Oligonucleotides, antisense therapy

Antisense therapy means the selective, sequence-specific inhibition of gene expression by single-stranded DNA oligonucleotides. By hybridizing to the target mRNA, which results in a subsequent double-helix formation, gene expression is blocked. This process can occur at any point between the conclusion of transcription and initiation of translation or even possibly during translation. 

Particles from cationic lipids may also be useful for antisense therapy of skin disease — a nontoxic increase in the oligonucleotide uptake by cultivated keratinocytes and a sebocyte cell line has been reported [66]. Moreover, cationic dendri-mers also efficiently transfer reporter gene DNA to human keratinocytes cultivated in vitro. In the skin of hairless mice, in vivo transfection was possible with complexes, yet reporter gene expression was localized to perifollicular areas. Transfection, however, failed with the naked plasmid. For prolonged contact, biodegradable membranes coated with dendrimer/DNA complexes were used [67]. This hints at a follicular uptake of these complexes and indicates that gene transfection also may be possible with human skin, which has a thicker stratum comeum compared with mouse skin (eight to ten vs. two to three layers [58]). 

The primary application of LNA has been in antisense therapy due to the aforementioned properties. It has been used to knock down human protein kinase C-a (PKC-ot) with greater efficiency than the corresponding phosphor-othioate ODN, as an inhibitor of human telomerase, to block the synthesis of RNA polymerase II and to inhibit human vascular smooth muscle cell growth. LNA-modified oligonucleotides have also been used in RNA interference (RNAi). ... 

Oligonucleotides are only very poorly taken up into cells, and a variety of conjugates have been studied with the aim of improving cellular uptake. The cellular uptake of the ISIS ICAM-1-specific phosphorothioate ODN conjugated to cholesterol (ISIS-9388) has been studied in vivo for uptake into liver cells in rats." The presence of the 3 -cholesterol on the ODN resulted in a two-fold increase in accumulation of the ODN in various liver cell types, and the authors conclude that conjugation of ODNs with cholesterol is likely to be beneficial for antisense therapy of liver-associated diseases. ODNs which have 3 -linked cholesterol have been shown to interact with cell membranes in macrophages, and... 

Antisense Therapy This is a relatively new approach and it requires the modifications to oligonucleotides that can bind to RNA and DNA (refer to Appendix 2 for a description of cell structure, genes, DNA, RNA and proteins). The antisense drugs are used to stop transcriptional (from DNA) or translational (from RNA) pathways from proceeding, and so interfere with the process of disease. 

Antisense therapy Aimed at inhibiting the production of specific proteins, antisense oligonucleotides entrapped in PLGA nanospheres disrupt growth regulation of vascular smooth muscle cells and prevent... 

A newer, highly experimental approach to anxiety therapy is the use of antisense oligonucleotides to the anxiogenic peptide, NPY (44). 

Antisense Oligonucleotides. Table 1 Malignant disorders as potential targets for ribozyme gene therapy... 

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