Abstract 4504: Potential use of polyethyleneimine as a gene delivery vehicle for breast cancer.

Abstract

Abstract Breast cancer is the second leading cause of cancer death in US women, after lung cancer. A major impediment in advancing gene therapy approaches to breast cancer is the resistance of cancer cell membrane to transport DNA/RNA. Viral vectors are efficient to deliver target genes; however, they are associated with the risk of immune response, random integration into the host genome or recombination with other wild type viruses. In contrast, non-viral vectors, that include lipoplex and polyplex forming carriers, are more advantageous as they are less expensive, easier to manufacture, and can carry large molecules of DNA. Polyethyleneimine (PEI) has emerged as a very effective gene transfection agent. PEI is water soluble, positively charged, and can envelope negatively charged DNA and protect it from lysosomal degradation. However, gene transfection efficacy of PEI for breast cancer cells remains poorly understood. In addition, information on the relationship between the polymer structure and its biological function, such as DNA condensation, toxicity and transfection efficacy is still limited. In this study, we evaluated the transfection efficiency of PEIs differing in molecular weight and branching. pGL3 control plasmid (5256 bp) containing a coding for the firefly luciferase gene driven by the SV40 promoter was used for this study. pGL3 complexed with different PEIs was tested for gene transfection study in breast cancer cells, using luciferase activity measurements with a luminometer. Cytotoxicity was measured by trypan blue exclusion assay. Static and dynamic laser light scattering was used to determine the ability of PEIs to condense plasmid DNA to nanoparticles and determine the size of the nanoparticles. Our results showed maximum transfection efficiency with 22 kDa linear PEI at N/P (nitrogen/phosphorus) ratio of 4.8 to 6. Linear and branched 25 kDa PEIs were less efficient than 22 kDa PEI. Low molecular weight (0.6 and 1.2 kDa) PEIs had negligible effect in transporting plasmid DNA, whereas 10 kDa PEI showed some activity. Cytotoxic effects of the PEIs were suppressed by DNA complexation. Both branched and linear PEIs condensed plasmid DNA to nanoparticles (hydrodynamic radius: ∼155 nm). Taken together, these results demonstrate structure-function relationships of PEIs in condensing and transporting plasmid DNA. Our results might be useful in selecting and improving the properties of PEI as a gene delivery vehicle for breast cancer. Citation Format: T. J. Thomas, Sripriya Venkiteswaran, Thresia Thomas. Potential use of polyethyleneimine as a gene delivery vehicle for breast cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4504. doi:10.1158/1538-7445.AM2013-4504