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An In Vitro Dormancy Model of Estrogen-sensitive Breast Cancer in the Bone Marrow: A Tool for Molecular Mechanism Studies and Hypothesis Generation
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An In Vitro Dormancy Model of Estrogen-sensitive Breast Cancer in the Bone Marrow: A Tool for Molecular Mechanism Studies and Hypothesis Generation

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AIB1 is a conduit for kinase-mediated growth factor signaling to the estrogen receptor

J Font de Mora1, M Brown

  • 1Department of Adult Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA.

Molecular and Cellular Biology
|June 24, 2000
PubMed

Insights

Growth factors impact estrogen receptor (ER) activity, crucial in breast cancer. This study shows mitogen-activated protein kinase (MAPK) enhances AIB1 coactivator activity, suggesting a key mechanism in estrogen signaling.

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Endocrinology

Background:

  • Estrogen receptor (ER) activity is modulated by growth factors, impacting normal physiology and breast cancer.
  • Growth factors activate ER ligand-independently via mitogen-activated protein kinase (MAPK) and ER phosphorylation.

Purpose of the Study:

  • To investigate the role of AIB1, a coactivator amplified in ER-positive breast cancers, in growth factor-mediated ER activity.
  • To determine if MAPK phosphorylation affects AIB1 transcriptional activity and its interaction with other proteins.

Main Methods:

  • In vivo and in vitro phosphorylation assays to assess AIB1 modification by MAPK.
  • Analysis of AIB1 transcriptional activity following MAPK activation.
  • Assessment of p300 recruitment and histone acetyltransferase activity.

Main Results:

  • AIB1 is a phosphoprotein in vivo and is phosphorylated by MAPK in vitro.
  • MAPK phosphorylation enhances the transcriptional activity of AIB1.
  • MAPK activation of AIB1 promotes the recruitment of p300 and its associated histone acetyltransferase activity.

Conclusions:

  • MAPK activation of the nuclear receptor coactivator AIB1 is a potential mechanism mediating growth factor modulation of estrogen action.
  • This finding highlights AIB1 as a potential therapeutic target in breast cancer.
  • Understanding this pathway provides insights into ER-positive breast cancer pathogenesis.

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