Objective   To investigate whether difluromethylornithine (DFMO) can be used in the treatment of human leukemia.    Methods   The cell proliferation was detected by MTS [3-(4

5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium)] assay after treatment of human lymphocyte Jurkat cells by DFMO (0 to 10 mmol/L) for 24 to 72 h. Enzyme activity of spermine oxidase (SMO) and acetylpolyamine oxidase (PAO) was determined by chemiluminesence assay. DNA fragmentation assay was used to evaluate cell apoptosis. Fluorescent dye assay was performed to determine the changes in mitochondrial membrane potential. Western blotting was used to determine Bax content. Casepase-3 enzyme activity was measured by spectrophotometric method.    Results   DFMO treatment inhibited the proliferation of Jurkat cells significantly in a dosage- and time-dependent manner (P0.01). When DFMO concentration was 10 mmol/L

the inhibitory rate for cell growth was 33% in 24 h

38% in 48 h and 49% in 72 h respectively. DFMO treatment resulted in DNA fragmentation

promoted translocation of Bax from the cytoplasma to the mitochondria and increased caspase-3 activity by 46% (P0.05) accompanied by a significant reduction in the mitochondrial membrane potential in Jurkat cells

reducing 29% at 2 mmol/L DFMO and 53% at 5 mmol/L DFMO (P0.01). DFMO promoted the activity of SMO  by 1.1fold (P0.05) but no inducible effect on PAO activity in Jurkat cells.    Conclusion   DFMO can inhibit cell growth and induce apoptosis in human leukemia Jurkat cells.