Triple therapy with octreotide, galanin and serotonin induces necrosis and increases apoptosis of a rat colon carcinoma

A rat colonic adenocarcinoma was implanted subcutaneously (s.c.) in nude mice. After 7 days, the animals were divided into different groups. Two groups received subcutaneous injections twice daily with 3 or 6 mug/kg body weight octreotide, galanin and serotonin. Three groups were respectively treated with 20, 30, and 40 mug/kg body weight of the previously mentioned bioactive substances. Control group received only saline solution in the same fashion as treated animals. The treatment lasted for 5 days. The tumour volume and weight, the relative density of blood vessels, of tumour necrotic tissue, of apoptotic nuclei and of proliferating nuclei were measured. Apoptosis was detected by in situ labelling of nuclear DNA fragmentation according to TUNEL method, and proliferation by immunocytochemistry. Morphometry was done with the classical stereological point-counting method. Food consumption, animal weight, faeces weight and its water content were measured for 3 days before and after treatment. Triple therapy with 3 and 6 mug/kg body weight had no effect on any of the parameters measured, except in reducing the relative volume density of tumour blood vessels. Treatment with 20, 30 and 40 mug/kg body weight of the previously mentioned bioactive substances reduced the tumour volume, the relative volume density of blood vessels and increased the relative volume density of necrotic tissue and of apoptotic nuclei (in the 20 mug group). However, there was no difference between treated mice and controls regarding the relative volume density of proliferating nuclei. There was no statistical difference between treated animals regarding food consumption, body weight, faeces weight and its water content before and during treatment. The present study confirms that triple therapy with octreotide, galanin and serotonin causes regression of a rat colon carcinoma. It further showed that optimum treatment dose is 20 mug/kg body weight of each bioactive substance. Moreover, this therapy regime does not show apparent side effects in the experiments carried out on mice. (C) 2002 Elsevier Science B.V. All rights reserved.