ESR1 amplification in breast cancer by optimized RNase FISH: frequent but low-level and heterogeneous

PLoS One. 2013 Dec 18;8(12):e84189. doi: 10.1371/journal.pone.0084189. eCollection 2013.


Prevalence of ESR1 amplification in breast cancer is highly disputed and discrepancies have been related to different technical protocols and different scoring approaches. In addition, pre-mRNA artifacts have been proposed to influence outcome of ESR1 FISH analysis. We analyzed ESR1 gene copy number status combining an improved RNase FISH protocol with multiplex ligation-dependent probe amplification (MLPA) after laser microdissection. FISH showed a high prevalence of ESR1 gains and amplifications despite RNase treatment but MLPA did not confirm ESR1 copy number increases detected by FISH in more than half of cases. We suggest that the combination of the ESR1-specific intra-tumor heterogeneity and low-level copy number increase accounts for these discrepancies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Artifacts
  • Breast Neoplasms / genetics*
  • Breast Neoplasms / pathology*
  • DNA Copy Number Variations
  • Estrogen Receptor alpha / genetics*
  • Gene Amplification*
  • Humans
  • In Situ Hybridization, Fluorescence / methods*
  • Laser Capture Microdissection
  • Ribonucleases / metabolism*
  • Tissue Array Analysis


  • ESR1 protein, human
  • Estrogen Receptor alpha
  • Ribonucleases

Grant support

This study was supported by the Deutsche Forschungsgemeinschaft (DGF SI 1347/3-1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.