Reactive oxygen species activate mitogen-activated protein kinases in pancreatic acinar cells

It has been recently reported that kinases that belong to the mitogen-activ ated protein kinase (MAPK) family are rapidly activated by cholecystokinin (CCK) in rat pancreas both in vitro and in vivo. It is known that reactive oxygen species (ROS) play an important role in the pathogenesis of acute pa ncreatitis induced by supraphysiologic stimulation with CCK analogue, cerul ein. The aim of our study was to evaluate whether MAPKs are activated by RO S in pancreatic acini. The activity of MAPK, c-Jun amino-terminal kinase (J NK), and p38 MAPK was determined in isolated rat pancreatic acinar cells by means of Western blotting, with the use of specific antibody that recogniz es active, dually phosphorylated kinases. Incubation of acini with ROS dono rs, hydrogen peroxide (H2O2) and/or menadione (MND), strongly activated all three kinases. Activation of these kinases by ROS, but not by CCK, was sub stantially inhibited by pretreatment of acini with antioxidant N-acetylo-L- cysteine (NAC). Whereas CCK-induced activation of MAPK or JNK was totally o r partially blocked by protein kinase C (PKC) inhibitor GF-109203X, ROS-ind uced activation of MAPK, JNK, and p38 MAPK was PKC independent. In conclusi on, ROS strongly activate MAPK, JNK, and p38 MAPK in pancreatic acinar cell s. It may be of importance in acute pancreatitis, because ROS are involved in the pathogenesis of this disease.