Sox9 directs divergent epigenomic states in brain tumor subtypes

Epigenetic dysregulation is a universal feature of cancer that results in altered patterns of gene expression that drive malignancy. Brain tumors exhibit subtype-specific epigenetic alterations, however the molecular mechanisms responsible for these diverse epigenetic states remain unclear. Here we show that the developmental transcription factor Sox9 differentially regulates epigenomic states in high-grade glioma (HGG) and ependymoma (EPN). These contrasting roles for Sox9 correspond with protein interactions with histone deacetylating complexes in HGG, and association with the Rela oncofusion in EPN. Together, our studies demonstrate how epigenomic states are differentially regulated in distinct subtypes of brain tumors, while revealing divergent roles for Sox9 in HGG and EPN tumorigenesis.