title: The Src inhibitor dasatinib accelerates the differentiation of human bone marrow-derived mesenchymal stromal cells into osteoblasts.
abstract: BACKGROUND
  The proto-oncogene Src is an important non-receptor protein tyrosine kinase involved in signaling pathways that control cell adhesion, growth, migration and differentiation. It negatively regulates osteoblast activity, and, as such, its inhibition is a potential means to prevent bone loss. Dasatinib is a new dual Src/Bcr-Abl tyrosine kinase inhibitor initially developed for the treatment of chronic myeloid leukemia. It has also shown promising results in preclinical studies in various solid tumors. However, its effects on the differentiation of human osteoblasts have never been examined.
  
  
  METHODS
  We evaluated the effects of dasatinib on bone marrow-derived mesenchymal stromal cells (MSC) differentiation into osteoblasts, in the presence or absence of a mixture of dexamethasone, ascorbic acid and beta-glycerophosphate (DAG) for up to 21 days. The differentiation kinetics was assessed by evaluating mineralization of the extracellular matrix, alkaline phosphatase (ALP) activity, and expression of osteoblastic markers (receptor activator of nuclear factor kappa B ligand [RANKL], bone sialoprotein [BSP], osteopontin [OPN]).
  
  
  RESULTS
  Dasatinib significantly increased the activity of ALP and the level of calcium deposition in MSC cultured with DAG after, respectively, 7 and 14 days; it upregulated the expression of BSP and OPN genes independently of DAG; and it markedly downregulated the expression of RANKL gene and protein (decrease in RANKL/OPG ratio), the key factor that stimulates osteoclast differentiation and activity.
  
  
  CONCLUSIONS
  Our results suggest a dual role for dasatinib in both (i) stimulating osteoblast differentiation leading to a direct increase in bone formation, and (ii) downregulating RANKL synthesis by osteoblasts leading to an indirect inhibition of osteoclastogenesis. Thus, dasatinib is a potentially interesting candidate drug for the treatment of osteolysis through its dual effect on bone metabolism.
authors.affiliation: Laboratoire d'Hematologie Experimentale, Institut Jules Bordet, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Hichame
authors.initials: H
authors.lastname: Id Boufker
authors.forename: Laurence
authors.initials: L
authors.lastname: Lagneaux
authors.forename: Mehdi
authors.initials: M
authors.lastname: Najar
authors.forename: Martine
authors.initials: M
authors.lastname: Piccart
authors.forename: Ghanem
authors.initials: G
authors.lastname: Ghanem
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Body
authors.forename: Fabrice
authors.initials: F
authors.lastname: Journé
mesh_terms: D000293:Adolescent; D000328:Adult; D000469:Alkaline Phosphatase / Q000378:metabolism; D001205:Ascorbic Acid / Q000494:pharmacology; D001854:Bone Marrow Cells / Q000187:drug effects* / Q000201:enzymology; D002113:Calcification, Physiologic / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects* / Q000235:genetics; D049109:Cell Proliferation / Q000187:drug effects; D002469:Cell Separation; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D000069439:Dasatinib; D003907:Dexamethasone / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D005994:Glycerophosphates / Q000494:pharmacology; D006801:Humans; D058574:Integrin-Binding Sialoprotein; D007700:Kinetics; D059630:Mesenchymal Stem Cells / Q000187:drug effects* / Q000201:enzymology; D008875:Middle Aged; D010006:Osteoblasts / Q000187:drug effects* / Q000201:enzymology; D010012:Osteogenesis / Q000187:drug effects* / Q000235:genetics; D053495:Osteopontin / Q000378:metabolism; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D000090063:Proto-Oncogene Mas; D011743:Pyrimidines / Q000494:pharmacology*; D053245:RANK Ligand / Q000378:metabolism; D012795:Sialoglycoproteins / Q000378:metabolism; D013844:Thiazoles / Q000494:pharmacology*; D055815:Young Adult; D019061:src-Family Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D005994:Glycerophosphates; C546871:IBSP protein, human; D058574:Integrin-Binding Sialoprotein; C000715470:MAS1 protein, human; D047428:Protein Kinase Inhibitors; D000090063:Proto-Oncogene Mas; D011743:Pyrimidines; D053245:RANK Ligand; C506895:SPP1 protein, human; D012795:Sialoglycoproteins; C505688:TNFSF11 protein, human; D013844:Thiazoles; D053495:Osteopontin; D003907:Dexamethasone; D019061:src-Family Kinases; D000469:Alkaline Phosphatase; D001205:Ascorbic Acid; D000069439:Dasatinib; C031463:beta-glycerophosphoric acid