phorbol-12-13-didecanoate and Thymoma

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.

Topics: Animals; Carcinogens; Cell Cycle; Cell Division; Macrophages; Mice; Mice, Inbred C57BL; Phorbol Esters; Tetradecanoylphorbol Acetate; Thymoma; Tumor Cells, Cultured