Abstract: Objective To investigate the effect of norcantharidin （NCTD） on proliferation， apoptosis， cell cycle and the activity of nuclear factor （NF）κB on human leukemia cell line K562. Methods The K562 cell was treated with different concentrations of NCTD （0， 10， 25， 50， 100 μmol／L） and the proliferation inhibition rates were measured by CCK-8 kit at 24， 48， 72， 96 h post-treatment. The apoptotic rates at 24 and 48 h together with cell cycle at 48 h after NCTD treatments were evaluated via flow cytometry. The in situ cell death detection kit （Tunnel） was applied to measure the levels of apoptosis at 24 and 48 h post-treatment. As for the activity of NF-κB， levels of p65 subunit of NFκB and IκBα were detected by Western blotting at 48 h posttreatment. Results NCTD in the range 10 to 100 μmol／L could increase the proliferation inhibition rates on K562 cells in a dose- and time- dependent manner （P＜0.05）. In comparison with 0 μmol／L NCTD， there were elevated apoptotic rates and indices at 24 and 48 h posttreatment （P＜0.05）. The treatment with NCTD （10~100 μmol／L） resulted in a higher proportion of cells within G0／G1phase but a lower proportion of cells within S and G2／M phases with significant differences than 0 μmol／L （P＜0.05）. Reduced IκBα but elevated p65 subunit of NFκB were observed only in 10100 μmol／L NCTD （P＜0.05）.
Conclusion NCTD exhibited cytotoxity on K562 cells， possibly by the inhibition of the cell proliferation， induction of apoptosis and down-regulation of the activity of NF-κB.