title: Nutlin-3 cooperates with doxorubicin to induce apoptosis of human hepatocellular carcinoma cells through p53 or p73 signaling pathways.
abstract: OBJECTIVE
  Despite recent advances in chemotherapeutic agents for Hepatocellular carcinoma (HCC) treatment, the results of chemotherapy remain unsatisfactory. Doxorubicin (DOX) still represents the cornerstone in HCC chemotherapy, but resistance and toxicity to normal cells are major obstacles to successful chemotherapy. Therefore, new active agents in HCC chemotherapy and agents that increase the chemosensitivity of HCC cells to DOX are still urgently required. Nutlin-3 is a small-molecule inhibitor that acts to inhibit murine double minute-2 (MDM2) binding to p53 or p73, and subsequently activates p53- or p73-dependent apoptosis signaling pathway. This study was designed to investigate whether Nutlin-3 alters cell toxicity to HCC cells following DNA damage and to assess the suitability of DOX/Nutlin-3 as a chemotherapeutic combination in HCC chemotherapy.
  
  
  METHODS
  Four human HCC cells were analyzed using cell proliferation assay, apoptosis assay, western blotting, co-immunoprecipitation and siRNA experiments. Anti-tumoral effects of Nutlin-3/DOX targeting the p53/MDM2 and p73/MDM2 pathways were evaluated in HCC cell lines.
  
  
  RESULTS
  Nutlin-3 enhances the growth inhibition by DOX and potentates the apoptotic effect in all HCC cell lines with different p53 types. Nutlin-3 acts through the disruption of p53-MDM2 binding in HepG2, and the disruption of p73-MDM2 in Huh-7 and Hep3B cell lines with subsequent activation of the apoptotic pathway, which leads to the increase in chemosensitivity to DOX in HCC cells.
  
  
  CONCLUSIONS
  Taken together, our findings suggest that Nutlin-3 will be active in the treatment of HCC and offers new prospects for overcoming DOX resistance.
authors.affiliation: Department of General Surgery, First Affiliated Hospital of Harbin Medical University, No. 23 Youzheng Street, Harbin 150001, Heilongjiang Province, China.
authors.forename: Tongsen
authors.initials: T
authors.lastname: Zheng
authors.forename: Jiabei
authors.initials: J
authors.lastname: Wang
authors.forename: Xuan
authors.initials: X
authors.lastname: Song
authors.forename: Xianzhi
authors.initials: X
authors.lastname: Meng
authors.forename: Shangha
authors.initials: S
authors.lastname: Pan
authors.forename: Hongchi
authors.initials: H
authors.lastname: Jiang
authors.forename: Lianxin
authors.initials: L
authors.lastname: Liu
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000473:pathology; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000502:physiology*; D004317:Doxorubicin / Q000494:pharmacology*; D004357:Drug Synergism; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000473:pathology; D009687:Nuclear Proteins / Q000502:physiology*; D010879:Piperazines / Q000494:pharmacology*; D051736:Proto-Oncogene Proteins c-mdm2 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology*; D000072160:Tumor Protein p73; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*; D025521:Tumor Suppressor Proteins / Q000502:physiology*
chemical_list: D000903:Antibiotics, Antineoplastic; D004268:DNA-Binding Proteins; D007093:Imidazoles; D009687:Nuclear Proteins; D010879:Piperazines; D034741:RNA, Small Interfering; C000606460:TP73 protein, human; D000072160:Tumor Protein p73; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; C482205:nutlin 3; D004317:Doxorubicin; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2