Selective Induction of Estrogen Conjugative Metabolism

描述（由申请人提供）：本提案旨在检验一种新的假设，即能够优先刺激雌二醇（E2）及其羟基化代谢物（如4-OH-E2和16 α-OH-E1）代谢转化为无活性水溶性结合物的化学品，与雌激素氧化代谢诱导剂相比，是E2诱导癌症的更好和更安全的抑制剂。根据我们最近关于膳食二苯甲酰甲烷（DAM）对人乳腺细胞和动物E2结合代谢的优先刺激作用的数据，我们提出了以下四个具体目标，用于我们对这一新假设的初步检验。目标1：通过生物化学测定和北方印迹分析，研究膳食DBM及其类似物在诱导非肿瘤性人乳腺上皮细胞AG 11134中雌激素结合酶（葡萄糖醛酸化、硫酸化和O-甲基化）与氧化的活性。目标二：研究目标1下确定的强效饮食诱导剂在雌性ACI大鼠肝脏、乳腺和子宫中诱导雌激素结合的活性。目标3：比较雌激素结合的强诱导剂与吲哚-3-甲醇（雌激素氧化的典型饮食诱导剂）对雌性ACI大鼠血液和靶器官中E2和4-OH-E2（代表性生物活性羟雌激素代谢产物）代谢结局的影响。目标4：比较雌激素结合代谢诱导剂吲哚-3-甲醇对雌激素E2和4-OH-E2在雌性大鼠乳腺和子宫中促有丝分裂作用的影响，并比较它们预防雌激素诱导的雌性ACI大鼠乳腺肿瘤的效果。我们预测，在雌激素的激素活性同样受到抑制的条件下，雌激素结合代谢的诱导剂将具有比雌激素氧化代谢的诱导剂高得多的癌症预防功效。这些假设驱动的，基于机制的研究将导致一个有效的，新的策略的发展，饮食或植物化学为基础的预防雌激素诱导的人类癌症。这些研究还将提供生物活性雌激素代谢物的重要作用的检查（例如，4-OH-E2和16 α-OH-E2）在雌激素诱导的癌症中的作用。

DESCRIPTION (provided by applicant): This proposal is aimed at testing a novel hypothesis that chemicals that can preferentially stimulate the metabolic conversion of estradiol (E2) and its hydroxylated metabolites (such as 4-OH-E2 and 16alpha-OH-E1) to inactive, water-soluble conjugates would be better and safer inhibitors of E2-induced cancer than inducers of estrogen oxidative metabolism. On the basis of our recent data on the preferential stimulatory effect of dietary dibenzoylmethane (DAM) on E2 conjugative metabolism in human mammary cells and in animals, we propose the following four Specific Aims for our initial testing of this novel hypothesis. Aim 1: To study dietary DBM and its analogs for their activity in inducing the enzymes for estrogen conjugation (glucuronidation, sulfation, and O-methylation) vs oxidation in non-neoplastic AG11134 human mammary epithelial cells by using biochemical assays and Northern blot analysis. Aim 2: To study strong dietary inducers identified under Aim 1 for their activity in inducing estrogen conjugation in liver, breast, and uterus of female ACI rats. Aim 3: To compare the effects of strong inducers of estrogen conjugation with indole-3-carbinol (a prototypical dietary inducer of estrogen oxidation) on the metabolic fate of E2 and 4-OH-E2 (a representative bioactive hydroxyestrogen metabolite) in blood and target organs of female ACI rats. Aim 4: To compare the effects of an identified inducer of estrogen conjugative metabolism with indole-3-carbinol on the mitogenic actions of E2 and 4-OH-E2 in the breast and uterus of female rats, and to compare their efficacies in the prevention of estrogen-induced mammary tumors in female ACI rats. We predict that an inducer of estrogen conjugative metabolism will have a much higher cancer-preventive efficacy than an inducer of estrogen oxidative metabolism under conditions where estrogen's hormonal activity is equally inhibited. These hypothesis-driven, mechanism-based studies will lead to the development of an effective, novel strategy for dietary or phytochemical-based prevention of estrogen-induced human cancers. These studies will also provide examinations of the important roles of bioactive estrogen metabolites (e.g., 4-OH-E2 and 16alpha-OH-E2) in estrogen-induced cancers.