Cancer stem cells (CSCs) are responsible for cancer drug resistance with high expression of ABCG2, which pumps the internalized chemotherapeutic out to escape drug-induced cytotoxicity. Here, we established a functionalized mesoporous silica nanoparticle (MSN) system to deliver shABCG2 and doxorubicin (Dox) synergistically. With excellent cell uptake and endosomal escape capacities, the dual-delivery carriers internalized shABCG2 and Dox into CSCs efficiently. ABCG2 depletion increased intracellular and intranuclear Dox enrichment, drove vigorous Dox-induced cell death, and impaired the self-renewal of CSCs. Additionally, the nanoparticles eliminated tumors efficiently and reduced tumor initiation by CSCs in vivo, with negligible side effects. Our findings suggest that well-designed delivery systems for conventional chemotherapeutic agents are promising for CSC therapy.

Polycationic vectors are often used to deliver DNA for cancer therapies, but their inefficiency in releasing DNA from the polyplexes after endosomal escape limits DNA transcription and their efficient application in vivo. In this study, DNA/PEI polyplexes were cross-linked by a reduction-sensitive disulfide bond and then further complexed with electrostatic competitive heparin (HP) and hyaluronidase (HAase)-sensitive hyaluronate (HA) to obtain DNA/PEIS/HA–HP (DPSHA–HP). DPSHA–HP was stable in an extracellular environment (pH = 7.4) and degraded by HAase after targeted HA receptor CD44-mediated cell endocytosis, causing the outer shielding of the nanocomplex to loosen. The resulting partially exposed disulfide-linked DNA/PEI nanocomplexes efficiently ruptured the endosome, facilitating the cleavage of disulfide bonds and the release of DNA/PEI polyplexes into the cytoplasm, where DNA release from the polyplexes was remarkably enhanced due to strong electrostatic competition of HP with PEI. Consequently, DPSHA–HP exhibited excellent DNA transfection of the target cells, better than disulfide cross-linked DNA/PEI (25 kDa) and DNA/PEIS/HA. Moreover, these novel layered nanocomplexes have high efficiency in down-regulating B-cell-specific Moloney murine leukemia virus insertion site 1 (Bmi-1) and exhibit significant inhibition of tumor formation with minimal toxicity in a mouse tumor model.

In this study, we constructed a layered graphene oxide (GO) nanocomplex with pH-responsive charge-reversible chitosan-aconitic anhydride (CS-Aco), biocompatible polyethylene glycol (PEG) and low molecular weight polyethylenimine (PEI). This was employed as a novel delivery system for intracellular pH-triggered DOX and short hairpin RNA (shRNA) controlled release and synergistic therapy. The nanocomplex GO–PEI–PEG/DOX/CS-Aco/PEI/shRNA exhibited high drug and shRNA loading, and good stability at physiological pH. In an acid pH environment, the negatively charged CS-Aco layer hydrolyzed into positively charged chitosan, causing the shielding layers of the nanocomposite to loosen. The disassembled GO–PEI–PEG/DOX and chitosan efficiently ruptured the endosome, significantly facilitating the release of DOX and PEI/shRNA into the cytoplasm, and then the shRNA disassembled rapidly because of its weak electrostatic interactions with the short PEI chains. Consequently, GO–PEI–PEG/DOX/CS-Aco/PEI/shRNA exhibited excellent shABCG2 and DOX co-delivery efficiency in HepG2 cells, which was better than that of GO/DOX and the non-charge-reversible GO–PEI–PEG/DOX/CS-Car/PEI/shRNA nanocomplex. Furthermore, this novel nanocomplex had high efficiency in silencing ABCG2 expression, and exhibited a significant synergistic efficacy in chemotherapy.

Many synthetic Au-based cationic nanoparticles (AuNPs) for nonviral gene delivery show high efficiency in vitro, but their excessive charge density, harsh reducing conditions, and nontarget delivery prevent their application in vivo. Herein, we constructed a sandwich-type layered polyethylenimine (PEI)-coated gold nanocomposite outerlaid with a nucleus-targeted Dexamethasone (Dexa), namely, Au-PEI/DNA/PEI-Dexa nanocomplex, for DNA delivery system using a low molecular weight PEI as a mild reducing agent. The nucleus-targeting Au-PEI/DNA/PEI-Dexa nanocomplex with low positive charge and low cytotoxicity condensed DNA and protected from enzymatic degradation. In vitro transfection studies demonstrated that Au-PEI/DNA/PEI-Dexa nanocomplex exhibited much more efficient nucleus transfection than Au-PEI/DNA/PEI without nucleus-targeted residues and commercially available PEI 25 kDa due to the Dexa targeting of the nucleus. Furthermore, the nanocomplex markedly transfected pTRAIL (TRAIL = tumor-necrosis-factor-related apoptosis-inducing ligand) to tumors in vivo and subsequently inhibited the tumor growth with minimal side effects. These findings suggest that nucleus-targeting Au-PEI/DNA/PEI-Dexa ternary complexes have promising potential in gene delivery.Keywords: dexamethasone; gold nanoparticle; layer-by-layer; nucleus-targeted; polyethylenimine

In this study, we constructed a layered graphene oxide (GO) nanocomplex with pH-responsive charge-reversible chitosan-aconitic anhydride (CS-Aco), biocompatible polyethylene glycol (PEG) and low molecular weight polyethylenimine (PEI). This was employed as a novel delivery system for intracellular pH-triggered DOX and short hairpin RNA (shRNA) controlled release and synergistic therapy. The nanocomplex GO–PEI–PEG/DOX/CS-Aco/PEI/shRNA exhibited high drug and shRNA loading, and good stability at physiological pH. In an acid pH environment, the negatively charged CS-Aco layer hydrolyzed into positively charged chitosan, causing the shielding layers of the nanocomposite to loosen. The disassembled GO–PEI–PEG/DOX and chitosan efficiently ruptured the endosome, significantly facilitating the release of DOX and PEI/shRNA into the cytoplasm, and then the shRNA disassembled rapidly because of its weak electrostatic interactions with the short PEI chains. Consequently, GO–PEI–PEG/DOX/CS-Aco/PEI/shRNA exhibited excellent shABCG2 and DOX co-delivery efficiency in HepG2 cells, which was better than that of GO/DOX and the non-charge-reversible GO–PEI–PEG/DOX/CS-Car/PEI/shRNA nanocomplex. Furthermore, this novel nanocomplex had high efficiency in silencing ABCG2 expression, and exhibited a significant synergistic efficacy in chemotherapy.

Polycationic vectors are often used to deliver DNA for cancer therapies, but their inefficiency in releasing DNA from the polyplexes after endosomal escape limits DNA transcription and their efficient application in vivo. In this study, DNA/PEI polyplexes were cross-linked by a reduction-sensitive disulfide bond and then further complexed with electrostatic competitive heparin (HP) and hyaluronidase (HAase)-sensitive hyaluronate (HA) to obtain DNA/PEIS/HA–HP (DPSHA–HP). DPSHA–HP was stable in an extracellular environment (pH = 7.4) and degraded by HAase after targeted HA receptor CD44-mediated cell endocytosis, causing the outer shielding of the nanocomplex to loosen. The resulting partially exposed disulfide-linked DNA/PEI nanocomplexes efficiently ruptured the endosome, facilitating the cleavage of disulfide bonds and the release of DNA/PEI polyplexes into the cytoplasm, where DNA release from the polyplexes was remarkably enhanced due to strong electrostatic competition of HP with PEI. Consequently, DPSHA–HP exhibited excellent DNA transfection of the target cells, better than disulfide cross-linked DNA/PEI (25 kDa) and DNA/PEIS/HA. Moreover, these novel layered nanocomplexes have high efficiency in down-regulating B-cell-specific Moloney murine leukemia virus insertion site 1 (Bmi-1) and exhibit significant inhibition of tumor formation with minimal toxicity in a mouse tumor model.