Phorbol myristate acetate-induced adherence of Walker 256 carcinosarcoma cells.
Treatment of nonadherent Walker 256 carcinosarcoma cells with phorbol myristate acetate (PMA) causes these cells to become adherent to noncellular foreign surfaces such as nylon fibers and plastic culture dishes and to monolayers of endothelial cells. Increased adherence is first observed after a short lag period (5 to 15 min) and is transient. Other tumor-promoting analogs of PMA also induce this response, while inactive analogs of PMA do not. Simultaneous treatment of the cells with 2-deoxyglucose, colchicine, cytochalasin B, and cycloheximide indicates that the adherence response of the cells is an energy-dependent process that requires an intact cytoskeleton but does not require protein synthesis. Inhibitors of phospholipids and arachidonic acid metabolism including indomethacin, nordihydroguaiaretic acid, and p-bromophenacyl bromide greatly inhibit PMA-induced adherence, but acetylsalicylic acid is much less effective. PMA also increases the rate of attachment to plastic dishes of cells which would normally attach, although slowly, and grow as substrate-attached cells. However, PMA treatment has no effect on the subsequent degree of susceptibility of these cells to release from plastic dishes mediated by proteolytic enzymes. These findings suggest (a) that PMA may be useful in delineating the initial events involved in the adherence of cells to cellular and noncellular surfaces and (b) that PMA may stimulate tumor cell adherence in a manner similar to that of chemotactic peptides may be useful in delineating the events associated with chemotactic factor stimulation of these cells.