Enhanced Therapeutic Efficiency of PEI/Bile Acid-Coated Adenovirus Complex Against Low Coxsackie and Adenovirus Receptor-Expressing Cancer

Abstract

Adenovirus (Ad) has been widely employed as a potential therapeutic agent for cancer gene therapy, including self-propagation, lysis of infected cancer cells, and secondary infection of adjacent cells within the tumor, but their transduction efficiency depends on the level of CAR expression in the target cell. To overcome this hurdle, a strategy of generating hybrid vector that combines viral and nonviral elements as a more intelligent gene carrier has been employed. Here, we used bile acid conjugated polyethyleneimine (DA3) for coating the surface of Ad to enhance transduction efficiency of Ad on cancer cells. We characterized the effect of polymer concentration on particle size distribution, zeta potential and structural properties. The transduction efficiency of Ad/DA3 complex was increased in a DA3 concentration-dependent manner, and the enhancement of gene transfer efficiency of Ad/DA3 over naked Ad was more evident in CAR-moderate and CAR-negative cancer cells than CAR-positive cancer cells. Competition assay using CAR-specific antibody revealed that entry/internalization of Ad/DA3 complex is not predominantly mediated by the normal CAR-mediated endocytosis pathway. Moreover, investigation into the internalization mechanism of Ad/DA3 complex showed that cellular uptake mechanism of Ad/DA3 complex is different from that of naked Ad which is clathrin-mediated endocytosis, and Ad/DA3 complex seems to enter the cells via clathrin-, caveolae–, and macropinocytosis–mediated endocytosis in part. When oncolytic Ad was complexed with DA3 (RdB-KOX/DA3 complex), cancer cell killing efficacy was significantly increased over naked Ad, and the increase of enhanced cancer cell killing effect was inversely proportional to the expression level of CAR. Moreover, tumor xenografts study demonstrated the enhanced therapeutic efficacy of RdB-KOX/DA3 complex over naked oncolytic Ad control. Taken together, these results suggest that the Ad/DA3 complex has potential to enhance the therapeutic efficacy on low CAR expressing cell.