Adenoviral delivery of dominant-negative transforming growth factor β type II receptor up-regulates transcriptional repressor SKI-like oncogene, decreases matrix metalloproteinase 2 in hepatic stellate cell and prevents liver fibrosis in rats

Background Dominant‐negative transforming growth factor β type II receptor (TβRIIΔcyt) is a protein that blocks transforming growth factor (TGF‐β) signaling. Because the consequences of blocking TGF‐β have not been completely elucidated in liver fibrosis, we analysed the effects of adenoviral delivery of TβRIIΔcyt on profibrogenic genes and matrix metalloproteinase (MMP) proteins, as well as on TGF‐β signal repressor SKI‐like oncogene (SnoN), in cultured hepatic stellate cells (HSCs) and in a rat model of liver fibrosis. Methods To induce liver fibrosis, rats were treated with thioacetamide for 7 weeks and administrated once with Ad‐TβRIIΔcyt or Ad‐βgal through the iliac vein. Fibrosis was measured by morphometric analysis. We evaluated SnoN by western blot, immunocytochemistry and immunohistochemistry; MMP activity was determined by zymography and profibrogenic gene expression by the real‐time reverse transcriptase‐polymerase chain reaction in cultured HSCs and liver tissue. Results Profibrogenic gene expression of collagen α1 (I), TGF‐β1, platelet‐derived growth factor‐B, plasminogen activator inhibitor (PAI)‐1, tissue inhibitor of matrix metalloproteinase‐1 and MMP‐2 was down‐regulated; whereas MMP‐3 was over‐expressed in response to Ad‐TβRIIΔcyt in HSCs. Moreover, zymography assays corroborated MMP‐2 and MMP‐3 changes in activity. Surprisingly, anti‐TGF‐β molecular intervention increased nuclear SnoN in HSCs. In vivo, Ad‐TβRIIΔcyt reduced liver fibrosis, increased nuclear SnoN in sinusoidal cells, and also produced significant suppression in collagen α1 (I), TGF‐β1, PAI‐1, MMP‐2 and over‐expression in MMP‐3 in thioacetamide‐intoxicated animals. Conclusions The results obtained in the present study suggest that the molecular mechanism for the blocking effects of Ad‐TβRIIΔcyt in TGF‐β signaling acts via up‐regulation of the transcriptional repressor SnoN, which antagonizes TGF‐β signaling (TGF‐β/Smad‐pathway inhibitor). Consequently, profibrogenic genes are down‐regulated. Copyright © 2009 John Wiley & Sons, Ltd.