title: Apoptosis resistance in Barrett's esophagus: ex vivo bioassay of live stressed tissues.
abstract: OBJECTIVE
  Barrett's esophagus (BE) is a premalignant lesion of the distal esophagus in which squamous epithelial cells are replaced by metaplastic intestinal-like columnar epithelium that contains goblet cells. The factors that contribute to the progression from normal squamous mucosa to BE, Barrett's dysplasia, and adenocarcinoma are not well understood at the molecular level. Since reflux of bile acids is associated with BE development, we speculate that cells with an apoptosis-resistant phenotype are selected after long-term repeated exposure to pulses of bile acids. This will result in the survival of cells with unrepaired DNA damage, and a consequent increase in genomic instability leading to cancer progression. The major goal of this study is to compare sensitivity to apoptosis induced by the bile acid, deoxycholate (DOC), a known inducer of apoptosis, in normal esophageal squamous epithelium, normal colon epithelium, and BE.
  
  
  METHODS
  Thirteen patients with a confirmed diagnosis of BE and four patients who had undergone clinically indicated colectomy were included in the present study. Freshly obtained biopsies were incubated with control medium or medium supplemented with 1 mM DOC for 3 h and then evaluated for apoptotic changes using transmission electron microscopy and immunohistochemical staining for two apoptotic markers, cleaved caspase 3 and cleaved cytokeratin 18.
  
  
  RESULTS
  Our results indicate that BE is resistant to apoptosis induced by DOC compared to esophageal squamous epithelium and normal colon epithelium. In addition, electron micrographs revealed mitochondrial swelling in squamous epithelial cells treated ex vivo with DOC, which was absent in epithelial cells of BE. Formation of swollen mitochondria is an early marker of apoptotic cell death. Altogether, the data indicate that reduced apoptosis capability in BE tissue may contribute to progression to esophageal adenocarcinoma.
authors.affiliation: Department of Biology and Anatomy, College of Medicine, The University of Arizona, Tucson, Arizona.
authors.forename: Katerina
authors.initials: K
authors.lastname: Dvorakova
authors.forename: Claire M
authors.initials: CM
authors.lastname: Payne
authors.forename: Lois
authors.initials: L
authors.lastname: Ramsey
authors.forename: Harris
authors.initials: H
authors.lastname: Bernstein
authors.forename: Hana
authors.initials: H
authors.lastname: Holubec
authors.forename: Melissa
authors.initials: M
authors.lastname: Chavarria
authors.forename: Carol
authors.initials: C
authors.lastname: Bernstein
authors.forename: Richard E
authors.initials: RE
authors.lastname: Sampliner
authors.forename: Chris
authors.initials: C
authors.lastname: Riley
authors.forename: Anil
authors.initials: A
authors.lastname: Prasad
authors.forename: Harinder
authors.initials: H
authors.lastname: Garewal
mesh_terms: D000328:Adult; D000368:Aged; D017209:Apoptosis / Q000187:drug effects*; D001471:Barrett Esophagus / Q000378:metabolism / Q000473:pathology*; D001706:Biopsy; D053148:Caspase 3; D020169:Caspases / Q000032:analysis; D003106:Colon / Q000473:pathology; D003840:Deoxycholic Acid / Q000494:pharmacology*; D004848:Epithelium / Q000187:drug effects / Q000473:pathology; D004947:Esophagus / Q000737:chemistry / Q000473:pathology* / Q000648:ultrastructure; D006801:Humans; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000187:drug effects / Q000473:pathology; D007633:Keratins / Q000032:analysis; D046529:Microscopy, Electron, Transmission; D008875:Middle Aged
chemical_list: D003840:Deoxycholic Acid; D007633:Keratins; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases