Oridonin inhibits metastasis of human ovarian cancer cells by suppressing the mTOR pathway

Introduction: Oridonin, which is isolated from the Chinese herb Rabdosia rubescens, has been reported to exhibit an anti-tumorous effect on different cancers. In this study, we investigated the molecular mechanism by which oridonin suppresses human ovarian cancer. Material and methods: The inhibition of oridonin on cell proliferation was assessed by CCK8 assay. Cell cycle and apoptosis were analyzed by flow cytometry, staining with propidium iodide (PI) or annexin-V/PI respectively. The metastasis rate was evaluated using a transwell migration assay. The expression of metastasis-associated genes and mTOR pathway related genes were detected by western blot. Results: We demonstrated that oridonin suppressed the proliferation and blocked the cell cycle in G1/S phage and induced apoptosis in SKOV3 and A2780 cells (p < 0.01). We further found that the mTOR signaling pathway was suppressed by the treatment with oridonin, and the activation of the mTOR pathway attenuated the anti-tumorous effect of oridonin in human ovarian cancer cells, suggesting that the mTOR pathway was involved in the anti-tumorous process of oridonin. Additionally, the activation of the mTOR pathway by an exogenous activator reduced the expression level of FOXP3 (p < 0.01), thus providing evidence that FOXP3 is a factor that is necessary for the anti-tumorous effect of oridonin, and is negatively regulated by the mTOR pathway. Conclusions: These results suggested that oridonin suppressed the mTOR signaling pathway, up-regulated the FOXP3 level, and inhibited metastasis of human ovarian cancer cells.