中华医学杂志（英文版）2009，Vol.122Issue(11)：1255-1259,5.DOI:10.3760/cma.j.issn.0366-6999.2009.11.004
Glioblastoma stem cells resistant to temozolomide-induced autophagy
Glioblastoma stem cells resistant to temozolomide-induced autophagy
摘要
Abstract
Background Recent studies have demonstrated the existence of a small fraction of cells with features of primitive neural progenitor cells and tumor-initiating function in brain tumors. These cells might represent primary therapeutic target for complete eradication of the tumors. This study aimed to determine the resistant phenotype of glioblastoma stem cells (GSCs) to temozolomide (TMZ) and to explore the possible molecular mechanisms underlying TMZ resistance.Methods Freshly resected glioblastoma specimen was collected and magnetic isolation of GSCs was carded out using the Miltenyi Biotec CD133 Celt isolation kit. The cytotoxic effect of TMZ on CD133+ and CD133- glioblastoma cells was determined by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Autophagy-related proteins (Beclin-1, LC3 and Atg5) and cleaved caspase-3 (p17) were analyzed by Westem blotting. Immunofluorescent staining was used to detect Atg5, glial fibrillary acidic protein (GFAP) and CD133 expression in glioblastoma cells. Statistical analysis was carried out using SPSS 10.0 software. For all tests, the level of statistical significance was set at P <0.05.Results CD133+ glioblastoma cells exhibited neurosphere-like growth in vitro and high expression of CD133 stem cell marker. The growth-inhibiting rate in CD133- glioblastoma cells treated with 5 or 50 pmol/L TMZ was significantly higher than that in CD133+ glioblastoma cells ((14.36±3.75)% vs (2.54±1.36)% or (25.95±5.25)% vs (2.72±1.84)%, respectively, P <0.05). Atg5, LC3-ll and Beclin-1 levels were significantly lower in CD133+ glioblastoma cells than those in autologous CD133- cells after TMZ treatment (P <0.05). Caspase-3 was mildly activated only in CD133- glioblastoma cells after exposure to TMZ (P <0.05). Immunofluorescent staining revealed elevated expression of Atg5 in GFAP* cells following TMZ treatment.Conclusions The GSCs display strong capability of tumor's resistance to TMZ. This resistance is probably contributed by the CD133+ cells with down-regulation of autophagy-related proteins. Future treatment should target this small population of cancer stem cells in tumors to improve survival of patients.关键词
glioblastoma/ neoplastic stem cells/ chemoresistance/ temozolomideKey words
glioblastoma/ neoplastic stem cells/ chemoresistance/ temozolomide分类
医药卫生引用本文复制引用
FU Jun,LIU Zhi-gang,LIU Xiao-mei,CHEN Fu-rong,SHI Hong-liu,PANG Jesse Chung-sean,NG Ho-keung,CHEN Zhong-ping..Glioblastoma stem cells resistant to temozolomide-induced autophagy[J].中华医学杂志（英文版）,2009,122(11):1255-1259,5.基金项目
This study was supported by a grant from National Natural Science Foundation of China (No.30772551). （No.30772551）
