Renal
fibrosis is a common pathological pathway of various
chronic kidney diseases progressing to
end-stage renal disease and is characterized by tubular
atrophy, fibroblast/myofibroblast activation and excessive deposition of extracellular matrix (ECM). N-Myc downstream-regulated gene-2 (NDRG2) is reported to be associated with
liver fibrosis in rats. However, the
biological function of NDRG2 in renal
fibrosis remains unclear. Therefore, we investigate the effect of NDRG2 on renal
fibrosis and the underlying mechanism of NDRG2 in TGF-β1-induced renal tubular epithelial cells (HK-2). Our results show that TGF-β1 down-regulates NDRG2
mRNA and
protein expression in HK-2 cells. Moreover, NDRG2 knockdown dramatically reduces the TGF-β1-induced
protein and
mRNA of
E-cadherin and increases the TGF-β1-induced
protein and
mRNA expression level of α-SMA,
Vimentin, Snail, Col-I, Col-III and FN; this is reversed by NDRG2 overexpression. Furthermore, NDRG2 silencing significantly increases the phosphorylation level of Smad3 (p-Smad3), which is decreased by NDRG2 overexpression, although these have no effect on the
protein expression of p-Smad2 and Smad7. In addition, SIS3, a specific inhibitor of Smad3 phosphorylation, partly reverses the effect of NDRG2 knockdown on the
protein and
mRNA expression of epithelial-mesenchymal transition (EMT) markers and ECM components in TGF-β1-induced HK-2 cells. Taken together, our results indicate that NDRG2 knockdown promotes renal
fibrosis through its effect on the
protein and
mRNA expression of EMT markers and ECM components by regulating the downstream Smad3 signaling pathway in renal tubular epithelial cells. Modulation of NDRG2 expression might provide a new
therapy for renal
fibrosis.