Proliferative actions of natriuretic peptides on neuroblastoma cells - Involvement of guanylyl cyclase and non-guanylyl cyclase pathways

To identify neural tumor cell lines that could be used as models to study g rowth-related natriuretic peptide actions, we determined the effects of the se peptides on the proliferation of human and rodent neuroblastoma cell lin es. Subnanomolar concentrations of atrial natriuretic peptide (ANP) and typ e C natriuretic peptide (CNP) stimulated proliferation in all four cell lin es. These actions were associated with cGMP elevation and were blocked by a protein kinase G inhibitor. These data imply the involvement of guanylyl c yclase (GC)-coupled natriuretic receptors. However, higher concentrations o f ANP and CNP, and low concentrations of des-[Gln(18), Ser(19), Gly(20), Le u(21) , Gly(22)]-ANP(4-23)-NH2 (desANP(4-23)) (analog for NPR-C receptor) e xerted antiproliferative actions in three of the cell lines. These effects were insensitive to a protein kinase G inhibitor and to HS-142-1, suggestin g that growth-inhibitory actions involved a non-GC receptor. They did not a ppear to involve cAMP, protein kinase X protein kinase C, or calcium mobili zation but were abolished when constitutive mitogen-activated protein kinas e activity was inhibited. Radioligand binding experiments revealed the pres ence of a uniform class of binding sites in NG108 cells and multiple bindin g sites in Neuro2a cells. Northern and reverse transcriptase-polymerase cha in reaction analyses revealed differential gene expression for NPRA/B/C in NG108 and Neuro2a cells. The results indicate that natriuretic peptides sti mulate neuroblastoma cell proliferation through type NPRA/B (GC) receptors. Higher concentrations of ANP and CNP exerted a mitogen-activated protein k inase-dependent antiproliferative action mediated by a non-GC receptor that interacts with desANP(4-23) with relatively high affinity.