11 research outputs found
Nouveau modĂšle dâĂ©tude de lâhĂ©patoblastome in vivo et identification de microARNs rĂ©gulateurs de la ÎČ-catĂ©nine
Hepatoblastoma (HBL) is the most common pediatric liver cancer. At molecular level it is characterized by activating mutations in ÎČ-catenin gene (CTNNB1) that cause protein accumulation and abnormal Wnt signaling pathway activation leading to malignant transformation of hepatic cells. Therefore, ÎČ-catenin is a key therapeutic target in HBL.This manuscript describes two major parts of my thesis project that aimed to understand the role of ÎČ-catenin-regulating microRNAs in HBL carcinogenesis.The first part presents the development of a new in vivo HBL model. This work consisted of making HBL-derived cells xenograft on chick embryo chorioallantoic membrane (CAM) and studying tumor development using histological and molecular approaches. My results show that HBL cells implanted on CAM modify their phenotype and activate survival and proliferation mechanisms to form organized and vascularized tumor nodules. Cell treatment with cisplatin leads to tumor progression arrest.The second part presents results concerning the regulation of ÎČ-catenin and oncogenic processes by microRNAs in HBL cells. A functional screening allowed me to identify several microRNAs with an inhibitory effect on ÎČ-catenin. Four microRNAs down-regulated in patient tumors inhibit cell proliferation and Wnt pathway activity in vitro. The most efficient microRNA directly interacts with ÎČ-catenin mRNA through a unique site localized in 3â untranslated region and blocks HBL tumor growth on CAM.During my thesis I developed a new animal model to study HBL that allows modelling rapid tumor growth and testing the impact of therapeutic molecules. My work also led to the identification of new microRNAs down-regulated in HBL tumors that inhibit ÎČ-catenin expression and act as tumor suppressor genes. Those microRNAs represent new potential therapeutic molecules for HBL treatment and could be also used as diagnostic and prognostic biomarkers.Nouveau modĂšle dâĂ©tude de lâhĂ©patoblastome in vivo et identification de microARNs rĂ©gulateurs de la ÎČ-catĂ©nineLâhĂ©patoblastome (HBL) est le cancer du foie le plus frĂ©quent chez lâenfant. Au niveau molĂ©culaire, il est caractĂ©risĂ© par des mutations activatrices dans le gĂšne de la ÎČ-catĂ©nine (CTNNB1) entrainant une accumulation de sa protĂ©ine et une activation anormale de la voie de signalisation Wnt, responsables de la transformation maligne des cellules hĂ©patiques. Ainsi, la ÎČ-catĂ©nine est une cible thĂ©rapeutique majeure dans lâHBL.Ce manuscrit dĂ©crit les deux parties principales de mon projet de thĂšse, dont lâobjectif Ă©tait dâĂ©tudier le rĂŽle de microARNs rĂ©gulateurs de la ÎČ-catĂ©nine sur la carcinogenĂšse de lâHBL.La premiĂšre partie prĂ©sente le dĂ©veloppement dâun nouveau modĂšle dâĂ©tude in vivo de lâHBL. Ce travail a consistĂ© Ă rĂ©aliser des xĂ©nogreffes de cellules dĂ©rivĂ©es dâHBL sur la membrane chorioallantoidienne (CAM) de lâembryon de poulet, et Ă Ă©tudier le dĂ©veloppement des tumeurs par des approches histologiques et molĂ©culaires. Mes rĂ©sultats montrent que les cellules dâHBL modifient leur phĂ©notype et activent des mĂ©canismes de survie et de prolifĂ©ration pour former des nodules tumoraux structurĂ©s et vascularisĂ©s au sein de la CAM. Le traitement des cellules par le cisplatine conduit Ă un arrĂȘt net de la progression tumorale.La seconde partie prĂ©sente les rĂ©sultats concernant la rĂ©gulation de la ÎČ-catĂ©nine et des processus oncogĂ©niques par les microARNs dans les cellules dâHBL. Un crible fonctionnel mâa permis dâidentifier plusieurs microARNs ayant un effet inhibiteur sur la ÎČ-catĂ©nine. Quatre microARNs, sous-exprimĂ©s dans les tumeurs de patients, bloquent la prolifĂ©ration cellulaire et lâactivitĂ© de la voie Wnt in vitro. Le miARN le plus efficace interagit avec lâARNm de la ÎČ-catĂ©nine via un site unique localisĂ© dans sa rĂ©gion 3â non traduite et bloque la croissance des tumeurs dâHBL sur la CAM.Durant ma thĂšse jâai dĂ©veloppĂ© un nouveau modĂšle animal dâĂ©tude de lâHBL qui permet de modĂ©liser la croissance tumorale et de tester lâimpact de molĂ©cules thĂ©rapeutiques. Ce travail a Ă©galement permis dâidentifier de nouveaux microARNs sous-exprimĂ©s dans les tumeurs dâHBL, qui inhibent lâexpression de la ÎČ-catĂ©nine et agissent comme des gĂšnes suppresseurs de tumeur. Ces microARNs constituent de potentielles nouvelles molĂ©cules thĂ©rapeutiques dans le traitement de lâHBL et pourraient aussi ĂȘtre utilisĂ©s comme des biomarqueurs diagnostiques et pronostiques
New in vivo model of hepatoblastoma and identification of microRNAs regulating ÎČ-catenin
Nouveau modĂšle dâĂ©tude de lâhĂ©patoblastome in vivo et identification de microARNs rĂ©gulateurs de la ÎČ-catĂ©nineLâhĂ©patoblastome (HBL) est le cancer du foie le plus frĂ©quent chez lâenfant. Au niveau molĂ©culaire, il est caractĂ©risĂ© par des mutations activatrices dans le gĂšne de la ÎČ-catĂ©nine (CTNNB1) entrainant une accumulation de sa protĂ©ine et une activation anormale de la voie de signalisation Wnt, responsables de la transformation maligne des cellules hĂ©patiques. Ainsi, la ÎČ-catĂ©nine est une cible thĂ©rapeutique majeure dans lâHBL.Ce manuscrit dĂ©crit les deux parties principales de mon projet de thĂšse, dont lâobjectif Ă©tait dâĂ©tudier le rĂŽle de microARNs rĂ©gulateurs de la ÎČ-catĂ©nine sur la carcinogenĂšse de lâHBL.La premiĂšre partie prĂ©sente le dĂ©veloppement dâun nouveau modĂšle dâĂ©tude in vivo de lâHBL. Ce travail a consistĂ© Ă rĂ©aliser des xĂ©nogreffes de cellules dĂ©rivĂ©es dâHBL sur la membrane chorioallantoidienne (CAM) de lâembryon de poulet, et Ă Ă©tudier le dĂ©veloppement des tumeurs par des approches histologiques et molĂ©culaires. Mes rĂ©sultats montrent que les cellules dâHBL modifient leur phĂ©notype et activent des mĂ©canismes de survie et de prolifĂ©ration pour former des nodules tumoraux structurĂ©s et vascularisĂ©s au sein de la CAM. Le traitement des cellules par le cisplatine conduit Ă un arrĂȘt net de la progression tumorale.La seconde partie prĂ©sente les rĂ©sultats concernant la rĂ©gulation de la ÎČ-catĂ©nine et des processus oncogĂ©niques par les microARNs dans les cellules dâHBL. Un crible fonctionnel mâa permis dâidentifier plusieurs microARNs ayant un effet inhibiteur sur la ÎČ-catĂ©nine. Quatre microARNs, sous-exprimĂ©s dans les tumeurs de patients, bloquent la prolifĂ©ration cellulaire et lâactivitĂ© de la voie Wnt in vitro. Le miARN le plus efficace interagit avec lâARNm de la ÎČ-catĂ©nine via un site unique localisĂ© dans sa rĂ©gion 3â non traduite et bloque la croissance des tumeurs dâHBL sur la CAM.Durant ma thĂšse jâai dĂ©veloppĂ© un nouveau modĂšle animal dâĂ©tude de lâHBL qui permet de modĂ©liser la croissance tumorale et de tester lâimpact de molĂ©cules thĂ©rapeutiques. Ce travail a Ă©galement permis dâidentifier de nouveaux microARNs sous-exprimĂ©s dans les tumeurs dâHBL, qui inhibent lâexpression de la ÎČ-catĂ©nine et agissent comme des gĂšnes suppresseurs de tumeur. Ces microARNs constituent de potentielles nouvelles molĂ©cules thĂ©rapeutiques dans le traitement de lâHBL et pourraient aussi ĂȘtre utilisĂ©s comme des biomarqueurs diagnostiques et pronostiques.Hepatoblastoma (HBL) is the most common pediatric liver cancer. At molecular level it is characterized by activating mutations in ÎČ-catenin gene (CTNNB1) that cause protein accumulation and abnormal Wnt signaling pathway activation leading to malignant transformation of hepatic cells. Therefore, ÎČ-catenin is a key therapeutic target in HBL.This manuscript describes two major parts of my thesis project that aimed to understand the role of ÎČ-catenin-regulating microRNAs in HBL carcinogenesis.The first part presents the development of a new in vivo HBL model. This work consisted of making HBL-derived cells xenograft on chick embryo chorioallantoic membrane (CAM) and studying tumor development using histological and molecular approaches. My results show that HBL cells implanted on CAM modify their phenotype and activate survival and proliferation mechanisms to form organized and vascularized tumor nodules. Cell treatment with cisplatin leads to tumor progression arrest.The second part presents results concerning the regulation of ÎČ-catenin and oncogenic processes by microRNAs in HBL cells. A functional screening allowed me to identify several microRNAs with an inhibitory effect on ÎČ-catenin. Four microRNAs down-regulated in patient tumors inhibit cell proliferation and Wnt pathway activity in vitro. The most efficient microRNA directly interacts with ÎČ-catenin mRNA through a unique site localized in 3â untranslated region and blocks HBL tumor growth on CAM.During my thesis I developed a new animal model to study HBL that allows modelling rapid tumor growth and testing the impact of therapeutic molecules. My work also led to the identification of new microRNAs down-regulated in HBL tumors that inhibit ÎČ-catenin expression and act as tumor suppressor genes. Those microRNAs represent new potential therapeutic molecules for HBL treatment and could be also used as diagnostic and prognostic biomarkers
New in vivo model of hepatoblastoma and identification of microRNAs regulating ÎČ-catenin
Nouveau modĂšle dâĂ©tude de lâhĂ©patoblastome in vivo et identification de microARNs rĂ©gulateurs de la ÎČ-catĂ©nineLâhĂ©patoblastome (HBL) est le cancer du foie le plus frĂ©quent chez lâenfant. Au niveau molĂ©culaire, il est caractĂ©risĂ© par des mutations activatrices dans le gĂšne de la ÎČ-catĂ©nine (CTNNB1) entrainant une accumulation de sa protĂ©ine et une activation anormale de la voie de signalisation Wnt, responsables de la transformation maligne des cellules hĂ©patiques. Ainsi, la ÎČ-catĂ©nine est une cible thĂ©rapeutique majeure dans lâHBL.Ce manuscrit dĂ©crit les deux parties principales de mon projet de thĂšse, dont lâobjectif Ă©tait dâĂ©tudier le rĂŽle de microARNs rĂ©gulateurs de la ÎČ-catĂ©nine sur la carcinogenĂšse de lâHBL.La premiĂšre partie prĂ©sente le dĂ©veloppement dâun nouveau modĂšle dâĂ©tude in vivo de lâHBL. Ce travail a consistĂ© Ă rĂ©aliser des xĂ©nogreffes de cellules dĂ©rivĂ©es dâHBL sur la membrane chorioallantoidienne (CAM) de lâembryon de poulet, et Ă Ă©tudier le dĂ©veloppement des tumeurs par des approches histologiques et molĂ©culaires. Mes rĂ©sultats montrent que les cellules dâHBL modifient leur phĂ©notype et activent des mĂ©canismes de survie et de prolifĂ©ration pour former des nodules tumoraux structurĂ©s et vascularisĂ©s au sein de la CAM. Le traitement des cellules par le cisplatine conduit Ă un arrĂȘt net de la progression tumorale.La seconde partie prĂ©sente les rĂ©sultats concernant la rĂ©gulation de la ÎČ-catĂ©nine et des processus oncogĂ©niques par les microARNs dans les cellules dâHBL. Un crible fonctionnel mâa permis dâidentifier plusieurs microARNs ayant un effet inhibiteur sur la ÎČ-catĂ©nine. Quatre microARNs, sous-exprimĂ©s dans les tumeurs de patients, bloquent la prolifĂ©ration cellulaire et lâactivitĂ© de la voie Wnt in vitro. Le miARN le plus efficace interagit avec lâARNm de la ÎČ-catĂ©nine via un site unique localisĂ© dans sa rĂ©gion 3â non traduite et bloque la croissance des tumeurs dâHBL sur la CAM.Durant ma thĂšse jâai dĂ©veloppĂ© un nouveau modĂšle animal dâĂ©tude de lâHBL qui permet de modĂ©liser la croissance tumorale et de tester lâimpact de molĂ©cules thĂ©rapeutiques. Ce travail a Ă©galement permis dâidentifier de nouveaux microARNs sous-exprimĂ©s dans les tumeurs dâHBL, qui inhibent lâexpression de la ÎČ-catĂ©nine et agissent comme des gĂšnes suppresseurs de tumeur. Ces microARNs constituent de potentielles nouvelles molĂ©cules thĂ©rapeutiques dans le traitement de lâHBL et pourraient aussi ĂȘtre utilisĂ©s comme des biomarqueurs diagnostiques et pronostiques.Hepatoblastoma (HBL) is the most common pediatric liver cancer. At molecular level it is characterized by activating mutations in ÎČ-catenin gene (CTNNB1) that cause protein accumulation and abnormal Wnt signaling pathway activation leading to malignant transformation of hepatic cells. Therefore, ÎČ-catenin is a key therapeutic target in HBL.This manuscript describes two major parts of my thesis project that aimed to understand the role of ÎČ-catenin-regulating microRNAs in HBL carcinogenesis.The first part presents the development of a new in vivo HBL model. This work consisted of making HBL-derived cells xenograft on chick embryo chorioallantoic membrane (CAM) and studying tumor development using histological and molecular approaches. My results show that HBL cells implanted on CAM modify their phenotype and activate survival and proliferation mechanisms to form organized and vascularized tumor nodules. Cell treatment with cisplatin leads to tumor progression arrest.The second part presents results concerning the regulation of ÎČ-catenin and oncogenic processes by microRNAs in HBL cells. A functional screening allowed me to identify several microRNAs with an inhibitory effect on ÎČ-catenin. Four microRNAs down-regulated in patient tumors inhibit cell proliferation and Wnt pathway activity in vitro. The most efficient microRNA directly interacts with ÎČ-catenin mRNA through a unique site localized in 3â untranslated region and blocks HBL tumor growth on CAM.During my thesis I developed a new animal model to study HBL that allows modelling rapid tumor growth and testing the impact of therapeutic molecules. My work also led to the identification of new microRNAs down-regulated in HBL tumors that inhibit ÎČ-catenin expression and act as tumor suppressor genes. Those microRNAs represent new potential therapeutic molecules for HBL treatment and could be also used as diagnostic and prognostic biomarkers
New in vivo model of hepatoblastoma and identification of microRNAs regulating ÎČ-catenin
Nouveau modĂšle dâĂ©tude de lâhĂ©patoblastome in vivo et identification de microARNs rĂ©gulateurs de la ÎČ-catĂ©nineLâhĂ©patoblastome (HBL) est le cancer du foie le plus frĂ©quent chez lâenfant. Au niveau molĂ©culaire, il est caractĂ©risĂ© par des mutations activatrices dans le gĂšne de la ÎČ-catĂ©nine (CTNNB1) entrainant une accumulation de sa protĂ©ine et une activation anormale de la voie de signalisation Wnt, responsables de la transformation maligne des cellules hĂ©patiques. Ainsi, la ÎČ-catĂ©nine est une cible thĂ©rapeutique majeure dans lâHBL.Ce manuscrit dĂ©crit les deux parties principales de mon projet de thĂšse, dont lâobjectif Ă©tait dâĂ©tudier le rĂŽle de microARNs rĂ©gulateurs de la ÎČ-catĂ©nine sur la carcinogenĂšse de lâHBL.La premiĂšre partie prĂ©sente le dĂ©veloppement dâun nouveau modĂšle dâĂ©tude in vivo de lâHBL. Ce travail a consistĂ© Ă rĂ©aliser des xĂ©nogreffes de cellules dĂ©rivĂ©es dâHBL sur la membrane chorioallantoidienne (CAM) de lâembryon de poulet, et Ă Ă©tudier le dĂ©veloppement des tumeurs par des approches histologiques et molĂ©culaires. Mes rĂ©sultats montrent que les cellules dâHBL modifient leur phĂ©notype et activent des mĂ©canismes de survie et de prolifĂ©ration pour former des nodules tumoraux structurĂ©s et vascularisĂ©s au sein de la CAM. Le traitement des cellules par le cisplatine conduit Ă un arrĂȘt net de la progression tumorale.La seconde partie prĂ©sente les rĂ©sultats concernant la rĂ©gulation de la ÎČ-catĂ©nine et des processus oncogĂ©niques par les microARNs dans les cellules dâHBL. Un crible fonctionnel mâa permis dâidentifier plusieurs microARNs ayant un effet inhibiteur sur la ÎČ-catĂ©nine. Quatre microARNs, sous-exprimĂ©s dans les tumeurs de patients, bloquent la prolifĂ©ration cellulaire et lâactivitĂ© de la voie Wnt in vitro. Le miARN le plus efficace interagit avec lâARNm de la ÎČ-catĂ©nine via un site unique localisĂ© dans sa rĂ©gion 3â non traduite et bloque la croissance des tumeurs dâHBL sur la CAM.Durant ma thĂšse jâai dĂ©veloppĂ© un nouveau modĂšle animal dâĂ©tude de lâHBL qui permet de modĂ©liser la croissance tumorale et de tester lâimpact de molĂ©cules thĂ©rapeutiques. Ce travail a Ă©galement permis dâidentifier de nouveaux microARNs sous-exprimĂ©s dans les tumeurs dâHBL, qui inhibent lâexpression de la ÎČ-catĂ©nine et agissent comme des gĂšnes suppresseurs de tumeur. Ces microARNs constituent de potentielles nouvelles molĂ©cules thĂ©rapeutiques dans le traitement de lâHBL et pourraient aussi ĂȘtre utilisĂ©s comme des biomarqueurs diagnostiques et pronostiques.Hepatoblastoma (HBL) is the most common pediatric liver cancer. At molecular level it is characterized by activating mutations in ÎČ-catenin gene (CTNNB1) that cause protein accumulation and abnormal Wnt signaling pathway activation leading to malignant transformation of hepatic cells. Therefore, ÎČ-catenin is a key therapeutic target in HBL.This manuscript describes two major parts of my thesis project that aimed to understand the role of ÎČ-catenin-regulating microRNAs in HBL carcinogenesis.The first part presents the development of a new in vivo HBL model. This work consisted of making HBL-derived cells xenograft on chick embryo chorioallantoic membrane (CAM) and studying tumor development using histological and molecular approaches. My results show that HBL cells implanted on CAM modify their phenotype and activate survival and proliferation mechanisms to form organized and vascularized tumor nodules. Cell treatment with cisplatin leads to tumor progression arrest.The second part presents results concerning the regulation of ÎČ-catenin and oncogenic processes by microRNAs in HBL cells. A functional screening allowed me to identify several microRNAs with an inhibitory effect on ÎČ-catenin. Four microRNAs down-regulated in patient tumors inhibit cell proliferation and Wnt pathway activity in vitro. The most efficient microRNA directly interacts with ÎČ-catenin mRNA through a unique site localized in 3â untranslated region and blocks HBL tumor growth on CAM.During my thesis I developed a new animal model to study HBL that allows modelling rapid tumor growth and testing the impact of therapeutic molecules. My work also led to the identification of new microRNAs down-regulated in HBL tumors that inhibit ÎČ-catenin expression and act as tumor suppressor genes. Those microRNAs represent new potential therapeutic molecules for HBL treatment and could be also used as diagnostic and prognostic biomarkers
Tracking cellular and molecular changes in a species-specific manner during experimental tumor progression <i>in vivo</i>
International audienceHepatoblastoma (HBL) is a pediatric liver cancer with defined molecular alterations driving its progression. Here, we describe an animal model for HBL on the chick chorioallantoic membrane (CAM), which recapitulates relevant features of HBL in patients. Expression of classic tumor-associated proteins such as ÎČ-catenin, EpCAM and CK19 was maintained in acini-like organized tumors on CAM, as was synthesis of AFP, a tumor marker used for monitoring patient response. RNA sequencing revealed an unexpected molecular evolution of HBL cells on the CAM, with significant deregulation of more than 6,000 genes including more than half of all HOX genes. Bioinformatic analysis distinguish between tumor cell-expressed genes and chick genes, thereby shedding new light on the complex interactions taking place during HBL progression. Importantly, human tumor suppressive ribosomal genes were downregulated after implantation, whereas mitochondrial genes encoding for anti-apoptotic peptides were strongly induced in vivo. Meprin-1α expression was increased during evolution of CAM tumors and confirmed by immunohistochemistry. Cisplatin, a commonly used chemotherapeutic agent for HBL, showed significant anti-tumoral effects. Our results broaden the understanding of the molecular adaptation process of human cancer cells to the microenvironment and might help to elaborate novel therapeutic concepts for the treatment of this pediatric liver tumor
New tumor suppressor microRNAs target glypican-3 in human liver cancer
International audienceGlypican-3 (GPC3) is an oncogene, frequently upregulated in liver malignancies such as hepatocellular carcinoma (HCC) and hepatoblastoma and constitutes a potential molecular target for therapy in liver cancer. Using a functional screening system, we identified 10 new microRNAs controlling GPC3 expression in malignant liver cells, five of them e.g. miR-4510, miR-203a-3p, miR-548aa, miR-376b-3p and miR-548v reduce GPC3 expression. These 5 microRNAs were significantly downregulated in tumoral compared to non-tumoral liver and inhibited tumor cell proliferation. Interestingly, miR-4510 inversely correlated with GPC3 mRNA and protein in HCC samples. This microRNA also induced apoptosis of hepatoma cells and blocked tumor growth in vivo in the chick chorioallantoic membrane model. We further show that the tumor suppressive effect of miR-4510 is mediated through direct targeting of GPC3 mRNA and inactivation of Wnt/ÎČ-catenin transcriptional activity and signaling pathway. Moreover, miR-4510 up-regulated the expression of several tumor suppressor genes while reducing the expression of other pro-oncogenes. In summary, we uncovered several new microRNAs targeting the oncogenic functions of GPC3. We provided strong molecular, cellular and in vivo evidences for the tumor suppressive activities of miR-4510 bringing to the fore the potential value of this microRNA in HCC therapy
Identification and experimental validation of druggable epigenetic targets in hepatoblastoma
International audienc
Germline elongator mutations in Sonic Hedgehog medulloblastoma
Cancer genomics has revealed many genes and core molecular processes that contribute to human malignancies, but the genetic and molecular bases of many rare cancers remains unclear. Genetic predisposition accounts for 5 to 10% of cancer diagnoses in children(1,2), and genetic events that cooperate with known somatic driver events are poorly understood. Pathogenic germline variants in established cancer predisposition genes have been recently identified in 5% of patients with the malignant brain tumour medulloblastoma(3). Here, by analysing all protein-coding genes, we identify and replicate rare germline loss-of-function variants across ELP1 in 14% of paediatric patients with the medulloblastoma subgroup Sonic Hedgehog (MBSHH)(.)ELP1 was the most common medulloblastoma predisposition gene and increased the prevalence of genetic predisposition to 40% among paediatric patients with MBSHH. Parent-offspring and pedigree analyses identified two families with a history of paediatric medulloblastoma. ELP1-associated medulloblastomas were restricted to the molecular SHH alpha subtype(4) and characterized by universal biallelic inactivation of ELP1 owing to somatic loss of chromosome arm 9q. Most ELP1-associated medulloblastomas also exhibited somatic alterations in PTCH1, which suggests that germline ELP1 loss-of-function variants predispose individuals to tumour development in combination with constitutive activation of SHH signalling. ELP1 is the largest subunit of the evolutionarily conserved Elongator complex, which catalyses translational elongation through tRNA modifications at the wobble (U-34) position(5,6). Tumours from patients with ELP1-associated MBSHH were characterized by a destabilized Elongator complex, loss of Elongator-dependent tRNA modifications, codon-dependent translational reprogramming, and induction of the unfolded protein response, consistent with loss of protein homeostasis due to Elongator deficiency in model systems(7-9). Thus, genetic predisposition to proteome instability may be a determinant in the pathogenesis of paediatric brain cancers. These results support investigation of the role of protein homeostasis in other cancer types and potential for therapeutic interference.Germline mutations in the Elongator complex gene ELP1 predispose individuals to the development of childhood medulloblastoma
Aberrant ERBB4-SRC Signaling as a Hallmark of Group 4 Medulloblastoma Revealed by Integrative Phosphoproteomic Profiling
International audienc
Identification and experimental validation of druggable epigenetic targets in hepatoblastoma
Background & Aims: Hepatoblastoma (HB) is the most frequent childhood liver cancer. Patients with aggressive tumors have
limited therapeutic options; therefore, a better understanding of HB pathogenesis is needed to improve treatment. HBs have a
very low mutational burden; however, epigenetic alterations are increasingly recognized. We aimed to identify epigenetic regulators consistently dysregulated in HB and to evaluate the therapeutic efficacy of their targeting in clinically relevant models.
Methods: We performed a comprehensive transcriptomic analysis of 180 epigenetic genes. Data from fetal, pediatric, adult,
peritumoral (n = 72) and tumoral (n = 91) tissues were integrated. Selected epigenetic drugs were tested in HB cells. The most
relevant epigenetic target identified was validated in primary HB cells, HB organoids, a patient-derived xenograft model, and a
genetic mouse model. Transcriptomic, proteomic and metabolomic mechanistic analyses were performed.
Results: Altered expression of genes regulating DNA methylation and histone modifications was consistently observed in association with molecular and clinical features of poor prognosis. The histone methyltransferase G9a was markedly upregulated in
tumors with epigenetic and transcriptomic traits of increased malignancy. Pharmacological targeting of G9a significantly inhibited
growth of HB cells, organoids and patient-derived xenografts. Development of HB induced by oncogenic forms of b-catenin and
YAP1 was ablated in mice with hepatocyte-specific deletion of G9a. We observed that HBs undergo significant transcriptional
rewiring in genes involved in amino acid metabolism and ribosomal biogenesis. G9a inhibition counteracted these pro-tumorigenic
adaptations. Mechanistically, G9a targeting potently repressed the expression of c-MYC and ATF4, master regulators of HB
metabolic reprogramming.
Conclusions: HBs display a profound dysregulation of the epigenetic machinery. Pharmacological targeting of key epigenetic
effectors exposes metabolic vulnerabilities that can be leveraged to improve the treatment of these patients