105 results on '"Kwon NH"'
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2. Surface Optimization of Noble-Metal-Free Conductive [Mn 1/4 Co 1/2 Ni 1/4 ]O 2 Nanosheets for Boosting Their Efficacy as Hybridization Matrices.
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Kwon NH, Kim SJ, Gu TH, Lee JM, Kim MH, Paik D, Jin X, Kim H, and Hwang SJ
- Abstract
Conductive 2D nanosheets have evoked tremendous scientific efforts because of their high efficiency as hybridization matrices for improving diverse functionalities of nanostructured materials. To address the problems posed by previously reported conductive nanosheets like poorly-interacting graphene and cost-ineffective RuO
2 nanosheets, economically feasible noble-metal-free conductive [Mnx Co1-2x Nix ]O2 oxide nanosheets are synthesized with outstanding interfacial interaction capability. The surface-optimized [Mn1/4 Co1/2 Ni1/4 ]O2 nanosheets outperformed RuO2 /graphene nanosheets as hybridization matrices in exploring high-performance visible-light-active (λ >420 nm) photocatalysts. The most efficient g-C3 N4 -[Mn1/4 Co1/2 Ni1/4 ]O2 nanohybrid exhibited unusually high photocatalytic activity (NH4 + formation rate: 1.2 mmol g-1 h-1 ), i.e., one of the highest N2 reduction efficiencies. The outstanding hybridization effect of the defective [Mn1/4 Co1/2 Ni1/4 ]O2 nanosheets is attributed to the optimization of surface bonding character and electronic structure, allowing for improved interfacial coordination bonding with g-C3 N4 at the defect sites. Results from spectroscopic measurements and theoretical calculations reveal that hybridization helps optimize the bandgap energy, and improves charge separation, N2 adsorptivity, and surface reactivity. The universality of the [Mn1/4 Co1/2 Ni1/4 ]O2 nanosheet as versatile hybridization matrices is corroborated by the improvement in the electrocatalytic activity of hybridized Co-Fe-LDH as well as the photocatalytic hydrogen production ability of hybridized CdS., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)- Published
- 2024
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3. The InterVision Framework: An Enhanced Fine-Tuning Deep Learning Strategy for Auto-Segmentation in Head and Neck.
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Choi B, Beltran CJ, Yoo SK, Kwon NH, Kim JS, and Park JC
- Abstract
Adaptive radiotherapy (ART) workflows are increasingly adopted to achieve dose escalation and tissue sparing under dynamic anatomical conditions. However, recontouring and time constraints hinder the implementation of real-time ART workflows. Various auto-segmentation methods, including deformable image registration, atlas-based segmentation, and deep learning-based segmentation (DLS), have been developed to address these challenges. Despite the potential of DLS methods, clinical implementation remains difficult due to the need for large, high-quality datasets to ensure model generalizability. This study introduces an InterVision framework for segmentation. The InterVision framework can interpolate or create intermediate visuals between existing images to generate specific patient characteristics. The InterVision model is trained in two steps: (1) generating a general model using the dataset, and (2) tuning the general model using the dataset generated from the InterVision framework. The InterVision framework generates intermediate images between existing patient image slides using deformable vectors, effectively capturing unique patient characteristics. By creating a more comprehensive dataset that reflects these individual characteristics, the InterVision model demonstrates the ability to produce more accurate contours compared to general models. Models are evaluated using the volumetric dice similarity coefficient (VDSC) and the Hausdorff distance 95% (HD95%) for 18 structures in 20 test patients. As a result, the Dice score was 0.81 ± 0.05 for the general model, 0.82 ± 0.04 for the general fine-tuning model, and 0.85 ± 0.03 for the InterVision model. The Hausdorff distance was 3.06 ± 1.13 for the general model, 2.81 ± 0.77 for the general fine-tuning model, and 2.52 ± 0.50 for the InterVision model. The InterVision model showed the best performance compared to the general model. The InterVision framework presents a versatile approach adaptable to various tasks where prior information is accessible, such as in ART settings. This capability is particularly valuable for accurately predicting complex organs and targets that pose challenges for traditional deep learning algorithms.
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- 2024
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4. Assessment of radio-activation using spectroscopy in medical linear accelerators.
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Kwon NH, Jang YJ, Yu S, Lee H, Choi DH, Ahn SH, Kim KB, Kim JS, Kim DW, and Choi SH
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- Humans, Radiotherapy Dosage, Particle Accelerators, Photons, Spectrum Analysis, Radioisotopes, Manganese
- Abstract
In radiotherapy, when photon energy exceeding 8 MV is utilized, photoneutrons can activate the components within the gantry of the linear accelerator (linac). At the end of the linac's lifecycle, radiation workers are tasked with its dismantling and disposal, potentially exposing them to unintentional radiation. This study aims to identify and measure the radioisotopes generated by this activation through spectroscopy, and to evaluate the effective dose rate. We selected nine medical linacs, considering various factors such as manufacturer (Siemens, Varian, and Elekta), model, energy, period of operation, and workload. We identified the radionuclides in the linac head by employing an in situ high-purity germanium (HPGe) detector. Spectroscopy and dose-rate measurements were conducted post-shutdown. We also measured the dose rates at the beam-exit window following irradiation with 10 MV and 15 MV photon beams. As a result of the spectroscopy, we identified approximately 20 nuclides including those with half-lives of 100 days or longer, such as 54Mn, 60Co, 65Zn, 122Sb, and 198Au. The dose rate measurements after 10 MV irradiation decreased to the background level in 10 min. By contrast, on 15 MV irradiation, the dose rate was 628 nSv/h after 10 min and decreased to 268 nSv/h after 1.5 hours. It was confirmed that the difference in the level of radiation and the type of nuclide depends on the period of use, energy, and workload. However, the type of nuclide does not differ significantly between the linacs. It is necessary to propose appropriate guidelines for the safety of workers, and disposal/move-install should be planned while taking into consideration the equipment's energy usage rate., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Kwon et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)
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- 2024
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5. Enhanced therapeutic potential of antibody fragment via IEDDA-mediated site-specific albumin conjugation.
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Go EB, Lee JH, Cho JH, Kwon NH, Choi JI, and Kwon I
- Abstract
Background: The use of single-chain variable fragments (scFvs) for treating human diseases, such as cancer and immune system disorders, has attracted significant attention. However, a critical drawback of scFv is its extremely short serum half-life, which limits its therapeutic potential. Thus, there is a critical need to prolong the serum half-life of the scFv for clinical applications. One promising serum half-life extender for therapeutic proteins is human serum albumin (HSA), which is the most abundant protein in human serum, known to have an exceptionally long serum half-life. However, conjugating a macromolecular half-life extender to a small protein, such as scFv, often results in a significant loss of its critical properties., Results: In this study, we conjugated the HSA to a permissive site of scFv to improve pharmacokinetic profiles. To ensure minimal damage to the antigen-binding capacity of scFv upon HSA conjugation, we employed a site-specific conjugation approach using a heterobifunctional crosslinker that facilitates thiol-maleimide reaction and inverse electron-demand Diels-Alder reaction (IEDDA). As a model protein, we selected 4D5scFv, derived from trastuzumab, a therapeutic antibody used in human epithermal growth factor 2 (HER2)-positive breast cancer treatment. We introduced a phenylalanine analog containing a very reactive tetrazine group (frTet) at conjugation site candidates predicted by computational methods. Using the linker TCO-PEG4-MAL, a single HSA molecule was site-specifically conjugated to the 4D5scFv (4D5scFv-HSA). The 4D5scFv-HSA conjugate exhibited HER2 binding affinity comparable to that of unmodified 4D5scFv. Furthermore, in pharmacokinetic profile in mice, the serum half-life of 4D5scFv-HSA was approximately 12 h, which is 85 times longer than that of 4D5scFv., Conclusions: The antigen binding results and pharmacokinetic profile of 4D5scFv-HSA demonstrate that the site-specifically albumin-conjugated scFv retained its binding affinity with a prolonged serum half-life. In conclusion, we developed an effective strategy to prepare site-specifically albumin-conjugated 4D5scFv, which can have versatile clinical applications with improved efficacy., (© 2024. The Author(s).)
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- 2024
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6. Enhancing Hydrogen Evolution Reaction Activity of Palladium Catalyst by Immobilization on MXene Nanosheets.
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Sun Y, Lee J, Kwon NH, Lim J, Jin X, Gogotsi Y, and Hwang SJ
- Abstract
Efficient catalysts with minimal content of catalytically active noble metals are essential for the transition to the clean hydrogen economy. Catalyst supports that can immobilize and stabilize catalytic nanoparticles and facilitate the supply of electrons and reactants to the catalysts are needed. Being hydrophilic and more conductive compared with carbons, MXenes have shown promise as catalyst supports. However, the controlled assembly of their 2D sheets creates a challenge. This study established a lattice engineering approach to regulate the assembly of exfoliated Ti
3 C2 Tx MXene nanosheets with guest cations of various sizes. The enlargement of guest cations led to a decreased interlayer interaction of MXene lamellae and increased surface accessibility, allowing intercalation of Pd nanoparticles. Stabilization of Pd nanoparticles between interlayer-expanded MXene nanosheets improved their electrocatalytic activity. The Pd-immobilized K+ -intercalated MXene nanosheets (PdKMX) demonstrated exceptional electrocatalytic performance for the hydrogen evolution reaction with the lowest overpotential of 72 mV (@10 mA cm-2 ) and the highest turnover frequency of 1.122 s-1 (@ an overpotential of 100 mV), which were superior to those of the state-of-the-art Pd nanoparticle-based electrocatalysts. Weakening of the interlayer interaction during self-assembly with K+ ions led to fewer layers in lamellae and expansion of the MXene in the c direction during Pd anchoring, providing numerous surface-active sites and promoting mass transport. In situ spectroscopic analysis suggests that the effective interfacial electron injection from the Pd nanoparticles strongly immobilized on interlayer-expanded PdKMX may be responsible for the improved electrocatalytic performance.- Published
- 2024
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7. Enhanced anti-tumor activity of arginine decarboxylase through the incorporation of aromatic amino acids at the multimer-forming interface.
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Park MY, Kim S, Kwon NH, Moon G, Cha J, and Kwon I
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- Amino Acids metabolism, Tyrosine, Phenylalanine, Arginine, Tryptophan chemistry, Amino Acids, Aromatic, Carboxy-Lyases
- Abstract
The pressing challenge of cancer's high mortality and invasiveness demands improved therapeutic approaches. Targeting the nutrient dependencies within cancer cells has emerged as a promising approach. This study is dedicated to demonstrating the potential of arginine depletion for cancer treatment. Notably, the focus centers on arginine decarboxylase (RDC), a pH-dependent enzyme expecting enhanced activity within the slightly acidic microenvironments of tumors. To investigate the effect of a single-site mutation on the catalytic efficacy of RDC, diverse amino acids, including glycine, alanine, phenylalanine, tyrosine, tryptophan, p-azido-phenylalanine, and a phenylalanine analog with a hydrogen-substituted tetrazine, were introduced at the crucial threonine site (position 39) in the multimer-forming interface. Remarkably, the introduction of either a natural or a non-natural aromatic amino acid at position 39 substantially boosted enzymatic activity, while amino acids with smaller side chains did not show the same effect. This enhanced enzymatic activity is likely attributed to the reinforced formation of multimer structures through favorable interactions between the introduced aromatic amino acid and the neighboring subunit. Noteworthy, at slightly acidic pH, the RDC variant featuring tryptophan at position 39 demonstrated augmented cytotoxicity against tumor cells compared to the wild-type RDC. This attribute aligns with the tumor microenvironment and positions these variants as potential candidates for targeted cancer therapy., (© 2023 Wiley-VCH GmbH.)
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- 2024
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8. Defect-Regulated Two-Dimensional Superlattice of Holey g-C 3 N 4 - TiO 2 Nanohybrids: Contrasting Influence of Vacancy Content on Hybridization Impact and Photocatalyst Performance.
- Author
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Kwon NH, Park J, Jin X, Kim SJ, Kim H, and Hwang SJ
- Abstract
Defect engineering provides an effective way to explore efficient nanostructured catalysts. Herein, we synthesize defect-regulated two-dimensional superlattices comprising interstratified holey g-C
3 N4 and TiO2 monolayers with tailorable interfacial coupling. Using this interfacial-coupling-controlled hybrid system, a strong interdependence among vacancy content, performance, and interfacial coupling was elucidated, offering key insights for the design of high-performance catalysts. The defect-optimized g-C3 N4 -TiO2 superlattice exhibited higher photocatalytic activity toward visible-light-induced N2 fixation (∼1.06 mmol g-1 h-1 ) than defect-unoptimized and disorderly assembled g-C3 N4 -TiO2 homologues. The high photocatalytic performance of g-C3 N4 -TiO2 was attributed to the hybridization-induced defect creation, facilitated hydrogenation of adsorbed nitrogen, and improvement in N2 adsorption and charge transport. A comparison of the defect-dependent photocatalytic activity of g-C3 N4 , g-C3 N4 nanosheets, and g-C3 N4 -TiO2 revealed the presence of optimal defect content for improving photocatalytic performance and the continuous increase of hybridization impact with the defect content. Sophisticated mutual influence among defect, electronic coupling, and photocatalytic ability underscores the importance of defect fine control in exploring high-performance hybrid photocatalysts. Along with the DFT calculation, the excellent photocatalyst performance of defect-optimized g-C3 N4 -TiO2 can be ascribed to the promotion of the uphill *N hydrogenation step as well as to enhancement of N2 adsorption, charge transfer kinetics, and mass transports.- Published
- 2023
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9. Uncertainty Evaluation for the Quantification of Urinary Amphetamine and 4-Hydroxyamphetamine Using Liquid Chromatography-Tandem Mass Spectrometry: Comparison of the Guide to the Expression of Uncertainty in Measurement Approach and the Monte Carlo Method with R.
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Kim SY, Shin DW, Hyun J, Kwon NH, Cheong JC, Paeng KJ, Lee J, and Kim JY
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- Chromatography, Liquid methods, Uncertainty, Monte Carlo Method, p-Hydroxyamphetamine, Tandem Mass Spectrometry methods
- Abstract
Estimating the measurement uncertainty (MU) is becoming increasingly mandatory in analytical toxicology. This study evaluates the uncertainty in the quantitative determination of urinary amphetamine (AP) and 4-hydroxyamphetamine (4HA) using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method based on the dilute-and-shoot approach. Urine sample dilution, preparation of calibrators, calibration curve, and method repeatability were identified as the sources of uncertainty. To evaluate the MU, the Guide to the Expression of Uncertainty in Measurement (GUM) approach and the Monte Carlo method (MCM) were compared using the R programming language. The MCM afforded a smaller coverage interval for both AP (94.83, 104.74) and 4HA (10.52, 12.14) than that produced by the GUM (AP (92.06, 107.41) and 4HA (10.21, 12.45)). The GUM approach offers an underestimated coverage interval for Type A evaluation, whereas the MCM provides an exact coverage interval under an abnormal probability distribution of the measurand. The MCM is useful in complex settings where the measurand is combined with numerous distributions because it is generated from the uncertainties of input quantities based on the propagation of the distribution. Therefore, the MCM is more practical than the GUM for evaluating the MU of urinary AP and 4HA concentrations using LC-MS/MS.
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- 2023
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10. Super Proton Conductivity Through Control of Hydrogen-Bonding Networks in Flexible Metal-Organic Frameworks.
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Kwon NH, Han S, Kim J, and Cho ES
- Abstract
Metal-organic frameworks (MOFs) have received much attention as a solid-state electrolyte in proton exchange membrane fuel cells. The introduction of proton carriers and functional groups into MOFs can improve the proton conductivity attributed to the formation of hydrogen-bonding networks, while the underlying synergistic mechanism is still unclear. Here, a series of flexible MOFs (MIL-88B, [Fe
3 O(OH)(H2 O)2 (O2 C-C6 H4 -CO2 )3 ] with imidazole) is designed to modify the hydrogen-bonding networks and investigate the resulting proton-conducting characteristics by controlling the breathing behaviors. The breathing behavior is tuned by varying the amount of adsorbed imidazole into pore (small breathing (SB) and large breathing (LB)) and introducing functional groups onto ligands (-NH2 , -SO3 H), resulting in four kinds of imidazole-loaded MOFs-Im@MIL-88B-SB, Im@MIL-88B-LB, Im@MIL-88B-NH2 , and Im@MIL-88B-SO3 H. Im@MIL-88B-LB without functional groups exhibits the highest proton conductivity of 8.93 × 10-2 S cm-1 at 60 °C and 95% relative humidity among imidazole-loaded proton conductors despite the mild condition, indicating that functional groups may not be always required to enhance proton conductivity. The elaborately controlled pore size and host-guest interaction in flexible MOFs through imidazole-dependent structural transformation are translated into the high proton concentration without the limitation of proton mobility, contributing to the formation of effective hydrogen-bonding networks in imidazole conducting media., (© 2023 Wiley-VCH GmbH.)- Published
- 2023
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11. Demonstration of high-accuracy 3D imaging using a Si optical phased array with a tunable radiator.
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Yoon J, Yoon H, Kim JY, Kim J, Kang G, Kwon NH, Kurt H, and Park HH
- Abstract
Precise imaging in three-dimension (3D) is an essential technique for solid-state light detection and ranging (LiDAR). Among various solid-state LiDAR technologies, silicon (Si) optical phased array (OPA)-based LiDAR has the significant advantage of robust 3D imaging due to its high scanning speed, low power consumption, and compactness. Numerous techniques employing a Si OPA have utilized two-dimensional arrays or wavelength tuning for longitudinal scanning but the operation of those systems is restricted by additional requirements. Here, we demonstrate high-accuracy 3D imaging using a Si OPA with a tunable radiator. As we adapted a time-of-flight approach for distance measurement, we have developed an optical pulse modulator that allows a ranging accuracy of less than 2 cm. The implemented Si OPA is composed of an input grating coupler, multimode interferometers, electro-optic p-i-n phase shifters, and thermo-optic n-i-n tunable radiators. With this system, it is possible to attain a wide beam steering range of 45° in a transversal angle with a 0.7° divergence angle, and 10° in a longitudinal angle with a 0.6° divergence angle can be achieved using Si OPA. The character toy model was successfully imaged in three dimensions with a range resolution of 2 cm using the Si OPA. The further improvement of each component of the Si OPA will allow even more accurate 3D imaging over a longer distance.
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- 2023
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12. Demonstration of beam steering using a passive silica optical phased array with wavelength tuning.
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Kim JY, Yoon J, Kim J, Kwon NH, Rhee HW, Baek M, Lee Y, Park HH, and Yoon H
- Abstract
We demonstrate beam steering using a passive silica optical phased array (OPA) with wavelength tuning. In this OPA, a constant path difference is built up to assign sequential phase delays with a wavelength variation in arrayed waveguide channels for the beam steering. From as-fabricated 1 × 101 passive silica OPA chips, we successfully achieved beam forming with a transversal divergence angle of 0.57° at a 1548.3-nm wavelength and also beam steering of 15.4° by wavelength tuning of 30.7 nm. Combining a cylindrical lens in front of the end-fire radiators, the longitudinal divergence angle could be reduced from 13.0° to 0.42°. The side-mode suppression ratio of the beam was 10.3 dB at the center position. Through simulation, we analyzed the effects of the phase errors on the beam quality, due to the effective index fluctuation of the waveguide channels, and provided an allowable error range to attain beam forming from the passive OPA.
- Published
- 2022
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13. Computation-Aided Design of Albumin Affibody-Inserted Antibody Fragment for the Prolonged Serum Half-Life.
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Kwon NH, Lee JH, and Kwon I
- Abstract
Single-chain variable fragments (scFvs) have been recognized as promising agents in cancer therapy. However, short serum half-life of scFvs often limits clinical application. Fusion to albumin affibody (ABD) is an effective and convenient half-life extension strategy. Although one terminus of scFv is available for fusion of ABD, it is also frequently used for fusion of useful moieties such as small functional proteins, cytokines, or antibodies. Herein, we investigated the internal linker region for ABD fusion instead of terminal region, which was rarely explored before. We constructed two internally ABD-inserted anti-HER2 4D5scFv (4D5-ABD) variants, which have short (4D5-S-ABD) and long (4D5-L-ABD) linker length respectively. The model structures of these 4D5scFv and 4D5-ABD variants predicted using the deep learning-based protein structure prediction program (AlphaFold2) revealed high similarity to either the original 4D5scFv or the ABD structure, implying that the functionality would be retained. Designed 4D5-ABD variants were expressed in the bacterial expression system and characterized. Both 4D5-ABD variants showed anti-HER2 binding affinity comparable with 4D5scFv. Binding affinity of both 4D5-ABD variants against albumin was also comparable. In a pharmacokinetic study in mice, the 4D5-ABD variants showed a significantly prolonged half-life of 34 h, 114 times longer than that of 4D5scFv. In conclusion, we have developed a versatile scFv platform with enhanced pharmacokinetic profiles with an aid of deep learning-based structure prediction.
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- 2022
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14. Multilayer Conductive Hybrid Nanosheets as Versatile Hybridization Matrices for Optimizing the Defect Structure, Structural Ordering, and Energy-Functionality of Nanostructured Materials.
- Author
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Kwon NH, Jin X, Kim SJ, Kim H, and Hwang SJ
- Abstract
The hybridization of conductive nanospecies has garnered significant research interest because of its high efficacy in improving the diverse functionalities of nanostructured materials. In this study, a novel synthetic strategy is developed to optimize the defect structure, structural ordering, and energy-related functionality of nanostructured-materials by employing a multilayer multicomponent two-dimenstional (2D) graphene/metal oxide/graphene nanosheet (NS) as a versatile hybridization matrix. The hybridization of the robust trilayer, polydiallyldiammonium (PDDA)-anchored reduced-graphene oxide (prGO)/metal oxide/prGO NS effectively enhance the structural ordering and porosity of the hybridized MoS
2 /MnO2 NS through suppression of defect formation and tight stacking. In comparison with monolayer rGO/RuO2 NS-based homologs, the 2D superlattice trilayer prGO/RuO2 /prGO NS hybrids deliver better functionalities as a hydrogen evolution electrocatalyst and as a supercapacitor electrode, demonstrating the merits of hybridization with multilayer NSs. The advantages of using multilayer multicomponent conductive NSs as hybridization matrices arise from the enhancement of charge and mass transport through the layer flattening or defect suppression of the hybridized NSs and the increase in porosity, as evidenced by density functional theory calculations. Finally, the universal utility of multilayer NSs is confirmed by investigating the strong effect of the stacking order on the electrocatalytic functionality of MoS2 /rGO/RuO2 films fabricated through layer-by-layer deposition., (© 2021 The Authors. Advanced Science published by Wiley-VCH GmbH.)- Published
- 2022
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15. Lagerstroemia ovalifolia Exerts Anti- Inflammatory Effects in Mice of LPSInduced ALI via Downregulating of MAPK and NF-κB Activation.
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Min JH, Kim SM, Park JW, Kwon NH, Goo SH, Ngatinem, Ningsih S, Paik JH, Choi S, Oh SR, Han SB, Ahn KS, and Lee JW
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- Acute Lung Injury chemically induced, Animals, Anti-Inflammatory Agents pharmacology, Chemokine CCL2, Cyclooxygenase 2, Cytokines metabolism, Heme Oxygenase-1, Indonesia, Macrophages drug effects, Male, Membrane Proteins, Mice, Mice, Inbred C57BL, Nitric Oxide Synthase Type II, Plant Leaves chemistry, RAW 264.7 Cells, Signal Transduction drug effects, Acute Lung Injury drug therapy, Lagerstroemia chemistry, Mitogen-Activated Protein Kinases metabolism, NF-kappa B metabolism, Plant Extracts pharmacology
- Abstract
Lagerstroemia ovalifolia Teijsm. & Binn. (LO) (crape myrtle) has reportedly been used as traditional herbal medicine (THM) in Java, Indonesia. Our previous study revealed that the LO leaf extract (LOLE) exerted anti-inflammatory effects on lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Based on this finding, the current study aimed to evaluate the protective effects of LOLE in a mouse model of LPS-induced acute lung injury (ALI). The results showed that treatment with LPS enhanced the inflammatory cell influx into the lungs and increased the number of macrophages and the secretion of the inflammatory cytokines in the bronchoalveolar lavage fluid (BALF) of mice. However, these effects were notably abrogated with LOLE pretreatment. Furthermore, the increase of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and monocyte chemoattractant protein-1 (MCP-1) expression in the lung tissues of mice with ALI was also reversed by LOLE. In addition, LOLE significantly suppressed the LPS-induced activation of the MAPK/NF-κB signaling pathway and led to heme oxygenase-1 (HO-1) induction in the lungs. Additionally, in vitro experiments showed that LOLE enhanced the expression of HO-1 in RAW264.7 macrophages. The aforementioned findings collectively indicate that LOLE exerts an ameliorative effect on inflammatory response in the airway of ALI mice.
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- 2021
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16. Synergetic Advantages of Atomically Coupled 2D Inorganic and Graphene Nanosheets as Versatile Building Blocks for Diverse Functional Nanohybrids.
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Jin X, Gu TH, Kwon NH, and Hwang SJ
- Abstract
2D nanostructured materials, including inorganic and graphene nanosheets, have evoked plenty of scientific research activity due to their intriguing properties and excellent functionalities. The complementary advantages and common 2D crystal shapes of inorganic and graphene nanosheets render their homogenous mixtures powerful building blocks for novel high-performance functional hybrid materials. The nanometer-level thickness of 2D inorganic/graphene nanosheets allows the achievement of unusually strong electronic couplings between sheets, leading to a remarkable improvement in preexisting functionalities and the creation of unexpected properties. The synergetic merits of atomically coupled 2D inorganic-graphene nanosheets are presented here in the exploration of novel heterogeneous functional materials, with an emphasis on their critical roles as hybridization building blocks, interstratified sheets, additives, substrates, and deposited monolayers. The great flexibility and controllability of the elemental compositions, defect structures, and surface natures of inorganic-graphene nanosheets provide valuable opportunities for exploring high-performance nanohybrids applicable as electrodes for supercapacitors and rechargeable batteries, electrocatalysts, photocatalysts, and water purification agents, to give some examples. An outlook on future research perspectives for the exploitation of emerging 2D nanosheet-based hybrid materials is also presented along with novel synthetic strategies to maximize the synergetic advantage of atomically mixed 2D inorganic-graphene nanosheets., (© 2021 Wiley-VCH GmbH.)
- Published
- 2021
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17. Clinical utility of methionyl-tRNA synthetase 1 immunostaining in cytologic brushings of indeterminate biliary strictures: a multicenter prospective study.
- Author
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Jang SI, Nahm JH, Kwon NH, Jeong S, Lee TH, Cho JH, Kwon CI, Kim DU, Kim JM, Cho HD, Lee HS, Kim S, and Lee DK
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- Cholangiopancreatography, Endoscopic Retrograde, Constriction, Pathologic, Humans, Prospective Studies, Sensitivity and Specificity, Bile Duct Neoplasms, Cholestasis, Methionine-tRNA Ligase
- Abstract
Background and Aims: Endobiliary brushings are routinely used in the diagnosis, treatment, and prognostication of biliary strictures. However, standard Papanicolaou (Pap) staining has a low sensitivity in this setting, and the accuracy of brush cytology has not been established for indeterminate strictures. We therefore evaluated the diagnostic merit of methionyl-transfer RNA synthetase 1 (MARS1) immunofluorescence (IF) staining in such cytologic specimens., Methods: During ERCP, endobiliary brushings were obtained from patients with extrahepatic biliary strictures prospectively enrolled at 6 tertiary hospitals. Using liquid-based cytologic preparations of these samples, we performed Pap and MARS1 IF staining., Results: In total, 240 patients were eligible; of these, we compared the Pap and MARS1 IF staining results of 218 (malignant, 157; benign, 61). By conventional Pap staining, the diagnoses were distributed as follows: malignant, 55; suspicious of malignancy, 60; atypical, 45; negative for malignancy, 58. MARS1 IF staining was strongly positive in malignant biliary stricture but not so in specimens negative for malignancy. The diagnostic parameters (sensitivity, specificity, positive predictive value, negative predictive value, and accuracy) of the MARS1 IF (93.6%, 96.7%, 98.7%, 85.5%, and 94.5%, respectively) and conventional Pap (73.2%, 100%, 100%, 59.2%, and 80.7%, respectively) staining methods differed significantly (P < .0001)., Conclusions: The high sensitivity and accuracy of MARS1 IF staining enabled the detection of malignancy in patients with biliary strictures. Further prospective studies are needed to validate our findings. (Clinical trial registration number: NCT03708445.)., (Copyright © 2021 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.)
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- 2021
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18. Identification of Thieno[3,2- d ]pyrimidine Derivatives as Dual Inhibitors of Focal Adhesion Kinase and FMS-like Tyrosine Kinase 3.
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Cho H, Shin I, Yoon H, Jeon E, Lee J, Kim Y, Ryu S, Song C, Kwon NH, Moon Y, Kim S, Kim ND, Choi HG, and Sim T
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- Animals, Antineoplastic Agents chemical synthesis, Antineoplastic Agents metabolism, Antineoplastic Agents pharmacology, Cell Line, Tumor, Drug Screening Assays, Antitumor, Female, Focal Adhesion Kinase 1 antagonists & inhibitors, Focal Adhesion Kinase 1 metabolism, Humans, Mice, Inbred BALB C, Mice, Nude, Molecular Docking Simulation, Molecular Structure, Neoplasm Metastasis prevention & control, Phosphorylation drug effects, Protein Kinase Inhibitors chemical synthesis, Protein Kinase Inhibitors metabolism, Protein Kinase Inhibitors pharmacology, Pyrimidines chemical synthesis, Pyrimidines metabolism, Pyrimidines pharmacology, Structure-Activity Relationship, Thiophenes chemical synthesis, Thiophenes metabolism, Thiophenes pharmacology, Xenograft Model Antitumor Assays, fms-Like Tyrosine Kinase 3 antagonists & inhibitors, fms-Like Tyrosine Kinase 3 metabolism, Mice, Antineoplastic Agents therapeutic use, Neoplasms drug therapy, Protein Kinase Inhibitors therapeutic use, Pyrimidines therapeutic use, Thiophenes therapeutic use
- Abstract
Focal adhesion kinase (FAK) is overexpressed in highly invasive and metastatic cancers. To identify novel FAK inhibitors, we designed and synthesized various thieno[3,2- d ]pyrimidine derivatives. An intensive structure-activity relationship (SAR) study led to the identification of 26 as a lead. Moreover, 26 , a multitargeted kinase inhibitor, possesses excellent potencies against FLT3 mutants as well as FAK. Gratifyingly, 26 remarkably inhibits recalcitrant FLT3 mutants, including F691L, that cause drug resistance. Importantly, 26 is superior to PF-562271 in terms of apoptosis induction, anchorage-independent growth inhibition, and tumor burden reduction in the MDA-MB-231 xenograft mouse model. Also, 26 causes regression of tumor growth in the MV4-11 xenograft mouse model, indicating that it could be effective against acute myeloid leukemia (AML). Finally, in an orthotopic mouse model using MDA-MB-231, 26 remarkably prevents metastasis of orthotopic tumors to lymph nodes. Taken together, the results indicate that 26 possesses potential therapeutic value against highly invasive cancers and relapsed AML.
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- 2021
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19. Discovery of novel potent migrastatic Thiazolo[5,4-b]pyridines targeting Lysyl-tRNA synthetase (KRS) for treatment of Cancer metastasis.
- Author
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Lee S, Kwon NH, Seo B, Lee JY, Cho HY, Kim K, Kim HS, Jung K, Jeon YH, Kim S, and Suh YG
- Subjects
- Animals, Antineoplastic Agents chemical synthesis, Antineoplastic Agents chemistry, Cell Line, Tumor, Cell Movement drug effects, Cell Proliferation drug effects, Dose-Response Relationship, Drug, Drug Screening Assays, Antitumor, Enzyme Inhibitors chemical synthesis, Enzyme Inhibitors chemistry, Female, Humans, Lysine-tRNA Ligase metabolism, Mammary Neoplasms, Experimental diagnostic imaging, Mammary Neoplasms, Experimental drug therapy, Mammary Neoplasms, Experimental metabolism, Mice, Mice, Inbred BALB C, Molecular Structure, Pyridines chemical synthesis, Pyridines chemistry, Structure-Activity Relationship, Antineoplastic Agents pharmacology, Drug Discovery, Enzyme Inhibitors pharmacology, Lysine-tRNA Ligase antagonists & inhibitors, Pyridines pharmacology
- Abstract
Recently, non-canonical roles of Lysyl-tRNA Synthetase (KRS), which is associated with cell migration and cancer metastasis, have been reported. Therefore, KRS has emerged as a promising target for the treatment of cell migration-related diseases, especially cancer metastasis, although the satisfying chemical inhibitors targeting KRS have not yet been identified. Here, we report the discovery of novel, mechanistically unique, and potent cell migration inhibitors targeting KRS, including the chemical and biological studies on the most effective N,N-dialkylthiazolo [5,4-b]pyridin-2-amine (SL-1910). SL-1910 exhibited highly potent migration inhibition (EC
50 = 81 nM against the mutant KRS-overexpressed MDA-MB-231 cells) and was superior to the previously reported KRS inhibitor (migration inhibitory EC50 = 8.5 μM against H226 cells). The KRS protein binding study via fluorescence-based binding titration and KRS protein 2D-NMR mapping study, in vitro concentration-dependent cell migration inhibition, and in vivo anti-metastatic activity of SL-1910, which consists of a new scaffold, have been reported in this study. In addition, in vitro absorption, distribution, metabolism, and excretion studies and mouse pharmacokinetics experiments for SL-1910 were conducted., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)- Published
- 2021
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20. Determination of zolpidem phenyl-4-carboxylic acid and zolpidem 6-carboxylic acid in hair using gas chromatography-electron ionization-tandem mass spectrometry.
- Author
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Kwon NH, Kim SY, Suh SI, and Kim JY
- Subjects
- Humans, Limit of Detection, Linear Models, Reproducibility of Results, Spectrometry, Mass, Electrospray Ionization, Gas Chromatography-Mass Spectrometry methods, Hair chemistry, Pyridines analysis, Pyridines metabolism, Zolpidem metabolism
- Abstract
A gas chromatography-electron ionization-tandem mass spectrometric (GC-EI-MS/MS) method was developed and validated for determination of the major metabolites of zolpidem, zolpidem phenyl-4-carboxylic acid (ZPCA) and zolpidem 6-carboxylic acid (ZCA) in human hair. The sample preparation procedure involves decontamination, mechanical pulverization, incubation, extraction and purification prior to instrumental analysis. The extracts were derivatized using hexafluoroisopropanol and heptafluorobutyric anhydride and analyzed by GC-EI-MS/MS. The linear ranges were 8-100 pg/mg for ZPCA and 16-200 pg/mg for ZCA, with the correlation coefficients >0.997. The limits of detection were 1.8 pg/mg for ZPCA and 1.7 pg/mg for ZCA. The recoveries ranged from 77.6 to 111.7%. The intra- and inter-day precisions were within 16.9 and 11.7%, while intra- and inter-day accuracies were -7.0-8.7 and -2.8-7.8%, respectively. The developed method was applied for the analysis of forensic hair samples obtained from suspected zolpidem abusers and the following concentration ranges were monitored: ZPCA 11.9-35.9 pg/mg and ZCA 16.6-21.8 pg/mg. The method proved to be suitable for picogram-level determination of ZPCA and ZCA in human hair., (© 2021 John Wiley & Sons, Ltd.)
- Published
- 2021
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21. LC-MS/MS method for determining picogram-level of zolpidem and its main metabolites in hair using a zirconia-based sorbent.
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Kim SY, Kwon NH, Cheong JC, and Kim JY
- Subjects
- Chromatography, Liquid, Limit of Detection, Reproducibility of Results, Substance Abuse Detection, Zirconium, Zolpidem, Hair, Tandem Mass Spectrometry
- Abstract
Although urine and blood samples have been conventionally used for testing zolpidem (ZPD), a sedative-hypnotic, these matrices have limited application because they have a relatively short detection period and can be used only in case of recent drug exposure. Therefore, it is necessary to use an alternative biological sample to obtain the evidence of ZPD misuse. Herein, a liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for the determination of ZPD and its metabolites, zolpidem phenyl-4-carboxylic acid (ZPCA) and zolpidem 6-carboxylic acid (ZCA), in hair to resolve the above-mentioned problems. Mechanical pulverization of hair, methanol extraction with sonication, and the zirconia-based hybrid solid-phase extraction technique were used for obtaining improved extraction efficiency and effective sample purification. The treated hair sample was analyzed using the LC-MS/MS method with the electrospray ionization source in positive and multiple-reaction monitoring modes. The target analytes were separated and detected within 8 min using an Xselect HSS T3 column. Gradient elution was performed using 5 mM ammonium formate and acetonitrile. The lower limit of quantification of ZPD, ZPCA, and ZCA were 1.0, 0.5, and 1.0 pg mg
-1 , respectively. The calibration ranges were 1.0-1000.0 pg mg-1 for ZPD, 0.5-200.0 pg mg-1 for ZPCA, and 1.0-200.0 pg mg-1 for ZCA, with the determination coefficients (r2 ≥ 0.9986). The intraday accuracy and precision ranged from -7.1 to 9.0% and within 6.5%, respectively, and the interday accuracy and precision ranged from -6.1 to 7.9% and within 5.4%, respectively. The recovery, matrix effect, and process efficiency were 65.2-96.6%, 64.6-106.5%, and 44.3-100.5%, respectively, with the relative standard deviation of 4.0-5.0%. The developed method was successfully applied to analyze 13 forensic hair samples of ZPD abusers, and the concentration ratios of ZPD and its two main metabolites (ZPCA and ZCA) in the ZPD-positive samples were also presented. These results revealed that ZPCA and ZCA were not easily incorporated into hair, and demonstrated that their analysis in hair samples requires the employed method to have picogram-level sensitivity. Therefore, the developed method was suitable for simultaneous analysis of ZPD, ZPCA, and ZCA in hair samples, and it could provide clear evidence for illegal ZPD administration, including ZPD-facilitated sexual assault., (Copyright © 2020 Elsevier B.V. All rights reserved.)- Published
- 2021
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22. S100A8/A9 mediate the reprograming of normal mammary epithelial cells induced by dynamic cell-cell interactions with adjacent breast cancer cells.
- Author
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Jo SH, Heo WH, Son HY, Quan M, Hong BS, Kim JH, Lee HB, Han W, Park Y, Lee DS, Kwon NH, Park MC, Chae J, Kim JI, Noh DY, and Moon HG
- Subjects
- Animals, Breast Neoplasms pathology, Cell Line, Tumor, Epithelial Cells pathology, Female, Humans, Mammary Glands, Human pathology, Mice, Mice, Inbred BALB C, Breast Neoplasms metabolism, Calgranulin A metabolism, Calgranulin B metabolism, Cell Communication, Epithelial Cells metabolism, Mammary Glands, Human metabolism, Neoplasm Proteins metabolism
- Abstract
To understand the potential effects of cancer cells on surrounding normal mammary epithelial cells, we performed direct co-culture of non-tumorigenic mammary epithelial MCF10A cells and various breast cancer cells. Firstly, we observed dynamic cell-cell interactions between the MCF10A cells and breast cancer cells including lamellipodia or nanotube-like contacts and transfer of extracellular vesicles. Co-cultured MCF10A cells exhibited features of epithelial-mesenchymal transition, and showed increased capacity of cell proliferation, migration, colony formation, and 3-dimensional sphere formation. Direct co-culture showed most distinct phenotype changes in MCF10A cells followed by conditioned media treatment and indirect co-culture. Transcriptome analysis and phosphor-protein array suggested that several cancer-related pathways are significantly dysregulated in MCF10A cells after the direct co-culture with breast cancer cells. S100A8 and S100A9 showed distinct up-regulation in the co-cultured MCF10A cells and their microenvironmental upregulation was also observed in the orthotropic xenograft of syngeneic mouse mammary tumors. When S100A8/A9 overexpression was induced in MCF10A cells, the cells showed phenotypic features of directly co-cultured MCF10A cells in terms of in vitro cell behaviors and signaling activities suggesting a S100A8/A9-mediated transition program in non-tumorigenic epithelial cells. This study suggests the possibility of dynamic cell-cell interactions between non-tumorigenic mammary epithelial cells and breast cancer cells that could lead to a substantial transition in molecular and functional characteristics of mammary epithelial cells.
- Published
- 2021
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23. Role of tRNAs in Breast Cancer Regulation.
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Kwon NH, Lee JY, and Kim S
- Subjects
- Gene Expression Profiling, High-Throughput Nucleotide Sequencing, Humans, RNA, Transfer genetics, Breast Neoplasms genetics
- Abstract
Increased proliferation and protein synthesis are characteristics of transformed and tumor cells. Although the components of the translation machinery are often dysregulated in cancer, the role of tRNAs in cancer cells has not been well studied. Nevertheless, the number of related studies has recently started increasing. With the development of high throughput technologies such as next-generation sequencing, genome-wide differential tRNA expression patterns in breast cancer-derived cell lines and breast tumors have been investigated. The genome-wide transcriptomics analyses have been linked with many studies for functional and phenotypic characterization, whereby tRNAs or tRNA-related fragments have been shown to play important roles in breast cancer regulation and as promising prognostic biomarkers. Here, we review their expression patterns, functions, prognostic value, and potential therapeutic use as well as related technologies.
- Published
- 2021
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24. Single-cell analysis of AIMP2 splice variants informs on drug sensitivity and prognosis in hematologic cancer.
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Ku J, Kim R, Kim D, Kim D, Song S, Lee K, Lee N, Kim M, Yoon SS, Kwon NH, Kim S, Kim Y, and Koh Y
- Subjects
- Adolescent, Adult, Aged, Aged, 80 and over, Cell Line, Tumor, Drug Resistance, Neoplasm genetics, Exons, Female, Gene Expression Regulation, Neoplastic, Hematologic Neoplasms mortality, Humans, Image Processing, Computer-Assisted, In Situ Hybridization, Fluorescence, Leukemia, Myeloid, Acute drug therapy, Leukemia, Myeloid, Acute genetics, Leukemia, Myeloid, Acute mortality, Male, Middle Aged, Molecular Targeted Therapy, Paclitaxel pharmacology, Prognosis, Single-Cell Analysis, Young Adult, Alternative Splicing, Hematologic Neoplasms drug therapy, Hematologic Neoplasms genetics, Nuclear Proteins genetics
- Abstract
Aminoacyl-tRNA synthetase-interacting multifunctional protein 2 (AIMP2) is a non-enzymatic component required for the multi-tRNA synthetase complex. While exon 2 skipping alternatively spliced variant of AIMP2 (AIMP2-DX2) compromises AIMP2 activity and is associated with carcinogenesis, its clinical potential awaits further validation. Here, we found that AIMP2-DX2/AIMP2 expression ratio is strongly correlated with major cancer signaling pathways and poor prognosis, particularly in acute myeloid leukemia (AML). Analysis of a clinical patient cohort revealed that AIMP2-DX2 positive AML patients show decreased overall survival and progression-free survival. We also developed targeted RNA-sequencing and single-molecule RNA-FISH tools to quantitatively analyze AIMP2-DX2/AIMP2 ratios at the single-cell level. By subclassifying hematologic cancer cells based on their AIMP2-DX2/AIMP2 ratios, we found that downregulating AIMP2-DX2 sensitizes cells to anticancer drugs only for a subgroup of cells while it has adverse effects on others. Collectively, our study establishes AIMP2-DX2 as a potential biomarker and a therapeutic target for hematologic cancer.
- Published
- 2020
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25. New staining method using methionyl-tRNA synthetase 1 antibody for brushing cytology of bile duct cancer.
- Author
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Jang SI, Kwon NH, Lim BJ, Nahm JH, Park JS, Kang CM, Park SR, Lee Sd SY, Kang BS, Kim S, and Lee DK
- Subjects
- Bile Ducts, Bile Ducts, Intrahepatic, Cholangiopancreatography, Endoscopic Retrograde, Humans, Prospective Studies, Sensitivity and Specificity, Staining and Labeling, Bile Duct Neoplasms diagnosis, Methionine-tRNA Ligase
- Abstract
Background and Aims: Identifying malignant biliary strictures using endobiliary brushing cytology specimens is important for treatment decision-making and prognosis prediction. The sensitivity of brushing cytology specimens based on Papanicolaou (Pap) staining is low, which hampers accurate diagnosis of indeterminate strictures. Here, we assessed the diagnostic value of immunohistochemical (IHC) and immunofluorescence (IF) staining for methionyl-tRNA synthetase 1 (MARS1)., Methods: Endobiliary brushing cytology specimens were obtained during ERCP from 80 patients with an extrahepatic biliary stricture. Pap and MARS1 IF staining were performed on liquid-based cytology slides derived from these specimens. Sections of bile duct adenocarcinoma and normal bile duct tissue were obtained from 45 patients who underwent surgery for malignant biliary stricture, and MARS1 levels were evaluated by IHC staining., Results: MARS1 IF staining was applied to brushing cytology specimens, and the results showed strong signals in malignant biliary structures but not in the negative for malignancy specimens. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 70.4%, 96.2%, 97.4%, 56.8%, and 78.8%, respectively, for conventional Pap staining and 98.1%, 96.1%, 98.1%, 96.2%, and 97.5%, respectively, for MARS1 IF (P < .0001). When IHC staining was used, MARS1 was detected in 45 bile duct adenocarcinoma sections but not in 15 normal bile duct sections. Moreover, MARS1 mRNA and protein levels were significantly higher in bile duct adenocarcinoma sections according to polymerase chain reaction and Western blot, respectively., Conclusions: The high sensitivity and accuracy of MARS1 IF staining enabled detection of malignancy in patients with indeterminate biliary stricture. Further prospective studies are needed to validate our findings. (Clinical trial registration number: KCT 0003285.)., (Copyright © 2020 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.)
- Published
- 2020
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26. An Isoform of the Oncogenic Splice Variant AIMP2-DX2 Detected by a Novel Monoclonal Antibody.
- Author
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Kim DG, Nguyen TTH, Kwon NH, Sung J, Lim S, Kang EJ, Lee J, Seo WY, Kim A, Chang YS, Shim H, and Kim S
- Subjects
- Animals, Carcinoma, Non-Small-Cell Lung metabolism, Cells, Cultured, Cricetulus, Humans, Lung Neoplasms metabolism, Nuclear Proteins isolation & purification, Nuclear Proteins metabolism, Rabbits, Antibodies, Monoclonal genetics, Carcinoma, Non-Small-Cell Lung genetics, Lung Neoplasms genetics, Nuclear Proteins genetics, Protein Isoforms genetics
- Abstract
AIMP2-DX2, an exon 2-deleted splice variant of AIMP2 (aminoacyl-tRNA synthetase-interacting multifunctional protein 2), is highly expressed in lung cancer and involved in tumor progression in vivo. Oncogenic function of AIMP2-DX2 and its correlation with poor prognosis of cancer patients have been well established; however, the application of this potentially important biomarker to cancer research and diagnosis has been hampered by a lack of antibodies specific for the splice variant, possibly due to the poor immunogenicity and/or stability of AIMP2-DX2. In this study a monoclonal antibody, H5, that specifically recognizes AIMP2-DX2 and its isoforms was generated via rabbit immunization and phage display techniques, using a short peptide corresponding to the exon 1/3 junction sequence as an antigen. Furthermore, based on mutagenesis, limited cleavage, and mass spectrometry studies, it is also suggested that the endogenous isoform of AIMP2-DX2 recognized by H5 is produced by proteolytic cleavage of 33 amino acids from N-terminus and is capable of inducing cell proliferation similarly to the uncleaved protein. H5 monoclonal antibody is applicable to enzyme-linked immunosorbent assay, immunoblot, immunofluorescence, and immunohistochemistry, and expected to be a valuable tool for detecting AIMP2-DX2 with high sensitivity and specificity for research and diagnostic purposes., Competing Interests: The authors declare no conflict of interest.
- Published
- 2020
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27. Li 0.5 Ni 0.5 Ti 1.5 Fe 0.5 (PO 4 ) 3 /C Electrode Material for Lithium Ion Batteries Exhibiting Faster Kinetics and Enhanced Stability.
- Author
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Srout M, Kwon NH, Ben Youcef H, Semlal N, Fromm KM, and Saadoune I
- Abstract
Natrium super ionic conductor (NASICON) materials providing attractive properties such as high ionic conductivity and good structural stability are considered as very promising materials for use as electrodes for lithium- and sodium-ion batteries. Herein, a new high-performance electrode material, Li
0.5 Ni0.5 Ti1.5 Fe0.5 (PO4 )3 /C, was synthesized via the sol-gel method and was electrochemically tested as an anode for lithium ion batteries, providing enhanced electrochemical performance as a result of nickel substitution into the lithium site in the LiTi2 (PO4 )3 family of materials. The synthesized material showed good ionic conductivity, excellent structural stability, stable long-term cycling performance, and improved high rate cycling performance compared to LiTi2 (PO4 )3 . The Li0.5 Ni0.5 Ti1.5 Fe0.5 (PO4 )3 /C electrode delivered reversible capacities of about 93 and 68% of its theoretical one at current rates of 0.1 C (6.42 mA·g-1 ) after 100 cycles and 5 C (320.93 mA·g-1 ) after 1000 cycles, respectively. Theoretically, three Li+ ions can be inserted into the vacancies of the Li0.5 Ni0.5 Ti1.5 Fe0.5 (PO4 )3 /C structure. However, when the electrode is discharged to 0.5 V, more than three Li+ ions are inserted into the NASICON structure, leading to its structural transformation, and thus to an irreversible electrochemical behavior after the first discharge process.- Published
- 2020
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28. A Nano-Rattle SnO 2 @carbon Composite Anode Material for High-Energy Li-ion Batteries by Melt Diffusion Impregnation.
- Author
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Maharajan S, Kwon NH, Brodard P, and Fromm KM
- Abstract
The huge volume expansion in Sn-based alloy anode materials (up to 360%) leads to a dramatic mechanical stress and breaking of particles, resulting in the loss of conductivity and thereby capacity fading. To overcome this issue, SnO
2 @C nano-rattle composites based on <10 nm SnO2 nanoparticles in and on porous amorphous carbon spheres were synthesized using a silica template and tin melting diffusion method. Such SnO2 @C nano-rattle composite electrodes provided two electrochemical processes: a partially reversible process of the SnO2 reduction to metallic Sn at 0.8 V vs. Li+ /Li and a reversible process of alloying/dealloying of Lix Sny at 0.5 V vs. Li+ /Li. Good performance could be achieved by controlling the particle sizes of SnO2 and carbon, the pore size of carbon, and the distribution of SnO2 nanoparticles on the carbon shells. Finally, the areal capacity of SnO2 @C prepared by the melt diffusion process was increased due to the higher loading of SnO2 nanoparticles into the hollow carbon spheres, as compared with Sn impregnation by a reducing agent., Competing Interests: The authors declare no conflict of interest whatsoever.- Published
- 2020
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29. Moonlighting matrix metalloproteinase substrates: Enhancement of proinflammatory functions of extracellular tyrosyl-tRNA synthetase upon cleavage.
- Author
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Jobin PG, Solis N, Machado Y, Bell PA, Rai SK, Kwon NH, Kim S, Overall CM, and Butler GS
- Subjects
- Chemokines metabolism, Chemotaxis, Enzyme Stability, Humans, Macrophages metabolism, Models, Biological, Monocytes metabolism, NF-kappa B metabolism, Signal Transduction, Substrate Specificity, THP-1 Cells, Toll-Like Receptor 2 metabolism, Tumor Necrosis Factor-alpha metabolism, Tyrosine metabolism, Extracellular Space enzymology, Inflammation Mediators metabolism, Matrix Metalloproteinases metabolism, Tyrosine-tRNA Ligase metabolism
- Abstract
Tyrosyl-tRNA synthetase ligates tyrosine to its cognate tRNA in the cytoplasm, but it can also be secreted through a noncanonical pathway. We found that extracellular tyrosyl-tRNA synthetase (YRS) exhibited proinflammatory activities. In addition to acting as a monocyte/macrophage chemoattractant, YRS initiated signaling through Toll-like receptor 2 (TLR2) resulting in NF-κB activation and release of tumor necrosis factor α (TNFα) and multiple chemokines, including MIP-1α/β, CXCL8 (IL8), and CXCL1 (KC) from THP1 monocyte and peripheral blood mononuclear cell-derived macrophages. Furthermore, YRS up-regulated matrix metalloproteinase (MMP) activity in a TNFα-dependent manner in M0 macrophages. Because MMPs process a variety of intracellular proteins that also exhibit extracellular moonlighting functions, we profiled 10 MMPs for YRS cleavage and identified 55 cleavage sites by a mino- t erminal o riented m ass s pectrometry of s ubstrates (ATOMS) positional proteomics and Edman degradation. Stable proteoforms resulted from cleavages near the start of the YRS C-terminal EMAPII domain. All of the MMPs tested cleaved at ADS
386 ↓387 LYV and VSG405 ↓406 LVQ, generating 43- and 45-kDa fragments. The highest catalytic efficiency for YRS was demonstrated by MMP7, which is highly expressed by monocytes and macrophages, and by neutrophil-specific MMP8. MMP-cleaved YRS enhanced TLR2 signaling, increased TNFα secretion from macrophages, and amplified monocyte/macrophage chemotaxis compared with unprocessed YRS. The cleavage of YRS by MMP8, but not MMP7, was inhibited by tyrosine, a substrate of the YRS aminoacylation reaction. Overall, the proinflammatory activity of YRS is enhanced by MMP cleavage, which we suggest forms a feed-forward mechanism to promote inflammation., (© 2020 Jobin et al.)- Published
- 2020
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30. New Ni 0.5 Ti 2 (PO 4 ) 3 @C NASICON-type Electrode Material with High Rate Capability Performance for Lithium-Ion Batteries: Synthesis and Electrochemical Properties.
- Author
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Srout M, Kwon NH, Luo W, Züttel A, Fromm KM, and Saadoune I
- Abstract
Ni
0.5 Ti2 (PO4 )3 /C NASICON-type phosphate is introduced as a new anode material for lithium-ion batteries (LIBs). Ni0.5 Ti2 (PO4 )3 /C was synthesized through the sol-gel route and delivered some remarkable electrochemical performances. Specifically, the Ni0.5 Ti2 (PO4 )3 /C electrode demonstrates a high rate capability performance and delivers high reversible capacities ranging from 130 mAh g-1 to about 111 mAh g-1 at current rates ranging from 0.1 C to 5 C in the voltage window of 1.85-3 V (vs. Li+ /Li). In the same voltage range, the material reaches an initial capacity of 105 mAh g-1 with a capacity retention of about 82 % after 1000 cycles at the high current rate of 10 C. The electrodes are also tested in the wider voltage range of 0.5-3 V (vs. Li+ /Li) and show good reversibility and rate capability performance. Moreover, the Ni0.5 Ti2 (PO4 )3 /C electrodes enable fast Li+ diffusion (in the order of 10-13 cm2 s-1 ) compared with other NASICON-type materials. As a result, a first discharge capacity of 480 mAh g-1 is reached., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)- Published
- 2019
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31. Surface Modifications of Positive-Electrode Materials for Lithium Ion Batteries.
- Author
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Kwon NH, Conder J, Srout M, and Fromm KM
- Abstract
Lithium ion batteries are typically based on one of three positive-electrode materials, namely layered oxides, olivine- and spinel-type materials. The structure of any of them is 'resistant' to electrochemical cycling, and thus, often requires modification/post-treatment to improve a certain property, for example, structural stability, ionic and/or electronic conductivity. This review provides an overview of different examples of coatings and surface modifications used for the positive-electrode materials as well as various characterization techniques often chosen to confirm/detect the introduced changes. It also assesses the electrochemical success of the surface-modified positive-electrode materials, thereby highlighting remaining challenges and pitfalls.
- Published
- 2019
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32. Methionyl-tRNA Synthetase is a Useful Diagnostic Marker for Lymph Node Metastasis in Non-Small Cell Lung Cancer.
- Author
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Lee JM, Kim T, Kim EY, Kim A, Lee DK, Kwon NH, Kim S, and Chang YS
- Subjects
- Aged, Antigens, CD metabolism, Carcinoma, Non-Small-Cell Lung pathology, Cell Line, Tumor, Female, Humans, Lung Neoplasms pathology, Lymph Nodes pathology, Lymphatic Metastasis pathology, Male, Middle Aged, Neoplasm Staging, ROC Curve, Biomarkers, Tumor metabolism, Carcinoma, Non-Small-Cell Lung diagnosis, Carcinoma, Non-Small-Cell Lung enzymology, Lung Neoplasms diagnosis, Lung Neoplasms enzymology, Lymphatic Metastasis diagnosis, Methionine-tRNA Ligase metabolism
- Abstract
Purpose: Identification of lymph node (LN) metastasis in non-small cell lung cancer (NSCLC) is critical for disease staging and selection of therapeutic modalities. Sometimes it is not possible to obtain LN core tissue by endobronchial ultrasound-guided transbronchial needle aspirate (EBUS-TBNA), resulting in low diagnostic yield., Materials and Methods: In this study, 138 specimens were collected from 108 patients who underwent EBUS-TBNA under the suspicion of LN metastasis of NSCLC. Diagnostic yields of anti-CD45 and anti-methionyl-tRNA synthetase (MRS), immunofluorescent (IF) staining on cytology specimens were compared with those of conventional cytology and positron emission tomography-computed tomography (PET-CT)., Results: MRS was strongly expressed in NSCLC cells metastasized to LNs, but weakly expressed in cells at the periphery of the LN germinal center. The majority of cells were CD20 positive, although a few cells were either CD3 or CD14 positive, indicating that CD45 staining is required for discrimination of non-malignant LN constituent cells from NSCLC cells. When the diagnostic efficacy of MRS/CD45 IF staining was evaluated using 138 LN cellular aspirates from 108 patients through EBUS-TBNA, the sensitivity was 76.7% and specificity was 90.8%, whereas those of conventional cytology test were 71.8% and 100.0%, respectively. Combining the results of conventional cytology testing and those of PET-CT showed a sensitivity and specificity of 71.6% and 100%, and the addition of MRS/CD45 dual IF data to this combination increased sensitivity and specificity to 85.1% and 97.8%, respectively., Conclusion: MRS/CD45 dual IF staining showed good diagnostic performance and may be a good tool complementing conventional cytology test for determining LN metastasis of NSCLC., Competing Interests: The authors have no potential conflicts of interest to disclose., (© Copyright: Yonsei University College of Medicine 2019.)
- Published
- 2019
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33. Matrix metalloproteinases inactivate the proinflammatory functions of secreted moonlighting tryptophanyl-tRNA synthetase.
- Author
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Jobin PG, Solis N, Machado Y, Bell PA, Kwon NH, Kim S, Overall CM, and Butler GS
- Subjects
- Cells, Cultured, Endothelial Cells metabolism, Fibroblasts metabolism, Humans, Macrophages metabolism, Inflammation metabolism, Interferon-gamma metabolism, Matrix Metalloproteinases metabolism, Tryptophan-tRNA Ligase metabolism
- Abstract
Tryptophanyl-tRNA synthetase (WRS) is a cytosolic aminoacyl-tRNA synthetase essential for protein synthesis. WRS is also one of a growing number of intracellular proteins that are attributed distinct noncanonical "moonlighting" functions in the extracellular milieu. Moonlighting aminoacyl-tRNA synthetases regulate processes such as inflammation, but how these multifunctional enzymes are themselves regulated remains unclear. Here, we demonstrate that WRS is secreted from human macrophages, fibroblasts, and endothelial cells in response to the proinflammatory cytokine interferon γ (IFNγ). WRS signaled primarily through Toll-like receptor 2 (TLR2) in macrophages, leading to phosphorylation of the p65 subunit of NF-κB with associated loss of NF-κB inhibitor α (IκB-α) protein. This signaling initiated secretion of tumor necrosis factor α (TNFα) and CXCL8 (IL8) from macrophages. We also demonstrated that WRS is a potent monocyte chemoattractant. Of note, WRS increased matrix metalloproteinase (MMP) activity in the conditioned medium of macrophages in a TNFα-dependent manner. Using purified recombinant proteins and LC-MS/MS to identify proteolytic cleavage sites, we demonstrated that multiple MMPs, but primarily macrophage MMP7 and neutrophil MMP8, cleave secreted WRS at several sites. Loss of the WHEP domain following cleavage at Met
48 generated a WRS proteoform that also results from alternative splicing, designated Δ1-47 WRS. The MMP-cleaved WRS lacked TLR signaling and proinflammatory activities. Thus, our results suggest that moonlighting WRS promotes IFNγ proinflammatory activities, and these responses can be dampened by MMPs., (© 2019 Jobin et al.)- Published
- 2019
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34. Aminoacyl-tRNA synthetases as therapeutic targets.
- Author
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Kwon NH, Fox PL, and Kim S
- Subjects
- Animals, Binding Sites, Catalytic Domain, Clinical Trials as Topic, Drug Evaluation, Preclinical, Evolution, Molecular, Humans, Infections drug therapy, Infections enzymology, Molecular Targeted Therapy, Mutation, Neoplasms drug therapy, Neoplasms enzymology, Amino Acyl-tRNA Synthetases chemistry, Amino Acyl-tRNA Synthetases genetics, Amino Acyl-tRNA Synthetases metabolism, Drug Discovery methods
- Abstract
Aminoacyl-tRNA synthetases (ARSs) are essential enzymes for protein synthesis with evolutionarily conserved enzymatic mechanisms. Despite their similarity across organisms, scientists have been able to generate effective anti-infective agents based on the structural differences in the catalytic clefts of ARSs from pathogens and humans. However, recent genomic, proteomic and functionomic advances have unveiled unexpected disease-associated mutations and altered expression, secretion and interactions in human ARSs, revealing hidden biological functions beyond their catalytic roles in protein synthesis. These studies have also brought to light their potential as a rich and unexplored source for new therapeutic targets and agents through multiple avenues, including direct targeting of the catalytic sites, controlling disease-associated protein-protein interactions and developing novel biologics from the secreted ARS proteins or their parts. This Review addresses the emerging biology and therapeutic applications of human ARSs in diseases including autoimmune and rare diseases, and cancer.
- Published
- 2019
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35. Hybrid Solid-Phase Extraction for Selective Determination of Methamphetamine and Amphetamine in Dyed Hair by Using Gas Chromatography-Mass Spectrometry.
- Author
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Kwon NH, Lee YR, Kim HS, Cheong JC, and Kim JY
- Subjects
- Humans, Reproducibility of Results, Amphetamine chemistry, Amphetamine isolation & purification, Gas Chromatography-Mass Spectrometry, Hair chemistry, Methamphetamine chemistry, Methamphetamine isolation & purification, Solid Phase Extraction
- Abstract
Sample preparation is an important step in the isolation of target compounds from complex matrices to perform their reliable and accurate analysis. Hair samples are commonly pulverized or processed as fine cut, depending on preference, before extraction by techniques such as solid-phase extraction (SPE), liquid-liquid extraction, and other methods. In this study, a method based on hybrid solid-phase extraction (hybridSPE) and gas chromatography-mass spectrometry (GC-MS) was developed and validated for the determination of methamphetamine (MA) and amphetamine (AP) in hair. The hair samples were mechanically pulverized after washing with de-ionized water and acetone. The samples were then sonicated in methanol at 50 °C for 1 h and centrifuged at 50,000× g for 3 min. The supernatants were transferred onto the hybridSPE cartridge and extracted using 1 mL of 0.05 M methanolic hydrogen chloride. The combined solutions were evaporated to dryness, derivatized using pentafluoropropionic anhydride, and analyzed by GC-MS. Excellent linearity (R
2 > 0.9998) was achieved in the ranges of 0.05-5.0 ng/mg for AP and 0.1-10.0 ng/mg for MA. The recovery was 83.4-96.8%. The intra- and inter-day accuracies were -9.4% to 5.5% and -5.1% to 3.1%, while the intra- and inter-day precisions were within 8.3% and 6.7%, respectively. The limits of detections were 0.016 ng/mg for AP and 0.031 ng/mg for MA. The validated hybridSPE method was applied to dyed hair for MA and AP extraction and compared to a methanol extraction method currently being used in our laboratory. The results showed that an additional hybridSPE step improved the recovery by 5.7% for low-concentration quality control (QC) samples and by 24.1% for high-concentration QC samples. Additionally, the hybridSPE method was compared to polymeric reversed-phase SPE methods, and the absolute recoveries for hybridSPE were 50% and 20% greater for AP (1.5 ng/mg) and MA (3.0 ng/mg), respectively. In short, the hybridSPE technique was shown to minimize the matrix effects, improving GC-MS analysis of hair. Based on the results, the proposed method proved to be effective for the selective determination of MA and AP in hair samples.- Published
- 2019
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36. Tumor Suppressor miRNA-204-5p Regulates Growth, Metastasis, and Immune Microenvironment Remodeling in Breast Cancer.
- Author
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Hong BS, Ryu HS, Kim N, Kim J, Lee E, Moon H, Kim KH, Jin MS, Kwon NH, Kim S, Kim D, Chung DH, Jeong K, Kim K, Kim KY, Lee HB, Han W, Yun J, Kim JI, Noh DY, and Moon HG
- Subjects
- Animals, Breast Neoplasms genetics, Breast Neoplasms immunology, Cell Line, Tumor, Cell Proliferation genetics, Class I Phosphatidylinositol 3-Kinases genetics, Female, Heterografts, Humans, Mice, Phosphatidylinositol 3-Kinases metabolism, Proto-Oncogene Proteins c-akt metabolism, Signal Transduction, Survival Analysis, Breast Neoplasms pathology, MicroRNAs physiology, Neoplasm Metastasis genetics, Tumor Microenvironment
- Abstract
Various miRNAs play critical roles in the development and progression of solid tumors. In this study, we describe the role of miR-204-5p in limiting growth and progression of breast cancer. In breast cancer tissues, miR-204-5p was significantly downregulated compared with normal breast tissues, and its expression levels were associated with increased survival outcome in patients with breast cancer. Overexpression of miR-204-5p inhibited viability, proliferation, and migration capacity in human and murine breast cancer cells. In addition, miR-204-5p overexpression resulted in a significant alteration in metabolic properties of cancer cells and suppression of tumor growth and metastasis in mouse breast cancer models. The association between miR-204-5p expression and clinical outcomes of patients with breast cancer showed a nonlinear pattern that was reproduced in experimental assays of cancer cell behavior and metastatic capacities. Transcriptome and proteomic analysis revealed that various cancer-related pathways including PI3K/Akt and tumor-immune interactions were significantly associated with miR-204-5p expression. PIK3CB, a major regulator of PI3K/Akt pathway, was a direct target for miR-204-5p, and the association between PIK3CB-related PI3K/Akt signaling and miR-204-5p was most evident in the basal subtype. The sensitivity of breast cancer cells to various anticancer drugs including PIK3CB inhibitors was significantly affected by miR-204-5p expression. In addition, miR-204-5p regulated expression of key cytokines in tumor cells and reprogrammed the immune microenvironment by shifting myeloid and lymphocyte populations. These data demonstrate both cell-autonomous and non-cell-autonomous impacts of tumor suppressor miR-204-5p in breast cancer progression and metastasis. SIGNIFICANCE: This study demonstrates that regulation of PI3K/Akt signaling by miR-204-5p suppresses tumor metastasis and immune cell reprogramming in breast cancer., (©2019 American Association for Cancer Research.)
- Published
- 2019
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37. Lysyl-tRNA synthetase-expressing colon spheroids induce M2 macrophage polarization to promote metastasis.
- Author
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Nam SH, Kim D, Lee D, Lee HM, Song DG, Jung JW, Kim JE, Kim HJ, Kwon NH, Jo EK, Kim S, and Lee JW
- Subjects
- Animals, Chemokine CXCL1 genetics, Chemokine CXCL1 metabolism, Colonic Neoplasms genetics, Colonic Neoplasms pathology, Fibroblast Growth Factor 2 genetics, Fibroblast Growth Factor 2 metabolism, Fibroblasts enzymology, Fibroblasts pathology, HCT116 Cells, Humans, Intercellular Signaling Peptides and Proteins genetics, Intercellular Signaling Peptides and Proteins metabolism, Lysine-tRNA Ligase genetics, Macrophages pathology, Mice, Mice, Inbred BALB C, Mice, Knockout, Neoplasm Metastasis, Neoplasm Proteins genetics, Spheroids, Cellular pathology, Colonic Neoplasms enzymology, Gene Expression Regulation, Enzymologic, Gene Expression Regulation, Neoplastic, Lysine-tRNA Ligase biosynthesis, Macrophages enzymology, Neoplasm Proteins biosynthesis, Spheroids, Cellular enzymology, Tumor Microenvironment
- Abstract
Lysyl-tRNA synthetase (KRS) functions canonically in cytosolic translational processes. However, KRS is highly expressed in colon cancer, and localizes to distinct cellular compartments upon phosphorylations (i.e., the plasma membranes after T52 phosphorylation and the nucleus after S207 phosphorylation), leading to probably alternative noncanonical functions. It is unknown how other subcellular KRSs crosstalk with environmental cues during cancer progression. Here, we demonstrate that the KRS-dependent metastatic behavior of colon cancer spheroids within 3D gels requires communication between cellular molecules and extracellular soluble factors and neighboring cells. Membranous KRS and nuclear KRS were found to participate in invasive cell dissemination of colon cancer spheroids in 3D gels. Cancer spheroids secreted GAS6 via a KRS-dependent mechanism and caused the M2 polarization of macrophages, which activated the neighboring cells via secretion of FGF2/GROα/M-CSF to promote cancer dissemination under environmental remodeling via fibroblast-mediated laminin production. Analyses of tissues from clinical colon cancer patients and Krs-/+ animal models for cancer metastasis supported the roles of KRS, GAS6, and M2 macrophages in KRS-dependent positive feedback between tumors and environmental factors. Altogether, KRS in colon cancer cells remodels the microenvironment to promote metastasis, which can thus be therapeutically targeted at these bidirectional KRS-dependent communications of cancer spheroids with environmental cues.
- Published
- 2018
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38. Early-Stage Sustainability Evaluation of Nanoscale Cathode Materials for Lithium Ion Batteries.
- Author
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Hischier R, Kwon NH, Brog JP, and Fromm KM
- Abstract
Results of an early-stage sustainability evaluation of two development strategies for new nanoscale cathode materials for Li-ion batteries are reported: (i) a new production pathway for an existing material (LiCoO
2 ) and (ii) a new nanomaterial (LiMnPO4 ). Nano-LiCoO2 was synthesized by a single-source precursor route at a low temperature with a short reaction time, which results in a smaller grain size and, thereby, a better diffusivity for Li ions. Nano-LiMnPO4 was synthesized by a wet chemical method. The sustainability potential of these materials was then investigated (at the laboratory and pilot production scales). The results show that the environmental impact of nano-LiMnPO4 is lower than that of the other examined nanomaterial by several factors regardless of the indicator used for comparison. In contrast to commercial cathode materials, this new material shows, particularly on an energy and capacity basis, results of the same order of magnitude as those of lithium manganese oxide (LiMn2 O4 ) and only slightly higher values than those for lithium iron phosphate (LiFePO4 ); values that are clearly lower than those for high-temperature LiCoO2 ., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)- Published
- 2018
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39. Stabilization of Cyclin-Dependent Kinase 4 by Methionyl-tRNA Synthetase in p16 INK4a -Negative Cancer.
- Author
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Kwon NH, Lee JY, Ryu YL, Kim C, Kong J, Oh S, Kang BS, Ahn HW, Ahn SG, Jeong J, Kim HK, Kim JH, Han DY, Park MC, Kim D, Takase R, Masuda I, Hou YM, Jang SI, Chang YS, Lee DK, Kim Y, Wang MW, Basappa, and Kim S
- Abstract
Although abnormal increases in the level or activity of cyclin-dependent kinase 4 (CDK4) occur frequently in cancer, the underlying mechanism is not fully understood. Here, we show that methionyl-tRNA synthetase (MRS) specifically stabilizes CDK4 by enhancing the formation of the complex between CDK4 and a chaperone protein. Knockdown of MRS reduced the CDK4 level, resulting in G0/G1 cell cycle arrest. The effects of MRS on CDK4 stability were more prominent in the tumor suppressor p16
INK4a -negative cancer cells because of the competitive relationship of the two proteins for binding to CDK4. Suppression of MRS reduced cell transformation and the tumorigenic ability of a p16INK4a -negative breast cancer cell line in vivo . Further, the MRS levels showed a positive correlation with those of CDK4 and the downstream signals at high frequency in p16INK4a -negative human breast cancer tissues. This work revealed an unexpected functional connection between the two enzymes involving protein synthesis and the cell cycle., Competing Interests: The authors declare no competing financial interest., (Copyright © 2018 American Chemical Society.)- Published
- 2018
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40. Intercalative hybridization of layered double hydroxide nanocrystals with mesoporous g-C 3 N 4 for enhancing visible light-induced H 2 production efficiency.
- Author
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Lee JM, Yang JH, Kwon NH, Jo YK, Choy JH, and Hwang SJ
- Abstract
Efficient visible light active hybrid photocatalysts for H
2 production can be synthesized by the intercalative hybridization of Zn-Cr-layered double hydroxide (Zn-Cr-LDH) with a mesoporous g-C3 N4 lattice. Small Zn-Cr-LDH nanocrystals with a size of ∼6 nm are immobilized in the mesopores of g-C3 N4 . Beyond an optimal LDH/g-C3 N4 molar ratio of 0.3, a further increase in the LDH content leads to the surface deposition of LDH crystals on the g-C3 N4 material as well as the intercalative immobilization of LDH into its mesopores, indicating the controllability of the LDH deposition site. The Zn-Cr-LDH-g-C3 N4 nanohybrids exhibit smaller surface areas than the pristine g-C3 N4 , confirming the intercalative stabilization of Zn-Cr-LDH nanocrystals in the mesopore of g-C3 N4 . The hybridization between Zn-Cr-LDH and g-C3 N4 is effective in enhancing visible light absorptivity and also in depressing electron-hole recombination, which is attributable to an efficient electronic coupling between both the hybridized components. The present Zn-Cr-LDH-g-C3 N4 nanohybrid exhibits promising photocatalytic activities for visible light-induced H2 production at a rate of 155.7 μmol g-1 h-1 , which is much superior to that of the pristine g-C3 N4 (21.7 μmol g-1 h-1 ). The present study underscores that the intercalative immobilization of Zn-Cr-LDH crystals in the limited space of a mesopore is quite useful in improving the visible light active photocatalyst functionality of mesoporous carbon nitride.- Published
- 2018
- Full Text
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41. Transfer-RNA-mediated enhancement of ribosomal proteins S6 kinases signaling for cell proliferation.
- Author
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Kwon NH, Lee MR, Kong J, Park SK, Hwang BJ, Kim BG, Lee ES, Moon HG, and Kim S
- Subjects
- Adaptor Proteins, Signal Transducing genetics, Adaptor Proteins, Signal Transducing metabolism, Amino Acid Sequence, Amino Acids deficiency, Animals, Breast Neoplasms metabolism, Breast Neoplasms pathology, Cell Line, Tumor, Cell Proliferation, Female, Gene Expression Regulation, HEK293 Cells, HT29 Cells, Humans, MCF-7 Cells, Mice, NIH 3T3 Cells, Phosphorylation, RNA, Small Interfering genetics, RNA, Small Interfering metabolism, RNA, Transfer, Leu antagonists & inhibitors, RNA, Transfer, Leu metabolism, RNA-Binding Proteins genetics, RNA-Binding Proteins metabolism, Receptor, ErbB-2 metabolism, Receptor, ErbB-3 metabolism, Ribosomal Protein S6 Kinases metabolism, Ribosomal Protein S6 Kinases, 90-kDa genetics, Ribosomal Protein S6 Kinases, 90-kDa metabolism, Signal Transduction, Breast Neoplasms genetics, RNA, Transfer, Leu genetics, Receptor, ErbB-2 genetics, Receptor, ErbB-3 genetics, Ribosomal Protein S6 Kinases genetics
- Abstract
While transfer-RNAs (tRNAs) are known to transport amino acids to ribosome, new functions are being unveiled from tRNAs and their fragments beyond protein synthesis. Here we show that phosphorylation of 90-kDa RPS6K (ribosomal proteins S6 kinase) was enhanced by tRNA
Leu overexpression under amino acids starvation condition. The phosphorylation of 90-kDa RPS6K was decreased by siRNA specific to tRNALeu and was independent to mTOR (mammalian target of rapamycin) signaling. Among the 90-kDa RPS6K family, RSK1 (ribosomal S6 kinase 1) and MSK2 (mitogen-and stress-activated protein kinase 2) were the major kinases phosphorylated by tRNALeu overexpression. Through SILAC (stable isotope labeling by/with amino acids in cell culture) and combined mass spectrometry analysis, we identified EBP1 (ErbB3-binding protein 1) as the tRNALeu -binding protein. We suspected that the overexpression of free tRNALeu would reinforce ErbB2/ErbB3 signaling pathway by disturbing the interaction between ErbB3 and EBP1, resulting in RSK1/MSK2 phosphorylation, improving cell proliferation and resistance to death. Analysis of samples from patients with breast cancer also indicated an association between tRNALeu overexpression and the ErbB2-positive population. Our results suggested a possible link between tRNALeu overexpression and RSK1/MSK2 activation and ErbB2/ErbB3 signaling.- Published
- 2018
- Full Text
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42. Control of leucine-dependent mTORC1 pathway through chemical intervention of leucyl-tRNA synthetase and RagD interaction.
- Author
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Kim JH, Lee C, Lee M, Wang H, Kim K, Park SJ, Yoon I, Jang J, Zhao H, Kim HK, Kwon NH, Jeong SJ, Yoo HC, Kim JH, Yang JS, Lee MY, Lee CW, Yun J, Oh SJ, Kang JS, Martinis SA, Hwang KY, Guo M, Han G, Han JM, and Kim S
- Subjects
- Animals, Antineoplastic Agents pharmacology, Cell Line, Tumor, Drug Screening Assays, Antitumor, Female, Humans, Leucine-tRNA Ligase genetics, Mechanistic Target of Rapamycin Complex 1 genetics, Mice, Mice, Inbred BALB C, Mice, Nude, Monomeric GTP-Binding Proteins genetics, Neoplasms genetics, Neoplasms metabolism, Protein Binding drug effects, Signal Transduction drug effects, Sirolimus pharmacology, Leucine metabolism, Leucine-tRNA Ligase metabolism, Mechanistic Target of Rapamycin Complex 1 metabolism, Monomeric GTP-Binding Proteins metabolism, Neoplasms enzymology
- Abstract
Leucyl-tRNA synthetase (LRS) is known to function as leucine sensor in the mammalian target of rapamycin complex 1 (mTORC1) pathway. However, the pathophysiological significance of its activity is not well understood. Here, we demonstrate that the leucine sensor function for mTORC1 activation of LRS can be decoupled from its catalytic activity. We identified compounds that inhibit the leucine-dependent mTORC1 pathway by specifically inhibiting the GTPase activating function of LRS, while not affecting the catalytic activity. For further analysis, we selected one compound, BC-LI-0186, which binds to the RagD interacting site of LRS, thereby inhibiting lysosomal localization of LRS and mTORC1 activity. It also effectively suppressed the activity of cancer-associated MTOR mutants and the growth of rapamycin-resistant cancer cells. These findings suggest new strategies for controlling tumor growth that avoid the resistance to existing mTOR inhibitors resulting from cancer-associated MTOR mutations.Leucyl-tRNA synthetase (LRS) is a leucine sensor of the mTORC1 pathway. Here, the authors identify inhibitors of the GTPase activating function of LRS, not affecting its catalytic activity, and demonstrate that the leucine sensor function of LRS can be a new target for mTORC1 inhibition.
- Published
- 2017
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43. A critical role of catalyst morphology in low-temperature synthesis of carbon nanotube-transition metal oxide nanocomposite.
- Author
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Jin X, Lim J, Ha Y, Kwon NH, Shin H, Kim IY, Lee NS, Kim MH, Kim H, and Hwang SJ
- Abstract
The effect of the catalyst morphology on the growth of carbon nanotubes (CNT) on nanostructured transition metal oxides was investigated to study a novel low-temperature synthetic route to functional CNT-transition metal oxide nanocomposites. Among several nanostructured manganese oxides with various morphologies and structures, only exfoliated 2D nanosheets of layered MnO
2 acted as an effective catalyst for the chemical vapor deposition of CNT at low temperatures of 400-500 °C, which emphasizes the critical role of the catalyst morphology in CNT growth. Heat treatment of the MnO2 nanosheets under a C2 H2 flow induced the deposition of CNT, as well as a phase transition to a 2D ordered assembly of MnO nanoparticles. The resulting CNT-MnO nanocomposites displayed excellent functionalities in Li-ion electrodes with huge discharge capacities and good rate characteristics, which highlights the usefulness of the present method for studying functional CNT-metal oxide nanocomposites. Electron microscopy and density functional theory calculations propose a formation mechanism via the efficient adsorption of carbon on the MnO2 nanosheets followed by the surface diffusion of carbon. It is of prime importance that the substitution of Fe for layered MnO2 nanosheets remarkably improved the efficiency of the formation of CNT by enhancing the surface adsorption of carbon species. This is the first report of the efficient growth of CNT at a very low temperature of 400 °C. The universal merit of the 2D nanosheet morphology was confirmed by the successful synthesis of a CNT-TiO2 nanocomposite with exfoliated titanate nanosheets. The present study demonstrates that employing exfoliated transition metal oxide nanosheets as catalysts provides an efficient low-temperature synthetic route to functional CNT-transition metal oxide nanocomposites.- Published
- 2017
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44. Characteristics and properties of nano-LiCoO 2 synthesized by pre-organized single source precursors: Li-ion diffusivity, electrochemistry and biological assessment.
- Author
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Brog JP, Crochet A, Seydoux J, Clift MJD, Baichette B, Maharajan S, Barosova H, Brodard P, Spodaryk M, Züttel A, Rothen-Rutishauser B, Kwon NH, and Fromm KM
- Subjects
- A549 Cells, Cations, Monovalent, Chemokines analysis, Cobalt toxicity, Cytokines analysis, Dendritic Cells drug effects, Dendritic Cells metabolism, Electric Power Supplies, Electrodes, Humans, Macrophages drug effects, Macrophages metabolism, Oxides toxicity, Particle Size, Cobalt chemistry, Electrochemistry methods, Lithium chemistry, Nanoparticles chemistry, Oxides chemistry
- Abstract
Background: LiCoO
2 is one of the most used cathode materials in Li-ion batteries. Its conventional synthesis requires high temperature (>800 °C) and long heating time (>24 h) to obtain the micronscale rhombohedral layered high-temperature phase of LiCoO2 (HT-LCO). Nanoscale HT-LCO is of interest to improve the battery performance as the lithium (Li+ ) ion pathway is expected to be shorter in nanoparticles as compared to micron sized ones. Since batteries typically get recycled, the exposure to nanoparticles during this process needs to be evaluated., Results: Several new single source precursors containing lithium (Li+ ) and cobalt (Co2+ ) ions, based on alkoxides and aryloxides have been structurally characterized and were thermally transformed into nanoscale HT-LCO at 450 °C within few hours. The size of the nanoparticles depends on the precursor, determining the electrochemical performance. The Li-ion diffusion coefficients of our LiCoO2 nanoparticles improved at least by a factor of 10 compared to commercial one, while showing good reversibility upon charging and discharging. The hazard of occupational exposure to nanoparticles during battery recycling was investigated with an in vitro multicellular lung model., Conclusions: Our heterobimetallic single source precursors allow to dramatically reduce the production temperature and time for HT-LCO. The obtained nanoparticles of LiCoO2 have faster kinetics for Li+ insertion/extraction compared to microparticles. Overall, nano-sized LiCoO2 particles indicate a lower cytotoxic and (pro-)inflammogenic potential in vitro compared to their micron-sized counterparts. However, nanoparticles aggregate in air and behave partially like microparticles.- Published
- 2017
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45. Ratio of Autoantibodies of Tumor Suppressor AIMP2 and Its Oncogenic Variant Is Associated with Clinical Outcome in Lung Cancer.
- Author
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Jung JY, Kim EY, Kim A, Chang J, Kwon NH, Moon Y, Kang EJ, Sung JS, Shim H, Kim S, and Chang YS
- Abstract
Aminoacyl-tRNA synthetase-interacting multi-functional protein 2 (AIMP2) works as potent tumor suppressor, while its splicing variant lacking exon 2 (AIMP2-DX2) competes with AIMP2 for binding to target proteins and compromises its anti-tumor activity. Assuming that AIMP2 and its variant AIMP2-DX2 could be released out to human sera in pathological condition, we investigated the diagnostic and prognostic usefulness of autoantibodies against AIMP2 and AIMP2-DX2 by measuring their serum levels in 80 normal and lung cancer samples that were matched in age, gender and smoking status. The area under the curve of AIMP2-DX2, AIMP2, and AIMP2-DX2/AIMP2 autoantibody ratio was low (0.416, 0.579, and 0.357, respectively), suggesting limited diagnostic value. A total of 165 lung cancer patients were classified into low and high AIMP2-DX2, AIMP2, and AIMP2-DX2/AIMP2 based on the median expression of each parameter. The high AIMP2-DX2 group was older and had larger tumors (>3 cm) than the low AIMP2-DX2 group. The high AIMP2-DX2/AIMP2 group had higher CYFRA-21 levels and significantly shorter overall survival than the low AIMP2-DX2/AIMP2 group (18.6 vs. 48.9 months, P = 0.021, Log Rank Test). Taken together, autoantibodies against AIMP2-DX2 and AIMP2 are detectable in the human blood and the increased ratio of AIMP2-DX2/AIMP2 is related to poor clinical outcome of lung cancer., Competing Interests: Competing Interests: The authors have declared that no competing interest exists.
- Published
- 2017
- Full Text
- View/download PDF
46. Corrigendum: Secreted tryptophanyl-tRNA synthetase as a primary defence system against infection.
- Author
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Ahn YH, Park S, Choi JJ, Park BK, Rhee KH, Kang E, Ahn S, Lee CH, Lee JS, Inn KS, Cho ML, Park SH, Park K, Park HJ, Lee JH, Park JW, Kwon NH, Shim H, Han BW, Kim P, Lee JY, Jeon Y, Huh JW, Jin M, and Kim S
- Published
- 2017
- Full Text
- View/download PDF
47. In Vitro and In Vivo Studies on Quercus acuta Thunb. (Fagaceae) Extract: Active Constituents, Serum Uric Acid Suppression, and Xanthine Oxidase Inhibitory Activity.
- Author
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Yoon IS, Park DH, Bae MS, Oh DS, Kwon NH, Kim JE, Choi CY, and Cho SS
- Abstract
Quercus acuta Thunb. (Fagaceae) (QA) is cultivated as a dietary and ornamental plant in China, Japan, South Korea, and Taiwan. It has been widely used as the main ingredient of acorn tofu, a traditional food in China and South Korea. The aim of this study was to determine in vitro and in vivo xanthine oxidase (XO) inhibitory and antihyperuricemic activities of an ethyl acetate extract of QA leaf (QALE) and identify its active phytochemicals using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography (LC) systems. The QALE was found to possess potent in vitro antioxidant and XO inhibitory activities. In vivo study using hyperuricemic mice induced with potassium oxonate demonstrated that the QALE could inhibit hepatic XO activity at a relatively low oral dose (50 mg/kg) and significantly alleviate hyperuricemia to a similar extent as allopurinol. Several active compounds including vitamin E known to possess XO inhibitory activity were identified from the QALE. To the best of our knowledge, this is the first study that reports the active constituents and antihyperuricemic effect of QA, suggesting that it is feasible to use QALE as a food therapy or alternative medicine for alleviating hyperuricemia and gout., Competing Interests: The authors have declared that there are no competing interests.
- Published
- 2017
- Full Text
- View/download PDF
48. Secreted tryptophanyl-tRNA synthetase as a primary defence system against infection.
- Author
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Ahn YH, Park S, Choi JJ, Park BK, Rhee KH, Kang E, Ahn S, Lee CH, Lee JS, Inn KS, Cho ML, Park SH, Park K, Park HJ, Lee JH, Park JW, Kwon NH, Shim H, Han BW, Kim P, Lee JY, Jeon Y, Huh JW, Jin M, and Kim S
- Subjects
- Animals, Bacterial Infections pathology, Bacterial Load, Chemokines metabolism, Humans, Immunologic Factors administration & dosage, Immunologic Factors blood, Macrophages immunology, Mice, Monocytes immunology, Phagocytosis, Salmonella Infections, Animal, Salmonella typhimurium isolation & purification, Sepsis immunology, Sepsis pathology, Survival Analysis, Tryptophan-tRNA Ligase administration & dosage, Tryptophan-tRNA Ligase blood, Bacterial Infections immunology, Immunity, Innate, Immunologic Factors metabolism, Tryptophan-tRNA Ligase metabolism
- Abstract
The N-terminal truncated form of a protein synthesis enzyme, tryptophanyl-tRNA synthetase (mini-WRS), is secreted as an angiostatic ligand. However, the secretion and function of the full-length WRS (FL-WRS) remain unknown. Here, we report that the FL-WRS, but not mini-WRS, is rapidly secreted upon pathogen infection to prime innate immunity. Blood levels of FL-WRS were increased in sepsis patients, but not in those with sterile inflammation. FL-WRS was secreted from monocytes and directly bound to macrophages via a toll-like receptor 4 (TLR4)-myeloid differentiation factor 2 (MD2) complex to induce phagocytosis and chemokine production. Administration of FL-WRS into Salmonella typhimurium-infected mice reduced the levels of bacteria and improved mouse survival, whereas its titration with the specific antibody aggravated the infection. The N-terminal 154-amino-acid eukaryote-specific peptide of WRS was sufficient to recapitulate FL-WRS activity and its interaction mode with TLR4-MD2 is now suggested. Based on these results, secretion of FL-WRS appears to work as a primary defence system against infection, acting before full activation of innate immunity.
- Published
- 2016
- Full Text
- View/download PDF
49. Integrative analysis of mutational and transcriptional profiles reveals driver mutations of metastatic breast cancers.
- Author
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Lee JH, Zhao XM, Yoon I, Lee JY, Kwon NH, Wang YY, Lee KM, Lee MJ, Kim J, Moon HG, In Y, Hao JK, Park KM, Noh DY, Han W, and Kim S
- Abstract
Despite the explosion in the numbers of cancer genomic studies, metastasis is still the major cause of cancer mortality. In breast cancer, approximately one-fifth of metastatic patients survive 5 years. Therefore, detecting the patients at a high risk of developing distant metastasis at first diagnosis is critical for effective treatment strategy. We hereby present a novel systems biology approach to identify driver mutations escalating the risk of metastasis based on both exome and RNA sequencing of our collected 78 normal-paired breast cancers. Unlike driver mutations occurring commonly in cancers as reported in the literature, the mutations detected here are relatively rare mutations occurring in less than half metastatic samples. By supposing that the driver mutations should affect the metastasis gene signatures, we develop a novel computational pipeline to identify the driver mutations that affect transcription factors regulating metastasis gene signatures. We identify driver mutations in ADPGK, NUP93, PCGF6, PKP2 and SLC22A5, which are verified to enhance cancer cell migration and prompt metastasis with in vitro experiments. The discovered somatic mutations may be helpful for identifying patients who are likely to develop distant metastasis.
- Published
- 2016
- Full Text
- View/download PDF
50. Suppression of lysyl-tRNA synthetase, KRS, causes incomplete epithelial-mesenchymal transition and ineffective cell‑extracellular matrix adhesion for migration.
- Author
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Nam SH, Kang M, Ryu J, Kim HJ, Kim D, Kim DG, Kwon NH, Kim S, and Lee JW
- Subjects
- Cell Adhesion, Cell Movement, Focal Adhesion Protein-Tyrosine Kinases genetics, HCT116 Cells, Humans, Lysine-tRNA Ligase metabolism, Neoplasms genetics, Signal Transduction, Epithelial-Mesenchymal Transition, Extracellular Matrix genetics, Lysine-tRNA Ligase genetics, Neoplasms pathology
- Abstract
The cell-adhesion properties of cancer cells can be targeted to block cancer metastasis. Although cytosolic lysyl-tRNA synthetase (KRS) functions in protein synthesis, KRS on the plasma membrane is involved in cancer metastasis. We hypothesized that KRS is involved in cell adhesion-related signal transduction for cellular migration. To test this hypothesis, colon cancer cells with modulated KRS protein levels were analyzed for cell-cell contact and cell-substrate adhesion properties and cellular behavior. Although KRS suppression decreased expression of cell-cell adhesion molecules, cells still formed colonies without being scattered, supporting an incomplete epithelial mesenchymal transition. Noteworthy, KRS-suppressed cells still exhibited focal adhesions on laminin, with Tyr397-phopshorylated focal adhesion kinase (FAK), but they lacked laminin-adhesion-mediated extracellular signal-regulated kinase (ERK) and paxillin activation. KRS, p67LR and integrin α6β1 were found to interact, presumably to activate ERK for paxillin expression and Tyr118 phosphorylation even without involvement of FAK, so that specific inhibition of ERK or KRS in parental HCT116 cells blocked cell-cell adhesion and cell-substrate properties for focal adhesion formation and signaling activity. Together, these results indicate that KRS can promote cell-cell and cell-ECM adhesion for migration.
- Published
- 2016
- Full Text
- View/download PDF
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