Hydrogen peroxide regulates glucose-regulated protein 78 expression via a cyclooxygenase-2 dependent mechanism

This study was designed to investigate the effect of hydrogen peroxide on the expression of endoplasmic reticulum stress marker glucose-regulated protein 78 (GRP78) in endothelial cells and reveals the possible role of cyclooxygenase in this effect. The porcine endothelial cell line was cultured in 1640 medium. Western blot and immunocytochemistry were used to detect the expression of GRP78. The caspase-12 activity was analyzed with the immune fluorescence method. The results showed that after the endothelial cells were incubated with 250 μM of hydrogen peroxide for 12 h, apoptosis increased, which was antagonized by the cyclooxygenase-2 inhibitor nimesulide or the nonselective cyclooxygenase inhibitor aspirin, but not by the cyclooxygenase-1 inhibitor piroxicam. The expression of GRP78 was induced in endothelial cells after exposure to hydrogen peroxide for 12 h. The overexpression of GRP78 was inhibited by nimesulide and aspirin, but not by piroxicam. There are no significant differences in caspase-12 activity among all groups. The present study provides evidence that hydrogen peroxide induced GRP78 overexpression in endothelial cells by a mechanism involving cyclooxygenase-2-dependent pathway.