aplysiatoxin and Hemolysis

Aqueous extracts of the foot muscle of the marine mollusc Aplysia californica contain a proteins(s) that stimulates cytolysis and prostaglandin production in the C-9 rat liver cell line and hemolysis of red blood cells. Partial purification of the protein by ion exchange chromatography and fast protein liquid chromatography resulted in parallel increases in specific activity for prostaglandin production and hemolysis. Prostaglandin release occurred both at cytolytic concentrations of the protein and at lower concentrations that caused no apparent alterations in cell morphology. Differential sensitivity of a variety of cell lines to stimulation of prostaglandin production was observed; one group of cells, including the C-9 rat liver cell line, displayed a 5-fold stimulation of arachidonic acid metabolism with 1-3 micrograms of a partially purified protein preparation, while a second group was insensitive to concentrations as high as 20 micrograms protein of that preparation. Red blood cells also displayed differential sensitivity to hemolysis: rhesus and squirrel monkey red blood cells were 100-fold more sensitive to lysis by the protein than cebus monkey erythrocytes. Both activities were abolished by treatment with pepsin, trypsin or heat and both had a molecular weight of congruent to 45,000, as determined by gel filtration. Stimulation of both prostaglandin synthesis and hemolysis was Ca2+ dependent. These observations suggest, but do not prove, that the protein that causes lysis of red blood cells and the protein that stimulates arachidonic acid metabolism in the C-9 cell line is the same.

Topics: Animals; Aplysia; Arachidonic Acids; Cebus; Chromatography, High Pressure Liquid; Electrophoresis, Polyacrylamide Gel; Hemolysis; Hot Temperature; In Vitro Techniques; Liver; Lyngbya Toxins; Macaca mulatta; Mice; Molecular Weight; Muscles; Prostaglandins; Rabbits; Rats; Saimiri; Species Specificity

Human peripheral blood monocytes were cultured and exposed to plant diterpenes, indole alkaloids and polyacetates with various degrees of tumor-promoting activity. The effect of the above-mentioned encounter on monocyte function was examined, as expressed by H2O2 production and lysis of dog erythrocytes by the cells, and the inhibition of 3H-PDBu binding to the monocytes by the various test agents. The most effective reagents in both activation of monocyte function and inhibition of 3H-PDBu binding were 12-0-tetradecanoyl-phorbol 13-acetate (TPA), phorbol 12, 13 dibutyrate, teleocidin, and aplysiatoxin which are known to be strong tumor promoters. Strong stimulation of monocyte function was also exerted by the weak tumor promoters, phorbol 12-retinoate 13-acetate, mezerein and debromoaplysiatoxin. Non-tumor-promoting phorbol diterpenes such as phorbol 12, 13-diacetate, phorbol 12-myristate, phorbol 13-acetate and 4-alpha TPA were 1,000 times less effective than TPA in monocyte stimulation and inhibition of 3H-PDBu binding. These results indicate that stimulation of human monocyte H2O2 production and related cytotoxicity might discriminate effectively between tumor-promoting and non-tumor-promoting reagents.

Topics: Binding, Competitive; Caenorhabditis elegans Proteins; Carcinogens; Carrier Proteins; Cells, Cultured; Cytotoxicity, Immunologic; Diterpenes; Hemolysis; Humans; Hydrogen Peroxide; Lyngbya Toxins; Monocytes; Oxygen Consumption; Phorbol Esters; Protein Kinase C; Receptors, Drug; Receptors, Immunologic; Structure-Activity Relationship