title: In vitro biological characterization and antiangiogenic effects of PD 166866, a selective inhibitor of the FGF-1 receptor tyrosine kinase.
abstract: Through direct synthetic efforts, we discovered a small molecule that is a nanomolar inhibitor of the human fibroblast growth factor-1 receptor (FGFR) tyrosine kinase. PD 166866, a member of a new structural class of tyrosine kinase inhibitors, the 6-aryl-pyrido[2,3-d]pyrimidines, was identified by screening a compound library with assays that measure protein tyrosine kinase activity. PD 166866 inhibited human full-length FGFR-1 tyrosine kinase with an IC50 value of 52.4 +/- 0.1 nM and was further characterized as an ATP competitive inhibitor of the FGFR-1. In contrast, PD 166866 had no effect on c-Src, platelet-derived growth factor receptor-beta, epidermal growth factor receptor or insulin receptor tyrosine kinases or on mitogen-activated protein kinase, protein kinase C and CDK4 at concentrations as high as 50 microM. PD 166866 was a potent inhibitor of basic fibroblast growth factor (bFGF)-mediated receptor autophosphorylation in NIH 3T3 cells expressing endogenous FGFR-1 and in L6 cells overexpressing the human FGFR-1 tyrosine kinase, confirming a tyrosine kinase-mediated mechanism. PD 166866 also inhibited bFGF-induced tyrosine phosphorylation of the 44- and 42-kDa (ERK 1/2) mitogen-activated protein kinase isoforms in L6 cells, presumably via inhibition of bFGF-stimulated FGFR-1 tyrosine kinase activation. PD 166866 did not inhibit platelet-derived growth factor, epidermal growth factor or insulin-stimulated receptor autophosphorylation in vascular smooth muscle, A431 or NIHIR cells, respectively, further supporting its specificity for the FGFR-1. In addition, daily exposure of PD 166866 to L6 cells at concentrations from 1 to 100 nM resulted in a concentration-related inhibition of bFGF-stimulated cell growth for 8 consecutive days with an IC50 value of 24 nM. In contrast, PD 166866 had little effect on platelet-derived growth factor-BB-stimulated growth of L6 cells or serum-stimulated vascular smooth muscle cell proliferation. Finally, PD 166866 was found to be a potent inhibitor of microvessel outgrowth (angiogenesis) from cultured artery fragments of human placenta. These results highlight the discovery of PD 166866, a new nanomolar potent and selective small molecule inhibitor of the FGFR-1 tyrosine kinase with potential use as antiproliferative/antiangiogenic agent for such therapeutic targets as tumor growth and neovascularization of atherosclerotic plaques.
authors.affiliation: Department of Vascular and Cardiac Diseases, Parke-Davis Pharmaceutical Research, Division of Warner-Lambert Company, Ann Arbor, Michigan, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Panek
authors.forename: G H
authors.initials: GH
authors.lastname: Lu
authors.forename: T K
authors.initials: TK
authors.lastname: Dahring
authors.forename: B L
authors.initials: BL
authors.lastname: Batley
authors.forename: C
authors.initials: C
authors.lastname: Connolly
authors.forename: J M
authors.initials: JM
authors.lastname: Hamby
authors.forename: K J
authors.initials: KJ
authors.lastname: Brown
mesh_terms: D016475:3T3 Cells; D000818:Animals; D005346:Fibroblast Growth Factors / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology*; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D051496:Receptor, Fibroblast Growth Factor, Type 1; D017468:Receptors, Fibroblast Growth Factor / Q000037:antagonists & inhibitors*; D014508:Urea / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D011743:Pyrimidines; D017468:Receptors, Fibroblast Growth Factor; D005346:Fibroblast Growth Factors; D014508:Urea; C496348:FGFR1 protein, human; C496349:Fgfr1 protein, mouse; C496350:Fgfr1 protein, rat; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases; D051496:Receptor, Fibroblast Growth Factor, Type 1; C113399:PD 166866