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Bcl-2 is an apoptotic target suppressed by both c-Myc and E2F-1

C M Eischen1, G Packham, J Nip

  • 1Department of Biochemistry, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.

Oncogene
|November 13, 2001
PubMed

Insights

Oncogene overexpression, like c-Myc or E2F-1, triggers apoptosis by suppressing Bcl-2. Restoring Bcl-2 blocks this cell death, independent of the ARF/p53 pathway, revealing a key mechanism in cancer development.

Area of Science:

  • Cell Biology
  • Molecular Oncology
  • Cancer Research

Background:

  • Malignant transformation is linked to oncogenes such as c-Myc and E2F-1.
  • Apoptosis, or programmed cell death, is a critical process regulated by tumor suppressors like p53.
  • Immortalized myeloid cells (32D.3) lacking ARF show inactivated ARF/p53 apoptotic pathways.

Purpose of the Study:

  • To investigate the mechanism by which c-Myc and E2F-1 overexpression accelerate apoptosis in IL-3-deprived myeloid cells.
  • To determine the role of Bcl-2 in oncogene-induced apoptosis.
  • To elucidate the involvement of the ARF/p53 pathway in this process.

Main Methods:

  • Overexpression of c-Myc and E2F-1 in immortalized myeloid cells.
  • IL-3 deprivation to induce apoptosis.
  • Analysis of Bcl-2 protein and RNA levels.
  • Restoration of Bcl-2 expression.
  • Inactivation of p53 using mutant p53.
  • Engineering cells with c-Myc and E2F-1 DNA binding mutants.

Main Results:

  • c-Myc or E2F-1 overexpression suppressed Bcl-2 protein and RNA levels.
  • Restoration of Bcl-2 effectively blocked accelerated apoptosis.
  • Blocking p53 activity did not prevent E2F-1-induced Bcl-2 suppression.
  • DNA binding activity of c-Myc and E2F-1 was essential for Bcl-2 suppression.

Conclusions:

  • Targeting Bcl-2 family members is a significant mechanism of oncogene-induced apoptosis.
  • This Bcl-2 suppression occurs independently of the ARF/p53 apoptotic pathway.
  • Understanding this pathway is crucial for developing novel cancer therapies.

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