Abstract
The aim of the present study was to examine whether erastin influences radioresistance in non-small cell lung cancer (NSCLC) cells and produce a preliminary investigation into its mechanism of action. The radioresistant subtype of NSCLC cells, A549-R and H460-R, were induced by high-dose hypofractionated irradiation. Erastin was used to treat the radioresistant cells and radiosensitivity was examined by colony formation assays. Cell death was determined after the cells were treated with erastin, irradiation (IR) or erastin together with IR. The expression of glutathione peroxidase 4 (GPX4) expression in the parental cells and radioresistance cells was detected by western blotting. GPX4 expression in the radioresistance cells was subsequently inhibited, radiosensitivity and cell death was measured, and erastin enhanced radiosensitivity in A549-R and H460-R cells. Erastin and IR exhibited a combined effect on killing cells, as co-treatment with erastin and IR demonstrated a higher effect on killing cells compared with erastin or IR alone. GPX4 expression was inhibited by erastin in the radioresistant cells. Inhibiting GPX4 expression also radiosensitized NSCLC cells to radiation in the radioresistant cell lines. Erastin-induced and GPX4-inhibition-induced cell death could partially be rescued by deferoxamine, but not Z-VAD-FMK and olaparib, which indicated that erastin and GPX4-inhibition induced ferroptosis in the radioresistant cells. Erastin decreased radioresistance of NSCLC cells partially by inducing GPX4-mediated ferroptosis.