title: Potent antitumoral efficacy of a novel replicative adenovirus CNHK300 targeting telomerase-positive cancer cells.
abstract: OBJECTIVE
  Telomerase reverse transcriptase (hTERT) is the key determinant of telomerase activity and plays a crucial role in cellular immortalization and oncogenesis. It will be a promising target for cancer gene therapy. We constructed a novel replicative adenovirus CNHK300 in which hTERT promoter with three extra E-boxes downstream of the promoter was introduced and used to regulate adenoviral E1a gene, and studied its properties of selective replication in cancer cells and antitumoral activity.
  
  
  METHODS
  Luciferase assay was used to detect hTERT promoter activity. The selective replication of CNHK300 in cancer cells was investigated by E1a Western blot and green fluorescent protein (GFP) reporter gene assay. The antitumoral activity of CNHK300 and its toxicity were measured on animal models.
  
  
  RESULTS
  Luciferase assay showed that introducing extra E-boxes downstream of hTERT promoter is beneficial to decreasing the promoter activity in normal cells without affecting its strong activity in cancer cells. Experiments in vitro and in vivo demonstrated that CNHK300 can selectively target to hTERT-positive cancer cells and replicate in them, resulting in oncolytic or antitumoral effect. CNHK300 is superior to ONYX-015 in terms of selective replication and oncolytic or antitumoral effect. The toxicity assay showed no signs of toxicity to liver cells even at the higher dosage of CNHK300 in vivo.
  
  
  CONCLUSIONS
  The hTERT promoter-controlled, replication-competent adenovirus CNHK300 is a promising system for targeted cancer gene therapy.
authors.affiliation: Laboratory of Viral and Gene Therapy, Eastern Hepatobiliary Surgical Hospital, The Second Military Medical University, 225 Changhai Rd, 200438 Shanghai, China.
authors.forename: C-Q
authors.initials: CQ
authors.lastname: Su
authors.forename: J
authors.initials: J
authors.lastname: Sham
authors.forename: H-B
authors.initials: HB
authors.lastname: Xue
authors.forename: X-H
authors.initials: XH
authors.lastname: Wang
authors.forename: D
authors.initials: D
authors.lastname: Chua
authors.forename: Z-F
authors.initials: ZF
authors.lastname: Cui
authors.forename: L-H
authors.initials: LH
authors.lastname: Peng
authors.forename: L-F
authors.initials: LF
authors.lastname: Li
authors.forename: L-H
authors.initials: LH
authors.lastname: Jiang
authors.forename: M-C
authors.initials: MC
authors.lastname: Wu
authors.forename: Q-J
authors.initials: QJ
authors.lastname: Qian
mesh_terms: D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D004268:DNA-Binding Proteins; D015316:Genetic Therapy / Q000379:methods; D049452:Green Fluorescent Proteins; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009369:Neoplasms / Q000201:enzymology* / Q000821:virology; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019098:Telomerase / Q000235:genetics* / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D049452:Green Fluorescent Proteins; D019098:Telomerase