Apoptosis resistance in Barrett's esophagus: ex vivo bioassay of live stressed tissues.
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.
Dvorakova
Katerina
K
Department of Biology and Anatomy, College of Medicine, The University of Arizona, Tucson, Arizona.
Payne
Claire M
CM
Ramsey
Lois
L
Bernstein
Harris
H
Holubec
Hana
H
Chavarria
Melissa
M
Bernstein
Carol
C
Sampliner
Richard E
RE
Riley
Chris
C
Prasad
Anil
A
Garewal
Harinder
H
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
D003840:Deoxycholic Acid; D007633:Keratins; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases