Cellular uptake and intracellular trafficking of oligonucleotides

Abstract

Oligonucleotides manifest much promise as potential therapeutic agents. However, understanding of how oligonucleotides function within living organisms is still rather limited. A major concern in this regard is the mechanisms of cellular uptake and intracellular trafficking of both ‘free’ oligonucleotides and oligonucleotides associated with various polymeric or nanocarrier delivery systems. Here we review basic aspects of the mechanisms of endocytosis and intracellular trafficking and how insights from these processes can be used to understand oligonucleotide delivery. In particular we discuss opportunities for escape of oligonucleotides from endomembrane compartments and describe recent studies using small molecules to enhance oligonucleotide effects.

Non-coding RNAs as drug targets

“…Duplex RNAs or ASOs are complex molecules that can cause off-target effects through multiple mechanisms (Box 1, Box 2) 27,28 . They are often delivered into cultured cells using cationic lipid 29 , which while an excellent delivery tool, can compound the observation of off-target effects. Nucleic acids can also exert effects that are sequence-dependent, but independent of interactions with the intended RNA target.…”

6BIO Enhances Oligonucleotide Activity in Cells: A Potential Combinatorial Anti-androgen Receptor Therapy in Prostate Cancer Cells

“…12,16,33 It is commonly accepted that ASOs delivered by gymnosis are internalized into cells through the process of endocytosis. They then enter the membrane vesicle endosome-lysosome shuttling system.…”

“…The ability of PS oligos to enter the cells without transfection reagents ("free uptake") had been appreciated for several years, 12 but the discovery of gymnosis, 9,[13][14][15][16] which demonstrated that these PS LNA oligos can not only enter cells, but can also produce gene silencing, has placed these potentially therapeutic molecules among the leaders in the arsenal of experimental oligos. Absent the side effects of transfection, in vitro gymnotic delivery of ASOs more closely parallels the administration of saline formulations of ASOs in vivo.…”

Smart polymeric nanocarriers for small nucleic acid delivery

“…Nanocarriers are generally uptaken by cells via adsorptive endocytosis (4,14). Thus, stronger binding affinity to the target cellular surface is likely to result in more efficient cellular internalization of nanocarriers.…”

“…These backbone modifications not only protect nucleic acids from enzymatic degradation, but also affect their biodistribution and cellular uptake profiles. For instance, phosphorothioate-modified ASOs are reported to bind to plasma proteins in the bloodstream, leading to enhanced accumulation in the liver (4).…”