Elevated expression of galanin receptors in childhood neuroblastic tumors

The neuropeptide galanin (GAL) has been shown to be present in certain brain tumors. In order to learn more about GAL and its receptors in human tumors of the peripheral nervous system, we investigated the expression of the GAL peptide and the GAL receptors in tumor tissue from childhood neuroblastic tumors. GAL peptide concentrations up to 674 +/- 166 fmol/mg of tissue were detected by radioimmunoassay, but no significant correlation with standard tumor markers or the prognosis of the 14 patients investigated was observed. Ligand binding experiments showed different levels of GAL binding in all 28 primary neuroblastomas and 7 ganglioneuromas investigated. All three human GAL receptor subtypes cloned to date could be detected, with the GALR1 receptor subtype being expressed most prominently. GAL binding did not significantly correlate with genetic markers such as unfavorable DNA ploidy, amplification of the oncogene MYCN and allelic loss of chromosome 1p. However, low galanin binding was significantly correlated with survival (p = 0.021) in this limited analysis of neuroblastic tumor samples. These results raise the possibility that the expression of GAL binding sites may play a role in neuroblastic tumor biology and behavior.