Oridonin induced U937 cell apoptosis through ERK pathway

Objective: To study the mechanisms of oridonin-induced U937 cell apoptosis, and to examine the role of ERK MAPK.

Methods: MTT, Hoechst 33258 staining, DNA agarose gel electrophoresis and Western blot analysis were used.

Results: Oridonin inhibited U937 cell growth in a time- and dose-dependent manner. Apoptotic bodies were found with Hoechst 33258 staining after treatment with 27 micromol x L(-1) oridonin. Simultaneously, ERK phosphorylation was significant. ERK inhibitor PD98059 partially blocked the growth-inhibitory effect as well as DNA fragmentation. The expression of antiapoptotic mitochondrial protein Bcl-XL decreased time-dependently, and that of proapoptotic protein Bax increased. However, PD98059 reversed the effect of oridonin on Bcl-XL and Bax.

Conclusions: Oridonin induces U937 cell apoptosis through activation of ERK and alteration of the ratio of Bax/Bcl-XL.