Objective      To study the molecular mechanism of oridonin (ORI) in inhibiting proliferation and inducing apoptosis of human osteosarcoma cell line 143B.   Methods      143B cells were treated with different doses of ORI in a certain time before being used in the experiment. The proliferation inhibitory effect of ORI was tested by crystal violet staining and Western blotting. The effect of inducing apoptosis was detected by Annexin V-EGFP staining and Western blotting. The influence on WNT/β-catenin signal pathway was investigated by RT-PCR and Western blotting. After Si-β-catenin or Ad-β-catenin was used to silence or over-express β-catenin in 143B cells

the proliferation inhibitory effect of ORI was tested by crystal violet staining again.   Results        ORI could inhibit the proliferation and induce apoptosis of 143B cells in a concentration-dependent manner. It also suppressed the expression of proliferating cell nuclear antigen (PCNA)

promoted the expression of Caspase 3 and Bad

and decreased the level of β-catenin. The apoptosis of 143B cells was promoted or inhibited by silencing or overexpressing β-catenin.    Conclusion      ORI can inhibit the proliferation and induce the apoptosis of 143B cells in a concentration-dependent manner

which may be associated with the down-regulation of β-catenin.