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Functional interplay between the DNA-damage-response kinase ATM and ARF tumour suppressor protein in human cancer

Georgia Velimezi1, Michalis Liontos, Konstantinos Vougas

  • 1Molecular Carcinogenesis Group, Department of Histology and Embryology, School of Medicine, University of Athens, 75 Mikras Asias Str, Athens, GR-11527, Greece.

Nature Cell Biology
|July 16, 2013
PubMed

Insights

The DNA damage response (DDR) pathway

Area of Science:

  • Molecular Biology
  • Oncology
  • Cellular Biology

Background:

  • The DNA damage response (DDR) pathway and ARF are critical barriers against cancer development.
  • Previous research suggested ARF is positively regulated by the DDR, or that they operate independently.
  • The precise interaction between ATM, a key DDR kinase, and ARF remains incompletely understood.

Purpose of the Study:

  • To investigate the functional interplay between the ATM kinase and ARF in cancer cells.
  • To elucidate the molecular mechanisms by which ATM influences ARF protein levels and activity.
  • To explore the therapeutic implications of the ATM-ARF axis in cancer treatment.

Main Methods:

  • Analysis of ARF protein levels and activity in human oncogene-transformed and cancer cells.
  • Investigation of ATM's effect on ARF via transcription-independent pathways.
  • Biochemical assays to determine the role of protein phosphatase 1, Nek2, NPM, and ULF E3-ubiquitin ligase.
  • Correlation analysis of ATM expression with ARF levels in human clinical samples.
  • Inhibition of ATM in xenograft and tissue culture models to assess ARF's tumor-suppressive effects.

Main Results:

  • ATM suppresses ARF protein levels and activity in a transcription-independent manner in cancer cells.
  • ATM activates protein phosphatase 1, which antagonizes Nek2-dependent NPM phosphorylation, freeing ARF for degradation by the ULF E3-ubiquitin ligase.
  • Loss of ATM expression in clinical samples correlates with increased ARF levels.
  • ATM inhibition enhances ARF's tumor-suppressive effects in preclinical models.

Conclusions:

  • ATM negatively regulates ARF protein stability and activity through a novel signaling cascade involving protein phosphatase 1, Nek2, NPM, and ULF.
  • This crosstalk between the DDR and ARF provides a new understanding of cancer development.
  • Targeting the ATM-ARF axis may offer therapeutic strategies for advanced tumors.

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