Expression of the bacterial nitroreductase enzyme in mammalian cells renders them selectively sensitive to killing by the prodrug CB1954 (original) (raw)
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Cancer Gene Therapy, 2000
Expression of the Escherichia coli enzyme nitroreductase (NTR) in mammalian cells enables them to activate the prodrug 5-(aziridin-1-yl)-2,4-dinitrobenzamide (CB1954), leading to interstrand DNA cross-linking and apoptosis in both proliferating and quiescent cells. In the work reported here, we used human hepatocellular carcinoma and squamous carcinoma cell lines constitutively expressing NTR to demonstrate that the ntr/CB1954 system results in potent, long-lasting antitumoral effects in mice. We also demonstrate that this enzyme/prodrug combination results in antitumoral effects in vivo when only a minority of tumor cells express the enzyme, using either cells constitutively expressing NTR or ntr gene delivery in situ. Cancer Gene Therapy (2000) 7, 721-731
Human Gene Therapy, 2000
Gene transfer of the herpes simplex virus thymidine kinase (TK) gene associated with ganciclovir (GCV) treatment can lead to death of TK-expressing cells, and of neighboring TK 2 cells because of the bystander effect. Thus, a small proportion of TK 1 cells in a tumor can lead to its complete regression after GCV treatment. However, a lack of efficacy of gene transfer into tumors associated with low GCV sensitivity and poor bystander effect of human cancer cells currently limit the clinical use of this suicide gene therapy approach. To increase the potency of suicide gene therapy, we have tested the GCV sensitivity and the bystander effect of TK mutants that have been previously described. After retroviral transduction of the TK mutants into human tumor cells of various origins, we have found a strong killing effect of GCV with cells expressing the mutants TK30 or TKF161C. The GCV sensitivity of several human tumor cell types expressing TK30 was 9-to 500-fold higher than cells containing wild-type TK. Furthermore, TK30-expressing cells were able to kill bystander cells much more efficiently than TK-expressing cells. Thus, TK30 mutant is a promising candidate for suicide gene therapy clinical trials.
A mammalianized synthetic nitroreductase gene for high-level expression
BMC Cancer, 2009
The nitroreductase/5-(azaridin-1-yl)-2,4-dinitrobenzamide (NTR/CB1954) enzyme/ prodrug system is considered as a promising candidate for anti-cancer strategies by gene-directed enzyme prodrug therapy (GDEPT) and has recently entered clinical trials. It requires the genetic modification of tumor cells to express the E. coli enzyme nitroreductase that bioactivates the prodrug CB1954 to a powerful cytotoxin. This metabolite causes apoptotic cell death by DNA interstrand crosslinking. Enhancing the enzymatic NTR activity for CB1954 should improve the therapeutical potential of this enzyme-prodrug combination in cancer gene therapy.
Cancer research, 1998
Past studies have documented the promise of herpes simplex virus type 1 (HSV-1) thymidine kinase (TK) suicide gene therapy as a potential antitumor treatment. HSV-TK converts the pro-drug ganciclovir (GCV) into a toxic nucleotide analogue, the incorporation of which into cellular DNA blocks cell proliferation. In this report, we have examined the hypothesis that the effectiveness of HSV-TK suicide gene therapy can be enhanced by coexpression of the antitumor cytokine human tumor necrosis factor-alpha (TNF-alpha) from the same replication-defective HSV-1 vector. In vitro testing demonstrated that TNF-alpha expression from this vector potentiated the killing of both TNF-alpha-sensitive L929 tumor cells and TNF-alpha-resistant U-87 MG cells in the presence of GCV. Furthermore, treatment of established intradermal L929 tumors in vivo with the TNF-alpha/TK vector and GCV resulted in prolonged animal survival compared with treatment with parental HSV-TK vector in the presence or absence o...
Cancer Gene Therapy, 2003
The Herpes simplex virus 1 (HSV) thymidine kinase (tk) suicide gene together with ganciclovir (GCV) have been successfully used for the in vivo treatment of various solid tumors and for the ablation of unwanted transfused stem cells in recent clinical trials. With the aim of improving this therapeutic system, we compared the potential efficacy of adenoviral (Ad) vectors expressing enhanced tk mutants in vitro and in vivo. The previously created HSV-tk mutants dm30 and sr39, created by random sequence mutagenesis, were inserted into a standard Ad.RSV E1 À E3 À backbone using homologous recombination. GCV killing of Ad.HSV-tk, Ad.dm30-tk and Ad.sr39-tk was assessed in various tumor cell lines with a cell proliferation assay. Cells expressing the two TK mutants were two-to-five-fold more sensitive to GCV when compared with Ad.HSV-tk transduced cells in all cell lines tested (five human mesotheliomas, one human lung cancer, a human cervical carcinoma, a mouse fibrosarcoma, and a rat glioma line) at equal TK expression levels. Flank tumor models, including cell-mixing studies, assessed the in vivo efficacy of the engineered viruses in BALB/C and SCID mice. In all animal studies, Ad.dm30-tk and Ad.sr39-tk showed more tumor growth inhibition than Ad.HSV-tk when GCV was administered. The use of adenovirus-mediated gene transfer of both tk mutants dm30-tk and sr39-tk for cancer suicide gene therapy should provide a more effective and safer alternative to wild-type HSV-tk.