Quantitative analyses of epidermal growth factor receptors, HER-2/neu oncoprotein and cathepsin D in nonmalignant and malignant uteri

Hormone receptors and oncoproteins are receiving increased attention as possible prognostic factors in different carcinomas. Few data are available regarding quantification of their levels of expression in gynecologic malignancies. Epidermal growth factor (EGF) receptor specific binding capacities and affinities were measured by ligand binding assay using [125I]EGF in a competition mode with Accufit software (Lundon Software, Inc., Middlefield, OH). HER-2/neu oncoprotein was extracted from membranes and measured using an enzyme-linked immunosorbent assay. Cathepsin D was measured by an immunoradiometric assay using cytosols for steroid receptor analyses. EGF receptors in 23 nonmalignant uteri ranged from undetectable to 50 fmol/mg membrane protein (median, 0), with dissociation constant values of 1.2 x 10(-9) M to 8.5 x 10(-10) M, compared with EGF receptors in 76 endometrial cancers that ranged from undetectable to 7674 fmol/mg (median, 52). HER-2/neu oncoprotein ranged from undetectable to 2.9 HER-2/neu units (HNU)/microg protein (median, 0.6) in 41 nonmalignant uteri and from undetectable to 5.8 HNU/microg protein (median, 2.5) in endometrial cancers (n = 53). Cathepsin D ranged from 5 to 32 pmol/mg cytosol protein (median, 11) in 42 nonmalignant uteri and 18 to 144 pmol/mg protein (median, 42) in 29 endometrial cancers. Determination of the frequency and levels of EGF receptors, HER-2/neu protein, and cathepsin D in uteri with and without cancer and the availability of reference materials developed in our laboratory, will allow evaluation of their prognostic value in cancers of the uterus.