Neuropeptide Y in neuroblastoma: increased concentration in metastasis, release during surgery, and characterization of plasma and tumor extracts.

Five children with neural crest tumors (two ganglioneuromas, one ganglioneuroblastoma, and two neuroblastomas) were investigated regarding neuropeptide Y-like immunoreactivity (NPY-LI) in tumor tissue and plasma at diagnosis and during surgery. Radioimmunoassay of extracted plasma revealed higher NPY-LI at diagnosis of neuroblastoma (640 and 230 pmol/L resp) than ganglioneuroblastoma or ganglioneuroma (74, 45, and 26 pmol/L resp). During surgery of neuroblastoma plasma NPY-LI increased two- to four-fold while no peroperative increase was seen in the other children. NPY-LI was considerably higher in neuroblastoma tissue (220 pmol/g and 144 pmol/g) than in ganglioneuroblastoma (40.2 pmol/g), ganglioneuroma (0.6 and 4.4 pmol/g), or healthy adrenal tissue (5.5 pmol/g). The highest NPY-LI concentration was found in neuroblastoma metastasis, 3,091 pmol/g. Gel-permeation chromatography of a neuroblastoma tumor showed that a majority of NPY-LI was representing intact NPY (NPY 1-36) while metastasis and plasma from the same child mainly contained smaller immunoreactive fragments. High concentrations of systemic NPY in neuroblastoma patients are of tumoral origin. Plasma levels of NPY and its fragments can be useful in diagnosing and monitoring neuroblastoma, and for early detection of relapse or metastatic disease. A possible involvement of NPY in neuroblastoma tumor growth and spread deserves further investigation.