Beta-Elemene Blocks Epithelial-Mesenchymal Transition in Human Breast Cancer Cell Line MCF-7 through Smad3-Mediated Down-Regulation of Nuclear Transcription Factors

Epithelial-mesenchymal transition (EMT) is the first step required for breast cancer to initiate metastasis. However, the potential of drugs to block and reverse the EMT process are not well explored. In the present study, we investigated the inhibitory effect of beta-elemene (ELE), an active component of a natural plant-derived anti-neoplastic agent in an established EMT model mediated by transforming growth factor-beta1 (TGF-beta 1). We found that ELE (40 mu g/ml) blocked the TGF-beta 1-induced phenotypic transition in the human breast cancer cell line MCF-7. ELE was able to inhibit TGF-beta 1-mediated upregulation of mRNA and protein expression of nuclear transcription factors (SNAI1, SNAI2, TWIST and SIP1), potentially through decreasing the expression and phosphorylation of Smad3, a central protein mediating the TGF-beta 1 signalling pathway. These findings suggest a potential therapeutic benefit of ELE in treating basal-like breast cancer.