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Establishment of Proliferative Tetraploid Cells from Nontransformed Human Fibroblasts
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Fbw7 regulates the activity of endoreduplication mediators and the p53 pathway to prevent drug-induced polyploidy

S Finkin1, Y Aylon, S Anzi

  • 1Department of Experimental Medicine and Cancer Research, Hebrew University Medical School, Jerusalem, Israel.

Oncogene
|April 9, 2008
PubMed

Insights

Fbw7, a tumor suppressor, regulates cell growth. Its inactivation leads to polyploidy and impaired p53 response to chemotherapy, affecting cancer treatment outcomes.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cell Biology

Background:

  • Fbw7 is a crucial tumor suppressor gene.
  • It encodes an E3 ubiquitin ligase regulating cell growth and proliferation.
  • Mutations in Fbw7 are linked to various cancers.

Purpose of the Study:

  • To investigate the impact of Fbw7 inactivation on chemotherapy response.
  • To understand the mechanisms behind Fbw7's role in cell cycle regulation and cancer.

Main Methods:

  • Utilized Fbw7-deficient cell models.
  • Exposed cells to spindle toxins (vinblastine, taxol).
  • Analyzed cell ploidy, mitotic slippage, and protein expression levels (cyclin E, Aurora A, p53, Lats2, p21).

Main Results:

  • Fbw7-deficient cells exhibited polyploidy due to mitotic slippage and endoreduplication when treated with spindle toxins.
  • Combined elevation of cyclin E and Aurora A was necessary for this polyploidy.
  • Fbw7 deficiency impaired p53's response to mitotic toxins but not DNA damage.
  • Fbw7 regulated p53-dependent gene induction (Lats2, p21) following vinblastine treatment.

Conclusions:

  • Fbw7 inactivation promotes drug-induced polyploidy by deregulating key cell cycle proteins.
  • Fbw7 plays a critical role in p53-mediated responses to mitotic stress.
  • Fbw7 acts as a master regulator of the mitotic and tetraploidy checkpoints, impacting cancer therapy effectiveness.

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