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ERK promotes tumorigenesis by inhibiting FOXO3a via MDM2-mediated degradation

Jer-Yen Yang1, Cong S Zong, Weiya Xia

  • 1Department of Molecular and Cellular Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.

Nature Cell Biology
|January 22, 2008
PubMed

Insights

The RAS-ERK pathway promotes tumor growth by phosphorylating and degrading FOXO3a via MDM2. A non-phosphorylated FOXO3a mutant inhibits proliferation, revealing a novel cancer pathway.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Oncology

Background:

  • The RAS-ERK pathway is crucial for cell differentiation, proliferation, and tumor progression.
  • Dysregulation of this pathway is implicated in various cancers.

Purpose of the Study:

  • To elucidate the molecular mechanism by which the RAS-ERK pathway regulates Forkhead box O 3a (FOXO3a).
  • To investigate the role of FOXO3a phosphorylation and degradation in tumorigenesis.

Main Methods:

  • Direct interaction and phosphorylation assays to study Erk and FOXO3a.
  • MDM2-mediated degradation studies using wild-type and mutant FOXO3a.
  • Cell proliferation and tumorigenicity assays.

Main Results:

  • Erk directly phosphorylates FOXO3a at specific serine residues (Ser294, Ser344, Ser425).
  • Phosphorylated FOXO3a undergoes MDM2-mediated degradation, promoting cell proliferation and tumorigenesis.
  • A non-phosphorylated FOXO3a mutant resists MDM2 interaction and degradation, inhibiting cell proliferation and tumorigenicity.

Conclusions:

  • The RAS-ERK pathway negatively regulates FOXO3a stability and function.
  • This novel pathway involving RAS-ERK, FOXO3a, and MDM2 is critical for controlling cell growth and tumorigenesis.

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