雷公藤甲素增敏替莫唑胺杀伤胶质瘤细胞的机制研究

Mechanism of synergistic cytotoxic effect of Triptolide with Temozolomide on glioma cells

目的探讨雷公藤甲素（TPL）对替莫唑胺（TMZ）杀伤胶质瘤细胞效应的影响及其可能机制。方法采用CCK一8法检测TPL与TMZ对胶质瘤细胞增殖的抑制效应，使用Chou—Talalay法评估TPL和TMZ的联合作用，流式细胞仪检测技术检测TPL和（或）TMZ作用后U87胶质瘤细胞的周期和凋亡的变化，以及应用Western blot技术检测TPL和（或）TMZ作用后U87胶质瘤细胞中IKBa、磷酸化IKBa、XIAP及Cleaved PARP表达的变化。结果TPL与TMZ作为单药均能够剂量依赖性的抑制胶质瘤细胞增殖；在U87细胞系中，TPL联合TMZ抑制U87细胞达IC50时联合指数（cI）为0．76，表明TPL与TMZ具有协同作用；TPL与TMZ联用处理U87细胞后，细胞凋亡比例显著多于单药用药组（t=14．474，P〈0．01；t=11．244，P〈0．01）；TPL与TMZ联用可抑制NF-κB信号转导通路中关键蛋白IKBa的磷酸化以及抗凋亡蛋白XIAP的表达。结论TPL在体外能够协同增加TMZ杀伤胶质瘤细胞的效应，其机制可能通过抑制NF-κB信号转导通路的活化，进一步诱导胶质瘤细胞凋亡所致。

Objective This study aimed to explore the effect of triptolide （TPL） on the efficiency of temozolomide （TMZ） in killing glioma cells and the possible mechanism. Methods CCK -8 assay was used to test the growth inhibition effect of TMZ and TPL against the glimoa cell. The combined effects of TPL and TMZ on glioma cells were calculated by Chou -Talalay method. Propidium iodide staining, Annexin V - FITC/PI staining, and Western - blot were used to detect the change of cell cycle, apoptosis, and its related protein treated by TPL and/or TMZ in glioma cells. Results TPL and TMZ reduced the growth rate of glioma cell line U87 in a dose - dependent manner. CI values of TPL and TMZ are less than 1, indicating the synergistic effect of the two agents. The apoptosis induced by combined TPL and TMZ was more significant than that by either single agent treatment group in U87 cells. Western blot analysis showed that TPL resulted in the down - regulation of anti - apoptotic protein XIAP and the dephosphorylation of IκBα a key component in NF -κB pathway. Conclusions TPL synergistically acted with TMZ to kill glioma cells. TPL enhanced the TMZ - induced apoptosis in glioma cells. Suppression of NF -κB pathway was the possible mechanism.