Intracellular delivery of siRNA by cell-penetrating peptides modified with cationic oligopeptides.
ABSTRACT To achieve the effective intracellular delivery of siRNA and silence specific genes, various types of conjugates between cell-penetrating peptides (CPPs; Transportan, Penetratin, Tat) and cationic peptides were developed. Uptake, intracellular localization, cytotoxicity, and biological activity of siRNA were significantly dependent on the kind of CPP used and the length of the cationic peptides in the conjugate. Transportan-based conjugates yielded both high internalization of siRNA and strong gene silencing activity, while Penetratin- and Tat-based conjugates did not. These different properties of CPPs emphasize the importance of careful peptide selection and design when attempting the application of CPP technology.
SourceAvailable from: David L Selwood[Show abstract] [Hide abstract]
ABSTRACT: In order to deliver siRNA for therapeutic use several hurdles must be addressed. Metabolic degradation must be blocked, the RNAi cellular machinery is located in the cytoplasm, while double stranded siRNA is large, highly charged and impermeable to cell membranes. To date the solutions to the delivery issues have mostly involved different forms of lipid particle encapsulation. Cell penetrating peptides (CPPs) and their mimics or analogues offer a different approach and this is an emerging field with the first in vivo examples now reported. Recent reports point to lipid receptors being involved in the cellular uptake of both types of transporter. This review examines the delivery of siRNA with a focus on CPPs and their small molecule and oligomeric mimics. The current status of siRNA delivery methods in clinical trials is examined. It now seems that the goal of delivering siRNA therapeutically is achievable but will they form part of a sustainable healthcare portfolio for the future. © 2012 John Wiley & Sons A/S.Chemical Biology & Drug Design 09/2012; 80(6). DOI:10.1111/cbdd.12052 · 2.51 Impact Factor
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ABSTRACT: Stem cell differentiation is modulated by several key molecules, including cytokines, hormones, and engineered peptides. Emerging evidence suggests that microRNA has potential applications in stem cell engineering, such as in osteoblastic differentiation. MicroRNAs (miRNAs) bind to the 3'-untranslated region (UTR) sequence of target mRNA, thereby attenuating protein synthesis. Our goal was to evaluate the delivery of miRNA, i.e., miRNA-29b, to stem cells to promote osteoblastic differentiation because this miRNA is known to target anti-osteogenic factors gene expression. Despite the important role of miRNAs, their application has been limited due to poor cell/tissue penetration. The authors attempted to overcome this limitation by using a cell-penetrating peptide (CPP) carrier. Herein, the arginine-rich CPP, called the lowmolecular weight protamine (LMWP), is the sequence from natural protamine. We worked out the difficult problem to transfect into hMSCs by the complex with LMWP, and then we investigated synthetic double-stranded miR-29b could be induced osteoblast differentiation.Biomaterials 03/2013; DOI:10.1016/j.biomaterials.2013.02.039 · 8.31 Impact Factor
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ABSTRACT: Small interfering RNAs (siRNAs) have displayed considerable promise for the treatment of cancer. However, their delivery to the desired cell population remains a challenging task. Here we have covalently conjugated a siRNA against survivin to gastrin-releasing peptides (GRPs) to direct siRNA molecules to cancer cells that express the GRP receptor. The cellular uptake of the peptide-siRNA conjugates was tested in breast MDA-MB 231 cancer cells, which express the GRP receptor. Fluorescein-tagged GRP-siRNA conjugates were taken up by cancer cells but not normal mammary epithelial cells or human blood monocytes. By 120 min of incubation, most of the cells have taken up the conjugates. Excess free peptide inhibited uptake, implying dependence of uptake on GRP receptor. Moreover, bitargeting of siRNA molecules by GR and luteinizing hormone-releasing peptides accelerated the uptake kinetics by MDA-MB 231 cells when compared to monotargeted siRNAs. Peptide-siRNA conjugates, but not free siRNAs, inhibited the expression of survivin, an endogenous gene involved in cancer cell survival. None of the peptide-siRNA conjugates induced the expression of inflammatory cytokines or interferon α in human blood leukocytes. Overall, the data demonstrate the feasibility of GRP receptor-mediated targeted delivery of siRNAs to cancer cells, an important step for RNA interference therapy in humans.Bioconjugate Chemistry 03/2012; 23(5). DOI:10.1021/bc300050j · 4.82 Impact Factor