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Analysis of Cell Cycle Position in Mammalian Cells
12:19

Analysis of Cell Cycle Position in Mammalian Cells

Published on: January 21, 2012

Oncogenic Ras blocks transforming growth factor-beta-induced cell-cycle arrest by degradation of p27 through a

Hein Schepers1, Albertus T J Wierenga, Bart J L Eggen

  • 1Division of Hematology, Department of Medicine, University Medical Center Groningen, The Netherlands.

Experimental Hematology
|June 21, 2005
PubMed
Abstract

Insights

Oncogenic Ras prevents TGF-beta-induced cell-cycle arrest in leukemia by degrading p27 via a MapK/SKP2 pathway. Restoring p27 re-establishes cell-cycle arrest, offering therapeutic insights.

Area of Science:

  • Cell biology
  • Molecular oncology
  • Signal transduction

Background:

  • Transforming growth factor-beta (TGF-beta) is a key regulator of cell-cycle arrest.
  • Oncogenic Ras proteins can interfere with cellular signaling pathways.
  • Hematopoietic cell-cycle regulation is critical in leukemia development.

Purpose of the Study:

  • To investigate how oncogenic Ras impacts TGF-beta-mediated cell-cycle arrest in hematopoietic cells.
  • To elucidate the downstream signaling pathways involved in this interference.

Main Methods:

  • Utilized leukemic cell lines with N-Ras mutations (HL-60, TF-1) and wild-type Ras (M1).
  • Employed signal transduction inhibitors, gene overexpression, and RNA interference.
  • Assessed cell-cycle arrest, protein levels (p27, SKP2), and protein localization.

Main Results:

  • N-Ras mutations abolished TGF-beta-induced G0-G1 arrest due to p27 absence.
  • p27 degradation was mediated by elevated SKP2 levels, a Ras-dependent process.
  • Inhibitors of farnesyl transferase and MEK, along with SKP2 RNA interference, restored p27 levels and cell-cycle arrest.
  • Overexpression of p27 rescued TGF-beta-induced cell-cycle arrest.

Conclusions:

  • N-Ras(L61) transformed cells exhibit a G0-G1 arrest defect upon TGF-beta treatment due to p27 absence.
  • p27 degradation occurs via a MapK- and SKP2-dependent pathway.
  • Restoring p27 levels re-establishes TGF-beta-induced cell-cycle arrest in these cells.

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