Issu de remaniements chromosomiques, le gène de fusion TMPRSS2 :ERG a été identifié dans plus de 50% des cas des cancers de la prostate (CaP). Cette découverte a ouvert une nouvelle voie dans la compréhension du processus de cancérisation. De nombreuses études cliniques démontrent l’association de la présence de ce gène de fusion avec un mauvais pronostic. Erg (Ets-Related-Gene) est un facteur de transcription dont l’expression est associée, en particulier, à la mise en place du cartilage et plus largement du squelette. Une étude transcriptomique, comparant les transcriptomes des chondrocytes embryonnaires de souris sauvages et de souris transgéniques qui expriment une protéine ERG tronquée, à l’effet trans-dominant négatif, nous a permis d’identifier de nombreux marqueurs osseux et gènes associés à la métastase osseuse comme gènes cibles de ce facteur de transcription. Les CaP, lorsqu’ils évoluent, provoquent dans la plupart des cas des métastases osseuses. Ces résultats suggèrent un rôle potentiel du gène de fusion dans la formation de métastases osseuses du CaP.Pour notre étude, nous avons établi des lignées de cellules cancéreuses prostatiques PC3c qui expriment stablement le gène de fusion TMPRSS2 :ERG. Dans un premier temps, nous avons démontré que l’expression ectopique du gène de fusion renforce la migration et l’invasion des cellules PC3c de manière dose-dépendante. Une étude transcriptomique a révélé que l’expression de certains gènes associés à la migration et l’invasion est dérégulée suite à l’expression du gène de fusion. Grâce à cette étude, de nouveaux gènes cibles de TMPRSS2 :ERG ont été mis en évidence dans les CaPs. L’identification de ces nouveaux gènes cibles renforce l’hypothèse d’un rôle du gène de fusion dans les métastases du cancer de la prostate. Par ailleurs, ces lignées de cellules cancéreuses prostatiques qui expriment stablement TMPRSS2 :ERG ont été injectées dans les tibias des souris SCID pour établir un modèle de métastases osseuses induites. Nous avons démontré que les cellules PC3c exprimant stablement le gène de fusion sont capables d’induire des lésions ostéocondensantes, tandis que les cellules témoins induisent des lésions mixtes (ostéolytiques et ostéocondensantes). Ce modèle nous a permis, pour la première fois, d’associer ce gène de fusion avec la formation des métastases osseuses du CaP in vivo.L’ensemble des résultats contribue à comprendre l’influence qualitative et quantitative de l’expression de TMPRSS2 :ERG dans les métastases du CaP. / Prostate cancer (PCa) is one of the most common malignancies that affect men in western countries. Recurrent gene fusion, involving the ERG gene and the androgen-regulated TMPRSS2 gene promoter, occurs in over 50% of PCa. The TMPRSS2:ERG gene fusion results in aberrant ERG transcription factor expression in PCa. We and others have shown that the ERG transcription factor, a member of ETS family, is associated with embryonic skeleton development. Interestingly, some of the potential ERG-target genes, identified using high-throughput DNA microarray analysis, have implications in the physiological bone homeostasis or the pathological bone metastases development. Bone metastases are frequent and represent severe complications of PCa. This suggests a potential role of the TMPRSS2:ERG in PCa bone metastases.In this study, we used PC3c cells line (derived from PC3 cell line) to establish TMPRSS2:ERG-expressing clones cells. The ectopic expression of the fusion resulted in significant induction of cell migration and invasion in a dose-dependent manner. In agreement with this phenotype, high-throughput microarray analysis revealed that a set of genes, functionally associated with cell motility and invasiveness, were deregulated in a dose-dependent manner in TMPRSS2:ERG-expressing cells. Importantly, further analyses of these deregulated genes revealed that some of them are direct target genes of TMPRSS2:ERG in PCa. These results provide novel insights into the role of the TMPRSS2:ERG fusion in PCa metastasis. To test the hypothesis of the implication of ERG in bone metastases development, we used an experimental bone metastases induction model. The implantation of the TMPRSS2:ERG-expression PC3c cells in the tibia of the SCID mice induced osteoblastic bone lesions, whereas the control PC3c resulted in mixed bone lesions. Our results show, for the first time, the possible implication of TMPRSS2:ERG in CaP bone metastasis formation.To summarize, this study provided novel evidences of the role of TMPRSS2:ERG fusion in PCa metastasis.

Ce travail décrit un criblage systématique du système ubiquitine-protéasome (UPS) basé sur une organisation en cascade. Nous avons évalué l’effet de l’inhibition par ARN interférent de composants individuels d’UPS sur la viabilité de cellules cancéreuses de la prostate, avec un accent particulier sur les cellules TMPRSS:ERG-positive (VCaP), comme un modèle de phénotype prévalent du cancer. Sept gènes ont été identifiés comme étant particulièrement importants pour le fonctionnement des cellules cancéreuses de la prostate. Parmi eux, le gène-candidat le plus prometteur était UBE2U. Cette thèse met en évidence l’implication d’UBE2U dans la carcinogénèse de la prostate et décrit les premières caractérisations d’UBE2U comme une cible thérapeutique potentielle.La prévalence des composants de la voie CRL/NEDD8 parmi les hits (4 sur 7) suggère que la neddylation est importante dans la biologie des cellules cancéreuses de la prostate. Deux de ces gènes, CUL2 et RBX1, n’ont des effets spécifiques que dans des cellules TMPRSS2:ERG-positives, et, donc, sont potentiellement ERG-dépendantes. Nous avons également révélé un rôle crucial du facteur d’échange de CRL (CAND1), en particulier lorsque la neddylation est compromise. L’inhibition de CAND1 induit l’apoptose dans des cellules VCaP, qui est renforcé par l’inhibiteur spécifique de la neddylation MLN4924. CAND1 est donc une nouvelle cible thérapeutique potentielle. Par ailleurs, nous avons démontré que l’inhibition de la voie CRL/NEDD8 dans les cellules cancéreuses de prostate a des conséquences qui dépendent fortement du contexte cellulaire. L’inhibiteur MLN4924 induit l’apoptose dans toutes les lignées cellulaires testées, bien que les cellules TMPRSS2:ERG-positives se soient révélées significativement plus résistantes. Nous avons démontré que la résistance accrue des cellules VCaP reflète la plasticité des cellules cancéreuses régulée par un réseau d’interactions ERG:NF-kB:c-Myc:Wnt/β-cat:AR. L’inhibition partielle de la neddylation enclenche une reprogrammation transcriptionnelle de cellules VCaP, amenant à la quiescence des cellules et à l’inhibition de l’apoptose dépendant de la prolifération. Cet effet est le résultat de la réactivation du programme AR. Nous avons conclus que la voie CRL/NEDD8 régule le réseau transcriptionnel qui contrôle la plasticité des cellules cancéreuses. Ces résultats peuvent aider à trouver des traitements plus efficaces de cancers TMPRSS2:ERG-positifs.Finalement, nous avons observé que l’inhibition de la neddylation modifie les propriétés de la membrane et la morphologie des cellules VCaP. Cet effet est accompagné par des changements du taux et de la localisation de plusieurs protéines associées à la membrane, y compris l’occludine, la N-cadherine, la paxilline and FAK. Nous en avons conclus que la voie CRL/NEDD8 pourrait être impliquée dans le tri/trafic des protéines membranaires. Cette partie du projet nécessite de plus amples études, étant donné que la compréhension des mécanismes sous-jacents est importante et peut mettre à jour un nouveau rôle de la voie CRL/NEDD8 dans la régulation des fonctions cellulaires.Conclusion générales :1. Nous avons caractérisé l’implication de tous les composants E1-E2 d’UPS dans la régulation de la viabilité des cellules cancéreuses de prostate (avec cinq différentes lignées cellulaires).2. Nos travaux ont mise en évidence de nouvelles cibles thérapeutiques potentielles pour le traitement du cancer, telles qu’UBE2U et CAND1.3. Nous avons démontré le rôle de la voie CRL/NEDD8 dans la régulation de la plasticité et de la morphologie des cellules cancéreuses. / In this work we describe a systematic approach for screening of ubiquitin-proteasome system (UPS) based on cascade organization. We have evaluated the effect of RNAi knockdown of individual UPS components on viability of PCa cells with major focus on TMPRSS:ERG-positive cell line, VCaP, as a model of prevalent phenotype of prostate cancer. Seven genes have been identified to be particularly important for the functioning of PCa cells. Among them, UBE2U was the strongest hit. This thesis provides the first evidence for UBE2U involvement in prostate carcinogenesis and describes initial characterization of UBE2U as a potential drug-target.The prevalence of the components of CRL/NEDD8 pathway in the hits (four out of seven) suggested the importance of neddylation for PCa biology. Two of these hits, CUL2 and RBX1, being specific to TMPRSS2:ERG-positive cells, are potentially ERG-dependent. We have also revealed the crucial role of CRL-exchange factor CAND1, in particular, when the neddylation is compromised. Knockdown of CAND1 induces apoptosis in VCaP cells that is further potentiated by neddylation-specific inhibitor MLN4924. CAND1 is, therefore, a novel potential drug target. Furthermore, we have demonstrated that the inhibition of CRL/NEDD8 pathway in prostate cancer cells has a complex outcome that strongly depends on cellular context. MLN4924 inhibitor induced apoptosis in all tested cell lines, though TMPRSS2:ERG positive cells were significantly more resistant. We have demonstrated that the increased resistance of VCaP cells reflects the plasticity of cancer cells ensured by sophisticated interaction network ERG:NF-kB:c-Myc:Wnt/β-cat:AR. We found that partial inhibition of neddylation triggered transcriptional reprogramming of VCaP cells leading to cell quiescence and inhibition of proliferation-dependent apoptosis. This was a result of re-activation of AR program and induction of differentiation-like state. We conclude that CRL/NEDD8 pathway regulates cancer transcriptional network that underlies cancer cells plasticity. This knowledge would help to find better treatments for TMPRSS2:ERG-positive cancers.Finally, we observed that neddylation inhibition changed membrane properties and morphology of VCaP cells. This was accompanied by dose-dependent changes in the level and the localization of several membrane-associated proteins, including occludin, N-cadherin, paxillin and FAK. We thus conclude that CRL/NEDD8 pathway might be involved in sorting/trafficking of membrane proteins. This part of the work requires further investigation, as understanding of the underlying mechanisms is of general importance and may uncover a new role of CRL/NEDD8 pathway in regulation of cellular functions.General conclusions:1. We have obtained a comprehensive dataset on the involvement of all human E1-E2 UPS components in the regulation of viability of PCa cells, represented by five different cell lines.2. Our work has revealed new potential drug targets for PCa treatment: UBE2U and CAND1.3. We have demonstrated the role of CRL/NEDD8 pathway in the regulation of cancer cell plasticity and morphology.

O interesse científico em rearranjos gênicos relacionados com a etiogênese e progressão do câncer relaciona-se, principalmente, à descoberta da fusão BCR/ABL na Leucemia Mieloide Crônica, sendo que desde então, houve uma evolução no manejo dessa doença, instigando uma série de estudos correlatos em outras neoplasias. Essas pesquisas culminaram no encontro do primeiro rearranjo gênico em tumores sólidos, o gene de fusão TMPRSS2/ERG, envolvendo a região promotora do gene da serina protease, o TMPRSS2, e o gene da família de fatores de transcrição ETS, o ERG. Ele é específico de adenocarcinoma da próstata, o que o torna forte candidato a biomarcador e já demonstra exercer papel de destaque no manejo clínico do câncer de próstata (CaP), tal qual o exercido pela fusão BCR/ABL. Sua frequência têm se mostrado associada a diversos fatores, sobretudo à etnia de origem. Indivíduos portadores de CaP oriundos de diversos países já foram estudados quanto à frequência dessa fusão e o resultado é bastante diversificado. No Brasil, entretanto, ainda não há dados a respeito desse rearranjo, e este trabalho visa contribuir para a identificação da frequência da mesma e sua contribuição para o diagnóstico e o tratamento do CaP no país. Para tal, utilizamos mRNA de 20 indivíduos com CaP provenientes do serviço de atendimento do HCFMRP/USP, e por meio da técnica de RT-PCR, obtivemos o cDNA dos mesmos que foram investigados quanto à presença da fusão TMPRSS2/ERG, e as amostras positivas sequenciadas para determinação do tipo de isoforma envolvida. Identificamos que 35% das amostras continham o rearranjo e que todas correspondiam à isoforma do tipo III, cuja literatura a relaciona com um fenótipo agressivo do CaP, porém não metástico, e é também a mais comumente identificada. Ao confrontarmos essa evidência com os dados clínicos e histopatológicos, constatamos que havia correlação entre eles, sugerindo assim, como em outros trabalhos, o potencial desse rearranjo como marcador de agressividade do CaP. No entanto, não verificamos relação entre a presença da fusão e dados de progressão da doença. Em vista desses resultados, destacamos a necessidade da promoção de outros trabalhos de mesmo caráter, abrangendo outras regiões, a fim de se delinear um perfil mais representativo desse rearranjo no Brasil, uma vez que seu potencial como biomarcador diagnóstico e clínico é enorme e pode influenciar sobremaneira no manejo do CaP. / Scientific interest in gene rearrangements associated with cancer progression and etiogenesis relates mainly to the discovery of BCR/ABL fusion in chronic myelogenous leukemia, and since then there has been an evolution in the management of this disease, prompting a series of related studies in other malignancies. These researches resulted in the meeting of the first gene rearrangement in solid tumors, the fusion gene TMPRSS2/ERG involving the promoter region of the gene of serine protease, TMPRSS2, and the gene family of transcription factors ETS, the ERG. It is specific for adenocarcinoma of the prostate, which makes it a strong candidate biomarker and shows already exert a prominent role in the clinical management of prostate cancer (PCa), as is exercised by the BCR/ABL. Its frequency has been shown to be associated with several factors, especially the ethnic origin. Individuals with CaP from different countries have been studied in the frequency of this merger and the result is quite diverse. In Brazil, however, there is no data about this rearrangement, and this paper aims to contribute to the identification of the same frequency and its contribution to the diagnosis and treatment of PCa in the country. Therefore, we used mRNA from 20 individuals with CaP from the answering service HCFMRP/USP, and by RT-PCR, cDNA obtained from the same people who were investigated for the presence of fusion TMPRSS2/ERG, and positive samples sequenced to determine the type of isoform involved. We found that 35% of the samples contained the rearrangement and that all corresponded to the type III isoform, whose literature relates to an aggressive phenotype of PCa, but not metastatic, and is also the most commonly identified. When we compared this evidence with clinical and histopathological data, we found that there was a correlation between them, suggesting, as in other studies, the potential of this rearrangement as a agressivity marker of PCa. However, no significant association between the presence of data fusion and disease progression. In view of these results, we highlight the need to promote other works of the same character, covering other regions, in order to delineate a more representative profile of this rearrangement in Brazil, since its potential as a biomarker and clinical diagnosis is huge and can influence greatly in the management of PCa.

O interesse científico em rearranjos gênicos relacionados com a etiogênese e progressão do câncer relaciona-se, principalmente, à descoberta da fusão BCR/ABL na Leucemia Mieloide Crônica, sendo que desde então, houve uma evolução no manejo dessa doença, instigando uma série de estudos correlatos em outras neoplasias. Essas pesquisas culminaram no encontro do primeiro rearranjo gênico em tumores sólidos, o gene de fusão TMPRSS2/ERG, envolvendo a região promotora do gene da serina protease, o TMPRSS2, e o gene da família de fatores de transcrição ETS, o ERG. Ele é específico de adenocarcinoma da próstata, o que o torna forte candidato a biomarcador e já demonstra exercer papel de destaque no manejo clínico do câncer de próstata (CaP), tal qual o exercido pela fusão BCR/ABL. Sua frequência têm se mostrado associada a diversos fatores, sobretudo à etnia de origem. Indivíduos portadores de CaP oriundos de diversos países já foram estudados quanto à frequência dessa fusão e o resultado é bastante diversificado. No Brasil, entretanto, ainda não há dados a respeito desse rearranjo, e este trabalho visa contribuir para a identificação da frequência da mesma e sua contribuição para o diagnóstico e o tratamento do CaP no país. Para tal, utilizamos mRNA de 20 indivíduos com CaP provenientes do serviço de atendimento do HCFMRP/USP, e por meio da técnica de RT-PCR, obtivemos o cDNA dos mesmos que foram investigados quanto à presença da fusão TMPRSS2/ERG, e as amostras positivas sequenciadas para determinação do tipo de isoforma envolvida. Identificamos que 35% das amostras continham o rearranjo e que todas correspondiam à isoforma do tipo III, cuja literatura a relaciona com um fenótipo agressivo do CaP, porém não metástico, e é também a mais comumente identificada. Ao confrontarmos essa evidência com os dados clínicos e histopatológicos, constatamos que havia correlação entre eles, sugerindo assim, como em outros trabalhos, o potencial desse rearranjo como marcador de agressividade do CaP. No entanto, não verificamos relação entre a presença da fusão e dados de progressão da doença. Em vista desses resultados, destacamos a necessidade da promoção de outros trabalhos de mesmo caráter, abrangendo outras regiões, a fim de se delinear um perfil mais representativo desse rearranjo no Brasil, uma vez que seu potencial como biomarcador diagnóstico e clínico é enorme e pode influenciar sobremaneira no manejo do CaP. / Scientific interest in gene rearrangements associated with cancer progression and etiogenesis relates mainly to the discovery of BCR/ABL fusion in chronic myelogenous leukemia, and since then there has been an evolution in the management of this disease, prompting a series of related studies in other malignancies. These researches resulted in the meeting of the first gene rearrangement in solid tumors, the fusion gene TMPRSS2/ERG involving the promoter region of the gene of serine protease, TMPRSS2, and the gene family of transcription factors ETS, the ERG. It is specific for adenocarcinoma of the prostate, which makes it a strong candidate biomarker and shows already exert a prominent role in the clinical management of prostate cancer (PCa), as is exercised by the BCR/ABL. Its frequency has been shown to be associated with several factors, especially the ethnic origin. Individuals with CaP from different countries have been studied in the frequency of this merger and the result is quite diverse. In Brazil, however, there is no data about this rearrangement, and this paper aims to contribute to the identification of the same frequency and its contribution to the diagnosis and treatment of PCa in the country. Therefore, we used mRNA from 20 individuals with CaP from the answering service HCFMRP/USP, and by RT-PCR, cDNA obtained from the same people who were investigated for the presence of fusion TMPRSS2/ERG, and positive samples sequenced to determine the type of isoform involved. We found that 35% of the samples contained the rearrangement and that all corresponded to the type III isoform, whose literature relates to an aggressive phenotype of PCa, but not metastatic, and is also the most commonly identified. When we compared this evidence with clinical and histopathological data, we found that there was a correlation between them, suggesting, as in other studies, the potential of this rearrangement as a agressivity marker of PCa. However, no significant association between the presence of data fusion and disease progression. In view of these results, we highlight the need to promote other works of the same character, covering other regions, in order to delineate a more representative profile of this rearrangement in Brazil, since its potential as a biomarker and clinical diagnosis is huge and can influence greatly in the management of PCa.

Shortcomings of current methods of prostate cancer detection draw attention to a need for improved biomarkers. The TMPRSS2:ERG gene fusion leads to the overexpression of ERG, an ETS family transcription factor, and is the most prevalent genetic lesion in prostate cancer, but its clinical utility remains to be defined. Two radical prostatectomy samples were analysed by next-generation whole transcriptome sequencing. The chosen samples differed in fusion gene status, as previously determined by RT-PCR. The involvement of novel and previously reported prostate cancer-related transcripts, Wnt signalling, p53 effector loss and several ETS-regulated pathways was identified in the prostate cancer cases examined. ERG was found to directly transactivate RhoGDIB, a gene associated with fusion-positive prostate cancer. Overexpression of RhoGDIB elicited spindle-shaped morphology, faster cell migration and increased cell proliferation, phenotypic changes suggestive of cancer progression. The present findings confirm the value of comprehensive sequencing for biomarker development and indicate avenues of future study.

Shortcomings of current methods of prostate cancer detection draw attention to a need for improved biomarkers. The TMPRSS2:ERG gene fusion leads to the overexpression of ERG, an ETS family transcription factor, and is the most prevalent genetic lesion in prostate cancer, but its clinical utility remains to be defined. Two radical prostatectomy samples were analysed by next-generation whole transcriptome sequencing. The chosen samples differed in fusion gene status, as previously determined by RT-PCR. The involvement of novel and previously reported prostate cancer-related transcripts, Wnt signalling, p53 effector loss and several ETS-regulated pathways was identified in the prostate cancer cases examined. ERG was found to directly transactivate RhoGDIB, a gene associated with fusion-positive prostate cancer. Overexpression of RhoGDIB elicited spindle-shaped morphology, faster cell migration and increased cell proliferation, phenotypic changes suggestive of cancer progression. The present findings confirm the value of comprehensive sequencing for biomarker development and indicate avenues of future study.

Prostate cancer is a clinically heterogeneous disease, with manifestations ranging from a rapid and often fatal progression, to indolent disease. Unfortunately, current clinicopathological criteria cannot differentiate men whose tumours require immediate and aggressive therapy from those in which active surveillance may be more appropriate. Both PTEN deletion and ETS gene fusions are biomarkers with potential to aid in prostate cancer clinical management. In this thesis, I postulate that PTEN and fusion gene rearrangements may be associated with specific genomic changes, and might also have general impact on the genomic landscape of prostate cancer. A meta-analysis of somatic copy number alterations (CNAs) examined 662 unique prostate cancer patient samples consisting of 546 primary and 116 advanced tumours derived from eleven publications. Normalization, segmentation and identification of corresponding CNAs for meta-analysis were achieved using established commercial software. The CNA distribution in primary disease was characterized by losses at 2q, 3p, 5q, 6q, 8p, 12p, 13q, 16q, 17p, 18q and 10q (PTEN), and acquisition of 21q deletions associated with the TMPRSS2:ERG fusion rearrangement. Unsupervised analysis identified five genomic subgroups. Parallel analysis of advanced and primary tumours indicated that PTEN genomic deletions and the gene fusion were enriched in advanced disease. A supervised analysis of PTEN deletions and gene fusions demonstrated that PTEN deletion was sufficient to impose higher levels of CNA. Moreover, the overall percentage of the genome altered was significantly higher when PTEN was deleted, suggesting that this important genomic subgroup was likely characterized by intrinsic chromosomal instability. Candidate genes in each of the recurrent CNA regions characteristic of each subgroup showed that signalling networks associated with cancer progression and genome stability were likely to be perturbed at the highest level in the PTEN deleted genomic subgroup. Therefore classification of primary prostate cancer according to PTEN deletions, but not the gene fusion, was associated with greatly increased levels of CNA. Collectively, the impact of PTEN loss resulted in a significantly greater frequency and extent of alteration, and heightened genomic instability with concomitant pathway disruptions. / Thesis (Ph.D, Pathology & Molecular Medicine) -- Queen's University, 2014-04-29 14:20:06.02

Les tumeurs locales de la prostate sont associées à une évolution lente et une bonne survie, alors que les stades plus avancés révèlent dans 80% des cas des métastases osseuses incurables. La découverte de gènes de fusion issus de remaniements chromosomiques, tel que TMPRSS2:ERG dans plus de 50% des cas, a ouvert une nouvelle voie dans la compréhension du processus de cancérisation de la prostate. La présence de ce gène de fusion peut être associée à un mauvais pronostic dans de nombreuses études cliniques. Cependant, son rôle précis au cours de la cancérisation et de la progression du cancer de la prostate reste à déterminer. Le gène Erg (Ets related gene) code un facteur de transcription dont l’expression est notamment associée à la mise en place du cartilage, et plus largement du squelette. Ceci suggère un rôle potentiel du gène de fusion impliquant ce facteur, et de ses gènes cibles, dans la formation des métastases osseuses du cancer de la prostate.Pour notre étude, nous avons utilisé des lignées de cellules tumorales prostatiques PC3 et PC3c, exprimant stablement le gène de fusion TMPRSS2:ERG et précédemment établies au laboratoire. Dans un premier temps, en utilisant un modèle d’injections intratibiales chez les souris SCID, nous avons démontré que l’expression ectopique de la fusion améliore la capacité d’induction de lésions ostéocondensantes en inhibant l’ostéolyse dans le modèle PC3 ostéolytique, et en stimulant l’ostéoformation dans le modèle PC3c mixte (ostéolytique et ostéocondensant). Cette expression ectopique de la fusion augmente également l’ostéomimétisme dans les deux modèles cellulaires, c’est-à-dire l’acquisition d’un phénotype semblable aux cellules osseuses leur conférant des avantages de survie et de propagation dans la moelle osseuse. En outre, trois nouveaux gènes cibles de TMPRSS2:ERG ont été mis en évidence : ET-1 (Endothelin-1), stimulant la différenciation ostéoblastique et inhibant la résorption osseuse ostéoclastique, ALPL (Alkaline Phosphatase Liver/Bone/Kidney), marqueur de différenciation des ostéoblastes, et COL1A1 (Collagen Type 1 Alpha 1), composant de la matrice osseuse, témoignant d’un rôle du gène de fusion dans la formation de métastases ostéocondensantes du cancer de la prostate.Par ailleurs, deux autres gènes ont été étudiés, codant soit une protéine impliquée dans la stabilisation de structures particulières appelées invadopodes, soit une protéine impliquée dans le métabolisme des lipides. L’ensemble de ces résultats contribue à mieux comprendre les mécanismes de cancérisation et d’évolution métastatique du cancer de la prostate, en particulier l’influence de l’expression du gène de fusion TMPRSS2:ERG dans les métastases osseuses du cancer de la prostate. / Local prostate cancers are associated with slow progression and good survival, while advanced stages reveal incurable bone metastases in 80% of cases. The discovery of fusion genes resulting from chromosomal rearrangements, such as TMPRSS2:ERG in more than 50% of cases, opened a new way in understanding the process of prostate cancer. The presence of this fusion gene may be associated with poor prognosis in many clinical studies. However, its precise role during cancerization and progression of prostate cancer remains to be determined. The Erg gene (Ets related gene) encodes a transcription factor whose expression is associated in particular with embryonic skeleton development. This suggests a potential role of the fusion gene involving this factor, and its target genes, in the formation of prostate cancer bone metastases.In this study, we used prostate cancer cell lines PC3 and PC3c, stably expressing the TMPRSS2:ERG fusion gene and previously established in the laboratory. First, using a model of intratibial injections in SCID mice, we demonstrated that ectopic expression of the fusion enhances the ability to induce osteoblastic lesions by inhibiting osteolysis in the osteolytic PC3 model, and by stimulating osteoformation in the mixed PC3c model (osteolytic and osteoblastic). This ectopic expression of the fusion also increases osteomimicry in both cell models, meaning the acquisition of a bone-cell-like phenotype which gives them advantages of survival and spread in the bone marrow. In addition, three new TMPRSS2:ERG target genes have been described: ET-1 (Endothelin-1), stimulating osteoblastic differentiation and inhibiting osteoclastic bone resorption, ALPL (Alkaline Phosphatase Liver/Bone/Kidney), a marker of the osteoblasts differentiation, and COL1A1 (Collagen Type 1 Alpha 1), a component of the bone matrix, providing novel insights into the role of the fusion gene in the formation of osteoblastic metastases of prostate cancer.In addition, two other genes have been studied, encoding either a protein involved in the stabilization of particular structures called invadopodia, or a protein involved in lipid metabolism.All these results contribute to decipher the mechanisms of cancerization and metastatic progression of prostate cancer, in particular the influence of the expression of TMPRSS2:ERG fusion gene in prostate cancer bone metastases.

The aim of this thesis was to assess the presence of fusion gene TMPRSS2:ERG and expressions of PCA3, miR23b, miR26 and miR221 in PCa. PSA was measured in peripheral blood and tumor tissue (FFPE samples). The presence of fusion gene TMPRSS2:ERG and expression of PCA3 gene and miRNA in FFPE tumor tissue was analysed by RT real-time PCR. This determination would help to identify patients with high-risk tumors.

No description available.