), and 60-minutes post (60P) during both testing exercise sessions (Pre and Post). Following the 4-week intervention, all participants' maximal dynamic and isometric strength, mean and peak power output, muscle morphology, and hormonal responses were reassessed. Performance, ultrasound, and area under the curve data were analyzed using ANCOVA to observe between-group comparisons while controlling for baseline (PRE) values. Endocrine data were analyzed using a two-way, mixed-factorial repeated-measures ANOVA. RESULTS: Participants in the UT group experienced significant strength improvements of the trained (28 to 150%) and untrained legs (12 to 160%). Training did not elicit significant improvements in maximal isometric strength or power output of the trained or untrained leg. The trained RF experienced significant increases in CSA and MT. The trained VL experienced a significant increase in CSA. Muscle size of the untrained leg was not significantly augmented. Training did not elicit changes in the acute hormonal response to exercise. CONCLUSIONS: Four weeks of unilateral lower body resistance training using the dominant leg appears sufficient to evoke strength gains of both the ipsilateral and contralateral legs. However, meaningful morphological changes were observed in the trained leg only. Differences in acute hormonal responses to resistance exercise did not appear to explain the observed differences. In addition, unilateral lower body resistance training did not appear to augment the acute endocrine response to an acute bout of resistance exercise. Current findings suggest that the cross-educational strength transfer during the early stage of training is attributable to factors other than changes in muscle morphology and circulating hormones.
M.S.
Masters
Child, Family and Community Sciences
Education and Human Performance
Sport & Exercise Science; Applied Exercise Physiology Track

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Al-Naser, Al Zekri Huda M. "Oligo/amenorrhoea : endocrine profiles, ovarian ultrasound, insulin resistan and anthropometric factors; relationships between insulin resistance and ovarian function." Thesis, University of Glasgow, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360284.

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Sofyali, Emre [Verfasser], and Stefan [Akademischer Betreuer] Wiemann. "GLYATL1 PROMOTES ENDOCRINE THERAPY RESISTANCE IN BREAST CANCER / Emre Sofyali ; Betreuer: Stefan Wiemann." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/1218785217/34.

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Shaw, Lesley E. "The identification of novel genes associated with endocrine resistance in human breast cancer." Thesis, University of Reading, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408985.

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Simões, Joana Filipe Marques. "Regulation of estrogen receptor interactome in acquisition of endocrine resistance in breast cancer." Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14919.

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Mestrado em Bioquímica - Bioquímica Clínica
Breast cancer is a multifactorial disease which remains the main cause of cancer in women. Approximately 70% of all breast cancers diagnosed are estrogen receptor (ER) positive and therefore ERα remains the primary target for endocrine therapies. Currently, tamoxifen (Tam) is the most successful targeted antiestrogen treatment, although the acquisition of Tam resistance have been associated with high rates of Tam relapse and also its ineffectiveness as a first line treatment in breast cancer. The ER interactome has been associated with the modulation of its transcriptional activity and once that the ER expression and activity have been found deregulated in breast cancer, the characterization of the ER interactome might contribute to disclose the mechanisms underlying the Tam resistance. We studied the differences of ERα expression at transcript and protein levels in a spontaneous hormone-dependent mouse mammary tumor (M05), sensitive (M05-S) and resistant (M05-R) to Tam, using qRT-PCR and western blot, respectively. In order to study the ER transcriptional activity, we used qRT-PCR to measure the transcripts of the ERα target genes, complement component 3 (C3) and progesterone receptor (PR). For the same purpose, the immunofluorescence of ERα phosphorylations (p-ERα in S118 and Y537) and the kinases that promote these phosphorylations (p-Erk 1/2 and p-Src-S416, respectively) was evaluated in T47-D cell line grown in medium containing M05-S and M05-R extracellular matrix (ECM) components. The viability assay was used with intention to verify if the effect of M05 ECMs on T47-D cells in response to estrogen (E2), Tam and E2+Tam treatment correlated with levels of p-ERα/activity. Finally, the ERα interacting proteins of M05-S and M05-R tumors were pulled down using BSA-E2 sepharose beads followed by identification with liquid chromatography tandem mass spectrometry (LC-MS/MS). Herein, we show that even though M05-R tumors have lower ERα expression, it is more transcriptionally active denoted by higher transcript levels of C3 and PR. Yet, we observed that M05 ECMs components exert high levels of p-ERα in S118 and Y537 when compared with T47-D cells grown on plastic. At the same time, we noticed that M05-R ECMs trigger E2-independent increased of p-ERα which is in concordance with the high levels of its target genes, reinforcing the increase ERα transcriptional activity. Intriguingly, the p-Erk 1/2 was higher in T47-D cells treated with M05-S ECM, suggesting that p-ERα S118 in M05-R ECM could also be triggered by activation of other growth signalling pathways. On the other hand, the high levels of p-Src-S416 in T47-D cells with M05-R ECM revealed the putative role of p-ERα Y537 in acquisition of Tam resistance and was correlated with the lack of response to E2 and Tam in the viability assays. In contrast, with M05-S ECM the T47-D cells became E2-responsive and their metabolic activity was inhibited by Tam. Regarding MS analysis, 42 proteins were identified in M05-S and 10 in M05-S tumors, generally associated with translation and transcription processes. Our findings allow to conclude that the acquisition of Tam resistance results in the loss of the regulation of ERα, once the proteins which module the transcriptional activity of ERα in the M05-S tumors are not the same proteins which interact with ERα when the tumor becomes resistant to Tam. Possibly this process occurs due to the loss of ERα expression and the high intervariability of M05-R tumors. In summary, acquisition of Tam resistance in the M05 tumors is associated to decreased expression of ERα, increased p-ERα levels and higher transcription of its target genes. This effect is mediated through ECM factors and correlates to loss of ERα regulatory proteins and refractoriness to Tam treatment.
O cancro da mama é uma doença multifactorial que permanece a principal causa de morte por cancro nas mulheres. Aproximadamente 70% de todos os cancros da mama diagnosticados são receptor de estrogénio (ER) positivo e, portanto, o ERα permanece o principal alvo terapêutico da terapia endócrina. Atualmente, o tamoxifeno (Tam) é considerado o agente antiestrogénico com maior sucesso no tratamento, embora a aquisição de resistência ao Tam esteja associada a elevadas taxas de reincidência e também à sua ineficácia como tratamento de primeira linha no cancro da mama. O interactoma do ER está envolvido na modulação da sua atividade transcripcional e uma vez que a expressão e atividade do ER se encontram desreguladas no cancro da mama, a caracterização do interactoma do ER poderá elucidar os mecanismos subjacentes à resistência ao Tam. Assim sendo, foram estudadas as diferenças de expressão do ERα ao nível do transcrito e proteína, num modelo animal de murganho com cancro da mama dependente de estrogénio (E2), sensível (M05-S) e resistente (M05-R) ao Tam, por qRT-PCR e western blot, respetivamente. Para estudar a atividade transcripcional do ER, foi usado qRT-PCR para quantificar o mRNA de genes alvo do ERα, complemento C3 (C3) e receptor de progesterona (PR). Com o mesmo objetivo, a imunofluorescência foi utilizada para a identificação de fosforilações do ERα (p-ERα no resíduo S118 e Y537) e das cinases que promovem essas fosforilações (p-Erk 1/2 e p-Src-S416, respetivamente), em células T47-D cultivadas em meio contendo componentes da matriz extracelular (MEC) dos tumores M05-S e M05-R. O ensaio de viabilidade foi utilizado com o objetivo de verificar os efeitos da MEC dos tumores M05 na resposta das células T47-D ao tratamento com E2, Tam e E2+Tam e de correlacionar com os níveis de p-ERα. Finalmente, os interactomas do ERα dos tumores M05-S e M05-R foram isolados a partir de BSA-E2 ligado a esferas de sepharose seguida da sua identificação por cromatografia líquida acoplada à espectrometria de massa tandem (LC-MS/MS). Foi encontrado que apesar dos tumores M05-R expressarem menos ERα estão mais transcripcionalmente ativos, observado pelo maior nível de mRNA do C3 e PR. Foi observado ainda que os componentes da MEC dos tumores M05 promovem altos níveis de fosforilação do ERα (p-ERα) no resíduo S118 e Y537 quando comparado com as células T47-D cultivadas no plástico. Do mesmo modo, verificámos que a MEC dos tumores M05-R desencadeia a p-ERα independentemente da ação do E2 o que é concordante com os altos níveis dos seus genes alvo, confirmando o aumento da atividade transcripcional do ERα. Os altos níveis de p-Erk 1/2 nas células T47-D tratadas com MEC de tumores M05-S sugerem que a p-ERα S118 nas células T47-D tratadas com MEC dos tumores M05-R pode ser desencadeada pela ativação de outras vias de crescimento celular. Por outro lado, os níveis de p-Src-S416 nas células T47-D com MEC dos tumores M05-R revelam um potencial mecanismo de indução de p-ERα Y537 na aquisição da resistência ao Tam, também provado pela inalteração da atividade metabólica/viabilidade das células T47-D à estimulação com E2 e Tam. Contrariamente, com a MEC dos tumors M05-S, as células T47-D tornam-se sensíveis ao E2 e a sua atividade metabólica é inibida pelo Tam. Em relação à análise MS, foram identificadas 42 proteínas nos tumores M05-S e apenas 10 proteínas nos tumores M05-R, que se encontram associadas a processos de transcrição e tradução. Os nossos resultados permitem concluir que a aquisição da resistência ao Tam resulta na perda de regulação do ERα, uma vez que as proteínas moduladoras da atividade do ERα nos tumores M05-S não são as mesmas proteínas que interagem com os tumores M05 que se tornam resistentes ao Tam. Possivelmente devido à perda de expressão do ERα e à elevada intervariabilididade dos tumores M05-R. Em resumo, a aquisição da resistência ao Tam nos tumores M05 está associada à diminuição da expressão de ERα, aumento dos níveis de p-ERα e maior transcrição dos seus genes-alvo. Este efeito é mediado por fatores da MEC e correlaciona-se com a perda de proteínas reguladoras do ERα e resistência ao tratamento com Tam.

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16

Chae, Sungwon. "Acute Endocrine Responses to Rest Redistribution with Heavier Loads in Resistance-Trained Men." Thesis, University of North Texas, 2020. https://digital.library.unt.edu/ark:/67531/metadc1707275/.

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The purpose of this study was to investigate endocrine responses to redistribution with heavier loads (RR+L) during back squat (BS) exercise in resistance-trained men. Ten men (mean±SE; 23±2 years, 175.6±2.0 cm, 78.0±3.4 kg, 4±1 training years) were assigned using randomization to either RR+L (4 sets of (2×5 repetitions) of BS with 30 s intra-set and 90 s inter-set rest using 75% of their 1RM) or traditional sets (TS; 4 sets of 10 repetitions of BS with 120 s inter-set rest using 70% of their 1RM). Fasted blood samples were collected pre-exercise (PRE), immediately post-exercise (IP), and 5 (+5), 15 (+15), and 30 (+30) minutes post-exercise to analyze the concentrations of testosterone (T), growth hormone (GH), cortisol (C), and blood lactate (BL). Two-way ANOVAs with repeated measures were used (p≤0.05). A main effect of condition (p=0.023) was observed for BL (RR+L; 5.9±0.5 vs TS; 6.7±0.4 mmol/L). A main effect of time point (p≤0.001) was observed for T, GH, C, and BL. T was greater at IP (8.8±1.1), +5 (9.0±1.1), +15 (8.5±1.0), and +30 (8.0±1.0) than PRE (7.1±0.8 ng/mL). GH was greater at IP (58.3±12.7), +5 (62.8±12.7), +15 (67.9±13.3), and +30 (52.8±11.2) than PRE (3.6±1.6 µIU/mL). C was greater at +15 (25.5±2.9) and +30 (25.6±2.7) than PRE (20.0±2.7 µg/dL). BL was greater at IP (8.6±0.6), +5 (8.2±0.6), +15 (7.4±0.5), and +30 (5.8±0.5) than PRE (1.4±0.2 mmol/L). RR+L resulted in lower BL but no differences in T, GH, and C responses compared to TS. Thus, practitioners may incorporate RR+L without affecting endocrine responses.

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Ray, Swagat. "Growth Factor Pathways in Development of Endocrine Resistance in Human Breast Cancer Cells." Thesis, University of Reading, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520093.

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18

Arthur, Laura Margaret. "Tumour evolution over time : treatment and progression : exploring the molecular heterogeneity of oestrogen receptor positive breast cancer." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/29581.

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Introduction Recent advances in microarray technology have allowed more understanding of the complex molecular biology of breast cancer. The traditional prognostic information afforded by hormone receptor status and pathology variables is being supplemented and superseded by gene signatures predictive of risk of recurrence and response to treatments. Approximately 75% of breast cancers are oestrogen receptor positive (ER+) and can be treated by drugs that block oestrogen production such as letrozole. However not all ER+ tumours respond and even those that initially respond can develop resistance. Treating patients with neoadjuvant letrozole affords a unique opportunity to sample the same tumour in vivo at different time points reducing any potential inter-patient and inter-tumour variability. The molecular effects of drugs can be assessed long before clinical outcome is apparent. Underlying genetic differences or characteristics of the patient, tumour or sample may affect the molecular response to treatment. This project set out to use sequential patient-matched samples to evaluate molecular changes in breast tumours in the presence or absence of endocrine treatment in different subtypes, defined by histology or mutation status and to assess molecular variation between primary tumour and nodal metastasis. Methods RNA was extracted and processed to generate whole transcriptome Illumina Beadarray gene expression data from four unique cohorts of patients. Clinical data on treatments, recurrence and survival was collected from medical records. The first cohort compared 25 breast cancer patients with matched samples at diagnosis and at surgery, 14-35 (median 23) days later, with no intervening treatment; with 36 patients treated with neoadjuvant letrozole. A PCR assay to detect 8 known PIK3CA mutations and assessment of PTEN status was performed at both the primary and secondary event in a second cohort of 120 patients with endocrine treated disease who relapsed with either recurrence, lymph node metastases, a new second primary or progression of disease on primary endocrine therapy. The third cohort compared the molecular response to neoadjuvant letrozole in 14 patients with invasive lobular cancer (ILC) and 14 patients with invasive ductal cancer (IDC). A fourth cohort of women with node positive disease at diagnosis were assessed for variations in gene expression profiles between primary tumour and synchronous metastatic axillary lymph nodes (68 samples from 31 patients). Results The genomic profile of the no intervening treatment cohort did not differ significantly. Some changes in inflammatory genes were evident. This reassures us that changes seen during treatment are truly due to drug effect. This validates the use of a second biopsy to explore prediction of response. PIK3CA mutation status is maintained in the majority of patients with endocrine resistant disease and changed in only 15.7%. Where there was a change in PIK3CA this was significantly more likely to be a second primary breast cancer rather than a recurrence or progression of the primary cancer. PTEN status was also maintained in most patients. This does not support the theory that acquisition of a PIK3CA mutation is responsible for developing endocrine resistance. Novel PI3K inhibitor drugs may still be suitable in endocrine-resistant disease if activation of the pathway develops by other mechanisms. Consistent with previous studies, significant molecular differences were observed between ILC and IDC pre-treatment. Over half of these molecular differences were maintained after 3 months of letrozole. However, changes over time in individual tumours in response to letrozole were highly consistent in both ILC and IDC. When comparing primary with synchronous metastatic nodes only 39% of tumours clustered together with their matched primary or node. The molecular subtype of the node was often a poorer prognosis than the primary. There were also differences in subtype between nodes in a small cohort of patients with 2 involved nodes. Conclusions We have demonstrated that neoadjuvant window studies are a valid model for assessment of drug effects and evaluated differences in histology and mutation status. Endocrine resistance in breast cancer is rarely related to acquisition of PIK3CA mutations. Synchronous lymph node metastases can differ greatly from their matched primary. These findings are highly relevant when considering prescribing (neo)/adjuvant therapy and have significantly improved our understanding of breast cancer as we strive towards personalised medicine.

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Cerqueira, Vera. "Role of intracellular signalling pathways in conferring resistance to endocrine therapies in breast cancer." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4511.

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Breast cancer is the most prevalent form of cancer in women and accounts for 519,000 annual deaths (WHO Statistics). It has long been established that oestrogen (E2) stimulates tumour growth of oestrogen receptor (ER) positive breast cancer and is involved in the pathogenesis of the disease. Consequently, therapeutic approaches targeting the ER were developed. The use of endocrine therapy is an integral component in treating breast cancer however resistance to such drugs is a major limitation. Unfortunately, even initially responding tumours eventually develop resistance - acquired resistance. The aim of this study was to determine which intracellular pathways may be important in conferring acquired endocrine resistance. In order to do so, a three-stage MCF-7 cell model emulating the clinical development of acquired endocrine was used. MCF-7/LCC1 (LCC1) and MCF-7/LCC9 (LCC9) cells lines were derived from the oestrogen dependent and antioestrogen sensitive MCF-7 cell line. LCC1 cells remain responsive to endocrine therapies but their growth is not dependent on oestrogenic stimulus. LCC9 cells, on the other hand are fully resistant to endocrine therapies and completely oestrogen independent. A number of different cell membrane receptors and intracellular pathways have been implicated in endocrine resistance including HER receptor family, PI3K/Akt & MEK/ERK pathways. These pathways are of particular interest since they are able to activate ER in the absence of oestrogenic stimulus. It is likely that several pathways may be important in conferring resistance to endocrine therapies therefore the experiments in this study focussed on the transcriptional regulation of HER receptors, the activation of the Akt pathway and its implication to basic cellular processes. Following E2 treatment (48h), HER2/3/4 mRNA and protein levels were reduced in MCF- 7 and LCC1 but not in the endocrine-resistant LCC9 cell line as measured by QRT-PCR and Western blotting. The anti-estrogen fulvestrant (ICI 182,780) reversed the E2 modulation. A previous study has shown that ER and the HER2 promoter compete for limiting amounts of SRC-1 in oestrogen-responsive ZR-75-1 cells, causing HER2 repression after E2 stimulation (Newman et al.,Oncogene, 19, 490-7, 2000). ER RNAi abolished E2 repression of HER2 in MCF-7 and LCC1 cells. Furthermore, LCC9 cells have reduced SRC-1 recruitment to ER (assessed by ChIP) allowing SRC-1 to bind to the HER2 promoter. SRC-1 RNAi reduced HER2 transcription in MCF7 cells in a manner similar to E2 whilst it did not restore E2 repression in LCC9 suggesting that the latter cells have alternative mechanisms regulating HER2 transcription. RNAis against the other two p160 co-activators TIF2 and AIB1 did not restore E2 mediated HER2 repression in LCC9 cells. The importance of redundancy between p160 co-activators was also determined by performing double knockouts. SRC-1/TIF2 and TIF2/AIB1 double siRNAs had little effect on HER2 mRNA levels however SRC-1/AIB1 siRNA restored oestrogen mediated downregulation of HER2 transcription in LCC9 cells. This data indicates that SRC-1 and AIB1 co-activators play a role in the transcriptional regulation of HER receptor particularly in MCF-7 and LCC1 cells. The regulation of this transcriptional mechanism is altered in resistant LCC9 cells but, as evidenced by the double knockouts, p160 coactivators are still able to affect HER expression in these cells. This mechanism was further studied in primary breast cancer tumour material. The importance of the Akt pathway in this cell line model was also investigated as phospho-Akt levels are elevated in LCC1 and LCC9 cells. This in turn was shown to activate mTOR and ER (Ser167 residue phosphorylation) thereby contributing to increased growth and ligand independent activation of the oestrogen receptor respectively. Activation of PI3K and PTEN is unchanged in LCC1 and LCC9 cells suggesting that these proteins are not responsible for elevated Akt phosphorylation. In contrast, these cells do express higher levels of phospho-IGFR due to the high availability of receptor ligands (IGFI & IGFII). This is likely to be, at least partially, responsible for the elevated Akt activation. Moreover, the role of Akt isoforms was also determined as they are known to have different functions. The levels of Akt 2 phosphorylation are higher in endocrine resistant cell lines in comparison to parental MCF-7 cells. Interestingly, the Akt 3 phosphorylation is present in all cell lines whilst Akt 1 phosphorylation is minimal. Nevertheless, Akt RNAi studies reveal that Akt 1 and 2 siRNA dramatically reduce growth in MCF-7, LCC1 and LCC9 cells. These results suggest that Akt 2 phosphorylation may play a part in conferring endocrine resistance but the other isoforms are also important for normal cellular growth. The cell cycle profiles of LCC1 and LCC9 are very similar to MCF-7. Similarly, migration levels are unchanged in endocrine resistant cell lines. However, in the presence of antioestrogenic drugs, apoptosis in LCC1 and LCC9 cells in reduced in comparison to the parental MCF-7 cell line. Furthermore, LCC1 and LCC9 cells have higher invasion rates. The deregulation of HER receptor expression and elevated Akt activation may together confer survival advantage in LCC1 and LCC9 cells whilst also increasing their invading potential.

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20

Skerry, Benjamin James Oliver. "Investigating epigenetic mechanisms of acquired endocrine resistance in an in vitro model of breast cancer." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8106.

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I have investigated epigenetic mechanisms of acquired endocrine-resistance in breast cancer using an in vitro model system based on estrogen-dependent MCF7 cells and their derivatives, LCC1 and LCC9. LCC1 cells, derived from MCF7 after passage in ovariectomised mice and routinely cultured in vitro in the absence of estrogen, exhibit estrogen-independent growth. They retain sensitivity to tamoxifen and fulvestrant. LCC9 cells, derived from LCC1 cells by growing them in increasing concentrations of fulvestrant, are completely estrogen-independent and are resistant to fulvestrant and cross-resistant to tamoxifen. When compared to MCF7 cells, LCC1 cells have marked up-regulation of the estrogen receptor α (ERα) protein that is not concomitant with increased estrogen receptor 1 (ESR1) transcription, suggesting a role for estrogen in controlling the proteasomal degradation of ERα. However, despite being grown in the same estrogen-deprived conditions, LCC9 cells do not have up-regulated ERα levels. As LCC1 cells retain sensitivity to tamoxifen and fulvestrant, these data suggest that LCC1 have developed estrogen-independence through ERα uncoupled from its ligand. However, LCC9 cells appear to have developed an alternative mechanism which is not dependent on ERα, presumably explaining their resistance to fulvestrant. I have studied global gene expression changes in the presence and absence of estrogen in these cell lines, using oligonucleotide microarrays, and correlated these data with global DNA methylation data derived from methylation arrays, which interrogate the methylation status of approximately 27,000 CpG dinucleotides in the genome. The analysis led to the discovery of more than 5,000 genes that were potentially either up-regulated or down-regulated by estrogen in MCF7 cells, either directly or indirectly. The transcriptional response to estrogen was generally muted in LCC1 and LCC9 compared with MCF7, but was not completely absent. I used various methods based on differential gene expression to parse the data, including gene ontology analysis, aiming to select genes for further mechanistic study. However, none of these methods led to the conclusive identification of a specific gene (or set of genes) that might have accounted for the physiological differences between the cell lines. In one strategy, I reasoned that, as the endocrine-resistant cells had lost their estrogen-dependence, genes involved might be regulated in an estrogen-dependent manner in MCF7 cells, without exhibiting misregulation in LCC9. This led to the identification of DUSP1 as a candidate gene, which was taken forward for mechanistic study because of its potential role in regulating ERα expression. However, when over-expressing DUSP1 in LCC9 cells, I could not demonstrate any effect on ERα levels. The final approach taken was to identify genes that might have been epigenetically deregulated, being both estrogen-regulated and deregulated in association with aberrant DNA methylation in the estrogen-independent cell lines. Surprisingly, given the phenotypic differences between the cell lines, only a very few genes were significantly methylated between cell lines. Of those that were differentially methylated between MCF7 cells and LCC1/9, only three exhibited the expected inverse correlation between methylation and expression. Of these, the gene CYBA was selected for further investigation. CYBA is a critical component of the NAPDH oxidase complex which is involved in generating oxygen free-radicals. My work suggests CYBA expression is estrogen-dependent, and that chronic estrogen deprivation leads to the epigenetic inactivation of CYBA in breast cancer cells. I speculate that the epigenetic suppression of CYBA may protect cells from the oxidant damage that results from estrogen deprivation and may be part of the mechanism that leads to acquired endocrine-resistance in previously sensitive cells.

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21

Ek, Ingvar. "Polycystic ovary syndrome : a study of adipocyte lipolysis in relation to endocrine and metabolic status /." Stockholm, 2003. http://diss.kib.ki.se/2003/91-7349-562-x/.

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Rautio, K. (Katriina). "Effects of insulin-lowering drugs in PCOS: endocrine, metabolic and inflammatory aspects." Doctoral thesis, University of Oulu, 2006. http://urn.fi/urn:isbn:951428268X.

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Abstract Most women with polycystic ovary syndrome (PCOS) exhibit features of metabolic syndrome, including insulin resistance, abdominal obesity, dyslipidaemia, glucose intolerance and low-grade chronic inflammation, reflected in elevated levels of serum C-reactive protein (CRP), placing these women at increased risk of cardiovascular disease and type 2 diabetes (type 2 DM). The aim of this study was to investigate the effects of two well-known insulin-lowering drugs used in the treatment of type 2 DM, metformin and rosiglitazone, on traditional cardiovascular risk factors and inflammation in women with PCOS. In addition, the impact of rosiglitazone was evaluated as regards clinical, endocrine and metabolic aspects of PCOS. Six-months of metformin treatment in women with PCOS had beneficial effects on levels of CRP, lipid profile and blood pressure, expressed as increased levels of high-density lipoprotein cholesterol (HDL-C), and decreased levels of triglycerides (TGs), decreased ratio of total cholesterol/HDL-C, decreased levels of CRP, and decreased systolic and diastolic blood pressures. Four-month treatment with rosiglitazone in a randomised, double-blind, placebo-controlled study in overweight women with PCOS resulted in significant improvements in menstrual cyclicity, hyperandrogenism, insulin resistance and hyperinsulinaemia. In addition, rosiglitazone decreased levels of markers of low-grade inflammation, CRP and white blood cell (WBC) count, and the liver function marker alanine aminotransferase (ALAT), while having neutral effects on levels of lipids, and blood pressure. In conclusion, metformin treatment, in accordance with the known beneficial metabolic effects of this drug, could be useful in the prevention of cardiovascular complications in women with PCOS. Rosiglitazone represents an alternative treatment for overweight anovulatory women with PCOS. It could be useful in the prevention of type 2 DM in overweight women with PCOS and for those suffering from possible side-effects related to metformin treatment. In addition, alleviation of inflammation and improvement of liver function during rosiglitazone treatment may indicate decreased future risks of cardiovascular diseases and non-alcoholic fatty liver disease (NAFLD).

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23

Morgan, Liam David. "Elevated Src kinase activity accompanies endocrine-resistance in breast cancer and promotes an aggressive cell phenotype." Thesis, Cardiff University, 2007. http://orca.cf.ac.uk/55686/.

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Despite the effectiveness of tamoxifen in the treatment of oestrogen-receptor-positive breast cancer, a significant proportion of initially-responsive tumours will develop resistance. Using an in vitro cell-model (Tam-R), our laboratory has previously demonstrated that altered growth-factor signalling contributes to tamoxifen-resistant growth. Furthermore, preliminary studies have revealed that acquired tamoxifen-resistance is also accompanied by an aggressive cell-phenotype. Src plays a key role in the regulation of cellular events such as proliferation, migration and invasion. Given that Src has been implicated in tumour progression and metastasis, the aims of this thesis were to further investigate the aggressive phenotype of tamoxifen-resistant breast cancer cells, together with the role of Src in such behaviour. Characterisation of Tam-R cells revealed that these cells grew in loosely-packed colonies and displayed a more angular appearance, which is characteristic of cells undergoing an EMT-like process. Furthermore, Tam-R cells demonstrated increased growth and a significantly augmented motile and invasive phenotype compared to MCF7wt. Analysis of Src expression in these cell-lines revealed no change in mRNA or protein levels however, a dramatic increase in basal Src activation (phosphorylation at Y419) was observed in Tam-R cells. Inhibition of Src in Tam-R cells using AZM555130 restored cell-cell contacts, decreased cell-matrix attachment and suppressed migration and invasion in a dose-dependent manner. Furthermore, inhibition of Src was accompanied by decreased proliferation and a corresponding reduction in EGFR signalling. Conversely, over-expression of constitutively-active Src in MCF7wt cells resulted in elevated growth-factor signalling and FAK/paxillin activity, and promoted increased cell growth, migration and invasion. Importantly, these cells demonstrated insensitivity to the growth-inhibitory effects of tamoxifen, an effect reversed by co-treatment with AZM555130. Together, these data suggest that Src plays a pivotal role in mediating the aggressive phenotype of tamoxifen-resistant breast cancer cells in vitro, and that targeting Src in such cancers may be of therapeutic advantage.

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24

Bernards, Jake. "An Investigation into Fatigue Management: Effects of Two Different Loading Protocols on Markers of Inflammation and the Endocrine Response." Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/etd/3445.

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The purposes of this dissertation were to 1) determine the effectiveness of the neutrophillymphocyte ratio (NLR) as an athlete monitoring tool in resistance training and 2) determine if repetition maximum or relative intensity loading scheme is superior in managing fatigue through the hormonal, inflammatory, and performances response throughout a 10-week periodized resistance training program. Results from the dissertation give merit to continued research regarding the use of NLR as a monitoring tool to help determine the degree of recovery. Furthermore, results from this dissertation lead to questioning the effectiveness of using a repetition maximum (RM) loading scheme within a periodized training model. Results indicated statistical significant time x group interaction effects for training strain and T:C, statistical main effects for time for NLR, IPF, and IPFa. Under an identical programming model, RM loading subjects experienced a 48.7% increase in training strain over the course of ten weeks. This intensification in training strain likely contributed to the increased negative immune and endocrine response the RM subjects experienced when compared to the relative intensity (RISR) group. When dissecting the individual pre-post performance results, the three largest decreases in static jump height (out of four) participated in the RM loading group. Additionally, only two subjects experienced decreases in their maximal strength (based on isometric mid-thigh pull), both of which participated in the RM loading group. Lastly, it is highly likely that one subject from the RM group was at exceedingly high risk of entering a state overtraining. At a minimum, the subject entered a state of a nonfunctional overreach, based on an increase in cortisol concentrations, NLR, T:C levels, along with decreases in testosterone concentrations and maximal strength performance. When combined, results suggest that using an RM loading scheme and a periodized model may not allow for adequate recovery, especially during phases where recovery is of utmost importance (e.g. a taper).

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Borgoni, Simone [Verfasser], and Stefan [Akademischer Betreuer] Wiemann. "Time-resolved profiling reveals ATF3 as a novel mediator of endocrine resistance in breast cancer / Simone Borgoni ; Betreuer: Stefan Wiemann." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/1224356276/34.

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26

Jehanno, Charly. "Régulation de l'activité de récepteur alpha des oestrogènes (ERα) par l'hypoxie et le facteur MKL1 dans un modèle de cellules cancéreuses mammaires." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1B050/document.

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Les œstrogènes, et en particulier l’œstradiol E2, régulent un nombre considérable de fonctions physiologiques au sein de l’organisme et permettent notamment l’établissement et le maintien des fonctions reproductives chez tous les vertébrés. L’E2 agit localement dans de multiples organes cibles via l’intermédiaire de ses récepteurs : ERα et ERβ. Par son action proliférative contribuant au renouvellement de l’épithélium mammaire, l’E2 ainsi que son récepteur ERα ont été associés au développement pathologique de tumeurs mammaires. Celles-ci sont qualifiées d’hormono-dépendantes car elles répondent pour la majorité d’entre elles à l’utilisation de l’hormonothérapie visant à bloquer leur croissance. Malheureusement, on estime que 30 à 40% des tumeurs mammaires finissent par présenter une résistance aux traitements anti-oestrogéniques, par des mécanismes extrêmement complexes. Les travaux présentés dans ce manuscrit ont pour objectifs de mieux comprendre les mécanismes moléculaires et cellulaires impliqués dans le phénomène d’échappement des cellules tumorales mammaires au contrôle hormonal. Dans le cadre de cette thèse, nous nous sommes intéressés à deux facteurs capables de moduler l’activité d’ERα : l’hypoxie, qui désigne l’appauvrissement en oxygène du microenvironnement cellulaire, et la voie RhoA/MKL1 fréquemment mise en place au cours de la transition épithélio-mésenchymateuse. L’hypoxie est une caractéristique majeure des tumeurs solides, et des études lui suggèrent un rôle dans l’apparition de résistance endocrine. Nous montrons que le stress hypoxique inhibe fortement l’expression d’ERα, principalement au niveau protéique, et qu’il abolit la prolifération et la survie cellulaire induites par l’E2. L’analyse transcriptomique démontre qu’un certain nombre de gènes cibles d’ERα sont également régulés par l’hypoxie, qui peut soit réprimer (CXCL12…) ou bien augmenter leur expression (AREG…). Par ailleurs, l’analyse du cistrome d’ERα démontre une perte massive du nombre d’ERBSs (Estrogen Receptor Binding Site) par l’hypoxie, mais également une apparition d’ERBSs hypoxie-spécifiques. Nos résultats suggèrent que le fort recouvrement de régulation entre ERα et l’hypoxie puisse moduler l’efficacité des thérapies antihormonales. Enfin, l’équipe a démontré que l’activation de la voie RhoA/MKL1 provoque une forte inhibition de la fonction AF1 d’ERα. Afin de mieux appréhender les effets de cette voie de signalisation sur l’activité d’ERα, une lignée cellulaire MCF7 exprimant stablement un mutant constitutivement actif du facteur MKL1 a été générée. Nous montrons que son expression modifie profondément le contexte cellulaire en provoquant le basculement d’un phénotype luminal vers un phénotype basal-like. L’analyse transcriptomique de la réponse à l’E2 montre que le changement d’orientation cellulaire induit par MKL1 abolit toute régulation transcriptionnelle des gènes cibles d’ERα. Ce changement d’orientation cellulaire s’accompagne d’une reprogrammation massive du cistrome d’ERα avec une perte importante de ses sites de fixation à la chromatine, mais également de façon inattendue, un enrichissement en nouveaux ERBSs. Enfin, nous montrons une forte augmentation des interactions « non-génomiques » d’ERα avec des partenaires cytoplasmiques tels que PI3K, MSK1 et Src. Ces données suggèrent que dans des cellules agressives de type mésenchymal exprimant ERα, l’activité du récepteur repose majoritairement sur son action « non-génomique ». De façon intéressante, l’utilisation de l’anti-œstrogène pur ICI 182 780 n’a aucun effet inhibiteur sur ces interactions, pour lesquelles un rôle fonctionnel reste à établir
Estrogens, and in particular estradiol E2, regulate a considerable number of physiological functions in the body and allow the establishment and maintenance of reproductive functions in all vertebrates. E2 acts locally in multiple target organs via its receptors: ERα and ERβ. By its proliferative action contributing to the renewal of the mammary epithelium, E2 as well as its ERα receptor have been associated with the pathological development of mammary tumors. These are qualified as hormone-dependent because they, for the majority of them, respond to the use of hormone therapy to block their growth. Unfortunately, it is estimated that 30-40% of mammary tumors end up with resistance to anti-estrogen treatments, through extremely complex mechanisms. The work presented in this manuscript aims to better understand the molecular and cellular mechanisms involved in the escape of mammary tumor cells to hormonal control. In this thesis, we looked at two factors that can modulate the ERα activity: hypoxia, which refers to oxygen depletion in the cellular microenvironment, and the RhoA/MKL1 pathway that is frequently activated during the epithelial-mesenchymal transition. Hypoxia is a major feature of solid tumors, and studies suggest a role in the development of endocrine resistance in breast cancer. We show that hypoxic stress strongly inhibits the expression of ERα, mainly at the protein level, and that it abolishes E2-induced cell proliferation and survival. Transcriptomic analysis shows that a certain number of ERα target genes are also regulated by hypoxia, which can either repress (CXCL12) or increase their expression (AREG ...). Moreover, the analysis of the ERα cistrome demonstrates a massive loss of the number of ERBSs (Estrogen Receptor Binding Site) by hypoxia, but also an appearance of hypoxia-specific ERBSs. Our results suggest that the strong regulatory overlap between ERα and hypoxia may modulate the efficacy of anti-hormonal therapies. Finally, the team demonstrated that the activation of the RhoA/MKL1 pathway causes a strong inhibition of the ERα AF1 function. In order to better understand the effects of this signaling pathway on ERα activity, an MCF7 cell line stably expressing a constitutively active mutant of the MKL1 factor was generated. We show that its expression profoundly modifies the cellular context by causing the switch from a luminal phenotype to a basal-like phenotype. The transcriptomic analysis of the E2 response shows that the MKL1 induced change in cell fate abolishes any transcriptional regulation of ERα target genes. This change in cellular orientation is accompanied by massive reprogramming of the ERα cistrome with a significant loss of its chromatin binding sites, but also unexpectedly, an enrichment of new ERBSs. Finally, we show a strong increase of "non-genomic" ERα interactions with cytoplasmic partners such as PI3K, MSK1 and Src. These data suggest that in aggressive mesenchymal cells expressing ERα, the receptor activity is mainly based on its "non-genomic" action. Interestingly, the use of pure anti-estrogen ICI 182 780 has no inhibitory effect on these interactions, for which a functional role remains to be established

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Cottu, Paul-Henri. "Caractérisation moléculaire de la résistance à l’hormonothérapie et au ciblage de la voie PI3K/mTOR dans des modèles murins de cancers du sein luminaux." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS114/document.

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Les cancers du sein luminaux, exprimant le récepteur aux œstrogènes (RE) représentent 65-75% des cancers du sein soit environ 35.000 nouvelles patientes par an en France. Les référentiels thérapeutiques en vigueur recommandent une prescription systématique d’hormonothérapie au stade précoce, et quasiment constante au stade avancé. Néanmoins, il est admis que plus de 20% des patientes au stade précoce, et la quasi-totalité au stade avancé, vont échapper au traitement endocrinien, rendant impératif le développement de modèles précliniques permettant d’étudier les mécanismes d’hormonorésistance. Dans un contexte de modèles cellulaires anciens et très imparfaits (MCF7, T47D), et de quasi absence de modèles murins pertinents, nous avons choisi de développer des modèles murins dérivés de tumeurs fraîches, dits PDX (patient derived xenografts). Nous avons montré que ces modèles, difficiles à obtenir, récapitulaient avec une grande fidélité les caractéristiques morphologiques et biologiques des tumeurs d’origine. Les PDX se distinguent également par une grande stabilité de ces caractéristiques lors des passages successifs, les rendant utilisables au long cours. Nous avons également évalué les modèles obtenus pour leur profil de sensibilité à diverses modalités de traitement hormonal.Dans une seconde étape, nous avons développé des modèles résistants à partir des PDX précédemment obtenues. Quatre modèles ont pu être obtenus, qui nous ont permis d’avoir à disposition des modèles rendant compte de situations cliniques variées. Ces 4 modèles ont fait l’objet d’analyses biologiques extensives visant à identifier les caractéristiques moléculaires potentiellement associées à telle modalité de résistance : nos données suggèrent fortement qu’il y a autant de mécanismes de résistance que de situations, rendant illusoire une définition biologique unifiée de l’hormonorésistance. La reprogrammation fonctionnelle du RE semble être au centre de ces mécanismes.La voie PI3K/mTOR est une des plus fréquemment associée à l’hormonorésistance. De manière originale, nous avons mis en évidence que cette voie était activée aussi bien dans les modèles sensibles que dans les modèles résistants. La troisième étape a consisté à évaluer l’efficacité de l’everolimus, agent ciblant mTORC1. Nous avons pu montrer que l’everolimus était hautement actif dans toutes les situations considérées, sans argument pour une synergie entre everolimus et tamoxifène ou exemestane. En revanche, il existe une nette tendance à la synergie avec le fulvestrant, inhibiteur hautement spécifique du RE entraînant sa dégradation, et faisant suggérer des interactions avec la voie non génomique du RE.Nous testons actuellement des inhibiteurs spécifiques de la PI3KCA grâce à diverses collaborations industrielles qui permettront également de mener des analyses génomiques approfondies. De multiples projets académiques sont en cours
Luminal breast cancer (ER+, HER2 negative) accounts for 65-75% of all breast carcinomas. Current guidelines strongly recommend endocrine treatment at both the early and advanced stages. However, more than 20% of early stage patients, and all advanced patients will eventually develop endocrine resistance.As most preclinical models (MCF7, T47D) do not recapitulate tumor biology, we have chosen to develop murine models derived from fresh tumors, hence called patient derived xenografts (PDX). We show that these models, although difficult to generate, faithfully exhibit the morphological and biological features of their parental counterpart, with high long term stability. These models have also been evaluated for their sensitivity to various endocrine treatments.In the next step, we developed from these initially endocrine sensitive models new tumors rendered resistant to endocrine therapies. We show that there is no unique biological pattern associated with endocrine resistance, although ER functional reprogramming appears to be critical. We also show that PI3K/mTOR pathway activation, may not be always related to endocrine resistance, and suggest that fulvestrant, an ER down regulator, may be highly synergistic with everolimus in specific cases.Several PI3KCA inhibitors are currently being evaluated in this setting

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Pearson, Todd. "The Genetic Basis of Resistance to Transplantation Tolerance Induced by Costimulation Blockade in NOD Mice: a Dissertation." eScholarship@UMMS, 2003. https://escholarship.umassmed.edu/gsbs_diss/16.

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The NOD mouse is a widely studied model of type 1 diabetes. The loss of self-tolerance leading to autoimmune diabetes in NOD mice involves at least 27 genetic loci. Curing type I diabetes in mice and humans by islet transplantation requires overcoming both allorejection and recurrent autoimmunity. This has been achieved with systemic immunosuppression, but tolerance induction would be preferable. In addition to their genetic defects in self-tolerance, NOD mice resist peripheral transplantation tolerance induced by costimulation blockade using donor-specific transfusion and anti-CDl54 antibody. Failure has been attributed to the underlying autoimmunity, assuming that autoimmunity and resistance to transplantation tolerance have a common basis. Hypothesizing that these two abnormalities might be related, we investigated whether they had a common genetic basis. Diabetes-resistant NOD and C57BL/6 stocks congenic for various reciprocally introduced Idd loci were assessed for their ability to be tolerized. Surprisingly, in NOD congenic mice that are almost completely protected from diabetes, costimulation blockade failed to prolong skin allograft survival. In reciprocal C57BL/6 congenic mice with NOD-derived Idd loci, skin allograft survival was readily prolonged by costimulation blockade. Unexpectedly, we observed that (NOD x C57BL/6)F1 mice, which have no diabetes, nonetheless resist induction of tolerance to skin allografts. Further analyses revealed that the F1 mice shared the dendritic cell maturation defects and abnormal CD4+ T cell responses of the NOD but had lost its defects in macrophage maturation and NK cell activity. Finally, using a genome wide scan approach, we have identified four suggestive markers in the mouse genome that control the survival of skin allografts following DST and anti-CD154 mAb therapy. We suggest that mechanisms controlling autoimmunity and transplantation tolerance in NOD mice are not completely overlapping and are potentially distinct, or that the genetic threshold for normalizing the transplantation tolerance defect is higher than that for preventing autoimmune diabetes. We conclude that resistance to allograft tolerance induction in the NOD mouse is not a direct consequence of overt autoimmunity and that autoimmunity and resistance to costimulation blockade-induced transplantation tolerance phenotypes in NOD mice are not under identical genetic control.

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Micallef, Rachel Antonia. "Wnt signalling in endocrine resistant breast cancer." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/41274/.

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Wnt signalling components are reported to be deregulated in breast cancer but the contribution of this pathway in endocrine resistance is less clearly defined. Endocrine resistance is an important clinical challenge affecting up to a quarter of all breast cancer patients and is associated with a poorer clinical prognosis. This project focussed on exploring the role of Wnt signalling in endocrine resistant breast cancer cell models. Wnt pathway elements were deregulated in the acquired tamoxifen resistant cell line (Tam-R) compared to tamoxifen sensitive parental cells (MCF-7), with changes supportive of Wnt signalling activation in this tamoxifen resistant model apparent from Affymetrix HGU-133A gene microarray data and Western blot analysis. In contrast, Wnt signalling appeared to be suppressed based on Affymetrix data for MCF-7 cells treated with oestradiol for 10 days, with equivocal changes in MCF-7 cells treated with tamoxifen for 10 days or a faslodex resistant cell model (Fas-R). Excitingly, Tam-R cells were also more sensitive than MCF-7 cells to pharmacological manipulation of Wnt signalling. While Wnt activation using Wnt3a and LiCl did not affect cell growth or migration, inhibition of Wnt signalling usingIWP2, PNU 74654 and iCRT14 suppressed Tam-R cell growth and migration. There is mounting evidence of cross talk between Wnt and EGFR signalling in breast cancer, and EGFR activity is upregulated in Tam-R cells. The project’s findings tentatively supported cross-talk between the two signalling pathways in this model. Thus, targeting of the Wnt pathway alongside EGFR blockade was superior in suppressing cell growth and migration in Tam-R cells. The effect appeared to be more pronounced when Wnt signalling was inhibited at the nuclear level using iCRT14. Collectively, these data suggest that Wnt signalling may play an important role in tamoxifen resistance where it may offer an opportunity for more effective therapeutic intervention to control relapse and associated tumour aggressiveness.

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Rajalekshmi, Devi Sarika. "Development of Novel anti-estrogens for endocrine resistant Breast Cancer." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/81275.

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ER+ breast cancer raises a significant diagnostic challenge since resistance invariably develops to the current endocrine therapies. 70% of breast cancers are ER+, which results from the overexpression of estrogen receptor. ER mediates strong anti-inflammatory signaling in ER+ tissues. Once activated with estradiol (E2), ER inhibits inflammatory gene expression via protein-protein interactions that block NF-kappa B transcriptional activity. Importantly, NF-kappa B is a primary mediator of resistance in many cancers, including breast cancer. All current endocrine suppressive treatments block this palliative signaling pathway, along with the desired proliferative pathway. Thus, there is a significant unmet clinical need for novel endocrine treatments for breast cancer that can ameliorate patient outcome in resistant populations, be less prone to resistance development, retain anti-inflammatory action, and cause fewer side effects. Following the hypothesis driven approach, the work described here introduces structural analogs of an innovative ligand scaffold, 5,6-bis-(4-hydroxyphenyl)-7-oxabicyclo[2.2.1]hept-5-ene-2-sulfonic acid phenyl ester, termed OBHS, which reduces gene activation through ligand-induced shifts in helices 8 and 11, thereby indirectly modulating helix 12 of ER (hence, indirect antagonists). This new class of ligands with a bicyclic hydrophobic core retains strong anti-inflammatory effects while dialing out the proliferative effects of E2 (similar to Selective Estrogen Receptor Modulators, SERMS), and could potentially replace the current endocrine therapies of breast cancer. In this work, we carried out rational design and syntheses of two series of OBHS analogs, namely OBHS-A (for acetamido derivatives), and OBHS-P (for propargyl derivatives), while we explored a synthetic methodology for a third series of OBHS compounds. Many analogs from the OBHS-A series exhibited high binding affinity. For example, the exo diastereomer of 2.11a, 2.11b, 2.11c, 2.11d, and 2.11e exhibited Relative Binding Affinities (RBAs) of 22.6%, 10.5%, 19.5%, 12.1%, and 14.4%, respectively. As observed before, endo OBHS compounds exhibited lower binding affinities than exo compounds. The RBA values with acetamide, and isobutyramide (i.e. short hydrophobic chains) were very comparable to each other. However, unexpectedly the propionamide compound showed lower binding affinity than butyramide. Nevertheless, we consider OBHS analogs with RBA values greater than 1% (Kd = 20 nM) to be very potent. This data is only the first step in a battery of assays that will be conducted eventually on these compounds. In particular, our emphasis is in ascertaining and improving the NF-kappa B mediated anti-inflammatory property, where these compounds have shown promising activity in conjunction with their anti-proliferative activity.
Master of Science

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McAdler, Marisa M. "The Relationship Between Vitamin D Status of Adult Women and Diet, Sun Exposure, Skin Reflectance, Body Composition, and Insulin Sensitivity." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1090.

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As the prevalence of vitamin D deficiency continues to grow, mounting evidence supporting its link with chronic disease strengthens suggesting vitamin D’s candidacy in the prevention and treatment of multiple disease states and their complications. Dietary guidelines, however, do not take sun exposure into account. The present study sought to explore the impact of sun exposure on vitamin D status (serum 25(OH)D), and identify other significant determinants of serum levels which may have the greatest effects on overall health. Participants (n = 34) were pre-menopausal women aged 18 to 50 years (mean age 39 ± 6 years), who had their blood drawn at a local pathology lab and a follow-up appointment at a health assessment lab for the collection of other measurements. Mean serum 25(OH)D level was 64 ± 18 nmol/L, and mean dietary vitamin D intake was approximately 327 ± 229 IU/day. Although 82% of participants were below the RDA guidelines (600 IU/day for females ages 9-50 years) for dietary vitamin D intake, only 32% had serum 25(OH)D levels < 50 nmol/L (the recommended level of sufficiency for bone health) reflecting deficiency. While serum 25(OH)D levels were significantly correlated to dietary vitamin D intake (r = 0.42, p = 0.0139), it is reasonable to assume that participants obtained adequate vitamin D from sun exposure. Fasting serum insulin levels were significantly, positively correlated with BMI (r = 0.83, p < 0.0001), and sun exposure index (Body Surface Area x Minutes of Direct Sunlight) was significantly, positively correlated with serum 25(OH)D levels (fall weekend SEI: r = 0.47, p = 0.0059; spring weekend SEI: r = 0.43, p = 0.0135; average weekend SEI: r = 0.43, p = 0.013; and average overall SEI: r = 0.39, p = 0.0247). Reported sun exposure appeared to be least during winter weekdays and the most during summer weekends. Regression analysis was used to determine the strongest predictors of serum 25(OH)D levels, which were found to be sun exposure, dietary vitamin D intake, skin reflectance, age, BMI, and ethnicity (R2 = 0.58 , p = 0.0031), demonstrating that simple questionnaires, such as those employed in this study, can help to predict serum 25(OH)D status and thus be considered in the future treatment of vitamin D deficiency.

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Bryan, R. A. "The role of androgen receptor signalling in endocrine resistant breast cancer." Thesis, University of Essex, 2018. http://repository.essex.ac.uk/22355/.

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Breast cancer (BCa) is the most prevalent cancer among women in the UK. The majority of BCas are endocrine sensitive and develop through the action of oestrogens, facilitated through the transcription factor Oestrogen Receptor alpha (ERα). Treatment for these patients usually involves endocrine therapies (Aromatase Inhibitors and antioestrogens), which are successful in many patients, but therapy resistance represents a major clinical issue. The Androgen Receptor (AR) is a transcription factor that is more highly expressed than ERα in BCa, and mediates the functions of androgens. In early forms of ERα-positive disease, AR is a positive indicator of prognostic outcome and suppresses ERα signalling. However, in ERα-negative disease AR has been demonstrated to drive cancer progression and recent evidence has suggested that AR can drive endocrine resistance. Reporter assays, gene expression analysis and Chromatin Immunoprecipitation assays demonstrated that AR and ERα inhibit each other’s activity and that antioestrogens can reverse this inhibition, resulting in an active AR. Importantly, long term colony formation assays demonstrated that androgen could induce anti-oestrogen resistant growth, but anti-androgens prevented this from developing. Co-treatment of tumours with anti-oestrogens and anti-androgens could therefore be a viable option to block this mechanism of resistance. Cell line models of endocrine resistant disease were used to investigate AR signalling in therapy resistance. The results demonstrated that AR levels were enhanced in several lines and that all cell lines were sensitive to androgen for growth. Importantly, anti-androgens could inhibit androgen-induced growth in all models. Anti-androgens could therefore also be a viable option for the treatment of tumours that have become resistant to endocrine therapies. This study therefore furthers our understanding of the role of the AR in BCa progression and suggests that it is a valid therapeutic target to prevent and/or treat endocrine resistant disease.

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Li, Zhuo. "Modulation of IGFBP2 upon aging, obesity and insulin resistance in mice and humans." Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28371/28371.pdf.

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Hagan, G. Nana. "Adipocyte Insulin-Mediated Glucose Transport: The Role of Myosin 1c, and a Method for in vivo Investigation: A Dissertation." eScholarship@UMMS, 2008. https://escholarship.umassmed.edu/gsbs_diss/403.

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The importance of insulin delivery and action is best characterized in Type 2 Diabetes, a disease that is becoming a pandemic both nationally and globally. Obesity is a principal risk factor for Type 2 Diabetes, and adipocyte function abnormalities due to adipose hypertrophy and hyperplasia, have been linked to obesity. Numerous reports suggest that the intracellular and systemic consequences of adipocyte function abnormalities include adipocyte insulin resistance, enhanced production of free fatty acids, and production of inflammatory mediators. A hallmark of adipocyte insulin sensitivity is the stimulation of glucose transporter isoform 4 (GLUT4) trafficking events to promote glucose uptake. In the Type 2 diabetic and insulin resistant states the mechanism behind insulin-stimulated GLUT4 trafficking is compromised. Therefore, understanding the role of factors involved in glucose-uptake in adipose tissue is of great importance. Studies from our laboratory suggest an important role for the unconventional myosin, Myo1c, in promoting insulin-mediated glucose uptake in cultured adipocytes. Our observations suggest that depletion of Myo1c in cultured adipocytes results in a significant reduction in the ability of adipocytes to take up glucose following insulin treatment, suggesting Myo1c is required for insulin-mediated glucose uptake. A plausible mechanism by which Myo1c promotes glucose uptake in adipocytes has been suggested by further work from our laboratory in which expression of fluorescently-tagged Myo1c in cultured adipocytes induces significant membrane ruffling at the cell periphery, insulin-independent GLUT4 translocation to the cell periphery, and accumulation of GLUT4 in membrane ruffling regions. Taken together Myo1c seems to facilitate glucose uptake through remodeling of cortical actin. In the first part of this thesis I, in collaboration with others, uncovered a possible mechanism through which Myo1c regulates adipocyte membrane ruffling. Here we identified a novel protein complex in cultured adipocytes, comprising Myo1c and the mTOR binding partner, Rictor. Interestingly our studies in cultured adipocytes suggest that the Rictor-Myo1c complex is biochemically distinct from the Rictor-mTOR complex of mTORC2. Functionally, only depletion of Rictor but not Myo1c results in decreased Akt phosphorylation at serine 473, but depletion of either Rictor or Myo1c results in compromised cortical actin dynamic events. Furthermore we observed that whereas the overexpression of Myo1c in cultured adipocytes causes remarkable membrane ruffling, Rictor depletion in cells overexpressing Myo1c significantly reduces these ruffling events. Taken together our findings suggest that Myo1c, in conjunction with Rictor, modulates cortical actin remodeling events in cultured adipocytes. These findings have implications for GLUT4 trafficking as GLUT4 has been previously observed to accumulate in Myo1c-induced membrane ruffles prior to fusion with the plasma membrane. During our studies of adipocyte function we noticed that current siRNA electroporation methods present numerous limitations. To silence genes more effectively we employed a lentivirus-mediated shRNA delivery system, and to standardize this technology in cultured adipocytes we targeted Myo1c and MAP4K4. Using this technology we were able to achieve clear advantages over siRNA oligonucleotide electroporation techniques in stability and permanence of gene silencing. Furthermore we showed that the use of lentiviral vectors in cultured adipocytes did not affect insulin signaling or insulin-mediated glucose uptake events. Despite our inability to use lentiviral vectors to achieve gene silencing in mice we were able to achieve adipose tissue-specific gene silencing effects in mice following manipulation of the lentiviral conditional silencing vector, and then crossing resulting founders with aP2-Cre mice. Interestingly however, only founders from the MAP4K4 conditional shRNA vector, but not founders from the Myo1c conditional shRNA vector, showed gene knockdown, possibly due to position-effect variegation. Taken together, findings from these studies are important because they present an alternative means of achieving gene silencing in cultured adipocytes, with numerous advantages not offered by siRNA oligonucleotide electroporation methods. Furthermore, the in vivo, adipose tissue-specific RNAi studies offer a quick, inexpensive, and less technically challenging means of achieving adipose tissue-specific gene ablations relative to traditional gene knockout approaches.

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Sivanandan, Kavitta. "Role of forkhead transcription factors in endocrine sensitive and resistant breast cancer cell lines." Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522211.

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Shi, Xiarong. "Mitochondrial Dysfunction and AKT Isoform-Specific Regulation in 3T3-L1 Adipocytes: A Dissertation." eScholarship@UMMS, 2010. https://escholarship.umassmed.edu/gsbs_diss/505.

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Excess food consumption and/or lack of exercise have dramatically contributed to the prevalence of overweight (BMI≥25) and obesity (BMI≥30) in modern society. The obesity epidemic has been linked to the rise in type 2 diabetes. In recent years, evidence has pointed to a close association between mitochondrial dysfunction in white adipose tissue (WAT) and insulin resistance, a key feature of type 2 diabetes. In order to dissect the cause and effect relationship between WAT mitochondrial dysfunction and insulin resistance, we established an in vitro cell line system to investigate this issue. We artificially introduced mitochondrial dysfunction in 3T3-L1 adipocytes by depleting the mitochondrial transcription factor A (Tfam) during adipogenesis, without changing the overall adipocyte differentiation program. We found that these Tfam-depleted 3T3-L1 adipocytes showed symptoms of insulin resistance, evidenced by impaired insulin stimulated GLUT4 translocation and glucose uptake. This result suggested that mitochondrial dysfunction could be a primary contributor to insulin resistance in fat tissue. However, the exact mechanism underlying this finding remains unclear. As part of a comprehensive understanding of insulin signaling in fat cells, we also investigated the involvement of the endosomal protein WDFY2 in the regulation of Akt isoform-specific effect on glucose uptake. In 3T3-L1 adipocytes, both Akt1 and Akt2 isoforms are expressed, but only Akt2 plays an indispensible role in insulin-stimulated GLUT4 translocation and glucose uptake. Previous studies implied that endosomal proteins may take a part in determining Akt substrate specificity. Here we found that WDFY2 preferentially co-localized with Akt2 and that knockdown of WDFY2 inhibited insulin-stimulated glucose uptake in 3T3-L1 adipocytes, suggesting that endosomes are involved in this regulation. The effect of WDFY2 knockdown on insulin-stimulated glucose uptake worked through the down-regulation of Akt2, but not Akt1, protein level. We concluded that, endosomal protein WDFY2, by preferentially interacting with Akt2, regulates insulin signaling in glucose uptake in 3T3-L1 adipocytes. Our findings may help to develop specific therapeutic interventions for treatment of insulin resistance and type 2 diabetes.

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Vilquin, Paul. "Événements moléculaires associés à la résistance acquise aux anti-aromatases dans le cancer du sein hormono-dépendant : voie de survie PI3K/Akt/mTOR : profils d'expression spécifiques de miRNAs." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10295.

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La résistance aux anti-aromatases (AAs) constitue un obstacle thérapeutique majeur dans le traitement des cancers du sein RE+. Les objectifs de ce travail étaient : (i) de caractériser les événements moléculaires associés à la résistance acquise aux AAs ; (ii) d’identifier de manière globale de nouveaux profils de miRNAs spécifiquement associés à la résistance aux AAs. Notre étude a mis en évidence le rôle central de la voie Akt/mTOR dans la résistance acquise et de novo aux AAs dans des modèles cellulaires, mais également dans des échantillons de patientes ayant récidivé sous anastrozole. La combinaison d’un AA avec le MK-2206, inhibiteur d’Akt ou avec la rapamycine, inhibiteur de mTOR, augmente la sensibilité à l’AA dans les cellules contrôles et est suffisante pour surmonter la résistance et restaurer la sensibilité à l'hormonothérapie dans les cellules résistantes. Notre travail propose également un modèle de résistance acquise aux AAs basé sur la sélection de cellules « cancer-initiating-like » dotées de propriétés d'auto-renouvellement, d’une résistance intrinsèque aux AAs et d’une sensibilité au MK-2206. Notre étude à grande échelle des miRNAs a identifié la voie Akt/mTOR comme une des cibles privilégiées de ces miRNAs. Nous avons identifié et validé trois miRNAs dérégulés capables de moduler le statut d’activation de la voie Akt/mTOR, qui représentent des cibles potentielles. En conclusion, notre projet a mis en évidence de nouvelles voies de signalisations ciblées par ces miRNAs et de nouveaux évènements moléculaires, qui représentent des candidats potentiels dans la résistance aux AAs
Resistance to aromatase inhibitors (AIs) remains a major drawback in the treatment of ER+ breast cancers. Our objectives were (i) to characterize molecular events associated with acquired AI resistance (ii) to capture a global view of the miRNA expression profiles associated with AI resistance. Our results showed the major role of the Akt/mTOR pathway in both de novo and acquired resistance to AI in cellular models and also in breast tumors of patients who relapsed under anastrozole. Combining AI with the Akt inhibitor MK-2206 or with the mTOR inhibitor rapamycin increased sensitivity to this AI in the control cells and was sufficient to overcome resistance and restore sensitivity to endocrine therapy in the resistant cells. Our findings propose a model of AI-acquired resistance based on the selection of cancer-initiating-like cells possessing self-renewing properties, intrinsic resistance to AI and sensitivity to MK-2206. Our large-scale study identified the Akt/mTOR pathway as one of the main targets of the deregulated miRNAs. We identified and validated three miRNAs able to modulate the Akt/mTOR activation status, suggesting these miRNAs as potential targets. To conclude, our project identified new miRNA-targeted signaling pathways and new molecular events, representing strong candidates in the mediation of AI resistance

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Kergoat, Micheline. "Secretion et mode d'action de l'insuline dans un modele de diabete non-insulinodependant chez le rat." Paris 7, 1988. http://www.theses.fr/1988PA077085.

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Britton, David J. "Role of oestrogen receptor phosphorylation in the growth of endocrine-responsive and anti-oestrogen-resistant breast cancer cell lines." Thesis, Cardiff University, 2005. http://orca.cf.ac.uk/54251/.

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EGFR/MAPK signalling has been implicated in mediating tamoxifen-resistant breast cancer cell growth in the clinic and in preclinical models. However, ERa expression and functionality has also been shown to be maintained in this condition. ERa transcriptional activity can be driven, in a tigand-independent manner, via growth factor signalling-mediated phosphorylation of ERa. The aim of mis thesis was to investigate whether growth factor signalling pathways regulate phosphorylation and functionality of ERa in tamoxifen-sensitive (WT) and -resistant (TAM-R) MCF-7 breast cancer cell lines and if so whether mis cross-talk mechanism plays a role in the generation and maintenance of the tamoxifen-resistant phenotype. Western blotting and immunocytochemistry assays revealed increased levels of serine 118 (SI 18), but not serine 167, phosphorylated ERa in TAM-R compared to WT cells. Basal SI 18 ERa phosphorylation was regulated by both EGFR and IGF-IR signalling pathways, via MAPK, in Tam-R cells and by IGF-1 R/phosphatidylinositol 3-kinase signalling in WT cells. ERa transcriptional activity, assayed by oestrogen response element (ERE) activity and pS2 and amphiregulin (AR) mRNA levels, was similarly IGF-1R/EGFR/MAPK-regulated in TAM-R cells, whereas, ERE activity was only IGF-1R-dependent in WT cells. AP-1 and serum response element activity was EGFR/IGF-1R-independent in born cell lines. Recruitment of the co-activators p68 RNA helicase and SRC1 was EGFR/MAPK- and SI 18 phosphorylation-dependent in TAM-R cells indicative of a role for SI 18 phosphorylation in mediating ERa transcriptional activity. The ability of ERa to regulate AR mRNA expression also suggested the existence of a self propagating autocrine growth regulatory loop in TAM-R cells. This was confirmed by the presence of ERa on the AR gene promoter, elevated basal AR mRNA expression, inhibition of EGFR, MAPK and ERa SI 18 phosphorylation by AR neutralising antibodies and growth promotion by AR and inhibition by the selective EGFR tyrosine kinase inhibitor gefitinib and the pure antioestrogen fulvestrant.

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Young, James L. "Innate Immunity in Type 2 Diabetes Pathogenesis: Role of the Lipopolysaccharide Signaling Cascade: A Dissertation." eScholarship@UMMS, 2008. https://escholarship.umassmed.edu/gsbs_diss/400.

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Once seen as a disease of wealthy nations, type 2 diabetes mellitus is now showing unprecedented growth throughout the world, fueling increases in microvascular and macrovascular complications. A compelling and growing body of evidence suggests that glucose intolerance and insulin resistance, hallmarks of the diabetic patient, may be driven by chronic inflammation. In particular, a predominance of visceral fat has been associated with enhanced inflammatory cytokine secretion that may contribute to enhanced risk of diabetes and comorbid cardiovascular disease in these individuals. As a function of its potency and wide environmental and biological distribution, we hypothesized that bacterial lipopolysaccharide (LPS, also known as endotoxin) may promote adipose inflammation and concomitant metabolic dysfunction. Indeed, expression of the LPS receptor CD14 is enhanced on visceral adipocytes of ob/ob mice, paralleling enhanced IL-6 secretion ex vivo. Furthermore, rosiglitazonefed ob/obmice demonstrated a reduction in CD14 that coordinated with diminished IL-6 secretion, suggesting a basis for the touted anti-inflammatory effects of this commonly employed type 2 diabetes medication. Mice deficient in components of the LPS signaling cascade, namely CD14, TLR4, and MyD88, yielded adipocytes with markedly attenuated IL-6 secretion, corroborating the central importance of LPS in adipocyte inflammation and supporting the role of this signaling pathway in depot-specific inflammation. Despite the prominent role of LPS signaling in adipocyte inflammation, CD14-, TLR4-, and MyD88-deficient mice failed to show resistance to diet induced obesity. Surprisingly, cd14-/- and tlr4-/- mice had marked glucose intolerance without alteration in total weight or adipose accumulation. In contrast, myd88-/- mice revealed minor glucose intolerance only with high fat diet challenge at an advanced age despite being overtly obese. In cd14-/- and tlr4-/-, but not myd88-/-, mice, an exaggerated rebound to hypoglycemia was associated with enhanced norepinephrine secretion, which could be abrogated by the adrenergic β-blocker propranolol. The overlay of these mouse models reveals a divergence of phenotypes that demonstrate LPS signaling disruption may lead to glucose intolerance and insulin resistance in part due to enhanced sympathoadrenal tone, uncovering an essential role of innate immunity in physiological stress and its impact upon glucose homeostasis.

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Neto, João Francisco Ribeiro Furtado. "Prevalência da síndrome metabólica em adolescentes de 06 Escolas na Cidade de São Luís/MA Brasil." Universidade do Estado do Rio de Janeiro, 2013. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=6713.

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Na população pediátrica tem aumentado a prevalência da Síndrome Metabólica. No Brasil, poucos estudos foram realizados em relação a sua prevalência, critérios de diagnósticos, principalmente no Norte/Nordeste. Apesar de não termos uma definição oficial para a Síndrome Metabólica em adolescentes, utilizamos critérios da NCEP ATP III modificados que consistiram em: Obesidade Abdominal >= 90 percentil, HDL-colesterol <= 40 mg/dl, Triglicerídeo > = 110 mg/dl, Glicemia em Jejum >= 100 mg/dl, Pressão Arterial >= 90 percentil ajustável para idade e gênero. Participaram deste estudo 468 adolescentes sendo 168 (40,2%) do gênero masculino e 280 (59,8%) do gênero feminino de 06 (seis) escolas públicas e particulares, da cidade de São Luís/MA, durante o ano de 2012. A prevalência da Síndrome Metabólica foi de 12,2% sendo 30 pacientes do gênero masculino e 27 do gênero feminino. Houve uma predominância no gênero masculino e a faixa etária mais acometida foi 16-17 anos, seguido da faixa de 13-14 anos. Em relação aos componentes da Síndrome Metabólica, a Hipertensão Arterial foi o componente dominante (100% dos casos), seguida do HDL-colesterol diminuída (94,7%), obesidade (79%), triglicerídeos (71,9%), proteína C reativa média e alto risco em 28,1% dos casos, e glicemia em jejum alterada não foi encontrada em nenhum caso, porém, evidenciamos HOMA-IR alterado em 75,4% dos casos. Apesar de termos apena 01 referência na literatura brasileira na padronização sobre a medida da circunferência abdominal, foi realizado a sua medida na população estudada e a sua relação com a altura. Utilizamos como ponto de corte >= 0,5 para avaliar a adiposidade visceral nos pacientes estudados com Síndrome Metabólica encontramos relação Circunferência Abdominal e Altura aumentada em 66,7% dos casos. Em relação aos antecedentes mórbidos familiares dos adolescentes portadores de Síndrome Metabólica, a prevalência de obesidade foi de 22,8%, seguido de diabetes e hipertensão arterial em 17,5%, diabetes, hipertensão arterial e obesidade foi de 15,8%.
In the pediatric population is increasing the prevalence of Metabolic Syndrome. In Brazil, few studies have been conducted regarding its prevalence, diagnostic criteria, especially in the North / Northeast. Despite not having an official definition for metabolic syndrome in adolescents, we used the NCEP ATP III criteria modified consisting of Abdominal Obesity > = 90 percentile, HDL-cholesterol <= 40 mg / dl, triglycerides> = 110 mg / dl, Fasting glucose > = 100 mg / dl, blood pressure> = 90 percentile for age and gender. 468 adolescents were evaluated and 168 (40.2%) male and 280 (59.8%) females of six (06) public and private schools in the city of São Luis / MA, during the year 2012. The prevalence of metabolic syndrome was 12.2% with 30 male patients and 27 female. There was a male predominance and the most affected age group was 14-15 years, followed by the range of 16-17 years. Regarding the components of the Metabolic Syndrome, hypertension was the dominant component in all cases, then HDL cholesterol decreased (94.7%), obesity (79%), triglycerides (71.9%), medium and high risk C-reactive protein (28.1%), while hyperglicemia was not found in any case, alterede HOMA-IR was found in 75.4% of cases. It was measured the relationship between waist circumference and height in this population with a cutoff size> = 0.5 in order to assess visceral adiposity. In patients with metabolic syndrome it was found a relation RCA increased in 66.7% of adolescents. Regarding family history of patients with metabolic syndrome the prevalence of obesity was around 22.8%, followed by 17.5% Diabetes Hypertension and 15.8% Diabetes, Hypertension and Obesity.

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Sebastiani, Giorgia. "Repercusiones endocrino-metabólicas del bajo peso al nacer: influencia de la alimentación precoz y del crecimiento post-natal." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/405572.

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INTRODUCCION Según la teoría del “Programming”, la asociación entre bajo peso al nacer para la edad gestacional (PEG), desarrollo de enfermedad coronaria en la edad adulta y síndrome metabólico (SM) caracterizado por resistencia a la insulina y exceso de adiposidad central y visceral, ocurre fundamentalmente en individuos PEG que desarrollan un “catch-up” rápido y exagerado durante los primeros meses de vida postnatal. El tejido adiposo (TA) juega un papel fundamental en el desarrollo del SM: según la teoría de expansibilidad del TA si se excede su máxima capacidad de almacenamiento este se vuelve hipertrófico y disfuncionante produciendo más adipoquinas pro-inflamatoria y menos adiponectina de alto peso molecular (APM). Esto llevaría a lipotoxicidad por acumulo ectópico de lípidos en hígado, musculo y páncreas con consecuente resistencia a la insulina y desarrollo de hígado graso. Además la resistencia a la insulina propia de estos individuos llevaría a alteraciones cardiovasculares ya detectables en edades tempranas. Un desequilibrio en la nutrición postnatal podría alterar todos estos mecanismos de adiposidad por cambios epigenéticos. Se ha descrito que la lactancia materna (LM) tiene un papel protector sobre el riesgo de obesidad. DISEÑO DEL ESTUDIO Y OBJETIVOS Los 5 artículos de esta Tesis forman parte de un estudio longitudinal de duración de 6 años realizado sobre una población de niños PEG comparados con niños de peso adecuado para la edad gestacional (PAEG) nacidos a término de embarazos no complicados. Los objetivos fueron: 1. Determinar en recién nacidos PEG el perfil endocrino-metabólico, la composición corporal y el patrón de adipoquinas. 2. Estudiar los efectos de LM y dos fórmulas artificiales: estándar (LA1) e hipercalórica (LA2) sobre el perfil endocrino-metabólico y la composición corporal durante los primeros 12 meses de vida. 3. Determinar a los 3-6 años de edad: distribución de grasa abdominal, perfil endocrino-metabólico y la intima media arterial (IMT). RESULTADOS • Los niveles de Folistatina fueron más elevados en recién nacidos PEG comparados con AEG (p<0.01). • Al nacer los valores de Pref-1 fueron más altos en PEG que en AEG (p= 0.004). • Comparados con los AEG, los PEG a los 4 meses ganaron más masa magra agravando su déficit de masa grasa (p<0.0005). A los 4 meses los PEG alimentados con LA presentaron valores elevados de IGF-1 (p<0.001) y adiponectina-APM (p<0.005) con respecto a los PEG alimentados con LM. • Entre los 4 y los 12 meses los PEG alimentados con LA2 se caracterizaron por un aumento de masa grasa (p<0.005), y de IGF-1 (p=0.008) y por un descenso de los niveles de adiponectina-APM (p<0.005). • A los 6 años los niños PEG presentaron valores más elevados de cIMT (p<0.0001), aIMT (p<0.01), y de IGF-1 (p<0.05), concentraciones más bajas de adiponectina-APM (p<0.05) y menor sensibilidad a la insulina medida por el índice HOMA-IR (p<0.05). Además presentaron valores aumentados de grasa pre-peritoneal (p<0.001) y hepática (p<0.05). CONCLUSIONES • Los recién nacidos PEG presentan un perfil insulino-sensible y alteración de los mecanismos de adipogénesis fetal con escaso tejido adiposo al nacer. Este perfil insulino-sensible prepara a los niños PEG para el “catch-up”. • A los 4 meses de vida persiste el déficit de TA independientemente de la alimentación recibida. Los PEG alimentados con LA presentan un incremento compensatorio de adiponectina-APM e IGF-1 que llevaría a mayor reclutamiento de adipocitos en condiciones de ingesta hipercalórica. • A los 12 meses los PEG alimentados con LA2 presentan un perfil endocrino-metabólico más desfavorable con patrón de resistencia a la insulina y aumento de masa grasa que produciría hipertrofia y disfunción de los adipocitos con consecuente lipotoxicidad e hipo-adiponectinemia. • Los PEG con cacth-up presentan a los 3-6 años resistencia a la insulina, disfunción endotelial y a los 6 años aparecen los primeros signos de lipotoxicidad.
BACKGROUND AND STUDY DESIGN The “reprogramming” during critical time of fetal life can lead to Metabolic Syndrome (MS). The sequence of born small for gestational age (SGA) and MS characterized by insulin resistance and visceral adiposity is associated to rapid weight gain during the first months of life. The adipose tissue (AT) expandability hypothesis explains the development of insulin resistance. This insulin resistance is relationed with precocious cardiovascular illness. Moreover overnutrition in infancy causes growth acceleration and increases the risk of obesity due to epigenetic mechanisms. Breastfeeding (BF) protects against the development of obesity. Our aim was to assess the endocrine-metabolic profile and body composition in SGA at birth; to study the effects of BF and 2 formula-feeding: standard (FOF1) and enriched (FOF2) during the first 12 months of life; to assess at 3-6 years-old the distribution of abdominal fat, endocrine-metabolic profile and intima media thickness (IMT). We compared these results to appropriate for gestational age population (AGA). RESULTS • Follistatin concentrations were higher en SGA newborn than AGA (p<0.01). • Pref-1 levels were higher in SGA than AGA fetuses (p= 0.004). • 4 months-SGA gained more lean mass, aggravating their low adiposity (p<0.0005). At 4 months the levels of IGF-1 (p<0.001) and adiponectin (p<0.005) were higher in SGA-FOF than AGA-BF infants. • Between 4 and 12 months SGA-FOF2 infants were characterized by increased fat mass (p<0.005), IGF-1 (p=0.008) and fall of adiponectin (p<0.005). • At 6 years-old SGA children had increased cIMT (p<0.0001), aIMT (p<0.01), and IGF-1 (p<0.05), lower adiponectin concentrations (p<0.05) and were less insulin sensitive (p<0.05). SGA had more pre-peritoneal (p<0.001) and hepatic fat (p<0.05). CONCLUSIONS • SGA newborns are insulin sensitive and have lower fat mass than AGA. • At 4 months SGA prioritize the recovery of lean mass not influenced by nutrition. SGA-FOF showed more adiponectin and IGF-1 levels to recruit more adipocytes in overfeeding condition. • At 12 months SGA-FOF2 had unfavorable metabolic profile as jugged by more insulin resistance, increased of fat mass with hypertrophic and dysfunctional adipocytes that lead to lipotoxicity and hypo-adiponectinemia. • SGA children aged 3-6 years were found to have more insulin resistance, endothelial dysfunction and at 6 years the first signs of lipotoxicity.

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De, Nigris Valeria. "The possible link between high glucose-induced PKCβ expression and the appearance of GLP-1 resistance in endothelial cells." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/325682.

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INTRODUCTION. It has been demonstrated that Glucagon-like peptide-1 (GPL-1) has a protective effect on endothelial cells. GLP-1 improves endothelial function in diabetes, however the mechanisms underlying the GLP-1 protective effects have not yet been fully elucidated. Additionally, it has been proposed that GLP-1 could restore high glucose - endoplasmic reticulum (ER) stress induction. Recent evidences claim a resistance of GLP-1 action that has been shown in pancreatic 13-cells of diabetic patients. A proposed mechanism to explain this resistance to the GLP-1 action in diabetes is the activation of PKCI3, induced by hyperglycaemia, which is able to reduce the expression of GLP-1 receptor. AIM. The aim of this thesis project was to decipher if GLP-1 acute treatment is able to counteract chronic high glucose-induced damage in Human umbilical Vein Endothelial cells (HUVECs). METHODS. In this study HUVECs were cultured for 21 days under normal glucose (5mmol/L, NG) or high glucose (25mmol/L glucose, HG) concentrations. GLP-1 and Ruboxistaurin were added alone or in combination, 1 hour before cell harvesting. Analysis of GLP-1 receptor protein levels as well as of gene expression of different ER stress-related genes, proliferation markers, antioxidant cell response-related genes and PKA subunits was performed. ROS production was also measured in HUVECs exposed to mentioned treatments. RESULTS. GLP-1 receptor expression was reduced in HUVECs exposed to chronic high glucose concentrations and it was partially restored after treatment with the chemical PKCI3 specific inhibitor, Ruboxistaurin. GLP-1, added as an acute treatment in endothelial cells, had the capacity to induce the expression of detoxifying enzymes Nrf2 targets, to increase transcript levels of scavenger genes, to attenuate the high glucose-induced PKA subunits expression, ER stress and also the apoptotic phenotype of HUVECs only when high glucose-induced PKCI3 overexpression was reduced by Ruboxistaurin. In the same direction, ROS production induced by high glucose was reduced by GLP-1 in the presence of PKCI3 inhibitor. CONCLUSIONS. This study suggests that PKCI3 increase, induced by high glucose, could have a role in endothelial GLP-1 resistance, reducing GLP-1 receptor levels and disrupting GLP-1 canonical pathway.
INTRODUCCIÓN. Se ha demostrado que el Glucagon-like peptide-1 (GLP-1) tiene un efecto protector sobre las células endoteliales. GLP-1 mejora la función endotelial en la diabetes, sin embargo los mecanismos subyacentes a los efectos protectores de GLP-1 aún no han sido completamente aclarada. Además, se ha propuesto que el GLP-1 podría restaurar la función del retículo endoplasmático (ER), cuyo estés es inducido en condiciones de alta glucosa. Evidencias recientes afirman que existe una resistencia a las propiedades beneficiosas del GLP-1. Esto se ha demostrado en las células beta del páncreas de pacientes diabéticos. Un mecanismo propuesto para explicar esta resistencia a la acción de GLP-1 en la diabetes es la activación de PKCβ, inducida por la hiperglucemia, que se ha visto está involucrada en la reducción de la expresión del receptor del GLP-1 en el endotelio glomerular de modelos animales de diabetes. OBJETIVO. El objetivo de este proyecto de tesis fue descifrar si el tratamiento agudo con GLP-1 puede contrarrestar el daño inducido por condiciones de alta glucosa crónica en las células endoteliales humanas de la vena umbilical (HUVECs) y también corroborar los efectos de dicha molécula en caso de que se inhiba la activación de PKCI3 inducida por las altas concentraciones de glucosa. MÉTODOS. En este estudio las células HUVEC se cultivaron durante 21 días bajo las dos condiciones de glucosa normal (5 mmol/L, NG) o alta glucosa (25 mmol/L, HG). Se añadieron GLP-1 y Ruboxistaurin, el inhibidor específico de PKCI3, solos o en combinación, 1 hora antes de la recolección de células. Se realizó un análisis de los niveles de proteína del receptor del GLP-1, así como de la expresión génica de diferentes relacionados con el estrés del ER, la proliferación, el proceso de apoptosis, y también los genes relacionados con la respuesta antioxidante. La producción de ROS fue además medida en las HUVECs expuestas a los diferentes tratamientos mencionados. RESULTADOS. La expresión del receptor del GLP-1 fue reducida en las HUVECs expuestas a concentraciones de alta glucosa crónica y fue parcialmente restaurada después del tratamiento con el inhibidor específico de PKCI3, Ruboxistaurin. GLP-1, añadido como un tratamiento agudo en las células endoteliales, tuvo la capacidad de inducir la expresión de enzimas desintoxicantes que son dianas de Nrf2, el regulador más importante de la respuesta antioxidante en las células. Además, el GLP-1 aumentó los niveles de transcriptos de los marcadores de estrés de ER inducido por la alta glucosa y los marcadores de proliferación en las HUVECs sólo cuando la sobreexpresión PKCβ inducida por la alta glucosa se redujo en presecia de su inhibidor. En la misma dirección, la producción de ROS inducida por la alta glucosa disminuyó cuando las HUVECs se trataron con GLP-1 en presencia del inhibidor de PKCI3. CONCLUSIONES. Este estudio sugiere que el aumento de PKCβ, inducido por la alta glucosa, podría tener un papel en la resistencia a las acciones protectoras del GLP-1 a nivel endotelial, reduciendo los niveles del receptor del GLP-1 e interrumpiendo su vía canónica.

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Thomas, Amandine. "Hypoxie intermittente et homéostasie glucidique : étude des mécanismes d'action cellulaire A hybrid model to study pathological mutations of the human ADP/ATP carriers Visceral white fat remodeling contributes to intermittent hypoxia-induced atherogenesis The insulin sensitizing effect of topiramate involves KATP channel activation in the central nervous system The Impact of Sleep Disorders on Glucose Metabolism: Endocrine and Molecular Mechanisms Endoplasmic reticulum stress as a novel inducer of hypoxia inducible factor-1 activity: its role in the susceptibility to myocardial ischemia-reperfusion induced by chronic intermittent hypoxia Chronic intermittent hypoxia improves whole-body glucose tolerance by activating skeletal muscle AMP-activated protein kinase in mice Prolyl-4-hydroxylase 1 (PHD1) deficiency impairs whole-body glucose tolerance and insulin sensitivity in mice but does not worsen high-fat diet-induced metabolic dysfunctions Specific transcriptomic signature in response to intermittent hypoxia exposure in liver and fat tissue." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAV044.

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L'hypoxie intermittente (HI), induite par les apnées du sommeil, conduit à des altérations de la sensibilité à l'insuline et de l'homéostasie glucidique mais les mécanismes impliqués restent mal connus. L'objectif de ce travail était d'étudier les effets et les mécanismes sous jacents d'une exposition chronique à l'HI sur l'homéostasie glucidique. L'HI induit une résistance à l'insuline à la fois systémique et tissulaire, ainsi qu'une amélioration de la tolérance au glucose associée à une activation de l'AMPK musculaire. L'HI cause également des altérations du foie et du tissu adipeux associées à un changement du pattern d'expression des gènes dans ces tissus et à un risque accru de développement de pathologies vasculaires comme l'athérosclérose. Enfin, la délétion de PHD1, une des protéines régulatrices de HIF-1, entraîne une résistance à l'insuline associée une stéatose hépatique, faisant de HIF-1 une cible potentielle impliquée dans les altérations metaboliques induites par l'HI
Intermittent hypoxia (IH), induced by sleep apnea, leads to alterations in insulin sensitivity and glucose homeostasis but the mechanisms involved remains poorly understood. The objective of this work was to study the effects and the underlying mechanisms of chronic exposure to IH on glucose homeostasis. IH induces both systemic and tissue-specific insulin resistance , as well as improved glucose tolerance associated with an activation of muscle AMPK. IH also causes a change in the pattern of gene expression in liver and adipose tissue and an increased risk of vascular pathologies such as atherosclerosis development. Finally, the deletion of PHD1, a regulatory protein of HIF-1, leads to insulin resistance associated with hepatic steatosis, making HIF-1 a possible target involved in the metabolic changes induced by IH

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Toste, Fernanda Pereira. "A composição corporal, resistência à leptina e função tireóidea são programadas em ratos cujas mães foram tratadas com leptina no início da lactação." Universidade do Estado do Rio de Janeiro, 2008. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=1147.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
A morbidade e mortalidade por doenças cardiovasculares demonstram tendência geral de declínio, mas, em países em desenvolvimento como o Brasil a ocorrência destes eventos é crescente. A obesidade e principalmente a localização intra-abdominal de gordura, relaciona-se com a ocorrência de doença crônica e diferentes tipos de dietas tem sido testados na busca pela efetiva redução da adiposidade. Fatores biológicos como a resistência à insulina pode interferir na resposta obtida com intervenções nutricionais. O objetivo deste estudo foi avaliar se a perda de peso e as mudanças ocorridas na composição corporal de mulheres saudáveis, eutróficas ou com sobrepeso, submetidas a um programa de prevenção de ganho de peso foram influenciadas pela resistência à insulina no inicio da intervenção. Trata-se de um estudo observacional prospectivo. 203 mulheres foram alocadas randomicamente para dieta de baixo e alto índice glicêmico. Destas, 185, foram avaliadas quanto a presença de resistência a insulina na linha de base, 34,6% foram classificadas como resistentes a insulina segundo o índice HOMA-IR, no ponto de corte 2,71. As medidas antropométricas de localização de gordura, circunferência da cintura (CC) e relação cintura quadril (RCQ) associaram-se com a resistência a insulina do inicio do estudo, sendo a RCQ a mais fortemente associada (razão de prevalência: 2,28; p=0,0005, enquanto que para CC o valor foi 1,53; p=0,04). A análise da modificação do peso e das medidas antropométricas de composição corporal ao longo dos 6 meses de acompanhamento não demonstrou diferença estatisticamente significante entre os grupos com e sem resistência a insulina. Em conclusão, embora a resistência à insulina tenha se correlacionado com a localização de gordura avaliada principalmente pela relação cintura quadril no inicio do estudo, ela não foi capaz de explicar mudanças na composição corporal e de peso em resposta a uma intervenção nutricional.
Pups leptin injection on the first 10 days of lactation programmes for higher food intake (FI), body mass (BM), lean mass, thyroid function, hyperleptinemia and resistance to its action and lower leptin receptor (ObRb) expression on 150 days-old rats. When mothers were leptin-treated on the last 3 days of lactation, it seems to reproduce partially this programming effect, except for higher visceral fat mass (VFM). So, we evaluated the offspring metabolic phenotype when the mothers were treated with leptin in the first 10 days of lactation. On birth, the lactating Wistar rats were divided into: Leptin (LEP) treated with recombinant leptin (8mg/100g, PC, sc) for the first 10 days of lactation and Control (C) saline-treated in the same conditions. The mothers BM and FI were monitored daily and they were milked at the 21st day of lactation. LEP mothers had lower BM during lactation (~6%, p <0.05) and normal FI. The mothers sacrifice occurred to the end of lactation. The leptin concentration of LEP mothers was normal in serum and milk, while T3 was normal in serum and higher in milk (+30%, p <0.05). The offspring BM and FI was monitored daily and accompanied by 4 on 4 days after weaning until 180 days of age. The LEP offspring had lower BM during lactation (~5%, p<0.05) and from the day 69 onward higher BM (+10%, p<0.05), while the FI was higher (+17%, p<0.05) at day 145 onward. The leptin resistance test was performed at 30 and 180 days. Both group was subdivided into: CLEP and LEPLEP treated with leptin (0.5 mg / kg / ip PC); CSAL and LEPSAL treated with saline. The animals were sacrificed at 21, 30 and 180 days. We collected the VFM, carcass, blood (glycemia, leptin, total T3 and T4, TSH, insulin) and liver (GPDm activity). LEP offspring had higher T3 at 21 days, but not significant (p = 0.06) and when they were 30 days-old they already present leptin resistance and lower serum T3 (-20%,p<0.05). At 180 days they had higher VFM (+57%, p<0.05), total body fat (+40%, p<0.05), leptin resistance, hyperleptinemia (+1,35x, p<0.05) with normal 125I thyroid uptake, serum T4 and TSH and lower GPDm activity at 30 and 180 day (-42% and -57%,p< 0.05 respectively). So, the mother's hyperleptinaemia in the beginning of lactation programs as early as the 30 days-old offspring: leptin resistance and hypothyroidism, probably by a higher leptin transfer through the milk. We suggested that the levels of leptin in early lactation are determinants of the physiological regulation of energy balance in adulthood. We suggest that the programming effects are dependent on the way that leptin reaches the offspring. The present study seems more physiological and reproduces almost completely the programming effect in the adulthood when the mothers were leptin-injected at the end of lactation and, partially reproduces the effects when leptin was directally injected in the pups.

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46

Silva, Andreia Marisa Ribeiro da. "Endocrine Resistance and Notch Signalling Pathway in Breast Cancer." Dissertação, 2013. https://repositorio-aberto.up.pt/handle/10216/89949.

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Silva, Andreia Marisa Ribeiro da. "Endocrine Resistance and Notch Signalling Pathway in Breast Cancer." Master's thesis, 2013. https://repositorio-aberto.up.pt/handle/10216/89949.

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48

Alves, Carla Maria Lourenço 1985. "Characterization and functional analysis of biomarkers in endocrine resistance of breast cancer treatment." Master's thesis, 2013. http://hdl.handle.net/10451/9622.

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Abstract:

Tese de mestrado. Biologia (Biologia Molecular e Genética). Universidade de Lisboa, Faculdade de Ciências, 2013
Estrogen receptor positive (ER+) breast cancer accounts for over 80% of breast tumors and these patients are eligible for endocrine therapy. Despite the efficacy of endocrine treatment many breast cancer patients experience recurrence or disease progression as a result of de novo or acquired resistance. Fulvestrant is a relatively recent anti-estrogen drug used in the treatment of advanced ER+ breast cancer, however resistance to this drug also occur in breast cancer patients. The mechanisms of resistance to fulvestrant, as to all forms of endocrine therapy, remain not fully elucidated and likely involve many molecular pathways. By understanding these pathways it should be possible to identify more specific biomarkers that predict response to endocrine therapy and develop new effective therapeutic strategies targeting different mechanisms to improve patient outcome. In this thesis, the role of selected proteins in the molecular mechanism of fulvestrant resistance was evaluated. Using gene array a panel of genes differentially expressed in fulvestrant-resistant vs. parental fulvestrant-sensitive breast cancer cell lines was identified and the role of selected genes on the resistant phenotype was assessed. Initially, the altered expression of the candidate genes and proteins in fulvestrant-resistant cell lines was verified. Knock down experiments using small interfering RNA were performed to evaluate whether reduction of the otherwise over-expression of the genes affected the resistant phenotype. Knock down of CDK6 and SNAI2 in fulvestrant-resistant cells led to decreased proliferation and increased cell death in the presence of fulvestrant. In contrast, no alteration in the proliferation and death was observed in the absence of fulvestrant. These genes may play an important role in the mechanisms of fulvestrant resistance and the evaluation of the expression of these proteins in metastatic breast cancer tissue from patients treated with fulvestrant is underway to assess the prognostic/predictive potential of the genes in clinical setting.
O cancro da mama positivo para o receptor de estrogénio (RE+) corresponde a 80% dos casos de cancro da mama sendo estes doentes elegíveis para terapêutica hormonal. Apesar da eficácia da hormonoterapia a recidiva ou progressão da doença como resultado de resistência de novo ou adquirida ao tratamento é comum. O fulvestrant é um fármaco anti-estrogénio relativamente recente usado no tratamento do cancro da mama RE+ metastizado contudo já foram relatados casos clínicos de resistência a este fármaco. Os mecanismos de resistência a fulvestrant, e a todas as formas de hormonoterapia, permanecem por elucidar envolvendo diferentes vias moleculares. Um melhor conhecimento das diferentes vias poderá permitir a identificação de biomarcadores mais específicos que possam prever a resposta à hormonoterapia e o desenvolvimento de novas estratégias terapêuticas com mecanismos de acção diferentes para melhorar o outcome dos doentes. Nesta tese, é avaliado o papel de potenciais biomarcadores nos mecanismos de resistência a fulvestrant. Após identificação de genes expressos diferencialmente em linhas celulares resistentes e sensíveis a fulvestrant foi avaliado o papel desses genes seleccionados no fenótipo resistente. Inicialmente, foi verificada a elevada expressão dos genes e proteínas candidatos em linhas celulares resistentes comparativamente à linha celular sensível a fulvestrant. Foram realizadas experiências de knock down usando small interfering RNA (siRNA) para determinar se a diminuição da elevada expressão dos genes seleccionados afectava o fenótipo resistente. O knock down de CDK6 e SNAI2 induziu uma diminuição da proliferação e um aumento da morte nas células resistentes na presença de fulvestrant no meio de cultura mas não na ausência deste. Estes genes podem desempenhar um papel importante nos mecanismos de resistência a fulvestrant e, por isso, será avaliada a expressão destas proteínas em tumores da mama metastizados de doentes tratados com fulvestrant para determinar o potencial prognóstico/predictivo destes genes na prática clínica.

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Sousa, Mário Filipe Teixeira de Fontes e. "Exploring epigenetic profiling as prognostic/predictive markers of endocrine resistance in estrogen receptor positive breast cancer." Tese, 2020. https://hdl.handle.net/10216/129249.

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Sousa, Mário Filipe Teixeira de Fontes e. "Exploring epigenetic profiling as prognostic/predictive markers of endocrine resistance in estrogen receptor positive breast cancer." Doctoral thesis, 2020. https://hdl.handle.net/10216/129249.

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Dissertations / Theses on the topic 'Endocrine resistance'

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