Modulation of tumor cell adherence by prostaglandins.

The initiation of tumor cell metastasis is thought to involve the adherence of circulating tumor cells to endothelial cells and/or basement membranes. The adherence of Walker carcinosarcoma tumor cells to foreign surfaces induced by phorbol myristate acetate and the chemotactic formyl peptide, formylmethionyl-leucyl-phenylalanine is inhibited by prostacyclin and 15-S-15-methyl PGE1 in a dose-dependent manner. The inhibition of tumor cell adherence by prostacyclin and 15-S-15-methyl PGE1 is associated with a 3- to 5-fold increase in intracellular cyclic adenosine monophosphate (cAMP) concentrations. The data suggests that the local production of prostaglandins may be an important modulator of tumor cell metastasis due to its direct effect on the tumor cells.