The effect of somatostatin analogue RC-160 on the growth of hepatic metastases of colon cancer was investigated in rats using magnetic nes

The effect of somatostatin analogue RC-160 on the growth of hepatic metastases of colon cancer was investigated in rats using magnetic nes onance imaging. Experimental liver metastatic tumors were established in syngeneic BDIX rats after intrasplenic injection of DHD/K12 colon adenocarcinomacells. Each rat with implanted liver tumors receiveds.c. injections of somatostatin analogue RC-160 (50 @tg/kg)or the vehicle (control) twice a day for 4 weeks,starting 3 weeksafter tumor inocula tion. During the treatment with RC-160, the growth ofliver tumors was studied quantitatively by measuring liver tumor volumes in vivowith magnetic resonance imaging at intervals of 7 days. Chronic administra don of RC-160 inhibited the growth of hepatic metastasesof colon cancer in rats. Significant inhibition of liver tumor growth in RC-160treated rats was observed throughout the treatment. The final liver tumor volume in the treated rats was decreasedby 56.1% as compared to the controls. The treatment with RC-160 reduced the percentage increase in liver tumor volume from 1575 ±674% (mean ±SEM) for the control to 1034±727%in the treated group. The tumor volumedoubling time in treated rats was 3.7 days longer than the controls. The liver tumor growth delay time was 15.1days. At the end of the treatment, the incidence of ascites and the weights of tumorous livers were also do creased by RC-160 treatment. Administration of RC-160 prolonged the median survival time by 13 days in treated rats. In cell cultures, signif icant inhibitory effects of somatostatin-14 and RC-160 on the growth of DHD/K12 colon cancer cells were determined by MTT assay and 13H1thymidine incorporation assay, indicating direct effectsofthese peptides on the growth of colon cancer cells in vitro. These data suggest that administration of RC-160 could inhibit the growth of colon cancer and their hepatic metastases in rats. Somatostatin analogue RC-160 might be considered as a potential newagent for the treatment of patients with hepatic metastases of colorectal cancers.