Induction of matrix metalloproteinase-1 by small interfering RNA targeting connective tissue growth factor in dermal fibroblasts from patients with systemic sclerosis.

We aimed to evaluate the effect of small interfering RNA (siRNA) targeting CTGF on extracellular matrices (ECMs) metabolism in normal and SSc fibroblasts. Normal and SSc fibroblasts were transfected with CTGF-specific siRNAs to silence CTGF synthesis. After silencing CTGF, production of type I collagen and matrix metalloproteinase (MMP)-1 by fibroblasts stimulated with TGF-beta was examined. Then quantitative analyses of protein production or mRNA expression of type I collagen, MMP-1,-2,-9 and tissue inhibitor of metalloproteinase (TIMP)-1 with TGF-beta stimulation were carried out. Furthermore, after silencing CTGF, proliferations of normal and SSc fibroblasts were investigated. CTGF-specific siRNA significantly reduced CTGF production. The production of type I collagen was significantly reduced by CTGF silencing in normal fibroblasts. The CTGF silencing significantly increased the production of MMP-1 and decreased the production of TIMP-1 in SSc fibroblasts. The mRNA expression of MMP-1 was increased in CTGF-silenced SSc fibroblasts, but not in normal fibroblasts. There were no significant changes in the production or mRNA expression of other ECM-related genes in normal and SSc fibroblasts. Fibroblast proliferations were suppressed by CTGF silencing in normal and SSc fibroblasts. Our data showed that MMP-1 was increased by CTGF-specific siRNA transfection only in SSc fibroblasts. RNAi targeting CTGF could be a novel therapeutic strategy for SSc.