Evaluation of the safety profiles of estrogenic Chinese herbal medicines in breast cancer

Abstract

Background: An increasing number of breast cancer patients in Asian countries has been found to consume dietary supplements including phytoestrogen-rich Chinese herbal medicines with an expectation to alleviate the side effects of conventional cancer therapies. Purpose: The question of whether estrogenic Chinese herbal medicines are beneficial or detrimental to the health of breast cancer patients remains uncertain. Study Design: The present study aimed at establishing a systematic approach to look at the safety profiles of estrogenic Chinese herbal medicines (CHM). Methods: The effects of estrogenic CHM on the growth of human breast cancer cells as well as the progression of breast tumors in mice have been investigated. Results: Our results demonstrated that among 10 selected estrogenic CHM, the aqueous extracts of Cistanche deserticola (CD) and Dioscorea opposita (DO) at 0.4 to 1.6 mg/ml significantly stimulated cell viability in both estrogen receptor (ER)-positive (MDA-MB-361 and MCF-7) and ER-negative (SKBR3 and MDA-MB-231) breast cancer cells. However, results from animal studies showed that no significant difference was found on the size of mouse 4T1 breast tumors in CD- and DO-treated mice when compared with the control group, while the number of proliferative cells were found to be increased in DO-treated group. Besides, CD and DO treatments induced significant immunomodulatory effects on 4T1 tumor-bearing mice by increasing the production of cytokines IL-2 and IFN-γ and modulation of regulatory T-cells. Furthermore, CD and DO treatments did not stimulate, but in fact suppressed human triple-negative MDA-MB-231 breast xenografts growth in immunodeficiency mice. Conclusion: The considerable concerns on the use of CD and DO in breast cancer patients could be relieved to some extents upon the findings of this pre-clinical study. The potential harmful effects of estrogenic Chinese herbal medicines on breast cancer growth should be verified in both cell-based and tumor-bearing mice models.