title: Analyses on the mechanisms that underlie the chondroprotective properties of calcitonin.
abstract: BACKGROUND
  Calcitonin (CT) has recently been shown to display chondroprotective effects. Here, we investigate the putative mechanisms by which CT delivers these actions.
  
  
  METHODS
  Immortalized C-28/I2 cells or primary adult human articular chondrocytes (AHAC) were cultured in high-density micromasses to investigate: (i) CT anabolic effects using qPCR and immuhistochemistry analysis; (ii) CT anti-apoptotic effects using quantitation of Bax/Bcl gene products ratio, TUNEL assay and caspase-3 expression; (iii) CT effects on CREB, COL2A1 and NFAT transcription factors.
  
  
  RESULTS
  CT (10(-10)-10(-8)nM) induced significant up-regulation of cartilage phenotypic markers (SOX9, COL2A1 and ACAN), with down-regulation of catabolic (MMP1 and MMP13 and ADAMTS5) gene products both in resting and inflammatory conditions. This was mirrored by an augmented production of type II collagen and accumulation of glycosaminoglycan- and proteoglycan-rich extracellular matrix in vitro. Mechanistic analyses revealed only partial involvement of cyclic AMP formation in these effects of CT. Congruently, using reporter assays for specific transcription factors, there was no indication for CREB activation, whereas the COL2A1 promoter was genuinely and directly activated by cell exposure to CT. Phenotypically, these mechanisms supported the ability of CT, whilst inactive on its own, to counteract the pro-apoptotic effects of IL-1β, demonstrated by TUNEL-positive staining of chondrocytes and ratio of BAX/BCL genes products.
  
  
  CONCLUSIONS
  These data may provide a novel lead for the development of CT-based chondroprotective strategies that rely on the engagement of mechanisms that lead to augmented chondrocyte anabolism and inhibited chondrocyte apoptosis.
authors.affiliation: The William Harvey Research Institute, Barts and The London School of Medicine, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, United Kingdom.
authors.forename: Karin V
authors.initials: KV
authors.lastname: Greco
authors.affiliation: The William Harvey Research Institute, Barts and The London School of Medicine, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, United Kingdom.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Nalesso
authors.affiliation: The William Harvey Research Institute, Barts and The London School of Medicine, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, United Kingdom.
authors.forename: Magdalena K
authors.initials: MK
authors.lastname: Kaneva
authors.affiliation: The William Harvey Research Institute, Barts and The London School of Medicine, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, United Kingdom.
authors.forename: Joanna
authors.initials: J
authors.lastname: Sherwood
authors.affiliation: The William Harvey Research Institute, Barts and The London School of Medicine, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, United Kingdom.
authors.forename: Asif J
authors.initials: AJ
authors.lastname: Iqbal
authors.affiliation: The William Harvey Research Institute, Barts and The London School of Medicine, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, United Kingdom.
authors.forename: Niloufar
authors.initials: N
authors.lastname: Moradi-Bidhendi
authors.affiliation: The William Harvey Research Institute, Barts and The London School of Medicine, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, United Kingdom.
authors.forename: Francesco
authors.initials: F
authors.lastname: Dell'Accio
authors.affiliation: The William Harvey Research Institute, Barts and The London School of Medicine, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, United Kingdom. Electronic address: m.perretti@qmul.ac.uk.
authors.forename: Mauro
authors.initials: M
authors.lastname: Perretti
mesh_terms: D051722:ADAM Proteins / Q000378:metabolism; D000071116:ADAMTS5 Protein; D053674:Aggrecans / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D015415:Biomarkers / Q000378:metabolism; D002116:Calcitonin / Q000494:pharmacology*; D002358:Cartilage, Articular / Q000166:cytology / Q000187:drug effects; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects* / Q000378:metabolism*; D024043:Collagen Type II / Q000096:biosynthesis / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D006025:Glycosaminoglycans / Q000096:biosynthesis; D006801:Humans; D020781:Matrix Metalloproteinase 1 / Q000378:metabolism; D053509:Matrix Metalloproteinase 13 / Q000378:metabolism; D020011:Protective Agents / Q000494:pharmacology*; D055758:SOX9 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: C508319:ACAN protein, human; D053674:Aggrecans; D015415:Biomarkers; C499177:COL2A1 protein, human; D024043:Collagen Type II; D006025:Glycosaminoglycans; D020011:Protective Agents; D055758:SOX9 Transcription Factor; C527932:SOX9 protein, human; D002116:Calcitonin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D051722:ADAM Proteins; D000071116:ADAMTS5 Protein; C121532:ADAMTS5 protein, human; C507079:MMP13 protein, human; D053509:Matrix Metalloproteinase 13; D020781:Matrix Metalloproteinase 1
keywords: Anabolism; Apoptosis; Calcitonin receptor; Cartilage; Osteoarthritis