Tat-LK15运载siRNA沉默RGC-5神经细胞nNOS基因的实验研究

目的探讨离体条件下细胞穿透肽Tat-LK15运载小干扰RNA(small interference RNA,siRNA)沉默RGC-5视神经节细胞(retinal ganglion cell line,RGC-5)神经元型一氧化氮合酶(neuronal nitric oxide synthase,n NOS)基因的可行性,为在体条件下研究Tat-LK15运载siRNA沉默n NOS表达治疗神经病理性疼痛提供理论依据。方法 1通过凝胶阻滞分析测定Tat-LK15与siRNA的最佳交联比。流式细胞术检测Tat-LK15/FAM-siRNA以最佳交联比转染RGC-5细胞的转染效率;不同剂量Tat-LK15(1、2.5、5、10和20μg)孵育RGC-5细胞24 h,流式细胞术检测细胞凋亡率。2制备n NOS高表达的RGC-5细胞模型。3将RGC-5细胞随机分为5组:对照组、模型组、Tat-S组(Tat-LK15运载n NOS/siRNA转染模型细胞)、Lipo-S组(LipofectamineTMRNAi MAX运载n NOS/siRNA转染模型细胞)及Tat-N组(Tat-LK15运载NCsiRNA转染模型细胞),通过Q-PCR及Western blot检测各组nN OS表达水平。结果 Tat-LK15与siRNA质量比为2∶1时可完全包裹siRNA,达到最佳交联,此时其转染效率为(84.4±3.9)%。当Tat-LK15剂量为20μg(6.1μmol·L-1)时才出现一定细胞毒性,细胞凋亡率高于对照组[(10.3±1.1)%vs(7.4±0.9)%,P<0.05]。造模后RGC-5细胞nN OS表达水平明显升高(P<0.05)。与模型组相比,Tat-S组nN OS mRNA及蛋白表达水平降低(P<0.05),Tat-S组与Lipo-S组相比无差异(P>0.05)。结论Tat-LK15能高效转染siRNA,细胞毒性低,离体条件下可有效运载siRNA沉默nN OS的基因表达。     

Delivery systems for siRNA drug development in cancer therapy

Since the discovery of the Nobel prize-winning mechanism of RNA interference (RNAi) ten years ago, it has become a promising drug target for the treatment of multiple diseases, including cancer. There have already been some successful applications of siRNA drugs in the treatment of age-related macular degeneration and respiratory syncytial virus infection. However, significant barriers still exist on the road to clinical applications of siRNA drugs, including poor cellular uptake, instability under physiological conditions, off-target effects and possible immunogenicity. The successful application of siRNA for cancer therapy requires the development of clinically suitable, safe and effective drug delivery systems. Herein, we review the design criteria for siRNA delivery systems and potential siRNA drug delivery systems for cancer therapy, including chemical modifications, lipid-based nanovectors, polymer-mediated delivery systems, conjugate delivery systems, and others.     

Efficacy and mechanism of antiresistant vinorelbine liposomes in treating resistant breast cancer cells

Among the comprehensive treatment strategies of breast cancer, chemotherapy plays a crucial role in eliminating cancer cells. However, multidrug resistance is one of the major obstacles to successful treatment. The objectives of this study were to construct an antiresistant vinorelbine liposomes and to demonstrate the efficacy and mechanism for treating resistant breast cancer cells. The study was performed using breast cancer MCF-7/adr cells. The antiresistant vinorelbine liposomes were modified with tamoxifen and dequalinium. The average particle size of antiresistant vinorelbine liposomes were approximately 100 nm, and they showed a robust overall anticancer efficacy by direct killing and by apoptosis induction. The mechanisms were associated with increased cellular uptake, decreased ABCB1 and ABCC10 transporters, and targeting to mitochondria. The apoptosis signaling pathways were ralated to activiated caspases (8, 9, 3), induced release of cytochrome c from mitochondria, activated Bax, inhibited Mcl-1, and generation of ROS. The new antiresistant vinorelbine liposomes could be a useful formulation deserving further development, and the present study provides a potential strategy for circumventing drug resistance in breast cancer.     

siRNA体内递送的研究现状

RNAi是用来沉默特定基因的一个强有力的研究工具,并为基因治疗策略带来新希望。目前已经用于治疗肿瘤、乙型肝炎、老年性黄斑变性等疾病。RNAi的效应分子为小分子干扰RNA（siRNA）,然而裸siRNA自身具有电负性、分子量大、极性强、半衰期短,以及容易被内源酶降解和肾小球滤过等缺陷,使其临床应用受到极大的限制。如何通过对siRNA进行化学修饰和载体构建,包括运用病毒性载体和非病毒性载体,以提高siRNA的体内稳定性,成为当前的研究重点。本文对siRNA结构的化学修饰、siRNA的载体递送以及临床试验等研究现状予以综述     

Efficient gene delivery with serum into human cancer cells using targeted anionic liposomes

Success of human gene therapy depends upon the development of delivery vehicles or vectors, which can selectively deliver therapeutic genes to target cells with efficiency and safety. Previous studies have shown an efficient, systemic trans-gene expression in many cell lines (in vitro) by using an anionic liposomal vector, based on the composition of retroviral envelopes (artificial viral envelopes, AVEs). The AVE-liposomes and their complexes with plasmid (DNA) were characterized according to zeta potential measurements and transmission electron microscopy (TEM). We successfully demonstrated that AVE liposomes, dispersed in 10% serum-containing growth medium, efficiently delivered plasmid DNA to HuH-7 (human hepatoma cell line) cells. We assessed the utility of liver-targeted vesicles as a drug/gene delivery system for the treatment of liver diseases. We found that small unilamellar AVE vesicles containing 15 mol% digalactosyl diglyceride (DGDG) are efficiently targeted to the liver via the hepatic asialoglycoprotein receptor.     

GL67 lipid-based liposomal formulation for efficient siRNA delivery into human lung cancer cells

The efficient delivery of small interfering RNA (siRNA) to the targeted cells significantly affects the regulation of the overexpressed proteins involved in the progression of several genetic diseases. SiRNA molecules in naked form suffer from low internalization across the cell membrane, high susceptibility to degradation by nuclease enzyme and low stability, which hinder their efficacy. Therefore, there is an urge to develop a delivery system that can protect siRNA from degradation and facilitate their uptake across the cell membrane. In this study, the cationic lipid (GL67) was exploited, in addition to DC-Chol and DOPE lipids, to design an efficient liposomal nanocarrier for siRNA delivery. The physiochemical characterizations demonstrated that the molar ratio of 3:1 has proper particle size measurements from 144 nm to 332 nm and zeta potential of −9 mV to 47 mV that depends on the ratio of the GL67 in the liposomal formulation. Gel retardation assay exhibited that increasing the percentage of GL67 in the formulations has a good impact on the encapsulation efficiency compared to DC-Chol. The optimal formulations of the 3:1 M ratio also showed high metabolic activity against A549 cells following a 24 h cell exposure. Flow cytometry findings showed that the highest GL67 lipid ratio (100 % GL67 and 0 % DC-Chol) had the highest percentage of cellular uptake. The lipoplex nanocarriers based on GL67 lipid could potentially influence treating genetic diseases owing to the high internalization efficiency and safety profile.     

Delivery of gamma-imaging agents by liposomes

Liposomes are spherical bilayers which spontaneously form when water is added to a dried lipid mixture. Much progress has been made in the use of liposomes as vehicles for the delivery of gamma imaging agents. These radiolabeled liposomes have a wide variety of potential diagnostic uses including the detection of sites of infection, inflammation, gastrointestinal bleeding, tumor, cardiac blood pool imaging and lymphoscintigraphy. The ability to modify the surface of the liposomes permits the customization of liposome formulations for each particular diagnostic use.     

载siRNA阳离子脂质体的制备

目的制备载siRNA阳离子脂质体并对其进行制剂学评价。方法利用siRNA与溴化乙锭结合能产生荧光的原理,采用预染溴化乙锭(Ethidium Bromide,EB)琼脂糖凝胶,氨基丁三醇-硼酸-乙二胺四乙酸(Tris-Boric acid-EDTA,TBE)电泳缓冲液将游离siRNA分离并通过凝胶成像分析系统转换数据进行定性和定量,计算载siRNA阳离子脂质体包封率,并考察其阴离子的抵御能力和血清稳定性;利用Malver粒径和zeta电位测定仪对不同载siRNA阳离子脂质体进行评价。结果琼脂糖凝胶电泳法的线性为0.665~13.30 mg·L-1(R2=0.988 3),回收率为97%~103%,精密度RSD<2%,阳离子脂质体对siRNA包封率较高,且具有良好的抵御阴离子能力和较强的血清稳定性;载siRNA阳离子脂质体的粒径和zeta电位变化与文献报道一致。结论所制备的载siRNA阳离子脂质体体外性质均良好。     

Delivery and biodistribution of siRNA for cancer therapy: challenges and future prospects

RNAi-based approaches provide a promising therapeutic modality for the treatment of cancer. The inaccessibility of tumors in different cancer types necessitates the development of safe, specific and efficient systemic delivery systems to meet therapeutic need. The translation of siRNA-based cancer therapeutics to the clinic is hindered by several challenges associated with the cargo (siRNA) and the delivery system, including susceptibility to nucleases; insufficient circulation half-life due to phagocytosis by the reticuloendothelial system, transient and poor biodistribution in the tumor tissue; cellular uptake; inability to escape endosomes and release into the cytosolic compartment for an RNAi-mediated effect; microRNA-like unintended off-target effects; undesirable immune stimulation; and carrier-related toxicity. This review provides an overview of the pharmacokinetic and biodistribution challenges witnessed in the delivery of siRNA when administered systemically. It also describes the current delivery approaches using liposome-, polymer- and peptide-based delivery systems shown to elicit significant gene silencing and tumor growth regression in proof-of-concept studies. As part of future perspectives, delivery agents that showed significant efficacy in preclinical rodent models and clinical trials are also reviewed.     

Let-7 miRNA and CDK4 siRNA co-encapsulated in Herceptin-conjugated liposome for breast cancer stem cells

Recently, breast cancer stem cells (BCSCs) have rapidly emerged as a novel target for the therapy of breast cancer as they play critical roles in tumor growth, maintenance, metastasis, and recurrence. Let-7 miRNA is known to be downregulated in a variety of cancers, especially BCSCs, whereas CDK4 being overexpressed in human epidermal growth factor receptor 2 (HER-2) overexpressing tumor cells. In this study, let-7 miRNA and CDK4-specific siRNA were chosen as therapeutic agents and co-encapsulated in Herceptin-conjugated cationic liposomes for breast cancer therapy. Particle size, zeta potential, and encapsulation efficacy of mi/siRNA-loaded PEGylated liposome conjugated with Herceptin (Her-PEG-Lipo-mi/siRNA) were 176 nm, 28.1 mV, and 99.7% ± 0.1%, respectively. Enhanced cellular uptake (86%) was observed by fluorescence microscopy when SK-BR-3 cells were treated with Her-PEG-Lipo-mi/siRNA. Also, the increased amount of let-7a mRNA and decreased amount of cellular CDK4 mRNA were observed by qRT-PCR when SK-BR-3 cells were treated with Her-PEG-Lipo-mi/siRNA, which was even more so when SK-BR-3 stem cells were used (197 vs 768 times increase for let-7a, 62% vs 68% decrease for CDK4). Growth inhibition (65%) and migration arrest (0.5%) of the cells were achieved by the treatment of the cells with Her-PEG-Lipo-mi/siRNA, but not with mi/siRNA complex or other formulations. In conclusion, an efficient liposomal delivery system for the combination of miRNA and siRNA to target the BCSCs was developed and could be used as an efficacious therapeutic modality for breast cancer.     

Dual-modified cationic liposomes loaded with paclitaxel and survivin siRNA for targeted imaging and therapy of cancer stem cells in brain glioma

Development of safe, efficient nanocomplex for targeted imaging and therapy of cancer stem cells in brain glioma has become a great challenge. Herein, a low-density lipoprotein receptor-related protein and a RNA aptamer bound CD133 were used as dual-targeting ligands to prepare dual-modified cationic liposomes (DP-CLPs) loaded with survivin siRNA and paclitaxel (DP-CLPs–PTX–siRNA) for actively targeting imaging and treating CD133⁺ glioma stem cells after passing through the blood–brain barrier. After being administrated with DP-CLPs–PTX–siRNA nanocomplex, DP-CLPs showed a persistent target ability to bind glioma cells and brain microvascular endothelial cells (BCECs) and to deliver drugs (PTX/siRNA) to CD133⁺ glioma stem cells. Prepared DP-CLPs–PTX–siRNA nanocomplex showed very low cytotoxicity to BCECs, but induced selectively apoptosis of CD133⁺ glioma stem cells, and improved CD133⁺ glioma stem cells' differentiation into non-stem-cell lineages, also markedly inhibited tumorigenesis, induced CD133⁺ glioma cell apoptosis in intracranial glioma tumor-bearing nude mice and improved survival rates. In conclusion, prepared DP-CLPs–PTX–siRNA nanocomplex selectively induced CD133⁺ glioma stem cell apoptosis in vitro and in vivo exhibits great potential for targeted imaging and therapy of brain glioma stem cells.     

Co-delivery of curcumin and STAT3 siRNA using deformable cationic liposomes to treat skin cancer

Skin cancer is one of the most widely prevalent cancer types with over expression of multiple oncogenic signaling molecules including STAT3. Curcumin is a natural compound with effective anti-cancer properties. The objective of this work was to investigate the liposomal co-delivery of curcumin and STAT3 siRNA by non-invasive topical iontophoretic application to treat skin cancer. Curcumin was encapsulated in cationic liposomes and then complexed with STAT3 siRNA. The liposomal nanocomplex was characterized for particle size, zeta-potential, drug release and stability. Human epidermoid (A431) cancer cells were used to study the cell uptake, growth inhibition and apoptosis induction of curcumin-loaded liposome–siRNA complex. Topical iontophoresis was applied to study the skin penetration of nanocomplex in excised porcine skin model. Results showed that curcumin-loaded liposome–siRNA complex was rapidly taken up by cells preferentially through clathrin-mediated endocytosis pathway. The co-delivery of curcumin and STAT3 siRNA using liposomes resulted in significantly (p?<?.05) greater cancer cell growth inhibition and apoptosis events compared with neat curcumin and free STAT3 siRNA treatment. Furthermore, topical iontophoresis application enhanced skin penetration of nanocomplex to penetrate viable epidermis. In conclusion, cationic liposomal system can be developed for non-invasive iontophoretic co-delivery of curcumin and siRNA to treat skin cancer.     

Pseudovirions as Vehicles for the Delivery of siRNA

Over the last two decades, small interfering RNA (siRNA)-mediated gene silencing has quickly become one of the most powerful techniques used to study gene function in vitro and a promising area for new therapeutics. Delivery remains a significant impediment to realizing the therapeutic potential of siRNA, a problem that is also tied to immunogenicity and toxicity. Numerous delivery vehicles have been developed, including some that can be categorized as pseudovirions: these are vectors that are directly derived from viruses but whose viral coding sequences have been eliminated, preventing their classification as viral vectors. Characteristics of the pseudovirions discussed in this review, namely phagemids, HSV amplicons, SV40 in vitro-packaged vectors, influenza virosomes, and HVJ-Envelope vectors, make them attractive for the delivery of siRNA-based therapeutics. Pseudovirions were shown to deliver siRNA effector molecules and bring about RNA interference (RNAi) in various cell types in vitro, and in vivo using immune-deficient and immune-competent mouse models. Levels of silencing were not always determined directly, but the duration of siRNA-induced knockdown lasted at least 3 days. We present examples of the use of pseudovirions for the delivery of synthetic siRNA as well as the delivery and expression of DNA-directed siRNA.