Abstract B015: RNA N6-methyladenosine (m6A) as a therapeutic target in Diffuse Midline Glioma (DMG)

Abstract Diffuse Midline Glioma (DMG) is an incurable pediatric brain tumor thought to originate from oligodendrocyte precursor cells in midline brain structures. The RNA modification N6-methyladenosine (m6A) plays an important role in RNA stability and is critical to neuronal stem-cell self-renewal and differentiation. We therefore sought to investigate m6A as a therapeutic target in DMG. Moreover, targeting the epitranscriptome has shown promise in the treatment of other cancers, and several small-molecule inhibitors of m6A writers and erasers have been recently developed. To that end, we tested the sensitivity of a panel of patient-derived DMG cell lines to FB23-2, an inhibitor of the m6A eraser FTO, and STM2457, an inhibitor of the mRNA m6A writer METTL3. In order to interrogate the therapeutic mechanisms and identify predictive biomarkers for response, we then performed RNA-seq to measure gene expression changes, and native RNA-seq to measure RNA m6A levels. We found that DMG cell lines were more sensitive to FB23-2 (IC50 ~10μM) than STM2457 (IC50 ~100μM), indicating that m6A gain rather than loss may be a potential therapeutic strategy. Furthermore, we observed variation in FB23-2 sensitivity between cell lines with RNA-sequencing identifying marked changes in the expression of cell cycle, cell stress response, and differentiation associated genes in the cell lines which responded best to FB23-2. Additionally, these analyses also identified several potential biomarkers for response to FB23-2. Finally, we generated the first m6A transcriptome maps for DMG using native RNA sequencing and demonstrated that m6A is abundant in DMG cell lines and is particularly enriched on cell cycle, cell stress response, and metabolic pathway transcripts. Overall, our work identified the FTO m6A demethylase as a potential therapeutic target in DMG, whereby its inhibition with FB23-2 increases m6A abundance, altering the stability of critical transcripts and pathways. Citation Format: Samuel E. Ross, Holly Holliday, Maria Tsoli, David S. Ziegler, Marcel E. Dinger. RNA N6-methyladenosine (m6A) as a therapeutic target in Diffuse Midline Glioma (DMG) abstract. In: Proceedings of the AACR Special Conference on Brain Cancer; 2023 Oct 19-22; Minneapolis, Minnesota. Philadelphia (PA): AACR; Cancer Res 2024;84 (5 Suppl₁): Abstract nr B015.