Enhanced γ-glutamylcysteine synthetase activity decreases drug-induced oxidative stress levels and cytotoxicity
Enhanced γ-glutamylcysteine synthetase activity decreases drug-induced oxidative stress levels and cytotoxicity
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DOI：
10.1002/mc.20184
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发表时间：
2006-09-01
影响因子：
4.6
通讯作者：
Boldogh, Istvan
中科院分区：
文献类型：
--
作者：
Das, Gokul C.;Bacsi, Attila;Boldogh, Istvan
癌细胞的多药耐药性可以是内在的或获得性的，并且由于各种原因而发生，包括基因毒性损伤的修复增加，去除/解毒化学试剂或活性氧（ROS）的能力增强，以及细胞凋亡的抑制。与亲本细胞系A2780相比，人A2780/100卵巢癌细胞表现出对DNA交联剂苯丁酸氮芥（Cbl）、顺铂（Cpl）、美法仑（Mel）和电离辐射（IR）的抗性。在本研究中，我们表明，当A2780/100和A2780细胞与Cbl处理，GSH被挤出通过蛋氨酸或胱硫醚可降解的完整质膜转运。GSH损失后，ROS水平迅速增加。在Cbl添加后4-6小时内，抗性但非药物敏感的细胞使细胞内GSH浓度沿着与ROS水平正常化，并且在药物处理后存活。A2780/100细胞中GSH和ROS水平的正常化与γ-谷氨酰半胱氨酸合成酶（γ-GCS）活性升高（A2780细胞的10 +/- 1.8倍）密切相关。药物敏感细胞中γ-GCS重亚基的异位过表达几乎使GSH和ROS恢复到治疗前水平，从而增加了细胞对遗传毒性剂（Cbl、Cpl和IR）的抗性，而γ-GCS轻亚基的过表达没有这种作用。因此，在我们的模型系统中，耐药细胞具有维持增加的γ-GCS活性、重建生理GISH和细胞氧化还原状态以及维持增加的细胞对DNA交联剂和IR的抗性的固有能力。
Multidrug resistance of cancer cells can be intrinsic or acquired and occurs due to various reasons, including increased repair of genotoxic damage, an enhanced ability to remove/detoxify chemical agents, or reactive oxygen species (ROS), and repression of apoptosis. Human A2780/1 00 ovarian carcinoma cells exhibit resistance to DNA crosslinking agents, chlorambucil (Cbl), cisplatin (Cpl), melphalan (Mel), and ionizing radiation (IR) compared to the parental cell line, A2780. In the present study, we show that when A2780/1 00 and A2780 cells were treated with Cbl, GSH was extruded via methionine or cystathionine-inhibitable transporters of intact plasma membrane. GSH loss was followed by a rapid increase in ROS levels. The resistant, but not drug-sensitive cells normalized the intracellular GSH concentration along with ROS levels within 4-6 h after Cbl addition, and survived drug treatment. Normalization of GSH and ROS levels in A2780/100 cells correlated well with elevated gamma-glutamylcysteine synthetase (gamma-GCS) activity (10 +/- 1.8-fold over A2780 cells). Ectopic overexpression of the gamma-GCS heavy subunit in drug-sensitive cells nearly restored GSH and ROS to pre-treatment levels consequently increased cellular resistance to genotoxic agents (Cbl, Cpl, and IR), while overexpression of gamma-GCS light subunit had no such effects. Thus, in our model system, drug-resistant cells have the inherent ability to maintain increased gamma-GCS activity, reestablish physiological GISH, and cellular redox state and maintain increased cellular resistance to DNA cross-linking agents and IR. (c) 2006 Wiley-Liss, Inc.