Cyclin E amplification/overexpression is a mechanism of trastuzumab resistance in HER2+ breast cancer patients Academic Article uri icon


MeSH Major

  • Antibodies, Monoclonal
  • Breast Neoplasms
  • Cyclin E
  • Drug Resistance, Neoplasm
  • Gene Amplification
  • Oncogene Proteins
  • Receptor, ErbB-2


  • Clinical benefits from trastuzumab and other anti-HER2 therapies in patients with HER2 amplified breast cancer remain limited by primary or acquired resistance. To identify potential mechanisms of resistance, we established trastuzumab-resistant HER2 amplified breast cancer cells by chronic exposure to trastuzumab treatment. Genomewide copy-number variation analyses of the resistant cells compared with parental cells revealed a focal amplification of genomic DNA containing the cyclin E gene. In a cohort of 34 HER2(+) patients treated with trastuzumab-based therapy, we found that cyclin E amplification/overexpression was associated with a worse clinical benefit (33.3% compared with 87.5%, P < 0.02) and a lower progression-free survival (6 mo vs. 14 mo, P < 0.002) compared with nonoverexpressing cyclin E tumors. To dissect the potential role of cyclin E in trastuzumab resistance, we studied the effects of cyclin E overexpression and cyclin E suppression. Cyclin E overexpression resulted in resistance to trastuzumab both in vitro and in vivo. Inhibition of cyclin E activity in cyclin E-amplified trastuzumab resistant clones, either by knockdown of cyclin E expression or treatment with cyclin-dependent kinase 2 (CDK2) inhibitors, led to a dramatic decrease in proliferation and enhanced apoptosis. In vivo, CDK2 inhibition significantly reduced tumor growth of trastuzumab-resistant xenografts. Our findings point to a causative role for cyclin E overexpression and the consequent increase in CDK2 activity in trastuzumab resistance and suggest that treatment with CDK2 inhibitors may be a valid strategy in patients with breast tumors with HER2 and cyclin E coamplification/overexpression.

publication date

  • March 2011



  • Academic Article



  • eng

PubMed Central ID

  • PMC3048107

Digital Object Identifier (DOI)

  • 10.1073/pnas.1014835108

PubMed ID

  • 21321214

Additional Document Info

start page

  • 3761

end page

  • 6


  • 108


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