title: CP690,550 inhibits oncostatin M-induced JAK/STAT signaling pathway in rheumatoid synoviocytes.
abstract: BACKGROUND
  Interleukin (IL)-6-type cytokines exert their effects through activation of the Janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling cascade. The JAK/STAT pathways play an important role in rheumatoid arthritis, since JAK inhibitors have exhibited dramatic effects on rheumatoid arthritis (RA) in clinical trials. In this study, we investigated the molecular effects of a small molecule JAK inhibitor, CP690,550 on the JAK/STAT signaling pathways and examined the role of JAK kinases in rheumatoid synovitis.
  
  
  METHODS
  Fibroblast-like synoviocytes (FLS) were isolated from RA patients and stimulated with recombinant oncostatin M (OSM). The cellular supernatants were analyzed using cytokine protein chips. IL-6 mRNA and protein expression were analyzed by real-time PCR method and ELISA, respectively. Protein phosphorylation of rheumatoid synoviocytes was assessed by Western blot using phospho-specific antibodies.
  
  
  RESULTS
  OSM was found to be a potent inducer of IL-6 in FLS. OSM stimulation elicited rapid phosphorylation of STATs suggesting activation of the JAK/STAT pathway in FLS. CP690,550 pretreatment completely abrogated the OSM-induced production of IL-6, as well as OSM-induced JAK/STAT, and activation of mitogen-activated kinases (MAPKs) in FLS.
  
  
  CONCLUSIONS
  These findings suggest that IL-6-type cytokines contribute to rheumatoid synovitis through activation of the JAK/STAT pathway in rheumatoid synoviocytes. Inhibition of these pro-inflammatory signaling pathways by CP690,550 could be important in the treatment of RA.
authors.affiliation: Department of Rheumatology and Clinical Research Center, Nagasaki Medical Center, Kubara 2-1001-1, Omura 856-8652, Japan. migita@nmc.hosp.go.jp
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Migita
authors.forename: Atsumasa
authors.initials: A
authors.lastname: Komori
authors.forename: Takafumi
authors.initials: T
authors.lastname: Torigoshi
authors.forename: Yumi
authors.initials: Y
authors.lastname: Maeda
authors.forename: Yasumori
authors.initials: Y
authors.lastname: Izumi
authors.forename: Yuka
authors.initials: Y
authors.lastname: Jiuchi
authors.forename: Taiichiro
authors.initials: T
authors.lastname: Miyashita
authors.forename: Minoru
authors.initials: M
authors.lastname: Nakamura
authors.forename: Satoru
authors.initials: S
authors.lastname: Motokawa
authors.forename: Hiromi
authors.initials: H
authors.lastname: Ishibashi
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D001172:Arthritis, Rheumatoid / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D001562:Benzimidazoles / Q000494:pharmacology; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004347:Drug Interactions; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D053613:Janus Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D053614:Janus Kinase 2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D053616:Janus Kinase 3 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D053683:Oncostatin M / Q000494:pharmacology; D010880:Piperidines; D011728:Pyridones / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology*; D011758:Pyrroles / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D050794:STAT1 Transcription Factor / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000378:metabolism; D050799:STAT5 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D013583:Synovial Membrane / Q000166:cytology; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: C524063:2-tert-butyl-9-fluoro-3,6-dihydro-7H-benz(h)imidazo(4,5-f)isoquinoline-7-one; D000970:Antineoplastic Agents; D001562:Benzimidazoles; D017077:Culture Media, Conditioned; C508600:IL6 protein, human; D015850:Interleukin-6; D010880:Piperidines; D011728:Pyridones; D011743:Pyrimidines; D011758:Pyrroles; D012333:RNA, Messenger; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D050799:STAT5 Transcription Factor; D053683:Oncostatin M; C479163:tofacitinib; C507904:JAK1 protein, human; C507924:JAK2 protein, human; C507933:JAK3 protein, human; D053613:Janus Kinase 1; D053614:Janus Kinase 2; D053616:Janus Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases