RESUMEN
The sulfated polysaccharide, p-KG03, purified from the marine microalga, Gyrodinium impudium, is a unique compound comprising homogenous galactose units conjugated to uronic acid and sulfated groups. Although previous studies showed that p-KG03 suppresses tumor cell growth and infection by encephalomyocarditis virus, its effect against enveloped virus infection and the biological mechanism of action have not been elucidated. In this report, the inhibitory activity of p-KG03 against influenza virus was examined and compared with that of other sulfated polysaccharides (fucoidan and pentosan polysulfate) and antiviral agents (oseltamivir phosphate, oseltamivir carboxylate, amantadine, and ribavirin). The results of a cytopathic effect reduction assay using MDCK cells demonstrated that p-KG03 exhibited the 50% effective concentration (EC(50)) values of 0.19-0.48 µg/ml against influenza type A virus infection (selectivity index >200) but not all influenza type B viruses. Mechanism studies showed that inhibition of influenza virus replication was maximized when p-KG03 was added during or within 6 h after viral infection, suggesting that mainly the viral adsorption and internalization steps are targeted by this compound. The results of influenza virus binding assay to p-KG03 and fluorescence microscopy indicate that the antiviral activity of p-KG03 is directly associated with its interaction with viral particles. The sulfated polysaccharide p-KG03 is a potent and specific influenza A viral entry inhibitor and may be a candidate for antiviral drug development.
Asunto(s)
Antivirales/farmacología , Virus de la Influenza A/efectos de los fármacos , Gripe Humana/virología , Microalgas/química , Rhodophyta/química , Animales , Antivirales/química , Línea Celular , Humanos , Virus de la Influenza A/fisiología , Virus de la Influenza B/efectos de los fármacos , Virus de la Influenza B/fisiología , Gripe Humana/tratamiento farmacológico , Polisacáridos/química , Polisacáridos/farmacología , Internalización del Virus/efectos de los fármacos , Replicación Viral/efectos de los fármacosRESUMEN
Using high-throughput screening with small-molecule libraries, we identified a compound, KCG165 [(2-(3-(2-(pyrrolidin-1-yl)ethoxy)-1,10b-dihydro-[1,2,4]triazolo[1,5-c]quinazolin-5(6H)-one)], which strongly activated p53-mediated transcriptional activity. KCG165-induced phosphorylations of p53 at Ser(6), Ser(15), and Ser(20)(,) which are all key residues involved in the activation and stabilization of p53. Consistent with these findings, KCG165 increased level of p53 protein and led to the accumulation of transcriptionally active p53 in the nucleus with the increased occupancy of p53 in the endogenous promoter region of its downstream target gene, p21(WAF1/CIP). Notably, KCG165-induced p53-dependent apoptosis in cancer cells. Furthermore, we suggested topoisomerase II as the molecular target of KCG165. Together, these results indicate that KCG165 may have potential applications as an antitumor agent.
Asunto(s)
Apoptosis , Neoplasias del Colon/genética , Neoplasias del Colon/patología , Quinazolinonas/farmacología , Triazoles/farmacología , Proteína p53 Supresora de Tumor/metabolismo , Antineoplásicos/farmacología , Línea Celular Transformada , Línea Celular Tumoral , Núcleo Celular/metabolismo , Inhibidor p21 de las Quinasas Dependientes de la Ciclina/metabolismo , ADN-Topoisomerasas de Tipo II/química , Relación Dosis-Respuesta a Droga , Fibroblastos/metabolismo , Humanos , Fosforilación , Activación TranscripcionalRESUMEN
A novel biotin-tagged photoaffinity probe was synthesized and evaluated as a vascular endothelial growth factor receptor-2 (VEGFR-2) tyrosine kinase inhibitor. The probe (2) is a potent VEGFR-2 inhibitor with an IC(50) value of 7.1 microM, and inhibits VEGF-induced proliferation in human umbilical vein endothelial cells (HUVEC), with an IC(50) value of 40.3 microM. This probe will be a useful reagent for investigating ligand-protein interactions.