Tumour cell radiosensitization using constitutive (CMV) and radiation inducible (WAF1) promoters to drive the iNOS gene: a novel suicide gene therapy.
Nitric oxide (NO(*)) has many characteristics including cytotoxicity, radiosensitization and anti-angiogenesis, which make it an attractive molecule for use in cancer therapy. We have investigated the use of iNOS gene transfer, driven by both a constitutive (CMV) and X-ray inducible (WAF1) promoter, for generating high concentrations of NO(*) within tumour cells. We have combined this treatment with radiation to exploit the radiosensitizing properties of this molecule. Transfection of murine RIF-1 tumour cells in vitro with the iNOS constructs resulted in increased iNOS protein levels. Under hypoxic conditions cells were radiosensitized by delivery of both constructs so that these treatments effectively eliminated the radioresistance observed under hypoxic conditions. In vivo transfer of the CMV/iNOS construct by direct tumour injection resulted in a delay (4.2 days) in tumour growth compared with untreated controls. This was equivalent to the effect of 20 Gy X-rays alone. Combination of CMV/iNOS gene transfer with 20 Gy X-rays resulted in a dramatic 19.8 day growth delay compared with controls. Tumours treated with the CMV/iNOS showed large areas of necrosis and abundant apoptosis. We believe that iNOS gene transfer has the potential to be a highly effective treatment in combination with radiotherapy.
Worthington
J
J
Radiation Science Research Group, School of Biomedical Sciences, University of Ulster, Newtownabbey, Co. Antrim, UK.
Robson
T
T
O'Keeffe
M
M
Hirst
D G
DG
D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D002455:Cell Division / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D003131:Combined Modality Therapy; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics / Q000528:radiation effects; D005260:Female; D005354:Fibrosarcoma / Q000473:pathology / Q000532:radiotherapy / Q000628:therapy*; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000627:therapeutic use; D051379:Mice; D008809:Mice, Inbred C3H; D019001:Nitric Oxide Synthase / Q000235:genetics* / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D011401:Promoter Regions, Genetic / Q000528:radiation effects; D011838:Radiation-Sensitizing Agents / Q000378:metabolism*; D014162:Transfection; D014407:Tumor Cells, Cultured
C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D011838:Radiation-Sensitizing Agents; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse