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1.
Artigo em Inglês | MEDLINE | ID: mdl-30373799

RESUMO

NVR 3-778 is the first capsid assembly modulator (CAM) that has demonstrated antiviral activity in hepatitis B virus (HBV)-infected patients. NVR 3-778 inhibited the generation of infectious HBV DNA-containing virus particles with a mean antiviral 50% effective concentration (EC50) of 0.40 µM in HepG2.2.15 cells. The antiviral profile of NVR 3-778 indicates pan-genotypic antiviral activity and a lack of cross-resistance with nucleos(t)ide inhibitors of HBV replication. The combination of NVR 3-778 with nucleos(t)ide analogs in vitro resulted in additive or synergistic antiviral activity. Mutations within the hydrophobic pocket at the dimer-dimer interface of the core protein could confer resistance to NVR 3-778, which is consistent with the ability of the compound to bind to core and to induce capsid assembly. By targeting core, NVR 3-778 inhibits pregenomic RNA encapsidation, viral replication, and the production of HBV DNA- and HBV RNA-containing particles. NVR 3-778 also inhibited de novo infection and viral replication in primary human hepatocytes with EC50 values of 0.81 µM against HBV DNA and between 3.7 and 4.8 µM against the production of HBV antigens and intracellular HBV RNA. NVR 3-778 showed favorable pharmacokinetics and safety in animal species, allowing serum levels in excess of 100 µM to be achieved in mice and, thus, enabling efficacy studies in vivo The overall preclinical profile of NVR 3-778 predicts antiviral activity in vivo and supports its further evaluation for safety, pharmacokinetics, and antiviral activity in HBV-infected patients.


Assuntos
Antivirais/farmacologia , Benzamidas/farmacologia , Capsídeo/efeitos dos fármacos , DNA Viral/antagonistas & inibidores , Vírus da Hepatite B/efeitos dos fármacos , Hepatite B/tratamento farmacológico , Piperidinas/farmacologia , RNA Viral/antagonistas & inibidores , Animais , Antígenos Virais/genética , Antígenos Virais/metabolismo , Antivirais/sangue , Antivirais/química , Antivirais/farmacocinética , Benzamidas/sangue , Benzamidas/química , Benzamidas/farmacocinética , Capsídeo/química , Capsídeo/metabolismo , DNA Viral/genética , DNA Viral/metabolismo , Avaliação Pré-Clínica de Medicamentos , Feminino , Células Hep G2 , Hepatite B/virologia , Vírus da Hepatite B/genética , Vírus da Hepatite B/metabolismo , Hepatócitos/efeitos dos fármacos , Hepatócitos/patologia , Hepatócitos/virologia , Humanos , Masculino , Camundongos , Testes de Sensibilidade Microbiana , Piperidinas/sangue , Piperidinas/química , Piperidinas/farmacocinética , Cultura Primária de Células , RNA Viral/genética , RNA Viral/metabolismo , Proteínas do Core Viral/antagonistas & inibidores , Proteínas do Core Viral/genética , Proteínas do Core Viral/metabolismo , Replicação Viral/efeitos dos fármacos
2.
Cell Stress Chaperones ; 15(6): 913-27, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20717760

RESUMO

Cancer cells are exposed to external and internal stresses by virtue of their unrestrained growth, hostile microenvironment, and increased mutation rate. These stresses impose a burden on protein folding and degradation pathways and suggest a route for therapeutic intervention in cancer. Proteasome and Hsp90 inhibitors are in clinical trials and a 20S proteasome inhibitor, Velcade, is an approved drug. Other points of intervention in the folding and degradation pathway may therefore be of interest. We describe a simple screen for inhibitors of protein synthesis, folding, and proteasomal degradation pathways in this paper. The molecular chaperone-dependent client v-Src was fused to firefly luciferase and expressed in HCT-116 colorectal tumor cells. Both luciferase and protein tyrosine kinase activity were preserved in cells expressing this fusion construct. Exposing these cells to the Hsp90 inhibitor geldanamycin caused a rapid reduction of luciferase and kinase activities and depletion of detergent-soluble v-Src::luciferase fusion protein. Hsp70 knockdown reduced v-Src::luciferase activity and, when combined with geldanamycin, caused a buildup of v-Src::luciferase and ubiquitinated proteins in a detergent-insoluble fraction. Proteasome inhibitors also decreased luciferase activity and caused a buildup of phosphotyrosine-containing proteins in a detergent-insoluble fraction. Protein synthesis inhibitors also reduced luciferase activity, but had less of an effect on phosphotyrosine levels. In contrast, certain histone deacetylase inhibitors increased luciferase and phosphotyrosine activity. A mass screen led to the identification of Hsp90 inhibitors, ubiquitin pathway inhibitors, inhibitors of Hsp70/Hsp40-mediated refolding, and protein synthesis inhibitors. The largest group of compounds identified in the screen increased luciferase activity, and some of these increase v-Src levels and activity. When used in conjunction with appropriate secondary assays, this screen is a powerful cell-based tool for studying compounds that affect protein synthesis, folding, and degradation.


Assuntos
Inibidores Enzimáticos/farmacologia , Inibidores de Histona Desacetilases/farmacologia , Chaperonas Moleculares/antagonistas & inibidores , Inibidores de Proteassoma , Dobramento de Proteína/efeitos dos fármacos , Inibidores da Síntese de Proteínas/farmacologia , Benzoquinonas/farmacologia , Linhagem Celular Tumoral , Avaliação Pré-Clínica de Medicamentos , Proteínas de Choque Térmico HSP40/antagonistas & inibidores , Proteínas de Choque Térmico HSP40/metabolismo , Proteínas de Choque Térmico HSP70/antagonistas & inibidores , Proteínas de Choque Térmico HSP70/genética , Proteínas de Choque Térmico HSP70/metabolismo , Proteínas de Choque Térmico HSP90/antagonistas & inibidores , Proteínas de Choque Térmico HSP90/genética , Proteínas de Choque Térmico HSP90/metabolismo , Histona Desacetilases/química , Histona Desacetilases/farmacologia , Humanos , Lactamas Macrocíclicas/farmacologia , Luciferases de Vaga-Lume/genética , Luciferases de Vaga-Lume/metabolismo , Proteína Oncogênica pp60(v-src)/química , Proteína Oncogênica pp60(v-src)/genética , Proteína Oncogênica pp60(v-src)/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Interferência de RNA , RNA Interferente Pequeno , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Ubiquitina/antagonistas & inibidores , Ubiquitina/metabolismo
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