Oxygen radical induced gastric mucosal cell death: apoptosis or necrosis?

Reactive oxygen species (ROS) and resultant oxidative damage is a common pathway for gastric mucosal injury. This study was undertaken to determine whether apoptosis or necrosis was responsible for hydrogen peroxide (a representative ROS)-induced gastric mucosal death and whether caspase cascade blockade could prevent this process. AGS cells (human gastric adenocarcinoma cells) were exposed to hydrogen peroxide (H(2)O(2)), 0.5-2 mM, from 6 to 24 h. Lactic dehydrogenase (LDH) measured necrosis, whereas Caspase-3 and PARP activation and DNA-histone complex formation measured apoptosis. In addition, AGS cells received no pretreatment or preincubation for 1 h with 50-100 microM z-VAD, a pan-caspase inhibitor, and were then treated with 1-2 mM H(2)O(2). With high concentrations of H(2)O(2), cell death was predominantly necrotic, whereas lower concentrations evoked time and concentration dependent apoptosis. Furthermore, z-VAD pretreatment prevented oxidant induced apoptosis and necrosis. Since caspase cascade blockade prevents both processes, our results support the hypothesis that H(2)O(2) induced cell death is predominantly a caspase-mediated apoptosis.