Hypoxia response element-driven cytosine deaminase/5-fluorocytosine gene therapy system: a highly effective approach to overcome the dynamics of tumour hypoxia and enhance the radiosensitivity of prostate cancer cells in vitro

Laure Marignol, Ruth Foley, Thomas D Southgate, Mary Coffey, Donal Hollywood, Mark Lawler, Mark Lawler

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

BACKGROUND: We proposed to exploit hypoxia-inducible factor (HIF)-1alpha overexpression in prostate tumours and use this transcriptional machinery to control the expression of the suicide gene cytosine deaminase (CD) through binding of HIF-1alpha to arrangements of hypoxia response elements. CD is a prodrug activation enzyme, which converts inactive 5-fluorocytosine to active 5-fluorouracil (5-FU), allowing selective killing of vector containing cells.

METHODS: We developed a pair of vectors, containing either five or eight copies of the hypoxia response element (HRE) isolated from the vascular endothelial growth factor (pH5VCD) or glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (pH8GCD) gene, respectively. The kinetics of the hypoxic induction of the vectors and sensitization effects were evaluated in 22Rv1 and DU145 cells in vitro.

RESULTS: The CD protein as selectively detected in lysates of transiently transfected 22Rv1 and DU145 cells following hypoxic exposure. This is the first evidence of GAPDH HREs being used to control a suicide gene therapy strategy. Detectable CD levels were sustained upon reoxygenation and prolonged hypoxic exposures. Hypoxia-induced chemoresistance to 5-FU was overcome in both cell lines treated with this suicide gene therapy approach. Hypoxic transfectants were sensitized to prodrug concentrations that were ten-fold lower than those that are clinically relevant. Moreover, the surviving fraction of reoxygenated transfectants could be further reduced with the concomitant delivery of clinically relevant single radiation doses.

CONCLUSIONS: This strategy thus has the potential to sensitize the hypoxic compartment of prostate tumours and improve the outcome of current therapies.

Original languageEnglish
Pages (from-to)169-79
Number of pages11
JournalThe Journal of Gene Medicine
Volume11
Issue number2
DOIs
Publication statusPublished - Feb 2009

Bibliographical note

Copyright (c) 2008 John Wiley & Sons, Ltd.

Keywords

  • Cell Hypoxia
  • Cell Line, Tumor
  • Cell Survival
  • Cytosine Deaminase
  • Flucytosine
  • Genetic Therapy
  • Genetic Vectors
  • Humans
  • Male
  • Prostatic Neoplasms
  • Radiation Tolerance
  • Response Elements
  • Transfection

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