RESUMEN
Spider venom toxins, such as Protoxin-II (ProTx-II), have recently received much attention as selective Nav1.7 channel blockers, with potential to be developed as leads for the treatment of chronic nocioceptive pain. ProTx-II is a 30-amino acid peptide with three disulfide bonds that has been reported to adopt a well-defined inhibitory cystine knot (ICK) scaffold structure. Potential drawbacks with such peptides include poor pharmacodynamics and potential scrambling of the disulfide bonds in vivo. In order to address these issues, in the present study we report the solid-phase synthesis of lanthionine-bridged analogues of ProTx-II, in which one of the three disulfide bridges is replaced with a thioether linkage, and evaluate the biological properties of these analogues. We have also investigated the folding and disulfide bridging patterns arising from different methods of oxidation of the linear peptide precursor. Finally, we report the X-ray crystal structure of ProTx-II to atomic resolution; to our knowledge this is the first crystal structure of an ICK spider venom peptide not bound to a substrate.
Asunto(s)
Disulfuros/farmacología , Canal de Sodio Activado por Voltaje NAV1.7/metabolismo , Péptidos/farmacología , Venenos de Araña/farmacología , Arañas/química , Bloqueadores del Canal de Sodio Activado por Voltaje/farmacología , Animales , Cristalografía por Rayos X , Disulfuros/química , Modelos Moleculares , Conformación Molecular/efectos de los fármacos , Péptidos/química , Venenos de Araña/química , Bloqueadores del Canal de Sodio Activado por Voltaje/químicaRESUMEN
The pharmaceutical industry is under huge pressure to overhaul what is currently viewed as a highly inefficient operating model. Unacceptable levels of late-stage failure in clinical development remain a fundamental problem for the sector. Lack of efficacy is a major reason for candidate failure and a lack of understanding of disease biology is considered to be a key issue underpinning this problem. There has been a recent upsurge in interest from pharmaceutical and biotechnology companies to collaborate with academic institutions, with the latter viewed as being home to research teams with in-depth biological knowledge and translational research expertise. This article outlines models for collaboration in drug discovery and development being pursued by the research-based charity Cancer Research UK (CR-UK).
Asunto(s)
Antineoplásicos , Descubrimiento de Drogas/métodos , Neoplasias/tratamiento farmacológico , Conducta Cooperativa , Descubrimiento de Drogas/economía , Industria Farmacéutica , Humanos , Neoplasias/economía , Investigación , Reino UnidoRESUMEN
V-RAF murine sarcoma viral oncogene homolog B1 (BRAF) is a serine/threonine-specific protein kinase that is mutated with high frequency in cutaneous melanoma, and many other cancers. Inhibition of mutant BRAF is an attractive therapeutic approach for the treatment of melanoma. A triarylimidazole BRAF inhibitor bearing a phenylpyrazole group (dimethyl-[2-(4-{5-[4-(1H-pyrazol-3-yl)-phenyl]-4-pyridin-4-yl-1H-imidazol-2-yl}-phenoxy)-ethyl]-amine, 1a) was identified as an active BRAF inhibitor. Based on this starting point, we synthesized a series of analogues leading to the discovery of 6-{2-[4-(4-methyl-piperazin-1-yl)-phenyl]-5-pyridin-4-yl-3H-imidazol-4-yl}-2,4-dihydro-indeno[1,2-c]pyrazole (1j), with nanomolar activity in three assays: inhibition of purified mutant BRAF activity in vitro; inhibition of oncogenic BRAF-driven extracellular regulated kinase (ERK) activation in BRAF mutant melanoma cell lines; and inhibition of proliferation in these cells.
Asunto(s)
Furanos/química , Imidazoles/química , Inhibidores de Proteínas Quinasas/química , Proteínas Proto-Oncogénicas B-raf/antagonistas & inhibidores , Pirazoles/química , Animales , Sitios de Unión , Simulación por Computador , Femenino , Humanos , Ratones , Mutación , Inhibidores de Proteínas Quinasas/síntesis química , Inhibidores de Proteínas Quinasas/farmacología , Estructura Terciaria de Proteína , Proteínas Proto-Oncogénicas B-raf/genética , Proteínas Proto-Oncogénicas B-raf/metabolismo , Pirazoles/síntesis química , Pirazoles/farmacocinética , Relación Estructura-ActividadRESUMEN
Acid pump antagonists (APAs) such as the imidazo[1,2-a]pyridine AZD-0865 2 have proven efficacious at low oral doses in acid related gastric disorders. Herein we describe some of the broader SAR in this class of molecule and detail the discovery of an imidazo[1,2-a]pyridine 15 which has excellent efficacy in animal models of gastric acid secretion following oral administration, as well as a good overall developability profile. The discovery strategy focuses on use of heteroaryl and heterocyclic substituents at the C-6 position and optimization of developability characteristics through modulation of global physico-chemical properties.
Asunto(s)
Inhibidores de la Bomba de Protones , Inhibidores de la Bomba de Protones/química , Piridinas/química , Administración Oral , Animales , Perros , ATPasa Intercambiadora de Hidrógeno-Potásio/metabolismo , Humanos , Concentración de Iones de Hidrógeno , Inhibidores de la Bomba de Protones/síntesis química , Inhibidores de la Bomba de Protones/farmacología , Piridinas/síntesis química , Piridinas/farmacología , Ratas , Relación Estructura-ActividadRESUMEN
Modification of the potent imidazole-based B-Raf inhibitor SB-590885 resulted in the identification of a series of furan-based derivatives with enhanced CNS penetration. One such compound, SB-699393 (17), was examined in vivo to challenge the hypothesis that selective B-Raf inhibitors may be of value in the treatment of stroke.
Asunto(s)
Sistema Nervioso Central/efectos de los fármacos , Furanos/síntesis química , Furanos/farmacología , Indanos/síntesis química , Indanos/farmacología , Proteínas Proto-Oncogénicas B-raf/antagonistas & inhibidores , Animales , Furanos/química , Imidazoles/química , Imidazoles/farmacología , Indanos/química , Estructura Molecular , Piridinas/química , Piridinas/farmacología , Ratas , Accidente Cerebrovascular/tratamiento farmacológico , Relación Estructura-ActividadRESUMEN
Oncogenic BRAF alleles are both necessary and sufficient for cellular transformation, suggesting that chemical inhibition of the activated mutant protein kinase may reverse the tumor phenotype. Here, we report the characterization of SB-590885, a novel triarylimidazole that selectively inhibits Raf kinases with more potency towards B-Raf than c-Raf. Crystallographic analysis revealed that SB-590885 stabilizes the oncogenic B-Raf kinase domain in an active configuration, which is distinct from the previously reported mechanism of action of the multi-kinase inhibitor, BAY43-9006. Malignant cells expressing oncogenic B-Raf show selective inhibition of mitogen-activated protein kinase activation, proliferation, transformation, and tumorigenicity when exposed to SB-590885, whereas other cancer cell lines and normal cells display variable sensitivities or resistance to similar treatment. These studies support the validation of oncogenic B-Raf as a target for cancer therapy and provide the first evidence of a correlation between the expression of oncogenic BRAF alleles and a positive response to a selective B-Raf inhibitor.
Asunto(s)
Imidazoles/uso terapéutico , Neoplasias/tratamiento farmacológico , Proteínas Proto-Oncogénicas B-raf/antagonistas & inhibidores , Alelos , Animales , Western Blotting , Línea Celular Tumoral , Movimiento Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Cristalización , Cristalografía por Rayos X , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Femenino , Células HT29 , Humanos , Imidazoles/química , Ratones , Ratones Desnudos , Modelos Moleculares , Estructura Molecular , Mutación/genética , Neoplasias/enzimología , Neoplasias/patología , Fosforilación/efectos de los fármacos , Conformación Proteica/efectos de los fármacos , Inhibidores de Proteínas Quinasas/química , Inhibidores de Proteínas Quinasas/uso terapéutico , Proteínas Proto-Oncogénicas B-raf/química , Proteínas Proto-Oncogénicas B-raf/genética , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
A novel triarylimidazole derivative, SB-590885 (33), bearing a 2,3-dihydro-1H-inden-1-one oxime substituent has been identified as a potent and extremely selective inhibitor of B-Raf kinase.