Oncogenic RAS induces accelerated transition through G2/M and promotes defects in the G2 DNA damage and mitotic spindle checkpoints

Jeffrey A. Knauf, Bin Ouyang, Erik S. Knudsen, Kenji Fukasawa, George Babcock, James A. Fagin

Research output: Contribution to journalArticle

66 Scopus citations

Abstract

Activating mutations of RAS are prevalent in thyroid follicular neoplasms, which commonly have chromosomal losses and gains. In thyroid cells, acute expression of HRASV12 increases the frequency of chromosomal abnormalities within one or two cell cycles, suggesting that RAS oncoproteins may interfere with cell cycle checkpoints required for maintenance of a stable genome. To explore this, PCCL3 thyroid cells with conditional expression of HRASV12 or HRASV12 effector mutants were presynchronized at the G1/S boundary, followed by activation of expression of RAS mutants and release from the cell cycle block. Expression of HRASV12 accelerated the G2/M phase by ∼4 h and promoted bypass of the G2 DNA damage and mitotic spindle checkpoints. Accelerated passage through G2/M and bypass of the G2 DNA damage checkpoint, but not bypass of the mitotic spindle checkpoint, required activation of mitogen-activated protein kinase (MAPK). However, selective activation of the MAPK pathway was not sufficient to disrupt the G2 DNA damage checkpoint, because cells arrested appropriately in G2 despite conditional expression of HRASV12,S35 or BRAFV600E. By contrast to the MAPK requirement for radiation-induced G2 arrest, RAS-induced bypass of the mitotic spindle checkpoint was not prevented by pretreatment with MEK inhibitors. These data support a direct role for the MAPK pathway in control of G2 progression and regulation of the G 2 DNA damage checkpoint. We propose that oncogenic RAS activation may predispose cells to genomic instability through both MAPK-dependent and independent pathways that affect critical checkpoints in G2/M.

Original languageEnglish (US)
Pages (from-to)3800-3809
Number of pages10
JournalJournal of Biological Chemistry
Volume281
Issue number7
DOIs
StatePublished - Feb 17 2006

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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