Spatiotemporally controllable diphtheria toxin expression using a light-switchable transgene system combining multifunctional nanoparticle delivery system for targeted melanoma therapy.

Gene therapy with external gene insertion (e. g. a suicide gene) and expression specifically in mutated tumor cells has shown to be a promising strategy in treatment of tumors. However, current tumor gene therapy often suffered from low efficiency in gene expression and off-target effects which may cause damage to normal tissues. To address these issues, in this study, a light-switchable transgene nanoparticle delivery system loaded with a diphtheria toxin A (DTA) segment encoded gene, a suicide gene for tumor cells, was developed. The nanoparticles contained vitamin E succinate-grafted polyethyleneimine core and arginylglycylaspartic acid (RGD)-modified pegylated hyaluronic acid shell for targeted delivery of the loaded gene to tumor cells via receptor-mediated (CD44 and αvβ3) endocytosis. Notably, the expression of target proteins in tumor cells could be conveniently regulated by adjusting the blue light intensity in the Light-On system. In in-vitro studies in cultured B16-F10 cells, the pG-DTA-loaded nano-micelles showed greatly improved inhibitory rate compared with the pG-DTA group. Moreover, in the tumor-bearing C57BL/6 mice model, the pG-DTA-loaded nanoparticle exhibited greatly improved efficacy and reduced systemic toxicity with significantly increased survival rate after 21 days. Significantly suppressed tumor angiogenesis was also identified in the nanoparticle-treated group likely due to the targeting ability of the RGD-modified nanoparticle. All the above results indicated that the combination of a light-switchable transgene system with a nanoparticle-based targeted delivery system have great potentials in gene therapy of malignant tumors with improved precision and efficacy.