Treatment of human endometrial gland epithelial cells with chorionic gonadotropin/luteinizing hormone increases the expression of the cyclooxygenase-2 gene

Abstract

Endometrial glands contain higher levels of LH/hCG receptors than other cells in the human uterus. The present study investigated their functional importance. Northern and Western blotting and covalent receptor cross-linking demonstrated that human endometrial gland epithelial cells in culture contained multiple LH/hCG receptor transcripts and an 80-kDa receptor protein that can bind [125I]hCG in a hormone-specific manner. Culturing cells with highly purified hCG resulted in a time- and dose-dependent increase in steady state levels of cyclooxygenase-2 (COX-2) messenger ribonucleic acid and protein and the secretion of PGE2. Although human LH could mimic hCG, FSH, TSH, and alpha- or beta-subunits of hCG had no effect on COX-2 protein levels. Studies on signaling revealed that treatment of cells with hCG resulted in an increase in cAMP levels and protein kinase A (PKA) activity. Inhibition of PKA activity by cotreatment with isoquinoline-sulfonamide (H-89) prevented hCG from increasing COX-2 protein levels. Treatment with 8-bromo-cAMP mimicked the effect of hCG, and cotreatment with a selective inhibitor of type I PKA, 8-chloro-cAMP, prevented 8-bromo-cAMP and hCG from increasing COX-2 protein levels. The requirement of receptors for LH/hCG action was investigated by 24-h treatment of human endometrial gland epithelial cells with 21-mer phosphorothioate oligodeoxynucleotides (ODNs) synthesized from human receptor sequence. Treatment with 2 micromol/L antisense, but not sense, ODN resulted in a dramatic reduction in LH/hCG receptor protein levels. hCG was unable to increase COX-2 protein, PGE2, and cAMP levels in an antisense, but not in sense, ODN-treated cells. In summary, we conclude that hCG and LH treatment can increase expression of the COX-2 gene in human endometrial gland epithelial cells. The effect was time and dose dependent, hormone specific, and mediated by the cAMP/type I protein kinase A signaling pathway. The hCG actions require a normal complement of its receptors in cells. These hCG and LH effects may be another action of these hormones in human endometrium that is important for implantation of the blastocyst and continuation of pregnancy.