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Gain of interaction with IRS1 by p110α-helical domain mutants is crucial for their oncogenic functions

Yujun Hao1, Chao Wang, Bo Cao

  • 1Department of Genetics and Genome Sciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA.

Cancer Cell
|May 7, 2013
PubMed

Insights

The PIK3CA E545K mutation enables direct association with IRS1, a novel oncogenic pathway rewiring. Disrupting this interaction inhibits cancer cell growth and tumor progression.

Area of Science:

  • Oncology
  • Molecular Biology
  • Biochemistry

Background:

  • The PIK3CA gene, encoding the p110α subunit of phosphatidylinositol 3-kinase α (PI3Kα), is frequently mutated in human cancers.
  • Key mutation hotspots include E545K in the helical domain and H1047R in the kinase domain.

Purpose of the Study:

  • To investigate the differential signaling mechanisms of PIK3CA E545K and H1047R mutations.
  • To explore the potential of targeting the IRS1-p110α interaction for cancer therapy.

Main Methods:

  • Investigated protein-protein interactions using biochemical assays.
  • Assessed the impact of mutations on signaling pathways (e.g., AKT phosphorylation).
  • Utilized xenograft models and peptide-based inhibitors to evaluate therapeutic efficacy.

Main Results:

  • p110α E545K, unlike H1047R, directly associates with IRS1 independently of the p85 regulatory subunit.
  • This aberrant interaction rewires the PI3Kα signaling pathway.
  • Disruption of the IRS1-p110α E545K interaction destabilizes p110α, reduces AKT phosphorylation, and inhibits tumor growth in xenograft models.
  • A hydrocarbon-stapled peptide targeting this interaction demonstrated anti-tumor effects.

Conclusions:

  • The E545K mutation confers a unique oncogenic mechanism by enabling direct IRS1 binding.
  • Targeting the IRS1-p110α E545K interaction represents a promising therapeutic strategy for cancers harboring this mutation.

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