Les tumeurs papillaires superficielles représentent plus de 75% de tous les cancers primaires de la vessie et on observe une récidive chez une majorité de patients dans les 12 mois suivant la résection de la tumeur, ce qui en fait un cancer provoquant une grande morbidité. L'objectif général des travaux présentés dans cette thèse est de confirmer la possible implication du gène PTC dans le processus de cancérogénèse vésicale. Dans un premier temps, une carcinogénèse chimique chez des souris Pte⁺/⁻ a montré une accélération de l'apparition des évènements prénéoplasiques et des carcinomes chez les souris mutantes comparativement à leurs congénères de type sauvage. De plus, l'apparition de foyers de prolifération stromale a été observée uniquement chez les souris mutantes, et ce avant même l'apparition de carcinomes. Dans un deuxième temps, la caractérisation de ce phénomène stromal a démontré qu'il s'agissait d'une prolifération de myofibroblastes activés et que cela était indépendant de l'altération de la voie Ptc/Shh canonique qui, elle, était observable dans toutes les tumeurs induites chez les souris, peu importe leur génotype. Cette prolifération stromale restreinte aux souris Ptc⁺/⁻ suggère que l'inactivation d'une copie du gène Ptc modifie les interactions épithélium/stroma, menant à une carcinogénèse accélérée. Dans un troisième temps, l'analyse de l'expression des membres de la voie PTC/SHH dans les tumeurs humaines a démontré une altération de la voie PTC/SHH indépendante du statut du locus de Ptc, donnée en parfait accord avec ce qui a été démontré chez la souris. Une baisse de PTC et une perte de GLI-l étaient observables dans la majorité des tumeurs, ce qui ne correspond pas à la logique de la voie, démontrant que le cancer de la vessie est une maladie multigénique impliquant des membres de la voie PTC/SHH, sans qu'il y ait activation de la voie canonique. Et finalement, une analyse d'e?, pression des membres de la voie PTC/SHH dans des lignées vésicales humaines a permis de démontrer une expression aléatoire des ces gènes, suggérant qu'ils ne sont pas essentiels au maintien des cellules in vitro. Des travaux préliminaires pour la mise au point d'un modèle cellulaire du cancer de la vessie ont démontré qu'il était impossible d'obtenir une expression stable des protéines GLI-l et GLI-2 dans des cellules de lignées vésicales par transfection, amenant l'hypothèse que ces protéines soient essentielles au bon maintien de l' intégrité de l'urothélium et que leur perte favorise la cancérogénèse.

La voie de signalisation HH joue un rôle crucial dans le contrôle de la prolifération et la différenciation cellulaires. Le dérèglement de cette voie est responsable de nombreux cancers. J’ai ainsi mis en place les outils moléculaires nécessaires pour identifier des régions importantes dans les interactions protéines-protéines au sein du complexe intracellulaire de la voie qui vont permettre de mieux comprendre les mécanismes de régulation du facteur de transcription CI en fonction de l’état d’activation de la voie. Mes travaux ouvrent la voie à de nombreuses études structurales et fonctionnelles de ces protéines jusqu'ici peu étudiées. / The Hedgehog (Hh) signaling pathway is a highly conserved regulator of growth and differentiation that is essential for both vertebrate and invertebrate development. In Drosophila, the HH pathway is regulated by a high molecular weight intracellular protein complex called the Hedgehog Transducing Complex (HTC), whose composition is controlled by the activation of the pathway. My thesis project is to characterise the HTC complex that regulates the fate of the HH transcription factor, CI. I am using structural studies, biochemistry and enzymology to better understand the protein-protein interactions and function that govern the Hedgehog pathway. My work provide a high resolution view of the HTC and help to understand how those proteins work and interact with each other.

Hedgehog-signalling in malignant gliomas The Hedgehog signalling pathway is important for the development of the central nervous system. On the other hand, aberrant induction is observed in different tumors. Immunofluorescence and real-time qRT-PCR confirmed that in some gliomas, specifically in Glioblastoma multiforme (GBM), Gli1, a transcription factor activated by signalling, is present. In general, the hedgehog pathway is initiated by binding of extracellular ligands to the transmembrane receptor Patched and leads finally to the activation of the transcription factors Gli1, Gli2, Gli3 and Gli4. Whereas Gli1 acts as an activator, Gli2 appears to be an activator but retains some repressor activities and Gli3 and Gli4 are believed to act only as inhibitors. Therefore, the determination of hedgehog activity at the level of transcription requires additional experiments measuring gene activation. For that reason, cells isolated from 13 tumors of patients with glioblastoma (WHO Grade IV) and cells from two different glioma cell lines were transfected with reporter genes. These reporter genes carried the luciferase gene from Gaussia princeps under the control of two promoters (pT109 and pT81) conjugated to Gli binding sites. The activity of the reporter genes was compared to a control plasmid with mutant Gli-binding sites. In addition reporter gene activity was analysed in the absence and presence of the hedgehog signalling inhibitor cyclopamine and the effect of cyclopamine on cellular metabolism was studied. The analysis revealed that the two cell lines and cells from 6 glioblastomas exhibited enhanced reporter gene activity compared to the activity mutant control. This points towards an enhanced expression of Gli1. In three cultures a repression was detected suggesting that Gli3 may be active in these cells. Four cultures did neither show activation nor repression. This could provide evidence that Gli1 and Gli3 effects cancel each other out or that there is no effect at all. Enhanced luciferase activity in cells from the line T98G and in cells from four primary cultures was not influenced by the hedgehog inhibitor cyclopamine, whereas one cell line significantly responded to its presence with a decreased activity. Interestingly, ATP level was suppressed by cyclopamine in cells from the line T98G and also in cells from one primary culture that responded to the inhibitor. This may point towards an effect of cyclopamine independent of smo. Since cyclopamine is a potential new substance for the treatment of tumors, the observed effect of this inhibitor even in cells without an indication of hedgehog signalling activity should be investigated in further experiments in more detail. / Der Hedgehog (Hh) -Signalweg spielt während der Embryonalentwicklung eine wichtige Rolle, so auch bei der Entstehung des zentralen Nervensystems (Varjosalo & Taipale 2008). Andererseits führt seine unregulierte Aktivität zur Ausbildung verschiedenster Tumore (Bailey et al. 2009; Fiaschi et al. 2009; Shaw et al. 2009; Velcheti & Govindan 2007). Vorausgegangene Studien wiesen durch Immunfluoreszenz und real-time qRT-PCR nach, dass auch in Gliomen, speziell in Glioblastoma multiforme, dem agressivsten Hirntumor des Menschen, Effektoren des Signalweges (Gli1) überexprimiert werden (Wang et al. 2010). Die Aktivierung des Signalweges geschieht über Bindung des Hh-Liganden an den Rezeptor Ptch und endet mit der Aktiverung der Transkriptionsfaktoren der Gli Familie (Kinzler & Vogelstein 1990; Stone et al. 1996). Die aktuell bekannten Vertreter dieser Familie sind der Aktivator der Transkription Gli1, Gli2, der als Aktivator und Repressor agieren kann sowie Gli3 und Gli4, die die Transkription inhibieren (Marine et al. 1997; Ruppert et al. 1988). Ziel dieser Arbeit war es, herauszufinden, inwieweit die Transkriptionsfaktoren der Gli-Familie in Zellen von Glioblastoma multiforme aktiv sind. Dafür wurden Zellen aus Tumormaterial isoliert und daraus Primärkulturen hergestellt. In diese 13 Primärkulturen, wie auch in zwei Gliom-Zelllinien, wurden mittels transienter Transfektion Reporterplasmide eingebracht. Diese enthielten ein Gen der Gaussia-Luciferase, das unter der Kontrolle zweier verschiedener Promotoren (pT109 und pT81) mit Bindungsmotiven für die Transkriptionsfaktoren der Gli-Familie stand. Weiterhin wurde der Einfluss des Inhibitors des Hh-Signalweges Cyclopamin auf die Gli-Aktivität und die Metabolische Aktivität der Zellen untersucht. Die Beobachtungen ergaben, dass die zwei Zelllinien und sechs der primären Kulturen eine erhöhte Luciferaseaktivität und damit gesteigerte Aktivität von Gli1 zeigten. Weiterhin wiesen vier Kulturen eine verminderte Luciferaseaktivität auf. Dies ließ darauf schließen, dass in diesen Zellen Gli3 aktiv war. In den restlichen vier Kulturen zeigte sich keine Veränderung der Luciferaseaktiviät, was für einen Aufhebungseffekt von Gli1 und Gli3 oder gar keinen Effekt spricht. Weiterhin konnte gezeigt werden, dass die Luciferaseaktivität und damit die Aktivität von Gli1 in Zellen der Zelllinie T98G und von vier Primärkulturen nicht durch Cyclopamin beeinflusst wird. Lediglich eine Probe der Primärkulturen reagierte mit einer Abnahme der Luciferaseaktivität. Außerdem konnte Cyclopamin die ATP-Produktion sowohl in Zellen von T98G als auch in Zellen der Zelllinie, deren Gli-Aktivität durch Cyclopamin vermindert wurde, senken. Dies sprach für eine Smo unabhängige Wirkung des Cyclopamins. Da Cyclopamin ein potenzielles Pharmakon für die Antitumortherapie ist, bedarf dieser Umstand näherer Untersuchungen.

Hedgehog (Hh) shape up development by playing important role in signaling, and thereby controlling growth and pattern formation. It is for this reason that their spatial distribution is tightly regulated. The 19kDa active form of Hh is modified with a palmitate at its N-terminal and with cholesterol at its C-terminal. This dually lipid modified form of Hh act as a morphogen, and is also referred to as HhNp (Mann and Beachy, 2004). In most cases, they are released from producing cells and spread into adjacent non-expressing cells within the tissue, where it activates target gene expression in a concentration-dependent manner. In Drosophila, Lipophorin (Lpp) particles carry these lipid-modified forms of Hh and play a role in long range signaling in the developing wing disc. Further, these particles circulate throughout the larvae in the hemolymph to distribute nutrients mostly in the form of lipids to different tissues of the animal. Thus, Lpp plays important role in metabolism and development. Hh as a morphogen plays a very important role in development and patterning of embryo and imaginal discs in Drosophila. We wanted to understand the role of Hh in overall development of Drosophila. In my thesis work, I discovered a new form of Hh that is systemically circulating in the 3rd instar larva of Drosophila. I show that imaginal tissues do not produce this form of circulating Hh. Our experiments strongly suggest that systemic Hh can travel from one tissue to another, a feature that was previously unknown. I also show that it could rescue the growth of the imaginal disc, implying its ability to influence cell proliferation. Since the concentration of systemic Hh is low it fails to up regulate the target genes. I characterized fat body as a target of systemically circulating Hh. I clearly demonstrate that fat body transcribes most of the components of Hh signaling pathway except Hh. Further, Hh accumulates in the fat body during late 3rd instar larvae. That makes the fat body an ideal target of systemic Hh. This could shed light in understanding the role of Hh in overall development of Drosophila melanogaster that includes tissue-based interaction.

Submitted by Ana Maria Fiscina Sampaio (fiscina@bahia.fiocruz.br) on 2015-03-26T19:18:11Z No. of bitstreams: 1 Caroline Brandi_S Sales Identificação....pdf: 2182912 bytes, checksum: 259ec8612d135428b26583b6a9303dcc (MD5) / Approved for entry into archive by Ana Maria Fiscina Sampaio (fiscina@bahia.fiocruz.br) on 2015-03-26T19:18:22Z (GMT) No. of bitstreams: 1 Caroline Brandi_S Sales Identificação....pdf: 2182912 bytes, checksum: 259ec8612d135428b26583b6a9303dcc (MD5) / Made available in DSpace on 2015-03-26T19:18:22Z (GMT). No. of bitstreams: 1 Caroline Brandi_S Sales Identificação....pdf: 2182912 bytes, checksum: 259ec8612d135428b26583b6a9303dcc (MD5) Previous issue date: 2015 / Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / INTRODUÇÃO: A Via Hedgehog (HH) está ativada em algumas neoplasias humanas, incluindo o Carcinoma Escamocelular de Boca (CEB), o qual corresponde a mais de 95% dos casos diagnosticados na cavidade bucal. Os glipicans (GPC) participam como reguladores desta cascata, atenuando (GPC1 e GPC3) ou regulando positivamente (GPC5) a via HH. OBJETIVO: O objetivo deste trabalho foi avaliar o perfil de expressão dos genes GPC1, 3 e 5, associando-os com genes da via HH (SHH, PTCH1 e SMO) e VEGFA, bem como caracterizar a imunoexpressão das proteínas GPC, em CEB. MATERIAL E MÉTODOS: Trinta e um casos de CEB foram submetidas a reações de qPCR para os genes SHH, PTCH1, SMO, VEGFA, GPC1, 3 e 5. O RNA total foi extraído utilizando uma coluna composta por membrana de silica (Rneasy Mini Kit). O DNA complementar foi obtido com auxílio da enzima Superscript Vilo™. As reações de qPCR foram conduzidas no aparelho ViiA™ 7 Real-Time PCR System utilizando o sistema Taqman, sendo a quantificação relativa avaliada pelo método comparativo de Cq (ΔΔCQ). Vinte e seis CEBs, 9 casos de margens tumorais (MAT) e 4 casos de mucosa bucal não neoplásica (MNN) foram submetidos à reação imuno-histoquímica para as proteínas GPC1, GPC3, GPC5, CD105 e MCM3 utilizando o sistema polimérico AdvanceTM ou LSABTM. As análises das proteínas GPC1, 3 e 5 foram realizadas de acordo com os parâmetros semi-quantitativos descritos por Gurgel et al. (2008). O número de células MCM3 positivas e de vasos/mm² (microdensidade vascular- MDV) foram avaliados em 5 campos, sendo a mediana de e intervalo de confiança utilizados para agrupar os CEBs em alto e baixo perfil proliferativo (AP e BP) e alta e baixa MDV, respectivamente. A análise estatística foi realizada utilizando GraphPad Prism versão 6.03. RESULTADOS: Transcritos do gene GPC1 (26; 83,87%); GPC3 (n=22; 70,97%) e GPC5 (n=15; 48,38%) foram observados em CEBs. SHH RNAm foi detectado em 5 CEBs (16,13%). A maioria dos CEBS apresentou expressão gênica de PTCH1 (n=25; 80.6%), SMO (n=26; 83,87%) e VEGFA (n=28; 90,32%). Correlação positiva forte e estatisticamente significante foi demonstrada para GPC5 e PTCH1 (rs=0,60; p=0,02) e entre PTCH1 e VEGFA (rs=0,69; p=0,0003). Imunomarcação citoplasmática e membranar de GPC1 foi observada principalmente em epitélio de MNN (n=4;100%) e MAT (n=9; 100%), enquanto que uma perda de imunomarcação desta proteína foi detectada no parênquima do CEB. A imunoexpressão da proteína GPC3 estava ausente em MNN (n= 4; 100%) e MAT (n=9; 100%). O GPC3 ocorreu na membrana e citoplasma de células do parênquima, observadas principalmente na periferia das ilhas tumorais, predominando o escore 3+ (n=5; 19.23%) entre os CEBs positivos (n=23; 88,46%). Ausência de imunomarcação de GPC5 foi observada em MNN (n=4; 0%) e apenas 2 espécimes de MAT (n=2; 22,22%) apresentaram baixa imunoexpressão, escore 1+. GPC5 citoplasmático em células tumorais positivas predominou o escore 1+ (n=5; 38.46%). Ao mesmo tempo, GPC5 foi detectado em estroma de 13 (50%) CEBs, especialmente em células endoteliais e semelhantes a fibroblastos. A expressão dos genes avaliados foi similar em tumores com AP e BP, assim como foi independente da MDV. CONCLUSÕES: A correlação entre os transcritos GPC5 e PTCH1, bem como a superexpressão das proteínas GPC5 e GPC3 e perda de imunopositividade de GPC1 são consistentes com a participação destas proteoglicanas como reguladoras da via HH em CEB. O perfil de expressão do gene e proteína GPC1 sugere que este glipican pode participa da biologia tumoral como uma proteína supressora tumoral, enquanto GPC3 e GPC5 participariam oncoproteínas. A presença de GPC5 em estroma tumoral (células endoteliais e fibroblastos) pode estar associada a regulação da via HH neste compartimento do microambiente tumoral. / INTRODUCTION: The Hedgehog pathway is activated in some human neoplasms, including Oral Squamous Cell Carcinoma (OSCC), which account for more than 95% of all oral cancers diagnosed. Glypicans are involved in the regulation of HH pathway through GPC3 e GPC1 downregulation or/and GPC5 upregulation. AIM: The aim of this study was to evaluate the expression profile of GPC1, 3 and 5 genes, correlating to HH and VEGFA gene, even as to characterize the immunoexpression of these proteins at OSCC. MATERIAL AND METHODS: A total of 31 cases of OSCC were assessed by qPCR for the SHH, PTCH1, SMO, VEGFA, GPC1, GPC3 and GPC5 genes. The total RNA were extracted using silica membrane column (Rneasy Mini Kit). Complementary DNA was obtained using of Superscript ™ Vilo enzyme. The qPCR reactions were performed in VIIA™ 7 Real-Time PCR System using the Taqman enzime, and relative quantification (RQ) was evaluated by the comparative method of Cq (ΔΔCQ). Immunohistochemical reactions for GPC1, GPC3, GPC5, MCM3 and CD105 proteins was performed on twenty-six OSCC, 9 cases of tumor margins (TM) and 4 cases of non-neoplastic oral mucosa (NNM) using AdvanceTM or LSABTM system. The analysis of GPC1, 3 and 5 proteins were conducted according to the semi-quantitative parameters described by Gurgel et al. (2008). The number of MCM3 positive cells and vessels//mm² (microvessel density -MVD) were evaluated in 5-matching areas, and the median and confidence interval being used to group the OSCC in high and low proliferative profile (HP and LP) and high and low MDV, respectively. Statistical analysis were carried out with GraphPad Prism v.6.03. RESULTS: Transcripts of GPC1 (26; 83.87%), GPC3 (n=22; 70.97%) and GPC5 (n=15; 48.38%) genes were observed in OSCC. SHH mRNA was detected in 5 OSCC (16:13%), PTCH1 gene in 25 CEBs (80.6%), SMO in 26 (83.87%) and VEGFA in 28 (90.32%). Strong and statistically significant positive correlation was demonstrated for GPC5 and PTCH1 genes (rs=0.60; p= 0.02) and PTCH1 and VEGFA transcripts (rs = 0.69; p = 0.0003). Cytoplasmic and membrane immunostaining of GPC1 was mainly observed in epithelial MNN (n = 5; 100%) and MAT (n=9; 100%), while a reduction of this protein was detected in parenchymal cells. GPC3 protein were absent in MNN (n = 4; 0%) and MAT (n=9; 0%). The GPC3 occurred in the membrane and cytoplasm of parenchymal cells, mainly observed in the periphery of the tumor islands and the 3+ score was predominat (n=3; 11:56%) in positive OSCC. GPC5 positive tumor cells occurred in the cytoplasm, scored 1+ (n = 5; 38.46%). In addition, GPC5 was detected in the stroma of 13 (50%) OSCC, especially in endothelial and fibroblast cells. The gene expression was similar in tumors with HP and LP, and was independent of MDV. CONCLUSIONS: The correlation between the GPC5 and PTCH1 transcripts, as well the overexpression of GPC5 and GPC3 protein and the loss of GPC1 positive cells are consistent with the participation of these proteoglycans as regulators of HH pathway in OSCC. The gene and protein expression profile of GPC3 indicate that this proteins participates in tumor biology as a tumor suppressor protein, while GPC5 and GPC3 function as oncoproteins. The presence of GPC5 in tumor stroma (endothelial cells and fibroblasts) could be associated with the regulation of the HH pathway in this compartment of the tumor microenvironment.

No description available.

La voie de signalisation Hedgehog (HH) est impliquée dans le développement du tractus gastro-intestinal chez de nombreuses espèces. Elle est importante chez ladulte en participant au maintien de lhoméostasie de lépithélium intestinal. Récemment la suractivation de la voie HH a été mise en évidence dans de nombreux cancers dont ceux du tractus gastro-intestinal tels que les cancers de lestomac et du pancréas. Au cours de ce travail, nous nous sommes intéressés à la voie de signalisation HH dans les cancers du côlon. Lexpression des membres principaux de la voie HH a dabord été caractérisée dans sept lignées cellulaires de cancers du côlon (Colo205, Colo320, HCT116, HT29, WiDr, SW480, Caco-2). Labsence dexpression de certains membres clés de la voie indique que celle-ci nest pas activée, de façon autocrine, dans les lignées cellulaires. Cette observation est également appuyée par des expériences réalisées en traitant les cellules à la cyclopamine, inhibiteur de la voie HH. Enfin GLI1, facteur de transcription mimant une activation de la voie HH, a été surexprimé stablement dans les cellules HCT116. Nous avons pu montrer que lactivation de la voie HH induisait lexpression du gène BMP4, gène cible de la voie HH lors de lembryogenèse intestinale, ainsi que lactivité phosphatase alcaline, marqueur de différenciation du côlon. Ces résultats suggèrent que la voie de signalisation HH nest pas activée de façon autocrine dans les cancers du côlon mais semble plutôt associée à la différenciation des cellules du côlon.

During embryonic development, the Hedgehog (Hh) signaling pathway plays an important role in the growth and patterning of numerous tissues and organs. In the developing retina, Hh signaling regulates the proliferation and differentiation of retinal progenitor cells (RPC) through mechanisms that are not completely understood. The principal downstream mediators of the Hh pathway are the Gli transcription factors (Gli1-3), which regulate the expression of target genes responsible for the effects of the Hh pathway on RPC. The network of genes targeted by this pathway in neural progenitor cells however, remains unknown. The objective of this thesis was to identify and characterize novel targets of Hh/Gli during retinal development. Using a computation approach, 390 genes were identified as having at least one conserved Gli binding motif within the vicinity of the coding sequence between humans and mice. During validation, I demonstrate that 30 of 46 selected targets were modulated in response to Hh pathway activation in either E14.5 and/or P0.5 retinal explants and that the induction of 25 of these were significantly different between the two developmental stages. Included in this list of Hh-modulated genes were Sox8 and Ndp, two highly inducible genes that are direct targets of Gli2. Functionally, I was unable to determine a role for Sox8 during retinal development which could reflect compensation by the closely related Sox9 and Sox10 genes. Ndp on the other hand was found to be sufficient and required for Hh mediated induction in progenitor cell proliferation and cell fate determination. Therefore, in this thesis Hh target genes have been identified which could provide some insight into the mechanisms that are responsible for the cellular outcome of a response to the pathway.

Hedgehog signaling is essential during embryogenesis and in the maintenance of adult

The Hedgehog receptor Patched (Ptch) is a well-studied tumor suppressor. Mutations in Ptch have been linked to mis-regulation of stem cell proliferation and tumorigenesis in numerous contexts. To study the role of Ptch function during retinal development and homeostasis, I analyzed retinal growth and patterning in the embryonic and post-embryonic (juvenile) zebrafish ptc2 mutant line. ptc2 deficiency in zebrafish results in an expansion of the stem/progenitor population of the ciliary marginal zone (CMZ), as well as ectopic proliferation within the neural retina at juvenile stages. ptc2-/- mutants also possess vitreo-retinal abnormalities that appear to be embryonic in origin. These phenotypes are similar to the ocular abnormalities previously reported in human patients suffering from Basal Cell Naevus Syndrome (BCNS), a disorder that has been linked to mutations in the human PTCH gene (the orthologue of the zebrafish ptc2), and point to the utility of the ptc2 mutant line as a model for the study of BCNS-related ocular pathologies. In addition, peripheral retinal dysplasias that include ectopic neuronal clusters and disrupted lamination were observed at later, juvenile stages. It has been previously proposed that retinal over-proliferation might contribute to retinal dysplasias observed in the post-natal Ptch1 /- mice (an established model for BCNS); however, this potential relationship has yet to be established experimentally. I demonstrated that a population of ectopically proliferating cells give rise to the ectopic neuronal clusters in the INL of ptc2-/- mutants and established ectopic proliferation as the likely cellular underpinning of retinal dysplasia in juvenile ptc2-/- mutants. / text