Triazole-linked dumbbell oligodeoxynucleotides with NF-kappaB binding ability as potential decoy molecules.

Triazole-cross-linked oligodeoxynucleotides were synthesized with use of the Cu(I) catalyzed alkyne-azide cycloaddition (CuAAC) with oligodeoxynucleotides possessing N-3-(azidoethyl)thymidine and N-3-(propargyl)thymidine at the 3'- and 5'-termini. The newly synthesized oligodeoxynucleotides were thermally stable and their global structures retained those of non-cross-linked oligodeoxynucleotides. The newly synthesized dumbbell oligodeoxynucleotides showed excellent stability against snake venom phosphodiesterase (3'-exonuclease) and high thermal stability, which are necessary for decoy molecules to achieve biological responses leading to alteration of gene expression. Moreover, dumbbell oligodeoxynucleotides have the ability to bind to NF-kappaB p50 homodimer within a similar range to that of a control double-stranded decoy oligodeoxynucleotide. This strategy allows us to prepare triazole-linked dumbbell oligodeoxynucleotides with a range of loop lengths, and we found that the greater the number of the thymidine residues constituting the loop region, the higher the binding affinity of the dumbbell oligodeoxynucleotides to the nuclear factor kappaB. This means that a protein binding ability of the dumbbell oligodeoxynucleotides could be modulated by altering the loop size. This study clearly shows that cross-linking by the triazole structure does not prevent the dumbbell oligodeoxynucleotides from binding to the nuclear factor kappaB transcription factor. Therefore, the results obtained conclusively demonstrate that the triazole cross-linked dumbbell oligodeoxynucleotides could be proposed as powerful decoy molecules.