Vasoactive intestinal peptide inhibits the growth of hamster pancreatic cancer but not human pancreatic cancer in vivo.

We have previously shown that hamster H2T pancreatic ductal cancer has a receptor for vasoactive intestinal peptide (VIP) which is not present on a cell line of human pancreatic ductal cancer (MIA). The purpose of this study was to examine the effect of chronic administration of VIP on the growth of both H2T hamster pancreatic carcinoma and MIA human pancreatic carcinoma in vivo. The growth of H2T was studied in hamsters; a control group of six hamsters received 0.1% bovine serum albumin (BSA) in saline, and two treatment groups of six hamsters each received VIP (1 and 10 nmol/kg), all administered three times a day by i.p. injection for 35 days. Both doses of VIP inhibited the growth of H2T tumor (tumor area, weight, DNA, RNA, and protein content). The growth of MIA was studied in athymic Balb/c mice, one group of 10 received 0.1% BSA and the other 10 received VIP (1 nmol/kg), both three times a day by i.p. injection for 3 months. There was no difference in tumor growth rate between the two groups. Treatment with VIP did not have any effect on body weight or size of the normal pancreas in either the hamsters or the mice. We conclude that the differential response of hamster and human pancreatic cancer to VIP treatment may be due to the presence or absence of VIP receptors.