title: Antitumor efficacy of a recombinant adenovirus encoding endostatin combined with an E1B55KD-deficient adenovirus in gastric cancer cells.
abstract: BACKGROUND
  Gene therapy using a recombinant adenovirus (Ad) encoding secretory human endostatin (Ad-Endo) has been demonstrated to be a promising antiangiogenesis and antitumor strategy of in animal models and clinical trials. The E1B55KD-deficient Ad dl1520 was also found to replicate selectively in and destroy cancer cells. In this study, we aimed to investigate the antitumor effects of antiangiogenic agent Ad-Endo combined with the oncolytic Ad dl1520 on gastric cancer (GC) in vitro and in vivo and determine the mechanisms of these effects.
  
  
  METHODS
  The Ad DNA copy number was determined by real-time PCR, and gene expression was assessed by ELISA, Western blotting or immunohistochemistry. The anti-proliferation effect (cytotoxicity) of Ad was assessed using the colorimetry-based MTT cell viability assay. The antitumor effects were evaluated in BALB/c nude mice carrying SGC-7901 GC xenografts. The microvessel density and Ad replication in tumor tissue were evaluated by checking the expression of CD34 and hexon proteins, respectively.
  
  
  RESULTS
  dl1520 replicated selectively in GC cells harboring an abnormal p53 pathway, including p53 mutation and the loss of p14(ARF) expression, but did not in normal epithelial cells. In cultured GC cells, dl1520 rescued Ad-Endo replication, and dramatically promoted endostatin expression by Ad-Endo in a dose- and time-dependent manner. In turn, the addition of Ad-Endo enhanced the inhibitory effect of dl1520 on the proliferation of GC cells. The transgenic expression of Ad5 E1A and E1B19K simulated the rescue effect of dl1520 supporting Ad-Endo replication in GC cells. In the nude mouse xenograft model, the combined treatment with dl1520 and Ad-Endo significantly inhibited tumor angiogenesis and the growth of GC xenografts through the increased endostatin expression and oncolytic effects.
  
  
  CONCLUSIONS
  Ad-Endo combined with dl1520 has more antitumor efficacy against GC than Ad-Endo or dl1520 alone. These findings indicate that the combination of Ad-mediated antiangiogenic gene therapy and oncolytic Ad therapeutics could be one of promising comprehensive treatment strategies for GC.
authors.affiliation: State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou 510060, China. liuranyi@mail.sysu.edu.cn.
authors.forename: Li-xia
authors.initials: LX
authors.lastname: Li
authors.forename: Yan-ling
authors.initials: YL
authors.lastname: Zhang
authors.forename: Ling
authors.initials: L
authors.lastname: Zhou
authors.forename: Miao-la
authors.initials: ML
authors.lastname: Ke
authors.forename: Jie-min
authors.initials: JM
authors.lastname: Chen
authors.forename: Xiang
authors.initials: X
authors.lastname: Fu
authors.forename: Chun-ling
authors.initials: CL
authors.lastname: Ye
authors.forename: Jiang-xue
authors.initials: JX
authors.lastname: Wu
authors.forename: Ran-yi
authors.initials: RY
authors.lastname: Liu
authors.forename: Wenlin
authors.initials: W
authors.lastname: Huang
mesh_terms: D000256:Adenoviridae / Q000187:drug effects / Q000378:metabolism*; D017501:Adenovirus E1B Proteins / Q000378:metabolism; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D043169:Endostatins / Q000494:pharmacology / Q000627:therapeutic use*; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D050504:Oncolytic Viruses / Q000187:drug effects / Q000378:metabolism; D011995:Recombination, Genetic / Q000235:genetics*; D015398:Signal Transduction / Q000187:drug effects; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000473:pathology; D016896:Treatment Outcome; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D014764:Viral Proteins / Q000378:metabolism*; D014779:Virus Replication / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D017501:Adenovirus E1B Proteins; D000970:Antineoplastic Agents; C553319:E1B55K protein, adenovirus; D043169:Endostatins; D016159:Tumor Suppressor Protein p53; D014764:Viral Proteins