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Results for “antisense targeting”

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At least 19 recordsLinked to original sources

PubMed1992

Specific inhibition of hepatitis B viral gene expression in vitro by targeted antisense oligonucleotides.

A 21-mer oligodeoxynucleotide complementary to the polyadenylation signal for human hepatitis B virus (HBV) was complexed to a soluble DNA-carrier system that is targetable to hepatocytes via asialoglycoprotein receptors present on those cells. A cell line, HepG2 (2.2.15) that possesses asialoglycoprotein receptors and is permanently transfected with hepatitis B virus (ayw subtype) was exposed to complexed antisense DNA or controls. In the presence of complexed antisense DNA, the concentration of hepatitis B surface antigen in medium was 80% lower than controls after 24 h. Furthermore, during the next 6 days, there was no significant increase in surface antigen concentration in the presence of complexed antisense DNA. The inhibition could be effectively blocked by competition with an excess of free asialoglycoprotein. Total protein synthesis remained unchanged by exposure to complexed antisense sequences under identical conditions. In addition, HBV DNA in the medium and cell layers after 24-h exposure to complexed antisense sequences was 80% lower than in controls. The data indicate that antisense oligonucleotides complexed by a soluble DNA-carrier system can be targeted to cells via asialoglycoprotein receptors resulting in specific inhibition of hepatitis B viral gene expression and replication.

Asialoglycoprotein Receptor↗

PubMed1992

The effect of loop size in antisense and target RNAs on the efficiency of antisense RNA control.

Most natural antisense RNAs display a high degree of secondary structure with stem-loops as their most prominent feature. Mutations affecting the inhibitory activity of these RNAs most often map in or close to loop regions in both the antisense and target RNAs. The primary recognition loops often contain 5-7 unpaired nucleotides. Nucleotide changes in the loops affect the binding rate and, hence, the inhibitory effect on the activity of the target RNA. Here we address the question whether loop sizes affect binding rates between antisense and target RNAs, using the replication control system of plasmid R1 as a model system. By creating a series of loop size mutants we show that loop size alterations have strong effects on the binding rates between the two reactant RNAs in vitro, and that most of the mutations analyzed display corresponding effects on antisense RNA control in vivo. Our data suggest that the three-dimensional structures of antisense and target RNA stem-loops are crucial for determining binding rates. The implications of these results for the design of efficient artificial antisense RNA control systems are discussed.

Bacterial Proteins↗

PubMed1991

Identification and analysis of antisense RNA target regions of the human immunodeficiency virus type 1.

Antisense RNA, transcribed intracellularly from constitutive expression cassettes, inhibits the replication of the human immunodeficiency virus type 1 (HIV-1) as demonstrated by a quantitative microinjection assay in human SW480 cells. Infectious proviral HIV-1 DNA was co-microinjected together with a fivefold molar excess of plasmids expressing antisense RNA complementary to a set of ten different HIV-1 target regions. The most inhibitory antisense RNA expression plasmids were targeted against a 1 kb region within the gag open reading frame and against a 562 base region containing the coding sequences for the regulatory viral proteins tat and rev. Experimental evidence is presented that the antisense principle is the inhibitory mechanism in this assay system.

Cell Line↗

PubMed1989

Proliferation of human malignant melanomas is inhibited by antisense oligodeoxynucleotides targeted against basic fibroblast growth factor.

Human malignant melanomas, unlike normal melanocytes, can proliferate in the absence of exogenous basic fibroblast growth factor (bFGF). Exposure of primary melanomas in the vertical growth phase and metastatic melanomas to antisense oligodeoxynucleotides targeted against three different sites of human bFGF mRNA inhibited cell proliferation and colony formation in soft-agar. In contrast, exposure of human bFGF sense or antisense oligonucleotides complementary to human beta-nerve growth factor or insulin-like growth factor I mRNA had no such effects. These experiments indicate that activation of the bFGF gene may play an important role in the progression from melanocytic precursor lesions to malignant melanoma.

Antineoplastic Agents↗

PubMed2026

A First-in-Japanese Phase 1, Double-Blind, Placebo-Controlled, Parallel-Cohort Study of Sefaxersen, an Antisense Oligonucleotide Targeting Complement Factor B, in Healthy Participants.

Increased activity in the complement alternative pathway (AP) plays a key role in diseases such as IgA nephropathy (IgAN). This first-in-Japanese double-blind Phase 1 study investigated the pharmacokinetics (PK), pharmacodynamics (PD), safety, and tolerability of sefaxersen (RO7434656), an antisense oligonucleotide targeting complement factor B messenger RNA. Healthy participants were randomized equally into four cohorts: placebo or sefaxersen 20, 40, or 70 mg. The PK, PD, and safety endpoints were monitored throughout the study and during the 90-day follow-up period. All 24 participants completed the study, with no new safety signals or clinically meaningful changes in blood chemistry, electrocardiogram, or vital signs observed. Plasma sefaxersen concentration demonstrated a biphasic PK profile, characterized by an initial rapid decline followed by a slow elimination. Sefaxersen decreased PD markers related to the complement AP selectively, without affecting the classical pathway, in a dose-dependent manner, and the PD effects persisted over 2 to 3 months. Sefaxersen was well tolerated by healthy Japanese participants, with a manageable safety profile. These findings support the inclusion of Japanese patients with IgAN in the global Phase 3 study (IMAGINATION, NCT05797610).

Humans↗

PubMed1992

Increased specificity for antisense oligodeoxynucleotide targeting of RNA cleavage by RNase H using chimeric methylphosphonodiester/phosphodiester structures.

One of the inherent problems in the use of antisense oligodeoxynucleotides to ablate gene expression in cell cultures is that the stringency of hybridization in vivo is not subject to control and may be sub-optimal. Consequently, phosphodiester or phosphorothioate antisense effectors and non-targeted cellular RNA may form partial hybrids which are substrates for RNase H. Such processes could promote the sequence dependent inappropriate effects recently reported in the literature. We have attempted to resolve this problem by using chimeric methylphosphonodiester/phosphodiester oligodeoxynucleotides. In contrast to the extensive RNA degradation observed with all-phosphodiester oligodeoxynucleotides, highly modified chimeric antisense effectors displayed negligible, or undetectable, cleavage at non-target sites without significantly impaired activity at the target site. We also note that all of the all-phosphodiester oligodeoxynucleotides tested demonstrated inappropriate effects, and that such undesirable activity could vary widely between different sequences.

Amino Acid Sequence↗

PubMed1989

Artificial immune system against viral infection involving antisense RNA targeted to the 5'-terminal noncoding region of coliphage SP RNA.

We previously reported the utilization of antisense RNA in the development of a novel immune system against RNA coliphage SP proliferation (Hirashima et al. [1986] Proc. Natl. Acad. Sci. U.S. 83, 7726-7730). We attempted to determine the most effective (i.e., those eliciting antiviral activity) sequences for targeting micRNAs within the 5'-terminal noncoding region of 54 nucleotides (nt). It was found that a 30-nt micRNA against the sequence from base 32 to 61 exhibited nearly complete inhibition of phage production. Upon further dissection of this sequence, it was concluded that the most effective micRNA against phage SP production should contain the sequences complementary to the Shine-Dalgarno (SD) sequence of the first gene and its 13-nt upstream sequence. The addition of downstream sequences had little effect. These results suggest that the micRNA functions by preventing the binding of ribosomes to the SD sequence of the first gene. The addition of further upstream sequences had a significant negative effect on the micRNA function, indicating that the removal of such impeditive sequences from a micRNA is an important strategy for the development of a potent micRNA immune system.

Base Sequence↗

PubMed1990

Control of replication of plasmid R1: formation of an initial transient complex is rate-limiting for antisense RNA--target RNA pairing.

The replication frequency of plasmid R1 is determined by the availability of the initiator protein RepA. Synthesis of RepA is negatively controlled by an antisense RNA, CopA, which forms a duplex with the upstream region of the RepA mRNA, CopT. We have previously shown that the in vitro formation of the CopA-CopT duplex follows second-order kinetics and occurs in at least two steps. The first step is the formation of a transient (kissing) complex, which is subsequently converted to a persistent duplex. Here, we investigate the details of the reaction scheme and determine the rate constants of the pathway from the free RNAs to the complete duplex. Using a shortened CopA RNA (CopI) we have been able to determine the association and dissociation rate constants (k1,k-1) for the kissing complex (which are inferred to be the same for CopI-T and CopA-T), and measured the hybridization rate constant k2 (for CopA-T k2 is at least 1000-fold greater than for CopI-T). The analysis of CopA derivatives of mutant and wild-type origin shows that the rate of formation of the kissing complex is rate-limiting for the overall pairing reaction between CopA and CopT, both in vitro and in vivo. The biological implications of the kinetically irreversible RNA-RNA binding reaction scheme are discussed.

DNA Mutational Analysis↗

PubMed1992

Antisense probes targeted to an internal domain in U2 snRNP specifically inhibit the second step of pre-mRNA splicing.

Functional domains within the mammalian U2 snRNP particle that are required for pre-mRNA splicing have been analysed using antisense oligonucleotides. A comparison of the melting temperatures of duplexes formed between RNA and different types of antisense oligonucleotides has demonstrated that the most stable hybrids are formed with probes made of 2'-O-allyl RNA incorporating the modified base 2-aminoadenine. We have therefore used these 2'-O-allyl probes to target sequences within the central domain of U2 snRNA. Overlapping biotinylated 2'-O-allyloligoribonucleotides complementary to the stem loop Ila region of U2 snRNA (nucleotides 54-72) specifically affinity selected U2 snRNA from HeLa nuclear extracts. These probes inhibited mRNA production in an in vitro splicing assay and caused a concomitant accumulation of splicing intermediates. Little or no inhibition of spliceosome assembly and 5' splice site cleavage was observed for all pre-mRNAs tested, indicating that the oligonucleotides were specifically inhibiting exon ligation. This effect was most striking with a 2'-O-allyloligoribonucleotide complementary to U2 snRNA nucleotides 57-68. These results provide evidence for a functional requirement for U2 snRNP in the splicing mechanism occurring after spliceosome assembly.

Base Sequence↗

PubMed1992

Epstein-Barr viral latency and cell immortalization as targets for antisense oligomers.

The approach of using an antisense oligonucleotide to oppose the synthesis of a single selected viral gene product needed to maintain the EBV episome in non-virus-producing cells appears to be promising not only for possible cure of latent viral infection, but also for reversal of EBV-driven cell proliferation. It is also possible that targeting multiple latent viral genes might mount a synergistic effect that would prove to be more efficient at curing latent infection. However, further work is needed to identify the reasons for the variable results that are observed as well as to prove specificity of the inhibitory effects. Finally, we are also working on other assays and methods to screen compounds rapidly.

Antigens, Viral↗

PubMed1990

An antisense oligodeoxynucleotide targeted against the type II beta regulatory subunit mRNA of protein kinase inhibits cAMP-induced differentiation in HL-60 leukemia cells without affecting phorbol ester effects.

The type II beta regulatory subunit of cAMP-dependent protein kinase (RII beta) has been hypothesized to play an important role in the growth inhibition and differentiation induced by site-selective cAMP analogs in human cancer cells, but direct proof of this function has been lacking. To address this issue, HL-60 human promyelocytic leukemia cells were exposed to RII beta antisense synthetic oligodeoxynucleotide, and the effects on cAMP-induced growth regulation were examined. Exposure of these cells to RII beta antisense oligodeoxynucleotide resulted in a decrease in cAMP analog-induced growth inhibition and differentiation without apparent effect on differentiation induced by phorbol esters. This loss in cAMP growth regulatory function correlated with a decrease in basal and induced levels of RII beta protein. Exposure to RII beta sense, RI alpha and RII alpha antisense, or irrelevant oligodeoxynucleotides had no such effect. These results show that the RII beta regulatory subunit of protein kinase plays a critical role in the cAMP-induced growth regulation of HL-60 leukemia cells.

Base Sequence↗

PubMed1992

Inhibition of smooth muscle cell proliferation by an antisense oligodeoxynucleotide targeting the messenger RNA encoding proliferating cell nuclear antigen.

BACKGROUND: The process by which normally quiescent vascular smooth muscle cells (SMCs) change into proliferating cells, which express and respond to multiple growth factors, plays a major role in restenosis after coronary angioplasty. We are attempting to inhibit SMC proliferation by interventions that inhibit specific factors involved in signal transduction pathways leading to cell division. To date, all studies taking this approach have attempted to block the effects of mitogens acting on the cell surface. In contrast, we have focused on a strategy that bypasses cell surface-mediated events by directly inhibiting the expression of proliferating cell nuclear antigen (PCNA), an intranuclear protein that functions in a final common pathway shared by diverse mitogen-induced signals. In the present investigation, we determined whether antisense oligodeoxynucleotides (ODNs) complementary to the messenger RNA of PCNA will inhibit PCNA expression and thereby reduce SMC proliferation. METHODS AND RESULTS: When antisense ODNs (15- or 18-mer), modified to inhibit their degradation, are introduced into the medium of rat aortic SMCs in concentrations ranging from 10 to 100 microM, the 18-mer ODN, in a concentration-related manner, decreases SMC growth (as assessed by cell counting) by more than 50%. This effect persists for at least 9 days. An ODN with the same nucleotides but a scrambled sequence has little effect. Western blots and immunocytochemistry indicate that the antisense ODN reduces expression of PCNA protein. CONCLUSIONS: Our results demonstrate that an antisense ODN directed at the messenger RNA of PCNA decreases expression of the PCNA gene product and reduces SMC proliferation. In addition, these results provide an important impetus to initiating in vivo studies to determine the feasibility of antisense strategies in the prevention of coronary restenosis.

Angioplasty, Balloon, Coronary↗

PubMed1988

Human promyelocytic leukemia HL-60 cell proliferation and c-myc protein expression are inhibited by an antisense pentadecadeoxynucleotide targeted against c-myc mRNA.

The human promyelocytic leukemia cell line HL-60 overexpresses the c-myc protooncogene. A calculated secondary structure for c-myc mRNA placed the initiation codon in a bulge of a weakly base-paired region. Treatment of HL-60 cells with 5' d(AACGTTGAGGGGCAT) 3', complementary to the initiation codon and the next four codons of c-myc mRNA, inhibited c-myc protein expression in a dose-dependent manner. However, treatment of HL-60 cells with 5' d(TTGGGATAACACTTA) 3', complementary to nucleotides 17-31 of vesicular stomatitis virus matrix protein mRNA, displayed no such effects. These results agree with analogous studies of normal human T lymphocytes [Heikkila, R., Schwab, G., Wickstrom, E., Loke, S. L., Pluznik, D. H., Watt, R. & Neckers, L. M. (1987) Nature (London) 328, 445-449], except that only one-third as much oligomer was needed for a comparable effect. Proliferation of HL-60 cells in culture was inhibited in a sequence-specific, dose-dependent manner by the c-myc-complementary oligomer, but neither the oligomer complementary to vesicular stomatitis virus matrix protein mRNA nor 5' d(CATTTCTTGCTCTCC) 3', complementary to nucleotides 5399-5413 of human immunodeficiency virus tat gene mRNA, inhibited proliferation. It thus appears that antisense oligodeoxynucleotides added to myc-transformed cells via culture medium are capable of eliciting sequence-specific, dose-dependent inhibition of c-myc protein expression and cell proliferation.

Base Sequence↗

PubMed1992

Dual-target inhibition of HIV-1 in vitro by means of an adeno-associated virus antisense vector.

An adeno-associated virus vector encoding an antisense RNA was used to transduce stable intracellular resistance to human immunodeficiency virus-1 (HIV-1) in human hemopoietic and non-hemopoietic cell lines. The antisense targets are present in all HIV-1 transcripts and include the TAR sequence, which is critical for transcription and virus replication, and the polyadenylation signal. Cell lines expressing antisense RNA showed up to 95 percent inhibition of gene expression directed by the HIV-1 long terminal repeat and greater than 99 percent reduction in infectious HIV-1 production, with no detectable cellular toxicity. Because of their efficient transcription and inability to recombine with HIV-1, adeno-associated virus vectors represent a promising form of anti-retroviral gene therapy.

Base Sequence↗

PubMed1990

Inhibition of expression of human immunodeficiency virus-1 in vitro by antibody-targeted liposomes containing antisense RNA to the env region.

Previous studies revealed that antisense oligodeoxynucleotides to specific regions of the human immunodeficiency virus-1 (HIV-1) are potent inhibitors of replication of HIV-1 in vitro (Zamecnik, P. C., Goodchild, J., Taguchi, Y., and Sarin, P. S. (1986) Proc. Natl. Acad. Sci. U. S. A. 83, 4143-4146). We now report that antisense RNA, synthesized in vitro using T7 and SP6 RNA polymerase, displayed an anti-HIV-1 effect in the HTLV-IIIB/H9 system in vitro. Treatment of HIV-1-infected H9 cells with viral env region antisense RNA encapsulated in liposomes targeted by antibodies specific for the T cell receptor molecule CD3 almost completely inhibited HIV-1 production. The viral env segment covered a part of exon II of HIV-1 tat gene. No anti-HIV activity could be detected with similarly targeted liposome-encapsulated sense env RNA or with pol RNA synthesized in either the sense or antisense orientations, or with env region antisense RNA free in solution, or encapsulated in liposomes in the absence of the targeting antibody. A semiquantitative evaluation revealed that 4000-7000 RNA molecules became cell-bound in targeted liposomes; the half-life of the intracellularly present hybridizable antisense env RNA was approximately 12 h. Western blots showed that antisense env RNA suppressed tat gene expression by approximately 90% and gp160 production by 100%. These data were confirmed by immunoprecipitation studies. Northern blots (using an env probe) demonstrated the existence of all major HIV RNA species (9.3-, 4.3-, and 2.0-kb mRNA) in HIV-infected cells treated with antisense env RNA although at a reduced level. We conclude that the antisense env RNA inhibited viral protein production at the translational level.

Antiviral Agents↗

PubMed1992

Antisense and differentiation.

The use of antisense technology in animals has great potential for studying individual genes and for generating animal models of human disorders. Further control can be obtained by the use of inducible promoters to regulate the expression of antisense constructs, so that the timing and degree of antisense inhibition can be manipulated. In addition, tissue-specific promoters and enhancers provide the potential for targeting antisense inhibition to specific organs. Transgene expression in mice directed by the Cyp1a-1 promoter and enhancer elements can be increased in the liver up to 10,000-fold by administration to the animals of the inducer, 3-methylcholanthrene. Transfected antisense constructs containing splice site regions of the hypoxanthine guanine phosphoribosyltransferase (HPRT) gene can reduce HPRT activity to less than 1% of levels in parental NIH-3T3, COS, or HeLa cells. Antisense constructs including splice site regions and driven by the inducible Cyp1a-1 promoter should prove to be powerful tools in generating mouse models of human disorders.

Actins↗

PubMed2025

Antisense oligonucleotide-mediated MSH3 suppression reduces somatic CAG repeat expansion in Huntington's disease iPSC-derived striatal neurons.

Expanded CAG alleles in the huntingtin (HTT) gene that cause the neurodegenerative disorder Huntington's disease (HD) are genetically unstable and continue to expand somatically throughout life, driving HD onset and progression. MSH3, a DNA mismatch repair protein, modifies HD onset and progression by driving this somatic CAG repeat expansion process. MSH3 is relatively tolerant of loss-of-function variation in humans, making it a potential therapeutic target. Here, we show that an MSH3-targeting antisense oligonucleotide (ASO) effectively engaged with its RNA target in induced pluripotent stem cell (iPSC)-derived striatal neurons obtained from a patient with HD carrying 125 HTT CAG repeats (the 125 CAG iPSC line). ASO treatment led to a dose-dependent reduction of MSH3 and subsequent stalling of CAG repeat expansion in these striatal neurons. Bulk RNA sequencing revealed a safe profile for MSH3 reduction, even when reduced by >95%. Maximal knockdown of MSH3 also effectively slowed CAG repeat expansion in striatal neurons with an otherwise accelerated expansion rate, derived from the 125 CAG iPSC line where FAN1 was knocked out by CRISPR-Cas9 editing. Last, we created a knock-in mouse model expressing the human MSH3 gene and demonstrated effective in vivo reduction in human MSH3 after ASO treatment. Our study shows that ASO-mediated MSH3 reduction can prevent HTT CAG repeat expansion in HD 125 CAG iPSC-derived striatal neurons, highlighting the therapeutic potential of this approach.

Huntington Disease↗

PubMed2026

EGFR-co-amplified lncRNA ELDR drives glioblastoma tumorigenicity by enhancing BMI1 activity.

BACKGROUND: In glioblastoma (GBM), epidermal growth factor receptor (EGFR) amplification, one of the most prevalent genetic alterations, often occurs on extrachromosomal DNAs (ecDNAs) that contain amplified oncogenes and regulatory elements, driving tumor progression. Despite the central oncogenic role of EGFR amplification, therapeutic strategies targeting EGFR have demonstrated limited clinical efficacy, suggesting that additional mechanisms may underlie EGFR-driven GBM malignancy and treatment resistance. Long non-coding RNAs (lncRNAs) are critical regulators in cancer; however, the roles of EGFR-associated lncRNAs-particularly those localized on ecDNA-in GBM tumorigenicity and therapeutic resistance remain poorly understood. METHODS: Transcriptomic and genomic analyses were performed to identify lncRNAs co-amplified with EGFR. Biochemical and molecular biological studies were carried out to reveal the mechanisms. In vivo xenograft models were used to evaluate the tumorigenicity and the therapeutic efficacy of combination treatment strategies. RESULTS: The lncRNA EGFR long non-coding downstream RNA (ELDR) was co-amplified with EGFR on ecDNA and chromosomes and was associated with poor prognosis in glioma. ELDR promoted GBM tumorigenicity through a BMI1-dependent epigenetic mechanism operating in parallel with canonical EGFR signaling. Mechanistically, ELDR interacted with purine-rich element-binding protein A (PURA), disrupted the inhibitory PURA-BMI1 interaction, and thereby enhanced the activity of BMI1, a core component of Polycomb repressive complex 1 (PRC1). Therapeutically, combining a BMI1 inhibitor or ELDR-targeting antisense oligonucleotides (ASOs) with an EGFR inhibitor erlotinib significantly enhanced antitumor efficacy in preclinical models of  EGFR  -amplified GBM with high ELDR expression. CONCLUSION: EGFR co-amplified ELDR promotes GBM tumorigenicity by enhancing BMI1 activity. Targeting the ELDR-BMI1 axis in combination with EGFR inhibition represents a promising therapeutic strategy for a subset of  EGFR  -amplified GBMs with high ELDR expression.

EGFR↗