PDGF-driven proliferation, migration, and IL8 chemokine secretion in human corneal fibroblasts involve JAK2-STAT3 signaling pathway

摘要

Purpose: Platelet-derived growth factor(PDGF) is associated with corneal fibroblast migration andproliferation and plays an important role in corneal wound healing.However, the intracellular mechanisms of PDGF-mediated functions incorneal fibroblasts are poorly understood. We tested the hypothesisthat PDGF functional activities in the cornea involve the Januskinase-2/signal transducers and activators of transcription-3(JAK2-STAT3) signaling pathway and whether PDGF induces the expressionof suppressors of cytokine signaling 3 (SOCS3), belonging to the novelfamily of feedback regulators of cytokine and growth factor activities.Methods: Human corneal fibroblast (HSF)cultures were used as an in vitro model for functional analysis.Real-time polymerase chain reactions were performed to quantify geneexpression. Immunoprecipitation and immunoblotting techniques were usedto measure protein expression. Cell growth, migration, and ELISA assayswere used for functional validation. Results: Low endogenous levels of STAT3and SOCS3 mRNA and protein expression were noted in HSFs. PDGFtreatment of HSF significantly induced SOCS3 mRNA (3.0–4.5 fold) andprotein (1.5–2.5 fold) expression in a time-dependent manner.Similarly, PDGF treatment of HSF significantly increased STAT3 proteinexpression at two tested time points (2.5–2.96 fold). Cultures exposedto vehicle (control) did not show any change in SOCS3 and STAT3 mRNA orprotein expression. An addition of AG-490, a selective inhibitor of theJAK2-STAT3 pathway, significantly inhibited PDGF-mediated STAT3induction and cell growth and migration in HSF. We also observed thatPDGF induced interleukin-8 (IL8) chemokine secretion (2 fold) andAG-490 inhibited IL8 secretion. Conclusions: Our data showed that PDGFinduced STAT3, SOCS3, and IL8 chemokine secretion in human cornealfibroblasts. Further, PDGF-induced cell growth, migration, and IL8secretion in corneal fibroblast involve the JAK2-STAT3 signalingpathway.