Optimization and Internalization Mechanisms of PEGylated Adenovirus Vector with Targeting Peptide for Cancer Gene Therapy

Abstract

We have previously developed a novel adenovirus vector (Adv) that targeted tumor tissues/vasculatures after systemic administration. The surface of this Adv is conjugated with CGKRK tumor homing peptide by the cross-linking reaction of polyethyleneglycol (PEG). In this study, we showed that the condition of PEG modification was important to minimize the gene expression in normal tissues after systemic treatment. When Adv was modified only with PEG-linked CGKRK, its luciferase expression was enhanced even in the liver tissue, as well as the tumor tissue. However, in the reaction with the mixture of non-cross-linking PEG and PEG-linked CGKRK, we found out that the best modification could suppress its gene expression in the liver, without losing that in the tumor. We also studied the internalization mechanisms of CGKRK-conjugated Adv. Results suggested that there is a specific interaction of the CGKRK peptide with a receptor at the cell surface enabling efficient internalization of CGKRK-conjugated Adv. The presence of cell-surface heparan sulfate is important receptor for the cellular binding and uptake of CGKRK-conjugated Adv. Moreover, macropinocytosis-mediated endocytosis is also important in endocytosis of CGKRK-conjugated Adv, aside from clathrin-mediated and caveolae-mediated endocytosis. These results could help evaluate the potentiality of CGKRK-conjugated Adv as a prototype vector with suitable efficacy and safety for systemic cancer gene therapy.

Progress and problems with the use of suicide genes for targeted cancer therapy

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Dual tumor targeting with pH-sensitive and bioreducible polymer-complexed oncolytic adenovirus

“…Numerous vector modifications have been developed to maximize the vector's tumor targeting while decreasing immunogenic side effects. Recent approaches include non-specific Ad surface masking polymers such as poly(-ethylenimine) (PEI) [21], PEG [22,38], N-(2-hydroxypropyl) methacrylamide (HPMA) [39,40], arginine-grafted bioreducible polymer [18,30,41] and chitosan [42], alteration of endogenous Ad tropism by ablation of CAR or integrin a v b 5 and a v b 5 binding properties [43], and by attaching targeting moieties (e.g. complexes, however, most combinations fail to take full advantage of their potential benefits.…”

Evolving Lessons on Nanomaterial-Coated Viral Vectors for Local and Systemic Gene Therapy

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