New perspectives into the biological and clinical relevance of oestrogen receptors in the human breast

Immunohistochemical expression of ER-α and PR in papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is the most common thyroid cancer with multiple risk factors including exposure to ionising radiation. Oestrogens contribute to papillary carcinoma development by promoting cell proliferation and invasion of mutated epithelial follicular cells. The present study aimed to assess ER-α and PR expression in PTC and to correlate their expression with the clinicopathological parameters in this cancer. This study included 62 primary and six metastatic papillary thyroid carcinoma cases. Nineteen and 38.7% of primary PTC cases showed positive nuclear expression for ER and PR, respectively. Metastatic cases showed 66.7% positive ER expression and all were negative for PR. Oestrogen receptor expression showed significant higher positivity in metastatic compared to primary PTC (p = 0.02) and it was significantly associated with primary PTC associated with thyroiditis (p = .002). Progesterone receptor expression was significantly associated with old age in primary PTC (p = .003) and it showed significant coparallel expression with ER (p = .000). Oestrogen and progesterone receptors expressed in papillary thyroid carcinoma opening the door for further studies to verify if those patients could benefit from hormonal therapy. Oestrogen receptor seems to have a role in metastatic process of PTC as malignant cells express it in metastatic more than primary site. The presence of lymphocytes in the stroma may promote ER expression in adjacent PTC, necessitating further studies on PTC cases associated with Hashimoto thyroiditis to verify this assumed relationship.

Training Nuclei Detection Algorithms with Simple Annotations

BACKGROUND

Generating good training datasets is essential for machine learning-based nuclei detection methods. However, creating exhaustive nuclei contour annotations, to derive optimal training data from, is often infeasible.

METHODS

We compared different approaches for training nuclei detection methods solely based on nucleus center markers. Such markers contain less accurate information, especially with regard to nuclear boundaries, but can be produced much easier and in greater quantities. The approaches use different automated sample extraction methods to derive image positions and class labels from nucleus center markers. In addition, the approaches use different automated sample selection methods to improve the detection quality of the classification algorithm and reduce the run time of the training process. We evaluated the approaches based on a previously published generic nuclei detection algorithm and a set of Ki-67-stained breast cancer images.

RESULTS

A Voronoi tessellation-based sample extraction method produced the best performing training sets. However, subsampling of the extracted training samples was crucial. Even simple class balancing improved the detection quality considerably. The incorporation of active learning led to a further increase in detection quality.

CONCLUSIONS

With appropriate sample extraction and selection methods, nuclei detection algorithms trained on the basis of simple center marker annotations can produce comparable quality to algorithms trained on conventionally created training sets.

Estradiol-independent modulation of breast cancer transcript profile by 17beta-hydroxysteroid dehydrogenase type 1

17beta-hydroxysteroid dehydrogenase type 1 (17β-HSD1) is a steroidal enzyme which, in breast cancer cells, mainly synthesizes 17-beta-estradiol (E2), an estrogenic hormone that stimulates breast cancer cell growth. We previously showed that the enzyme increased breast cancer cell proliferation via a dual effect on E2 and 5α-dihydrotestosterone (DHT) levels and impacted gene expression and protein profile of breast cancer cells cultured in E2-contained medium. Here, we used RNA interference technique combined with microarray analyses to investigate the effect of 17β-HSD1 expression on breast cancer cell transcript profile in steroid-deprived condition. Our data revealed that knockdown of 17β-HSD1 gene, HSD17B1, modulates the transcript profile of the hormone-dependent breast cancer cell line T47D, with 105 genes regulated 1.5 fold or higher (p < 0.05) in estradiol-independent manner. Using Ingenuity Pathway Analysis (IPA), we additionally assessed functional enrichment analyses, including biological functions and canonical pathways, and found that, in concordance with the role of 17β-HSD1 in cancer cell growth, most regulated genes are cancer-related genes. Genes that primarily involved in the cell cycle progression, such as the cyclin A2 gene, CCNA2, are generally down-regulated whereas genes involved in apoptosis and cell death, including the pro-apoptotic gene XAF1, IFIH1 and FGF12, are on the contrary up-regulated by 17β-HSD1 knockdown, and 21% of the modulated genes belong to this latter functional category. This indicates that 17β-HSD1 may be involved in oncogenesis by favoring anti-apoptosis pathway in breast cancer cells and correborates with its previously shown role in increasing breast cancer cell proliferation. The gene regulation occurring in steroid-deprived conditions showed that 17β-HSD1 can modulate endogenous gene expression in steroid-independent manners. Besides, we tested the ability of estrogen to induce or repress endogenous genes of T47D by microarray analysis. Expression of a total of 130 genes were found to increase or decrease 1.5-fold or higher (p < 0.05) in response to E2 treatment (1 nM for 48 h), revealing a list of potential new estrogen-responsive genes and providing useful information for further studies of estrogen-dependent breast cancer mechanisms. In conclusion, in breast cancer cells, in addition to its implication in the E2-dependent gene transcription, the present study demonstrates that 17β-HSD1 also modulates gene expression via mechanisms independent of steroid actions. Those mechanisms that may include the ligand-independent gene transcription of estrogen receptor alpha (ERα), whose expression is positively correlated with that of the enzyme, and that may implicate 17β-HSD1 in anti-apoptosis pathways, have been discussed.

Prevention of hormonal breast cancer by dietary jamun

SCOPE

Syzygium cumini (jamun) is perhaps the only berry that has the diversity of anthocyanidins of blueberry and bilberry and the abundance of ellagitannins/ellagic acid of black raspberry. Here, we report the potential of jamun against 17β-estrogen-mediated breast cancer and the role of miRNAs and other targets in disease inhibition.

METHODS AND RESULTS

Female August-Copenhagen Irish rats were given AIN-93M diet or diet supplemented with jamun. Two weeks later, animals received 17β-estradiol and were palpated weekly for the mammary tumors. At the end of 26 weeks, the jamun-diet significantly delayed the first tumor appearance by 21 days, and reduced the tumor incidence (65% versus 96%), tumor burden (313 ± 95 versus 661 ± 123 mm(3) ) and tumor multiplicity (1.8 ± 0.3 versus 4.2 ± 0.4 tumors/rat) compared to control. The experimental diet significantly reduced the estrogen-associated growth of pituitary prolactinomas, circulating prolactin and estradiol levels and offset estrogen-associated increases in mammary cell-proliferation, estrogen receptor-alpha (ER-α), and cyclinD1. miRNAs that were either overexpressed (miR-182 and miR-375) or underexpressed (miR-127 and miR-206) following estrogen-treatment were significantly protected by jamun diet.

CONCLUSIONS

Together, our data show that jamun significantly offset estrogen-mediated alterations in mammary cell-proliferation, ER-α, cyclinD1, and candidate miRNAs, and that the modulation of these biomarkers correlated with a reduction in mammary carcinogenicity.

The Role of Forkhead Box Protein M1 in Breast Cancer Progression and Resistance to Therapy

The Forkhead box M1 (FOXM1) is a transcription factor that has been implicated in normal cell growth and proliferation through control of cell cycle transition and mitotic spindle. It is implicated in carcinogenesis of various malignancies where it is activated by either amplification, increased stability, enhanced transcription, dysfunction of regulatory pathways, or activation of PI3K/AKT, epidermal growth factor receptor, Raf/MEK/MAPK, and Hedgehog pathways. This review describes the role of FOXM1 in breast cancer. This includes how FOXM1 impacts on different subtypes of breast cancer, that is, luminal/estrogen receptor positive (ER+), expressing human epidermal growth factor receptor 2 (HER2), basal-like breast cancer (BBC), and triple negative breast cancer (TNBC). The review also describes different tested preclinical therapeutic strategies targeting FOXM1. Developing clinically applicable therapies that specifically inhibit FOXM1 activity is a logical next step in biomarker-driven approaches against breast cancer but will not be without its challenges due to the unique properties of this transcription factor.

Prognostic and predictive value of ERβ1 and ERβ2 in the Intergroup Exemestane Study (IES)-first results from PathIES†

BACKGROUND

Intergroup Exemestane Study (IES) was a randomised study that showed a survival benefit of switching adjuvant endocrine therapy after 2-3 years from tamoxifen to exemestane. PathIES aimed to assess the potential prognostic and predictive value of ERβ1 and ERβ2 expression in primary tumours in order to determine benefit in the two treatment arms.

PATIENTS AND METHODS

Primary tumour samples were available for 1256 patients (27% IES population). ERβ1 and ERβ2 expression was dichotomised at the median IHC score (high if ERβ1 ≥ 191, ERβ2 ≥ 164). Hazard ratios (HRs) were estimated by multivariable Cox proportional hazards models adjusting for clinicopathological factors. Treatment effects with biomarker expressions were determined by interaction tests. Analysis explored effects of markers both as a continuous variable and with dichotomised cut-offs.

RESULTS

Neither ERβ1 nor ERβ2 were associated with disease-free survival (DFS) or overall survival (OS) in the whole cohort. In patients treated with continued tamoxifen, high ERβ1 expression compared with low was associated with better DFS [HR = 0.38:95% confidence interval (CI) 0.21-0.68, P = 0.001]. DFS benefit of exemestane over tamoxifen (HR = 0.40:95% CI 0.22-0.70) was found in the low ERβ1 subgroup (interaction P = 0.01). No significant difference with treatment was observed for ERβ2 expression in either DFS or OS.

CONCLUSION

In the PathIES population, exemestane appeared to be superior to tamoxifen among patients with low ERβ1 expression but not in those with high ERβ1 expression. This is the first trial of its kind to report a parameter potentially predicting benefit of an aromatase inhibitor when compared with tamoxifen and an independent validation is warranted.

Isoflavone intake inhibits the development of 7,12-dimethylbenz(a)anthracene(DMBA)-induced mammary tumors in normal and ovariectomized rats

To determine the associations between isoflavone (49.72% genistin, 5.32% daidzin, 34.54% glycitin) and breast cancer risk, 150 rats were given 5 mg 7,12-dimethylbenz(a)anthracene and half of them were ovariectomized. Then normal rats and ovariectomized rats were divided into 5 groups: control group, isoflavone high (HI), middle (MI), or low (LI) dose group consuming 100, 500, or 1000 mg isoflavones/kg diet, estrogen group (2.5 mg stilboestrol/kg diet). After 24 weeks, tumor incidences were 73% in control group, 7% in HI, 7% in MI, 27% in LI, and 80% in estrogen group for normal rats; 60% in control group, 13% in HI, 7% in MI, 13% in LI, and 73% in estrogen group for ovariectomized rats. Isoflavone treatment decreased tumor incidence and mean tumor number per rat and increased mean latent period compared with those in control group and estrogen group group significantly (p<0.05). The mRNA and protein expression of estrogen receptor β were significantly higher in isoflavone treatment groups than those in control group group. Moreover, isoflavone treatment significantly decreased 8-hydroxydeoxyguanosine content and increased superoxide dismutase level in normal rats and decreased malondialdehyde concentrations in ovariectomized rats compared with control group. In conclusions, isoflavone intake significantly inhibited the development of premenopausal and postmenopausal mammary tumors.

Glyphosate induces human breast cancer cells growth via estrogen receptors

Glyphosate is an active ingredient of the most widely used herbicide and it is believed to be less toxic than other pesticides. However, several recent studies showed its potential adverse health effects to humans as it may be an endocrine disruptor. This study focuses on the effects of pure glyphosate on estrogen receptors (ERs) mediated transcriptional activity and their expressions. Glyphosate exerted proliferative effects only in human hormone-dependent breast cancer, T47D cells, but not in hormone-independent breast cancer, MDA-MB231 cells, at 10⁻¹² to 10⁻⁶M in estrogen withdrawal condition. The proliferative concentrations of glyphosate that induced the activation of estrogen response element (ERE) transcription activity were 5-13 fold of control in T47D-KBluc cells and this activation was inhibited by an estrogen antagonist, ICI 182780, indicating that the estrogenic activity of glyphosate was mediated via ERs. Furthermore, glyphosate also altered both ERα and β expression. These results indicated that low and environmentally relevant concentrations of glyphosate possessed estrogenic activity. Glyphosate-based herbicides are widely used for soybean cultivation, and our results also found that there was an additive estrogenic effect between glyphosate and genistein, a phytoestrogen in soybeans. However, these additive effects of glyphosate contamination in soybeans need further animal study.

PKCα and ERβ Are Associated with Triple-Negative Breast Cancers in African American and Caucasian Patients

Although the incidence of breast cancer in the United States is higher in Caucasian women compared with African American women, African-American patients have more aggressive disease as characterized by a higher percentage of triple-negative breast cancers (TNBCs), high-grade tumors, and a higher mortality rate. PKCα is a biomarker associated with endocrine resistance and poor prognosis and ERβ is emerging as a protective biomarker. Immunohistochemical analysis of ERβ and PKCα expression was performed on 198 formalin-fixed paraffin-embedded primary infiltrating ductal carcinomas from 105 African-American and 93 Caucasian patients. PKCα is positively correlated with TNBC in patients of both races and with high tumor grade in African-American patients. Patients with TNBC express less nuclear ERβ compared with all other subtypes. We find no difference in frequency or intensity of PKCα or ERβ expression between African-American and Caucasian patients. PKCα and ERβ are discussed as potential therapeutic targets for the treatment of patients with TNBC.

The Possible Impact of Obesity on Androgen, Progesterone and Estrogen Receptors (ERα and ERβ) Gene Expression in Breast Cancer Patients

BACKGROUND

Obesity has been associated with increased mortality from hormone dependant cancers such as breast cancer which is the most prevalent cancer in women. The link between obesity and breast cancer can be attributed to excess estrogen produced through aromatization in adipose tissue. The role of steroid hormone receptors in breast cancer development is well studied but how obesity can affect the expression pattern of steroid hormones in patients with different grades of breast cancer was the aim of this study.

METHODS

In this case-control study, 70 women with breast cancer participated with different grades of obesity (36 none obese, BMI < 25 kg/m(2) and 34 obese, BMI ≥ 25 kg/m(2)). The mean age of participants was 44.53 ± 1.79 yr (21-70 yr). The serum level of estrogen, progesterone and androgen determined by ELISA. Following quantitative expression of steroid hormone receptors mRNA in tumor tissues evaluated by Real-time PCR. Patients with previous history of radiotherapy or chemotherapy were excluded. SPSS 16 was used for data analysis and P < 0.05 considered statistically significant.

RESULTS

The difference in ERα, ERβ and PR mRNA level between normal and obese patients was significant (P < 0.001). In addition, the expression of AR mRNA was found to be higher than other steroid receptors. There was no significant relation between ERβ gene expression in two groups (P = 0.68). We observed a significant relationship between ERα and AR mRNA with tumor stage and tumor grade, respectively (P = 0.023, P = 0.015).

CONCLUSION

According to the obtained results, it is speculated that obesity could paly a significant role in estrogen receptors gene expression and also could affect progression and proliferation of breast cancer cells.

Overexpression of estrogen receptor-α in human papillary thyroid carcinomas studied by laser- capture microdissection and molecular biology

The expression pattern of estrogen receptor (ER) isoforms in normal and tumor thyroid tissues is still controversial and poor defined, therefore, a more detailed study of the distribution of these molecules is needed. Most discrepancies might be due to the methods utilized. We studied the expression of ER isoforms in human papillary thyroid carcinoma (PTC), in fine-needle aspiration biopsy-derived specimens, and in cells, using more accurate techniques, such as laser-capture microdissection, real-time quantitative PCR, and Western blot. Laser-capture microdissection allowed us to isolate homogeneous cell populations from human PTC surgical samples. Tumor, peritumor, or normal host tissue of the same sample were separately dissected and analyzed by RT-PCR and Western blot. Estrogen receptor-α mRNA was more expressed in cancer-microdissected cells from human PTC, as compared with microdissected cells obtained from surrounding normal host tissue (450 vs 12, P = 0.001). A similar pattern was observed with Western blot for the ER-a protein. By contrast, ER-β mRNA expression was not detected among the microdissected tissue fractions. Fine-needle aspiration biopsy-derived specimens showed a similar expression pattern to ER. Moreover, human PTC cell line BCPAP and cancer stem cells from PTC, analyzed under hypoxic conditions, showed a hypoxia-driven increase in ER-α expression. In conclusion, ER-α might have an important role in human PTC, and its overexpression can be studied in routine needle aspirate as a possible marker of malignancy.

ERβ1 represses FOXM1 expression through targeting ERα to control cell proliferation in breast cancer

In this study, we investigated the effects of ectopic estrogen receptor (ER)β1 expression in breast cancer cell lines and nude mice xenografts and observed that ERβ1 expression suppresses tumor growth and represses FOXM1 mRNA and protein expression in ERα-positive but not ERα-negative breast cancer cells. Furthermore, a significant inverse correlation exists between ERβ1 and FOXM1 expression at both protein and mRNA transcript levels in ERα-positive breast cancer patient samples. Ectopic ERβ1 expression resulted in decreased FOXM1 protein and mRNA expression only in ERα-positive but not ERα-negative breast carcinoma cell lines, suggesting that ERβ1 represses ERα-dependent FOXM1 transcription. Reporter gene assays showed that ERβ1 represses FOXM1 transcription through an estrogen-response element located within the proximal promoter region that is also targeted by ERα. The direct binding of ERβ1 to the FOXM1 promoter was confirmed by chromatin immunoprecipitation analysis, which also showed that ectopic expression of ERβ1 displaces ERα from the endogenous FOXM1 promoter. Forced expression of ERβ1 promoted growth suppression in MCF-7 cells, but the anti-proliferative effects of ERβ1 could be overridden by overexpression of FOXM1, indicating that FOXM1 is an important downstream target of ERβ1 signaling. Together, these findings define a key anti-proliferative role for ERβ1 in breast cancer development through negatively regulating FOXM1 expression.

Characterization of BCAR4, a novel oncogene causing endocrine resistance in human breast cancer cells

Resistance to the antiestrogen tamoxifen remains a major problem in the management of estrogen receptor-positive breast cancer. Knowledge on the resistance mechanisms is needed to develop more effective therapies. Breast cancer antiestrogen resistance 4 (BCAR4) was identified in a functional screen for genes involved in tamoxifen resistance. BCAR4 is expressed in 27% of primary breast tumors. In patients treated with tamoxifen for metastized disease high BCAR4 mRNA levels are associated with reduced clinical benefit and progression-free survival. Regarding tumor aggressiveness high BCAR4 mRNA levels are associated with a shorter metastasis free survival and overall survival. In the present study, we investigated the role of BCAR4 in endocrine resistance. Forced expression of BCAR4 in human ZR-75-1 and MCF7 breast cancer cells resulted in cell proliferation in the absence of estrogen and in the presence of various antiestrogens. Inhibition of estrogen receptor 1 (ESR1) expression with small interfering RNA (siRNA), implied that the BCAR4-induced mechanism of resistance is independent of ESR1. Highly conserved BCAR4 homologues of rhesus monkey, green monkey, and the less conserved common marmoset gene induced tamoxifen-resistant cell proliferation, in contrast to the distant BCAR4 homologues of bovine and rabbit. Injection of BCAR4-expressing ZR-75-1 cells into nude mice resulted in rapidly growing tumors. In silico analysis showed that BCAR4 mRNA is highly expressed in human placenta and oocyte, and absent in other normal tissues. In conclusion, BCAR4 is a strong transforming gene causing estrogen-independent growth and antiestrogen resistance, and induces tumor formation in vivo. Due to its restricted expression, BCAR4 may be a good target for treating antiestrogen-resistant breast cancer.

Estrogenic effect of the MEK1 inhibitor PD98059 on endogenous estrogen receptor alpha and beta

Estrogens are key regulators in mammary development and breast cancer and their effects are mediated by estrogen receptors alpha (ERα) and beta (ERβ). These two receptors are ligand activated transcription factors that bind to regulatory regions in the DNA known as estrogen responsive elements (EREs). ERα and ERβ activation is subject to modulation by phosphorylation and p42/p44 MAP kinases are the best characterized ER modifying kinases. Using a reporter gene (3X-ERE-TATA-luciferase) to measure activation of endogenous ERs, we found that MEK1 inhibitor PD98059, used in concentrations insufficient to inhibit MEK1 activation of p42/p44 MAP kinases, exerted estrogenic effects on the reporter gene and on the ERE-regulated RIP 140 protein. Such estrogenic effects were observed in mammary epithelial HC11 cells and occur on unliganded ERα and ligand activated ERβ. Additionally, concentrations of PD98059 able to inhibit p42/p44 phosphorylation were not estrogenic. Further, inhibition of p42 MAP kinase expression with siRNAs also resulted in loss of PD98059 estrogenic effect. In summary, PD98059 in concentrations below the inhibitory for MEK1, exerts estrogenic effects in HC11 mammary epithelial cells.

Is soy consumption good or bad for the breast?

Genistein in soy activates estrogen receptor (ER)-α and ERβ and acts as an estradiol in multiple target tissues. Because estrogens increase breast cancer risk and genistein promotes the growth of ER-positive human breast cancer cells, it has remained unclear whether this isoflavone or soy is safe. Results reviewed here suggest that women consuming moderate amounts of soy throughout their life have lower breast cancer risk than women who do not consume soy; however, this protective effect may originate from soy intake early in life. We also review the literature regarding potential risks genistein poses for breast cancer survivors. Findings obtained in 2 recent human studies show that a moderate consumption of diet containing this isoflavone does not increase the risk of breast cancer recurrence in Western women, and Asian breast cancer survivors exhibit better prognosis if they continue consuming a soy diet. The mechanisms explaining the breast cancer risk-reducing effect of early soy intake or the protective effect in Asian breast cancer survivors remain to be established. We propose that the reduction in risk involves epigenetic changes that result in alterations in the expression of genes that regulate mammary epithelial cell fate, i.e. cell proliferation and differentiation. Lifetime soy consumption at a moderate level may prevent breast cancer recurrence through mechanisms that change the biology of tumors; e.g. women who consumed soy during childhood develop breast cancers that express significantly reduced Human epidermal growth factor receptor 2 levels. More research is needed to understand why soy intake during early life may both reduce breast cancer risk and risk of recurrence.

Estrogen receptor beta2 and beta5 are associated with poor prognosis in prostate cancer, and promote cancer cell migration and invasion

Estrogens play a pivotal role in the development and progression of prostate cancer (PCa). Their actions are mediated by estrogen receptors (ERs), particularly ERbeta in the prostate epithelium. With the discovery of ERbeta isoforms, data from previous studies that focused principally on the wild-type ERbeta (ERbeta1) may not be adequate in explaining the still controversial role of ERbeta(s) in prostate carcinogenesis. In this study, using newly generated isoform-specific antibodies, immunohistochemistry (IHC) was performed on a tumor microarray comprised of 144 specimens. IHC results were correlated with pathological and clinical follow-up data to delineate the distinct roles of ERbeta1, ERbeta2, and ERbeta5 in PCa. ERbeta2 was commonly found in the cytoplasm and was the most abundant isoform followed by ERbeta1 localized predominantly in the nucleus, and ERbeta5 was primarily located in the cytoplasm. Logistic regression analyses demonstrated that nuclear ERbeta2 (nERbeta2) is an independent prognostic marker for prostate specific antigen (PSA) failure and postoperative metastasis (POM). In a Kaplan-Meier analysis, the combined expression of both nERbeta2 and cytoplasmic ERbeta5 identified a group of patients with the shortest POM-free survival. Cox proportional hazard models revealed that nERbeta2 predicted shorter time to POM. In concordance with IHC data, stable, ectopic expression of ERbeta2 or ERbeta5 enhanced PCa cell invasiveness but only PCa cells expressing ERbeta5 exhibited augmented cell migration. This is the first study to uncover a metastasis-promoting role of ERbeta2 and ERbeta5 in PCa, and show that the two isoforms, singularly and conjointly, have prognostic values for PCa progression. These findings may aid future clinical management of PCa.

Phosphorylation of estrogen receptor beta at serine 105 is associated with good prognosis in breast cancer

Estrogen receptor (ER) action is modulated by posttranslational modifications. Although ERalpha phosphorylation correlates with patient outcome, ERbeta is similarly phosphorylated but its significance in breast cancer has not been addressed. We investigated whether ERbeta that is phosphorylated at serine 105 (S105-ERbeta) is expressed in breast cancer and assessed potential clinical implications of this phosphorylation. Following antibody validation, S105-ERbeta expression was studied in tissue microarrays comprising 108 tamoxifen-resistant and 351 tamoxifen-sensitive cases and analyzed against clinical data. S105-ERbeta regulation in vitro was assessed by Western blot, flow cytometry, and immunofluorescence. Nuclear S105-ERbeta was observed in breast carcinoma and was associated with better survival (Allred score > or =3), even in tamoxifen-resistant cases, and additionally correlated with ERbeta1 and ERbeta2 expression. Distinct S105-ERbeta nuclear speckles were seen in some higher grade tumors. S105-ERbeta levels increased in MCF-7 cells in response to 17beta-estradiol, the ERbeta-specific agonist diarylpropionitrile, and the partial ERbeta-agonist genistein. S105-ERbeta nuclear speckles were also seen in MCF-7 cells and markedly increased in size and number at 24 hours following 17beta-estradiol and, in particular diarylpropionitrile, treatment. These speckles were coexpressed with ERbeta1 and ERbeta2. Presence of S105-ERbeta in breast cancer and association with improved survival, even in endocrine resistant breast tumors suggest S105-ERbeta might be a useful additional prognostic marker in this disease.

Nuclear and cytoplasmic expressions of ERβ1 and ERβ2 are predictive of response to therapy and alters prognosis in familial breast cancers

Estrogen receptor (ER) α has been studied extensively in familial breast cancers but there are limited data on ERβ and its isoforms. This is an important issue since many BRCA1-associated tumours are "triple negative" and are resistant to conventional and targeted therapies. We performed an immunohistochemical study of pan-ERβ, ERβ1 and ERβ2 in a cohort of 123 familial breast carcinomas (35 BRCA1, 33 BRCA2 and 55 BRCAX) using a cut-off for positivity at 20% (Shaaban et al. in Clin Cancer Res 14:5228-5235, 2008). BRCA1 cancers were more likely to be nuclear ERα negative and nuclear pan-ERβ positive (21/32, 66%) when compared with BRCA2 (2/29, 7%) and BRCAX cancers (11/49, 22%) (both P < 0.001). For survival analysis, expression was also stratified using cut-offs defined by Bates et al. (Breast Cancer Res Treat 111:453-459, 2008) (score out of 7). Cytoplasmic ERβ2 expression correlated with shorter overall survival at 15 years regardless of cut-off used (both P < 0.046) At a cut-off score of 6 out of 7, cytoplasmic ERβ2 expression correlated with a poorer response to chemotherapy in both univariate (P = 0.011) and multivariate analyses including grade, lymph node status and chemotherapy as an interaction variable (P = 0.045, Hazard ratio 1.22, 95% CI 1.004-9.87). A similar trend was seen in a univariate analysis with a cut-off of 20% although this did not reach statistical significance (P = 0.057). Expression of nuclear ERβ1 was associated with a favourable response to endocrine therapy at 15 years regardless of cut-offs employed (both P < 0.025). However, this did not reach statistical significance in a multivariate analysis (P > 0.05). Since a significant proportion of ERα negative familial breast carcinomas are positive for nuclear ERβ1 and cytoplasmic ERβ2, the different ERβ isoforms and their intracellular location may need to be assessed, to identify patients that may benefit from hormonal and chemotherapy.

Role of ERalpha in the differential response of Stat5a loss in susceptibility to mammary preneoplasia and DMBA-induced carcinogenesis

Deregulated estrogen signaling is evidently linked to breast cancer pathophysiology, although the role of signal transducer and activator of transcription (Stat)5a, integral to normal mammary gland development, is less clear. A mouse model of mammary epithelial cell-targeted deregulated estrogen receptor alpha (ERalpha) expression [conditional ERalpha in mammary epithelium (CERM)] was crossed with mice carrying a germ line deletion of Stat5a [Stat5a-/-] to investigate interactions between ERalpha and Stat5a in mammary tissue. CERM, CERM/Stat5a+/-, CERM/Stat5a-/-, Stat5a+/-, Stat5a-/- and wild-type (WT) mice were generated to test the roles of ERalpha and Stat5a on pubertal differentiation and cancer progression with and without exposure to the chemical carcinogen 7,12-dimethylbenz[a]anthracene (DMBA). Only CERM/Stat5a-/- mice demonstrated delayed pubertal terminal end bud differentiation. Without DMBA exposure, Stat5a loss abrogated ERalpha-initiated hyperplastic alveolar nodule (HAN) development and, similarly, Stat5a-/- mice did not develop HANs. However, although Stat5a loss still reduced ERalpha-initiated HAN prevalence following DMBA exposure, Stat5a loss without deregulated ERalpha was associated with an increased HAN prevalence compared with WT. Progression to ERalpha(+) and ERalpha(-) adenocarcinoma was found in all CERM-containing genotypes (CERM, CERM/Stat5a+/-, CERM/Stat5a-/-) and ERalpha(+) adenocarcinoma in the Stat5a-/- genotype. The mammary epithelial cell proliferative index was increased only in CERM mice independent of Stat5a loss. No differences in apoptotic indices were found. In summary, Stat5a cooperated with deregulated ERalpha in retarding pubertal mammary differentiation and contributed to ERalpha-initiated preneoplasia, but its loss did not prevent development of invasive cancer. Moreover, in the absence of deregulated ERalpha, Stat5a loss was associated with development of both HANs and invasive cancer following DMBA exposure.

Unliganded estrogen receptor-beta regulation of genes is inhibited by tamoxifen

Tamoxifen can stimulate the growth of some breast tumors and others can become resistant to tamoxifen. We previously showed that unliganded ERbeta inhibits ERalpha-mediated proliferation of MCF-7 cells. We investigated if tamoxifen might have a potential negative effect on some breast cancer cells by blocking the effects of unliganded ERbeta on gene regulation. Gene expression profiles demonstrated that unliganded ERbeta upregulated 196 genes in MCF-7 cells. Tamoxifen significantly inhibited 73 of these genes by greater than 30%, including several growth-inhibitory genes. To explore the mechanism whereby unliganded ERbeta activates genes and how tamoxifen blocks this effect, we used doxycycline-inducible U2OS-ERbeta cells to produce unliganded ERbeta. Doxycycline produced a dose-dependent activation of the NKG2E, MSMB and TUB3A genes, which was abolished by tamoxifen. Unliganded ERbeta recruitment of SRC-2 to the NKG2E gene was blocked by tamoxifen. Our findings suggest that tamoxifen might exert a negative effect on ERbeta expressing tumors due to its antagonistic action on unliganded ERbeta.

Dietary acrylamide intake and estrogen and progesterone receptor-defined postmenopausal breast cancer risk

Acrylamide, a potential human carcinogen, has been discovered in a variety of heat-treated carbohydrate-rich food products. Previously, dietary acrylamide intake was shown to be associated with endocrine-related cancers in humans. We assessed the association between dietary acrylamide intake and risk of postmenopausal breast cancer stratified by estrogen and progesterone receptor status. This study was embedded within the Netherlands Cohort Study on diet and cancer, which was initiated in 1986 enrolling 62,573 women aged 55-69 years at baseline. After 13.3 years of follow-up, 2225 incident breast cancer cases were ascertained, with hormone receptor status information for 43%. Cox proportional hazards analysis was applied to determine hazard ratios in quintiles of dietary acrylamide intake stratifying on estrogen receptor (ER) and progesterone receptor (PR) and smoking status. No association was observed for overall breast cancer or receptor-negative breast cancer risk, irrespective of smoking status. A statistically non-significantly increased risk of ER positive, PR positive and joint receptor-positive breast cancer was found in never-smoking women. The multivariable-adjusted hazard ratios were 1.31 (95% CI: 0.87-1.97, P (trend) = 0.26) for ER+, 1.47 (0.86-2.51, P (trend) = 0.14) for PR+, and 1.43 (0.83-2.46, P (trend) = 0.16) for ER+PR+, when comparing women in the highest quintile of acrylamide intake (median 36.8 microg/day) to women in the lowest (median 9.5 microg/day). This study showed some indications of a positive association between dietary acrylamide intake and receptor-positive breast cancer risk in postmenopausal never-smoking women. Further studies are needed to confirm or refute our observations.

Dual effects of TGF-beta on ERalpha-mediated estrogenic transcriptional activity in breast cancer

Background

TGF-β resistance often develops in breast cancer cells that in turn overproduce this cytokine to create a local immunosuppressive environment that fosters tumor growth and exacerbates the invasive and metastatic behavior of the tumor cells themselves. Smads-mediated cross-talk with the estrogen receptor has been implied to play an important role in development and/or progression of breast cancer. We investigated how TGF-β regulates ERα-induced gene transcription and potential mechanisms of frequent TGF-β resistance in breast cancer.

Methods

Effect of TGF-β on ERα-mediated gene transcription was investigated in breast cancer cell lines using transient transfection, real-time PCR, sequential DNA precipitation, and small interfering RNA assays. The expression of Smads on both human breast cancer cell lines and ERα-positive human breast cancer tissue was evaluated by immunofluorescence and immunohistochemical assays.

Results

A complex of Smad3/4 mediates TGF-β inhibition of ERα-mediated estrogenic activity of gene transcription in breast cancer cells, and Smad4 is essential and sufficient for such repression. Either overexpression of Smad3 or inhibition of Smad4 leads to the "switch" of TGF-β from a repressor to an activator. Down-regulation and abnormal cellular distribution of Smad4 were associated with some ERα-positive infiltrating human breast carcinoma. There appears a dynamic change of Smad4 expression from benign breast ductal tissue to infiltrating ductal carcinoma.

Conclusion

These results suggest that aberrant expression of Smad4 or disruption of Smad4 activity lead to the loss of TGF-β suppression of ERα transactivity in breast cancer cells.

Soy consumption and histopathologic markers in breast tissue using tissue microarrays

This study examined the relation of soy intake with hormonal and proliferation markers in benign and malignant breast tissue using tissue microarrays (TMAs). TMAs with up to 4 malignant and 4 benign tissue samples for 268 breast cancer cases were constructed. Soy intake in early life and in adulthood was assessed by questionnaire. The TMAs were stained for estrogen receptor (ER) alpha, ERbeta, progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2/neu), proliferating cell nuclear antigen (PCNA), and Ki-67 using standard immunohistochemical methods. Logistic regression was applied for statistical analysis. A higher percentage of women showed positive marker expression in malignant than in benign tissue. With one exception, HER2/neu, no significant associations between soy intake and pathologic markers were observed. Early life soy intake was associated with lower HER2/neu and PCNA staining of malignant tissue. In benign tissue, early life soy intake showed higher ER and PR expression, but no difference in proliferation markers. The results of this investigation provide some assurance that soy intake does not adversely affect markers of proliferation. TMAs were shown to be a useful tool for epidemiologic research.

Novel image analysis approach for quantifying expression of nuclear proteins assessed by immunohistochemistry: application to measurement of oestrogen and progesterone receptor levels in breast cancer

Introduction

Manual interpretation of immunohistochemistry (IHC) is a subjective, time-consuming and variable process, with an inherent intra-observer and inter-observer variability. Automated image analysis approaches offer the possibility of developing rapid, uniform indicators of IHC staining. In the present article we describe the development of a novel approach for automatically quantifying oestrogen receptor (ER) and progesterone receptor (PR) protein expression assessed by IHC in primary breast cancer.

Methods

Two cohorts of breast cancer patients (n = 743) were used in the study. Digital images of breast cancer tissue microarrays were captured using the Aperio ScanScope XT slide scanner (Aperio Technologies, Vista, CA, USA). Image analysis algorithms were developed using MatLab 7 (MathWorks, Apple Hill Drive, MA, USA). A fully automated nuclear algorithm was developed to discriminate tumour from normal tissue and to quantify ER and PR expression in both cohorts. Random forest clustering was employed to identify optimum thresholds for survival analysis.

Results

The accuracy of the nuclear algorithm was initially confirmed by a histopathologist, who validated the output in 18 representative images. In these 18 samples, an excellent correlation was evident between the results obtained by manual and automated analysis (Spearman's ρ = 0.9, P < 0.001). Optimum thresholds for survival analysis were identified using random forest clustering. This revealed 7% positive tumour cells as the optimum threshold for the ER and 5% positive tumour cells for the PR. Moreover, a 7% cutoff level for the ER predicted a better response to tamoxifen than the currently used 10% threshold. Finally, linear regression was employed to demonstrate a more homogeneous pattern of expression for the ER (R = 0.860) than for the PR (R = 0.681).

Conclusions

In summary, we present data on the automated quantification of the ER and the PR in 743 primary breast tumours using a novel unsupervised image analysis algorithm. This novel approach provides a useful tool for the quantification of biomarkers on tissue specimens, as well as for objective identification of appropriate cutoff thresholds for biomarker positivity. It also offers the potential to identify proteins with a homogeneous pattern of expression.

Evidence for the expression of estrogen receptors in osteogenic cells isolated from hen medullary bone

Medullary bone is a unique tissue in female birds and forms in the cavity of long bones. This bone displays rapid remodeling in response to circulating estrogen levels, suggesting that the osteoblasts in this bone are highly sensitive to estrogen. The present study examined expression of two estrogen receptor (ER) mRNAs in osteogenic cells of medullary bone of white Leghorn hens in vitro. At day 3, isolated cells from the hen medullary bone expressed alkaline phosphatase activity. Using immunocytochemistry, ER protein was demonstrated in the nuclei of these cells. RT-PCR analysis revealed that ER-alpha mRNA was constantly expressed from day 3 to day 15 of culture, while ER-beta mRNA was not detected throughout the culture period. These results indicate that estrogen may act via ER-alpha, but not ER-beta, on osteogenic cells of the avian medullary bone.

hPMC2 is required for recruiting an ERbeta coactivator complex to mediate transcriptional upregulation of NQO1 and protection against oxidative DNA damage by tamoxifen

In the presence of ERbeta, trans-hydroxytamoxifen (TOT) protects cells against 17beta-estradiol (E(2))-induced oxidative DNA damage (ODD) and this correlates with increased expression of the antioxidative enzyme quinone reductase (QR). Here, we investigate the molecular mechanism responsible for ERbeta-mediated protection against ODD. We observe constitutive interaction between ERbeta and the novel protein hPMC2. Using a combination of breast epithelial cell lines that are either positive or negative for ERalpha, we demonstrate TOT-dependent recruitment of both ERbeta and hPMC2 to the EpRE (electrophile response element)-regulated antioxidative enzyme QR. We further demonstrate TOT-dependent corecruitment of the coactivators Nrf2, PARP-1 (poly (ADP-ribose) polymerase 1) and topoisomerase IIbeta, both in the presence and absence of ERalpha. However, absence of either ERbeta or hPMC2 results in nonrecruitment of PARP-1 and topoisomerase IIbeta, loss of antioxidative enzyme induction and attenuated protection against ODD by TOT even in the presence of Nrf2 and ERalpha. These findings indicate minor role for Nrf2 and ERalpha in TOT-dependent antioxidative gene regulation. However, downregulation of PARP-1 attenuates TOT-dependent antioxidative gene induction. We conclude that ERbeta and hPMC2 are required for TOT-dependent recruitment of coactivators such as PARP-1 to the EpRE resulting in the induction of antioxidative enzymes and subsequent protection against ODD.

Evaluation of the current knowledge limitations in breast cancer research: a gap analysis

BACKGROUND

A gap analysis was conducted to determine which areas of breast cancer research, if targeted by researchers and funding bodies, could produce the greatest impact on patients.

METHODS

Fifty-six Breast Cancer Campaign grant holders and prominent UK breast cancer researchers participated in a gap analysis of current breast cancer research. Before, during and following the meeting, groups in seven key research areas participated in cycles of presentation, literature review and discussion. Summary papers were prepared by each group and collated into this position paper highlighting the research gaps, with recommendations for action.

RESULTS

Gaps were identified in all seven themes. General barriers to progress were lack of financial and practical resources, and poor collaboration between disciplines. Critical gaps in each theme included: (1) genetics (knowledge of genetic changes, their effects and interactions); (2) initiation of breast cancer (how developmental signalling pathways cause ductal elongation and branching at the cellular level and influence stem cell dynamics, and how their disruption initiates tumour formation); (3) progression of breast cancer (deciphering the intracellular and extracellular regulators of early progression, tumour growth, angiogenesis and metastasis); (4) therapies and targets (understanding who develops advanced disease); (5) disease markers (incorporating intelligent trial design into all studies to ensure new treatments are tested in patient groups stratified using biomarkers); (6) prevention (strategies to prevent oestrogen-receptor negative tumours and the long-term effects of chemoprevention for oestrogen-receptor positive tumours); (7) psychosocial aspects of cancer (the use of appropriate psychosocial interventions, and the personal impact of all stages of the disease among patients from a range of ethnic and demographic backgrounds).

CONCLUSION

Through recommendations to address these gaps with future research, the long-term benefits to patients will include: better estimation of risk in families with breast cancer and strategies to reduce risk; better prediction of drug response and patient prognosis; improved tailoring of treatments to patient subgroups and development of new therapeutic approaches; earlier initiation of treatment; more effective use of resources for screening populations; and an enhanced experience for people with or at risk of breast cancer and their families. The challenge to funding bodies and researchers in all disciplines is to focus on these gaps and to drive advances in knowledge into improvements in patient care.

Effects of adiponectin on breast cancer cell growth and signaling

Obesity is a risk factor for postmenopausal breast cancer. Adiponectin/Acrp30 is lower in obese individuals and may be negatively regulating breast cancer growth. Here we determined that five breast cancer cell lines, MDA-MB-231, MDA-MB-361, MCF-7, T47D, and SK-BR-3, expressed one or both of the Acrp30 receptors. In addition, we found that the addition of Acrp30 to MCF-7, T47D, and SK-BR-3 cell lines inhibited growth. Oestrogen receptor (ER) positive MCF-7 and T47D cells were inhibited at lower Acrp30 concentrations than ER-negative SK-BR-3 cells. Growth inhibition may be related to apoptosis since PARP cleavage was increased by Acrp30 in the ER-positive cell lines. To investigate the role of ER in the response of breast cancer cells to Acrp30, we established the MDA-ERalpha7 cell line by insertion of ER-alpha into ER-alpha-negative MDA-MB-231 cells. This line readily formed tumours in athymic mice and was responsive to oestradiol in vivo. In vitro, MDA-ERalpha7 cells were growth inhibited by globular Acrp30 while the parental cells were not. This inhibition appeared to be due to blockage of JNK2 signalling. These results provide information on how obesity may influence breast cancer cell proliferation and establish a new model to examine interactions between ER and Acrp30.

Expression of the forkhead transcription factor FOXP1 is associated with that of estrogen receptor-beta in primary invasive breast carcinomas

We previously identified a correlation between estrogen receptor alpha (ERalpha) and the candidate tumour suppressor gene Forkhead Box P1 (FOXP1), whose nuclear protein expression in breast tumours was associated with improved patient survival. However, the expression pattern of FOXP1 in normal breast tissue is more reminiscent of the second receptor, ERbeta, which has an emerging role as a tumour suppressor in breast cancer and critically may underlie the ability of some ERalpha-negative tumours to respond to tamoxifen. In a series of 283 breast cancers, in which ERalpha-positive tumours were treated with tamoxifen, the nuclear expression of ERbeta correlated significantly with ERalpha (p = 0.004), low-tumour grade (p = 0.008) and nuclear FOXP1 (p = 0.01). High-grade tumours exhibited significantly more cytoplasmic ERbeta than the low-grade tumours (p = 0.006). Regression analysis demonstrated that FOXP1 expression was most closely related to nuclear ERbeta (p = 0.021). Neither, nuclear or cytoplasmic ERbeta expression demonstrated prognostic significance. FOXP1 is not estrogen regulated and silencing FOXP1 expression, using siRNA, did not affect ERalpha, ERbeta or progesterone receptor expression, suggesting ER and FOXP1 co-expression may reflect a common regulatory mechanism.

Identification of differentially expressed genes after PPM1D silencing in breast cancer

Amplification and overexpression of PPM1D (protein phosphatase magnesium-dependent 1 delta) has been observed in various cancer cell lines and primary tumors and has also been associated with cancers of poor prognosis. In addition to the negative feedback regulation of p38-p53 signaling, PPM1D inhibits other tumor suppressor activities and is involved in the control of DNA damage and repair pathways. To elucidate the functional significance of PPM1D in breast cancer, we employed RNA interference to downregulate PPM1D expression in BT-474, MCF7, and ZR-75-1 breast cancer cell lines and then investigated the effects of PPM1D silencing on global gene expression patterns and signaling pathways using oligonucleotide microarrays. We identified 1798 differentially expressed (at least a two-fold change) gene elements with functions related to key cellular processes, such as regulation of cell cycle, assembly of various intracellular structures and components, and regulation of signaling pathways and metabolic cascades. For instance, genes involved in apoptosis (NR4A1, RAB25, PLK1), formation of nucleosome structure (HIST1H2AC, HIST1H2BF, HIST1H2BO, HIST1H1D), and hormone related activities (NR4A1, ESR1, STC1) were among the differentially expressed genes. Overall, our findings suggest that PPM1D contributes to breast cancer associated phenotypic characteristics by directly or indirectly affecting several important cellular signaling pathways.