RESUMO
A high throughput screening campaign was designed to identify allosteric inhibitors of Chk1 kinase by testing compounds at high concentration. Activity was then observed at K(m) for ATP and at near-physiological concentrations of ATP. This strategy led to the discovery of a non-ATP competitive thioquinazolinone series which was optimized for potency and stability. An X-ray crystal structure for the complex of our best inhibitor bound to Chk1 was solved, indicating that it binds to an allosteric site approximately 13A from the ATP binding site. Preliminary data is presented for several of these compounds.
Assuntos
Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/farmacologia , Proteínas Quinases/efeitos dos fármacos , Quinazolinas/síntese química , Quinazolinas/farmacologia , Sítios de Ligação , Quinase 1 do Ponto de Checagem , Técnicas de Química Combinatória , Cristalografia por Raios X , Humanos , Conformação Molecular , Estrutura Molecular , Inibidores de Proteínas Quinases/química , Proteínas Quinases/química , Proteínas Quinases/metabolismo , Quinazolinas/químicaRESUMO
From HTS lead 1, a novel benzoisoquinolinone class of ATP-competitive Chk1 inhibitors was devised and synthesized via a photochemical route. Using X-ray crystallography as a guide, potency was rapidly enhanced through the installation of a tethered basic amine designed to interact with an acidic residue (Glu91) in the enzyme pocket. Further SAR was explored at the solvent front and near to the H1 pocket and resulted in the discovery of low MW, sub-nanomolar inhibitors of Chk1.
Assuntos
Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/farmacologia , Proteínas Quinases/efeitos dos fármacos , Quinolonas/síntese química , Quinolonas/farmacologia , Apoptose/efeitos dos fármacos , Sítios de Ligação , Linhagem Celular Tumoral , Quinase 1 do Ponto de Checagem , Cristalografia por Raios X , Avaliação Pré-Clínica de Medicamentos , Inibidores Enzimáticos/química , Humanos , Concentração Inibidora 50 , Modelos Moleculares , Estrutura Molecular , Fotoquímica , Proteínas Quinases/química , Quinolonas/química , Relação Estrutura-AtividadeRESUMO
Through a comparison of X-ray co-crystallographic data for 1 and 2 in the Chek1 active site, it was hypothesized that the affinity of the indolylquinolinone series (2) for Chek1 kinase would be improved via C6 substitution into the hydrophobic region I (HI) pocket. An efficient route to 6-bromo-3-indolyl-quinolinone (9) was developed, and this series was rapidly optimized for potency by modification at C6. A general trend was observed among these low nanomolar Chek1 inhibitors that compounds with multiple basic amines, or elevated polar surface area (PSA) exhibited poor cell potency. Minimization of these parameters (basic amines, PSA) resulted in Chek1 inhibitors with improved cell potency, and preliminary pharmacokinetic data are presented for several of these compounds.