Signaling in H2O2-Induced Increase in Cell Proliferation in

Mechanisms whereby acid reflux may accelerate the progres-sion from Barrett’s esophagus (BE) to esophageal adenocarci-noma (EA) are not fully understood. We have previously shown that NADPH oxidase NOX5-S generates reactive oxygen spe-cies (ROS) when Barrett’s metaplastic cells are exposed to acid. Besides metaplastic cells, other H2O2-producing cells (e.g., inflammatory cells) present in BE mucosa may produce additional ROS, which may also affect metaplastic cells con-tributing to esophageal tumorigenesis. In this study, we investi-gate whether exogenous H2O2 stimulates cell proliferation by increasing NOX5-S expression. Low dose (1013 M) of H2O2 significantly increased thymidine incorporation, NOX5-S mRNA, and protein expression in a Barrett’s EA cell line FLO. H2O2-induced increase in NOX5-S expression was significantly inhibite