Acquired Resistance to Temozolomide in Glioma Cell Lines: Molecular Mechanisms and Potential Translational Applications
Acquired Resistance to Temozolomide in Glioma Cell Lines: Molecular Mechanisms and Potential Translational Applications
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DOI：
10.1159/000306139
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发表时间：
2010-01-01
期刊：
影响因子：
3.5
通讯作者：
Bradshaw, Tracey D.
中科院分区：
文献类型：
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作者：
Zhang, Jihong;Stevens, Malcolm F. G.;Bradshaw, Tracey D.
多形性胶质母细胞瘤的治疗包括烷化剂替莫唑胺联合电离辐射。在o6 -甲基鸟嘌呤甲基转移酶阴性的肿瘤中，替莫唑胺持续的o6 -鸟嘌呤甲基化导致DNA错配修复识别的细胞毒性病变，引发细胞凋亡。耐药性（内在或获得性）是替莫唑胺成功治疗的障碍，限制了药物疗效和预期寿命。两种胶质瘤细胞系SNB19和U373对替莫唑胺敏感（GI（50）值分别为36和68 μ M），暴露于增加替莫唑胺浓度（1-100 μ M）。产生获得性替莫唑胺耐药的变异细胞株SNB19VR、U373VR （GI（50）分别为280和289 μ M）。仅在U373VR细胞中观察到对米佐洛胺的交叉耐药。在克隆性和MTT实验中，使用o6 -苄基鸟嘌呤去除甲基鸟嘌呤甲基转移酶（MGMT）使U373VR细胞对替莫唑胺敏感，表明耐药机制涉及MGMT重新表达。事实上，Western blot分析显示细胞裂解物中存在MGMT蛋白。在SNB19VR细胞中，下调MSH6信息和蛋白表达可能赋予替莫唑胺耐受性。抑制poly（adp -核糖）聚合酶-1（关键碱基切除修复（BER）酶）部分恢复敏感性，DNA修复基因阵列显示在SNB19VR细胞中BER基因NTL1上调（>5倍）。总之，我们已经开发了两种胶质瘤细胞系，它们对替莫唑胺的获得性耐药机制不同，涉及MGMT的表达，或DNA错配修复失活和BER酶的募集，与临床观察一致。这些细胞系为开发对抗替莫唑胺耐药性的策略提供了有价值的模型。版权所有：S. Karger AG，巴塞尔
Treatment for glioblastoma multiforme includes the alkylating agent temozolomide combined with ionizing radiation. Persistent O6-guanine methylation by temozolomide in O6-methylguanine methyl transferase negative tumors causes cytotoxic lesions recognized by DNA mismatch repair, triggering apoptosis. Resistance (intrinsic or acquired) presents obstacles to successful temozolomide treatment, limiting drug efficacy and life expectancy. Two glioma cell lines, SNB19 and U373, sensitive to temozolomide (GI(50) values 36 and 68 mu M, respectively) were exposed to increasing temozolomide concentrations (1-100 mu M). Variant cell lines (SNB19VR, U373VR) were generated that displayed acquired temozolomide resistance (GI(50) values 280 and 289 mu M, respectively). Cross-resistance to mitozolomide was observed in U373VR cells only. In clonogenic and MTT assays, methylguanine methyltransferase (MGMT) depletion using O6-benzylguanine sensitized U373VR cells to temozolomide, indicating the resistance mechanism involves MGMT re-expression. Indeed, Western blot analyses revealed MGMT protein in cell lysates. In SNB19VR cells, down-regulation of MSH6 message and protein expression may confer temozolomide tolerance. Inhibition of poly(ADP-ribose) polymerase-1 (a key base excision repair (BER) enzyme) partially restored sensitivity, and DNA repair gene arrays demonstrated up-regulation (>5-fold) of BER gene NTL1 in SNB19VR cells. In conclusion, we have developed two glioma cell lines whose distinct mechanisms of acquired resistance to temozolomide, involving expression of MGMT, or inactivation of DNA mismatch repair and recruitment of BER enzymes, are consistent with clinical observations. These cell lines provide valuable models for the development of strategies to combat temozolomide resistance. Copyright (C) 2010 S. Karger AG, Basel