P13K/Akt通路在药物放射增敏中作用的机制

目的 进一步探讨PI3K/Akt信号转导途径在药物放射增敏中作用的分子机制.方法 体外培养HeLa细胞,多西紫杉醇(docetaxel)和顺铂(cisplatin)单独及分别联合P13K抑制剂LY294002作用24 h,X线6 Gy剂量照射;Western blot检测Akt、磷酸化Akt(pAkt)、Bad、磷酸化Bad(pBad)蛋白的表达变化;RT-PCR检测Bad、Ku70、Ku80 mR-NA的表达变化;中性彗星电泳检测不同处理组细胞DNA的损伤.结果 ①docetaxel+LY294002联合照射组、cispla-tin+LY294002联合照射组Bad mRNA表达增高,Ku70 mRNA表达减低,Ku80 mRNA表达无明显变化;②docetaxel+LY294002联合照射组、cisplatin+LY294002联合照射组Bad蛋白表达增高,pAkt、pBad蛋白表达减低,Akt蛋白表达无明显变化;③docetaxel+LY294002联合照射组、cisplatin+LY294002联合照射组细胞彗星电泳尾距明显长于单纯药物增敏照射组.结论 ①docetaxel和cisplatin药物增敏照射能够明显活化PI3K/Akt信号转导途径;②抑制PI3K/Akt信号转导途径能够抑制Ku70表达,减少细胞DNA损伤后的再修复,提高促凋亡因子Bad的表达,促进细胞的凋亡.

The Role of PI3K/Akt Pathway in Radiosensitization of HeLa Cells

Objective To further explore the biologic mechanism of the role of PI3K/Akt pathway in radiosensitization of HeLa cells. Methods The HeLa cells were cultured in vitro. Using the IC_(20) of cisplatin and docetaxel in HeLa or combined with LY294002,the cells were radiated by X-ray. The protein expression of pAkt,Akt,Bad and pBad was detected by Western blot,and the mRNA expression of Bad,Ku70 and Ku80 by RT-PCR. The DNA damages were detected by neutro-comet electro-phoresis. Results ①The expression level of Bad mRNA in LY294002 + docetaxel/cisplatin group was higher,and that of Ku-70 mRNA was lower,but there was no significant change in Ku-70 mRNA expression. ②The expression level of Bad protein in LY294002 + docetaxel/cisplatin group was higher,and that of pBad and pAkt protein was lower, but there was no significant changes in the Akt protein expression. ③The comet electrophoresis tail distance in docetaxel+cisplatin+LY294002 group was longer than docetaxel + cisplatin group. Conclusion The radiosensitization of docetaxel and cisplatin could activate the PI3K/ Akt pathway. Inhibiting PI3K/Akt pathway may increase radiosensitization of HeLa cells by inhibiting Ku70 to suppress the DNA recovery,and enhancing the expression of Bad to promote cell apoptosis.