RESUMEN
Porcupine is an O-acyltransferase that regulates Wnt secretion. Inhibiting porcupine may block the Wnt pathway which is often dysregulated in various cancers. Consequently porcupine inhibitors are thought to be promising oncology therapeutics. A high throughput screen against porcupine revealed several potent hits that were confirmed to be Wnt pathway inhibitors in secondary assays. We developed a pharmacophore model and used the putative bioactive conformation of a xanthine inhibitor for scaffold hopping. The resulting maleimide scaffold was optimized to subnanomolar potency while retaining good physical druglike properties. A preclinical development candidate was selected for which extensive in vitro and in vivo profiling is reported.
Asunto(s)
Aciltransferasas/antagonistas & inhibidores , Antineoplásicos/farmacología , Maleimidas/farmacología , Proteínas de la Membrana/antagonistas & inhibidores , Piridazinas/farmacología , Animales , Antineoplásicos/administración & dosificación , Antineoplásicos/síntesis química , Antineoplásicos/farmacocinética , Línea Celular Tumoral , Inhibidores del Citocromo P-450 CYP1A2/administración & dosificación , Inhibidores del Citocromo P-450 CYP1A2/síntesis química , Inhibidores del Citocromo P-450 CYP1A2/farmacocinética , Inhibidores del Citocromo P-450 CYP1A2/farmacología , Inhibidores del Citocromo P-450 CYP2D6/administración & dosificación , Inhibidores del Citocromo P-450 CYP2D6/síntesis química , Inhibidores del Citocromo P-450 CYP2D6/farmacocinética , Inhibidores del Citocromo P-450 CYP2D6/farmacología , Inhibidores del Citocromo P-450 CYP3A/administración & dosificación , Inhibidores del Citocromo P-450 CYP3A/síntesis química , Inhibidores del Citocromo P-450 CYP3A/farmacocinética , Inhibidores del Citocromo P-450 CYP3A/farmacología , Femenino , Células HEK293 , Ensayos Analíticos de Alto Rendimiento , Humanos , Maleimidas/administración & dosificación , Maleimidas/síntesis química , Maleimidas/farmacocinética , Ratones Endogámicos BALB C , Ratones Desnudos , Microsomas Hepáticos/metabolismo , Piridazinas/administración & dosificación , Piridazinas/síntesis química , Piridazinas/farmacocinética , Ratas , Relación Estructura-Actividad , Vía de Señalización Wnt , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Porcupine is a component of the Wnt pathway which regulates cell proliferation, migration, stem cell self-renewal, and differentiation. The Wnt pathway has been shown to be dysregulated in a variety of cancers. Porcupine is a membrane bound O-acyltransferase that palmitoylates Wnt. Inhibiting porcupine blocks the secretion of Wnt and effectively inhibits the Wnt pathway. Using high throughput screening, we have identified a number of novel porcupine inhibitors with diverse scaffolds. The pharmacophore requirements for our porcupine inhibitors were elucidated, and a pharmacophore model is proposed. Our compounds as well as all currently published porcupine inhibitors may be fitted to this model in low energy conformations with good superimposition of the pharmacophore elements. The model also explains the stereochemical requirements of our chiral porcupine inhibitors. The pharmacophore model was successfully used for designing 3 new series of porcupine inhibitors having a tricyclic xantine, a phtalimide, or a piperidine-maleimide scaffold.
Asunto(s)
Diseño de Fármacos , Proteínas de la Membrana/antagonistas & inhibidores , Modelos Moleculares , Proteínas Wnt/antagonistas & inhibidores , Aciltransferasas , Células HEK293 , Humanos , Conformación Molecular , Estereoisomerismo , Especificidad por SustratoRESUMEN
Tankyrases constitute potential drug targets for cancer and myelin-degrading diseases. We have applied a structure- and biophysics-driven fragment-based ligand design strategy to discover a novel family of potent inhibitors for human tankyrases. Biophysical screening based on a thermal shift assay identified highly efficient fragments binding in the nicotinamide-binding site, a local hot spot for fragment binding. Evolution of the fragment hit 4-methyl-1,2-dihydroquinolin-2-one (2) along its 7-vector yields dramatic affinity improvements in the first cycle of expansion. A crystal structure of 7-(2-fluorophenyl)-4-methylquinolin-2(1H)-one (11) reveals that the nonplanar compound extends with its fluorine atom into a pocket, which coincides with a region of the active site where structural differences are seen between tankyrases and other poly(ADP-ribose) polymerase (PARP) family members. A further cycle of optimization yielded compounds with affinities and IC50 values in the low nanomolar range and with good solubility, PARP selectivity, and ligand efficiency.