Abstract: Objective The aim of this study was to investigate the effects of shikonin, a herbal medicine, on proliferation,apoptosis and phosphatidylinositol 3-kinase (PI3K)/protein kinase (Akt)/nuclear transcription factor-κB (NF-κB) signaling pathway protein expression in HepG2 cells in vitro. Methods HepG2 cells in logarithmic growth phase were treated with different concentration [0(control), 1, 2.5 and 5 μmol/L of shikonin for 48h. The proliferation inhibition rate of HepG2 cells was detected by MTT assay, the apoptosis by flow cytometry and the expression of apoptosis-related proteins (Bax, Bcl-2, Caspase-3), autophagy-related proteins (LC3-I, LC3-II, p62) and PI3K/Akt/NF-κB proteins were detected by Western bloting. Results After intervention for 48 h, the proliferation inhibition rates of cells from low, middle and high dose of shikonin were (23.7±3.5)%, (36.2±6.1)% and (56.9±8.3)%, all significantly higher than [(0.0±0.0)%, P<0.05]in the control, and theapoptosis rates were (19.2±5.3)%, (37.4±7.6)% and (58.6±8.8)%, also significantly higher than [(2.5±1.2)%, P<0.05]in the control; the apoptosis-related protein expression Bax/Bcl-2 ratio and relative expression of Caspase-3 were (1.3±0.2) and (2.7±0.3), (8.2±0.6) and (0.45±0.10), and (0.78±0.16) and (0.95±0.21), all significantly higher than [(0.6±0.1) and (0.18±0.06), respectively, P<0.05]in the control; the autophagy-related protein expression LC3-II/LC3-I ratio were (1.25±0.08), (1.43±0.10) and (1.76±0.22), significantly higher than [(0.96±0.08), P<0.05]in the control, while the relative expression of p62 were (0.81±0.09), (0.62±0.15), (0.43±0.08), significantly lower than that [(1.06±0.05), P<0.05]in the control, and the PI3K, Akt and p65 protein expression were [0.64±0.16), (0.51±0.12) and (0.32±0.06)], [(0.54±0.17), (0.37±0.05) and (0.05±0.01), and [(0.63±0.15), (0.52±0.10) and (0.36±0.09)], all significantly lower than [(0.84±0.13), 0.76±0.15) and (0.89±0.11), respectively, P<0.05]in the control. Conclusion Shikonin promotes apoptosis and autophagy of HepG2 cells in vitro, which might be related to the inhibition of PI3K/Akt/NF-κB signaling pathway protein expression.

Key words: HepG2 cells, Shikonin, phosphatidylinositol 3-kinase, Protein kinase, Nuclear transcription factor-κB, In vitro