Estrogen and progesterone receptor proteins in patients with breast cancer

Activation of antimetastatic Nm23-H1 gene expression by estrogen and its alpha-receptor

Metastasis of various malignant cells is inversely related to the abundance of the Nm23-H1 protein. The role of estrogens in tumor metastasis has now been investigated by examining the effect of E2 on the expression of the Nm23-H1 gene. Three human breast carcinoma cell lines, in which endogenous ERalpha is expressed at different levels, were used as a tool to assess the role of ERalpha in Nm23-H1 gene-mediated metastasis. E2 induced time-dependent increases in the abundance of Nm23-H1 mRNA and protein, with the extent of these effects correlating with the level of expression of ERalpha. E2 induced a marked decrease in the invasive activity of MCF-7 and BT-474 cells but had no effect on BCM-1 cells, which had virtually no ERalpha. Consistent with these results, the ER-mediated Nm23-H1 promoter activity was inhibited 3-fold by the E2 antagonist, ICI 182,780. Deletion analysis of the promoter region of the Nm23-H1 gene identified a positive estrogen-responsive element located in -108/-94. ER protein bound specifically to the -108/-79 fragment with high avidity. These results indicate that E2, acting through ERalpha, activated transcription of the Nm23-H1 gene via a positive estrogen-responsive element in the promoter region of the gene. These results suggest that E2 could suppress tumor metastasis by activating the expression of the Nm23-H1 gene.

The Estrogen Receptor Paradox in Breast Cancer: Association of High Receptor Concentrations with Reduced Overall Survival

Occasional reports have suggested an unfavorable effect of high estrogen receptor (ER) concentrations in primary breast cancer. In a population-based study we identified a subgroup explicitly exhibiting this seemingly paradoxical effect. ER concentrations were prospectively measured in a single laboratory by multipoint DCC assay. The relative risk of death in relation to the concentration of the interval-scaled variables ER and PgR was continually estimated by serial Cox regression analyses. Thus we circumvented loss of information due to primary categorization and avoided assumptions about relations between factor and risk. Based on 2,735 consecutively accrued primary breast cancer cases (median follow-up 56 months) we identified node-negative patients up to 60 years of age as the relevant subpopulation. High (>/=300 fmol/mg protein) ER concentrations exhibited an even more unfavorable impact (p < 0.03) on overall survival than ER concentrations of less than 10 fmol/mg protein. The well-known association of age and ER concentration was definitely excluded as an underlying biological cause for the increased risk. Differences in the distribution of other prognostic factors (HER-2/neu, Ki-67, DNA ploidy) were also excluded. As we observed a preponderance of pT2 tumors in the high ER group, we repeated the analysis, selectively focusing on pT2 tumors in the relevant subgroup, but the effect remained unchanged. In contrast, node-positive patients adjusted for age significantly (p = 0.02) profited from high ER concentrations as compared to the ER-negative group. As the phenomenon did not occur in node-positive patients, receptor defects in the high-ER group seem unlikely. To the contrary, we suspect that ER overexpressing cells are hypersensitive even to low levels of estrogens. Once they have sneaked past local barriers prior to primary surgery, they may cause early death in the absence of appropriate adjuvant endocrine therapy.

Immunohistochemical localization of estrogen receptor in the normal canine female genital tract

The distribution of estrogen receptor (ER) in the ovaries and uterus was studied throughout the estrous cycle in the bitch. The stage in the estrous cycle of 25 dogs was assessed by gross and histologic appearance of the uterus and ovaries and blood steroid hormone values. Demonstration of ER was performed by an indirect immunohistochemical technique with monoclonal antibodies. ER was found as a red nuclear staining in the surface, crypt, and glandular epithelium; in endometrial stroma cells; and in smooth muscle cells of the tunica muscularis of the uterus. Total scores of ER-positive cells varied during the estrous cycle, with the highest scores in the early proliferative stage and the lowest scores in the early secretory stage of the estrous cycle. These results are in concordance with the observations in other animals and the human uterus. In the canine ovaries, positive staining for ER was present in surface epithelium and subsurface epithelial ingrowths, which is in contrast with negative staining of human ovaries. This study confirms the earlier hypothesis that the epithelial ingrowths in canine ovaries may be responsive to blood steroid hormones.