Estrogen receptor analysis in primary breast tumors by ligand-binding assay, immunocytochemical assay, and northern blot: a comparison.

Estrogen receptor (ER) status is an important parameter in breast cancer management. In this study, ER protein contents established by two conventional techniques were confronted to ER mRNA level, to analyze whether the latter may be introduced in routine assay. Eighty-seven breast tumor samples were examined. ER amounts were determined by ligand-binding assay (LBA) and by computer-assisted immunocytochemical assay (ICA), ER mRNA was analysed and quantified by northern blot. Seventy-seven percent of tumor samples examined were positive for ER mRNA and they all expressed the 6.7-kb receptor signal. No trace of small-sized ER mRNA variants was detected in any sample. Following akaike information criterion (AIC) discriminant analysis, a simple linear correlation was found between ER mRNA levels and ER amounts provided by LBA. This was not observed when either mRNA or LBA values were compared to ICA values. These latter were found to rapidly reach a plateau at increasing mRNA or LBA values. In conclusion, our data points to the linear correlation between ER amounts determined in breast tumors at both protein and mRNA levels by quantitative methods; they also indicate that the semi-quantitative computer-associated ICA may complement rather than replace these quantitative methods.

Estrogenic and anti-estrogenic regulation of estrogen receptor in MCF-7 breast-cancer cells: comparison of immunocytochemical data with biochemical measurements.

Data from immunocytochemical assessment of estrogen receptor (ER) regulation in MCF-7 cells under estrogenic and anti-estrogenic stimulation were compared with those obtained by enzyme immunoassay (Abbott ER-EIA). Similar trends were observed, although ER level variations were less marked when assessed immunocytochemically. We confirmed reports of ER disappearance in the presence of estrogens (Es; E2 and DES) and pure anti-estrogens (AEs; RU 58,668 and ICI 164,384) as well as its increase with partial AEs (4-OH-TAM and RU 39,119). E2-induced ER down-regulation was partly blocked by actinomycin D (AMD), okadaic acid (OK) and cycloheximide (CHX) when assessed by these 2 methods. Down-regulation by pure AEs was not impeded by CHX, indicating that they operate differently from Es (i.e., transformation of ER to a form sensitive to constitutive degradation activity). In situ pre-labeling of the cells with [3H]TAZ indicated that all investigated ligands eliminate pre-existing ER through binding to newly synthetized receptors, since [3H]TAZ co-valently associates with ER; E2 and RU 58,668 were more effective than 4-OH-TAM in this regard. CHX blocked ER disappearance even in the presence of pure AEs, which is in contrast to the data established with cells not pre-exposed to [3H]TAZ. Nuclear location of [3H]TAZ-ER complexes may explain this discrepancy, since pure AE-ER complexes were reported to be incapable of nuclear translocation.

[Immunocytochemical assay of estrogen receptors in puncture products of breast carcinomas]. / Dosage immunocytochimique du récepteur d'oestrogène dans les produits de ponctions de carcinomes mammaires.

In a pilot study, estrogen receptors (ER) were assayed on 42 surgically removed breast tumors by the following 3 methods: biochemical assay with dextran coated charcoal (DCC), Abbott immunoenzymatic (ER-EIA) and immunocytochemical (ER-ICA) technics. DCC and ER-EIA were performed on biopsy specimens while ER-ICA was run on cytocentrifugated cells obtained by fine needle aspiration (FNA). ER contents were expressed according to an index taking into account the proportion of colored neoplastic cells and the intensity of staining. Statistical correlation coefficient (Spearman and Kendall) concordance, sensitivity and specificity between the results were calculated (ER - ICA/ER - EIA: P less than 0.001, r = 0.38, concordance = 83%, sensitivity = 86%, specificity = 77%; ER - ICA/DCC: P less than 0.05, r = 0.22, concordance = 77%, sensitivity = 85%, specificity = 63%; ER - EIA/DCC: P less than 0.001, (r = 0.60). As previously reported, both immunoassays showed good agreement. The weaker but nevertheless significant correlation found with reference DCC may be due to the heterogeneity of tumoral ER content. This hypothesis is supported by the variability of ER - ICA assays on multiple FNA performed in 16 cases from our series. Use of multidirectional FNA slightly improved the results. Nevertheless, ER - ICA appear to be a good semi-quantitative method and might be helpful in the follow-up of metastasis treated with anti-estrogen, especially in small lesions not assayable by DCC.