Abstract 3270: The effect of soy exposure in different ages on the mammary tumor development of the MMTV-ErbB-2 transgenic mice

Abstract

Abstract Objective:To investigate the effect of different soy exposure timings on the mammary tumor development using MMTV-erbB-2 transgenic mice. Furthermore, the underlying mechanisms were also examined. Methods:120 MMTV-erbB-2 transgenic female mice were randomly divided into four groups:control group, early exposure group, late exposure group and lifelong exposure group. The control group mice were treated with soy free diet from week 3 to week 60, the experiment groups mice were treated with soy diet between week 3 to week 12, week 20 to week 60, week 3 to week 60, respectively. Then, the body weight change of each mice, the latency period, and the growth speed of mammary tumor were recorded. Furthermore, the mammary gland morphology was examined by whole mount at 5 weeks. In order to understand the underlying mechanisms of the mammary tumor development, the signal pathways of c-Fos, erbB2 and p-ERK were also examined in breast cancer tissue using immunohistochemistry. Results:We found that the weight in the four groups had no significant difference. Compared with the control group, the TEB numbers and the growth speed of tumors in the early exposure group and the lifelong exposure group were significantly decreased and the tumor latency periods were significantly prolonged (P<0.05). Furthermore, immunohistochemistry showed that the mice in the early exposure group and the lifelong exposure group displayed decreased expression of c-Fos and p-ERK (P<0.05). The expression of erbB-2 protein among the different groups was not statistically significant (P>0.05). Conclusion: Early or lifelong soy exposure affects the morphological development of mammary gland of MMTV-erbB-2 transgenic mice. Soy may display a preventive effect on the initiation of breast cancer. These obersveration may serve as a guide for soy use in the early prevention of the breast cancer. The c-Fos and and p-ERK may be involved in the development of mammary tumor in the MMTV-erbB-2 transgenic mice. The underlying mechanism warrants further studies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3270. doi:1538-7445.AM2012-3270