Clinical significance of analysis of estrogen and progesterone receptors in human uterine tissues

Estrogen (ER) and progesterone receptors (PR) in tumorous mammary gland tissues have been investigated for a long time. The clinical significance of measuring the amount of ER and PR in the normal and pathological endometrium and myometrium was assessed. Endometrial and myometrial tissue obtained by operation was placed in a vessel containing liquid nitrogen an dry ice. Homogenization was performed at 15 5 and 45 seconds in a buffer solution. After ultracentrifugation at 105 g for 1 hour cytosol fraction was separated and used for ER PR and protein analysis according to the method of Lowry. The ER content of normal endometrium was 4 times higher than that of normal myometrium however the PR content in normal endometrium was only 2 times higher than in normal myometrium. The ER content did not differ in cancerous endometrium but the PR content decreased 1.5 times. ER and PR amounts in myomatous neoplasm tissue increased 3 times compared with healthy myometrium. Robel et al. showed the ER increased to 6000-10000/cell after ovulation while the number of PR reached 14000/cell in the preovulation phase. IN 29 endometrial cancer patients a significant decrease of both were fund. The ratio of PR to ER was 7.9 in the endometrial tissues of healthy women compared with 2.28 in those with endometrial cancer. In the present investigation the respective ratios were 3.6 and 1.8; this low index was attributed to women in postmenopause without estrogen stimulation. The number of PR seems to be directly influenced by estrogens being higher in women with cyclical activity of the ovaries thus receptors in uterine tissue change depending on endocrine functions. Endometrium and myometrium are hormone-dependent tissues. The increase of Er and PR is characteristic of benign processes while the decrease of PR and especially of the PR/ER index indicates the malignant nature of the disease.