U251源性脑肿瘤干细胞的耐药性及耐药酶的表达

背景与目的：从胶质瘤中分离的肿瘤干细胞（cancer stem cells,CSCs）是胶质瘤的种子细胞和复发的源泉,它们不能被有效的杀死导致胶质瘤的预后不理想。本研究旨在探讨胶质瘤来源的肿瘤干细胞对化疗药物的耐药性及相关耐药酶的表达。方法：用免疫磁珠法从U251细胞中分选肿瘤干细胞（U251-CSC）后继续培养;MTT比色试验法观察化疗药物替尼泊苷（Vm-26）、卡莫司汀（BCNU）和顺铂（DDP）对U251和U251-CSC的增殖抑制作用,流式细胞仪检测3种化疗药物引起的细胞凋亡;Western blot免疫印迹法检测3种耐药酶LRP、MGMT和TopoⅡα的表达。结果：在3种药物作用下,U251的生长抑制比U251-CSC明显,U251的细胞凋亡率高于U251-CSC;U251-CSC表达LRP、MGMT和TopoⅡα的强度高于U251。结论：胶质瘤肿瘤干细胞对化疗药物Vm-26、BCNU和DDP有高耐药性,原因可能是肿瘤干细胞高表达耐药酶LRP、MGMT和TopoⅡα。

Drug resistance and expression of drug-resistance enzymes in brain cancer stem cells isolated from U251 cell lines

Background and purpose: Cancer stem cells (CSCs) isolated from human glioma are cancer-initiating cells and sources of tumor recurrence in brain tumors. The poor outcome of glioma is because cancer stem cells can not be eradicated. This article was aimed to explore the resistance of CSCs to chemotherapeutic agents and expression of drug-resistance enzymes in glioma cancer stem cells. Methods: Cancer stem cells from U251 were isolated by using magnetic sorting. The proliferation inhibitory effects of Vumon-26 (Vm-26), bischloronitrosourea (BCNU) and diamminedichloroplatinum (DDP) on U251-CSC and U251 were examined by drug sensitivity testing in vitro (MTT assay) and the apoptosis rates were observed by flow cytometry. Western blot was performed to examine the expression of three drug-resistance enzymes including LRP, MGMT and Topo Ⅱα. Results: Chemotherapeutic agents had a more obvious inhibitory effect on U251 than U251-CSC, as well as higher apoptosis rates. LRP, MGMT and Topo Ⅱα expression were significantly higher in U251-CSC as compared to U251, Conclusion: Glioma stem cells showed strong capability of tumor's resistance to chemotherapeutic agents including Vm-26, BCNU and DDP. This resistance is probably contributed by the CD133 positive cell with higher expression of on LRP, MGMT and Topo Ⅱα.