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Arsenic enhances the apoptosis induced by interferon gamma: key role of IRF-1

J El Bougrini1, M Pampin, M K Chelbi-Alix

  • 1UPR CNRS 9045, Institut André Lwoff 7 rue Guy Moquet, 94801 Villejuif, France.

Cellular and Molecular Biology (Noisy-Le-Grand, France)
|August 18, 2006
PubMed

Insights

Interferons (IFNs) and arsenic trioxide synergize to inhibit cancer cell growth. This combination prolongs STAT1 activation, increasing IRF-1 expression, which drives anti-proliferative effects and apoptosis.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cellular Signaling

Background:

  • Interferons (IFNs) and arsenic trioxide (As2O3) are established inhibitors of cell proliferation with applications in malignancy treatment.
  • IFNgamma signaling involves STAT1 phosphorylation, dimerization, nuclear translocation, DNA binding, and gene transcription.

Purpose of the Study:

  • To investigate the synergistic effects of IFNgamma and As2O3 on STAT1 phosphorylation and IRF-1 expression in human fibrosarcoma cells.
  • To elucidate the role of IRF-1 in mediating the anti-proliferative and pro-apoptotic effects of this combination therapy.

Main Methods:

  • Utilized the human fibrosarcoma cell line 2fTGH.
  • Administered IFNgamma and As2O3, alone and in combination.
  • Assessed STAT1 phosphorylation, DNA binding to GAS motifs, IRF-1 expression, cell proliferation, and apoptosis.
  • Employed RNA interference to down-regulate IRF-1 expression.

Main Results:

  • As2O3 prolonged IFNgamma-induced STAT1 phosphorylation, leading to sustained STAT1 binding to GAS motifs.
  • This resulted in significantly increased IRF-1 expression.
  • The enhanced IRF-1 expression correlated with increased anti-proliferative effects and apoptosis.
  • Down-regulation of IRF-1 abolished the biological responses induced by IFNgamma and As2O3.

Conclusions:

  • The combination of IFNgamma and As2O3 exhibits synergistic anti-cancer activity in fibrosarcoma cells.
  • Sustained STAT1 activation and subsequent IRF-1 upregulation are critical mediators of these synergistic effects.
  • IRF-1 plays a key role in mediating the anti-proliferative and pro-apoptotic outcomes of this therapeutic combination.

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