Chicken Ovalbumin Upstream Promoter Transcription Factor to the Same cis-Acting Element

In stromal cells of endometriosis, marked levels of aromatase P450 (P450arom) mRNA and activity are present and can be vigorously stimulated by (Bu) 2cAMP or PGE 2 to give rise to physiologically significant estrogen biosynthesis. Since eutopic endometrial tissue or stromal cells lack P450arom expression, we studied the molecular basis for differential P450arom expression in endometriosis and eutopic endometrium. First, we demonstrated by rapid amplification of cDNA 5�-ends that P450arom expression in pelvic endometriotic lesions is regulated almost exclusively via the alternative promoter II. Then, luciferase reporter plasmids containing deletion mutations of the 5�flanking region of promoter II were transfected into endometriotic stromal cells. We identified two critical regulatory regions for cAMP induction of promoter II activity: 1) a �214/�100 bp proximal region responsible for a 3.7-fold induction, and 2) a �517/ �214 distal region responsible for potentiation of cAMP response up to 13-fold. In the �214/�100 region, we studied eutopic endometrial and endometriotic nuclear protein binding to a nuclear receptor half-site (NRHS, AGGTCA) and an imperfect cAMP response element (TGCACGTCA). Using electrophoretic mobility shift assay, cAMP response element-binding activity in nuclear proteins from both endometriotic and eutopic endometrial cells gave rise to formation of identical