ABSTRACT
PURPOSE: We evaluated the comparative effects of intraprostatic injection of cobra cardiotoxin D and botulinum toxin type A on prostate structure in the rat model. MATERIALS AND METHODS: A total of 18 Sprague-Dawley® rats weighing 500 to 600 gm received a single 0.1 ml injection of saline (6), botulinum toxin type A (6) or the cardiotoxin D (6) component of cobra (Naja naja atra) toxin in the right and left ventral lobes of the prostate. At 14 days the rats were sacrificed. The prostate glands were harvested, weighed and processed for immunohistochemical and morphological studies. RESULTS: Prostate glands injected with cardiotoxin D showed significantly decreased weight compared to that of prostates injected with botulinum toxin type A and the saline control. Prostatic atrophy in the glandular component with flattening of the epithelial lining was seen histologically in rats that received botulinum toxin and cardiotoxin D. Each group injected with cardiotoxin D and botulinum toxin showed a significant increase in the number of apoptotic cells compared with controls while only the botulinum toxin group showed a significant increase in the number of proliferating cells. Only rats injected with botulinum toxin had body weight loss. CONCLUSIONS: Our study shows that intraprostatic injection of cobra cardiotoxin D induces prostatic atrophy and leads to a decrease in prostatic weight greater than that of intraprostatic injection of botulinum toxin type A. No systemic effects, such as decreased body weight, were noted after cardiotoxin D injection. Further studies are warranted but the statistically significant decrease in the number of proliferating cells implies a prolonged effect of cardiotoxin D.
Subject(s)
Cobra Cardiotoxin Proteins/pharmacology , Prostate/drug effects , Prostate/pathology , Animals , Atrophy/chemically induced , Botulinum Toxins, Type A/administration & dosage , Botulinum Toxins, Type A/pharmacology , Cobra Cardiotoxin Proteins/administration & dosage , Injections , Male , Rats , Rats, Sprague-DawleyABSTRACT
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).
Subject(s)
Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Lactones/pharmacology , TNF-Related Apoptosis-Inducing Ligand/metabolism , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Cell Survival/drug effects , Drug Screening Assays, Antitumor , Humans , Lactones/chemical synthesis , Lactones/chemistry , Molecular Conformation , Stereoisomerism , Structure-Activity Relationship , TNF-Related Apoptosis-Inducing Ligand/chemistry , Tumor Cells, CulturedABSTRACT
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.
Subject(s)
Apoptosis , Cobra Cardiotoxin Proteins/chemistry , Cobra Cardiotoxin Proteins/metabolism , Leukemia, T-Cell/metabolism , Animals , Avidin/chemistry , B-Lymphocytes/metabolism , Binding Sites , Binding, Competitive , Biotin/chemistry , Biotinylation , Cell Membrane/metabolism , Cell Survival , Chromatography, High Pressure Liquid , Cross-Linking Reagents/pharmacology , Disulfides , Dose-Response Relationship, Drug , Electrophoresis, Polyacrylamide Gel , Flow Cytometry , Fluorescence Resonance Energy Transfer , Humans , Macrophages/metabolism , Mass Spectrometry , Models, Chemical , Models, Molecular , Monocytes/metabolism , Oxygen/metabolism , Peptides/chemistry , Protein Binding , Protein Structure, Tertiary , Spectrometry, Fluorescence , T-Lymphocytes/metabolism , Trypsin/pharmacologyABSTRACT
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.
