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PAK1 is a breast cancer oncogene that coordinately activates MAPK and MET signaling

Y Shrestha1, E J Schafer, J S Boehm

  • 1Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA.

Oncogene
|November 23, 2011
PubMed

Insights

p21-activated kinase 1 (PAK1) amplification drives breast cancer by activating MAPK and MET signaling pathways. This discovery reveals PAK1 as a novel oncogene and a potential therapeutic target in breast cancer treatment.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cell Signaling

Background:

  • Activating mutations in RAS or BRAF are common in cancers but rare in breast tumors.
  • The Mitogen-Activated Protein Kinase (MAPK) pathway is frequently activated in breast cancer, suggesting alternative activation mechanisms.
  • Identifying novel oncogenes driving MAPK pathway activation is crucial for understanding breast cancer pathogenesis.

Purpose of the Study:

  • To identify novel breast cancer oncogenes that activate the MAPK pathway.
  • To investigate the role of p21-activated kinase 1 (PAK1) in breast cancer development.
  • To elucidate the signaling pathways regulated by PAK1 in malignant transformation.

Main Methods:

  • Screening a human kinase library for induction of anchorage-independent growth in immortalized human mammary epithelial cells (HMLE).
  • Assessing the necessity of PAK1 kinase activity for cellular transformation.
  • Investigating PAK1's simultaneous activation of MAPK and MET signaling pathways, including merlin inhibition.

Main Results:

  • p21-activated kinase 1 (PAK1) was identified as a kinase promoting anchorage-independent growth in HMLE cells.
  • PAK1 amplification was found in 30-33% of breast tumor samples and cell lines.
  • PAK1 kinase activity is essential for transformation and simultaneously activates MAPK and MET signaling by inhibiting merlin.

Conclusions:

  • PAK1 amplification represents an alternative mechanism for MAPK pathway activation in human breast cancer.
  • PAK1 functions as a breast cancer oncogene by coordinately regulating MAPK and MET signaling.
  • PAK1's dual pathway activation contributes to malignant transformation, highlighting its potential as a therapeutic target.

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