Epidermal growth factor increases prostaglandin E₂ production via ERK1/2 MAPK and NF-κB pathway in fibroblast like synoviocytes from patients with rheumatoid arthritis

Abstract

High concentration of epidermal growth factor (EGF) is found in the synovial fluid of rheumatoid arthritis (RA) that might imply the involvement of EGF in the pathogenesis of arthritic diseases. In order to investigate if EGF is involved in the regulation of cyclooxygenase-2 (COX-2) and the prostaglandin E2 (PGE2) production in fibroblast like synoviocytes (FLS) from patients with RA. The levels of COX-2 and microsomal prostaglandin E synthase-1 (mPGES-1) were evaluated using RT-PCR and Western blot analysis. Electrophoretic mobility shift assay (EMSA) was performed to investigate EGF mediated DNA binding activity of nuclear factor-κB (NF-κB). PGE2 levels were analyzed by ELISA. EGF enhanced both COX-2 protein and mRNA expressions. mPGES-1 mRNA level was also increased by EGF treatment. EGF also stimulated ERK1/2 MAPK activity and the inhibition of ERK1/2 by PD098059 (ERK1/2 specific inhibitor) resulted in the suppression of EGF-induced COX-2 expression. The DNA binding activity of NF-κB was remarkably increased by EGF treatment and the pretreatment of PD098059 abolished EGF-stimulated NF-κB activity. We also observed that the level of PGE2 was significantly elevated with the treatment of EGF in FLS, and the pretreatment of PD098059 abolished this stimulating effect. These results suggest that EGF is involved in the inflammatory process of RA by stimulating COX-2 expression and PGE2 production. And EGF enhanced PGE2 production appears to be mediated via ERK1/2 MAPK and NF-κB pathway in FLS.