METTL3-m6A-EGFR-axis drives lenvatinib resistance in hepatocellular carcinoma.

Lenvatinib is emerging as the first-line therapeutic option for advanced hepatocellular carcinoma (HCC), but drug resistance remains a major hurdle for its long-term therapy efficiency in clinic. N6-methyladenosine (m6A) is the most abundant mRNA modification. Here, we aimed to investigate the modulatory effects and underlying mechanisms of m6A in lenvatinib resistance in HCC. Our data revealed that m6A mRNA modification was significantly upregulated in the HCC lenvatinib resistance (HCC-LR) cells compared to parental cells. Methyltransferase-like 3 (METTL3) was the most significantly upregulated protein among the m6A regulators. Either genetic or pharmacological inhibition of m6A methylation through METTL3 deactivation in primary resistant cell line MHCC97H and acquired resistant Huh7-LR cells decreased cell proliferation and increased cell apoptosis upon lenvatinib treatment in vitro and in vivo. In addition, the specific METTL3 inhibitor STM2457 improved tumor response to lenvatinib in multiple mouse HCC models, including subcutaneous, orthotopic and hydrodynamic models. The MeRIP-seq results showed that epidermal growth factor receptor (EGFR) was a downstream target of METTL3. EGFR overexpression abrogated the METTL3 knocked down-induced cell growth arrest upon lenvatinib treatment in HCC-LR cells. Thus, we concluded that targeting METTL3 using specific inhibitor STM2457 improved the sensitivity to lenvatinib in vitro and in vivo, indicating that METTL3 may be a potential therapeutic target to overcome lenvatinib resistance in HCC.