METTL1/WDR4-mediated m ⁷ G Hypermethylation of SCLT1 mRNA Promotes Gefitinib Resistance in Non-small Cell Lung Cancer

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have produced durable complete responses, but the eventual development of acquired resistance presents a huge challenge in the treatment of non-small cell lung cancer (NSCLC). N7-methylguanosine (m ⁷ G), a prevalent post-transcriptional modification within RNA, play regulatory roles in RNA stability, expression dynamics, and functional diversity. Despite these insights, the contribution of m ⁷ G methylation to EGFR-TKIs resistance remains poorly characterized. Here, we identified substantial upregulation of mRNA internal m ⁷ G modifications and their associated methyltransferase complex composed of methyltransferase-like 1 (METTL1) /WD repeat domain 4 (WDR4) were significantly elevated in NSCLC specimens, correlating with therapeutic resistance. Functional assays confirmed that METTL1/WDR4 enhances gefitinib resistance in both cellular and animal models via the internal RNA m ⁷ G methyltransferase activity in NSCLC. Mechanistically, m ⁷ G MeRIP-seq coupled with RNA-seq identified sodium channel and clathrin linker 1 (SCLT1) as the m ⁷ G target of METTL1/WDR4. METTL1/WDR4 knockdown may result in a decrease in both the demethylation level and mRNA stability of the SCLT1 transcript, while overexpression of wild-type METTL1, but not its catalytically inactive mutant, rescues mRNA stability. METTL1/WDR4-mediated m ⁷ G modification of SCLT1 regulates gefitinib resistance by activating the NF-κB signaling. These results establish aberrant mRNA internal m ⁷ G modification as a novel resistance mechanism and propose therapeutic targeting of the METTL1/WDR4-SCLT1-NF-κB axis cascade to overcome EGFR-TKIs resistance.