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Exp Cell Res ; 338(2): 251-60, 2015 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-26302264


Cellular levels of inhibitor of apoptosis (IAP) proteins are elevated in multiple human cancers and their activities often play a part in promoting cancer cell survival by blocking apoptotic pathways, controlling signal transduction pathways and contributing to resistance. These proteins function through interactions of their BIR (baculoviral IAP repeat) protein domains with pathway components and these interactions are endogenously antagonized by Smac/Diablo (second mitochondrial activator of caspases/direct IAP binding protein with low isoelectric point). This report describes development of synthetic smac mimetics (SM) and compares their binding, antiproliferative and anti-tumor activities. All dimeric antagonists inhibit in vitro smac tetrapeptide binding to recombinant IAP proteins, rescue IAP-bound caspase-3 activity and show anti-proliferative activity against human A875 melanoma cells. One heterodimeric SM, SM3, binds tightly to IAP proteins in vitro and slowly dissociates (greater than two hours) from these protein complexes compared to the other antagonists. In addition, in vitro SM anti-proliferation potency is influenced by ABCB1 transporter (ATP-binding cassette, sub-family B; MDR1, P-gp) activities and one antagonist, SM5, does not appear to be an ABCB1 efflux pump substrate. All dimeric smac mimetics inhibit the growth of human melanoma A875 tumors implanted in athymic mice at well-tolerated doses. One antagonist, SM4, shows broad spectrum in vivo anti-tumor activity and modulates known pharmacodynamic markers of IAP antagonism. These data taken together demonstrate the range of diverse dimeric IAP antagonist activities and supports their potential as anticancer agents.

Antineoplásicos/farmacologia , Transporte Biológico/efeitos dos fármacos , Caspase 3/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/antagonistas & inibidores , Proteínas Mitocondriais/antagonistas & inibidores , Subfamília B de Transportador de Cassetes de Ligação de ATP/metabolismo , Animais , Apoptose/efeitos dos fármacos , Proteínas Reguladoras de Apoptose , Biomimética/métodos , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Feminino , Células HCT116 , Humanos , Proteínas Inibidoras de Apoptose/antagonistas & inibidores , Melanoma/tratamento farmacológico , Melanoma/metabolismo , Camundongos Endogâmicos BALB C , Camundongos Nus , Ligação Proteica/efeitos dos fármacos , Estrutura Terciária de Proteína/efeitos dos fármacos