SELECTIVE REGULATION OF RNK-16 CELL-MATRIX METALLOPROTEINASES BY THE EP(4) SUBTYPE OF PROSTAGLANDIN E(2) RECEPTOR

Cell surface expression of multiple structurally and functionally dist inct prostaglandin E(2) (PGE(2)) receptors (Rs), designated the EP(1), EP(2), EP(3), and EP(4) Rs, is a principal determinant of the diverse cellular effects of PGE(2). The RNK-16 line of rat large granular lym phocytes, which has served as a model for natural killer cells, coexpr esses a mean of 1092 EP(3) Rs and EP(4) Rs per cell with a mean K-d of 2.7 nM. The presence of the EP(3) and EP(4) Rs and the absence of the EP(1) and EP(2) Rs were revealed by inhibition of [H-3]PGE(2) binding by the EP(3)/EP(1)R agonist sulprostone, the EP(3)/EP(2)/EP(4)R agoni st M&B 28767, and the EP(2)/EP(4)/EP(3)R agonist misoprostol but not b y the EP(1)R antagonist SC-19220 or the EP(2)R agonist butaprost. Func tional EP(4) R expression was confirmed by finding that PGE(2) and mis oprostol, but not butaprost or sulprostone, evoked increases in the in tracellular concentration of cyclic AMP ([cAMP](i)) in RNK-16 cells. M atrix metalloproteinase (MMP)-1 and -3 were identified by zymography a nd Western blots as the principal MMPs secreted by RNK-16 cells. Secre tion of both MMPs by RNK-16 cells attained a maximal level after 24 h of incubation and was enhanced significantly by 10(-9) to 10(-7) M PGE (2), 10(-6) M misoprostol, and 10(-4) M dibutyryl cyclic AMP, but not by the EP(3)R agonist sulprostone. Thus, the effect of PGE(2) on RNK-1 6 cell MMP secretion is mediated by an EP(4) R-dependent mechanism inv olving increases in [cAMP](i). The migration of RNK-16 cells across mi cropore filters, without or with a layer of Matrigel, was stimulated c hemokinetically by PGE(2) and misoprostol. PGE(2)-elicited chemokinesi s of RNK-16 cells across a Matrigel model basement membrane, but not a cross a microfilter alone, was suppressed by the GM 6001 inhibitor of MMP activities. Stimulation of MMP activities in RNK-16 cells by the E P(4)R thus facilitates migration of the NK cells across vascular basem ent membranes.