The effect of phorbol esters on tumor cell sensitivity to macrophage-mediated cytostasis.
Macrophage-mediated cytostasis was measured in a mouse syngeneic system where EL4 thymoma cells were found to be inhibited by C57B1/6 mouse macrophages. When tumor cells were pretreated with TPA, they became resistant to macrophage-mediated stasis. Nonelutriated as well as elutriated cells enriched in G1/early S and late S were sensitive to macrophage-mediated stasis. However, when elutriated cells were treated with TPA, cells enriched in G1/early S were rendered resistant to the cytostatic activity of macrophages whereas cells enriched in late S were not. The TPA effect on tumor cell susceptibility to stasis was found to be reversible and a nontumor-promoting phorbol ester, alpha-PDD, was ineffective.
Nycum
L M
LM
Department of Immunology, St. Jude Children's Research Hospital, Memphis, Tennessee 38101.
Fishman
M
M
D000818:Animals; D002273:Carcinogens / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D008264:Macrophages / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D010703:Phorbol Esters / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D013945:Thymoma / Q000473:pathology; D014407:Tumor Cells, Cultured / Q000473:pathology*
D002273:Carcinogens; D010703:Phorbol Esters; C008876:phorbol-12,13-didecanoate; D013755:Tetradecanoylphorbol Acetate