GREB1

Gene Summary

Gene:GREB1; growth regulation by estrogen in breast cancer 1
Location:2p25.1
Summary:This gene is an estrogen-responsive gene that is an early response gene in the estrogen receptor-regulated pathway. It is thought to play an important role in hormone-responsive tissues and cancer. Three alternatively spliced transcript variants encoding distinct isoforms have been found for this gene. [provided by RefSeq, Jul 2008]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:protein GREB1
HPRD
Source:NCBIAccessed: 06 August, 2015

Ontology:

What does this gene/protein do?
GREB1 is implicated in:
- integral to membrane
Data from Gene Ontology via CGAP
Pathways:What pathways are this gene/protein implicaed in?
Show (1)

Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 06 August 2015 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Up-Regulation
  • Hormone-Dependent Cancers
  • Oligonucleotide Array Sequence Analysis
  • Transfection
  • RTPCR
  • Chromatin Immunoprecipitation
  • Breast Cancer
  • DNA-Binding Proteins
  • Estrogen Receptor alpha
  • Response Elements
  • siRNA
  • Staging
  • RT-PCR
  • Messenger RNA
  • Ovarian Cancer
  • Random Allocation
  • RNA Interference
  • G-Protein-Coupled Receptors
  • Membrane Proteins
  • Cell Proliferation
  • Western Blotting
  • Estradiol
  • Cancer RNA
  • STAT1 Transcription Factor
  • Cancer Gene Expression Regulation
  • Neoplasm Proteins
  • Tumor Markers
  • Risk Factors
  • Tissue Array Analysis
  • Case-Control Studies
  • Chromosome 2
  • alpha Karyopherins
  • Tumor Suppressor Proteins
  • Estrogen Receptors
  • Estrogens
  • Prostate Cancer
  • Ultrasound, High-Intensity Focused, Transrectal
  • Signal Transduction
  • Gene Expression Profiling
  • Cancer DNA
Tag cloud generated 06 August, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (3)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: GREB1 (cancer-related)

Haynes BP, Viale G, Galimberti V, et al.
Differences in expression of proliferation-associated genes and RANKL across the menstrual cycle in estrogen receptor-positive primary breast cancer.
Breast Cancer Res Treat. 2014; 148(2):327-35 [PubMed] Related Publications
The purpose of this study is to determine if there are differences in the expression of estrogen-regulated genes (ERGs), proliferation-associated genes and the progesterone effector RANKL, in premenopausal ER+ breast cancer as a result of the major changes in hormone levels that occur through the menstrual cycle. Primary ER+ tumours from 174 patients were assigned to one of three menstrual cycle windows: W1 (days 27-35 + 1-6), W2 (days 7-16) and W3 (days 17-26). RNA expression of 42 genes, including 24 putative genes associated with plasma E2 levels, seven proliferation genes and RANKL was measured. Expression of PGR, TFF1, GREB1 and PDZK1 followed the previously reported pattern: a higher level in W2 compared to W1 while W3 had an intermediate value, mirroring changes in plasma estradiol. Of the other 20 ERGs, four (RUNX1, AGR2, SERPINA3 and SERPINA5) showed significant differences (p = 0.009-0.049) in expression across the menstrual cycle. The expression of six of seven proliferation-associated genes varied across the cycle but differently from the ERGs, being 20-35 % lower in W3 compared to W1 and W2 (p = 0.004-0.031). Expression of RANKL was 2.5 to 3-fold highest in W3 (p = 0.0001) and negatively correlated to the expression of the proliferation-associated genes (r = -0.37; p < 0.0001). Expression of proliferation-associated genes and RANKL in ER+ breast tumours varies across the menstrual cycle showing a different rhythm to that of ERGs. This may affect the interpretation of gene expression profiles but may be exploitable as an endogenous test of endocrine responsiveness.

Kim HI, Quan FS, Kim JE, et al.
Inhibition of estrogen signaling through depletion of estrogen receptor alpha by ursolic acid and betulinic acid from Prunella vulgaris var. lilacina.
Biochem Biophys Res Commun. 2014; 451(2):282-7 [PubMed] Related Publications
Extracts of Prunella vulgaris have been shown to exert antiestrogenic effects. To identify the compounds responsible for these actions, we isolated the constituents of P. vulgaris and tested their individual antiestrogenic effects. Rosmarinic acid, caffeic acid, ursolic acid (UA), oleanolic acid, hyperoside, rutin and betulinic acid (BA) were isolated from the flower stalks of P. vulgaris var. lilacina Nakai (Labiatae). Among these constituents, UA and BA showed significant antiestrogenic effects, measured as a decrease in the mRNA level of GREB1, an estrogen-responsive protein; the effects of BA were stronger than those of UA. UA and BA were capable of suppressing estrogen response element (ERE)-dependent luciferase activity and expression of estrogen-responsive genes in response to exposure to estradiol, further supporting the suppressive role of these compounds in estrogen-induced signaling. However, neither UA nor BA was capable of suppressing estrogen signaling in cells ectopically overexpressing estrogen receptor α (ERα). Furthermore, both mRNA and protein levels of ERα were reduced by treatment with UA or BA, suggesting that UA and BA inhibit estrogen signaling by suppressing the expression of ERα. Interestingly, both compounds enhanced prostate-specific antigen promoter activity. Collectively, these findings demonstrate that UA and BA are responsible for the antiestrogenic effects of P. vulgaris and suggest their potential use as therapeutic agents against estrogen-dependent tumors.

Marques M, Laflamme L, Benassou I, et al.
Low levels of 3,3'-diindolylmethane activate estrogen receptor α and induce proliferation of breast cancer cells in the absence of estradiol.
BMC Cancer. 2014; 14:524 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: 3,3'-diindolylmethane (DIM) is an acid-catalyzed dimer of idole-3-carbinol (I3C), a phytochemical found in cruciferous vegetables that include broccoli, Brussels sprouts and cabbage. DIM is an aryl hydrocarbon receptor (AhR) ligand and a potential anticancer agent, namely for the treatment of breast cancer. It is also advertised as a compound that regulates sex hormone homeostasis.
METHODS: Here we make use of RNA expression assays coupled to Chromatin Immunoprecipitation (ChIP) in breast cancer cell lines to study the effect of DIM on estrogen signaling. We further make use of growth assays, as well as fluorescence-activated cell sorting (FACS) assays, to monitor cell growth.
RESULTS: In this study, we report that 'physiologically obtainable' concentrations of DIM (10 μM) activate the estrogen receptor α (ERα) signaling pathway in the human breast cancer cell lines MCF7 and T47D, in a 17β-estradiol (E2)-independent manner. Accordingly, we observe induction of ERα target genes such as GREB1 and TFF1, and an increase in cellular proliferation after treatment with 10 μM DIM in the absence of E2. By using an ERα specific inhibitor (ICI 182 780), we confirm that the transcriptional and proliferative effects of DIM treatment are mediated by ERα. We further show that the protein kinase A signaling pathway participates in DIM-mediated activation of ERα. In contrast, higher concentrations of DIM (e.g. 50 μM) have an opposite and expected effect on cells, which is to inhibit proliferation.
CONCLUSIONS: We document an unexpected effect of DIM on cell proliferation, which is to stimulate growth by inducing the ERα signaling pathway. Importantly, this proliferative effect of DIM happens with potentially physiological concentrations that can be provided by the diet or by taking caplet supplements.

Hodgkinson KM, Vanderhyden BC
Consideration of GREB1 as a potential therapeutic target for hormone-responsive or endocrine-resistant cancers.
Expert Opin Ther Targets. 2014; 18(9):1065-76 [PubMed] Related Publications
INTRODUCTION: Steroid hormones increase the incidence and promote the progression of many types of cancer. Exogenous estrogens increase the risk of developing breast, ovarian and endometrial cancer and many breast cancers initially respond to estrogen deprivation. Although steroid hormone signaling has been extensively studied, the mechanisms of hormone-stimulated cancer growth have not yet been fully elucidated, limiting opportunities for novel approaches to therapeutic intervention.
AREAS COVERED: This review examines growing evidence for the important role played by the steroid hormone-induced gene called GREB1, or growth regulation by estrogen in breast cancer 1. GREB1 is a critical mediator of both the estrogen-stimulated proliferation of breast cancer cells and the androgen-stimulated proliferation of prostate cancer cells.
EXPERT OPINION: Although its exact function in the cascade of hormone action remains unclear, the ability of GREB1 to modulate tumor progression in models of breast, ovarian and prostate cancer renders this gene an excellent candidate for further consideration as a potential therapeutic target. Research examining the mechanism of GREB1 action will help to elucidate its role in proliferation and its potential contribution to endocrine resistance and will determine whether GREB1 interference may have therapeutic efficacy.

Tan S, Ding K, Li R, et al.
Identification of miR-26 as a key mediator of estrogen stimulated cell proliferation by targeting CHD1, GREB1 and KPNA2.
Breast Cancer Res. 2014; 16(2):R40 [PubMed] Free Access to Full Article Related Publications
INTRODUCTION: Estrogen signaling is pivotal in the progression of estrogen receptor positive breast cancer primarily by the regulation of cell survival and proliferation. Micro (mi)RNAs have been demonstrated to be regulated by estrogen to mediate estrogenic effects. Herein, we determined the role of estrogen regulated miR-26 and its underlying molecular mechanisms associated with estrogen receptor (ER)+ breast cancer proliferation.
METHODS: The expression of miR-26a and miR-26b was evaluated by real-time quantitative (RT)-PCR. The expression of miR-26a or miR-26b was modulated in ER+ breast cancer cells (MCF-7 and T47D) and tumor cell growth in vitro and an in vivo xenograft model was determined. Bioinformatics analyses were utilized to screen for estrogen responsive genes, which were also predicted to be targeted by miR-26. Luciferase reporter assays were performed to confirm miR-26 regulation of the 3' UTR of target genes. The levels of miR-26 target genes (CHD1, GREB1 and KPNA2) were evaluated by western blotting and immunohistochemistry.
RESULTS: Estrogen reduced the expression of miR-26a and miR-26b in ER+ breast cancer cells. Forced expression of miR-26a or miR-26b significantly inhibited the estrogen stimulated growth of ER+ breast cancer cells and tumor growth in xenograft models, whereas miR-26a/b depletion increased the growth of ER+ breast cancer cells in the absence of estrogen treatment. Screening of estrogen responsive genes, which were also predicted to be targeted by miR-26, identified GREB1 and nine other genes (AGPAT5, AMMECR1, CHD1, ERLIN1, HSPA8, KPNA2, MREG, NARG1, and PLOD2). Further verification has identified nine genes (AGPAT5, CHD1, ERLIN1, GREB1, HSPA8, KPNA2, MREG, NARG1 and PLOD2) which were directly targeted by miR-26 via their 3' UTR. Functional screening suggested only three estrogen regulated miR-26 target genes (CHD1, GREB1 and KPNA2) were involved in the regulation of estrogen promoted cell proliferation. Depletion of either CHD1, GREB1 or KPNA2 significantly abrogated the enhanced growth of ER+ breast cancer cells due to miR-26 depletion. We further demonstrated that estrogen stimulated c-MYC expression was both sufficient and necessary for the diminished expression of miR-26a and miR-26b.
CONCLUSIONS: We have identified a novel estrogen/MYC/miR-26 axis that mediates estrogen stimulated cell growth via CHD1, GREB1 and KPNA2.

Li M, Guo J, Gao W, et al.
Bisphenol AF-induced endogenous transcription is mediated by ERα and ERK1/2 activation in human breast cancer cells.
PLoS One. 2014; 9(4):e94725 [PubMed] Free Access to Full Article Related Publications
Bisphenol AF (BPAF)-induced transcriptional activity has been evaluated by luciferase reporter assay. However, the molecular mechanism of BPAF-induced endogenous transcription in human breast cancer cells has not been fully elucidated. In the present study, we investigated the effect and mechanism of BPAF-induced endogenous transcription detected by real-time PCR in human breast cancer cells. We found that BPAF stimulated transcription of estrogen responsive genes, such as trefoil factor 1 (TFF1), growth regulation by estrogen in breast cancer 1 (GREB1) and cathepsin D (CTSD), through dose-dependent and time-dependent manners in T47D and MCF7 cells. Gene-silencing of ERα, ERβ and G protein-coupled estrogen receptor 1 (GPER) by small interfering RNA revealed that BPAF-induced endogenous transcription was dependent on ERα and GPER, implying both genomic and nongenomic pathways might be involved in the endogenous transcription induced by BPAF. ERα-mediated gene transcription was further confirmed by inhibition of ER activity using ICI 182780 in ERα-positive T47D and MCF7 cells as well as overexpression of ERα in ERα-negative MDA-MB-231 breast cancer cells. Moreover, we utilized Src tyrosine kinase inhibitor PP2 and two MEK inhibitors PD98059 and U0126 to elucidate the rapid nongenomic activation of Src/MEK/ERK1/2 cascade on endogenous transcription. Our data showed that BPAF-induced transcription could be significantly blocked by PP2, PD98059 and U0126, suggesting activation of ERK1/2 was also required to regulate endogenous transcription. Taken together, these results indicate that BPAF-induced endogenous transcription of estrogen responsive genes is mediated through both genomic and nongenomic pathways involving the ERα and ERK1/2 activation in human breast cancer cells.

Laviolette LA, Hodgkinson KM, Minhas N, et al.
17β-estradiol upregulates GREB1 and accelerates ovarian tumor progression in vivo.
Int J Cancer. 2014; 135(5):1072-84 [PubMed] Free Access to Full Article Related Publications
Exogenous 17β-estradiol (E2) accelerates the progression of ovarian cancer in the transgenic tgCAG-LS-TAg mouse model of the disease. We hypothesized that E2 has direct effects on ovarian cancer cells and this study was designed to determine the molecular mechanisms by which E2 accelerates ovarian tumor progression. Mouse ovarian cancer ascites (MAS) cell lines were derived from tgCAG-LS-TAg mice. Following intraperitoneal engraftment of two MAS cell lines, MASC1 and MASE2, into SCID mice, exogenous E2 significantly decreased the survival time and increased the tumor burden. Microarray analysis performed on MASE2-derived tumors treated with E2 or placebo showed that E2 treatment caused the upregulation of 197 genes and the downregulation of 55 genes. The expression of gene regulated by estrogen in breast cancer 1 (Greb1) was upregulated in mouse tumors treated with E2 and was overexpressed in human ovarian cancers relative to human ovarian surface epithelium, suggesting a role for GREB1 in human ovarian tumor progression. RNA interference-mediated knockdown of GREB1 in MASE2 cells decreased their proliferation rate in vitro and increased survival time in mice engrafted with the cells. These results emphasize the importance of E2 in ovarian tumor progression and identify Greb1 as a novel gene target for therapeutic intervention.

Huang Y, Ju B, Tian J, et al.
Ovarian cancer stem cell-specific gene expression profiling and targeted drug prescreening.
Oncol Rep. 2014; 31(3):1235-48 [PubMed] Related Publications
Cancer stem cells, with unlimited self-renewal potential and other stem cell characteristics, occur in several types of cancer, including ovarian cancer (OvC). Although CSCs can cause tumor initiation, malignant proliferation, relapse and multi-drug resistance, ways to eliminate them remain unknown. In the present study, we compared ovarian cancer stem cell (OVCSC) expression profiles in normal ovarian surface epithelium and ovarian cells from patients with advanced disease to identify key pathways and specific molecular signatures involved in OVC progression and to prescreen candidate small-molecule compounds with anti-OVCSC activity. Comparison of genome-wide expression profiles of OvC stemness groups with non-stemness controls revealed 6495, 1347 and 509 differentially expressed genes in SDC, SP1 and SP2 groups, respectively, with a cut-off of fold-change set at >1.5 and P<0.05. NAB1 and NPIPL1 were commonly upregulated whereas PROS1, GREB1, KLF9 and MTUS1 were commonly downregulated in all 3 groups. Most differentially expressed genes consistently clustered with molecular functions such as protein receptor binding, kinase activity and chemo-repellent activity. These genes regulate cellular components such as centrosome, plasma membrane receptors, and basal lamina, and may participate in biological processes such as cell cycle regulation, chemoresistance and stemness induction. Key Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways such as ECM receptor, ErbB signaling, endocytosis and adherens junction pathways were enriched. Gene co-expression extrapolation screening by the Connectivity Map revealed several small-molecule compounds (such as SC-560, disulfiram, thapsigargin, esculetin and cinchonine) with potential anti-OVCSC properties targeting OVCSC signature genes. We identified several key CSC features and specific regulation networks in OVCSCs and predicted several small molecules with potential anti-OVCSC pharmacological properties, which may aid the development of OVCSC-specific drugs.

Yu T, Zhou Z, Mu Y, et al.
A novel anti-cancer agent, acetyltanshinone IIA, inhibits oestrogen receptor positive breast cancer cell growth by down-regulating the oestrogen receptor.
Cancer Lett. 2014; 346(1):94-103 [PubMed] Related Publications
In this paper we show that acetyltanshinone IIA (ATA), a novel anti-cancer agent, preferentially inhibits cell growth of oestrogen receptor positive (ER+) breast cancer cells and that it is more potent than the commonly used anti-breast cancer agent, tamoxifen. The metabolic product of ATA, hydroquinone tanshinone IIA (HTA) binds to the ERα and causes its degradation mainly in the nucleus via an ubiquitin-mediated proteasome-dependent pathway. In addition, ATA also reduced the mRNA levels of the ERα encoding gene, ESR1, distinguishing ATA from another anti-breast cancer drug, fulvestrant. Finally, ATA reduced the transcription of an ER-responsive gene, GREB1.

Giessrigl B, Schmidt WM, Kalipciyan M, et al.
Fulvestrant induces resistance by modulating GPER and CDK6 expression: implication of methyltransferases, deacetylases and the hSWI/SNF chromatin remodelling complex.
Br J Cancer. 2013; 109(10):2751-62 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Breast cancer is the leading cause of cancer death in women living in the western hemisphere. Despite major advances in first-line endocrine therapy of advanced oestrogen receptor (ER)-positive breast cancer, the frequent recurrence of resistant cancer cells represents a serious obstacle to successful treatment. Understanding the mechanisms leading to acquired resistance, therefore, could pave the way to the development of second-line therapeutics. To this end, we generated an ER-positive breast cancer cell line (MCF-7) with resistance to the therapeutic anti-oestrogen fulvestrant (FUL) and studied the molecular changes involved in resistance.
METHODS: Naive MCF-7 cells were treated with increasing FUL concentrations and the gene expression profile of the resulting FUL-resistant strain (FR.MCF-7) was compared with that of naive cells using GeneChip arrays. After validation by real-time PCR and/or western blotting, selected resistance-associated genes were functionally studied by siRNA-mediated silencing or pharmacological inhibition. Furthermore, general mechanisms causing aberrant gene expression were investigated.
RESULTS: Fulvestrant resistance was associated with repression of GPER and the overexpression of CDK6, whereas ERBB2, ABCG2, ER and ER-related genes (GREB1, RERG) or genes expressed in resistant breast cancer (BCAR1, BCAR3) did not contribute to resistance. Aberrant GPER and CDK6 expression was most likely caused by modification of DNA methylation and histone acetylation, respectively. Therefore, part of the resistance mechanism was loss of RB1 control. The hSWI/SNF (human SWItch/Sucrose NonFermentable) chromatin remodelling complex, which is tightly linked to nucleosome acetylation and repositioning, was also affected, because as a stress response to FUL treatment-naive cells altered the expression of five subunits within a few hours (BRG1, BAF250A, BAF170, BAF155, BAF47). The aberrant constitutive expression of BAF250A, BAF170 and BAF155 and a deviant stress response of BRG1, BAF170 and BAF47 in FR.MCF-7 cells to FUL treatment accompanied acquired FUL resistance. The regular and aberrant expression profiles of BAF155 correlated directly with that of CDK6 in naive and in FR.MCF-7 cells corroborating the finding that CDK6 overexpression was due to nucleosome alterations.
CONCLUSION: The study revealed that FUL resistance is associated with the dysregulation of GPER and CDK6. A mechanism leading to aberrant gene expression was most likely unscheduled chromatin remodelling by hSWI/SNF. Hence, three targets should be conceptually addressed in a second-line adjuvant therapy: the catalytic centre of SWI/SNF (BRG1) to delay the development of FUL resistance, GPER to increase sensitivity to FUL and the reconstitution of the RB1 pathway to overcome resistance.

Wang Z, Li T, Xing X, et al.
Replication study of RAD54B and GREB1 polymorphisms and risk of PCOS in Han Chinese.
Reprod Biomed Online. 2013; 27(3):316-21 [PubMed] Related Publications
A previous genome-wide association study (GWAS) of polycystic ovary syndrome (PCOS) identified several susceptibility loci, with P-values about 10⁻⁵. In the present study, an independent cohort was used for a replication study to evaluate the association of RAD54B and GREB1 with polycystic ovary syndrome (PCOS) in the Han Chinese population. Four single-nucleotide polymorphisms (SNP), rs2930961 (RAD54B), rs12470971, rs11686574 and rs6740248 (GREB1), were genotyped in 1124 PCOS patients and 1067 healthy controls from the Han Chinese population. Real-time quantitative PCR by TaqMan-MGB probe assay was applied for genotyping. The allele and genotype frequencies of these four SNP were not significantly different in the replication cohort. However, the minor allele frequency of rs2930961 was significantly different in hyperandrogenism of PCOS. After meta-analysis by combining the results of these two studies, there was a non-significant trend for the association of rs2930961 (RAD54B) with PCOS. RAD54B and GREB1 gene polymorphisms may not be associated with PCOS in the Han Chinese population. Nevertheless, RAD54B may contribute to hyperandrogenism in PCOS patients.

Mohammed H, D'Santos C, Serandour AA, et al.
Endogenous purification reveals GREB1 as a key estrogen receptor regulatory factor.
Cell Rep. 2013; 3(2):342-9 [PubMed] Related Publications
Estrogen receptor-α (ER) is the driving transcription factor in most breast cancers, and its associated proteins can influence drug response, but direct methods for identifying interacting proteins have been limited. We purified endogenous ER using an approach termed RIME (rapid immunoprecipitation mass spectrometry of endogenous proteins) and discovered the interactome under agonist- and antagonist-liganded conditions in breast cancer cells, revealing transcriptional networks in breast cancer. The most estrogen-enriched ER interactor is GREB1, a potential clinical biomarker with no known function. GREB1 is shown to be a chromatin-bound ER coactivator and is essential for ER-mediated transcription, because it stabilizes interactions between ER and additional cofactors. We show a GREB1-ER interaction in three xenograft tumors, and using a directed protein-protein approach, we find GREB1-ER interactions in half of ER(+) primary breast cancers. This finding is supported by histological expression of GREB1, which shows that GREB1 is expressed in half of ER(+) cancers, and predicts good clinical outcome. These findings reveal an unexpected role for GREB1 as an estrogen-specific ER cofactor that is expressed in drug-sensitive contexts.

Haynes BP, Viale G, Galimberti V, et al.
Expression of key oestrogen-regulated genes differs substantially across the menstrual cycle in oestrogen receptor-positive primary breast cancer.
Breast Cancer Res Treat. 2013; 138(1):157-65 [PubMed] Related Publications
Plasma estradiol (E2) and progesterone vary markedly through the menstrual cycle. Data on whether these differences in hormone levels affect gene expression in oestrogen receptor-positive (ER+) tumours are inconsistent. We wished to determine whether there are substantial changes in the expression of oestrogen-regulated genes (ERGs) in ER+ breast cancer through the menstrual cycle. One hundred and seventy five paraffin-embedded ER+ breast carcinomas from premenopausal patients were analysed. Timing of the ovarian cycle was confirmed using serum progesterone levels. Patients were ascribed to one of three pre-defined menstrual cycle windows: 1 (days 27-35 + 1-6), 2 (days 7-16) and 3 (days 17-26). The RNA expression of ESR1, four ERGs (PGR, GREB1, TFF1 and PDZK1), and three proliferation genes (MKI67, TOP2A and CDC20) were compared between the windows. Gene expression of the four ERGs was 53-129 % higher in window 2 than window 1 (p = 0.0013, 0.0006, 0.022 and 0.066 for PGR, GREB1, TFF1 and PDZK1, respectively) and lower (9-41 %) in window 3 compared to window 2 (p = 0.079, 0.31, 0.031 and 0.065 for PGR, GREB1, TFF1 and PDZK1, respectively). Their average expression (AvERG) was 64 % higher in window 2 than window 1 (p < 0.0001) and 21 % lower in window 3 than window 2 (p = 0.0043). There were no significant differences between the windows for ESR1 and proliferation genes. In agreement with the gene expression data, progesterone receptor protein levels measured by immunohistochemistry (IHC) were 164 and 227 % higher in windows 2 and 3, respectively, compared to window 1 (30.7 and 37.9 % cells positive vs. 11.6 %; p = 0.0003 and 0.0004, respectively), while no difference in ER IHC score was observed. In conclusion, we observed significant differences in the expression of ERGs in ER+ breast tumours across the menstrual cycle. This variability may affect the interpretation of gene expression profiles incorporating ERGs and may be exploitable as an endogenous test of endocrine responsiveness.

Liu M, Fan J, Wang S, et al.
Transcriptional profiling of Chinese medicinal formula Si-Wu-Tang on breast cancer cells reveals phytoestrogenic activity.
BMC Complement Altern Med. 2013; 13:11 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Si-Wu-Tang (SWT), comprising the combination of four herbs, Paeoniae, Angelicae, Chuanxiong and Rehmanniae, is one of the most popular traditional oriental medicines for women's diseases. In our previous study, the microarray gene expression profiles of SWT on breast cancer cell line MCF-7 were found similar to the effect of β-estradiol (E2) on MCF-7 cells in the Connectivity Map database.
METHODS: Further data analysis was conducted to find the main similarities and differences between the effects of SWT and E2 on MCF-7 gene expression. The cell proliferation assay on MCF-7 (ER-positive) and MDA-MB-231 (ER-negative) cells were used to examine such estrogenic activity. The estrogenic potency of SWT was further confirmed by estrogen-responsive element (ERE) luciferase reporter assay in MCF-7 cells.
RESULTS: Many estrogen regulated genes strongly up-regulated by E2 were similarly up-regulated by SWT, e.g., GREB1, PGR and EGR3. Of interest with regard to safety of SWT, the oncogenes MYBL1 and RET were strongly induced by E2 but not by SWT. Quantitative RT-PCR analysis revealed a highly concordant expression change in selected genes with data obtained by microarrays. Further supporting SWT's estrogenic activity, in MCF-7 but not in MDA-MB-231 cells, SWT stimulated cell growth at lower concentrations (< 3.0 mg/ml), while at high concentrations, it inhibits the growth of both cell lines. The growth inhibitory potency of SWT was significantly higher in MDA-MB-231 than in MCF-7 cells. The SWT-induced cell growth of MCF-7 could be blocked by addition of the estrogen receptor antagonist tamoxifen. In addition, SWT was able to activate the ERE activity at lower concentrations. The herbal components Angelicae, Chuanxiong and Rehmanniae at lower concentrations (< 3.0 mg/ml) also showed growth-inducing and ERE-activating activity in MCF-7 cells.
CONCLUSIONS: These results revealed a new mechanism to support the clinical use of SWT for estrogen related diseases and possibly for cancer prevention. This study also demonstrated the feasibility of using microarray transcriptional profiling to discover phytoestrogenic components that are present in natural products.

Ferreira LB, Palumbo A, de Mello KD, et al.
PCA3 noncoding RNA is involved in the control of prostate-cancer cell survival and modulates androgen receptor signaling.
BMC Cancer. 2012; 12:507 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: PCA3 is a non-coding RNA (ncRNA) that is highly expressed in prostate cancer (PCa) cells, but its functional role is unknown. To investigate its putative function in PCa biology, we used gene expression knockdown by small interference RNA, and also analyzed its involvement in androgen receptor (AR) signaling.
METHODS: LNCaP and PC3 cells were used as in vitro models for these functional assays, and three different siRNA sequences were specifically designed to target PCA3 exon 4. Transfected cells were analyzed by real-time qRT-PCR and cell growth, viability, and apoptosis assays. Associations between PCA3 and the androgen-receptor (AR) signaling pathway were investigated by treating LNCaP cells with 100 nM dihydrotestosterone (DHT) and with its antagonist (flutamide), and analyzing the expression of some AR-modulated genes (TMPRSS2, NDRG1, GREB1, PSA, AR, FGF8, CdK1, CdK2 and PMEPA1). PCA3 expression levels were investigated in different cell compartments by using differential centrifugation and qRT-PCR.
RESULTS: LNCaP siPCA3-transfected cells significantly inhibited cell growth and viability, and increased the proportion of cells in the sub G0/G1 phase of the cell cycle and the percentage of pyknotic nuclei, compared to those transfected with scramble siRNA (siSCr)-transfected cells. DHT-treated LNCaP cells induced a significant upregulation of PCA3 expression, which was reversed by flutamide. In siPCA3/LNCaP-transfected cells, the expression of AR target genes was downregulated compared to siSCr-transfected cells. The siPCA3 transfection also counteracted DHT stimulatory effects on the AR signaling cascade, significantly downregulating expression of the AR target gene. Analysis of PCA3 expression in different cell compartments provided evidence that the main functional roles of PCA3 occur in the nuclei and microsomal cell fractions.
CONCLUSIONS: Our findings suggest that the ncRNA PCA3 is involved in the control of PCa cell survival, in part through modulating AR signaling, which may raise new possibilities of using PCA3 knockdown as an additional therapeutic strategy for PCa control.

Liu M, Wang G, Gomez-Fernandez CR, Guo S
GREB1 functions as a growth promoter and is modulated by IL6/STAT3 in breast cancer.
PLoS One. 2012; 7(10):e46410 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Growth Regulation by Estrogen in Breast cancer (GREB1) was an estrogen receptor (ER) target gene, and GREB1 expression inversely correlated with HER2 status, possibly as a surrogate marker for ER status and a predictor for tamoxifen resistance in breast cancer patients. In the present study, we examine the function and regulation of GREB1 in breast cancer, with the goal to develop GREB1 as a biomarker in breast cancer with de novo and acquired tamoxifen resistance.
METHODS: We overexpressed GREB1 using adenovirus containing the full length GREB1 cDNA (Ad-GREB1) in breast cancer cell lines. The soft agar assay was used as a measure of anchorage independent growth. The effects of GREB1 on cell proliferation in MCF-7 cells transduced with Ad-GREB1 were also measured by the me olic activity using AlamarBlue assay. We tested whether there was interaction between STAT3 and ER, which could repress GREB1 expression by immunoprecipitation assay. The effects of IL-6/JAK/STAT3 cascade activation on estrogen-induced GREB1 promoter activity were determined by luciferase assay and those on gene expression were measured by real time reverse transcription polymerase chain reaction (qRT-PCR).
RESULTS: We found that the ability of breast cancer cells to grow in soft agar is enhanced following GREB1 transfection. In MCF-7 cells transduced with Ad-GREB1 or transfected with siRNA GREB1, the metabolic activity was increased or completely abolished, suggesting that GREB1 may function as a growth promoter in breast cancer. E2 treatment increased GREB1 promoter luciferase activity. IL-6 inhibited E2-induced GREB1 transcription activity and GREB1 mRNA expression. Constitutively expressing active STAT3 construct (STAT3-C) dramatically decreased GREB1 transcription.
CONCLUSIONS: These data indicate that overexpression of GREB1 promotes cell proliferation and increases the clonogenic ability in breast cancer cells. Moreover, Il6/STAT3 modulates estrogen-induced GREB1 transcriptional activity in breast cancer cells.

Weigel MT, Ghazoui Z, Dunbier A, et al.
Preclinical and clinical studies of estrogen deprivation support the PDGF/Abl pathway as a novel therapeutic target for overcoming endocrine resistance in breast cancer.
Breast Cancer Res. 2012; 14(3):R78 [PubMed] Free Access to Full Article Related Publications
INTRODUCTION: The majority of breast tumors at primary diagnosis are estrogen receptor positive (ER+). Estrogen (E) mediates its effects by binding to the ER. Therapies targeting the estrogenic stimulation of tumor growth reduce mortality from ER+ breast cancer. However, resistance remains a major clinical problem.
METHODS: To identify molecular mechanisms associated with resistance to E-deprivation, we assessed the temporal changes in global gene expression during adaptation to long-term culture of MCF7 human breast cancer cells in the absence of estradiol (E2), long term estrogen deprived (LTED), that leads to recovery of proliferative status and models resistance to an aromatase inhibitor (AI). The expression levels of proteins were determined by western blotting. Proliferation assays were carried out using the dual platelet derived growth factor receptor (PDGFR)/Abelson tyrosine kinase (Abl) inhibitor nilotinib. Luciferase reporter assays were used to determine effects on ER-mediated transactivation. Changes in recruitment of cofactors to the gene regulated by estrogen in breast cancer 1 (GREB1) promoter were determined by chromatin immunoprecipitation (ChIP). Gene expression data were derived from 81 postmenopausal women with ER+ BC pre-treatment and at two-weeks post-treatment with single agent anastrozole in a neoadjuvant trial.
RESULTS: The PDGF/Abl canonical pathway was significantly elevated as early as one week post E-deprivation (P = 1.94 E-04) and this became the top adaptive pathway at the point of proliferative recovery (P = 1.15 E-07). Both PDGFRβ and Abl protein levels were elevated in the LTED cells compared to wild type (wt)-MCF7 cells. The PDGF/Abl tyrosine kinase inhibitor nilotinib, suppressed proliferation in LTED cells in the presence or absence of E. Nilotinib also suppressed ER-mediated transcription by destabilizing the ER and reducing recruitment of amplified in breast cancer-1 (AIB1) and the CREB binding protein (CBP) to the promoter of the E-responsive gene GREB1. High PDGFRβ in primary ER+ breast cancer of 81 patients prior to neoadjuvant treatment with an AI was associated with poorer antiproliferative response. Additionally PDGFRβ expression increased after two weeks of AI therapy (1.25 fold, P = 0.003).
CONCLUSIONS: These preclinical and clinical data indicate that the PDGF/Abl signaling pathway merits clinical evaluation as a therapeutic target with endocrine therapy in ER+ breast cancer.

Chand AL, Wijayakumara DD, Knower KC, et al.
The orphan nuclear receptor LRH-1 and ERα activate GREB1 expression to induce breast cancer cell proliferation.
PLoS One. 2012; 7(2):e31593 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Liver Receptor Homolog 1 (LRH-1, NR5A2) is an orphan nuclear receptor that is over-expressed in cancers in tissues such as the breast, colon and pancreas. LRH-1 plays important roles in embryonic development, steroidogenesis and cholesterol homeostasis. In tumor cells, LRH-1 induces proliferation and cell cycle progression. High LRH-1 expression is demonstrated in breast cancers, positively correlating with ERα status and aromatase activity. LRH-1 dependent cellular mechanisms in breast cancer epithelial cells are poorly defined. Hence in the present study we investigated the actions of LRH-1 in estrogen receptor α (ERα) positive breast cancer cells.
RESULTS: The study aimed to investigate LRH-1 dependent mechanisms that promote breast cancer proliferation. We identified that LRH-1 regulated the expression of Growth Regulation by Estrogen in Breast Cancer 1 (GREB1) in MCF-7 and MDA-MB-231 cells. Over-expression of LRH-1 increased GREB1 mRNA levels while knockdown of LRH-1 reduced its expression. GREB1 is a well characterised ERα target gene, with three estrogen response elements (ERE) located on its promoter. Chromatin immunoprecipitation studies provided evidence of the co-localisation of LRH-1 and ERα at all three EREs. With electrophoretic mobility shift assays, we demonstrated direct binding of LRH-1 to EREs located on GREB1 and Trefoil Factor 1 (TFF1, pS2) promoters. LRH-1 and ERα co-operatively activated transcription of ERE luciferase reporter constructs suggesting an overlap in regulation of target genes in breast cancer cells. Over-expression of LRH-1 resulted in an increase in cell proliferation. This effect was more pronounced with estradiol treatment. In the presence of ICI 182,780, an ERα antagonist, LRH-1 still induced proliferation.
CONCLUSIONS: We conclude that in ER-positive breast cancer cells, LRH-1 promotes cell proliferation by enhancing ERα mediated transcription of target genes such as GREB-1. Collectively these findings indicate the importance of LRH-1 in the progression of hormone-dependent breast cancer and implicate LRH-1 as a potential avenue for drug development.

Liu J, Welm B, Boucher KM, et al.
TRIM29 functions as a tumor suppressor in nontumorigenic breast cells and invasive ER+ breast cancer.
Am J Pathol. 2012; 180(2):839-47 [PubMed] Related Publications
Tripartite motif-containing 29 (TRIM29) is a member of the TRIM protein family that has been implicated in hematologic and solid tumor cancers. We found that TRIM29 functions as a tumor suppressor in both the nontumorigenic MCF10A [estrogen receptor (ER)-/TRIM29+] breast cell line and the invasive MCF7 (ER+/TRIM29-) breast cell line. Silencing TRIM29 in MCF10A cells resulted in preneoplastic changes that included loss of polarity in three-dimensional culture, increased proliferation, anchorage-independent growth, and increased migration and invasion. Conversely, the introduction of TRIM29 into MCF7 cells caused reversion to a less aggressive phenotype by antagonizing the growth effect of 17β-estradiol. The interaction between TRIM29 and ER signaling in MCF7 cells was supported by a reduction in ERE binding in the presence of TRIM29 and suppression of ER-dependent gene expression of TFF1, FOS, and GREB1. By microarray analyses, we showed that younger women (<55 years of age) with early-stage, ER+ breast cancer who were given no adjuvant systemic therapy had a significantly lower risk of relapse when their tumor had high TRIM29 expression (P = 0.02). This effect was not observed in older women (>55 years of age) and thus may be due to menopause and loss of circulating estrogens. Our results suggest that loss of TRIM29 expression in normal breast luminal cells can contribute to malignant transformation and lead to progression of ER+ breast cancer in premenopausal women.

Haakensen VD, Bjøro T, Lüders T, et al.
Serum estradiol levels associated with specific gene expression patterns in normal breast tissue and in breast carcinomas.
BMC Cancer. 2011; 11:332 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: High serum levels of estradiol are associated with increased risk of postmenopausal breast cancer. Little is known about the gene expression in normal breast tissue in relation to levels of circulating serum estradiol.
METHODS: We compared whole genome expression data of breast tissue samples with serum hormone levels using data from 79 healthy women and 64 breast cancer patients. Significance analysis of microarrays (SAM) was used to identify differentially expressed genes and multivariate linear regression was used to identify independent associations.
RESULTS: Six genes (SCGB3A1, RSPO1, TLN2, SLITRK4, DCLK1, PTGS1) were found differentially expressed according to serum estradiol levels (FDR = 0). Three of these independently predicted estradiol levels in a multivariate model, as SCGB3A1 (HIN1) and TLN2 were up-regulated and PTGS1 (COX1) was down-regulated in breast samples from women with high serum estradiol. Serum estradiol, but none of the differentially expressed genes were significantly associated with mammographic density, another strong breast cancer risk factor. In breast carcinomas, expression of GREB1 and AREG was associated with serum estradiol in all cancers and in the subgroup of estrogen receptor positive cases.
CONCLUSIONS: We have identified genes associated with serum estradiol levels in normal breast tissue and in breast carcinomas. SCGB3A1 is a suggested tumor suppressor gene that inhibits cell growth and invasion and is methylated and down-regulated in many epithelial cancers. Our findings indicate this gene as an important inhibitor of breast cell proliferation in healthy women with high estradiol levels. In the breast, this gene is expressed in luminal cells only and is methylated in non-BRCA-related breast cancers. The possibility of a carcinogenic contribution of silencing of this gene for luminal, but not basal-like cancers should be further explored. PTGS1 induces prostaglandin E2 (PGE2) production which in turn stimulates aromatase expression and hence increases the local production of estradiol. This is the first report studying such associations in normal breast tissue in humans.

Bauerschlag DO, Ammerpohl O, Bräutigam K, et al.
Progression-free survival in ovarian cancer is reflected in epigenetic DNA methylation profiles.
Oncology. 2011; 80(1-2):12-20 [PubMed] Related Publications
OBJECTIVE: Many patients with ovarian cancer disease relapse within 6 months after adjuvant chemotherapy, with a limited prognosis. Epigenetic modifications have been shown to play an important role in tumor development and formation. Therefore, global analysis of DNA methylation patterns might reveal specific CpG sites that correlate with progression-free interval (PFI) after therapy.
METHODS: Twenty samples of advanced ovarian cancer with a predominantly serous papillary histological subtype were subjected to DNA methylation profiling. Illumina HumanMethylation27 BeadChip technology was used for simultaneous analysis of 27,578 CpG sites in >14,000 genes.
RESULTS: Differential DNA methylation of various cytosines correlated with PFI. However, this becomes only significant by classification according to PFI with a cutoff of >28 months. Longer survival was associated with hypomethylation at specific CpG sites (e.g. GREB1, TGIF and TOB1) and hypermethylation in other genes (e.g. TMCO5, PTPRN and GUCY2C). Gene ontology analysis revealed that differentially methylated genes were significantly overrepresented in the categories telomere organization, mesoderm development and immune regulation.
CONCLUSION: Epigenetic modifications at specific CpG sites correlate with PFI in ovarian cancer. Therefore, such analysis might be of prognostic value.

Englert NA, Spink BC, Spink DC
Persistent and non-persistent changes in gene expression result from long-term estrogen exposure of MCF-7 breast cancer cells.
J Steroid Biochem Mol Biol. 2011; 123(3-5):140-50 [PubMed] Related Publications
Life-long estrogen exposure is recognized as a major risk factor for the development of breast cancer. While the initial events in the regulation of gene expression by estrogen have been described in detail, far less is known of the role of estrogen in the long-term regulation of gene expression. In this study, we investigated the effects of long-term exposure of MCF-7 breast cancer cells to 1nM 17β-estradiol on gene expression with the goal of distinguishing between gene expression that is continually reliant on estrogen receptor (ER) function as opposed to secondary and persistent effects that are downstream of ER. To assess the direct involvement of ER in the differential gene expression of long-term estrogen exposed (LTEE) cells in comparison with that of control cells, we exposed cultures to the selective estrogen receptor modulator raloxifene (RAL). cDNA microarray analysis showed that exposure to RAL inhibited expression of numerous characterized estrogen-regulated genes, including PGR, GREB1, and PDZK1. Genes that were increased in expression in LTEE cells yet were unaffected by RAL exposure included the aryl hydrocarbon receptor (AHR) and numerous other genes that were not previously reported to be regulated by estrogen. Epigenetic regulation was evident for the AHR gene; AhR transcript levels remained elevated for several cell passages after the removal of estrogen. Signal transducer and activator of transcription 1 (STAT1); STAT1-regulated genes including ISG15, IFI27, and IFIT1; and MHC class I genes were also up-regulated in LTEE cells and were unaffected by RAL exposure. STAT1 is commonly overexpressed in breast and other cancers, and is associated with increased resistance to radiation and chemotherapy. This is the first study to relate estrogen exposure to increased STAT1 expression in breast cancer cells, an effect that may represent an additional role of estrogen in the pathogenesis of breast cancer.

Macpherson L, Matthews J
Inhibition of aryl hydrocarbon receptor-dependent transcription by resveratrol or kaempferol is independent of estrogen receptor α expression in human breast cancer cells.
Cancer Lett. 2010; 299(2):119-29 [PubMed] Related Publications
Resveratrol and kaempferol are natural chemopreventative agents that are also aryl hydrocarbon receptor (AHR) antagonists and estrogen receptor (ER) agonists. In this study we evaluated the role of ERα in resveratrol- and kaempferol-mediated inhibition of AHR-dependent transcription. Kaempferol or resveratrol inhibited dioxin-induced cytochrome P450 1A1 (CYP1A1) and CYP1B1 expression levels and recruitment of AHR, ERα and co-activators to CYP1A1 and CYP1B1. Both phytochemicals induced the expression and recruitment of ERα to gene amplified in breast cancer 1 (GREB1). RNAi-mediated knockdown of ERα in T-47D cells did not affect the inhibitory action of either phytochemical on AHR activity. Both compounds also inhibited AHR-dependent transcription in ERα-negative MDA-MB-231 and BT-549 breast cancer cells. These data show that ERα does not contribute to the AHR-inhibitory activities of resveratrol and kaempferol.

Woodfield GW, Chen Y, Bair TB, et al.
Identification of primary gene targets of TFAP2C in hormone responsive breast carcinoma cells.
Genes Chromosomes Cancer. 2010; 49(10):948-62 [PubMed] Free Access to Full Article Related Publications
The TFAP2C transcription factor is involved in mammary development, differentiation, and oncogenesis. Previous studies established a role for TFAP2C in the regulation of ESR1 (ERalpha) and ERBB2 (Her2) in breast carcinomas. However, the role of TFAP2C in different breast cancer phenotypes has not been examined in detail. To develop a more complete characterization of TFAP2C target genes, ChIP-seq with anti-TFAP2C antibody and expression arrays with TFAP2C knock down were analyzed in MCF-7 breast carcinoma cells. Genomic sequences common to the ChIP-seq data set defined the consensus sequence for TFAP2C chromatin binding as the nine base sequence SCCTSRGGS (S = G/C, r = A/G), which closely matches the previously defined optimal in vitro binding site. Comparing expression arrays before and after knock down of TFAP2C with ChIP-seq data demonstrated a conservative estimate that 8% of genes altered by TFAP2C expression are primary target genes and includes genes that are both induced and repressed by TFAP2C. A set of 447 primary target genes of TFAP2C was identified, which included ESR1 (ERalpha), FREM2, RET, FOXA1, WWOX, GREB1, MYC, and members of the retinoic acid response pathway. The identification of ESR1, WWOX, GREB1, and FOXA1 as primary targets confirmed the role of TFAP2C in hormone response. TFAP2C plays a critical role in gene regulation in hormone responsive breast cancer and its target genes are different than for the Her2 breast cancer phenotype.

Dunbier AK, Anderson H, Ghazoui Z, et al.
Relationship between plasma estradiol levels and estrogen-responsive gene expression in estrogen receptor-positive breast cancer in postmenopausal women.
J Clin Oncol. 2010; 28(7):1161-7 [PubMed] Free Access to Full Article Related Publications
PURPOSE To determine whether plasma estradiol (E2) levels are related to gene expression in estrogen receptor (ER)-positive breast cancers in postmenopausal women. Materials and METHODS Genome-wide RNA profiles were obtained from pretreatment core-cut tumor biopsies from 104 postmenopausal patients with primary ER-positive breast cancer treated with neoadjuvant anastrozole. Pretreatment plasma E2 levels were determined by highly sensitive radioimmunoassay. Genes were identified for which expression was correlated with pretreatment plasma E2 levels. Validation was performed in an independent set of 73 ER-positive breast cancers. Results The expression of many known estrogen-responsive genes and gene sets was highly significantly associated with plasma E2 levels (eg, TFF1/pS2, GREB1, PDZK1 and PGR; P < .005). Plasma E2 explained 27% of the average expression of these four average estrogen-responsive genes (ie, AvERG; r = 0.51; P < .0001), and a standardized mean of plasma E2 levels and ER transcript levels explained 37% (r, 0.61). These observations were validated in an independent set of 73 ER-positive tumors. Exploratory analysis suggested that addition of the nuclear coregulators in a multivariable analysis with ER and E2 levels might additionally improve the relationship with the AvERG. Plasma E2 and the standardized mean of E2 and ER were both significantly correlated with 2-week Ki67, a surrogate marker of clinical outcome (r = -0.179; P = .05; and r = -0.389; P = .0005, respectively). CONCLUSION Plasma E2 levels are significantly associated with gene expression of ER-positive breast cancers and should be considered in future genomic studies of ER-positive breast cancer. The AvERG is a new experimental tool for the study of putative estrogenic stimuli of breast cancer.

Antunes AA, Leite KR, Reis ST, et al.
GREB1 tissue expression is associated with organ-confined prostate cancer.
Urol Oncol. 2012 Jan-Feb; 30(1):16-20 [PubMed] Related Publications
OBJECTIVE: By reason of its heterogeneous behavior, it is difficult to determine the prognosis of many prostate cancer cases. Patients with the same clinicopathologic conditions may present varying clinical findings and rates of progression. We determined the role of new genes as potential molecular markers for prostate cancer prognosis.
MATERIALS AND METHODS: We performed a microarray analysis of two pools of patients with prostate cancer divided according to their clinicopathologic characteristics. After that, we validated these results by testing the genes with most different expressions between the two pools using the quantitative real time polymerase chain reaction method. We analyzed gene expression in 33 patients with localized prostate cancer according to prostate specific antigen (PSA), pathologic stage, Gleason score, and biochemical recurrence. For statistical analysis we used the Mann-Whitney Test.
RESULTS: The microarray analysis revealed that 4,147 genes presented a different expression between the two pools. Among them, 3 genes, TMEFF2, GREB1, and TH1L, were at least 13-times overexpressed, and 1 gene, IGH3, which was at least 5 times under-expressed in pool 1 (good prognosis) compared with pool 2 (bad prognosis), were selected for analysis. After the validation tests, GREB1 was significantly more overexpressed among patients with stage T2 compared with T3 (P = 0.020). The expressions of other 3 genes did not present significant differences according to the clinicopathological variables.
CONCLUSIONS: Tissue expression of GREB1 is associated with organ-confined prostate cancer and may constitute a gene associated with a favorable prognosis.

Hnatyszyn HJ, Liu M, Hilger A, et al.
Correlation of GREB1 mRNA with protein expression in breast cancer: validation of a novel GREB1 monoclonal antibody.
Breast Cancer Res Treat. 2010; 122(2):371-80 [PubMed] Related Publications
Studies of gene regulated by estrogen in breast cancer 1 (GREB1) have focused on mRNA levels with limited evidence about GREB1 protein expression in normal and breast cancer cells. A monoclonal antibody that recognizes GREB1 protein in breast tissues could be applied to correlate protein expression with established mRNA expression data. A hybridoma expressing a murine monoclonal antibody targeting a 119 amino acid peptide specific to human GREB1 was generated. The novel monoclonal GREB1 antibody (GREB1ab) was validated for use in Western blotting as well as immunohistochemical (IHC) applications. GREB1ab detects a 216 kDa protein corresponding to GREB1 in estrogen receptor alpha (ERalpha+) breast cancer cells as well as ERalpha- breast cancer cells transduced with a GREB1 expression vector. GREB1ab specificity was verified using an ERalpha antagonist to prevent GREB1 induction as well as a silencing siRNA targeting GREB1 mRNA. GREB1ab was further validated for detection of GREB1 by IHC in breast cancer cell lines and breast tissue microarrays (TMA). ERalpha+ cell lines were observed to express GREB1 while ERalpha- cell lines did not express detectable levels of the protein. Using breast cancer tissue whole sections, IHC with the GREB1ab identified protein expression in ERalpha+ breast cancer tissue as well as normal breast tissue, with little GREB1 expression in ERalpha- breast cancer tissue. Furthermore, these data indicate that GREB1 mRNA expression correlates well with protein expression. The novel monoclonal GREB1ab is specific for GREB1 protein. This antibody will serve as a tool for investigations focused on the expression, distribution, and function of GREB1 in normal breast and breast cancer tissues.

Hu C, Liu H, Du J, et al.
Estrogenic activities of extracts of Chinese licorice (Glycyrrhiza uralensis) root in MCF-7 breast cancer cells.
J Steroid Biochem Mol Biol. 2009; 113(3-5):209-16 [PubMed] Related Publications
Despite the wide use of Chinese licorice root (Glycyrrhiza uralensis) for the treatment of menopausal complaints, little is known on its potential estrogenic properties, and available information relative to its effects on cell proliferation is contradictory. In this study, the estrogenic properties of licorice root were evaluated in vitro by use of several assays. The effects of increasing concentrations of a DMSO extract of licorice root on the growth of MCF-7 breast cancer cells were biphasic. The extract showed an ER-dependent growth-promoting effect at low concentrations and an ER-independent anti-proliferative activity at high concentrations. In further experiments, licorice root was sequentially extracted to yield four fractions: hexane, EtOAc, methanol and H(2)O. Only the EtOAc extract had effects on cell proliferation similar to the DMSO extract. The hexane extract had no effect on cell growth. In contrast, the methanol and water extracts showed an ER-independent, growth-promoting effect. Similar to its effects on cell proliferation, the EtOAc extract had a biphasic effect on S phase cell cycle distribution and the level of PCNA protein. This extract-induced transactivation of endogenous ERalpha in MCF-7 cells, supported by inducing down-regulation of ERalpha protein and mRNA levels, and up-regulation of ERalpha target genes pS2 and GREB1. These results suggest that the activity of licorice root and the balance between increased risk for cancer and prevention of estrogen-dependent breast cancer may depend on the amount of dietary intake.

Antunes AA, Leite KR, Sousa-Canavez JM, et al.
The role of prostate specific membrane antigen and pepsinogen C tissue expression as an adjunctive method to prostate cancer diagnosis.
J Urol. 2009; 181(2):594-600 [PubMed] Related Publications
PURPOSE: The diagnosis of prostate cancer in men with persistently increased prostate specific antigen after a negative prostate biopsy has become a great challenge for urologists and pathologists. We analyzed the diagnostic value of 6 genes in the tissue of patients with prostate cancer.
MATERIALS AND METHODS: The study was comprised of 50 patients with localized disease who underwent radical prostatectomy. Gene selection was based on a previous microarray analysis. Among 4,147 genes with different expressions between 2 pools of patients 6 genes (PSMA, TMEFF2, GREB1, TH1L, IgH3 and PGC) were selected. These genes were tested for diagnostic value using the quantitative reverse transcription polymerase chain reaction method. Initially malignant tissue samples from 33 patients were analyzed and in the second part of the study we analyzed benign tissue samples from the other 17 patients with prostate cancer. The control group was comprised of tissue samples of patients with benign prostatic hyperplasia.
RESULTS: Analysis of malignant prostatic tissue demonstrated that prostate specific membrane antigen was over expressed (mean 9 times) and pepsinogen C was under expressed (mean 1.3 x 10(-4) times) in all cases compared to benign prostatic hyperplasia. The other 4 tested genes showed a variable expression pattern not allowing for differentiation between benign and malignant cases. When we tested these results in the benign prostate tissues from patients with cancer, pepsinogen C maintained the expression pattern. In terms of prostate specific membrane antigen, despite over expression in most cases (mean 12 times), 2 cases (12%) presented with under expression.
CONCLUSIONS: Pepsinogen C tissue expression may constitute a powerful adjunctive method to prostate biopsy in the diagnosis of prostate cancer cases.

Hu Q, Kwon YS, Nunez E, et al.
Enhancing nuclear receptor-induced transcription requires nuclear motor and LSD1-dependent gene networking in interchromatin granules.
Proc Natl Acad Sci U S A. 2008; 105(49):19199-204 [PubMed] Free Access to Full Article Related Publications
Although the role of liganded nuclear receptors in mediating coactivator/corepressor exchange is well-established, little is known about the potential regulation of chromosomal organization in the 3-dimensional space of the nucleus in achieving integrated transcriptional responses to diverse signaling events. Here, we report that ligand induces rapid interchromosomal interactions among specific subsets of estrogen receptor alpha-bound transcription units, with a dramatic reorganization of nuclear territories, which depends on the actions of nuclear actin/myosin-I machinery and dynein light chain 1. The histone lysine demethylase, LSD1, is required for these ligand-induced interactive loci to associate with distinct interchromatin granules, long thought to serve as "storage" sites for the splicing machinery, some critical transcription elongation factors, and various chromatin remodeling complexes. We demonstrate that this 2-step nuclear rearrangement is essential for achieving enhanced, coordinated transcription of nuclear receptor target genes.

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