Multifunctionalized polyethyleneimine-based nanocarriers for gene and chemotherapeutic drug combination therapy through one-step assembly strategy

Gene therapy combined with chemotherapy to achieve synergistic therapeutic effects has been a hot topic in recent years. In this project, the human tumor necrosis factor-related apoptosis-inducing ligand-encoding plasmid gene (TRAIL) and doxorubicin (Dox)-coloaded multi-functional nanocarrier was constructed based on the theory of circulation, accumulation, internalization, and release. Briefly, polyethyleneimine (PEI) was selected as skeleton material to synthesize PEI-polyethylene glycol (PEG)-TAT (PPT). Dox was conjugated to PEI using C6-succinimidyl 6-hydrazinonicotinate acetone hydrazone (C6-SANH), and a pH-sensitive Dox-PEI (DP) conjugate was obtained. Then, intracellular cationic pH-sensitive cellular assistant PPT and DP were mixed to condense TRAIL, and TRAIL-Dox coloaded PPT/DP/TRAIL (PDT) nanocarriers were obtained by one-step assembly. TRAIL was completely condensed by DP or PPT when mass ratios (DP/PPT to TRAIL) were up to 100:64, which indicated that DP and PPT could be mixed at any ratio for TRAIL condensation. The intracellular uptake rate of PDT was enhanced (P<0.05) when the contents of PPT in PPT+DP increased from 0 to 30%. Free Dox and TRAIL-loaded nanocarriers (PPT/C6-SANH-PEI/TRAIL [PCT]) were selected as controls to verify the synergistic antitumor effects of PDT. Compared with free TRAIL, TRAIL-protein expression was upregulated by PDT and PCT on Western blotting assays. The in vitro cytotoxicity of PDT was significantly enhanced compared to free Dox and PCT (P<0.01). Furthermore, murine PDT nanocarriers showed higher in vivo antitumor ability than both the Dox group (P<0.05) and the murine PCT group (P<0.05). These results indicated that the TRAIL + Dox synergistic antitumor effect could be achieved by PDT, which paves the way to gene-drug combination therapy for cancer.