Tailor-made fibroblast-specific and antibiotic-free interleukin 12 plasmid for gene electrotransfer-mediated cancer immunotherapy

摘要

Electrotransfer mediated delivery of interleukin-12 (IL-12) gene, encoded on a plasmid vector, has already been demonstrated to have a potent antitumor efficacy and great potential for clinical application. In the present study, our aim was to construct an optimized IL-12-encoding plasmid that is safe from the regulatory point of view. In light of previous studies demonstrating that IL-12 should be released in a tumor localized manner for optimal efficacy, the strong ubiquitous promoter was replaced with a weak endogenous promoter of the collagen 2 gene, which is specific for fibroblasts. Next, to comply with increasing regulatory demands for clinically used plasmids, the expression cassette was cloned in a plasmid lacking the antibiotic resistance gene. The constructed fibroblast specific and antibiotic-free IL-12 plasmid was demonstrated to support low IL-12 expression after gene electrotransfer in selected cell lines. Furthermore, the removal of antibiotic resistance did not affect the plasmid expression profile and lowered its cytotoxicity. With optimal IL-12 expression and minimal transgene non-specific effects, i.e., low cytotoxicity, the constructed plasmid could be especially valuable for different modern immunological approaches to achieve localized boosting of the host's immune system. (C) 2016 Elsevier Inc. All rights reserved.