ERE environment- and cell type-specific transcriptional effects of estrogen in normal endometrial cells

Our previous results have suggested a repression of E 2 (17 β-estradiol) effect on the c-fos gene of cultured guinea-pig endometrial cells. To investigate this repression, the expression of three human c-fos gene recombinants, pFC1-BL (−2250/+41), pFC2-BL (−1400/+41) and pFC2E (−1300/−1050 and −230/+41), known to be E 2-responsive in Hela cells, was studied in stromal (SC) and glandular epithelial cells (GEC). In both cellular types, pFC1-BL was not induced by E 2, even in the presence of growth factors or co-transfected estrogen receptor. The pattern of pFC2-BL and pFC2E expression was strikingly different and depended on the cellular type: pFC2-BL and pFC2E induction was restricted to the glandular epithelial cells and did not occur in the SCs. We argue for a repression of E 2 action which is dependent on the estrogen-responsive cis-acting element (ERE) environment and also cell type-specific involving DNA/protein and/or protein/protein interactions with cellular type-specific factors.