THE EFFECT OF TUMOR BURDEN ON ORNITHINE DECARBOXYLASE ACTIVITY IN MICE

AbstractPolyamines are essential for cell growth of normal and neoplastic tissue. α-Difluoromethylornithine (DFMO) is a known irreversible inhibitor or ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine biosynthesis. The purpose of this study was to examine the effects of tumor burden on ODC in tissues of tumorbearing compared with tumor-free mice. Twenty-eight male Balb/c mice were divided into four groups of 7 each. Groups 1 and 2 were inoculated subcutaneously with 10 X 106 MC-26 mouse colon adenocarcinoma cells. Groups 3 and 4 were kept as tumor-free controls. Ten days after inoculation, groups 2 and 4 were injected with DFMO (200 mg/kg) intraperitoneally (IP) while Groups 1 and 3 received saline. Two hours after the injection of DFMO the animals were sacrificed. The tumor, pancreas, kidney, and liver were excised and analyzed for ODC activity. DFMO caused a significant reduction (compared with controls that did not receive DFMO) in the ODC activity of tumors; however, ODC activity o...