38-AMINO ACID FORM OF PITUITARY ADENYLATE-CYCLASE ACTIVATING PEPTIDE INDUCES PROCESS OUTGROWTH IN HUMAN NEUROBLASTOMA-CELLS

Permanent cell lines from human neuroblastoma, a sympathoadrenal malignancy, are known to exhibit a more neuronal phenotype characterized by outgrowth of long processes in response to multiple second messenger analogs. In this report we demonstrate that the 38-amino acid form of a peptide homologous to vasoactive intestinal peptide (VIP), pituitary adenylate cyclase activating peptide (PACAP), as well as the 27-amino acid form of PACAP, induce NB-OK human neuroblastoma cells to extrude cellular processes within 5 hr of treatment with either peptide at 10(-8) M. Treatment of NB-OK cells with PACAP38 or PACAP27 at 10(-8) M for 1 hr also elevates cAMP content greater than 100-fold and inositol lipid turnover 11- to 12-fold. VIP acutely induces process outgrowth and elevates intracellular second messenger levels in NB-OK cells only at higher concentrations, 10(-6) M or greater. In contrast to the equipotency of PACAP27 and PACAP38 in stimulating the outgrowth of processes observed after 5 hr of treatment, PACAP38 is much more potent than PACAP27 when NB-OK cells are scored for process outgrowth after 72 hr of treatment. Correlating with the extended time course over which morphologic changes are seen with PACAP38, cAMP levels remain elevated for a more prolonged time span during treatment with PACAP38 than PACAP27. After 72 hr of treatment with PACAP38 versus treatment with PACAP27, cAMP levels are elevated 10-fold versus 3-fold, respectively. PACAP38 at 10(-8) M also induces process outgrowth in two additional human neuroblastoma lines tested, SMS-KAN and LA-N-1, whereas PACAP27 and VIP at the same concentration are less effective. The effects of PACAP38 on neuroblastoma cells may be a model for neurotrophic activities of PACAP38 via G protein-linked intracellular messengers in human sympathoadrenal cells.