title: The effect of osteopontin on the adhesion of calcium oxalate crystals to Madin-Darby canine kidney cells.
abstract: OBJECTIVE
  We have recently reported that osteopontin protein (OPN) is present in calcium-containing urinary calculi and in rat distal tubular cells and that it is an important substance of the matrix in urinary stone formation. To investigate how OPN participates in urinary stone formation, we assessed the role of OPN in the adhesion of the surfaces of Madin-Darby canine kidney (MDCK) cells, which are distal tubular cells of the dog, to calcium oxalate crystals.
  
  
  METHODS
  We cultured MDCK cells with OPN, thrombin, which is an OPN inhibitor, Arg-Gly-Asp peptide and Arg-Gly-Glu peptide as a control for Arg-Gly-Asp peptide, and examined changes in adhesion of calcium oxalate crystals to the cells by scanning electron microscopy and the calcium (45Ca) concentration around the cells.
  
  
  RESULTS
  The 45Ca concentration in calcium oxalate crystals adhering to MDCK cells was about 1.4 times higher in MDCK cells incubated with OPN than in an MDCK-cell-negative group, and was about one half that in MDCK cells incubated with thrombin than in the group without MDCK cells.
  
  
  CONCLUSIONS
  OPN is considered to be an accelerator of urinary stone formation because of the increase in adhesion of calcium oxalate crystals to the renal distal tubular epithelium in the presence of OPN. These findings suggest that OPN plays an important role in the formation of calcium-containing urinary stones.
authors.affiliation: Department of Urology, Kinki University School of Medicine, Osaka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yamate
authors.forename: K
authors.initials: K
authors.lastname: Kohri
authors.forename: T
authors.initials: T
authors.lastname: Umekawa
authors.forename: N
authors.initials: N
authors.lastname: Amasaki
authors.forename: N
authors.initials: N
authors.lastname: Amasaki
authors.forename: Y
authors.initials: Y
authors.lastname: Isikawa
authors.forename: M
authors.initials: M
authors.lastname: Iguchi
authors.forename: T
authors.initials: T
authors.lastname: Kurita
mesh_terms: D000818:Animals; D002129:Calcium Oxalate / Q000494:pharmacology*; D002448:Cell Adhesion / Q000187:drug effects*; D002478:Cells, Cultured; D003460:Crystallization; D004285:Dogs; D007668:Kidney / Q000166:cytology*; D008855:Microscopy, Electron, Scanning; D053495:Osteopontin; D010750:Phosphoproteins / Q000494:pharmacology*; D012795:Sialoglycoproteins / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D013917:Thrombin / Q000494:pharmacology; D014545:Urinary Calculi / Q000209:etiology
chemical_list: D010750:Phosphoproteins; D012795:Sialoglycoproteins; C506897:Spp1 protein, rat; D053495:Osteopontin; D002129:Calcium Oxalate; D013917:Thrombin