Abstract: AIM: To research the proliferation inhibitory effect of oridonin on human breast cancer MDA-MB-231cells and explore the mechanism of the inhibitory effect. METHODS: MDA-MB-231 cells were incubated with oridonin in vitro. Morphological changes of MDA-MB-231 cells induced by oridonin for 24 h were observed by invert microscrope. The cell viability rate was evaluated by MTT assay. The cell apoptotic rate was evalutated by flow cytometry (FCM). The apoptosis associated protein level of procaspase-3, PARP,Akt, p-Akt, p-GSK 3β was examined by Western blotting. RESULTS: The apoptosis phenomenon of MDA-MB-231 cells induced by oridonin for 24 h could be observed. The apoptosis phenomenon of 24 μmol/L group was more obvious than other groups. The cell viability rate induced by 6,12,24 μmol/L oridonin was decreased and apoptotic rate was increased in a time- and dose-dependent manner (P<0.01). Oridonin cleaved PARP which is the substrate of caspase-3 in a dose-dependent manner(P<0.05). Oridonin also down- regulated the protein level of procaspase-3, phospho-Akt(p-Akt) and phospho-GSK3β(p- GSK3β) in a dose-dependent manner(P<0.05).CONCLUSION: Oridonin can inhibit the proliferation of human breast cancer MDA-MB-231 cells and induce cell apoptosis by inhibiting PI3K/Akt pathway.

Key words: Oridonin, MDA-MB-231, Cell apoptosis