REGULATION OF EPIDERMAL GROWTH-FACTOR RECEPTOR SYNTHESIS BY OVARIAN-STEROIDS IN HUMAN ENDOMETRIAL CELLS IN CULTURE

The aim of this study was to investigate the effect of oestradiol and progesterone on epidermal growth factor (EGF) binding in human endomet rial glands and stromal cells in culture. Monolayers of isolated gland s or stromal cells were cultured for 6 days in the presence or absence of steroids which were replenished daily. Binding of I-125-labelled E GF was measured in the presence and absence of unlabelled EGF. Over a 6 day period, oestradiol caused a dose-dependent increase in the numbe r of EGF receptors in stromal cells, with a maximum effect of 150% con trol at a concentration of 10 nmol l(-1). The effect of progesterone w as also dose dependent and reached a maximum of 170% control at 100 nm ol progesterone l(-1). Oestradiol and progesterone in combination caus ed a greater increase in EGF receptor concentration than did either st eroid alone (control, 100 +/- 11%; oestradiol, 144 +/- 11% control; pr ogesterone, 200 +/- 20% control; oestradiol and progesterone, 288 +/- 6% control). Steroid treatment did not alter the affinity of the recep tor for EGF. The stage of the cycle of the tissue did not affect the r esponse to steroids. The effect of oestradiol was inhibited by the ant i-oestrogen ICI182780, and that-of progesterone by the anti-progestin RU486. In endometrial glands, neither oestradiol nor progesterone affe cted the number of EGF receptors, but the two steroids in combination induced an increase of 140 +/- 23% control where control was 100 +/- 1 5%. These data demonstrate that oestradiol and progesterone increase t he number of EGF receptors in vitro, and suggest that EGF is involved in mediating the actions of these steroids on the processes of prolife ration and differentiation in the human endometrium.