Epigenetic modulation of BRCA1 and BRCA2 gene expression by equol in breast cancer cell lines

Br J Nutr. 2012 Oct;108(7):1187-93. doi: 10.1017/S000711451100657X. Epub 2012 Jan 5.

Abstract

S-Equol is a metabolite resulting from the conversion of daidzein, a soya phyto-oestrogen, by the gut microflora. The potential protective effects of equol in breast cancer are still under debate. Consequently, we investigated the effects of equol on DNA methylation of breast cancer susceptibility genes (BRCA1 and BRCA2) and oncosuppressors in breast cancer cell lines (MDA-MB-231 and MCF-7) and in a dystrophic breast cell line (MCF-10a) following exposure to S-equol (2 μm) for 3 weeks. We demonstrated by quantitative analysis of methylated alleles a significant decrease in the methylation of the cytosine phosphate guanine (CpG) islands in the promoters of BRCA1 and BRCA2 after the S-equol treatment in MCF-7 and MDA-MB-231 cells and a trend in MCF-10a cells. We also showed that S-equol increases BRCA1 and BRCA2 protein expression in the nuclei and the cytoplasm in MCF-7, MDA-MB-231 and MCF-10a cell lines by immunohistochemistry. The increase in BRCA1 and BRCA2 proteins was also found after Western blotting in the studied cell lines. In summary, we demonstrated the demethylating effect of S-equol on the CpG islands inside the promoters of BRCA1 and BRCA2 genes, resulting in an increase in the level of expressed oncosuppressors in breast cancer cell lines.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Antineoplastic Agents, Phytogenic / pharmacology*
  • BRCA1 Protein / genetics
  • BRCA1 Protein / metabolism*
  • BRCA2 Protein / genetics
  • BRCA2 Protein / metabolism*
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology
  • Cell Line, Tumor
  • Cell Nucleus / drug effects
  • Cell Nucleus / metabolism
  • CpG Islands / drug effects
  • Cytoplasm / drug effects
  • Cytoplasm / metabolism
  • DNA Methylation / drug effects*
  • Epigenesis, Genetic / drug effects
  • Equol / pharmacology*
  • Estrogen Receptor alpha / metabolism
  • Estrogen Receptor beta / metabolism
  • Female
  • Humans
  • Phytoestrogens / pharmacology*
  • Promoter Regions, Genetic / drug effects
  • Protein Transport / drug effects
  • Up-Regulation / drug effects

Substances

  • Antineoplastic Agents, Phytogenic
  • BRCA1 Protein
  • BRCA1 protein, human
  • BRCA2 Protein
  • BRCA2 protein, human
  • Estrogen Receptor alpha
  • Estrogen Receptor beta
  • Phytoestrogens
  • estrogen receptor alpha, human
  • Equol