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STAT1 gene expression is enhanced by nuclear EGFR and HER2 via cooperation with STAT3

Woody Han1, Richard L Carpenter, Xinyu Cao

  • 1Division of Surgical Sciences, Department of Surgery, Duke University School of Medicine, Durham, North Carolina, 27710.

Molecular Carcinogenesis
|June 14, 2012
PubMed

Insights

Epidermal Growth Factor Receptor (EGFR) and HER2 signaling pathways regulate Signal Transducer and Activator of Transcription 1 (STAT1) expression. STAT3 synergizes with nuclear EGFR, EGFRvIII, and HER2 to enhance STAT1 expression, linking mitogenic and inflammatory pathways.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cell Signaling

Background:

  • Epidermal Growth Factor Receptor (EGFR) and Human Epidermal growth factor Receptor 2 (HER2) are key drivers of cancer development.
  • While known as plasma membrane receptors, their nuclear translocation and functional impact are not fully understood.
  • The Signal Transducer and Activator of Transcription 1 (STAT1) is a transcription factor involved in inflammatory responses.

Purpose of the Study:

  • To investigate the role of nuclear EGFR and HER2 in regulating STAT1 expression.
  • To elucidate the mechanism by which EGFR and HER2 influence STAT1, particularly in the context of cancer.
  • To explore the interplay between EGFR/HER2 signaling and the STAT3 transcription factor in STAT1 regulation.

Main Methods:

  • Analysis of STAT1 promoter activity in response to nuclear EGFR and STAT3.
  • Identification and characterization of STAT3-binding sites on the human STAT1 promoter.
  • Correlation studies of STAT1, EGFR, and phosphorylated STAT3 (p-STAT3) levels in human breast cancer cell lines.
  • Investigating STAT1 upregulation by HER2 and heregulin stimulation.

Main Results:

  • EGFR nuclear activity upregulates STAT1 expression.
  • STAT3 binds to the STAT1 promoter and synergizes with nuclear EGFR to enhance STAT1 gene expression.
  • Four functional STAT3-binding sites were identified in the STAT1 promoter, crucial for co-regulation by EGFR and STAT3.
  • Constitutively active EGFR variant (EGFRvIII) also cooperates with STAT3 to activate the STAT1 promoter.
  • STAT1 expression is positively associated with EGFR and p-STAT3 levels in breast cancer cells.
  • HER2 and heregulin stimulation transcriptionally upregulate STAT1 in breast cancer cells, further augmented by STAT3.

Conclusions:

  • Nuclear EGFR, EGFRvIII, and HER2 upregulate STAT1 expression.
  • STAT3 acts synergistically with these receptors to enhance STAT1 expression.
  • This study establishes a novel connection between the ErbB signaling pathway and the STAT1-mediated inflammatory pathway.
Keywords:
EGFREGFRvIIIHER2STAT1STAT3gene regulation

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