Induction of neurite outgrowth in PC12 cells by the bacterial nucleoside N6-methyldeoxyadenosine is mediated adenosine A2a receptors via cAMP and MAPK signaling pathways

We have previously shown that N-6-methyldeoxyadenosine (MDA) is an inducer of differentiation in several tumor cells. Here we show that in addition to its ability to induce neurite-outgrowth in PC12 cells, MDA also significantly enhances the nerve-growth factor-mediated neurite outgrowth of these cells. Thus, MDA acts synergistically with NGF to repress cdc2 and cdk2 synthesis and to enhance tyrosine hydroxylase synthesis. To further elucidate the mechanisms of action of MDA, we investigated the effect of this drug on various signaling pathways. The neuritogenesis observed in PC12 following NIDA treatment is mediated through activation of adenylyl cyclase in a PKA independent process and through the recruitment of the p44/p42 MAPK pathway. Furthermore, the adenosine A(2a) receptor antagonist ZM 241385 prevents the MDA-induced neuritogenesis, suggesting that MDA mediates its effect via this adenylyl cyclase-coupled A(2a) receptor. Collectively, these findings suggest that, in PC12 cells, the MDA-induced neuritogenesis requires the recruitment of adenosine A(2a) receptors the stimulation of adenylate cyclase, and the activation of the p44/42MAP kinase cascade. (C) 2003 Elsevier Science (USA). All rights reserved.