EIF4E promotes gefitinib resistance in non-small cell lung cancer by activating the Wnt/β-catenin pathway

Tyrosine kinase inhibitors (TKIs) like gefitinib, which target the epidermal growth factor receptor (EGFR), show considerable therapeutic effectiveness in non-small cell lung cancer (NSCLC) with EGFR-activating mutations. Nevertheless, the resistance that develops against EGFR-TKIs diminishes their therapeutic impact in clinical settings. This investigation focused on the impact of eukaryotic translation initiation factor 4E (eIF4E) on gefitinib resistance in NSCLC. Using the CCK-8 assay, the influence of different gefitinib concentrations on cell proliferation was examined. eIF4E and EGFR expressions were verified by qRT-PCR and/or western blotting in NSCLC cell lines. Moreover, the effects of eIF4E knockdown in gefitinib-treated PC9/GR cells were detected by CCK-8, flow cytometry, colony formation assays, and xenograft tumor model. eIF4E expression was remarkably upregulated in the gefitinib-resistant PC9/GR cells. Moreover, the expression levels of eIF4E in NSCLC cell lines exhibited a dose-dependent increase following gefitinib administration. The function assays demonstrated that reducing eIF4E levels hindered the proliferation of PC9/GR cells and enhanced the apoptosis-inducing effects of gefitinib both in vitro and in vivo, and also had an inhibitory action on the Wnt/β-catenin pathway. Taken together, these results suggested that eIF4E confers gefitinib resistance in NSCLC by regulating the Wnt/β-catenin pathway. Therefore, eIF4E is a possible therapeutic target for improving therapeutic action in NSCLC patients who have developed resistance to gefitinib.