TY - JOUR
T1 - Acid increases MAPK-mediated proliferation in Barrett's esophageal adenocarcinoma cells via intracellular acidification through a Cl -/HCO3- exchanger
AU - Sarosi, George A.
AU - Jaiswal, Kshama
AU - Herndon, Emily
AU - Lopez-Guzman, Christie
AU - Spechler, Stuart J.
AU - Souza, Rhonda F.
PY - 2005/12
Y1 - 2005/12
N2 - Abundant epidemiological evidence links acid reflux to adenocarcinoma in Barrett's esophagus, but few studies have examined the cellular mechanisms by which acid promotes this neoplastic progression. We hypothesized that extracellular acid exposure causes intracellular acidification that triggers MAPK signaling and proliferation in Barrett's epithelial cells. We tested that hypothesis in a Barrett's-derived esophageal adenocarcinoma cell line (SEG-1). SEG-1 cells were exposed to varying concentrations of acid, and intracellular pH (pHi) was measured by 2′,7′-bis-(2-carboxyethyl)-5-(and- 6)-carboxyfluorescein microfluorimetry. After acid exposure, ERK and p38 MAPK activation were measured by Western blot analysis and an immune complex kinase assay. Proliferation was measured by Coulter counter cell counts and a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide incorporation assay. Exposure of SEG-1 cells to solutions with a pH between 3 and 6.5 caused a rapid, reversible decrease in pHi to a level approximately equal to extracellular pH. Acid exposure caused a rapid activation of both ERK and p38 MAPKs and also resulted in pH-dependent increases in cell number, with a maximum increase of 41% observed at pH 6.0. The MAPK activation and proliferation in SEG-1 cells induced by acid exposure could be blocked by pretreatment with disodium 4,4′-diisothiocyanatostilbine-2,2′-disulfonate (DIDS), which prevents intracellular acidification by inhibiting the Cl -/HCO3- exchanger. In conclusion, in SEG-1 cells, extracellular acid exposure causes intracellular acidification, which activates MAPK and causes proliferation. The magnitude of these effects is pH dependent, and the effects can be inhibited by preventing intracellular acidification with DIDS.
AB - Abundant epidemiological evidence links acid reflux to adenocarcinoma in Barrett's esophagus, but few studies have examined the cellular mechanisms by which acid promotes this neoplastic progression. We hypothesized that extracellular acid exposure causes intracellular acidification that triggers MAPK signaling and proliferation in Barrett's epithelial cells. We tested that hypothesis in a Barrett's-derived esophageal adenocarcinoma cell line (SEG-1). SEG-1 cells were exposed to varying concentrations of acid, and intracellular pH (pHi) was measured by 2′,7′-bis-(2-carboxyethyl)-5-(and- 6)-carboxyfluorescein microfluorimetry. After acid exposure, ERK and p38 MAPK activation were measured by Western blot analysis and an immune complex kinase assay. Proliferation was measured by Coulter counter cell counts and a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide incorporation assay. Exposure of SEG-1 cells to solutions with a pH between 3 and 6.5 caused a rapid, reversible decrease in pHi to a level approximately equal to extracellular pH. Acid exposure caused a rapid activation of both ERK and p38 MAPKs and also resulted in pH-dependent increases in cell number, with a maximum increase of 41% observed at pH 6.0. The MAPK activation and proliferation in SEG-1 cells induced by acid exposure could be blocked by pretreatment with disodium 4,4′-diisothiocyanatostilbine-2,2′-disulfonate (DIDS), which prevents intracellular acidification by inhibiting the Cl -/HCO3- exchanger. In conclusion, in SEG-1 cells, extracellular acid exposure causes intracellular acidification, which activates MAPK and causes proliferation. The magnitude of these effects is pH dependent, and the effects can be inhibited by preventing intracellular acidification with DIDS.
KW - Barrett's esophagus
KW - Mitogen-activated protein kinase
KW - Proliferation
KW - pH
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UR - http://www.scopus.com/inward/citedby.url?scp=27644439083&partnerID=8YFLogxK
U2 - 10.1152/ajpgi.00215.2005
DO - 10.1152/ajpgi.00215.2005
M3 - Article
C2 - 16081761
AN - SCOPUS:27644439083
SN - 0193-1857
VL - 289
SP - G991-G997
JO - American Journal of Physiology - Gastrointestinal and Liver Physiology
JF - American Journal of Physiology - Gastrointestinal and Liver Physiology
IS - 6 52-6
ER -