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

Abstract

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 E2 (PGE2) and an array of agonists and antagonists. Glycosaminoglycan synthesis was assayed after extraction by measuring the [3H]glucosamine and [35S]sulphate incorporated into GAG and cAMP production was determined by radioimmunoassay. PGE2 significantly stimulated GAG synthesis. Neither 17-phenyl-trinor-PGE2, the EP1 selective agonist, nor sulprostone, an EP3 agonist, had any effect on GAG production. Butaprost, the EP2 selective agonist, also failed to increase GAG synthesis. AH6809, an EP2 antagonist, had no effect on PGE2-stimulated GAG production. AH23848, an EP4 antagonist, inhibited the GAG synthesis provoked by PGE2. PGE2 and butaprost significantly increased cAMP production. Both AH6809 and AH23848 inhibited the PGE2-stimulated cAMP production. H89, a cAMP-dependent protein kinase (PKA) inhibitor, did not inhibit PGE2-stimulated GAG synthesis and Sp-cAMPS, a selective PKA activator, failed to increase GAG production. In conclusion, both EP4 and EP2 receptors are present and functional in human cervical fibroblasts. Only EP4 receptors mediate PGE2 stimulated GAG synthesis in a PKA-independent pathway.