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，大豆中存在的生理浓度的异黄酮会调节培养的乳腺癌MCF7细胞中17种β-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。因此，本研究的目的是阐明异黄酮类化合物对培养的人乳腺组织切片中17β-雌二醇代谢的影响。通过反转录/竞争性聚合酶链式反应和使用模型底物(最好是17β-雌二醇或其基因毒性最强的代谢物)，将分别测定经异黄酮类化合物处理的组织切片中最重要的17种β-雌二醇代谢酶的基因水平和酶活性。此外，将使用三种不同的体外测试系统(I)转基因BigBlue®RAT 2细胞、(Ii)选择性地转导17β-雌二醇激活和失活酶的V79细胞和(Iii)MCF7细胞来确定17β-雌二醇代谢变化对基因突变频率的影响。

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.