title: Angiogenic growth factors inhibit chondrocyte ageing in osteoarthritis: potential involvement of catabolic stress-induced overexpression of caveolin-1 in cellular ageing.
abstract: OBJECTIVE
  Recently, attention has been attracted by the finding that overexpression of caveolin-1 induces cellular senescence in age-related diseases. We aimed to ascertain whether angiogenic growth factors (AGFs) can inhibit interleukin (IL)-1beta-induced senescence in human chondrocytes by downregulation of caveolin-1.
  
  
  METHODS
  We investigated the intracellular signalling pathways involved in chondrocyte ageing. Human chondrocytes were isolated from the articular cartilage of patients undergoing arthroplastic knee surgery in osteoarthritis (OA). Chondrocytes were stimulated with or without IL-1beta (10 ng/mL) in the presence or absence of vascular endothelial growth factor, basic fibroblast growth factor or hepatocyte growth factor (20 ng/mL). After 72-h incubation, we observed the expression of caveolin-1 in human chondrocytes by immunohistochemistry, and analysed the protein levels of caveolin-1 by Western blot. We examined the time-course of phosphorylation patterns of mammalian mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3-K) by Western blot, and used several specific protein kinase inhibitors to evaluate the involvement of the intracellular signalling pathways. Also, chondrocyte replicative lifespan was analyzed in the presence or absence of AGFs.
  
  
  RESULTS
  Treatment with AGFs inhibited IL-1beta-induced overexpression of caveolin-1 in human OA chondrocytes. Treatment with AGFs all down-regulated protein levels of IL-1beta-accelerated expression of caveolin-1 in chondrocytes. IL-1beta significantly decreased the cellular replicative lifespan in chondrocytes. Treatment with AGFs prevented the IL-1beta-induced shortening of chondrocyte replicative lifespan. The specific inhibitors for MAPK/extracellular signal-regulated kinase and PI3-K cancelled the AGF-induced downregulation of overexpression of caveolin-1.
  
  
  CONCLUSIONS
  Our results suggest that AGFs downregulated IL-1beta-induced chondrocyte ageing and overexpression of caveolin-1 in human chondrocytes, which is mediated by kinase cascades involving the p42/44 MAP kinase and PI3-K/Akt signalling pathways.
authors.affiliation: Department of Frontier Medicine, Institute of Medical Science, St. Marianna University School of Medicine, Kawasaki, Japan. yudo@marianna-u.ac.jp
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yudoh
authors.forename: Yeqing
authors.initials: Y
authors.lastname: Shi
authors.forename: Rie
authors.initials: R
authors.lastname: Karasawa
mesh_terms: D051242:Caveolin 1 / Q000378:metabolism*; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects / Q000502:physiology; D019902:Chondrocytes / Q000187:drug effects* / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism / Q000494:pharmacology; D017228:Hepatocyte Growth Factor / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D007150:Immunohistochemistry; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism* / Q000494:pharmacology; D053583:Interleukin-1beta / Q000378:metabolism / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D010003:Osteoarthritis / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D013312:Stress, Physiological / Q000187:drug effects / Q000502:physiology; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: C495540:CAV1 protein, human; D051242:Caveolin 1; D036341:Intercellular Signaling Peptides and Proteins; D053583:Interleukin-1beta; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D016222:Fibroblast Growth Factor 2; D017228:Hepatocyte Growth Factor; D019869:Phosphatidylinositol 3-Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases