Shikonin inhibits the proliferation of breast cancer cell lines in vitro and in vivo

Abstract

Objective To further examine the effects of shikonin on breast cancer cells. Methods Four typical breast cancer cell lines were used. The effects of shikonin were evaluated through a series of experiments in vitro and in vivo. Results The cell counting kit-8 (CCK-8) assay revealed shikonin inhibited proliferation of MCF7, ZR-75-1, SUM1315 and MDA-MB-231 breast cancer cells in a dose-dependent manner. The 50% inhibitory dose (IC50) of MCF7, ZR-75-1, SUM1315 and MDA-MB-231 were 1.165±0.025, 1.043±0.010, 1.595±0.006 and 1.516±0.015 μmol/L, respectively. Flow cytometry demonstrated shikonin promoted cell cycle arrest in the G1 phase and induced cell apoptosis. The apoptosis rate of MCF7, ZR-75-1, SUM1315 and MDA-MB-231 were 12.1±0.7 (P=0.001), 9.1±0.4 (P=0.001), 15.0±0.9 (P=0.001), 15.3±1.3 (P=0.001), respectively. When compared with control group, the percentages of G1 phase were 15.8±0.7 (P=0.019), 32.3±2.0 (P=0.038), 45.0±2.5 (P=0.010), 15.8±0.4 (P=0.001), respectively. Moreover, shikonin significantly reduced the growth of tumor xenografts derived from SUM1315 breast cancer cells in nude mice. And the efficacy was associated with shikonin concentrations. A statistical difference was found between Group C and A on the 7th day (P=0.047). On the 9th day, there was statistical difference between Group C and A(P=0.011), so as Group C and B (P=0.005). On the 11th day, the comparison between any two groups have statistical significance (A vs. B: P=0.046; B vs. C: P=0.024; A vs. C: P=0.007). Conclusion The study demonstrates shikonin can inhibit the proliferation of breast cancer cell lines in vitro and in vivo. Key words: Shikonin; Breast cancer; Proliferation