Measurement of oxidative DNA damage by catechol estrogens and analogues in vitro.
Measurement of oxidative DNA damage by catechol estrogens and analogues in vitro.
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DOI：
10.1021/tx980128i
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发表时间：
1999-02
影响因子：
4.1
通讯作者：
J. Mobley;A. Bhat;R. Brueggemeier
中科院分区：
文献类型：
--
作者：
J. Mobley;A. Bhat;R. Brueggemeier
雌激素在激素依赖性肿瘤组织中的生长促进作用涉及已被广泛认可的受体介导的途径。然而，雌激素在肿瘤发生中的作用仍然存在争议。雌激素代谢物，主要是儿茶酚雌激素（CE），通过氧化还原循环机制参与肿瘤的发生。我们开发了代谢稳定的 CE 类似物，用于研究受体与氧化还原循环对 DNA 损伤的影响。对羟基雌二醇 (HE2's)、甲氧基雌二醇 (ME2's) 和羟甲基雌二醇 (HME2) 在电位测定和 DNA 损伤研究中进行了比较。使用 8-oxo-2'-脱氧鸟苷 (8-oxo-dG) 作为氧化应激的基因毒性标记物评估小牛胸腺 DNA 中的 DNA 损伤。 2-HE2 和 4-HE2 的 8-oxo-dG/10(5) dG 数量显着增加。 Cu(II)SO4 是一种已知能催化邻醌氧化还原循环的过渡金属，它大大增加了两种 CE 造成的 DNA 损伤量。然而，DNA 损伤仅在 10 µM 或更高的浓度下观察到，远大于生理条件下发现的损伤。此外，内源性抗氧化剂（如谷胱甘肽、SOD 和过氧化氢酶）的存在大大减少了高浓度 2-HE2 引起的 DNA 损伤。对于非氧化还原循环 HME2 没有观察到 DNA 损伤，这使得这些化合物成为研究受体介导的致癌作用的有用探针。因此，2-HE2和4-HE2都能够在体外以微摩尔浓度产生氧化DNA损伤。然而，由于CE的量在体内尚未显示超过纳摩尔水平，因此通过CE的氧化还原循环产生的自由基不太可能是人类肿瘤发生的致病因素。
The growth-promoting effects of estrogens in hormone-dependent tumor tissues involve receptor-mediated pathways that are well-recognized; however, the role of estrogens in tumor initiation remains controversial. Estrogen metabolites, primarily the catechol estrogens (CE's), have been implicated in tumor initiation via a redox cycling mechanism. We have developed metabolically stable CE analogues for the study of receptor versus redox cycling effects on DNA damage. Comparisons between hydroxy estradiols (HE2's), methoxy estradiols (ME2's), and hydroxymethyl estradiols (HME2) in potentiometric and DNA damaging studies were made. DNA damage was assessed in calf thymus DNA using 8-oxo-2'-deoxyguanosine (8-oxo-dG) as a genotoxic marker for oxidative stress. Increases in the number of 8-oxo-dG/10(5) dG were significant for each 2-HE2 and 4-HE2. Cu(II)SO4, a transition metal known to catalyze the redox cycling of o-quinones, substantially increased the amount of DNA damage caused by both CE's. However, DNA damage was only observed at concentrations of 10 microM or higher, much greater than what is found under physiologic conditions. Furthermore, the presence of endogenous antioxidants such as glutathione, SOD, and catalase drastically reduced the amount of DNA damage induced by high concentrations of 2-HE2. There was no DNA damage observed for the non-redox cycling HME2's, making these compounds useful probes in the study of receptor-mediated carcinogenesis. Thus, both 2-HE2 and 4-HE2 are capable of producing oxidative DNA damage at micromolar concentrations in vitro. However, since the amount of CE's has not been shown to surpass nanomolar levels in vivo, it is unlikely that free radical production via redox cycling of CE's is a causative factor in human tumorigenesis.