RNA N6-methyladenosine (m6A) regulates cell cycle progression in diffuse midline glioma (DMG) and confers sensitivity to FTO inhibition

Diffuse midline gliomas (DMG) are deadly pediatric brain cancers with limited treatment options. These tumors likely arise from oligodendrocyte precursor cells (OPC) that acquire a driver histone mutation, leading to an aberrant epigenome. RNA N6-methyladenosine (m6A) is a vital epi-transcriptomic modification that regulates RNA processes and plays a significant role in OPC development through its regulation of transcripts involved in histone modification processes. Despite this pivotal role in OPC biology, the epi-transcriptome has not yet been investigated in DMG, and its interrogation may uncover new therapeutic options and understanding of this disease. Therefore, for the first time, we generated base-resolution m6A landscapes for patient-derived DMG cultures and found that DMG exhibits elevated m6A levels compared to non-neoplastic patient cells, with particularly strong enrichment on transcripts involved in cell motility and migration. In contrast, the minority of transcripts that have lower levels of m6A in DMG were associated with cell cycle regulation, especially components of chromosome segregation machinery. We also demonstrate that DMG is sensitive to inhibition of the m6A demethylase FTO, with FB23-2 treatment resulting in decreased proliferation, reduced survival, and pronounced S-phase arrest/stress, accompanied by robust induction of CDKN1A, GADD45B, and TFRC. Furthermore, FTO inhibition led to significant downregulation of key cell cycle regulators at both the transcriptomic and proteomic levels. Collectively, these findings highlight RNA methylation as a critical regulator of DMG tumorigenicity and identify FTO as a promising therapeutic target for this currently incurable disease.