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MUCOSAL BIOLOGY
Departments of 1Surgery and 2Medicine, University of Texas Southwestern Medical Center and Veterans Affairs North Texas Health Center, and 3The Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas
Submitted 13 April 2005 ; accepted in final form 15 October 2005
Bile reflux has been implicated in the neoplastic progression of Barretts esophagus (BE). Bile salts increase proliferation in a Barretts-associated adenocarcinoma cell line (SEG-1 cells) by activating ERK and p38 MAPK pathways. However, it is not clear that these findings in cancer cells are applicable to non-neoplastic cells of benign BE. We examined the effect of bile salts on three human cell lines: normal esophageal squamous (NES) cells, non-neoplastic Barretts cells (BAR cells), and SEG-1 cells. We hypothesized that bile salt exposure activates proproliferative and antiapoptotic pathways to promote increased growth in BE. NES, BAR, and SEG-1 cells were exposed to glycochenodeoxycholic acid (GCDA) at a neutral pH for 5 min. Proliferation was measured by Coulter counter cell counts and a 5-bromo-2'-deoxyuridine (BrdU) incorporation assay. GCDA-induced MAPK activation was examined by Western blot analysis for phosphorylated ERK and p38. Apoptosis was measured by TdT-mediated dUTP nick-end labeling and annexin V staining after GCDA and UV-B exposure. Statistical significance was determined by ANOVA. NES cells exposed to 5 min of GCDA did not increase cell number. In BAR cells, GCDA exposure increased cell number by 31%, increased phosphorylated p38 and ERK levels by two- to three-fold, increased BrdU incorporation by 30%, and decreased UV-induced apoptosis by 1520%. In conclusion, in a non-neoplastic Barretts cell line, GCDA exposure induces proliferation by activation of both ERK and p38 MAPK pathways. These findings suggest a potential mechanism whereby bile reflux may facilitate the neoplastic progression of BE.
bile salts; mitogen-activated protein kinase
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