The effect of elemene on lung adenocarcinoma A549 cell radiosensitivity and elucidation of its mechanism

OBJECTIVE: To investigate the effect of elemene on the radiosensitivity of A549 cells and its possible molecular mechanism. METHODS: Apoptosis of A549 cells was detected by flow cytometry and fluorescence microscopy. The effect of double-strand break (DSB) damage repair in A549 cells was evaluated using the neutral comet assay. Protein expression levels were detected using western blotting, and the correlation between protein levels was analyzed. RESULTS: Elemene exhibited a radiosensitizing effect on A549 cells. The level of apoptosis induced by elemene combined with radiation was significantly greater (p<0.01) than that elicited by either radiation or elemene alone. Following radiation and subsequent repair for 24 h, the tail intensity of A549 cells treated with a combination of elemene and radiation was greater than that of cells treated with either elemene or radiation alone (p<0.01). This result indicates that elemene inhibits cellular DSB repair. Both elemene combined with radiation and radiation alone decreased the protein expression of DNA-PKcs and Bcl-2 compared to elemene alone (p<0.01), while p53 protein expression was increased (p<0.01). A negative correlation was observed between DNA-PKcs and p53 expression (r=−0.569, p=0.040), while a positive correlation was found between DNA-PKcs and Bcl-2 expression (r=0.755, p=0.012). CONCLUSIONS: Elemene exhibits a radiosensitizing effect on A549 cells, and its underlying molecular mechanism of action may be related to the downregulation of DNA-PKcs gene expression.