17 beta-estradiol hydroxylation catalyzed by human cytochrome P450 1B1
17 beta-estradiol hydroxylation catalyzed by human cytochrome P450 1B1
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DOI：
10.1073/pnas.93.18.9776
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发表时间：
1996-09-03
影响因子：
11.1
通讯作者：
Sutter, TR
中科院分区：
文献类型：
--
作者：
Hayes, CL;Spink, DC;Sutter, TR
17β-雌二醇的4-羟基代谢物(E(2))与这种激素的致癌作用有关。以往的研究表明，芳烃受体激动剂诱导细胞色素P450催化E(2)的4-羟基化。该活性与人P450 1b1相关。为了确定人P4501b1基因产物与E(2)4-羟基化的关系，在酿酒酵母中表达了该蛋白。转化酵母的微粒体能催化E(2)的4-羟基化和2-羟基化，K-m值分别为0.71和0.78mU/M，转化率分别为1.39和0.27nmoL产物min(-1)。NmolP450(-1)。用芳烃受体配体吲哚[3，2-b]咔唑处理MCF-7人乳腺癌细胞后，P450 1b1和P450 1A1的mRNA水平呈浓度依赖性增加，并导致E(2)的2-、4-、6-α和15α-羟化速率增加。在E(2)浓度为10 nM时，2-羟化和40-羟化的增加速率大致相同，强调了E(2)代谢的低K-mP450 1b1组分的重要性。这些研究表明，人P4501b1是一种催化高效的E(2)4-羟基酶，可能参与内分泌调节和雌激素的毒性。
The 4-hydroxy metabolite of 17 beta-estradiol (E(2)) has been implicated in the carcinogenicity of this hormone. Previous studies showed that aryl hydrocarbon-receptor agonists induced a cytochrome P450 that catalyzed the 4-hydroxylation of E(2). This activity was associated with human P450 1B1. To determine the relationship of the human P450 1B1 gene product and E(2) 4-hydroxylation, the protein was expressed in Saccharomyces cerevisiae. Microsomes from the transformed yeast catalyzed the 4- and 2-hydroxylation of E(2) with K-m values of 0.71 and 0.78 mu M and turnover numbers of 1.39 and 0.27 nmol product min(-1). nmol P450(-1), respectively. Treatment of MCF-7 human breast cancer cells with the aryl hydrocarbon-receptor ligand indolo[3,2-b]carbazole resulted in a concentration-dependent increase in P450 1B1 and P450 1A1 mRNA levels, and caused increased rates of 2-, 4-, 6 alpha-, and 15 alpha-hydroxylation of E(2). At an E(2) concentration of 10 nM, the increased rates of 2- and 40-hydroxylation were approximately equal, emphasizing the significance of the low K-m P450 1B1-component of E(2) metabolism. These studies demonstrate that human P450 1B1 is a catalytically efficient E(2) 4-hydroxylase that is likely to participate in endocrine regulation and the toxicity of estrogens.