Pretreatment with phytoestrogen-rich plant decreases breast tumor incidence and exhibits lower profile of mammary ERα and ERβ

Objective: Phytoestrogens have been reported to exhibit antiproliferation to human breast cancer cells in vitro. We tested the phytoestrogen-rich, Pueraria mirifica against rat breast cancer induction in vivo. Methods: The weanling female Spargue-Dawley rats were pretreated with P. mirifica tuberous powder at a dosage of 0, 10, 100 and 1000 mg/kg BW/day for four consecutive weeks. Mammary tumor development was then induced with a single dose of 7,12-DMBA, 80 mg/kg BW, followed by a weekly examination for size and multiplicity of mammary tumors for 20 weeks and finally a necropsy. Mammary tissues were investigated for the virulence of tumor and also monoclonal antibody stained against ER alpha and ER beta. Results: Pretreatment of 1000 mg/(kg BW day) of P. mirifica tuberous powder resulted in decreasing of the virulence of rat tumor development. The mammary tumor tissues exhibited lower profile of ER alpha and ER beta as well as ER alpha/ER beta. Conclusion: P mirifica exhibited prevention of 7,12-DMBA-induced rat mammary tumors, with a proposed mechanism of strong competitive binding of its phytoestrogens to ER alpha and/or synthesis suppressor of ER alpha. (c) 2007 Elsevier Ireland Ltd. All rights reserved.