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Won Jong Kim

Publications and source records attributed to Won Jong Kim.

13 recordsLinked to original sources
PubMed2006

Hypoxia-inducible gene expression system using the erythropoietin enhancer and 3'-untranslated region for the VEGF gene therapy.

Gene therapy with the vascular endothelial growth factor (VEGF) gene is a potential treatment for many disorders or injuries with ischemia. However, unregulated expression of VEGF may induce pathological angiogenesis, promoting tumor growth, diabetic proliferative retinopathy and rupture of atherosclerotic plaque. Therefore, the effective regulation of the gene expression is one of the requirements for the VEGF gene therapy. In this research, we evaluated the hypoxia-inducible gene expression system with the erythropoietin (Epo) enhancer and the Epo 3'-untranslated region (UTR). The luciferase plasmids were constructed with the Epo enhancer (pEpo-SV-Luc), the Epo 3'-UTR (pSV-Luc-EpoUTR) or both (pEpo-SV-Luc-EpoUTR). The polyethylenimine/plasmid complexes were transfected to 293 or A7R5 cells and the cells were incubated under normoxia or hypoxia. The results showed that the Epo enhancer or Epo 3'-UTR increased the target gene expression under hypoxia. pEpo-SV-Luc-EpoUTR showed the highest luciferase expression. The VEGF expression plasmid with the Epo enhancer and 3'-UTR was also constructed. The VEGF expression by pEpo-SV-VEGF-EpoUTR showed the highest specificity of the gene expression in the hypoxic cells. The results suggest that the VEGF plasmid with the Epo enhancer and the Epo 3'-UTR may be useful for gene therapy for ischemic diseases.

3' Untranslated Regions↗
PubMed2006

Cholesteryl oligoarginine delivering vascular endothelial growth factor siRNA effectively inhibits tumor growth in colon adenocarcinoma.

Vascular endothelial growth factor (VEGF) is a multifunctional angiogenic growth factor that is a primary stimulant of the development and maintenance of a vascular network in the vascularization of solid tumors. It has been reported that a blockade of VEGF-mediated angiogenesis is a powerful method for tumor regression. RNA interference represents a naturally occurring biological strategy for inhibition of gene expression. In mammalian systems, however, the in vivo application of small interfering RNA (siRNA) is severely limited by the instability and poor bioavailability of unmodified siRNA molecules. In this study, we tested the hypothesis that a hydrophobically modified protein transduction domain, cholesteryl oligo-d-arginine (Chol-R9), may stabilize and enhance tumor regression efficacy of the VEGF-targeting siRNA. The noncovalent complexation of a synthetic siRNA with Chol-R9 efficiently delivered siRNA into cells in vitro. Moreover, in a mouse model bearing a subcutaneous tumor, the local administration of complexed VEGF-targeting siRNA, but not of scrambled siRNA, led to the regression of the tumor. Hence, we propose a novel and simple system for the local in vivo application of siRNA through Chol-R9 for cancer therapy.

Adenocarcinoma↗
PubMed2006

Anti-angiogenic inhibition of tumor growth by systemic delivery of PEI-g-PEG-RGD/pCMV-sFlt-1 complexes in tumor-bearing mice.

Vascular endothelial growth factor (VEGF) is an endogenous mediator of tumor angiogenesis. Blocking associations of the VEGF with its corresponding receptors (Flt-1, KDR/flk-1) have become critical for anti-tumor angiogenesis therapy. Previously, we synthesized PEI-g-PEG-RGD conjugate and evaluated as an angiogenic endothelial polymeric gene carrier. In this study, PEI-g-PEG-RGD/pCMV-sFlt-1 complexes are evaluated in terms of tumor growth inhibition in vivo. Complexes were repeatedly injected systemically via tail vein into subcutaneous tumor-bearing mice. As a result, tumor growth was inhibited in the PEI-g-PEG-RGD/pCMV-sFlt-1 injected group. However, this effect was not identified in PEI-g-PEG/pCMV-sFlt-1 or PEI-g-PEG-RGD/pCMV-GFP control groups. Moreover, the survival rate increased in the PEI-g-PEG-RGD/pCMV-sFlt-1 group compared with the controls group. These results suggest that delivery of pCMV-sFlt-1 using PEG-g-PEG-RGD may be effective for anti-angiogenic gene therapy.

Angiogenesis Inhibitors↗
PubMed2005

Anti-GAD antibody targeted non-viral gene delivery to islet beta cells.

An islet cell targeting polymeric gene carrier was synthesized by conjugating anti-GAD Fab' fragment to PEI via PEG linker (PEI-PEG-Fab'). The Fab' fragment was prepared from a murine monoclonal antibody against glutamic acid decarboxylase (GAD), which has been identified as one of the major auto-antigens expressed in islet cells, and used as a targeting moiety for islet cell targeting. The electrophoretic migration of plasmid DNA (pCMVLuc)/PEI-PEG-Fab' complexes in agarose gel was completely retarded above the N/P ratio of 2. The complexes demonstrated a size of 100-275 nm with an almost neutral surface charge. Confocal microscopy revealed that the PEI-PEG-Fab' complexes showed much higher cellular binding and uptake efficiency compared to PEI-PEG complexes. The PEI-PEG-Fab' showed about 10-fold higher transfection efficiency (relative luciferase activity) than PEI-PEG in GAD-expressing mouse insulinoma cells (MIN6), however the transfection efficiency of PEI-PEG-Fab' reduced to that of PEI-PEG in GAD negative cells (293) and in the presence of competitive free Fab'. Considering the neutral surface charge of its complexes with DNA, and selectivity toward the islet cells expressing a specific antigen, the PEI-PEG-Fab' conjugate could be thought as a potential candidate of the systemic gene therapy for the treatment of type I diabetes.

Animals↗
PubMed2005

Soluble Flt-1 gene delivery using PEI-g-PEG-RGD conjugate for anti-angiogenesis.

Vascular endothelial growth factor (VEGF), a potent angiogenic molecule specific for vascular endothelial cells, is overexpressed in most tumors and closely associated with tumor growth and metastasis. It has been shown that a soluble fragment of VEGF receptor Flt-1 (sFlt-1) has anti-angiogenic properties by way of its antagonist activity against VEGF. In the present study, we demonstrated that the stable expression of sFlt-1 by endothelial cell targeted non-viral gene delivery inhibited the angiogenesis of endothelial cells. A targeted polymeric gene delivery system, PEI-g-PEG-RGD, was developed by incorporating the alphanubeta3/alphanubeta5 integrin-binding RGD peptide, ACDCRGDCFC (single-letter amino acid code), into the cationic polymer, polyethylenimine (PEI) via a hydrophilic polyethylene glycol (PEG) spacer. The functional analysis of therapeutic gene encoding sFlt-1/carrier complex was performed with an endothelial cell proliferation assay. The complex of sFlt-1 gene with PEI-g-PEG-RGD conjugate efficiently inhibited the proliferation of cultured endothelial cells, representing that expressed sFlt-1 predominantly bound to exogenous VEGF and blocked the binding of VEGF to the full-length Flt-1 receptor. These findings suggest that the combination of targeted gene carrier and sFlt-1 possesses the potential to be an efficient tool for the anti-angiogenic gene therapy to treat cancer.

Angiogenesis Inhibitors↗
PubMed2003

Cationic comb-type copolymers for DNA analysis.

Genetic diagnoses, such as single nucleotide polymorphism (SNP) typing, allow elucidation of gene-based physiological differences, such as susceptibility to diseases and response to drugs, among individuals. Many detection technologies, including allele-specific hybridization, allele-specific primer extension and oligonucleotide ligation, are being used to discriminate SNP alleles. These methods still have many unsolved practical issues. In general they require adequate and specific hybridizations of primer or probe DNAs with target DNAs. This frequently needs optimization of the probe/primer structures and operating conditions. In nature, highly homology-sensitive hybridization is assisted by a nucleic acid chaperone that reduces the energy barrier associated with breakage and reassociation of nucleic base pairs. Here we report a simple, quick, precise but enzyme-free method for SNP analysis. The method uses cationic comb-type copolymers (CCCs) producing high nucleic acid chaperone activities. A single-base mismatch in 20-mer DNA can be detected within a few minutes at ambient temperatures (25-37 degrees C). Even without careful optimization processes, the method has the sensitivity to detect the mismatches causing subtle changes (Delta T(m) equals approximately 1 degree C) in duplex thermal stability. CCCs may have various bioanalytical applications where precise hybridization of nucleic acids is needed.

Aryl Hydrocarbon Hydroxylases↗
PubMed2003

Design of artificial nucleic acid chaperones for DNA engineering.

We have shown that the comb-type copolymer consisting of a polycation backbone and hydrophilic side chains stabilizes DNA hybrids. Furthermore, the copolymers showed the activity to accelerate DNA strand exchange reactions between double helical DNA and its complementary DNA. The copolymer was considered to stimulate breakage and reassociation of base pairing and act as an artificial nucleic acid chaperone. The polymer's chaperoning activity was elaborated for rapid and precise judging of a subtle difference in DNA sequences. One base alternation out of 20mer DNA was quickly detected by the strand exchange assay employing the copolymer. From these, we conclude that the copolymer would be a useful material in DNA engineering that employs rapid and precise DNA folding.

Biopolymers↗
PubMed2003

Polycation-accelerated strand exchange (PASE) for SNPs typing.

In the previous study (Chem. Eur. J., 7, 176 (2001), J. Am. Chem. Soc., 124, 12676 (2002)), we demonstrated that the cationic comb-type copolymer (PLL-g-Dex, CCC) composed of a cationic poly(L-lysine) backbone and water-soluble side chains of dextran accelerated the DNA strand exchange reaction between double helical DNA and its homologous single strand. In this study, Polycation-Accelerated Strand Exchange (PASE) assay was applied to discriminate single-base mismatch in DNA sequence such as single nucleotide polymorphisms (SNPs). We could discriminate the 20mer DNA with a single-base mismatch from the full matched DNA with high efficacy by PASE.

Base Pair Mismatch↗
PubMed2002

DNA strand exchange stimulated by spontaneous complex formation with cationic comb-type copolymer.

Cationic comb-type copolymers (CCCs) composed of a polycation backbone and water-soluble side chains accelerate by 4-5 orders the DNA strand exchange reaction (SER) between double helical DNA and its homologous single-strand DNA. The accelerating effect is considered due to alleviation of counterion association during transitional intermediate formation in sequential displacement pathway. CCCs stabilize not only matured hybrids but also the nucleation complex to accelerate hybridization.

Cations↗
PubMed2002

Investigation of DNA strand exchange mechanisms mediated by cationic polymers.

It was observed that conjugation of dextran for PLL provided PLL-g-Dex with new properties of enhancing and accelerating inter-nucleotide recognition (1, 2, 3). In this paper, we report the effects of cationic PLL-g-Dex copolymers on base-pair formation of self-complementary octamer oligonucleotide by using NMR and CD analysis. NMR studies revealed that PLL-g-Dex copolymer did not affect hydrogen-bondings between bases in DNA duplex. CD studies also supported inert nature of the copolymer upon hybrid structure.

Base Sequence↗
PubMed2002

Enhancement in the cleavage activity of a hammerhead ribozyme by cationic comb-type polymers and an RNA helicase in vitro.

The activity of a hammerhead ribozyme (Rz) in vivo depends on several factors, such as abundance, stability, and accessibility of Rz to its target mRNA. Among these factors, accessibility is believed to be the rate-limiting factor for Rz-mediated cleavage in vivo. As Rz and its substrate RNA are negatively charged, we examined whether cellular RNA-interacting proteins or artificial polycations might improve the accessibility of Rz to its substrate RNA. Specifically, we examined the effects of two kinds of cationic comb-type copolymer, alphaPLL-g-Dex, and a cellular RNA helicase on the accessibility of Rz to a model structured RNA in vitro. The cleavage activity of Rz was slightly enhanced by alphaPLL-g-Dex, probably due to an acceleration of the association/dissociation rate. And also, the RNA helicase-bound hybrid-Rz could cleave the target substrate at a significantly higher rate due to its unwinding activity for the duplex RNA substrate. These approaches should be useful in the development of efficient gene-inactivating reagents in the post-genomic era.

Base Sequence↗
PubMedDate not supplied

Reducible poly(amido ethylenimine)s designed for triggered intracellular gene delivery.

Poly(amido ethylenimine) polymers, a new type of peptidomimetic polymer, containing multiple disulfide bonds (SS-PAEIs) designed to degrade after delivery of plasmid DNA (pDNA) into the cell were synthesized and investigated as new carriers for triggered intracellular gene delivery. More specifically, three SS-PAEIs were synthesized from Michael addition reactions between cystamine bisacrylamide (CBA) and three different ethylene amine monomers, i.e., ethylenediamine (EDA), diethylenetriamine (DETA), or triethylenetetramine (TETA). Complete addition reactions were confirmed by (1)H NMR. The molecular weight, buffer capacity, and relative degree of branching for each SS-PAEI was determined by gel permeation chromatography (GPC), acid-base titration, and liquid chromatography-mass spectroscopy (LC-MS), respectively. Physicochemical characteristics of polymer/pDNA complexes (polyplexes) were analyzed by gel electrophoresis, particle size, and zeta-potential measurements. All three SS-PAEIs effectively complex pDNA to form nanoparticles with diameters less than 200 nm and positive surface charges of approximately 32 mV. The in vitro gene transfer properties of SS-PAEIs were evaluated using mouse embryonic fibroblast cell (NIH3T3), primary bovine aortic endothelial cell (BAEC), and rat aortic smooth muscle cell (A7R5) lines. Interestingly, polyplexes based on all three SS-PAEIs exhibited remarkably high levels of reporter gene expression with nearly 20x higher transfection efficiency than polyethylenimine 25k. The high transfection efficiency was maintained in the presence of 10% serum in the transfection medium. Furthermore, confocal microscopy experiments using labeled pDNA indicated that polyplexes of SS-PAEI displayed greater intracellular distribution of pDNA as compared to PEI, most likely due to environmentally triggered release. Therefore, SS-PAEIs are a new class of transfection agents that facilitate high gene expression while maintaining a low level of toxicity.

Amides↗