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.