中文摘要：

目的 观察替莫唑胺（TMZ）诱导人脑胶质瘤U251耐药细胞株（U251/TR）经放射线照射后细胞周期及P-糖蛋白（P-gp）表达的改变.方法 逐步递增剂量诱导方法建立U251/TR细胞株,细胞计数试剂盒（CCK-8）法测定其药物敏感性;倒置显微镜观察亲本U251细胞及U251/TR两种细胞结晶紫染液染色后形态差异;医用直线加速器6 Gy剂量放射线照射两种细胞后观察细胞周期的变化;Western blot分析耐药蛋白细胞膜P-gp表达变化.结果 成功诱导建立人脑恶性胶质瘤U251耐药细胞株后,结晶紫染液染色显示显微镜下两种细胞存在形态学差异.CCK-8法检测显示U251/TR对TMZ、阿霉素、环磷酰胺、依托泊苷、硫酸长春新碱化疗药物的耐受指数分别为2.63、2.76、2.15、10.58、3.54.流式细胞术检测发现在同步化之后,经6Gy X线照射后6、24、48、72 h细胞周期各时比较,提示U251/TR细胞株较亲本细胞G2/M期明显减少,G0/G1期和S期明显增多.Western blot结果显示6 Gy放射线照射U251/TR和U251细胞后,P-gp的蛋白表达均下降（相对蛋白表达量分别为0.535±0.002、0.349±0.004）,说明6 Gy放射线对两种细胞均有杀伤作用.结论 经小剂量6Gy X线辐射照射可抑制甚至杀伤胶质瘤U251细胞及耐TMZ细胞U251/TR,一定剂量放疗后两种细胞放射敏感性均增高.

英文摘要：

Objective To investigate the cell cycle and P-glycoprotein expression changes of drugresistance cell lines of U251 induced by temozolomide （TMZ） after radiation exposure.Methods The U251 cells resistant to TMZ （U251/TR） were maked by increasing concentrations.The muhidrug resistance was detected by cell counting kit-8 （CCK-8）.Cell morphology of U251 and U251/TR was observed under optical microscope with crystal violet staining.We induced U251 parents and U251/TR cells used 6 Gy X-rays by linear accelerator.The flow cytometer was used to test the change of cells cycle after X-rays irradiation.Protein expression of P-glycoprotein （P-gp） was detected by using Western blotting.Results We were successful in inducing to establish a constant drug-resistace cell lines U251/TR by TMZ.Inverted microscope to observe morphology of the U251 and U251/TR were different after dyeing.CCK-8 method test showed that：the U251/TR to TMZ,doxorubicin,cyclophosphamide,etoposide,sulfuric acid vincristine chemotherapy drugs resistance index for parents of U251 respectively 2.63,2.76,2.15,10.58,3.54.The flow cytometric test showed the U251/TR cell lines of G2/M phase was decreased significantly than parent cell,but G0/G1 phase and S phase were increased obviously.Western blotting result analysis：the P-gp protein expression was decreased after exposure to 6 Gy X-ray irradiation （The relative quantity of protein expression,respectively was 0.535 ± 0.002,0.349 ± 0.004）.Conclusion Small doses X-ray （such as 6 Gy） radiation exposure to inhibit or even killing.Both U251 and U251/TR Cells were increased radiosensitivity after Right Dosage X-ray irradiation.