Due to low charge density and stiff backbone structure, small interfering RNA (siRNA) has inherently poor binding ability to cationic polymers and lipid carriers, which results in low siRNA loading efficiency and limits siRNA success in clinical application. Here, siRNA-phospholipids conjugates are developed, which integrate the characteristics of the two phospholipids to self-assemble via hydrophilic siRNA and hydrophobic phospholipid tails to overcome the siRNA's stiff backbone structures and enhance the siRNA loading efficiency. In this study, the thiol-modified sense and antisense siRNA are chemically conjugated with phospholipids to form sense and antisense siRNA-phospholipid, and then these sense or antisense siRNA-phospholipids with equal amounts are annealed to generate siRNA-phospholipids. The siRNA-phospholipids can serve dual functions as agents that can silence gene expression and as a component of nanoparticles to embed hydrophobic anticancer drugs to cure tumor. siRNA-phospholipids together with cationic lipids and DSPE-PEG2000 fuse around PLGA to form siRNA-phospholipids enveloped nanoparticles (siRNA-PCNPs), which can deliver siRNAs and hydrophobic anticancer drugs into tumor. In animal models, intravenously injected siRNA-PCNPs embedded DOX (siPlk1-PCNPs/DOX) is highly effective in inhibiting tumor growth. The results indicate that the siRNA-PCNPs can be potentially applied as a safe and efficient gene and anticancer drug delivery carrier.
Autophagy is an evolutionarily conserved lysosome-based degradation process. Atg5 plays a very important role in autophagosome formation. Here we show that Atg5 is required for biogenesis of late endosomes and lysosomes in an autophagy-independent manner. In Atg5 (-/-) cells, but not in other essential autophagy genes defecting cells, recycling and retrieval of late endosomal components from hybrid organelles are impaired, causing persistent hybrid organelles and defective formation of late endosomes and lysosomes. Defective retrieval of late endosomal components from hybrid organelles resulting from impaired recruitment of a component of V1-ATPase to acidic organelles blocks the pH-dependent retrieval of late endosomal components from hybrid organelles. Lowering the intracellular pH restores late endosome/lysosome biogenesis in Atg5 (-/-) cells. Our data demonstrate an unexpected role of Atg5 and shed new light on late endosome and lysosome biogenesis.
Malignant tumor disease is one of the leading causes of human death in many countries. Currently, chemotherapy is considered highly efficient for cancer treatment. However, the clinical application of conventional chemotherapeutic agents is limited because of their high toxicity. With the development of nanotechnology, engineered nanomaterials have been widely and increasingly used in biomedical fields such as biomedicine. Thus, the use of engineered nanomaterials has become a promising approach to cancer treatment. Many newly fabricated nanomaterials with unique characteristics exhibit favorable therapeutic and diagnostic properties, implying their enormous potential as biomedical candidates. [Gd@C(82)(OH)(22)](n) is a new type of metallofullerenol nanoparticle with high anti-tumor activity but low toxicity. In this article, the properties and biological effects of [Gd@C(82)(OH)(22)](n) are summarized, and their possible mechanisms are analyzed.
Cationic liposome based siRNA delivery system has improved the efficiencies of siRNA. However, cationic liposomes are prone to be rapidly cleared by the reticuloendothelial system (RES). Although modification of cationic liposomes with polyethylene glycol (PEG) could prolong circulation lifetime, PEG significantly inhibits siRNA entrapment efficiency, cellular uptake and endosomal/lysosomal escape process, resulting in low gene silencing efficiency of siRNA. In this study, we report the synthesis of zwitterionic polycarboxybetaine (PCB) based distearoyl phosphoethanolamine-polycarboxybetaine (DSPE-PCB) lipid for cationic liposome modification. The DSPE-PCB20 cationic liposome/siRNA complexes (lipoplexes) show an excellent stability in serum medium. The siRNA encapsulation efficiency of DSPE-PCB20 lipoplexes could reach 92% at N/P ratio of 20/1, but only 73% for DSPE-PEG lipoplexes. The zeta potential of DSPE-PCB20 lipoplexes is 8.19±0.53mV at the pH of 7.4, and increases to 24.6±0.87mV when the pH value is decreased to be 4.5, which promotes the endosomal/lysosomal escape of siRNA. The DSPE-PCB20 modification could enhance the silencing efficiency of siRNA by approximately 20% over the DSPE-PEG 2000 lipoplexes at the same N/P ratio in vitro. Furthermore, DSPE-PCB20 lipoplexes could efficiently mediate the down-regulation of Apolipoprotein B (ApoB) mRNA in the liver and consequently decrease the total cholesterol in serum in vivo, suggesting therapeutic potentials for siRNA delivery in hypercholesterolemia-related diseases.
Multi-hydroxylated endohedral metallofullerenol [Gd@C(82)(OH)(22)](n) nanoparticles possess the general physico-chemical characteristics of most nanoparticles. They also exhibit uniquely low toxicity and antineoplastic efficacy. In the current study, the molecular mechanisms and epigenetic characteristics of the antineoplastic action of these nanoparticles are explored. Human breast cancer MCF-7 and human umbilical vein endothelial ECV304 cell lines were used. Cell viability assay, cell hierarchical cluster analysis by cDNA microarray, semi-quantitative reverse transcription-polymerase chain reaction and Western blot analysis were conducted to investigate the changes in molecular and cellular signaling pathways caused by [Gd@C(82)(OH)(22)](n). The results demonstrated the high antitumor activity and low cytotoxicity of [Gd@C(82)(OH)(22)](n) nanoparticles both in vivo and in vitro. Their possible anti-tumor mechanisms were also discussed. The present study may provide new insight into the mechanism of action of these nanoparticles.
Antiangiogenesis is an effective strategy for cancer treatment because uncontrolled tumor growth depends on tumor angiogenesis and sufficient blood supply. Great progress has been made in developing a "molecular" form of angiogenesis inhibitors; however, the narrow inhibition spectrum limits anticancer efficacy as those inhibitors that usually target a few or even a single angiogenic factor among many angiogenic factors might initially be effective but ultimately lead to the failure of the treatment due to the induction of expression of other angiogenic factors. In this work, we report that with a multiple hydroxyl groups functionalized surface, the Gd@C(82)(OH)(22) fullerenic nanoparticles (f-NPs) are capable of simultaneously downregulating more than 10 angiogenic factors in the mRNA level that is further confirmed at the protein level. After studying this antiangiogenesis activity of the f-NPs by cellular experiment, we further investigated its anticancer efficacy in vivo. A two-week treatment with the f-NPs decreased >40% tumor microvessels density and efficiently lowered the speed of blood supply to tumor tissues by approximately 40%. Efficacy of the treatment using f-NPs in nude mice was comparable to the clinic anticancer drug paclitaxel, while no pronounced side effects were found. These findings indicate that the f-NPs with multiple hydroxyl groups serve as a potent antiangiogenesis inhibitor that can simultaneously target multiple angiogenic factors. We propose that using nanoscale "particulate" itself as a new form of medicine (particulate medicine) may be superior to the traditional "molecular" form of medicine (molecular medicine) in cancer treatment.
Nucleotide Binding Domains (NBDs) are responsible for the ATPase activity of the multidrug resistance protein 1 (MRP1). A series of NBD1-linker-NBD2 chimeric fusion proteins were constructed, expressed and purified, and their ATPase activities were analyzed. We report here that a GST linked NBD1(642-890)-GST-NBD2(1286-1531) was able to hydrolyze ATP at a rate of about 4.6 nmol/mg/min (K(m)=2.17 mM, V(max)=12.36 nmol/mg/min), which was comparable to the purified and reconstituted MRP1. In contrast, neither a mixture of NBD1 and GST-NBD2 nor the NBD1-GST-NBD1 fusion protein showed detectable ATPase activity. Additionally, the E1455Q mutant was found to be nonfunctional. Measurements by both MIANS labeling and circular dichroism spectroscopy revealed significant conformational differences in the NBD1-GST-NBD2 chimeric fusion protein compared to the mixture of NBD1 and GST-NBD2. The results suggest a direct interaction mediated by GST between the two NBDs of MRP1 leading to conformational changes which would enhance its ATPase activity.
[Gd@C(82)(OH)(22)](n) is a new type of nanoparticle with potent antineoplastic activity and low toxicity compared with traditional drugs. In this study, we explored, for the first time, the effect of [Gd@C(82)(OH)(22)](n) on the cell cycle using human breast cancer MCF-7 and human umbilical vein endothelial ECV304 cell lines by flow cytometry.
Although a multitude of promising anti-cancer drugs have been developed over the past 50 years, effective delivery of the drugs to diseased cells remains a challenge. Recently, nanoparticles have been used as drug delivery vehicles due to their high delivery efficiencies and the possibility to circumvent cellular drug resistance. However, the lack of biocompatibility and inability to engineer spatially addressable surfaces for multi-functional activity remains an obstacle to their widespread use. Here we present a novel drug carrier system based on self-assembled, spatially addressable DNA origami nanostructures that confronts these limitations. Doxorubicin, a well-known anti-cancer drug, was non-covalently attached to DNA origami nanostructures through intercalation. A high level of drug loading efficiency was achieved, and the complex exhibited prominent cytotoxicity not only to regular human breast adenocarcinoma cancer cells (MCF 7), but more importantly to doxorubicin-resistant cancer cells, inducing a remarkable reversal of phenotype resistance. With the DNA origami drug delivery vehicles, the cellular internalization of doxorubicin was increased, which contributed to the significant enhancement of cell-killing activity to doxorubicin-resistant MCF 7 cells. Presumably, the activity of doxorubicin-loaded DNA origami inhibits lysosomal acidification, resulting in cellular redistribution of the drug to action sites. Our results suggest that DNA origami has immense potential as an efficient, biocompatible drug carrier and delivery vehicle in the treatment of cancer.
The common aggregation of single-wall carbon nanotube (SWCNT) in solution is the critical obstacle to elucidate their unique physico-chemical characteristics and biological properties. Therefore, it is very important to overcome this barrier through manipulation of the weak interaction of small molecules with nanotube surface limited interface. A highly dispersed SWCNT system was achieved by binding with polycyclic organic compounds (POCs) including rhodamine 123, ethidium bromide, fluorescein isothiocyanate and 1-pyrene butyric acid as chaperons, in cooperation with sodium dodecyl sulfate. POCs were believed to penetrate through the interstices of aggregated SWCNTs and bind with individual SWCNTs to form highly dispersed and stable SWCNT-POC-surfactant conjugates in both water and phosphate buffer-serum solution, confirmed by gel electrophoresis, transmission electron microscopy and atomic force microscopy. The possible binding interaction includes ?-? stacking with side-wall, electrostatic interactions with defect sites and coating surfactants. Compared to pristine SWCNTs, individual SWCNT-POC conjugates had improved transmembrane passage ability through both endocytosis and diffusion pathways, validated by laser scanning confocal microscopy and micro-Raman mapping techniques. For the applications of SWCNTs in drug delivery, in vitro imaging and other research fields, this novel strategy could provide highly dispersed SWCNTs with better efficiency of drug loading and stability.
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