BOMBESIN INHIBITS GROWTH OF PANCREATIC DUCTAL ADENOCARCINOMA (H2T) INNUDE-MICE

Bombesin (BBS), a tetradecapeptide, stimulates growth of various types of cells, including fibroblasts and human small cell lung cancer, and has been termed the universal ''on-switch'' due to its ability to sti mulate the release of numerous hormones. In addition, BBS receptors ha ve been identified in normal and neoplastic pancreatic tissue. A pancr eatic ductal adenocarcinoma cell line (H2T), established in our labora tory, possesses specific binding sites for BBS. The purpose of this st udy was to examine the effect of BBS on the growth of H2T tumors trans planted into athymic nude mice. H2T cells (5 x 10(6) cells/mouse) were injected s.c. into the interscapular region of the nude mice and then the mice were randomized into two groups (n = 10/group). Mice receive d either 0.1 ml of saline with 0.1% bovine serum albumin (BSA) (contro l) or 0.1 ml BBS (5 mu g/kg) intraperitoneally, three times/day. Tumor area was measured twice weekly until the mice were killed (day 32), w hen tumor and normal pancreas were removed, weighed, and assayed for D NA and protein content. Administration of BBS significantly inhibited H2T tumor area, weight, and DNA and protein content. Conversely, growt h of normal pancreas, removed as an in vivo bioassay so as to ensure t he efficacy of BBS, was stimulated. We conclude that BBS is a growth i nhibitory factor for H2T tumors and that different mechanisms may be r esponsible for the differential growth effects elicited by normal and neoplastic pancreas in response to BBS.