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Essential role of Stat3 in PI3K-induced oncogenic transformation

Jonathan R Hart1, Lujian Liao, John R Yates

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

Proceedings of the National Academy of Sciences of the United States of America
|July 27, 2011
PubMed

Insights

The PI3K pathway, specifically the p110α-H1047R mutant, activates Stat3 phosphorylation, crucial for cancer development. Inhibiting PI3K or Tec kinase blocks this activation, offering potential therapeutic strategies for cancer.

Area of Science:

  • Oncology
  • Molecular Biology
  • Signal Transduction

Background:

  • The PI3K/Akt pathway is frequently dysregulated in cancer.
  • Stat3 activation is implicated in various oncogenic processes.
  • Understanding the interplay between PI3K and Stat3 is critical for cancer therapy.

Purpose of the Study:

  • To investigate the role of PI3K, specifically the p110α-H1047R mutant, in Stat3 activation.
  • To identify the kinase(s) mediating PI3K-induced Stat3 phosphorylation.
  • To explore the therapeutic potential of targeting the PI3K-Stat3 axis in cancer.

Main Methods:

  • Utilized cells transformed with the p110α-H1047R PI3K mutant.
  • Employed specific inhibitors: GDC-0941 (PI3K inhibitor) and LFM-A13 (Tec kinase inhibitor).
  • Assessed Stat3 tyrosine phosphorylation levels via Western blotting and functional assays.

Main Results:

  • PI3K p110α-H1047R transformation increased Stat3 tyrosine phosphorylation.
  • Dominant-negative Stat3 interfered with PI3K-induced oncogenesis.
  • PI3K inhibition (GDC-0941) and Tec kinase inhibition (LFM-A13) reduced Stat3 phosphorylation.
  • Neither JAK (AG490) nor Src (Src-1) inhibitors affected Stat3 phosphorylation.
  • H1047R-transformed cells released a factor inducing Stat3 phosphorylation in normal cells.

Conclusions:

  • PI3K-mediated Stat3 activation is essential for PI3K-induced oncogenesis.
  • Tec kinase family members are key mediators of PI3K-induced Stat3 phosphorylation.
  • The PI3K-Stat3 signaling axis is a significant target in human cancers, with potential therapeutic implications.

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