INDUCTION OF APOPTOSIS IN HUMAN LEUKEMIA K562 CELLS BY ALPHA-ANORDRIN

AIM: To study antitumor action of alpha-anordrin (Ano). METHODS: Morph ological assessment of apoptosis was performed with light microscope a nd electron microscope. Membrane integrity was determined by trypan bl ue exclusion method. Endonucleolysis was assessed by agarose gel elect rophoresis and flow RESULTS: Exposure of K562 cells to Ano 2.5 - 50 mu mol . L(-1) for 48 h resulted in growth arrest, Ano 50 mu mol . L(-1) inhibited the growth of K562 cells by 67%. Cells were mainly blocked to progress through S-phase and arrested at G(1) phase. After treatmen t of K562 cells with Ano, marked morphological changes including conde nsed chromatin, nuclear fragmentation, and reduction in volume were ob served. Agarose gel electrophoresis of DNA from cells treated with Ano for 24 - 48 h revealed ''ladder'' pattern, typical features of apopto sis, and near 70% of cells underwent apoptosis as determined by flow c ytometry. The S-phase cells were more susceptible to apoptosis. Despit e extensive cleavage of DNA and nuclear fragmentation, the cell membra ne of Ano-treated cells remained intact, excluding trypan blue. Apopto tic cells were detected as early as 8 h after Ano (50 mu mol . L(-1)) treatment. CONCLUSION: Ano induces apoptosis in K562 cells.