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p53-deficient cells rely on ATM- and ATR-mediated checkpoint signaling through the p38MAPK/MK2 pathway for survival

H Christian Reinhardt1, Aaron S Aslanian, Jacqueline A Lees

  • 1Center for Cancer Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, E18-580, Cambridge, MA 02139, USA.

Cancer Cell
|February 13, 2007
PubMed

Insights

In p53-deficient cells, a third cell-cycle checkpoint pathway involving p38MAPK/MK2 is crucial for DNA damage response and survival. Disrupting this pathway alongside Chk1 causes mitotic catastrophe and tumor regression.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Cancer Research

Background:

  • Eukaryotic cells activate ATM-Chk2 and ATR-Chk1 pathways for DNA damage response, cell cycle arrest, and repair.
  • The role of alternative checkpoint pathways in p53-deficient cells remains incompletely understood.

Purpose of the Study:

  • To investigate the role of the p38MAPK/MK2 pathway in cell-cycle arrest and survival following DNA damage in p53-deficient cells.
  • To determine the impact of MK2 depletion on checkpoint activation and cellular response to genotoxic stress.

Main Methods:

  • Utilized p53-deficient and p53 wild-type cell lines.
  • Employing cisplatin and doxorubicin as DNA-damaging agents.
  • Assessed cell-cycle checkpoints (S phase and G2/M) and cellular fate (mitotic catastrophe).
  • Investigated the effect of MK2 depletion and Chk1 inhibitor (UCN-01) treatment.

Main Results:

  • MK2 depletion abrogated the Cdc25A-mediated S phase checkpoint in p53-deficient cells exposed to cisplatin.
  • Loss of the Cdc25B-mediated G2/M checkpoint was observed in p53-deficient cells treated with doxorubicin after MK2 depletion.
  • MK2 depletion led to mitotic catastrophe and significant tumor regression in vivo in p53-deficient models.
  • The Chk1 inhibitor UCN-01 was found to inhibit MK2, suggesting dual pathway disruption in p53-defective cells.

Conclusions:

  • The p38MAPK/MK2 pathway represents a critical third cell-cycle checkpoint in p53-deficient cells, essential for survival after DNA damage.
  • Simultaneous inhibition of MK2 and Chk1 pathways, as achieved by UCN-01, is a promising strategy for treating p53-defective cancers.
  • Targeting the MK2 pathway offers a novel therapeutic avenue for enhancing the efficacy of DNA-damaging agents in specific cancer contexts.

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