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

The effect of somatostatin analogue, lanreotide, and bombesin/GRP anta gonist, BIM 26226, on the growth of colon cancer peritoneal carcinomat osis 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 lanreo tide, BIM 26226, combination of treatments or peptide solvents. At sac rifice, an day 45, no significant difference between groups was observ ed for peritoneal tumor growth, hepatic metastases, ascite volume and labeling indices in normal colonic mucosa and tumoral tissues. Surviva l times were similar in other lanreotide-treated and control groups. H owever, 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. Interest ingly, bombesin receptor number was higher in severe than in minor can cer 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 wer e inactive on tumor growth in this model.