中文摘要：

目的 研究渥曼青霉素（wortmannin,WM）对恶性胶质瘤的辐射增敏作用及机制.方法 采用10 μmol/L WM预处理人胶质瘤细胞U251 2 h,并给予10 Gy X射线照射,检测细胞周期及凋亡的变化；通过Western blot和免疫荧光染色方法检测蛋白共剂失调-毛细血管扩张症突变基因（ATM）及其靶基因,以及DNA依赖蛋白激酶的催化亚单位（DNA-PKcs）的表达和功能的变化.结果 WM预处理联合X射线照射（WM＋ IR）组,U251细胞的凋亡率由对照组和IR组的（5.3±0.66）％和（11.5±2.0）％增高到（21.8±2.4）％,各组间差异具有统计学意义（F=57.38,P＜0.05）.在IR组和WM＋ IR组中,伴随着凋亡率的增加,凋亡基因cleaved caspase-3的表达明显高于对照组（q=12.49、19.19,P＜0.05）,且WM＋ IR组较IR组增高更为明显（q =6.70,P＜0.05）.与对照组比较,细胞周期检测IR组G2/M期细胞明显增多（q =9.67,P＜0.05）,WM＋ IR组进一步增加（q =21.25,P＜0.05）,出现明显的G2/M期阻滞.同时,WM有效抑制了X射线诱导的ATM蛋白激酶的磷酸化及其下游基因p53和SMC1的活化,并且抑制射线诱导的DNA-PKcs表达,而增加了DSB标记物phospho-γ-H2A.X（Ser139）的表达.结论 WM通过下调ATM激酶和DNA-PK蛋白的活性来增强恶性胶质瘤细胞的辐射敏感性.

英文摘要：

Objective To study the mechanism of wortmannin （WM） in enhancing radiosensitivity of malignant glioma cells.Methods Human glioma cells （U251） were pretreated with 10 μmol/L WM for 2 h and then irradiated with 10 Gy X-rays.The changes of cell cycle and apoptosis ratio were examined.Western Blot and immunofluorescence staining were used to detect the expression and function of ATM and its target genes as well as DNA-PKcs.Results The ratio of apoptotic cells in the WM combined with X-ray treatment group （WM ＋ IR） was increased from （5.3 ± 0.66） ％ of control group and （11.5 ± 2.0） ％ of IR group to （21.8 ± 2.4） ％ significantly （F =57.38,P ＜ 0.05）.Along with the increase of apoptosis,the expression of cleave-caspase-3 was significantly increased in IR or WM ＋ IR group compared to control group （q =12.49,19.19,P ＜ 0.05）,and its enhancement in WM ＋ IR group was more significant than that in IR group （q =6.70,P ＜ 0.05）.Compared to control group,the cell cycle assay showed that the amount of U251 cells in G2/M phase was increased in IR group （q =9.67,P ＜ 0.05）,and further increased in WM ＋ IR group （q =21.25,P ＜ 0.05）,indicating an obvious G2/M phase arrest.Moreover,WM could effectively inhibit the phosphorylation of ATM kinase and the activity of ATM downstream target genes of p53 and SMC1.WM also suppressed the IR-induced expressions of DNAPKcs and phospho-γH2AX （Ser139）.Conclusions WM effectively increased the radiation sensitivity of malignant glioma cells through down-regulating the activity of ATM kinase and DNA-PK.