Association of CYP1A1 polymorphisms with differential metabolic activation of 17β-estradiol and estrone
Association of CYP1A1 polymorphisms with differential metabolic activation of 17β-estradiol and estrone
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DOI：
10.1158/0008-5472.can-04-3543
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发表时间：
2005-04-01
期刊：
影响因子：
11.2
通讯作者：
Schwarz, D
中科院分区：
文献类型：
--
作者：
Kisselev, P;Schunck, WH;Schwarz, D
一些流行病学研究将某些CYP 1A 1基因型单独或联合与雌激素相关癌症风险增加联系起来。为了回答CYP 1A 1对雌激素的基因型依赖性激活是否可能是潜在机制的问题，我们研究了人CYP 1A 1最常见的等位基因变体对两种内源性雌激素17 β-雌二醇（E2）和雌酮（El）的羟基化活性。我们表达并纯化了CYP1A1.1（野生型）、CYP1A1.2（Ile（462）瓦尔）和CYP1A1.4（Thr（461）Asn），并在重构的CYP 1A 1系统中进行了NADPH依赖性雌激素羟基化的酶促测定。所有CYP 1A 1变体都催化E2和E1形成2-、4-、6 α-和15 α-羟基化雌激素代谢物，但催化效率和区域特异性不同。而变体CYP1A1.2（Ile 462 Val）对所有羟基化位点和两种底物具有显著更高的催化活性，对2-羟基化的催化活性最明显。与野生型酶相比，CYP1A1.2形成主要代谢产物2-OH-E2和2-OH-E1的催化效率分别高5.7倍和12倍。由CYP 1A 1A催化的羟基化的催化效率与野生型酶的催化效率大致相当。酶动力学分析表明，CYP1A1.2（Ile 462 Val）的上级活性主要是由于V-max较高所致，而所有变异体的Km值相似。这些数据表明，雌激素诱导的癌症和心血管疾病的风险可能至少部分由CYP 1A 1基因型决定。
Several epidemiologic studies associate certain CYP1A1 genotypes, alone or in combination, with-an increased risk of estrogen-related cancers. To answer the question of whether genotype-dependent activation of estrogens by CYP1A1 could be the underlying mechanism, we studied the hydroxylation activity of the most common allelic variants of human CYP1A1 towards both endogenously occurring estrogens, 17 beta-estradiol (E2) and estrone (El). We expressed and purified CYP1A1.1 (wild-type), CYP1A1.2 (Ile(462)Val), and CYP1A1.4 (Thr(461)Asn) and did enzymatic assays of NADPH-dependent estrogen hydroxylation in reconstituted CYP1A1 systems. All CYP1A1 variants catalyzed the formation of 2-, 4-, 6 alpha-, and 15 alpha-hydroxylated estrogen metabolites from E2 and El, yet with varying catalytic efficiency and distinct regiospecificity. Whereas the variant CYP1A1.2 (Ile462Val) had a significant higher catalytic activity for all hydroxylation sites and both substrates, it was most pronounced for 2-hydroxylation. Catalytic efficiencies for the formation of the major metabolites, 2-OH-E2 and 2-OH-E1, by CYP1A1.2 were 5.7- and 12-fold higher, respectively, compared with the wild-type enzyme. The catalytic efficiencies for hydroxylations catalyzed by CYP1A1A were roughly comparable with those of the wild-type enzyme. Enzyme kinetics showed that the superior activity of CYP1A1.2 (Ile462Val) is mainly caused by a higher V-max, whereas K-m values of all variants were similar. The data suggest that risk of estrogen-induced cancers and cardiovascular diseases might be-at least partially-determined by the CYP1A1 genotype.