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Karalė K, Bollmark M, Stulz R, Honcharenko D, Tedebark U, Strömberg R. A Study on Synthesis and Upscaling of 2'- O-AECM-5-methyl Pyrimidine Phosphoramidites for Oligonucleotide Synthesis. Molecules 2021; 26:6927. [PMID: 34834019 PMCID: PMC8619030 DOI: 10.3390/molecules26226927] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 11/11/2021] [Accepted: 11/14/2021] [Indexed: 11/16/2022] Open
Abstract
2'-O-(N-(Aminoethyl)carbamoyl)methyl-modified 5-methyluridine (AECM-MeU) and 5-methylcytidine (AECM-MeC) phosphoramidites are reported for the first time and prepared in multigram quantities. The syntheses of AECM-MeU and AECM-MeC nucleosides are designed for larger scales (approx. 20 g up until phosphoramidite preparation steps) using low-cost reagents and minimizing chromatographic purifications. Several steps were screened for best conditions, focusing on the most crucial steps such as N3 and/or 2'-OH alkylations, which were improved for larger scale synthesis using phase transfer catalysis (PTC). Moreover, the need of chromatographic purifications was substantially reduced by employing one-pot synthesis and improved work-up strategies.
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Affiliation(s)
- Kristina Karalė
- Department of Biosciences and Nutrition, Karolinska Institutet, Neo, 141 57 Huddinge, Sweden; (K.K.); (R.S.); (D.H.)
- RISE, Department Chemical Process and Pharmaceutical Development, Forskargatan 18, 151 36 Södertälje, Sweden; (M.B.); (U.T.)
| | - Martin Bollmark
- RISE, Department Chemical Process and Pharmaceutical Development, Forskargatan 18, 151 36 Södertälje, Sweden; (M.B.); (U.T.)
| | - Rouven Stulz
- Department of Biosciences and Nutrition, Karolinska Institutet, Neo, 141 57 Huddinge, Sweden; (K.K.); (R.S.); (D.H.)
- Oligonucleotide Discovery, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, 431 50 Gothenburg, Sweden
| | - Dmytro Honcharenko
- Department of Biosciences and Nutrition, Karolinska Institutet, Neo, 141 57 Huddinge, Sweden; (K.K.); (R.S.); (D.H.)
| | - Ulf Tedebark
- RISE, Department Chemical Process and Pharmaceutical Development, Forskargatan 18, 151 36 Södertälje, Sweden; (M.B.); (U.T.)
| | - Roger Strömberg
- Department of Biosciences and Nutrition, Karolinska Institutet, Neo, 141 57 Huddinge, Sweden; (K.K.); (R.S.); (D.H.)
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Danielsen MB, Wengel J. Cationic oligonucleotide derivatives and conjugates: A favorable approach for enhanced DNA and RNA targeting oligonucleotides. Beilstein J Org Chem 2021; 17:1828-1848. [PMID: 34386102 PMCID: PMC8329367 DOI: 10.3762/bjoc.17.125] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 07/14/2021] [Indexed: 12/20/2022] Open
Abstract
Antisense oligonucleotides (ASOs) have the ability of binding to endogenous nucleic acid targets, thereby inhibiting the gene expression. Although ASOs have great potential in the treatment of many diseases, the search for favorable toxicity profiles and distribution has been challenging and consequently impeded the widespread use of ASOs as conventional medicine. One strategy that has been employed to optimize the delivery profile of ASOs, is the functionalization of ASOs with cationic amine groups, either by direct conjugation onto the sugar, nucleobase or internucleotide linkage. The introduction of these positively charged groups has improved properties like nuclease resistance, increased binding to the nucleic acid target and improved cell uptake for oligonucleotides (ONs) and ASOs. The modifications highlighted in this review are some of the most prevalent cationic amine groups which have been attached as single modifications onto ONs/ASOs. The review has been separated into three sections, nucleobase, sugar and backbone modifications, highlighting what impact the cationic amine groups have on the ONs/ASOs physiochemical and biological properties. Finally, a concluding section has been added, summarizing the important knowledge from the three chapters, and examining the future design for ASOs.
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Affiliation(s)
- Mathias B Danielsen
- Biomolecular Nanoscale Engineering Center, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
| | - Jesper Wengel
- Biomolecular Nanoscale Engineering Center, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
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Koizumi K, Maeda Y, Kano T, Yoshida H, Sakamoto T, Yamagishi K, Ueno Y. Synthesis of 4′-C-aminoalkyl-2′-O-methyl modified RNA and their biological properties. Bioorg Med Chem 2018; 26:3521-3534. [DOI: 10.1016/j.bmc.2018.05.025] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Revised: 05/17/2018] [Accepted: 05/17/2018] [Indexed: 12/16/2022]
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Menzi M, Wild B, Pradère U, Malinowska AL, Brunschweiger A, Lightfoot HL, Hall J. Towards Improved Oligonucleotide Therapeutics Through Faster Target Binding Kinetics. Chemistry 2017; 23:14221-14230. [PMID: 28746731 DOI: 10.1002/chem.201701670] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Indexed: 01/19/2023]
Abstract
When used as inhibitors of gene expression in vivo, oligonucleotides require modification of their structures to boost their binding affinity for complementary target RNAs. To date, hundreds of modifications have been designed and tested but few have proven to be useful. Among those investigated are mono- and polyamino-groups. These are positively charged at physiological pH and have been appended to oligonucleotides in an effort to reduce electrostatic repulsion during hybridization to RNAs, but have generally shown relatively minor benefits to binding. We conjugated spermine to uracils in oligonucleotides via a triazole linker so that the polyamine fits in the major groove of a subsequently formed RNA-duplex. The modifications produced large increases in target-binding affinity of the oligonucleotides. Using surface plasmon resonance-based assays, we showed that the increases derived mainly from faster annealing (kon ). We propose that the spermine fragments play a similar role to that of natural polyamines during oligonucleotide-target interactions in cells, and may be advantageous for oligonucleotides that operate catalytic mechanisms.
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Affiliation(s)
- Mirjam Menzi
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093, Zürich, Switzerland
| | - Bettina Wild
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093, Zürich, Switzerland
| | - Ugo Pradère
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093, Zürich, Switzerland
| | - Anna L Malinowska
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093, Zürich, Switzerland
| | - Andreas Brunschweiger
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Strasse 6, 44227, Dortmund, Germany
| | - Helen L Lightfoot
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093, Zürich, Switzerland
| | - Jonathan Hall
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093, Zürich, Switzerland
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Milton S, Honcharenko D, Rocha CSJ, Moreno PMD, Smith CIE, Strömberg R. Nuclease resistant oligonucleotides with cell penetrating properties. Chem Commun (Camb) 2015; 51:4044-7. [PMID: 25664358 DOI: 10.1039/c4cc08837a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
2'-O-AECM modified oligonucleotides provide an unusual combination of remarkable properties. This includes the combination of high resistance towards enzymatic degradation and the spontaneous cellular uptake of AECM oligonucleotides.
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Affiliation(s)
- Stefan Milton
- Karolinska Institutet, Department of Biosciences and Nutrition, Novum, Hälsovägen 7, SE-14183, Huddinge, Sweden.
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Polyamine-oligonucleotide conjugates: a promising direction for nucleic acid tools and therapeutics. Future Med Chem 2015; 7:1733-49. [PMID: 26424049 DOI: 10.4155/fmc.15.90] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Chemical modification and/or the conjugation of small functional molecules to oligonucleotides have significantly improved their biological and biophysical properties, addressing issues such as poor cell penetration, stability to nucleases and low affinity for their targets. Here, the authors review the literature reporting on the biophysical, biochemical and biological properties of one particular class of modification - polyamine-oligonucleotide conjugates. Naturally derived and synthetic polyamines have been grafted onto a variety of oligonucleotide formats, including antisense oligonucleotides and siRNAs. In many cases this has had beneficial effects on their properties such as target hybridization, nuclease resistance, cellular uptake and activity. Polyamine-oligonucleotide conjugation, therefore, represents a promising direction for the further development of oligonucleotide-based therapeutics and tools.
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Biscans A, Rouanet S, Bertrand JR, Vasseur JJ, Dupouy C, Debart F. Synthesis, binding, nuclease resistance and cellular uptake properties of 2'-O-acetalester-modified oligonucleotides containing cationic groups. Bioorg Med Chem 2015; 23:5360-8. [PMID: 26260340 DOI: 10.1016/j.bmc.2015.07.054] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 07/24/2015] [Accepted: 07/25/2015] [Indexed: 11/18/2022]
Abstract
We report on the synthesis and properties of oligonucleotides (ONs) with 2'-O-acetalester modifications containing cationic side chains in a prodrug-like approach. In the aim to improve cell penetration and nuclease resistance, various different amino- or guanidino-acetalester were grafted to 2'-OH of uridine and the corresponding phosphoramidites were incorporated into ONs. Introduction of 2'-O-(2-aminomethyl-2-ethyl)butyryloxymethyl (AMEBuOM) modification into 2'-OMe ONs leads to high resistance towards enzymatic degradation and to destabilization of duplexes with complementary RNA strand. Spontaneous uptake experiments of a twelve-mer containing ten 2'-O-AMEBuOM-U units into A673 cells showed moderate internalization of ON within the cells whereas substantial internalization of the corresponding lipophilic 2'-O-pivaloyloxymethyl ON was observed for the first time.
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Affiliation(s)
- Annabelle Biscans
- Department of Nucleic Acids, IBMM UMR 5247, CNRS-Université Montpellier-ENSCM, UM Campus Triolet, Place E. Bataillon, 34095 Montpellier Cedex 05, France
| | - Sonia Rouanet
- Department of Nucleic Acids, IBMM UMR 5247, CNRS-Université Montpellier-ENSCM, UM Campus Triolet, Place E. Bataillon, 34095 Montpellier Cedex 05, France
| | - Jean-Rémi Bertrand
- UMR 8203 CNRS, Université Paris-Saclay, Institut Gustave Roussy, 114 rue Edouard Vaillant, 94805 Villejuif Cedex, France
| | - Jean-Jacques Vasseur
- Department of Nucleic Acids, IBMM UMR 5247, CNRS-Université Montpellier-ENSCM, UM Campus Triolet, Place E. Bataillon, 34095 Montpellier Cedex 05, France
| | - Christelle Dupouy
- Department of Nucleic Acids, IBMM UMR 5247, CNRS-Université Montpellier-ENSCM, UM Campus Triolet, Place E. Bataillon, 34095 Montpellier Cedex 05, France.
| | - Françoise Debart
- Department of Nucleic Acids, IBMM UMR 5247, CNRS-Université Montpellier-ENSCM, UM Campus Triolet, Place E. Bataillon, 34095 Montpellier Cedex 05, France.
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Abstract
Insufficient pharmacokinetic properties and poor cellular uptake are the main hurdles for successful therapeutic development of oligonucleotide agents. The covalent attachment of various ligands designed to influence the biodistribution and cellular uptake or for targeting specific tissues is an attractive possibility to advance therapeutic applications and to expand development options. In contrast to advanced formulations, which often consist of multiple reagents and are sensitive to a variety of preparation conditions, oligonucleotide conjugates are defined molecules, enabling structure-based analytics and quality control techniques. This review gives an overview of current developments of oligonucleotide conjugates for therapeutic applications. Attached ligands comprise peptides, proteins, carbohydrates, aptamers and small molecules, including cholesterol, tocopherol and folic acid. Important linkage types and conjugation methods are summarized. The distinct ligands directly influence biochemical parameters, uptake mechanisms and pharmacokinetic properties.
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Milton S, Ander C, Honcharenko D, Honcharenko M, Yeheskiely E, Strömberg R. Synthesis and Stability of a 2′-O-[N-(Aminoethyl)carbamoyl]methyladenosine-Containing Dinucleotide. European J Org Chem 2013. [DOI: 10.1002/ejoc.201300699] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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10
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Hacker SM, Hardt N, Buntru A, Pagliarini D, Möckel M, Mayer TU, Scheffner M, Hauck CR, Marx A. Fingerprinting differential active site constraints of ATPases. Chem Sci 2013. [DOI: 10.1039/c3sc21916j] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Milton S, Ander C, Yeheskiely E, Strömberg R. Stability of a 2′-O-(Carbamoylmethyl)adenosine-Containing Dinucleotide. European J Org Chem 2011. [DOI: 10.1002/ejoc.201101264] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Kolganova NA, Florentiev VL, Chudinov AV, Zasedatelev AS, Timofeev EN. Simple and stereoselective preparation of an 4-(aminomethyl)-1,2,3-triazolyl nucleoside phosphoramidite. Chem Biodivers 2011; 8:568-76. [PMID: 21480503 DOI: 10.1002/cbdv.201000047] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A simple and stereoselective synthesis of a protected 4-(aminomethyl)-1-(2-deoxy-β-D-ribofuranosyl)-1,2,3-triazole cyanoethyl phosphoramidite was developed for the modification of synthetic oligonucleotides. The configuration of the 1,2,3-triazolyl moiety with respect to the deoxyribose was unambiguously determined in ROESY experiments. The aminomethyl group of the triazolyl nucleotide was fully functional in labelling reactions. Furthermore, the hybridization behavior of 5' triazole-terminated oligonucleotide was similar to that of 5' aminohexyl-terminated oligomer with the same sequence. Internal modifications of the oligonucleotide strands resulted in significant decrease of duplex stability.
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Affiliation(s)
- Natalia A Kolganova
- Engelhardt Institute of Molecular Biology, 32 Vavilov St., Moscow 119991, Russia
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Winkler J, Giessrigl B, Novak C, Urban E, Noe CR. 2′-O-Lysylaminohexyladenosine modified oligonucleotides. MONATSHEFTE FUR CHEMIE 2010. [DOI: 10.1007/s00706-010-0318-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Lönnberg H. Solid-phase synthesis of oligonucleotide conjugates useful for delivery and targeting of potential nucleic acid therapeutics. Bioconjug Chem 2009; 20:1065-94. [PMID: 19175328 DOI: 10.1021/bc800406a] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Olignucleotide-based drugs show promise as a novel form of chemotherapy. Among the hurdles that have to be overcome on the way of applicable nucleic acid therapeutics, inefficient cellular uptake and subsequent release from endosomes to cytoplasm appear to be the most severe ones. Covalent conjugation of oligonucleotides to molecules that expectedly facilitate the internalization, targets the conjugate to a specific cell-type or improves the parmacokinetics offers a possible way to combat against these shortcomings. Since workable chemistry is a prerequisite for biological studies, development of efficient and reproducible methods for preparation of various types of oligonucleotide conjugates has become a subject of considerable importance. The present review summarizes the advances made in the solid-supported synthesis of oligonucleotide conjugates aimed at facilitating the delivery and targeting of nucleic acid drugs.
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Affiliation(s)
- Harri Lönnberg
- Department of Chemistry, University of Turku, FIN-20014 Turku, Finland.
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Winkler J, Martin-Killias P, Plückthun A, Zangemeister-Wittke U. EpCAM-targeted delivery of nanocomplexed siRNA to tumor cells with designed ankyrin repeat proteins. Mol Cancer Ther 2009; 8:2674-83. [PMID: 19723880 DOI: 10.1158/1535-7163.mct-09-0402] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Specific delivery to tumors and efficient cellular uptake of nucleic acids remain major challenges for gene-targeted cancer therapies. Here we report the use of a designed ankyrin repeat protein (DARPin) specific for the epithelial cell adhesion molecule (EpCAM) as a carrier for small interfering RNA (siRNA) complementary to the bcl-2 mRNA. For charge complexation of the siRNA, the DARPin was fused to a truncated human protamine-1 sequence. To increase the cell binding affinity and the amount of siRNA delivered into cells, DARPin dimers were generated and used as fusion proteins with protamine. All proteins expressed well in Escherichia coli in soluble form, yet, to remove tightly bound bacterial nucleic acids, they were purified under denaturing conditions by immobilized metal ion affinity chromatography, followed by refolding. The fusion proteins were capable of complexing four to five siRNA molecules per protamine, and fully retained the binding specificity for EpCAM as shown on MCF-7 breast carcinoma cells. In contrast to unspecific LipofectAMINE transfection, down-regulation of antiapoptotic bcl-2 using fusion protein complexed siRNA was strictly dependent on EpCAM binding and internalization. Inhibition of bcl-2 expression facilitated tumor cell apoptosis as shown by increased sensitivity to the anticancer agent doxorubicin.
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Affiliation(s)
- Johannes Winkler
- Institute of Pharmacology, University of Bern, 3010 Bern, Switzerland
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Winkler J, Gilbert M, Kocourková A, Stessl M, Noe CR. 2'-O-Lysylaminohexyl oligonucleotides: modifications for antisense and siRNA. ChemMedChem 2008; 3:102-10. [PMID: 17979170 DOI: 10.1002/cmdc.200700169] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A novel type of oligonucleotide has been developed, characterized by the attachment of a lysyl moiety to a 2'-O-aminohexyl linker. A protected lysine building block was tethered to 2'-O-aminohexyluridine, and the product was converted into the corresponding phosphoramidite. Up to six modified nucleosides were incorporated in dodecamer DNA and RNA oligonucleotides using standard phosphoramidite chemistry. Each of the building blocks contributes one positive charge to the oligonucleotide instead of the negative charge of a wild-type nucleotide. Thermal denaturation profiles indicated a stabilizing effect of 2'-O-lysylaminohexyl chains that was more pronounced in RNA duplexes. Incubation of the oligonucleotides with 5'-exonuclease revealed an exceptionally high stability against enzymatic degradation. Incorporation of up to three modifications into functional antisense and siRNA oligonucleotides targeted at ICAM-1 showed that the gene-silencing activity was higher with an increasing number of lysylaminohexyl nucleotides. Compared with wild-type antisense or siRNA, compounds with three modifications led to equal or higher ICAM-1 downregulation.
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Affiliation(s)
- Johannes Winkler
- Department of Medicinal Chemistry, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
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Oligonucleotide-polyamine conjugates: influence of length and position of 2'-attached polyamines on duplex stability and antisense effect. Eur J Med Chem 2008; 44:670-7. [PMID: 18617292 DOI: 10.1016/j.ejmech.2008.05.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2007] [Revised: 04/15/2008] [Accepted: 05/19/2008] [Indexed: 11/22/2022]
Abstract
Tethering cationic ligands to oligonucleotides results in zwitterionic molecules with often improved target affinity and better cell membrane permeation. Due to the ideal distance between cationic groups, polyamines are perfect counter ions for oligonucleotides. Using an easy and versatile procedure for attaching ligands to the 2'-position, polyamines were conjugated to distinct terminal and internal positions of oligonucleotides. With polyamines attached to terminal nucleosides, the affinity to complementary DNA or RNA strands increased with growing number of cationic amines. Tethering polyamines to an internal nucleoside of wild type DNA oligonucleotides resulted in a considerable decrease in duplex stability, but in phosphorothioates, no significant decrease was detected. Conjugates exhibited progressively higher target downregulation ability with increasing polyamine chain length in a human melanoma cell culture assay.
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Winkler J, Noe CR. Oligonucleotide charge reversal: 2'-O-lysylaminohexyl modified oligonucleotides. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2008; 26:939-42. [PMID: 18058513 DOI: 10.1080/15257770701507978] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
A novel cationic building nucleoside building block designed for antisense and siRNA oligonucleotides is presented. Protected L-lysine was coupled to 2'-O-aminohexyluridine and the resulting nucleoside was phosphitylated for automated oligonucleotide synthesis. An increasing number of these 2'-O-lysylaminohexyl nucleosides lowered the melting temperature of desoxy-thymidine homododecamers, but the decrease was lower than that for DNA/RNA hybrids. Incubation with an exonuclease showed the exceptionally high resistance against enzymatic degradation. CD spectrometry revealed a gradual transition towards an A-type oligonucleotide structure. Based on these data, the cationic building block is particularly suited for gapmer antisense as well as siRNA oligonucleotides.
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Affiliation(s)
- Johannes Winkler
- Department of Medicinal Chemistry, University of Vienna, Vienna, Austria.
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