IN-VIVO EFFECT OF SOMATOSTATIN ANALOG, LANREOTIDE, AND/OR GRP ANTAGONIST, BIM-26226, ON THE GROWTH OF COLON-CANCER PERITONEAL CARCINOMATOSIS IN THE RAT

Abstract

The effect of somatostatin analogue, lanreotide, and bombesin/GRP antagonist, BIM 26226, on the growth of colon cancer peritoneal carcinomatosis in the rat was studied. BDIX rats were i.p. injected with DHD/K12 rat colon cancer cells at day 0 and received from day 3 either lanreotide, BIM 26226, combination of treatments or peptide solvents. At sacrifice, an day 45, no significant difference between groups was observed for peritoneal tumor growth, hepatic metastases, ascite volume and labeling indices in normal colonic mucosa and tumoral tissues. Survival times were similar in other lanreotide-treated and control groups. However, BIM 26226 decreased plasma gastrin level, consistently with a physiological effect of this peptide. Ln all groups, somatostatin and bombesin receptors were found on mucosal and tumoral tissues. Interestingly, bombesin receptor number was higher in severe than in minor cancer stages, contrarily to that of somatostatin receptors. Moreover, an up-regulation of somatostatin and bombesin receptors was observed in BIM 26226- and lanreotide-treated group tumors, respectively, Despite the presence of these specific receptors, lanreotide and BIM 26226 were inactive on tumor growth in this model.