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 cells 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 simultaneous PX/TRAIL treatment also exhibited weak inhibition on GSCs growth without synergy. However,combined sequential PX/TRAIL treatment showed a synergistic effect and achieved favorable inhibition on GSCs both at low concentrations. 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 mechanisms of PX/TRAIL synergy were related to upregulation of death receptor ( DR ) - 4, caspase - 8 and caspase - 3, but not DR5 and cytochrome c. Conclusion: PX can sensitize GSCs to TRAIL through extrinsic pathway of cell apoptosis by upregulation of DR4,caspase -8 and caspase -3. These results suggest that combined sequential PX/TRAIL treatment may be promising in glioma chemotherapy.%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.
展开▼
