cyclin-d1 and Cicatrix--Hypertrophic

The molecular mechanisms behind the pathogenesis of postburn hypertrophic scar (HS) remain unclear. Here, we investigate the role of the IL-6 trans-signaling-signal transducer and activator of transcription (STAT)3 pathway in HS fibroblasts (HSFs) derived from post-burn HS skin. HSF showed increased Tyr 705 STAT3 phosphorylation compared with normal fibroblast (NF) after IL-6•IL-6Rα stimulation by immunoassays. The endogenous STAT3 target gene, SOCS3, was upregulated in HSFs and showed increased STAT3 binding on its promoter relative to NFs in a chromatin immunoprecipitation assay. We observed that the cell-surface signaling transducer glycoprotein 130 is upregulated in HSFs by quantitative real-time reverse-transcriptase-PCR and flow cytometry. The production of excessive extracellular matrix (ECM), including the expression of alpha2 (1) procollagen (Col1A2) and fibronectin 1 (FN), was seen in HSFs. A STAT3 peptide inhibitor abrogated FN and Col1A2 gene expression in HSFs indicating involvement of STAT3 in ECM production. The cellular proliferation markers Cyclin D1, Bcl-Xl, and c-Myc were also upregulated in HSF, and knockdown of STAT3 by small interfering RNA attenuated c-Myc expression indicating the essential role of STAT3 in fibroblast proliferation. Taken together, our results suggest that the IL-6 trans-signaling-STAT3 pathway may have an integral role in HS pathogenesis, and disruption of this pathway could be a potential therapeutic strategy for the treatment of post-burn HS.

Topics: bcl-X Protein; Cell Proliferation; Cicatrix, Hypertrophic; Collagen Type I; Cyclin D1; Extracellular Matrix; Fibroblasts; Fibronectins; Glycoproteins; Humans; Interleukin-6; Proto-Oncogene Proteins c-myc; Signal Transduction; STAT3 Transcription Factor; Up-Regulation