Biomedical subjects

E M Berns

Publications and source records attributed to E M Berns.

At least 37 records · Page 2Linked to original sources

PubMed1995

Association between RB-1 gene alterations and factors of favourable prognosis in human breast cancer, without effect on survival.

The retinoblastoma (RB) tumour suppressor gene has been associated not only with retinoblastoma but also with several other tumours like osteosarcoma, small cell lung carcinoma and prostate and breast cancer. We have studied the incidence of RB gene alterations in 96 primary breast tumours using Southern blotting techniques. The outcome has been related with patient and tumour characteristics, oncogene amplifications, p53 mutations and prognosis. RB gene alterations were found to occur more frequently in estrogen receptor (ER)-positive than in ER-negative tumours and less frequently in tumours with oncogene amplification than in tumours without oncogene amplification of HER2/neu, c-myc or 11q13. RB gene alteration was observed in tumours both with and without a p53 gene mutation. Data on 87 patients (mean age, 59.6 years; median follow-up, 108 months) and RB gene alterations revealed a significant association between the frequency of RB gene alterations and node-negative patients (p < 0.01) or smaller (< 2 cm) tumours (p < 0.01), but no relation with age, differentiation grade or (relapse-free) survival. Patients with and without RB gene alterations showed the same relapse-free and overall survival.

Adult↗

PubMed1995

Infrequent CDKN2 (MTS1/p16) gene alterations in human primary breast cancer.

Changes which lead to excessive cyclin production or to loss of cell cycle inhibition by proteins such as p16/MTS1 may release breast tumour cells from the constraints of cell division. In order to establish the frequency of MTS1/p16 gene alteration and its relation with genetic damage to the p53 and cyclin D1 genes, we have studied these gene abnormalities in 164 human primary breast cancers and in six breast cancer cell lines. Two breast cancer cell lines and one primary tumour showed a homozygous deletion of exon 2 of the MTS1 gene. Using single-strand conformation polymorphism and subsequent sequencing analysis, one tumour showed an alteration at codon 67 (CCC-->CTC; Pro to Leu). Another tumour showed a mutation at codon 98 (without amino acid change) with an additional polymorphism at codon 140. This polymorphism was also found in 13 other tumour samples, but has no effect on (disease-free) survival. From these data we conclude that the occurrence of CDKN2 (p16/MTS1) mutation in primary breast cancer is a rare event and is not likely to be involved in human breast tumour carcinogenesis and progression.

Base Sequence↗

PubMed1995

Molecular genetic evidence for unifocal origin of advanced epithelial ovarian cancer and for minor clonal divergence.

Detection of loss of heterozygosity (LOH) and DNA flow cytometry (FCM) were used to trace the origin of bilateral ovarian cancer from 16 patients. From each tumour the DNA index (DI) and LOH patterns for chromosomes 1, 3, 6, 11, 17, 18, 22 and X were determined with 36 microsatellite markers. Formalin-fixed, paraffin-embedded as well as frozen specimens were used. Flow cytometric cell sorting was used to enrich tumour cells for polymerase chain reaction (PCR)-driven LOH analysis. Analysis of the LOH data showed that in 12 of the 16 cases concordance was observed for all informative markers, namely retention of heterozygosity (ROH) or loss of identical alleles in both tumour samples. In four cases discordant LOH patterns were observed. In two cases the discordant LOH was found for one of the chromosomes tested while other LOH patterns clearly indicated a unifocal origin. This suggests limited clonal divergence. In the other two cases all LOH patterns were discordant, most likely indicating an independent origin. The number of chromosomes showing LOH ranged from 0 to 6. Comparison of DNA FCM and the LOH data showed that the latter technique has a higher sensitivity for the detection of a unifocal origin. In 14/16 cases evidence was found for a unifocal origin, while in two cases clonal divergence was found at LOH level and in two other cases clonal divergence at DNA ploidy level. In 12 cases the complete observed allelotype had developed before the formation of metastases, including the two cases showing a large DNA ploidy difference.

Carcinoma↗

PubMed1994

Ki-67 staining in benign, borderline, malignant primary and metastatic ovarian tumors: correlation with steroid receptors, epidermal-growth-factor receptor and cathepsin D.

Ki-67 immunoreactivity was studied in relation to immunohistochemically assessed expression of epidermal-growth-factor receptor (EGFR), estrogen receptor (ER) progesterone receptor (PgR) and cytosolic levels of cathepsin D in advanced human ovarian adenocarcinomas, borderline and benign cystadenomas and normal ovaries. A significantly higher number of Ki-67-positive cells were found in metastatic tumors vs. primary adenocarcinomas and in the total group of adenocarcinomas vs. benign/borderline cystadenomas. Cathepsin-D levels were also significantly higher in metastatic tumors than in primary adenocarcinomas, which in turn presented higher levels than were found in normal ovaries. However, no significant difference was observed between cathepsin-D levels in malignant adenocarcinomas and borderline/benign cystadenomas. Immunohistochemically assessed expression of ER and PgR was detected in variable percentages of epithelial tumor cells, and stromal cells were occasionally positive as well. In the group of primary adenocarcinomas, 46% were ER-positive and 34% were PgR-positive, although there was no significant difference between primary and metastatic lesions with respect to ER or PgR expression. Concordance between immunohistochemically assessed ER or PgR data and cytosolic ER and PgR levels measured with enzyme immunoassay was relatively low. EGFR, immunohistochemically assessed with MAb-EGFRI, was positive in 76% of the primary and in 78% of the metastatic adenocarcinomas. A strong positive association was detected between ER and PgR, and EGFR was observed to present a weak positive correlation with Ki-67 and ER. Cathepsin-D levels were not found to be significantly correlated with the expression of ER, PgR, EGFR or Ki-67.

Adenocarcinoma↗

PubMed1993

Cell biological factors associated with the response of breast cancer to systemic treatment.

A large number of cell biological parameters are currently available to predict the prognosis of patients with breast cancer, but it is still difficulty accurately to predict the response to treatment. A valuable prognostic factor can be a poor predictive factor for response, and vice versa. High tumor levels of ER, PgR, AR and pS2 predict a relatively good response to endocrine therapy, while EGF-R positively, HER2/neu positivity, aneuploidy, high proliferation indices and possibly high uPA levels indicate a high chance of poor response to endocrine therapy in metastatic breast cancer. With respect to chemotherapy, a high proliferation rate and HER2/neu amplification predict a good response to therapy in metastatic disease, while MDR gene expression and possibly c-myc amplification are related to a worse response. In conclusion, the newer cell biological parameters can be used to select high and low-risk patients, type of systemic treatment, and as targets for new treatment modalities.

Biomarkers, Tumor↗

PubMed1993

The prognostic value of epidermal growth factor receptors, determined by both immunohistochemistry and ligand binding assays, in primary epithelial ovarian cancer: a pilot study.

After our previous studies on the incidence of epidermal growth factor receptors (EGF-R) and its relationships with other tumour characteristics in more than 100 ovarian tumours, in the present study we investigated the prognostic value of EGF-R with respect to progression-free survival in 50 patients with primary ovarian cancer and sufficient follow-up (median 26 months, range 10-33 months). EGF-R was measured by both biochemical and two immunohistochemical methods, using two monoclonal antibodies (MAb), in addition to oestrogen receptors (ER) and progesterone receptors (PgR). EGF-R by ligand binding assay and Scatchard analysis were detectable in 63% of the tumours, by immunohistochemistry with MAb 2E9 in 82% and with MAb EGF-R1 in 78% of the tumours. ER-positivity was found in 58% and PgR-positivity in 38% of the patients. The results of the three measurements of EGF-R showed only weak to moderate associations with Spearman rank correlations (Rs) between 0.13 and 0.46. ER and PgR were only weakly correlated (Rs = 0.20) and they showed no significant association with EGF-R status. There was no clear evidence of the existence of correlations between receptor values and FIGO stage and tumour rest. Univariate Cox regression analyses showed that a higher FIGO stage and larger tumour rest were associated with shorter progression-free survival (P = 0.001), while PgR positivity was associated with a longer progression-free survival (P = 0.02). The level of EGF-R (irrespective of the method of determination used) showed a positive correlation with the risk of progression, but this correlation was not statistically significant.

Adult↗

PubMed1993

Prognostic factors and response to therapy in breast cancer.

For the integration of new cell biological prognostic factors in daily clinical practice, we need to know not only their prognostic power with respect to prediction of relapse free and overall survival, but also their possible relation to response to endocrine therapy or chemotherapy in order to select adequate treatment for each patient. A large number of cell biological parameters are currently available to predict the prognosis of patients with breast cancer, but it is still difficult to predict the response to treatment accurately. A valuable prognostic factor can be a worthless predictive factor for endocrine therapy or chemotherapy, and vice versa. High tumour levels of ER, PGR, AR and PS2 protein predict a relatively good response to endocrine therapy, whereas EGFR positivity, HER2/neu positivity, aneuploidy, high proliferation indices and possibly high u-PA levels indicate a good chance of a poor response to endocrine therapy in metastatic breast cancer. With respect to chemotherapy, a high proliferation rate and HER2/neu amplification predict a good response to therapy in metastatic disease, whereas MDR gene expression and possibly c-myc amplification are related to a worse response. In conclusion, the newer cell biological parameters can be used to select high and low risk patients and type of systemic treatment and can be used as targets for new treatment modalities.

Biomarkers, Tumor↗

PubMed1992

Receptors for hormones and growth factors and (onco)-gene amplification in human ovarian cancer.

Receptor status and gene amplification were studied in advanced human ovarian adenocarcinoma tissues, borderline and benign ovarian tumours and normal ovarian tissues. Sixty-five percent (53/82) of ovarian adenocarcinomas, 57% (8/14) of benign/borderline tumours and only 31% (5/16) of normal ovarian tissues studied showed specific 125I-EGF (epidermal growth factor) binding (median: 17; 10; and 0 fmol EGF-R/mg protein, respectively) and a significant increase in progesterone receptor (PgR) levels was observed in these groups (median: 5; 33; and 152 fmol/mg protein, respectively). No correlations were observed between the levels of EGF-R and the levels of either oestrogen receptors (ER) or PgR. All membrane samples of 25 adenocarcinomas studied by Scatchard analysis were positive for insulin-like growth-factor-I receptors (IGF-I-R) and contained higher IGF-I-R levels than membranes of 10 normal ovarian tissues, of which 9 were positive (median: 64 and 26 fmol IGF-I-R/mg membrane protein, respectively). Also, as measured by autoradiography, 37 adenocarcinoma tissues showed a higher expression of IGF-I-R (1.5+ to 4+) than sections derived from 10 normal ovarian tissues (1+). 125I-IGF-I binding was predominantly associated with epithelial tumour cells, the surrounding connective tissue was negative and in several samples high expression of IGF-I-R was found in areas of tumour necrosis. Southern blot analysis of DNAs isolated from 25 ovarian adenocarcinomas revealed no amplification of the IGF-I-R or the EGF-R gene. The HER2/neu gene was amplified only in 2 out of 3 histologically confirmed endometrioid adenocarcinomas studied but not in 22 other tumours. An amplification of the c-myc gene was observed in 28% (7/25) of the tumours. All c-myc-amplified tumours were PgR-negative. No rearrangement was observed for any of the genes studied. In conclusion, ovarian adenocarcinoma tissues show a decrease in PgR levels and an increased expression of IGF-I-R and EGF-R, in the absence of gene amplification, when compared to benign/borderline ovarian tumours and normal ovarian tissues. In addition, amplification of the c-myc and HER2/neu genes, without rearrangement of these genes, occurs in a minority of these tumours.

Adenocarcinoma↗

PubMed1992

Pleiotropic actions of suramin on the proliferation of human breast-cancer cells in vitro.

Suramin, a non-specific growth factor antagonist, is currently under investigation for treatment of cancer patients. We studied its action on 6 different human breast-cancer cell lines in vitro. In complete growth medium, pleiotropic effects were observed with respect to cell proliferation, i.e. suramin is stimulatory at low concentrations and inhibitory at higher concentrations, for 4 of the 6 cell lines studied. The various cell lines showed marked differences with respect to the antiproliferative action of suramin, the Evsa-T cells being by far the most sensitive ones. A suramin concentration of 100 micrograms/ml brought about a 100% stimulation of the proliferation of ZR/HERc cells, ZR 75.1 cells ectopically expressing a human epidermal growth factor receptor (EGF-R) cDNA. Although less pronounced (10 to 60% stimulation), a similar response was observed for the parent ZR 75.1 cells, as well as for T-47D and MDA-MB-231 cells. The non-specificity of the action of suramin was established by the observation that suramin-induced inhibition of cell proliferation could be abolished by insulin-like growth factor-I (IGF-I) or basic fibroblast growth factor (bFGF), and even by estradiol, both in complete growth medium and under defined serum-free conditions. Our data indicate that suramin exerts pleiotropic effects on the proliferation of human breast cancer cells in vitro, and confirm the non-specific nature of its action. The stimulatory effect of low concentrations of suramin on the proliferation of breast cancer cells may have important consequences for breast cancer patients treated with suramin.

Breast Neoplasms↗

PubMed1992

c-myc amplification is a better prognostic factor than HER2/neu amplification in primary breast cancer.

Amplification of the c-myc and HER2/neu genes was found in 20 and 23%, respectively, of primary breast cancer tissues derived from 282 patients (median follow-up, 74 months). c-myc amplification was observed more frequently in larger tumors (P = 0.01) and in lymph node-positive patients (P = 0.01) but was not associated with age, menopausal status, or with differentiation grade or steroid receptor status. c-myc amplification was strongly negatively correlated with HER2/neu amplification (P less than 0.001). In univariate analysis, amplification of c-myc proved to be a significant predictor of reduced relapse-free and overall survival (for both, P less than 0.001). In multivariate analysis for relapse-free survival, c-myc amplification significantly (P = 0.001) added to the prognostic power of tumor size (P less than 0.001), lymph node status (P less than 0.001), and estrogen receptor status (P = 0.003), with the highest relative failure rate (1.8) after lymph node status (2.2). In this pilot study, c-myc amplification was predictive for outcome, especially among patients with node-negative disease or steroid receptor-positive tumors; 51 and 46% differences in actuarial 5-year recurrence rates when compared to patients with tumors with normal c-myc gene copy numbers, respectively. HER2/neu amplification was not associated with relapse-free survival but weakly with shorter overall survival in univariate analysis (P = 0.035). Only in the relatively small subgroup of steroid receptor-negative tumors, HER2/neu amplification may identify those patients with an increased risk of death. In conclusion, amplification of c-myc is an independent powerful prognosticator, particularly in node-negative and steroid receptor-positive breast cancer, whereas HER2/neu amplification may be of limited prognostic value, only in steroid receptor-negative disease.

Adult↗

PubMed1992

Sporadic amplification of the insulin-like growth factor 1 receptor gene in human breast tumors.

A principal difference between malignant and normal cells is the aberrant expression of oncogenes. Previously, we have reported on the expression of the insulin-like growth factor 1 receptor (IGF-1-R) in 93% of the human primary breast cancers studied. In the present study, we observed an increased gene copy number of the IGF-1-R in only 19 (2%) of 975 cases studied. The gene copy number of tumors with an amplified IGF-1-R gene varies between 3 and 56 (median, 24 copies). In 11 breast tumor samples with high (greater than or equal to 20 copies) IGF-1-R gene copy numbers, an additional amplification of either the c-myc gene (n = 3) or int-2/bcl-1 genes (n = 5) was observed, whereas no amplification of the HER2/neu gene was detected. The c-fes gene (like the IGF-1-R gene located on chromosome 15q25-qter), was found coamplified with the IGF-1-R in two cases, in one case to the same high extent (38 gene copies, each) and in the other case to only a moderate extent (4 copies of the c-fes gene and 21 copies of the IGF-1-R gene). Tumors with an amplified IGF-1-R gene showed a noticeable increased expression of the IGF-1-R as measured by ligand binding assays on membrane preparations. The median amount of the IGF-1-R protein of the amplified tumors was observed to be 35 times higher when compared to nonamplified tumors (P less than 0.001). Patients with tumors containing a high (greater than or equal to 20 copies) IGF-1-R gene copy number tend to have a shorter median overall survival (42 months; range, 14-120+; n = 8) than patients with tumors having a low amplified (3-10 copies) IGF-1-R gene copy number (median, 77 months; range, 19.5-98+; n = 4).

Adult↗

PubMed1992

Prognostic factors in human primary breast cancer: comparison of c-myc and HER2/neu amplification.

Amplification of oncogenes in primary tumours may have prognostic and/or therapeutic significance for patients with breast cancer. We have studied HER2/neu and c-myc amplification together with steroid receptors in human primary breast tumours and related the outcome with (relapse-free) survival. A strong inverse correlation was found between HER2/neu amplification and the presence of oestrogen and progesterone receptors. Actuarial 5-years survival showed that breast cancer patients with c-myc amplification in their primary tumours experience a shorter relapse-free survival, especially in node-negative and in receptor-positive tumours, whereas HER2/neu amplification may be of prognostic value for overall survival in receptor-negative tumours. Overall, in our hands, c-myc amplification appeared to be a more potent prognosticator than HER2/neu amplification in human primary breast cancer.

Breast Neoplasms↗

PubMed1992

Prevalence of amplification of the oncogenes c-myc, HER2/neu, and int-2 in one thousand human breast tumours: correlation with steroid receptors.

The frequency of oncogene amplification described in the literature shows a large fluctuation, which could be attributed to the study of relatively small series of tumours, to selection of subgroups of patients, or, especially in retrospective studies, to selection of tumour material from the tumour-bank. To address this question, we have studied amplification of c-myc, HER2/neu and int-2/bcl-1 genes in a series of 1052 collected human breast tumours. The retrospective and prospective subgroups in this collected series of tumours were of equal size. c-myc was amplified in 17.1%, HER2/neu in 18.7% and int-2/bcl-1 in 14.1%, of all breast cancer specimens studied. In the retrospective subgroup the prevalence of amplification was 18.1% for c-myc; 22.6% for HER2/neu and 11.6% for int-2/bcl-1, whereas in the prospective subgroup an incidence of amplification of 16.1%, 15.1% and 16.3% for c-myc, HER2/neu and int-2/bcl-1, respectively was observed. HER2/neu amplification was negatively correlated with oestrogen receptor (ER) and progesterone receptor (PR) status (P less than 0.0001; for both), c-myc amplification was more prevalent in the PR-negative subpopulation (P less than 0.05) and int-2/bcl-1 amplification was positively correlated with ER status (P less than 0.001).

Breast Neoplasms↗

PubMed1992

Epidermal growth factor receptor in ovarian tumours: correlation of immunohistochemistry with ligand binding assay.

Epidermal growth factor receptor (EGFR) was studied in ovarian tumours with immunohistochemical (IH) and ligand-binding assay (LBA). Two different monoclonal antibodies (MoAbs: 2E9, EGFR1) with respect to detecting EGFR with different ligand-binding affinities (low, high and low) were used. When comparing the IH data of MoAbs, 2E9 and EGFR1 a significant correlation was found (2P < 0.0001). Both antibodies stained 77% of the adenocarcinoma samples. The incidence of positivity as well as the mean percentage of stained cells was increased in metastases when compared with primary lesions. In 12.5% overexpression of EGFR (score 3) was noticed in some of the tumour cells. This was not due to amplification of the EGFR gene in any of the 25 ovarian tumours studied (including 6 which showed high expression of EGFR in IH). EGFR was detected in 66% of the adenocarcinomas analysed with LBA. A statistically significant correlation was found between the maximum binding capacities of EGFR obtained from Scatchard plots and the percentage of positive tumour cells determined by MoAb EGFR1 (2P < 0.0001). A weaker correlation was found between the reactivity of MoAb 2E9 and LBA (2P < 0.1). Clinical studies are necessary to determine the possible prognostic impact of EGFR determined with either method, or whether a combination of both will give a better discrimination between high- and low-risk patients.

Adenocarcinoma↗

PubMed1990

Antiproliferative effects of suramin on androgen responsive tumour cells.

UNLABELLED: The effect of the polyanionic drug suramin on two androgen responsive tumour cell lines was studied. Human prostate tumour (LNCaP) cell growth is stimulated two- to three-fold by the synthetic androgen R1881 (0.1 nM) or EGF (1 ng/ml). Suramin (0.01-1.0 mM) inhibited the growth of LNCaP cells in a dose dependent way, both in the presence and absence of androgen or EGF. Growth was arrested in the G0/G1 phase of the cell cycle, but was resumed after removal of suramin. DDT-1 hamster ductus deferens tumour cells are stimulated by PDGF (25 ng/ml), b-FGF (10 ng/ml) and testosterone (10 nM). Suramin inhibited PDGF and b-FGF stimulated cell growth. However in the presence of testosterone, suramin showed a biphasic effect: stimulatory at low dose (0.01 mM) and inhibitory above 0.01 mM. Suramin decreased the apparent affinity of EGF binding sites on LNCaP cells with a two- to eight-fold increase in Kd at 0.1 and 1.0 mM suramin, respectively. IN CONCLUSION: suramin counteracts the growth stimulatory effects of both androgens and growth factors on androgen sensitive tumour cells. The effects are reversible after withdrawal of suramin.

Androgen Antagonists↗

PubMed1986

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.

Animals↗

PubMed1986

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.

Androgens↗

PubMed1985

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.

Animals↗