RNAi药物的临床研究进展

RNA干扰（RNAi）是指在细胞内由双链RNA（double-stranded RNA,dsRNA）介导的降解同源序列的mRNA,从而抑制相应基因表达的现象。它是转录后基因沉默（PTGS）的一种。RNA干扰不仅是基础研究的热点．也是临床应用研究的热点．小干扰RNA（siRNA）药物虽然在国际上已有部分进入Ⅰ-Ⅲ期临床研究,但是siR—NA的脱靶效应、siRNA的导入等实际问题一直是RNA干扰临床治疗的最大障碍。核酸药物比传统的化学分子甚至比蛋白质更容易被降解,而RNA干扰药物的有效传递依旧是RNAi药物临床应用的拦路虎,该技术一旦被攻克．将会被广泛应用于基因性疾病、传染性疾病及恶性肿瘤的临床治疗。本文就RNA干扰的作用机制、临床应用、存在问题及广阔前景作一简要综述。     

癌症治疗中小干扰RNA治疗方法及载体的研究概况

癌症是当前危害人类健康的主要疾病之一。采用传统的手术、化疗等治疗手段无法完全根除或杀死肿瘤细胞,且易发生转移和复发等现象。由于小干扰RNA（siRNA）介导的基因沉默技术可通过破坏目的蛋白mRNA的完整性,达到抑制疾病相关基因表达的作用;且siRNA因其高效性、特异性特点以及作为基因药物的巨大潜力,备受研究者的青睐。本文就小干扰RNA技术的作用机制、小干扰RNA药物传递系统及其在抗肿瘤领域的相关应用进行综述。     

全身RNA干扰的重大突破

RNA干扰已经成为一种强有力的研究工具，然而这项技术在临床治疗应用方面的进展最近才开始起步。这个领域最主要的进展是Zimmermann等在Nature上首先报道的在灵长类动物中全身递送小分子干扰RNA（siRNA）后的基因沉默效应。     

siRNA体内递送研究进展

RNA干扰(RNA interference,RNAi),是一种在动植物中存在的通过双链RNA诱导同源特异性序列转录后基因沉默的过程。虽然小干扰RNA (siRNA) 较单链反义寡核苷酸显示出更好的稳定性与基因沉默效果,但是作为新型的基因治疗药物,靶向递送siRNA是药物进入临床应用最主要的环节,siRNA体内有效作用发挥的关键在于它在体内能否高效递送至靶细胞并与靶基因结合。目前研究主要集中在siRNA的修饰方式与递送载体研究,以提高其体内的稳定性与靶向性。文中主要综述了siRNA的体内靶向递送障碍以及近几年siRNA非病毒递送载体脂质体、阳离子多聚物、纳米粒、胶束等方面的研究进展。     

c-Myc靶向小分子干扰RNA抑制人直肠癌Colo320细胞增殖的实验研究

目的：利用小分子干扰RNA（siRNA）技术抑制人直肠癌Colo320细胞c-Myc基因的表达。为研究c-Myc基因在人直肠癌Colo320细胞中的作用提供一个新的方法。方法：设计人直肠癌Colo320细胞基因特异性小分子干扰RNA，用体外转录方法合成人直肠癌Colo320细胞基因的小分子干扰RNA并转染人直肠癌Colo320细胞，培养48—96h后，收集细胞RNA应用实时荧光定量RT—PCR方法检测转染细胞中c-Myc基因mRNA水平变化，骶temblot检测C—MYC蛋白的表达，四甲基偶氮唑蓝（MTT法）和集落形成实验检测细胞增殖活性。结果：转染siRNA后，与对照组相比，实验组pGensil—c—Myc-14的c-Myc基因mRNA水平明显降低，MTT法和集落形成实验表明实验组的增殖速率明显低于对照组的增殖速率。结论：在人直肠癌Colo320细胞中存在RNA干扰的机制，特异性siRNA能够有效的抑制c-Myc基因的表达，为研究c-Myc基因在肿瘤细胞中的调节途径提供了一个新的方法。     

siRNA新型非病毒载体递送策略新进展

小干扰RNA(siRNA)是一个靶向治疗和精确医学的代表性治疗工具，可通过序列特异性的RNA干扰(RNAi)沉默任何疾病相关基因的表达。然而，它的治疗前景历来受到体内半衰期短、递送困难和安全问题的限制。非病毒载体介导的药物递送已经成为克服这些局限性的一个成功策略，可实现siRNA在体内的有效递送，高效沉默靶基因。目前，已有多种药物处于临床试验中，4种基于siRNA的新型疗法已获得美国FDA的批准，标志着靶向疗法新时代的开始。该文概述了近年来基于siRNA的非病毒载体递送策略的新进展及其应用，并展望了siRNA药物研究的未来发展趋势。     

siRNA抗乙型肝炎病毒研究进展

现有的抗乙肝病毒药物如α-干扰素和核苷类似物药物,若长期应用会引起病毒变异,许多学者都在探索新的抗乙肝病毒途径.小干扰RNA(small interfering RNA,siRNA)的发现受到科学界的广泛重视,其介导的序列特异性基因沉默可有效抑制内源性、外源性基因的表达[1].目前,应用RNA干扰(RNA interference,RNAi)治疗肿瘤、艾滋病和肝炎等方面已经取得了重大进展.     

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。     

siRNA干扰技术在乳腺癌中的研究进展

<正>RNA干扰(RNAi)是指在生物进化过程中高度保守的、由双链RNA(dsRNA)诱发的、同源信使RNA高效特异性降解的现象[1]。RNA干扰其效应因子是小分子干扰RNA(siRNA)。由于使用RNAi技术可以特异性剔除或关闭特定基因的表达,因具有高特异性、高效性、细胞穿透性等特点,已成为靶向基因治疗的又一有力工具,尤其是恶性肿瘤的基因治疗。本文就近年来siRNA干扰技术及其在乳腺     

RNA interference and innate immunity

RNA interference is an evolutionarily conserved gene silencing process triggered by double-stranded RNAs. Common to all cell types, is the production of 21-24 nucleotide small interfering RNA (siRNAs), which guide the RNA-induced silencing complex (RISC) to identify and cleave target mRNA sequences. Presently, this biological breakthrough method has revolutionised gene function studies and holds great promise as validating drug targets and treating human diseases. However, despite the success that has been achieved by this technology, studies carried in human blood cells have revealed that siRNAs could generate bystander effects, including the activation of innate immunity and inhibition of unintended target genes. Interestingly, 2' uridine-modified siRNAs did not trigger TLR signalling, but they totally suppressed immune activation by immunostimulatory siRNAs when both molecules where delivered to the same endosomes. This review describes the recent advances in understanding the innate immune response to both single and double-stranded siRNAs. Also, it highlights the spectrum of molecular strategies allowing the design of therapeutic siRNAs with minimal side effects.     

On the delivery of small interfering RNAs into mammalian cells

RNA interference is becoming the technique of choice for analysing gene function and drug target validation. In this process, sequence-specific gene inhibition is initiated by small RNA duplexes, known as small interfering RNAs (siRNAs). The possibility that exogenously delivered siRNAs or endogenously expressed hairpin siRNAs can cause the destruction of specific target mRNA in vitro and in animal models has been demonstrated. However, the key challenges for the development of siRNAs as human therapeutics is largely dependent on the development of suitable delivery agents and improved siRNA specificity. This review highlights recent advances in siRNA delivery, as well as challenging problems related to immune stimulation.     

On the delivery of small interfering RNAs into mammalian cells

RNA interference is becoming the technique of choice for analysing gene function and drug target validation. In this process, sequence-specific gene inhibition is initiated by small RNA duplexes, known as small interfering RNAs (siRNAs). The possibility that exogenously delivered siRNAs or endogenously expressed hairpin siRNAs can cause the destruction of specific target mRNA in vitro and in animal models has been demonstrated. However, the key challenges for the development of siRNAs as human therapeutics is largely dependent on the development of suitable delivery agents and improved siRNA specificity. This review highlights recent advances in siRNA delivery, as well as challenging problems related to immune stimulation.     

siRNA--getting the message out.

The recent observation that potent and sequence-specific gene silencing by injection of double-stranded RNA (dsRNA) has sparked the phenomenon known as "RNA interference" (RNAi) and has enabled the gene-specific knockdown of drug transport proteins and metabolizing enzymes. The application of small interfering RNAs (siRNAs) is broad and the potential for use as research tools is now well established in vitro. In vivo use is still a challenge that is primarily focused on the difficulty of delivering siRNAs to target cells. The potential use of siRNAs as therapeutic agents is also exciting and holds great promise for future. For the study of drug transporter function in absorption, distribution, metabolism and excretion (ADME) and in the treatment of diseases, siRNA offers a way to gather interpretable mechanistic data-a distinct advantage over the use of "specific" chemical inhibitors. This mini review provides background information on siRNA as well as examples of the use of siRNA as applied to drug transporters.     

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.     

Inhibition of RNAse A family enzymes prevents degradation and loss of silencing activity of siRNAs in serum

Small interfering RNAs (siRNA), RNA duplexes of approximately 21 nucleotides, offer a promising approach to specifically degrade RNAs in target cells by a process termed RNA interference. Insufficient in vivo-stability is a major problem of a systemic application of siRNAs in humans. The present study demonstrated that RNAse A-like RNAses degraded siRNAs in serum. The susceptibility of siRNAs towards degradation in serum was strongly enhanced by local clustering of A/Us within the siRNA sequence, i.e. regions showing low thermal stability, most notably at the ends of the molecule, and by 3'-overhanging bases. Importantly, inhibition of RNAse A family enzymes prevented the degradation and loss of silencing activity of siRNAs in serum. Furthermore, the degradation of siRNAs was considerably faster in human than in mouse serum, suggesting that the degradation of siRNAs by RNAse A family enzymes might be a more challenging problem in a future therapeutic application of siRNAs in humans than in mouse models. Together, the present study indicates that siRNAs are degraded by RNAse A family enzymes in serum and that the kinetics of their degradation in serum depends on their sequence. These findings might be of great importance for a possible future human therapeutic application of siRNAs.     

siRNA—Getting the message out

The recent observation that potent and sequence-specific gene silencing by injection of double-stranded RNA (dsRNA) has sparked the phenomenon known as “RNA interference” (RNAi) and has enabled the gene-specific knockdown of drug transport proteins and metabolizing enzymes. The application of small interfering RNAs (siRNAs) is broad and the potential for use as research tools is now well established in vitro. In vivo use is still a challenge that is primarily focused on the difficulty of delivering siRNAs to target cells. The potential use of siRNAs as therapeutic agents is also exciting and holds great promise for future. For the study of drug transporter function in absorption, distribution, metabolism and excretion (ADME) and in the treatment of diseases, siRNA offers a way to gather interpretable mechanistic data—a distinct advantage over the use of “specific” chemical inhibitors. This mini review provides background information on siRNA as well as examples of the use of siRNA as applied to drug transporters.     

Molecular design and delivery of siRNA

Double stranded short interfering RNAs (siRNAs) mediate gene silencing in a sequence specific manner. By virtue of their specific gene silencing activity and owing to the recent discoveries on their plasmid and virus driven expression, siRNAs are being widely adopted in research and therapeutics. Efforts were made to optimize the siRNA expression system for the application in therapy. One major obstacle in developing RNA interference (RNAi) therapy is the delivery of siRNAs to the target cells. Combination of novel molecular targeting technologies, such as recombinant protein technology and ribosome display technology, will enable to deliver gene silencing agents to target cells specifically and efficiently.