Antisense Nucleic Acids Research Articles

Complete response of Ctnnb1-mutated tumours to β-catenin suppression by locked nucleic acid antisense in a mouse hepatocarcinogenesis model

Hepatocellular cancer (HCC) remains a disease of poor prognosis, highlighting the relevance of elucidating key molecular aberrations that may be targeted for novel therapies. Wnt signalling activation, chiefly due to mutations in CTNNB1, have been identified in a major subset of HCC patients. While several in vitro proof of concept studies show the relevance of suppressing Wnt/β-catenin signalling in HCC cells or tumour xenograft models, no study has addressed the impact of β-catenin inhibition in a relevant murine HCC model driven by Ctnnb1 mutations. We studied the in vivo impact of β-catenin suppression by locked nucleic acid (LNA) antisense treatment, after establishing Ctnnb1 mutation-driven HCC by diethylnitrosamine and phenobarbital (DEN/PB) administration. The efficacy of LNA directed against β-catenin vs. scrambled on Wnt signalling was demonstrated in vitro in HCC cells and in vivo in normal mice. The DEN/PB model leads to HCC with Ctnnb1 mutations. A complete therapeutic response in the form of abrogation of HCC was observed after ten treatments of tumour-bearing mice with β-catenin LNA every 48h as compared to the scrambled control. A decrease in β-catenin activity, cell proliferation and increased cell death was evident after β-catenin suppression. No effect of β-catenin suppression was evident in non-Ctnnb1 mutated HCC, observed after DEN-only administration. Thus, we provide the in vivo proof of concept that β-catenin suppression in HCC will be of significant therapeutic benefit, provided the tumours display Wnt activation via mechanisms like CTNNB1 mutations.

Locating RNAs in situ with FISH-STIC probes.

The location of a molecule within the cell often provides important clues to its function and regulation, therefore techniques to locate RNA within cells are vital tools to study noncoding RNA function. Fluorescence in situ hybridization (FISH) is a simple and reliable approach to locate RNAs in any cell type. Intracellular localization of RNA using FISH (RNA-FISH) requires resolution at the single cell and single molecule level which can be achieved using fluorescent-labeled nucleic acid antisense probes. Sequential Tagged and Intertwined oligodeoxyribonucleotide Complex (FISH-STIC) probes are a straightforward means for laboratories to design their own FISH probes that can be synthesized commercially. Here we provide a detailed protocol for applying FISH-STIC probes for in situ hybridization on cultured cells as a convenient and flexible method for localizing individual RNAs with many fluorophores using fluorescence microscopy.

Antisense oligonucleotides: modifications and clinical trials

There has been an upsurge in the number of clinical trials involving chemically modified oligonucleotide-based drug candidates after the FDA approval of Vitravene, Macugen, and recently, Kynamro. Over the years, different types of backbone, nucleobase and/or sugar-modified oligonucleotides have been synthesized because natural DNA/RNA based oligonucleotides pose some limitations, such as poor binding affinity, low degree of nuclease resistance, affecting their direct use in antisense therapeutics. In this review article, we discuss in detail different modifications of nucleosides/oligonucleotides along with the related clinical trials, which demonstrated their potential as drug candidates for antisense and related nucleic acid based therapeutics.

Survivin inhibition via EZN-3042 in canine lymphoma and osteosarcoma.

Canine lymphoma (LSA) and osteosarcoma (OS) have high mortality rates and remain in need of more effective therapeutic approaches. Survivin, an inhibitor of apoptosis (IAP) family member protein that inhibits apoptosis and drives cell proliferation, is commonly elevated in human and canine cancer. Survivin expression is a negative prognostic factor in dogs with LSA and OS, and canine LSA and OS cell lines express high levels of survivin. In this study, we demonstrate that survivin downregulation in canine LSA and OS cells using a clinically applicable locked nucleic acid antisense oligonucleotide (EZN-3042, Enzon Pharmaceuticals, Piscataway Township, NJ, USA) inhibits growth, induces apoptosis and enhances chemosensitivity in vitro, and inhibits survivin transcription and protein production in orthotopic canine OS xenografts. Our findings strongly suggest that survivin-directed therapies might be effective in treatment of canine LSA and OS and support evaluation of EZN-3042 in dogs with cancer.

Experimental Screening mRNA Targets by Reverse Transcription for Ribozyme to GPA Expression Interference

An oligodeoxynucleotide library which the sequence were defined at 5 prime and randomized at 3 prime was employed to screen mRNA accessible targets,in reverse transcription and PCR after hybridized the library with mRNA. The mRNA of Glycophorin A(GPA),type I transmembrane glycoprotein,was screened and obtained 4 targets sequences. Accordingly 4 antisense nucleic acids designed respectively,the binding efficiency of every target were verified by using RNase H with antisense nucleic acids. Among them 2 targets showed better effects on binding and cutting. Designed 2 ribozymes to these targets,packaged in lentivirus system,then infected K562 cells(human erythroid leukemia line),the down-regulation effect of gene expression was validated by Real Time RT-PCR and by Western Blot. It was found that the screened targets showed the best effective knocking down effects on gene expression. The study provided a reference for mRNA targets screening and Ribozyme design,and was helpful in membrane receptor expression interference,since GPA is a transmembrane protein.

Quantitative evaluation of the improvement in the pharmacokinetics of a nucleic acid drug delivery system by dynamic PET imaging with 18F-incorporated oligodeoxynucleotides

Recently, we demonstrated the utility of positron emission tomography (PET) imaging-based pharmacokinetic evaluation studies for preclinical experiments and microdose clinical trials, mainly focused on low molecular weight compounds. In order to investigate the pharmacokinetics of nucleic acid drugs and their drug delivery systems (DDSs) in vivo by using PET imaging, we developed a novel and efficient method for radiolabeling oligodeoxynucleotides with the positron-emitting radionuclide 18F (stoichiometry-focused Huisgen-type 18F labeling). By using this method, we succeeded in synthesizing a variety of 18F-labeled oligodeoxynucleotides with not only phosphodiesters (PO) in natural forms, but also phosphorothioate (PS) and bridged nucleic acid (BNA) in artificial forms, and then performed PET studies and radioactive metabolite analyses of these 18F-labeled oligodeoxynucleotides. The tissue-distribution and dynamic changes in radioactivity showed significantly different profiles between these antisense oligodeoxynucleotides. The radioactivity of 18F-labeled PO-DNA and PO-BNA rapidly accumulated in the kidneys and liver and then moved to the renal medulla, ureter, bladder, and intestine. However, the radioactivity of 18F-labeled PS-DNA and PS-BNA, possessing PS backbone structures, was retained in the blood for relatively long periods and then gradually accumulated in the liver and kidneys. The metabolite analysis showed that 18F-labeled PO-DNA rapidly degraded by 5min and 18F-labeled PO-BNA gradually degraded over time by 60min. Conversely, 18F-labeled PS-DNA and PS-BNA were shown to be much more stable. To demonstrate the usefulness of the PET imaging technique for evaluating the improved targeting potential of the DDS, we designed and synthesized a cholesterol-modified oligodeoxynucleotide, that we developed as an antisense nucleic acid drug against proprotein convertase subtilisin/kexin type 9 (PCSK9) for hypercholesterolemia therapy, and evaluated its pharmacokinetics using PET imaging. As expected, the 18F-labeled cholesterol-modified PS-BNA-type oligodeoxynucleotide showed much higher and more rapid accumulation in the delivery target organ, that is, the liver, which encourages us to develop this drug. These results suggest that dynamic PET studies using 18F-incorporated oligodeoxynucleotide synthesized by stoichiometry-focused Huisgen-type labeling is useful for quantitative pharmacokinetic evaluation of nucleic acid drugs and their delivery systems.

Antisense nucleic acids—tough delivery

Antisense nucleic acids—tough delivery

Antisense peptide nucleic acid-functionalized cationic nanocomplex for in vivo mRNA detection

Acute lung injury (ALI) is a complex syndrome with many aetiologies, resulting in the upregulation of inflammatory mediators in the host, followed by dyspnoea, hypoxemia and pulmonary oedema. A central mediator is inducible nitric oxide synthase (iNOS) that drives the production of NO and continued inflammation. Thus, it is useful to have diagnostic and therapeutic agents for targeting iNOS expression. One general approach is to target the precursor iNOS mRNA with antisense nucleic acids. Peptide nucleic acids (PNAs) have many advantages that make them an ideal platform for development of antisense theranostic agents. Their membrane impermeability, however, limits biological applications. Here, we report the preparation of an iNOS imaging probe through electrostatic complexation between a radiolabelled antisense PNA-YR9 · oligodeoxynucleotide (ODN) hybrid and a cationic shell-cross-linked knedel-like nanoparticle (cSCK). The Y (tyrosine) residue was used for (123)I radiolabelling, whereas the R9 (arginine9) peptide was included to facilitate cell exit of untargeted PNA. Complete binding of the antisense PNA-YR9 · ODN hybrid to the cSCK was achieved at an 8 : 1 cSCK amine to ODN phosphate (N/P) ratio by a gel retardation assay. The antisense PNA-YR9 · ODN · cSCK nanocomplexes efficiently entered RAW264.7 cells, whereas the PNA-YR9 · ODN alone was not taken up. Low concentrations of (123)I-labelled antisense PNA-YR9 · ODN complexed with cSCK showed significantly higher retention of radioactivity when iNOS was induced in lipopolysaccharide+interferon-γ-activated RAW264.7 cells when compared with a mismatched PNA. Moreover, statistically, greater retention of radioactivity from the antisense complex was also observed in vivo in an iNOS-induced mouse lung after intratracheal administration of the nanocomplexes. This study demonstrates the specificity and sensitivity by which the radiolabelled nanocomplexes can detect iNOS mRNA in vitro and in vivo and their potential for early diagnosis of ALI.

First-in-human phase I study of EZN-4176, a locked nucleic acid antisense oligonucleotide (LNA-ASO) to androgen receptor (AR) mRNA in patients with castration-resistant prostate cancer (CRPC).

5052 Background: EZN-4176 is a third generationLNA-ASO that binds the ligand binding domain of AR mRNA resulting in full length AR mRNA degradation and decreased AR protein expression. Methods: Patients (pts) (performance status ECOG≤1) with progressing CRPC were eligible; prior abiraterone and enzalutamide treatment were allowed. EZN-4176 was administered as a weekly (QW) one-hour intravenous infusion. The starting dose was 0.5 mg/Kg with a 4-week dose-limiting toxicity (DLT) period. After determination of the DLT and the maximum tolerated dose (MTD) for weekly administration, a fortnightly schedule (Q2W) was initiated; a 3+3 modified Fibonacci dose escalation design was pursued. PD studies evaluated AR expression in tissue utilizing antibodies to the amino and carboxy-termini of the AR. Results: 22 pts were enrolled (median age 70.6 years, range 59 – 84 years). One pt was treated with the Q2W schedule. Two DLTs (G3/G4 ALT/AST elevation) occurred at 10 mg/Kg, which was therefore identified as the MTD for the weekly schedule. Multiple pts treated at 6.5 and 10 mg/Kg (5/9 pts, 55%) developed ≥G2 ALT and/or AST elevation after the first cycle requiring dose reduction and treatment delay. The most frequent adverse events (AEs) all-grades were fatigue (21/22 pts, 95.4%), nausea (10/22 pts, 45.4%), constipation (8/22 pts, 36.3%), AST (8/22 pts, 36.3%) and ALT (10/22 pts, 45.4%) elevation. The most frequent G3/4 AEs were AST (4/22 pts, 18.1%) and ALT (5/22 pts, 22.7%) elevation. Maximum PSA and circulating tumor cells (CTCs) declines are summarized below. There were no objective soft tissue responses. PD studies did not document any knockdown of AR expression Conclusions: EZN-4176 has limited antitumour activity in CRPC at its MTD for weekly administration. Safety, PK, PD and efficacy data will be presented. Clinical trial information: NCT01337518. [Table: see text]

Acute Kidney Injury During Therapy With an Antisense Oligonucleotide Directed Against PCSK9

Antisense oligonucleotides have been explored widely in clinical trials and generally are considered to be nontoxic for the kidney, even at high concentrations. We report a case of toxic acute tubular injury in a healthy 56-year-old female volunteer after a pharmacologically active dose of a locked nucleic acid antisense oligonucleotide was administered. The patient received 3 weekly subcutaneous doses of experimental drug SPC5001, an antisense oligonucleotide directed against PCSK9 (proprotein convertase subtilisin/kexin type 9) that is under investigation as an agent to reduce low-density lipoprotein cholesterol levels. Five days after the last dose, the patient's serum creatinine level increased from 0.81 mg/dL at baseline (corresponding to an estimated glomerular filtration rate [eGFR] of 78 mL/min/1.73 m(2)) to 2.67 mg/dL (eGFR, 20 mL/min/1.73 m(2)), and this increase coincided with the presence of white blood cells, granular casts, and minimal hematuria on urine microscopy. The patient's serum creatinine level peaked at 3.81 mg/dL (eGFR, 13 mL/min/1.73 m(2)) 1 week after the last oligonucleotide dose. Kidney biopsy showed multifocal tubular necrosis and signs of oligonucleotide accumulation. Upon conservative treatment, the patient's serum creatinine level gradually decreased and reached her baseline level 44 days after the last oligonucleotide was administered. The patient recovered fully and kidney function was normal at every follow-up visit.

DEADSouth protein localizes to germ plasm and is required for the development of primordial germ cells in Xenopus laevis

SummaryDEADSouth mRNA is a component of germ plasm in Xenopus laevis and encodes a DDX25 DEAD-box RNA helicase. To determine the intracellular localization of DEADSouth protein, we injected mRNA encoding DEADSouth tagged with mCherry fluorescent protein into fertilized eggs from transgenic Xenopus expressing EGFP fused with a mitochondrial targeting signal. The DEADSouth-mCherry fusion protein was localized to the germ plasm, a mitochondria-rich region in primordial germ cells (PGCs). DEADSouth overexpression resulted in a reduction of PGC numbers after stage 20. Conversely, DEADSouth knockdown using an antisense locked nucleic acid gapmer inhibited movement of the germ plasm from the cortex to the perinuclear region, resulting in inhibition of PGC division at stage 12 and a decrease in PGC numbers at later stages. The knockdown phenotype was rescued by intact DEADSouth mRNA, but not mutant mRNA encoding inactive DEADSouth helicase. Surprisingly, it was also rescued by mouse vasa homolog and Xenopus vasa-like gene 1 mRNAs that encode DDX4 RNA helicases. The rescue was dependent on the 3′ untranslated region (3′UTR) of DEADSouth mRNA, which was used for PGC-specific expression. The 3′UTR contributed to localization of the injected mRNA to the germ plasm, resulting in effective localization of DEADSouth protein. These results demonstrate that localization of DEADSouth helicase to the germ plasm is required for proper PGC development in Xenopus laevis.

SIRT Regulates the Molecular Interaction Between c-MYC and HIF-1α in Multiple Myeloma

Abstract 574Multiple Myeloma (MM) is an incurable hematologic malignancy characterized by the accumulation of malignant plasma cells. Dysregulation of MYC by rearrangement or translocation are common somatic events described either in early or late stage of the disease, and transcriptional profiling of MYC pathway activation is observed in more than 60% of MM cell lines. Hypoxia Inducible Factor-1α (HIF-1α) overexpression has been described in several MM cell lines and in about 30% of MM patients samples. In solid tumours, deregulation of c-MYC has been associated with HIF-1α upregulation: under physiologic conditions HIF-1α inhibits c-MYC activity by direct interaction and stimulation of a proteasome-dependent pathway.In the present study we explored the interaction between c-MYC and HIF-1α in a panel of MM cell lines (MM1S, OPM2, RPMI8226, U266). We had previously shown that treatment with EZN2968, a locked nucleic acid antisense oligonucleotide directed against HIF-1α, resulted in a significantly reduction of HIF-1α protein level after 24h of incubation. The reduction of HIF-1α was specific and lasted over 96h. To confirm the inhibition of HIF-1α activity, MM1S cells were treated with EZN2968 for 24h, lysed, co-precipitated with p300, and incubated with anti-HIF-1α antibody. We showed that HIF-1α was no longer associated p300 in EZN-treated compared to untreated samples, suggesting an inhibitory effect of HIF-1α activity. We next observed that treatment with EZN2968 induced a progressive accumulation of cells in S-phase with concomitant reduction of G2/M phase. By western blot analysis, we observed that p21 and p27, cell cycle check points negatively regulated by c-MYC, were up-regulated in treated samples. We further verified the effect of HIF-1α inhibition on c-MYC protein level by western blotting analysis. After treatment with EZN2968, c-MYC protein expression was reduced in a time dependent manner (c-MYC protein was almost undetectable after 72h of incubation), suggesting that c-MYC protein level is associated with inhibition of HIF-1α. To examine whether HIF-1α and c-MYC regulate each other promoter activity, we performed Chromatin Immunoprecipitation (ChIP) assays with HIF-1α or c-MYC antibodies. HIF-1A and MYC promoter amplification signals, were present in the controls samples, and increased after EZN2968 exposure, suggesting that these proteins can play a direct role in regulating each other’s activity.Recently, it has been shown that SIRT1, a transcription factor involved in a development, cellular stress responses, and metabolism, can modulate HIF-1α and c-MYC activity. By Immunoblotting assay, we observed that SIRT1 physically interacts with both proteins and that, after 24h of exposure to EZN2968, c-MYC and HIF-1α were no longer associated to SIRT1. These results were also confirmed at the transcriptional level, by ChIP assay using an anti-SIRT1 antibody. After 24h of treatment with EZN2968, we observed a significant increase of HIF-1A and MYC promoter amplification signals in treated compared to untreated samples, suggesting that SIRT1 recruitment at both promoters is dependent on HIF inhibition.We showed that in MM cell lines the expression of HIF-1α and c-MYC are linked and mediated by SIRT1 deacetylase protein. The data suggests a new regulatory mechanism for controlling c-MYC and HIF-1α activity by SIRT1. The identification of a HIF-c- MYC–SIRT 1 interaction in MM cell lines suggests a novel therapeutic target for MM patients. Disclosures:Cavo:Janssen: Consultancy, Honoraria, Speakers Bureau; Celgene: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria, Speakers Bureau; Millennium Pharmaceuticals: Consultancy.

Phosphorylation of ezrin/radixin/moesin (ERM) protein in spinal microglia following peripheral nerve injury and lysophosphatidic acid administration

Peripheral nerve injury activates spinal glial cells, which may contribute to the development of pain behavioral hypersensitivity. There is growing evidence that activated microglia show dynamic changes in cell morphology; however, the molecular mechanisms that underlie the modification of the membrane and cytoskeleton of microglia are not known. Here, we investigated the phosphorylation of ezrin, radixin, and moesin (ERM) proteins in the spinal cord after peripheral nerve injury. ERM is known to function as membrane-cytoskeletal linkers and be localized at filopodia- and microvilli-like structures. ERM proteins must be phosphorylated at a specific C-terminal threonine residue to be in the active state. The nature of ERM proteins in the spinal cord of animals in a neuropathic pain model has not been investigated and characterized. In the present study, we observed an increase in the phosphorylated ERM in the spinal microglia following spared nerve injury. The intrathecal administration of lysophosphatidic acid induced the phosphorylation of ERM proteins in microglia along with the development of mechanical pain hypersensitivity. Intrathecal administration of ERM antisense locked nucleic acid suppressed nerve injury-induced tactile allodynia and decreased the phosphorylation of ERM, but not the Iba1 staining pattern, in spinal glial cells. These findings suggest that lysophosphatidic acid induced the phosphorylation of ERM proteins in spinal microglia and may be involved in the emergence of neuropathic pain. These findings may underlie the pathological mechanisms of nerve injury-induced neuropathic pain.

Potent Antibacterial Antisense Peptide–Peptide Nucleic Acid Conjugates AgainstPseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic pathogen causing severe infections in hospital settings, especially with immune compromised patients, and the increasing prevalence of multidrug resistant strains urges search for new drugs with novel mechanisms of action. In this study we introduce antisense peptide-peptide nucleic acid (PNA) conjugates as antibacterial agents against P. aeruginosa. We have designed and optimized antisense peptide-PNA conjugates targeting the translation initiation region of the ftsZ gene (an essential bacterial gene involved in cell division) or the acpP gene (an essential bacterial gene involved in fatty acid synthesis) of P. aeruginosa (PA01) and characterized these compounds according to their antimicrobial activity and mode of action. Four antisense PNA oligomers conjugated to the H-(R-Ahx-R)(4)-Ahx-βala or the H-(R-Ahx)(6)-βala peptide exhibited complete growth inhibition of P. aeruginosa strains PA01, PA14, and LESB58 at 1-2 μM concentrations without any indication of bacterial membrane disruption (even at 20 μM), and resulted in specific reduction of the targeted mRNA levels. One of the four compounds showed clear bactericidal activity while the other significantly reduced bacterial survival. These results open the possibility of development of antisense antibacterials for treatment of Pseudomonas infections.

Combating Hepatitis C Virus by Targeting MicroRNA-122 Using Locked Nucleic Acids

MicroRNAs have been predicted to regulate the stability and translation of many target mRNAs that are involved in modulating disease outcome. Thus, valuable strategies to enhance or to diminish the function of microRNAs are needed to manipulate microRNA-mediated target gene expression. Recently, it has become apparent that one class of antisense oligonucleotides, locked nucleic acids, can be used to sequester microRNAs in the liver of a variety of animals including humans, opening the possibility of applying locked nucleic acid-mediated gene therapy. This review summarizes the success of sequestration of liver-specific microRNA miR-122 by antisense locked nucleic acids and their use in combating hepatitis C virus in clinical trials.

Downregulation of miR-181a upregulates sirtuin-1 (SIRT1) and improves hepatic insulin sensitivity

Sirtuin-1 (SIRT1) is a potential therapeutic target to combat insulin resistance and type 2 diabetes. This study aims to identify a microRNA (miRNA) targeting SIRT1 to regulate hepatic insulin sensitivity. Luciferase assay combined with mutation and immunoblotting was used to screen and verify the bioinformatically predicted miRNAs. miRNA and mRNA levels were measured by real-time PCR. Insulin signalling was detected by immunoblotting and glycogen synthesis. Involvement of SIRT1 was studied with adenovirus, inhibitor and SIRT1-deficient hepatocytes. The role of miR-181a in vivo was explored with adenovirus and locked nucleic acid antisense oligonucleotides. miR-181a targets the 3' untranslated region (3'UTR) of Sirt1 mRNA through a miR-181a binding site, and downregulates SIRT1 protein abundance at the translational level. miR-181a is increased in insulin-resistant cultured hepatocytes and liver, and in the serum of diabetic patients. Overexpression of miR-181a decreases SIRT1 protein levels and activity, and causes insulin resistance in hepatic cells. Inhibition of miR-181a by antisense oligonucleotides increases SIRT1 protein levels and activity, and improves insulin sensitivity in hepatocytes. Ectopic expression of SIRT1 abrogates the effect of miR-181a on insulin sensitivity, and inhibition of SIRT1 activity or SIRT1 deficiency markedly attenuated the improvement in insulin sensitivity induced by antisense miR-181a. In addition, overexpression of miR-181a by adenovirus impairs hepatic insulin signalling, and intraperitoneal injection of locked nucleic acid antisense oligonucleotides for miR-181a improves glucose homeostasis in diet-induced obesity mice. miR-181a regulates SIRT1 and improves hepatic insulin sensitivity. Inhibition of miR-181a might be a potential new strategy for treating insulin resistance and type 2 diabetes.

Subtracting Gene Function by Gene Silencing and Disruption in Bacteria

Gene silencing using antisense RNA or RNA interference (RNAi) is now a popular method used in eukaryotes. However, RNAi mechanism is absent in bacteria, and hence, single-stranded antisense RNAs, DNAs or nucleic acid analogs are used. Gene silencing in bacteria are achieved by either one of the following two approaches: expressing antisense RNAs using expression plasmids or adding synthetic antisense agents into the culture media. Recently, many advances on this method have been reported. In particular, the problem of low silencing efficiency has been solved remarkably, and as a result, this method is being used practically in biotechnology. This review mainly deals with the features and applications of gene silencing as a gene function subtracting method. Also, gene disruption is described as a competing and mutually complementary method. Keywords: Antisense RNA, Escherichia coli, gene disruption, gene knock-down, gene knock-out, gene silencing, growth essential gene, LNA, locked nucleic acid, paired-termini, peptide nucleic acid, PNA, RNA silencing, ribosome-binding site.

Patent Highlights

Patent Highlights

Cell number and transfection volume dependent peptide nucleic acid antisense activity by cationic delivery methods

Efficient intracellular delivery is essential for high activity of nucleic acids based therapeutics, including antisense agents. Several strategies have been developed and practically all rely on auxiliary transfection reagents such as cationic lipids, cationic polymers and cell penetrating peptides as complexing agents and carriers of the nucleic acids. However, uptake mechanisms remain rather poorly understood, and protocols always require optimization of transfection parameters. Considering that cationic transfection complexes bind to and thus may up-concentrate on the cell surface, we have now quantitatively compared the cellular activity (in the pLuc705 HeLa cell splice correction system) of PNA antisense oligomers using lipoplex delivery of cholesterol- and bisphosphonate-PNA conjugates, polyplex delivery via a PNA-polyethyleneimine conjugate and CPP delivery via a PNA-octaarginine conjugate upon varying the cell culture transfection volume (and cell density) at fixed PNA concentration. The results show that for all delivery modalities the cellular antisense activity increases (less than proportionally) with increasing volume (in some cases accompanied with increased toxicity), and that this effect is more pronounced at higher cell densities. These results emphasize that transfection efficacy using cationic carriers is critically dependent on parameters such as transfection volume and cell density, and that these must be taken into account when comparing different delivery regimes.

Screening of antisense accessible sites of human telomerase reverse transcriptase gene

Objective To screen the antisense nucleic acid accessible sites of human telomerase reverse transcriptase (hTERT) gene.Methods The 20 mer random oligonucleotide library was synthesized and then hybridized with in vitro transcripted total hTERT cRNA,then digested by RNase H.After primer extension and autoradiography,26 antisease accessible sites (AAS) were selected.Seven AAS had obvious stem-loop structure after analyzed by the RNAstructure software.The seven AAS were considered as the best AAS and the complementary antisense oligonucleotide (AS-ODN) were synthesized and transferred into prostate cancer cell line PC-3.Tetrazolium bromide (MTT) colorimetry assay and reverse transcription polymerase chain reaction (RT-PCR) were used to detect the growth inhibition and expression level of hTERT mRNA in prostate cancer cells respectively.Results After AS-ODN1-7 was transferred into PC-3 cells,the AS-ODN3 could significantly inhibit the growth of PC-3 cells (40.6 ± 1.0) ％ ( P ＜ 0.05 ),and suppress the hTERT mRNA expression ( 35.8 ± 1.2) ％ ( P ＜ 0.05 ) as compared with other groups.Conclusion To screen AAS of hTERT gene and synthesize there AS-ODAs can block the biological functions effectively. Key words: hTERT gene; Antisense oligonucleotide; Primer