TSG-6 Inhibits the Growth of Keloid Fibroblasts Via Mediating the TGF-β1/Smad Signaling Pathway
Xinyi Li, Xin-Yi Li, Xiaojuan Weng, xiao-jing Li, xiao-jing Li, Xiao-Yu Tian
Abstract
BACKGROUND: The cytokine TNF-α-stimulated gene-6 (TSG-6) had been verified to have a certain inhibitory effect on the inflammation. During wound healing, fibroblasts increasingly proliferated and deposited collagen fibers, leading to the formation of pathological scars. We sought to elucidate the mechanism by which the TGF-β1/Smad pathway was mediated by TSG-6 in human keloid fibroblasts. MATERIALS AND METHODS: Human keloid fibroblast cells were isolated from keloid tissue by enzyme digestion and identified by immunocytochemistry. Lentiviral vectors pLVX-puro-TSG-6 and pLVX-shRNA1-TSG-6 were constructed which were then transfected into human keloid fibroblasts. The mRNA and protein levels of TSG-6 were detected respectively by RT-PCR and western blot assay. The intracellular localization of TGF-β1-induced proteins and phosphorylated (p)-Smad2/3 in keloid fibroblasts were investigated using an immunofluorescence assay. Plasminogen activator inhibitor-1 (PAI-1) transcriptional activity was detected by RT-PCR. RESULTS: TSG-6 could effectively interfere the TGF-β1/Smad signal transduction pathway in keloid fibroblasts rather than in normal fibroblasts. The phosphorylation levels of Smad2/3 were notably reduced by TSG-6 treatment. TSG-6 blocked the complex formation of Smad2/3/4, and their nuclear translocation. However, it upregulated Smad7 expression, presenting dose dependence. PAI-1 was also suppressed by TSG-6 treatment. CONCLUSIONS: TSG-6 inhibits proliferation by inducing apoptosis in keloid fibroblasts, which may be associated with TGF-β1/Smad pathway.