The effect of cinobufacini injection on DNA topoisomerase I of human hepatocellular carcinoma HepG-2 cells

Background and purpose:The cinobufacini injection is a traditional antitumor drug.However,its mechanism is still unclear.The purpose of this study was to observe the effect of cinobufacini injections in DNA TOPOⅠ of human hepatocellular carcinoma HepG-2 cells.Methods:The cells that were proliferated were assessed by MTT assay.Cell cycles were shown through FCM.TOPOⅠmRNA expression was analyzed through RT-PCR.The activity of TOPOⅠ was measured by TOPOⅠ mediated super coiled PBR322 relaxation.Supercoiled PBR322 was also used to determine the direct DNA breakages.Results:Cinobufacini injections significantly inhibited HepG-2 cells proliferation in ways that were dependent on dosages and time.Induced tumor cells arrest at the S-phase.TOPOⅠ mRNA expression decreased in a manner that was dependent on dosages which inhibited the TOPOⅠ mediated DNA relaxations.However,the cinobufacini injections could not directly induce DNA breakage at any concentration.Conclusion:Cinobufacini injections can inhibit human hepatocellular carcinoma HepG-2 cells proliferation.The regulation of topoisomerase Ⅰ activity and mRNA expression may be one of the mechanisms that causes the cinobufacini injection to contribute against tumor.