TGF-β1 can be regulated by NDRG2 via the NF-κB pathway in hypoxia-induced liver fibrosis

BACKGROUND: The identification of the important elements that control hepatic stellate cell (HSC) activation will expand our understanding of the mechanism of liver fibrosis induced by hypoxia and affect the outcome of clinical treatment. A previous research demonstrated that N-Myc downstream-regulated gene 2 (NDRG2) is a potential regulator of fibrosis and a downstream target gene of hypoxia-inducible factor 1 (HIF-1). In this research, we studied the expression and function of NDRG2 in liver fibrosis induced by hypoxia. METHODS: LX-2 cells/NF-κB-silenced LX-2 cells were exposed to hypoxic conditions (1% O(2)) to activate HSCs in vitro. The protein and mRNA expression levels of NDRG2, α-SMA and transforming growth factor beta 1 (TGF-β1) were evaluated by western blotting and real-time polymerase chain reaction (RT-PCR), respectively. Functional studies were performed using adenovirus-mediated gene upregulation. RESULTS: The NDRG2 mRNA and protein levels were reduced under hypoxic conditions in LX-2 cells and overexpression of NDRG2 resulted in a decrease in the expression of TGF-β1 and α-SMA. Interestingly, no relationship was observed between NDRG2 and TGF-β1 when the NF-κB pathway was blocked, which indicates that NDRG2 can regulate the expression of TGF-β1 in LX-2 cells via the NF-κB pathway under hypoxic conditions. CONCLUSIONS: NDRG2 may regulate the expression of TGF-β1 via the NF-κB pathway and may be a novel therapeutic target for liver fibrosis induced by hypoxia.