Dunlap Tareisha L, Howell Caitlin E, Mukand Nita, Chen Shao-Nong, Pauli Guido F, Dietz Birgit M, Bolton Judy L
UIC/NIH Center for Botanical Dietary Supplements Research, Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago , 833 S. Wood Street, Chicago, Illinois 60612-7231, United States.
Chem Res Toxicol. 2017 Nov 20;30(11):2084-2092. doi: 10.1021/acs.chemrestox.7b00237. Epub 2017 Oct 19.
Many women consider botanical dietary supplements (BDSs) as safe alternatives to hormone therapy for menopausal symptoms. However, the effect of BDSs on breast cancer risk is largely unknown. In the estrogen chemical carcinogenesis pathway, P450 1B1 metabolizes estrogens to 4-hydroxylated catechols, which are oxidized to genotoxic quinones that initiate and promote breast cancer. In contrast, P450 1A1 catalyzed 2-hydroxylation represents a detoxification pathway. The current study evaluated the effects of red clover, a popular BDS used for women's health, and its isoflavones, biochanin A (BA), formononetin (FN), genistein (GN), and daidzein (DZ), on estrogen metabolism. The methoxy estrogen metabolites (2-MeOE, 4-MeOE) were measured by LC-MS/MS, and CYP1A1 and CYP1B1 gene expression was analyzed by qPCR. Nonmalignant ER-negative breast epithelial cells (MCF-10A) and ER-positive breast cancer cells (MCF-7) were derived from normal breast epithelial tissue and ER+ breast cancer tissue. Red clover extract (RCE, 10 μg/mL) and isoflavones had no effect on estrogen metabolism in MCF-10A cells. However, in MCF-7 cells, RCE treatments downregulated CYP1A1 expression and enhanced genotoxic metabolism (4-MeOE/CYP1B1 > 2-MeOE/CYP1A1). Experiments with the isoflavones showed that the AhR agonists (BA, FN) preferentially induced CYP1B1 expression as well as 4-MeOE. In contrast, the ER agonists (GN, DZ) downregulated CYP1A1 expression likely through an epigenetic mechanism. Finally, the ER antagonist ICI 182,780 potentiated isoflavone-induced XRE-luciferase reporter activity and reversed GN and DZ induced downregulation of CYP1A1 expression. Overall, these studies show that red clover and its isoflavones have differential effects on estrogen metabolism in "normal" vs breast cancer cells. In breast cancer cells, the AhR agonists stimulate genotoxic metabolism, and the ER agonists downregulate the detoxification pathway. These data may suggest that especially breast cancer patients should avoid red clover and isoflavone based BDSs when making choices for menopausal symptom relief.
许多女性认为植物性膳食补充剂（BDS）是缓解更年期症状的激素疗法的安全替代品。然而，BDS对乳腺癌风险的影响很大程度上尚不清楚。在雌激素化学致癌途径中，细胞色素P450 1B1（P450 1B1）将雌激素代谢为4-羟基化儿茶酚，后者被氧化为具有基因毒性的醌，从而引发和促进乳腺癌。相反，P450 1A1催化的2-羟基化代表一条解毒途径。本研究评估了用于女性健康的常见BDS红三叶草及其异黄酮（染料木黄酮（BA）、芒柄花素（FN）、染料木素（GN）和大豆苷元（DZ））对雌激素代谢的影响。通过液相色谱-串联质谱法（LC-MS/MS）测定甲氧基雌激素代谢物（2-甲氧基雌激素（2-MeOE）、4-甲氧基雌激素（4-MeOE）），并通过定量聚合酶链反应（qPCR）分析细胞色素P450 1A1（CYP1A1）和细胞色素P450 1B1（CYP1B1）基因表达。非恶性雌激素受体阴性乳腺上皮细胞（MCF-10A）和雌激素受体阳性乳腺癌细胞（MCF-7）分别来源于正常乳腺上皮组织和雌激素受体阳性乳腺癌组织。红三叶草提取物（RCE，10μg/mL）和异黄酮对MCF-10A细胞的雌激素代谢没有影响。然而，在MCF-7细胞中，RCE处理下调了CYP1A1表达并增强了基因毒性代谢（4-MeOE/CYP1B1＞2-MeOE/CYP1A1）。异黄酮实验表明，芳烃受体（AhR）激动剂（BA、FN）优先诱导CYP1B1表达以及4-MeOE。相反，雌激素受体（ER）激动剂（GN、DZ）可能通过表观遗传机制下调CYP1A1表达。最后，雌激素受体拮抗剂ICI 182,780增强了异黄酮诱导的XRE-荧光素酶报告基因活性，并逆转了GN和DZ诱导的CYP1A1表达下调。总体而言，这些研究表明，红三叶草及其异黄酮对“正常”细胞与乳腺癌细胞中的雌激素代谢具有不同影响。在乳腺癌细胞中，AhR激动剂刺激基因毒性代谢，而ER激动剂下调解毒途径。这些数据可能表明，尤其是乳腺癌患者在选择缓解更年期症状的方法时应避免使用红三叶草和基于异黄酮的BDS。
