N6-methyladenosine promotes temozolomide resistance through non-canonical regulation of mRNA stability in glioblastoma cells

N6-methyladenosine (m6A) is a critical regulator of mRNA processing and function, impacting nearly every step of the mRNA lifecycle. Changes in m6A status have been implicated in many different types of cancer, including glioblastoma where acquired resistance to temozolomide remains a major clinical challenge. We established glioblastoma cell culture models of acquired temozolomide resistance and analyzed the role of m6A in controlling resistance-associated pathways. We show that m6A stabilizes key genes and pathways promoting temozolomide resistance in glioblastoma, including MGMT, the enzyme that repairs primary temzolomide-induced DNA damage, and PI3K/Akt signaling, a major driver of chemoresistance. Pharmacological inhibition of the m6A methyltransferase METTL3 destabilizes MGMT and other critical mRNAs, restoring temozolomide sensitivity. Collectively, our results suggest that genes associated with temozolomide resistance are stabilized by m6A methylation, even as the majority of the transcriptome remains subject to m6A-mediated mRNA decay. Moreover, these data highlight METTL3 inhibition as a promising therapeutic approach to overcoming temozolomide resistance in glioblastoma.