Triclosan (TCS) is an endocrine-disrupting chemical (EDC) and has a potential to increase progression of hormone responsive cancers as does 17β-estradiol (E2). As a phytoestrogen, Kaempferol plays a chemopreventive role inhibiting cancer formation and progression. In this study, chemopreventive activity of kaempferol was examined by measuring its effect on growth, epithelialmesenchymal transition (EMT), and migration of MCF-7 breast cancer cells increased by 17β-estradiol (E2, a positive

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... ) or triclosan (TCS), an endocrinedisrupting chemical (EDC). As an EDC, TCS is known to interfere estrogen receptor (ER) dependent pathway in MCF-7 cells expressing ERs. In MTT assay, TCS (10 -4 -10 -7 M) or E2 (10 -9 M) induced cell growth of MCF-7 cells, which was reversed to a control level by co-treatment of ICI 182,780 (10 -8 M), an ER antagonist, or kaempferol (50 uM). In a wound-healing scratch assay, TCS enhanced migration of MCF-7 cells like E2, but co-treatment of kaempferol or ICI 182,720 decreased the migration ability of MCF-7 cells to a control level. Also Kaempferol could block invasion ability of MCF-7 breast cancer cell induced by E2 and TCS in transwell invasion assay. In western blot assay, we examined the effect of TCS and Kaempferol on protein expression of EMT-related markers such as Ecadherin, N-cadherin, snail and slug. TCS induced the increased expression of EMT promoting markers such as N-cadherin, snail and slug, but down-regulated the expression of E-cadherin, an epithelial marker inhibiting EMT process. On the contrary, kaempferol was shown to reverse the expression pattern of EMT-related markers induced by TCS or E2. Also, E2 and TCS induced metastasis in MCF -7 breast cancer cell. We examined the effect of E2, TCS and Kaempferol on protein expression of metastasis related markers such as Cathepsin B and D. E2 and TCS increased the expression of Cathepsin B and D, but ICI 182,780 and Kaempferol decreased the expression of cathepsin B and D. In conclusion, kaempferol effectively suppressed growth, EMT, and migration ability of MCF-7 breast cancer cells increased by E2 and TCS. ABSTRACT 17ß-estradiol or triclosan-induced epithelial-mesenchymal transition and migration of MCF-7 breast cancer cells were reversed by kaempferol, a phytoestrogen