title: Bile salt exposure increases proliferation through p38 and ERK MAPK pathways in a non-neoplastic Barrett's cell line.
abstract: Bile reflux has been implicated in the neoplastic progression of Barrett's esophagus (BE). Bile salts increase proliferation in a Barrett's-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 Barrett's 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 15-20%. In conclusion, in a non-neoplastic Barrett's 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.
authors.affiliation: Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas 75216, USA.
authors.forename: Kshama
authors.initials: K
authors.lastname: Jaiswal
authors.forename: Christie
authors.initials: C
authors.lastname: Lopez-Guzman
authors.forename: Rhonda F
authors.initials: RF
authors.lastname: Souza
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Spechler
authors.forename: George A
authors.initials: GA
authors.lastname: Sarosi
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism; D017304:Annexin A5 / Q000378:metabolism; D000963:Antimetabolites; D017209:Apoptosis / Q000187:drug effects; D001471:Barrett Esophagus / Q000378:metabolism*; D001647:Bile Acids and Salts / Q000494:pharmacology*; D015153:Blotting, Western; D001973:Bromodeoxyuridine; D002452:Cell Count; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004938:Esophageal Neoplasms / Q000378:metabolism; D004947:Esophagus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D020287:In Situ Nick-End Labeling; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D017304:Annexin A5; D000963:Antimetabolites; D001647:Bile Acids and Salts; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D001973:Bromodeoxyuridine