title: The tyrosine kinase inhibitor dasatinib effectively blocks PDGF-induced orbital fibroblast activation.
abstract: BACKGROUND
  Graves' ophthalmopathy (GO) remains hard to treat. Excessive orbital fibroblast activation by platelet-derived growth factor (PDGF)-BB contributes to GO. The tyrosine kinase inhibitors (TKIs) imatinib mesylate and dasatinib both target PDGF-receptor tyrosine kinase activity, albeit with a different potency. We compared the efficacy of these TKIs on PDGF-BB-induced proliferation, and on cytokine and hyaluronan production by orbital fibroblasts. Also the capacity of dasatinib to suppress GO-associated gene expression in orbital tissue was examined.
  
  
  METHODS
  Orbital fibroblasts from four GO patients and five control subjects were used. The efficacy of the two TKIs was tested by: 1) pre-incubating orbital fibroblasts overnight with different TKI concentrations, followed by 24 h stimulation with PDGF-BB, 2) adding TKI and PDGF-BB simultaneously to the orbital fibroblasts in 24 h cultures. Proliferation was assessed by colorimetric assay. Hyaluronan and cytokine production were measured by ELISA. Furthermore, orbital tissue was obtained from a patient with active GO, and the effect of dasatinib on the expression levels of HAS2-, CCL2-, IL6-, and IL8-mRNA expression was examined by real-time quantitative PCR.
  
  
  RESULTS
  Pre-incubation of orbital fibroblasts with imatinib mesylate or dasatinib resulted in significant and dose-dependent inhibition of PDGF-BB-induced orbital fibroblast proliferation, and hyaluronan and cytokine production. Dasatinib exhibited these effects at far lower concentrations. The same results were observed in the setting where TKI and PDGF-BB treatments were commenced simultaneously. In orbital tissue from active GO, dasatinib significantly suppressed HAS2-, CCL2-, IL6- and IL8-mRNA levels.
  
  
  CONCLUSIONS
  Dasatinib may be a promising alternative to high-dose steroids in the treatment of GO.
authors.affiliation: Department of Immunology, Erasmus MC, University Medical Center, PO Box 2040, 3000, CA, Rotterdam, The Netherlands.
authors.forename: Sita
authors.initials: S
authors.lastname: Virakul
authors.forename: Virgil A S H
authors.initials: VA
authors.lastname: Dalm
authors.forename: Dion
authors.initials: D
authors.lastname: Paridaens
authors.forename: Willem A
authors.initials: WA
authors.lastname: van den Bosch
authors.forename: Nattiya
authors.initials: N
authors.lastname: Hirankarn
authors.forename: P Martin
authors.initials: PM
authors.lastname: van Hagen
authors.forename: Willem A
authors.initials: WA
authors.lastname: Dik
mesh_terms: D000077214:Becaplermin; D001549:Benzamides / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000235:genetics; D000069439:Dasatinib; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology; D014453:Glucuronosyltransferase / Q000235:genetics; D049970:Graves Ophthalmopathy / Q000188:drug therapy / Q000473:pathology; D006801:Humans; D000076002:Hyaluronan Synthases; D000068877:Imatinib Mesylate; D015850:Interleukin-6 / Q000235:genetics; D016209:Interleukin-8 / Q000235:genetics; D009915:Orbit / Q000473:pathology*; D010879:Piperazines / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D020574:Proto-Oncogene Proteins c-sis / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D013844:Thiazoles / Q000494:pharmacology*
chemical_list: D001549:Benzamides; C111835:CCL2 protein, human; C508606:CXCL8 protein, human; D018932:Chemokine CCL2; C508600:IL6 protein, human; D015850:Interleukin-6; D016209:Interleukin-8; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D020574:Proto-Oncogene Proteins c-sis; D011743:Pyrimidines; D012333:RNA, Messenger; D013844:Thiazoles; D000077214:Becaplermin; D000068877:Imatinib Mesylate; D014453:Glucuronosyltransferase; C101754:HAS2 protein, human; D000076002:Hyaluronan Synthases; D011505:Protein-Tyrosine Kinases; D000069439:Dasatinib