Immunocytochemical identification of estrogen receptor in ovarian carcinomas. Localization with monoclonal estrophilin antibodies compared with biochemical assays.

Estrogen receptor (estrophilin) has been identified in ovarian carcinomas by a variety of physicochemical methods. Since these methods require disruption of the tissue, they do not provide any anatomic information about the cellular distribution and location of receptor. The authors have used monoclonal estrophilin antibodies and an indirect immunoperoxidase technique to study the immunocytochemical localization of estrogen receptor in 43 tissue samples of ovarian carcinoma from 27 patients. The immunocytochemical findings were compared with the results of conventional estrogen receptor assays of cytosolic and nuclear extracts prepared from adjacent pieces of ovarian carcinoma. Exclusively nuclear localization of estrogen receptor was observed with the immunocytochemical technique in all of the 25 tumor samples which had a cytosolic estrogen receptor content, determined by either the dextran-coated charcoal or hydroxylapatite techniques, greater than 700 fmoles/gm wet weight of tissue. Only 3 of 16 tumor samples with cytosolic estrophilin concentrations of less than 700 fmoles/gm wet weight displayed nuclear staining for estrogen receptor; two of these three were metastases from receptor-rich primaries. Specific cytoplasmic staining for estrogen receptor was not observed. These results indicate that many ovarian carcinomas have estrogen receptor, predominantly localized in the nucleus, which is similar to tissues of the female genital tract (vagina, cervix, endometrium, fallopian tube) and breast carcinoma.