Epitranscriptomic and Epigenetic Engineering as Novel Therapeutic Approaches in Glioma

Glioma is the most common form of primary brain cancer and suffers from a paucity of efficacious therapies. Decades of research have successfully characterized glioma subtypes based on genetic, epigenetic, and molecular signatures that act as important prognostic indicators. Here, we present two novel approaches to designing therapeutics that convert malignant glioma and glioblastoma subtypes into more treatment-amenable subtypes. We first describe how the IDH1mut → D-2-HG ⊣ FTO axis establishes a unique epitranscriptomic profile that we term G-RAMP, which results in reduced tumor cell proliferation in both patient tumor samples and patient-derived gliomaspheres via inhibition of the anti-apoptotic regulator ATF5. G-RAMP was characterized using MeRIP-Seq unbiased screening of N6-methyladenosine (m6A) enrichment sites in IDH1mut gliomas, and small molecule inhibitors of FTO were employed to recapitulate IDH1mut growth phenotypes in more malignant IDH1wt lines. Our second approach utilized dCas9-DNMT3a epigenetic editing platforms to induce high-density methylation of the MGMT promoter and exon 1 region. MGMT methylation is a positive prognostic indicator in gliomas that predicts patient tumor responses to the standard-of-care antineoplastic agent temozolomide. We demonstrate that unmethylated MGMT gliomas can be converted to exhibit MGMT methylated profiles, which results in decreased expression of MGMT and enhanced sensitivity to temozolomide. The utilization of epitranscriptomic and epigenetic engineering approaches thus represent two novel means of effecting subtype conversions in glioma that demonstrate promising potential as neoadjuvant therapies