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At least 19 recordsLinked to original sources
PubMed1997

3-Morpholino-sydnonimine-induced suppression of human neutrophil degranulation is not mediated by cyclic GMP, nitric oxide or peroxynitrite: inhibition of the increase in intracellular free calcium concentration by N-morpholino-iminoacetonitrile, a metabolite of 3-morpholino-sydnonimine.

This study was designed to clarify the mechanism of the inhibitory action of a nitric oxide (NO) donor 3-morpholino-sydnonimine (SIN-1) on human neutrophil degranulation. SIN-1 (100-1000 microM) inhibited degranulation (beta-glucuronidase release) in a concentration-dependent manner and concomitantly increased the levels of cGMP in human neutrophils in suspension. However, further studies suggested that neither NO nor increase in cGMP levels were mediating the inhibitory effect of SIN-1 on human neutrophil degranulation because 1) red blood cells or 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl added as NO scavengers did not inhibit the effect; 2) inhibitors of cGMP synthesis (methylene blue) or phosphodiesterases (3-isobutyl-1-methylxanthine) did not produce changes in cell function correlating with the changes in cGMP. SIN-1 releases both nitric oxide and superoxide, which together form peroxynitrite. Chemically synthesized peroxynitrite (1-100 microM) did not inhibit, but at high concentrations (1000-2350 microM), it potentiated FMLP-induced beta-glucuronidase release from neutrophils. Thus formation of peroxynitrite from SIN-1 does not explain its inhibitory effects on neutrophil degranulation. The NO-deficient metabolite of SIN-1, SIN-1C (330-1000 microM) inhibited human neutrophil degranulation in a concentration-dependent manner similar to that of SIN-1 and reduced the increase in intracellular free calcium induced by N-formyl-L-methionyl-L-leucyl-L-phenylalanine. C88-3934 (330-1000 microM), another NO-deficient sydnonimine metabolite, also inhibited human neutrophil degranulation. In conclusion, the data shows that the NO-donor SIN-1 inhibits human neutrophil degranulation in a cGMP-, NO-, and peroxynitrite-independent manner, probably because of the formation of more stable active metabolites such as SIN-1C. The results demonstrate that studies on the role of NO and/or peroxynitrite carried out with SIN-1 and other NO-donors should be carefully re-evaluated as to whether the effects found are really attributable to NO or peroxynitrite and that in future studies, it will be crucial to carry out control experiments with the NO-deficient metabolites in any studies with sydnonimine NO-donors.

Acetonitriles↗
PubMed1995

Activity of the morpholino anthracycline 3'-deamino-3'-morpholino-13-deoxo-10-hydroxycarminomycin (MX2) against human tumor colony-forming units in vitro.

In several preclinical systems, the morpholino anthracycline MX2 has greater antitumor activity than doxorubicin, is less cardiotoxic, and is effective against multidrug resistant cancer cells. We used a human tumor soft-agar cloning assay to test the cytotoxicity of MX2 against single cell suspensions from freshly obtained human tumors. Tumor cells were exposed to MX2 at 0.05 and 0.5 micrograms/ml either for 1 hour (2-1 specimens; 77 [38%] assessable) or continuously (231 specimens; 91 [39%] assessable). Superior antitumor activity was observed with continuous exposure (19% in vitro response at 0.05 micrograms/ml and 69% at 0.5 micrograms/ml) than with 1-hour exposure (1.3% at 0.05 micrograms/ml and 12% at 0.5 micrograms/ml). Activity was seen against all types of cancer tested including renal (91%), melanoma (88%), ovarian (73%), breast (71%) and non-small-cell lung (67%) cancer at a MX2 concentration of 0.5 micrograms/ml after continuous exposure. If appropriate plasma levels can be achieved in patients, MX2 could have significant clinical activity with those tumors.

Antibiotics, Antineoplastic↗
PubMedDate not supplied

The effect of epidermal growth factor receptor antisense morpholino oligomer on non-small cell lung cancer cell line.

Overexpression of the epidermal growth factor receptor (EGFR) has been identified as a common component of various cancer types including lung cancer. Recently morpholino oligonucleotides appeared as a promising modification for antisense applications with few toxic effects and their stability. We investigated the effect of EGFR antisense morpholino oligomer on non-small cell lung cancer (NSCLC) cell line by evaluating EGFR mRNA, protein product and cell proliferation. The EGFR antisense morpholino oligomer was designed to target the translation start site in the EGFR mRNA. The four base-mismatch morphlino oligomer was designed as a control for EGFR antisense morpholino oligomer. These morpholino oligomers were introduced into NCI-H125 cell line which showed overexpression of EGFR. The EGFR mRNA and protein expression were quantified by real time RT-PCR and ELISA, respectively. The significant repression in both EGFR mRNA and protein expression was observed for three days after single treatment with EGFR antisense morpholino oligomer. Furthermore, the growth of NCI-H125 cell line was significantly inhibited with treatment by EGFR antisense morpholino oligomer. Our results indicate that EGFR antisense morpholino oligomer represses the EGFR expression at both mRNA and protein level and inhibits the proliferation of NSCLC cell line suggesting that it may be a promising strategy as one of antisense therapies for NSCLC.

Carcinoma, Non-Small-Cell Lung↗
PubMed2001

Action of morpholinos in Ciona embryos.

First, using morpholino against lacZ, we demonstrate that the morpholino specifically suppresses the translation of the gene introduced exogenously into Ciona eggs. Second, using morpholino against an alkaline phosphatase gene, we show that the morpholino suppresses the translation of the endogenous gene as well. Third, using morpholino against beta-catenin gene, we confirm that the suppression by the morpholino can be rescued by injection of beta-catenin mRNA. All of these results indicate that morpholino act in Ciona embryos to specifically block the function of endogenous genes as well as exogenously introduced genes. genesis 30: 103--106, 2001.

Animals↗
PubMed2005

Morpholino antisense oligomer targeting human midkine: its application for cancer therapy.

Overexpression of a heparin-binding growth factor, midkine (MK), has been observed in many malignancies, making it an attractive therapeutic target. We used morpholino antisense oligomers to downregulate human MK expression in human prostate (PC-3) and colon carcinoma (SW620) cells, and determined the practical advantages of this anticancer therapeutic. Morpholino antisense oligomers directed against MK caused a dramatic and sequence-specific decrease of the target protein level, resulting in the inhibition of growth and anchorage-independent growth of the transfected cells. Furthermore, MK morpholino antisense oligomers exhibited a significant anticancer effect in the PC-3- and SW620-xenograft models. In comparison with phosphorothioate-modified oligodeoxynucleotide, morpholino oligomers showed 2 major advantages, stability and non-toxicity. MALDI-TOF mass spectrometric analysis showed that morpholino antisense oligomers were completely stable in the presence of serum nuclease(s). Serological examinations demonstrated no toxicity of MK morpholino antisense oligomers. Our study indicates that inhibition of MK expression by morpholino antisense oligomer is a promising novel and safe therapeutic strategy for cancers.

Animals↗
PubMed1995

Crystal structures of four morpholino-doxorubicin anticancer drugs complexed with d(CGTACG) and d(CGATCG): implications in drug-DNA crosslink.

Among the new generations of anthracycline drugs, morpholino-doxorubicin (MDox) and its derivative have unusually potent activity when compared with the parent doxorubicin. 3"-Cyano-morpholino-doxorubicin (CN-MDox) has been suggested to form a covalent crosslink to DNA, although the exact mode of interactions remains unclear. To establish the structural basis of this crosslink, we carried out X-ray diffraction analyses of the complexes between four different morpholino-doxorubicins (i.e., MDox, CN-MDox, (R)- and (S)-2"-methoxy-morpholino-Dox (MMDox)) and two DNA hexamers CGTACG and CGATCG. Their crystal data are similar to other Dau/Dox complexes with space group P4(1)2(1)2,a = b approximately 28 A, c approximately 53 A. The refined structures at approximately 1.8 A resolution revealed that two drug molecules bind to the duplex with the aglycons intercalated between the CpG steps with their N3'-morpholino-daunosamines in the minor groove. The morpholino moiety is flexible and may adopt different conformations dependent on the sequence context. The O1" atoms of the two morpholino groups in the drug-DNA complexes are in van der Waals contact. The structural results suggest possible crosslinking mechanism of CN-MDox. It is worth pointing out that by linking two piperazinyl- or piperidinyl-doxorubicins at the 1" positions a new type of bis-doxorubicin derivatives may be synthesized which may bind to a hexanucleotide sequence with some specificity.

Antibiotics, Antineoplastic↗
PubMed2001

Triplex formation by morpholino oligodeoxyribonucleotides in the HER-2/neu promoter requires the pyrimidine motif.

Triplex-forming oligonucleotides (TFOs) are good candidates to be used as site-specific DNA-binding agents. Two obstacles encountered with TFOs are susceptibility to nuclease activity and a requirement for magnesium for triplex formation. Morpholino oligonucleotides were shown in one study to form triplexes in the absence of magnesium. In the current study, we have compared phosphodiester and morpholino oligonucleotides targeting a homopurine-homopyrimidine region in the human HER2/neu promoter. Using gel mobility shift analysis, our data demonstrate that triplex formation by phosphodiester oligonucleotides at the HER-2/neu promoter target is possible with pyrimidine-parallel, purine-antiparallel and mixed sequence (GT)-antiparallel motifs. Only the pyrimidine-parallel motif morpholino TFO was capable of efficient triple helix formation, which required low pH. Triplex formation with the morpholino TFO was efficient in low or no magnesium. The pyrimidine motif TFOs with either a phosphodiester or morpholino backbone were able to form triple helices in the presence of potassium ions, but required low pH. We have rationalized the experimental observations with detailed molecular modeling studies. These data demonstrate the potential for the development of TFOs based on the morpholino backbone modification and demonstrate that the pyrimidine motif is the preferred motif for triple helix formation by morpholino oligonucleotides.

Base Sequence↗
PubMed2002

Targeted "knockdown" of channel expression in vivo with an antisense morpholino oligonucleotide.

We have examined whether antisense morpholino oligonucleotides (morpholinos) can be used as a tool to suppress or "knockdown" the expression of ion channels during development of the zebrafish. Because the acetylcholine receptor channel is well characterized in zebrafish and is abundant as skeletal muscle is found throughout the body, we sought to knock down its expression as a general test of the feasibility of this approach. A 25-mer morpholino was designed to target the 5' region of the cloned alpha-subunit and was injected into early stage blastulae in order to trap it in all developing cells. From the time of hatching (early on the third day of development) and for a few days after, a fraction of the injected embryos were immobile, i.e. were "morphant". Injection of blastulae without the morpholino or with a control morpholino containing four mispaired bases did not affect the embryos. Although the morphant embryos were generally normal in appearance, they lacked staining with alpha-bungarotoxin or an alpha-subunit-specific monoclonal antibody. In whole muscle cell recordings from morphant embryos, miniature end-plate potentials were undetectable in many of the cells and in most they had a slower, immature time course. These results are consistent with a greatly reduced, dysfunctional level of expression of acetylcholine receptors in morphant embryos. Because of their stability and specificity, morpholinos should prove useful for targeted deletion of transmitter receptors and channels in developing zebrafish and possibly in other preparations.

Animals↗
PubMed2003

Morpholino antisense oligonucleotide induced dystrophin exon 23 skipping in mdx mouse muscle.

The mdx mouse model of muscular dystrophy arose due to a nonsense mutation in exon 23 of the dystrophin gene. We have previously demonstrated that 2'-O-methyl phosphorothioate antisense oligonucleotides (AOs) can induce removal of exon 23 during processing of the primary transcript. This results in an in-frame mRNA transcript and subsequent expression of a slightly shorter dystrophin protein in mdx muscle. Refinement of AO design has allowed efficient exon skipping to be induced in mdx mouse muscle cultures at nanomolar concentrations. In contrast, splicing intervention by morpholino AOs has been applied to the beta-globin gene pre-mRNA in cultured cells to correct aberrant splicing when delivered in the micromolar range. The morpholino chemistry produces a neutral molecule that has exceptional biological stability but poor cellular delivery. We present data showing that exon skipping in mdx cells may be induced by morpholino AOs at nanomolar concentrations when annealed to a sense oligonucleotide or "leash", and delivered as a cationic lipoplex. We have investigated a number of leash designs and chemistries, including mixed backbone oligonucleotides, and their ability to influence delivery and efficacy of the morpholino AO. Significantly, we detected dystrophin protein synthesis and correct sarcolemmal localisation after intramuscular injection of morpholino AO : leash lipoplexes in mdx muscle in vivo. We show enhanced delivery of a morpholino AO, enabling the advantageous properties to be exploited for potentially therapeutic outcomes.

Alternative Splicing↗
PubMed2005

AMOD: a morpholino oligonucleotide selection tool.

AMOD is a web-based program that aids in the functional evaluation of nucleotide sequences through sequence characterization and antisense morpholino oligonucleotide (target site) selection. Submitted sequences are analyzed by translation initiation site prediction algorithms and sequence-to-sequence comparisons; results are used to characterize sequence features required for morpholino design. Within a defined subsequence, base composition and homodimerization values are computed for all putative morpholino oligonucleotides. Using these properties, morpholino candidates are selected and compared with genomic and transcriptome databases with the goal to identify target-specific enriched morpholinos. AMOD has been used at the University of Minnesota to design approximately 200 morpholinos for a functional genomics screen in zebrafish. The AMOD web server and a tutorial are freely available to both academic and commercial users at http://www.secretomes.umn.edu/AMOD/.

DNA Primers↗
PubMed2004

Evaluation of developmental phenotypes produced by morpholino antisense targeting of a sea urchin Runx gene.

BACKGROUND: Runx transcription factors are important regulators of metazoan development. The sea urchin Runx gene SpRunt was previously identified as a trans-activator of the CyIIIa actin gene, a differentiation marker of larval aboral ectoderm. Here we extend the functional analysis of SpRunt, using morpholino antisense oligonucleotides (morpholinos) to interfere with SpRunt expression in the embryo. RESULTS: The developmental effects of four different SpRunt-specific morpholinos were evaluated. The two morpholinos most effective at knocking down SpRunt produce an identical mitotic catastrophe phenotype at late cleavage stage that is an artifact of coincidental mis-targeting to histone mRNA, providing a cautionary example of the insufficiency of two different morpholinos as a control for specificity. The other two morpholinos produce gastrula stage proliferation and differentiation defects that are rescued by exogenous SpRunt mRNA. The expression of 22 genes involved in cell proliferation and differentiation was analyzed in the latter embryos by quantitative polymerase chain reaction. Knockdown of SpRunt was found to perturb the expression of differentiation markers in all of the major tissue territories as well as the expression of cell cycle control genes, including cyclin B and cyclin D. CONCLUSIONS: SpRunt is essential for embryonic development, and is required globally to coordinate cell proliferation and differentiation.

Animals↗
PubMed2001

Achieving efficient delivery of morpholino oligos in cultured cells.

One of the many features that make morpholino oligos unique among the antisense structural types is an uncharged backbone. While this feature eliminates the nonspecific interactions of traditional S-oligos, it also renders the morpholino undeliverable via the traditional lipid-based delivery systems. This article describes a highly efficient method of delivering morpholino oligos into adherent and nonadherent cultured cells. In this system, a nonionic morpholino oligo is paired to a complementary DNA "carrier." The DNA is then bound electrostatically to a partially ionized, weakly-basic ethoxylated polyethylenimine (EPEI). This morpholino/DNA/EPEI complex is efficiently endocytosed, and when the pH drops within the endosome, the EPEI more fully ionizes, resulting in permeabilization of the endosomal membrane and release of the morpholino into the cytosol. This article describes optimization of delivery in HeLa cells and provides the basis for delivery in any cultured endocytic cell type. genesis 30:94--102, 2001.

Base Sequence↗
PubMed2000

Pyrimidine morpholino oligonucleotides form a stable triple helix in the absence of magnesium ions.

Oligonucleotides can be used as sequence-specific DNA ligands by forming a local triple helix. In order to form more stable triple-helical structures or prevent their degradation in cells, oligonucleotide analogues that are modified at either the backbone or base level are routinely used. Morpholino oligonucleotides appeared recently as a promising modification for antisense applications. We report here a study that indicates the possibility of a triple helix formation with a morpholino pyrimidine TFO and its comparison with a phosphodiester and a phosphoramidate oligonucleotide. At a neutral pH and in the presence of a high magnesium ion concentration (10 mM), the phosphoramidate oligomer forms the most stable triple helix, whereas in the absence of magnesium ion but at a physiological monovalent cation concentration (0.14 M) only morpholino oligonucleotides form a stable triplex. To our knowledge, this is the first report of a stable triple helix in the pyrimidine motif formed by a noncharged oligonucleotide third strand (the morpholino oligonucleotide) and a DNA duplex. We show here that the structure formed with the morpholino oligomer is a bona fide triple helix and it is destabilized by high concentrations of potassium ions or divalent cations (Mg(2+)).

Base Sequence↗
PubMed2003

A potent and specific morpholino antisense inhibitor of hepatitis C translation in mice.

Hepatitis C virus (HCV) is an RNA virus infecting one in every 40 people worldwide. Current treatments are ineffective and HCV is the leading cause of liver failure leading to transplantation in the United States and Europe. Translational control of HCV is a prime therapeutic target. We assessed the inhibitory potential of morpholino phosphoramidate antisense oligonucleotides (morpholinos) on HCV translation by codelivering them with reporter plasmids expressing firefly luciferase under the translational control of the HCV internal ribosome entry site (IRES) into the livers of mice. Real-time imaging of HCV IRES luciferase reporter messenger RNA (mRNA) translation in living mice showed that a 20-mer complementary to nucleotides 345-365 of the IRES inhibited translation by greater than 95% for at least 6 days and showed mismatch specificity. No significant nonspecific inhibition of a cap-dependent luciferase or encephalomyocarditis virus (EMCV) IRES luciferase reporter translation was observed. Inhibition by the 20-mer morpholino was dose dependent, with 1 nmol/mouse giving the highest inhibition. In conclusion, morpholino antisense oligonucleotides are potent inhibitors of HCV IRES translation in a preclinical mouse model; morpholinos have potential as molecular therapeutics for treating HCV and other viral infections. The in vivo model described is a broadly applicable, straightforward, and rapid readout for inhibitor efficacy. As such, it will greatly facilitate the development of novel therapeutic strategies for viral hepatitis. Notably, the level of antisense inhibition observed in this in vivo model is similar to the maximal inhibition we have obtained previously with RNA interference in mice.

Animals↗
PubMed1997

Morpholino and phosphorothioate antisense oligomers compared in cell-free and in-cell systems.

Morpholino and phosphorothioate (S-DNA) antisense oligos were compared in both cell-free and in-cell translation systems. In the most stringent test of specificity in the cell-free system, a globin-targeted S-DNA oligo was found to inhibit its target sequence at concentrations of 10 nM and above, but the sequence-specific component of this inhibition dropped below 50% at concentrations of 100 nM and above. A corresponding Morpholino oligo achieved even higher inhibition at 10 nM, but in contrast to the S-DNA, with the Morpholino, the sequence-specific component of this inhibition remained above 93% at a concentration of 3000 nM. In this same cell-free test system, several S-DNA oligos exhibited substantial undesired nonantisense effects at concentrations of 300 nM and above, whereas corresponding Morpholino oligos exhibited little or no nonantisense activity through a concentration of 3000 nM. In scrape-loaded HeLa cells, both globin-targeted and HBV-targeted S-DNAs (both antisense and control oligos) generally failed to achieve significant translational inhibition at extracellular concentrations up to 3000 nM. In contrast, the Morpholino oligos achieved effective and specific translational inhibition at extracellular concentrations ranging from 30 nM to 3000 nM.

Animals↗
PubMed1986

Morpholino derivatives of benzyl-benzodioxole, a study of structural requirements for drug interactions at the colchicine/podophyllotoxin binding site of tubulin.

We performed a structure-activity evaluation of the effects of methoxy substituents in the benzyl moiety of a series of morpholinyl Mannich base derivatives of 6-benzyl-1,3-benzodioxol-5-ol ("morpholino compounds") on the ability of these compounds to inhibit tubulin polymerization in vitro. Structurally these agents are most similar to the natural product podophyllotoxin and, like podophyllotoxin, they inhibited in vitro tubulin polymerization, tubulin-dependent GTP hydrolysis, and the binding of colchicine to tubulin. The benzyl ring (C ring) of these compounds appeared to be analogous to the trimethoxybenzene ring (E ring) of podophyllotoxin (with its methoxy substituents at the 3', 4' and 5' positions), but the morpholino compound superficially most similar to podophyllotoxin (with 3', 4' and 5' methoxy substituents) was the least active in the series. The most potent methoxy-substituted morpholino compounds bear these substituents either at the 2' and 4' positions (NSC 370277) or at the 2', 4' and 6' positions (NSC 381577). NSC 370277 and NSC 381577 were essentially identical in their inhibitory effects on tubulin polymerization, but the latter compound was considerably more effective as an inhibitor of the binding of colchicine to tubulin. The most active of the monomethoxy substituted compounds bore this group at position 4'. A number of compounds with alternative substituents at this position (in particular, alkyl-substituted amines) also had significant in vitro inhibitory effects on tubulin polymerization. Although the morpholino compounds appear to possess only limited cytotoxicity, these findings suggest possible modifications of the antimitotic benzyl-benzodioxole compounds described previously [Batra et al., Molec. Pharmac. 27, 94 (1985)] to enhance their antineoplastic activity.

Benzyl Compounds↗