Vorinostat Enhances Chemosensitivity To5-fluorouracil And Oxaliplatin In Hepatocellular Carcinoma

Part1Vorinostat enhances chemosensitivity to5-fluorouracil in hepatocellular carcinoma via inhibition of thymidylate synthaseObjectives:To study the combination of vorinostat and5-fluorouracil and investigate if they had synergism in hepatocellular carcinoma (HCC) cells.Methods:HepG2, SMMC7721and BEL7402cells were treated with vorinostat and/or5-fluorouracil (5-FU). Cell viability assay, colony formation assay, soft agarose assay, cell cycle analysis, apoptosis analysis, reverse transcription-PCR analysis, western blotting, immunohistochemistry and xenograft tumorigenicity assay were performed.Results:Both vorinostat and5-FU inhibited the proliferation of HepG2, SMMC7721and BEL7402cells. The combination of vorinostat and5-FU resulted in a combination index of less than1and a dose-reduction index value of above1in the three cell lines indicating a synergistic effect. Co-treatment of vorinostat and5-FU led to G0/G1phase arrest and caspase-dependent apoptosis. Co-administration of vorinostat and5-FU inhibited tumorigenicity both in vitro and in vivo.5-FU alone enhanced the expression of thymidylate synthase (TS) which was down-regulated by vorinostat.Conclusion:The combination of vorinostat and5-FU has a synergistic effect in HCC. The co-treatment inhibits cell growth and tumorigenicity in vitro and in vivo via the induction of cell cycle arrest, apoptosis through the inhibition of TS. We would predict that combination of5-FU with vorinostat may be of benefit in the treatment of HCC. Part2Vorinostat enhances chemosensitivity to oxaliplatin in hepatocellular carcinoma via inhibition of Notch pathwayObjectives:To investigate the combination of vorinostat and oxaliplatin to explore whether they have synergism in HCC cells.Methods:SMMC7721, BEL7402and HepG2cells were treated with vorinostat and/or oxaliplatin. Cytotoxicity assay, tumorigenicity assay in vitro, cell cycle analysis, apoptosis analysis, western blotting analysis, animal model study and immunohistochemistry were performed.Results:Vorinostat and oxaliplatin attenuated the proliferation of SMMC7721, BEL7402and HepG2cells. The combination index values were all below1and the dose reduction index values were all above1in the three cell lines indicating a synergistic effect after the combination of the two agents. Co-administration of vorinostat and oxaliplatin induced G2/M phase arrest, triggered caspase-dependent apoptosis and prohibited tumorigenicity both in vitro and in vivo. Vorinostat down-regulated the expression of Notch pathway induced by oxaliplatin. Conclusion:Co-treatment with vorinostat and oxaliplatin synergistically inhibits HCC cell proliferation and tumorigenicity both in vitro and in vivo through the induction of cell cycle arrest and apoptosis via inhibition of Notch pathway. Our results predict that combination of vorinostat and oxaliplatin may be useful in the treatment of advanced HCC.