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Adenovirus-mediated overexpression of p14(ARF) induces p53 and Bax-independent apoptosis

Philipp G Hemmati1, Bernhard Gillissen, Clarissa von Haefen

  • 1Department of Hematology, Oncology and Tumor Immunology, Charité-Campus Berlin-Buch, Humboldt University, Lindenberger Weg 80, 13125 Berlin-Buch, Germany.

Oncogene
|June 26, 2002
PubMed

Insights

The tumor suppressor p14(ARF) induces apoptosis independently of p53 and Bax. Its pro-apoptotic function is mediated by mitochondrial pathways, inhibited by Bcl-x(L), suggesting novel therapeutic targets in cancer.

Area of Science:

  • Molecular Biology
  • Oncology
  • Cell Biology

Background:

  • The human INK4a gene locus encodes tumor suppressors p16(INK4a) and p14(ARF), frequently inactivated in human cancers.
  • p16(INK4a) targets the Rb-cdk4/6-cyclin D pathway, while p14(ARF) functions often depend on p53.
  • Emerging evidence suggests p14(ARF) also mediates p53-independent apoptosis and cell cycle regulation.

Purpose of the Study:

  • To investigate the pro-apoptotic function of p14(ARF) in relation to functional p53.
  • To explore p14(ARF)-mediated apoptosis in cancer cells with varying p53 and Bax status.
  • To elucidate the signaling pathways involved in p14(ARF)-induced apoptosis.

Main Methods:

  • Construction of a replication-deficient adenoviral vector for p14(ARF) overexpression (Ad-p14(ARF)).
  • Apoptosis induction assays in various human cancer cell lines (osteosarcoma, colon, prostate) with different p53 and Bax genetic backgrounds.
  • Analysis of mitochondrial permeability transition, caspase activation, DNA fragmentation, and the effect of Bcl-2 family proteins.

Main Results:

  • Ad-p14(ARF) induced apoptosis in osteosarcoma, colon, and prostate cancer cells, irrespective of functional p53 or Bax.
  • p14(ARF) overexpression triggered mitochondrial pathway activation, including caspase activation and DNA fragmentation.
  • Bcl-x(L) overexpression significantly inhibited p14(ARF)-induced apoptosis, suggesting a Bcl-2-sensitive but Bax-independent mechanism.

Conclusions:

  • p14(ARF) can induce apoptosis through p53- and Bax-independent signaling pathways.
  • The mechanism involves activation of the mitochondrial apoptosis pathway.
  • p14(ARF) may activate an unknown pro-apoptotic factor sensitive to Bcl-2 inhibition, offering potential therapeutic avenues.

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