title: Differences in activity and phosphorylation of MAPK enzymes in esophageal squamous cells of GERD patients with and without Barrett's esophagus.
abstract: We hypothesized that, in esophageal squamous epithelial cells, there are differences among individuals in the signal transduction pathways activated by acid reflux that might underlie the development of Barrett's esophagus. To explore that hypothesis, we immortalized nonneoplastic, esophageal squamous cells from patients with gastroesophageal reflux disease (GERD) with (NES-B3T) and without (NES-G2T) Barrett's esophagus and used those cells to study acid effects on MAPK proteins. During endoscopy in patients with GERD with and without Barrett's esophagus, we took biopsy specimens from the distal squamous esophagus to study MAPK proteins before and after esophageal perfusion with 0.1 N HCl. We used immunoblotting and Western blotting to study MEK1/2 phosphorylation at two activating sites (serines 217/221), MEK1 phosphorylation at an inhibitory site (threonine 286), and MEK1/2 activity. After acid exposure, both cell lines exhibited increased MEK1/2 phosphorylation at the activating sites; the NES-B3T cells had higher levels of MEK1 phosphorylation at the inhibitory site, however, and only the NES-G2T cells showed an acid-induced increase in MEK1/2 activity. Similarly, in the squamous epithelium of patients with GERD with and without Barrett's esophagus, acid perfusion increased MEK1/2 phosphorylation at the activating sites in both patient groups; the Barrett's patients had higher levels of MEK1 phosphorylation at the inhibitory site, however, and only the patients without Barrett's demonstrated an acid-induced increase in ERK1/2 phosphorylation. In esophageal squamous cell lines and biopsies from patients with GERD with and without Barrett's esophagus, we have found differences in MAPK pathways activated by acid exposure. We speculate that these differences might underlie the development of Barrett's metaplasia.
authors.affiliation: Department of Medcine, Veterans Affairs North tExas Health Care System and the University of Texas Southwestern Medical School, MC# 111B1, Dallas VA Medical Ctr., 4500 South Lancaster Rd., Dallas, TX 75216, USA.
authors.forename: Hui Ying
authors.initials: HY
authors.lastname: Zhang
authors.forename: Xi
authors.initials: X
authors.lastname: Zhang
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.forename: Deena
authors.initials: D
authors.lastname: Thomas
authors.forename: Kathy
authors.initials: K
authors.lastname: Hormi-Carver
authors.forename: Frederick
authors.initials: F
authors.lastname: Elder
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Spechler
authors.forename: Rhonda F
authors.initials: RF
authors.lastname: Souza
mesh_terms: D001471:Barrett Esophagus / Q000201:enzymology* / Q000209:etiology / Q000473:pathology; D002461:Cell Line, Transformed; D049109:Cell Proliferation; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D018450:Disease Progression; D054638:Dual Specificity Phosphatase 1 / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology / Q000528:radiation effects; D004945:Esophagoscopy; D004947:Esophagus / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology / Q000528:radiation effects; D005744:Gastric Acid / Q000378:metabolism; D005764:Gastroesophageal Reflux / Q000150:complications / Q000201:enzymology* / Q000473:pathology; D006801:Humans; D006851:Hydrochloric Acid / Q000494:pharmacology; D048369:MAP Kinase Kinase 1 / Q000378:metabolism; D048370:MAP Kinase Kinase 2 / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000528:radiation effects; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C482128:MAP2K2 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; C482125:MAP2K1 protein, human; C517019:DUSP1 protein, human; D054638:Dual Specificity Phosphatase 1; D006851:Hydrochloric Acid