title: Epidermal growth factor receptor (EGFR) is overexpressed in high-grade dysplasia and adenocarcinoma of the esophagus and may represent a biomarker of histological progression in Barrett's esophagus (BE).
abstract: OBJECTIVE
  The assessment of cancer risk in patients with Barrett's esophagus (BE) is currently fraught with difficulty. The current gold standard method of assessing cancer risk is histological assessment, with the appearance of high-grade dysplasia (HGD) as the key event monitored. Sampling error during endoscopy limits the usefulness of this approach, and there has been much recent interest in supplementing histological assessment with molecular markers, which may aid in patient stratification.
  
  
  METHODS
  No molecular marker has been yet validated to accurately correlate with esophageal histological progression. Here, we assessed the suitability of several membranous proteins as biomarkers by correlating their abundance with histological progression. In all, 107 patient samples, from 100 patients, were arranged on a tissue microarray (TMA) and represented the various stages of histological progression in BE. This TMA was probed with antibodies for eight receptor proteins (mostly membranous).
  
  
  RESULTS
  Epidermal growth factor receptor (EGFR) staining was found to be the most promising biomarker identified with clear increases in staining accompanying histological progression. Further, immunohistochemistry was performed using the full-tissue sections from BE, HGD, and adenocarcinoma tissues, which confirmed the stepwise increase in EGFR abundance. Using a robust H-score analysis, EGFR abundance was shown to increase 13-fold in the adenocarcinoma tissues compared to the BE tissues. EGFR was "overexpressed" in 35% of HGD specimens and 80% of adenocarcinoma specimens when using the H-score of the BE patients (plus 3 s.d.) as the threshold to define overexpression. EGFR staining was also noted to be higher in BE tissues adjacent to HGD/adenocarcinoma. Western blotting, although showing more EGFR protein in the adenocarcinomas compared to the BE tissue, was highly variable. EGFR overexpression was accompanied by aneuploidy (gain) of chromosome 7, plus amplification of the EGFR locus. Finally, the bile acid deoxycholic acid (DCA) (at neutral and acidic pH) and acid alone was capable of upregulating EGFR mRNA in vitro, and in the case of neutral pH DCA, this was NF-κB dependent.
  
  
  CONCLUSIONS
  EGFR is overexpressed during the histological progression in BE tissues and hence may be useful as a biomarker of histological progression. Furthermore, as EGFR is a membranous protein expressed on the luminal surface of the esophageal mucosa, it may also be a useful target for biopsy guidance during endoscopy.
authors.affiliation: Institute of Life Science, Swansea School of Medicine, Swansea University, Swansea, UK.
authors.forename: James
authors.initials: J
authors.lastname: Cronin
authors.forename: Elizabeth
authors.initials: E
authors.lastname: McAdam
authors.forename: Antonios
authors.initials: A
authors.lastname: Danikas
authors.forename: Chris
authors.initials: C
authors.lastname: Tselepis
authors.forename: Paul
authors.initials: P
authors.lastname: Griffiths
authors.forename: John
authors.initials: J
authors.lastname: Baxter
authors.forename: Linzi
authors.initials: L
authors.lastname: Thomas
authors.forename: James
authors.initials: J
authors.lastname: Manson
authors.forename: Gareth
authors.initials: G
authors.lastname: Jenkins
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics* / Q000473:pathology; D000368:Aged; D001471:Barrett Esophagus / Q000235:genetics* / Q000473:pathology; D014408:Biomarkers, Tumor / Q000235:genetics*; D001707:Biopsy, Needle; D015153:Blotting, Western; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000473:pathology; D015331:Cohort Studies; D018450:Disease Progression; D004815:Epidermal Growth Factor / Q000235:genetics* / Q000378:metabolism; D004938:Esophageal Neoplasms / Q000235:genetics* / Q000473:pathology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D016133:Polymerase Chain Reaction; D011230:Precancerous Conditions / Q000235:genetics* / Q000473:pathology; D011237:Predictive Value of Tests; D011379:Prognosis; D012333:RNA, Messenger / Q000235:genetics; D015854:Up-Regulation
chemical_list: D014408:Biomarkers, Tumor; D012333:RNA, Messenger; D004815:Epidermal Growth Factor