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Caffeine abolishes the mammalian G(2)/M DNA damage checkpoint by inhibiting ataxia-telangiectasia-mutated kinase

B B Zhou1, P Chaturvedi, K Spring

  • 1Department of Oncology Research, SmithKline Beecham Pharmaceuticals, King of Prussia, Pennsylvania 19406, USA. Bing-Bing_S_Zhou@sbphrd.com

The Journal of Biological Chemistry
|April 1, 2000
PubMed

Insights

Caffeine disrupts the G(2)/M cell cycle checkpoint by inhibiting ATM kinase activity, preventing Chk2/Cds1 activation and subsequent Cdc25C phosphorylation. This mechanism explains caffeine

Area of Science:

  • Cell cycle regulation
  • DNA damage response
  • Cancer research

Background:

  • Cell cycle arrest at G(2)/M is crucial for DNA repair.
  • Cdc25C phosphorylation at serine 216 is key to G(2)/M arrest.
  • ATM and Chk2/Cds1 are central to the DNA damage response.

Purpose of the Study:

  • To elucidate the molecular mechanism of caffeine's effect on the G(2)/M checkpoint.
  • To investigate caffeine's impact on the ATM-Chk2/Cds1 pathway.
  • To understand how caffeine influences radiosensitivity.

Main Methods:

  • Utilized phospho-specific antibodies to detect phosphorylated Cdc25C (serine 216) and Chk2/Cds1 (threonine 68).
  • Exposed cells to gamma-radiation and treated with caffeine.
  • Assayed ATM kinase activity and Chk2/Cds1 phosphorylation in vitro and in vivo.

Main Results:

  • Caffeine treatment inhibited radiation-induced nuclear accumulation of phosphorylated Cdc25C (serine 216).
  • Caffeine blocked ATM-dependent activation and phosphorylation of Chk2/Cds1 at threonine 68.
  • Caffeine's IC(50) for inhibiting ATM phosphorylation of Chk2/Cds1 was approximately 200 microM.

Conclusions:

  • Caffeine abrogates the G(2)/M checkpoint by inhibiting ATM kinase activity.
  • This inhibition prevents Chk2/Cds1 activation and subsequent Cdc25C phosphorylation.
  • Targeting the ATM-Chk2/Cds1 pathway explains caffeine's radiosensitizing effect.

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