Made available in DSpace on 2016-01-26T12:51:19Z (GMT). No. of bitstreams: 1 suelisuzigan_tese_parte5.pdf: 78044 bytes, checksum: ede6079670fe7d13ddd7e25ead03f505 (MD5) Previous issue date: 2002-05-03 / Introduction. Tumor growth and metastasis depend greatly on angiogenesis. There are several angiogenic growth factors able to induce new vessels in renal tumors, but the most important are vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (b-FGF). The aim of our study was to investigate expression of b-FGF and to quantify microvessel density (MVD) in oncocytomas and renal cell carcinomas (RCCs) and to relate these parameters of tumor vascularity to other clinicopathological features. Material and Methods. b-FGF and CD31 immunostaining were performed on formalin-fixed paraffin-embedded archival tissues from Larpac Laboratories files, including 36 RCCs (10 conventional, 10 papillary, 8 sarcomatoid, and 8 chromophobe) and 5 oncocytomas. Angiogenesis was quantified microscopically by two independent observers. Results. b-FGF was positive in all five oncocytomas and only in seven of 36 RCCs: 5 of conventional type, 1 papillary, and 1 chromophobe. All sarcomatoid carcinomas were negative. The expression of b-FGF was not related to tumor size, grade, stage, or short survival in either group. MVD mean value was 124.16 ± 50.1 in oncocytomas and 91.54 ± 52.4 in RCCs. The pattern of vascularization observed in oncocytomas was characterized by a fine vascular network around groups of tumor cells although in RCCs the microvessels tended to be more disorganized. When analyzing only carcinomas, patients who died within 12 months after the diagnosis had a tumoral MVD mean value significantly higher (124.12 ± 75.2) than that observed in patients who were still alive one year after diagnosis (80.34 ± 37.8). ix Conclusion. We demonstrate that b-FGF is expressed more often in oncocytomas than in RCCs but MVD is similar in both groups of tumors. The high expression of b-FGF in oncocytomas may reflect the peculiar pattern of vascularization of these tumors. High MVD in rapidly lethal RCCs is an indication that angiogenesis may be correlated with the degree of malignancy of these tumors. / O desenvolvimento dos tumores e das suas metastases dependem em grande parte da angiogenese tumoral. Existem varios fatores de crescimento capazes de induzir à neoformação vascular nas neoplasias renais, porém, os mais importantes são o fator de crescimento do entotélio vascular (vegf) e o fator de crescimento fibroblástico básico (bfgf). O objetivo deste estudo foi o de investigar a expressão do b-fgf e a densidade microvascular (dmv) nos oncocitomas e nos carcinomas de células renais (ccrs) e correlacionar estes parâmetros da vascularização tumoral com outros ascpectos clínico-patológicos. Material e métodos. O estudo imunohidtoquímico para o b-fgf e o cd31 (densidade microvascular) foi realizado em material fixado em formalina e incluído em parafina de 36 casos de ccrs (10 convencionais, 10 papilíferos, 8 sarcomatóides e 8 cromófobos) e 5 oncocitomas, oriundos de exames anátomo-patológicos por dois observadpres independentes. Resultados. Nota de Resumo Foi encontrada positividade para o b-fgf em todos os 5 casos de oncocitomas e em 7 dos 36 casos de ccrs: 5 do tipo convencional, um papilífero, e um cromófobo. Todos os carcinomas sarcomatóides mostraram-se negativos. A expressão tumoral do b-fgf não apresentou correlação com tamanho tumora, grau histológico, estadio patológico, ou sobrevida a curto prazo em nenhum dos grupos. O valor médio da dvm foi de 124,16 +/- 50,1 nos oncocitomas e de 91,54 +/- 52,4 nos ccrs. O padrão de vascularização observado nos oncocitomas era caracterizado por um delicado leito vascular envolvendo grupos de celulas tumorais, enquanto que nos ccrs a microvascularização se apresentou de forma mais organizada. Entre os carcinomas, os tumores que se mostraram letais nos 12 primeiros meses após o diagnóstico, apresentaram um ídice angiogênico significativamente maior (124,12 +/- 75,2) em relação aos pacientes que ainda permaneciam vivos um ano após o diagnóstico (80,34 +/- 37,8). Conclusão. Demostramos que o b-fgf está expresso mais freqüentemente nos oncocitomas do que nos ccrs. Nota de Resumo Apesar de as dmv ser semelhante em ambos os grupos tumorais, observou-se um padrão de vascularização característico nos oncocitomas. Uma dvm mais elevada nos ccrs, rapidamente letais é indicativo de que a angiogenese possa estar correlacionada com grau de malignidade destes tumores.

La transition épithélio-Mésenchymateuse (TEM) est un processus de plasticité cellulaire qui existe dans le développement embryonnaire et qui permet la formation des tissus et organes. Dans la cancérogénèse, ce processus est réactivé par des facteurs de transcription dont l’action implique très probablement un remodelage de la chromatine. La cartographie exacte de ces changements épigénétiques est peu connue à l’échelle du génome entier, même si il y a eu quelques études antérieures explorant les changements de quelques loci de façon bien ciblée. Ce mémoire traite du remodelage épigénétique médié par le facteur de transcription Twist1 dans un modèle de lignée mammaire immortalisée. L’architecture de ce remodelage a été cartographiée grâce à l’utilisation des techniques de haut-Débit pour analyser la méthylation de l’ADN (DREAM) et les modifications des histones (ChIPseq). Nos résultats montrent un changement majeur du méthylome pendant la TEM avec une hyperméthylation focale et une hypométhylation globale des corps des gènes prédominant au niveau des « domaines partiellement méthylés »; ces domaines sont déjà connus dans le développement pour gagner de façon concomitante à leur hypométhylation des marques d’histone répressives. Nous avons aussi observé un remodelage des domaines de l’histone répressive H3K27me3 avec une réduction de leur taille, et surtout le quasi doublement du nombre de gènes bivalents qui accompagne la transition. Le couplage de la méthylation de l’ADN avec le profil des microRNA nous a permis d’identifier le miR-203 comme l’unique microRNA régulé par méthylation de l’ADN durant la TEM; nous avons aussi montré que l’extinction épigénétique du miR-203 est requise pour la TEM et l’acquistion des propriétés de cellules souches. Enfin, nous avons réalisé une caractérisation génétique et/ou épigénétique de deux cancers rares, les carcinomes fibrolamellaires du foie et les carcinomes du rein à translocation. Pour les carcinomes fibrolamellaires du foie, nous avons décrit la nature endocrine de cette tumeur et établi une signature épigénétique basée sur la méthylation de l’ADN pouvant servir à différencier les formes histologiques appelées « pures » des formes « mixtes ». Pour les cancers du rein à translocation, nous avons montré les bases génétiques et épigénétiques de la différence entre les formes pédiatriques et adultes, avec la découverte fréquente du gain du bras chromosomique 17q dans les formes adultes. Nous avons aussi identifié une mutation récurrente dans le gène qui remodèle la chromatine INO80D appartenant à la famille INO80. En conclusion, ce travail explore le rôle de l’étude de l’épigénome pour comprendre la reprogrammation pendant les processus physiologiques comme la TEM d’une part et le cancer d’autre part. / The epithelial-Mesenchymal transition (EMT) is a process of cellular plasticity that exists in embryonic development and which allows the formation of tissues and organs. In carcinogenesis, the process is reactivated by transcription factors whose action probably involves chromatin remodeling. The exact mapping of these epigenetic changes is poorly understood genome-Wide, although there have been some previous studies exploring changes in so few well-Targeted loci. This thesis deals with the epigenetic remodeling mediated by the transcription factor Twist1 in a model of human mammary immortalized cell line. The architecture of this remodeling has been mapped through the use of high-Throughput techniques to analyze DNA methylation (DREAM) and histone modifications (ChIPseq). Our results suggest a major change in the EMT methylome with focal hypermethylation and gene body hypomethylation predominantly within "partially methylated domains"; these areas are already known in development to gain repressive histone marks concomitantly with DNA hypomethylation. We also observed landscape remodeling of repressive histone mark H3K27me3 with a reduction in domains size, and especially the almost doubling of the number of bivalent genes. The coupling of DNA methylation with the profile of microRNA has allowed us to identify miR-203 as single microRNA regulated by DNA methylation during EMT; we have also shown that epigenetic suppression of miR-203 is both required for EMT and acquisition of stem cell properties. Finally, we performed a genetic and/or epigenetic characterization of two rare cancers, named fibrolamellar hepatocellular carcinomas and translocation renal cell carcinomas. In fibrolamellar hepatocellular carcinoma, we described the endocrine nature of this tumor and established a signature based on DNA methylation which can be used to distinguish histological forms called "pure" from "mixed" fibrolamellar hepatocellular carcinomas. Regarding translocation renal cell carcinomas, we established the genetic and epigenetic basis of differences between pediatric and adult forms, characterized by frequent gain of 17q gain chromosomal arm in adults. We also identified recurrent mutations in the chromatin remodeling gene INO80D which belongs to INO80 family. In conclusion, this work explores the impact of analyzing the epigenome to understand reprogramming during physiological processes such as EMT and cancer.