A Study On Radiosensitivity Of β-elemene To Cervical Cancer Of HeLa Cell Line In Vitro

Radiotherapy is a very important way to treat the cervical cancer. But the result ofradiotherapy is not satisfactory because of the biological features and the localmicroenvironment of the tumor. In order to improve the raidotheraputic effect, people tryto search for more effective radiosensitization agents for cervical cancer..In recent years, people find that some Traditional Chinese Medicine have theradiosensitizing effect. β-elemene is used as a non-cytotoxicity anti-tumor drug, it is a kindof floristics new anti-cancer drugs extracted from common turmeric. It has been showedthat β-elemene is a broad-spectrum and relatively safe agent to be applied to treat the tumor.Researching of its function mechanism of radiosensitization was mainly aboutproliferation、apoptosis and differentiation, the study on its new effect target is rare.We exposed HeLa cells in low-cytotoxic concentrations, then observed theradiosensitive effects on HeLa cells in vitro and investigated the mechanism ofradiosensitization. It could be a new thought for clinical study and provide study methodfor Chinese traditional radiationsensitizing agents.Objective: This study aims to evaluate the influence of β-elemene to human Cervicalcancer HeLa cells on radiosensitization and to investigate that if there is correlationbetween radiosensitization and the expression level of CDK1, cyclin B1, bcl-2and P53gene.Method: Taking HeLa cells as the research object, Cells were cultured in commonRPMI-1640culture medium. The test groups were exposed to the culture medium atdifferent concentrations of β-elemene (0μg/ml,10μg/ml,20μg/ml,40μg/ml,80μg/ml,160μg/ml,320μg/ml). The control group had no β-elemene in culture medium. Then theywere exposed to radiation at different dose of X-ray(0Gy,2Gy,4Gy,6Gy,8Gy,10Gy). Allindexes were detected after HeLa cells culture finished. Inhibiting rate on cell proliferationexposed to different concentrations was evaluated with a way of MTT assay, then calculate IC50of24h. Radiosensitivity of HeLa cells was observed with the methods of MTT assayand clone forming assay. The expression level of CDK1, cyclin B1, bcl-2and P53mRNAwere detected by Fluorescence quantitative Real-Time Polymerase ChainReaction(RT-PCR).Results:1. The24h IC50value to HeLa cells of β-elemene is112.6μg/ml. Along with theincreasing of β-elemene concentration, proliferation inhibition rate gradually increased.β-elemene is shown as possessing a proliferation inhibition effect in vitro inHeLa cells. Statistical analysis has significant difference (p<0.05).2. HeLa cells were exposed to β-elemene in different concentrations (30μg/ml,45μg/ml) for24h and radiated, The results indicate: at the same radiation dose, the groupof30μg/ml β-elemene combined radiotherapy decreased A570nm value relative to thesimple radiotherapy group. Statistical analysis between groups has significant difference (P<0.05). β-elemene is shown preliminarily as possessing a radiosensitizing effect in vitro inHeLa cells.3. HeLa cells were exposed to β-elemene in the concentrations (30μg/ml、45μg/ml)cultured for24h and radiated, then were measured the number of cell clone and survivalrate. Compared to the control group, there was significant difference between30μg/mlgroup and45μg/ml group,(p<0.05), there was also significant difference between30μg/mlgroup and45μg/ml group (p<0.05). Survival rate results indicate that the radiosensitivity ofHeLa cells can be enhanced by β-elemene, radiosensitization effect increased graduallywith the increased concentration of β-elemene.4. HeLa cells were exposed to β-elemene in the concentrations30μg/ml and45μg/mlcultured for24h and48h, The expression of CDK1, Cyclin B1, the bcl-2and p53mRNAwere measured by RT-PCR. Results show that the β-elemene can slightly down-regulatedCyclin B1and bcl-2, up-regulated p53. The effect had a positive correlation with the timeand dose.Conclusion:1. β-elemene could significantly inhibit the proliferation of HeLa cells, the IC50, IC20and IC10is112.6μg/ml,45.34μg/ml and29.56μg/ml, respectively. the proliferationinhibition rate increased along with increasing concentration of β-elemene.2The radiosensitization of HeLa cells can be enhanced by β-elemene, radiosensitization effect increased gradually with the prolongation of the action time andincreasing of concentration.3. HeLa cells were exposed to β-elemene could down-regulate Cyclin B1and bcl-2,up-regulated p53. It suggested that the radiotherapy sensitization mechanism of β-elemenemay be through cell cycle arrest, induction of apoptosis effect so as to have the effect ofradiotherapy sensitization. The detailed mechanism remains to be further developed.