Enriching suicide gene bearing tumor cells in vivo for an increased bystander effect: a novel strategy for cancer gene therapy
Unger, Marcus Michael
LicenseStandard (Fassung vom 03.05.2003)
The low efficacy of gene transfer severely limits the clinical implementation of cancer gene therapies requiring in vivo transfer. We now show that in vivo enrichment of tumor cells post suicide gene transfer is an effective alternative to increasing gene transfer for enhancing tumor control. Enrichment allows for a very strong bystander effect after administration of the prodrug, leading to eradication of most tumor cells. For this enrichment-eradication strategy we used a suicide fusion gene comprised of cytosine deaminase from yeast and uracil phosphoribosyl-transferase (FCU1). This suicide gene is bifunctional since it allows for both positive and negative selection. Positive selection (enrichment) is achieved by concurrently giving N-(phosphonacetyl)-L-aspartate (PALA), which leads to pyrimidine depletion-mediated death of non-transduced cells and cytosine, which rescues FCU1 containing cells via the pyrimidine salvage pathway. Negative selection (eradication) is induced once the prodrug 5-fluorocytosine is given. Murine NXS2 neuroblastoma cells transduced with FCU1 were effectively enriched in vitro, leading to a near-complete bystander effect. In vivo, enrichment-eradication led to decreased tumor growth and prolonged survival of mice bearing subcutaneous NXS2 tumors. In conclusion, the enrichment-eradication approach can complement efforts to increase gene transfer efficacy, one major hurdle of cancer gene therapy.
Subject HeadingsGentherapie [GND]
Gene therapy [MeSH]