title: High glucose induces vascular endothelial growth factor production in human synovial fibroblasts through reactive oxygen species generation.
abstract: BACKGROUND
  Diabetes is an independent risk factor of osteoarthritis (OA). Angiogenesis is essential for the progression of OA. Here, we investigated the intracellular signaling pathways involved in high glucose (HG)-induced vascular endothelial growth factor (VEGF) expression in human synovial fibroblast cells.
  
  
  METHODS
  HG-mediated VEGF expression was assessed with qPCR and ELISA. The mechanisms of action of HG in different signaling pathways were studied using Western blotting. Knockdown of proteins was achieved by transfection with siRNA. Chromatin immunoprecipitation assays were used to study in vivo binding of c-Jun to the VEGF promoter.
  
  
  RESULTS
  Stimulation of OA synovial fibroblasts (OASF) with HG induced concentration- and time-dependent increases in VEGF expression. Treatment of OASF with HG increased reactive oxygen species (ROS) generation. Pretreatment with NADPH oxidase inhibitor (APO or DPI), ROS scavenger (NAC), PI3K inhibitor (Ly294002 or wortmannin), Akt inhibitor, or AP-1 inhibitor (curcumin or tanshinone IIA) blocked the HG-induced VEGF production. HG also increased PI3K and Akt activation. Treatment of OASF with HG increased the accumulation of phosphorylated c-Jun in the nucleus, AP-1-luciferase activity, and c-Jun binding to the AP-1 element on the VEGF promoter.
  
  
  CONCLUSIONS
  Our results suggest that the HG increases VEGF expression in human synovial fibroblasts via the ROS, PI3K, Akt, c-Jun and AP-1 signaling pathway.
  
  
  CONCLUSIONS
  We link high glucose on VEGF expression in osteoarthritis.
authors.affiliation: Department of Orthopaedic Surgery, China Medical University Hospital, Taichung, Taiwan.
authors.forename: Chun-Hao
authors.initials: CH
authors.lastname: Tsai
authors.forename: Yi-Chun
authors.initials: YC
authors.lastname: Chiang
authors.forename: Hsien-Te
authors.initials: HT
authors.lastname: Chen
authors.forename: Po-Hao
authors.initials: PH
authors.lastname: Huang
authors.forename: Horng-Chaung
authors.initials: HC
authors.lastname: Hsu
authors.forename: Chih-Hsin
authors.initials: CH
authors.lastname: Tang
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000730:Androstadienes / Q000494:pharmacology; D002867:Chromones / Q000494:pharmacology; D003474:Curcumin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005786:Gene Expression Regulation / Q000187:drug effects; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D017746:Joint Capsule / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009025:Morpholines / Q000494:pharmacology; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D010003:Osteoarthritis / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D061251:Primary Cell Culture; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D017382:Reactive Oxygen Species / Q000819:agonists / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D018808:Transcription Factor AP-1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D000077191:Wortmannin
chemical_list: D000111:Acetylcysteine; D000730:Androstadienes; D002867:Chromones; D003474:Curcumin; D005947:Glucose; D009025:Morpholines; D019255:NADPH Oxidases; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D016755:Proto-Oncogene Proteins c-jun; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D018808:Transcription Factor AP-1; D042461:Vascular Endothelial Growth Factor A; D000077191:Wortmannin; C467484:VEGFA protein, human; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one