60. Radiation Improves Local Delivery of a Virus-Mimicking Nanostructure Complex in Tumors
Authors: Rebecca A. Abela, Liang Xu, Theodore S. Lawrence, Ming Zhang
Journal: Molecular Therapy (2006)

Efficiency and specificity of gene delivery to tumors are major concerns in cancer gene therapy. We have previously used regional ionizing radiation to improve adenovirus uptake and to enhance gene expression in intrahepatic tumors (Zhang, M, et al. Mol Ther. 2003, 8:21-28; Qian, J, et al. Cancer Res. 2005, 65:5493-5497). However, non-specific gene expression and cytotoxicity in normal liver is still inevitable. Here, we explore the potentials of radiation in improving gene delivery by a virus-mimicking nanostructure complex, transferrin (Tf)-cationic liposome-DNA complex (Tf- lipoplex) (Liang, Xu, et al. Human Gene Ther. 2002, 13:469-481). Tf-lipoplex cocondensated with plasmid encoding CMV-GFP (Tf- lipoplex-GFP) was highly efficient in transducing various cancer cell lines of lung (LLC1, H1299), colon (CT26, LoVo), prostate (PC3), liver (HepG2) as well as normal hepatocyte (WB) and macrophage (MH-S). Pre-treatment of cells with radiation significantly increased GFP expression (folds) in WB (4.09), LLC1 (3.46), H1299 (2.19), HepG2 (2.15), and CT26 (2.10) in a radiation dose-dependent manner. These inductions were most effective when Tf-lipoplex-GFP was applied immediately after radiation and were diminished mostly by a 24-h delayed transfection. In contrast, radiation failed to induce GFP expression in all cells transduced by a Tf-deficient complex (Liposome-GFP) regardless of radiation doses and time, suggesting that Tf receptor-mediated internalization of the complex may be activated during radiation. Radiation on cells pre-incubated with Tf-lipoplex-GFP had no induction on gene expression. Cellular binding and uptake of the complex in WB and LLC1 cells were significantly increased by 2 Gy of radiation ( 4- fold) for 15'. Radiation-induced transgene expression in tumor was further investigated in mice bearing subcutaneous LLC1 tumors by using complex containing plasmid encoding CMV-LacZ gene (Tf- lipoplex-LacZ). Regional radiation followed by intravenous injection of complex markedly induced LacZ expression in tumor xenografts in a radiation dose-dependent fashion while no or minimal LacZ expression was observed in normal liver, or lung and spleen. Moreover, LacZ-containing DNA contents in irradiated tumors were increased in correlation with increased LacZ expression, suggesting that radiation may induce complex uptake in tumors. We conclude that radiation improves Tf-lipoplex gene delivery in tumors both in vitro and in vivo. These findings should provide us insight in developing ligand-specific liposome complex for targeted gene delivery for human cancer gene therapy. Efficiency and specificity of gene delivery to tumors are major concerns in cancer gene therapy. We have previously used regional ionizing radiation to improve adenovirus uptake and to enhance gene expression in intrahepatic tumors (Zhang, M, et al. Mol Ther. 2003, 8:21-28; Qian, J, et al. Cancer Res. 2005, 65:5493-5497). However, non-specific gene expression and cytotoxicity in normal liver is still inevitable. Here, we explore the potentials of radiation in improving gene delivery by a virus-mimicking nanostructure complex, transferrin (Tf)-cationic liposome-DNA complex (Tf- lipoplex) (Liang, Xu, et al. Human Gene Ther. 2002, 13:469-481). Tf-lipoplex cocondensated with plasmid encoding CMV-GFP (Tf- lipoplex-GFP) was highly efficient in transducing various cancer cell lines of lung (LLC1, H1299), colon (CT26, LoVo), prostate (PC3), liver (HepG2) as well as normal hepatocyte (WB) and macrophage (MH-S). Pre-treatment of cells with radiation significantly increased GFP expression (folds) in WB (4.09), LLC1 (3.46), H1299 (2.19), HepG2 (2.15), and CT26 (2.10) in a radiation dose-dependent manner. These inductions were most effective when Tf-lipoplex-GFP was applied immediately after radiation and were diminished mostly by a 24-h delayed transfection. In contrast, radiation failed to induce GFP expression in all cells transduced by a Tf-deficient complex (Liposome-GFP) regardless of radiation doses and time, suggesting that Tf receptor-mediated internalization of the complex may be activated during radiation. Radiation on cells pre-incubated with Tf-lipoplex-GFP had no induction on gene expression. Cellular binding and uptake of the complex in WB and LLC1 cells were significantly increased by 2 Gy of radiation ( 4- fold) for 15'. Radiation-induced transgene expression in tumor was further investigated in mice bearing subcutaneous LLC1 tumors by using complex containing plasmid encoding CMV-LacZ gene (Tf- lipoplex-LacZ). Regional radiation followed by intravenous injection of complex markedly induced LacZ expression in tumor xenografts in a radiation dose-dependent fashion while no or minimal LacZ expression was observed in normal liver, or lung and spleen. Moreover, LacZ-containing DNA contents in irradiated tumors were increased in correlation with increased LacZ expression, suggesting that radiation may induce complex uptake in tumors. We conclude that radiation improves Tf-lipoplex gene delivery in tumors both in vitro and in vivo. These findings should provide us insight in developing ligand-specific liposome complex for targeted gene delivery for human cancer gene therapy.