Increasing the DNA damage threshold in breast cancer cells.
Increasing the DNA damage threshold in breast cancer cells.
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提高乳腺癌细胞中的 DNA 损伤阈值。
DOI：
10.1006/taap.2002.9391
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发表时间：
2002
影响因子：
3.8
通讯作者：
Brueggemeier,RobertW
中科院分区：
文献类型：
--
作者：
Mobley,JamesA;Brueggemeier,RobertW
雌激素在雌激素依赖型乳腺癌发生发展中的生化作用尚不清楚，雌激素在肿瘤发生中的作用仍存在争议。有关雌激素介导的DNA损伤的报道包括在体外和体内诱导8-氧-2‘-脱氧鸟苷(8-oxo-DG)，表明氧化应激在肿瘤的启动和/或进展中发挥作用。然而，DNA分离、细胞DNA修复和高抗氧化状态使得在体内和细胞培养中测定8-oxo-DG具有一定的挑战性。在这一点上，可以通过耗尽细胞中储存的谷胱甘肽来增强DNA损伤。为了研究雌激素对乳腺癌细胞的损伤作用，我们选择用γ-谷氨酰半胱氨酸氨基转移酶抑制剂丁硫氨酸亚硫胺去除雌激素受体阳性的乳腺癌细胞株中的谷胱甘肽。用10μM2-OH-E2或4-OH-E2处理谷胱甘肽缺乏的MCF-7细胞30min，8-oxo-dG/105dG分别增加127和160%。在邻苯二酚雌激素诱导的DNA损伤中加入氯化铜，对2-OH-E2和4-OH-E2的DNA损伤分别增加165%和200%。此外，100 nM和1.0μM雌二醇以剂量-反应方式分别使DNA损伤增加145%和189%。用BSO耗尽GSH可能被证明是研究细胞DNA损伤的一种有利技术，否则抵抗氧化应激和/或烷化剂，并已被证明在雌激素诱导的DNA氧化损伤的研究中具有高度的重复性和敏感性。
The biochemical role of estrogens in the development of estrogen-dependent breast cancer remains to be elucidated, and the involvement of estrogens in tumor initiation remains controversial. Reports regarding estrogen-mediated DNA damage include the induction of 8-oxo-2′-deoxyguanosine (8-oxo-dG) in vitro and in vivo, indicating a role for oxidative stress in tumor initiation and/or progression. However, DNA isolation, cellular DNA repair, and high antioxidant status have made the measurement of 8-oxo-dG in vivo and in cell culture somewhat challenging. In this regard, a potentiation in DNA damage can be achieved by depleting cellular stores of glutathione. We chose to deplete glutathione in the estrogen receptor (ER)-positive MCF-7 breast cancer cell line with a γ-glutamylcysteine transpeptidase enzyme inhibitor buthionine sulphoximine (BSO) for the purpose of studying estrogen-induced DNA damage. Treatment of GSH-depleted MCF-7 cells with 10 μM 2-OH-E2or 4-OH-E2for 30 min resulted in a statistically significant increase in 8-oxo-dG/105dG of 127 and 160%, respectively. A potentiation in catechol estrogen-induced DNA damage was observed with the addition of copper(II) chloride for both 2-OH-E2and 4-OH-E2by 165 and 200%, respectively. In addition, 100 nM and 1.0 μM estradiol increased DNA damage in a dose–response-like fashion by 145 and 189%, respectively. The depletion of GSH by BSO may prove to be an advantageous technique for the study of DNA damage in cells otherwise resistant to oxidative stress and/or alkylating agents and has proven useful in the study of estrogen-induced oxidative DNA damage in a highly reproducible and sensitive manner.