A physiological role for estrogen and progesterone in breast cancer

Expression of Estrogen and Progesterone Receptors in Papillary Thyroid Carcinoma in Korea

Purpose

The aim of this study was to examine the rate of expression of estrogen receptor α (ERα) and β1 (ERβ1), progesterone receptor (PR), and rate of overexpression of epidermal growth factor receptor (EGFR) in a relatively large cohort of patients with papillary thyroid carcinoma (PTC). We also aimed to examine whether each receptor influenced clinicopathological characteristics and prognosis of PTC.

Materials and Methods

We made a microarray of paraffin-embedded PTC surgical tissues from 436 patients. We compared the results of the immunohistochemical staining for each hormone receptor with clinicopathological characteristics.

Results

The positive expression rate of hormonal receptors was 40.4% for ERα, 83.7% for ERβ1, and 71.3% for PR in patients with PTC. Overexpression of EGFR was shown in 19.3% of patients with PTC. The age was lower (44.6±12.1 years vs. 47.1±12.5 years, p=0.040) and tumor smaller (0.96±0.69 cm vs. 1.13±0.82 cm, p=0.020) in the ERα positive group, which also showed higher PR positivity (80.7% vs. 65.0%, p < 0.001) and overexpression of EGFR (27.3% vs. 13.8%, p < 0.001). However, neither the positivity of hormone receptors nor overexpression of EGFR affected the recurrence of PTC.

Conclusion

In conclusion, most (94.6%) patients with PTC were found to exhibit positive expression for ERs or PR. We also found that neither the positive expression of hormone receptors nor overexpression of EGFR were associated with the recurrence of PTC.

Design, synthesis, and biological activity of a novel series of benzofuran derivatives against oestrogen receptor-dependent breast cancer cell lines

A docking study of a novel series of benzofuran derivatives with ERα was conducted. In this study, we report the synthesis of a novel series of benzofuran derivatives and evaluation of their anticancer activity in vitro against MCF-7 human breast cancer cells, as well as their potential toxicity to ER-independent MDA-MB-231 breast cancer cells, human renal epithelial HEK-293 cells, and human immortal keratinocytes (HaCaT cells) by using the MTT colorimetric assay. The screening results indicated that the target compounds exhibited anti-breast cancer activity. The target compound 2-benzoyl-3-methyl-6-[2-(morpholin-4-yl)ethoxy]benzofuran hydrochloride (4e) exhibited excellent activity against anti-oestrogen receptor-dependent breast cancer cells and low toxicity. The preliminary structure-activity relationships of the target benzofuran derivatives have been summarised. In conclusion, the novel benzofuran scaffold may be a promising lead for the development of potential oestrogen receptor inhibitors.

Higher tumor mass and lower adipose mass are associated with colon‑26 adenocarcinoma‑induced cachexia in male, female and ovariectomized mice

Cachexia is responsible for nearly 20% of all cancer‑related deaths, yet effective therapies to prevent or treat the disease are lacking. Clinical studies have shown that male patients lose weight at a faster rate than females. Additionally, an 'obesity paradox' may exist where excess adiposity may confer survival to patients with cancer cachexia. To further explore these phenomena, the aim of this study was to evaluate the role of changes of adipose tissue mass, sex status, and tumor mass on outcomes of male, female and ovariectomized (OVX) mice with C‑26 adenocarcinoma‑induced cachexia. We used EchoMRI to assess body composition and grip strength to measure muscle function. Body weights and food intake were measured daily. Mice were euthanized 19 days post‑-inoculation. Post‑necropsy, muscle fiber cross‑sectional areas were quantified and real‑time PCR was performed for genes relating to proteolysis. Survival curve, correlation and multiple linear regression analyses were performed to identify predictors of cachexia. Female and OVX tumor mice developed cachexia similarly to males, as evidenced by loss of skeletal and adipose masses, decreased grip strength, and increased proteolytic gene expression. Notably, female and OVX tumor mice had earlier onset of cachexia (≥5% weight loss) than male tumor mice. Larger tumor mass and lower adipose mass were the strongest predicting factors for increased severity of cachexia, regardless of sex or ovariectomy status. These results indicated that the impact of sex status may be subtle in comparison to the predictive effect of tumor and adipose mass in mice with C‑26‑induced cachexia.

Expression of human aromatase (CYP19) in Escherichia coli by N-terminal replacement and induction of cold stress response

CYP19 (P450arom) catalyzes the aromatization reaction of C19 steroids leading to estrogens. While readily expressed in insect cells, the human P450arom has been a difficult P450 to express in Escherichia coli at useful levels. In the present study, we replaced the N-terminal sequence in human CYP19 with the corresponding sequences of other microsomal P450s (CYP2C11 and CYP17) that are efficiently expressed in E. coli. Although the N-terminal replacement alone was not sufficient for the expression, human P450arom was successfully expressed up to the level of 240nmol/l culture by the combination of the N-terminal replacement and the induction of cold stress response by 1 microg/ml chloramphenicol. Membrane fractions containing the expressed P450arom catalyzed aromatization of androstenedione with a specific activity of 4.9 nmol/min/nmol P450. Our results are important to provide large quantities of human P450arom as an active form for structure-function studies.

Biological effects and morphological responses to estriol, estriol-3-sulfate, estriol-17-sulfate and tamoxifen in a tamoxifen-resistant cell line (R-27) derived from MCF-7 human breast cancer cells

The R-27 cell line is a variant clone derived from the MCF-7 human breast cancer cell line which has lost its inhibitory response to anti-estrogens. In the present study, we have compared the biological responses to estriol (E3), estriol-3-sulfate (E3-3-S), and estriol-17-sulfate (E3-17-S) in these cells and in the parent MCF-7 cells. In the R-27 cell line after 7 days of culture, the progesterone receptor (PR) concentrations were greatly increased by E3 and E3-3-sulfate; however, tamoxifen did not block this effect. The effect in PR provoked by E3-17-S was significantly less intense. The concentrations of PR (pmol/mg DNA +/- S.D.) in the R-27 cells were as follows: control: 1.1 +/- 0.8; +E3: 10.5 +/- 2.4; +E3-3-S: 5.4 +/- 2.3; +E3-17-S: 2.6 +/- 0.8. E3 and E3-3-S also stimulated PR in the MCF-7 cells but to a lesser extent. No stimulation was observed in the E3-17-S treatment. A fraction (0.5-1%) of the E3-3-S was found to be hydrolysed in the medium during the incubation in both cell lines, but no hydrolysis occurred after incubation with E3-17-S. Ultrastructural observations showed that in the E3 and E3-3-S treated cells, there was an important development of the ergastoplasm, bundles of filaments and an accumulation of ribosomes. No significant morphological alteration was observed in cells exposed to E3-17-S. In conclusion, E3 is biologically very active in both the R-27 and the MCF-7 cell lines and E3-3-S could play a role in the control of the estrogenic activity of E3.

Secretory component in breast cancer. Analysis of the levels in primary and metastatic disease

Levels of secretory component (SC) were measured in breast tumors from 95 patients with primary or metastatic cancer. Tumor cytosols were prepared by polytron disruption and high speed centrifugation (105,000 g X 30 min) and SC was measured using a sensitive radioimmunoassay which detects primarily free SC. In frozen samples stored for up to 5 months SC resisted degradation and could be measured quantitatively without interference. In primary tumors from patients between ages 28 and 97, SC positive samples ranged from 4 ng/mg protein to 600 ng/mg protein. In metastatic lesions, SC positive samples ranged no higher than 46 ng/mg protein. The studies indicate that SC can be measured quantitatively in both primary and metastatic tumors and that prolonged storage does not interfere with measurements of SC. The wide variation in SC levels in primary tumor samples may be related to a susceptibility to metastasis. Further, the low levels of SC in metastatic lesions could indicate a potential for SC involvement in immune regulation of tumor growth.

A simple method to determine whole cell uptake of radiolabelled oestrogen and progesterone and their subcellular localization in breast cancer cell lines in monolayer culture

Specific uptake of tritiated 17 beta-oestradiol and R5020, a synthetic progestin, in breast cancer cell lines ( MCF7 and T47D) growing in monolayer culture in multiwell plates has been shown. Binding characteristics, calculated by Scatchard analysis, indicate the presence of steroid receptors of similar affinities and capacities to those already obtained with broken cell preparations. Lysis of the cells by treatment with a hypotonic buffer reveals the subcellular localization of the receptors so the method can be used to study receptor dynamics such as nuclear translocation and processing. Cell growth can be measured by DNA determination directly in the multiwell plates. Thus, the method provides a convenient way of studying the effects of steroid hormones (or any antihormone or chemotherapeutic agent) on growth and receptor content of breast cancer cells in monolayer culture.

Estrogen and progesterone receptors in mammary tumors induced in rats by simultaneous administration of 17 beta-estradiol and progesterone

Mammary tumors were promoted in male rats of the Wistar WAG strain by continuous and simultaneous administration of 17 beta-estradiol and progesterone. Tumor induction and growth were dependent on estradiol and on progesterone. Their histological features were comparable with those of human breast cancers. Hormone receptors were present in tumor cells. Estradiol receptor was found in 95% of them, at a higher level in nuclei than in cytosol. Progesterone receptor was present in 75% of tumors. In all cases, the level of androgen receptor was low.

Association of plasminogen activator activity and steroid receptors in human breast cancer

Plasminogen activating activity (PAA) has been determined in 105 human breast cancer cytosols with a colorimetric assay. PAA has been related to steroid receptors in the same cytosols. A strong positive correlation between PAA and progesterone receptor levels was found (Spearmans coefficient of rank correlation, R - 0.74, P less than 0.001). PAA discriminates between progesterone receptor-positive and -negative tumours, irrespective of oestradiol receptor content. It is suggested that PAA is a marker of functional oestradiol receptor and that fibrinolytic activity may be a causative factor in the low metastatic potential of progesterone receptor-positive tumours.

Growth regulation of two rat adenocarcinoma cell lines by dexamethasone and progesterone

We have studied the effect of steroids on cell proliferation in two continuous cell lines derived from rat mammary tumors induced by 7, 12-dimethyl-benz (a) anthracene (DMBA) and N-nitrosomethylurea (NMU). These cell lines contain high concentrations of glucocorticoid and androgen receptors but no estrogen and progesterone receptors as previously shown (1). The cell proliferation was evaluated by measuring [3H] thymidine incorporation into DNA, cell number, and DNA content. Dexamethasone was found to markedly stimulate cell proliferation in a dose-dependent manner, suggesting that it was acting via the glucocorticoid receptor. The effect of 5 alpha-dihydrotestosterone (DHT) was weaker since a stimulation of [3H] thymidine incorporation was contrasted by the absence of a constant increase of cell proliferation. Progesterone partially stimulated NMU cell growth and totally inhibited the stimulatory effect of dexamethasone in both cell lines. The synthetic progestin R5020 displayed a similar activity to that of progesterone. These results show that progestins can directly modulate the growth of mammary cancer cells even in the absence of progesterone receptor by interacting on the glucocorticoid receptor. We conclude that progestins act mostly as partial agonist-antagonists of glucocorticoids in these two rat mammary adenocarcinoma cell lines.

Multiple steroid receptors in human breast cancer. III. Relationships between steroid receptors and the state of differentiation and the activity of carcinomas throughout the pathologic features

Histopathologic features (tumor cell density, histological type, and histoprognostic grade) were analyzed in 314 breast cancers investigated for estrogen (E) and progestin (P) receptors (R). The presence of PR is associated with the presence of ER. A relationship was found between the acinoductal differentiation of the lesions and the presence of SR: the more differentiated the carcinoma, the higher the frequency of ER. HPG III carcinomas have the lowest frequency of positive ER and HPG I tumors the opposite: the likelihood of the presence of SRs is inversely correlated with HPG. No statistically significant relationship existed between tumor cell density (TCD) and the presence of ER or ER content. Similar findings were observed for the stromal reaction. The results are discussed with respect to the biological significance of SR and histopathologic features: SR presence could be correlated with (1) a differentiated state of the tumors and (2) a slow rate of cellular replication.