METTL3 Confers Oxaliplatin Resistance Through the Activation of G6PD-enhanced Pentose Phosphate Pathway in Hepatocellular Carcinoma
Oxaliplatin-based therapeutics is a widely used treatment approach for hepatocellular carcinoma (HCC) patients; however, drug resistance poses a significant clinical challenge. Epigenetic modifications have been implicated in the development of drug resistance. In our study, employing siRNA library screening, we identified that silencing the m6A writer METTL3 significantly enhanced the sensitivity to oxaliplatin in both in vivo and in vitro HCC models. Further investigations through combined RNA-seq and non-targeted metabolomics analysis revealed that silencing METTL3 impeded the pentose phosphate pathway (PPP), leading to a reduction in NADPH and nucleotide precursors. This disruption induced DNA damage, decreased DNA synthesis, and ultimately resulted in cell cycle arrest. Mechanistically, METTL3 was found to modify E3 ligase TRIM21 near the 3'UTR with N6-methyladenosine, leading to reduced RNA stability upon recognition by YTHDF2. TRIM21, in turn, facilitated the degradation of the rate-limiting enzyme of PPP, G6PD, through the ubiquitination-proteasome pathway. Importantly, high expression of METTL3 was significantly associated with adverse prognosis and oxaliplatin resistance in HCC patients. Notably, treatment with the specific METTL3 inhibitor, STM2457, significantly improved the efficacy of oxaliplatin. These findings underscore the critical role of the METTL3/TRIM21/G6PD axis in driving oxaliplatin resistance and present a promising strategy to overcome chemoresistance in HCC. Overall design: To investigate the effect of METTL3 on HCC cells, the total RNA of Huh7 stable cell-lines transfected with shNC or shMETTL3 lentivirus were subjected to RNA-seq.