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Updated: Oct 13, 2026

Detecting the Ligand-binding Domain Dimerization Activity of Estrogen Receptor Alpha Using the Mammalian Two-Hybrid Assay
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Cis element 'decoy' against the upstream promoter of the human estrogen receptor gene

L Penolazzi1, E Lambertini, G Aguiari

  • 1Dipartimento di Biochimica e Biologia Molecolare, Università degli Studi di Ferrara, Via L. Borsari, 46 44100, Ferrara, Italy.

Biochimica Et Biophysica Acta
|September 27, 2000
PubMed

Insights

Estrogen receptor (ER)-negative breast cancers lack ER gene expression. Researchers identified a specific DNA sequence that binds negative transcription factors, inhibiting ER gene expression in these cancers.

Area of Science:

  • Molecular Biology
  • Oncology
  • Genetics

Background:

  • Estrogen receptor (ER)-negative breast carcinomas are associated with poor prognosis and resistance to endocrine therapy.
  • The molecular mechanisms underlying the lack of ER gene expression in these tumors remain incompletely understood.
  • Identifying factors that regulate ER gene expression is crucial for developing targeted therapies.

Purpose of the Study:

  • To investigate the potential role of negative transcription factors in suppressing ER gene expression in ER-negative breast cancer cells.
  • To identify specific DNA sequences within the ER gene promoter that interact with these putative negative factors.
  • To explore the possibility of reactivating ER gene expression in ER-negative cells.

Main Methods:

  • Analysis of the P3 upstream promoter of the human ER gene.
  • Identification and characterization of a specific DNA sequence (-3258 to -3157) that binds proteins from ER-negative MDA-MB-231 cells.
  • Introduction of this DNA sequence as 'decoy' cis elements into ER-negative breast cancer cells.
  • Transient transfection assays using SV-40 promoted luciferase reporter.
  • Gel shift assays and Southwestern experiments to identify DNA-protein interactions and specific proteins.

Main Results:

  • A critical DNA sequence in the ER gene promoter (-3258 to -3157) was identified that binds protein factors present in ER-negative MDA-MB-231 cells.
  • This sequence was shown to inhibit ER gene transcription.
  • Introduction of the DNA sequence as a 'decoy' element reactivated ER gene transcription in ER-negative cells.
  • The identified sequence decreased SV-40 promoted luciferase activity in transfection assays.
  • Gel shift and Southwestern assays confirmed specific DNA-protein interactions and the presence of a protein unique to ER-negative MDA-MB-231 cells.

Conclusions:

  • A novel regulatory mechanism involving negative transcription factors and a specific DNA sequence in the ER gene promoter contributes to ER gene silencing in ER-negative breast cancer.
  • The identified 'decoy' cis element strategy shows potential for reactivating ER gene expression, offering a new therapeutic avenue for ER-negative breast cancers.

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