Influence of curcumin on smad signal transduction pathway of EMT

Objective To investigate the interfering effect of curcumin(Cur)on smad signal transduction pathway of epithelial myofibroblast transdifferentiation(EMT)induced by transforming growth factor-β1(TGF-β1).Methods The human HK-2 cells were treated by TGF-β1(10 μg/L)at different time points(0,12,24,48 and 72 h).The expressions of α-smooth muscle actin(α-SMA)and E-cadherin were detected by using Western blotting method.The human HK-2 cells were pretreated with Cur in ascending concentration(1,5 and 10 μmoL/L)for 24 hours and then cultured in TGF-β1 culture solution for collecting and exacting protein and mRNA for 48 hours.The expressions of smad3,p-smad2/3,smad7 and TFβR-Ⅱ were detected by using Western blotting method,and mRNA expressions of collagen Ⅰ(Col Ⅰ)and Col Ⅲ were determined by applying RT-PCR.Results The phosphorylation of smad2/3 in HK-2 cells induced by TGF-β1 was earlier than the down-regulation of E-cadherin and the synthesis of α-SMA.After the intervention of Cur,the expressions of TFβR-Ⅱ,Col Ⅰ-mRNA and Col Ⅲ-mRNA,and phosphorylation of smad2 were inhibited significantly.The expression of smad7 was improved.Conclusion Cur can obstruct EMT process through interfering multiple sites of TGF-β1/smads signal transduction pathway.