Mitogen-activated protein kinases mediate peroxynitrite-induced cell death in human bronchial epithelial cells

Peroxynitrite, formed by the reaction of nitric oxide ( NO.) with superoxide anions (O-2(-.)), may play a role in the pathophysiology of inflammation. The effects of 3-morpholinosydnonimine (SIN-1), a peroxynitrite generator, on the human bronchial epithelial cell line BEAS-2B, were examined. SIN-1 exposure resulted in cell death in a time- and dose-dependent manner. Depletion of intracellular glutathione increased the vulnerability of the cells. Pretreatment with Mn(III) tetrakis(N-methyl-4'-pyridyl) porphyrin ( MnTMPyP) or hydroxocobalamin (HC), O-2(-.) and NO. scavengers, respectively, reduced significantly SIN-1-induced cell death ( 18.66 +/- 3.57 vs. 77.01 +/- 14.07 or 82.20 +/- 9.64, % cell viability SIN-1 vs. MnTMPyP or HC). Moreover, the mitogen-activated protein kinases ( MAPK) p44/42 (ERK), p38, and p54/46 (JNK) were also activated in a time- and concentration-dependent manner. PD-98059 and SB-239063, specific inhibitors of ERK and p38 MAPK pathways, failed to protect cells against 1 mM SIN-1. However, PD-98059 partially inhibited (60% cell survival) SIN-1 effects at less than or equal to0.25 mM, and this was increased with the inclusion of SB-239063. Therefore, MAPKs may mediate signal transduction pathways induced by peroxynitrite in lung epithelial cells leading to cell death.