Withaferin A Inhibits Experimental Epithelial-Mesenchymal Transition in MCF-10A Cells and Suppresses Vimentin Protein Level in Vivo in Breast Tumors

We have shown previously that withaferin A (WA), a bioactive component of the medicinal plant Withania somnifera, inhibits growth of cultured and xenografted human breast cancer cells and prevents breast cancer development and pulmonary metastasis incidence in a transgenic mouse model. The present study was undertaken to determine if the anticancer effect of WA involved inhibition of epithelial-mesenchymal transition (EMT). Experimental EMT induced by exposure of MCF-10A cells to tumor necrosis factor- (TNF-) and transforming growth factor-1 (TGF-) was partially reversed by treatment with WA but not by its structural analogs withanone or withanolide A. Combined TNF- and TGF- treatments conferred partial protection against MCF-10A cell migration inhibition by WA. Inhibition of TNF- and TGF--induced MCF-10A cell migration by WA exposure was modestly attenuated by knockdown of E-cadherin protein. MCF-7 and MDA-MB-231 cells exposed to WA exhibited sustained (MCF-7) or transient (MDA-MB-231) induction of E-cadherin protein. On the other hand, the level of vimentin protein was increased markedly after 24h treatment of MDA-MB-231 cells with WA. WA-induced apoptosis was not affected by vimentin protein knockdown in MDA-MB-231 cells. Protein level of vimentin was significantly lower in the MDA-MB-231 xenografts as well as in MMTV-neu tumors from WA-treated mice compared with controls. The major conclusions of the present study are that (a) WA treatment inhibits experimental EMT in MCF-10A cells, and (b) mammary cancer growth inhibition by WA administration is associated with suppression of vimentin protein expression in vivo. (c) 2013 Wiley Periodicals, Inc.