The epidermal growth factor receptor in the human endometrial adenocarcinoma cell line HEC-1-B

The binding characteristics and steroidal regulation of the EGF receptor were investigated in the human endometrial adenocarcinoma cell line HEC-1-B. The cell line was shown to possess a single, high affinity binding site for epidermal growth factor receptor (EGF) with a Kd of 3.09 +/- 1.39 nM (mean +/- SD, n = 6) and binding of 845 +/- 311 fmol/mg protein (mean +/- SD, n = 6). The protein kinase C activator, phorbol 12-myristate, 13-acetate (PMA) increased the Kd of the EGF receptor in a dose dependent manner (PMA: 0, 1, 10, 100 nM; Kd: 4.1, 5, 10, 50 nM, respectively). The effect of PMA (10 nM) was overcome by preincubating the cells with the protein kinase C inhibitor staurosporine (1 microM) prior to the addition of PMA. The effect of the ovarian steroids oestradiol and progresterone on EGF receptor accumulation was studied by pretreating the cells for 6 days with oestradiol or progesterone in phenol red free DMEM:F12, 1:1 supplemented with 5% charcoal stripped fetal calf serum. Both steroids were shown to increase EGF receptor number with a maximum 5- and 7-fold increase in the presence of 1 nM oestradiol or 1 microM progresterone, respectively. The study demonstrates the presence of a high affinity binding site for EGF in HEC-1-B cells which is regulated by oestradiol and progresterone.