RESUMEN
Centromere-associated protein-E (CENP-E) is a kinetochore-associated mitotic kinesin that is thought to function as the key receptor responsible for mitotic checkpoint signal transduction after interaction with spindle microtubules. We have identified GSK923295, an allosteric inhibitor of CENP-E kinesin motor ATPase activity, and mapped the inhibitor binding site to a region similar to that bound by loop-5 inhibitors of the kinesin KSP/Eg5. Unlike these KSP inhibitors, which block release of ADP and destabilize motor-microtubule interaction, GSK923295 inhibited release of inorganic phosphate and stabilized CENP-E motor domain interaction with microtubules. Inhibition of CENP-E motor activity in cultured cells and tumor xenografts caused failure of metaphase chromosome alignment and induced mitotic arrest, indicating that tight binding of CENP-E to microtubules is insufficient to satisfy the mitotic checkpoint. Consistent with genetic studies in mice suggesting that decreased CENP-E function can have a tumor-suppressive effect, inhibition of CENP-E induced tumor cell apoptosis and tumor regression.
Asunto(s)
Antineoplásicos/farmacología , Compuestos Bicíclicos Heterocíclicos con Puentes/farmacología , Proteínas Cromosómicas no Histona/antagonistas & inhibidores , Sarcosina/análogos & derivados , Sitio Alostérico , Animales , Antineoplásicos/química , Sitios de Unión , Compuestos Bicíclicos Heterocíclicos con Puentes/química , Línea Celular Tumoral , Proteínas Cromosómicas no Histona/química , Proteínas Cromosómicas no Histona/metabolismo , Perros , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Técnicas In Vitro , Cinesinas/antagonistas & inhibidores , Cinesinas/química , Cinesinas/metabolismo , Ratones , Microtúbulos/metabolismo , Mitosis/efectos de los fármacos , Modelos Moleculares , Estructura Molecular , Sarcosina/química , Sarcosina/farmacología , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Kinesin spindle protein (KSP), an ATPase responsible for spindle pole separation during mitosis that is present only in proliferating cells, has become a novel and attractive anticancer target with potential for reduced side effects compared to currently available therapies. We report herein the discovery of the first known ATP-competitive inhibitors of KSP, which display a unique activity profile as compared to the known loop 5 (L5) allosteric KSP inhibitors that are currently under clinical evaluation. Optimization of this series led to the identification of biphenyl sulfamide 20, a potent KSP inhibitor with in vitro antiproliferative activity against human cells with either wild-type KSP (HCT116) or mutant KSP (HCT116 D130V). In a murine xenograft model with HCT116 D130V tumors, 20 showed significant antitumor activity following intraperitoneal dosing, providing in vivo proof-of-principle of the efficacy of an ATP-competitive KSP inhibitor versus tumors that are resistant to the other known KSP inhibitors.