title: Oxygen tension and a pharmacological switch in the regulation of transgene expression for gene therapy.
abstract: BACKGROUND
  The combination of physiologically and pharmacologically controlled elements may provide a means to ensure both the regulation and the safety of transgene expression--two major goals in gene therapy.
  
  
  METHODS
  A two-gene modulation system was developed that uses the following three levels of control: (i) the hypoxia-responsive element directing the transcription of the tetracycline-controlled transactivator (tTA); (ii) part of the oxygen-degradation domain limiting the production of tTA in normoxia; and (iii) the tetracycline switch of the transactivator activity (the tet-off system).
  
  
  RESULTS
  This triple-control system allowed high expression of the gene of interest (luciferase or erythropoietin) by transfected cells upon hypoxia and low expression under normoxia or in the presence of tetracycline. This control of transgene expression was also obtained in mouse tumors.
  
  
  CONCLUSIONS
  This multiple-control system is of interest for spatially restricting transgene expression into hypoxic tumors, and for finely adjusting the expression level of a therapeutic protein to the oxygen supply in medical applications such as neoangiogenesis or the erythropoietin-mediated treatment of anemia.
authors.affiliation: Laboratoire de Thérapie Génique Hématopoïétique, Institut Universitaire d'Hématologie, Hĵpital Saint-Loius, Paris, France. letg@chu-stlouis.fr
authors.forename: E
authors.initials: E
authors.lastname: Payen
authors.forename: M
authors.initials: M
authors.lastname: Bettan
authors.forename: A
authors.initials: A
authors.lastname: Henri
authors.forename: E
authors.initials: E
authors.lastname: Tomkiewitcz
authors.forename: A
authors.initials: A
authors.lastname: Houque
authors.forename: I
authors.initials: I
authors.lastname: Kuzniak
authors.forename: J
authors.initials: J
authors.lastname: Zuber
authors.forename: D
authors.initials: D
authors.lastname: Scherman
authors.forename: Y
authors.initials: Y
authors.lastname: Beuzard
mesh_terms: D000256:Adenoviridae / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D000818:Animals; D018827:Carcinoma, Lewis Lung / Q000378:metabolism; D017931:DNA Primers / Q000737:chemistry; D004921:Erythropoietin / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects*; D015316:Genetic Therapy; D005822:Genetic Vectors; D006801:Humans; D000860:Hypoxia / Q000235:genetics; D008156:Luciferases / Q000235:genetics; D008175:Lung Neoplasms / Q000378:metabolism; D051379:Mice; D010100:Oxygen / Q000378:metabolism*; D013752:Tetracycline / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D019076:Transgenes / Q000235:genetics*
chemical_list: D017931:DNA Primers; D004921:Erythropoietin; D008156:Luciferases; D013752:Tetracycline; D010100:Oxygen