RESUMEN
A small molecule compound, JTP-74057/GSK1120212/trametinib, had been discovered as a very potent antiproliferative agent able to induce the accumulation of CDK inhibitor p15INK4b. To conduct its drug development rationally as an anticancer agent, molecular targets of this compound were identified as MEK1/2 using compound-affinity chromatography. It was shown that JTP-74057 directly bound to MEK1 and MEK2 and allosterically inhibited their kinase activities, and that its inhibitory characteristics were similar to those of the known and different chemotype of MEK inhibitors PD0325901 and U0126. It was further shown that JTP-74057 induced rapid and sustained dephosphorylation of phosphorylated MEK in HT-29 colon and other cancer cell lines, while this decrease in phosphorylated MEK was not observed in PD0325901-treated cancer cells. Physicochemical analyses revealed that JTP-74057 preferentially binds to unphosphorylated MEK (u-MEK) in unique characteristics of both high affinity based on extremely low dissociation rates and ability stabilizing u-MEK with high thermal shift, which were markedly different from PD0325901. These findings indicate that JTP-74057 is a novel MEK inhibitor able to sustain MEK to be an unphosphorylated form resulting in pronounced suppression of the downstream signaling pathways involved in cellular proliferation.
Asunto(s)
Antineoplásicos/farmacología , MAP Quinasa Quinasa 1/antagonistas & inhibidores , MAP Quinasa Quinasa 2/antagonistas & inhibidores , Terapia Molecular Dirigida , Neoplasias/enzimología , Inhibidores de Proteínas Quinasas/farmacología , Piridonas/farmacología , Pirimidinonas/farmacología , Regulación Alostérica , Antineoplásicos/química , Benzamidas/farmacología , Butadienos/farmacología , Cromatografía de Afinidad , Difenilamina/análogos & derivados , Difenilamina/farmacología , Relación Dosis-Respuesta a Droga , Células HEK293 , Células HT29 , Humanos , Cinética , MAP Quinasa Quinasa 1/metabolismo , MAP Quinasa Quinasa 2/metabolismo , Estructura Molecular , Neoplasias/patología , Nitrilos/farmacología , Fosforilación , Unión Proteica , Inhibidores de Proteínas Quinasas/química , Piridonas/química , Pirimidinonas/química , Transducción de Señal/efectos de los fármacosRESUMEN
The discovery of small and potent peptide antagonists of the corticotropin-releasing factor (CRF) receptor is described. Through the structure-activity relationship studies of 12-amino acid peptide corresponding to the C-terminal residues of astressin, we assumed that a particular surface of the alpha-helix was important for binding to the receptor. The small peptide containing d-Ala31 and cyclohexylalanine38 on that surface was as potent as astressin in binding to the CRF receptor and showed significant ACTH suppression when administered to rats.