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Updated: Jun 11, 2026

Identification of Inositol Phosphate or Phosphoinositide Interacting Proteins by Affinity Chromatography Coupled to Western Blot or Mass Spectrometry
08:07

Identification of Inositol Phosphate or Phosphoinositide Interacting Proteins by Affinity Chromatography Coupled to Western Blot or Mass Spectrometry

Published on: July 26, 2019

Phosphatidylinositol 3-kinase: the oncoprotein

Peter K Vogt1, Jonathan R Hart, Marco Gymnopoulos

  • 1Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA. pkvogt@scripps.edu

Current Topics in Microbiology and Immunology
|June 29, 2010
PubMed

Insights

Class I phosphoinositide 3-kinase (PI3K) subunits are oncogenic, with mutations enhancing activity and driving cancer. The generated phosphoinositide 3,4,5 trisphosphate (PIP(3)) is crucial for this PI3K-mediated oncogenicity.

Area of Science:

  • Oncology
  • Molecular Biology
  • Biochemistry

Background:

  • Class I phosphoinositide 3-kinase (PI3K) subunits, p110α and p85, possess oncogenic potential.
  • Cancer-specific mutations in p110α and p85 lead to enhanced enzymatic activity, constitutive signaling, and oncogenicity.
  • Overexpression of wild-type p110 β, γ, and δ isoforms also promote cell transformation.

Purpose of the Study:

  • To investigate the role of phosphoinositide 3,4,5 trisphosphate (PIP(3)) in PI3K-mediated oncogenicity.
  • To elucidate the molecular mechanisms underlying gain-of-function mutations in p110α.
  • To identify essential downstream signaling pathways in PI3K-initiated oncogenesis.

Main Methods:

  • Analysis of cancer-specific mutations in PI3K subunits.
  • Genetic and cell biological studies to assess the role of PIP(3).
  • Mutational analysis to determine mechanisms of gain-of-function.
  • Investigation of the involvement of TOR (target of rapamycin) kinase signaling.

Main Results:

  • Class I PI3Ks generate PIP(3), which is essential for oncogenicity, explaining why Class II and III PI3Ks are not linked to cancer.
  • Two distinct molecular mechanisms for p110α gain-of-function mutations were identified: independence from receptor tyrosine kinases and Ras.
  • TOR kinase signaling, particularly TORC1-mediated cap-dependent translation, is an essential component of PI3K-initiated oncogenic signaling.

Conclusions:

  • Class I PI3Ks play a critical role in oncogenesis through PIP(3) production.
  • Understanding the specific mechanisms of PI3K mutations and their downstream targets like TOR is vital for cancer research.
  • Targeting PI3K/TOR signaling pathways may offer therapeutic strategies for cancers driven by PI3K activation.

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