963. Development and Testing of Anti-Cancer Sleeping Beauty Transposons for Localized Tumors and Use in Metastasis Suppression

Top of pageAbstract We have developed a series of anti-cancer Sleeping Beauty (SB) transposons designed for transfer of anti-angiogenic genes or Herpes Simplex Virus Thymidine Kinase (HSVTK) fusion genes into tumor cells, tumor-associated stroma, or organs undergoing metastatic attack. All genes were placed in SB T2 transposon vectors driven by the chicken beta-actin/CMV immediate early promoter/rabbit globin intron (CAGGS) promoter construct. Glioblastoma multiforme (GBM) and at least 6 other cancers overexpress IL-13 receptors. In order to take advantage of this, the human IL-13 ligand was fused to the N-terminus of HSVTK to make a secreted, tumor-targeted, suicide gene. Cell culture media collected from cells transfected with IL13-HSVTK is able to specifically sensitize IL-13 receptor positive GBM-derived cells to ganciclovir. Furthermore, we have delivered the IL13-HSVTK transposon intratumorally as plasmid DNA vector in polyethylenimine (PEI) to abolish glioma xenografts in immunodeficient nu/nu mice. We have also used angiostatin-endostatin fusion and dominant-negative VEGF transposons, delivered intratumorally as DNA/PEI complexes, to reduce glioma xenograft size and halt tumor growth. GBM generally causes death quickly as a primary tumor, however metastatic disease such as occurs in late-stage melanoma also remains difficult to treat. Therefore, we have investigated delivering anti-angiogenic transposons into the mouse lung as DNA/PEI complexes to prevent metastatic engraftment of syngenic B16F10 melanoma cells. Both the quantity and volume of lung metastases was reduced in a transposase-dependent fashion in mice treated 2 months prior to melanoma challenge. SB anti-cancer transposons represent a novel, non-viral vector system that could be used to augment conventional therapy for localized and metastatic cancers.