Radiosensitization Effect Study Of Elemene On Human Lung Adenocarcinoma A549 Cell Line In Vitro Experiment

Objective To explore the radiosensitizing effect of Elemene on human lung adenocarcinoma A549 cell line and its underlying mechanism. Offering new ideas and methods for radiosensitizing treatment of lung cancer.Methods (1) Human lung adenocarcinoma A549 cell line was cultured in vitro, periodically exchanged of medium and passaged to maintain good cell growth. (2) The growth inhibiting effects of different concentrations of Elemene on A549 cells at different times was measured by MTT colorimetric test (MTT method). 10% inhibitory concentration (IC10) was calculated by LOGIT method with IC software after A549 cells were exposed to Elemene for 24h. The concentration closed to IC10 in 24 hours was used on radiosensitizing effect research lest toxic effects of drugs. (3) Each group (the control group and combination radio exposure group) placed in different doses of 0, 2Gy, 4Gy, 6Gy, 8Gy, 10Gy X-ray radiation, then culture 14 days and the radiosensitizing effect of Elemene on A549 cells was observed by colony-forming method. The mathematic model of one-hit multi-target was used to fit radiation dose-cell survival curve, and calculate the average lethal dose (D₀),quasi-threshold dose (Dq) and other relevant parameters. (4) The cell cycle and apoptosis changes of A549 line were observed by flow cytometry analysis after Elemene managed 24h. (5) The protein expression of Bcl-2, Bax, Survivin and VEGF was observed by immunocytochemistry after A549 cells were exposed to Elemene for 24h. (6) The data was analysised by SPSS 17.0 statistical package, using single-factor analysis of variance.Results (1) The proliferation of human lung adenocarcinoma A549 cell line was inhibited significantly by Elemene. With the increase of the concentration effect, the cell proliferation inhibition rate increased;with the role of time extented, the cell inhibition rate was increased as well. The inhibition was dose- and time-dependent manner. (2) The survival curve of Elemene combined radiation group to the left, D₀ reduced and Dq diminished, showing that the radiation sensitivity of A549 cell was increased. (3) The flow cytometry analysis displayed: the distribution of cell cycle can be affected by Elemene, A549 cells were exposed to Elemene for 24h, G₂/M phase fraction was higher significantly, while the S-phase fraction which resistanced to radiation was decreased significantly and apoptosis rate increased. (4) A549 cells were exposed to Elemene for 24h, the expression of Bax protein which promote apoptosis increased at the same time cytoplasm coloration accentuation. Bcl-2 protein which inhibit apoptosis expression decreased and cytoplasm coloration declined. Proliferin Survivin and VEGF expressed all descended, furthermore they all correlated with drug concentration.Conclusions (1) Human lung adenocarcinoma A549 cell line was inhibited significantly by Elemene in a concentration-dependent and time-dependent maner. (2) Elemene has radiosensitization effect in a low concentration. (3) The sensitizing mechanisms of Elemene may be related to that cell cycle was blocked in G₂/M phase and up-regulated the expression of apoptosis-related protein then apoptosis induced.