siRNA非病毒递送载体的研究现状

RNA干扰(RNA interference,RNAi)是近年发展起来的一种新技术。RNAi是指通过外源性或内源性的双链RNA在体内诱导靶基因mRNA产生特异性降解,进而引起不同水平的基因沉默。RNAi已经用于肿瘤、病毒感染、乙型肝炎等多种疾病的治疗。小干扰RNA(siRNA)是RNAi的效应分子,可在体内诱导RNAi效应。但是裸siRNA在体内容易被核酶(RNase)降解,且半衰期短,转染效率低。因此,siRNA需要借助递送载体进入细胞发挥治疗作用。病毒载体在基因治疗中有潜在的免疫原性、致突变等副作用。所以,非病毒载体成为当前的研究热点。本文对siRNA非病毒递送载体的研究现状进行了综述。     

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     

shRNA病毒递送载体

RNA干扰(RNA interference,RNAi)是一种有力的基因沉默工具,在功能基因组学、微生物学、基因表达调控机制研究等领域广泛应用。RNAi可以用于鉴定药物靶标及治疗疾病,尤其是传统治疗手段无效的重大疾病。如何将双链小干扰RNA(siRNA)高效传递至体内靶细胞是RNAi成功用于疾病治疗的关键,也是目前研究的热点。由于病毒载体能高效转导多种细胞成为基因工程和基因治疗的主要载体。目前,越来越多的研究将病毒载体应用于介导RNAi,然而病毒载体存在靶向性差、生物安全性等问题。本文针对这些病毒载体的优劣进行归纳并指出今后改进的方向。     

RNA干扰抗HBV的研究进展

RNA干扰是由长的双链RNA（double—stranded RNA．dsRNAl引发的降解与之同源的信使RNA（messager RNA，mRNA）的过程，dsRNA进入真核细胞．在胞浆内经限制性核酸内切酶Dicer作用，被切割成21—23bp的大小的小分子干扰RNA片段（small interfering RNAs,siRNhs），siRNAs与核酶复合物结合从而形成所谓的RNA诱导沉默复合物（RNA—induced silencing complex。RISC）。激活的RISC可以精确降解与siRNAs序列同源的mRNA．完全抑制了该基因在细胞内的翻译和表达。RNAi可以用来降低或清除内源性异常基因如癌基因表达和抵抗外源性入侵遗传学分子如转座子、转基因、病毒等．被认为是一种古老的保护体免受病毒入侵的机制．因此对传染性疾病的治疗可以说是RNAi最具前景的应用。     

siRNA作为基因治疗药物的研究难题

RNA干扰（RNAi）现象的发现与研究，为基因治疗带来新的契机，虽然小干扰RNA（siRNA）较单链反义寡核苷酸显示了更好的稳定性与基因沉默效果，但却同样面临基因治疗药物存在的共同问题，如体内的靶向性与有效性、完善的定量分析方法等等。因此，siRNA作为治疗药物还有诸多困难需要克服。目前的研究主要集中在：修饰方式与递送系统研究，以提高siRNA体内的稳定性与靶向性；siRNA定量分析方法学研究，以考察其体内药动学行为并进一步阐明其体内作用机制。     

基于RNAi的新型药物浮出水面

RNA干扰的治疗前景RNA干扰(RNAi)是一种高度保守的内源性基因沉默机制,发现于1998年,为双链RNA介导的序列专一性降解mRNA。科学家们很快就认识到了RNAi的治疗潜力。目前,有多家公司正在研发RNAi药物。Sirna公司报道了第一个基于RNAi干扰的药物Sirna-027,现处于Ⅰ期临床试验阶段     

生物技术及产品-RNAi：从核苷酸到临床应用还有相当距离

RNA干涉（RNAi）的发现从根本上改变了我们对生物学的理解,并为掌控这种天然过程的生物研究创造了一件强有力的工具。RNAi技术是药物研发越来越重要的平台。如同单克隆抗体（MAb）,RNAi治疗代表一种新的治疗模式。然而,同样地要开发一项赢得诺贝尔奖的发现直到广泛治疗应用可能要假以时日。有几个因素将推动RNAi从实验室推进到临床的决定。首先,人基因组项目的完成使得有可能设计能沉默任何基因的小干涉RNA（siRNA）。     

N-乙酰半乳糖胺偶联小干扰RNA类药物的非临床毒性研究进展

小干扰核糖核酸（siRNA）作为核苷酸类药物,通过RNA干扰（RNAi）特异性诱导基因沉默而发挥作用,在代谢性疾病、抗感染及肿瘤等领域被广泛应用。目前已获批上市4款基于N-乙酰半乳糖胺（GalNAc）偶联技术siRNA药物,汇总分析已上市GalNAc偶联药物的非临床毒性特征及临床不良反应,初步明确非临床研究中毒性常见类型,包括脱靶与非脱靶毒性等。结合GalNAc-siRNA类药物非临床研究实践,了解可预测的脱靶毒性及对于非临床安全性评价中的毒性关注点,以期为GalNAc-siRNA药物临床研究提供参考。     

006 基于RNAi的新型药物浮出水面

RNA干扰的治疗前景RNA干扰（RNAi）是一种高度保守的内源性基因沉默机制，发现于1998年，为双链RNA介导的序列专一性降解mRNA。科学家们很快就认识到了RNAi的治疗潜力。     

RNAi在神经退行性疾病发病机制及防治研究中的应用

RNA干扰（RNA interference，RNAi）技术能特异性降解mRNA，沉默靶基因，在转录后水平抑制基因的表达，从而可用来进行基因功能的分析和药物靶标的研究。RNAi技术日趋成熟，已被广泛应用于生命科学的各个领域。在神经科学上，尤其是在神经退行性疾病，如阿尔茨海默病、帕金森病、亨廷顿病、脊髓小脑性共济失调、肌萎缩性侧索硬化症、朊病毒病等的研究中取得了显著进展，RNAi的应用为神经退行性疾病发病机制的揭示和治疗另辟了蹊径。     

RNA interference may be more potent than antisense RNA in human cancer cell lines

1. RNA interference (RNAi) is a newly discovered cellular pathway for the silencing of sequence-specific genes at the mRNA level by the introduction of the cognate double-stranded (ds) RNA. Because antisense (AS) mechanisms have similar effects, we compared these two effects in human cancer cell lines, considering a possible application of RNAi for cancer therapy. 2. We tested RNAi effects by transfecting human hepatoma and pancreatic cancer cell lines with AS and sense (S) RNA expression plasmids corresponding to the exogenous luciferase gene or the endogenous c-raf gene in the form of complexes with a cationic lipopolyamine or a tumour-targeting peptide vector we developed. In addition, we compared the effects of small interfering RNA and AS oligoDNA complexed with the peptide vector. 3. From the viewpoint of AS actions, the effect of the AS RNA may be cancelled by the S RNA, although, interestingly, we found that the combination of the AS and S RNA expression plasmids was more effective than the AS RNA expression plasmids alone in reducing target gene expression, whereas the S RNA expression plasmids had no effects. The combination of the luciferase AS and S RNA had no effects on the expression of either the beta-galactosidase gene or the c-raf gene. In the presence of 2-aminopurine (an inhibitor of dsRNA-activated protein kinase), the inhibitory effect of the combination of AS and S RNA on gene expression did not change in the case of the endogenous c-raf gene, but was reduced in the case of the exogenous luciferase gene. The effect of 22 nucleotide RNA duplexes corresponding to the luciferase gene was by one order stronger than that of the phosphorothioate AS DNA. 4. Thus, it is suggested that RNAi may be more potent than AS RNA in reducing target gene expression in human cancer cell lines, regardless of the length of dsRNA. With further studies on the RNAi phenomenon in cancer cells, RNAi could provide a novel approach for cancer gene therapy.     

Knocking Down Transport: Applications of RNA Interference in The Study of Drug Transport Proteins

RNA interference (RNAi) is a gene silencing process mediated by double-stranded RNA (dsRNA). The silencing process is comprised of an initiation step, in which small interfering RNA (siRNA) is introduced to the cell, and an effector step, which involves degrading mRNA molecules of the target gene. RNA interference has been observed in most organisms from plants to vertebrates. As a gene silencing approach, RNAi has proven to be extremely useful in characterizing gene function and developing new tools in cancer therapy and drug delivery. The development of RNAi-related technologies is an emerging area in biomedical research. In this review, recent progress in the application of RNAi to the study of transport proteins is summarized and evaluated; the advantages, disadvantages and future directions of RNAi technology are discussed.     

Knocking down transport: applications of RNA interference in the study of drug transport proteins

RNA interference (RNAi) is a gene silencing process mediated by double-stranded RNA (dsRNA). The silencing process is comprised of an initiation step, in which small interfering RNA (siRNA) is introduced to the cell, and an effector step, which involves degrading mRNA molecules of the target gene. RNA interference has been observed in most organisms from plants to vertebrates. As a gene silencing approach, RNAi has proven to be extremely useful in characterizing gene function and developing new tools in cancer therapy and drug delivery. The development of RNAi-related technologies is an emerging area in biomedical research. In this review, recent progress in the application of RNAi to the study of transport proteins is summarized and evaluated; the advantages, disadvantages and future directions of RNAi technology are discussed.     

RNA interference and its therapeutic potential

RNA interference is a technique that has become popular in the past few years. This is a biological method to detect the activity of a specific gene within a cell. RNAi is the introduction of homologous double stranded RNA to specifically target a gene’s product resulting in null or hypomorphic phenotypes. This technique involves the degradation of specific mRNA by using small interfering RNA. Both microRNA (miRNA) and small interfering RNA (siRNA) are directly related to RNA interference. RNAi mechanism is being explored as a new technique for suppressing gene expression. It is an important issue in the treatment of various diseases. This review considers different aspects of RNAi technique including its history of discovery, molecular mechanism, gene expression study, advantages of this technique against previously used techniques, barrier associated with this technique, and its therapeutic application.     

RNA干扰的研究进展

RNA干扰（RNAi）是由双链RNA介导，在转录后mRNA水平关闭相应基因表达的新基因阻断技术，在基因功能研究、基因治疗方面已显示出巨大的前景。同时，RNAi的分子机制研究也不断取得进展，包括对基因转录后水平、翻译水平、基因甲基化及沉默信号的传递等层次的研究。清晰阐述RNAi作用机理将为大规模的基因系统筛查、新基因的发现、人类肿瘤及难治性疾病的基因治疗提供重要理论依据和有力工具。     

Potential applications of siRNA in hepatitis C virus therapy

Small interfering RNAs (siRNAs) are short RNA duplexes approximately 21 nucleotides long. When introduced into mammalian cells, siRNA can silence specific gene expression. Hepatitis C virus (HCV) replicates in the cytoplasm of liver cells without integration into the host genome. Because the HCV genome is a single-stranded RNA that functions both as a messenger RNA and as a viral replication template, destruction of HCV RNA could eliminate not only virally directed protein synthesis, but also viral replication. It has been demonstrated that siRNAs interfere with HCV gene expression and replication, and this review will describe the use of RNAi as a tool to inhibit HCV gene expression.     

The new technology for controlling gene function in zebrafish

The technology for the control of gene function is necessary not only to study development, but also to study pharmacology and to invent new medicines. Morpholino oligo blocks mRNA translation and, as a result, inhibits gene function, mimicking the mutation of the gene. As the method is quite simple and effective, morpholino oligo has been an essential tool in developmental biology. Caged RNA is an innovative technology evolved in Japan. Caged RNA is reduced in translational activity, whereas illumination of caged RNA with ultraviolet light leads to recovery of translational activity. Using caged RNA, we will be able to activate the translation of any gene at any time and in any cell(s) we want.     

Ribozyme and peptide-nucleic acid-based gene therapy

The recent discovery that RNA can act as a catalyst, apart from carrying genetic information, has given a new dimension to the field of gene therapy and has come to act synergistically with antisense technology. Ribozymes can be used to down-regulate (by RNA cleavage) or repair (by RNA trans-splicing) unwanted gene expression involved in disease. Hammerhead ribozymes have been used extensively to down-regulate gene expression in many diseases such as viral infections and cancer. Group I intron ribozymes on the other hand, have only been tried to repair inherited mutations but hold great promise for the future. Peptide nucleic acids (PNAs) technology is another new technology, which is currently been tried to block gene or RNA function. Gene therapy protocols need significant improvements in order to be used routinely in patients and hopefully, these new players should prove valuable to identifying new therapies for several untreated diseases.