COE inhibits TGF-β1 induced EMT in SGC-7901 cells. (A) The effect of COE on the viability of SGC-7901 cells, as measured with the MTT assay. SGC-7901 cells were either untreated or treated with 20, 40, 80, 160, 320 μg/mL of COE for 24 h. Results are presented as means±SD of three assays. **P <0.01, compared with the untreated control. (B) Morphological changed between TGF-β1-treated SGC-7901 cells and TGF-β1-treated SGC-7901 cells with COE. SGC-7901 cells were incubated with COE (5, 10, 20 μg/mL) for 1 h followed by treatment with 10 ng/mL TGF-β1 for 24 h. Representative pictures of cells treated with COE showed that epithelial morphology of cells was maintained even in the presence of TGF-β1 (200 × magnification). (C) The effect of COE on TGF-β1-induced invasion and migration in SGC-7901 cells were assessed using transwell assay. The invasion and migration ability of cells were quantified by counting the number of cells that invaded to the underside of the porous polycarbonate membrane under microscope (200 × magnification). (D) The effect of COE on the expression of EMT markers. The expression of epithelial marker, E-cadherin and mesenchymal markers, N-cadherin, Vimentin were evaluated by western blot. β-actin was served as an internal control of protein level. The relative density of EMT markers was normalized to β-actin, which was determined by densitometric analysis. Values are expressed as means±SD of three independent experiments. #P <0.05, ##P <0.01, compared with control. *P <0.05, **P <0.01, compared to TGF-β1-treated cells.