Effects of a long-acting somatostatin analog, octreotide (SMS), cysteamine (CSH), tripeptide colon mitosis inhibitor (CMI), and of cytostatic agent 5-fluorouracil on growth of transplantable murine colonic cancer Colon 38 were investigated. Tumor weight and bromodeoxyuridine (BrDU) incorporation into the tumoral cell nuclei were considered as indices of the tumor growth tumor growth. BrDU labelling was also evaluated in non-neoplastic colon. It was found that only the treatments with 5-FU alone and 5-FU plus SMS resulted in a statistically significant decrease of the tumor weight. In turn, a statistically significant reduction in tumor cell proliferation (measured by BrDU incorporation) was found only after simultaneous treatment with 5-FU and SMS. In contrast to the action in tumors, SMS did not enhance the 5-FU effect on cell proliferation in the non-neoplastic colon. Some tendencies towards lower tumor weights and cell proliferation indices was also observed after other treatments. This study suggests that SMS and 5-FU act synergistically on the growth of the investigated tumor.

Keywords: colonic cancer, somatostatin, octreotide, Cysteamine, colon mitosis inhibitor, 5-fluorouracil