ABSTRACT
<p><b>OBJECTIVE</b>To investigate the growth inhibition and apoptosis of gastric cancer cell MKN45 induced by oridonin and its mechanism.</p><p><b>METHODS</b>The 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.</p><p><b>RESULTS</b>Oridonin 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.</p><p><b>CONCLUSIONS</b>Oridonin 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.</p>