Medulloblastoma and other cPNETs possess phenotypic properties common to neuronal progenitor cells and stem cells of the central nervous system (CNS). We hypothesized that central PNETs of childhood share markers of neuroendocrine origin with peripheral PNETs (pPNET) suggesting a common origin for these neoplasms.

We examined the gene expression of the neuropeptides VIP and somatostatin(ss) and the corresponding receptor subtypes (VIPR 1,2; sst1-5) in 5 cell lines and 25 primary tissue samples of PNETs (see table). Following RNA isolation and enzymatic digestion with DNAse, we employed RT-PCR. Southern Hybridization was used as a confirmatory method. To show functionality of the receptors, we performed competitive binding assays on cell membrane preparations of selected cell lines

Table 1
Full size table

Our results for the gene expression of ss, VIP, sst1, sst2, VIPR 1 and VIPR 2 are represented in the table. The genes for sst3-5 were expressed to a lesser extent and more common in cPNETs.

Previous immunohistochemical studies have demonstrated the presence of VIP and somatostatin in cPNETs. These results support a neuroendocrine origin for both cPNET and pPNET. Further studies of neuropeptides and their receptors may help delineate a stage in the development when these tissues diverge into final differentiation patterns.