Effects of red clover extracts on breast cancer cell migration and invasion

Postmenopausal hormone therapy is associated with increased incidence of breast cancer. For this reason alternative therapeutic options to treat menopausal symptoms have been developed. Red clover extracts (RCE) are rich in isoflavones, particularly genistein and daidzein and they have been proved to be effective in reducing vasomotor symptoms in a number of studies. Due to their partial selectivity of action on estrogen receptors (ERs) these compounds have been claimed to be safer on the breast. In this article, we explored the action of RCE on motility and invasion of ER positive breast cancer cells and we partially characterized the signaling mechanisms. The principal isoflavones contained in RCE acted as weak estrogenic compounds when administered alone. However, when provided in association with physiological amounts of estradiol, RCE acted as estrogen antagonist on remodeling of actin cytoskeleton that are requested to enact cell movement and with related modifications of the activity of actin-binding proteins, such as moesin. These results offer novel information on the molecular actions of isoflavones contained in red clover on breast cancer cells, supporting a possible action of these molecules as natural selective estrogen receptor modulators in the presence of physiological amounts of estrogens.