Effects of progestins and relaxin on glycodelin gene expression in human endometrial cells

OBJECTIVE: Glycodelin is an endometrial protein proposed to play an important role in embryonic implantation. We examined the effects of progestins and relaxin on glycodelin transcription, synthesis, and secretion. STUDY DESIGN: Northern blotting, metabolic labeling, and fluorography were used to assess glycodelin messenger ribonucleic acid and protein synthesis in endometrial tissue and cells. Luciferase reporter constructs transfected into endometrial adenocarcinoma cells ([shikawa cells) were used to determine whether progestins or relaxin could activate the glycodelin gene promoter. RESULTS: Progestins but not relaxin stimulated glycodelin secretion in primary epithelial cell cultures. A 452-base pair fragment of the glycodelin gene promoter was activated 4.3 ± 0.7 times normal by 10nmol/L promegestone; however, addition of relaxin to the same construct repressed progestin- stimulated promoter activation by >30%. CONCLUSION: Glycodelin transcription, synthesis, and secretion by endometrial epithelial cells were stimulated by progestins. However, relaxin failed to stimulate production of this immunomodulatory protein and, in fact, repressed progestin-stimulated activation of the glycodelin gene promoter.