Abstract: Objective To investigate the inhibitory effect and related mechanisms of Brucea oil on proliferation of H22 hepatoma cell line. Methods H22 cells cultured in vitro were incubated with different concentration of Breucea oil （10~160 μg/ml） and cell proliferation was determined by MTT assay；Mice bearing H22 tumors were treated with Breacea oil for 10 days，and then the mice were scarified and tumor inhibitory rate， spleen index and thymus index were calculated；MTT was performed to detect the proliferation of spleen cells from tumor-bearing mice；The serum TNF-α was measured by enzyme-linked immunosorbent assay and serum transforming growth factor-α （TGF-α） levels by radioimmunoassay. Result The cell proliferation was inhibited by Brucea oil to 34.1%~52.31% of that of in the control at concentrations of 10 to 160 μg/ml；At concentration of 25 and 50 mg·kg-1，the tumor mass in tumor-bearing mice were reduced to （1.095±0.301） g and （0.920±0.250） g，respectively，and serum TGF-α levels decreased to（11.172±0.639） pg/ml and （14.438±0.587） pg/ml，respectively，significantly lower than those in non-treated tumor-bearing mice[（1.867±0.554） g and （16.354±0.762） pg/ml，respectively]；In contrast，serum TNF-α levels increased to（28.132±2.456） pg/ml and（26.521±3.267）pg/ml，respectively，significantly higher than that in non-treated tumor-bearing mice[（20.231±2.614） pg/ml，P<0.05]；Brucea oil also promoted the proliferation of spleen cells，but had no significant effect on the spleen index and thymus index as compared to those in tumor-bearing mice. Conclusion Brucea oil inhibits the proliferation of H22 cells in vitro and in vivo，and the anti-tumor effect might be related to the regulation of spleen cells in tumor-bearing mice.

Key words: H22 cell line, Brucea oil, Proliferation, Spleen cells, Tumor necrosis factor-α, Transforming growth factor-α