RESUMO
Three new modified peptides named grassystatins D-F (1-3) were discovered from a marine cyanobacterium from Guam. Their structures were elucidated using NMR spectroscopy and mass spectrometry. The hallmark structural feature in the peptides is a statine unit, which contributes to their aspartic protease inhibitory activity preferentially targeting cathepsins D and E. Grassystatin F (3) was the most potent analogue, with IC50 values of 50 and 0.5 nM against cathepsins D and E, respectively. The acidic tumor microenvironment is known to increase the activation of some of the lysosomal proteases associated with tumor metastasis such as cathepsins. Because cathepsin D is a biomarker in aggressive forms of breast cancer and linked to poor prognosis, the effects of cathepsin D inhibition by 1 and 3 on the downstream cellular substrates cystatin C and PAI-1 were investigated. Furthermore, the functional relevance of targeting cathepsin D substrates was evaluated by examining the effect of 1 and 3 on the migration of MDA-MD-231 cells. Grassystatin F (3) inhibited the cleavage of cystatin C and PAI-1, the activities of their downstream targets cysteine cathepsins and tPA, and the migration of the highly aggressive triple negative breast cancer cells, phenocopying the effect of siRNA-mediated knockdown of cathepsin D.
Assuntos
Ácido Aspártico Proteases/efeitos dos fármacos , Peptídeos/isolamento & purificação , Aminoácidos , Catepsina D/antagonistas & inibidores , Catepsina E/antagonistas & inibidores , Catepsina L/metabolismo , Cianobactérias/química , Relação Dose-Resposta a Droga , Endopeptidases/metabolismo , Feminino , Guam , Humanos , Concentração Inibidora 50 , Lisossomos/metabolismo , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Peptídeos/química , Peptídeos/farmacologia , Inibidor 1 de Ativador de Plasminogênio/metabolismo , Inibidores de Proteases/farmacologiaAssuntos
Inibidores da Protease de HIV/farmacologia , Lopinavir/farmacologia , Nelfinavir/farmacologia , Tripanossomicidas/farmacologia , Trypanosoma cruzi/efeitos dos fármacos , Ácido Aspártico Proteases/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Membrana Celular/ultraestrutura , Flagelos/efeitos dos fármacos , Flagelos/ultraestrutura , Dose Letal Mediana , Microscopia Eletrônica de Varredura , Microscopia de Fluorescência , Microscopia de Interferência , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/enzimologia , Mitocôndrias/fisiologia , Oxirredutases/efeitos dos fármacos , Oxirredutases/metabolismo , Permeabilidade/efeitos dos fármacos , Complexo de Endopeptidases do Proteassoma/efeitos dos fármacos , Complexo de Endopeptidases do Proteassoma/metabolismo , Trypanosoma cruzi/enzimologia , Trypanosoma cruzi/crescimento & desenvolvimento , Trypanosoma cruzi/fisiologiaRESUMO
FIV is a significant pathogen in the cat and is, in addition, the smallest available natural model for the study of lentivirus infections. Although divergent at the amino acid level, the cat lentivirus has an abundance of structural and pathophysiological commonalities with HIV and thus serves well as a model for development of intervention strategies relevant to infection in both cats and man. The following review highlights both the strengths and shortcomings of the FIV/cat model, particular as regards development of antiviral drugs.
