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Implications of caspase-dependent proteolytic cleavage of cyclin A1 in DNA damage-induced cell death

Sang Hyeok Woo1, Sung-Keum Seo1, Sungkwan An2

  • 1Division of Radiation Cancer Research, Korea Institute of Radiological & Medical Sciences, 215-4 Gongneung-dong, Nowon-gu, Seoul, Republic of Korea.

Biochemical and Biophysical Research Communications
|October 5, 2014
PubMed

Insights

Doxorubicin reduces cyclin A1 (cell cycle regulator) in lung cancer cells via caspase-1 activation. Restoring cyclin A1 levels protects cells from doxorubicin and radiation, revealing a new DNA damage response pathway.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • Cyclin A1 regulates cell-cycle progression by binding to CDK2.
  • Understanding cyclin A1's role in DNA damage response is crucial for cancer therapy.

Purpose of the Study:

  • To investigate the effect of doxorubicin on cyclin A1 expression.
  • To elucidate the mechanism of cyclin A1 regulation by DNA-damaging agents.
  • To determine the role of cyclin A1 in cellular response to doxorubicin and ionizing radiation.

Main Methods:

  • Western blotting and quantitative PCR to assess protein and mRNA levels.
  • Enzyme inhibition assays using z-YAVD-fmk.
  • In vitro cleavage assays with purified caspases.
  • Cell viability assays and RNA interference for functional studies.

Main Results:

  • Doxorubicin decreased both protein and mRNA levels of cyclin A1 in A549 lung cancer cells.
  • Doxorubicin upregulated caspase-1, and its inhibition restored cyclin A1 levels.
  • Active caspase-1 cleaved cyclin A1, with subsequent cleavage by caspase-3.
  • Overexpression of cyclin A1 reduced doxorubicin cytotoxicity, while its knockdown increased sensitivity to ionizing radiation.

Conclusions:

  • DNA-damaging agents like doxorubicin downregulate cyclin A1 through caspase-1 activation.
  • Cyclin A1 plays a protective role against DNA damage-induced cell death.
  • This pathway involving cyclin A1 and caspases is a novel mechanism in cellular response to DNA damage.
Keywords:
Caspase-1Cyclin A1DoxorubicinIonizing radiation

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