Дисертації з теми "Cancer cell physiology"

Studies have shown that gain-of- function mutant p53, AKT, and NFκB promote invasion and metastasis in tumor cells. Signals transduced by AKT and p53 are integrated via negative feedback between the two pathways. Tumor derived p53 was also indicated to induce NFκB gene expression. Due to the close relationship between p53/AKT and p53/NFκB, we hypothesized that AKT and NFκB can enhance motility in cells expressing mutant p53. Effects on cell motility were determined by scratch assays. CXCL5- chemokine is also known to induce cell motility. We hypothesized that enhanced cell motility by AKT and NFκB is mediated, in part, by CXCL5. CXCL5 expression levels in the presence and absence of inhibitors were determined by qRT-PCR. We also hypothesized that gain-of-function mutant p53 contributes to the activation of AKT. The effect of mutant p53 on AKT phosphorylation was investigated with a Ponasterone A- inducible mutant cell line (H1299/R175H) and vector control. These results indicated that AKT and NFκB enhance motility in cells expressing mutant p53 and this enhanced motility is, in part, mediated by CXCL5. However, AKT phosphorylation was independent of mutant p53.

The insulin-like growth factor (IGF) pathway consists of two ligands (IGF-I and IGF-II), two receptors (IGF-IR and IGF-IIR) and six IGF binding proteins (IGFBP-I through -6). There is considerable evidence from both laboratory and population studies that IGF physiology is relevant to neoplastic growth. For example, it has been shown that IGF-I and/or IGF-II act as mitogens and anti-apoptotic agents for both normal and malignant cells by binding to the IGF-IR and activating downstream signalling pathways. Consistent with this data, IGF-IR inhibition by a variety of strategies inhibits cancer cell proliferation and/or induces apoptosis both in vitro and in animal models of neoplasia. Furthermore, epidemiological studies have demonstrated a positive correlation between serum IGF-I levels and risk of subsequent cancer. Classically, the IGFBPs were considered to be growth inhibitors, as they had a well-defined role in sequestering the mitogens IGF-I and IGF-II, therefore preventing binding and subsequent activation of mitogenic and anti-apoptotic pathways downstream of the IGF-IR. However, increasing evidence indicates that under certain conditions, IGFBPs can act as growth stimulators, and both IGF-dependent and -independent mechanisms have been proposed.
Although the roles of the IGFs, IGF-IR and IGFBPs in cancer have been studied extensively, this thesis describes several new links between IGF physiology and neoplasia. In the first section, we demonstrate that IGF-I can attenuate growth inhibition and apoptosis induced by a class of drugs called COX-2 inhibitors in BxPC-3 pancreatic cancer cells. This effect could be attributed to opposite influences of IGF-IR signalling and COX-2 inhibitors on activation of Akt, with IGF-IR signalling increasing activity and COX-2 inhibitors decreasing activity. In the second section, we demonstrate that in 184htert cells, an immortal but untransformed breast epithelial cell line, COX-2 inhibitors can induce IGFBP-3 expression. We go on to show that IGFBP-3 can inhibit growth of this cell line in an IGF-dependent manner, and speculate that this action of COX-2 inhibitors may be relevant to data linking use of this class of drugs to decreased breast cancer risk. In the third section, we demonstrate that the expression of IGFBP-2 in U251 glioma cells is inhibited by the induction of the tumor suppressor PTEN. Furthermore, IGFBP-2 does not effect the growth of this cell line, indicating that published associations between tumor IGFBP-2 expression and grade of glioma may be a result of IGFBP-2 acting as a marker for loss of function of PTEN. In the fourth and final section, we demonstrate that in MDA-MB-231 breast cancer cells, over-expression of IGFBP-2 can enhance growth, indicating that the effect of IGFBP-2 on growth of neoplastic cells is tissue specific. Furthermore, antisense strategies targeting IGFBP-2 mRNA (antisense oligonucleotides and siRNA) can inhibit growth of IGFBP-2-expressing breast cancer cells both in vitro and in vivo.
Taken together, these results extend the existing body of evidence demonstrating that IGF physiology contributes to neoplastic growth, and suggest that strategies to inhibit IGF-IR signalling and/or IGFBP-2 expression may have therapeutic value for some types of cancers.

The mechanisms by which cancer cells hijack the actin cytoskeleton to invade and disseminate to distant sites of metastasis remains one of the great frontiers in cancer research. Many actin-regulating proteins have been identified to be important in cancer cell invasion and metastasis. However the role of a major actin assembly promoting complex, Scar/WAVE regulatory complex (WRC) in cancer cell invasion is poorly understood. WRC has a well-known motility-promoting role in 2D planar cell migration, but a recent study on human epithelial cancers suggests WRC may be anti-invasive in vivo. To investigate the controversy, human epithelial cancer cells with reduced WRC expression were tested in multiple 3D cell motility assays. Interestingly, WRC demonstrates a robust anti-invasive role in these exciting experiments. To understand how loss of WRC promotes invasion, the molecular mechanism is investigated. N-WASP is the other major actin assembly promoting protein. Unlike WRC, N-WASP is interestingly not required for 2D planar cell migration, but is important for motility in 3D. The interplay of the two major actin assembly promoting proteins has not been explored in 3D cell motility. I report here that loss of WRC promotes hyper-activation of focal adhesion kinase that leads to N-WASP accumulation and activation at the invasive front. This chain of events results in enhanced invasion providing a molecular mechanism of WRC’s anti-invasive function.  In addition to this FAK-N-WASP core mechanism, I also identified a novel pro- invasive role of HSPC300 independently of WRC. Loss of WRC possibly releases free HSPC300 that could subsequently interact with and regulate N-WASP activation during invasion providing a potential direct molecular link between the two proteins. Furthermore, WRC also supresses focal adhesion kinase mediated cell transformation and tumour formation in vivo. In this thesis I therefore demonstrate novel anti-invasion and anti-tumourigenesis functions of WRC. I also show how a novel WRC binding protein, NHS, could negatively regulate WRC function.

The process of metastasis is initiated through the acquisition of inherent and autonomous motile and invasive properties by tumor cells. These phenomena are initiated through a balance between forward cancer cell membrane protrusion and tail retraction, and occur via cell cytoskeleton remodeling, actin reorganization, and coordinated focal adhesion assembly and disassembly events. Among the vast network of cytoskeletal proteins, the actin-bundling protein fascin plays a major function in cell cytoskeleton remodeling. It is a 55-kDa protein involved in the formation of filopodia and cell migration, and found to be upregulated in many cancers. We report herein key functions for fascin in the regulation of prostate and breast cancer progression. Fascin expression is upregulated in localized and hormone refractory prostate cancer, responsible for a more aggressive clinical course. In addition, functional dissection of fascin reveals a novel function in the regulation of focal adhesion turnover dynamics, by modulating the phosphorylation state of central focal adhesion proteins through a potential collaboration with the protein tyrosine phosphatase, PEST. Together, our data support the importance of fascin in cancer cell invasion and as a significant prognostic marker and a potential therapeutic target for aggressive cancers.

Breast cancer (BC) is one of the most diffused types of cancer worldwide. It affects predominantly women and is a highly curable disease if diagnosed at early stage. Several classifications of BC do exist according to different histopathological and molecular features. The worst subtype of BC are triple negative breast cancers (TNBCs) that do not express Estrogen (ER), Progesterone (PgR) and epidermal growth factor 2 (HER2) receptors consequently, these tumors are not sensitive to hormonal therapy. Nowadays, there is no specific clinical guideline approved, therefore, TNBCs treatment consists of cytotoxic agents and radiotherapy. The Hedgehog (Hh) pathway plays a pivotal role during the development of the organism and its expression is tightly controlled and normally kept silent in adult tissue. The Hh pathway indeed is reactivated for homeostasis maintenance after tissue injury or for the physiological tissue renewal. Deregulation of the Hh pathway is associated with development disturbs, underlining the relevance of its precise controlled expression. More and more Hh signalling is found to be involved in cancer development and progression. A growing body of literature underlines the correlation between the Hh pathway and bad prognosis for BCs. Indeed, the Hh pathway is normally silenced in normal breast epithelium and aberrantly activated in TNBCs, where it is associated with a more aggressive phenotype, enhancing proliferation, migration and invasion, furthermore, its activation is related to chemoresistant phenotypes of TNBCs. Carbonic anhydrases (CAs) are evolutionary conserved enzymes, mostly known for their role in pH regulation. CAs catalyze the reversible hydration of H2CO3 into CO2 and H2O. Several other roles have been described and attributed to CAs, from cell survival and migration, to the priming of the stem cell niche. Several CAs classes have been characterized and are conserved among the species. The classification is done according to the subcellular localization of CAs. Membrane bound CAs namely CAIX and CAXII, are overexpressed and active in cancer. While the role of CAIX is associated to bad prognosis, the role of CAXII has a contradictory outcome and still need to be elucidated. In BC, downregulation of CAXII reduced MDAMB231 cell migration through a reduction in p38 phosphorylation, while some researchers confer to the presence of this protein, a good prognostic value. We demonstrate for the first time a correlation between the Hh pathway and CAXII in controlling BCs pathology, emphasising how the activation of the Hh pathway is crucial in the control of CAXII expression, with consistent effects on cell proliferation, migration and invasion. Understanding the reciprocal regulation could be of main interest and should be taken into account in the design of new molecules to improve BC patient’s life expectancy.

Protein kinase C δ (PKC-δ) is a novel member of the PKC family of serine-threonine kinases. PKC-δ structure is widely conserved within the PKC family and has a catalytic region and regulatory region. The regulatory region has two main sub domains C1 and C2. Although several studies have investigated the role of the C1 domain, little is known about the function of the C2 domain, however there is some evidence that it acts as a protein interaction domain. PKCs are involved in a wide variety of cellular functions within cancer. PKC-δ has been demonstrated to have a particular involvement with the apoptotic processes of a cancer cell. A pro-apoptotic role for PKC-δ has been identified, whereby tyrosine phosphorylation of particular residues induces translocation to the nucleus, alongside a similar translocation event for caspase-3. In the nucleus, caspase-3 cleaves the regulatory and catalytic regions to form a free catalytic domain that is uninhibited by the regulatory portion. This free catalytic region causes the induction of the apoptotic pathway. Conversely an anti-apoptotic role has also been identified for PKC-δ. This was found in MDA-MB-231 cells, which have a ras mutation. Due to this mutation in these cells, ERK1/2 phosphorylation is high. Without PKC-δ activity the high phosphorylation levels induce apoptosis. PKC-δ acts on a pathway to reduce ERK1/2 phosphorylation, thus facilitating cell survival. This study aimed to investigate the role of the PKC-δ C2 domain within breast cancer cells. Through use of these techniques, the role of the C2 domain was examined in order to consider its utility as a drug target to treat breast cancer. •Constructs were developed of pIRESneo2 vector with myc-tagged C2 domain and myc-tagged PKC-δ sequences •Breast cancer cell lines, MDA-MB-468, MDA-MB-231 and MCF-7, were stably transfected with a vector control and myc-δC2 construct. MDA-MB-231 and MCF-7 were also transfected with myc-PKC-δ. •Cell lines developed were examined for alterations due to the presence of the C2 domain or PKC-δ over-expression As the C2 domain is proposed to be a protein interaction domain, we hypothesized that over-expression of this domain would interfere with endogenous PKC-δ interactions, through competitive inhibition, and thus we could identify C2 domain roles. The effect on the cells of the endogenous PKC-δ would be opposed by the C2 domain. Thus the role of endogenous PKC-δ could also be clarified for a particular situation - it would be the opposite of the effects induced by the myc-δC2 on the cells. In the MDA-MB-468 stable cell lines, immuno-fluorescence examination of the myc-δC2 cells showed the myc-δC2 was localised at the ends of actin protrusions from the bulk of the cell. The myc-δC2 expressing cells had a more extensive cytoskeleton than the Vector control cells, possibly suggesting improved attachment to a surface. An experiment examining this illustrated that the myc-δC2 cells appeared to attach in a shorter time period. This implies that the role of the endogenous PKC-δ is to discourage cell attachment and promote an invasive phenotype, this is in agreement with the literature. During sub-culture of the MDA-MB-468 cell lines it became apparent that the myc-δC2 cells were growing at an increased rate over the Vector cell lines. This was quantified and indeed the myc-δC2 cells did increase in cell number more than the Vector cells. This was also the case with the MDA-MB-231 cells but not with the MCF-7 cells. Growth is a balance of proliferation and apoptosis. This effect indicates that PKC-δ is pro-apoptotic, or anti-proliferative. MCF-7 cells lack caspase-3 and thus pro-apoptotic effects of PKC-δ would be affected in this cell line. As the myc-δC2 did not have an effect in these cells we examined apoptosis to see if these effects could be attributed to differences in apoptosis. The MDA-MB-468 cells expressing myc-δC2 had higher viability than the Vector cells. This fits with the cell number data, indicating that a lower level of apoptosis has led to a greater cell number, and advocates a pro-apoptotic role for PKC-δ. This was not the case in MDA-MB-231 cell lines where Vector cells had higher viability. This agrees with the literature describing PKC-δ displaying an anti-apoptotic role in this cell line, but does not fit with the cell number data. Thus, differences in cell number are likely due to effects on proliferation, although this was not investigated. MCF-7 cells showed no differences indicating the apoptotic program of these cells is indeed affected by the lack of caspase-3. Serum starvation is a commonly used method to induce apoptosis. MDA-MB-468 cell lines were serum starved in order to examine the effects. The apoptosis profile was altered and myc-δC2 cells showed lower viability than the Vector cells, indicative of an anti-apoptotic effect of PKC-δ. An anti-apoptotic effect is observed in MDA-MB-231 cells, where the effect was proteasome dependent. This was also the case in this situation. The anti-apoptotic effect is related to levels of phosphorylated ERK1/2, where high levels are pro-apoptotic. The phosphorylation status was examined and illustrated a much higher level of phosphorylation in myc-δC2 cells over Vector cells when starved. This indicates myc-δC2 is inhibiting the de-phosphorylating role of PKC-δ in these apoptotic cells. Thus it appears that the C2 domain acts as a ‘sensor’ to serum status, appropriating PKC-δ effects in apoptotic pathways according to the serum status, the method of which is unknown. This study has highlighted the importance of the PKC-δ C2 domain in breast cancer apoptosis. The effects appear to require a fully active PKC-δ pro-apoptotic pathway, and are dependent on the serum status of the cells. Further investigation would be required to identify a level of serum for use in vitro that is relevant to an in vivo tumour situation. If low levels are more relevant to a clinical state then it may be possible to target the C2 domain with drugs to allow induction of apoptosis. The differences between the cell lines clearly show that the phenotypic analysis of tumours would be vital to identifying whether such treatment would be applicable, as effects of any drug would vary greatly across tumour types. MDA-MB-468 and MDA-MB-231 are both triple negative cell lines (i.e. they do not express progesterone, oestrogen or HER2 receptors); however the strong differences seen in this case indicate further phenotypic analysis would be essential.

Myofibroblasts are recognised to play an important role in wound healing and the maintenance of tissue integrity. In addition, they are increasingly recognised to provide a supporting microenvironment for cancer cells. They secrete a variety of chemokines, cytokines, growth factors and proteases that collectively regulate cell proliferation, migration and invasion. Specific chemokines are known to recruit mesenchymal stromal cells (MSCs) to both tumours and normal tissue which may then give rise to myofibroblasts. Proteomic studies by Holmberg and Varro (unpublished observations) identified chemerin as an upregulated chemokine in conditioned media (CM) from oesophageal cancer associated myofibroblasts (CAMs) compared to adjacent tissue myofibroblasts (ATMs). Chemerin is potent chemo-attractant for immune and inflammatory cells. The objectives of this thesis were (a) to functionally characterise the oesophageal myofibroblasts,(b) validate the findings of previous proteomic studies and (c) determine the role of chemerin in MSC migration. Oesophageal CAMs from both squamous and adenocarcinoma tumours were shown to be more proliferative than their paired ATMs, or normal tissue myofibroblasts (NTMs). In addition, CAM conditioned media increased the proliferation and migration of two oesophageal cancer cell lines (OE21 and OE33) and stimulated MSC migration compared to ATM CM. The data suggest oesophageal CAMs promote an aggressive tumour microenvironment. Western blotting and ELISA confirmed increased chemerin secretion by squamous carcinoma CAMs. Chemerin and conditioned media from squamous carcinoma CAMs, stimulated MSC and OE21 cell migration; Chemerin neutralizing antibody reversed these effects and siRNA knockdown of chemerin in CAMs, or of its cognate receptor ChemR23 in MSCs, decreased migratory responses. Studies using pharmacological inhibitors or Western blot of cellular proteins indicated that chemerin stimulated MSCs via PKC, and p42/44, p38 MAP and JNK kinases. Macrophage Inhibitory Factor (MIF) was identified as a putative chemerin target in MSCs and validated by ELISA and Western blot of MSC media and cell extracts. MIF inhibited MSC migration in response to low or moderate concentrations of chemerin, indicating that it might restrain MSC migration in normal tissues but not in cancers where chemerin is elevated. Finally, confirmation of chemerin-chemR23 interactions was obtained using a chemR23 antagonist, CCX832. Chemerin induced MSC and OE21 cell migration was inhibited by CCX832. Moreover, transendothelial migration of MSCs in response to chemerin or CAM conditioned media was reversed by CCX832. Transendothelial migration was also shown to depend on chemerin-stimulated MMP-2 secretion. These findings indicate a molecular mechanism by which MSCs are recruited to tumours. Taken as a whole, this work indicates that myofibroblasts derived from oesophageal cancers differ from those in adjacent or normal tissue. The finding of increased chemerin in these cells is novel and may be relevant to MSC recruitment. Since it is possible to inhibit the effects of chemerin on MSCs using CCX832, there is the potential for a novel therapeutic approach to prevent cancer progression.

Background. Fatigue is a debilitating consequence of lung cancer and its treatments. Reviewing the literature in cancer-related fatigue provides few etiological factors, making evidence-based interventions limited. In this study, previously identified factors as well as muscular and cardiorespiratory function were assessed as potential contributors to fatigue in stages 3A/B and 4 NSCLC patients.
Methods. Participants were evaluated by a physical therapist within the McGill Cancer Nutrition and Rehabilitation Program. Performance-based measures of physical function [upper limb strength and endurance (Jamar dynamometry), lower limb strength (30sec chair rise), cardiorespiratory function (2 minute walk - 2MW)] and a symptom questionnaire (Edmonton Symptom Assessment Scale) were conducted at one point in time. The primary endpoint of global fatigue rating was assessed using the Brief Fatigue Inventory (BFI).
Results. Fifty-eight patients (30M:28F, mean age 68 +/- 12) participated in the study. Forty-three percent were actively receiving treatment at the time of assessment. On the BFI, 67% had moderate or severe fatigue and 84% indicated fatigue had interfered with their functioning during the past 24 hours. Global fatigue scores were unrelated to hand grip strength or endurance measurements, hematological parameters or sleep quality but were significantly correlated with chair rise performance, overall rating of breathlessness, patient rating of pain and patient rated weakness. Multivariate regression analysis suggested the best model for global fatigue scores incorporates patients' ratings of weakness, breathlessness and chair rise performance.
Conclusions. Fatigue is prevalent and impacts on the function of advanced NSCLC patients. Several key factors contribute to this fatigue, with muscular and cardiorespiratory restrictions playing an important role. Such findings may have clinical implications in the recommendations of rest and exercise to best manage fatigue.

Head and neck squamous cell carcinoma is the 6th most common malignancyworldwide. Recently, a link between cancer and inflammation has been found. Mediatingthis relationship are the chemotactic cytokines known as chemokines. CXCL8 (Interleukin-8), a CXC ELR+ Chemokine mainly responsible for neutrophil chemoattraction, has beenimplicated in increased tumor proliferation, migration and angiogenesis. The current studytests the effects of CXCL8 on the tumor proliferation and metastasis. By genetically modifying cells to knockdown or overexpress the CXCL8 gene we tested its biological rolein head and neck cancer progression. Overexpression of CXCL8 in HN4 tumor cells withlow endogenous CXCL8 levels was found to increase tumor growth, as judged by cellcounting and MTT assays. Conversely, RNAi-mediated knockdown of CXCL8 expressionin HN12 cells, which express high levels of this chemokine, resulted in a decrease inproliferation. Similarly, overexpression of CXCL8 enhanced migration of HN4 cells invitro, while knockdown inhibited HN12 cell migration and invasion through a basementmembrane substitute. Taken together, these findings support the hypothesis that CXCL8affects multiple processes involved in head and neck cancer tumor progression. The datasuggest that CXCL8 is a potential therapeutic target for head and neck, and other, cancers.

Thesis (PhD)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: Introduction – Due to spatial separation from the native vascular bed, solid tumours develop regions with limited access to nutrients essential for growth and survival. The promotion of a process known as macroautophagy may facilitate in the maintenance of intracellular amino acid levels, through breakdown of cytoplasmic proteins, so that they remain available for macromolecular biosynthesis and ATP production. Several studies point to the potential ability of some cancers to temporarily increase autophagy and thereby prolong cell survival during metabolic stress. The validity of these claims is assessed when a commonly used breast cancer cell line and an epithelial breast cell line are starved of amino acids in this study. Furthermore, we go on to hypothesize that acute amino acid deprivation during treatment will result in an elevated sensitivity of MDAMB231 cells to doxorubicin toxicity but limit its cytotoxic side-effects in MCF12A cells. Methods and study design- Human breast cancer cells (MDAMB231) and breast epithelial cells (MCF12A) cultured in complete growth medium were compared to those incubated in medium containing no amino acids. Steady state autophagy levels were monitored using classical protein markers of autophagy (LC3-II and beclin-1) and the acidic compartmentalization in cells (Lysotracker™ red dye) in conjunction with autophagy inhibition (bafilomycin A1 and ATG5 siRNA). Cell viability was monitored using several techniques, including caspase 3/7 activity. ATP levels were assessed using a bioluminescent assay, while mass spectrometry based proteomics was used to quantify cellular amino acid levels. Similar techniques were used to monitor autophagy during doxorubicin treatment, while cellular doxorubicin localization was monitored using immunofluorescence microscopy. Finally, a completely novel GFP-LC3 mouse tumour model was designed to assess autophagy and caspase activity within tumours in vivo, during protein limitation and doxorubicin treatment. Results - Amino acid deprivation resulted in a transient increase in autophagy at approximately 6 hours of amino acid starvation in MDAMB231 cells. The amino acid content was preserved within these cells in an autophagy-dependent manner, a phenomenon that correlated with the maintenance of ATP levels. Inhibition of autophagy during these conditions resulted in decreased amino acid and ATP levels and increased signs of cell death. MCF12A cells displayed a greater tolerance to amino acid starvation during 24 hours of amino acid starvation. Evidence indicated that autophagy was important for the maintenance of amino acid and ATP levels in these cells and helped prevent starvation-induced cell death. Furthermore, data showed that concomitant amino acid withdrawal resulted in decreased cellular acidity in MDAMB231 cells, and increased acidity in MCF12A cells, during doxorubicin treatment. These changes correlated with evidence of increased cell death in MDAMB231 cells, but a relative protection in MCF12A cells. A novel model was used to apply these techniques in vivo, and although mice fed on a low protein diet during high dose doxorubicin treatment had increased mean survival and smaller tumour sizes, evidence suggested that autophagy is protecting a population of cells within these tumours. Conclusions - This novel approach to tumour sensitization could have several implications in the context of cancer therapy, and given the delicate relationship that autophagy has with the cancer microenvironment, efforts to determine the mechanisms involved in autophagy and sensitization could lead to new and innovative treatment opportunities for cancer management.
AFRIKAANSE OPSOMMING: Inleiding – As gevolg van hul skeiding van die oorpronklike vaskulêre netwerk, ontwikkel soliede gewasse areas met beperkte toegang tot noodsaaklike voedingstowwe. Die bevordering van 'n proses wat as makro-autofagie bekend staan, kan die handhawing van intrasellulêre aminosuur vlakke fasiliteer. Voorafgenoemde proses word waarskynlik deur die afbreek van sitoplasmiese proteïene teweegebring om sodoende vir makro-molekulêre biosintese en ATP produksie beskikbaar te kan wees. Verskeie studies dui daarop dat sommige kankersoorte die vermoë het om autofagie tydelik te verhoog, en daarby sel oorlewing gedurende metaboliese stress te verleng. Die geldigheid van hierdie eise word evalueer wanneer 'n algemeen beskikbare borskanker sellyn, en 'n borsepiteelsellyn in hierdie studie van aminosure verhonger word. Verder, veronderstel ons dat akute aminosuur ontneming gedurende behandeling 'n verhoogde sensitiwiteit van MDAMB231 selle tot doxorubicin toksisiteit tot gevolg sal hê, maar terselfdetyd die middel se sitotoksiese newe-effekte in MCF12A selle sal beperk. Metodes en studie ontwerp – Menslike borskanker- (MDAMB231) en bors epiteel selle (MCF12A) wat in volledige groeimedium gekweek is, is vergelyk met selle wat in aminosuur vrye medium gekweek is. Basislyn autofagie-vlakke is gemonitor deur die gebruik van klassieke autofagie proteïen merkers (LC3-II en beclin-1) en die asidiese kompartementalisering in selle (Lysotracker™ rooi kleurstof) saam met autofagie inhibisie (bafilomycin A1 and ATG5 siRNA). Sellewensvatbaarheid is deur die gebruik van verskeie tegnieke, insluitend caspase 3/7 aktiwiteit, gemonitor. ATP-vlakke is deur die gebruik van 'n bioluminiserende tegniek gemeet, terwyl massa-spektrometrie-gebaseerde “proteomics” gebruik is om sel aminosuur vlakke te kwantifiseer. Soortgelyke tegnieke is gebruik om autofagie gedurende doxorubicin behandeling waar te neem, terwyl sellulêre doxorubicin lokalisasie deur die gebruik van immunofluoresensie mikroskopie gemonitor is. Ten slotte, is 'n unieke GFP-LC3 muismodel in hierdie studie ontwikkel. Hierdie model is gebruik om autofagie en caspase aktiwiteit in gewasse in vivo te bestudeer tydens proteïen beperking en doxorubicin behandeling. Resultate – Aminosuur ontneming het tot 'n tydelike verhoging in autofagie na ongeveer 6 ure van aminosuur verhongering in MDAMB231 selle gelei. Die aminosuur inhoud van hierdie selle het op 'n autofagie-afhanklike manier behoue gebly. Hierdie verskynsel het met die handhawing van ATP-vlakke gekorreleer. Autofagie inhibisie gedurende hierdie kondisies het 'n verlaging in aminosuur en ATP-vlakke teweeggebring, sowel as vermeerderde tekens van seldood tot gevolg gehad. MCF12A selle het 'n groter toleransie tot aminosuur verhongering tydens die 24 uur aminosuur verhongeringsperiode getoon. Getuienis het aangedui dat autofagie belangrik vir die handhawing van aminosuur en ATP-vlakke in hierdie selle was, en gehelp het om verhongerings-geïnduseerde seldood te voorkom. Verder het data gewys dat aminosuur ontrekking tot verminderde sellulêre asiditeit in MDAMB231 selle, en verhoogde asiditeit in MCF12A selle gedurende doxorubicin behandeling gelei het. Hierdie veranderinge stem ooreen met getuienis van toenemende seldood in MDAMB231 selle, maar 'n relatiewe beskerming in MCF12A selle. 'n Unieke model was gebruik om hierdie tegnieke in vivo toe te pas. Alhoewel verhoogde oorlewing en kleiner gewasse in muise op 'n lae proteïen dieet gedurende hoë dosis doxorubicin behandeling opgemerk is, het bewyse voorgestel dat autofagie 'n populasie selle binne die gewasse beskerm. Gevolgtrekkings – Hierdie unieke benadering tot tumor sensitisering kan verskeie implikasies in die konteks van kanker behandeling hê. Gegewe die delikate verhouding van autofagie met die kanker mikro-omgewing, kan pogings om die meganismes betrokke in autofagie en sensitisering te bepaal, tot nuwe en innoverende behandelings vir kanker lei.

Colorectal cancer (CRC) arises in part from the dysregulation of cellular proliferation, associated with the canonical Wnt pathway, and differentiation, effected by the Notch signalling network. In this thesis, we develop a mathematical model of ordinary differential equations (ODEs) for the coupled interaction of the Notch and Wnt pathways in cells of the human intestinal epithelium. Our central aim is to understand the role of such crosstalk in the genesis and treatment of CRC. An embedding of this model in cells of a simulated colonic tissue enables computational exploration of the cell fate response to spatially inhomogeneous growth cues in the healthy intestinal epithelium. We also examine an alternative, rule-based model from the literature, which employs a simple binary approach to pathway activity, in which the Notch and Wnt pathways are constitutively on or off. Comparison of the two models demonstrates the substantial advantages of the equation-based paradigm, through its delivery of stable and robust cell fate patterning, and its versatility for exploring the multiscale consequences of a variety of subcellular phenomena. Extension of the ODE-based model to include mutant cells facilitates the study of Notch-mediated therapeutic approaches to CRC. We find a marked synergy between the application of γ-secretase inhibitors and Hath1 stabilisers in the treatment of early-stage intestinal polyps. This combined treatment is an efficient means of inducing mitotic arrest in the cell population of the intestinal epithelium through enforced conversion to a secretory phenotype and is highlighted as a viable route for further theoretical, experimental and clinical study.

Breast cancer is the most common type of cancer in women worldwide. Approximately two-thirds of breast cancers are oestrogen receptor positive (ER+), which are activated via oestrogen dependent and independent mechanisms. The pathogenic role of oestrogen in breast cancer is well established, thus, targeting ER becomes an essential target in breast cancer anti-hormonal therapy. Tamoxifen is the most important anti-hormonal therapeutic agent which has been used as the gold standard in the treatment of ER+ breast cancer patients. Tamoxifen acts by competing with oestrogen for binding to the ER and reduces the transcription of oestrogen dependent genes. However, approximately 30-50% of patients either fail to respond or eventually become resistant to tamoxifen via not fully elucidated mechanisms, resulting in a serious clinical challenge in breast cancer management. Also there is increasing evidence that cancers are driven by cancer stem cells which are characterised by their ability for self renewal and resistance to drug therapies. Therefore the aim of this study was to evaluate the role of oestrogen receptors in both de novo and acquired tamoxifen resistant breast cancer. Study the influence of stem cell factors and the embryonic stemness gene in both MDA-MB-231 and MCF7/Tmx breast cancer cell lines with respect to the hypothesis that anti-stem cell factor and silencing of the Nanog may restore sensitivity to tamoxifen and enhance cell apoptosis. Qualitative and quantitative assays showed significant expression of CD44, PgP, MRP1 and embryonic markers (Nanog, Oct3/4 and Sox2) in MDA-MB-231 and MCF7/Tmx cells. Independently, MDA-MB-231, MCF7/Tmx and parental MCF7/WT cells were treated with monoclonal anti-stem cell factor (ACSF) and interfered with Nanog short interference RNA (siRNA), then growth rate, drug accumulation and apoptosis were assessed in response to 4-hydroxtamoxifen (4-OHT). Quantitative analysis of the influx and efflux rate was performed using the Technetium (99mTc) sestamibi assay in response to blocking SCF. iv Results show a significant apoptosis enhancement after treatment with ASCF in both MDA-MB-231 and MCF/Tmx cells (P<0.005) and a significant increase in the influx rate of 99mTc-MIBI in MDA-MB-231 cells. Growth rate and apoptosis markers were assessed prior to and after the silencing of Nanog gene. Results show a significant increase in apoptosis and reduction in the growth rate in both MDA-MB-231 and MCF/Tmx cells (P<0.005). This study demonstrates that multi drug resistance is mainly a phenomenon of acquired tamoxifen resistance, but not de novo resistance. The inhibition of SCF could inhibit cell proliferation and significantly increases cell sensitivity to tamoxifen in MDA-MB-231 and acquired tamoxifen resistant cells MCF7/Tmx. This study identified a high expression of embryonic markers Nanog, Oct3/4 and Sox2 in both MDA-MB-231 and MCF7/Tmx cells and that the silencing of the Nanog gene reduces cell proliferation and increases apoptosis in MDA-MB-231 and MCF7/Tmx cells. In conclusion, the results suggest that the neutralisation of stem cell factor may play an important role in enhancing tamoxifen response in ER- cells and less in acquired tamoxifen resistant breast cancer cells, via enhancing drug accumulation. The positive association of the embryonic markers with negative (ER-) and acquired tamoxifen resistant breast cancer cells could be used as prognostic markers and the knockdown of these transcription markers could enhance the response to tamoxifen and could be used in the management of breast cancer.

Doxorubicin (DOX) is one of the most potent anthracycline antibiotics used for treatment of multiple tumor types including breast cancer treatment. However, its efficacy is limited by fatal toxicities associated with DOX therapy causing damage to healthy tissues and organs. In this project, a high molecular weight gelatin-doxorubicin (GDOX) conjugate was synthesized and purified. Gelatin was linked to DOX in this conjugation via glygly spacer and an acid labile hydrazone bond. GDOX was characterized for molecular weight distribution of gelatin by size exclusion chromatography. Drug load on the conjugate was measured by UV-visible spectroscopy. DOX release from conjugate was measured at three different pH: 4.8, 6.5 and 7.4. A minimal DOX release of 9% ± 3 % was observed at systemic pH (7.4) and maximum release of 49 ± 1.8 % was observed at tumor microenvironment at pH 4.8. GDOX was then evaluated in an in vitro model consisting of two breast cancer cell lines: MCF7 cells and a triple negative breast cancer (TNBC) MDA-MB-231 cells for intracellular trafficking with emphasis on lysosomal targeting. Cell uptake and localization of an equivalent concentration of 10 µM DOX in GDOX was determined with fluorescence microscopy in these cells and fluorescence quantification was performed with Fiji software. Whole cell fluorescence showed localization of GDOX in both cell lines with higher conjugate accumulation in MDA-MB-231 cells. Lysosomal membrane permeabilization (LMP) was studied using a fluorescent labelled dextran. After 24 h, GDOX triggered 100% LMP in TNBC cells but surprisingly no LMP was observed in MCF7 cells. Finally, to evaluate GDOX induced DNA damage in these cells, TUNEL assay was performed which labels DNA strands breaks using a fluorescent tag. Images were captured on a fluorescent microscope and evaluated for percent apoptotic cell count. A similar extent of apoptosis was seen in both the cell lines and was comparable to free DOX. Overall, these results suggest that conjugate has potential of inducing toxicity to TNBC cells via lysosomal pathway which may induce apoptosis and thus has a potential for treatment of TNBC tumors. However, MCF7 cell studied results indicates a different pathway of toxicity in inducing apoptosis.

In recent years, mitochondria have gained much interest as organelles involved not only in the processes of obtaining energy, but also associated with novel roles in cell physiopathology. These roles range from mitochondria being the site for lipid synthesis, through constituting a buffering system for intracellular calcium, and from being a mediator of reactive oxygen species signalling to a regulator of different cell death types. This group of roles requires a highly regulated system of signalling mechanisms. One of these emerging mechanisms is the communication between the mitochondria and the endoplasmic reticulum. In fact, mitochondria and endoplasmic reticulum are tightly associated, in a region called mitochondria associated membranes, where several signalling events allow continuous communication between the two organelles. Among these signalling events, calcium signalling has been considered of great importance. Advanced techniques of molecular biology allow the development of tools for the investigation of these complex subcellular compartments. Particularly useful are those based on the green fluorescent protein and the calcium sensitive luminescent protein, aequorin. In this work, the aforementioned tools have been used to investigate mitochondrial physiology, especially its communications with the endoplasmic reticulum. Two different cellular events were studied: i) the regulation of apoptosis by a strategic oncosuppressor, p53 and ii) differentiation of oligodendrocytes progenitor cells into adult oligodendrocytes during stress condition generated by cytokines. Performed experiments allowed the describing of the endoplasmic reticulum as a new intracellular localization site of p53, where it increases the luminal calcium concentration, promoting the sensitivity to calcium dependent apoptotic stimuli. Simultaneously, it has been revealed how mitochondria are a target for TNFα in oligodendrocytes progenitors, where it promotes reactive oxygen species production and impairment of the respiratory chain activity, inhibiting cell differentiation without promoting cell death. In conclusion, these approaches reveal completely new relations between mitochondria, calcium signalling and cell physiology, shedding new light on the role for this fascinating organelle.

Early detection of biomarkers of tumour treatment response improves clinical management, in vivo. Magnetic resonance spectroscopy (MRS) has demonstrated potential for identifying early biomarkers of effective treatment. However, more detailed in vitro studies are required to improve our understanding and facilitate its use. The aim of this study is to determine ¹H high-resolution magic angle spinning (HR-MAS) nuclear magnetic resonance (NMR) biomarkers of cytostasis and cell death in a rat glioma BT4C cell line. Cytostasis and cell death were induced in BT4C cells using cisplatin and substrate free medium, respectively. Cell viability was examined by various techniques. The lipid and metabolite alterations in whole cells were investigated by ¹H HR-MAS NMR. Significant alterations in lipids and metabolites were detected in response to cytostasis or necrosis. NMR lipid accumulation was associated with an increase in cytoplasmic lipid droplets seen prior to morphological and molecular markers of cell death. Significant differences were detected in individual choline containing metabolites (CCMs), emphasising the importance of identifying CCMs separately. Alterations were also detected in lactate, alanine, glycine, glutamate, and succinate levels, suggesting changes in the energy metabolism pathways which may provide novel biomarkers in vivo. ¹H HR-MAS NMR reveals alterations in lipids and metabolites during cytostasis and cell death which may provide early markers of treatment efficacy.

T cell antigen receptors (TCRs) on CD8+ T cells recognise endogenously processed peptides bound to major histocompatibility complex (pMHC) antigens presented on the cell surface on almost all types of cells in the body, including tumour cells. The majority of tumour-associated peptide antigens (TAPAs) are derived from non-mutated self-proteins and are therefore subject to immunological tolerance, mainly through negative selection of high avidity T cells in the thymus. In addition, there is low presentation of pMHC on the surface of cancer cells. As a result, T cell responses tend to be weak and ineffective at killing tumour cells. ImmTACs (Immune mobilising monoclonal T cell receptors Against Cancer) are bispecific soluble biologics comprising a soluble TCR with an enhanced affinity for tumour-associated pMHCI fused to a humanised anti-CD3 single-chain antibody fragment (scFv) which redirect and activate T cells to lyse tumour cells. In this study, the potency, sensitivity, and specificity of ImmTACs was investigated for pMHCI epitopes derived from four tumour associated antigens (TAAs): (1) gp100, (2) MAGE-A3, (3) Melan-A/MART-1, and (4) NY-ESO-1/LAGE-1. A comprehensive range of assays and methodologies have been established to characterise the ImmTAC reagents. Cytokine release assays such as IFN-γ and Granzyme B ELISpot were used to evaluate the specificity and biological activity of ImmTACs. In concentration-response experiments, all four ImmTACs produced EC50 values in the range of 100 picomolar or lower demonstrating a high degree of sensitivity despite low epitope numbers. Killing assays, including LDH-release for assessing short-term lysis and IncuCyte technology to visualise long-term killing kinetics in real time, show that redirected T cells potently kill their targets. Furthermore, in vitro screening against a panel of antigen negative, primary human cell lines have shown that ImmTACs are highly specific and only activate T cells against target cells presenting their cognate pMHC. The potency of ImmTACs was also investigated using tumour infiltrating lymphocytes (TILs) extracted from tumour specimens and with tumour-derived cancer cells as targets. An HLA-A2, gp100 specific ImmTAC has received phase I clinical trial regulatory approval in the UK and in the US on the basis of this in vitro data, which has been used to determine minimal anticipated biological effect level (MABEL). The clinical trial is currently in progress.

The field of cancer research has grown immensely in recent decades and has led to a better understanding of the causes of the disease, as well as greatly improved treatment for various types of cancers, especially breast cancer. One of the most effective treatments involves the chemotherapeutic drug doxorubicin (DOX). DOX is an effective tool against all types of breast cancer, especially against triple negative breast cancer. However, DOX causes adverse side effects that include damage to the heart and skeletal muscle, particularly above specific cumulative doses. Recent evidence suggests that embryonic stem cell-derived (ES) exosomes, nanoscale extracellular vesicles that carry proteins, messenger RNA, and microRNAs, may be able to mitigate some of the cardio- and cytotoxic effects of DOX without reducing its efficacy. The present study examined the effects of combined treatment with DOX (1 μM) and ES exosomes (10 μg/mL) on three cancer cell lines, MCF7, MDA-MB-231, and MDA-MB-468. The DOX/ES exosomes treatment increased cell death and increased apoptosis specifically compared to control, as measured via dye exclusion assay and flow cytometry. The treatment also decreased cell growth compared to control, as measured via MTS cell proliferation assay. In addition, DOX/ES exosomes treatment also increased expression of pro-apoptotic Bax while decreasing the expression of anti-apoptotic Bcl-2, as measured via Western blot. Finally, the DOX/ES exosomes treatment decreased expression of miR-200c, a microRNA associated with preventing epithelial-mesenchymal transition, a process that is integral to metastasis. Although increased cell death and apoptosis and decreased cell proliferation implies that the DOX/exosomes treatment is effective against cancer, the decrease in miR-200c expression may suggest the opposite and will be investigated further in future studies. Even so, the results of this study suggest that exosomes may be an important component to reduce the harmful effects of cancer treatment in the future.

Yearly, 22, 200 Canadians are diagnosed with lung cancer, with 80-85% of the cases being non-small cell lung cancer (NSCLC). With diagnoses being predominantly in the advanced stages, prognosis is poor and quality of life (QoL) becomes the focus of treatment. The main symptom cachexia, issues a loss of strength and impacts on an important aspect of QoL, physical function. Physical function is predominately assessed subjectively. Lately performance-based measures are gaining in popularity. One performance measure, the chair rise test, has not been validated in the NSCLC population and was the objective of this study.
Subjects completed the chair rise test, 6MWT, hand grip, and the SF-36 pre and post chemotherapy. Evidence for construct and discriminant validity but not predictive validity was provided for the chair rise test. The 60-second chair rise may be too strenuous for persons with severe disability but a standardized timed-based chair rise test is needed.

The role of neurofibromin, the product of the Neurofibromatosis Type 1 (NF1) gene, in cell physiology is still not well understood. Considering the different traits associated to NF1 it is clear that neurofibromin participates in processes of proliferation and differentiation of different cell types. The Ras-GAP activity of neurofibromin is its best characterized biochemical function, which is regulated by the alternative splicing of exon 23a (E23a). In this thesis we intended to better understand the role of alternative splicing of E23a during neuronal differentiation, with the aim that in the future it could provide information on the learning and cognitive issues related to this disease. Due to the large size of neurofibromin, the difficulty of manipulating it in vitro and the necessity to mimic, as much as possible, the physiological conditions of the cell, we used Phosphorodiamidate Morpholino Oligomers (PMOs) to modify the exonic composition of NF1 mRNA while preserving the endogenous neurofibromin expression levels. We developed a PMO-based system that successfully allowed to force the expression of type II (+E23a) or type I (-E23a) isoforms without altering the physiological expression levels of NF1 mRNA in PC12 cells, a neuronal differentiation model, in the presence or absence of Nerve Growth Factor (NGF). This PMO system could be used in other cellular models of NF1, and could be reproduced for studying the regulation of the alternative splicing in other genes. Furthermore, we set up a group of functional assays for assessing proliferation, differentiation, signaling and apoptosis in this PC12 neuronal model. Our results showed that forcing type I (-E23a) isoform was not sufficient for inducing PC12 neuronal differentiation in the absence of NGF. However, the results also demonstrate that any alteration of the NGF-induced ratio between type I/II isoforms, either in a quantitative or time-dependent manner, interfered with the correct neuronal differentiation process, in particular, altering the correct formation of neurites, as well as the proper regulation of the RAS/MAPK and cAMP/PKA signalling pathways. Moreover, the alteration of the natural E23a alternative splicing also impeded the proper neuronal differentiation process in other neuronal models, such as the H19-7 hippocampus cells. Our results also showed that the depletion of neurofibromin in PC12 induce a generalized process of apoptosis; suggest the existence of an early negative feed-back on the function of neurofibromin when type I isoform is abnormally expressed, and shows that the regulation of the cAMP/PKA pathway is also dependent on the GAP domain of neurofibromin. All together, the results of this thesis indicate that the regulation of the alternative splicing of exon 23a of the NF1 gene allows the fine-tuning of the RAS/MAPK and cAMP/PKA pathways through its GAP activity in a coordinate and opposite way along the time-dependent process of neuronal differentiation.
La neurofibromina és el producte del gen NF1, que mutat causa la Neurofibromatosis de tipus 1. Tot i que en l'actualitat, encara ens cal entendre millor el rol d'aquesta proteïna en la fisiologia cel•lular, l'activitat Ras-GAP és la funció bioquímica més ben caracteritzada de la neurofibromina. Aquesta funció està regulada per l'splicing alternatiu de l'exó 23a (E23a). En aquesta tesi ens vàrem proposar comprendre millor el paper d'aquest splicing alternatiu durant el procés de diferenciació neuronal, amb l'objectiu de proporcionar nova informació sobre els problemes cognitius i d'aprenentatge associats a aquesta malaltia. Degut a la gran grandària de la neurofibromina i a la dificultat de manipular-la in vitxo, es varen utilitzar Phosphorodiamidate Morpholino Oligomers (PMOs) per modificar la composició exònica del mARN (per tant l'estructura resultant de la neurofibromina) sense alterar les condicions fisiològiques d'expressió del gen NF 1 . Es va desenvolupar un sistema basat en PMOs per forçar l'expressió de l'isoforma tipus II (+E23a) o tipus I (-E23a) del gen NF1 en cèl•lules PC12, un model de diferenciació neuronal, en presència o absència de Nerve Growth Factor (NGF). A més, per entendre la importància de 1'E23a es va establir un grup de metodologies i assajos funcionals per poder determinar diferents respostes cel•lulars i valorar la funció d'aquest en el procés de diferenciació neuronal. Els nostres resultats van mostrar que forçar l'isoforma tipus I (-E23a) no era suficient per induir la diferenciació de les cèl•lules PC12 en absència de NGF. No obstant això, qualsevol alteració en la relació entre les isoformes tipus I/II en presència de NGF, ja sigui d'una manera quantitativa o dependent del temps, interferia en el correcte procés de diferenciació neuronal, en particular, alterant la correcta formació de neurites, així com l'adequada regulació de les vies de senyalització RAS/MAPK i cAMP/PKA. En conjunt, els resultats d'aquesta tesi indiquen que la regulació de l'splicing alternatiu de 1'E23a del gen NF1 permet un ajust fi de les vies RAS/MAPK i cAMP/PKA a través de la activitat GAP de la neurofibromina, d'una forma oposada i coordinada al llarg del temps durant el procés de diferenciació neuronal.

Autophagy is a cellular process that delivers cytoplasmic materials for degradation by the lysosomes. Autophagy-related (Atg) genes were identified in yeast genetic screens for vehicle formation under stress conditions, and Atg genes are conserved from yeast to human. When cells or animals are under stress, autophagy is induced and Atg8 (LC3 in mammal) is activated by E1 activating enzyme Atg7. Atg8-containing membranes form and surround cargos, close and mature to become the autophagosomes. Autophagosomes fuse with lysosomes, and cargos are degraded by lysosomal enzymes to sustain cell viability. Therefore, autophagy is most frequently considered to function in cell survival. Whether the Atg gene regulatory pathway that was defined in yeast is utilized for all autophagy in animals, as well as if autophagy could function in a cell death scenario, are less understood. The Drosophila larval digestive tissues, such as the midgut of the intestine and the salivary gland, are no longer required for the adult animal and are degraded during the pupal stage of development. Cells stop growing at the end of larval development, and proper cell growth arrest is required for midgut degradation. Ectopic activation of the PI3K/Akt signaling induces cell growth and inhibits autophagy and midgut degradation. Down regulating PI3K/Akt pathway by Pten mis-expression activates autophagy. In addition, mis-expression of autophagy initiator Atg1 inhibits cell growth and knocking down autophagy restore PI3K/Akt activity. Together, these results indicate that autophagy and growth signaling mutually inhibit each other. Midgut destruction relies on the autophagy gene Atg18, but not caspase activation. The intestine length shortens and the cells undergo programmed cell size reduction, a phenomenon that also requires Atg18, before cell death occurs during midgut destruction. To further investigate whether cell size reduction is cell autonomous and requires other Atg genes, we reduced the function of Atg genes in cell clones using either gene mutations or RNAi knockdowns. Indeed, many Atg genes, including Atg8, are required for autophagy and cell size reduction in a cell autonomous manner. Surprisingly, Atg7 is not required for midgut cell size reduction and autophagy even though this gene is essential for stress-induced autophagy. Therefore, we screened for known E1 enzymes that may function in the midgut, and discovered that Uba1 is required for autophagy, size reduction and clearance of mitochondria. Uba1 does not enzymatically substitute for Atg7, and Ubiquitin phenocopies Uba1, suggesting Uba1 functions through ubiquitination of unidentified molecule(s) to regulate autophagy. In conclusion, this thesis describes: First, autophagy participates in midgut degradation and cell death. Second it reveals a previously un-defined role of Uba1 in autophagy regulation. Third it shows that the Atg genes are not functionally conserved and the requirement of some Atg genes can be context dependent.

Autophagy is a cellular process that delivers cytoplasmic materials for degradation by the lysosomes. Autophagy-related (Atg) genes were identified in yeast genetic screens for vehicle formation under stress conditions, and Atg genes are conserved from yeast to human. When cells or animals are under stress, autophagy is induced and Atg8 (LC3 in mammal) is activated by E1 activating enzyme Atg7. Atg8-containing membranes form and surround cargos, close and mature to become the autophagosomes. Autophagosomes fuse with lysosomes, and cargos are degraded by lysosomal enzymes to sustain cell viability. Therefore, autophagy is most frequently considered to function in cell survival. Whether the Atg gene regulatory pathway that was defined in yeast is utilized for all autophagy in animals, as well as if autophagy could function in a cell death scenario, are less understood. The Drosophila larval digestive tissues, such as the midgut of the intestine and the salivary gland, are no longer required for the adult animal and are degraded during the pupal stage of development. Cells stop growing at the end of larval development, and proper cell growth arrest is required for midgut degradation. Ectopic activation of the PI3K/Akt signaling induces cell growth and inhibits autophagy and midgut degradation. Down regulating PI3K/Akt pathway by Pten mis-expression activates autophagy. In addition, mis-expression of autophagy initiator Atg1 inhibits cell growth and knocking down autophagy restore PI3K/Akt activity. Together, these results indicate that autophagy and growth signaling mutually inhibit each other. Midgut destruction relies on the autophagy gene Atg18, but not caspase activation. The intestine length shortens and the cells undergo programmed cell size reduction, a phenomenon that also requires Atg18, before cell death occurs during midgut destruction. To further investigate whether cell size reduction is cell autonomous and requires other Atg genes, we reduced the function of Atg genes in cell clones using either gene mutations or RNAi knockdowns. Indeed, many Atg genes, including Atg8, are required for autophagy and cell size reduction in a cell autonomous manner. Surprisingly, Atg7 is not required for midgut cell size reduction and autophagy even though this gene is essential for stress-induced autophagy. Therefore, we screened for known E1 enzymes that may function in the midgut, and discovered that Uba1 is required for autophagy, size reduction and clearance of mitochondria. Uba1 does not enzymatically substitute for Atg7, and Ubiquitin phenocopies Uba1, suggesting Uba1 functions through ubiquitination of unidentified molecule(s) to regulate autophagy. In conclusion, this thesis describes: First, autophagy participates in midgut degradation and cell death. Second it reveals a previously un-defined role of Uba1 in autophagy regulation. Third it shows that the Atg genes are not functionally conserved and the requirement of some Atg genes can be context dependent.

Integrins have the ability to impact major aspects of epithelial biology including adhesion, migration, invasion, signaling and differentiation, as well as the formation and progression of cancer (Hynes 2002; Srichai and Zent 2010; Anderson et al. 2014). This thesis focuses on how integrins are regulated and function in the context of mammary epithelial biology and breast cancer with a specific focus on the α6 integrin heterodimers (α6β1 and α6β4). These integrins function primarily as receptors for the laminin family of extracellular matrix (ECM) proteins and they have been implicated in mammary gland biology and breast cancer (Friedrichs et al. 1995; Wewer et al. 1997; Mercurio et al. 2001; Margadant and Sonnenberg 2010; Muschler and Streuli 2010; Nistico et al. 2014). The first project investigates how alternative splicing of the α6 subunit impacts the genesis and function of breast cancer stem cells (CSCs). This work revealed that the α6Bβ1 splice variant, but not α6Aβ1, is necessary for the function of breast CSCs because it activates the Hippo transducer TAZ (Zhao et al. 2008a), which is known to be essential for breast CSCs (Cordenonsi et al. 2011). My work also led to the discovery that laminin (LM) 511 is the specific ligand for α6Bβ1 and that autocrine LM511, which is mediated by TAZ, is needed to sustain breast CSCs by functioning as a ‘ECM niche’. An important aspect of this study is the finding that surface-bound LM511 characterizes a small population of cells in human breast tumors with CSC properties. The second project of my thesis concentrated on identifying transcription factors that regulate expression of the β4 subunit. The expression of the α6β4 integrin is repressed during the epithelial-mesenchymal transition (EMT) (Yang et al. 2009) but the contribution of specific transcription factors to this repression is poorly understood. This study revealed that Snai1 is a transcriptional repressor of β4, which is responsible for establishing the PRC2 (Polycomb complex 2)- associated repressive histone mark H3K27Me3. However, I also found that the ability of Snai1 to repress transcription is abrogated by its interaction with Id2. Specifically, I identified the biochemical mechanism for how Id2 regulates Snai1. Id2 binds the SNAG domain of Snai1 that is the docking site for several corepressors (Peinado et al. 2004; Lin et al. 2010b; Dong et al. 2012a). One important consequence of Id2 interacting with Snai1 on the β4 promoter is that it prevents repressive epigenetic modifications. This finding may explain why some epithelial cells express Snai1 and β4 because they also express Id2 (Vincent et al. 2009; Bastea et al. 2012). The repression of the α6β4 integrin during the EMT is consistent with data indicating that this integrin is not expressed in CSCs (Mani et al. 2008; Goel et al. 2012; Goel et al. 2013; Goel et al. 2014). An important question going forward is to understand how the α6β4 integrin contributes to tumor formation. In summary, my thesis provides novel insights into the biology of the α6 integrins that has important implications for the function of these integrins in mammary gland biology and breast cancer, especially our understanding of breast CSCs.

Autophagy is a conserved catabolic process that traffics cellular components to the lysosome for degradation. Autophagy is required for cell survival during nutrient restriction, but it has also been implicated in programmed cell death. It is associated with several diseases, including cancer. Cancer is a disease characterized by aberrant cell growth and proliferation. To support this growth, the tumor cell often deregulates several metabolic processes, including autophagy. Interestingly, autophagy plays paradoxical roles in tumorigenesis. It has been shown to be both tumor suppressive through cell death mechanisms and tumor promoting through its cytoprotective properties. However, the mechanisms regulating the balance between cell death and cell survival, as well as the metabolic consequences of disrupting this balance, are still poorly understood. Autophagy functions in both cell survival and cell death during the development of Drosophila melanogaster, making it an ideal model for studying autophagy in vivo. My research aimed to better understand the regulation and metabolic contribution of autophagy during cell death in Drosophila. I found that the Ral GTPase pathway, important to oncogenesis, regulates autophagy specifically during cell death in Drosophila larval salivary glands. Contrary to previous studies in mammalian cell culture, Ral is dispensable for autophagy induced during nutrient deprivation suggesting that Ral regulates autophagy in a context-dependent manner. This is the first in vivo evidence of Ral regulating autophagy. I found that disrupting autophagy has an extensive impact on an organism’s metabolism. Additionally, I found that autophagy in degrading tissues is crucial for maintaining the fly’s metabolic homeostasis, and that it may be important for resource allocation amongst tissues. This research highlights the importance of understanding how pathways regulate autophagy in different cell contexts and the metabolic outcomes of manipulating those pathways. This is especially important as we investigate which pathways to target therapeutically in an effort to harness autophagy to promote cell death rather than cell survival.

Autophagy is a conserved catabolic process that traffics cellular components to the lysosome for degradation. Autophagy is required for cell survival during nutrient restriction, but it has also been implicated in programmed cell death. It is associated with several diseases, including cancer. Cancer is a disease characterized by aberrant cell growth and proliferation. To support this growth, the tumor cell often deregulates several metabolic processes, including autophagy. Interestingly, autophagy plays paradoxical roles in tumorigenesis. It has been shown to be both tumor suppressive through cell death mechanisms and tumor promoting through its cytoprotective properties. However, the mechanisms regulating the balance between cell death and cell survival, as well as the metabolic consequences of disrupting this balance, are still poorly understood. Autophagy functions in both cell survival and cell death during the development of Drosophila melanogaster, making it an ideal model for studying autophagy in vivo. My research aimed to better understand the regulation and metabolic contribution of autophagy during cell death in Drosophila. I found that the Ral GTPase pathway, important to oncogenesis, regulates autophagy specifically during cell death in Drosophila larval salivary glands. Contrary to previous studies in mammalian cell culture, Ral is dispensable for autophagy induced during nutrient deprivation suggesting that Ral regulates autophagy in a context-dependent manner. This is the first in vivo evidence of Ral regulating autophagy. I found that disrupting autophagy has an extensive impact on an organism’s metabolism. Additionally, I found that autophagy in degrading tissues is crucial for maintaining the fly’s metabolic homeostasis, and that it may be important for resource allocation amongst tissues. This research highlights the importance of understanding how pathways regulate autophagy in different cell contexts and the metabolic outcomes of manipulating those pathways. This is especially important as we investigate which pathways to target therapeutically in an effort to harness autophagy to promote cell death rather than cell survival.

Thesis (MSc (Physiological Sciences))--University of Stellenbosch, 2009.
Breast cancer is currently the primary cause of cancer-related death in women worldwide. Conventional treatments such as radiation and chemotherapy have many deleterious and long lasting side-effects, some of which are permanent, such as infertility. As certain tumour cells can also acquire resistance to chemotherapy, the need for the development of a less severe, yet more effective, targeted anti-cancer treatment exists. Curcumin, a plant polyphenol from Curcuma longa, has long been thought to possess antitumour, antioxidant, anti-arthritic, anti-amyloid, anti-ischemic and anti-inflammatory properties. Numerous studies conducted over the past sixty years confirm this. We aimed at examining the effect of curcumin on cell viability and the different modes of cell death, namely apoptosis, necrosis and autophagy, in the MCF-12A (non-tumorigenic mammary epithelial) and MCF-7 (mammary adenocarcinoma) cell lines. Cells were incubated with different doses of curcumin to evaluate the dose response through a MTT assay. Thereafter, cells were incubated with 200 μM curcumin for 48 hrs and stained with markers and DNA stains for apoptosis (Hoechst, Caspase-3, PARP), necrosis (Propidium Iodide) and autophagy (LC3B and Beclin-1). Cells were examined via fluorescence microscopy, Western Blot- and FACS analyses. MTT results showed no significant decrease in viability in the MCF-12A cell line after curcumin treatment. However, a significant decrease in viability was observed in MCF-7 cells after treatment with 200 μM curcumin (p < 0.05). Treated MCF-7 cells also show clear LC3B expression. FACS results show a significant difference in Hoechst mean fluorescence intensity in MCF-7 cells after curcumin treatment (p < 0.05). This study provides evidence that MCF-7 cells respond to a 200 μM dose of curcumin treatment through metabolic change and induction of the autophagic pathway. The model system used in this study provides groundwork for further cell culture based studies regarding breast cancer and curcumin.

Hepatocyte growth factor (HGF) signaling drives epithelial cells to scatter by breaking cell-cell adhesions and migrating as solitary cells, a process that parallels epithelial-mesenchymal transition. HGF binds and activates the c-Met receptor tyrosine kinase, but downstream signaling required for scattering remains poorly defined. This study addresses this shortcoming in a number of ways.A high-throughput in vitro drug screen was employed to identify proteins necessary in this HGF-induced signaling. Cells were tested for reactivity to HGF stimulation in a Boyden chamber assay. This tactic yielded several small molecules that block HGF-induced scattering, including a calcium channel blocker. Patch clamping was used to determine the precise effect of HGF stimulation on Ca2+ signaling in MDCK II cells. Cell-attached patch clamping was employed to detect Ca2+ signaling patterns, and channel blockers were used in various combinations to deduce the identity of Ca2+ channels involved in EMT. The results of these experiments show that HGF stimulation results in sudden and transient increases in calcium channel influxes. These increases occur at predictable intervals and rely on proper tubulin polymerization to appear, as determined through the use of a tubulin polymerization inhibitor. Though multiple channels occur in the membranes of MDCK II cells, noticeably TRPV4 and TrpC6, it is TrpC6 that is specifically required for HGF-induced scattering. These HGF-induced calcium influxes through TrpC6 channels drive a transient increase in NFAT-dependent gene transcription which is required for HGF-induced EMT. This was determined through the use of luciferase-based NFAT reporter assays and confirmed through confocal immunofluorescence. Using a small-molecule inhibitor of WNK kinase, it was determined that loss of WNK kinase function is sufficient to prevent HGF-induced EMT. Furthermore, patch-clamp analysis demonstrated that WNK kinase significantly increases channel opening at the surface of MDCK cells, indicating a possible mechanism of action for c-Met inhibition, but leaving doubt as to whether WNK kinase is in fact normally involved in c-Met signaling, or whether it is simply permissive.

Gliomas grow in a neuronal environment, but the interactions between glioma cells and peritumoral neurons remain poorly understood. Understanding this complex relationship could add useful information to develop more effective therapeutic approaches for the treatment of this deadly disease. In recent years, the interaction between cancer cells and tumor microenvironment has emerged as one important regulator of tumor progression. Thus, my thesis aimed to investigate the crosstalk between neural peritumoral tissue and glioma cells; in particular, I assessed i) functional impairments of peritumoral tissue occurring during tumor progression and ii) the impact of neural activity on glioma proliferation. To monitor longitudinal changes in network activity, I recorded visual evoked potentials (VEP) and local field potentials (LFP) after transplant of GL261 glioma cells (or PBS) in mouse visual cortex. Gliomas were injected in visual cortex to allow a detailed investigation of peritumoral neurons using several physiological parameters. Thanks to this analysis, I detected a progressive deterioration of VEP amplitudes along with tumor progression and changes in the LFP power spectra typical of focal epilepsy, with an increase of the power of delta band and the deterioration of alpha rhythm in glioma-bearing mice. To understand the molecular alterations that underlie these perturbed patterns of neuronal activity, I analysed the gene expression profile of microdissected peritumoral pyramidal neurons in the cortical superficial layers (i.e., II-III). The data were clear in indicating that glioma induces alterations in both pre- and post-synaptic markers, demonstrating that its progression shapes the network activity of peritumoral areas towards hyperexcitability. Indeed, I recorded the occurrence of seizures in a subset of glioma-bearing animals, finding alterations in the LFP power spectra just before the onset of ictal events. To investigate how levels of cortical activity affects tumor cell proliferation, I inoculated GL261 glioma cells into the mouse neocortex and modulated neuronal activity by different methods. Second, I dissected the role of inhibitory and excitatory circuitries on tumor proliferation and I found that while the activation of excitatory networks exacerbate glioma proliferation (confirming the data in literature), inhibitory circuits decrease GL261 cell proliferation. Based on these data, I investigated whether a sensory stimulation of the visual cortex may also impact on tumor growth. I found that a reduction of visual cortical activity via Dark Rearing enhanced the density of proliferating glioma cells, while a Visual Stimulation had the opposite effect. Intriguingly the effect was region-specific, as visual deprivation had no significant effect on glioma proliferation in motor cortex. I found that local blockade of neurotransmission via administration of the synaptic blocker botulinum neurotoxin A (BoNT/A) enhances glioma cell proliferation, underlying the importance of neural activity in controlling glioma progression. In addition, the stimulation with visual patterns combined with temozolomide treatment delayed the deterioration of visual responses induced by glioma growth. Altogether, these data demonstrate complex effects of different neuronal subtypes and afferent sensory input in the control of glioma proliferation.

Voltage dependent potassium channels are a group of plasma membrane ion channels with a key role in the immune system as the predominant ion channels controlling the resting membrane potential and tuning intracellular Ca2+ signaling in lymphocytes, monocytes, macrophages, and dendritic cells. Leukocytes present a limited Kv repertoire, including Kv1.3 and Kv1.5 channel isoforms. Kv1.3 is expressed in the immune system, and the blockade of this channel is associated with selective inhibition of T cell activation and proliferation. A functional Kv channel is an oligomeric complex composed of pore-forming and ancillary subunits. The KCNE gene family (KCNE1-5) is a novel group of modulatory Kv channel elements expressed in several tissues including leukocytes. KCNE peptides are small single spanning membrane proteins known to modulate Kv channels trafficking and biophysical properties. The hypothesis of the present PhD thesis entitled “Kv1.3 and Kv1.5 channels in leukocytes” was that changes in the channelosome composition by modulating the heterooligomeric combinations of the Kv1.3 channelosome control physiological and neoplastic cell growth as well as leukocyte responses. Evidence suggests that Kv channels are involved in cell differentiation and cell cycle control (because non-specific drugs, such as 4-AP and TEA, impaire proliferation), and they are also known to be remodeled during carcinogenesis. Thus, we elucidated the role of Kv1.3 and Kv1.5 channels in cell growth and their relationship with cancer, in models such as B lymphocytes and lymphomas (non-Hodgkin lymphomas), pancreatic ductal adenocarcinoma (PDAC) and glioblastomas. In spite of its significance, the mechanisms that regulate Kv1.3 and its role in the T cell activation are not well known. To that end, we analyzed the expression of KCNEs ancillary subunits upon different states of activation and proliferation of leukocytes (macrophages, T and B lymphocytes). In addition, recent data from our laboratory demonstrate that KCNE4, acting as a dominant negative ancillary subunit, physically interacts with Kv1.3 inhibiting K+ currents and retaining the channel intracellularly. Therefore, we studied the Kv1.3 modulation by the auxiliary subunit KCNE4 in leukocytes.

This work is focussed on the analysis of breast tumour physiology by pharmacokinetic modelling of dynamic contrast enhanced MRI (DCE-MRI) data. DCEMRI consists of the intravenous bolus injection of a small molecular weight contrast agent into the patient followed by the rapid acquisition of MR images across both breasts. Due to the leaky nature of the lesion microvasculature there is a greater uptake of contrast agent within the tumour than in the surrounding tissues. The dynamic contrast enhanced MR signal curve can be fitted by compartmental analysis providing information linked to the tumour’s permeability and flow. The effect of the DCE-MRI acquisition parameters on the accuracy of the estimated pharmacokinetic quantities was investigated together with the assumptions lying behind the pharmacokinetic model used for the fitting. Contrast enhanced MRI data were also examined using a fractal measure of tumour heterogeneity with the aim of assessing whether this could be a potential predictor of the tumour response to chemotherapy. Among the factors believed to play an important role in terms of tumour treatment is an increased interstitial fluid pressure (IFP) in the central areas of some large tumours. Here DCE-MRI data were analyzed in a way to see whether it could provide any information related to IFP distribution across tumour volumes. Finally, when performing quantitative DCE-MRI, particular care needs to be taken in the choice of an arterial input function (AIF) which accurately describes the passage of the contrast agent bolus at the lesion location. Here a new approach was proposed and demonstrated for the estimation of a tumour capillary input function together with lesion pharmacokinetic parameters. This was achieved by optimizing the capillary input function with a measure of the patient’s cardiac output, a parameter which is expected to vary depending on the patient’s pathology/physiology.

Thesis (PhD)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Introduction Cisplatin has been widely used to treat solid tumours and much success has come from the use of this drug in the treatment of head and neck, ovarian, testicular, cervical and small-cell lung cancers. However, the success of cisplatin treatment is limited due to its dose-limiting toxicity and its resulting side-effects, such as nephro- and ototoxicity. The devastating side-effects induced by cisplatin treatment provided the platform for this study whereby the aim was to lower the concentration of cisplatin while maintaining its cancer-specific cytotoxic action. Equally concerning is, cisplatin resistance which is becoming increasingly common, and this radically limits the clinical efficacy and utility of the drug. Adjuvant therapy has thus become necessary in an attempt to possibly curb or lessen the extent of cisplatin resistance. Due to the large body of evidence implicating the importance of autophagy in cancer, the prospect of targeting this mechanism has generally been accepted. Various chemotherapy agents induce autophagy in cancer cells; however the effect of cisplatin on autophagic induction has not been very well explored. We thus hypothesise that the manipulation of the autophagic pathway will sensitise cancer cells to a low concentration of cisplatin treatment. Furthermore, due to the functional interaction between Bcl-2 and Beclin-1 and its role in the regulation of autophagy, ratio analysis of Beclin-1 to Bcl-2 as means of detecting the role of autophagy within the cell under homeostatic and treatment/stress conditions has been conducted. Additionally, Bcl-2 has a prominent role in the malignant cell and it’s over-expression has been found to confer resistance in a variety of cancerous cell lines. We therefore hypothesise that the silencing of Bcl-2 prior to cisplatin treatment will sensitise cervical cancer cells to apoptosis and increase the Beclin-1/Bcl-2 ratio in favour of apoptosis. Materials and Methods Three human cervical cell lines were used: a non-cancerous ectocervical epithelial cell line (Ect1/E6E7) and two cancerous cervical cell lines (HeLa and CaSki). In order to determine a concentration of cisplatin that was non-toxic to the non-cancerous Ect1/E6E7 cell line, a dose-response was performed. With the use of an autophagy inhibitor (bafilomycin A1) and an autophagy inducer (rapamycin), autophagic flux capacities were assessed in each cell line through the Western blotting technique. In order to assess whether the chosen concentration of cisplatin induced autophagy, flow cytometry with the use of a Lysotracker™ dye was utilised, as well as analysis of autophagy protein levels (LC-3 II, Beclin-1 and p62). Autophagy modulation was achieved through two methods: pharmacological modulation with use of two recognised agents, namely bafilomycin A1 and rapamycin, and biological manipulation with the use of ATG5 and mTOR mRNA silencing. The effects of different treatment regimes on cell death was assessed with the use of PARP and caspase-3 cleavage through Western blotting, caspase-3/-7 activity (Caspase-Glo®), PI inclusion, LDH release and MTT reductive capacity. Additionally the effects of these treatment regimes on cell-cycle progression were also analysed. Beclin-1 and Bcl-2 expression was determined through Western blotting and immunocytochemistry before and after treatment with cisplatin in HeLa and CaSki cells. To assess the reliance of the cervical cancer cells on Bcl-2 after cisplatin treatment, Bcl-2 knock-down was achieved through RNA interference, where after the Beclin-1/Bcl-2 ratio was assessed as well as apoptosis with the use of cleaved PARP analysis (Western blotting) and Caspase-Glo©. For the ex vivo analysis, biopsies were collected from patients undergoing routine colposcopy screenings and hysterectomies at Tygerberg Hospital, Tygerberg, Western Cape. A total of 10 normal, 29 low-grade squamous intraepithelial lesions (LSIL), 33 high-grade squamous intraepithelial lesions (HSIL) and 13 carcinoma biopsies were collected for analysis, where after the expression profiles of two autophagy markers (mTOR and LC-3 II), as well as one anti-apoptotic marker (Bcl-2) were assessed. Protein levels were analysed through Western blot and confirmed through immunohistochemistry. Results Dose-response curves revealed that 15 μM of cisplatin did not induce cell death in the normal cervical epithelial cell line (Ect1/E6E7) and was therefore utilised through-out the remainder of the study. It was additionally determined that the CaSki cells were more resistant to cisplatin treatment when compared to the HeLa and Ect1/E6E7 cells. Autophagic flux analysis revealed that, although all three cell lines were cervix derived, their autophagic flux capacities differed. It was observed that the chosen concentration of cisplatin was able to induce autophagy in all three cell lines, with the HeLa cells demonstrating a particularly pronounced response. Autophagy modulation in conjunction with cisplatin treatment revealed the following: Autophagy inhibition with bafilomycin A1 lead to significant increases in caspase-3 and PARP cleavage and LDH release in both cervical cancer cell lines. The inhibition of autophagy through silencing of ATG5 induced caspase-3 cleavage and agrees with results obtained from pharmacological inhibition of autophagy with bafilomycin A1. In addition to autophagic induction, a low concentration of cisplatin induced the up-regulation of Bcl-2, which when silenced significantly improved cisplatin-induced apoptosis in both cervical cancer cell lines. Analysis of the expression profiles of mTOR and LC-3 in normal, pre-malignant (LSIL and HSIL) and cancerous cervical tissue revealed that autophagy is significantly up-regulated in HSILs and carcinoma of the cervix. Additionally, Bcl-2 expression is significantly increased in cervical carcinoma tissue, which agrees with results from other studies. Conclusion Autophagic flux capacities between the three cell lines investigated, derived from the same organ, differ significantly. This should be taken into consideration when autophagic modulation is being used as an adjuvant treatment. With regard to chemotherapy treatment in cervical cells, a low-concentration of cisplatin significantly induces autophagy in malignant and non-malignant cervix-derived cell lines where it serves a pro-survival mechanism. Inhibition of autophagy with bafilomycin A1 and ATG5 siRNA confirmed this survival effect in both cancerous cell lines where apoptosis was significantly increased. Interestingly, rapamycin pre-treatment together with cisplatin did not induce significant levels of apoptosis in HeLa cells where autophagy induction may have provided additional protection from the cytotoxic effects of cisplatin. Therefore the inhibition of autophagy through pharmacological and biological inhibition improves the cytotoxicity of a low concentration of cisplatin and provides a promising new avenue for the future treatment of cervical cancer. Bcl-2 up-regulation in response to cisplatin treatment also serves as a protective mechanism by which cervical cancer cells survive. The extent of apoptotic cell death observed after biological inhibition of Bcl-2 reiterates the fact that this response may be exploited in order to favour the use of lower concentrations of cisplatin. Analysis of clinical specimens emphasised the value of the in vitro work: Cervical cancer biopsies had increased expression of both LC-3 II and Bcl-2, indicating autophagy induction and apoptosis inhibition, respectively. Thus two novel methods of improving cisplatin cytotoxicity have been demonstrated in the following study. Treatment regimens may administer more frequently and prolonged due to the minimal side-effects that accompanies low-dose cisplatin treatment.
AFRIKAANSE OPSOMMING: Inleiding Sisplatien word algemeen gebruik vir die behandeling van soliede gewasse. Baie sukses is reeds deur die gebruik van díe middel behaal in die behandeling van kop en nek, ovariale, terstikulêre, servikale en klein-sel kankers. Die sukses van Sisplatien-behandeling word wel ingeperk deur die dosis-beperkende toksisiteit en die gevolglike newe-effekte soos nefrotoksisiteit. Hierdie verwoestende newe-effekte wat deur sisplatien behandelings geïnduseer word, het as die platform vir hierdie studie gedien. Die doel was om die sisplatien konsentrasies te verlaag, maar terselfdertyd die kankerspesifieke sitotoksisiteit te behou. Nog ʼn punt van kommer is dat sisplatien-weerstandigheid aan die toeneem is, wat die kliniese effektiwiteit en gebruik van hierdie middel geweldig beperk. Byvoegmiddels het dus noodsaaklik geraak in die poging om die sisplatien-weerstandigheid te verhoed. As gevolg van verskeie bewyse wat die belangrikheid van outofagie in kanker impliseer, is die vooruitsig om hierdie meganisme te teiken, algemeen aanvaar. Verskeie chemoterapeutiese middels induseer outofagie in kanker selle, hoewel die effek van Sisplatien op outofagiese induksie nog nie goed ondersoek is nie. Ons hipotese is dus dat die manipulasie van die outofagiese pad die kankerselle sensitiseer tot ʼn lae konsentrasie van sisplatien. Verder, as gevolg van die funksionele interaksie tussen Bcl-2 en Beclin-1, en hul rol in die regulering van outofagie, is verhouding-analises van Beclin-1 tot Bcl-2 uitgevoer met die doel om die rol van outofagie in die sel onder homeostatiese en behandeling/stres kondisies te bepaal. Verder is Bcl-2 bekend daarvoor om ʼn prominente rol te speel in kwaadaardige selle, en die ooruitdrukking daarvan is gevind om weerstandigheid aan te help in ʼn verskeidenheid van kankeragtige sellyne. Ons hipotetiseer dus dat geenonderdrukking van Bcl-2 voor die behandeling met sisplatien die servikale kanker selle sal sensitiseer tot apoptose en ʼn verhoging in die verhouding van Beclin-1/Bcl-2 veroorsaak, wat in die guns van apoptose is. Materiale en Metodes Drie menslike servikale sellyne was gebruik: ʼn nie-kankeragtige servikale epiteel sellyn (Ect/E6E7) en twee kankeragtige servikale sellyne (HeLa en CaSki). Om ʼn konsentrasie van sisplatien te bepaal wat nie-toksies tot die nie-kankeragtige Ect1/E6E7 sellyn is, was ʼn dosisrespons uitgevoer. Met die gebruik van ʼn outofagiese inhibeerder (bafilomycin A1) en ʼn outofagiese induseerder (rapamycin), is die outofagiese-fluks kapasiteite van elke sellyn deur die Western Blotting tegniek geassesseer. Om te bepaal of die gekose konsentrasie van sisplatien outofagie induseer, is vloeisitometrie met ʼn Lysotracker™ kleurstof gebruik, sowel as analises op outofagie proteïenvlakke (LC-3 II, Beclin-1 en p62). Outofagie modulering is behaal deur twee metodes: farmakologiese modulering met twee erkende middels, naamlik bafilomycin A1 en rapamycin, en biologiese manipulasie met die gebruik van ATG5 en mTOR geenonderdrukking. Die effekte van die verskillende behandeling skedules op seldood was geassesseer deur gebruik te maak van PARP en kaspase-3 splitsing deur Western Blotting, kaspase-3/-7 aktiwiteit deur Caspase-Glo ®, PI-insluiting, LDH vrystelling en MTT reduserende kapasiteit. Verder is die effekte van hierdie behandeling skedules op selsiklus progressie ook geanaliseer. Beclin-1 en Bcl-2 uitdrukking was ook bepaal deur Western Blotting en immunohistochemie voor en na behandeling met sisplatien in HeLa en CaSki selle. Om die afhanklikheid van die servikale kankerselle op Bcl-2 na sisplatien behandelings te toets, is Bcl-2 onderdruk deur RNA-inmenging, waarna Beclin-1/Bcl-2 verhouding geassesseer is, sowel as opoptose deur die gebruik van gesplitste PARP analises (Western Blotting) en Caspase-Glo©. Vir die ex vivo analises is biopsies vanaf pasiënte wat roetine kolposkopie en histerektomies ondergaan, verkry (Tygerberg Hospitaal, Tygerberg, Westelike Provinsie). ʼn Totaal van 10 normale, 29 lae-graad plaveisel intraepiteel letsels (LSIL), 33 hoe-graad plaveisel intraepiteel letsels (HSIL) en 13 karsinoom biopsies is verkry vir analises. Die uitdrukkingsprofiel van twee outofagiese merkers (mTOR en LC-3 II), asook een merker vir apoptose (Bcl-2), was geassesseer. Proteïen vlakke was ook deur Western Blotting geanaliseer en deur immunohistochemie bevestig. Resultate Dosisrespons kurwes het getoon dat 15 μM sisplatien nie seldood in die normale sellyn (Ect1/E6E7) geïnduseer het nie, en was daarom gebruik deur die res van hierdie studie. Verder is daar ook gevind dat CaSki selle meer weerstandig tot sisplatien behandelings is wanneer vergelyk word met die HeLa en Ect1/E6E7 selle. Outofagiese-fluks analises het getoon dat, alhoewel al drie sellyne vanaf die serviks afkomstig is, daar verskille is in hul outofagiese-fluks kapasiteit. Daar is ook waargeneem dat die gekose konsentrasie van sisplatien in staat was om outofagie te induseer in al drie sellyne, met HeLa selle wat die mees merkbare respons getoon het. Modulering van outofagie in samewerking met sisplatien behandelings het die volgende onthul: inhibisie van outofagie deur bafilomycin A1 het gelei tot ʼn beduidende verhoging in kaspase-3, PARP splitsing en LDH vrylating in beide servikale kankersellyne. Geenonderdrukking van ATG5 induseer kaspase-3 splitsing en stem ooreen met resultate wat verkry is deur farmakologiese inhibisie van outofagie met bafilomycin A1. Bykomend tot outofagiese indusering, het ʼn lae konsentrasie sisplatien die opregulering van Bcl-2 geïnduseer. Wanneer Bcl-2 geenonderdrukking in hierdie scenario toegepas was, het dit ʼn beduidende verbetering in sisplatien-geïnduseerde apoptose in beide servikale kankersellyne getoon. Analises van die uitdrukkingsprofiel van mTOR en LC-3 in normale, pre-maligne (LSIL en HSIL) en kankeragtige servikale weefsel, het getoon dat outofagie beduidend opgereguleer is in HSILs en servikale karsinome. Verder is Bcl-2 uitdrukking ook gevind om beduidend verhoog te wees in servikale karsinoomweefsel, wat ooreenstem met resultate verkry in ander studies. Gevolgtrekking Outofagiese-fluks kapasiteite tussen die drie sellyne, afkomstig van dieselfde orgaan, toon beduidende verskille. Hierdie bevinding moet in ag geneem word wanneer outofagiese-modulering as ʼn bevorderingsbehandeling gebruik word. Met betrekking tot chemoterapie behandeling in servikale selle; ʼn lae konsentrasie van sisplatien veroorsaak ʼn beduidende indusering van outofagie in kwaadaardige en nie-kwaadaardige serviks-afkomstige sellyne, en dien as ʼn oorlewingsmeganisme. Inhibisie van outofagie met bafilomycin A1 en ATG5 siRNA het hierdie beskermings effek bevestig, aangesien apoptose beduidend verhoog was in beide kankersellyne. Interessant genoeg het rapamycin pre-behandeling tesame met sisplatien nie beduidende vlakke van apoptose in HeLa selle geïnduseer nie. Outofagie induksie mag dalk addisionele beskerming teen die sitotoksiese effekte van sisplatien gebied het. Daarom het die inhibisie van outofagie deur farmakologiese en biologiese inhibering die sitotoksisiteit van ʼn lae konsentrasie sisplatien bevorder, wat ʼn belowende bevinding is vir die toekomstige behandeling van servikale kanker. Bcl-2 opregulering as gevolg van sisplatien behandelings dien ook as beskermings meganisme waarby servikale kankerselle oorleef. Die mate van apoptotiese seldood wat waargeneem word na biologiese inhibering van Bcl-2, wys weer op die feit dat hierdie respons uitgebuit kan word vir die gebruik van laer konsentrasies van sisplatien. Analises van die kliniese monsters het ook die waarde van die in vitro werk versterk: Servikale kanker biopsies het verhoogde uitdrukking van beide LC-3 II en Bcl-2 getoon, wat aandui dat outofagie geïnduseer en apoptose geïnhibeer word. Daar is dus twee nuwe metodes vir die verbetering van sisplatien-toksisiteit in hierdie studie gedemonstreer. Behandeling regimes kan meer gereeld en vir langer tydperke toegepas word, aangesien die newe-effekte van lae-dosis sisplatien behandelings minimaal is.
MRC for funding

La adherencia a la Dieta Mediterránea se ha asociado a una disminución de enfermedades de alta prevalencia como el cáncer colorrectal, y este hecho se ha relacionado con el consumo moderado de vino y aceite de oliva, que son dos alimentos característicos de la Dieta Mediterránea. Ambos alimentos son una mezcla compleja de numerosos componentes con estructura y características fisicoquímicas diversas, entre los que destacan los polifenoles. Los estilbenos y los tirosoles son polifenoles que se encuentran presentes en pocos alimentos, entre los que se incluyen el vino y el aceite de oliva. El objetivo de este trabajo ha sido estudiar el papel de componentes bioactivos del vino y el aceite de oliva en el control del crecimiento de células epiteliales intestinales. Para ello, como modelo experimental se utilizó una línea celular procedente de un adenocarcinoma humano denominada Caco-2. El resveratrol (RV), que es un polifenol representativo del vino, es capaz de regular el crecimiento de las células epiteliales intestinales in vitro a concentraciones que no se alcanzan en plasma tras un consumo moderado de vino, dado que esta molécula se metaboliza muy rápidamente. En este sentido, los resultados muestran que los metabolitos sulfatados y glucuronidados del RV mantienen la capacidad antioxidante de este, así como la de inhibir el crecimiento y de inducir apoptosis. El trans-piceido, que es el glucósido del RV presente en concentraciones elevadas en el vino, presenta un efecto antioxidante, una actividad antimitogénica y pro-apoptótica sobre las células Caco-2 similar a la del RV. Además se observó que la capacidad antioxidante del RV está relacionada con la presencia de grupos hidroxilo en posición 3, 5 y 4’. Aunque es este último hidroxilo el determinante de dicha actividad antioxidante. La sustitución de estos hidroxilos por grupos cloro o metoxi, a pesar de reducir su actividad antioxidante, conserva sus efectos biológicos sobre el crecimiento de las células Caco-2. Los ácidos grasos monoinsaturados, y en especial el ácido oleico, que es el ácido graso mayoritario del aceite de oliva, inducen el crecimiento de las Caco-2, probablemente a través de la síntesis de metabolitos por la vía de las lipoxigenasas. Algunos ácidos grasos poliinsaturados, como el eicosapentaenoico y el docosahexaenoico, presentaron un efecto dual, ya que a baja concentración indujeron la proliferación celular, pudiendo estar implicados en este efecto las prostaglandinas y los ácidos hidroxieicosapentaenoicos. Mientras que una concentración alta de estos ácidos grasos poliinsaturados tuvo un efecto opuesto sobre el crecimiento celular e indujo apoptosis. Es interesante señalar que el efecto mitogénico del ácido oleico fue revertido por diversos componentes minoritarios del aceite de oliva como el hidroxitirosol, la oleuropeina, el escualeno, el ácido maslínico y el pinoresinol. Algunos de los cuales inhibieron la liberación de ácido araquidónico y la síntesis de eicosanoides, elementos implicados en el control del crecimiento de las células epiteliales intestinales. En conclusión, la cantidad y el tipo de ácidos grasos consumidos junto con los componentes minoritarios del vino y del aceite de oliva, así como sus metabolitos, pueden tener un importante papel en el control de la cascada del ácido araquidónico y de la proliferación de células epiteliales intestinales Caco-2.
Adherence to Mediterranean Diet has been associated with colorectal cancer prevention, this fact has been linked to moderate consumption of wine and olive oil, two characteristic foods of Mediterranean Diet. Both are a complex mixture of components among which polyphenols stand out. Stilbenes and tyrosols are polyphenols present in wine and olive oil. The objective of this work was to study the effect of bioactive components of wine and olive oil on intestinal epithelial cell growth. For this purpose, Caco-2 cells ware used as experimental model. Resveratrol (RV), a polyphenol representative of wine, is able to regulate intestinal epithelial cells growth in vitro and sulphated and glucuronidated RV metabolites maintain their antioxidant, antiproliferative and apoptotic activity. Trans-piceid is the RV aglycone more present in wine, has antioxidant, anti-mitotic and pro-apoptotic effect similar to that of RV. The antioxidant capacity of RV is related to the presence of hydroxyl groups in 3, 5 and 4 'position, been the last determinant for this activity. The substitution of these hydroxyls for chloro or methoxy groups, despite reducing their antioxidant activity, retains its biological effects on Caco-2 cells growth. Monounsaturated fatty acids, and especially oleic acid, which is the major fatty acid in olive oil, induce Caco-2 cell growth, probably through the synthesis of metabolites from lipoxygenase pathway. Some polyunsaturated fatty acids (PUFA), such as eicosapentaenoic and docosahexaenoic, had a dual effect, since at low concentration they induced cell proliferation, while at high concentration these PUFA had an opposite effect on cell growth and induced apoptosis. Is interesting to note that the mitogenic effect of oleic acid was reversed by some minor components of olive oil such as hydroxytyrosol, oleuropein, squalene, maslinic acid and pinoresinol. Some of which inhibited the release of arachidonic acid and the synthesis of eicosanoids, elements involved in the control of intestinal epithelial cells growth. In conclusion, the amount and type of fatty acids consumed together with minor components of wine and olive oil, as well as their metabolites, may play an important role in arachidonic acid cascade regulation and intestinal epithelial Caco-2 cell proliferation.

Thesis (MTech (Biomedical Technology))--Cape Peninsula University of Technology, 2015.
Cancer is the leading cause of death in both developed and developing countries. In particular, breast cancer is regarded as the most common neoplastic disease in females and accounts for the high mortality rates in women. Increased mortality rates could be attributed to ineffective current cancer treatment modalities that have been implicated to cause multidrug resistance, high toxicity and induction of several side effects. In addition, oxidative stress appears to play a role in the development of breast cancer. Therefore, current cancer research aims to search for plant based anticancer compounds with less side effects and toxicity towards the human body. An example of such a plant is Hibiscus sabdariffa also known as roselle and is reported to have bioactive compounds that exhibit anticancer and antioxidant effects. However, the effects of Hibiscus sabdariffa on breast cancer in relation to oxidative stress and apoptosis have not been investigated. In this research study, the aim was to evaluate the cytotoxic and antioxidant effects of water and methanolic extracts of Hibiscus sabdariffa (HS) on cancerous MCF7 and non-cancerous MCF12A breast cell lines with special reference to oxidative stress and apoptosis. This was done based on the fact that HS has been documented for its traditional use against cancer and other ailments.

Thesis (MSc)--University of Stellenbosch, 2006.
ENGLISH ABSTRACT: Introduction: The ability of different polyunsaturated fatty acids (PUFAs), especially n-3 PUFAs, to prevent the development of cancer has been under intense investigation the past three decades. Numerous studies have shown that these fatty acids can kill cancer cells in vitro as well as in vivo whilst normal cells remain unaffected. Unfortunately, the cellular and molecular mechanisms responsible for this phenomenon are still poorly understood. This study investigated the signalling pathways modulated by docosahexaenoic acid (DHA) in an adenocarcinoma cell line, in order to shed some light on these unknown mechanisms. Materials & Methods: NCM460 (normal colon epithelial) and CaCo2 (colon adenocarcinoma) cells were cultured and treated with low doses of palmitic acid (PMA), oleic acid (OA), arachidonic acid (AA), and DHA. The effects of these fatty acids on the proliferation of the cells were measured with the MTT assay. The composition of membrane phospholipids of CaCo2 cells was determined after 48h supplementation with different fatty acids by gas chromatography. Also, CaCo2 cells were treated with DHA (10 μM) only and proteins were harvested at fixed time points ranging from 2 minutes to 48 hours. The protein inhibitors wortmannin (PI3 kinase inhibitor), PD 98059 (MEK inhibitor) and SB 203580 (p38 inhibitor) and also RNA interference (RNAi) of the p38 MAPK protein were used to investigate cross-talk between signalling pathways. ERK, p38 MAP kinase, Akt, and p53 were then analysed by Western blotting using phospho-specific and total antibodies. The cleavage of the apoptotic proteins, caspase-3 and PARP were also analysed. Results and discussion: MTT assays revealed that none of the fatty acids were toxic to normal cells. In addition, DHA was shown to be most effective to kill CaCo2 cells whilst protecting NCM460 cells and a subsequent dose response experiment revealed that lower concentrations are most suitable for this purpose. DHA was also shown to be readily incorporated into phospholipids, along with AA. This is associated with increased membrane fluidity, which could affect the localisation, and downstream effects, of various signalling proteins within the membrane. Western blot analysis revealed a rapid increase in activity in most proteins under investigation, especially ERK and Akt (Ser473). Long-term DHA supplementation suppressed the full activation of Akt. This down regulation of survival signalling could lead to cell death in CaCo2 cells. In addition, it was shown that after 48h, DHA induced the cleavage of caspase-3 and PARP, which is indicative of apoptosis. RNAi experiments suggested a possible role for p38 MAPK in the phosphorylation of p53 at Ser15, a site which is associated with DNA damage. Conclusion: DHA exerts its effects by means of cellular signal transduction pathways, particularly by suppression of the important survival-related kinase, Akt. This could have implications for future therapeutic interventions in cancer patients, as fatty acids are safe to use and do not interfere with the functionality of normal tissue.
AFRIKAANSE OPSOMMING: Inleiding: Die vermoë van verskillende poli-onversadigde vetsure (POVSe), veral n-3 POVSe, om die ontstaan van kanker te voorkom, is intens nagevors die afgelope drie dekades. Menigte studies het aangevoer dat hierdie vetsure kankerselle in vitro asook in vivo kan doodmaak, terwyl normale selle nie daardeur beïnvloed word nie. Ongelukkig word die sellulêre and molekulêre meganismes onderliggend tot hierdie verskynsel nie goed begryp nie. Hierdie studie het verskeie seintransduksie-paaie wat deur dokosaheksaenoësuur (DHS) in ‘n adenokarsinoom sellyn gemoduleer word, ondersoek. Materiale & Metodes: NCM460 (normale kolonepiteel) en CaCo2 (kolon adenokarsinoom) selle is onderhou in ‘n selkultuur-laboratorium en behandel met lae dosisse palmitiensuur (PMS), oleïensuur (OS), aragidoonsuur (AS), en DHS. Die invloed van hierdie vetsure op die proliferasie van die selle is d.m.v. die MTT toets bepaal. The samestelling van membraan-fosfolipiede van CaCo2 selle is na 48h behandeling met die verskillende vetsure bepaal deur middel van gaschromatografie. Die CaCo2 selle is ook met DHA (10 μM) alleenlik behandel en teen vaste tydpunte wat wissel van 2 minute tot 48h, waarna proteïene geëkstraeer is. Die proteïen-inhibitore wortmannin (PI3 kinase inhibitor), PD 98059 (MEK inhibitor), en SB 203580 (p38 inhibitor) asook RNAinterferensie (RNAi) teen die p38 MAPK proteïen is ingespan om oorvleueling tussen seintransduksie–weë te ondersoek. ERK, p38 MAPK, Akt, en p53 is geanaliseer deur middel van die Western–klad metode met fosfo–spesifieke en totale antiliggame. Die kliewing van die apoptotiese proteïene caspase-3 en PARP is ook bepaal. Resultate en bespreking: MTT toetse het ontul dat geen vetsure toksies was vir die normale selle nie. Daar is ook gevind dat DHS die mees effektiewe vetsuur was om CaCo2 selle te dood, terwyl NCM460 selle beskerm word. Gevolglik het ‘n dosis-respons eksperiment getoon dat laer konsentrasies die beste geskik is vir hierdie doel. Daar is ook gevind dat DHA maklik in fosfolipiede geïnkorporeer word, tesame met AS. Dit word geassosieer met verhoogde membraan-vloeibaarheid, wat die ligging, en ook stroom-af werking, van verskeie seintransduksie proteïene in die membraan, kan beïnvloed. Westernklad analises het ‘n vinnige verhoging in die aktiwiteite van die meeste proteïene onder die soeklig, getoon, veral ERK en Akt (Ser473). Langdurige DHS behandeling het die maksimale aktiwiteit van Akt onderdruk. Hierdie afname van oorlewing-gerigte seine kan lei tot seldood in CaCo2 selle. Daar is boonop geving dat DHS die kliewing van caspase-3 en PARP geïnduseer het na 48, wat dui op apoptose. Uit die RNAi eksperiment kon daar ook ‘n moontlike rol vir p38 MAPK in die fosforilering van p53 by Ser15, wat geassosieer word met DNS-skade, getoon word. Gevolgtrekking: DHS beoefen sy effekte deur middel van seintransduksie paaie, veral deur die oorlewing-geassosieerde kinase, Akt, te onderdruk. Dit kan implikasies hê vir toekomende terapeutiese ingrypings in kankerpasiënte, aangesien vetsure veilig is om te gebruik en nie skadelik is vir normale weefsel nie.

Breast cancer is the most common malignant cancer in western countries. It can be classified into various types/stages according to patient age, tumor size, histological grade or hormone receptor status. Obesity is a well-known risk factor of breast tumor. Studies have shown that overweight or obese postmenopausal women have a threefold higher risk to develop breast cancer in comparison to their lean or normal counterparts. There are many mechanisms that can link obesity with breast cancer and one of the major contributors is adipokines. The main focus of this study is adiponectin. Many cellular and animal studies have illustrated the inhibitory action of adiponectin on breast cancer cell proliferation. In this study, the effect of complete loss of adiponectin expression on breast cancer development in Mouse Mammary Tumor Virus-polyomavirus middle T antigen(MMTV-PyVT)mice [PyVT(+/-)]will be investigated. Mice with [ADN(+/+)]or without [ADN(-/-)] adiponectin gene were used for comparison. It was found that PyVT(+/-)ADN(-/-)mice had earlier tumor onset time and larger tumor volume than PyVT(+/-)ADN(+/+) mice. Histological analysis has demonstrated that increased and more dispersed metastasis existed in lung tissue of PyVT(+/-)ADN(-/-)mice in comparing with PyVT(+/-)ADN(+/+)mice. The aggressiveness of adiponectin deficient tumor was preserved after implantation into immune-deficient mice. Gene expression and protein expression studies of PyVT tumor have indicated a different expression level and pattern of two important molecules: P63 and YY1. In conclusion, tumor developed under microenvironment of adiponectin deficient will give rise to a more aggressive tumor. This tumor consistsof modified genotypes and phenotypes that are permanent and can be preserved after re-implantation into immuno-compromised mice.
published_or_final_version
Pharmacology and Pharmacy
Master
Master of Medical Sciences

Cell populations in the human body form highly complex systems, their behavior driven by countless processes within the cells themselves as well as their interactions with each other and their environment. A mathematical approach to describing their emergent phenomena on the tissue level typically requires abstractions of these underlying systems in order to obtain tractable and interpretable models, which in turn often leads to descriptions involving stochastic processes.In this doctoral thesis two such cellular systems are investigated. The first is the human hematopoietic system: the machinery by which precursor cells of the blood are cultivated and matured in the bone marrow. This process is essential to enable mammalian physiology, from providing oxygen-carrying erythrocytes to ensuring regular upkeep and preservation of the immune system. Obtaining a quantitative understanding of key aspects of this system can provide valuable insights and testable predictions concerning the origin and dynamics of various blood-related diseases, however, in vivo studies of maturing blood cells pose significant challenges and in vitro studies provide only limited predictive power. The system’s hierarchical architecture is on the other hand well fit to the application of mathematical techniques relying only on a few basic assumptions and parameters. This research aims to contribute to two broader questions concerning hematopoiesis, the first being “What is the shape of this system?” and the second “How does it behave?”. Both questions must be answered sufficiently before quantitative models can be developed with enough predictive power to aid in clinical research and applications.The second project stems from questions in oncology concerning the locomotive capabilities of various cancerous cell types, but ultimately poses these in a broader context, attempting to understand cell motion in the context of a growing but spatially restricted population. Drawing from the domain of non-equilibrium statistical mechanics applied to actively moving particles, an important goal is to understand the effects of heightened proliferation on the collective motion.
Les populations cellulaires du corps humain forment des systèmes complexes, leur comportement étant déterminé par d'innombrables processus au sein des cellules elles-mêmes ainsi que par leurs interactions entre elles et avec leur environnement. Une approche mathématique de la description de leurs phénomènes émergents au niveau des tissus nécessite généralement l'abstraction de ces systèmes sous-jacents afin d'obtenir des modèles traitables et interprétables, ce qui à son tour conduit souvent à des descriptions impliquant des processus stochastiques. Dans cette thèse de doctorat, deux de ces systèmes cellulaires sont étudiés.Le premier est le système hématopoïétique humain :la machinerie par laquelle les cellules précurseurs du sang sont cultivées et maturées dans la moelle osseuse. Ce processus est essentiel pour permettre la physiologie des mammifères, depuis la fourniture d'érythrocytes porteurs d'oxygène jusqu'à la préservation du système immunitaire. L'obtention d'une compréhension quantitative des aspects clés de ce système peut fournir des informations précieuses et des prévisions vérifiables concernant l'origine et la dynamique de diverses maladies liées au sang. Cependant, les études in vivo de la maturation des cellules sanguines posent des défis importants, et les études in vitro n'offrent qu'un pouvoir prédictif limité. Par ailleurs, l'architecture hiérarchique du système est bien adaptée à l'application de techniques mathématiques reposant uniquement sur quelques hypothèses et paramètres. Cette recherche vise à contribuer à deux questions plus larges concernant l'hématopoïèse, la première étant "Quelle est la forme de ce système" et la seconde "Comment se comporte-t-il ?Ces deux questions doivent recevoir une réponse suffisante avant que des modèles quantitatifs puissent être développés avec un pouvoir prédictif suffisant pour faciliter la recherche clinique et les applications.Le deuxième projet découle de questions en oncologie concernant les capacités locomotrices de divers types de cellules cancéreuses, mais les pose finalement dans un contexte plus large, en essayant de comprendre le mouvement des cellules dans le disposition d'une population croissante mais limitée dans l'espace. En s'appuyant sur le domaine de la mécanique statistique du non-équilibre appliquée aux particules en mouvement actif, un objectif important est de comprendre les effets d'une prolifération accrue sur le mouvement collectif.
Celpopulaties in het menselijk lichaam vormen complexe systemen. Het individuele celgedrag wordt gedreven door zowel talloze processen binnenin de cellen zelf, als door interacties met elkaar en hun omgeving. Een wiskundige beschrijving van fenomenen op het niveau van de weefsels vereist abstracties van deze onderliggende systemen om hanteerbare en interpreteerbare modellen te verkrijgen, waarbij vaak stochastische processen betrokken zijn. In dit proefschrift worden twee van dergelijke cellulaire systemen onderzocht. Het eerste is het menselijke hematopoëtische systeem: de machinerie waarmee voorlopercellen van het bloed worden ontwikkeld in het beenmerg. Dit proces is essentieel om de fysiologie van zoogdieren mogelijk te maken, van het leveren van zuurstofdragende rode bloedcellen tot het onderhoud van het immuunsysteem. Het verkrijgen van een kwantitatief inzicht in aspecten van dit systeem kan waardevolle inzichten en testbare voorspellingen opleveren met betrekking tot de oorsprong en de dynamiek van verschillende bloedgerelateerde ziekten. Echter, in vivo studies van ontwikkelende bloedcellen vormen een aanzienlijke uitdaging en in vitro studies leveren slechts een beperkt voorspellend vermogen op. De hiërarchische architectuur van het systeem verleent zich daarentegen handig naar het toepassen van wiskundige technieken op basis van slechts enkele aannames en parameters. Dit onderzoek heeft als doel bij te dragen aan twee bredere vragen met betrekking tot hematopoëse, de eerste zijnde "Wat is de structuur van dit systeem?" en de tweede "Hoe gedraagt het zich?". Beide vragen moeten voldoende worden beantwoord voordat kwantitatieve modellen kunnen worden ontwikkeld met voldoende voorspellende kracht om klinisch onderzoek te kunnen bijstaan.Het tweede project komt voort uit vraagstukken in de oncologie over de motorische capaciteiten van verschillende kankerceltypes, maar plaatst deze uiteindelijk in een bredere context, waarbij getracht wordt de stochastische beweging van cellen te begrijpen in de context van een groeiende maar ruimtelijk beperkte populatie. Uitgaande van het domein van de niet-evenwicht statistische mechanica toegepast op actief bewegende deeltjes, is een belangrijk doel het begrijpen van de effecten van een verhoogde proliferatie op de collectieve beweging.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished

Successful adoptive immunotherapy (AIT) for cancer relies on the infusion of in vitro expanded, tumor-reactive lymphocytes with a goal of generating productive tumor immunity. Previously, our lab has developed a protocol to activate selectively tumor-reactive T lymphocytes in vitro using two pharmacologic agents, bryostatin-1 and ionomycin. Following the pharmacological stimulation, conventionally, IL-2 is added to stimulate in vitro proliferation. In this report, alternate cytokines from the common cytokine receptor γ-chain family, namely IL-7 and IL-15, were explored as the alternative cytokine supplements. We found that tumor DLN cells activated in vitro with B/I and cultured in IL-7/15 alternate common γ-chain cytokines expanded better than IL-2 cultured cells. Furthermore, immunosuppressive myeloid-derived suppressor cells from the tumor microenvironment were targeted with a chemotherapeutic agent, gemcitabine. Despite combining gemcitabine and the T lymphocytes expanded in IL-7/15, AIT failed to induce regression of large established 4T1 mammary flank tumors.

Abstract: Notch signaling is prominently involved in cell fate decision and growth regulation in metazoan tissues. Because of this, Notch is often upregulated in cancer and current efforts point to developing drugs that block its activation. Notch receptor endocytosis towards acidic compartments is a recently appreciated determinant of signaling activation. The Vacuolar H+ ATPase (V-ATPase) is responsible for acidification of endocytic organelles and recently it has been shown that mutants in V-ATPase subunit encoding genes in model organisms display loss of Notch signaling phenotypes. In the first part of my graduate studies, we aimed at discovering whether pharmacologic reduction of V-ATPase activity affected Notch signaling. We found that administration of BafilomycinA1 (BafA1), a highly specific V-ATPase inhibitor decreases Notch signaling during Drosophila and Zebrafish development, and in human cells in culture. In normal breast cells, we have found that BafA1 treatment leads to accumulation of Notch in the endo-lysosomal system, and reduces its processing and signaling activity. In Notch-addicted breast cancer cells, BafA1 treatment reduces growth in cells expressing membrane tethered forms of Notch, while sparing cells expressing cytoplasmic forms. In contrast, V-ATPase inhibition reduces growth of leukemia cells, without affecting Notch activating cleavage. However, consistent with the emerging roles of V-ATPase in controlling multiple signaling pathways, in these cells Akt activation is reduced, as it is also the case in BafA1-treated breast cancer cells. Our data support V-ATPase inhibition as a novel therapeutic approach to counteract tumor growth sustained by signaling pathways regulated at the endo-lysosomal level. The functions of Notch throughout the life of an individual are varied and complex. This complexity is not sufficiently accounted for by the limited core of known Notch signaling components and a growing body of evidence attributes it to additional factors that determine whether, when and how Notch functions within a given context. Considering this, in the second part of my graduate work, we sought to identify novel genes that might influence Notch. Thus, we performed a high content immunofluorescence-based RNA interference screen of a pharmacologically-relevant subset of the human genome. To this end, we monitored how knockdown of specific genes perturbs the localization of the Notch-1 receptor in human breast cells under resting and signaling conditions. Here we present the screen setup, the primary screen results and the candidate follow-up strategy.

L'hétérogénéité tumorale observée dans le cancer du sein est à l'origine des échecs cliniques malgré un important arsenal thérapeutique. Cette hétérogénéité est expliquée par la présence, au sein de la tumeur d'une population minoritaire de cellules, les cellules souches cancéreuses (CSC). Ces CSC sont responsables des résistances aux traitements conventionnelles entrainant des rechutes et des métastases. Un meilleur décryptage des programmes régulant les propriétés cardinales de ces cellules, autorenouvellement et différenciation, est une étape cruciale pour le développement de nouvelles thérapies. L'identité des CSC est régulée par des mécanismes épigénétiques. Les travaux de cette thèse se sont intéressés à l'étude de deux mécanismes épigénétique: la méthylation de l'ADN et les microARNs. Nous avons d'abord identifié une signature de 68 régions hypométhylées dans les CSC. Cette signature présentait un enrichissement de la voie TGF-ß et avait un impact pronostic sur la survie des patientes. Nous nous sommes ensuite intéressés à la régulation des CSC par les miARNs. Nous avons identifié miR-600, un microARN bimodal, régulant la balance autorenouvellement-différenciation. miR-600 régule la voie Wnt, via SCD1. L'identification de l'axe miR-600/SCD1/Wnt ouvre une nouvelle perspective thérapeutique pour cibler les CSC. Nos travaux ont décryptés de nouveaux programmes épigénétiques régulantl'identité le destin des CSC mammaires. Ces travaux pourront être le terreau du développement de nouvelles approches thérapeutiques pour traiter le cancer du sien
Tumor heterogeneity observed in breast cancer is the main cause of clinical failures despite a significant therapeutic arsenal. This heterogeneity is explained by the presence of a minority population of cells, the cancer stem cells (CSC). CSC are resistant to conventional therapies causing relapse and metastasis. Deciphering programs regulating the cardinal properties of these cells, self-renewal and differentiation, is a crucial step for the development of new therapies. The identity of CSC is regulated by epigenetic mechanisms. The work of this thesis focused on the study of two epigenetic mechanisms: DNA methylation and microRNAs. We first identified a signature of 68 regions hypomethylated in CSC. This signature showed an enrichment of the TGF-ß pathway and had a prognostic impact on patient survival. We then were interested in the regulation of CSC by miRNAs. We identified miR-600, a bimodal microRNAs, regulating the self-renewal-differentiation balance. MiR-600 regulates Wnt pathway via SCD1. The identification of the miR-600/SCD1/Wnt axis opens a new therapeutic perspective to target CSCs. Our work deciphered epigenetic programs, regulating breast CSC-fate and open new perspective to improve breast cancer care

In the mammalian genome, 5‟-CpG-3‟ dinucleotides are frequently methylated, correlating with transcriptional silencing. Genome-wide waves of demethylation are thought to occur only twice during development, in primordial germ cells and in the pre-implantation embryo. They are followed by de novo methylation, setting up a pattern that is inherited throughout development. No global methylation changes are thought to occur during further somatic development, although methylation does alter at gene-specific loci, contributing to tissue-specific patterns of gene expression. Here we studied DNA methylation in differentiating mouse erythroblasts in vivo using several approaches including genomic-scale, reduced representation bisulfite sequencing (RRBS). Surprisingly, demethylation at the erythroid-specific β-globin locus was coincident with a wave of global DNA demethylation at most genomic elements, including repetitive elements and genes silenced in erythropoiesis. Over 30% of total methylation is irreversibly lost during erythroid differentiation. Demethylation occurred through a passive mechanism, requiring the rapid DNA replication triggered with the onset of erythroid terminal differentiation. Global loss of DNA methylation was not associated with a global increase in transcription, as determined by GeneChip analysis. We propose that global demethylation is a consequence of cellular mechanisms required for the rapid demethylation and induction of β-globin and other erythroid genes. Our findings demonstrate that, contrary to previously held dogma, DNA demethylation can occur globally during somatic cell differentiation, providing a new experimental model for the study of global demethylation in development and disease.

Dans différents types de cancers, notamment dans le cancer du sein, il existe une population cellulaire à l’origine des mécanismes de rechute de la maladie plusieurs années après la fin des traitements initiaux, caractérisée par des propriétés de cellules souches et une chimiorésistance unique dont le mécanisme est inconnu. Pour ces raisons il est important de comprendre les mécanismes et de connaître les acteurs physiologiques impliqués à la fois dans la régulation des cellules souches normales et cancéreuses. Le CD10 est une endopeptidase zinc-dépendante capable d’inactiver un certain nombre de peptides impliqués, entre autre, dans le développement de la glande mammaire. Nos recherches ont permis de montrer que la population cellulaire exprimant le CD10 dans la glande mammaire était enrichie en cellules souches/progéniteurs communs précoces/cellules myoépithéliales. Nos résultats suggèrent que l’adhérence des cellules souches au stroma via l’intégrine β1 et le clivage de certains peptides par le CD10 sont des éléments clés du micro-environnement permettant le maintien du réservoir de cellules souches et de progéniteurs précoces dans la glande mammaire. Le tissu adipeux est également un des constituants majeur de l’environnement de la glande mammaire et joue un rôle dans la sécrétion de facteurs de croissances également impliqués dans l’homéostasie du tissu mammaire. Nos résultats ont suggéré qu’en plus de son rôle nourricier, le tissu adipeux pouvait constituer une source potentielle de cellules souches épithéliales luminales pouvant ainsi être considérée comme une nouvelle source cellulaire à l’origine de certains cancers du sein
In breast, the existence of cancer stem cells has been demonstrated and that explain a number of observations as tumour heterogeneity. Other studies have demonstrated the resistance of radio and chemotherapy by different innate or acquired stem cell specific mechanisms that could explain relapse few years after the traitment. For all these reasons, that is very important to understand these mechanisms and to know physiological actors both implicated in the regulation of normal or cancer stem cells. CD10 is a zinc-dependant metallo-endopeptidase that inactivates a number of signalling peptides that could be implicated in mammary growth and differentiation. We have showed that CD10+ cell sorted population is enriched in Stem Cells/Early Common Progenitors/MyoEPithelial cells. We demonstrate that the protease activity of CD10 and the adhesion function of beta1-integrin are required to prevent differentiation of mammary stem cells/early progenitors. Taken together, our data suggest that integrin-mediated contact with the basement membrane and cleavage of signalling factors by CD10 are key elements in the microenvironment that maintains the progenitor and stem cell pools in the mammary gland. Adipose tissue is also a major component of the mammary microenvironment implicated in its homeostasis by the secretion of soluble factors. Our results suggested that the adipose tissue could be considered as a potential source of stem cells that differentiated into the luminal epithelial lineage involved in some breast cancers