EP4 receptors mediate prostaglandin E2-stimulated glycosaminoglycan synthesis in human cervical fibroblasts in culture

The aim of this study was to determine the prostaglandin E (EP) receptors and second messengers implicated in glycosaminoglycan (GAG) synthesis by human cervical fibroblasts in culture. Human cervical fibroblasts were obtained from cervical biopsies in pre-menopausal, cycling women. Cultured cells were incubated with prostaglandin E(2) (PGE(2)) and an array of agonists and antagonists. Glycosaminoglycan synthesis was assayed after extraction by measuring the [(3)H]glucosamine and [(35)S]sulphate incorporated into GAG and cAMP production was determined by radioimmunoassay. PGE(2) significantly stimulated GAG synthesis. Neither 17-phenyl-trinor-PGE(2), the EP(1) selective agonist, nor sulprostone, an EP(3) agonist, had any effect on GAG production. Butaprost, the EP(2) selective agonist, also failed to increase GAG synthesis. AH6809, an EP(2) antagonist, had no effect on PGE(2)-stimulated GAG production. AH23848, an EP(4) antagonist, inhibited the GAG synthesis provoked by PGE(2). PGE(2) and butaprost significantly increased cAMP production. Both AH6809 and AH23848 inhibited the PGE(2)-stimulated cAMP production. H89, a cAMP-dependent protein kinase (PKA) inhibitor, did not inhibit PGE(2)-stimulated GAG synthesis and Sp-cAMPS, a selective PKA activator, failed to increase GAG production. In conclusion, both EP(4) and EP(2) receptors are present and functional in human cervical fibroblasts. Only EP(4) receptors mediate PGE(2) stimulated GAG synthesis in a PKA-independent pathway.