4-Arylazo-3,5-diamino-1<i>H</i>-pyrazole CDK Inhibitors: SAR Study, Crystal Structure in Complex with CDK2, Selectivity, and Cellular Effects
作者:Vladimír Kryštof、Petr Cankař、Iveta Fryšová、Jan Slouka、George Kontopidis、Petr Džubák、Marián Hajdúch、Josef Srovnal、Walter F. de Azevedo、Martin Orság、Martina Paprskářová、Jakub Rolčík、Aleš Látr、Peter M. Fischer、Miroslav Strnad
DOI:10.1021/jm0605740
日期:2006.11.1
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 CDK9cyclin 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.