Epigenomics, 2011, 3(6):795-803.

DNA methylation and soy phytoestrogens: quantitative study in DU-145 and PC-3 human prostate cancer cell lines

Mawussi Adjakly, et al

Département d'Oncogénétique, Centre Jean Perrin, Clermont-Ferrand, France; et al

AIM: DNA hypermethylation is an epigenetic mechanism which induces silencing of tumor-suppressor genes in prostate cancer. Many studies have reported that specific components of food plants like soy phytoestrogens may have protective effects against prostate carcinogenesis or progression. Genistein and daidzein, the major phytoestrogens, have been reported to have the ability to reverse DNA hypermethylation in cancer cell lines. The aim of this study was to investigate the potential demethylating effects of these two soy compounds on BRCA1, GSTP1, EPHB2 and BRCA2 promoter genes.

METHODS & MATERIALS: Prostate cell lines DU-145 and PC-3 were treated with genistein 40 µM, daidzein 110 µM, budesonide (methylating agent) 2 µM and 5-azacytidine (demethylating agent) 2 µM. In these two human prostate cancer cell lines we performed methylation quantification by using Methyl Profiler DNA methylation analysis. This technique is based on a methylation-specific digestion followed by quantitative PCR. We analyzed the corresponding protein expression by western blotting.

RESULTS: Soy phytoestrogens induced a demethylation of all promoter regions studied except for BRCA2, which is not methylated in control cell lines. An increase in their protein expression was also demonstrated by western blot analysis and corroborated the potential demethylating effect of soy phytoestrogens.

CONCLUSION: This study showed that the soy phytoestrogens, genistein and daidzein, induce a decrease of methylation of BRCA1, GSTP1 and EPHB2 promoters. Therefore, soy phytoestrogens may have a protective effect on prostate cancer. However, more studies are needed in order to understand the mechanism by which genistein and daidzein have an inhibiting action on DNA methylation.

英国《表观基因学》，2011年12月

DNA 甲基化和大豆植物雌激素︰ 在 DU-145 和 PC-3 人体前列腺癌细胞中的定量研究

马武西 艾迪克利等

法国克莱蒙费朗让佩林中心遗传学系等

目的︰ DNA 的甲基化是一种表观遗传机制，在前列腺癌中诱导肿瘤抑制基因的抑制。很多研究报道，类似于大豆植物雌激素的食品植物的特定组分可能会对前列腺癌的发生或进展起到保护作用。染料木素和大豆黄酮，主要的植物雌激素，曾经被报道过能够逆转肿瘤细胞的DNA 甲基化。本研究旨在探讨这两种大豆化合物对 BRCA1、 GSTP1、 EPHB2 和 BRCA2 启动子基因去甲基化的影响潜力。

方法与材料︰ 前列腺癌细胞DU-145 和 PC-3 用40 µM金雀异黄素、110 µM大豆苷元、2 µM布地奈德 （甲基化试剂）和2 µM 5-氮杂胞苷 （去甲基化试剂）处理。在这两种人体前列腺癌细胞中我们使用甲基探查器 DNA 甲基化分析仪完成了对甲基化的量化。这项技术基于在定量 PCR后的甲基化特异性消化。我们用免疫印迹法分析了相应的蛋白表达。

结果︰ 大豆植物雌激素诱导了所有研究的启动子的去甲基化，除了在对照细胞中没有甲基化的BRCA2。通过免疫印迹分析也表明它们的蛋白表达有所增加并且证实了大豆植物雌激素潜在的去甲基化影响。

结论︰ 本研究表明，大豆植物雌激素， 染料木素和大豆黄酮，诱导 BRCA1、 GSTP1 和 EPHB2 的启动子甲基化降低。因此，大豆植物雌激素可能对前列腺癌具有保护作用。然而，需要更多的研究来了解染料木素和大豆黄酮对 DNA 甲基化产生抑制作用的机制。