OBJECTIVETo study radiation-enhancing effects on human gastric cancer MKN28 cell line and underlying mechanisms of β-elemene.

METHODSInhibition of MKN28 cell proliferation at different concentrations of β-elemene was assessed using the methyl thiazolyl blue colorimetric method (MTT method), with calculation of IC50 value and choice of 20% of the IC50 as the experimental drug concentration. Irradiation group and β-elemene+irradiation group were established, and the cell survival fraction (SF) was calculated from flat panel colony forming analysis, and fitted by the 'multitarget click mathematical model'. Draw the survival curve and get the radiobiological parameters D0, Dq, SF2, N and SER. Flow cytometry (FCM) was used to detect changes in the cell cycle and cell apoptosis rates was detected by Annexin-V/PI assay.

RESULTSβ-elemene exerted inhibitory effects on proliferation of gastric cancer MKN28 cells, with an IC50 of 45.6 mg/L and we chose 8 mg/L as the experimental concentration. The cell survival fraction of MKN28 cells with irradiation decreased significantly after treated with β-elemene; D0, Dq decreased, SER = 1.3. After combined treatment of β-elemene+irradiation, the results of FCM showed that cells could be arrested in the G2/M phase and the cell apoptosis increased significantly.

CONCLUSIONSβ-elemene can enhance the radiosensitivity of gastric cancer MKN28 cell line. Mechanistically, β-elemene mainly influences the cell cycle distribution of MKN28 cells by inducing G2/M phase arrest, inhibits the repair of sublethal damage and induces cell apoptosis to enhance the killing effects of radioactive rays.