RESUMO
A related series of styryllactones with small functional and stereochemical variations were compiled for a comparative study of their apoptotic activities toward two tumorigenic and one non-tumorigenic control cell line. While a substantial range of intrinsic activity was observed, the relative order of activity of the different compounds toward the cell types varied somewhat as did the relative ratios of apoptosis and necrosis observed in conjunction with the loss of cell viability. While some of the styryllactones showed substantial activity, a small but significant apoptosis-induced synergism was demonstrated with (-)-altholactone and TRAIL (tumor necrosis factor-related apoptosis-inducing ligand).
Assuntos
Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Lactonas/farmacologia , Ligante Indutor de Apoptose Relacionado a TNF/metabolismo , Antineoplásicos/síntese química , Antineoplásicos/química , Sobrevivência Celular/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Lactonas/síntese química , Lactonas/química , Conformação Molecular , Estereoisomerismo , Relação Estrutura-Atividade , Ligante Indutor de Apoptose Relacionado a TNF/química , Células Tumorais CultivadasRESUMO
Human leukemic T-lymphocytes undergo extensive and rapid apoptosis in the presence of L1AD3, a small cyclic peptide derivative of cobra cardiotoxin. The first step in this process involves its binding to membranes of susceptible cells. By the use of a biotin "handle" synthetically incorporated at the N-terminus of L1AD3, we show that binding is saturable and selective: normal human peripheral blood lymphocytes do not bind this peptide. Fluorescence resonance energy transfer experiments indicate that the binding sites are separated by at least 55 A. Loss of binding occurs if membrane proteins are enzymatically degraded, suggesting that L1AD3's target is a cell-membrane surface protein receptor. Finally, crosslinking of cyclic BTNL1AD3 peptide to a leukemic T-cell membrane surface receptor, as examined using a biotin-avidin blot, indicated a molecular weight of approximately 34,400.
Assuntos
Apoptose , Proteínas Cardiotóxicas de Elapídeos/química , Proteínas Cardiotóxicas de Elapídeos/metabolismo , Leucemia de Células T/metabolismo , Animais , Avidina/química , Linfócitos B/metabolismo , Sítios de Ligação , Ligação Competitiva , Biotina/química , Biotinilação , Membrana Celular/metabolismo , Sobrevivência Celular , Cromatografia Líquida de Alta Pressão , Reagentes de Ligações Cruzadas/farmacologia , Dissulfetos , Relação Dose-Resposta a Droga , Eletroforese em Gel de Poliacrilamida , Citometria de Fluxo , Transferência Ressonante de Energia de Fluorescência , Humanos , Macrófagos/metabolismo , Espectrometria de Massas , Modelos Químicos , Modelos Moleculares , Monócitos/metabolismo , Oxigênio/metabolismo , Peptídeos/química , Ligação Proteica , Estrutura Terciária de Proteína , Espectrometria de Fluorescência , Linfócitos T/metabolismo , Tripsina/farmacologiaRESUMO
L1AD3 is a small cyclic synthetic peptide designed to resemble the first loop of a cobra venom cytotoxin. Instead of inducing membrane disruption similar to that caused by the parent toxin, L1AD3 promotes extensive and unusually rapid apoptosis in leukemic T-cells without making the plasma membrane permeable to small fluorescent dyes. Within 4 h, micromolar concentrations of L1AD3 almost totally inhibit thymidine incorporation, and ATP levels decrease significantly. By contrast, normal human white blood cells are not affected by L1AD3, nor is heart cell function affected by it. If L1AD3 kills by interacting with targets that are different from those of currently applied agents, this peptide, or a derivative of it, could become a useful adjunct for cancer chemotherapy.
