Increased progesterone receptor concentrations in bladder lesions of estrogen-treated Syrian hamsters

During studies of renal tumorigenesis induced by estrogen in Syrian hamsters, we have observed that about 15 to 20% of animals develop bladder lesions with an increased wet weight of tissue from 0.2 g to 0.4 to 1.7 g. Histological examination of the lesions showed a spectrum of changes from inflammatory reactions to squamous metaplasia and intense hyperplasia of the transitional epithelium. The concentration of progesterone-binding sites was increased in the bladders with lesions. No specific progesterone-binding sites could be detected in the cytosol of bladders from hamsters not treated with estrogen. The affinity constant for the progesterone-binding sites in cytosol from bladders with lesions was 10(9) M-1, the same as that reported for progesterone receptors in other target tissues for estrogen. The binding sites are specific for progesterone and are not competed for by 17 beta-estradiol, 5 alpha-dihydrotestosterone, or aldosterone.

Correlation of estrogen and progesterone receptors with histologic differentiation in endometrial adenocarcinoma

Endometrial carcinomas from 58 patients were graded histologically, and the histologic grade was compared with the estrogen and progesterone receptor content of the tumor tissues. Receptor content was determined by multiple concentration saturation analysis and sucrose density gradient analysis. A positive correlation was found between the presence of estrogen and progesterone receptors and the degree of tumor differentiation. The majority (85%) of well-differentiated lesions contained significant amounts of both steroid receptor proteins. In contrast, only 13% of the poorly differentiated lesions were characterized by the presence of detectable levels of both estrogen and progesterone receptor proteins. The relationship of receptor content and degree of differentiation to prognosis and potential for response to hormonal therapy is discussed.

Steroid hormone receptors in human colon cancers

Tumors from patients with primary colon cancer were studied for the presence of steroid hormone receptors for estrogen (E2), progesterone (Prog), dihydrotestosterone (DHT) and glucocorticoid. Ten of 33 (30%) tumors contained high affinity E2 receptors. Four were males and six females with positive assays predominantly from the left colon. Twenty-three of these tumors were also assayed for DHT and Prog and six (26%) contained all three receptors. An additional twelve tumors had at least one receptor, so that 70% of the tumors studied contained one or more receptors. Five of 22 (23%) samples were positive for glucocorticoid receptors. Common etiological factors associated with colon and breast cancer were briefly discussed. These factors, along with the presence of hormone receptors in primary colon malignancies suggest that some large bowel cancers may be endocrine-dependent.

Distribution, frequency, and quantitative analysis of estrogen, progesterone, androgen, and glucocorticoid receptors in human breast cancer

The distribution and frequency of steroid hormone receptors are described 329 patients with breast cancer. The distribution of each of the steroid hormone receptors is unimodal with a progressive increase in the proportion of patients positive at lower receptor values. Receptor values expressed as fmol/mg cytoplasmic protein are well correlated with values expressed as fmol/mg breast tumor. Estrogen receptor was positive in 53% of the patients; progesterone receptor was positive in 38% of the patients; glucocorticoid receptor was positive in 52% of the patients; and androgen receptor was positive in 31% of the patients. The type of tissue assayed did not affect steroid hormone receptor positivity. For primary tumors, there was no correlation between steroid hormone receptor positivity and location of the tumor in the breast, size of the tumor, or extent of the disease. Each of the steroid hormone receptors was positively associated with each of the other steroid hormone receptors. Estrogen receptor was correlated with menopausal status and axillary nodal status, but these correlations did not exist for the other steroid hormone receptors. Estrogen receptor was not correlated with age after adjustment for menopausal status. The other steroid hormone receptors were not correlated with age.

Estrogen receptors and tumor associated antigens in breast cancer

The methods of performing estrogen and progesterone receptors and the role of receptors in the management of the patient with breast cancer are reviewed. Quality control of the assays and concentrations of receptor protein in normal tissues is emphasized as is the possible relationship of estrogen receptor protein to carcinoembryonic antigen.

Estrogen and progesterone receptors in human breast cancer with concomitant assay of plasma 17beta-estradiol, progesterone, and prolactin levels

The specific estrogen receptor in the cytosol of human breast cancer tissue was assayed in 217 primary cases. The specific progesterone receptor was also assayed in 48 cases as evidence of estrogen action on the tissue. Both receptors were positive in 45.8% of all cases. Plasma 17beta-estradiol and progesterone were assayed concomitantly with these steroid receptors. The higher hormone levels were found in the cases with fewer receptor binding sites. The relationship between 17beta-estradiol levels in tumor cytosol and the number of binding sites was more clearly observed. Plasma prolactin levels, however, showed no correlation with the number of receptor binding sites or the plasma levels of sex steroids. None of these assayed substances had a clear correlation with the histological type of tumor or the clinical stage of the disease.

[The clinical significance of hormone receptors in the treatment of breast cancer]

The assay of steroid receptors in tumor tissue has been shown to be a useful tool to evaluate the response of disseminated breast cancer to endocrine therapy. Principle and problems of this assay are outlined. An objective response of estrogen-receptor positive tumors to endocrine treatment can be achieved in about 60%. The rate of remissions in the receptor-negative group is below 10%. Possible explanations for false-positive or false-negative receptor assays are discussed. Additionally some possibilities for increasing the accuracy of the method are detailed.

A histochemical technique for evaluation of progesterone receptors in breast cancer

A histochemical method for the detection and localization of progesterone receptors in human breast cancer has been developed employing a fluorescein labeled conjugate of bovine serum albumin linked to a progestin as the binding hormone. Considerable tumor cell receptor heterogeneity was apparent and nuclear binding was frequently noted. The results of the new assay correlated with those obtained by dextran-coated charcoal assay in 91 per cent of specimens.

Steroid hormone receptors in human colon cancers

Tumors from patients with primary colon cancer were studied for the presence of steroid hormone receptors for estrogen (E2), progesterone (Prog), dihydrotestosterone (DHT) and glucocorticoid. Ten of 33 (30%) tumors contained high affinity E2 receptors. Four were males and six females with positive assays predominantly from the left colon. Twenty-three of these tumors were also assayed for DHT and Prog and six (26%) contained all three receptors. An additional twelve tumors had at least one receptor, so that 70% of the tumors studied contained one or more receptors. Five of 22 (23%) samples were positive for glucocorticoid receptors. Common etiological factors associated with colon and breast cancer were briefly discussed. These factors, along with the presence of hormone receptors in primary colon malignancies suggest that some large bowel cancers may be endocrine-dependent.

[Determination of cytoplasmic receptors for specific steroid hormones. III) Progestin receptor]

A method for determining cytoplasmic progesterone receptor was standardized in normal human endometrium comparing two different tracers, 3H-progesterone (3H-P) and 3H-medroxyprogesterone acetate (3H-MAP), a synthetic progestin which does not bind to Corticosteroid Binding Globulin (CBG). Receptor assays were performed as previously reported for 17beta-estradiol receptor, with slight modifications: incubation lasted 1 hr at 0 degree C, followed by 5 min DCC exposure under the same conditions. When 3H-P was employed as tracer, blanks performed with cold MAP gave similar results as using cortisol in incubation tubes and progesterone and cortisol in blanks. 3H-MAP was a good tracer for progesterone receptor because it neither bound to CBG nor to androgen or cortisol receptors; it had very high affinity and specificity for P-R; it was not metabolized by cytosol at 0 degree C and, finally, it detected receptor amounts quite comparable to those obtained using 3H-P.

Hormone serum levels and hormone receptor contents of endometria in women with normal menstrual cycles and patients bearing endometrial carcinoma

Serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin (HPRL), 17 beta-estradiol (E2) and progesterone (P) were estimated in 46 subjects with normal menstrual cycles in whom hysterectomies were performed. Estrogen (ER) and progesterone receptor (PgR) levels in endometrial samples of these patients were estimated, and histological dating of the cycle day was carried out. Similarly, hormone serum levels and ER as well as PgR were estimated in 17 patients with endometrial carcinoma. No correlation between LH, FSH, HPRL and ER as well as PgR was noted in the normal subjects. Correlation between P and ER was observed in this group. Parallel variations between E2 and PgR were recorded in the normal females. In the carcinoma group no correlations between hormone serum levels and receptor contents were found, but ER and PgR correlated with each other. Receptor levels was highest in the well-differentiated group of endometrial carcinoma. The present experiments provide a rationale for progestagen therapy of carcinoma of the endometrium.

Renal cancer steroid receptors: biochemical basis for endocrine therapy

Estradiol receptor (ER) and progesterone receptor (PR), found in experimental renal cancer as well as in normal human kidney and in human renal cell carcinoma (RCC), have been measured in 27 RCCs from patients submitted to surgery and endocrine therapy in an attempt to predict the response to progestational therapy. Of these 27 tumors 59% were positive for ER and 59% for PR; 37% were positive and 19% negative for both ER and PR. The follow-up of 23 patients showed that progestational therapy, started in 18 patients, has given favorable results in 14 patients and negative results in 3 patients with ER-PR- renal cancer. Antiestrogenic therapy, started soon after nephrectomy in 1 patient with ER+PR- renal cancer and lung metastases, failed since the patient died 8 months after surgery.

Steroid receptors in sarcomatous lesions

Clinical observations showed that the natural history of sarcomatous lesions may be different among males and females, and it may be influenced by hormonal factors. Estrogen receptors (ER) were measured on biopsy specimens of melanoma (two patients), soft-tissue sarcoma (four patients), cystosarcoma phylloides (five patients), benign breast tissues (27 patients), and breast carcinoma (109 patients). Thirty-four specimens also had progesterone receptors (PR) analyzed. One of the five cystosarcoma phylloides and five of the six nonmammary sarcoma tissues contained ER (mainly of the 4 Svedburg (S) variety) of more than 7 femtomoles (fmoles)/mg cytosol proteins (6/11 = 54%). For comparison three of the 14 fibroadenoma specimens and two of the 13 patients with other benign lesions had positive ERs (5/27 = 19%), whereas 56% of the breast carcinomas were ER positive. Since the amount of 8S ER found in sarcomatous tissues is relatively low, hormonal treatment would not be effective.

Androgen, estrogen and progesterone receptors of the R3327H Copenhagen rat prostatic tumor

Sucrose density gradient analysis of the R3327H tumor cytosol demonstrated the presence of both androgen and estrogen binding proteins. Competitive binding analysis with 17 beta-estradiol, 5 alpha-dihydrotestosterone, R1881, cyproterone acetate, and cortisol was consistent with the presence of 2 different binding sites for androgens and estrogens. Scatchard binding analysis was performed in the dorsal-lateral prostate as well as the R3327H tumor from normal Copenhagen rats. High affinity receptors for androgen and estrogen but not progesterone were found. However, in R3327H tumors relapsing following castration, the presence of high affinity receptors for progesterone were readily detectable.

Progesterone and oestrogen receptors in human breast cancer

Receptors for progesterone were found in 27% of 98 human breast tumours, and for oestrogen in 57% of 191 tumours. With one exception, progesterone receptors were found only in tumours which also contained oestrogen receptors. Levels of oestrogen receptor in positive tumours rose significantly with patient age whereas progesterone receptors were unchanged. Progesterone receptor levels were lower in lymph node metastases than in primary tumours, and oestrogen receptor levels were lower in large tumours (greater than 5 cm diameter) compared to small lesions. Receptor levels were not significantly correlated with circulating concentrations of either oestrogen or prolactin. The implications of receptor measurements in assessing hormone responsiveness of breast tumours are discussed.

[Response to an antiestrogen as a criterion for hormonal sensitivity of endometrial cancer]

A test is described for the evaluation of hormone sensitivity of endometrial cancer in vivo. The concentrations of progesterone and estradiol receptors, and the activities of ornithine-decarboxylase and 17 beta-hydroxysteroid oxido-reductase enzymes have been measured in the tumor, before and after administration of the anti-estrogen tamoxifen. The responses observed, in particular the increase of progesterone receptor, could allow a more rational approach to hormonal therapy of endometrial cancer.

Distribution of cytoplasmic estrogen and progesterone receptors in human endometrium

Unoccupied estrogen receptors and progesterone receptors were measured in the cytoplasm of five sections along the length of endometrium obtained from noncancerous, premenopausal hysterectomy specimens. The concentrations of the two receptors were measured with tritiated estradiol or R5020 (a synthetic progestin), the latter two having been purified by high-pressure liquid chromatography, and were found to be highest in the fundus and lowest in the cervix. Progesterone receptor levels, ranging from 50 to 3,500 fmoles of R5020 bound per milligram of protein, were generally much higher in each section of the endometrium than estrogen receptor levels, which ranged from 0 to 500 fmoles of estradiol bound per milligram of protein. Near ovulation it seemed that the distribution profiles of both receptors became very steep, with more than a tenfold difference in the receptor levels being found between the fundus and the cervix. Receptor levels measured in endometrial samples obtained by curettage or aspiration should be interpreted with caution.

Use of the vertical rotor to facilitate estrogen and progesterone receptor analysis

Sucrose density-gradient analysis is one method of identifying specific estrogen and progesterone receptors in mammary tumor tissue. Use of the vertical rotor makes this practical for routine applications in the clinical laboratory by increasing the number of samples that can be run at one time and shortening the centrifuge time from 18 to less than 2 h. The separations and reproducibility compare favorably with those obtained with a swinging-bucket rotor.

Steroid receptor analyses of nine human breast cancer cell lines

Nine human breast cancer cell lines in permanent tissue culture and currently available to researchers have been assayed for their content of cytoplasmic estrogen receptors, progesterone receptors, androgen receptors, and glucocorticoid receptors, as well as for the presence of unfilled or hormone-filled nuclear estrogen receptors. Receptor distribution varied considerably among the nine lines and differed from the expected distribution predicted from solid tumors. We find that estrogen receptor, when present, is usually localized in the nucleus as unfilled nuclear estrogen receptor. Progesterone receptor is correlated with presence of unfilled nuclear estrogen receptor. Glucocorticoid receptors are ubiquitous; they were found in all cell lines tested. The distribution of androgen receptor and progesterone receptor differed, suggesting that these proteins are dissimilar.

[The influence of endogenous hormones on the oestrogen and progesterone receptor determination in tissue of mammary carcinoma (author's transl)]

Oestrogen and progesterone receptors were determined in 48 primary tumors of invasive mammary carcinoma. 86% showed a positive oestrogen receptor binding, 53% were progesterone receptor positive. The binding capacity for oestradiol was 5-211 pmoles/g tissue protein, for progestin (R 5020) 7-146 pmoles. The question of the investigation was whether the content of determined receptors depends on endogenous oestradiol and progesterone concentrations. A clear dependence did not exist between the hormone level in the plasma, collected just before the excision of the tumor, and the amount of identifiable receptors in the tumor. On the contrary, in considering the quantities of endogenous hormones in the tissues, based on the plasma content of the tissue and the plasma hormone level, a correlation could be found. The content of identifiable receptors decreased with increasing amounts of endogenous hormones in the cytosol. It is postulated that rather the amount of endogenous hormones in the tissue than the plasma hormone level characterizes the degree of saturation of existing receptors by endogenous hormones. Apparently, the determined receptor concentrations at endogenous hormone values under 2 pmoles/g tissue protein reflect rather the true receptor content, whereas at higher values too low or false negative results should be reckoned with.

Hormone receptors and breast cancer

The hormones of reproduction have been implicated in breast cancers of women. A short reproductive life, and a pregnancy prior to the age of 30 years, both reduce the risk of breast cancer (Doll, 1975). In addition, removal of endogenous sources of oestrogens, and administration of anti-oestrogens, cause some breast cancers to regress (Stoll, 1969). Such observations have led to an investigation of the role of the hormones of reproduction, and of oestrogen in particular, in the maintenance of breast cancers.

Hormones in breast cancer: update 1978

The role of cytoplasmic estrogen receptor (ER) assays in determining therapeutic strategies for advanced breast cancer is certainly well established. The use of ER assays in the primary breast tumor specimen to predict for early recurrence and ultimate survival is a new finding, however, and will probably be employed in future trials of adjuvant therapy. The prevalence and significance of nuclear-bound ER still requires additional clarification. Our previous suggestion that progesterone receptor measurements might be a useful marker for hormone dependence in advanced breast cancer is gaining support and may soon have a place in routine therapeutic decision-making. The emphasis on early adjuvant therapy has hastened the search for a safe endocrine therapy that would have good patient compliance and achieve remission rates comparable to previous agents and procedures. Antiestrogens show promise of meeting these requirements. We are now beginning an era in which primary and secondary systemic therapies for breast cancer can be based on sound biologic principles. The empirical approach is outdated.

Characterization and assay of the progesterone receptor in rat uterine cytosol

The synthetic progestogen R5020 (17,21-dimethyl-19-norpregna-4,9-diene-3,20-dione) binds with high affinity (Ka = 8.8 X 10(8) l/mol at 0 degree C) to the progesterone receptor from rat uterine cytosol. At nanomolar concentrations, equilibrium is attained in less than 90 min. R5020 has a very low affinity for other specific steroid-binding proteins (corticosteroid-binding globulin and oestrogen receptors) present in relatively high concentrations in the urine cytosol. The affinity of the receptor for the natural hormone progesterone is remarkably low (Ka = 1 X 10(8)-1.7 X 10(8) l/mol at 0 degree C) which explains the instability of progesterone-receptor complexes. Advantage may be taken of this property to remove endogenous progesterone easily by charcoal treatment at 0 degree C, a treatment which does not modify the concentration of receptors. A method based on these characteristics is described for the assay of the total number (progesteron-bound and unbound) of receptor sites in uterine cytosol. This assay may be used in various physiological situations where endogenous progesterone is present at unknown concentrations.

Progesterone receptors in the rat uterus: variations in cytosol and nuclei during the oestrous cycle and pregnancy

The concentration of progesterone receptors in rat uterine cytosol and nuclei was measured during the oestrous cycle and pregnancy. The method used allowed the measurement of the total concentration of binding sites (unbound and hormone-bound). During the oestrous cycle, the concentration of receptors in the cytosol peaked at prooestrus, low concentrations were observed at oestrus and metoestrus, and in increase was seen at dioestrus. In the nuclei, maximum concentrations occurred at pro-oestrus and dioestrus. The number of receptors in the cytosol was very low during the first half of pregnancy, but the concentration increased progressively after day 15 to attain a very high level (about 26 000 binding sites/cell) on day 22. In the nuclei, the concentration of receptors was low at the beginning of pregnancy. On day 5 (day of implantation) there was a slight increase, which corresponded to a decrease in the number of cytosolic receptors and a small peak in the level of progesterone in the plasma. Maximum concentrations were attained during a 'plateau' period between days 9 and 15. Thereafter, there was very low; in some animals, probably on the verge of parturition, no receptors were detectable in the nuclei.