COMPARISON BETWEEN VASOACTIVE INTESTINAL POLYPEPTIDE AND PITUITARY ADENYLATE-CYCLASE ACTIVATING POLYPEPTIDE LEVELS IN NEUROBLASTOMA TUMOR-TISSUES

Vasoactive intestinal polypeptide (VIP) is reported to exert an autocr ine control on neuroblastoma cell tumours: VIP is produced by the tumo ur and stimulates cell differentiation. This study tested the hypothes is that the parent peptide, the pituitary adenylate cyclase activating polypeptide (PACAP) may have a similar role. It was found that PACAP mRNA and PACAP were expressed in 12/12 tumours; it was also observed t hat PACAP receptor mRNA and functional PACAP receptors were expressed in 12/12 and 5/9 tumours, respectively. VIP mRNA and VIP were detected in 9/12 tumours, VIP receptor mRNA was expressed in 5/12 tumours and functional VIP receptors were never demonstrated. The tumours having t he highest VIP levels also had the highest PACAP contents and were ass ociated with a watery diarrhoea syndrome due to activation of intestin al VIP receptors, As PACAP recognizes the PACAP receptors and the VIP receptors with the same high affinity it may contribute to the syndrom e and is a likely candidate for an autocrine control of neuroblastoma cell growth and differentiation.