Hypoxia- and radiation-activated Cre/loxP 'molecular switch' vectors for gene therapy of cancer.

Greco, O. and Joiner, M.C. and Doleh, A. and Powell, A.D. and Hillman, G.G. and Scott, S.D. (2006) Hypoxia- and radiation-activated Cre/loxP 'molecular switch' vectors for gene therapy of cancer. Gene Therapy, 13 (3). pp. 206-215. ISSN 0969-7128.

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Official URL http://dx.doi.org/10.1038/sj.gt.3302640

Abstract

Although a significant negative prognostic factor, tumor hypoxia can be exploited for gene therapy. To maximize targeting within the tumor mass, we have developed synthetic gene promoters containing hypoxia-responsive elements (HREs) from the erythropoietin (Epo) gene as well as radiation-responsive CArG elements from the early growth response (Egr) 1 gene. Furthermore, to achieve high and sustained expression of the suicide gene herpes simplex virus thymidine kinase (HSVtk), our gene therapy vectors contain an expression amplification system, or 'molecular switch', based on Cre/loxP recombination. In human glioma and breast adenocarcinoma cells exposed to hypoxia and/or radiation, the HRE/CArG promoter rapidly activated Cre recombinase expression leading to selective and sustained HSVtk synthesis. Killing of transfected tumor cells was measured after incubation with the prodrug ganciclovir (GCV; converted by HSVtk into a cytotoxin). In vitro, higher and more selective GCV-mediated toxicity was achieved with the switch vectors, when compared with the same inducible promoters driving HSVtk expression directly. In tumor xenografts implanted in nude mice, the HRE/CArG-switch induced significant growth delay and tumor eradication. In conclusion, hypoxia- and radiation-activated 'molecular switch' vectors represent a promising strategy for both targeted and effective gene therapy of solid tumors.

Item Type:	Article
Subjects:	Q Science
Divisions:	Faculties > Science Technology and Medical Studies > School of Biosciences > Biomedical Research Group
Depositing User:	Sue Davies
Date Deposited:	19 Dec 2007 17:55
Last Modified:	25 Jun 2012 10:28
Resource URI:	http://kar.kent.ac.uk/id/eprint/82 (The current URI for this page, for reference purposes)

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