scholarly journals AKT Alters Genome-Wide Estrogen Receptor α Binding and Impacts Estrogen Signaling in Breast Cancer

2008 ◽  
Vol 28 (24) ◽  
pp. 7487-7503 ◽  
Author(s):  
Poornima Bhat-Nakshatri ◽  
Guohua Wang ◽  
Hitesh Appaiah ◽  
Nikhil Luktuke ◽  
Jason S. Carroll ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Binding Sites ◽  
Transforming Growth Factor ◽  
Cell Types ◽  
Estrogen Receptor Α ◽  
Estrogen Signaling ◽  
Primary Tumors ◽  
Genome Wide ◽  
Extracellular Signal

ABSTRACT Estrogen regulates several biological processes through estrogen receptor α (ERα) and ERβ. ERα-estrogen signaling is additionally controlled by extracellular signal activated kinases such as AKT. In this study, we analyzed the effect of AKT on genome-wide ERα binding in MCF-7 breast cancer cells. Parental and AKT-overexpressing cells displayed 4,349 and 4,359 ERα binding sites, respectively, with ∼60% overlap. In both cell types, ∼40% of estrogen-regulated genes associate with ERα binding sites; a similar percentage of estrogen-regulated genes are differentially expressed in two cell types. Based on pathway analysis, these differentially estrogen-regulated genes are linked to transforming growth factor β (TGF-β), NF-κB, and E2F pathways. Consistent with this, the two cell types responded differently to TGF-β treatment: parental cells, but not AKT-overexpressing cells, required estrogen to overcome growth inhibition. Combining the ERα DNA-binding pattern with gene expression data from primary tumors revealed specific effects of AKT on ERα binding and estrogen-regulated expression of genes that define prognostic subgroups and tamoxifen sensitivity of ERα-positive breast cancer. These results suggest a unique role of AKT in modulating estrogen signaling in ERα-positive breast cancers and highlights how extracellular signal activated kinases can change the landscape of transcription factor binding to the genome.

scholarly journals Genome-Wide Identification of Estrogen Receptor α-Binding Sites in Mouse Liver

2008 ◽  
Vol 22 (1) ◽  
pp. 10-22 ◽  
Author(s):  
Hui Gao ◽  
Susann Fält ◽  
Albin Sandelin ◽  
Jan-Åke Gustafsson ◽  
Karin Dahlman-Wright
Keyword(s):  
Estrogen Receptor ◽  
Binding Sites ◽  
Mouse Liver ◽  
Estrogen Receptor Α ◽  
Estrogen Signaling ◽  
Transcription Start ◽  
Expression Levels ◽  
Transcription Start Sites ◽  
Genome Wide ◽  
Binding Regions

Abstract We report the genome-wide identification of estrogen receptor α (ERα)-binding regions in mouse liver using a combination of chromatin immunoprecipitation and tiled microarrays that cover all nonrepetitive sequences in the mouse genome. This analysis identified 5568 ERα-binding regions. In agreement with what has previously been reported for human cell lines, many ERα-binding regions are located far away from transcription start sites; approximately 40% of ERα-binding regions are located within 10 kb of annotated transcription start sites. Almost 50% of ERα-binding regions overlap genes. The majority of ERα-binding regions lie in regions that are evolutionarily conserved between human and mouse. Motif-finding algorithms identified the estrogen response element, and variants thereof, together with binding sites for activator protein 1, basic-helix-loop-helix proteins, ETS proteins, and Forkhead proteins as the most common motifs present in identified ERα-binding regions. To correlate ERα binding to the promoter of specific genes, with changes in expression levels of the corresponding mRNAs, expression levels of selected mRNAs were assayed in livers 2, 4, and 6 h after treatment with ERα-selective agonist propyl pyrazole triol. Five of these eight selected genes, Shp, Stat3, Pdgds, Pck1, and Pdk4, all responded to propyl pyrazole triol after 4 h treatment. These results extend our previous studies using gene expression profiling to characterize estrogen signaling in mouse liver, by characterizing the first step in this signaling cascade, the binding of ERα to DNA in intact chromatin.

scholarly journals The first decade of estrogen receptor cistromics in breast cancer

2016 ◽  
Vol 229 (2) ◽  
pp. R43-R56 ◽  
Author(s):  
Koen D Flach ◽  
Wilbert Zwart
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Transcription Factor ◽  
Tiling Array ◽  
Estrogen Receptor Α ◽  
Sequencing Technologies ◽  
Hormone Receptor Positive ◽  
Genome Wide ◽  
A Genome ◽  
On Chip

The advent of genome-wide transcription factor profiling has revolutionized the field of breast cancer research. Estrogen receptor α (ERα), the major drug target in hormone receptor-positive breast cancer, has been known as a key transcriptional regulator in tumor progression for over 30 years. Even though this function of ERα is heavily exploited and widely accepted as an Achilles heel for hormonal breast cancer, only since the last decade we have been able to understand how this transcription factor is functioning on a genome-wide scale. Initial ChIP-on-chip (chromatin immunoprecipitation coupled with tiling array) analyses have taught us that ERα is an enhancer-associated factor binding to many thousands of sites throughout the human genome and revealed the identity of a number of directly interacting transcription factors that are essential for ERα action. More recently, with the development of massive parallel sequencing technologies and refinements thereof in sample processing, a genome-wide interrogation of ERα has become feasible and affordable with unprecedented data quality and richness. These studies have revealed numerous additional biological insights into ERα behavior in cell lines and especially in clinical specimens. Therefore, what have we actually learned during this first decade of cistromics in breast cancer and where may future developments in the field take us?

scholarly journals Increased expression of the estrogen receptor alpha, ESR1, in the tumors of breast cancer patients treated with trastuzumab.

2020 ◽  
Author(s):  
Shahan Mamoor
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Estrogen Receptor Alpha ◽  
Estrogen Receptor Α ◽  
Needle Aspiration ◽  
Breast Cancers ◽  
Breast Cancer Patients ◽  
Primary Tumors ◽  
Transcriptional Induction ◽  
Selection Of

Hormones function as growth factors, and estrogen provides growth signals to support and induce the proliferation of breast cancers (1-3). This is the basis of the use of endocrine therapies (4, 5) including tamoxifen and letrozole as first-line treatment for patients with breast cancer. We found through mining published microarray and multiplexed gene expression profiling datasets that the estrogen receptor α (ESR1) was among the genes most differentially expressed in the primary tumors and fine needle aspiration-isolated tumor cells of patients with breast cancer treated with trastuzumab. However, estrogen receptor α was expressed at higher rather than lower levels in the tumors of trastuzumab-treated patients. These data, obtained through blind, systems-level analysis of published microarray data (6-8), suggest that trastuzumab administration in patients with breast cancer is associated with transcriptional induction of the estrogen receptor or selection of tumor clones with high expression of ESR1.

scholarly journals miR-22 Inhibits Estrogen Signaling by Directly Targeting the Estrogen Receptor α mRNA

2009 ◽  
Vol 29 (13) ◽  
pp. 3783-3790 ◽  
Author(s):  
Deo Prakash Pandey ◽  
Didier Picard
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Breast Cancer Cells ◽  
Estrogen Receptor Α ◽  
Estrogen Signaling ◽  
Systematic Assessment ◽  
Small Noncoding Rnas ◽  
Evolutionarily Conserved ◽  
Target Sites

ABSTRACT Estrogen receptor α (ERα) is a ligand-regulated transcription factor with a broad range of physiological functions and one of the most important classifiers in breast cancer. MicroRNAs (miRNAs) are small noncoding RNAs that have emerged as important regulators of gene expression in a plethora of physiological and pathological processes. Upon binding the 3′ untranslated region (UTR) of target mRNAs, miRNAs typically reduce their stability and/or translation. The ERα mRNA has a long 3′ UTR of about 4.3 kb which has been reported to reduce mRNA stability and which bears evolutionarily conserved miRNA target sites, suggesting that it might be regulated by miRNAs. We have performed a comprehensive and systematic assessment of the regulatory role of all miRNAs that are predicted to target the 3′ UTR of the ERα mRNA. We found that miR-22 represses ERα expression most strongly and by directly targeting the ERα mRNA 3′ UTR. Of the three predicted miR-22 target sites in the 3′ UTR, the evolutionarily conserved one is the primary target. miR-22 overexpression leads to a reduction of ERα levels, at least in part by inducing mRNA degradation, and compromises estrogen signaling, as exemplified by its inhibitory impact on the ERα-dependent proliferation of breast cancer cells.

scholarly journals Research Resource: Enhanced Genome-Wide Occupancy of Estrogen Receptor α by the Cochaperone p23 in Breast Cancer Cells

2012 ◽  
Vol 26 (1) ◽  
pp. 194-202 ◽  
Author(s):  
Natalie E. Simpson ◽  
Jason Gertz ◽  
Keren Imberg ◽  
Richard M. Myers ◽  
Michael J. Garabedian
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Estrogen Receptor Α ◽  
Genome Wide
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