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1.  Estrogen Receptor β Protein in Human Breast Cancer: Correlation with Clinical Tumor Parameters 
Cancer research  2003;63(10):2434-2439.
The recent discovery of a second estrogen receptor, designated ERβ, raises pressing questions about its role in estrogen regulation of human breast cancer cells, and its significance for the prediction of recurrence and treatment responses in clinical breast cancer. Most of what we know about ERβ expression comes from studies examining a limited number of samples at the RNA level. We have now generated a monoclonal antibody useful for the detection of ERβ at the protein level in archival, formalin-fixed breast tumors, and have examined its expression using immunohistochemistry (IHC) in a pilot series of 242 breast cancer patients. Co-expression of ERβ and ERα was found in the majority of the tumors, with 76% of the tumors expressing ERβ as determined by IHC. ERα, but not ERβ, was strongly associated with progesterone receptor (PR) expression, suggesting that ERα is the predominant regulator of this estrogen-induced gene in breast tumors. Although ERα expression was positively correlated with low tumor grade, diploidy, and low S-phase fraction, all biological parameters of a good prognostic profile, ERβ trended toward an association only with aneuploidy; no association with tumor grade or S-phase fraction was seen for ERβ. We found that ERβ expression does cause false-positive readings for ERα. These results suggest that ERβ expression is not a surrogate for ERα in clinical breast tumors, and as such, could be a useful biomarker in its own right.
PMCID: PMC4482102  PMID: 12750263
estrogen receptor β; breast cancer
2.  Cellular reprogramming by the conjoint action of ERα, FOXA1, and GATA3 to a ligand-inducible growth state 
Estrogen receptor α (ERα), FOXA1, and GATA3 form a functional enhanceosome in MCF-7 breast carcinoma cell that is significantly associated with active transcriptional features such as enhanced p300 co-activator and RNA Pol II recruitment as well as chromatin opening.The enhanceosome exerts significant impact and optimal transcriptional control in the regulation of E2-responsive genes.The presence of FOXA1 and GATA3 is indispensable in restoring the ERα growth-response machinery in the ERα-negative cells and recapitulating the appropriate expression cassette.
Estrogen receptor α (ERα) is a ligand-inducible hormone nuclear receptor that has important physiology and pathology roles in reproduction, cancer, and cardiovascular biology. The regulation of ERα involves its binding to the DNA recognition sequence also known as estrogen-response elements (EREs) and recruits a variety of co-activators, corepressors, and chromatin remodeling enzymes to initiate transcription machinery. In our previous (Lin et al, 2007) and recent (Joseph et al, 2010) studies, we have identified high confidence ERα binding sites in MCF-7 human mammary carcinoma cells. With known motif scanning and de novo motif detection, we identified that FOXA1 and GATA3 motifs were commonly enriched around ERα binding sites. Moreover, numerous microarray studies have documented the co-expression of ERα, FOXA1, and GATA3 in primary breast tumors (Badve et al, 2007; Wilson and Giguere, 2008). This evidence suggests that these three transcription factors (TFs) may cluster on DNA binding sites and contribute to the breast cancer phenotype. However, there is little understanding as to the nature of their coordinated interaction at the genome level or the biological consequences of their detailed interaction.
We mapped the genome-wide binding profiles of ERα, FOXA1, and GATA3 using the massive parallel chromatin immunoprecipitation-sequencing (ChIP-seq) approach. We observed that ERα, FOXA1, and GATA3 colocalized in a coordinated manner where ∼30% of all ERα binding sites were overlapped with FOXA1 and GATA3 bindings upon estrogen (E2) stimulation. Moreover, we found that the ERα+FOXA1+GATA3 conjoint sites were associated with highest p300 co-activator recruitment, RNA Pol II occupancy, and chromatin opening. Such results indicate that these three TFs form a functional enhanceosome and cooperatively modulate the transcriptional networks previously ascribed to ERα alone. And such enhanceosome binding sites appear to regulate the genes driving core ERα function.
To further validate that ERα+FOXA1+GATA3 co-binding represents an optimal configuration for E2-mediated transcriptional activation, we have performed luciferase reporter assays on GREB1 locus that actively engages ERα enhanceosome sites in gene regulation (Figure 5C). The presence of ERα induced the GREB1 luciferase activity to ∼246% (as compared with the control construct). The individual presence of FOXA1 and GATA3 or combination of both only produced subtle changes to the GREB1 luciferase activity. The combination of ERα+FOXA1 and ERα+GATA3 has increased the luciferase activity to ∼330%. Interestingly, the assemblage of ERα+FOXA1+GATA3 provided the optimal ER responsiveness to 370%. This suggests that ERα provides the fundamental gene regulatory module but that FOXA1 and GATA3 incrementally improve ERα-regulated transcriptional induction.
It is known that ERα is a ligand-activated TF that mediates the proliferative effects of E2 in breast cancer cells. Garcia et al (1992) showed inhibited growth in MDA-MB-231 cells with forced expression of ERα upon E2 treatment. The rationale for these different outcomes has remained elusive. We posited that these higher order regulatory mechanisms of ERα function such as the formation and composition of enhanceosomes may explain the establishment of transcriptional regulatory cassettes favoring either growth enhancement or growth repression.
To test this hypothesis, we stably transfected the MDA-MB-231 cells with individual ERα, FOXA1, GATA3, or in combinations (Figure 6A). We observed inhibited growth in cells with enforced expression of ERα or FOXA1. There was unaltered growth in cells with expression of GATA3. Co-expression of ERα+FOXA1 or ERα+GATA3 exhibited inhibition of cell proliferation as compared with control cells. However, the co-expression of ERα together with FOXA1 and GATA3 resulted in marked induction of cell proliferation under E2 stimulation. We have recapitulated this cellular reprogramming in another ERα-negative breast cancer cell line, BT-549 and observed similar E2-responsive growth induction in the ERα+FOXA1+GATA3-expressing BT-549 cells. This suggests that only with the full activation of conjoint binding sites by the three TFs will the proliferative phenotype associated with ligand induced ERα be manifest.
To assess the nature of this transcriptional reprogramming, we asked the question if the reprogrammed MDA-MB-231 cells display any similarity in the expression profile of the ERα-positive breast cancer cell line, MCF-7 (Figure 6C). We combined the E2-regulated genes from these differently transfected MDA-MB-231 cells, and compared their expressions in these MDA-MB-231-transfected cells and MCF-7 cells. Strikingly, we found that the expression profiles of ERα+FOXA1+GATA3-expressing MDA-MB-231 cells display a good correlation (R=0.42) with the E2-induced expression profile of MCF-7. We did not observe such correlation between the expression profiles of MDA-MB-231 transfected with ERα only (R=−0.21). Furthermore, we observed that there is marginal induced expression of luminal marker genes and reduced expression of basal genes in the ERα+FOXA1+GATA3-expressing MDA-MB-231 as compared with the vector control cells. This suggests that the enhanceosome component is competent to partially reprogramme the basal cells to resemble the luminal cells.
Taken together, we have uncovered the genomics impact as well as the functional importance of an enhanceosome comprising ERα, FOXA1, and GATA3 in the estrogen responsiveness of ERα-positive breast cancer cells. This enhanceosome exerts significant combinatorial control of the transcriptional network regulating growth and proliferation of ERα-positive breast cancer cells. Most importantly, we show that the transfection of the enhanceosome component was necessary to reprogramme the ERα-negative cells to restore the estrogen-responsive growth and to transcriptionally induce a basal to luminal transition.
Despite the role of the estrogen receptor α (ERα) pathway as a key growth driver for breast cells, the phenotypic consequence of exogenous introduction of ERα into ERα-negative cells paradoxically has been growth inhibition. We mapped the binding profiles of ERα and its interacting transcription factors (TFs), FOXA1 and GATA3 in MCF-7 breast carcinoma cells, and observed that these three TFs form a functional enhanceosome that regulates the genes driving core ERα function and cooperatively modulate the transcriptional networks previously ascribed to ERα alone. We demonstrate that these enhanceosome occupied sites are associated with optimal enhancer characteristics with highest p300 co-activator recruitment, RNA Pol II occupancy, and chromatin opening. Most importantly, we show that the transfection of all three TFs was necessary to reprogramme the ERα-negative MDA-MB-231 and BT-549 cells to restore the estrogen-responsive growth resembling estrogen-treated ERα-positive MCF-7 cells. Cumulatively, these results suggest that all the enhanceosome components comprising ERα, FOXA1, and GATA3 are necessary for the full repertoire of cancer-associated effects of the ERα.
PMCID: PMC3202798  PMID: 21878914
enhanceosome; estrogen receptor α; FOXA1; GATA3; synthetic phenotypes
3.  Estrogen receptor beta impacts hormone-induced alternative mRNA splicing in breast cancer cells 
BMC Genomics  2015;16(1):367.
Estrogens play an important role in breast cancer (BC) development and progression; when the two isoforms of the estrogen receptor (ERα and ERβ) are co-expressed each of them mediate specific effects of these hormones in BC cells. ERβ has been suggested to exert an antagonist role toward the oncogenic activities of ERα, and for this reason it is considered an oncosuppressor. As clinical evidence regarding a prognostic role for this receptor subtype in hormone-responsive BC is still limited and conflicting, more knowledge is required on the biological functions of ERβ in cancer cells. We have previously described the ERβ and ERα interactomes from BC cells, identifying specific and distinct patterns of protein interactions for the two receptors. In particular, we identified factors involved in mRNA splicing and maturation as important components of both ERα and ERβ pathways. Guided by these findings, here we performed RNA sequencing to investigate in depth the differences in the early transcriptional events and RNA splicing patterns induced by estradiol in cells expressing ERα alone or ERα and ERβ.
Exon skipping was the most abundant splicing event in the post-transcriptional regulation by estradiol. We identified several splicing events induced by ERα alone and by ERα + ERβ, demonstrating for the first time that ERβ significantly affects estrogen-induced splicing in BC cells, as revealed by modification of a subset of ERα-dependent splicing by ERβ, as well as by the presence of splicing isoforms only in ERβ + cells. In particular, we observed that ERβ + BC cell lines exhibited around 2-fold more splicing events than the ERβ- cells. Interestingly, we identified putative direct targets of ERβ-mediated alternative splicing by correlating the genomic locations of ERβ and ERα binding sites with estradiol-induced differential splicing in the corresponding genes.
Taken together, these results demonstrate that ERβ significantly affects estrogen-induced early transcription and mRNA splicing in hormone-responsive BC cells, providing novel information on the biological role of ERβ in these tumors.
Electronic supplementary material
The online version of this article (doi:10.1186/s12864-015-1541-1) contains supplementary material, which is available to authorized users.
PMCID: PMC4424892  PMID: 25956916
Breast cancer; Estrogen receptor beta; Alternative splicing; Alternative promoters; RNAseq
4.  Association of oestrogen receptor beta 2 (ERβ2/ERβcx) with outcome of adjuvant endocrine treatment for primary breast cancer – a retrospective study 
BMC Cancer  2007;7:131.
Oestrogen receptor beta (ERβ) modulates ERα activity; wild type ERβ (ERβ1) and its splice variants may therefore impact on hormone responsiveness of breast cancer. ERβ2/ERβcx acts as a dominant negative inhibitor of ERα and expression of ERβ2 mRNA has been proposed as a candidate marker for outcome in primary breast cancer following adjuvant endocrine therapy. We therefore now assess ERβ2 protein by immunostaining and mRNA by quantitative RT-PCR in relation to treatment outcome.
ERβ2-specific immunostaining was quantified in 141 primary breast cancer cases receiving adjuvant endocrine therapy, but no neoadjuvant therapy or adjuvant chemotherapy. The expression of mRNA for ERβ2/ERβcx was measured in 100 cases by quantitative RT-PCR. Statistical analysis of breast cancer relapse and breast cancer survival was performed using Kaplan Meier log-rank tests and Cox's univariate and multivariate survival analysis.
High ERβ2 immunostaining (Allred score >5) and high ERβ2 mRNA levels were independently associated with significantly better outcome across the whole cohort, including both ERα positive and negative cases (Log-Rank P < 0.05). However, only ERβ2 mRNA levels were significantly associated with better outcome in the ERα + subgroup (Log-Rank P = 0.01) and this was independent of grade, size, nodal status and progesterone receptor status (Cox hazard ratio 0.31 P = 0.02 for relapse; 0.17 P = 0.01 for survival). High ERβ2 mRNA was also associated with better outcome in node negative cases (Log Rank P < 0.001).
ERβ2 protein levels were greater in ERα positive cases (T-test P = 0.00001), possibly explaining the association with better outcome. Levels of ERβ2 protein did not correlate ERβ2 mRNA levels, but 34% of cases had both high mRNA and protein and had a significantly better outcome (Log-Rank relapse P < 0.005).
High ERβ2 protein levels were associated with ERα expression. Although most cases with high ERβ2 mRNA had strong ERβ2 immunostaining, mRNA levels but not protein levels were independently predictive of outcome in tamoxifen-treated ERα + tumours. Post-transcriptional control needs to be considered when assessing the biological or clinical importance of ERβ proteins.
PMCID: PMC1950511  PMID: 17640362
5.  Expression profile and prognostic role of sex hormone receptors in gastric cancer 
BMC Cancer  2012;12:566.
Increasing interest has been devoted to the expression and possible role of sex hormone receptors in gastric cancer, but most of these findings are controversial. In the present study, the expression profile of sex hormone receptors in gastric cancer and their clinicopathological and prognostic value were determined in a large Chinese cohort.
The mRNA and protein expression of estrogen receptor alpha (ERα), estrogen receptor beta (ERβ), progesterone receptor (PR), and androgen receptor (AR) in primary gastric tumors and corresponding adjacent normal tissues from 60 and 866 Chinese gastric cancer patients was detected by real-time quantitative PCR and immunohistochemistry method, respectively. The expression profile of the four receptors was compared and their associations with clinicopathological characteristics were assessed by using Chi-square test. The prognostic value of the four receptors in gastric cancer was evaluated by using univariate and multivariate Cox regression analysis.
The presence of ERα, ERβ, PR, and AR in both gastric tumors and normal tissues was confirmed but their expression levels were extremely low except for the predominance of ERβ. The four receptors were expressed independently and showed a decreased expression pattern in gastric tumors compared to adjacent normal tissues. The positive expression of the four receptors all correlated with high tumor grade and intestinal type, and ERα and AR were also associated with early TNM stage and thereby a favorable outcome. However, ERα and AR were not independent prognostic factors for gastric cancer when multivariate survival analysis was performed.
Our findings indicate that the sex hormone receptors may be partly involved in gastric carcinogenesis but their clinicopathological and prognostic significance in gastric cancer appears to be limited.
PMCID: PMC3517759  PMID: 23199240
Gastric cancer; Estrogen receptor alpha; Estrogen receptor beta; Progesterone receptor; Androgen receptor; Prognosis
6.  KiSS1/GPR54 and estrogen-related gene expression profiles in primary breast cancer 
Oncology Letters  2012;3(4):930-934.
The estrogen receptor α (ERα)-mediated pathway plays a critical role in breast cancer development and progression. KiSS1 was previously described as a metastasis suppressor gene in certain carcinomas. However, the role of KiSS1/GPR54 in breast cancer remains controversial. Whether the function of the KiSS1/GPR54 system depends on estrogen signaling in the breast cancer cell remains to be determined. This study aimed to determine the expression profiles of the KiSS1/GPR54, ERα, ERβ, aromatase and cyclin D1 genes in human breast cancer tissues, and to identify a possible link between the expression levels of the studied genes and the selected clinical and pathological features. The study subjects comprised 59 females treated surgically for primary breast cancer. Total RNA was extracted from frozen breast cancer tissues, and expression levels were examined to determine any correlations. We observed strong positive correlations between the expression levels of the studied genes. The expression of ERα correlated positively with progesterone receptors (PRs), and in these tumors we also observed positive correlations between KiSS1, GPR54 and cyclin D1 mRNAs and the ERα protein. ER-positive breast tumors exhibited higher KiSS1 and GPR54 levels than the ER-negative tumors. The expression levels of the ERα and GPR54 transcripts were higher in the moderately differentiated tumors (G2) compared to the poorly differentiated high-grade (G3) cancers. We also found that HER-2/neu status in breast cancer is negatively associated with GPR54 mRNA expression. Decreasing GPR54 mRNA expression levels in HER-2/neu (+) tumors may be associated with the deregulation of the classical estrogen-mediated signaling pathway in breast tumors, and therefore, with promotion of tumor invasiveness. Our findings indicate that genes involved in the KiSS1/GPR54 system, as well as in the estrogen signaling pathway, may be utilizable molecular factors in pathogenesis studies of breast cancer.
PMCID: PMC3362448  PMID: 22741021
KiSS1/GPR54; estrogen receptors; HER-2/neu; breast cancer
7.  Biologic Roles of Estrogen Receptor-β and Insulin-Like Growth Factor-2 in Triple-Negative Breast Cancer 
BioMed Research International  2015;2015:925703.
Triple-negative breast cancer (TNBC) occurs in 10–15% of patients yet accounts for almost half of all breast cancer deaths. TNBCs lack expression of estrogen and progesterone receptors and HER-2 overexpression and cannot be treated with current targeted therapies. TNBCs often occur in African American and younger women. Although initially responsive to some chemotherapies, TNBCs tend to relapse and metastasize. Thus, it is critical to find new therapeutic targets. A second ER gene product, termed ERβ, in the absence of ERα may be such a target. Using human TNBC specimens with known clinical outcomes to assess ERβ expression, we find that ERβ1 associates with significantly worse 5-year overall survival. Further, a panel of TNBC cell lines exhibit significant levels of ERβ protein. To assess ERβ effects on proliferation, ERβ expression in TNBC cells was silenced using shRNA, resulting in a significant reduction in TNBC proliferation. ERβ-specific antagonists similarly suppressed TNBC growth. Growth-stimulating effects of ERβ may be due in part to downstream actions that promote VEGF, amphiregulin, and Wnt-10b secretion, other factors associated with tumor promotion. In vivo, insulin-like growth factor-2 (IGF-2), along with ERβ1, is significantly expressed in TNBC and stimulates high ERβ mRNA in TNBC cells. This work may help elucidate the interplay of metabolic and growth factors in TNBC.
PMCID: PMC4385615  PMID: 25874233
8.  ERβ in Breast Cancer – Onlooker, Passive Player, or Active Protector? 
Steroids  2008;73(11):1039-1051.
The role of estrogen exposure in breast cancer risk is well-documented, and both estrogen synthesis and actions through the estrogen receptor (ER) have been targeted by therapies to control hormone-dependent breast cancer. The discovery of a second ER form and its therapeutic implications sparked great interest. Both the original ERα and the more recently identified ERβ subtypes bind and respond similarly to many physiological and pharmacological ligands. However, differences in phytoestrogen binding have been noted, and subtype-specific ligands have been developed. Cell-based assays show that ERβ and its variants are generally less active on gene transcription than ERα, and may influence ERα activity; however, both gene- and cell-specific responses occur, and nongenomic activities are less well explored. Specific ligands, and methods to disrupt or eliminate receptor subtype expression in animal and cell models, demonstrate that the ERs have both overlapping and distinct biological functions. Overall, in cell-based studies, ERα appears to play a predominant role in cell proliferation, and ERβ is suggested to be antiproliferative.
The potential for distinct populations of breast tumors to be identified based on ER subtype expression, and to exhibit distinct clinical behaviors, is of greatest interest. Several studies suggest that the majority of ER-positive tumors contain both subtypes, but that some tumors contain only ERβ and may have distinct clinical behaviors and responses. Expression of ERβ together with ERα favors positive responses to endocrine therapy in most studies, and additional studies to determine if the addition of ERβ to ERα as a tumor marker is of clinical benefit are warranted. In contrast, the positive association between ERβ and HER2 expression in high-grade ERα-negative breast cancer does not favor positive responses to endocrine therapy. Expression of ERβ in specific clinical subpopulations, and the potential for therapies targeting ERβ specifically, is discussed.
PMCID: PMC2583259  PMID: 18501937
9.  Expression of estrogen receptor beta in the breast carcinoma of BRCA1 mutation carriers 
BMC Cancer  2008;8:100.
Breast cancers (BC) in women carrying mutations in BRCA1 gene are more frequently estrogen receptor negative than the nonhereditary BC. Nevertheless, tamoxifen has been found to have a protective effect in preventing contralateral tumors in BRCA1 mutation carriers. The identification of the second human estrogen receptor, ERβ, raised a question of its role in hereditary breast cancer. The aim of this study was to assess the frequency of ERα, ERβ, PgR (progesterone receptor) and HER-2 expression in breast cancer patients with mutated BRCA1 gene and in the control group.
The study group consisted of 48 women with BRCA1 gene mutations confirmed by multiplex PCR assay. The patients were tested for three most common mutations of BRCA1 affecting the Polish population (5382insC, C61G, 4153delA). Immunostaining for ERα, ERβ and PgR (progesterone receptor) was performed using monoclonal antibodies against ERα, PgR (DakoCytomation), and polyclonal antibody against ERβ (Chemicon). The EnVision detection system was applied. The study population comprised a control group of 120 BC operated successively during the years 1998–99.
The results of our investigation showed that BRCA1 mutation carriers were more likely to have ERα-negative breast cancer than those in the control group. Only 14.5% of BRCA1-related cancers were ERα-positive compared with 57.5% in the control group (P < 0.0001). On the contrary, the expression of ERβ protein was observed in 42% of BRCA1-related tumors and in 55% of the control group. An interesting finding was that most hereditary cancers (75% of the whole group) were triple-negative: ERα(-)/PgR(-)/HER-2(-) but almost half of this group (44.4%) showed the expression of ERβ.
In the case of BRCA1-associated tumors the expression of ERβ was significantly higher than the expression of ERα. This may explain the effectiveness of tamoxifen in preventing contralateral breast cancer development in BRCA1 mutation carriers.
PMCID: PMC2387169  PMID: 18405391
10.  Global analysis of estrogen receptor beta binding to breast cancer cell genome reveals an extensive interplay with estrogen receptor alpha for target gene regulation 
BMC Genomics  2011;12:36.
Estrogen receptors alpha (ERα) and beta (ERβ) are transcription factors (TFs) that mediate estrogen signaling and define the hormone-responsive phenotype of breast cancer (BC). The two receptors can be found co-expressed and play specific, often opposite, roles, with ERβ being able to modulate the effects of ERα on gene transcription and cell proliferation. ERβ is frequently lost in BC, where its presence generally correlates with a better prognosis of the disease. The identification of the genomic targets of ERβ in hormone-responsive BC cells is thus a critical step to elucidate the roles of this receptor in estrogen signaling and tumor cell biology.
Expression of full-length ERβ in hormone-responsive, ERα-positive MCF-7 cells resulted in a marked reduction in cell proliferation in response to estrogen and marked effects on the cell transcriptome. By ChIP-Seq we identified 9702 ERβ and 6024 ERα binding sites in estrogen-stimulated cells, comprising sites occupied by either ERβ, ERα or both ER subtypes. A search for TF binding matrices revealed that the majority of the binding sites identified comprise one or more Estrogen Response Element and the remaining show binding matrixes for other TFs known to mediate ER interaction with chromatin by tethering, including AP2, E2F and SP1. Of 921 genes differentially regulated by estrogen in ERβ+ vs ERβ- cells, 424 showed one or more ERβ site within 10 kb. These putative primary ERβ target genes control cell proliferation, death, differentiation, motility and adhesion, signal transduction and transcription, key cellular processes that might explain the biological and clinical phenotype of tumors expressing this ER subtype. ERβ binding in close proximity of several miRNA genes and in the mitochondrial genome, suggests the possible involvement of this receptor in small non-coding RNA biogenesis and mitochondrial genome functions.
Results indicate that the vast majority of the genomic targets of ERβ can bind also ERα, suggesting that the overall action of ERβ on the genome of hormone-responsive BC cells depends mainly on the relative concentration of both ERs in the cell.
PMCID: PMC3025958  PMID: 21235772
11.  Estrogen Inhibits Renal Cell Carcinoma Cell Progression through Estrogen Receptor-β Activation 
PLoS ONE  2013;8(2):e56667.
Renal cell carcinoma (RCC) originates in the lining of the proximal convoluted tubule and accounts for approximately 3% of adult malignancies. The RCC incidence rate increases annually and is twofold higher in males than in females. Female hormones such as estrogen may play important roles during RCC carcinogenesis and result in significantly different incidence rates between males and females. In this study, we found that estrogen receptor β (ERβ) was more highly expressed in RCC cell lines (A498, RCC-1, 786-O, ACHN, and Caki-1) than in breast cancer cell lines (MCF-7 and HBL-100); however, no androgen receptor (AR) or estrogen receptor α (ERα) could be detected by western blot. In addition, proliferation of RCC cell lines was significantly decreased after estrogen (17-β-estradiol, E2) treatment. Since ERβ had been documented to be a potential tumor suppressor gene, we hypothesized that estrogen activates ERβ tumor suppressive function, which leads to different RCC incidence rates between males and females. We found that estrogen treatment inhibited cell proliferation, migration, invasion, and increased apoptosis of 786-O (high endogenous ERβ), and ERβ siRNA-induced silencing attenuated the estrogen-induced effects. Otherwise, ectopic ERβ expression in A498 (low endogenous ERβ) increased estrogen sensitivity and thus inhibited cell proliferation, migration, invasion, and increased apoptosis. Analysis of the molecular mechanisms revealed that estrogen-activated ERβ not only remarkably reduced growth hormone downstream signaling activation of the AKT, ERK, and JAK signaling pathways but also increased apoptotic cascade activation. In conclusion, this study found that estrogen-activated ERβ acts as a tumor suppressor. It may explain the different RCC incidence rates between males and females. Furthermore, it implies that ERβ may be a useful prognostic marker for RCC progression and a novel developmental direction for RCC treatment improvement.
PMCID: PMC3584057  PMID: 23460808
12.  Association of 11β-Hydroxysteroid Dehydrogenase Type 1 Expression and Activity with Estrogen Receptor β in Adipose Tissue from Postmenopausal Women 
Menopause (New York, N.Y.)  2012;19(12):1347-1352.
11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) regenerates active cortisol from inert cortisone in adipose tissue. Elevated adipose tissue 11βHSD1 activity is observed in obese humans and rodents where it is linked to obesity and its metabolic consequences. Menopause is also associated with increased abdominal fat accumulation suggesting that estrogen is also important in adipose tissue metabolism. The purpose of this current study was to establish whether estrogen signalling through estrogen receptors-α and -β (ERα and ERβ) can influence 11βHSD1 in premenopausal and postmenopausal adipose tissue.
19 premenopausal (aged 26±5, BMI 23.6±1.6) and 23 postmenopausal healthy women (aged 63±4, BMI 23.4±1.9) were studied. Subcutaneous adipose tissue biopsies and fasting venous blood samples were taken. Body composition was measured by bio-electrical impedance analysis. Human SGBS adipocyte cells were treated with ERα and ERβ-specific agonists for 24h. Basic anthropometric data, Serum 17β-estradiol and progesterone concentrations, ERα and ERβ mRNA levels and 11βHSD1 mRNA, protein and activity levels were assessed.
ERβ and 11βHSD1, but not ERα mRNA was significantly increased in adipose tissue from postmenopausal women compared to premenopausal women. ERβ had a significant positive correlation with the mRNA level of 11βHSD1 in adipose tissue from pre- and postmenopausal women. This association between ERβ and 11βHSD1 was greatest in adipose tissue from postmenopausal women. In human SGBS adipocytes, diarylpropiolnitrile (DPN), a selective ERβ agonist increased 11βHSD1 mRNA, protein and activity levels.
We conclude that in adipose tissue, ERβ-mediated estrogen-signalling can upregulate 11βHSD1 and that this may be of particular importance in postmenopausal women.
PMCID: PMC3510652  PMID: 23190557
menopause; Estrogen receptor β; 11β-Hydroxysteroid Dehydrogenase Type 1; adipose tissue
13.  Polymorphic repeat in AIB1 does not alter breast cancer risk 
Breast Cancer Research : BCR  2000;2(5):378-385.
We assessed the association between a glutamine repeat polymorphism in AIB1 and breast cancer risk in a case-control study (464 cases, 624 controls) nested within the Nurses' Health Study cohort. We observed no association between AIB1 genotype and breast cancer incidence, or specific tumor characteristics. These findings suggest that AIB1 repeat genotype does not influence postmenopausal breast cancer risk among Caucasian women in the general population.
A causal association between endogenous and exogenous estrogens and breast cancer has been established. Steroid hormones regulate the expression of proteins that are involved in breast cell proliferation and development after binding to their respective steroid hormone receptors. Coactivator and corepressor proteins have recently been identified that interact with steroid hormone receptors and modulate transcriptional activation [1]. AIB1 (amplified in breast 1) is a member of the steroid receptor coactivator (SRC) family that interacts with estrogen receptor (ER)α in a ligand-dependent manner, and increases estrogen-dependent transcription [2]. Amplification and overexpression of AIB1 has been observed in breast and ovarian cancer cell lines and in breast tumors [2,3]. A polymorphic stretch of glutamine amino acids, with unknown biologic function, has recently been described in the carboxyl-terminal region of AIB1 [4]. Among women with germline BRCA1 mutations, significant positive associations were observed between AIB1 alleles with 26 or fewer glutamine repeats and breast cancer risk [5]
To establish whether AIB1 repeat alleles are associated with breast cancer risk and specific tumor characteristics among Caucasian women.
Patients and methods:
We evaluated associations prospectively between AIB1 alleles and breast cancer risk in the Nurses' Health Study using a nested case-control design. The Nurses' Health Study was initiated in 1976, when 121 700 US-registered nurses between the ages of 30 and 55 years returned an initial questionnaire reporting medical histories and baseline health-related exposures. Between 1989 and 1990 blood samples were collected from 32 826 women. Eligible cases in this study consisted of women with pathologically confirmed incident breast cancer from the subcohort who gave a blood specimen. Cases with a diagnosis anytime after blood collection up to June 1, 1994, with no previously diagnosed cancer except for nonmelanoma skin cancer were included. Controls were randomly selected participants who gave a blood sample and were free of diagnosed cancer (except nonmelanoma skin cancer) up to and including the interval in which the cases were diagnosed, and were matched to cases on year of birth, menopausal status, postmenopausal hormone use, and time of day, month and fasting status at blood sampling. The nested case-control study consisted of 464 incident breast cancer cases and 624 matched controls. The protocol was approved by the Committee on Human Subjects, Brigham and Womens' Hospital, Boston, Massachusetts USA. Information regarding breast cancer risk factors was obtained from the 1976 baseline questionnaire, subsequent biennial questionnaires, and a questionnaire that was completed at the time of blood sampling. Histopathologic characteristics, such as stage, tumor size and ER and progesterone receptor (PR) status, were ascertained from medical records when available and used in case subgroup analyses.
AIB1 repeat alleles were determined by automated fluorescence-based fragment detection from polymerase chain reaction (PCR)-amplified DNA extracted from peripheral blood lymphocytes. Fluorescent 5' -labeled primers were utilized for PCR amplification, and glutamine repeat number discrimination was performed using the ABI Prism 377 DNA Sequencer (Perkin-Elmer, Foster City, CA, USA). Genotyping was performed by laboratory personnel who were blinded to case-control status, and blinded quality control samples were inserted to validate genotyping identification procedures (n = 110); concordance for the blinded samples was 100%. Methods regarding plasma hormone assays have previously been reported [6]. Conditional and unconditional logistic regression models, including terms for the matching variables and other potential confounders, were used to assess the association of AIB1 alleles and breast cancer characterized by histologic subtype, stage of disease, and ER and PR status. We also evaluated whether breast cancer risk associated with AIB1 genotype differed within strata of established breast cancer risk factors, and whether repeat length in AIB1 indirectly influenced plasma hormone levels.
The case-control comparisons of established breast cancer risk factors among these women have previously been reported [7], and are generally consistent with expectation. The mean age of the women was 58.3 (standard deviation [SD] 7.1) years, ranging from 43 to 69 years at blood sampling. There were 188 premenopausal and 810 postmenopausal women, with mean ages of 48.1 (SD 2.8) years and 61.4 (SD 5.0) years, respectively, at blood sampling. Women in this study were primarily white; Asians, African-Americans and Hispanics comprised less than 1% of cases or controls.
The distribution of AIB1 glutamine repeat alleles and AIB1 genotypes for cases and controls are presented in Table 1. Women with AIB1 alleles of 26 glutamine repeats or fewer were not at increased risk for breast cancer (odds ratio [OR] 1.01, 95% confidence interval [CI] 0.75-1.36; Table 2). Results were also similar by menopausal status and in analyses additionally adjusting for established breast cancer risk factors. Among premenopausal women, the OR for women with at least one allele with 26 glutamine repeats or fewer was 0.82 (95% Cl 0.37-1.81), and among postmenopausal women the OR was 1.09 (95% Cl 0.78-1.52; Table 2). We did not observe evidence of a positive association between shorter repeat length and advanced breast cancer, defined as women with breast cancer having one or more involved nodes (OR 1.07, 95% Cl 0.64-1.78), or with cancers with a hormone-dependent phenotype (ER-positive: OR 1.16, 95% Cl 0.81-1.65; Table 3). No associations were observed among women who had one or more alleles with 26 glutamine repeats or fewer, with or without a family history of breast cancer (family history: OR 1.09; 95% Cl 0.46-2.58; no family history: OR 0.94; 95% Cl 0.68-1.31; test for interaction P = 0.65). We also did not observe associations with breast cancer risk to be modified by other established breast cancer risk factors. Among postmenopausal controls not using postmenopausal hormones, geometric least-squared mean plasma levels of estrone sulfate and estrone were similar among carriers and noncarriers of AIB1 alleles with 26 glutamine repeats or fewer (both differences: ≤ +3.5%; P >0.50). Mean levels of estradiol were slightly, but nonsignificantly elevated among carriers of alleles with 26 glutamine repeats or fewer (+11.6%; P = 0.08).
In this population-based nested case-control study, women with at most 26 repeating glutamine codons (CAG/CAA) within the carboxyl terminus of AIB1 were not at increased risk for breast cancer. We did not observe shorter repeat alleles to be positively associated with breast cancer grouped by histologic subtype, stage of disease, or by ER and PR status. These data suggest that AIB1 repeat length is not a strong independent risk factor for postmenopausal breast cancer, and does not modify the clinical presentation of the tumor among Caucasian women in the general population.
PMCID: PMC13920  PMID: 11056690
AIB1 polymorphism; breast cancer; genetic susceptibility; molecular epidemiology
14.  Estrogen receptor, progesterone receptor, interleukin-6 and interleukin-8 are variable in breast cancer and benign stem/progenitor cell populations 
BMC Cancer  2014;14:733.
Estrogen receptor positive breast cancers have high recurrence rates despite tamoxifen therapy. Breast cancer stem/progenitor cells (BCSCs) initiate tumors, but expression of estrogen (ER) or progesterone receptors (PR) and response to tamoxifen is unknown. Interleukin-6 (IL-6) and interleukin-8 (IL-8) may influence tumor response to therapy but expression in BCSCs is also unknown.
BCSCs were isolated from breast cancer and benign surgical specimens based on CD49f/CD24 markers. CD44 was measured. Gene and protein expression of ER alpha, ER beta, PR, IL-6 and IL-8 were measured by proximity ligation assay and qRT-PCR.
Gene expression was highly variable between patients. On average, BCSCs expressed 10-106 fold less ERα mRNA and 10-103 fold more ERβ than tumors or benign stem/progenitor cells (SC). BCSC lin-CD49f−CD24−cells were the exception and expressed higher ERα mRNA. PR mRNA in BCSCs averaged 10-104 fold less than in tumors or benign tissue, but was similar to benign SCs. ERα and PR protein detection in BCSCs was lower than ER positive and similar to ER negative tumors. IL-8 mRNA was 10-104 higher than tumor and 102 fold higher than benign tissue. IL-6 mRNA levels were equivalent to benign and only higher than tumor in lin-CD49f−CD24−cells. IL-6 and IL-8 proteins showed overlapping levels of expressions among various tissues and cell populations.
BCSCs and SCs demonstrate patient-specific variability of gene/protein expression. BCSC gene/protein expression may vary from that of other tumor cells, suggesting a mechanism by which hormone refractory disease may occur.
Electronic supplementary material
The online version of this article (doi:10.1186/1471-2407-14-733) contains supplementary material, which is available to authorized users.
PMCID: PMC4190475  PMID: 25269750
Breast cancer; Stem cell; Estrogen receptor; Progesterone receptor; Interleukin-6; Interleukin-8; Proximity ligation assay; Protein
15.  Estrogen receptor splice variants as a potential source of false-positive estrogen receptor status in breast cancer diagnostics 
It is well established that only estrogen receptor (ER)-positive tumors benefit from hormonal therapies. We hypothesized that a subgroup of breast cancer patients expresses estrogen receptor α (ERα), but fails to respond to hormonal therapy due to the expression of a non-functional receptor. We analyzed a series of 2,658 ERα-positive HER2-negative breast tumors for ERα and progesterone receptor (PR) status as determined by mRNA expression and for their molecular subtypes (Luminal type vs Basal type, assessed by BluePrint™ molecular subtyping assay). In addition, we assessed the recurrence risk (low vs high) using the 70-gene MammaPrint™ signature. We found that 55 out of 2,658 (2.1 %) tumors that are ERα positive by mRNA analysis also demonstrate a Basal molecular subtype, indicating that they lack expression of estrogen-responsive genes. These ERα-positive Basal-type tumors express significantly lower levels of both ERα and PR mRNA as compared to Luminal-type tumors (P < 0.0001) and almost invariably (94.5 %) have a high-risk MammaPrint™ profile. Twelve of the MammaPrint™ genes are directly ERα responsive, indicating that MammaPrint™ assesses ERα function in breast cancer without considering ERα mRNA levels. We find a relatively high expression of the dominant negative ERα splice variant ERΔ7 in ERα-positive Basal-type tumors as compared to ERα-positive Luminal-type tumors (P < 0.0001). Expression of the dominant negative ERα variant ERΔ7 provides a rationale as to why tumors are of the Basal molecular subtype while staining ERα positive by immunohistochemistry. These tumors may lack a functional response to estrogen and consequently may not respond to hormonal therapy. Our data indicate that such patients are of MammaPrint™ high recurrence risk and might benefit from adjuvant chemotherapy.
Electronic supplementary material
The online version of this article (doi:10.1007/s10549-013-2648-1) contains supplementary material, which is available to authorized users.
PMCID: PMC3742961  PMID: 23912957
Breast cancer; Estrogen receptor variants; Intrinsic subtypes; Molecular subtypes; Tamoxifen
16.  Association of serum sex steroid receptor bioactivity and sex steroid hormones with breast cancer risk in postmenopausal women 
Endocrine-Related Cancer  2012;19(2):137-147.
Postmenopausal women with elevated serum sex steroids have an increased risk of breast cancer. Most of this risk is believed to be exerted through binding of the sex steroids to their receptors. For the first time, we investigate the association of estrogen receptor (ER) and androgen receptor (AR) serum bioactivity (SB) in addition to hormone levels in samples from women with breast cancer collected before diagnosis. Two hundred postmenopausal women participating in the UK Collaborative Trial of Ovarian Cancer Screening who developed ER-positive breast cancer 0.6–5 years after sample donation were identified and matched to 400 controls. ER and AR bioassays were used to measure ERα, ERβ, and AR SB. Androgen and estrogen levels were measured with immunoassays. Subjects were classified according to quintiles of the respective marker among controls and the associations between SB and hormones with breast cancer risk were determined by logistic regression analysis. ERα and ERβ SB were significantly higher before diagnosis compared with controls, while estrogens showed no difference. Women had a twofold increased breast cancer risk if ERα SB (odds ratio (OR), 2.114; 95% confidence interval (CI), 1.050–4.425; P=0.040) was in the top quintile >2 years before diagnosis or estrone (OR, 2.205; 95% CI, 1.104–4.586; P=0.029) was in the top quintile <2 years before diagnosis. AR showed no significant association with breast cancer while androstenedione (OR, 3.187; 95% CI, 1.738–6.044; P=0.0003) and testosterone (OR, 2.145; 95% CI, 1.256–3.712; P=0.006) were significantly higher compared with controls and showed a strong association with an almost threefold increased breast cancer risk independent of time to diagnosis. This study provides further evidence on the association of androgens and estrogens with breast cancer. In addition, it reports that high ER but not AR SB is associated with increased breast risk >2 years before diagnosis.
PMCID: PMC3322660  PMID: 22199143
17.  Subtype Specific Elevated Expression of Hyaluronidase-1 (HYAL-1) in Epithelial Ovarian Cancer 
PLoS ONE  2011;6(6):e20705.
Epithelial ovarian cancer (EOC) is morphologically heterogeneous being classified as serous, endometrioid, clear cell, or mucinous. Molecular genetic analysis has suggested a role for tumor suppressor genes located at chromosome 3p in serous EOC pathogenesis. Our objective was to evaluate the expression of HYAL1, located at chromosome 3p21.3, in these EOC subtypes, and to investigate its correlation with the expression of steroid hormone receptors.
Methodology/Principal Findings
We determined the mRNA expression of HYAL1, estrogen receptor (ER)-α, ERβ and progesterone receptor (PR) in EOC tumor samples and cell lines using quantitative RT-PCR. We also examined the expression of these genes in a publicly available microarray dataset. HYAL-1 enzyme activity was measured in EOC cell lines and in plasma samples from patients. We found that HYAL1 mRNA expression was elevated in clear cell and mucinous EOC tissue samples, but not in serous and endometrioid samples, normal ovaries or benign tumors. Similar results were obtained by two different techniques and with tissue sample cohorts from two independent institutions. Concordantly, HYAL1 mRNA levels and enzymatic activity were elevated only in EOC cell lines derived from clear cell and mucinous subtypes. We also showed that HYAL1 mRNA was inversely correlated to that of ERα specifically in clear cell and mucinous EOCs. Additionally, ectopic expression of ERα in a clear cell EOC cell line (ER- and PR-negative) induced 50% reduction of HYAL1 mRNA expression, supporting a role of ERα in HYAL1 gene regulation. Significantly, HYAL-1 activity was also high in the plasma of patients with these EOC subtypes.
This is the first report showing high HYAL-1 levels in EOC and demonstrating HYAL1 gene repression by ERα. Our results identify Hyaluronidase-1 as a potential target/biomarker for clear cell and mucinous EOCs and especially in tumors with low ERα levels.
PMCID: PMC3112150  PMID: 21695196
18.  Integrative genomics of gene and metabolic regulation by estrogen receptors α and β, and their coregulators 
To define how the estrogen receptors α and β control specific responses in breast cancer cells, genome-wide patterns of chromatin binding of the ERα and ERβ receptors and their coregulators, SRC3 and RIP140, were determined and integrated with gene expression data and functional analyses.
The closely related transcription factors, estrogen receptors ERα and ERβ, can elicit differential cellular responses.To understand the basis of this specificity, chromatin binding of ERs and key coregulators, and gene expression, were analyzed genome wide in human breast cancer cells containing ERα only, ERα+ERβ, and ERβ only.A clustering-based combinatorial analysis of ChIP-Seq and gene expression data was used to parse genes into groups, specifying their mode of functional regulation in a particular cell background.Through this analysis, RIP140 was identified as an ERβ-preferential cofactor regulating cell proliferation, apoptosis, and adipogenesis programs.A 20-gene ERβ and RIP140 signature was developed, which predicted outcome and disease-free survival in breast cancer patients.
The closely related transcription factors (TFs), estrogen receptors ERα and ERβ, regulate divergent gene expression programs and proliferative outcomes in breast cancer. Utilizing breast cancer cells with ERα, ERβ, or both receptors as a model system to define the basis for differing response specification by related TFs, we show that these TFs and their key coregulators, SRC3 and RIP140, generate overlapping as well as unique chromatin-binding and transcription-regulating modules. Cistrome and transcriptome analyses and the use of clustering algorithms delineated 11 clusters representing different chromatin-bound receptor and coregulator assemblies that could be functionally associated through enrichment analysis with distinct patterns of gene regulation and preferential coregulator usage, RIP140 with ERβ and SRC3 with ERα. The receptors modified each other's transcriptional effect, and ERβ countered the proliferative drive of ERα through several novel mechanisms associated with specific binding-site clusters. Our findings delineate distinct TF-coregulator assemblies that function as control nodes, specifying precise patterns of gene regulation, proliferation, and metabolism, as exemplified by two of the most important nuclear hormone receptors in human breast cancer.
PMCID: PMC3964312  PMID: 23774759
coregulator usage; estrogen receptors α and β; gene regulation; metabolism; proliferation
19.  Mammographic density and epithelial histopathologic markers 
BMC Cancer  2009;9:182.
We explored the association of mammographic density, a breast cancer risk factor, with hormonal and proliferation markers in benign tissue from tumor blocks of pre-and postmenopausal breast cancer cases.
Breast cancer cases were recruited from a case-control study on breast density. Mammographic density was assessed on digitized prediagnostic mammograms using a computer-assisted method. For 279 participants of the original study, we obtained tumor blocks and prepared tissue microarrays (TMA), but benign tissue cores were only available for 159 women. The TMAs were immunostained for estrogen receptor alpha (ERα) and beta (ERβ), progesterone receptor (PR), HER2/neu, Ki-67, and Proliferating Cell Nuclear Antigen (PCNA). We applied general linear models to compute breast density according to marker expression.
A substantial proportion of the samples were in the low or no staining categories. None of the results was statistically significant, but women with PR and ERβ staining had 3.4% and 2.4% higher percent density. The respective values for Caucasians were 5.7% and 11.6% but less in Japanese women (3.5% and -1.1%). Percent density was 3.4% higher in women with any Ki-67 staining and 2.2% in those with positive PCNA staining.
This study detected little evidence for an association between mammographic density and expression of steroid receptors and proliferation markers in breast tissue, but it illustrated the problems of locating tumor blocks and benign breast tissue samples for epidemiologic research. Given the suggestive findings, future studies examining estrogen effects in tissue, cell proliferation, and density in the breast may be informative.
PMCID: PMC2709637  PMID: 19523235
20.  Expression of oestrogen receptors, ERα, ERβ, and ERβ variants, in endometrial cancers and evidence that prostaglandin F may play a role in regulating expression of ERα 
BMC Cancer  2009;9:330.
Endometrial cancer is the most common gynaecological malignancy; risk factors include exposure to oestrogens and high body mass index. Expression of enzymes involved in biosynthesis of oestrogens and prostaglandins (PG) is often higher in endometrial cancers when compared with levels detected in normal endometrium. Oestrogens bind one of two receptors (ERα and ERβ) encoded by separate genes. The full-length receptors function as ligand-activated transcription factors; splice variant isoforms of ERβ lacking a ligand-binding domain have also been described. PGs act in an autocrine or paracrine manner by binding to specific G-protein coupled receptors.
We compared expression of ERs, progesterone receptor (PR) and cyclooxygenase-2 (COX-2) in stage 1 endometrial adenocarcinomas graded as well (G1), moderately (G2) or poorly (G3) differentiated (n ≥ 10 each group) using qRTPCR, single and double immunohistochemistry. We used endometrial adenocarcinoma cell lines to investigate the impact of PGF2α on expression of ERs and PR.
Full length ERβ (ERβ1) and two ERβ variants (ERβ2, ERβ5) were expressed in endometrial cancers regardless of grade and the proteins were immunolocalised to the nuclei of cells in both epithelial and stromal compartments. Immunoexpression of COX-2 was most intense in cells that were ERαneg/low. Expression of PR in endometrial adenocarcinoma (Ishikawa) cell lines and tissues broadly paralleled that of ERα. Treatment of adenocarcinoma cells with PGF2α reduced expression of ERα but had no impact on ERβ1. Cells incubated with PGF2α were unable to increase expression of PR mRNA when they were incubated with E2.
We have demonstrated that ERβ5 protein is expressed in stage 1 endometrial adenocarcinomas. Expression of three ERβ variants, including the full-length protein is not grade-dependent and most cells in poorly differentiated cancers are ERβpos/ERαneg. We found evidence of a link between COX-2, its product PGF2α, and expression of ERα and PR that sheds new light on the cross talk between steroid and PG signalling pathways in this disease.
PMCID: PMC2755482  PMID: 19758455
21.  Smoking Out Reproductive Hormone Actions in Lung Cancer 
Experimental and population-based evidence has been steadily accumulating that steroid hormones are fundamentally involved in the biology of the lung. Both estrogen and progesterone receptors are present in normal and malignant lung tissue, and the reproductive hormones that bind these receptors have a role in lung development, lung inflammation, and lung cancer. The estrogen receptor β (ERβ) was discovered in the 1990's as a novel form of ER that is transcribed from a gene distinct from ERα, the receptor previously isolated from breast tissue. Interestingly, ERβ is the predominate ER expressed in normal and malignant lung tissue, while inflammatory cells that infiltrate the lung are known to express both ERα and ERβ. Although there is evidence from animal models for the preferential effects of ERβ in the lungs of females, human lung tumors from males often contain comparable numbers of ERβ-positive cells and male-derived lung cancer cell lines respond to estrogens. Lung tumors from both males and females also express CYP19 (aromatase), the rate-limiting enzyme in estrogen synthesis that converts testosterone to estrone and β-estradiol. Thus, testosterone acts as a precursor for local estrogen production within lung tumors, independent of reproductive organs. This review discusses the recent literature findings concerning the biology of the ERs, aromatase, and the progesterone receptor (PR) in lung cancer and highlights the ongoing clinical trials and future therapeutic implications of these findings.
PMCID: PMC3972805  PMID: 24398390
22.  Obesity associated alterations in the biology of adipose stem cells mediate enhanced tumorigenesis by estrogen dependent pathways 
Breast Cancer Research : BCR  2013;15(5):R102.
Obesity has been associated with increased incidence and mortality of breast cancer. While the precise correlation between obesity and breast cancer remains to be determined, recent studies suggest that adipose tissue and adipose stem cells (ASCs) influence breast cancer tumorigenesis and tumor progression.
Breast cancer cells lines were co-cultured with ASCs (n = 24), categorized based on tissue site of origin and body mass index (BMI), and assessed for enhanced proliferation, alterations in gene expression profile with PCR arrays, and enhanced tumorigenesis in immunocompromised mice. The gene expression profile of ASCs was assess with PCR arrays and qRT-PCR and confirmed with Western blot analysis. Inhibitory studies were conducted by delivering estrogen antagonist ICI182,780, leptin neutralizing antibody, or aromatase inhibitor letrozole and assessing breast cancer cell proliferation. To assess the role of leptin in human breast cancers, Oncomine and Kaplan Meier plot analyses were conducted.
ASCs derived from the abdominal subcutaneous adipose tissue of obese subjects (BMI > 30) enhanced breast cancer cell proliferation in vitro and tumorigenicity in vivo. These findings were correlated with changes in the gene expression profile of breast cancer cells after co-culturing with ASCs, particularly in estrogen receptor-alpha (ESR1) and progesterone receptor (PGR) expression. Analysis of the gene expression profile of the four groups of ASCs revealed obesity induced alterations in several key genes, including leptin (LEP). Blocking estrogen signaling with ICI182,780, leptin neutralizing antibody, or letrozole diminished the impact of ASCs derived from obese subjects. Women diagnosed with estrogen receptor/progesterone receptor positive (ER+/PR+) breast cancers that also expressed high levels of leptin had poorer prognosis than women with low leptin expression.
ASCs isolated from the abdomen of obese subjects demonstrated increased expression of leptin, through estrogen stimulation, which increased breast cancer cell proliferation. The results from this study demonstrate that abdominal obesity induces significant changes in the biological properties of ASCs and that these alterations enhance ER+/PR+ breast cancer tumorigenesis through estrogen dependent pathways.
PMCID: PMC3978929  PMID: 24176089
23.  Altered expression of ERs, aromatase, and COX2 connected to estrogen action in type 1 endometrial cancer biology 
Tumour Biology  2013;34(6):4007-4016.
In order to study estrogen-driven microenvironment associated with type 1 endometrial carcinoma, we evaluated estrogen receptors (ERs), aromatase, and cyclooxygenase II (COX2) molecular and immunohistochemical profiles with correlation to clinicopathological features. We investigated aromatase, ERα, ERβ, and COX2 expression at the mRNA and protein levels using quantitative real-time PCR and immunohistochemical method in 51 endometrial carcinomas and 16 normal endometria. All the studied tumors, as well as normal endometria, expressed ERα, ERβ, and COX2 mRNAs. Five endometrial carcinoma tissues and one normal endometrium showed no aromatase mRNA expression. The majority of tumors expressed ERα (82 %), aromatase (80 %), and COX2 (88 %) proteins. Forty-one percent of the studied tumors were ERβ-negative. ERα and ERβ showed significantly decreased mRNA and protein expression levels in endometrial carcinoma as compared to normal endometrium. An opposite trend was shown for COX2 and aromatase proteins. ERα expression correlated positively with COX2 expression at both mRNA and protein levels (P < 0.005, r = 0.398; P < 0.0005, r = 0.510, respectively). There was also a positive correlation between COX2 and aromatase expression in cancer tissue (P < 0.002, r = 0.433 for transcriptional level; P < 0.0005, r = 0.614 for protein level). We observed positive correlations between ERβ and ERα, as well as between ERβ and COX2 at the transcriptional level only (P < 0.0005, r = 0.644; P < 0.002, r = 0.444, respectively). Negative correlations were found between pT category of primary tumor and levels of ERα and ERβ transcripts (P < 0.02, r = −0.332; P < 0.02, r = −0.348, respectively). A negative association between ERβ and the International Federation of Gynecology and Obstetrics (FIGO) staging was also found. The growth of EC1 with the presence of ERα and overexpression of aromatase and COX2 is dependent on estrogens. We believe that ERβ may be considered as a potential marker in the progression of disease in endometrial cancer patients.
PMCID: PMC3858613  PMID: 23873111
ERs (ERα, ERβ); Aromatase; COX2; Type 1 endometrial cancer
24.  Telomerase activity, estrogen receptors (α, β), Bcl-2 expression in human breast cancer and treatment response 
BMC Cancer  2006;6:206.
The mechanism for maintaining telomere integrity is controlled by telomerase, a ribonucleoprotein enzyme that specifically restores telomere sequences, lost during replication by means of an intrinsic RNA component as a template for polymerization. Among the telomerase subunits, hTERT (human telomerase reverse transcriptase) is expressed concomitantly with the activation of telomerase. The role of estrogens and their receptors in the transcriptional regulation of hTERT has been demonstrated. The current study determines the possible association between telomerase activity, the expression of both molecular forms of estrogen receptor (ERα and ERβ) and the protein bcl-2, and their relative associations with clinical parameters.
Tissue samples from 44 patients with breast cancer were used to assess telomerase activity using the TRAP method and the expression of ERα, ERβ and bcl-2 by means of immunocytochemical techniques.
Telomerase activity was detected in 59% of the 44 breast tumors examined. Telomerase activity ranged from 0 to 49.93 units of total product generated (TPG). A correlation was found between telomerase activity and differentiation grade (p = 0.03). The only significant independent marker of response to treatment was clinical stage. We found differences between the frequency of expression of ERα (88%) and ERβ (36%) (p = 0.007); bcl-2 was expressed in 79.5% of invasive breast carcinomas. We also found a significant correlation between low levels of telomerase activity and a lack of ERβ expression (p = 0.03).
Lower telomerase activity was found among tumors that did not express estrogen receptor beta. This is the first published study demonstrating that the absence of expression of ERβ is associated with low levels of telomerase activity.
PMCID: PMC1562436  PMID: 16911782
25.  Significance of ERβ expression in different molecular subtypes of breast cancer 
Diagnostic Pathology  2014;9:20.
This study is to investigate the estrogen receptor β (ERβ) expression in molecular subtypes of breast cancer and clinic significance of ERβ expression.
The ERβ expression was detected in 730 cases of breast cancer tissue specimens by immunohistochemistry. Twenty-one patients were censored during 2–10 years follow-up. The difference in ERβ expression was analyzed by Pearson Chi-square Test. Its correlation with estrogen receptor α (ERα), progesterone receptor (PR) and human epidermal growth factor receptor 2 (Her-2) was analyzed by Spearman rank correlation. The accumulative tumor-free survival rate was calculated by Kaplan-Meier method and difference in survival rate was analyzed by Log-rank test. Cox regression was used for multi-factor analysis.
The ERβ expression was significantly different among the molecular subtypes of breast cancer (P < 0.05). The ERβ expression in breast cancer was positively correlated with Her-2 (P < 0.05) while it had no correlation with ERα and Her-2. The expression of ERα was negatively correlated with Her-2 (P < 0.01) whereas positively correlated with PR (P < 0.01). The expression of PR was negatively correlated with Her-2 (P < 0.05). The tumor-free survival rate in patients with positive ERβ expression was significantly lower than that in patients with negative ERβ expression.
Positive ERβ expression is a poor prognostic factor of breast cancer.
Virtual slides
The virtual slides for this article can be found here:
PMCID: PMC3911955  PMID: 24457087
Breast cancer; ERβ; Molecular subtypes

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