Les cancers colorectaux (CCR) constituent un véritable problème de santé publique. En France, en 2015, ils se situent au 3ème rang des cancers et au 2ème rang des décès par cancer, en raison d’un diagnostic souvent tardif et de réponses variables aux thérapeutiques. L’amélioration des tests de dépistage ces vingt dernières années n’a pas significativement réduit la morbi/mortalité liée au CCR et une meilleure caractérisation des différents sous-types moléculaires reste importante pour l’identification de nouveaux biomarqueurs. Les tumeurs colorectales sont hétérogènes tant sur le plan clinico-pathologique que moléculaire, issues de différentes voies de cancérogenèse. Les tumeurs de la voie festonnée représentent 20 à 30% des CCR. Elles sont caractérisées par une instabilité épigénétique (CpG Island Methylation Phenotype, CIMP), une instabilité microsatellitaire (MSI) et des mutations fréquentes du gène BRAF. Sur le plan phénotypique, ce sont des tumeurs volontiers mucisécrétantes surexprimant les mucines MUC2 et MUC5AC. L’identification précoce de leurs précurseurs reste actuellement un enjeu, d’autant que la séquence carcinogénétique des tumeurs festonnées serait particulièrement rapide.Dans cette étude, nous avons déterminé les caractéristiques clinico-pathologiques et moléculaires d’une série de cancers et polypes colorectaux et évalué l’intérêt des gènes de mucines MUC2 et MUC5AC pour classer les polypes festonnés et identifier les lésions précurseurs des cancers CIMP/MSI.L’étude a porté sur 418 CCR et 330 polypes coliques, incluant 218 polypes festonnés et 112 adénomes conventionnels, dont nous avons déterminé le profil moléculaire (mutations KRAS/BRAF, MSI, CIMP, méthylation MGMT, MLH1), ainsi que le profil d’expression et de méthylation des gènes de mucines MUC2 et MUC5AC. Les résultats ont été comparés aux données cliniques et anatomo-pathologiques.Nous montrons que l’hypométhylation du gène MUC5AC est un marqueur spécifique des CCR CIMP/MSI, indépendant des données clinico-pathologiques. De plus, nous montrons que l’hypométhylation de MUC5AC est un évènement précoce qui est spécifiquement associé aux polypes hyperplasiques de type microvésiculaire (MVHP) et adénomes festonnés sessiles (SSA), suggérant une filiation entre ces deux lésions, qui seraient les précurseurs des CCR CIMP/MSI. L’hypométhylation de MUC5AC était par ailleurs très spécifique des lésions festonnées mutées BRAF, CIMP ou MSI.En conclusion, nos résultats suggèrent un rôle de la mucine MUC5AC dans le développement des tumeurs coliques de la voie festonnée. L’hypométhylation du gène MUC5AC est un évènement précoce qui pourrait avoir un intérêt pour le diagnostic des polypes festonnés, en particulier lorsque la morphologie est ambiguë, et pour l’identification précoce des lésions à potentiel malin. De plus, nos résultats suggèrent que certains MVHP pourraient progresser en SSA et en CCR CIMP/MSI, d’où l’importance de réaliser des biopsies des polypes festonnés lors de l'endoscopie afin de repérer le sous-type microvésiculaire parmi les polypes hyperplasiques colorectaux, qui pourrait, bénéficier d’une surveillance minimale. / Colorectal cancer (CRC) is a major public health problem yet it remains the third most common and the second deadliest cancer for both men and women in the United States and in Europe, owing to diagnosis at advanced stage and variable response to the treatments. However, the incidence and mortality appear to be steadily declining in countries with programmatic screening and it remains critical to characterize CRC molecular subtypes to identify new biomarkers. CRC display a wide clinicopathological and molecular heterogeneity and arise from different carcinogenesis pathway. Approximately 20% to 30% of CRC occur by the means of the serrated neoplasia pathway. CRC from the serrated pathway are associated with frequent epigenetic instability (CIMP, CpG island methylator phenotype) which causes most sporadic microsatellite instability (MSI) CRC through epigenetic inactivation of MLH1 and frequent BRAF mutation. CRC from the serrated pathway frequently display a mucinous pattern and are prone to express secreted mucins MUC2 and MUC5AC. Early identification of serrated pathway precursor lesions is currently challenging since the progression to adenocarcinoma in this pathway is particularly brief.We assessed in this study clinicopathological and molecular features of colorectal carcinomas and polyps and we analyzed the interest of mucin genes MUC2 and MUC5AC to classify serrated polyps and to identify the precursor lesions of CIMP/MSI carcinomas._x000D_A series of 418 CRC and 330 polyps was included in the study, with 218 serrated polyps and 112 conventional adenomas. We assessed the molecular profile (KRAS/BRAF mutations, MSI, CIMP, MGMT methylation, MLH1) and the expression and methylation profile of MUC2 and MUC5AC genes and further correlation with clinical and pathological data were performed.We show that MUC5AC hypomethylation is a specific marker of CIMP/MSI CRC, independently of other clinical or pathological factors. We show moreover than MUC5AC hypomethylation is an early event of carcinogenesis, specific to microvesicular hyperplastic polyps (MVHP) and sessile serrated adenoma (SSA) suggesting a filiation between these two lesions and also a progression of MVHP to SSA, SSA with dysplasia, and then to MSI/CIMP CRC. MUC5AC hypomethylation was moreover highly specific of BRAF mutated, CIMP or MSI serrated lesions.In conclusion, our results suggest that the MUC5AC mucin is involved/plays a role in the development/progression of colorectal tumors of the serrated pathway. MUC5AC hypomethylation occurs early during carcinogenesis and may be of interest for the diagnosis of serrated polyp especially in the presence of ambiguous morphology and to early detection of polyps carrying a malignant potential. Our results suggest moreover that some MVHP may progress to SSA and CIMP/MSI CRCs highlighting the importance to perform biopsy of serrated polyps during endoscopy to identify microvesicular subtype among colorectal hyperplastic polyps, which could require a minimal surveillance.

Class of 2017 Abstract / Objectives: To determine the efficacy and toxicity of fluorouracil/leucovorin/oxaliplatin (FOLFOX) versus capecitabine/oxaliplatin (XELOX) in the treatment of colorectal cancer (CRC) in the adjuvant (aCRC) and metastatic (mCRC) setting in Veterans at the Southern Arizona Veteran Affairs Health Care System (SAVAHCS). Methods: A retrospective chart review was conducted to collect efficacy and toxicity data. Subjects were included based on age, treatment setting and regimen in the preset 5-year period, and appropriate diagnosis via International Classification of Diseases-Revision 9 (ICD-9) codes. Efficacy was measured via 1-year disease-free survival (DFS) for aCRC, progression-free survival (PFS) for mCRC, and overall survival (OS) for both settings. Results: A total of 79 subjects were initially enrolled with 51 and 54 all-male subjects included in the efficacy and toxicity analysis, respectively. Mean range of age was 63-72 years old. Subjects were divided into four groups: FOLFOX aCRC (17) and mCRC (19), XELOX aCRC (10) and mCRC (8). No difference was found in 1-year DFS and OS between aCRC groups, and PFS between mCRC groups; a higher incidence of 1-year OS with FOLFOX in the mCRC setting was noted (p = 0.03). No difference was found in toxicity between FOLFOX and XELOX, except a higher incidence of hand-foot syndrome in XELOX (p = 0.0007). Conclusions: Efficacy between FOLFOX and XELOX in aCRC and mCRC is similar, while toxicity is slightly more prevalent in XELOX due to increased hand-foot syndrome incidence. These findings agreed with the results reported by prospective clinical trials.

No description available.

One-carbon metabolism, a network of enzymatic reactions involving the transfer of methyl groups, depends on B-vitamins as cofactors, folate as a methyl group carrier, and amino acids, betaine, and choline as methyl group donors. One-carbon metabolism influences many processes in cancer initiation and development such as DNA synthesis, genome stability, and histone and epigenetic methylation. To study markers of one-carbon metabolism and inflammation in relation to colorectal cancer (CRC) risk, we used prediagnostic plasma samples from over 600 case participants and 1200 matched control participants in the population-based Northern Sweden Health and Disease Study cohort. This thesis studies CRC risk with respect to the following metabolites measured in pre-diagnostic plasma samples: 1) folate, vitamin B12, and homocysteine; 2) components of one-carbon metabolism (choline, betaine, dimethylglycine, sarcosine, and methionine); and 3) three markers of different aspects of vitamin B6 status. In addition, this thesis examines three homocysteine ratios as determinants of total B-vitamin status and their relation to CRC risk. In two previous studies, we observed an association between low plasma concentrations of folate and a lower CRC risk, but we found no significant association between plasma concentrations of homocysteine and vitamin B12 with CRC risk. We have replicated these results in a study with a larger sample size and found that low folate can inhibit the growth of established pre-cancerous lesions. Using the full study cohort of over 1800 participants, we found inverse associations between plasma concentrations of the methionine cycle metabolites betaine and methionine and CRC risk. This risk was especially low for participants with the combination of low folate and high methionine versus the combination of low folate and low methionine. Well-functioning methionine cycle lowers risk, while impaired DNA synthesis partly explains the previous results for folate. We used the full study cohort to study associations between CRC risk and the most common marker of vitamin B6 status, pyridoxal' 5-phosphate (PLP), and two metabolite ratios, PAr (4-pyridoxic acid/(PLP + pyridoxal)) estimating vitamin B6 related inflammatory processes and the functional vitamin B6 marker 3-hydroxykynurenine to xanthurenic acid (HK:XA). Increased vitamin B6-related inflammation and vitamin B6 deficiency increase CRC risk. Inflammation was not observed to initiate tumorigenesis. Total B-vitamin status can be estimated by three different recently introduced homocysteine ratios. We used the full study cohort to relate the ratios as determinants of the total B-vitamin score in case and control participants and estimated the CRC risk for each marker. Sufficient B-vitamin status as estimated with homocysteine ratios was associated with a lower CRC risk. These studies provide a deeper biochemical knowledge of the complexities inherent in the relationship between one-carbon metabolism and colorectal tumorigenesis.

Les dommages de l’ADN, induits par les traitements de chimiothérapie, sont responsables de l’induction de la sénescence, un arrêt définitif du cycle cellulaire dépendant des voies p53-p21 et p16-Rb. L'efficacité de cette suppression n’est pas optimale en raison d’une hétérogénéité de réponse à la chimiothérapie. Dans cette étude, nous avons analysé l’échappement à la sénescence en réponse à l’irinotécan, un traitement des cancers colorectaux. Dans les cellules LS174T, le processus de sénescence est induit mais des cellules conservent leurs capacités prolifératives et l’exercent après l’élimination du traitement. Les cellules proliférantes (PLD) et sénescentes (PLS) forment un mélange hétérogène appelé cellules persistantes (PLCs). Alors qu’elles sont constituées d’une part importante de cellules sénescentes, les PLCs sont capables de former des tumeurs in vivo, de manière comparable aux cellules parentales. De façon intéressante, le traitement est également associé à l’augmentation de l’agressivité caractérisée par la croissance en faible adhérence. L’émergence des PLD et la résistance à l’anoikis sont dépendantes de l’expression des protéines Mcl-1, Bcl-xL et p21. L’enrichissement des PLD et PLS, réalisé par cytométrie en flux, a permis d’identifier les PLS comme nécessaires à la résistance à l’anoikis. Les PLS pourraient donc créer un environnement favorable à la transformation de cellules non touchées par le traitement. Alors que le rôle de Mcl-1 et Bcl-xL dans chaque population reste à déterminer, l’utilisation d’inhibiteurs de ces protéines combinés à l’irinotécan pourrait limiter l’hétérogénéité de réponse à la chimiothérapie et l’agressivité tumorale. / Activated by chemotherapy, senescence is a suppressive response which prevents cell cycle progress through activation of the p53-p21 and p16-Rb signaling pathways. However, despite the efficiency of this suppression, cancer cells can emerge to induce clinical relapse. In this study, we analyzed senescence escape in response to irinotecan, one of the first line treatment used in colorectal cancer. After treatment, senescence is induced in LS174T cell but a subpopulation of cells finally resume proliferation. Persistent cells (PLCs) are composed of an heterogenous mixture of senescent (PLS) and dividing cells (PLD). In spite of PLS, PLCs are able to grow in vivo as efficiently as parental LS174T cells. Importantly, persistence induced the emergence of more transformed cells characterized by the ability to grow in low adhesion conditions. PLD emergence and anoikis resistance depend on Mcl-1, Bcl-xL and p21. PLD and PLS enrichment, by flow cytometry, allowed us to identify PLS as essential for anoikis resistance. Our results suggest that PLS establish a favorable environment for the transformation of unaffected cells. Mcl-1 and Bcl-xL role in each population remains to be determined, but inhibitors of these protein used in combination with irinotecan should restrict the heterogeneity of the response and tumoral aggressiveness.

The aim of thesis is to identify and quantify the cost for therapy of colorectal cancer. The aim is to quantify the cost of individual treatments normally used in different stages of the disease and the total cost of treatment.

Os microRNAs (miRNAs) são pequenos RNAs não codificadores de proteínas presentes na maioria dos eucariotos. Esses RNAs regulam a expressão gênica em nível pós-transcricional através do silenciamento de mRNAs-alvo que possuem sítios complementares às suas sequências, atuando em praticamente todos os processos celulares. Embora a estrutura e função dos miRNAs estejam bem caracterizadas, aspectos relacionados à sua organização genômica, evolução e atuação em doenças são tópicos que apresentam enormes lacunas. Nesta tese, utilizamos abordagens computacionais para investigar estes temas em três trabalhos. No primeiro, processamos e integramos um vasto volume de dados publicamente disponíveis referentes aos miRNAs e genes codificadores de proteínas para cinco espécies de vertebrados. Com isso, construimos uma ferramenta web que permite a fácil inspeção da organização genômica dos miRNAs em regiões inter e intragênicas, o acesso a dados de expressão de miRNAs e de genes codificadores de proteínas (classificados em genes hospedeiros e não hospedeiros de miRNAs), além de outras informações pertinentes. Verificamos que a ferramenta tem sido amplamente utilizada pela comunidade científica e acreditamos que ela possa facilitar a geração de hipóteses associadas à regulação dos miRNAs, principalmente quando estão inseridos em genes hospedeiros. No segundo estudo, buscamos compreender como o contexto genômico e a origem evolutiva dos genes hospedeiros influenciam a expressão e evolução dos miRNAs humanos. Nossos achados mostraram que os miRNAs intragênicos surgem preferencialmente em genes antigos (origem anterior à divergência de vertebrados). Observamos que os miRNAs inseridos em genes antigos têm maior abrangência de expressão do que os inseridos em genes novos. Surpreendentemente, miRNAs jovens localizados em genes antigos são expressos em um maior número de tecidos do que os intergênicos de mesma idade, sugerindo uma vantagem adaptativa inicial que pode estar relacionada com o controle da expressão dos genes hospedeiros, e como consequência, expondo-os a contextos celulares e conjuntos de alvos diversos. Na evolução a longo prazo, vimos que genes antigos conferem maior restrição nos padrões de expressão (menor divergência de expressão) para miRNAs intragênicos, quando comparados aos intergênicos. Também mostramos possíveis associações funcionais relacionadas ao contexto genômico, tais como o enriquecimento da expressão de miRNAs intergênicos em testículo e dos intragênicos em tecidos neurais. Propomos que o contexto genômico e a idade dos genes hospedeiros são fatores-chave para a evolução e expressão dos miRNAs. Por fim, buscamos estabelecer associações entre a expressão diferencial de miRNAs e a quimioresistência em câncer colorretal utilizando linhagens celulares sensíveis e resistentes às drogas 5-Fluoruracil e Oxaliplatina. Dentre os miRNAs identificados, o miR-342 apresentou níveis elevados de expressão nas linhagens sensíveis à Oxaliplatina. Com base na análise dos alvos preditos, detectamos uma significativa associação de miR-342 com a apoptose. A superexpressão de miR-342 na linhagem resistente SW620 evidenciou alterações na expressão de genes da via apoptótica, notavelmente a diminuição da expressão do fator de crescimento PDGFB, um alvo predito possivelmente sujeito à regulação direta pelo miR-342. / MicroRNAs (miRNAs) are short non-coding RNAs found in most eukaryotic species. These RNAs regulate gene expression at post-transcriptional level by silencing target mRNAs through base-pairing of complementary sequences, thus acting on virtually all cellular processes. Although the structure and function of miRNAs are well understood, several aspects related to their genomic organization, evolution and involvement with diseases are largely underexplored. In this thesis, we employed computational methods to investigate such issues in three different studies. In the first one, we have processed and integrated a large amount of public data related to miRNAs and coding genes for five vertebrate species. Then, we developed a webtool to allow the analysis of the miRNA genomic context in inter and intragenic regions, the access of miRNA and gene expression data (classified as host and non-host genes), as well as other relevant information. We noticed that the webtool has been largely used by the scientific community, and we believe that it can facilitate hypothesis generation related to miRNA regulation, especially when they are within host genes. In the following study, we sought to understand how the genomic context and the evolutionary origin of host genes can affect the expression and evolution of human miRNAs. Our findings showed that intragenic miRNAs are preferentially embedded within old host genes (originated before the split of vertebrates). We observed that miRNAs within old genes are more broadly expressed than those within young genes. Surprisingly, young miRNAs within old genes were expressed in more tissues than their intergenic counterparts, suggesting an initial adaptive advantage which might be related to their hosts expression control, and as a consequence, exposing them to a more diverse cellular contexts and target genes. In the long run, we found that old host genes lead to expression constraints (lower expression divergence) between species for intragenic miRNAs, in respect to intergenic ones. We also showed possible functional associations related to miRNA genomic context, such as the enrichment of young intergenic miRNAs in testis, while young intragenic miRNAs were enriched in neural tissues. Thus, we propose that the genomic context and the age of the host genes are key factors in shaping the expression and evolution of miRNAs. Finally, we sought to establish associations between differential expression of miRNAs and chemoresistance in colorectal cancer using resistant and sensitive cell lines to 5-Fluoruracil and Oxaliplatin. Among differentially expressed miRNAs, miR-342 was highly expressed in sensitive cell lines to Oxaliplatin. Based on target prediction analysis, miR-342 is likely associated with apoptosis. The induced overexpression of miR-342 in SW620, a cell line resistant to Oxaliplatin, changed the expression levels of genes linked to the apoptosis pathway, notably the downregulation of PDGFB growth factor, which is a predicted target possibly subjected to direct regulation by miR-342.

Colorectal cancer (CRC) is the second leading cancer killer in the United States and the third most common cancer in African American men and women. Though the overall death rates have declined, this reduction in mortality is smaller for African Americans than for Whites. Factors that are protective against colorectal cancer include occupational or recreational physical activity, a diet high in fruits and vegetables, and colorectal cancer screening with removal of polyps (polypectomy) before they progress to cancer. Compliance with CRC screening recommendations requires people to know if a first-degree relative (parent, sibling, and child) or second-degree relative (aunt, uncle, niece, nephew, and grandparent) has been diagnosed with colorectal cancer. Little is known about how patients disclose this information to their relatives and what type of information is disclosed when disclosure takes place. The role of the family has long been overlooked in research on African American health screening behavior despite the fact that family interventions have been known to produce favorable outcomes in diet, nutrition, and exercise. This qualitative study explored the disclosure process among African American colorectal cancer survivors and FDRs with whom they shared their diagnosis. Of special interest was the role of social support in the disclosure process and the criteria used to decide which relatives to tell. Findings from this study will be used to advance the knowledge about the dynamics of CRC disclosure to first-degree relatives in African American families and ultimately increase CRC screening in relatives.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第22364号 / 医博第4605号 / 新制||医||1043(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 濵﨑 洋子, 教授 松田 文彦, 教授 遊佐 宏介 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 新制・課程博士 / 博士(医学) / 甲第23067号 / 医博第4694号 / 新制||医||1049(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 今中 雄一, 教授 武藤 学, 教授 妹尾 浩 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM