Abstract 841: Effect of equol on hormone-dependent rat mammary carcinoma induced by ethyl methanesulphonate (EMS)

Abstract

Soy isoflavones such as daidzein and its bioactive metabolite equol converted from daidzein by human intestinal bacterial flora, have been proposed to reduce the risk of breast cancer incidence in Asian women probably due to higher number of the inhabitants capable of producing equol in these countries. Although several in vitro studies shows the anti-cancer activity of equol against human breast cancer cells, there have been few reports that have directly showed the preventive role of equol in the experimental animal model of mammary carcinoma. We investigated here the effects of equol on the development of breast cancer using the EMS chemically induced rat model of hormone-dependent mammary carcinoma. Female WKA rats (n = 30) were equally divided into 2 groups, subsequently given EMS orally for 12 weeks and fed the CE2 diets with or without 50 mg equol/g diet throughout the experiments. All EMS-treated rats fed either diet developed ER- and/or PgR- positive hormone-dependent mammary carcinoma by 24 weeks. Compared with the equol-free diet, the diet supplemented with equol could not significantly delay the development of mammary carcinoma, showing any preventive activity on the development of EMS-induced hormone-dependent mammary carcinoma. The body weight, total EMS uptakes, and urine estradiol concentrations were not significantly different between these 2 groups. These data indicate that high dose administration of equol alone does not exert clear preventive effects on hormone-dependent EMS-induced mammary carcinogenesis, and may require other soy isoflavone components such as genistein that has previously been shown to exhibit a great synergy when combined with equol. The in vivo combination studies using genistein and equol are underway.

Citation Format: MISAKI ONO, Takako Higuchi, Mikako Takeshima, Shuji Nakano. Effect of equol on hormone-dependent rat mammary carcinoma induced by ethyl methanesulphonate (EMS). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 841.