Differences in degradation lead to asynchronous expression of cyclin E1 and cyclin E2 in cancer cells

Cell Cycle. 2013 Feb 15;12(4):596-605. doi: 10.4161/cc.23409. Epub 2013 Jan 16.


Cyclin E1 is expressed at the G 1/S phase transition of the cell cycle to drive the initiation of DNA replication and is degraded during S/G2M. Deregulation of its periodic degradation is observed in cancer and is associated with increased proliferation and genomic instability. We identify that in cancer cells, unlike normal cells, the closely related protein cyclin E2 is expressed predominantly in S phase, concurrent with DNA replication. This occurs at least in part because the ubiquitin ligase component that is responsible for cyclin E1 downregulation in S phase, Fbw7, fails to effectively target cyclin E2 for proteosomal degradation. The distinct cell cycle expression of the two E-type cyclins in cancer cells has implications for their roles in genomic instability and proliferation and may explain their associations with different signatures of disease.

Keywords: Fbw7; cell cycle; cyclin E1; cyclin E2; proliferation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle Proteins / genetics*
  • Cell Cycle Proteins / metabolism
  • Cell Line, Tumor
  • Cyclin E / genetics*
  • Cyclin E / metabolism
  • Cyclins / genetics*
  • Cyclins / metabolism
  • DNA Replication
  • F-Box Proteins / genetics*
  • F-Box Proteins / metabolism
  • F-Box-WD Repeat-Containing Protein 7
  • G1 Phase Cell Cycle Checkpoints / genetics*
  • G2 Phase Cell Cycle Checkpoints / genetics*
  • Gene Expression Regulation, Neoplastic*
  • Genome, Human
  • Genomic Instability
  • Humans
  • Oncogene Proteins / genetics*
  • Oncogene Proteins / metabolism
  • Proteasome Endopeptidase Complex / metabolism
  • Proteolysis
  • Ubiquitin-Protein Ligases / genetics*
  • Ubiquitin-Protein Ligases / metabolism


  • CCNE1 protein, human
  • CCNE2 protein, human
  • Cell Cycle Proteins
  • Cyclin E
  • Cyclins
  • F-Box Proteins
  • F-Box-WD Repeat-Containing Protein 7
  • FBXW7 protein, human
  • Oncogene Proteins
  • Ubiquitin-Protein Ligases
  • Proteasome Endopeptidase Complex