Studies on estrogen receptor in normal and cancerous human uterine endometrium by immunological methods

Abstract

The presence of cytosol estrogen receptor (ER) and the ER of nuclear extracts in normal uterine endometrium and endometrial adenocarcinoma tissues were determined by radioreceptor assay (RRA) and enzyme immunoassay (EIA). In addition the intracellular localization of ER and tissue distribution of ER positive cells was demonstrated by immunocytochemical assay (ICA). The levels of cytosol ER measured by EIA and RRA had a significant correlation in normal endometrium (r = 0.90) (P less than 0.01) and endometrial adenocarcinoma (r = 0.96) (P less than 0.01) as well as in breast cancer (r = 0.93) (P less than 0.01). The ER measured by immunocytochemical method using the monoclonal anti-ER antibody obtained from breast cancer cells was applicable to the detection of the ER in uterine endometrial tissues. In endometrial adenocarcinoma, the levels of cytosol ER in G1 (Highly differentiated adenomatous carcinoma) tissues (187.6 +/- 189.0 fmoles/mg protein) were significantly higher than those in G2 (Moderately differentiated adenomatous carcinoma with partly solid areas) tissues (15.0 +/- 31.9 fmoles/mg protein) (P less than 0.05). The levels of cytosol ER peaked in the late follicular phase (432.0 fmoles/mg protein) and remained low in the other phases. Epithelial cells in the normal endometrium were stained uniformly by ICA, in contrast, ICA stained and non-stained cells existed concurrently in the same endometrial adenocarcinoma tissues. A similar finding was also shown in breast cancer tissues and may be related to the efficacy of anti-estrogenic drugs on the growth of whole cancer tissues.