RESUMO
Lineage or cell of origin of cancers is often unknown and thus is not a consideration in therapeutic approaches. Alveolar rhabdomyosarcoma (aRMS) is an aggressive childhood cancer for which the cell of origin remains debated. We used conditional genetic mouse models of aRMS to activate the pathognomonic Pax3:Foxo1 fusion oncogene and inactivate p53 in several stages of prenatal and postnatal muscle development. We reveal that lineage of origin significantly influences tumor histomorphology and sensitivity to targeted therapeutics. Furthermore, we uncovered differential transcriptional regulation of the Pax3:Foxo1 locus by tumor lineage of origin, which led us to identify the histone deacetylase inhibitor entinostat as a pharmacological agent for the potential conversion of Pax3:Foxo1-positive aRMS to a state akin to fusion-negative RMS through direct transcriptional suppression of Pax3:Foxo1.
Assuntos
Antineoplásicos/farmacologia , Benzamidas/farmacologia , Piridinas/farmacologia , Rabdomiossarcoma Alveolar/patologia , Animais , Linhagem Celular Tumoral , Linhagem da Célula , Modelos Animais de Doenças , Epigênese Genética/efeitos dos fármacos , Proteína Forkhead Box O1 , Fatores de Transcrição Forkhead/metabolismo , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Camundongos , Fator de Transcrição PAX3 , Fatores de Transcrição Box Pareados/metabolismo , Proteína Supressora de Tumor p53/metabolismoRESUMO
Rhabdomyosarcoma is an aggressive childhood malignancy, accounting for more than 50% of all soft-tissue sarcomas in children. Even with extensive therapy, the survival rate among alveolar rhabdomyosarcoma patients with advanced disease is only 20%. The receptor tyrosine kinase Epidermal Growth Factor Receptor (EGFR) has been found to be expressed and activated in human rhabdomyosarcomas. In this study we have used a genetically engineered mouse model for alveolar rhabdomyosarcoma (ARMS) which faithfully recapitulates the human disease by activating the pathognomic Pax3:Fkhr fusion gene and inactivating p53 in the maturing myoblasts. We have demonstrated that tumors from our mouse model of alveolar rhabdomyosarcoma express EGFR at both the mRNA and protein levels. We then tested the EGFR inhibitor, Erlotinib, for its efficacy in this mouse model of alveolar rhabdomyosarcoma. Surprisingly, Erlotinib had no effect on tumor progression, yet mice treated with Erlotinib showed 10-20% loss of body weight. These results suggest that EGFR might not be an a priori monotherapy target in alveolar rhabdomyosarcoma.
