REGULATION OF THE PROMOTER OF THE HUMAN CORTICOTROPIN-RELEASING HORMONE GENE IN TRANSFECTED HUMAN ENDOMETRIAL CELLS

Corticotropin-releasing hormone (CRH) is expressed in several peripher al tissues, including normal epithelial cells of the human and rodent uterus. However, the biological role of endometrial CRH is known in ne ither species. As a first step to clarify this role, we studied the re gulation of CRH promoter in endometrial cells. We performed homologous transfection experiments in Ishikawa cells, a human endometrial cell line, using a 0.9-kb fragment of the 5'-flanking region of the human C RH gene coupled to luciferase. Transfected cells were exposed for 18 h to 8-bromo cyclic adenosine monophosphate, forskolin, epidermal growt h factor, steroids (estradiol, progesterone, and the synthetic glucoco rticoid dexamethasone and their antagonists), and prostaglandin E(2); then the activity of the luciferase reporter was determined in the cel l lysates. We found that the activity of the 5'-flanking region of the CRH gene was stimulated by cyclic adenosine monophosphate and epiderm al growth factor and inhibited in a receptor-mediated, dose-dependent fashion by estradiol and dexamethasone. The antiglucocorticoid RU 486 acted as a glucocorticoid agonist, suppressing the CRH gene activation , while progesterone was devoid of any activity. Prostaglandin E(2) st imulated the CRH activation, and the prostanoid inhibitor indomethacin suppressed it, most probably by inhibiting endogenous prostaglandins. These findings suggest that endometrial CRH gene expression may be un der the negative control of estrogens and glucocorticoids and under th e positive control of prostaglandin E(2).