title: ESR1 amplification in breast cancer by optimized RNase FISH: frequent but low-level and heterogeneous.
abstract: 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.
authors.affiliation: Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Cathy B
authors.initials: CB
authors.lastname: Moelans
authors.affiliation: Section of Gynecology and Obstetrics, Department of Clinical Science, Haukeland University Hospital, Bergen, Norway ; Department of Pathology, University Medical Center Hamburg Eppendorf, Hamburg, Germany.
authors.forename: Frederik
authors.initials: F
authors.lastname: Holst
authors.affiliation: Department of Legal Medicine, University Medical Center Hamburg Eppendorf, Hamburg, Germany.
authors.forename: Olaf
authors.initials: O
authors.lastname: Hellwinkel
authors.affiliation: Department of Pathology, University Medical Center Hamburg Eppendorf, Hamburg, Germany.
authors.forename: Ronald
authors.initials: R
authors.lastname: Simon
authors.affiliation: Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: van Diest
mesh_terms: D016477:Artifacts; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology*; D056915:DNA Copy Number Variations; D047628:Estrogen Receptor alpha / Q000235:genetics*; D005784:Gene Amplification; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D061346:Laser Capture Microdissection; D012260:Ribonucleases / Q000378:metabolism*; D046888:Tissue Array Analysis
chemical_list: C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha; D012260:Ribonucleases