Cytochrome P450 isofonns catalyze formation of catechol estrogen quinones that react with DNA
Cytochrome P450 isofonns catalyze formation of catechol estrogen quinones that react with DNA
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DOI：
10.1016/j.metabol.2007.03.001
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发表时间：
2007-07-01
影响因子：
9.8
通讯作者：
Rogan, Eleanor G.
中科院分区：
文献类型：
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作者：
Zhang, Yan;Gaikwad, Nilesh W.;Rogan, Eleanor G.
越来越多的证据表明，雌激素的特定代谢产物，即儿茶酚、雌激素、苯二酚，与DNA反应形成加合物并产生无嘌呤位点，这可能导致导致乳腺癌的突变。雌二醇(E-2)氧化产生2种儿茶酚类雌激素，其中主要代谢产物是4-羟基雌二醇(4-OHE2)和2-羟基雌二醇(2-OHE2)。它们被氧化成苯二酚，E-2-3，4-苯二酚(E-2-3，4-Q)和E-2-2，3-Q，可以与DNA反应。在肝外组织中，E_2氧化为2-OHE_2主要由细胞色素P450(CYP)1A1和CYP3A4催化，而在肝外组织中E_2氧化为4-OHE_2主要由细胞色素P450(CYP)1A1和部分细胞色素P3A催化。然而，CYP异构体在儿茶酚进一步氧化为半喹酮和苯二酚的过程中的潜在参与还没有详细的研究。本研究利用不同的重组人细胞色素P450亚型，即细胞色素P4501A1、细胞色素P1B1和细胞色素P3A4，将儿茶酚类雌激素2-OHE2和4-OHE2氧化成相应的雌激素醌，然后与DNA发生反应，以确定不同的细胞色素P450在将儿茶酚类雌激素氧化为苯二酚的过程中的潜在功能。用超高效液相色谱/串联质谱法分别在不同反应体系中观察到纯化加合物2-OHE2-6-N3Ade、4-OHE2-1-N3de和4-OHE2-1-N7Gua。此外，在这些反应中检测到的雌激素-谷胱甘肽(GSH)结合物水平要高出100多倍。当使用对照微体时，观察到谷胱甘肽偶联物的数量要少得多。当E2-3，4-Q与CYP1B1或对照微粒体反应30min时，得到去尿加合物和GSH结合物，进一步证明这些重组酶制剂中存在GSH。这些实验证明，CYP1A1、CYP1B1和CYP3A4能够将邻苯二酚类雌激素氧化为各自的苯二酚，这可以进一步与GSH、蛋白质和DNA反应，最后导致净化加合物，从而导致突变。(C)2007 Elsevier Inc.保留所有权利。
Accumulating evidence suggests that specific metabolites of estrogens, namely, catechol estrogen quinones, react with DNA to form adducts and generate apurinic sites, which can lead to the mutations that induce breast cancer. Oxidation of estradiol (E-2) produces 2 catechol estrogens, 4-hydroxyestradiol (4-OHE2) and 2-OHE2 among the major metabolites. These, in turn, are oxidized to the quinones, E-2-3, 4-quinone (E-2-3,4-Q) and E-2-2,3-Q, which can react with DNA. Oxidation of E2 to 2-OHE2 is mainly catalyzed by cytochrome P450 (CYP)1A1, and CYP3A4, whereas oxidation of E2 to 4-OHE2 in extrahepatic tissues is mainly catalyzed by CYP1B1 as well as some CYP3As. The potential involvement of CYP isoforms in the further oxidation of catechols to semiquinones and quinones has, however, not been investigated in detail. In this project, to identify the potential function of various CYPs in oxidizing catechol estrogens to quinones, we used different recombinant human CYP isoforms, namely, CYP1A1, CYP1B1, and CYP3A4, with the scope of oxidizing the catechol estrogens 2-OHE2 and 4-OHE2 to their respective estrogen quinones, which then reacted with DNA. The depurinating adducts 2-OHE2-6-N3Ade, 4-OHE2-1-N3de, and 4-OHE2-1-N7Gua were observed in the respective reaction systems by ultraperformance liquid chromatography/tandem mass spectrometry. Furthermore, more than 100-fold higher levels of estrogen-glutathione (GSH) conjugates were detected in the reactions. Glutathione conjugates were observed, in much smaller amounts, when control microsomes were used. Depurinating adducts, as well as GSH conjugates, were obtained when E2-3,4-Q was incubated with CYP1B1 or control microsomes in a 30-minute reaction, further demonstrating that GSH is present in these recombinant enzyme preparations. These experiments demonstrated that CYP1A1, CYP1B1, and CYP3A4 are able to oxidize catechol estrogens to their respective quinones, which can further react with GSH, protein, and DNA, the last resulting in depurinating adducts that can lead to mutagenesis. (c) 2007 Elsevier Inc. All rights reserved.