Evidence for nucleotide excision repair as a modifying factor of O-6-methylguanine-DNA methyltransferase-mediated innate chloroethylnitrosourea resistance in human tumor cell lines
Evidence for nucleotide excision repair as a modifying factor of O-6-methylguanine-DNA methyltransferase-mediated innate chloroethylnitrosourea resistance in human tumor cell lines
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DOI：
10.1124/mol.52.5.815
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发表时间：
1997-11-01
影响因子：
3.6
通讯作者：
Panasci, LC
中科院分区：
文献类型：
--
作者：
Chen, ZP;Malapetsa, A;Panasci, LC
我们检测了14个未经氯乙基亚硝脲(CENU)抗性筛选的人肿瘤细胞系的O-6-甲基鸟嘌呤-DNA甲基转移酶(MGMT)蛋白、MGMT活性水平和切除修复交叉互补啮齿动物修复缺陷基因ERCC2(XPD)的蛋白水平。并与1，3-双-(2-氯乙基)-1-亚硝脲(BCNU)的细胞毒性和紫外光敏感度进行了比较。MGMT蛋白与MGMT活性呈显著正相关(r=0.9497，p=0.0001)。免疫印迹分析(r=0.139，p=0.6348)和活性测定(r=0.131，p=0.6515)均未发现BCNU的细胞毒性与MGMT含量呈显著的线性相关。然而，富含mgmt的细胞株比mgmt缺乏的细胞株对紫外光更具抵抗力(t=2.2375，p=0.0225)，但对紫外线的抗性不强(f=1.1734，p=0.1317)。此外，对BCNU最敏感的细胞系都是MGMT缺乏的。紫外光敏感性与BCNU细胞毒性呈显著正相关(r=0.858，p=0.0001)。BCNU细胞毒性(r=0.786，p=0.0009)和紫外线敏感性(r=0.874，p=0.0001)与ERCC2蛋白水平呈显著正相关。我们的结果证实了MGMT在CENU抗性中起重要作用，但在UV抗性中不起作用。紫外线敏感性与BCNU细胞毒性的相关性表明，核苷酸切除修复是MGMT介导的人肿瘤细胞系，特别是高耐药细胞系天然CENU耐药性的重要修饰因素。ERCC2可能参与这一过程。
We examined the O-6-methylguanine-DNA methyltransferase (MGMT) protein as well as MGMT activity levels and the excision repair cross-complementing rodent repair deficiency gene, ERCC2 (XPD), protein levels in 14 human tumor cell lines not selected for chloroethylnitrosourea (CENU) resistance. These results were compared with 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU) cytotoxicity and UV light sensitivity. MGMT protein correlated significantly with MGMT activity (r = 0.9497, p = 0.0001). There was no significant linear correlation between BCNU cytotoxicity and MGMT content as determined by both Western analysis (r = 0.139, p = 0.6348) and activity assay (r = 0.131, p = 0.6515). However, MGMT-rich cell lines were found to be more resistant than MGMT-poor cell lines to BCNU (t = 2.2375, p = 0.0225) but not to UV (f = 1.1734, p = 0.1317). Furthermore, the most BCNU-sensitive cell lines were all MGMT-poor. UV sensitivity was significantly correlated to BCNU cytotoxicity (r = 0.858, p = 0.0001). Significant correlations were found between ERCC2 protein levels and BCNU cytotoxicity (r = 0.786, p = 0.0009) or UV sensitivity (r = 0.874, p = 0.0001). Our results confirm that MGMT plays an important role in CENU resistance, but not in UV resistance. The correlation of UV sensitivity with BCNU cytotoxicity suggests that nucleotide excision repair is an important modifying factor of MGMT-mediated innate CENU resistance in human tumor cell lines, especially in highly resistant cell lines. ERCC2 may be implicated in this process.