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Regulation of estrogen receptor-alpha expression by the tumor suppressor gene p53 in MCF-7 cells

S V Angeloni1, M B Martin, P Garcia-Morales

  • 1Centre for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.

The Journal of Endocrinology
|March 12, 2004
PubMed

Insights

The tumor suppressor p53 enhances estrogen receptor-alpha (ER alpha) expression in breast cancer cells. This occurs by increasing ER alpha gene transcription, independent of p53 DNA binding.

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Genetics

Background:

  • Estrogen receptor-alpha (ER alpha) is a key factor in breast cancer development and progression.
  • The tumor suppressor protein p53 plays a critical role in cellular regulation and cancer prevention.
  • Understanding the interplay between p53 and ER alpha is crucial for developing targeted breast cancer therapies.

Purpose of the Study:

  • To investigate the effect of p53 on ER alpha expression in MCF-7 human breast cancer cells.
  • To elucidate the molecular mechanisms by which p53 influences ER alpha gene expression.

Main Methods:

  • Utilized stable transfectants with antisense p53 to decrease p53 activity.
  • Employed transient transfection with wild-type p53 to overexpress the protein.
  • Assessed ER alpha protein levels via Western blotting.
  • Analyzed ER alpha gene transcription using deletion mutants of the ER alpha promoter and transfection assays with p53 mutants.

Main Results:

  • Decreased p53 activity led to reduced ER alpha protein expression.
  • Overexpression of p53 resulted in increased ER alpha protein levels.
  • p53 up-regulates ER alpha gene expression by enhancing transcription via elements upstream of promoter A.
  • The p53-mediated increase in ER alpha transcription is dependent on p53's interaction with other proteins, not its DNA-binding ability.

Conclusions:

  • p53 acts as a positive regulator of ER alpha expression in MCF-7 cells.
  • The mechanism involves transcriptional activation of the ER alpha gene.
  • p53's function in this context relies on protein-protein interactions rather than direct DNA binding.

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