RESUMO
Ewing Sarcoma is the second most common solid pediatric malignant neoplasm of bone and soft tissue. Driven by EWS/Ets, or rarely variant, oncogenic fusions, Ewing Sarcoma is a biologically and clinically aggressive disease with a high propensity for metastasis. However, the mechanisms underpinning Ewing Sarcoma metastasis are currently not well understood. In the present study, we identify and characterize a novel metastasis-promotional pathway in Ewing Sarcoma, involving the histone demethylase KDM3A, previously identified by our laboratory as a new cancer-promoting gene in this disease. Using global gene expression profiling, we show that KDM3A positively regulates genes and pathways implicated in cell migration and metastasis, and demonstrate, using functional assays, that KDM3A promotes migration in vitro and experimental, post-intravasation, metastasis in vivo. We further identify the melanoma cell adhesion molecule (MCAM) as a novel KDM3A target gene in Ewing Sarcoma, and an important effector of KDM3A pro-metastatic action. Specifically, we demonstrate that MCAM depletion, like KDM3A depletion, inhibits cell migration in vitro and experimental metastasis in vivo, and that MCAM partially rescues impaired migration due to KDM3A knock-down. Mechanistically, we show that KDM3A regulates MCAM expression both through a direct mechanism, involving modulation of H3K9 methylation at the MCAM promoter, and an indirect mechanism, via the Ets1 transcription factor. Finally, we identify an association between high MCAM levels in patient tumors and poor survival, in two different Ewing Sarcoma clinical cohorts. Taken together, our studies uncover a new metastasis-promoting pathway in Ewing Sarcoma, with therapeutically targetable components.
Assuntos
Epigenômica/métodos , Histona Desmetilases com o Domínio Jumonji/metabolismo , Sarcoma de Ewing/metabolismo , Sarcoma de Ewing/patologia , Adolescente , Animais , Antígeno CD146/genética , Antígeno CD146/metabolismo , Linhagem Celular Tumoral , Movimento Celular/fisiologia , Criança , Regulação para Baixo , Perfilação da Expressão Gênica , Xenoenxertos , Humanos , Histona Desmetilases com o Domínio Jumonji/genética , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Metástase Neoplásica , Regiões Promotoras Genéticas , Sarcoma de Ewing/enzimologia , Sarcoma de Ewing/genéticaRESUMO
Ewing Sarcoma is a biologically aggressive bone and soft tissue malignancy affecting children and young adults. Ewing Sarcoma pathogenesis is driven by EWS/Ets fusion oncoproteins, of which EWS/Fli1 is the most common. We have previously shown that microRNAs (miRs) regulated by EWS/Fli1 contribute to the pro-oncogenic program in Ewing Sarcoma. Here we show that miR-22, an EWS/Fli1-repressed miR, is inhibitory to Ewing Sarcoma clonogenic and anchorage-independent cell growth, even at modest overexpression levels. Our studies further identify the H3K9me1/2 histone demethylase KDM3A (JMJD1A/JHDM2A) as a new miR-22-regulated gene. We show that KDM3A is overexpressed in Ewing Sarcoma, and that its depletion inhibits clonogenic and anchorage-independent growth in multiple patient-derived cell lines, and tumorigenesis in a xenograft model. KDM3A depletion further results in augmentation of the levels of the repressive H3K9me2 histone mark, and downregulation of pro-oncogenic factors in Ewing Sarcoma. Together, our studies identify the histone demethylase KDM3A as a new, miR-regulated, tumor promoter in Ewing Sarcoma.