title: Heat-inducible transgene expression with transcriptional amplification mediated by a transactivator.
abstract: OBJECTIVE
  Control of therapeutic gene expression in tumours is a major goal of gene therapy research, as it can restrict cytotoxic gene expression in cancer cells. In addition, the combination of hyperthermia with gene therapy through the application of heat-inducible vectors can result in considerable improvements in therapeutic efficiency. In this study, to combine heat-inducibility with high-level transgene expression, we developed a heat-inducible transgene expression system with transcriptional amplification mediated by a tetracycline-responsive transactivator.
  
  
  METHODS
  A hybrid promoter was generated by placing the heat shock protein (HSP) 70B' promoter under the tetracycline-repressor responsive element sequence, and a reporter/therapeutic gene expression plasmid was constructed by placing a reporter/therapeutic gene under the control of this hybrid promoter.
  
  
  RESULTS
  When the transactivator expression plasmid harbouring an expression cassette of the tetracycline-responsive transactivator gene was co-transfected with a reporter gene expression plasmid, the reporter gene expression was controlled by heat treatment. With this system, high levels of heat-induced transgene expression were observed compared to that from the HSP promoter alone without the transactivator. Evaluation of in vitro therapeutic effects using cancer cell lines revealed that therapeutic gene expression effectively caused cell death in a greater percentage of the cells.
  
  
  CONCLUSIONS
  These findings indicate that this strategy improves the efficacy of cancer gene therapy.
authors.affiliation: Faculty of Engineering, Department of Chemical Engineering, Kyushu University, Fukuoka, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Ito
authors.forename: Noriaki
authors.initials: N
authors.lastname: Okamoto
authors.forename: Masaki
authors.initials: M
authors.lastname: Yamaguchi
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Kawabe
authors.forename: Masamichi
authors.initials: M
authors.lastname: Kamihira
mesh_terms: D045744:Cell Line, Tumor; D015870:Gene Expression; D015316:Genetic Therapy / Q000379:methods; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D006358:Hot Temperature; D006801:Humans; D009369:Neoplasms / Q000628:therapy; D011401:Promoter Regions, Genetic; D013752:Tetracycline; D015534:Trans-Activators / Q000235:genetics*; D019076:Transgenes / Q000235:genetics*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
chemical_list: D018840:HSP70 Heat-Shock Proteins; C491129:HSPA7 protein, human; D015534:Trans-Activators; D014409:Tumor Necrosis Factor-alpha; D013752:Tetracycline