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Rapamycin-mediated FOXO1 inactivation reduces the anticancer efficacy of rapamycin

Etienne Abdelnour-Berchtold1, Yannick Cerantola, Didier Roulin

  • 1Department of Visceral Surgery, University Hospital of Lausanne, Pavillon 3/CHUV, Av de Beaumont, 1011 Lausanne, Switzerland.

Anticancer Research
|April 16, 2010
PubMed
Abstract

Insights

Rapamycin

Area of Science:

  • Oncology
  • Molecular Biology
  • Cancer Signaling Pathways

Background:

  • Mammalian target of rapamycin (mTOR) inhibitors like rapamycin have limited cancer therapy success.
  • This is partly due to feedback activation of the phosphatidylinositol 3-kinase/Akt (PI3K/Akt) pathway.
  • The role of FOXO1 in this context requires further investigation.

Purpose of the Study:

  • To investigate the role of FOXO1, a downstream target of PI3K/Akt, in the anticancer effects of rapamycin.
  • To determine if modulating FOXO1 activity can enhance rapamycin's efficacy.

Main Methods:

  • Colon cancer cells were treated with rapamycin.
  • FOXO1 phosphorylation and cellular localization were analyzed using Western blot.
  • Cells expressing a constitutively active FOXO1 mutant were used to assess rapamycin's antiproliferative effects in vitro and in vivo.

Main Results:

  • Rapamycin treatment led to FOXO1 phosphorylation and cytoplasmic translocation, indicating inactivation.
  • Overexpression of an active FOXO1 mutant enhanced rapamycin's antiproliferative and antitumor effects.
  • Rapamycin-induced FOXO1 inactivation was shown to reduce rapamycin's overall antitumor efficacy.

Conclusions:

  • Rapamycin-induced inactivation of FOXO1 diminishes its anticancer efficacy.
  • Targeting FOXO1 may represent a strategy to improve rapamycin-based cancer therapies.

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