Abstract: Objective To investigate the inhibitory effect of 5-FU on human intrahepatic biliary epithelial cells with TGF-β1-induced mesenchymal transition, and to explore the mechanism. Methods The primary epithelial cells from human intrahepatic bile ducts were cultured, the cells were identified by immunofluorescence staining. The cells were randomly divided into 3 groups: normal control group, TGF-β1 group and TGF-β1+5-FU group. The expression of CK-19, E-cadherin, vimentin and α-SMA protein were measured by immunofluorescence staining and Western blot assay. Western blot was used to detect the expression levels of TGF-β1. Real-time PCR to detect mRNA expression of TGF-β1,Ⅰand collagen type Ⅲ. Results The primary epithelial cells of intrahepatic bile ducts were successfully cultured. In TGF-β1 group, the protein expression levels of vimentin, α-SMA and the mRNA expression levels ofⅠand collagen type Ⅲ were significantly higher than that of normal control group（P<0.05）, the protein expression levels of CK-19 and E-cadherin protein were lower than that of normal control group（P<0.05）, TGF-β1 protein and mRNA expressions were significantly higher compared with that of normal control group（P<0.05）. In TGF-β1+5-FU group, the protein expression levels of CK-19 and E-cadherin protein were higher than that in normal control group（P<0.05）, the protein expression levels of vimentin, α-SMA and the mRNA expression levels of collagen type Ⅲ were significantly lower than that of TGF-β1 group（P<0.05）, while there was no significantly difference in collagen typeⅠmRNA between the two groups（P>0.05）, TGF-β1 protein and mRNA expressions were significantly lower compared with that of normal TGF-β1 group（P<0.05）. Conclusions 5-FU could inhibit TGF-β1-induced biliary epithelial - mesenchymal transition with down-regulated expression of TGF-β1.

Key words: biliary epithelial cell, TGF-β1, mesenchymal transition, marker protein, 5-fluorouracil