The spin trapping agent PBN stimulates H2 O2 -induced Erk and Src kinase activity in human neuroblastoma cells

The spin-trap, alpha-phenyl-N-tert-butylnitrone (PBN) has been shown to have neuroprotective properties and may prevent oxidative injury in vivo and in cultured cells. Although PBN quenches reactive oxygen species, the direct mechanism of neuroprotective action is unknown. In the present study, we examined the effects of PBN on the regulation of the mitogen activated kinase Erk and as well as Src family tyrosine kinases, enzymes known to be activated by oxygen species such as H2O2. In SH-SY5Y human neuroblastoma cells, H2O2 induced activation of Erk and Src kinases was markedly potentiated by treatment with PBN. The potentiation by PBN of the Erk and Src kinase activation by H2O2 required extracellular Ca2+ and appeared dependent on voltage sensitive Ca2+ channels. In contrast, PBN did not affect depolarization-dependent or growth factor-dependent Erk and Src kinase phosphorylation. Our results suggest that PBN might have a protective effect on cells by potentiating the anti-apoptotic Erk and Src kinase pathways responding to H2O2, an effect apparently distinct from its ability to trap oxygen free radicals.