CONTRIBUTION OF O-6-METHYLGUANINE-DNA METHYLTRANSFERASE TO MONOFUNCTIONAL ALKYLATING-AGENT RESISTANCE IN HUMAN BRAIN TUMOR-DERIVED CELL-LINES
CONTRIBUTION OF O-6-METHYLGUANINE-DNA METHYLTRANSFERASE TO MONOFUNCTIONAL ALKYLATING-AGENT RESISTANCE IN HUMAN BRAIN TUMOR-DERIVED CELL-LINES
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DOI：
10.1002/mc.2940130203
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发表时间：
1995-06-01
影响因子：
4.6
通讯作者：
SILBER, JR
中科院分区：
文献类型：
--
作者：
BOBOLA, MS;BLANK, A;SILBER, JR
DNA 修复蛋白 O-6-甲基鸟嘌呤-DNA 甲基转移酶 (MGMT) 与人类脑肿瘤对烷化剂的耐药性有关。我们观察到 14 种人髓母细胞瘤和神经胶质瘤来源的细胞系对甲基化剂 N-甲基-N'-硝基-N-亚硝基胍 (MNNG) 的敏感性不同，如 10% 存活剂量 (LD(10)) 下的 28 倍范围所示。通过使用底物类似物抑制剂 O-6-苄基鸟嘌呤 (O-6-BG)，我们发现 MGMT 对耐药性的贡献差异很大，各品系之间的 LD(10) 降低了 3 至 30 倍，并且各个品系亚群之间的差异高达 26 倍。重要的是，在消除可测量的 MCMT 后，耐药性的变异性（表现为 LD(10) 的 20 倍范围）仍然存在，揭示了其他耐药机制对生存的不同贡献。悬浮在生长培养基中时暴露于 MNNG 的细胞比烷基化为亚汇合单层的细胞具有更强的抵抗力，并且 MGMT 在其抵抗力中所占比例较小。值得注意的是，品系的 MGMT 含量与 MNNG 抗性或 O-6-BG 的杀伤增强作用没有统计相关性，尽管 MGMT 是生化证明的抗性决定因素。相比之下，相同的品系对乙基化剂 N-乙基亚硝基脲 (ENU) 的抗性变化较小，并且 MCMT 对抗性的贡献很小。我们的结果强烈表明，对 MNNG 和 ENU 的耐药性是多因素的。 (C) 1995 Wiley-Liss, Inc.
The DNA repair protein O-6-methylguanine-DNA methyltransferase (MGMT) has been implicated in resistance of human brain tumors to alkylating agents. We observed that 14 human medulloblastoma- and glioma-derived cell lines differ in sensitivity to the methylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), as shown by their 28-fold range in 10% survival dose (LD(10)). By using the substrate analogue inhibitor O-6-benzylguanine (O-6-BG), we showed that the contribution of MGMT to resistance varies widely, as evidenced by 3- to 30-fold reductions in LD(10) among the lines, and varies up to 26-fold among subpopulations of individual lines. Importantly, variability in resistance, manifested as a 20-fold range in LD(10), persists after measurable MCMT is eliminated, disclosing differential contributions of other resistance mechanisms to survival. Cells exposed to MNNG while suspended in growth medium are more resistant than cells alkylated as subconfluent monolayers, and MGMT accounts for a smaller proportion of their resistance. Notably, the MGMT content of the lines is not statistically correlated with MNNG resistance or with potentiation of killing by O-6-BG, even though MGMT is a biochemically demonstrated determinant of resistance. In contrast, the same lines vary less in resistance to the ethylating agent N-ethylnitrosourea (ENU), and MCMT makes only a small contribution to resistance. Our results strongly indicate that resistance to both MNNG and ENU is multifactorial. (C) 1995 Wiley-Liss, Inc.