Rôle du TGFbeta dans l’initiation de la carcinogénèse pancréatique

PDA is the 5th cause of cancer related death in the western countries, and is estimated to move the second rank by 2020. The 5-year survival rate is less than 4%, and the median survival is around 6 months. The poor prognostic of this tumor is due to asymptomatic early phases of the disease, resulting in a late diagnosis. Primary tumors are composed by ductal neoplastic lesions embedded into a highly abundant stroma that prevents the access of chemotherapeutic drugs to the tumor cells. Thus, understanding tumor initiation and progression mechanisms is needed to develop new strategies aiming at detecting and taking care of patients in the most optimal manner. TGFbeta is a cytokine playing several physiological functions such as immunity regulation, wound healing, development or angiogenesis. Results presented in this manuscript demonstrate that activation of TGFbeta signaling disturb acinar cell differentiation during development, and disrupts acinar cell identity when activated in the adult pancreas. The simultaneous induction of acinar cell apoptosis and ADM leads to the massive loss of acinar cells and the emergence of ductal structures typical of pancreas regeneration. When the KRASG12D oncogene is expressed in combination with the activation of TGFbeta signaling, these regenerative duct structures are harnessed by KRASG12D to develop early neoplastic lesions. Thus, my work in Dr. Laurent BARTHOLIN’s team demonstrates a new function of TGFbeta in pancreatic carcinogenesis in vivoL’ADKP est la 5e cause de décès par cancer dans le monde occidental, et il est estimé qu’il constituera la 2e cause de mort par cancer d’ici à 2030. Le taux de survie à 5 ans est inférieur à 4%, et la médiane de survie est d’environ 6 mois. Ce pronostic sombre est dû à une pathologie asymptomatique dans les phases précoces du développement tumoral, résultant en un diagnostic tardif. Les tumeurs primaires sont constituées de structures épithéliales néoplasiques entourées par un stroma abondant empêchant l’accès des chimiothérapies aux cellules tumorales. La compréhension des mécanismes d’initiation et de progression tumorale est donc primordiale pour développer de nouvelles stratégies visant à la détection et à la prise en charge thérapeutique optimale des patients atteints d’ADKP. Le TGFbeta est une cytokine assurant de nombreuses fonctions physiologiques comme la régulation de l’immunité, la cicatrisation, le développement ou encore l’angiogenèse. Les résultats présentés dans ce manuscrit mettent en évidence que l’activation de la voie de signalisation TGFbeta perturbe la différenciation des cellules acineuses au cours du développement, et perturbe l’identité acineuse lorsqu’elle est activée dans le pancréas chez l’adulte. L’induction en parallèle de l’apoptose des cellules acineuses et d’une métaplasie acino-canalaire (ou ADM) mène à la disparition quasi-totale du tissu acineux au profit de structures canalaires typiques d’un pancréas en régénération. Lorsque l’oncogène KRASG12D est exprimé en parallèle dans le tissu pancréatique chez l’adulte, ce tissu canalaire régénératif est mis à profit par KRAS pour le développement précoce de lésions pré-néoplasiques. Mes travaux au sein de l’équipe du Dr. Laurent BARTHOLIN permettent donc de démontrer in vivo un nouveau rôle du TGFbeta dans la carcinogénèse pancréatiqu

Role of TGFbeta in the initiation of pancreas carcinogenesis

L’ADKP est la 5e cause de décès par cancer dans le monde occidental, et il est estimé qu’il constituera la 2e cause de mort par cancer d’ici à 2030. Le taux de survie à 5 ans est inférieur à 4%, et la médiane de survie est d’environ 6 mois. Ce pronostic sombre est dû à une pathologie asymptomatique dans les phases précoces du développement tumoral, résultant en un diagnostic tardif. Les tumeurs primaires sont constituées de structures épithéliales néoplasiques entourées par un stroma abondant empêchant l’accès des chimiothérapies aux cellules tumorales. La compréhension des mécanismes d’initiation et de progression tumorale est donc primordiale pour développer de nouvelles stratégies visant à la détection et à la prise en charge thérapeutique optimale des patients atteints d’ADKP. Le TGFbeta est une cytokine assurant de nombreuses fonctions physiologiques comme la régulation de l’immunité, la cicatrisation, le développement ou encore l’angiogenèse. Les résultats présentés dans ce manuscrit mettent en évidence que l’activation de la voie de signalisation TGFbeta perturbe la différenciation des cellules acineuses au cours du développement, et perturbe l’identité acineuse lorsqu’elle est activée dans le pancréas chez l’adulte. L’induction en parallèle de l’apoptose des cellules acineuses et d’une métaplasie acino-canalaire (ou ADM) mène à la disparition quasi-totale du tissu acineux au profit de structures canalaires typiques d’un pancréas en régénération. Lorsque l’oncogène KRASG12D est exprimé en parallèle dans le tissu pancréatique chez l’adulte, ce tissu canalaire régénératif est mis à profit par KRAS pour le développement précoce de lésions pré-néoplasiques. Mes travaux au sein de l’équipe du Dr. Laurent BARTHOLIN permettent donc de démontrer in vivo un nouveau rôle du TGFbeta dans la carcinogénèse pancréatiquePDA is the 5th cause of cancer related death in the western countries, and is estimated to move the second rank by 2020. The 5-year survival rate is less than 4%, and the median survival is around 6 months. The poor prognostic of this tumor is due to asymptomatic early phases of the disease, resulting in a late diagnosis. Primary tumors are composed by ductal neoplastic lesions embedded into a highly abundant stroma that prevents the access of chemotherapeutic drugs to the tumor cells. Thus, understanding tumor initiation and progression mechanisms is needed to develop new strategies aiming at detecting and taking care of patients in the most optimal manner. TGFbeta is a cytokine playing several physiological functions such as immunity regulation, wound healing, development or angiogenesis. Results presented in this manuscript demonstrate that activation of TGFbeta signaling disturb acinar cell differentiation during development, and disrupts acinar cell identity when activated in the adult pancreas. The simultaneous induction of acinar cell apoptosis and ADM leads to the massive loss of acinar cells and the emergence of ductal structures typical of pancreas regeneration. When the KRASG12D oncogene is expressed in combination with the activation of TGFbeta signaling, these regenerative duct structures are harnessed by KRASG12D to develop early neoplastic lesions. Thus, my work in Dr. Laurent BARTHOLIN’s team demonstrates a new function of TGFbeta in pancreatic carcinogenesis in viv

Approches d’immunothérapie cellulaire T dans les tumeurs solides

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Tumour burden and antigen-specific T cell magnitude represent major parameters for clinical response to cancer vaccine and TCR-engineered T cell therapy

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Identification of shared tumor epitopes from endogenous retroviruses inducing high-avidity cytotoxic T cells for cancer immunotherapy

International audienceHuman endogenous retroviruses (HERVs) represent 8% of the human genome. HERV products may represent tumor antigens relevant for cancer immunotherapy. We developed a bioinformatic approach to identify shared CD8 + T cell epitopes derived from cancer-associated HERVs in solid tumors. Six candidates among the most commonly shared HLA-A2 epitopes with evidence of translation were selected for immunological evaluation. In vitro priming assays confirmed the immunogenicity of these epitopes, which induced high-avidity CD8 + T cell clones. These T cells specifically recognize and kill HLA-A2 + tumor cells presenting HERV epitopes on HLA molecules, as demonstrated by mass spectrometry. Furthermore, epitope-specific CD8 + T cells were identified by dextramer staining among tumor-infiltrating lymphocytes from HLA-A2 + patients with breast cancer. Last, we showed that HERV-specific T cells lyse patient-derived organoids. These shared virus-like epitopes are of major interest for the development of cancer vaccines or T cell–based immunotherapies, especially in tumors with low/intermediate mutational burden

Generation of a conditional Flpo/FRT mouse model expressing constitutively active TGFβ in fibroblasts

International audienceTransforming growth factor (TGFβ) is a secreted factor, which accumulates in tissues during many physio- and pathological processes such as embryonic development, wound healing, fibrosis and cancer. In order to analyze the effects of increased microenvironmental TGFβ concentration in vivo, we developed a conditional transgenic mouse model (Flpo/Frt system) expressing bioactive TGFβ in fibroblasts, a cell population present in the microenvironment of almost all tissues. To achieve this, we created the genetically-engineered [Fsp1-Flpo; FSFTGFβCA] mouse model. The Fsp1-Flpo allele consists in the Flpo recombinase under the control of the Fsp1 (fibroblast-specific promoter 1) promoter. The FSFTGFβCA allele consists in a transgene encoding a constitutively active mutant form of TGFβ (TGFβCA) under the control of a Frt-STOP-Frt (FSF) cassette. The FSFTGFβCA allele was created to generate this model, and functionally validated by in vitro, ex vivo and in vivo techniques. [Fsp1-Flpo; FSFTGFβCA] animals do not present any obvious phenotype despite the correct expression of TGFβCA transgene in fibroblasts. This [Fsp1-Flpo; FSFTGFβCA] model is highly pertinent for future studies on the effect of increased microenvironmental bioactive TGFβ concentrations in mice bearing Cre-dependent genetic alterations in other compartments (epithelial or immune compartments for instance). These dual recombinase system (DRS) approaches will enable scientists to study uncoupled spatiotemporal regulation of different genetic alterations within the same mouse, thus better replicating the complexity of human diseases

Tif1γ Suppresses Murine Pancreatic Tumoral Transformation by a Smad4-Independent Pathway

International audienceTranscriptional intermediary factor 1␥ (TIF1␥; alias, TRIM33/RFG7/PTC7/ectodermin) belongs to an evolutionarily conserved family of nuclear factors that have been implicated in stem cell pluripo-tency, embryonic development, and tumor suppression. TIF1␥ expression is markedly down-regulated in human pancreatic tumors, and Pdx1-driven Tif1␥ inactivation cooperates with the Kras G12D onco-gene in the mouse pancreas to induce intraductal papillary mucinous neoplasms. In this study, we report that aged Pdx1-Cre; LSL-Kras G12D ; Tif1␥ lox/lox mice develop pancreatic ductal adenocarcinomas (PDACs), an aggressive and always fatal neoplasm, demonstrating a Tif1␥ tumor-suppressive function in the development of pancreatic carcinogenesis. Deletion of SMAD4/DPC4 (deleted in pancreatic car-cinoma locus 4) occurs in approximately 50% of human cases of PDAC. We, therefore, assessed the genetic relationship between Tif1␥ and Smad4 sig-naling in pancreatic tumors and found that Pdx1-Cre; LSL-Kras G12D ; Smad4 lox/lox ; Tif1␥ lox/lox (alias, KSSTT) mutant mice exhibit accelerated tumor progression. Consequently, Tif1␥ tumor-suppressor effects during progression from a premalignant to a malignant state in our mouse model of pancreatic cancer are independent of Smad4. These findings establish, for the first time to our knowledge, that Tif1␥ and Smad4 both regulate an intraductal papillary mucinous neoplasm-to-PDAC sequence through distinct tumor-suppressor programs

HERVs characterize normal and leukemia stem cells and represent a source of shared epitopes for cancer immunotherapy

International audienceHuman endogenous retroviruses (HERVs) represent 8% of the human genome. The expression of HERVs and their immune impact have not been extensively studied in Acute Myeloid Leukemia (AML). In this study, we used a reference of 14 968 HERV functional units to provide a thorough analysis of HERV expression in normal and AML bone marrow cells. We show that the HERV retrotranscriptome accurately characterizes normal and leukemic cell subpopulations, including leukemia stem cells, in line with different epigenetic profiles. We then show that HERV expression delineates AML subtypes with different prognoses. We finally propose a method to select and prioritize CD8 + T cell epitopes derived from AML-specific HERVs and we show that lymphocytes infiltrating patient bone marrow at diagnosis contain naturall

TIF1 Suppresses Tumor Progression by Regulating Mitotic Checkpoints and Chromosomal Stability

The transcription accessory factor TIF1γ/TRIM33/RFG7/PTC7/Ectodermin functions as a tumor suppressor that promotes development and cellular differentiation. However, its precise function in cancer has been elusive. In the present study, we report that TIF1γ inactivation causes cells to accumulate chromosomal defects, a hallmark of cancer, due to attenuations in the spindle assembly checkpoint and the post-mitotic checkpoint. TIF1γ deficiency also caused a loss of contact growth inhibition and increased anchorage-independent growth in vitro and in vivo. Clinically, reduced TIF1γ expression in human tumors correlated with an increased rate of genomic rearrangements. Overall, our work indicates that TIF1γ exerts its tumor-suppressive functions in part by promoting chromosomal stability