IGFBPrP1 induces liver fibrosis by inducing hepatic stellate cell activation and hepatocyte apoptosis via Smad2/3 signaling

AIM:To investigate the role and mechanism of insulinlike growth factor binding protein-related protein 1(IGFBPrP1)in the development of liver fibrosis.METHODS:An in vitro model using hepatic stellate cell(HSC)-T6 cells and an in vivo model of rat liver overexpressing IGFBPrP1 were established using an IGFBPrP1-expressing recombinant adenovirus.The expression of IGFBPrP1 was examined by immunofluorescence,and the expression of collagen?Ⅰ?and fibronectin was mea-sured by real-time reverse transcription-polymerase chain reaction and Western blot analysis.The expression of Smad2/3 and p-Smad2/3 was examined by Western blot and immunohistochemistry.A shSmad3-expressing recombinant adenovirus(AdshSmad3)was designed and used to knockdown the Smad3 gene in HSC-T6 cells and rat liver fibrosis transfected with IGFBPrP1.The expression of collagen?Ⅰ,fibronectin,andα-smooth muscle actin(α-SMA)was determined by Western blot analysis and immunohistochemistry.Hepatocyte apoptosis was assessed using TUNEL assay.RESULTS:IGFBPrP1 overexpression induced collagen deposition and up-regulated the expression ofα-SMA and p-Smad2/3,and AdshSmad3 inhibited IGFBPrP1-stimulated p-Smad2/3 activation and the expression ofα-SMA,collagen?Ⅰ?and fibronectin in HSC-T6 cells.Similarly,increased hepatocyte apoptosis(38.56%±3.42%vs 0.24%±0.03%,P<0.05),α-SMA positive stained cells(29.84%±1.36%vs 5.83%±1.47%,P<0.05),and increased numbers of Smad3(35.88%±2.15%vs10.24%±1.31%,P<0.05)and p-Smad2/3 positive cells(28.87%±2.73%vs 8.23%±0.98%,P<0.05)were detected in the livers of IGFBPrP1-overexpressing rats compared with the control group.Moreover,AdshSmad3 reduced IGFBPrP1-stimulated Smad3 expression and attenuatedα-SMA expression(29.84%±1.36%vs 8.23%±1.28%,P<0.05),hepatocyte apoptosis(38.56%±3.42%vs 6.75%±0.52%,P<0.05),and both collagen?Ⅰ?and fibronectin deposition in the livers of AdIGFBPrP1-treated rats.CONCLUSION:IGFBPrP1 induces liver fibrosis by mediating the activation of hepatic stellate cells and hepatocyte