Abstract
Formononetin is one of the main active components of red clover plants, and considered
as a phytoestrogen. Its pharmacological effects in vivo may be either estrogenic or
anti-estrogenic, mainly depending upon the estrogen levels. Our recent studies suggested
that formononetin inactivated IGF1/IGF1R-PI3K/Akt pathways and decreased cyclin D1
mRNA and protein expression in human breast cancer cells in vitro and in vivo. In
the present study, we further investigated the molecular mechanisms involved in the
induced apoptosis effect of formononetin on breast cancer cells. Our results suggested
that formononetin inhibited the proliferation of ER-positive MCF-7 cells and T47D
cells. In contrast, formononetin could not inhibit the cell of growth of ER-negative
breast cancer cells such as MDA-MB-435 S cells. We further found that formononetin
activated MAPK signaling pathway in a dose-dependent manner, which resulted in the
increased ratio of Bax/Bcl-2, and induced apoptosis on MCF-7 cells. However, when
MCF-7 cells were pretreated with p38MAPK inhibitor SB203580 before formononetin, apoptosis
induced by formononetin was significantly attenuated. Thus, we conclude that the induced
apoptosis effect of formononetin on human breast cancer cells were related to Ras-p38MAPK
pathway. Considering that red clover plants are widely used clinically, our results
provide the foundation for future development of formononetin for treatment of ER-positive
breast cancer.
Key words
formononetin - breast cancer - MAPK - p38 - apoptosis