Abstract: BACKGROUND ＆ AIM: To examine the inhibitory effects of Phellinus linteus intracellular polysaccharide(PLIP) on proliferation of leukemic cell line K562, and to explore its preliminary mechanisms. MATERIALS AND METHODS: The suppression of cellular growth was detected by MTT assay and trypan blue rejection. Apoptosis was studied by using Hoechst_PI fluorescence staining, DNA agarose gel electrophoresis,and flow cytometry. RESULTS: The PLIP could significantly inhibit the proliferation of K562 cells (P<0.05), and the highest inhibition rate could reach 52.55％ at the dose of 400 μg/ml,IC50 was 262.36 μg/ml. The apoptosis rates for 100 μg/ml,200 μg/ml,400 μg/ml were 5.72％,13.57％,19.39％,respectively, and morphologic and physiologic changes of apoptosis in K562 cells were induced . CONCLUSION: PLIP could significantly inhibit proliferation of K562 cells, and the mechanism responsible for the effect might involve the induction of apoptosis and the effects on cell cycle.

Key words: Phellinus linteus, intracellular polysaccharide, K562, apoptosis