Rozprawy doktorskie na temat „Microsatellites instability”
Kliknij ten link, aby zobaczyć inne rodzaje publikacji na ten temat: Microsatellites instability.
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych rozpraw doktorskich naukowych na temat „Microsatellites instability”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj rozprawy doktorskie z różnych dziedzin i twórz odpowiednie bibliografie.
1
Bodo, Sahra. "Induction d'un processus d'instabilité des microsatellites du génome dans des modèles murin et cellulaire : intérêt physiopathologique et clinique". Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066565/document.
Pełny tekst źródłaStreszczenie:
L'inactivation du système MMR (mismatch repair) favorise un processus oncogénique d'instabilité des microsatellites du génome (MSI). Au cours de ma thèse, j'ai étudié d'une part le rôle de l'azathioprine (Aza) dans l'induction de tumeurs MSI chez la souris. Des études épidémiologiques avaient rapporté une corrélation entre l'émergence de cancers MSI tardifs chez l'homme, et la prise au long cours de cet immunosuppresseur dont la cytotoxicité in vitro est médiée par l'activité MMR. Dans une étude dose-réponse, j'ai observé l'émergence de rares lymphomes MSI de survenue tardive chez la souris de génotype sauvage traitée par l'Aza, mais pas par la ciclosporine (autre immunosuppresseur utilisé en comparaison). Ces résultats permettent d'établir in vivo que l'Aza est un facteur de risque pour l'émergence de tumeurs MSI lors d'une exposition prolongée. D'autre part, je me suis intéressée au syndrome CMMRD (constitutional MMR deficiency), une prédisposition majeure et rare, aux cancers MSI. Les patients atteints étant porteurs de mutations germinales bialléliques d'un gène MMR, le diagnostic repose sur le génotypage constitutionnel, une méthode non-contributive quand un variant de signification inconnue est détecté (30% patients). Dans ce contexte, j'ai développé une méthode d'aide au dépistage de ce syndrome chez les sujets à risque, l'hypothèse étant que 2 caractéristiques fonctionnelles des cellules tumorales MMR-déficientes, le phénotype MSI et la tolérance aux agents génotoxiques tels que l'Aza, pouvaient être objectivées dans les tissus sains des patients CMMRD. Mes travaux proposent un test diagnostique sensible et spécifique qui répond aux limites de l'analyse génétiqueInactivation of the MMR (mismatch repair) system promotes the oncogenic process of microsatellite instability (MSI). During my PhD, I firstly investigated the role of azathioprine (Aza) in the induction of MSI tumors in mice. Epidemiological studies reported a correlation between the occurrence of late MSI cancers in humans and long-term treatment with this immunosuppressant whose cytotoxicity was shown in vitro to be mediated by MMR activity. Using a dose-response study, I observed the occurrence of rare late-onset MSI lymphomas in wild-type mice treated with Aza, but not with ciclosporin (another immunosuppressant used for comparison). These results established in vivo that long-term Aza exposure is a risk factor for the emergence of MSI tumors. Secondly, I was interested in the CMMRD syndrome (constitutional MMR deficiency), a major and rare predisposition to MSI cancers. Since CMMRD patients are carriers of biallelic germline mutations of a MMR gene, diagnosis is based on constitutional genotyping, a method that was found non-contributory when a variant of unknown significance is detected (30% patients). In this context, I developed a complementary approach for the detection of this syndrome in at-risk patients, based on the hypothesis that two functional features of MMR-deficient tumor cells, i.e. the MSI phenotype and the tolerance to genotoxic agents such as Aza, can be demonstrated in non-neoplastic tissues of CMMRD patients. We provided a sensitive and specific method that may constitute a valuable tool when diagnosis of CMMRD could not be confirmed by genetic testing
2
Wright, C. M. "The prognostic significance of microsatellite instability in sporadic stage C colorectal cancer". Thesis, The University of Sydney, 2008. https://hdl.handle.net/2123/28955.
Pełny tekst źródłaStreszczenie:
Identification and understanding of the molecular events involved in colorectal
cancer (CRC) pathogenesis should lead to better comprehension of the disease
process, hopefully leading to better prognostic stratification, and as a result more
targeted treatment regimens and improved patient outcomes. A sub group of
sporadic CRC exhibit microsatellite instability (MSI). MSI is seen when the
fidelity of DNA replication is impaired. Cancers may be categorized as MSI-high
(MSI-H), MSI-low (MSI-L), or microsatellite stable (MSS), according to the
degree of MSI exhibited.
This research project was designed to analyse the association between MSI—H and
MSI-L, clinicopathological features and survival in an unselected group of
patients with sporadic Australian Clinicopathological Stage (ACPS) C / American
Joint Committee on Cancer (AJCC) stage III CRC, i.e. patients with lymph node
metastases at the time of surgical resection of their cancer. The criteria used to
determine MSI, specifically the type and number of microsatellite markers used,
were also reviewed.
255 patients who underwent resection for sporadic ACPS stage C CRC were
studied; none of these patients received chemotherapy. Archival normal and
tumour DNA were extracted and amplified by polymerase chain reaction using a
radioactive-labelling technique and a panel of internationally recognised
microsatellite markers. MSI-H was defined as instability in 2 40% of 7 markers,
MSI-L as instability at > 0% but < 40% of 11 markers, and M88 as no instability.
Twenty one MSI-H and 33 MSI-L CRC were identified. Significant results
included that MSI-H tumours are more commonly right sided (p < 0.00001);
larger (p 5 0.0005); more likely to be high grade (p = 0.049); and, after adjustment
for age, sex and other pathology variables, associated with improved survival (p =
0.015). No difference was found between the biological characteristics of MSI-L
and MSS CRC. MSI-L CRC showed a trend towards poorer cancer-specific
survival than MSS CRC but this difference did not reach statistical significance.
Although dependent on the number and type of microsatellites used, similar trends
in the results were seen when different criteria were used to determine MSI.
This study has contributed to the rapidly expanding literature on CRC
carcinogenesis and, at the time completed, was one of the first to show an
association between MSI-H and improved survival in clinicopathological stage C
CRC patients who had not received chemotherapy. It supports the view that
identification of MSI status in patients with sporadic ACPS C / AJCC stage III
tumours may help stratify patients according to prognosis and should be
considered in therapeutic decision making and future trials of adjuvant therapy.
However to accurately determine the clinical usefulness of MSI more precise
standardisation of the definition and methodologies used to identify M81 is
required.
3
Greene, Malorie. "Étude des conséquences génomiques et fonctionnelles de l'instabilité des microsatellites dans le cancer colorectal". Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066592/document.
Pełny tekst źródłaStreszczenie:
L’instabilité des séquences répétées microsatellites du génome (courtes répétitions en tandem d’un à cinq nucléotides) est une conséquence de l’inactivation du système MMR (MisMatch Repair), en charge de la réparation des erreurs produites au cours de la réplication de l’ADN. Cette instabilité est associée à un processus de transformation cellulaire original, observé chez l’homme dans des pathologies tumorales fréquentes, nommées MSI (pour Microsatellite Instability). Les localisations primaires les plus fréquentes de ces tumeurs sont le côlon, l’endomètre et l’estomac. Elles peuvent avoir une origine héréditaire (prédisposition familiale ; syndrome de Lynch et apparentés), mais sont dans la majorité des cas de survenue sporadique. La transformation des cellules MMR-déficientes s’observe dans le contexte de l’accumulation de nombreuses mutations somatiques dans l’ADN tumoral. Certaines ont un caractère oncogénique en favorisant la troncature et la perte de fonction de gènes suppresseurs de tumeur ou apparentés, impliqués dans des voies de signalisations diverses et qui contiennent des microsatellites codants (mutations indels d’une à deux paires de base, décalant le cadre de lecture, fréquemment rapportées dans ces tumeurs). Les travaux présentés dans le cadre de mon doctorat visent à mieux comprendre le rôle de l’instabilité microsatellitaire dans la tumorigenèse MSI. Ils s’inscrivent dans le contexte du décryptage et de l’analyse des données de séquençage d’exome de 47 cancers colorectaux primitifs MSI. Dans le contexte d’un niveau élevé d’instabilité génomique caractérisant ces tumeurs, la mise au point par mon laboratoire d’accueil de modèles probabilistes a permis de dresser une liste restreinte de gènes, remarquables par le fait qu’ils sont affectés par des mutations somatiques dont les fréquences sont exceptionnellement élevées ou basses dans l’ADN tumoral. Sous l’hypothèse que de tels évènements somatiques affectent des gènes clés de la tumorigenèse MSI colique, j’ai focalisé mes recherches sur les gènes dont les altérations sont peu fréquentes. Brièvement, j’ai pu démontrer le caractère délétère d’un petit nombre d’altérations microsatellitaires codantes dont la survenue semble soumise à une pression de sélection négative (N=13). Mes résultats indiquent que ces mutations semblent fragiliser le phénotype tumoral des cellules dans lesquelles elles surviennent, la perte de fonction des gènes qu’elles affectent conduisant à diverses conséquences délétères en fonction du gène candidat (e.g. sensibilisation à la mort cellulaire, perte des capacités proliférative et migratoire, ralentissement de la croissance tumorale). Ces résultats rapportent pour la première fois et à grande échelle, la sélection négative de mutations dans des tumeurs à forte instabilité génomique MSI. Ils ouvrent de nouvelles voies pour la compréhension de ce mode particulier de transformation cellulaire, et sont potentiellement d’intérêt pour la mise au point de thérapies personnalisées pour les patientsSince the discovery of a link between mismatch repair (MMR) deficiency and cancer, microsatellite instability (MSI) is thought as a process underlying cell transformation and tumour progression and invasion. MSI tumours are a subset of frequent human neoplasms, both inherited and sporadic, associated with several primary locations (colon, stomach, endometrium…). In MMR-deficient cells, MSI generates hundreds of frameshift mutations in genes (MSI Target Genes, MSI-TGs) containing coding microsatellite sequences (e.g. -1/+1 bp, insertions/deletions, i.e. indels). Some of these mutations affect genes with a role in human carcinogenesis and are thus expected to promote the MSI-driven tumorigenic process. During my PhD, I aimed to decipher the role of MSI in colon tumorigenesis. I exploited exome-sequencing data available in my lab that were generated from the analysis of a series of 47 human MSI primary colorectal cancer (CRC). Through biostatistics analysis and mathematical models that we designed to interpret mutation rates in the context of the high background for instability characterizing MSI in CRC, we identified a few microsatellites containing genes coding mutations that were negatively selected in MSI colon tumours (N=13). Under the hypothesis that these events may have a negative impact in colon tumorigenesis, I demonstrated that the silencing of these MSI target genes (siRNA/shRNA) was deleterious for MSI cancer cells using in vitro and in vivo models (impairment of proliferation and/or migration and/or response to chemotherapy and/or tumour growth) (Jonchère*, Marisa*, Greene* et al., submitted)
4
Micelli, Lupinacci Renato. "Caractérisation anatomo-clinique et phénotypique des adénocarcinomes canalaires du pancréas avec instabilité des microsatellites". Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066311/document.
Pełny tekst źródłaStreszczenie:
L’adénocarcinome canalaire du pancréas (ACP) est un problème majeur de santé publique. L’ACP se développe principalement à partir de deux lésions précurseurs : les néoplasies intra-épithéliales pancréatiques et les tumeurs intracanalaires papillaires et mucineuses du pancréas (TIPMP). Les mécanismes moléculaires sous-tendant l’oncogenèse pancréatique sont nombreux. Nous avons étudié le mécanisme de cancérogenèse MSI (MicroSatellite Instability) où il existe une déficience dans le système de réparation des erreurs de réplication de l’ADN ou système MMR (Mismatch Repair). Ce mécanisme de cancérogenèse original est caractérisé par une instabilité génétique de l’ADN affectant les séquences répétées microsatellites du génome. Le phénotype MSI a été décrit dans le syndrome de Lynch (SL), dans lequel il existe une mutation germinale d’un des gènes du système MMR (MLH1, MSH2, MSH6 et PMS2). L’intérêt de l’étude des cancers MSI s’est accru de façon considérable avec le développement des immunothérapies dirigées contre les checkpoints immunitaires (ICK), en particulier PD-1/PD-L1. Nous avons confirmé que la fréquence du phénotype MSI se situe entre 1-2%. Nous avons montré que l’immunohistochimie est la méthode de screening plus adaptée pour l’identification de l’ACP MSI en comparaison avec les techniques de biologie moléculaire. Le phénotype MSI a été plus fréquemment observé dans un contexte de TIPMP. Les cas MSI identifiés présentaient des caractéristiques biologiques évocatrices du SL. Egalement, nos résultats confirment la présence d’un processus de carcinogenèse MSI immunogénique, mais suggèrent des évènements somatiques spécifiques à l’organe d’origine du cancer. Par ailleurs, les ACP MSI étaient caractérisés par un infiltrat inflammatoire riche en lymphocytes cytotoxiques T CD8+ et surexprimaient l’ICK PD-L1 permettant de supposer une probable réponse clinique de l’ACP MSI à l’immunothérapie anti-PD1/PD-L1Pancreatic ductal adenocarcinoma (PDAC) is a major health problem in France and around the world. PDAC is developed mainly from two precursor lesions: pancreatic intraepithelial neoplasia and intraductal papillary mucinous neoplasm (IPMN). There are several molecular mechanisms underlying pancreatic oncogenesis. Particularly, we were interested in the MSI (MicroSatellite Instability) which is due to a defective DNA Mismatch Repair (MMR) system, which normally functions to recognize and repair erroneous insertions, deletions, and mis-incorporation of bases that can arise during DNA replication and recombination. The MSI phenotype was first described in the familial cancer condition known as Lynch syndrome (LS), where the MMR genes MLH1, MSH2, MSH6 or PMS2 harbor germline mutations. Interest in MSI tumors has recently increased after studies have highlighted the concomitant expression of multiple active immune checkpoint (ICK) markers including PD-1 and PD-L1 and the role of the MSI status to predict clinical benefit from immune checkpoint blockade. A Our results indicate that the MSI phenotype occurs in PDAC with a frequency of 1-2%. Our data showed that IHC using antibodies against the four MMR proteins was more sensitive for the assessment of MSI status than PCR-based methods. In addition, we demonstrate for the first time a statistically significant positive association between MSI and IPMNs in PDAC. MSI PDAC, including IPMN, are unlikely to be sporadic since they display molecular features that are usually observed in LS-related neoplasms. Also, our results highlight that an MSI-driven immunogenic pathway to cancer is active in MSI PDACs but suggest that MSI-driven somatic events may be tissue-specific. We observed a stronger lymphocytic tumor infiltration by activated TCD8 cells in MSI PDAC compared to MSS PDAC and found a positive association between PD-L1 expression and MSI status, suggesting that MSI PDAC could be responsive to ICK blockade therapy
5
Cohen, Romain. "Caractérisation phénotypique et clinique des cancers colorectaux métastatiques avec instabilité des microsatellites Clinical and molecular characterization of hereditary and sporadic metastatic colorectal cancer harbouring microsatellite instability/DNA mismatch repair deficiency Association of primary resistance to immune checkpoint inhibitors in metastatic colorectal cancer with misdiagnosis of microsatellite instability or mismatch repair deficiency status". Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS313.
Pełny tekst źródłaStreszczenie:
L’instabilité des microsatellites (MSI) est un phénotype tumoral dû à une déficience héréditaire ou acquise du système de réparation des mésappariements de l’ADN (MMR : mismatch repair). Le phénotype MSI est retrouvé dans 5% des cancers colorectaux métastatiques (CCRm) et est un facteur prédictif positif majeur de l’efficacité des inhibiteurs de checkpoints immunitaires (ICKi). L’objectif de mon travail a été de caractériser sur le plan clinique et moléculaire les CCRm MSI, d’en évaluer les modalités diagnostiques et d’évaluer la réponse aux ICKi. Dans un 1er travail, je montre que l’histoire naturelle clinique des CCRm MSI diffère selon le mécanisme sporadique ou héréditaire de la déficience MMR (Cohen et al., Eur J Cancer 2017). Dans un 2e travail, je montre que près de 10% des CCRm détectés comme MSI/MMR-déficients en vie réelle correspondent à des faux positifs des analyses immunohistochimiques et/ou de PCR, et que ces faux positifs sont responsables de la majorité des cas de résistance primaire aux ICKi observés dans les essais cliniques (Cohen*, Hain* et al., JAMA Oncol. 2018). Après une revue de la littérature concernant le phénotype MSI, son impact dans le cadre du CCR et des ICKi, je présente les résultats des travaux développés durant ce doctorat, avant de proposer différentes perspectives à l’ère de l’immunothérapie des cancers MSIMicrosatellite instability (MSI) is a tumor phenotype linked to somatic or germline inactivating alterations of DNA mismatch repair (MMR) genes. MSI is observed in approximately 5% of metastatic colorectal cancers (mCRC) and has recently emerged as a major positive predictive biomarker for the efficacy of immune checkpoint inhibitors (ICKi) amongst mCRC patients. The objectives of my work was to clinically and molecularly characterize MSI mCRC, to evaluate the accuracy of MSI screening methods and the response to immunotherapy in the context of ICKi clinical trials. Fist, I show that sporadic and inherited MSI mCRC display distinct natural history (Cohen et al., Eur J Cancer 2017). In a second work, I show that MSI testing in routine practice is associated with almost 10% of false positives due to misinterpration of IHC and PCR assays. Moreover, these false-positives are the main cause of mCRC primary resistance to ICKi observed in clinical trials (Cohen*, Hain* et al., JAMA Oncol. 2018). After summarizing the literature concerning MSI, its consequences on CRC and immunotherapy, I present the results of the nosologic and diagnostic works developed during this doctoral thesis. Then I will go on perspectives in the context of MSI cancer
6
El-Murr, Nizar. "Étude de l'impact des microARNs sur la carcinogenèse des cancers colorectaux instables sur les séquences répétées microsatellites du génome". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2014. http://tel.archives-ouvertes.fr/tel-00990895.
Pełny tekst źródłaStreszczenie:
La progression tumorale MSI (Microsatellite Instable) est un processus multi-étapes résultant de mutations générées par un processus d'instabilité génétique qui affecte en majorité les motifs répétés en tandem de l'ADN (microsatellites). Ces mutations contribuent à l'oncogenèse lorsqu'elles perturbent la fonction d'oncogènes ou de gènes suppresseurs de tumeurs. Le trait phénotypique MSI est consécutif à l'inactivation du système de réparation des mésappariements de l'ADN (système MMR). Dans ce travail, je me suis intéressé au rôle des microARNs dans l'oncogenèse MSI. Les microARNs régulent l'expression de nombreux gènes pouvant avoir un rôle clé dans le cancer. J'ai donc fait l'hypothèse d'un rôle de ces microARNs lors des différentes étapes du processus tumorigénique MSI. Tout d'abord nous avons mis en évidence une surexpression du miR-155 (ciblant les principales protéines MMR) au niveau de la muqueuse colique non transformée des malades atteints d'une Maladie Inflammatoire Chronique Intestinale, qui pourrait constituer un évènement pré-tumoral favorisant l'émergence de clones MMR-déficients (notion d'effet de champs). Dans une deuxième partie, nous avons pu identifier la première mutation somatique touchant un microARN. Il s'agit du miR-3613 dont la répétition microsatellite est entièrement localisée dans le miR mature. L'instabilité au niveau de ce miR conduit à des changements de séquence à l'extrémité 3' du miR (notion d'IsomiRs). Les isomiRs produits ont un répertoire de cibles qui pour certaines sont communes à la forme sauvage et pour d'autres spécifiques à chacun des variants.
7
Boulagnon-Rombi, Camille. "Etude du récepteur d’endocytose LRP1 dans les adénocarcinomes coliques : caractéristiques cliniques, pathologiques et moléculaires associées et valeur pronostique". Thesis, Reims, 2017. http://www.theses.fr/2017REIMM203/document.
Pełny tekst źródłaStreszczenie:
LRP1 (low-density lipoprotein receptor–related protein 1), un récepteur endocytaire multifonctionnel, a récemment été identifié comme pivot d’un réseau de biomarqueurs pour la prédiction pronostique de plusieurs types de cancers. Son rôle dans le cancer du côlon n'a pas été caractérisé. Notre travail porte sur l’étude de la relation entre expression de LRP1 et cancer du côlon.L'expression de l'ARNm LRP1 a été déterminée dans des échantillons d'adénocarcinome et de muqueuses coliques appariées, ainsi que dans les cellules stromales et tumorales obtenues après microdissection laser. Les associations clinicopathologiques et moléculaires ont été étudiées par immunohistochimie dans une série de cancer colique (n = 307). La présence de méthylation ou mutation du gène LRP1 et l'expression de miR-205 ont été évaluées et comparées aux niveaux d'expression de LRP1.L’ARNm de LRP1 est sous exprimé dans les cellules d'adénocarcinome colique par rapport à la muqueuse colique par rapport aux cellules stromales. La faible expression immunohistochimique de LRP1 dans les adénocarcinomes était associée à un âge plus élevé, à localisation droite, une perte d'expression de CDX2, une expression d'Annexine A10, un statut CIMP-H, MSI-H et BRAFV600E muté. Cette faible expression était associée à un mauvais pronostic, en particulier chez les patients de stade IV. Les mutations du gène LRP1 entrainaient une sous-expression de LRP1. L’expression était peu modifiée par miR-205. Le promoteur de LRP1 n'était jamais méthylé.La perte d'expression de LRP1 est associée à un profil clinico-pathologique et moléculaire particulier et à un un mauvais pronostic dans les cancers du côlonLRP1 (low-density lipoprotein receptor–related protein 1), a multifunctional endocytic receptor, has recently been identified as a hub in a biomarker network for multi-cancer clinical outcome prediction. Its role in côlon cancer has not been characterized. Here, we investigate the relationship between LRP1 and colon cancer.LRP1 mRNA expression was determined in colon adenocarcinoma and paired colon mucosa samples, and in stromal and tumoral cells obtained after laser capture microdissection. The clinical potential was further investigated by immunohistochemistry in a population-based colon cancer series (n = 307). LRP1 methylation, mutation and miR-205 expression were evaluated and compared to LRP1 expression levels.LRP1 mRNA levels are significantly decreased in colon adenocarcinoma cells compared to colon mucosa and stromal cells. Low LRP1 immunohistochemical expression in adenocarcinomas was associated with higher age, right-sided tumor, loss of CDX2 expression, Annexin A10 expression, CIMP-H, MSI-H and BRAFV600E mutation. Low LRP1 expression correlates with poor clinical outcome, especially in stage IV patients. LRP1 expression was downregulated by LRP1 mutation. LRP1 expression was slightly modified by miR-205 expression. LRP1 promoter was never methylated.Loss of LRP1 expression is associated with peculiar clinocopathological and molecular characteristics and with worse colon cancer outcomes
8
Vaysse-Zinkhöfer, Wilhelm. "Mécanismes de réparations d’une cassure double-brin et résection au sein d’un microsatellite humain". Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS477.
Pełny tekst źródłaStreszczenie:
Les microsatellites sont des répétitions en tandem d’un motif compris entre une et neuf paires de bases. Ces répétitions retrouvées dans tous les organismes de façon ubiquitaire, sont particulièrement abondantes dans les organismes eucaryotes. Toutes ces répétitions sont capables de former des structures secondaires in vitro et possiblement in vivo. Certains microsatellites sont enclins à une expansion, conduisant à de nombreuses maladies neurodégénératives chez l’homme telle que la dystrophie myotonique de type 1 (DM1), maladie neurodégénérative la plus fréquemment transmise. L’apparition et la sévérité des symptômes sont positivement corrélée avec le nombre de répétitions, localisées dans le 3’UTR du gène DMPK. Dans des travaux précédents du laboratoire, une TALE nucléase (TALEN) a été élaborée dans le but d’introduire une cassure double-brin au sein d’un microsatellite (CTG)n provenant d’un patient DM1. La compréhension des mécanismes conduisant à la contraction des répétitions chez la levure est nécessaire si l’on souhaite en comprendre les mécanismes chez l’homme. Ainsi, des expériences ont été menées dans des cellules dont les systèmes de réparation des CDB ont été altérés, montrant que RAD51, POL32 et DNL4 n’étaient pas nécessaires à la réparation des CDB au sein des microsatellites. Seul RAD50 et RAD52 semblent nécessaires, indiquant que la cellule répare les CDB dans les régions répétées par single-strand annealing. L’objectif de cette thèse a été d’étudier le rôle de plusieurs gènes (MRE11, EXO1, SGS1, DNA2, SAE2, RIF1 et RIF2), impliqués dans la résection et la réparation d’une unique CDB au sein d’une région répétée CTG, chez la levureMicrosatellites are tandem repeats of a motif between one and nine base pairs. These repeats are found ubiquitously in all organisms and are particularly abundant in eukaryotic organisms. All these repeats are capable of forming secondary structures in vitro and possibly in vivo. Some microsatellites are prone to expansion, leading to many neurodegenerative diseases in humans such as myotonic dystrophy type 1 (DM1), the most frequently transmitted neurodegenerative disease. The onset and severity of symptoms are positively correlated with the number of repeats located in the 3'UTR of the DMPK gene. In previous work in the laboratory, a TALE nuclease (TALEN) was developed to introduce a double-strand break into a microsatellite (GTC)n from a DM1 patient. Understanding the mechanisms leading to repeat contraction in yeast is necessary to understand the mechanisms in humans. Thus, experiments were conducted in cells with altered CBD repair systems showing that RAD51, POL32 and DNL4 were not required for CBD repair within microsatellites. Only RAD50 and RAD52 appear to be required, indicating that the cell repairs CBDs in repeated regions by single-strand annealing. The objective of this thesis was to study the role of several genes (MRE11, EXO1, SGS1, DNA2, SAE2, RIF1 and RIF2), involved in the resection and repair of a single CBD within a CTG repeat region, in yeast
9
Palassin, Pascale. "Etude du rôle du corégulateur transcriptionnel RIP140 dans le contrôle de l'instabilité microsatellitaire des cancers colorectaux héréditaires". Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT054/document.
Pełny tekst źródłaStreszczenie:
Le corégulateur transcriptionnel RIP140 est un facteur ubiquitaire majeur impliqué dans la régulation de nombreux processus physiopathologiques, qui possède la capacité d’être un coactivateur ou un corépresseur des voies de signalisation selon son recrutement sur les gènes cible. Des résultats du laboratoire ont montré que RIP140 est un facteur de bon pronostic de la tumorigenèse intestinale sporadique. Ce travail s’intéresse à l’implication de ce facteur de transcription dans les cancers colorectaux familiaux et, plus particulièrement, en lien avec le syndrome de Lynch (LS). Le syndrome de Lynch est une prédisposition héréditaire aux cancers, majoritairement colorectaux, caractérisés par un défaut du système de réparation des mésappariements de l’ADN (Mismatch Repair, MMR), dû à une première mutation germinale d’un des gènes de ce système. La perte de fonctionnalité MMR est responsable du phénotype d’instabilité microsatellitaire (MSI). Cependant, il existe des formes familiales de cancers colorectaux, avec MSI, où il n’est pas retrouvé d’atteinte germinale ou somatique de l’un des gènes du système MMR. Ce sont les syndromes apparentés au syndrome de Lynch (Lynch Like Syndrome, LLS) dont la prise en charge est identique à celle du LS. L’utilisation de modèles murins et de lignées cellulaires colorectales, présentant des modulations d’expression de RIP140 ont permis de mettre en évidence l’effet positif de ce corégulateur sur la régulation transcriptionnelle de l’expression des gènes du système MMR, MSH2 et MSH6. La validité fonctionnelle de cette régulation a été explorée par des analyses d’instabilité microsatellitaire et de sensibilité à différentes molécules cytotoxiques. Des cohortes de tumeurs ont permis de confirmer la corrélation d’expression entre RIP140 et les gènes MSH2 et MSH6 chez les patients. En outre, la régulation de l’expression par RIP140 d’une polymérase translésionnelle particulière, la polymérase Polκ, a été étudiée. Cette polymérase assure la réplication des séquences microsatellitaires du génome. Nous avons démontré que RIP140 stimule l’expression du gène POLK dans nos modèles cellulaires et que son expression est corrélée à celle de RIP140 au sein des tumeurs colorectales humaines. Enfin, par séquençage de différentes lignées cellulaires, nous avons mis en évidence une mutation de RIP140 qui entraîne un décalage du cadre de lecture et génère une protéine tronquée avec perte de deux domaines répresseurs de la protéine. Un séquençage à très haut débit nous a permis de rechercher cette mutation parmi des échantillons de tumeurs colorectales avec MSI. Cette mutation est retrouvée dans 19% des tumeurs, notamment LLS (16,2%), où elle est associée à une moins bonne survie globale. Elle affecte les propriétés antiprolifératives et transrépressives de RIP140 ainsi que les régulations positives des gènes MSH2, MSH6 et POLK. Le développement d’un outil anticorps spécifique de cette mutation serait extrêmement utile pour suivre l’expression de la forme mutée au sein des tumeurs et des premiers essais ont été réalisés en ce sens. En conclusion de ce travail, RIP140 contrôle l’expression de gènes majeurs impliqués dans le maintien de l’intégrité du génome et une mutation de ce corégulateur transcriptionnel pourrait être responsable de l’instabilité microsatellitaire de certaines tumeurs où des altérations des gènes MMR ne sont pas retrouvées. Des études cliniques sur des cohortes plus conséquentes seront nécessaires pour valider son intérêt en tant que marqueur utilisable dans la prise en charge des patientsThe transcriptional coregulator RIP140 is an ubiquitous cofactor playing a major role in the regulation of many physiopathological processes. It can either act as a coactivator or as a corepressor of signaling pathways depending on its recruitment on target genes. It has been shown that RIP140 is a good prognostic marker in sporadic intestinal tumorigenesis. This work focuses on its role in familial colorectal cancers and particularly in relation to the Lynch syndrome (LS). Lynch syndrome is a hereditary cancer predisposition, mostly colorectal, characterized by a defect in the Mismatch Repair (MMR) system, due to a first germline mutation of one gene of this system. Loss of MMR function induces a microsatellite instability (MSI) phenotype. However, there are some MSI familial colorectal cancers, where neither germinal nor somatic alteration of one MMR gene is found. They are referred to as Lynch like Syndrome (LLS) and their overall management is identical to that of LS. Murine models and colorectal cell lines, harboring modulations of RIP140 expression, allowed us to demonstrate the positive transcriptional regulation of the MMR genes, MSH2 and MSH6 by RIP140. Functional validation of this regulation was explored by microsatellite instability and sensitivity to various cytotoxic drugs analyses. A positive correlation has been confirmed between RIP140 and MSH2 and MSH6 gene expression in a cohort of 396 patients. Moreover, the transcriptional regulation by RIP140 of a specialized translesional DNA polymerase, the Polκ polymerase, has been investigated. Polκ ensures microsatellite sequences replication. We have demonstrated that RIP140 positively stimulates the expression of the POLK gene in our cell models and which appears correlated with that of RIP140 in human colorectal tumors. Finally, by sequencing different cell lines, we found a frameshift mutation of RIP140, generating a truncated protein with loss of the last two repression domains. High-throughput sequencing allowed us to look for this mutation in patient MSI colorectal tumor samples. This mutation was found in 19% of these tumors, especially LLS (16,2%), where it has been associated with lower overall survival. This mutation affects the antiproliferative and transrepressive properties of RIP140, as well as the positive regulation of the MSH2, MSH6 and POLK gene. Development of a specific antibody for this mutation would be extremely useful in following the expression of this mutated form within tumors and first tests have been already carried out. In conclusion, RIP140 controls expression of major genes involved in genome integrity maintenance and a mutation of this transcriptional coregulator could be responsible for microsatellite instability of some tumors where alterations of MMR genes are not found. Clinical studies on larger cohorts will be necessary to validate its interest as a marker usable in patient management
10
Warusavitarne, Janindra. "Analysis of the factors that influence the biological behaviour and response to chemotherapy in sporadic colorectal carcinomas with microsatellite instability". Thesis, The University of Sydney, 2005. https://hdl.handle.net/2123/27920.
Pełny tekst źródłaStreszczenie:
High frequency microsatellite instability (MSI—H) is an alternate pathway of
colorectal carcinogenesis and is present in approximately 15% of all sporadic
colorectal cancers. These tumours are predominantly located in the right colon, occur
mainly in the elderly and have a better prognosis than microsatellite stable (MSS)
CRCs. In addition they are usually of mucinous type histology, tend to be locally
invasive, metastasise less and are of larger size than MSS CRCs.
The mismatch repair (MMR) genes hMLHl is most commonly mutated or methylated
in sporadic colorectal cancers with MSI-H. Several other gene mutations occur as a
result of the defective mismatch repair genes and mutations in a 10 x A repeat region
of the TGFBRII gene occurs in approximately 90% of MSI-H CRCs. TGFB is an
important tumour suppressor and TGFB signalling is impaired in the absence of
TGFBRH. Several studies have shown that restoring TGFB signalling in MSI-H CRC
results in reduced tumorigenicity suggesting that the lack of TGFB signalling may be
responsible for the increased tumorigenicity seen in these CRCs. In breast and
pancreatic cancer TGFB signalling has been associated with an increased metastatic
rate and it is postulated that the lack of TGFB signalling in MSI-H CRC is associated
with the reduced metastatic rate seen in these tumours when compared with MSS
CRCS.
11
Gryfe, Robert. "Colorectal cancer microsatellite instability". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ59033.pdf.
Pełny tekst źródła
12
Lagrange, Anais. "Mutation de la chaperonne HSP110 et cancers MSI : étude de ses conséquences moléculaires, fonctionelles, physiopathologiques et cliniques". Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066684/document.
Pełny tekst źródłaStreszczenie:
Les cancers MSI (Microsatellite Instable) sont caractérisés par un niveau élevé d'instabilité des séquences répétées de l'ADN, les microsatellites, suite à l'inactivation du système MMR (Mismatch Repair). L'étude de la carcinogenèse MSI a révélé des mutations somatiques (délétion/insertion) de nombreux gènes sur des microsatellites codants, qui décalent le cadre de lecture et engendrent la production de protéines tronquées dont la fonction est le plus souvent perdue. Ces altérations affectent des gènes suppresseurs de tumeurs ou apparentés agissant au niveau de voies de signalisation en rapport avec l'oncogenèse, et sont sélectionnées lorsqu'elles promeuvent le développement tumoral. Ces travaux font état de la découverte de la première mutation d'une chaperonne dans une pathologie tumorale, affectant l'oncogène codant pour HSP110 (Heat Shock Protein) sur un microsatellite non-codant intronique situé dans un site accepteur d'épissage. Cette mutation, conduisant à un saut d'exon, est inéluctable et bi-allélique dans l'ADN tumoral, et entraîne la perte des activités oncogéniques d'HSP110 dans les cellules cancéreuses (effet pro-apoptotique, chimio-sensibilisant, antiprolifératif et de ralentissement de la croissance tumorale). Ces résultats remettent en question les mécanismes de l'oncogenèse MSI et le caractère oncogénique de l'instabilité microsatellitaire. Au niveau physiopathologique et clinique, ils pointent HSP110 comme cible pronostique (facteur prédictif de réponse à la chimiothérapie) et thérapeutique. Je propose une approche de traitement pour les patients avec une tumeur MSI, visant à exacerber le caractère délétère de cette mutation dans les cellules tumoralesMSI cancers (MicroSatellite Instability) are characterized by widespread instability of DNA repeated sequences, known as microsatellites, due to MMR system (Mismatch Repair) deficiency. Since the detection of this tumor phenotype, most of the oncogenic events reported in these tumors are somatic mutations (1-2 bp insertions or deletions) that affect coding DNA repeats, resulting in frameshifts and inactivation of the corresponding proteins. They accumulate in tumor cells due to positive selection during the MSI-driven tumorigenic process when they promote tumor development by inactivating genes with tumor suppressor-related functions. This work reports the first somatic mutation of a chaperone protein in a cancer so far, i.e. HSP110 (Heat Shock Protein) in MSI colorectal cancer. This mutational event consists in the somatic deletion of the intronic microsatellite, located in the splice acceptor site of HSP110. We demonstrate that it is almost systematic and bi-allelic in these cancers, leading to inactivation of the oncogenic functions of the HSP110 chaperone (pro-apoptotic and anti-proliferative impact leading to chemosensitization of tumor cells and tumor growth decrease). Our findings support an unexpected and paradoxical anticancer impact of the microsatellite instability-driven pathway in mismatch repair-deficient colon cancer. From a pathophysiological and clinical point of view, they highlight HSP110 as a putative relevant prognostic marker (improvement of patients’ response to chemotherapy) and therapeutic target. According to these findings, I propose a therapeutic strategy targeting HSP110 and its mutant for personalized medicine of MSI colon cancer patients
13
Wang, Chen. "Novel software tool for microsatellite instability classification and landscape of microsatellite instability in osteosarcoma". Miami University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=miami1554829925088174.
Pełny tekst źródła
14
Mitmaker, Elliot. "Microsatellite instability in thyroid neoplasia". Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=101730.
Pełny tekst źródłaStreszczenie:
Micro satellite instability (MSI) is a form of genomic instability that has recently been implicated in the pathogenesis of thyroid cancer. The purpose of this study is to further define the distribution of microsatellite instability in both normal and neoplastic thyroid follicular epithelium.Using laser capture microdissection, cells from both normal and tumor tissue were individually collected. PCR amplification of the DNA was then performed using six dinucleotide and two mononucleotide microsatellite markers.
Forty benign and malignant thyroid tumors were compared with their adjacent normal thyroid follicular tissue and were analyzed for MSI. 9/14 papillary thyroid carcinomas and 10/16 of follicular thyroid carcinomas demonstrated MSI at >30--40% of loci tested. For benign follicular adenomas, 9/10 demonstrated microsatellite stability or low-frequency MSI.
Microsatellite instability appears to play a role in thyroid pathogenesis as evidenced by the high frequency of MSI in malignant thyroid neoplasms. In addition our study showed a significant difference in MSI frequency between follicular adenomas and follicular carcinomas. More importantly, the technique of laser capture microdissection allows for more accurate selection of benign, malignant and normal DNA.
15
Wei, Tatt Toh. "Microsatellite instability in colorectal cancer". Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/28464.
Pełny tekst źródłaStreszczenie:
Microsatellite instability (MSI) has been a promising molecular marker in colorectal cancer over the past twenty years. However, within the literature, there has been a degree of uncertainty in the effect of MSI status on prognosis, recurrence and treatment decision-making.
The thesis consists of seven peer-reviewed publications on different aspects of MSI in clinical management including:
1. A nationwide survey of medical oncologists and colorectal surgeons showing that MSI status is considered useful in selecting patients for adjuvant therapy as well as prognostication of colon cancer.
2. Meta-analysis evaluating the prognostic significance of MSI in CRC demonstrating that MSI is associated with an overall survival benefit with lower risk of dissemination, with survival benefit most evident in stage II and stage III colorectal cancer.
3. Cohort study evaluating the prognostic significance of sporadic MSI-H CRC. After adjustment for death from other causes as a competing risk, no statistically significant difference in cancer specific survival nor overall survival was demonstrated.
4. Lab-based study evaluating the tumour microenvironment of CRC by MSI status, showing increased tumour infiltrating lymphocytes (TILs), Programmed Death-1 (PD-1) expression and the presence of T resident memory (TRM) cells.
5. Lab-based study examining circulating tumour cell (CTC) release based on MSI status. Prior to this study, it was not known if the immunogenicity of MSI-H CRC decreased the risk of dissemination by reducing the release of CTCs. This study reports a trend towards increased CTC (rather than decreased CTC) release.
6. Systematic review on the role of MSI status in identifying CRC patients suitable for immunotherapy, demonstrating that immunotherapy has the potential to benefit immunogenic MSI-H CRCs.
7. Lab-based study developing a cost-effective and reliable method of determining MSI status with an MSI scoring system based on automatic computational algorithms.
16
PINO, MARIA SIMONA. "The Microsatellite instability phenotype in human colorectal carcinoma". Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2010. http://hdl.handle.net/2108/1417.
Pełny tekst źródłaStreszczenie:
Il carcinoma del colon-retto e' una delle neoplasie con maggior incidenza nella popolazione generale ed una delle maggiori cause di morte per neoplasia, in entrambi i sessi. L’acquisizione di una diffusa instabilità genetica e' essenziale per il suo sviluppo. Instabilità a livello dei microsatelliti o MSI, e' comunemente causata da un’alterazione a livello dei geni del MisMatch Repair (MMR) system, meccanismo multienzimatico deputato al mantenimento della stabilità dell'informazione genetica, che corregge i disappaiamenti di base e le anse di inserzione/delezione che si originano durante la replicazione del DNA. Instabilità microsatellitare si osserva nella Sindrome di Lynch, la forma più comune di carcinoma del colon-retto su base ereditaria, causata da difetti nella linea germinale di uno dei geni del MMR, e nel 10-15% dei carcinomi sporadici del colon-retto per silencing epigenetico del gene hMLH1.
Nella Syndrome di Lynch la carcinogenesi procede attraverso la sequenza adenoma-carcinoma. Tuttavia, sebbene il numero di adenomi in pazienti con Lynch sia simile a quello della popolazione generale, questi si osservano in età più precoce, hanno una predilezione per il colon prossimale, sono più voluminosi, classificati istologicamente come villosi, e crescono rapidamente e progrediscono in una forma invasive in meno di tre anni. Uno dei maggiori problemi in individui con sospetta Sindrome di Lynch e' l’assenza di tessuto tumorale su cui effettuare tests di instabilità microsatellitare. Nella presente tesi, utilizzando una popolazione altamente selezionata di individui affetti da Sindrome di Lynch, dimostriamo come l’analisi molecolare di adenomi colo-rettali possa avere un ruolo nella diagnostica. Utilizzando un’analisi di instabilità dei microsatelliti e la valutazione immunoistochimica dell’espressione delle proteine codificate dai geni del MMR su tessuto tumorale incluso in paraffina, abbiamo infatti identificato un difetto nel MMR system nel 73% degli adenomi asportati. Le singole metodiche hanno identificato alterazioni nel 58% e 70% dei casi, rispettivamente. Così nel work-up di individui con sospetta Lynch, e’ ragionevole iniziare con studi di MSI ed IHC su adenomi, ed i nostri dati suggeriscono che l’IHC da sola e’ sensibile quanto un approccio combinato. Sebbene un risultato positivo può dirigere la successiva analisi genetica, un risultato negativo su un adenoma deve essere interpretato con cautela e non dovrebbe essere utilizzato per escludere la diagnosi se altre caratteristiche cliniche suggeriscono la presenza di Lynch.
Tumori del colon-retto con instabilità microsatellitare sono caratterizzati da una prognosi particolarmente favorevole ma, ad oggi, le basi molecolari di tale fenomeno non sono note. Il gene più frequentemente mutato in tumori con MSI e’ il recettore di tipo II per il transforming growth factor-β (TGFBR2), il cui signaling media effetti soppressori nelle fasi precoci di sviluppo tumorale, mentre nelle fasi più tardive incrementa la progressione tumorale anche attraverso l'induzione di una transizione epitelio-mesenchima (EMT). Nella presente tesi, utilizzando una serie di linee cellulari a differente stato microsatellitare e con un recettore wild-type o mutato dimostriamo come linee con instabilità microsatellitare ed un recettore mutato, al seguito del trattamento con TGF-β, non vengono indotte in EMT, al contrario di linee con MSI ma senza mutazioni in TGFBR2. Inoltre, nella nostra analisi di 129 casi di tumori del colon-retto con o senza instabilità microsatellitare, la perdita di marcatori epiteliali e l’acquisizione di marcatori mesenchimali sono associati non solo con variabili clinicopatologiche di cattiva prognosi ma anche con l'assenza di instabilita’ microsatellitare. Collettivamente, i nostri dati in vitro ed in campioni umani suggeriscono che mutazioni nel TGFBR2 interferiscono con l’induzione di EMT da parte del TGF-β e pertanto riducono le capacita’ migratorie ed invasive delle cellule tumorali. Oltre a fornire una spiegazione a base molecolare per la prognosi favorevole costantemente osservata in tumori del colon-retto con instabilità microsatellitare, questi risultati suggeriscono un razionale per l’inibizione terapeutica del signaling del TGF-β in tumori del colon-retto senza MSI.Colorectal cancer is the second to the fourth most common cancer in industrialized countries. Baseline mutation rates are insufficient to account for the multiple mutations that are required for cancer to develop. Genomic instability is now recognized as an essential cellular feature that accompanies the acquisition of these mutations. In colon cancer, at least 3 distinct pathways of genomic instability have been described, the chromosomal instability, microsatellite instability (MSI), and the so-called CpG island methylator phenotype pathways, each with distinctive tumor genotypes and phenotypes. MSI is commonly caused by loss of the DNA mismatch repair (MMR) system, which normally recognizes and repairs mismatched nucleotides and insertion/deletion loops caused by slippage of DNA polymerase. MSI occurs in hereditary as well as sporadic CRC. In Lynch syndrome, responsible for 2-5% of all CRC cases, a germline mutation in a MMR gene accounts for more than 90% of cases, whereas in 10-15% of sporadic CRCs MSI is due to loss of expression of a MMR gene (most commonly hMLH1) caused by epigenetic silencing. In Lynch syndrome, carcinogenesis proceeds through the adenoma-carcinoma sequence. Although the number of polyps in Lynch patients appears to be similar to the general population, the polyps are more likely to occur at a younger age, have a predilection for the proximal colon, be larger, display villous features or high-grade dysplasia, and most importantly, grow rapidly and progress to invasive cancer in less than 3 years. As the recognition of Lynch is increasing in the population, many individuals with suspected Lynch now undergo routine colonoscopic screening with polypectomy. In such a scenario, there is no colon cancer tissue available for MSI and IHC testing. In this thesis, we present the results of a study that was undertaken to test the hypothesis that MSI testing and IHC analysis in pre-cancerous colorectal adenomas instead of colorectal cancers may be an alternative approach to screen for Lynch syndrome. MSI analysis, IHC staining for MMR proteins or both detected DNA repair deficiency in 58%, 70%, and 73% of the Lynch-associated adenomas, respectively, and this included adenomas smaller than 5 mm. Thus, in the workup of patients suspected to have a germline MMR gene mutation, it is reasonable to begin with MSI and IHC analyses of adenomas, and our data suggest that IHC testing alone is nearly as sensitive as a combined approach. Positive results can be utilized to direct germline genetic testing. However, a negative MSI or IHC test result in an adenoma should be interpreted cautiously and cannot be used to formally exclude the diagnosis of Lynch syndrome if other clinical features suggest the diagnosis. Nevertheless, this approach would expand the diagnostic testing options in cases with suspected Lynch and increase the opportunities to recognize the syndrome before the development of invasive cancer. The clinical behavior of MSI tumors is distinctive, and the most intriguing and consistently described feature is the enhanced survival benefit that does not appear to be attributable to differences in therapeutic response. The molecular basis for the prognostic advantage due to MSI is not clearly established. The most commonly mutated gene in tumors with MSI is the transforming growth factor-β receptor II (TGFBR2) gene, which harbors an (A)10 microsatellite that undergoes a frame shift. This mutation leads to a disruption in the TGF-β signaling, which plays a dual role in tumorigenesis: in early stages it mediates tumor-suppressive effects whereas, paradoxically, at later may enhance tumor progression due to its ability to inhibit cell death from growth factor deprivation, suppress immune function, and induce an epithelial to mesenchymal transition (EMT). In this thesis we provide a potential molecular explanation for the favorable outcome observed in MSI tumors. We show that TGFBR2 mutations, observed in up to 90% of CRCs with MSI, interfere with TGF-β-induced EMT, an important component of cancer progression, and therefore reduce the migratory and invasive capabilities of cancer cells. Tumors with MSI but without TGFBR2 mutations undergo EMT in response to TGF-β1, suggesting that TGFBR2 genotype and not MSI status per se may be the key determinant of the EMT response and ultimately, prognosis. In addition, these findings suggest a rationale for the therapeutic inhibition of TGF-β signaling in MSS colorectal tumors.
17
Lozano, Losanges de Fátima. "Obtenção de marcadores moleculares para prognóstico e diagnóstico de melanoma cutâneo maligno". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/87/87131/tde-11082009-173623/.
Pełny tekst źródłaStreszczenie:
Incidência de melanoma cutâneo maligno (MM) está aumentando em torno de 2,5 a 4% por ano no mundo. Os principais fatores de risco são história familiar de MM, múltiplos nevos benignos ou atípicos, e fatores adicionais como a imunossupressão, sensibilidade solar e exposição à radiação ultravioleta (UV). A instabilidade genômica é responsável pelo acúmulo de mutações que frequentemente estão envolvidas na transformação maligna. Podemos estudar a instabilidade genômica através de duas formas: microssatélites e RAPD (Random Amplified Polymorphic DNA). Na instabilidade genética o DNA repetitivo pode sofrer alterações. Através da Instabilidade de microssatélites (MSI) e da perda da heterozigosidade (LOH) podemos diferenciar tecidos normais de tumorais. A técnica de RAPD (baseada na PCR) produz fingerprints utilizados para detectar instabilidade genômica, polimorfismos, mutações e translocações quando comparados à fingerprints de amostras normais. No estudo de nove microssatélites encontramos um aumento de MSI (p=0.0132). D9S50 apresentou o maior número de alterações (28,5%) em nevos e MMs. D6S252, D9S52 e D9S180 são candidatos à marcador de prognóstico de MM porque apresentaram alterações (MSI + LOH) apenas em MMs. Na análise de 15 primers de RAPD em 12 amostras de MMs obtivemos 100 % de alteração com relação ao número ou posição das bandas. Os primers OPA-2 e OPA-14 são capazes de detectar alterações genéticas nos MMs. Dos padrões obtidos foram encontradas bandas que estavam ausentes nos tumores e estas foram clonadas e seqüenciadas. Estes procedimentos evidenciaram alterações em 9q33 e 12q15. O RAPD propicia o estudo do genoma humano sem a definição prévia de um lócus. Assim, podemos detectar alterações até então desconhecidas aumentando o conhecimento sobre a genômica tumoral.The incidence of malignant skin melanoma (MM) increases around 2,5 a 4% each year in the world. The main risk factors are family history of MM, multiple benign or atypical nevi, and additional factors such as immunossuppression, sun sensibility and UV exposure. Genomic instability is responsible for a collection of mutations that are frequently involved in malignant transformation, and it can cause alterations in repetitive DNA sequences. There are two ways of studying genomic instability: microsatellites and RAPD (Random Amplified Polymorphic DNA). Through microsatellite instability (MSI) and loss of heterozygosis (LOH) we can separate normal from tumoral tissues. RAPD technique (which is based on PCR) generates fingerprints used for detection of genomic instability, polymorphisms, mutations and translocations that can be compared with fingerprint generated from normal tissue. Studying nine microsatellite, we found an increased MSI (p=0.0132). D9S50 showed the greater number of alterations (28,5%) in nevi and MM. D6S252, D9S52 e D9S180 are candidates for MM prognostic marker for showing alterations (MSI+LOH) in melanomas only. The analysis of 15 RAPD primers in 12 MM samples showed 100% of alteration related to the number or location of the bands. OPA-2 and OPA-14 primers are capable of detecting genetic alterations in MM. In the patterns obtained, two bands which were absent in tumors were found, and they were cloned and submitted to sequencing. These procedures highlighted alterations in loci 9q33 e 12q15. RAPD makes it possible to study the genome without a previous definition of a locus. So we are able to detect alterations so far unknown, increasing our knowledge on tumor genetics.
18
MacDonald, Nicola Dawn. "Microsatellite instability and other molecular events in endometrial carcinogenesis". Thesis, Queen Mary, University of London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443550.
Pełny tekst źródła
19
Phillips, Simon M. "The Influence of Microsatellite Instability on Survival in Colorectal Cancer". Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491896.
Pełny tekst źródłaStreszczenie:
Colorectal cancers that express Micro~atellite Instability (MSI) differ in many clinicopathological and genetic features from 'sporadic' tumours. They also appear to confer an improved prognosis, roughly translating into a 10-20% improvement in S-year patient survival. This advantage is independent of patient age or tumour stage, despite these tumours co~only displaying otherwise advers~- features' such as poor tumour differentiation or mucinous tumour characteristics. One common explanation is that the 'mutator phenotype' limits tumour aggressiveness, but in fact MSI+ colonic adenomata progress faster towards invasive malignancy. Alternatively these tumours may invoke an enhanced immunological response, directed against tumour-derived antigens, which in turn affects the aggressiveness of MSI+ tumours. Although many workers have shown a quantitative increase in tumour lymphocytes compared with MSI- tumours, direct evidence showing that MSI+ tumours elicit enhanced cytotoxicity is limited. Moreover it implies only indirectly that lymphocytes within MSI+ tumours are activated in an antigen-specific manner. In a consecutive series of over 200 prospectively analysed colorectal cancers we assessed populations ofCD8+ and CD4+ T-cells, relative levels 0 f lymphocyte cytotoxicity (Granzyme B), and the degree ofantigen-specific activation in the tumour lymphocyte populations (Interleukin 2 receptor ex-subunit). Complimentary techniques were used. Firstly, gene expression of all markers was determined by real-time fully quantitative RT-PCR (faqman) to assay mRNA levels within fresh-frozen tumour samples. Secondly, protein expression of markers was compared using appropriate monoclonal antibodies and immunohistochemistry (IHC) from formalin-fixed paraffin-embedded specimens. Microsatellite stable (MSI-) and MSH groups were directly compared. In addition, clinico-pathological data was correlated with immunological variables in order to identify Supplied by The British Library - 'The world's knowledge' any independently predictive features for eitllCr survival, or for use as a model to allow identification of MSI+ tumours by incorporating standard c1inico-pathological variables and simple immunohistochemistry. The findings of this work corroborate the commonly reported c1inico-pathological features of MSI+ tumours. In addition we demonstrate significant differences in T-cell mRNA expression and immunohistochemical quantity, bOtll overall (CD3+) and for CD8+ and CD4+ subsets. Moreover, an observed significant difference in Granzyme B levels and IL2-RiX expression suggests tllat the lymphocyte population in MSI+ tumours is botll more highly activated and tllat this activation is likely to be antigen-specific. No firm commentary on survival differences can be made witllin our study group, nor prognostic relationships to any measured variable. Comparisons between the mRNA expression data and immunohistochemistry are made and tlle limitations of each technique are discussed.
20
Martinez, Ramon, Hans-K. Schackert, Jens Plaschke, Gustavo Baretton, Hella Appelt i Gabriele Schackert. "Molecular Mechanisms Associated with Chromosomal and Microsatellite Instability in Sporadic Glioblastoma multiforme". Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-133546.
Pełny tekst źródłaStreszczenie:
Objective: Two chromosomal instability (CIN) pathways are described in glioblastoma multiforme (GBM), type 1 and type 2, which can be observed in up to 70% of the cases. Microsatellite instability (MSI) plays a pathogenic role in sporadic cancers such as colon, gastric and endometrial carcinomas with deficient mismatch repair (MMR). We aimed to perform a comprehensive analysis of the relationship between CIN and MSI mechanisms in sporadic glioblastomas. Methods: 129 GBMs were examined (109 newly diagnosed and 20 relapses) investigating MSI, immunohistochemical expression of MMR proteins as well as sequencing and promoter methylation of hMLH1. We characterized the molecular changes frequently correlated with CIN in MSI+ GBMs and compared them with 26 microsatellite-stable tumors. Results: Low-level MSI was observed in 11 of 129 (8.5%) cases and was higher in relapses than in primary GBMs (25 vs. 5.5%, p = 0.027). High-level MSI was not found in any case. A deficient expression of MLH1 and PMS2 without hMLH1 inactivation was observed only in one giant cell GBM. 55% of the MSI+ GBMs showed a profile which did not correspond to one of the known CIN pathways. An inverse association was observed between MSI and mutations of both p53 and PTEN. Conclusions: Our data suggest that CIN and MSI contribute to the genomic instability in GBMs via independent pathways. Since MSI was significantly more frequent in relapses, it might play a role in the malignant progression of GBMDieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
21
Burgess, Michael Frans. "Mismatch repair and microsatellite instability in paediatric malignancy and cisplatin resistance". Thesis, University of Bristol, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311425.
Pełny tekst źródła
22
Martinez, Ramon, Hans-K. Schackert, Jens Plaschke, Gustavo Baretton, Hella Appelt i Gabriele Schackert. "Molecular Mechanisms Associated with Chromosomal and Microsatellite Instability in Sporadic Glioblastoma multiforme". Karger, 2004. https://tud.qucosa.de/id/qucosa%3A27514.
Pełny tekst źródłaStreszczenie:
Objective: Two chromosomal instability (CIN) pathways are described in glioblastoma multiforme (GBM), type 1 and type 2, which can be observed in up to 70% of the cases. Microsatellite instability (MSI) plays a pathogenic role in sporadic cancers such as colon, gastric and endometrial carcinomas with deficient mismatch repair (MMR). We aimed to perform a comprehensive analysis of the relationship between CIN and MSI mechanisms in sporadic glioblastomas.
Methods: 129 GBMs were examined (109 newly diagnosed and 20 relapses) investigating MSI, immunohistochemical expression of MMR proteins as well as sequencing and promoter methylation of hMLH1. We characterized the molecular changes frequently correlated with CIN in MSI+ GBMs and compared them with 26 microsatellite-stable tumors.
Results: Low-level MSI was observed in 11 of 129 (8.5%) cases and was higher in relapses than in primary GBMs (25 vs. 5.5%, p = 0.027). High-level MSI was not found in any case. A deficient expression of MLH1 and PMS2 without hMLH1 inactivation was observed only in one giant cell GBM. 55% of the MSI+ GBMs showed a profile which did not correspond to one of the known CIN pathways. An inverse association was observed between MSI and mutations of both p53 and PTEN.
Conclusions: Our data suggest that CIN and MSI contribute to the genomic instability in GBMs via independent pathways. Since MSI was significantly more frequent in relapses, it might play a role in the malignant progression of GBM.Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
23
Lawes, Daniel Alfred. "The role of microsatellite instability in the development of multiple colorectal cancer". Thesis, University College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407152.
Pełny tekst źródła
24
Coggins, Si'Ana Apri. "5-FU Chemotherapy Failure in Some Colorectal Cancer Patients with Microsatellite Instability". Thesis, The University of Arizona, 2015. http://hdl.handle.net/10150/579042.
Pełny tekst źródłaStreszczenie:
Human colorectal cancer (CRC) is the third most commonly diagnosed cancer as well as the second leading cause of cancer mortality in the United States. The hypothesis to be tested in this study is that the loss of TGFβ signaling causes overexpression of the uridine phosphorylase (UP) gene in human CRC when treated with 5-fluorouracil (5-FU), a common chemotherapeutic reagent. As a result, 5-FU may be metabolized via the RNA pathway, causing an increase in host-toxicity. Conversely, a mutation in the KRAS gene may drive the reaction towards the antitumor, DNA metabolic pathway. This mechanism would explain the ineffective nature of 5-FU-based treatments on tumors, some of which are TFGβ signaling-deficient, that are usually characterized as microsatellite instability high (MSI-H). If so, situational inhibition of UP may increase the intended anti-tumor activity of the 5-FU treatment while decreasing host-toxicity in this subcategory of MSI-H tumors, thus allowing only patients whose tumors have a 5-FU-susceptible genetic profile to be treated successfully with 5-FU based therapy. Cancerous cell lines containing different combinations of TGFBR2 and KRASᴳ¹³ᴰ mutations will be cultured and photographed. The cell lines Hke3 and Hkh2 contain a TGFBR2 mutation and have a morphological pattern that closely resembles the colonic mucosa while the HCT116 cell line contains both TGFBR2 and KRASᴳ¹³ᴰ mutations and has less structured morphology. Following culturing, UP and TP mRNA expression levels in all cell lines will be determined through reverse transcriptase (RT)-PCR and normalized to β-actin. If the hypothesis is supported, and then verified in patients, personalized therapy can be used to determine whether 5-FU should be administered in colorectal cancer cases in which KRASᴳ¹³ᴰ and TGFBR2 mutations are present or absent.
25
Neelsen, Kai John. "A novel gene therapy approach for the treatment of tumours with microsatellite instability". kostenfrei kostenfrei, 2008. http://e-collection.ethbib.ethz.ch/view/eth:30442.
Pełny tekst źródła
26
Hackman, Peter. "HPRT mutational spectra and microsatellite DNA instability in HNPCC and lung cancer patients /". Stockholm, 2000. http://diss.kib.ki.se/2000/91-628-4219-6/.
Pełny tekst źródła
27
Bokhari, A'Dem. "Etude de la mutation de la chaperonne HSP110 dans les cancers gastro-intestinaux MSI : conséquences fonctionnelles et cliniques". Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066239/document.
Pełny tekst źródłaStreszczenie:
L'instabilité microsatellitaire (MSI) résulte d'une déficience du système de réparation des mésappariements de l'ADN. Cette instabilité est observée dans 10-15% des tumeurs chez l'Homme, incluant les cancers colorectaux (CCR) et de l'estomac (CG). En 2011, notre laboratoire a rapporté la mutation de la chaperonne HSP110 dans les CCR MSI. Cette mutation affecte un microsatellite intronique de 17 thymidines (T17), localisé au niveau de l'intron 8. Les grandes délétions somatiques du T17 (? 5 paires de bases), représentant 25% des CCR MSI, conduisent à l'inactivation complète de la chaperonne HSP110 dans les CCR MSI. De manière remarquable, ces grandes délétions sont prédictives chez les patients d'une excellente réponse à la chimiothérapie adjuvante. Au cours de ma thèse, mes travaux ont visé à étudier l'impact de la mutation d'HSP110 dans les tumeurs gastro-intestinales MSI. Mes résultats démontrent que la mutation du microsatellite T17 d'HSP110 a pour conséquence une diminution de la prolifération cellulaire en partie lié à la diminution de la phosphorylation du facteur de transcription STAT3. En outre, mes résultats suggèrent que cette mutation serait un facteur prédictif de survie chez les patients atteint de CG, indiquant le potentiel théranostique d'HSP110. Enfin, je propose une approche thérapeutique innovante pour les patients atteints de CCR MSI, basée sur la potentialisation de l'expression de transcrits mutants, codant pour des protéines délétères pour la cellule tumorale, à l'instar du dominant négatif HSP110DE9 résultant de la mutation d'HSP110 dont l'ARN semble être régulé par le système NMD (Nonsense-Mediated mRNA Decay)Microsatellite instability (MSI) results from impaired DNA mismatch repair, being observed in 10-15% of frequent tumors in human, e.g. Colorectal (CRC), Gastric Cancers (GC) and others. In 2011, frequent somatic mutations of the HSP110 chaperone have been reported in MSI CRC by my lab, affecting a T17 intronic DNA repeat located in intron 8. Large (≥ 5 base pairs) bi-allelic somatic deletions of this DNA repeat in tumor DNAs, as observed in about 25% of MSI CRC, lead to complete inactivation of HSP110 by exon 9 skipping and sensitization of tumor cells to chemotherapy. These large deletions are predictive of improved response to adjuvant chemotherapy in CRC patients. During my PhD thesis, I further investigated the role of HSP110 in MSI tumors. My results demonstrate that HSP110 mutation leads to cell proliferation decrease through the reduction of STAT3 transcription factor phosphorylation in CRC tumors (Berthenet*, Bokhari*, et al., Oncogene 2016). Furthermore, I showed that HSP110 mutation is also frequently observed in MSI gastric cancer, leading to very similar pathophysiological consequences during tumor progression and improved patient’s survival independently from tumor stage (Cervera*, Lagrange*, Bokhari* et al., submitted). Finally, I worked on an innovative therapeutic approach that consisted in inhibiting the NMD (Nonsense-Mediated mRNA Decay) system, an ubiquitous process recognizing and degrading mRNAs containing premature termination codons (PTC). The inhibition of NMD leads to the expression of deleterious MSI-driven mutant transcripts such as the HSP110DE9, coding for a dominant negative mutant, derived from HSP110 mutation in MSI cancer cells
28
Millar, Anna L. "Frequency estimation of endometrial cancer associated with microsatellite instability and mismatch repair gene defects". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0005/MQ46045.pdf.
Pełny tekst źródła
29
Cunningham, Christopher. "Colerectal cancer genetics : a study of chromosome 8p tumour suppressor loci and microsatellite instability". Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/21177.
Pełny tekst źródłaStreszczenie:
Fourteen chromosome 8 polymorphic loci were analysed for loss of heterozygosity in 119 colorectal cancers selected at random. Loss of heterozygosity was detected in 59.6% (59/99) of informative cases. Markers were of sufficient density to allow the construction of a deletion map which delineated two discrete regions likely to contain tumour suppressor loci. A 4cM region at 8p22-21.3 between markers D8S133 and LPL and a further locus at 8p21-11.2, between markers D8S137 and D8S136, estimated to span some 17cM. Loss of heterozygosity on chromosome 8p was found to be independent of tumour site, Duke's stage, patient age, sex and survival. Analysis of 50 sporadic colorectal adenomas revealed a low frequency of chromosome 8p loss of heterozygosity, suggesting that the tumour suppressor loci are preferentially involved in the later stages of colorectal carcinogenesis. The role of defective DNA mismatch repair in colorectal cancer predisposition has been reported recently. These defects are manifested by microsatellite instability. Such instability was noted in tumour DNA during chromosome 8p loss of heterozygosity studies and the project was extended to investigate this phenomenon. The prevalence of microsatellite instability was determined in 245 colorectal cancers. 16.7% (41/245) displayed replication errors at one or more microsatellite loci, suggesting underlying errors in mismatch repair. Cancers displaying microsatellite instability tended to arise in the proximal colon, maintained nuclear diploidy and were associated with a significantly improved survival. The presence of replication errors was independent of patient age and sex, loss of heterozygosity at chromosomes 5q and 17p and immunohistochemistry for p53 protein. Loss of heterozygosity affecting chromosome 8p and defective DNA mismatch repair are frequent genetic abnormalities in colorectal cancers. This project provides important data localising the putative tumour suppressor genes to two discrete regions on chromosome 8p. This will aid future efforts towards cloning and identifying the genes involved. In addition, the prevalence and clinicopathological features of microsatellite instability have been established, in a large population of unselected colorectal cancers, allowing insight into the involvement of this mechanism in sporadic colorectal carcinogenesis.
30
Thomas, Emily A. "Characterization and Clinical Implications of Microsatellite Instability in Human Adult Mesenchymal and Hematopoietic Stem Cells". Miami University Honors Theses / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=muhonors1177506541.
Pełny tekst źródła
31
Borie, Claire. "Instabilité des microsatellites et cancers : recherche et description de ce phénotype tumoral dans les cancers du patient immunodéprimé". Paris 7, 2011. http://www.theses.fr/2011PA077067.
Pełny tekst źródłaStreszczenie:
Les cancers MSI sont déficients dans le système de réparation des mésappariements de base de l'ADN (système « Mismatch Repair »). L'inactivation de ce système est à l'origine de l'accumulation d'erreurs de réplication non réparées dans le génome de ces tumeurs, en particulier au niveau des séquences répétées, dites microsatellites de l'ADN ; ces tumeurs sont désignées MSI pour « Microsatellites Instables ». Les cancers MSI sont héréditaires, associés au syndrome colorectal familial (syndrome de Lynch ou HNPCC), et représentant également 15-20% des tumeurs sporadiques du côlon, de l'estomac et de l'endomètre. Plus récemment, un phénotype MSI a été rapporté dans d'autres tumeurs de survenue sporadique, notemment du fait de travaux réalisés dans le laboratoire d'acceuil ; ce phénotype a été décrit en particulier dans les lymphomes non hodgkiniens (LNH), mais cela uniquement dans les LNH survenant dans un contexte d'immunodépression (ID-RL), i. E. Chez les patients SIDA ou greffés d'organes et traités par immunosuppresseurs au long cours. Les objectifs de mon travail de thèse ont été dans ce contexte : (i) de préciser l'incidence de MSI dans les ID-RL et les caractéristiques cliniques et biologiques de ces lymphomes comparativement aux autres ID-RL (ID-RL non-MSI) ; (ii) de mettre en évidence une association éventuelle à MSI au sein d'autres types tumoraux fréquents du patient ID, e. G. Dans les cancers spino-cellulaires cutanés (ID-SCC) et les sarcomes de Kaposi (ID-KS). Mes travaux établissent que le phénotype MSI est rarement observé dans les ID-RL, venant représenter 2-5% des LNH du patient SIDA et 10% environ des LNH post-greffe (PTLD). Brièvement, les PTLD MSI se caractérisent par leur survenue tardive après la greffe (médiane > 5 ans), une faible association à l'EBV (< 50%), et une origine lymphocytaire T fréquente (50% des PTLD T sont MSI). MSI est significativement associé dans ces tumeurs à la prise d'Azathioprine (Imurel) par les patients. Par ailleurs, les pertes d'expression de protéines MMR sont panachées dans les ID-RL et affectent aussi bien MLH1, que MSH2 ou MSH6. L'inactivation de l'expression de ces protéines est significativement associée à l'inactivation de la protéine MGMT en raison d'une méthylation fréquente du promoteur du gène dans la tumeur. Enfin, les ID-RL MSI se caractérisent par une relative stabilité sur le plan cytogénétique et la survenue fréquente de mutations de l'oncogène BRAF (Borie et al. , Int. J Cancer 2010). Dans les SCC et les KS, mes travaux n'ont pas permis d'identifier de tumeurs MSI, suggérant la non participation de ce processus oncogénique à la tumorigenèse cutanée chez le patient ID (Borie et al. , Am. J. Transpl. , 2010). Ces études ont généralement porté sur de larges séries de tumeurs ID-RL, SCC et KS, permettant de conclure sur la part de MSI dans l'oncogenèse de ces tumeurs. De manière intéressante, certaines caractéristiques cliniques et moléculaires originales associées aux ID-RL MSI sont maintenant identifiées. En perspective, la nécessité de développer désormais des études visant à mieux identifier les caractéristiques pronostiques et de réponse aux traitements de ces tumeurs par rapport aux autres ID-RL serait d'intérêt, en particulier pour les PTLD-T. A l'instar de ce qui a été rapporté pour d'autres localisations tumorales chez l'homme, MSI pourrait être en effet un facteur à prendre en compte dans la prise en charge de ces lymphomes chez les patientsMSI cancers arise as a consequence of loss of fonction of the DNA Mismatch repair system ("MMR" System). Inactivation of this system results in accumulation of replication errors in the genome of these tumors, in particular in repetitive séquences of the DNA called microsatellites; these tumors are therefore called MSI for " Instable Microsatellite". MSI cancers are inherited diseases associated with familial the colorectal cancer (Lynch syndrom or HNPCC), and represent 15-20 % of sporadic colorectal, gastric and endometrial cancers. Recently, the MSI phenotype was reported in other sporadic cancers. In particular owing to the works realized in our laboratory; this phenotype was described in non Hodgkin lymphomas (NHLs), but only in the NHL arising in an immuno-suppression context ( ID-RL), i. E. HIV-related or after organ transplantation. The objectives of my thesis were in this context: i) to specify the incidence of MSI in the ID-RL and establish the clinical and biological characteristics of these lymphomas compared with the other ID-RL (ID-RL not -MSI); ii) to search for a possible association between MSI and other frequent immuno-supression related tumoral types, e. G. In the squamous cell carcinomas cancers (ID-SCC) and the Kaposi's sarcomas (ID-KS). We established that the MSI phenotype is rarely observed in the ID-RL, representing 2-5 % of HIV-related NHL and approximately 10 % of PTLD. Briefly, MSI PTLD are characterized by their late occurrence after organ transplantation (median > 5 years), rare association with EBV (< 50 %), and frequent T phenotype (50 % of the PTLD T are MSI). MSI is significantly associated in these tumors after Azathioprine (Imurel) treatement. Further, loss of expression of the MMR proteins is heterogeneous in the ID-RL : MLH1, as well MSH2 or MSH6 can be involved. Loss of expression of O6 methyl guanine transferase (MGMT), a repair enzyme whose inactivation helps in selection of MMR deficient clones, was significantly associated with MSI in ID-RL. Finally, ID-RL MSI are characterized by few chromosomal rearangements and frequent mutations of the oncogene BRAF (Borie and al. , Int. J Cancer on 2010). My work involved the study of large series of tumors ID-RL, SCC and KS, to better understand the role of MSI in the oncogenetic process. Interestingly, I contributed to the identification of original clinical and molecular features of ID-RL MSI. Prospectives studies are needed to better define prognostic factors and therapeutic protocols of these tumors as compared with to the other ID-RL. This would be in particular interest, in PTLD-T. Following the example of what has been reported in other tumors, MSI could indeed be a factor to take into account in the treatment of these lymphomas
32
Larkin, Kenneth John. "Development of a yeast-based colour assay for monitoring genetic and dietary influences on microsatellite instability". Thesis, University of East Anglia, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302203.
Pełny tekst źródła
33
Alhilal, Mohammed Ghanim Mehdi. "Development and validation of a next generation sequencing based microsatellite instability assay for routine clinical use". Thesis, University of Newcastle upon Tyne, 2016. http://hdl.handle.net/10443/3559.
Pełny tekst źródłaStreszczenie:
Colorectal cancer (CRC) is the second most common cancer in both men and women. Approximately 3-5% of CRCs show microsatellite instability (MSI) caused by germline defects in mismatch repair genes. In addition, 12% of sporadic CRCs show MSI. Currently, MSI is tested using a fragment analysis based assay not suitable for high throughput testing. Knowledge of microsatellite instability affects prognosis, surveillance and treatment of CRCs and MSI testing is now recommended for all newly diagnosed CRCs. As a result, development of high throughput approaches is desirable. The focus of my work was to develop and validate a high throughput sequence based MSI assay. Initially, I tested 25 (7-9bp) mononucleotide markers, previously identified from in silico analyses, using a cohort of 55 CRCs, and selected 8 markers which collectively could discriminate between MSI-high (MSI-H) and microsatellite stable (MSS) cases. To define the optimal parameters to discriminate between MSI-H and MSS samples, I tested these 8 markers and 9 long (8-12bp) mononucleotide markers identified in a parallel study, across a panel of 141 CRC samples. This allowed development of a scoring scheme for the 17 markers, which achieved 96% sensitivity and 100% specificity. I validated this scheme using an independent cohort of 70 CRCs without knowing their MSI status. The assay achieved a 100% sensitivity and specificity. Finally, I assessed the ability of short repeats to allow inference of the clonal variation within both FFPE (7) and fresh (4) MSI-H CRCs by analysing multiple samples from each cancer. I was able to infer the lineage relationship between primary tumour and lymph node metastasis in three cases and to construct phylogenetic trees for all cancers for which multiple samples were available illustrating the utility of these markers for understanding of CRC clonal variation.
34
Bergfors, Monica. "Evaluation of Microsatellite Instability Analysis as a Diagnostic Tool to Identify Lynch Syndrome in Endometrial Cancer Patients". Thesis, Uppsala universitet, Institutionen för kvinnors och barns hälsa, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-227772.
Pełny tekst źródłaStreszczenie:
Hereditary endometrial cancer (EC) is a Lynch syndrome (LS) related cancer variant and 2-10% of all EC are hereditary. The aim of this study was to develop a method for analysis of microsatellite instability (MSI) as such analysis would assist in identifying potential LS patients with EC at an early state of their disease, before a possible second cancer is developed in another organ. Twenty-six patients with adenocarcinoma in the endometrium, diagnosed at Uppsala University Hospital in Sweden between 1993 and 2012, were included in the study. Seven of these patients were also diagnosed with LS and the rest were sporadic EC. DNA was extracted from the patients’ formalin-fixed and paraffin-embedded tissues. The extracted DNA was subjected to a multiplex PCR with fluorescently labelled primers and then analysed by using capillary electrophoresis. Of the sporadic EC, 26% was MSI-High, which correlates well with published data. Of the LS patients, 83% was MSI-High. The outcome of this project resulted in that MSI analysis is now a validated and established method used in the process of identifying potential LS among patients with EC.
35
Kanopienė, Daiva. "Clinical relevance of studies on microsatellite instability and DNA mismatch repair system protein expression in endometrial carcinomas". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20141209_111951-10166.
Pełny tekst źródłaStreszczenie:
The evaluation of microsatellite instability in cancer patients might be of clinical importance as a prognostic and predictor factor. The aim of this study − evaluate the frequency and status of microsatellite instability and DNA mismatch repair protein expression in endometrial cancer and to relate the obtained results to clinicopathologic characteristics as well as patient survival. This study enrolled 109 patients.The objectives of the study: to determine the frequency and status of microsatellite instability by using two marker panels (earlier created BAT-25, BAT-26, NR-21, NR-24, MONO-27 and a new BAT-52, BAT-55, BAT-56, BAT-57, BAT-59 panels) recommended by Promega Corporation (USA); to compare the frequency and status of microsatellite instability with tumor clinicopathologic characteristics; to investigate the expression of DNA mismatch repair proteins (MLH1, PMS2, MSH2, and MSH6) in tumors with high-frequency microsatellite instability; to evaluate the impact of microsatellite instability on the survival of patients. The results showed that high-frequency microsatellite instability was detected two times more frequently with the new panel of markers in comparison while using earlier created panel. A statistically significant difference regarding tumor grade and myometrial invasion was found between the groups with high-frequency microsatellite instability and stable phenotype. There was no association between the survival of patients and microsatellite instability.Mikrosatelitų nestabilumo tyrimai svarbūs vėžio ligos prognozei vertinti bei parenkant individualų gydymą. Darbo tikslas − ištirti mikrosatelitų nestabilumo dažnį, pobūdį ir klaidingai suporuotų nukleotidų DNR pažaidų taisymo sistemos baltymų raišką sergant gimdos kūno vėžiu ir gautus rezultatus susieti su pacienčių klinikinėmis-patologinėmis charakteristikomis bei jų išgyvenamumu. Į stebėsenos perspektyvinį tyrimą buvo įtrauktos 109 pacientės. Darbo uždaviniai: nustatyti mikrosatelitų nestabilumo dažnį ir pobūdį tarp sergančiųjų gimdos kūno vėžiu, panaudojus Promega Corporation (JAV) sukurtus du žymenų rinkinius (anksčiau sukurtą BAT-25, BAT-26, NR-21, NR-24, MONO-27 ir naująjį BAT-52, BAT-55, BAT-56, BAT-57, BAT-59); palyginti mikrosatelitų nestabilumo dažnį ir pobūdį su pacienčių klinikinėmis-patologinėmis charakteristikomis; ištirti DNR pažaidų taisymo sistemos baltymų (MLH1, PMS2, MSH2, MSH6) raišką gimdos kūno navikuose, kuriuose nustatytas didelio dažnio mikrosatelitų nestabilumas; įvertinti mikrosatelitų nestabilumo įtaką pacienčių išgyvenamumui. Tyrimų rezultatai parodė, kad mikrosatelitų didelio dažnio nestabilumas dvigubai dažniau nustatytas naudojant naująjį žymenų rinkinį, palyginti su anksčiau sukurtu žymenų rinkiniu. Statistiškai reikšminga sąsaja konstatuota tarp mikrosatelitų didelio dažnio nestabilumo arba jo nebuvimo ir naviko diferenciacijos laipsnio bei invazijos į miometriumą gylio. Sergančiųjų išgyvenamumas nebuvo susijęs su mikrosatelitų nestabilumu. ... [toliau žr. visą tekstą]
36
Kaszynski, Richard Hideki. "A quantitative trait locus responsible for inducing B-cell lymphoblastic lymphoma is a hotspot for microsatellite instability". Kyoto University, 2010. http://hdl.handle.net/2433/120595.
Pełny tekst źródła
37
Virouleau, Alain. "Apprentissage statistique pour la détection de données aberrantes et application en santé". Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX028.
Pełny tekst źródłaStreszczenie:
Le problème de la détection de données aberrantes et celui de régression robuste dans un contexte de grande dimension est fondamental en statistiques et a de nombreuses applications.Dans la lignée de récents travaux proposant de traiter conjointement ces deux problèmes de régression et de détection, nous considérons dans la première partie de ce travail un modèle linéaire gaussien en grande dimension avec ajout d'un paramètre individuel pour chaque observation.Nous proposons une nouvelle procédure pour simultanément estimer les coefficients de la régression linéaire et les paramètres individuels, en utilisant deux pénalités différentes basées toutes les deux sur une pénalisation convexe l1 ordonnée, nommée SLOPE. Nous faisons l'analyse théorique de ce problème: nous obtenons dans un premier temps une borne supérieure pour l'erreur d'estimation à la fois pour le vecteur des paramètres individuels et pour le vecteur des coefficients de régression. Puis nous obtenons un résultat asymptotique sur le contrôle du taux de fausse découverte et sur la puissance concernant la détection du support du vecteur des paramètres individuels.Nous comparons numériquement notre procédure avec les alternatives les plus récentes, à la fois sur des données simulées et sur des données réelles.La seconde partie de ce travail est motivée par un problème issu de la génétique. Des séquences particulières d'ADN, appelées multi-satellites, sont des indicateurs du développement d'un type de cancer colorectal. Le but est de trouver parmi ces séquences celles qui ont un taux de mutation bien plus élevé (resp. bien moindre) qu'attendu selon les biologistes. Ce problème mène à une modélisation probabiliste non-linéaire et n'entre ainsi pas dans le cadre abordé dans la première partie de cette thèse. Nous traitons ainsi dans cette partie le cas de modèles linéaires généralisés, avec de nouveau des paramètres individuels en plus du prédicteur linéaire, et analysons les propriétés statistiques d'une nouvelle procédure estimant simultanément les coefficients de régression et les paramètres individuels. Nous utilisons de nouveau la pénalisation SLOPE mais nous nous restreignons au cas de la petite dimension. La performance de l'estimateur est mesuré comme dans la première partie en terme d'erreur d'estimation des paramètres et de taux de fausse découverte concernant la recherche du support du vecteur des paramètres individuelsThe problems of outliers detection and robust regression in a high-dimensional setting are fundamental in statistics, and have numerous applications.Following a recent set of works providing methods for simultaneous robust regression and outliers detection,we consider in a first part a model of linear regression with individual intercepts, in a high-dimensional setting.We introduce a new procedure for simultaneous estimation of the linear regression coefficients and intercepts, using two dedicated sorted-l1 convex penalizations, also called SLOPE.We develop a complete theory for this problem: first, we provide sharp upper bounds on the statistical estimation error of both the vector of individual intercepts and regression coefficients.Second, we give an asymptotic control on the False Discovery Rate (FDR) and statistical power for support selection of the individual intercepts.Numerical illustrations, with a comparison to recent alternative approaches, are provided on both simulated and several real-world datasets.Our second part is motivated by a genetic problem. Among some particular DNA sequences called multi-satellites, which are indicators of the development or colorectal cancer tumors, we want to find the sequences that have a much higher (resp. much lower) rate of mutation than expected by biologist experts. This problem leads to a non-linear probabilistic model and thus goes beyond the scope of the first part. In this second part we thus consider some generalized linear models with individual intercepts added to the linear predictor, and explore the statistical properties of a new procedure for simultaneous estimation of the regression coefficients and intercepts, using again the sorted-l1 penalization. We focus in this part only on the low-dimensional case and are again interested in the performance of our procedure in terms of statistical estimation error and FDR
38
Viguier, Jérôme. "Identification de facteurs moléculaires prédictifs de la chimiosensibilité des cancers colorectaux". Paris 6, 2006. http://www.theses.fr/2006PA066324.
Pełny tekst źródła
39
Gay, L. J. "APC mutation spectra and microsatellite instability in colorectal cancer and their relationship with dietary and other lifestyle factors". Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599339.
Pełny tekst źródłaStreszczenie:
Mutation analysis of the mutation cluster region (MCR) of APC (codons 1276-1556) and MSI analysis was performed on 185 tumour samples from participants of the European Prospective Investigation into Cancer and Nutrition (EPIC) Norfolk Study, with the aim of relating the molecular changes to dietary and lifestyle information collected at the start of the study. For the APC analysis, genomic DNA was extracted from formalin-fixed archival tissue, amplified and sequenced. Repeat analysis identified mutations that were consistently found (confirmed), from those that were not (unconfirmed). Overall, 43% of cancers had a confirmed mutation with hotspots at codons 1276, 1306, 1415, 1450 and 1556. Comparison of APC mutations by clinico-pathological features (sex, age, BMI, tumour site and Dukes’ stage) revealed that proximal colon tumours had more confirmed point mutations, whereas distal tumours had more transversions (P = 0.04). Negative MLH1 protein expression, high MLH1 promoter methylation (>50%) and MSI-High tumours were more likely to be from female cases, proximal in location and early Dukes’ stage (P = 0.03, 0.02 and 0.001 respectively). Case analysis of APC and MSI patterns by smoking status, red and processed meat consumption revealed that cases with processed meat intake above the mean (>26 g/day) were more likely to have confirmed GC to AT transitions (P = 0.05). In summary, this detailed study of APC and MSI patterns showed that the APC mutation spectra differed by tumour site, possibly due to the different physiological environments in the colon. MSI-H tumours were distinct, highlighting the different MSI pathway. The association of CRC with processed meat consumption suggests a mechanistic link between dietary alkylating agents, such as N-Nitroso compounds, and GC to AT transitions.
40
Miquel, Catherine. "Caractérisation des mutations des gènes cibles de l' instabilité des séquences répétées microsatellites dans les cancers colorectaux humains". Paris 6, 2005. http://www.theses.fr/2005PA066336.
Pełny tekst źródła
41
Chalastanis, Alexandra. "Etude des facteurs associés à l'instabilité des microsatellites dans l'initiation et la progression des tumeurs déficientes dans le système de réparation des mésappariements de bases de l'ADN". Paris 6, 2009. http://www.theses.fr/2009PA066580.
Pełny tekst źródłaStreszczenie:
L’inactivation du système de réparation des mésappariements de bases (MMR pour "MisMatch Repair") ne constitue pas per se un évènement transformant mais il induit un processus oncogénique d’instabilité génomique affectant les séquences répétées ou microsatellites de l’ADN (tumeurs MSI pour "MicroSatellite Instable"). Au cours de ma thèse, j’ai étudié le rôle de l’azathioprine, un immunosuppresseur fréquemment prescrit chez l’homme, dans l’oncogenèse MSI. J’ai démontré in vivo que cette molécule induisait un processus tumorigénique MSI chez la souris, notamment lorsqu’elle était administrée à des animaux porteurs à l’état hétérozygote d’une mutation constitutionnelle d’un gène MMR (équivalent murin du syndrome de prédisposition familiale aux cancers MSI). Ce travail se situe dans la continuité d’autres études menées au laboratoire auxquelles j’ai contribuées et qui ont permis de rapporter la survenue de lymphomes et cancers digestifs MSI chez des patients fréquemment traités par cet immunosuppresseur. Au total, mes résultats indiquent que l’azathioprine est un facteur iatrogénique favorisant l’émergence de tumeurs MSI. Dans une deuxième partie de mon travail, je me suis intéressée au rôle de l’instabilité chromosomique (CIN) dans l’oncogenèse MSI. J’ai analysé une grande série rétrospective de cancers du côlon et démontré que, contrairement à ce qui est décrit dans la littérature, ces deux types d’instabilité génétique ne sont pas mutuellement exclusifs. Un modèle suggérant un rôle particulier de CIN, complémentaire de MSI au cours de la progression tumorale a été proposé.
42
Pyatt, Robert E. "Microsatellite instability and large, genomic alterations of DNA mismatch repair genes in the etiology of HNPCC and sporadic tumors /". The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486572165278995.
Pełny tekst źródła
43
Ezzatizadeh, Vahid. "Friedreich ataxia : investigating the relationships between mismatch repair gene expression, FXN gene expression and GAA repeat instability in human and mouse cells and tissues". Thesis, Brunel University, 2012. http://bura.brunel.ac.uk/handle/2438/7626.
Pełny tekst źródłaStreszczenie:
Friedreich ataxia (FRDA) is the most common inherited ataxia disorder, caused by a GAA repeat expansion mutation within the first intron of the FXN gene. The subsequent deficiency of frataxin protein leads to neurological disability, increased risk of diabetes mellitus, cardiomyopathy and premature death. The exact FRDA disease mechanism is not yet clear, despite some understanding of epigenetic, transcriptional and DNA repair system effects that lead to frataxin reduction. Previous studies have shown that mismatch repair (MMR) genes can affect other trinucleotide repeat disorders by destabilisation of the repeats. Furthermore, it has been proposed that frataxin deficiency might lead to cell malignancy by an as yet undefined mode of action. Therefore, the principle aim of this thesis was to use human and genetically altered mouse cells and tissues to understand the effects of MMR proteins on GAA repeat instability and FXN transcription, and also to identify potential changes in MMR transcription that might cause malignancy in FXN-defective human cells. Firstly, by using FXN and MMR genetically altered mice, MMR proteins were shown to be involved in both intergenerational and somatic GAA repeat instability, although their effects in the two systems were different. Thus, Msh2 or Msh3 were both found to protect against intergenerational transmission of GAA contractions, while loss of Msh2 or Msh3 reduced somatic GAA repeat expansions and increased levels of FXN transcription in brain and cerebellum tissues. Loss of Msh6 induced both intergenerational GAA repeat expansions and contractions, while the frequency of somatic GAA repeat expansions was reduced. Curiously, the level of FXN transcription was also reduced in Msh6-deficient brain and cerebellum tissues. On the other hand, Pms2 was found to protect against both intergenerational and somatic GAA repeat expansions, with loss of Pms2 causing increased GAA repeat expansions and decreased levels of FXN transcription in brain and cerebellum tissues. Finally, loss of Mlh1 led to a reduced frequency of both intergenerational and somatic GAA repeat expansions, but the level of FXN transcription was also reduced in brain and cerebellum tissues. Furthermore, upregulation of MMR mRNA expression was detected in human FRDA fibroblast cells, but downregulation was seen in FRDA cerebellum tissues, suggesting tissue-dependent control of FXN and MMR expression. In summary, these studies indicate that the MMR system can affect GAA repeat expansion instability and FXN transcription through different mechanisms of action. Furthermore, frataxin deficiency can also affect the levels of MMR mRNA expression in a tissue-dependent manner. These findings will assist future investigations aimed at identifying novel FRDA therapies.
44
Vaurs-Barrière, Catherine. "Approches de l'oncogenese mammaire liee a brca1 : identification de genes exprimes differentiellement dans un contexte de predisposition hereditaire liee a brca1 et recherche d'une implication potentielle de brca1 dans le phenomene d'instabilite microsatellitaire". Clermont-Ferrand 1, 1998. http://www.theses.fr/1998CLF1MM07.
Pełny tekst źródła
45
Majed, Zeina. "Elaboration d'un nouveau modèle pour la caractérisation de nouveaux gènes impliqués dans la stabilité des sites fragiles". Montpellier 1, 2009. http://www.theses.fr/2009MON1T022.
Pełny tekst źródłaStreszczenie:
Les sites fragiles sont des sites récurrents de cassures, favorisant l'apparition de remaniements chromosomiques et participant ainsi à la progression tumorale. Les mécanismes et les gènes impliqués dans cette fragilité chromosomique sont actuellement peu connus. Afin de mieux comprendre ces mécanismes, nous avons établis un nouveau modèle d'étude. Ce modèle est constitué de clones cellulaires issus de la lignée HCT116 MMR déficiente, pour lesquels un ou plusieurs gènes cibles, potentiellement impliqués dans la stabilité des sites fragiles, possèdent une mutation l'inactivant partiellement. Nous avons sélectionné et analysé 20 gènes codant pour des protéines impliquées dans les voies de signalisation de la réponse aux dommages de l'ADN, au stress réplicatif et à la condensation des chromosomes. Nous avons ainsi établi une collection de 200 clones cellulaires qui portent des mutations dans 13 gènes étudiés. Nous avons ensuite mis en évidence le rôle de la mutation obtenue dans le gène ATR dans l'inactivation de ce dernier en favorisant l'accumulation des cassures au niveau des sites fragiles. Ces résultats nous ont permis de proposer un système modèle constituant un outil de choix pour l'étude des sites fragiles. Dans une étude menée en parallèle, nous nous sommes intéressés au gène MCPH1/BRIT1 codant pour une protéine impliquée dans plusieurs processus cellulaires. Nous avons pu mettre en évidence qu'une dérégulation du gène MCPH1/BRIT1 engendre une instabilité chromosomique et une accumulation des cassures au niveau des sites fragilesCommon fragile sites are chomosomal regions involved in recurrent breaks, which are "expressed" under various physiological stresses, most of them are known to disturb DNA replication. A direct link between fragile sites and emergence of various types of chromosomal rearrangement has been established, even in early stages of tumorigenesis. However, only few genes involved in genome stability at fragile sites have been identified. The aim of this study is to identify new genes involved in the expression of fragile sites and to elucidate molecular processes that affect their stability. We established a cell based system on a mismatch repair deficient background. 20 candidate genes were targeted in this study. We examined the incidence of frameshift mutations in 32 mononucleotide repeats of these genes. 17 frameshift mutations were found. We demonstrate that frameshift mutations affecting coding mononucleotide repeat of ATR, inactivate one of the two alleles leading to formation of breaks at fragile sites. This collection of clones gives us a unique cellular model to study precisely the maintenance of genome stability at fragile sites. Furthermore, we have investigated the effects of the deregulation of the expression of MCPH1/BRIT1 on common fragile site stability. MCPH1/BRIT1 acts as a regulator of both the intra-S and G2/M keckpoints. We show that deregulation of the expression of MCPH1/BRIT1 increase H2AX phosphorylation suggesting the accumulation of DNA double-strand breaks. This leads to formation of breaks at fragile sites. These findings demonstrate a critical role for the MCPH1/BRIT1 in regulating chromosome stability, and in particular, common fragile site
46
Takahashi(Mizuguchi), Aya. "Genetic features of multicentric/multifocal intramucosal gastric carcinoma". Kyoto University, 2019. http://hdl.handle.net/2433/243290.
Pełny tekst źródła
47
Bruhn, Norbert. "Mikrosatellitenalterationen in der Serum-DNA bei Patienten mit Bronchialkarzinom". Doctoral thesis, [S.l. : s.n.], 1999. http://deposit.ddb.de/cgi-bin/dokserv?idn=958164584.
Pełny tekst źródła
48
Marden, Aileen. "Development of a yeast-based assay system to enable rapid identification of the effects of dietary components on microsatellite instability in eukaryotic cells". Thesis, Heriot-Watt University, 2005. http://hdl.handle.net/10399/264.
Pełny tekst źródła
49
Ghanipour, Lana. "Colorectal Cancer : Aspects of Heredity, Prognosis and Tumour Markers". Doctoral thesis, Uppsala universitet, Kolorektalkirurgi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-224624.
Pełny tekst źródłaStreszczenie:
Colorectal cancer (CRC) is one of the most common cancer types and leading causes of cancer death worldwide. Since CRC is a heterogenic disease, there is a demand for increased knowledge of the underlying genetic and epigenetic mechanisms. The aim of this thesis was to investigate heredity and potential tumour markers in relation to prognosis. In paper I, survival of patients with CRC and a positive family history of CRC in first-degree relatives was analysed. Patients with colon cancer and positive family history of CRC had improved survival compared to patients with negative family history. This improvement in survival could not be explained by known clinico-pathological factors. In paper II, we investigated the prognostic value of Tryptophanyl t-RNA synthetase (TrpRS) in tissues from patients operated for CRC. Low protein expression of TrpRS in primary tumour tissues correlated with increased risk of recurrence and poorer survival. In paper III, the prognostic value of microsatellite instability (MSI) and the correlation to heredity for CRC in first-degree relatives was investigated. Patients with proximal colon cancer and MSI had improved cancer specific survival. There were no correlation between MSI and heredity. In paper IV, we evaluated the potential use of proximity ligation assay (SP-PLA) in patients with CRC, by simultaneous analysis of 35 proteins in only 5 μl plasma. SP-PLA is a suitable method for protein detection and might give valuable guidance in pursuing new prognostic and predictive tumour markers. However, none of the markers selected for present SP-PLA analyses gave better prognostic information than CEA. In conclusion, heredity is related to better survival independent of MSI in patients with CRC and MSI is associated with better prognosis in proximal colon cancer. Detection and increased knowledge of molecular mechanism in CRC is important, however it needs to be further investigated and validated in clinical use.
50
Capizzi, Carmela. "Novel genomic technologies and molecular diagnostics in Colorectal Cancer". Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/919.
Pełny tekst źródłaStreszczenie:
Cancer is a disease of the genome that is characterized by substantial variability in the clinical course and response to therapies. Colorectal cancer (CRC) is a heterogeneous cancer and represents an ideal model to investigate and elucidate the genetic alterations involved in tumor onset and progression. In this study 51 CRC patients were subdivided into groups according to the presence of microsatellite instability (MSI) and chromosomal instability (CIN). Of the 51 CRCs, 13.73% were MSI and 86.27% were microsatellite stable (MSS). The frequency of KRAS mutations in MSI-H and in MSS cancer was 28.57% and 40.91%, respectively.
To identify and characterize genomic alteration associated with colorectal cancer (CRC) the samples were analyzed with the last generation of Affymetrix single nucleotide polymorphism/CNV microarrays (SNP Array 6.0) and two new tools were implemented, Broad Cytogenetic Analysis (BroCyA) and Focal Cytogenetic Analysis (FoCyA), to identify broad (> ¼ chromosomal arm) and focal aberrations (< ¼ chromosomal arm). Broad copy number gains were noted on chromosomes 7, 8q, 9, 13q, 17q, 20 and broad copy number losses on chromosomes 4, 5q, 8p, 17p, 18, 19p, 20p and 22q. Moreover recurrent high level amplifications (HLAs) (copy number > 5.2) were located on chromosome 20, in regions containing known cancer pathway genes as STK4 and ID1, and homozygous deletions (HoD) containing potential new candidate tumor, suppressors such as BTG4 and D4S234E were located on chromosomes 11 and 4.
Recurrent somatic focal events (gains and losses) were identified in regions encompassing potential new candidate tumor suppressors and oncogenes, such as A2BP1 and PRDM16
Finally, several copy neutral-loss of heterozygosities (CN-LOHs) were detected, more frequently on chromosome 7p and 22q.
In conclusion, in this study some novel broad and focal copy number abnormalities (CNAs) and CN-LOHs were revealed in CRC. The precise and large-scale measurement of CNAs and CN-LOHs in the CRC genome provides a list of genes that might be involved in cancer development.