Background: VIP acts as a neuroendocrine mediator under physiological conditions, with an important role in water and electrolyte secretion in the gut. Recent findings suggest that VIP also promotes growth and proliferation of normal as well as malignant cells. We have investigated the VIP-serum levels in patients with pancreatic cancer and colonic adenocarcinoma as compared to healthy controls. This was accompanied by immunohistochemical investigations and in vitro experiments to further define the role of the peptide in pancreatic and colorectal cancer.
Materials and methods: Serum levels of VIP were evaluated under standardized conditions in a total of 135 patients; 45 patients had metastatic colorectal cancer, 45 suffered from metastatic pancreatic cancer, and 45 healthy volunteers served as controls. Human pancreatic and colorectal carcinoma cell lines were incubated over 5 days with VIP in increasing concentrations.
Results: In healthy controls, a median VIP-serum level of 42.44 +/- 2.540 pg/ml (range, 12.9-98.5 pg/ml) was found, while patients with pancreatic cancer had a median level of 40.58 +/- 3.013 pg/ml (range, 6.9-102.4 pg/ml). In patients with cancer originating in the colon, however, a median serum level of 116 +/- 10.14 pg/ml (range, 51.6-487 pg/ml) was found. While no difference between healthy controls and patients with pancreatic cancer could be detected (p = 0.6381), a significant difference between patients with colorectal cancer and healthy controls (p < 0.0001) and patients with pancreatic cancer (p < 0.0001) was demonstrated. The median VIP-concentrations found in the patients sera for pancreatic and colonic tumor patient groups, 40 pg/ml and 115 pg/ml respectively, had no significant effect on the proliferation of PANC-1 and HT29, inhibited ASPC-1, BxPC3, COLO201 and HCT-15 cells, and stimulated the growth of one pancreatic (CAPAN-1) and one colonic (COLO320DM) cell line under these conditions.
Conclusions: As opposed to pancreatic cancer and healthy controls, patients in our series had elevated serum VIP-levels. Further studies are warranted to evaluate whether VIP can be used as a tumor marker in this disease.