Oridonin enhances in vitro anticancer effects of lentinan in SMMC-7721 human hepatoma cells through apoptotic genes

Abstract

The aim of the present study was to determine the ability of oridonin to enhance the anticancer activity of lentinan (LNT) in SMMC-7721 human hepatoma cells in vitro by using various techniques, including MTT, flow cytometry, quantitative PCR and western blot assays. The results demonstrated that 20 μg/ml was a non-toxic concentration of oridonin for L02 normal liver cells and SMMC-7721 cells, while 0-200 μg/ml of LNT only had anti-proliferative effects on SMMC-7721 cells. LNT at 100 and 200 μg/ml inhibited the growth of SMMC-7721 cells by 22.8 and 60.0%, respectively, and after addition of 20 μg/ml oridonin, the inhibitory rate of 100 and 200 μg/ml LNT was increased to 47.2 and 80.7%, respectively. Oridonin (20 μg/ml) + LNT (200 μg/ml)-treated SMMC-7721 cells showed the highest apoptotic rate, which was 40.5±2.5%, which was higher than that of cells treated with LNT only. LNT raised the mRNA and protein expression of caspase-3, -8 and -9 as well as B-cell lymphoma 2 (Bcl-2)-associated X protein, p53 and p21, while reducing the expression of Bcl-2, Bcl extra large protein, epidermal growth factor (EGF) and EGF receptor expression in SMMC-7721 cells as compared to that in control cells. Treatment with 20 μg/ml oridonin and 200 μg/ml LNT increased these changes of gene expression. From the obtained results, it may be concluded that oridonin raised the in vitro anti-cancer effects of LNT in SMMC-7721 cells. Oridonin may also be used as a sensitizing agent to increase the anticancer activity of LNT in vivo.