Secretion of gastrin-releasing peptide by retroperitoneal tumors

Gastrin-releasing peptide (GRP) is a neuropeptide with growth factor activity in vitro for a variety of tumors including neuroblastoma. If GRP is secreted by neuroblastomas, its detection in serum might be an excellent way to both diagnose and monitor this tumor in patients.

Small portions of resected tumor specimens were maintained in tissue culture as tumor explants for 24 hours. The tumors included: 3 ganglioneuromas, 1 neuroblastoma, 1 primitive neuroectodermal tumor, 1 Wilms' tumor, 1 rhabdoid tumor, and 1 benign brachial plexus tumor. Control flasks were maintained simultaneously under identical conditions. After 24 hours of incubation, the tumor-conditioned media and the control media were assayed in duplicate for [GRP] using a radioimmunoassay.

All the conditioned media from the benign tumors contained < 25 pg/mL net GRP, whereas all the malignant tumor-conditioned media contained > or = 45 pg/mL (P = 0.003).

These data suggest that GRP is secreted by pediatric retroperitoneal tumors and that the amount secreted varies directly with the degree of malignancy of the tumor. This study suggests that GRP may be a candidate tumor marker for pediatric retroperitoneal tumors.