Shikonin induced breast cancer cell apoptosis via a caspase-dependent mechanism

To investigate the mechanism of apoptosis induced by shikonin in breast cancer cell lines,MTT colorimetric assay was used to examine the growth inhibition.The results showed that shikonin can significantly inhibit cell growth,which was time-and concentration-dependent in the tested four cell lines,and the IC50value was below 10 μmol·L-1 at 24 h.When treated with shikonin,typical apoptotic morphological change,biochemical character and cell cycle arrest in S phase were observed by morphological analysis,Hoechst fluorescence dye testing and FACS analysis.The 85 ku truncated PARP(Poly ADP-ribose Polymerase) was observed in MCF-7 cell treated with shikonin by western blot analysis,furtherly,caspase broad-spectrum inhibitor blocked significantly the apoptotic effect with the decreased level of PARP(85 ku) induced by shikonin in MCF-7 cell.These results indicated that shikonin may induce MCF-7 cell apoptosis through the caspase pathway.