Aptamer-Mediated Delivery of Splice-Switching Oligonucleotides to the Nuclei of Cancer Cells

Department of Surgery, Duke University Medical Center, Durham, North Carolina 27710, USA.
Nucleic acid therapeutics 06/2012; 22(3):187-95. DOI: 10.1089/nat.2012.0347
Source: PubMed


To reduce the adverse effects of cancer therapies and increase their efficacy, new delivery agents that specifically target cancer cells are needed. We and others have shown that aptamers can selectively deliver therapeutic oligonucleotides to the endosome and cytoplasm of cancer cells that express a particular cell surface receptor. Identifying a single aptamer that can internalize into many different cancer cell-types would increase the utility of aptamer-mediated delivery of therapeutic agents. We investigated the ability of the nucleolin aptamer (AS1411) to internalize into multiple cancer cell types and observed that it internalizes into a wide variety of cancer cells and migrates to the nucleus. To determine if the aptamer could be utilized to deliver therapeutic oligonucleotides to modulate events in the nucleus, we evaluated the ability of the aptamer to deliver splice-switching oligonucleotides. We observed that aptamer-splice-switching oligonucleotide chimeras can alter splicing in the nuclei of treated cells and are effective at lower doses than the splice switching oligonucleotides alone. Our results suggest that aptamers can be utilized to deliver oligonucleotides to the nucleus of a wide variety of cancer cells to modulate nuclear events such as RNA splicing.

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    • "In 2012, Sullenger and coworkers71 used G-quadruplex-forming AS1411 DNA aptamers to deliver SSOs into the nuclei of cancer cells (Figure 1d). As a form of antisense technology, single-stranded RNA oligonucleotides are designed to bind to a splice site or splicing enhancers, thereby blocking access to the endogenous splicing machinery and resulting in an alternate version of mature mRNA for translation. "
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    ABSTRACT: One hundred years ago, Dr. Paul Ehrlich popularized the "magic bullet" concept for cancer therapy in which an ideal therapeutic agent would only kill the specific tumor cells it targeted. Since then, "targeted therapy" that specifically targets the molecular defects responsible for a patient's condition has become a long-standing goal for treating human disease. However, safe and efficient drug delivery during the treatment of cancer and infectious disease remains a major challenge for clinical translation and the development of new therapies. The advent of SELEX technology has inspired many groundbreaking studies that successfully adapted cell-specific aptamers for targeted delivery of active drug substances in both in vitro and in vivo models. By covalently linking or physically functionalizing the cell-specific aptamers with therapeutic agents, such as siRNA, microRNA, chemotherapeutics or toxins, or delivery vehicles, such as organic or inorganic nanocarriers, the targeted cells and tissues can be specifically recognized and the therapeutic compounds internalized, thereby improving the local concentration of the drug and its therapeutic efficacy. Currently, many cell-type-specific aptamers have been developed that can target distinct diseases or tissues in a cell-type-specific manner. In this review, we discuss recent advances in the use of cell-specific aptamers for targeted disease therapy, as well as conjugation strategies and challenges.
    Molecular Therapy - Nucleic Acids 06/2014; 3(6):e169. DOI:10.1038/mtna.2014.21 · 4.51 Impact Factor
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    • "We have recently shown that β-arrestin 2 is critical for the onset and maintenance of both the chronic and blast crisis stages of CML (CML and bcCML) in mouse models of theses diseases [18]. Previous work has shown that the nucleolin aptamer can deliver oligonucleotides specifically into cancer cells if nucleolin is present on the membrane of the targeted cells [25]. Accordingly, we analyzed K562 cells, a human Gleevec-resistant bcCML cell-line, and found that membrane-associated nucleolin was approximately 30x more abundant than membrane-associated nucleolin in lymphoblastoid cells, which are non-cancerous human B cells (Figure 3A). "
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    ABSTRACT: β-arrestins, ubiquitous cellular scaffolding proteins that act as signaling mediators of numerous critical cellular pathways, are attractive therapeutic targets because they promote tumorigenesis in several tumor models. However, targeting scaffolding proteins with traditional small molecule drugs has been challenging. Inhibition of β-arrestin 2 with a novel aptamer impedes multiple oncogenic signaling pathways simultaneously. Additionally, delivery of the β-arrestin 2-targeting aptamer into leukemia cells through coupling to a recently described cancer cell-specific delivery aptamer, inhibits multiple β-arrestin-mediated signaling pathways known to be required for chronic myelogenous leukemia (CML) disease progression, and impairs tumorigenic growth in CML patient samples. The ability to target scaffolding proteins such as β-arrestin 2 with RNA aptamers may prove beneficial as a therapeutic strategy. An RNA aptamer inhibits β-arrestin 2 activity.Inhibiting β-arrestin 2 impedes multiple tumorigenic pathways simultaneously.The therapeutic aptamer is delivered to cancer cells using a cell-specific DNA aptamer.Targeting β-arrestin 2 inhibits tumor progression in CML models and patient samples.
    PLoS ONE 04/2014; 9(4):e93441. DOI:10.1371/journal.pone.0093441 · 3.23 Impact Factor
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    • "Tumor-specific uptake of targeted ligands, mediated by NCL, has been exploited by many different groups so far [166]. Using several in vivo and in vitro methods, it was demonstrated that the AS1411 aptamer, as well as F3-conjugated nanoparticles, target cancer cells overexpressing NCL on their cell surface and can be potentially used as non-invasive imaging tools for the diagnosis of cancer or to facilitate the release of conjugated chemotherapeutic drugs [134] [160] [167] [168] [169] [170] [171] [172] [173] [174] [175] [176] [177] [178] [179] [180] [181] [182] [183] [184] [185] [186] [187] [188] [189]. Given that AS1411 is internalized at much lower concentrations than those necessary for anti-proliferative effects [163], it could be a particularly promising agent for these and other targeted delivery approaches. "
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    ABSTRACT: A large number of mostly recent reports show enhanced expression of the multi-functional protein nucleolin (NCL) on the surface of activated lymphocytes, angiogenic endothelial and many different types of cancer cells. Translocation of NCL at the external side of the plasma membrane occurs via a secretory pathway independent of the endoplasmic reticulum-Golgi complex, requires intracellular intact actin cytoskeleton, and seems to be mediated by a variety of factors. Cell surface NCL serves as a binding partner of several molecules implicated in cell differentiation, adhesion, leukocyte trafficking, inflammation, angiogenesis and tumor development, mediating their biological activities and in some cases, leading to their internalization. Accumulating evidence validates cell surface NCL as a strategic target for treatment of cancer, while its property of tumor-specific uptake of targeted ligands seems to be useful for the development of non-invasive imaging tools for the diagnosis of cancer and for the targeted release of chemotherapeutic drugs. The observation that cell surface NCL exists in complexes with several other proteins implicated in tumorigenesis and angiogenesis suggests that targeting cell surface NCL might trigger multi-inhibitory effects, depending on the cell type. This review summarizes papers and patents related to the redistribution and the biological functions of cell surface NCL, with emphasis on the potential importance and advantages of developing efficient anti-cell surface NCL strategies.
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