Fluorescent ligands, used in histocytochemistry, do not discriminate between estrogen receptor-positive and receptor-negative human tumor cell lines

Characterization of polyclonal antibodies against the N-terminal domain of the human androgen receptor

Antibodies against the N-terminal domain of the human androgen receptor (hAR) were prepared by two different approaches. Firstly, rabbits were immunized with a beta-galactosidase-hAR (amino acids (aa) 174-353) fusion protein. Secondly, two synthetic peptides corresponding to potentially antigenic sites located within this fragment (aa 201-222 and 301-320) were used as immunogens. The obtained antisera contained high titer anti-hAR antibodies as was established with several independent methods (e.g. sucrose gradient centrifugation, immunoprecipitation, Western blotting). The two anti-peptide antisera specifically stained nuclei of glandular epithelial cells in frozen sections of human prostate tissue. Progesterone, estradiol and glucocorticoid receptors were not immunoprecipitated with these antisera. The specific hAR antibodies provide new tools for the characterization of this steroid receptor as well as for diagnostic purposes in pathology of the human prostate and androgen resistance.

Hormone receptor assays: clinical usefulness in the management of carcinoma of the breast

The revision of the subcellular model of hormone action is described, with an incorporation of potential autocrine mechanisms. A general overview of available assay methodologies considers the major disadvantages of earlier methods and describes in detail the current methodologies (sucrose gradient analysis, dextran-coated charcoal assays, ER-EIA, ERICA). A major concern with clinical correlations of response to hormone receptor levels is the quality assurance of the multicentric programs. Results from national and international programs are considered. The clinical correlations are divided into four major categories: (1) the response to hormone deprivation (oophorectomy or adrenalectomy), (2) the development of specific agents which exploit receptor mechanisms (antiestrogens) or inhibit steroid biosynthesis (aminoglutehimide), (3) the rates of recurrence of tumors following mastectomy, and (4) the correlation of hormone receptors with current adjuvant therapies.

Determination of steroid hormone-dependency of tumours utilizing tissue sections. Survey of histochemical techniques and their application in surgical pathology

The growth of neoplasms originating from steroid hormone target tissues may be hormone-dependent. It has been clearly demonstrated that the oestrogen and/or progestagen receptor status predicts the response to endocrine treatment and the prognosis of breast cancer. However steroid receptor determination in tumour cytosols has several limitations, which can partly be resolved by (immuno) histochemical detection of steroid hormone-responsive tumour cells. A variety of histochemical techniques including autoradiography of tritiated steroids, immunohistochemistry with antibodies to steroid hormones, histochemistry with fluorescent ligands of low molecular weight and fluorochrome- or enzyme-labelled macromolecular probes are discussed. It is concluded that there is as yet no substantial evidence that these methods visualize steroid receptors or detect steroid hormone-responsiveness of tumour cells. On the other hand, immunohistochemical demonstration of oestrogen receptors with monospecific antibodies seems validated and indications have been obtained that this information is clinically relevant. Recent developments suggest that immunocytochemistry of receptors and specific hormone-induced proteins, flow cytometric analysis and probably hybridocytochemistry in the future will help to improve management of steroid hormone-dependent tumours.

17 alpha-allyl estradiol analogues as candidates for development of high-affinity fluorescein-estradiol conjugates

In order to develop stable, high-affinity fluorescein-estradiol conjugates, the fluorescein moiety must be leashed to the estradiol molecule at a point which interferes least with estradiol's binding to the receptor. Because of the high affinity of 17 alpha-substituted estradiol (e.g. ethynyl estradiol), we investigated a series of 17 alpha-substituted estradiol compounds to determine the optimal properties of a leash at this position. Twelve estradiol derivatives bearing a three-carbon 17 alpha side chain with or without a terminal functional group and with varying degrees of unsaturation were synthesized. Initial comparison of the receptor binding affinities of some of these derivatives suggested that three factors might reduce affinity: internal hydrogen bonding of the 17 beta-hydroxyl proton with an oxygen atom of the 17 alpha side chain; hydrophilicity of the ligand; or steric interference of the side chain with receptor binding. Further comparisons were designed to evaluate the relative contribution of these factors. The results suggest that the relative affinities of these 17 alpha-substituted estradiol derivatives are influenced primarily by the steric interference of the side chains and also by their hydrophilicity. Internal hydrogen bonding involving the 17 beta-hydroxyl proton does not seem to have a profound effect.

Androgen-dependent growth regulation of and release of specific protein(s) by the androgen receptor containing human prostate tumor cell line LNCaP

Hormone sensitivity, as indicated by the presence of steroid hormone receptors and by the effect of androgens and anti-androgens on the release of proteins by cultured cells of the human prostate tumor cell line lymph node carcinoma of the prostate-fast growing colony (LNCaP-FGC), has been studied. The growth of the LNCaP-FGC cells were stimulated by androgens in a dose-dependent way. Under optimal conditions the synthetic nonmetabolizable androgen 17 beta-hydroxy-17 alpha-methyl-(3H)-estra-4,9,11-trien-3-one (R1881) (0.1 nM) stimulated cell growth by approximately 2.3 times. Increasing doses of R1881 (1-100 nM) partly decreased the stimulation of the cell growth. The anti-androgen cyproterone acetate exerted inhibitory effects on cell growth. The nuclear extract of the LNCaP-FGC cells contained 17,000 +/- 2,500 (mean +/- SD) KCl-extractable, nuclear androgen receptor sites/cell. Estrogen and progesterone receptors were not detectable in the nuclear extracts nor in cytosol, indicating that these receptors were absent. The release of proteins in the culture medium was studied using incorporation of the 35S-methionine, sodium dodecyl sulfate (SDS)-gel electrophoresis, and fluorography. Cells grown in media containing charcoal-stripped fetal calf serum released significantly lower amounts of a protein with an apparent molecular mass of 42,000 daltons. The release of this 42-kD protein could be restored in cells cultured in the presence of 5 alpha-dihydrotestosterone (0.1-1 microM) or R1881 (0.1-100 nM), whereas the addition of estrogens or corticosteroids had no effect. In the presence of anti-androgens, such as cyproterone acetate and 5,5-dimethyl-3-(4-nitro-3-(trifluoro-methyl)-phenyl)-2,4-imidasolidin edione, inhibitory effects on the release of the 42-kD protein were observed. The observed parallel between the effects of (anti)-androgens on the growth of the LNCaP prostate cells and the release of the 42-kD protein suggests that this protein is involved in the regulation of malignant prostate cell growth.

Comparative histological, histochemical, immunohistochemical and biochemical studies on oestrogen receptors, lectin receptors, and Barr bodies in human breast cancer

The present study performed on a total of 567 cases of human female breast cancer compares the results of the biochemical assay (dextran-coated charcoal assay = DCC) for oestrogen receptor (ER) with those of several morphological methods developed for the detection of the ER or for the prediction of prognosis by use of other systems (FSA = fluorescent ligand binding assay, ER-ICA = monoclonal antibody assay for ER, LRA = lectin receptor assay using peanut agglutinin, and Barr body estimation). Whereas no correlation at all was observed among the results of the DCC and those of the FSA and Barr body estimation, the ER-ICA and the LRA showed an unanimous tendency towards higher values of ER with increasing intensity of the staining product. The results of the ER-ICA may be expressed by an immuno-reactive score (IRS) calculated from the staining intensity (SI) and the percentage of positive cells (PP). The morphological methods are evaluated with special regard to their correlation with the DCC, their theoretical basis, and their practical application. In summary, the ER-ICA appears to be the sole method directly visualizing the ER protein and--in contrast to the DCC--is therefore completely independent of the content of endogenous or exogenous oestrogens in the tumor tissue. The LRA provides valuable additional information concerning tumour differentiation and possible response to endocrine therapy, whereas the FSA and Barr body estimation should be considered as obsolete and should therefore be abandoned.

Rapid and sensitive detection of oestrogen receptors in cells and tissue sections by autoradiography with 125I-oestradiol

The presence of receptors for steroid hormones in individual cells and tissue sections was assessed within 4-24 h using dry mount autoradiography with radio-iodinated oestradiol. Low affinity and nonspecific binding of steroids were significantly reduced by washing the cells or sections with diluted antiserum to oestradiol. For cells of the MCF-7 cell line variations in grain density were observed, indicating that cells of the MCF-7 cell line are heterogeneous with respect to their cellular receptor concentrations of oestrogen receptors. Receptor-negative cells, such as peritoneal macrophages, did not retain oestradiol label. In tissue sections of rat and calf uterus, predominant labelling was observed on the endometrial gland cells and stroma. Oestradiol receptor binding in the uterus cytosol for both radio-iodinated and tritiated oestradiol showed the same qualitative characteristics as determined by sucrose gradient sedimentation profiles and a comparable amount of binding sites was found for both labels. The relative binding affinity of 125I-oestradiol compared to [3H]oestradiol is about 70-80%. The dry mount autoradiographic technique as presented can be used for rapid screening of heterogeneity in oestrogen receptor distribution in cells and tissue sections, since this technique reveals differences in receptor concentrations on the single cell level.