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Cancer-associated mutations in chromatin remodeler hSNF5 promote chromosomal instability by compromising the mitotic

Robert G J Vries1, Vladimir Bezrookove, Lobke M P Zuijderduijn

  • 1Department of Molecular and Cell Biology, Leiden University Medical Centre, 2300 RA Leiden, The Netherlands.

Genes & Development
|March 17, 2005
PubMed

Insights

Loss of the hSNF5 tumor suppressor causes polyploidy and chromosomal instability in malignant rhabdoid tumors. Restoring hSNF5 function corrects these defects, while mutations worsen them by disrupting chromosome segregation.

Area of Science:

  • Cell Biology
  • Cancer Biology
  • Chromatin Biology

Background:

  • The human SWI/SNF (hSWI/SNF) complex is crucial for ATP-dependent chromatin remodeling.
  • hSNF5 is a key tumor suppressor subunit, frequently inactivated in malignant rhabdoid tumors (MRTs).
  • Loss of hSNF5 function is linked to uncontrolled cell proliferation and genetic instability in cancer.

Purpose of the Study:

  • To investigate the role of hSNF5 in maintaining genomic stability.
  • To determine how hSNF5 inactivation contributes to polyploidization and chromosomal instability in MRTs.
  • To elucidate the molecular mechanisms by which hSNF5 regulates cell cycle and ploidy checkpoints.

Main Methods:

  • Utilized MRT-derived cell lines with varying hSNF5 function (wild-type, loss-of-function, mutant).
  • Performed cell cycle analysis, ploidy assessment, and chromosomal instability scoring.
  • Investigated the involvement of the p16INK4a-cyclinD/CDK4-pRb-E2F pathway and mitotic checkpoint activation.

Main Results:

  • Loss of hSNF5 function in MRT cells resulted in significant polyploidization and chromosomal instability.
  • Re-expression of wild-type hSNF5 restored proper cell cycle progression and ploidy checkpoint control.
  • Cancer-associated hSNF5 mutants exacerbated poly- and aneuploidization by abrogating chromosome segregation.
  • hSNF5 was found to activate the mitotic checkpoint via the p16INK4a-cyclinD/CDK4-pRb-E2F pathway.

Conclusions:

  • hSNF5 is essential for preventing polyploidy and chromosomal instability in MRTs.
  • Mutations in hSNF5 can directly lead to severe genomic instability through impaired chromosome segregation.
  • These findings highlight the critical role of chromatin remodelers in maintaining genome integrity and suppressing tumor formation.

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