Objective: To study the effects of cinobufacini injections on the proliferation and expression of topoisomerase of hepatocarcinoma HepG-2 cells. Method: Experiment were divided into control group and experimental group (cinobufacini injections group 0.105

0.21

0.42 mg·L-1).Cell proliferation was assessed by Methyl Thiazolyl Tetrazolium blue reduction (MTT)assay.Apoptosis was detected by Annexin V/PI staining. Cell cycles were shown through flow cytometry method (FCM). TopoisomeraseⅠ(TopoⅠ)

TopoisomeraseⅡ (Topo Ⅱ) mRNA were analyzed by Reverse transcription-polymerase chain reaction (RT-PCR). Expressions of TopoⅠ

Topo Ⅱ protein were analyzed by Western-blot. Result: Cinobufacini injection significantly inhibited HepG-2 cellproliferation(P<0.05)

induced apoptosis(P<0.05) in a dose and time dependent manner

induced tumor cells arrested at the S-phase a dose dependent manner.Down regulated mRNA and protein expressions of TopoⅠ

Topo Ⅱ(P<0.05)in a dose dependent manner. Conclusion: Cinobufacini injections can inhibit human hepatocellular carcinoma HepG-2 cells proliferation

induced apoptosis and induced tumor cells arrested at the S-phase.The down regulation of TopoⅠ

Topo Ⅱ expressions might be one of the anti-tumor mechanisms of cinobufacini injection.