Background Inducible nitric oxide synthase (iNOS) gene therapy has been identified as a potential anti-tumour strategy. A major problem common to most gene therapy strategies is targeting of treatment to the turnout volume. in this study we report on the use of the X-ray-inducible WAF1 promoter to achieve targeting of iNOS expression to the turnout volume. Methods A WAF1/iNOS/liposome complex was injected directly into RIF-1 and HT29 tumours in mice. A 4 Gy dose of X-rays was applied to induce the WAF1 promoter followed, 8 h later, by treatment doses of 10 or 20 Gy. Tumour volume was measured, and growth curves plotted. Results Intra-tumoural injection of WAF1/iNOS combined with a priming dose of X-rays to induce the WAF1 promoter, followed by a treatment dose, resulted in sensitiser enhancement ratios of 2.0 and 1.3 in RIF-1 and HT29 tumours, respectively, compared with radiation treatment alone. PCR analysis of organ tissue after intra-tumoural injection of WAF1/iNOS showed that vector sequences were detected in all tissue tested; however, Western blot analysis revealed that iNOS protein levels were significantly increased only in tumour and the surrounding dermal tissue that had been exposed to the 4 Gy inducing dose. Conclusions iNOS gene therapy in combination with an inducible promoter results in significant tumour cell radiosensitisation. The WAF1 promoter may be a good candidate for a gene therapy as it is silent in normal tissue yet can be induced by the tumour environment. Copyright (C) 2004 John Wiley Sons, Ltd.
Worthington, J., McCarthy, HO., Barrett, E., Adams, C., Robson, T., & Hirst, DG. (2004). Use of the radiation-inducible WAF1 promoter to drive iNOS gene therapy as a novel anti-cancer treatment. Journal of Gene Medicine, 6(6), 673-680. https://doi.org/10.1002/jgm.567