TGF-β1 gene silencing for treating liver fibrosis

Small interfering RNA (siRNA) and short hairpin RNA (shRNA) targeting different regions of transforming growth factor β1 (TGF-β1) mRNA were designed and the silencing effect was determined after transfection into immortalized rat liver stellate cells (HSC-T6). There was not only significant decrease in TGF-β1, tissue inhibitor of metalloproteinase 1 (TIMP-1), R-smooth muscle actin (R-SMA) and type I collagen after transfection with TGF-β1 siRNAs, but also synergism in gene silencing when siRNAs targeting two different start sites were used as a pool for transfection. The two siRNA sequences which efficiently inhibited TGF-β1 gene expression were converted to shRNAs via cloning into the pSilencer1.0. There was significant decrease in TGF-β1 and TIMP-1 when HSC-T6 cells were transfected with pshRNA targeting the same regions of TGF-β1 mRNA as siRNAs. Furthermore, TGF-β1 gene silencing in HSC-T6 cells significantly decreased the levels of inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β). In conclusion, both siRNA and shRNA showed sequence-specific and dose dependent TGF-β1 gene silencing and have the potential to treat liver fibrosis.