title: Signal transduction pathways involved in the stimulation of tissue type plasminogen activator by interleukin-1alpha and Porphyromonas gingivalis in human osteosarcoma cells.
abstract: BACKGROUND
  Recently, evidences have shown that tissue type plasminogen activator (t-PA) may play an important role in the pathogenesis of periodontal diseases. However, the mechanisms and signal transduction pathways involved in the production of t-PA in human osteosarcoma cells are not fully understood.
  
  
  OBJECTIVE
  The purpose of this study was to investigate the caseinolytic activity in human osteosarcoma cell line U2OS cells stimulated with interleukin-1alpha (IL-1alpha) or Porphyromonas gingivalis in the absence or presence of p38 inhibitor SB203580, mitogen-activated protein kinase kinase (MEK) inhibitor U0126, and phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002.
  
  
  METHODS
  IL-1alpha and the supernatants of P. gingivalis were used to evaluate the caseinolytic activity in U2OS cells by using casein zymography and enzyme-linked immunosorbent assay (ELISA). Furthermore, to search possible signal transduction pathways, SB203580, U0126, and LY294002 were added to test how they modulated the caseinolytic activity.
  
  
  RESULTS
  Casein zymography exhibited a caseinolytic band with a molecular weight of approximately 70 kDa, suggestive of the presence of t-PA. Secretion of t-PA was found to be stimulated with IL-1alpha and P. gingivalis during a 2-day culture period (p < 0.05). From the results of casein zymography and ELISA, SB203580, U0126, and LY294002 significantly reduced the IL-1alpha or P. gingivalis-stimulated t-PA production, respectively (p < 0.05).
  
  
  CONCLUSIONS
  Our findings demonstrated that IL-1alpha and P. gingivalis enhance t-PA production in human osteosarcoma cells, and that the signal transduction pathways p38, MEK, and PI3K are involved in the inhibition of t-PA. SB203580, U0126, and LY294002 suppress t-PA production and/or activity and may therefore be valuable therapeutics in t-PA-mediated periodontal destruction, and might be proved clinically useful agents, in combination with standard treatment modalities, in the treatment of periodontitis.
authors.affiliation: Department of Periodontics, Chung Shan Medical University Hospital, Taichung, Taiwan.
authors.forename: Yu-Chao
authors.initials: YC
authors.lastname: Chang
authors.forename: Yung-Chuan
authors.initials: YC
authors.lastname: Ho
authors.forename: Lin Shin-Shen
authors.initials: LS
authors.lastname: Chou
authors.forename: Ming-Yung
authors.initials: MY
authors.lastname: Chou
authors.forename: Fu-Mei
authors.initials: FM
authors.lastname: Huang
mesh_terms: D002070:Butadienes / Q000494:pharmacology; D002364:Caseins / Q000378:metabolism*; D045744:Cell Line, Tumor; D002867:Chromones / Q000494:pharmacology; D017077:Culture Media, Conditioned; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D053582:Interleukin-1alpha / Q000502:physiology*; D020930:MAP Kinase Kinase Kinases / Q000037:antagonists & inhibitors / Q000502:physiology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D009025:Morpholines / Q000494:pharmacology; D009570:Nitriles / Q000494:pharmacology; D012516:Osteosarcoma; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D016966:Porphyromonas gingivalis / Q000502:physiology*; D011725:Pyridines / Q000494:pharmacology; D010959:Tissue Plasminogen Activator / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D015854:Up-Regulation / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology
chemical_list: D002070:Butadienes; D002364:Caseins; D002867:Chromones; D017077:Culture Media, Conditioned; D004791:Enzyme Inhibitors; D007093:Imidazoles; D053582:Interleukin-1alpha; D020930:MAP Kinase Kinase Kinases; D009025:Morpholines; D009570:Nitriles; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011725:Pyridines; D010959:Tissue Plasminogen Activator; D048051:p38 Mitogen-Activated Protein Kinases; C113580:U 0126; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C093642:SB 203580