Functional responses of tumor cells to phorbol esters: role for prostaglandins

The effects of phorbol esters on five murine cell lines were examined. In three of these lines, all of which were highly malignant, phorbol ester treatment induced motility and foreign surface adherence while concomitantly inhibiting proliferation. In two other, nonmalignant cell lines phorbol ester treatment stimulated proliferation but did not influence motility or adherence. Possible roles for prostaglandins in these responses were investigated. The mitogenic effects of the phorbol esters were duplicated by prostaglandin F2 alpha. In contrast, prostaglandin E1 and prostacyclin inhibited proliferation induced by the phorbol esters. These agents also inhibited phorbol ester-induced cell motility.