Influence of soy isoflavonoids on the detoxification of catechol and quinoid estrogens in vitro

雌性激素17β-雌二醇的遗传毒性代谢物的形成和失活的缺乏是乳腺癌发生的关键事件。我们实验室进行的研究表明，大豆中异黄酮的生理浓度可以调节培养的乳腺癌MCF-7细胞中一些17β-雌二醇代谢酶的基因表达和酶活性，从而有利于这些遗传毒性代谢物的产生和持续存在。因此，本研究的目的是阐明异黄酮类化合物对通过缩乳术获得的正常乳腺精密组织切片中17β-雌二醇代谢的影响。通过反转录/竞争性PCR和使用模型底物（最好是17β-雌二醇或其最具遗传毒性的代谢物）分别测定异黄酮处理的组织切片中最重要的17β-雌二醇代谢酶的mRNA水平和酶活性。此外，17β-雌二醇代谢改变对基因突变频率的影响将通过三种不同的体外测试系统来确定(i)转基因BigBlue®大鼠2细胞，（ii）选择性转染17β-雌二醇激活和失活酶的V79细胞，以及（iii） MCF-7细胞。

Formation and lack of inactivation of genotoxic metabolites of the female hormone 17β- estradiol are crucial events in breast carcinogenesis. Studies conducted in our laboratory demonstrated that physiological concentrations of isoflavones occurring in soy modulated the gene expression and the enzyme activity of some 17β-estradiol-metabolizing enzymes in cultured breast cancer MCF-7 cells in a way which would favor the generation and persistence of those genotoxic metabolites. Thus, the aim of the present study is the elucidation of the impact of isoflavonoids on the metabolism of 17β-estradiol in cultured precision-cut tissue slices from normal human mammary glands obtained by reduction mammoplasty. The mRNA levels and enzyme activities of the most important 17β-estradiol-metabolizing enzymes will be determined in tissue slices treated with isoflavonoids by reverse transcription/competitive PCR and the use of model substrates (preferably 17β-estradiol or its most genotoxic metabolite), respectively. Furthermore, the impact of alterations in 17β-estradiol metabolism on the frequency of gene mutations will be determined using three different in vitro test systems (i) transgenic BigBlue® rat 2 cells, (ii) V79 cells, selectively transfected with 17β-estradiol activating and deactivating enzymes, and (iii) MCF-7 cells.