Inhibitory effect of oridonin on proliferation of RPMI8226 cells and the possible underlying mechanism

ObjectiveTo observe the effects of oridonin on proliferation and apoptosis of myeloma RPMI8226 cells and to investigate the potential underlying mechanisms.MethodsRPMI8226 cells were treated with various concentrations of oridonin. Cell proliferation was analyzed using the thiazolyl blue tetrazolium bromide method. Ultramicrostructure was observed by transmission electron microscopy. Annexin-V/PI staining and flow cytometry was performed to determine cell apoptosis. Expression of apoptosis-related proteins was evaluated by western blot analysis.ResultsOridonin suppressed the proliferation of RPMI8226 cells and induced apoptosis in a time- and dose-dependent manner. Transmission electron microscopy confirmed apoptotic morphology upon treatment with 20 µmol/L oridonin and western blot revealed decreased expressions of the apoptosis suppressors survivin, Bcl-2 and pro-caspase-3 proteins, and the increased expression of the apoptosis inducer Bax.ConclusionOur results show that oridonin exhibits an inhibitory effect on the proliferation of RPMI8226 cells and induces apoptosis. This is associated with altering the balance between Bcl-2 and Bax protein expressions and decreased survivin and pro-caspase-3 expressions.