RESUMO
<p><b>OBJECTIVE</b>To investigate the effect of Smad7 on the expressions of collagen I and alpha-smooth muscle actin (alpha-SMA) in HSC-T6 cell line activated by transforming growth factor-beta1 (TGF-beta1).</p><p><b>METHODS</b>HSC-T6 cells stably expressing M2-flag protein were selected after co-infection of the cells with pTRE-Smad7-M2-flag and pTet-on. The optimal dose of doxycycline for inducing Smad7 was determined, and the effects of Smad7 over-expression on the expressions of collagen I and alpha-SMA in the cells activated by TGF-beta1 and on Smad2/3 phosphorylation were evaluated using Western blotting.</p><p><b>RESULTS</b>The optimal dose of doxycycline for inducing Smad7 expression was 2 mg/L. Smad7 over-expression induced by doxycycline decreased the expressions of collagen I and alpha-SMA in HSC-T6 cells activated by TGF-beta1, and down-regulated the level of Smad2/3 phosphorylation.</p><p><b>CONCLUSION</b>Smad7 over-expression inhibits Smad2/3 phosphorylation, and decreases the expression of collagen I and alpha-SMA in HSC-T6 cells induced by TGF-beta1 to inhibit the progression of liver fibrosis.</p>