Organic Synthesis and Antisense Effects of Oligonucleotide-Peptide Conjugates

In order to improve the biological and pharmacological properties of antisense oligonucleotides, we have been recently focused our efforts on synthesis of DNA-peptide conjugates and biological evaluation of them. Oligonucleotides can be covalently linked to peptides composed of any sequence of amino acids by Solid Phase Fragment Condensation (SPFC). The peptides incorporated into the conjugates include nuclear localizing signals (NLS), nuclear export signals (NES), membrane fusion domain of some viral proteins and some designed cationic α-helical or β-sheet peptides with amphipathic character. Some polyamines and sugars were also conjugated with oligonucleotides by SPFC in good yields. Evaluation of biological properties of DNA-peptide conjugates indicated that (a) the conjugates could bind to target RNA and dsDNA with increased affinity, (b) the conjugates were more resistant to cellular nuclease degradation, (c) the conjugates- RNA hybrids could activate RNase H as effective as native oligonucleotides, (d) the conjugates with fusion peptides showed largely enhanced cellular uptake, (e) the conjugates with NLS could be predominantly delivered into cell nucleus, (f) the conjugates with NES could be localized in cytoplasm. As a result, antisense oligonucleotides conjugated with NLS could inhibit human telomerase in human leukemia cells much more strongly than phosphorothioate oligonucleotides.