Homo sapiens
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ABSTRACT:
PROVIDER: PRJNA98759 | ENA |
REPOSITORIES: ENA
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Project description:Gene expression profiling of invasive breast cancer events from the tamoxifen prevention trial validates low estrogen receptor mRNA level as the main determinant of tamoxifen resistance in estrogen receptor positive breast cancer. In NSABP Breast Cancer Prevention Trial (BCPT), tamoxifen reduced the incidence of estrogen receptor (ER) positive tumors but not estrogen receptor negative breast cancer. More importantly, only 69% of estrogen receptor positive tumors were prevented by tamoxifen. The ER positive tumors arising in tamoxifen arm provides an ideal clinical model for acquired tamoxifen resistance. Based on data from NSABP trial B14 which showed linear prediction of the degree of benefit from adjuvant tamoxifen by the levels of ESR1 mRNA coding for ER-alpha, we hypothesized a priori that level of ESR1 mRNA would be lower in ER positive tumors arising in tamoxifen arm compared to those in placebo arm of BCPT. Keywords: Gene expression profiling analysis
2011-12-08 | GSE12665 | GEO
Project description:Gene expression profiling of invasive breast cancer events from the tamoxifen prevention trial validates low estrogen receptor mRNA level as the main determinant of tamoxifen resistance in estrogen receptor positive breast cancer. In NSABP Breast Cancer Prevention Trial (BCPT), tamoxifen reduced the incidence of estrogen receptor (ER) positive tumors but not estrogen receptor negative breast cancer. More importantly, only 69% of estrogen receptor positive tumors were prevented by tamoxifen. The ER positive tumors arising in tamoxifen arm provides an ideal clinical model for acquired tamoxifen resistance. Based on data from NSABP trial B14 which showed linear prediction of the degree of benefit from adjuvant tamoxifen by the levels of ESR1 mRNA coding for ER-alpha, we hypothesized a priori that level of ESR1 mRNA would be lower in ER positive tumors arising in tamoxifen arm compared to those in placebo arm of BCPT. Keywords: Gene expression profiling analysis Formalin fixed paraffin embedded tumor blocks with enough tumor tissue for RNA extraction were available from 108 cases (69 from placebo arm and 39 from tamoxifen arm) of the 264 that experienced invasive breast cancer (175 in placebo arm and 89 in tamoxifen arm) in BCPT before unblindings . Central ER immunohistochemistry identified 84 of them as ER positive (57 from placebo arm and 27 from tamoxifen arm). A novel protocol was developed and used to obtain microarray gene expression profiling from the degraded or fragmented RNA extracted from formalin fixed paraffin blocks.Hybridization intensity data were compiled using Partek Genomic Suite. After quantile normalization, genes with mean intensity below 500 were filtred out, which left 7743 probes with informative data. Data were log2 transformed for statistical analysis.
2011-12-08 | E-GEOD-12665 | biostudies-arrayexpress
Project description:Estrogen Receptor-a (ER) is the key feature in the majority of breast cancers and ER binding to the genome correlates with the Forkhead protein FOXA1 (HNF3a), but mechanistic insight is lacking. We now show that FOXA1 is the defining factor that governs differential ER-chromatin interactions. We show that almost all ER-chromatin interactions and gene expression changes are dependent on the presence of FOXA1 and that FOXA1 dictates genome-wide chromatin accessibility. Furthermore, we show that CTCF is an upstream negative regulator of FOXA1-chromatin interactions. In ER responsive breast cancer cells, the dependency on FOXA1 for tamoxifen-ER activity is absolute and in tamoxifen resistant cells, ER binding occurs independently of ligand, but in a FOXA1 dependent manner. Importantly, expression of FOXA1 in non-breast cancer cells is sufficient to alter ER binding and response to endocrine treatment. As such, FOXA1 is the primary determinant that regulates estrogen-ER activity and endocrine response in breast cancer cells and is sufficient to program ER functionality in non-breast cancer contexts. breast cancer MCF-7 cell lines were treaated in the presence of Estrogen, Estrogen plus Tamoxifen, Tamoxifen or a vehicle. MCF-7 cells were hormone-depleted for 3 d and treated with 100 nM estrogen or 1 microM Tamoxifen for 6 h. There were four biological replicates for each of the four different groups.
2010-11-17 | E-GEOD-25314 | biostudies-arrayexpress
Project description:Purpose: Endocrine therapies, such as tamoxifen are commonly given to most patients with estrogen receptor (ER) alpha-positive breast carcinoma but are not indicated for persons with ERalpha-negative cancer. The factors responsible for response to tamoxifen in 5-10% of patients with ERalpha-negative tumors are not clear. The aim of the present study was to elucidate the biology and role of the second ER, ERbeta, in patients treated with adjuvant tamoxifen. Experimental Design: We investigated ERbeta by immunohistochemistry in 353 stage II primary breast tumors from patients treated with two years adjuvant tamoxifen, and generated gene expression profiles for a representative subset of 88 tumors. Results: ERbeta was associated with increased survival (distant disease-free survival, P=0.01; overall survival, P=0.22), and in particular within ERalpha-negative patients (P=0.003; P=0.04), but not in the ERalpha-positive subgroup (P=0.49; P=0.88). Lack of ERbeta conferred early relapse (hazard ratio, 14; 95% CI, 1.8-106; P=0.01) within the ERalpha-negative subgroup even after adjustment for other markers. ERalpha was an independent marker only within the ERbeta-negative tumors (hazard ratio, 0.44; 95% CI, 0.21-0.89; P=0.02). An ERbeta gene expression profile was identified and was markedly different from the ERalpha signature. Conclusion: Expression of ERbeta is an independent marker for favorable prognosis after adjuvant tamoxifen treatment in ERalpha-negative breast cancer patients, and involves a gene expression program distinct from ERalpha. These results may be highly clinically significant, because in the U.S. alone, approximately 10,000 women are diagnosed annually with ERalpha-negative/ERbeta-positive breast carcinoma and may benefit from adjuvant tamoxifen. Keywords: Disease state analysis
2007-04-01 | GSE6577 | GEO
Project description:We have previously demonstrated that endoxifen is the most important tamoxifen metabolite responsible for eliciting the anti-estrogenic effects of this drug in breast cancer cells expressing estrogen receptor-alpha. However, the relevance of estrogen receptor-beta in mediating endoxifen action has yet to be explored. Therefore, the goals of this study were to determine the differences in the global gene expression profiles elicited by estradiol treatment and endoxifen between parental MCF7 breast cancer cells (expressing estrogen receptor alpha only) and MCF7 cells stably expressing estrogen receptor beta. Total RNA was isolated from parental or estrogen-receptor beta expressing MCF7 cells following 24 hour treatments with either ethanol vehicle, 1nM 17-beta-estradiol or 1nM estradiol plus 40nM endoxifen. All studies were conducted in biological replicates of 2.
2011-02-18 | E-GEOD-27375 | biostudies-arrayexpress
Project description:We have utilized ChIPseq to identify the ER-beta cistrome in ER-beta expressing MDA-MB-231 triple negative breast cancer cells. ER-beta has been identified as a tumor suppressor in breast cancer and recent reports have demonstrated that ER-beta protein is detectable at moderate to high levels in approximately 30% of triple negative breast tumors. Increased expression of ER-beta in triple negative breast cancer has also been reported to be associated with improved recurrence-free survival. Treatment of ER-beta expressing triple negative breast cancer cells with estrogen, or the ER-beta selective agonist, LY500307, results in decreased cell proliferation, invasion and migration. To begin to identify the molecular mechanisms by which ER-beta elicits tumor suppressive effects in triple negative breast cancer, we performed ChIPseq studies and identified the genome-wide binding sites for ER-beta following exposure to 1nM estrogen or 10nM LY500307 for 3 hours. Over 28,000 and 10,000 unique ER-beta binding sites were identifed in response to these two ligands respectively. The top transcription factor motifs identified under both treatment conditions were estrogen response elements and AP1 response elements. The majority of ER-beta binding sites were found at enhancer regions located within introns or intergenic chromatin regions followed by gene promoters.
2018-08-23 | GSE108979 | GEO
Project description:We have previously demonstrated that endoxifen is the most important tamoxifen metabolite responsible for eliciting the anti-estrogenic effects of this drug in breast cancer cells expressing estrogen receptor-alpha. However, the relevance of estrogen receptor-beta in mediating endoxifen action has yet to be explored. Therefore, the goals of this study were to determine the differences in the global gene expression profiles elicited by estradiol treatment and endoxifen between parental MCF7 breast cancer cells (expressing estrogen receptor alpha only) and MCF7 cells stably expressing estrogen receptor beta.
2011-02-18 | GSE27375 | GEO
Project description:Estrogen Receptor-a (ER) is the key feature in the majority of breast cancers and ER binding to the genome correlates with the Forkhead protein FOXA1 (HNF3a), but mechanistic insight is lacking. We now show that FOXA1 is the defining factor that governs differential ER-chromatin interactions. We show that almost all ER-chromatin interactions and gene expression changes are dependent on the presence of FOXA1 and that FOXA1 dictates genome-wide chromatin accessibility. Furthermore, we show that CTCF is an upstream negative regulator of FOXA1-chromatin interactions. In ER responsive breast cancer cells, the dependency on FOXA1 for tamoxifen-ER activity is absolute and in tamoxifen resistant cells, ER binding occurs independently of ligand, but in a FOXA1 dependent manner. Importantly, expression of FOXA1 in non-breast cancer cells is sufficient to alter ER binding and response to endocrine treatment. As such, FOXA1 is the primary determinant that regulates estrogen-ER activity and endocrine response in breast cancer cells and is sufficient to program ER functionality in non-breast cancer contexts. FoxA1 silenced breast cancer MCF-7 cell lines or control siRNA in the presence of Estrogen or a vehicle. MCF-7 cells were hormone-depleted for 3 d and treated with 100 nM estrogen for 6 h. There were three biological replicates for each of the four different groups.
2010-11-17 | E-GEOD-25315 | biostudies-arrayexpress
Project description:One of the greatest advances in therapy of estrogen receptor positive breast cancer has been the development of endocrine therapy. More than two thirds of primary breast tumors express estrogen receptor alpha (ERα) and their growth is mainly dependent on estrogen receptor activity. Several therapeutic approaches have thus been designed to inhibit ER activity in breast tissue. Tamoxifen, a selective ER modulator, is one of the main treatment options for premenopausal women with advanced ER positive breast cancer, and has also become well established as adjuvant therapy in the early breast cancer setting (Davies et al., 2011; Group, 1998; Jaiyesimi et al., 1995). In contrast to tamoxifen, which in other tissues such as bone and endometrium, can exert partial agonistic activity (Braithwaite et al., 2003; Fisher et al., 1994; Pietras, 2006), the selective ER downregulator, fulvestrant, is a potent ER antagonist. Binding of fulvestrant to ER inhibits receptor dimerization and nuclear uptake, prevents estrogen-response element binding and accelerates ER degradation (Dauvois et al., 1993; Dowsett et al., 2005; Fawell et al., 1990; Wakeling et al., 1991). Fulvestrant is approved for treatment of postmenopausal women with advanced breast cancer who have relapsed or progressed on first-line endocrine therapy (Howell et al., 2002; Osborne et al., 2002; Robertson et al., 2003). Estrogen deprivation by treatment with aromatase inhibitors (such as letrozole, anastrozole or exemestane) which block synthesis of estrogens is another effective therapy option in postmenopausal women (Bonneterre et al., 2000; Cuzick et al., 2010; Dowsett et al., 2010; Mouridsen et al., 2001; Nabholtz et al., 2000). The large majority of patients with ER+ breast cancer experience an initial response to endocrine therapy, however, in many of these patients, the disease subsequently progresses and eventually anti-estrogen therapy ceases to have effect. Biomarkers predicting response to estrogen deprivation and new alternative treatments targeting the pathways supporting estrogen independent growth are therefore urgently needed (Patani and Martin, 2014; Patani et al., 2013). In order to understand how tumors respond to withdrawal of their main growth signal, a comparison of molecular features of tumor before and during endocrine therapy is necessary, and the fate of individual cancer cell sub-clones should be monitored. Since studies of cellular dynamics are very difficult to perform with clinical material, we made use of a patient derived, estrogen dependent, orthotopically growing luminal-like primary breast cancer xenograft model (PDX) (Bergamaschi et al., 2009; Huuse et al., 2012). This PDX model is a representative model for luminal breast cancers as the molecular characteristics, cellular heterogeneity and estrogen dependency of the primary tumor are retained over many passages. Functionally different subpopulations of cancer cells were previously defined by expression of the markers CD24 and SSEA-4 in this model (Skrbo et al., 2014), and it is therefore a suitable model for comparison of cellular and molecular effects of estrogen deprivation and ER-signaling inhibition. In this study, a quantitative MS-based proteomic analysis using SILAC and a label-free approach were performed, aiming to map changes in protein expression induced by endocrine therapy. Inhibition of ER-signaling seemed to induce CD24 and SSEA-4 expression on residual tumor cells. Proteomic analysis revealed overexpression of enzymes involved in TCA cycle, oxidative phosphorylation and fatty acid beta-oxidation following endocrine treatment when compared to untreated tumors. These results indicated possible reprogramming of cell metabolism and utilization of aerobic respiration, i.e. oxidative phosphorylation, in response to endocrine therapy.
2022-02-28 | PXD002352 | Pride
Project description:Estrogen Receptor-a (ER) is the key feature in the majority of breast cancers and ER binding to the genome correlates with the Forkhead protein FOXA1 (HNF3a), but mechanistic insight is lacking. We now show that FOXA1 is the defining factor that governs differential ER-chromatin interactions. We show that almost all ER-chromatin interactions and gene expression changes are dependent on the presence of FOXA1 and that FOXA1 dictates genome-wide chromatin accessibility. Furthermore, we show that CTCF is an upstream negative regulator of FOXA1-chromatin interactions. In ER responsive breast cancer cells, the dependency on FOXA1 for tamoxifen-ER activity is absolute and in tamoxifen resistant cells, ER binding occurs independently of ligand, but in a FOXA1 dependent manner. Importantly, expression of FOXA1 in non-breast cancer cells is sufficient to alter ER binding and response to endocrine treatment. As such, FOXA1 is the primary determinant that regulates estrogen-ER activity and endocrine response in breast cancer cells and is sufficient to program ER functionality in non-breast cancer contexts.
2010-11-17 | GSE25315 | GEO