THE EPIDERMAL GROWTH-FACTOR RECEPTOR IN THE HUMAN ENDOMETRIAL ADENOCARCINOMA CELL-LINE HEC-1-B

The binding characteristics and steroidal regulation of the EGF recept or were investigated in the human endometrial adenocarcinoma cell line HEC-1-B. The cell line was shown to possess a single, high affinity b inding site for epidermal growth factor receptor (EGF) with a K-d of 3 .09 +/- 1.39 nM (mean +/- SD, n = 6) and binding of 845 +/- 311 fmol/m g protein (mean +/- SD, n = 6). The protein kinase C activator, phorbo l 12-myristate, 13-acetate (PMA) increased the K,of the EGF receptor i n a dose dependent manner (PMA: 0, 1, 10, 100 nM; K-d:4.1, 5, 10, 50 n M, respectively). The effect of PMA (10 nM) was overcome by preincubat ing the cells with the protein kinase C inhibitor staurosporine (1 mu M) prior to the addition of PMA. The effect of the ovarian steroids oe stradiol and progresterone on EGF receptor accumulation was studied by pretreating the cells for 6 days with oestradiol or progesterone in p henol red free DMEM:F12, 1:1 supplemented with 5% charcoal stripped fe tal calf serum. Both steroids were shown to increase EGF receptor numb er with a maximum 5- and 7-fold increase in the presence of 1 nM oestr adiol or 1 mu M progresterone, respectively. The study demonstrates th e presence of a high affinity binding site for EGF in HEC-1-B cells wh ich is regulated by oestradiol and progresterone.