Site specificity and mechanism of oxidative DNA damage induced by carcinogenic catechol
Site specificity and mechanism of oxidative DNA damage induced by carcinogenic catechol
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DOI：
10.1093/carcin/22.8.1239
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发表时间：
2001-08-01
期刊：
影响因子：
4.7
通讯作者：
Kawanishi, S
中科院分区：
文献类型：
--
作者：
Oikawa, S;Hirosawa, I;Kawanishi, S
邻苯二酚是一种天然存在的重要化工原料，具有强烈的促癌活性，可诱发啮齿类动物腺胃肿瘤。此外，儿茶酚。是致癌物质苯的主要代谢物。为了阐明儿茶酚的致癌机制，我们使用人培养细胞系和从人p53和p16肿瘤抑制基因和c-Ha-ras-l原癌基因获得的P-32标记的DNA片段来研究DNA损伤。儿茶酚增加了人白血病细胞系HL-60中8-氧代7，8-二氢-2 ′-脱氧鸟苷（8-oxodG）的量，已知8-oxodG与癌症的发病率相关，而其抗过氧化氢（H2 O2）克隆HP 100中8-oxodG的量没有增加。在Cu ~（2+）存在下，邻苯二酚能促进小牛胸腺DNA中8-oxodG的形成。在Cu ~（2+）存在下，邻苯二酚对P ~（32）标记的DNA片段造成损伤。当加入NADH时，DNA损伤显著增强，并且在相对低浓度的儿茶酚（< 1 μ M）下清楚地观察到。哌啶处理增强了DNA切割，表明儿茶酚加NADH不仅引起脱氧核糖磷酸骨架断裂，而且碱基修饰。儿茶酚加NADH经常修饰胸腺嘧啶残基。铜离子特异性螯合剂浴铜灵和过氧化氢酶可抑制DNA损伤，表明Cu+和H2 O2参与了DNA损伤。典型的羟自由基清除剂不能抑制儿茶酚加Cu ~（2+）引起的DNA损伤，而蛋氨酸则完全抑制了这种损伤，表明H_2O_2与Cu ~（2+）反应产生的活性物质参与了儿茶酚引起的DNA损伤。因此，我们认为邻苯二酚通过产生H_2O_2氧化DNA损伤在邻苯二酚和苯的致癌过程中起重要作用。
Catechol, a naturally occurring and an important industrial chemical, has been shown to have strong promotion activity and induce glandular stomach tumors in rodents. In addition, catechol. is a major metabolite of carcinogenic benzene. To clarify the carcinogenic mechanism of catechol, we investigated DNA damage using human cultured cell lines and P-32-labeled DNA fragments obtained from the human p53 and p16 tumor suppressor genes and the c-Ha-ras-l proto-oncogene. Catechol increased the amount of 8-oxo7,8-dihydro-2 ' -deoxyguanosine (8-oxodG), which is known to be correlated with the incidence of cancer, in a human leukemia cell line HL-60, whereas the amount of 8-oxodG in its hydrogen peroxide (H2O2)-resistant clone HP100 was not increased. The formation of 8-oxodG in calf thymus DNA was increased by catechol in the presence of Cu2+. Catechol caused damage to P-32-labeled DNA fragments in the presence of Cu2+. When NADH was added, DNA damage was markedly enhanced and clearly observed at relatively low concentrations of catechol (< 1 muM). DNA cleavage was enhanced by piperidine treatment, suggesting that catechol plus NADH caused not only deoxyribose phosphate backbone breakage but also base modification. Catechol plus NADH frequently modified thymine residues. Bathocuproine, a specific Cu+ chelator and catalase inhibited the DNA damage, indicating the participation of Cu+ and H2O2 in DNA damage. Typical hydroxyl radical scavengers did not inhibit catechol plus Cu2+-induced DNA damage, whereas methional completely inhibited it. These results suggest that reactive species derived from the reaction of H2O2 with Cu I participates in catechol-induced DNA damage. Therefore, we conclude that oxidative DNA damage by catechol through the generation Of H2O2 plays an important role in the carcinogenic process of catechol and benzene.