Effects of oridonin on proliferation of HT29 human colon carcinoma cell lines both in vitro and in vivo in mice

Oridonin, an active ditepenoid component isolated from Rabdosia rubescens which is currently one of the most important Chinese traditional herbs, has been reported to exhibit anti-tumor effects in vitro. In this study, the anti-proliferation effect of oridonin against the human colorectal carcinoma cells HT29 was investigated both in vitro and in vivo. MTT assay showed that oridonin inhibited HT29 cells in a time- and dose-dependent manner. Flow cytometric analysis demonstrated that oridonin induced a G2/M phase arrest. Apoptotic bodies were observed by Hoechst 32258 fluorescence staining. Notable apoptosis and decrease of mitochondrial membrane potentials was also detected by flow cytometry. In the in vivo experiments, oridonin (10, 15, 20 mg kg(-1) of body weight, on days 1-12) was injected intraperitoneally into mice 24 h after the mice were incubated with HT29 cells. Inhibition of the solid tumor was observed. As a result, oridonin could inhibit the proliferation of HT29 cells both in vitro and in vivo, and induce apoptosis partly via the mitochondrial pathway.