Effect of integrin-linked kinase towards matrix metalloproteinase-9/tissue inhibitor of metalloproteinase-1 in the process of TGF-β1-induced epithelial-mesenchymal transition of renal tubular cell

Abstract

Objective To investigate the possible regulating effect of integrin-linked kinase (ILK) towards matrix metalloproteinase-9/tissue inhibitor of metalloproteinase-1 (MMP-9/TIMP-1) ratio in the process of transforming growth factor-β1 (TGF-β1)-induced epithelial-mesenchymal transition (EMT) in human kidney proximal tubular epithelial (HK-2) cells. Methods HK-2 cells were cultured and stimulated with 10 ng/ml TGF-β1. Specific ILK-small interfering RNA (ILK-siRNA) was used to inhibit ILK expression. The characteristic epithelial marker (E-cadherin) and mesenchymal marker (α-SMA) of EMT were examined by Real-time reverse transcription polymerase chain reaction (real-time RT-PCR) and Western blot. The expressions of ILK, MMP-9, and TIMP-1 were also examined, to determine the regulating effect of ILK towards MMP-9/TIMP-1 ratio. Results In the HK-2 cells cultured with TGF-β1, the expression of E-cadherin decreased, and α-SMA expression increased; overexpression of ILK and an abnormal changing of MMP-9/TIMP-1 ratio were observed. ILK inhibition by ILK-siRNA could adjust MMP-9/TIMP-1 ratio to near normal. Meanwhile, the overexpressed ILK and α-SMA were decreased. Conclusions Our data indi-cates that ILK-siRNA successfully inhibits ILK expression, which regulates the MMP-9/TIMP-1 ratio in HK-2 cells. The inhibition of ILK expression suppresses TGF-β1-induced EMT partially. Key words: Transforming growth factor beta1; Kidney tubules; Epithelial cells; Biotransformation; Integrins; Matrix metalloproteinase 9; Tissue inhibitor of metalloproteinase-1