Boron-containing aptamers to ATP

Abstract

Boron neutron capture therapy (BNCT), an experimental treatment for certain cancers, destroys only cells near the boron; however, there is a need to develop highly specific delivery agents. As nucleic acid aptamers recognize specific molecular targets, we investigated the influence of boronated nucleotide analogs on RNA function and on the systematic evolution of ligands by exponential enrichment (SELEX) process. Substitution of guanosine 5'-(alpha-P-borano) triphosphate (bG) for GTP or uridine 5'-(alpha-P-borano) triphosphate (bU) for UTP in several known aptamers diminished or eliminated target recognition by those RNAs. Specifically, ATP-binding aptamers containing the zeta-fold, which appears in several selections for adenosine aptamers, became inactive upon bG substitution but were only moderately affected by bU substitution. Selections were carried out using the bG or bU analogs with C8-linked ATP agarose as the binding target. The selections with bU and normal NTP yielded some zeta-fold aptamers, while the bG selection yielded none of this type. Non-zeta aptamers from bU and bG populations tolerated the borano substitution and many required it. The borano nucleotide requirement is specific; bU could not be used in bG-dependent aptamers nor vice versa. The borano group plays an essential role, as yet undefined, in target recognition or RNA structure. We conclude that the bG and bU nucleotides are fully compatible with SELEX, and that these analogs could be used to make boronated aptamers as therapeutics for BNCT.

New NTP analogs: the synthesis of 4′-thioUTP and 4′-thioCTP and their utility for SELEX

“…However, recognition of the nucleoside triphosphates by the T7 RNA polymerase is quite restrictive, and few of the modified triphosphates are considered good candidates for SELEX. Thus far, 2′-modified-2′-deoxynucleoside 5′-triphosphates (16), nucleoside 5′-(α-P-borano)triphosphates (17) and nucleoside 5′-(α-thio)triphosphates (18) are used as modified triphosphates for SELEX. Among them, 2′-amino- and 2′-fluoro-2′-deoxypyrimidine nucleoside triphosphates (2′-NH 2 dUTP and 2′-NH 2 dCTP; 2′-FdUTP and 2′-FdCTP) are frequently used compounds, and a number of nuclease-resistant RNAs, especially RNA aptamers, were isolated by SELEX using these two sets of 5′-triphosphates.…”

Nucleic Acid Aptamers as Molecular Tags for Omics Analyses Involving Sequencing

“…Modified nucleoside triphosphates involving phosphorothioate and boranophosphate [Lato et al, 2002] are normally used as substrates. A phosphate-modified RNA aptamer specific for bFGF was obtained by screening the library of modified RNA exclusively involving phosphorothioate inter-nucleoside linkages, which could greatly enhance nuclease resistance [Jhaveri et al, 1998].…”

Nukleinsäure‐basierte molekulare Werkzeuge

“…B. Doxorubicin), [289] Toxine [290] und wirkstoffbeladene Nanopartikel, [291] einschleusen. Ihre Fähigkeit, sich spezifisch an verschiedene Gewebetypen anzulagern, vereint mit ihrer chemischen Funktionalisierbarkeit, erhöht das Potenzial von Aptameren für siRNA-Therapien verschiedener Krankheiten, [292] des Weiteren für die photodynamische Therapie, [293] Bor-Neutroneneinfangtherapie (boron neutroncapture therapy) [294] oder eine Enzymersatztherapie [295] durch die Anreicherung des relevanten molekularen Agenten an den Zielpunkten.…”