來自Alnylam公司,，美國麻省理工癌癥研究中心（Center for Cancer Research），德州大學(xué)西南醫(yī)學(xué)中心（University of Texas Southwestern Medical Center）,，瑞士聯(lián)邦技術(shù)院（Swiss Federal Institute of Technology Zurich,， ETHZ）的研究人員證實(shí)了一種深
具潛力的遺傳治療方法的安全性,，這種治療方法有廣泛的應(yīng)用前景，可以治療包括癌癥在內(nèi)的許多疾病,。
這一研究成果公布在9月27日的Nature雜志上,，文章描述了一種治療的新方法，去年一篇同樣發(fā)表于Nature的文章報(bào)道了另外一種常用的的方法,，但是這種方法會引起小鼠致死,。
在Anderson等人發(fā)表這篇新成果中，研究人員證實(shí)siRNA并不會如同shRNA一樣,，加大劑量引起毒性,，這是因?yàn)檫@一過程并不會影響miRNA途徑，而且研究人員在小鼠
和倉鼠肝臟細(xì)胞中實(shí)現(xiàn)了靶標(biāo)基因80％的沉默效果,。
Alnylam科研主任David Bumcrot表示,，“利用化學(xué)合成的siRNA，你可以傳遞有效siNRA,，獲得治療性的基因沉默效果,，而這并不影響細(xì)胞內(nèi)源性miRNA”。
研究人員采用的RNA傳遞系統(tǒng)是來自麻省理工的一種RNA傳遞新方法,，這種方法的具體細(xì)節(jié)將于另外一篇文章中公布,。
在許多RNAi研究中，研究人員都是利用逆轉(zhuǎn)錄病毒傳遞編碼shRNA的基因,，進(jìn)一步加工成siRNA,，一旦這一基因結(jié)合到細(xì)胞DNA上，shRNA就會合成,，從細(xì)胞核傳遞到細(xì)胞質(zhì),。早期的研究發(fā)現(xiàn)大量shRNA會阻斷細(xì)胞輸出miRNA，因?yàn)楹笳吲c前者使用的是同一輸出途徑,。沒有正常的功能性miRNAs,，小鼠就會死亡。雖然低劑量的shRNA不會引起毒性,，但是這種劑量很難進(jìn)行調(diào)控——一旦shNRA基因結(jié)合到宿主細(xì)胞DNA上,，它的表達(dá)期限就很長。
這篇文章則是將siRNA直接傳遞到細(xì)胞質(zhì),，因此不會與miRNA形成競爭,。Bumcrot認(rèn)為，“我們希望證明如果是在這一途徑的下游進(jìn)行,，那么就不會干擾miRNA途徑”,，“利用合成的siRNA，我們傳遞了一個(gè)合適劑量的siRNA,，我們知道這種效果會持續(xù)多久,，如果產(chǎn)生毒性,，可以馬上停止，因此這樣比較容易調(diào)控,，安全一些,。”
原始出處:
Nature advance online publication 26 September 2007 | doi:10.1038/nature06179; Received 17 November 2006; Accepted 16 August 2007; Published online 26 September 2007
Effective RNAi-mediated gene silencing without interruption of the endogenous microRNA pathway
Matthias John1, Rainer Constien1, Akin Akinc2, Michael Goldberg3, Young-Ah Moon5, Martina Spranger6, Philipp Hadwiger1, Jürgen Soutschek1, Hans-Peter Vornlocher1, Muthiah Manoharan2, Markus Stoffel6, Robert Langer3,4, Daniel G. Anderson4, Jay D. Horton5, Victor Koteliansky2 & David Bumcrot2
Alnylam Europe AG, Fritz-Hornschuch-Str. 9, 95326 Kulmbach, Germany
Alnylam Pharmaceuticals Inc., 300 Third Street, Cambridge, Massachusetts 02142, USA
Department of Chemistry, and,
Center for Cancer Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetss 02139, USA
Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9046, USA
Institute of Molecular Systems Biology, Swiss Federal Institute of Technology ETH Zürich, HPT E73, CH-8093 Zürich, Switzerland
Correspondence to: David Bumcrot2 Correspondence and requests for materials should be addressed to D.B. (Email: [email protected]).
Systemic administration of synthetic small interfering RNAs (siRNAs) effectively silences hepatocyte gene expression in rodents and primates1, 2, 3. Whether or not in vivo gene silencing by synthetic siRNA can disrupt the endogenous microRNA (miRNA) pathway remains to be addressed. Here we show that effective target-gene silencing in the mouse and hamster liver can be achieved by systemic administration of synthetic siRNA without any demonstrable effect on miRNA levels or activity. Indeed, siRNA targeting two hepatocyte-specific genes (apolipoprotein B and factor VII) that achieved efficient (80%) silencing of messenger RNA transcripts and a third irrelevant siRNA control were administered to mice without significant changes in the levels of three hepatocyte-expressed miRNAs (miR-122, miR-16 and let-7a) or an effect on miRNA activity. Moreover, multiple administrations of an siRNA targeting the hepatocyte-expressed gene Scap in hamsters achieved long-term mRNA silencing without significant changes in miR-122 levels. This study advances the use of siRNAs as safe and effective tools to silence gene transcripts in animal studies, and supports the continued advancement of RNA interference therapeutics using synthetic siRNA.
