Peroxisome proliferator-activated receptor-γ agonist inhibits collagen synthesis in human keloid fibroblasts by suppression of early growth response-1 expression through upregulation of miR-543 expression

A keloid is a benign skin tumor formed by an overgrowth of granulation tissue in affected patients. Peroxisome proliferator-activated receptor-γ (PPAR-γ) agonists were reported to be able to regulate extracellular matrix production in human dermal fibroblasts. This study explored the underlying molecular mechanism of PPAR-γ agonist troglitazone treatment for fibroblasts obtained from keloid patients. The data revealed that troglitazone treatment of keloid fibroblasts (KFs) downregulated the expression of early growth response-1 (Egr1) and collagen-1 (Col1). Level of Egr1 were closely associated with KF-induced fibrosis. The miRNA profiling data revealed that miR-543 was transcriptionally activated after troglitazone treatment. Bioinformatic analysis and experimental data showed that miR-543 was able to target Egr1. ELISA data confirmed that Col1 protein in the supernatant were modulated by the feedback regulatory axis of PPAR-γ agonist-induced miR-543 to inhibit Egr1 expression, whereas PPAR-γ antagonist treatment abolished such effect on Col1 suppression in KFs. This study demonstrated that the PPAR-γ agonist-mediated miR-543 and Egr1 signaling plays an important role in the suppression of collagen synthesis in KFs. Future in vivo studies are needed to confirm these in vitro data.