Influence of Combinations of Lipophilic and Phosphate Backbone Modifications on Cellular Uptake of Modified Oligonucleotides

Numerous types of oligonucleotide modifications have been developed since automated synthesis of DNA/RNA became a common instrument in the creation of synthetic oligonucleotides. Despite the growing number of types of oligonucleotide modifications under development, only a few of them, and moreover, their combinations have been studied wide enough in terms of their in-fluence on the properties of corresponding NA constructions. In the present study, a number of oligonucleotides with combinations of 3′ end lipophilic (single cholesteryl or pair of dodecyl residues) and phosphate backbone modifications were synthesized. The influence of the combi-nation of used lipophilic groups with phosphate modifications of various nature and different position on the efficiency of cell penetration was evaluated. Obtained results indicate that even a couple of phosphate modifications are able to affect a set of oligonucleotide properties in a complex manner and can remarkably change cellular uptake. These data clearly show that the strategy of using different patterns of modification combinations has great potential for the ra-tional design of oligonucleotide structures with desired predefined properties.