RESUMEN
Duchenne muscular dystrophy (DMD) is a fatal muscle-wasting disease arising from mutations in the dystrophin gene. Upregulation of utrophin to compensate for the missing dystrophin offers a potential therapy independent of patient genotype. The first-in-class utrophin modulator ezutromid/SMT C1100 was developed from a phenotypic screen through to a Phase 2 clinical trial. Promising efficacy and evidence of target engagement was observed in DMD patients after 24â weeks of treatment, however trial endpoints were not met after 48â weeks. The objective of this study was to understand the mechanism of action of ezutromid which could explain the lack of sustained efficacy and help development of new generations of utrophin modulators. Using chemical proteomics and phenotypic profiling we show that the aryl hydrocarbon receptor (AhR) is a target of ezutromid. Several lines of evidence demonstrate that ezutromid binds AhR with an apparent KD of 50â nm and behaves as an AhR antagonist. Furthermore, other reported AhR antagonists also upregulate utrophin, showing that this pathway, which is currently being explored in other clinical applications including oncology and rheumatoid arthritis, could also be exploited in future DMD therapies.
Asunto(s)
Benzoxazoles/química , Naftalenos/química , Proteómica/métodos , Receptores de Hidrocarburo de Aril/metabolismo , Utrofina/metabolismo , Animales , Benzoxazoles/metabolismo , Benzoxazoles/farmacología , Benzoxazoles/uso terapéutico , Reacción de Cicloadición , Diseño de Fármacos , Humanos , Cinética , Ratones , Sondas Moleculares/química , Distrofia Muscular de Duchenne/tratamiento farmacológico , Mioblastos/citología , Mioblastos/metabolismo , Naftalenos/metabolismo , Naftalenos/farmacología , Naftalenos/uso terapéutico , Unión Proteica , Receptores de Hidrocarburo de Aril/antagonistas & inhibidores , Receptores de Hidrocarburo de Aril/genética , Regulación hacia Arriba/efectos de los fármacos , Utrofina/agonistas , Utrofina/genéticaRESUMEN
Recently, the serine/threonine kinase glycogen synthase kinase-3 (GSK-3) emerged as a regulator of pancreatic beta cell growth and survival. On the basis of the previous observation that GSK-3 inhibitors like 1-azakenpaullone promote beta cell protection and replication, paullone derivatives were synthesized including 1-aza-, 2-aza-, and 12-oxapaullone scaffolds. In enzymatic assays distinct 1-azapaullones were found to exhibit selective GSK-3 inhibitory activity. Within the series of 1-azapaullones, three derivatives stimulated INS-1E beta cell replication and protected INS-1E cells against glucolipotoxicity induced cell death. Cazpaullone (9-cyano-1-azapaullone), the most active compound in the protection assays, also stimulated the replication of primary beta cells in isolated rat islets. Furthermore, cazpaullone showed a pronounced transient stimulation of the mRNA expression of the beta cell transcription factor Pax4, an important regulator of beta cell development and growth. These features distinguish cazpaullone as a unique starting point for the development of beta cell regenerative agents which might be useful in the treatment of diabetes.
Asunto(s)
Azepinas/farmacología , Inhibidores Enzimáticos/farmacología , Glucógeno Sintasa Quinasa 3/antagonistas & inhibidores , Indoles/farmacología , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/fisiología , Animales , Azepinas/síntesis química , Azepinas/química , Sitios de Unión , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/química , Humanos , Indoles/síntesis química , Indoles/química , Células Secretoras de Insulina/citología , Modelos Moleculares , Estructura Molecular , Ratas , Estereoisomerismo , Relación Estructura-ActividadRESUMEN
Recent developments indicate that the regeneration of beta cell function and mass in patients with diabetes is possible. A regenerative approach may represent an alternative treatment option relative to current diabetes therapies that fail to provide optimal glycemic control. Here we report that the inactivation of GSK3 by small molecule inhibitors or RNA interference stimulates replication of INS-1E rat insulinoma cells. Specific and potent GSK3 inhibitors also alleviate the toxic effects of high concentrations of glucose and the saturated fatty acid palmitate on INS-1E cells. Furthermore, treatment of isolated rat islets with structurally diverse small molecule GSK3 inhibitors increases the rate beta cell replication by 2-3-fold relative to controls. We propose that GSK3 is a regulator of beta cell replication and survival. Moreover, our results suggest that specific inhibitors of GSK3 may have practical applications in beta cell regenerative therapies.