中文摘要：

目的 研究乙醇对人乳腺癌MCF-7细胞放射敏感性的影响及相关机制。方法 将人乳腺癌MCF-7细胞分为4组,对照组（不做任何处理）、乙醇组（乙醇处理）、单纯照射组（6 Gy X射线处理）和联合组（乙醇与X射线联合作用）。克隆形成法检测50或100 mmol/L乙醇对MCF-7细胞放射敏感性的影响;流式细胞术检测细胞周期变化;Annexin V-FITC法检测细胞凋亡。结果 50和100 mmol/L乙醇处理MCF-7细胞50 h,对生长无明显影响（t=0.82和1.15,P〉0.05）;乙醇预处理2 h,可明显增加X射线照射后MCF-7细胞克隆形成的能力（t=4.15和10.28,P〈0.05）。相比于单纯照射组,乙醇降低了X射线照射诱导的细胞G2/M期阻滞（t=7.18,P〈0.05）,以及sub-G1峰的比例（t=5.39,P〈0.05）。而且,Annexin V-FITC检测结果示,乙醇联合X射线照射的细胞晚期和早期凋亡减少（t=4.86和7.59,P〈0.05）。结论 乙醇可以增加MCF-7细胞的辐射抗性,其机制可能与降低辐射诱导的细胞G2/M期阻滞及早、晚期凋亡的发生相关。

英文摘要：

Objective To investigate the effect of ethanol on radiosensitivity of human breast cancer MCF-7 cells. Methods Human breast cancer MCF-7 cells were divided into four groups including control group, ethanol treatment group, X-ray exposed group, and ethanol combined with X-ray group. Clonogenic assay was used to determine cell survival. Flow cytometry was employed to analyze cell cycle progression. Annexin V-FITC kit was used to determine cell apoptosis induction. Results Ethanol（50 and 100 mmol/L,50 h）had no influence on MCF-7 cell growth（t=0.82,1.15,P〉0.05）. The radiosensitivity of MCF-7 cells was reduced when the cells were pretreated with 50 mmol/L ethanol （t=4.15,P〈0.05） and 100 mmol/L ethanol（t=10.28,P〈0.05）for 2 h. Compared with irradiation with X-ray alone, ethanol treatment decreased G2/M phase arrest（t=7.18,P〈0.05） and sub-G1 population（an indicator of apoptosis induction）（t=5.39,P〈0.05）. A decrease of advanced and early apoptosis in the cells pretreated with ethanol was also confirmed by Annexin V-FITC apoptosis assay（t=4.86,7.59,P〈0.05）. Conclusions Ethanol causes radioresistance in human breast cancer MCF-7 cells, where the decreases of radiation-induced G2/M phase arrest and apoptosis may be involved.