紫杉醇在TRAIL诱导脑胶质瘤干细胞凋亡中的增敏作用研究

Paclitaxel increases sensitivity of glioma stem cells to apoptosis induced by TRAIL in vitro

目的:探讨体外试验中紫杉醇(PX)能否增强胶质瘤干细胞(GSCs)对肿瘤坏死因子相关凋亡诱导配体(TRAIL)诱导细胞凋亡的敏感性及其可能的机制。方法:悬浮培养法从U87细胞中培养出GSCs并鉴定。MTT法检测不同浓度的单药PX组、单药TRAIL组和PX与TRAIL联合给药组及序贯给药组对GSCs的抑制作用;流式细胞法检测不同给药方案对GSCs凋亡的影响,Western blot法检测细胞凋亡级联反应的相关蛋白表达变化。结果:TRAIL与PX对GSCs的增殖抑制作用均较低。两药同时联合应用未见协同作用;若PX与TRAIL先后序贯给药则出现协同作用(CDI=0.80)。与单独用药组相比,PX与TRAIL序贯给药可显著提高GSCs的凋亡率(P<0.001),提示PX可提高GSCs对TRAIL的敏感性。蛋白检测发现死亡受体(DR)4、半胱天冬酶(caspase)8和3表达明显上调(P<0.01)。结论:PX与TRAIL序贯给药后PX可能上调DR4的表达,提高GSCs对TRAIL的敏感性,并激活外源性凋亡途径caspase-8及caspase-3诱导细胞凋亡。PX与TRAIL序贯用药对GSCs有一定的诱导凋亡作用。

Objective：To investigate the chemosensitive effect of paclitaxel （PX） on apoptosis induced by tumor necrosis factor- related apoptosis -inducing ligand （TRAIL） in glioma stem cells （GSCs） derived from U87 cells, and the possible mechanisms. Methods：GSCs were cultured from human glioblastoma cell line U87 cells using serum - free stem cell media and identified by both biological behaviors and markers. PX/TRAIL in combination or alone at different concentrations were used to treat GSCs in vitro, and their effects on ceils were detected by MTT and flow cy- tometry. Proteins of the related apoptosis signaling cascade were measured using Western blot assay. Results： Neither TRAIL nor PX alone markedly inhibited GSCs growth in vitro, even at very high concentrations. Combined simultane- ous PX/TRAIL treatment also exhibited weak inhibition on GSCs growth without synergy. However, combined sequen- tial PX/TRAIL treatment showed a synergistic effect and achieved favorable inhibition on GSCs both at low concentra- tions. Remarkably higher apoptosis rate of GSCs was induced by combined sequential PX/TRAIL treatment compared with using each drug alone or combined simultaneous PX/TRAIL treatment. Protein assays revealed that the mecha- nisms of PX/TRAIL synergy were related to upregulation of death receptor （DR） -.4, caspase - 8 and caspase - 3, but not DR5 and cytoehrome e. Conclusion ： PX can sensitize GSCs to TRAIL through extrinsic pathway of cell apop- tosis by upregulation of DR4, easpase - 8 and easpase - 3. These results suggest that combined sequential PX/TRAIL treatment may be promising in glioma chemotherapy.