EPEN-05. TRANSCRIPTIONAL FACTOR-DIRECTED EPIGENETIC REGULATION IN CANCER NEUROSCIENCE OF ZFTA-RELA EPENDYMOMA

ZFTA-RELA (ZR^FUS) ependymoma is a pediatric brain tumor with dismal 10-year progression free survival rates. Prior studies revealed low somatic mutation load in pediatric ependymoma compared to adult glioma, suggesting that developmental mechanisms play a key role during disease development. Using human tissues and mouse tumors generated from our autochthonous in utero electroporation (IUE) model, we identified a cohort of developmental transcription factors (TFs) linked to ZR^FUS by investigating histone serotonylation changes with other epigenetic datasets. We further performed in vivo barcode-screening and identified the ETS variant transcription factor 5 (ETV5) is sufficient and required for disease progression. To further reveal the disease mechanism driven by ETV5, we applied transcriptomic, epigenetic, and proteomic analyses, and found ETV5 suppresses neuropeptide Y (NPY) expression in mouse ZR^FUS tumors by binding with epigenetic modulator, chromobox 3 (CBX3). We further found NPY overexpression delays tumor progression and suppressed tumor-driven neuronal activity in mice. This study suggests developmental TF can shape tumor-promoting microenvironment during disease progression through epigenetic regulation.