Antisense Oligonucleotide Analogs Research Articles

Introduction and History of the Chemistry of Nucleic Acids Therapeutics.

This introduction charts the history of the development of the major chemical modifications that have influenced the development of nucleic acids therapeutics focusing in particular on antisense oligonucleotide analogues carrying modifications in the backbone and sugar. Brief mention is made of siRNA development and other applications that have by and large utilized the same modifications. We also point out the pitfalls of the use of nucleic acids as drugs, such as their unwanted interactions with pattern recognition receptors, which can be mitigated by chemical modification or used as immunotherapeutic agents.

Inhibitory signaling through signal regulatory protein-α is not sufficient to explain the antitumor activities of CD47 antibodies

CD47 is a receptor for the secreted protein thrombospondin-1 and a counterreceptor for two members of the signal regulatory protein (SIRP) family. These interactions play important roles in hemostasis, cardiovascular pathophysiology, ischemic injuries, inflammation, radiation injuries, and cancer. Correspondingly, antibodies that block thrombospondin-1 or SIRPα binding and antisense oligonucleotide analogs that suppress CD47 expression have shown efficacy in treating rodent and porcine models of these diseases.

Lipoplex and peptide-based strategies for the delivery of steric-block oligonucleotides

Synthetic oligonucleotides offer interesting prospects for the control of gene expression but clinical applications have been severely limited by their poor bioavailability. Cationic lipids have been widely used for the delivery of charged oligonucleotide (ON) analogues but most of the commercial formulations are toxic and poorly stable in the presence of serum proteins. We have developed a DOGS/DOPE liposome formulation named DLS (for delivery liposomal system), that allows for the efficient nuclear delivery of negatively charged antisense ON analogues as monitored by fluorescence microscopy and by their ability to correct deficient pre-mRNA splicing, even in serum-supplemented cell culture. Uncharged DNA mimics such as peptide nucleic acids (PNA), or phosphorodiamidate morpholino (PMO) ON are particularly interesting for their high metabolic stability and affinity for complementary RNA targets but they cannot be delivered with cationic lipids. Cell penetrating peptides (CPP), such as Tat or penetratin, have been used widely as conjugates for the delivery of various biomolecules and might be appropriate for neutral ON analogues. However, entrapment within endocytic vesicles severely limits the efficiency of PNA delivery by CPPs in the absence of endosomolytic drugs, such as chloroquine. The conjugation of new arginine-rich CPPs to PNA allows efficient nuclear delivery in the absence of chloroquine as monitored in a splicing correction assay. Both strategies have their advantages but DLS-mediated delivery remains more efficient than CPP delivery for the nuclear targeting of splice correcting ON analogues in vitro.

Antisense‐Oligonucleotide – ein universelles Therapieprinzip

AbstractIn recent years, a nova1 class of pharmaceuticals has been developed which bind in a predictable way to certain nucleic acid target sequences aiming at selective inhibition of expression of disease‐causing genes. The chemical structure of these so‐called antisense oligonucleotide compounds must be altered relative to their natural models to render them stable under in vivo conditions and to allow their penetration to the site of action inside cells. In this article, the principle of antisense oligonucleotide function, the structure of antisense oligonucleotide analogues, the different strategies for improvement of their biological potency, and selected reports on successful in vivo studies and first clinical investigations using these antisense oligonucleotides are discussed.

Development of Antisense and Antigene Oligonucleotide Analogs

Publisher Summary Many excellent reviews and monographs have been written describing the chemistry and biological activity of various antisense and antigene oligonucleotides. This chapter focuses on two lines of research that are aimed at the development of antisense and antigene oligonucleotide analogs. The first line of research involves the development of nuclease-resistant antisense oligonucleotide analogs, the oligonucleoside methylphosphonates. The second line of research involves the development of nucleoside and oligonucleotide analogs that can be used to recognize sequences in double-stranded DNA. Antisense oligonucleotides are designed to interact with cytoplasmic messenger RNA (mRNA) or with precursor mRNA in the nucleus. Antigene oligonucleotides are designed to bind to double-stranded DNA via the formation of triple-stranded complexes (triplexes). Antisense oligonucleotides depend on Watson–Crick hydrogen-bonding interactions between an oligomer and its target, whereas antigene oligonucleotides make use of Hoogsteen or reversed-Hoogsteen hydrogen-bonding schemes. Antisense and antigene oligonucleotide analogs hold great promise for the design of reagents that can be used to inhibit gene expression selectively at either the mRNA or DNA level.

Antisense phosphorothioate oligodeoxynucleotides: introductory concepts and possible molecular mechanisms of toxicity

Over the past 5 years or so, much attention has been given to the possible use of synthetic antisense oligonucleotide analogs as a new class of therapeutic agents that function by sequence-specific inhibition of genetic expression. The basic design concepts which underline this novel approach to drug discovery are briefly described herein, together with some of the chemical, biochemical, and pharmacological aspects of phosphorothioate oligodeoxynucleotides that are first-generation antisense compounds now under clinical investigation. Possible molecular mechanisms of toxicity for this class, and other structural types of antisense compounds are discussed with the hope of stimulating interest in future toxicological studies in this emerging area of drug development.

Inhibition of α-Fetoprotein Production in a Hepatoma Cell Line by Antisense Oligonucleotide Analogues1

alpha-Fetoprotein (AFP) is a fetal protein which is absent in adult serum. However, the AFP gene is expressed in some neoplastic cells. According to the literature, AFP may play a role in accelerating the growth of cancer cells. In this report, 15 meric antisense oligonucleotide analogues (phosphorothioates and methylphosphonates) and their chimeric forms, which were complementary to different regions of AFP mRNA, were synthesized, and their physical characteristics such as stability, melting temperature, and toxicity were compared. They were examined as to their inhibitor effects on the translation of AFP mRNA in a AFP-producing hepatoma cell line, HuH-7. We found that chimeric oligomers with methylphosphonate or phosphorothioate linkages at both the 5' and 3' ends were more effective than prototypic oligomers. Inhibition of 72% was achieved with a chimeric oligomer against the translational initiation region, at a concentration of 25 microM. No suppressive effect of the oligomers was observed on cell viability or albumin production, indicating the specificity of the inhibition.

Comparative inhibition of chloramphenicol acetyltransferase gene expression by antisense oligonucleotide analogues having alkyl phosphotriester, methylphosphonate and phosphorothioate linkages.

Several classes of oligonucleotide antisense compounds of sequence complementary to the start of the mRNA coding sequence for chloramphenicol acetyl transferase (CAT), including methylphosphonate, alkyltriester, and phosphorothioate analogues of DNA, have been compared to "normal" phosphodiester oligonucleotides for their ability to inhibit expression of plasmid-directed CAT gene activity in CV-1 cells. CAT gene expression was inhibited when transfection with plasmid DNA containing the gene for CAT coupled to simian virus 40 regulatory sequences (pSV2CAT) or the human immunodeficiency virus enhancer (pHIVCAT) was carried out in the presence of 30 microM concentrations of analogue. For the oligo-methylphosphonate analogue, inhibition was dependent on both oligomer concentration and chain length. Analogues with phosphodiester linkages that alternated with either methylphosphonate, ethyl phosphotriester, or isopropyl phosphotriester linkages were less effective inhibitors, in that order. The phosphorothioate analogue was about two-times more potent than the oligo-methylphosphonate, which was in turn approximately twice as potent as the normal oligonucleotide.