β-Elemene Radiosensitizes Lung Cancer A549 Cells by Enhancing DNA Damage and Inhibiting DNA Repair

β‐Elemene is a broad‐spectrum antitumor agent. In China, several studies have indicated that β‐elemene enhances the cytotoxic effect of radiation in vitro and in vivo. In this study, the alkaline comet assay and neutral comet assay were used to measure both DNA strand breaks and DNA repair activity in A549 cells exposed to β‐elemene, irradiation or combination treatment. The overall object of the study was to test whether β‐elemene radiosensitization is associated with an enhancement in radiation‐induced DNA damage or with a decrease in the repair of radiation‐induced damage. The results revealed high levels of DNA single strand breaks (SSB) and double strand breaks (DSB) in A549 cells after exposure to the combination of β‐elemene and irradiation. To assess SSB and DSB repair, alkaline comet assay and neutral comet assay were performed at 24 h postirradiation. The damage induced by the combination of β‐elemene and irradiation was repaired at a slower rate. These findings suggest that β‐elemene can enhance A549 cell radiosensitivity through the enhancement of DNA damage and the suppression of DNA repair. Copyright © 2011 John Wiley & Sons, Ltd.