Characterization of squamous esophageal cells resistant to bile acids at acidic pH: implication for Barrett's esophagus pathogenesis.
Barrett's esophagus (BE) is a premalignant condition, where normal squamous epithelium is replaced by intestinal epithelium. BE is associated with an increased risk of developing esophageal adenocarcinoma (EAC). However, the BE cell of origin is not clear. We hypothesize that BE tissue originates from esophageal squamous cells, which can differentiate to columnar cells as a result of repeated exposure to gastric acid and bile acids, two components of refluxate implicated in BE pathology. To test this hypothesis, we repeatedly exposed squamous esophageal HET1A cells to 0.2 mM bile acid (BA) cocktail at pH 5.5 and developed an HET1AR-resistant cell line. These cells are able to survive and proliferate after repeated 2-h treatments with BA at pH 5.5. HET1AR cells are resistant to acidification and express markers of columnar differentiation, villin, CDX2, and cytokeratin 8/18. HET1AR cells have increased amounts of reactive oxygen species, concomitant with a decreased level and activity of manganese superoxide dismutase compared with parental cells. Furthermore, HET1AR cells express proteins and activate signaling pathways associated with inflammation, cell survival, and tumorigenesis that are thought to contribute to BE and EAC development. These include STAT3, NF-κB, epidermal growth factor receptor (EGFR), cyclooxygenase-2, interleukin-6, phosphorylated mammalian target of rapamycin (p-mTOR), and Mcl-1. The expression of prosurvival and inflammatory proteins and resistance to cell death could be partially modified by inhibition of STAT3 signaling. In summary, our study shows that long-term exposure of squamous cells to BA at acidic pH causes the cells to display the same characteristics and markers as BE.
Department of Cell Biology and Anatomy, Univ. of Arizona, 1501 N. Campbell Ave. P.O. Box 245044, Tucson, AZ 85724, USA.
Aaron
A
Goldman
Hwu Dau Rw
HD
Chen
Heather B
HB
Roesly
Kimberly A
KA
Hill
Margaret E
ME
Tome
Bohuslav
B
Dvorak
Harris
H
Bernstein
Katerina
K
Dvorak
D000143:Acids / Q000494:pharmacology; D000230:Adenocarcinoma / Q000378:metabolism; D001471:Barrett Esophagus / Q000209:etiology*; D001647:Bile Acids and Salts / Q000494:pharmacology*; D015415:Biomarkers / Q000378:metabolism; D002461:Cell Line, Transformed; D015536:Down-Regulation; D004351:Drug Resistance; D004848:Epithelium / Q000378:metabolism; D004938:Esophageal Neoplasms / Q000378:metabolism; D004947:Esophagus / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015850:Interleukin-6 / Q000378:metabolism; D008679:Metaplasia / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000037:antagonists & inhibitors / Q000378:metabolism; D015398:Signal Transduction; D013482:Superoxide Dismutase / Q000378:metabolism; D015854:Up-Regulation
D000143:Acids; D001647:Bile Acids and Salts; D015415:Biomarkers; D015850:Interleukin-6; D016328:NF-kappa B; D017382:Reactive Oxygen Species; D050796:STAT3 Transcription Factor; D013482:Superoxide Dismutase