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Updated: Aug 15, 2026
16:24
Profiling of Estrogen-regulated MicroRNAs in Breast Cancer Cells
Published on: February 21, 2014
Altered target gene regulation controlled by estrogen receptor-alpha concentration
Amy M Fowler1, Natalia M Solodin, Christopher C Valley
1Department of Physiology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Molecular Endocrinology (Baltimore, Md.)
|September 24, 2005
Summary
High estrogen receptor-alpha (ERalpha) levels in breast cancer cells activate transcription of specific genes, bypassing normal estrogen signaling. This concentration-dependent ERalpha function reveals a novel regulatory mechanism.
Area of Science:
- Molecular Biology
- Endocrinology
- Cancer Research
Background:
- Estrogen receptor-alpha (ERalpha) is a key regulator of gene transcription.
- Elevated ERalpha levels in postmenopausal breast tumors are linked to poor outcomes.
- The impact of high ERalpha concentrations on its function remains unclear.
Purpose of the Study:
- To investigate whether high ERalpha concentrations alter transcriptional targets and activation mechanisms compared to estrogen-stimulated ERalpha.
- To identify specific residues and cofactors involved in concentration-dependent ERalpha activity.
Main Methods:
- Comparative analysis of gene expression profiles under high ERalpha concentration versus estrogen stimulation.
- Site-directed mutagenesis of ERalpha to assess the role of specific residues (Asp351, Leu372) and domains (AF-1, LBD).
- Investigation of coactivator recruitment (SRC-3) and interaction domain interference assays.
Main Results:
- High ERalpha concentrations led to transcriptional activation but not repression of estrogen-responsive genes.
- ERalpha at high levels activated the uterine-specific gene complement component 3.
- Activation function-1 and ligand-binding domain residues are crucial for concentration-dependent ERalpha activity, distinct from estrogen-induced mechanisms.
Conclusions:
- ERalpha concentration, not just ligand binding, dictates its transcriptional activity and target gene profile.
- A noncanonical activation mechanism, independent of SRC-3 and LxxLL motifs, operates at high ERalpha levels.
- These findings highlight receptor concentration as a critical factor in ERalpha-driven breast cancer progression.
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