La compréhension des mécanismes impliqués dans la formation des métastases est l’un des défis majeurs de la recherche sur le cancer. En effet, la formation de métastases est la cause principale de mortalité chez les patients atteints du cancer. L'influence du microenvironnement tumoral fait partie intégrante de la recherche et plusieurs études démontrent qu’il joue un rôle primordial dans l’invasion des cellules tumorales. L’une des caractéristiques du microenvironnement tumoral est l’hypoxie. Les cellules cancéreuses ont développé différentes stratégies afin de survivre dans ce microenvironnement. Des études récentes rapportent que des mécanismes posttranscriptionnels sont induits par l’hypoxie tels que le routage intracellulaire de molécules d'adhésion, de protéases et l’activation de facteurs de croissance, et qu’ils influencent le phénotype métastatique des cellules cancéreuses. L’étape importante dans l’initiation de la formation des métastases est la dégradation de la membrane basale de la tumeur et de la matrice extracellulaire. Les cellules cancéreuses ont développé des stratégies afin de faciliter leur migration dont l’une est la formation d'invadopodes. Malgré plusieurs études sur la biogenèse et les fonctions de ces structures, peu de travaux ont été accomplis concernant l’influence du microenvironnement tumoral hypoxique sur la formation et les fonctions des invadopodes. Les travaux présentés dans cette thèse portent sur l’étude des mécanismes induits par l’hypoxie dans l’invasion des cellules cancéreuses. Dans le premier chapitre de la section résultats, nous démontrons que l’hypoxie induit une relocalisation stratégique de la furine, une convertase de pro-protéines, dans une boucle de recyclage en périphérie cellulaire. Nous démontrons que la redistribution de la furine favorise l’invasion cellulaire en condition hypoxique. Dans le deuxième chapitre, nous avons étudié l'impact de la relocalisation de la furine en hypoxie sur la maturation de substrats tumorigéniques. Nos résultats indiquent que l’hypoxie favorise la maturation du TGFß par la furine dans des vésicules acides. Nous démontrons que la présence d’une histidine, sensible au pH, située au site de clivage du pro-TGFß par la furine influence la capacité de cette dernière à cliver la pro-protéine. Enfin, dans le dernier chapitre, nous démontrons que l’induction hypoxique de la formation des invadopodes est principalement causée par la signalisation dépendante de Smad3 du TGFß. Nous identifions la HDAC6 comme étant un régulateur de la signalisation du TGFß en hypoxie. La HDAC6 permettrait la libération de Smad3 du réseau de tubuline, et suite à la liaison du TGFß sécrété à son récepteur, permettrait la phosphorylation et la translocation nucléaire de Smad3 afin d'induire ses gènes cibles. L'ensemble de ces travaux a permis d'identifier des molécules clés impliquées dans la formation des invadopodes en condition hypoxique. Nos travaux ont contribué de manière substantielle à nos connaissances des mécanismes impliqués dans l’invasion cellulaire dans le microenvironnement hypoxique. Nos résultats permettront en outre l’identification de cibles thérapeutiques potentielles qui pourraient servir à inhiber l’invasion cellulaire et la formation de métastases.

No momento em que há a agressão tecidual e a defesa inata é deflagrada, mediadores químicos são liberados no local afetado. Esses mediadores podem ser de origem celular tais como CGRP, VEGF e TGFß. Os objetivos desta pesquisa foram avaliar a expressão e distribuição de CGRP, TGFß e VEGF na gengiva do primeiro molar inferior esquerdo de rato no 7 e 14 dias após a indução por ligadura; a expressão e distribuição de CGRP, TGFß e VEGF na gengiva do dente contralateral correspondente sem ligadura, no 7 e 14 dias, e se a indução da periodontite por ligadura no dente experimental provoca uma inflamação na gengiva do dente contralateral correspondente no 7 e 14 dias após a ligadura. Para o desenvolvimento deste trabalho foram selecionados 15 ratos Rattus Novergicus, Albinus, Wistar. O grupo experimental de 12 ratos foi dividido em 2 subgrupos compostos por 6 ratos cada um deles distribuídos da seguinte maneira: os do subgrupo A1 permaneceram com a ligadura no primeiro molar inferior esquerdo por 7 dias e foram sacrificados; os do subgrupo A-2 -permaneceram com a ligadura no primeiro molar inferior esquerdo por 14 dias e foram sacrificados. Outros três animais constituíram o grupo controle. Após o sacrifício dos 12 animais dos grupos experimentais e controle suas mandíbulas foram colocadas em ácido etilenodiaminotetracético (EDTA) neutro para sofrerem descalcificação. Então foram processadas para inclusão em parafina e os cortes histológicos foram corados pela hematoxilina-eosina e submetidos à técnica imunohistoquímica para imunomarcação de CGRP, VEGF e TGFß. Aos 7 dias de ligadura observou-se na lâmina própria gengival, epitélio juncional e epitélio oral, expressiva marcação para CGRP. A expressão de VEGF foi intensa na lamina própria e com pouca ou nenhuma marcação no epitélio oral e juncional. O TGFß apresentou pouca marcação na lâmina própria ou nenhuma marcação no epitélio oral e juncional. Aos 14 dias de ligadura houve expressiva marcação de CGRP na lâmina própria, epitélios oral e juncional. O VEGF e o TGFß apresentaram muita marcação na lâmina própria e pouca ou nenhuma marcação no epitélio oral e juncional. Na gengiva dos dentes contralaterais nos 7 e 14 dias houve pouca marcação do CGRP do TGFß na lâmina própria e muita marcação do VEGF. Na gengiva dos dentes controle observou-se muita marcação do CGRP no epitélio juncional e oral e na lâmina própria. O TGFß e o VEGF se expressaram muito pouco ou não se expressaram. Devido à marcação expressiva do VEGF na lâmina própria dos dentes contralaterais, permanece inconclusiva a adequação do uso dos dentes contralaterais nos estudos experimentais das doenças periodontais, embora a expressão de TGFß e CGRP tenham sido menores nestes dentes. A maior marcação do CGRP, VEGF e TGFß nos animais com 14 dias de ligadura do que aos 7 dias demonstra a progressão do processo inflamatório crônico, não se observando processo de reparação cicatricial. / At the time of the tissue aggression the innate defense is triggered and the chemical mediators are released in the affected site. These mediators may have cell origin as the CGRP, VEGF and TGFß. The aim of this research were to evaluate the expression and distribution of the CGRP, VEGF and TGFß in the gingiva of the lower left first molar of rats in the seven and fourteen days after the ligature for inflammation induction; to analyse the expression and distribution of the CGRP, VEGF and TGFß in the gingiva of the correspondent counter lateral tooth without ligature in the seven and fourteen days and if the induction of periodontitis causes gingival inflammation of the counter lateral tooth after seven and fourteen days after ligature. For the development of this work were selected fifteen Rattus Novergicus, Albinus,Wistar. The experimental group of 12 rats was divided into 2 groups consisting of 6 rats each distributed of the following manner: the subgroup A1 remained with ligature in the first molar and left for 7 days before the sacrificed and the subgroup A-2 remained with the ligature for 14 days before the sacrificed. Another 3 animals constituted the control group. After the sacrificed of the 12 experimental and 3 control animals were immersedin neutral ethylenidiaminetetracetic (EDTA) for the decalcification. Then were processed for paraffin embedding. The sections were stained with hematoxylin-eosin and submitted to immunohistochemical techniques to imunostaining for CGRP, VEGF and TGFß. At 7 days of ligature was observed in the gingival lamina propria, junctional epithelium and oral epithelium, strong staining for CGRP. The intensive expression of VEGF occur in the lamina propria and scarce or no staining in the oral and junctional epithelium. The TGFß shows scarce staining in the lamina propria and no staining in the oral and junctional epithelium. At the fourteen days of ligature we observed strong staining of CGRP in the lamina propria and oral and junctional epithelium. The VEGF and TGFß show strong staining in the lamina propria and scarce or no staining in the junctional and oral epithelium. At the gingival of the counterlateral teeth in the 7 and 14 days there was scarce staining for CGRP and TGFß in the lamina propria and strong staining to VEGF. In the gingival of couterlateral teeth there was strong staining to CGRP in the junctional and oral epithelium and lamina propria. The TGFß and VEGF show scarce or none staining. Because the strong staining of VEGF in the lamina propria of the counterlateral teeth remain inconclusive the adequacy of the use of the counterlateral teeth in the experimental studies of the periodontal diseases, though the expression of the TGFß and CGRP has been smaller in this teeth. The bigger staining of CGRP, VEGF and TGFß in the animals with 14 days of ligature than those 7 days shows the evolution of the chronic inflammation process. We dont observe the process of tissue healing.

No momento em que há a agressão tecidual e a defesa inata é deflagrada, mediadores químicos são liberados no local afetado. Esses mediadores podem ser de origem celular tais como CGRP, VEGF e TGFß. Os objetivos desta pesquisa foram avaliar a expressão e distribuição de CGRP, TGFß e VEGF na gengiva do primeiro molar inferior esquerdo de rato no 7 e 14 dias após a indução por ligadura; a expressão e distribuição de CGRP, TGFß e VEGF na gengiva do dente contralateral correspondente sem ligadura, no 7 e 14 dias, e se a indução da periodontite por ligadura no dente experimental provoca uma inflamação na gengiva do dente contralateral correspondente no 7 e 14 dias após a ligadura. Para o desenvolvimento deste trabalho foram selecionados 15 ratos Rattus Novergicus, Albinus, Wistar. O grupo experimental de 12 ratos foi dividido em 2 subgrupos compostos por 6 ratos cada um deles distribuídos da seguinte maneira: os do subgrupo A1 permaneceram com a ligadura no primeiro molar inferior esquerdo por 7 dias e foram sacrificados; os do subgrupo A-2 -permaneceram com a ligadura no primeiro molar inferior esquerdo por 14 dias e foram sacrificados. Outros três animais constituíram o grupo controle. Após o sacrifício dos 12 animais dos grupos experimentais e controle suas mandíbulas foram colocadas em ácido etilenodiaminotetracético (EDTA) neutro para sofrerem descalcificação. Então foram processadas para inclusão em parafina e os cortes histológicos foram corados pela hematoxilina-eosina e submetidos à técnica imunohistoquímica para imunomarcação de CGRP, VEGF e TGFß. Aos 7 dias de ligadura observou-se na lâmina própria gengival, epitélio juncional e epitélio oral, expressiva marcação para CGRP. A expressão de VEGF foi intensa na lamina própria e com pouca ou nenhuma marcação no epitélio oral e juncional. O TGFß apresentou pouca marcação na lâmina própria ou nenhuma marcação no epitélio oral e juncional. Aos 14 dias de ligadura houve expressiva marcação de CGRP na lâmina própria, epitélios oral e juncional. O VEGF e o TGFß apresentaram muita marcação na lâmina própria e pouca ou nenhuma marcação no epitélio oral e juncional. Na gengiva dos dentes contralaterais nos 7 e 14 dias houve pouca marcação do CGRP do TGFß na lâmina própria e muita marcação do VEGF. Na gengiva dos dentes controle observou-se muita marcação do CGRP no epitélio juncional e oral e na lâmina própria. O TGFß e o VEGF se expressaram muito pouco ou não se expressaram. Devido à marcação expressiva do VEGF na lâmina própria dos dentes contralaterais, permanece inconclusiva a adequação do uso dos dentes contralaterais nos estudos experimentais das doenças periodontais, embora a expressão de TGFß e CGRP tenham sido menores nestes dentes. A maior marcação do CGRP, VEGF e TGFß nos animais com 14 dias de ligadura do que aos 7 dias demonstra a progressão do processo inflamatório crônico, não se observando processo de reparação cicatricial. / At the time of the tissue aggression the innate defense is triggered and the chemical mediators are released in the affected site. These mediators may have cell origin as the CGRP, VEGF and TGFß. The aim of this research were to evaluate the expression and distribution of the CGRP, VEGF and TGFß in the gingiva of the lower left first molar of rats in the seven and fourteen days after the ligature for inflammation induction; to analyse the expression and distribution of the CGRP, VEGF and TGFß in the gingiva of the correspondent counter lateral tooth without ligature in the seven and fourteen days and if the induction of periodontitis causes gingival inflammation of the counter lateral tooth after seven and fourteen days after ligature. For the development of this work were selected fifteen Rattus Novergicus, Albinus,Wistar. The experimental group of 12 rats was divided into 2 groups consisting of 6 rats each distributed of the following manner: the subgroup A1 remained with ligature in the first molar and left for 7 days before the sacrificed and the subgroup A-2 remained with the ligature for 14 days before the sacrificed. Another 3 animals constituted the control group. After the sacrificed of the 12 experimental and 3 control animals were immersedin neutral ethylenidiaminetetracetic (EDTA) for the decalcification. Then were processed for paraffin embedding. The sections were stained with hematoxylin-eosin and submitted to immunohistochemical techniques to imunostaining for CGRP, VEGF and TGFß. At 7 days of ligature was observed in the gingival lamina propria, junctional epithelium and oral epithelium, strong staining for CGRP. The intensive expression of VEGF occur in the lamina propria and scarce or no staining in the oral and junctional epithelium. The TGFß shows scarce staining in the lamina propria and no staining in the oral and junctional epithelium. At the fourteen days of ligature we observed strong staining of CGRP in the lamina propria and oral and junctional epithelium. The VEGF and TGFß show strong staining in the lamina propria and scarce or no staining in the junctional and oral epithelium. At the gingival of the counterlateral teeth in the 7 and 14 days there was scarce staining for CGRP and TGFß in the lamina propria and strong staining to VEGF. In the gingival of couterlateral teeth there was strong staining to CGRP in the junctional and oral epithelium and lamina propria. The TGFß and VEGF show scarce or none staining. Because the strong staining of VEGF in the lamina propria of the counterlateral teeth remain inconclusive the adequacy of the use of the counterlateral teeth in the experimental studies of the periodontal diseases, though the expression of the TGFß and CGRP has been smaller in this teeth. The bigger staining of CGRP, VEGF and TGFß in the animals with 14 days of ligature than those 7 days shows the evolution of the chronic inflammation process. We dont observe the process of tissue healing.

L’adénocarcinome canalaire pancréatique (ADKP) est l’une des tumeurs solides avec le pronostic le plus sombre. Le stroma de ces tumeurs, très abondant, est composé de matrice extra cellulaire ainsi que de cellules stromales (incluant des fibroblastes activés associés au cancer ou des cellules immunitaires). Les fibres nerveuses infiltrant ce stroma tumoral sont considérées comme une caractéristique des ADKP, impliquées dans le phénomène de remodelage nerveux, qui participent aux douleurs neuropathiques, à la dissémination des cellules tumorales, ainsi qu’à la rechute de la maladie après chirurgie. Le remodelage nerveux associé aux ADKP est régulé par un réseau fonctionnel, impliquant des interactions physiques et moléculaires entre cellules tumorales, cellules nerveuses dont les cellules de Schwann et les autres cellules stromales. Dans cette étude, nous avons démontré que les cellules de Schwann (cellules gliales, soutient des neurones périphériques) stimulent l’agressivité (migration, invasion, tumorigénicité) des cellules pancréatiques tumorales de façon dépendante du TGFβ (Transforming Growth Factor beta). En effet, nous révélons que le milieu conditionné des cellules de Schwann est enrichi en nombreuses molécules de signalisation, incluant de grandes quantités de TGFβ capable d’activer sa voie de signalisation dépendante des protéines SMAD, au sein des cellules cancéreuses. Des analyses de spectrométrie de masse des sécrétomes des cellules de Schwann et des cellules tumorales pancréatiques, cultivées seules ou ensemble, soulignent le rôle central du TGFβ dans les interactions neuro-épithéliales, comme illustré par la signature protéomique relative aux mécanismes d’adhésion et de motilité cellulaires. Ainsi, ces résultats démontrent que les cellules de Schwann sont une source de TGFβ dans les ADKP, et jouent un rôle crucial dans l’acquisition de propriétés agressives par les cellules tumorales / Pancreatic ductal adenocarcinoma (PDAC) is one of the solid tumors with the poorest prognosis. The stroma of this tumor is abundant and composed of extracellular matrix and stromal cells (including cancer-associated fibroblasts and immune cells). Nerve fibers invading this stroma represent a hallmark of PDAC, involved in neural remodeling, which participates in neuropathic pain, cancer cells dissemination and tumor relapse after surgery. Pancreatic cancer-associated neural remodeling is regulated through functional interplays mediated by physical and molecular interactions between cancer cells, nerve cells and surrounding Schwann cells, and other stromal cells. In the present study, we show that Schwann cells (glial cells supporting peripheral neurons) can enhance aggressiveness (migration, invasion, tumorigenicity) of pancreatic cancer cells in a transforming growth factor beta (TGFβ)-dependent manner. Indeed, we reveal that conditioned medium from Schwann cells contains various signaling cues, including high amounts of TGFβ able to activate the TGFβ-SMAD signaling pathway in cancer cells. Secretome analyses by mass spectrometry of Schwann cells and pancreatic cancer cells cultured alone or in combination highlighted the central role of TGFβ in neuro-epithelial interactions, as illustrated by proteomic signatures related to cell adhesion and motility. Altogether, these results demonstrate that Schwann cells are a meaningful source of TGFβ in PDAC, which plays a crucial role in the acquisition of aggressive properties by pancreatic cancer cells

No description available.

Plusieurs études animales et cellulaires suggèrent un rôle protecteur pour l’oestrogène dans les maladies inflammatoires intestinales. L'oestrogène agit principalement via l’interaction avec ses récepteurs ER? et ER?. Puisqu'ER? est l’isoforme prédominant dans l'épithélium colique, celui-ci devrait y être le médiateur des effets de l'oestrogène. Dans cette étude, nous avons tout d'abord démontré que la perte d’ER? chez la souris augmente les signes d'inflammation dans un modèle murin de colite. Également, l’activation sélective d’ER? avec le diarylpropionitrile (DPN) réduit les signes de colite dans le même modèle. L'expression de la cytokine inflammatoire TNF? était réduite alors que celle des cytokines anti-inflammatoires TGF?1, TGF?2 et TGF?3 était augmentée dans le côlon des souris traitées au DPN. Des études réalisées dans les cellules cancéreuses du côlon LS1034 ont démontré que le DPN augmente la signalisation du TGF? et que cette régulation contribue en partie à l’effet anti-inflammatoire du DPN dans ces mêmes cellules. Bref, ces résultats suggèrent que l'activation pharmacologique d’ER? réduit l’inflammation intestinale en partie via la régulation de la voie du TGF? dans les cellules épithéliales intestinales. Le récepteur nucléaire ERR?, un régulateur clé du métabolisme énergétique, possède une forte homologie avec les ERs bien que celui-ci ne peut lier l’oestrogène. Son activité est plutôt régulée par la disponibilité des coactivateurs ainsi que par des modifications post-traductionnelles. La découverte d'un variant d'épissage pour ERR? (ERR? ?5) a soulevé un nouveau mécanisme de régulation d'ERR?. En effet, puisqu'ERR? ?5 ne pourrait interagir avec les coactivateurs, il pourrait donc agir comme dominant négatif sur l’activité d'ERR?. Dans cette étude, nous avons démontré qu'ERR? et ERR? ?5 colocalisent au noyau en plus d’interagir physiquement De plus, ERR? ?5 réduit l'activité transcriptionnelle d'ERR? ainsi que l'expression de ses gènes cibles. Tout comme ERR?, ERR? ?5 est exprimé dans une multitude de lignées normales et cancéreuses du côlon ainsi que dans des cellules ou tissus provenant de d'autres organes et de d’autres espèces animales. Par contre, la protéine ERR? ?5 est exprimée plus faiblement qu'ERR? puisqu’elle est instable et rapidement dégradée par le protéasome. Néanmoins, la surexpression d'ERR? ?5 réduit la croissance cellulaire et possiblement l'adhésion cellulaire. Bref, nos résultats démontrent qu’ERR? ?5 agit comme dominant négatif sur ERR? et que son expression transitoire pourrait donc affecter l’activité d'ERR? ainsi que ses fonctions biologiques. [symboles non conformes]

TGFβ signalling via Smad transcription factors is essential for axis patterning and subsequent cell fate specification during mammalian embryogenesis. However, the cellular and molecular mechanisms have been difficult to characterise in vivo due to early embryonic lethality of mouse mutants and redundant functional activities. Here I show that combined deletion of closely related Smad2 and Smad3 in mouse embryonic stem cells impairs induction of lineage specific gene expression during differentiation, while extra-embryonic gene expression is up-regulated. Preliminary data suggest that the underlying mechanism of this differentiation defect reflects the inability of Smad2/3^-/- cells to establish lineage priming. Collectively, these findings identify novel downstream target genes controlled by Smad2/3 and an absolute requirement for Smad2/3 during embryonic differentiation. TGFβ signalling via Smad1 and Smad4 is essential for induction of the transcription factor Blimp1 required for primordial germ cell specification. The direct upstream regulators of Blimp1 are unknown, but T-box factors have recently been suggested to play a role. In a second project, I performed tissue- specific ablation of the T-box transcription factor Eomes as well as components of the TGFβ signalling pathway in either the visceral endoderm or the epiblast to examine tissue-specific functions for Blimp1 induction. I show that Eomes and Smad2 functions in the visceral endoderm as well as Eomes function in the epiblast are dispensable for Blimp1 induction, but rather are required to restrict Blimp1 induction to posterior epiblast cells. In contrast, epiblast-specific Smad4 or Smad1 mutants fail to robustly induce Blimp1 in the epiblast. My preliminary analysis suggests that competence to induce primordial germ cell fate is dependent on the interplay of Smad2/Eomes functions in the visceral endoderm and Smad1/4 functions in the epiblast. Collectively, this thesis provides insight into the transition from pluripotency to cell fate specification in the mammalian embryo that is impossible to obtain from human embryos in vivo.