RESUMO
A study on substitutions at the four open positions on the phenyl ring of the 1,4-dihydroindeno[1,2-c]pyrazoles as potent CHK-1 inhibitors is described. Bis-substitution at both the 6- and 7-positions led to inhibitors with IC(50) values below 0.3nM. The compound with the best overall activities (36) was able to potentiate the anti-proliferative effect of doxorubicin in HeLa cells by at least 47-fold. Physicochemical, metabolic, and pharmacokinetic properties of selected inhibitors are also disclosed.
Assuntos
Antineoplásicos/farmacocinética , Química Farmacêutica/métodos , Ensaios de Seleção de Medicamentos Antitumorais , Inibidores de Proteínas Quinases/farmacocinética , Proteínas Quinases/química , Animais , Antineoplásicos/química , Células CACO-2 , Quinase 1 do Ponto de Checagem , Dano ao DNA , Desenho de Fármacos , Citometria de Fluxo , Humanos , Concentração Inibidora 50 , Camundongos , Microssomos Hepáticos/metabolismo , Inibidores de Proteínas Quinases/química , Proteínas Quinases/metabolismo , RatosRESUMO
A new class of checkpoint kinase 1 (CHK-1) inhibitors bearing a 1,4-dihydroindeno[1,2-c]pyrazole core was developed after initial hits from high throughput screening. The efficient hit-to-lead process was facilitated by X-ray crystallography and led to potent inhibitors (<10nM) against CHK-1. X-ray co-crystal structures of bound inhibitors demonstrated that two sub-series of this class of compounds, exemplified by 21 and 41, exhibit distinctive hydrogen bonding patterns in the specificity pocket of the active site. Two compounds, 41 and 43, were capable of potentiating doxorubicin and camptothecin, both DNA-damaging agents, in cell proliferation assays (MTS and soft agar assays) and abrogating G2/M checkpoint in a mechanism-based FACS assay.
Assuntos
Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/farmacologia , Proteínas Quinases/metabolismo , Pirazóis/síntese química , Pirazóis/farmacologia , Antineoplásicos Fitogênicos/farmacologia , Camptotecina/farmacologia , Ciclo Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Quinase 1 do Ponto de Checagem , Cristalografia por Raios X , Avaliação Pré-Clínica de Medicamentos , Sinergismo Farmacológico , Células HeLa , Humanos , Ligação de Hidrogênio , Indicadores e Reagentes , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Especificidade por SubstratoRESUMO
Based on the X-ray crystallography of our lead compound 1-(5-chloro-2,4-dimethoxyphenyl)-3-(5-cyanopyrazin-2-yl)urea in the checkpoint kinase 1 (Chk1) enzyme, we modified R4, and to a lesser extent, R2, and R5 of the phenyl ring, and made a variety of N-aryl-N'-pyrazinylurea Chk1 inhibitors. Enzymatic activity less than 20 nM was observed in 15 of 41 compounds. Compound 8i provided the best overall results in the cellular assays as it abrogated doxorubicin-induced cell cycle arrest (IC50=1.7 microM) and enhanced doxorubicin cytotoxicity (IC50=0.44 microM) while displaying no single agent activity.
