title: IGF-1 and its receptor in esophageal cancer: association with adenocarcinoma and visceral obesity.
abstract: OBJECTIVE
  The insulin-like growth factor (IGF) pathway and visceral obesity have been independently linked with esophageal cancer. This study aimed to delineate the differential and interlinked role of visceral obesity and the IGF-1 system in esophageal adenocarcinoma and esophageal squamous-cell carcinoma (SCC).
  
  
  METHODS
  IGF-1 receptor (IGF-1R) mRNA and protein were examined in esophageal SCC (KYSE 410, OE21) and esophageal adenocarcinoma (OE19, OE33) cell lines by western blotting. Tumor cell proliferation in response to IGF-1 was assessed by bromodeoxyuridine incorporation assay. In esophageal tumor sections, expression of IGF-1R and CD68(+) cell numbers were assessed by immunohistochemistry. IGF-1 was measured in serum from esophageal cancer patients, Barrett's esophagus patients, and healthy controls by enzyme-linked immunosorbent assay.
  
  
  RESULTS
  Higher IGF-1R protein expressions were observed in SCC cells compared with esophageal adenocarcinoma cells however only adenocarcinoma cell lines significantly increased proliferation in response to IGF-1 (P<0.01). Serum IGF-1 levels were highest in esophageal adenocarcinoma patients (P<0.01) and higher in viscerally obese vs. nonobese (P<0.05) patients. In resected esophageal cancer, increased expression of IGF-1R was observed in the tumor and invasive edge compared with tumor-associated stroma (P<0.05), which coincided with increased CD68(+) cells in stromal tissue surrounding invasive tumor edge (P<0.01).
  
  
  CONCLUSIONS
  This novel study examined the differential role of the IGF system in esophageal adenocarcinoma and SCC, and its association with visceral obesity. These results indicate that the IGF-1 axis has a key role in malignant progression of esophageal cancer, and represents a plausible mechanism through which visceral obesity impacts on esophageal adenocarcinoma risk and tumor biology.
authors.affiliation: Department of Surgery, Institute of Molecular Medicine, Trinity Centre for Health Sciences, St James's Hospital and University of Dublin, Trinity College, Dublin, Ireland.
authors.forename: Suzanne L
authors.initials: SL
authors.lastname: Doyle
authors.forename: Claire L
authors.initials: CL
authors.lastname: Donohoe
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Finn
authors.forename: Julia M
authors.initials: JM
authors.lastname: Howard
authors.forename: Fiona E
authors.initials: FE
authors.lastname: Lithander
authors.forename: John V
authors.initials: JV
authors.lastname: Reynolds
authors.forename: Graham P
authors.initials: GP
authors.lastname: Pidgeon
authors.forename: Joanne
authors.initials: J
authors.lastname: Lysaght
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D049109:Cell Proliferation; D004938:Esophageal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D004947:Esophagus / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D017526:Receptor, IGF Type 1 / Q000235:genetics / Q000378:metabolism*
chemical_list: D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1