title: The role of Raf kinase inhibitor protein in rheumatoid fibroblast-like synoviocytes invasiveness and cytokine and matrix metalloproteinase expression.
abstract: Fibroblast-like synoviocytes (FLS) play an important role in the pathogenesis of rheumatoid arthritis. Raf kinase inhibitor protein (RKIP) negatively regulates the Raf/MEK/ERK and NF-κB pathway. The role of RKIP in rheumatoid FLS is unknown. The purpose of the present study was to investigate the function of RKIP in rheumatoid FLS. Rheumatoid FLS were transfected with either RKIP-expressing plasmids or RKIP small interfering RNA (siRNA). RKIP protein was detected in rheumatoid synovial tissue (ST) and FLS. RKIP overexpression significantly decreased IL-6 mRNA expression in TNF-α-stimulated rheumatoid FLS. RKIP overexpression also showed a decreased trend in IL-8, MMP-1, and MMP-3 mRNA expression in TNF-α-stimulated rheumatoid FLS. RKIP silencing resulted in significantly increased MMP-1 and MMP-3 mRNA expression in TNF-α-stimulated rheumatoid FLS. RKIP silencing also increased IL-6 and IL-8 mRNA expression in TNF-α-stimulated rheumatoid FLS, but this increase did not reach statistical significance. TNF-α-induced ERK and NF-κB activation was suppressed in FLS with RKIP overexpression. RKIP silencing resulted in a significantly higher invasion index in TNF-α-stimulated rheumatoid FLS compared to controls. These results suggest that RKIP might be a potential therapeutic target for rheumatoid arthritis.
authors.affiliation: Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Joong Kyong
authors.initials: JK
authors.lastname: Ahn
authors.forename: Ji-Won
authors.initials: JW
authors.lastname: Hwang
authors.forename: Eun-Kyung
authors.initials: EK
authors.lastname: Bae
authors.forename: Jaejoon
authors.initials: J
authors.lastname: Lee
authors.forename: Chan Hong
authors.initials: CH
authors.lastname: Jeon
authors.forename: Eun-Mi
authors.initials: EM
authors.lastname: Koh
authors.forename: Hoon-Suk
authors.initials: HS
authors.lastname: Cha
mesh_terms: D001172:Arthritis, Rheumatoid / Q000378:metabolism* / Q000473:pathology*; D002478:Cells, Cultured; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis / Q000235:genetics; D016209:Interleukin-8 / Q000096:biosynthesis / Q000235:genetics; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D020781:Matrix Metalloproteinase 1 / Q000096:biosynthesis / Q000235:genetics; D019278:Matrix Metalloproteinase 3 / Q000096:biosynthesis / Q000235:genetics; D016328:NF-kappa B / Q000378:metabolism; D049488:Phosphatidylethanolamine Binding Protein / Q000378:metabolism*; D034622:RNA Interference; D012333:RNA, Messenger / Q000096:biosynthesis; D034741:RNA, Small Interfering; D015398:Signal Transduction; D013583:Synovial Membrane / Q000378:metabolism / Q000473:pathology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D048490:raf Kinases / Q000378:metabolism
chemical_list: D015850:Interleukin-6; D016209:Interleukin-8; D016328:NF-kappa B; D049488:Phosphatidylethanolamine Binding Protein; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D014409:Tumor Necrosis Factor-alpha; D048490:raf Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D020930:MAP Kinase Kinase Kinases; D019278:Matrix Metalloproteinase 3; D020781:Matrix Metalloproteinase 1