Abstract: Objective To investigate the effect of shikoninon proliferation of leukemic NB4 cells andthe related mechanism. Methods CCK-8 assay was used to examine the proliferation inhibition of shikonin on NB4 cells. Cell cycle and apoptosis was detected by flow cytometry. Theexpression of c-MYC, ERK and p-ERK were detected by Western blot. The data was analyzed by one -wayANOVA test and ttest using SPSS17.0 softwarepackage.Results Shikonininhibited NB4 cell proliferation in concentration and time dependentmanner(P<0.01). The percentage of cells in G1 phase was increased while was decreased in G2 and S phases(P<0.01). The rate of apoptosis in the shikonin group was obviously higher than control group(P<0.01). Theexpression of c-MYC wasdecreased(P<0.05) and p-ERK was increased(P<0.01). ConclusionsShikoin can inhibit NB4 cells proliferationthrough down-regulation of c-MYC with involvement of ERK pathways.

Key words: shikonin, NB4 cells, proliferation, c-MYC