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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
Author(s) -
Marignol Laure,
Foley Ruth,
Southgate Thomas D.,
Coffey Mary,
Hollywood Donal,
Lawler Mark
Publication year - 2009
Publication title -
the journal of gene medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.689
H-Index - 91
eISSN - 1521-2254
pISSN - 1099-498X
DOI - 10.1002/jgm.1281
Subject(s) - du145 , cytosine deaminase , hypoxia (environmental) , cancer research , transfection , suicide gene , prostate cancer , genetic enhancement , prodrug , biology , chemistry , microbiology and biotechnology , lncap , gene , pharmacology , cancer , biochemistry , genetics , organic chemistry , oxygen
Background We proposed to exploit hypoxia‐inducible factor (HIF)‐1α overexpression in prostate tumours and use this transcriptional machinery to control the expression of the suicide gene cytosine deaminase (CD) through binding of HIF‐1α 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. Copyright © 2008 John Wiley & Sons, Ltd.