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). Using our autochthonous mouse models, we found that Sox9 suppresses HGG growth and expands associated H3K27ac states, while promoting ZFTA-RELA (ZR(FUS)) EPN growth and diminishing H3K27ac states. These contrasting roles for Sox9 correspond with protein interactions with histone deacetylating complexes in HGG and an association with the ZR(FUS) oncofusion in EPN. Mechanistic studies revealed extensive Sox9 and ZR(FUS) promoter co-occupancy, indicating functional synergy in promoting EPN tumorigenesis. 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.

Automated summary

Epigenetic dysregulation is a common characteristic of cancer, leading to altered gene expression patterns that drive malignancy. This study reveals that the developmental transcription factor Sox9 plays different roles in high-grade glioma and ependymoma, possibly due to its interactions with different proteins and fusion events. The study also demonstrates the functional synergy between Sox9 and ZR(FUS) in promoting ependymoma tumorigenesis.