Effective transfer of interleukin-12 gene to solid tumors using a novel gene delivery system, poly [D,L-2,4-diaminobutyric acid]

Abstract

Delivery of the interleukin-12 (IL-12) gene to solid tumors is a promising anticancer therapy. Vectors are currently being developed to achieve safe and effective intratumoral delivery of the IL-12 gene. Poly [D,L-2,4-diaminobutyric acid] (PDBA) is a novel gene carrier that was recently described. The goal of this study was to use this gene delivery system for treatment of solid tumors. To determine the optimal conditions for transfection, established B16F10-melanomas in C57BL/6 mice were treated with intratumoral injection of the PDBA/plasmid luciferase (pLuc) complex. We determined that the optimal complex composition was 50 mg/ml pLuc and 150 mg/ml PDBA. High levels of IL-12 protein were expressed in tumors after a single injection of PDBA/murine IL-12 (pmIL-12) complex, whereas serum levels of IL-12 in treated mice were below the limits of detection. IL-12 gene therapy with the PDBA system significantly inhibited tumor growth in comparison with the controls (Po.001). Moreover, both natural killer and cytotoxic T lymphocyte activities from draining lymph nodes of PDBA/pmIL-12-treated mice were increased substantially in comparison with those of controls (Po.05). These results suggest that PDBA-mediated IL-12 gene therapy is a potential strategy for treatment of patients with solid tumors.

Antitumor effects of the MIG and IP-10 genes transferred with poly [D,L-2,4-diaminobutyric acid] on murine neuroblastoma

“…Therefore, PDBA-mediated gene transfer appears to be a safe and effective method. The efficiencies of PDBA-mediated gene transfer to other tumor cell lines, such as melanoma 15 and colon (18.6%), and pancreatic (20.3%) cancers (unpublished data) were relatively high. PDBA-mediated gene transfer may be one of the most useful options for treatment of cancer.…”

“…Tumor samples were handled as described previously. 15 In brief, mice were killed on the first or third day after gene transfection and tumors were removed. Tumors were washed in PBS and placed in 400 ml T-PER Tissue Protein Extraction Reagent (Pierce Biotechnology, Rockford, IL) until they dissolved.…”

“…PDBA/pDNA complexes were prepared as described previously. 15 In brief, the concentration of pDNA was measured by UV absorption at 260 nm. PDBA was diluted in phosphatebuffered saline (PBS) to 50 mg/ml and pDNAs were diluted in PBS to 150 mg/ml.…”

“…We recently developed a novel non-viral cytokine gene delivery system based on poly [D,L-2,4-diaminobutyric acid] (PDBA). 15 PDBA differs from poly-lysine in the length of the side chain, resulting in high transfection efficiency. IL-12 gene transfer into tumor cells with the PDBA system induced high levels of production of IL-12 protein, resulting in inhibition of tumor growth.…”

“…IL-12 gene transfer into tumor cells with the PDBA system induced high levels of production of IL-12 protein, resulting in inhibition of tumor growth. 15 Lymphocytes are often a major component of the mononuclear cells that infiltrate solid tumors. The tumorhost interaction plays an important role in human neoplasm, [16][17][18][19][20][21][22][23] and it has been suggested that cancer patients with tumors containing large numbers of tumorinfiltrating lymphocytes (TILs) tend to have better prognose than do patients with few TILs.…”