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Both ERK1 and ERK2 kinases promote G2/M arrest in etoposide-treated MCF7 cells by facilitating ATM activation

Fengxiang Wei1, Yanyun Xie, Lijian Tao

  • 1Division of Nephrology, Department of Medicine, McMaster University, Hamilton, Ontario, Canada.

Cellular Signalling
|July 20, 2010
PubMed

Insights

Both ERK1 and ERK2 kinases are crucial for DNA damage response, facilitating ATM pathway activation to induce G2/M arrest after etoposide treatment in MCF7 cells.

Area of Science:

  • Cellular Biology
  • Molecular Oncology
  • DNA Damage Response

Background:

  • The MEK-ERK pathway is implicated in DNA damage response (DDR), but the specific roles of ERK1 and ERK2 kinases remain underexplored.
  • Etoposide triggers G2/M cell cycle arrest, a process dependent on ATM kinase activation.

Purpose of the Study:

  • To investigate the direct contributions of ERK1 and ERK2 to etoposide-induced G2/M arrest.
  • To elucidate the mechanism by which ERK1 and ERK2 influence the DNA damage response pathway.

Main Methods:

  • Individual knockdown of ERK1 and ERK2 in MCF7 cells using small interfering RNA (siRNA).
  • Assessment of ATM activation and phosphorylation of its substrates (H2AX, p53, CHK2) following etoposide treatment.
  • Evaluation of CDC25C phosphorylation and cell cycle progression.

Main Results:

  • Knockdown of ERK1 or ERK2 significantly reduced ATM activation and subsequent phosphorylation of ATM substrates (gammaH2AX, p53 S15, CHK2 T68) upon etoposide exposure.
  • Reduced phosphorylation of CDC25C at S216 was observed in cells with ERK1 or ERK2 knockdown.
  • Both ERK1 and ERK2 knockdown compromised etoposide-induced G2/M arrest, indicating their essential role in this process.

Conclusions:

  • ERK1 and ERK2 kinases are essential for etoposide-induced G2/M arrest by facilitating ATM pathway activation.
  • A cellular threshold of ERK kinase activity is necessary for proper checkpoint activation in response to DNA damage.

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