Co-treatment of betulin and gefitinib is effective against EGFR wild-type/KRAS-mutant non-small cell lung cancer by inducing ferroptosis

Wei-Ya Yan, Jian Cai, Jiang-Nan Wang,  Yong-Sheng Gong,  Xue-Bing Ding

Abstract:

Clinical trials suggest that non-small-cell lung cancer (NSCLC) patients with KRAS mutations and wild-type EGFR have reduced benefits from gefitinib treatment. Ferroptosis is a new form of cell death that plays an important role in mediating the sensitivity of EGFR-TIKs. Here, we explored the antitumor ability of gefitinib in combination with betulin to overcome drug resistance through ferroptosis in wild-type EGFR/KRAS-mutant NSCLC cells. A549 and H460 cells were treated with gefitinib and betulin, and cell viability, apoptosis, and migration ability were assessed using the CCK-8 assay, flow cytometry, and wound-healing assay, respectively. Several cell death inhibitors were used to study the form of cell death. Ferroptosis-related events were detected by performing reactive oxygen species (ROS) and iron level detection, malondialdehyde (MDA) assay, and glutathione (GSH) assay. EMT-associated proteins and ferroptosis-related proteins were detected by using western blotting. A xenograft model was constructed in vivo to investigate the role of the combination treatment of betulin and gefitinib in NSCLC tumor growth. Gefitinib in combination with betulin exhibited antagonistic effects on cellular viability and induced cell apoptosis. It also induced ROS accumulation, lipid peroxidation, and GSH depletion and induced ferroptosis-related gene expression. Moreover, ferroptosis inhibitors, but not inhibitors of other forms of cell death, abrogated the effect of gefitinib in combination with betulin. Moreover, it also inhibited the tumor growth of NSCLC in vivo. Our findings suggest that gefitinib in combination with betulin is a novel therapeutic approach to overcome gefitinib resistance in EGFR wild-type/KRAS-mutant NSCLC cells by inducing ferroptosis.