title: Screening and identification of a novel class of TGF-β type 1 receptor kinase inhibitor.
abstract: Transforming growth factor β (TGF-β) type I receptor (activin receptor-like kinase 5, ALK5) has been identified as a promising target for fibrotic diseases. To find a novel inhibitor of ALK5, the authors performed a high-throughput screen of a library of 420,000 compounds using dephosphorylated ALK5. From primary hits of 1521 compounds, 555 compounds were confirmed. In total, 124 compounds were then selected for follow-up based on their unique structures and other properties. Repeated concentration-response testing and final interference assays of the above compounds resulted in the discovery of a structurally novel ALK5 inhibitor (compound 8) (N-(thiophen 2-ylmethyl)-3-(3,4,5 trimethoxyphenyl)imidazo[1,2β]pyridazin 6-amine) with a low IC(50) value of 0.7 µM. Compound 8 also inhibited the TGF-β-induced nuclear translocation of SMAD with an EC(50) value of 0.8 µM. Kinetic analysis revealed that compound 8 inhibited ALK5 via mixed-type inhibition, suggesting that it may bind to ALK5 differently than other published adenosine triphosphate site inhibitors.
authors.affiliation: Research and Development, Gilead Sciences, Inc., Foster City, CA 94404, USA. khai.huynh@gilead.com
authors.forename: Q Khai
authors.initials: QK
authors.lastname: Huynh
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Wise
authors.forename: Keith A
authors.initials: KA
authors.lastname: Koch
authors.forename: Laurie A
authors.initials: LA
authors.lastname: Castonguay
authors.forename: Brian G
authors.initials: BG
authors.lastname: Reid
authors.forename: Erinn E
authors.initials: EE
authors.lastname: Pagratis
authors.forename: David
authors.initials: D
authors.lastname: Koditek
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Glascock
authors.forename: Kelly R
authors.initials: KR
authors.lastname: Pitts
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Turner
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Liu
authors.forename: Magdeleine
authors.initials: M
authors.lastname: Hung
authors.forename: Bin
authors.initials: B
authors.lastname: Han
authors.forename: Nikos
authors.initials: N
authors.lastname: Pagratis
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D045744:Cell Line, Tumor; D003198:Computer Simulation; D031541:Fluorescence Resonance Energy Transfer; D015200:Fluoroimmunoassay; D057166:High-Throughput Screening Assays; D006801:Humans; D007700:Kinetics; D008968:Molecular Conformation; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051785:Smad Proteins / Q000378:metabolism; D054852:Small Molecule Libraries / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000494:pharmacology
chemical_list: D047428:Protein Kinase Inhibitors; D018125:Receptors, Transforming Growth Factor beta; D051785:Smad Proteins; D054852:Small Molecule Libraries; D016212:Transforming Growth Factor beta; D000244:Adenosine Diphosphate; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; C000625841:TGFBR1 protein, human