Original Article

Cancer Gene Therapy (2006) 13, 993–1001. doi:10.1038/sj.cgt.7700970; published online 9 June 2006

Hydrodynamics-based gene delivery of naked DNA encoding fetal liver kinase-1 gene effectively suppresses the growth of pre-existing tumors

H Yazawa1, T Murakami2,6, H-M Li3, T Back4, K Kurosaka2, Y Suzuki1, L Shorts1, Y Akiyama5, K Maruyama5, E Parsoneault3, R H Wiltrout1 and M Watanabe1

  1. 1Laboratory of Experimental Immunology, NCI Center for Cancer Research, Frederick, MD, USA
  2. 2Laboratory of Molecular Immunoregulation, NCI Center for Cancer Research, Frederick, MD, USA
  3. 3Cell and Cancer Biology Branch, NCI Center for Cancer Research, Frederick, MD, USA
  4. 4Basic Research Program, SAIC-Frederick Inc., NCI-Frederick, Frederick, MD, USA
  5. 5Immunotherapy Division, Shizuoka Cancer Center Research Institute, Shizuoka, Japan

Correspondence: Dr M Watanabe, Laboratory of Experimental Immunology, NCI Center for Cancer Research, Bldg 560, Rm 31-16A, Frederick, MD 21702, USA. E-mail: watanabm@mail.nih.gov

6Current address: RCAI, RIKEN Yokohama Institute, 1-7-22 Suehiro-cho, Tsurumi-Ku, Yokohama City, Kanagawa, 230-0045, Japan.

Received 21 July 2005; Revised 25 February 2006; Accepted 22 April 2006; Published online 9 June 2006.

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Abstract

Antiangiogenic gene therapy is a promising strategy for cancer treatment, which generally requires highly efficient delivery systems. To date, success of this strategy has depended almost exclusively on the delivery of high titers of viral vectors, which can result in effective transgene expression. However, their cytotoxicity and immunogenicity are a major concern for clinical applications. Recent advances in delivery efficiency of naked DNA could potentially meet the requirement for both high transgene expression and minimal side effects. To investigate whether naked DNA can be used for antiangiogenic cancer therapy, an expression plasmid was generated that encodes a soluble form of fetal liver kinase-1 (Flk-1) gene, a receptor for vascular endothelial growth factor (VEGF). Hydrodynamic injection of this plasmid resulted in close to 0.1 mg/ml of soluble Flk-1 protein in mouse serum and blocked VEGF-driven angiogenesis in matrigel in vivo. The same delivery significantly suppressed the growth of two different pre-existing subcutaneous tumors, Renca renal cell carcinoma and 3LL lung carcinoma. CD31 immunohistochemistry revealed that the tumor-associated angiogenesis was also highly attenuated in soluble Flk-1-treated mice. Thus, expression of genes by hydrodynamics-based gene delivery of naked DNA appears to be a promising approach for antiangiogenic cancer gene therapy.

Keywords:

hydrodynamics-based gene delivery, VEGF, Flk-1, angiogenesis, renal cell carcinoma, lung carcinoma