title: Biological availability and nuclease resistance extend the in vitro activity of a phosphorothioate-3'hydroxypropylamine oligonucleotide.
abstract: Augmented biological activity in vitro has been demonstrated in oligonucleotides (oligos) modified to provide nuclease resistance, to enhance cellular uptake or to increase target affinity. How chemical modification affects the duration of effect of an oligo with potent activity has not been investigated directly. We postulated that modification with internucleotide phosphorothioates and 3' alkylamine provided additional nuclease protection which could significantly extend the biological activity of a 26 mer, (T2). We showed this analog, sT2a, could maximally inhibit interferon gamma-induced HLA-DR mRNA synthesis and surface expression in both HeLa and retinal pigmented epithelial cells and could continue to be effective, in the absence of oligo, 15 days following initial oligo treatment; an effect not observed with its 3'amine counterpart, T2a. In vitro stability studies confirmed that sT2a conferred the greatest stability to nucleases and that cellular accumulation of 32P-sT2a in both cell types was also greater than other T2 oligos. Using confocal microscopy, we revealed that the intracellular distribution of sT2a favored greater nuclear accumulation and release of oligo from cytoplasmic vesicles; a pattern not observed with T2a. These results suggest that phosphorothioate-3'amine modification could increase the duration of effect of T2 oligo by altering nuclease resistance as well as intracellular accumulation and distribution; factors known to affect biological availability.
authors.affiliation: Department of Surgery, School of Medicine, University of California-San Francisco 94143.
authors.forename: R C
authors.initials: RC
authors.lastname: Tam
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.forename: S
authors.initials: S
authors.lastname: Noonberg
authors.forename: D G
authors.initials: DG
authors.lastname: Hwang
authors.forename: G
authors.initials: G
authors.lastname: Lui
authors.forename: C A
authors.initials: CA
authors.lastname: Hunt
authors.forename: M R
authors.initials: MR
authors.lastname: Garovoy
mesh_terms: D001483:Base Sequence; D001682:Biological Availability; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004355:Drug Stability; D015870:Gene Expression; D006684:HLA-DR Antigens / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D010857:Pigment Epithelium of Eye / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D011994:Recombinant Proteins; D012260:Ribonucleases / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013873:Thionucleotides
chemical_list: D006684:HLA-DR Antigens; D009841:Oligonucleotides; D012333:RNA, Messenger; D011994:Recombinant Proteins; D013873:Thionucleotides; C086722:phosphorothioate-3'-hydroxypropylamine oligonucleotide sT2a; D007371:Interferon-gamma; D012260:Ribonucleases