AIM:To explore the role of high-mobility group box 1 (HMGB1) protein during liver fibrogenesis and investigate the functional effects of HMGB1 gene silencing in hepatic stellate cells (HSCs) using siRNA.METHODS:Hepatic fibrosis in rats was induced through serial subcutaneous injections of dimethylnitrosamine,and expression of HMGB1 was detected by immunohistochemistry.HMGB1 siRNAs were developed and transiently transfected into HSC-T6 cells using Lipofectamine 2000.HMGB1 expression was evaluated by real-time polymerase chain reaction (PCR) and Western blotting analysis.Expression of α-smooth muscle actin (α-SMA) and collagen typesⅠand Ⅲ was evaluated by real-time PCR.Cell proliferation and the cell cycle were determined using the methyl thiazolyl tetrazolium method.Finally,collagen content in HSC supernatant was evaluated by an enzyme-linked immunosorbent assay.RESULTS:The results showed that HMGB1 was upregulated during liver fibrosis and that its expression was closely correlated with the deposition of collagen.siRNA molecules were successfully transfected into HSCs and induced inhibition of HMGB1 expression in a time-dependent manner.Moreover,HMGB1 siRNA treatment inhibited synthesis of α-SMA and collagen types Ⅰ and Ⅲ in transfected HSCs.CONCLUSION:This study suggests a significant functional role for HMGB1 in the development of liver fibrosis.It also demonstrates that downregulation of HMGB1 expression might be a potential strategy to treat liver fibrosis. AIM: To explore the role of high-mobility group box 1 (HMGB1) protein during liver fibrogenesis and investigate the functional effects of HMGB1 gene silencing in hepatic stellate cells (HSCs) using siRNA. METHODS: Hepatic fibrosis in rats was induced through serial subcutaneous injections of dimethylnitrosamine, and expression of HMGB1 was detected by immunohistochemistry. HMGB1 siRNAs were developed and transiently transfected into HSC-T6 cells using Lipofectamine 2000. HMGB1 expression was evaluated by real-time polymerase chain reaction (PCR) and Western blotting analysis. Expression of α-smooth muscle actin (α-SMA) and collagen types Ⅰ and Ⅲ was evaluated by real-time PCR. Cell proliferation and the cell cycle were determined using the methyl thiazolyl tetrazolium method. Fundically, collagen content in HSC supernatant was evaluated by an enzyme- linked immunosorbent assay .RESULTS: The results showed that HMGB1 was upregulated during liver fibrosis and that its expression was closely correlat ed with the deposition of collagen. siRNA molecules were successfully transfected into HSCs and induced inhibition of HMGB1 expression in a time-dependent manner. Moreover, HMGB1 siRNA treatment inhibited synthesis of α-SMA and collagen types I and III in transfected HSCs.CONCLUSION: This study suggests a significant functional role for HMGB1 in the development of liver fibrosis. It also demonstrates that downregulation of HMGB1 expression might be a potential strategy to treat liver fibrosis.