title: Fragment based lead discovery of small molecule inhibitors for the EPHA4 receptor tyrosine kinase.
abstract: The in silico identification, optimization and crystallographic characterization of a 6,7,8,9-tetrahydro-3H-pyrazolo[3,4-c]isoquinolin-1-amine scaffold as an inhibitor for the EPHA4 receptor tyrosine kinase is described. A database containing commercially available compounds was subjected to an in silico screening procedure which was focused on finding novel, EPHA4 hinge binding fragments. This resulted in the identification of 6,7,8,9-tetrahydro-3H-pyrazolo[3,4-c]isoquinolin-1-amine derivatives as EPHA4 inhibitors. Hit exploration yielded a compound with 2 μM (IC(50)) affinity for the EPHA4 receptor tyrosine kinase domain. Soaking experiments into a crystal of the EPHA4 kinase domain gave a 2.11Å X-ray structure of the EPHA4 - inhibitor complex, which confirmed the binding mode of the scaffold as proposed by the initial in silico work. The results underscore the strength of fragment based in silico screening as a tool for the discovery of novel lead compounds as small molecule kinase inhibitors.
authors.affiliation: Leiden/Amsterdam Center for Drug Research (LACDR), Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
authors.forename: Oscar P J
authors.initials: OP
authors.lastname: van Linden
authors.forename: Carine
authors.initials: C
authors.lastname: Farenc
authors.forename: Willem H
authors.initials: WH
authors.lastname: Zoutman
authors.forename: Liesbeth
authors.initials: L
authors.lastname: Hameetman
authors.forename: Maikel
authors.initials: M
authors.lastname: Wijtmans
authors.forename: Rob
authors.initials: R
authors.lastname: Leurs
authors.forename: Cornelis P
authors.initials: CP
authors.lastname: Tensen
authors.forename: Gregg
authors.initials: G
authors.lastname: Siegal
authors.forename: Iwan J P
authors.initials: IJ
authors.lastname: de Esch
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001665:Binding Sites; D019295:Computational Biology; D055808:Drug Discovery / Q000379:methods*; D008958:Models, Molecular; D011487:Protein Conformation; D047428:Protein Kinase Inhibitors / Q000737:chemistry* / Q000494:pharmacology*; D036122:Receptor, EphA4 / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D054852:Small Molecule Libraries / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D047428:Protein Kinase Inhibitors; D054852:Small Molecule Libraries; D000255:Adenosine Triphosphate; D036122:Receptor, EphA4