OBJECTIVETo investigate the growth inhibition and apoptosis of gastric cancer cell MKN45 induced by oridonin and its mechanism.

METHODSThe MTT method was used to investigate the inhibitory effect of oridonin on MKN45 cells. The AO/EB and Hoechst 33258 staining were used to observe the cell morphologic changes of apoptosis induced by oridonin. Prophase apoptotic ratio and cell cycle change were evaluated by GuavaEasycyte PCA-96 system. The expressions of Bcl-2, Bax and caspase 3 proteins were determined by Western blot.

RESULTSOridonin significantly inhibited the proliferation of MKN45 cells in dose- and time-dependent manner. Typical apoptotic features of the cells treated with oridonin were found by AO/EB and Hoechest33258 staining. When MKN45 cells were treated with different doses of oridonin for 12 h, the prophase apoptotic ratio was stepped up from 3.3% (untreated group) to 8.7%-17.9%; after 24 h, from 4.8% (untreated group) to 13.9%-29.3%. There was significant difference between treated and untreated groups (P <0.01). After treatment with oridonin for 24 h, MKN45 cells were arrested at G(2)/M phase. Western blot analysis showed up-regulated expression of Bax and caspase-3, and no significant change of Bcl-2, but Bcl-2/Bax ratio decreased significantly.

CONCLUSIONSOridonin significantly inhibits the proliferation of MKN45 cell. Apoptosis of MKN45 induced by oridonin may be associated with the up-regulated expression of Bax and the change of Bcl-2/Bax ratio, thus to activate the caspase pathway.