title: 4-arylazo-3,5-diamino-1H-pyrazole CDK inhibitors: SAR study, crystal structure in complex with CDK2, selectivity, and cellular effects.
abstract: In a routine screening of our small-molecule compound collection we recently identified 4-arylazo-3,5-diamino-1H-pyrazoles as a novel group of ATP antagonists with moderate potency against CDK2-cyclin E. A preliminary SAR study based on 35 analogues suggests ways in which the pharmacophore could be further optimized, for example, via substitutions in the 4-aryl ring. Enzyme kinetics studies with the lead compound and X-ray crystallography of an inhibitor-CDK2 complex demonstrated that its mode of inhibition is competitive. Functional kinase assays confirmed the selectivity toward CDKs, with a preference for CDK9-cyclin T1. The most potent inhibitor, 4-[(3,5-diamino-1H-pyrazol-4-yl)diazenyl]phenol 31b (CAN508), reduced the frequency of S-phase cells of the cancer cell line HT-29 in antiproliferation assays. Further observed cellular effects included decreased phosphorylation of the retinoblastoma protein and the C-terminal domain of RNA polymerase II, inhibition of mRNA synthesis, and induction of the tumor suppressor protein p53, all of which are consistent with inhibition of CDK9.
authors.affiliation: Laboratory of Growth Regulators, Faculty of Science, Palacký University and Institute of Experimental Botany, Slechtitelů 11, 783 71 Olomouc, Czech Republic.
authors.forename: Vladimír
authors.initials: V
authors.lastname: Krystof
authors.forename: Petr
authors.initials: P
authors.lastname: Cankar
authors.forename: Iveta
authors.initials: I
authors.lastname: Frysová
authors.forename: Jan
authors.initials: J
authors.lastname: Slouka
authors.forename: George
authors.initials: G
authors.lastname: Kontopidis
authors.forename: Petr
authors.initials: P
authors.lastname: Dzubák
authors.forename: Marián
authors.initials: M
authors.lastname: Hajdúch
authors.forename: Josef
authors.initials: J
authors.lastname: Srovnal
authors.forename: Walter F
authors.initials: WF
authors.lastname: de Azevedo
authors.forename: Martin
authors.initials: M
authors.lastname: Orság
authors.forename: Martina
authors.initials: M
authors.lastname: Paprskárová
authors.forename: Jakub
authors.initials: J
authors.lastname: Rolcík
authors.forename: Ales
authors.initials: A
authors.lastname: Látr
authors.forename: Peter M
authors.initials: PM
authors.lastname: Fischer
authors.forename: Miroslav
authors.initials: M
authors.lastname: Strnad
mesh_terms: D000963:Antimetabolites; D001391:Azo Compounds / Q000138:chemical synthesis* / Q000494:pharmacology*; D001973:Bromodeoxyuridine; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D018360:Crystallography, X-Ray; D051357:Cyclin-Dependent Kinase 2 / Q000037:antagonists & inhibitors; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors*; D004791:Enzyme Inhibitors / Q000138:chemical synthesis* / Q000494:pharmacology*; D006801:Humans; D015151:Immunoblotting; D008958:Models, Molecular; D011720:Pyrazoles / Q000138:chemical synthesis* / Q000494:pharmacology*; D012313:RNA / Q000096:biosynthesis / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D048348:Reverse Transcription / Q000187:drug effects; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D000963:Antimetabolites; D001391:Azo Compounds; D004791:Enzyme Inhibitors; D011720:Pyrazoles; D012313:RNA; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D001973:Bromodeoxyuridine