Abstract
Despite initial dramatic efficacy of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR-TKIs) in EGFR-mutant lung cancer patients, subsequent emergence of acquired resistance is almost inevitable. Resveratrol and its derivatives have been found to exert some effects on EGFR-TKI resistance in non-small cell lung cancer (NSCLC), but the underlying mechanisms remain unclear. We screened several NSCLC cell lines with gefitinib resistance by MTT assay and analysed the miR-345/miR-498 expression levels. NSCLC cells were pre-treated with a resveratrol derivative, trans-3,5,4-trimethoxystilbene (TMS) and subsequently challenged with gefitinib treatment. The changes in apoptosis and miR-345/miR-498 expression were analysed by flow cytometry and q-PCR respectively. The functions of miR-345/miR-498 were verified by CCK-8 assay, cell cycle analysis, dual-luciferase reporter gene assay and immunoblotting analysis. Our results showed that the expression of miR-345 and miR-498 significantly decreased in gefitinib resistant NSCLC cells. TMS pre-treatment significantly upregulated the expression of miR-345 and miR-498 increasing the sensitivity of NSCLC cells to gefitinib and inducing apoptosis. MiR-345 and miR-498 were verified to inhibit proliferation by cell cycle arrest and regulate the MAPK/c-Fos and AKT/Bcl-2 signalling pathways by directly targeting MAPK1 and PIK3R1 respectively. The combination of TMS and gefitinib promoted apoptosis also by miR-345 and miR-498 targeting the MAPK/c-Fos and AKT/Bcl-2 signalling pathways. Our study demonstrated that TMS reduced gefitinib resistance in NSCLCs via suppression of the MAPK/Akt/Bcl-2 pathway by upregulation of miR-345/498. These findings would lay the theoretical basis for the future study of TMS for the treatment of EGFR-TKI resistance in NSCLCs.