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GSK-3beta-dependent destabilization of cyclin D1 mediates replicational stress-induced arrest of cell cycle

Atish Mukherji1, Vaibhao C Janbandhu, Vijay Kumar

  • 1Virology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110 067, India.

FEBS Letters
|March 11, 2008
PubMed

Insights

Hydroxyurea (HU) causes cancer cell growth arrest by destabilizing cyclin D1, a key cell cycle regulator. This process involves specific protein modifications and kinase activity, independent of other cell cycle controls.

Area of Science:

  • Cell Biology
  • Molecular Oncology
  • Cancer Therapeutics

Background:

  • Chemotherapeutic agents induce cancer cell cycle arrest and apoptosis via DNA damage.
  • Hydroxyurea (HU) is a known inhibitor of ribonucleotide reductase, impacting DNA synthesis.

Purpose of the Study:

  • To investigate the specific molecular mechanisms by which hydroxyurea (HU) induces cell cycle arrest.
  • To identify novel roles of cyclin D1 regulation in HU-induced growth inhibition.

Main Methods:

  • Cell cycle analysis in cancer cells treated with HU.
  • Western blotting to assess protein levels and phosphorylation.
  • Overexpression studies using cyclin D1 mutants and Akt kinase.

Main Results:

  • HU treatment induced G1/S phase arrest, primarily through cyclin D1 destabilization.
  • Cyclin D1 degradation was linked to phosphorylation at Thr286 by glycogen synthase kinase-3beta (GSK-3beta).
  • Akt kinase inactivation was observed, and its modulation affected cyclin D1 stability and cell cycle arrest.

Conclusions:

  • Cyclin D1 destabilization is a critical initiator of HU-induced G1/S phase arrest, acting independently of other cell cycle regulators.
  • The findings reveal a novel pathway involving GSK-3beta and Akt in regulating cyclin D1 stability during chemotherapy.
  • Hydroxyurea's growth arrest mechanism involves cyclin D1 destabilization beyond its ribonucleotide reductase inhibitory function.

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