Formyl-methionyl-leucyl-phenylalanine induces prostaglandin E-2 release from human amnion-derived WISH cells by phospholipase C-mediated [Ca2+](i) rise

The presence of binding sites for formyl-methionyl-leucyl-phenylalanine (fM LP), its effect on prostaglandin E (PGE) release, and the signal transducti on pathway activated by the peptide were investigated in human amnion-deriv ed WISH cells. Our results demonstrate that specific binding sites for fMLP are present on WISH cells and that the peptide induces a significant incre ase of prostaglandin (PG)E-2 release. The kinetic properties of binding are similar to those previously found in amnion tissue prior to the onset of l abor, i.e., only one population of binding sites with low affinity for the peptide is present. Binding of H-3- fMLP in WISH cells is inhibited by N-t- butoxycarbonyl-methionyl-leucyl-phenylalanine, an fMLP receptor antagonist, with an IC50 value very close to that shown by nonlaboring amnion. The fML P-induced PGE(2) output is inhibited by indomethacin, quinacrine, and U-731 22, inhibitors of cyclooxygenase, phospholipase A(2), and phospholipase C, respectively. As regards the transduction pathway activated by fMLP, we dem onstrate that phospholipase C activation, followed by an increase of intrac ellular calcium concentration ([Ca2+](i)), is involved in response to the p eptide. Our results add further evidence to the role of proinflammatory age nts in the determination of labor. Furthermore, because WISH cells appear t o behave like nonlaboring amnion tissue, they represent the ideal candidate for in vitro investigation of the events triggering the mechanism of deliv ery.