An estrogen receptor signaling pathway is involved in 3,3′-diindolylmethane-induced inhibition of cell migration of MCF-7 breast cancer caused by triclosan via the regulation of epithelial- mesenchymal transition

ECE 2016 Triclosan (TCS) and Bisphenol A (BPA) are an endocrinedisrupting chemicals (EDCs) and have a potential to increase progression of hormone responsive cancers as does 17β-estradiol (E2).3,3'-diindolylmethane (DIM), a phytoestrogen, has been known to have anticancer activity.In this study, we examined the anti-proliferative and antiepithelial-mesenchymal transition (EMT) effects of DIM on TCS, BPA or E2-induced EMT of MCF-7 breast cancer cells, which express estrogen receptors (ERs).In MTT assay, TCS and BPA (10 -4 -10 -7 M, both) induced growth of MCF-7 cells compared to a control (DMSO) like E2 (a positive control, 10 -9 M), which was antagonized by addition of ICI 182,720 (10 -8 M), suggesting that the cell proliferation effect induced by TCS appears to be mediated by an ER-dependent manner.On the contrary, DIM (20-50 uM) significantly reduced the increased viability of MCF-7 cells induced by TCS, BPA or E2.In a scratch assay, TCS and BPA also enhanced migration of MCF-7 cells like E2, but co-treatment of DIM or ICI 182,720 reduced the migration ability of TCS, BPA and E2 to a control level.Along with the effect of TCS, we measured TCS, BPA or E2-induced alterations in protein expression levels of EMT related markers, i.e., E-cadherin, N-cadherin, snail and slug by western blot assay.We detected that protein expression of E-cadherin was declined while N-cadherin, snail and slug expressions were increased by TCS, BPA or E2, indicating that TCS and BPA induced EMT process in MCF-7 cells like E2. Differently, DIM was shown to adversely affect the expression of EMT markers induced by TCS, BPA or E2.Taken together, these results present that DIM effectively inhibits the cell growth and EMT process of MCF-7 cells increased by TCS, BPA or E2.Furthermore, EDCs induced metastasis genes such as cathepsin B and D. they are sub genes of down stream in CXCR4 signaling pathway which stimulates EMT in ER positive breast cancer cell.Based on these in vitro results, in vivo effect of TCS, BPA and DIM on tumor growth and EMT process will be examined in a xenografted mouse model transplanted with human MCF-7 breast cancer cells.MCF-7 cells will be injected to mice and they will be taken E2, TCS, BPA and DIM chemicals in 10 weeks.And the tumor will be calculated for effects by EDCs and phytoestrogen.