Publications by authors named "So Yeong Lee"

96 Publications

The role of the voltage-gated potassium channel, Kv2.1 in prostate cancer cell migration.

BMB Rep 2021 Feb;54(2):130-135

Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 08826, Korea.

Voltage-gated potassium (Kv) channels are involved in many important cellular functions and play pivotal roles in cancer progression. The expression level of Kv2.1 was observed to be higher in the highly metastatic prostate cancer cells (PC-3), specifically in their membrane, than in immortalized prostate cells (WPMY-1 cells) and comparatively less metastatic prostate cancer cells (LNCaP and DU145 cells). However, Kv2.1 expression was significantly decreased when the cells were treated with antioxidants, such as N-acetylcysteine or ascorbic acid, implying that the highly expressed Kv2.1 could detect reactive oxygen species (ROS) in malignant prostate cancer cells. In addition, the blockade of Kv2.1 with stromatoxin-1 or siRNA targeting Kv2.1 significantly inhibited the migration of malignant prostate cancer cells. Our results suggested that Kv2.1 plays an important role as a ROS sensor and that it is a promising therapeutic molecular target in metastasis of prostate cancer. [BMB Reports 2021; 54(2): 130-135].
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7907745PMC
February 2021

High Salt Intake Recruits Tonic Activation of NR2D Subunit-Containing Extrasynaptic NMDARs in Vasopressin Neurons.

J Neurosci 2021 Feb 10;41(6):1145-1156. Epub 2020 Dec 10.

Department of Physiology, Chungnam National University, Daejeon 35015, Republic of Korea

In addition to producing a classical excitatory postsynaptic current via activation of synaptic NMDA receptors (NMDARs), glutamate in the brain also induces a tonic NMDAR current () via activation of extrasynaptic NMDARs (eNMDARs). However, since Mg blocks NMDARs in nondepolarized neurons, the potential contribution of eNMDARs to the overall neuronal excitatory/inhibitory (E/I) balance remains unknown. Here, we demonstrate that chronic (7 d) salt loading (SL) recruited NR2D subunit-containing NMDARs to generate an Mg-resistant tonic in nondepolarized [ (holding potential) -70 mV] vasopressin (VP; but not oxytocin) supraoptic nucleus (SON) neurons in male rodents. Conversely, in euhydrated (EU) and 3 d SL mice, Mg-resistant tonic was not observed. Pharmacological and genetic intervention of NR2D subunits blocked the Mg-resistant tonic in VP neurons under SL conditions, while an NR2B antagonist unveiled Mg-sensitive tonic but not Mg-resistant tonic In the EU group VP neurons, an Mg-resistant tonic was not generated by increased ambient glutamate or treatment with coagonists (e.g., d-serine and glycine). Chronic SL significantly increased NR2D expression but not NR2B expression in the SON relative to the EU group or after 3 d under SL conditions. Finally, Mg-resistant tonic selectively upregulated neuronal excitability in VP neurons under SL conditions, independent of ionotropic GABAergic input. Our results indicate that the activation of NR2D-containing NMDARs constitutes a novel mechanism that generates an Mg-resistant tonic in nondepolarized VP neurons, thus causing an E/I balance shift in VP neurons to compensate for the hormonal demands imposed by a chronic osmotic challenge. The hypothalamic supraoptic nucleus (SON) consists of two different types of magnocellular neurosecretory cells (MNCs) that synthesize and release the following two peptide hormones: vasopressin (VP), which is necessary for regulation of fluid homeostasis; and oxytocin (OT), which plays a major role in lactation and parturition. NMDA receptors (NMDARs) play important roles in shaping neuronal firing patterns and hormone release from the SON MNCs in response to various physiological challenges. Our results show that prolonged (7 d) salt loading generated a Mg-resistant tonic NMDA current mediated by NR2D subunit-containing receptors, which efficiently activated nondepolarized VP (but not OT) neurons. Our findings support the hypothesis that NR2D subunit-containing NMDARs play an important adaptive role in adult brain in response to a sustained osmotic challenge.
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http://dx.doi.org/10.1523/JNEUROSCI.1742-20.2020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7888215PMC
February 2021

A 24-week intervention based on nutrition care process improves diet quality, body mass index, and motivation in children and adolescents with obesity.

Nutr Res 2020 12 19;84:53-62. Epub 2020 Sep 19.

Department of Medical Nutrition, Kyung Hee University, Yongin, Gyeonggi-do, 17104, South Korea; Research Institute of Medical Nutrition, Kyung Hee University, Seoul 02447, South Korea. Electronic address:

Higher motivation could support to lead behavioral change for obese children and adolescents. This study aimed to evaluate the effects of a nutrition care process (NCP)-based intervention targeted on diet and weight status in moderate to severe obese children and adolescents in Korea. One hundred four subjects (mean age: 10.95 years, body mass index (BMI) ≥97th percentile of age-sex) participated in the present study. Subjects were divided into a usual care group (UG) and a nutrition group (NG). All participants underwent nutrition education 6 times. The NG received individual access and continuous monitoring and setting goals with respect to nutritional problems. Consumption of high-calorie, low-nutrient (HCLN) food was significantly decreased (P < .05) and the Diet Quality Index-International (DQI-I) score also increased with respect to sodium (P < .001). The total self-efficacy score was increased from 9.15 to 10.14 points (P < .01). After 24 weeks, the BMI-z-score decreased from 2.27 to 2.19 in the NG (P < .05); however, no group difference was found. BMI-z-score was negatively associated with self-efficacy (β = -0.03, P < .019). NCP-based intervention might be helpful to solve dietary problems by enhancing self-efficacy and lower BMI-z-score in moderately to severely obese children and adolescents.
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http://dx.doi.org/10.1016/j.nutres.2020.09.005DOI Listing
December 2020

Pharmacological inhibition of Kv3 on oxidative stress-induced cataract progression.

Biochem Biophys Res Commun 2020 Dec 14;533(4):1255-1261. Epub 2020 Oct 14.

Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, Republic of Korea. Electronic address:

Oxidative stress is one of the most important risk factors for cataractogenesis. Previous studies have indicated that BDS-II, a Kv3 channel blocker, plays pivotal roles in oxidative stress-related diseases. This study demonstrates that BDS-II exerts a protective effect on cataractogenesis. Specifically, BDS-II was observed to inhibit lens opacity induced by HO. BDS-II was also determined to inhibit cataract progression in a sodium selenite-induced in vivo cataract model by inhibiting reduction of the total GSH. In addition, BDS-II was demonstrated to protect human lens epithelial cells against HO-induced cell death. Our results suggest that BDS-II is a potential pharmacological candidate in cataract therapy.
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http://dx.doi.org/10.1016/j.bbrc.2020.09.138DOI Listing
December 2020

Acute Anemia Induces Erythropoiesis in Rat Organ Surface Primo-Vascular Tissue.

Adv Exp Med Biol 2020 ;1232:385-392

Department of Veterinary Pharmacology, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea.

The primo-vascular system (PVS) is a newly identified vascular tissue composed of primo-nodes (PNs) and primo-vessels (PVs). Previously, we reported erythropoietic activity in the organ-surface PVS (osPVS) tissue of rats with heart failure. In this study, we further investigated whether acute anemia could induce erythropoiesis in the PVS of rats, based on the hypothesis that erythropoiesis in osPVS tissue is due to anemia accompanying heart failure. Acute anemia was induced by an intraperitoneal injection of phenylhydrazine (PHZ). Circulating red blood cells (RBCs) and hematocrit decreased by 31.6%, whereas reticulocytes and white blood cells increased at day 3 and day 6 after PHZ treatment. All these parameters recovered to control levels at day 10. At days 3 and 6, we observed an increase in the size of the PNs (P < 0.05), the number of the osPVS tissue samples per rat (P < 0.01), and the proportion of osPVS tissue samples with red chromophore (P < 0.001), which was from the RBCs in the PVS tissue. The number of RBCs, estimated from the PN sections stained with hematoxylin and eosin, increased at day 6 in the rats with anemia (P < 0.01). All these anemia-induced changes in the osPVS tissue recovered to the control levels by day 10. Taken together, the results showed that the morphological and cytological changes in the osPVS tissue appear to be related to the erythropoietic activity induced by acute anemia in rats. This study confirmed the previous findings that the osPVS can exert erythropoietic activity in disease states accompanied by anemia, such as heart failure.
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http://dx.doi.org/10.1007/978-3-030-34461-0_49DOI Listing
January 2020

Nanostars on Nanopipette Tips: A Raman Probe for Quantifying Oxygen Levels in Hypoxic Single Cells and Tumours.

Angew Chem Int Ed Engl 2019 02 1;58(9):2710-2714. Epub 2019 Feb 1.

Department of Information Communication, Materials, and Chemistry Convergence Technology, Soongsil University, Seoul, Korea.

Multiple sharp-edged gold nanostars were efficiently assembled on nanopipette tips through electrostatic interactions for use as a potent intracellular hypoxia-sensing Raman probe. Colloidal stability and surface immobilization were checked using scanning electron microscopy, light scattering, and zeta potential measurements. Site-specific intracellular hypoxia levels can be estimated in vitro and in vivo using Raman lancets (RL). Distinct Raman spectral changes for the nitro-(NO ) functional group of the redox marker 4-nitrothiophenol (4NTP) can be quantified according to the intracellular oxygen (O ) content, ranging from 1 % to 10 %. Redox potential changes in mitochondrial respiration were also examined through serial injections of inhibitors. 3D-cultured cells and in vivo tests were used to validate our method, and its application in the assessment of the aggressiveness of cancer cells by differentiating spectral changes between malignant and benign cells was demonstrated.
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http://dx.doi.org/10.1002/anie.201812677DOI Listing
February 2019

Exercise training normalizes elevated firing rate of hypothalamic presympathetic neurons in heart failure rats.

Am J Physiol Regul Integr Comp Physiol 2019 02 28;316(2):R110-R120. Epub 2018 Nov 28.

Department of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University , Seoul , Republic of Korea.

Exercise training (ExT) normalizes elevated sympathetic nerve activity in heart failure (HF), but the underlying mechanisms are not well understood. In this study, we examined the effects of 3 wk of ExT on the electrical activity of the hypothalamic presympathetic neurons in the brain slice of HF rats. HF rats were prepared by ligating the left descending coronary artery. The electrophysiological properties of paraventricular nucleus neurons projecting to the rostral ventrolateral medulla (PVN-RVLM) were examined using the slice patch-clamp technique. The neuronal firing rate was elevated in HF rats, and ExT induced a reduction in the firing rate ( P < 0.01). This ExT-induced decrease in the firing rate was associated with an increased frequency of spontaneous and miniature inhibitory postsynaptic current (IPSCs; P < 0.05). There was no significant change in excitatory postsynaptic current. Replacing Ca with Mg in the recording solution reduced the elevated IPSC frequency in HF rats with ExT ( P < 0.01) but not in those without ExT, indicating an increase in the probability of GABA release. In contrast, ExT did not restore the reduced GABA receptor-mediated tonic inhibitory current in HF rats. A GABA receptor blocker (bicuculline, 20 μM) increased the firing rate in HF rats with ExT ( P < 0.01) but not in those without ExT. Collectively, these results show that ExT normalized the elevated firing activity by increasing synaptic GABA release in PVN-RVLM neurons in HF rats. Our findings provide a brain mechanism underlying the beneficial effects of ExT in HF, which may shed light on the pathophysiology of other diseases accompanied by sympathetic hyperactivation.
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http://dx.doi.org/10.1152/ajpregu.00225.2018DOI Listing
February 2019

Kv3.1 and Kv3.4, Are Involved in Cancer Cell Migration and Invasion.

Int J Mol Sci 2018 Apr 2;19(4). Epub 2018 Apr 2.

Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 08826, Korea.

Voltage-gated potassium (Kv) channels, including Kv3.1 and Kv3.4, are known as oxygen sensors, and their function in hypoxia has been well investigated. However, the relationship between Kv channels and tumor hypoxia has yet to be investigated. This study demonstrates that Kv3.1 and Kv3.4 are tumor hypoxia-related Kv channels involved in cancer cell migration and invasion. Kv3.1 and Kv3.4 protein expression in A549 and MDA-MB-231 cells increased in a cell density-dependent manner, and the pattern was similar to the expression patterns of hypoxia-inducible factor-1α (HIF-1α) and reactive oxygen species (ROS) according to cell density, whereas Kv3.3 protein expression did not change in A549 cells with an increase in cell density. The Kv3.1 and Kv3.4 blocker blood depressing substance (BDS) did not affect cell proliferation; instead, BDS inhibited cell migration and invasion. We found that BDS inhibited intracellular pH regulation and extracellular signal-regulated kinase (ERK) activation in A549 cells cultured at a high density, potentially resulting in BDS-induced inhibition of cell migration and invasion. Our data suggest that Kv3.1 and Kv3.4 might be new therapeutic targets for cancer metastasis.
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http://dx.doi.org/10.3390/ijms19041061DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5979479PMC
April 2018

Alteration of MicroRNA Expression Profiles by Surface-Modified Gold Nanoparticles in Human Lung Adenocarcinoma Cells.

J Nanosci Nanotechnol 2018 Apr;18(4):3024-3030

Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, 08826, Korea.

MicroRNAs that bind to mRNA are important post-transcriptional regulators that control gene expression by degradation or suppressing translation of target mRNAs. Several studies indicate that nanoparticles (NPs) induce alterations in microRNA expression relating to cell processes including cell development and progressive diseases. However, the alteration of microRNA expression by surface-modified gold nanoparticles (AuNPs) in A549 cells has not been reported. In order to investigate the patterns of microRNA expression, we analyzed data from microRNA arrays using cells treated with citrate- or chitosan-AuNPs. The results demonstrate that the expression of microRNA (hsa-miR-198) in cells treated with citrate-AuNPs significantly differed from non-treated cells, and the expression of 16 microRNAs in cells treated with chitosan-AuNPs significantly differed from non-treated cells. Furthermore, the predicted target genes of microRNAs were related to proliferation, apoptosis, migration, and cell differentiation, including the mitogen-activated protein kinase, ErbB, and Wnt signaling pathway. Thus, the alteration of microRNA expression profiles by citrate- and chitosan-AuNPs would mediate the regulation of the cell processes including cell survival, migration, and differentiation.
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http://dx.doi.org/10.1166/jnn.2018.14395DOI Listing
April 2018

Potential Erythropoiesis in the Primo-Vascular System in Heart Failure.

Adv Exp Med Biol 2017 ;977:409-415

Department of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, 08826, Republic of Korea.

The primo-vascular system (PVS), composed of primo-nodes (PNs) and primo-vessels (PVs), has been identified in various animal models. However, little is known about its function. Here, we investigated the changes in gross morphology and cellular composition of the organ-surface PVS (osPVS) in rats with heart failure (HF) induced by myocardial infarction. The size of the PNs in rats with HF was larger than in sham rats (1.87 vs. 0.80 mm; P < 0.01) and the density of osPVS per rat was greater for the HF rats (28 of 6 rats vs. 19 of 9 rats; P < 0.01). In addition, the osPVS number containing red chromophore was greater in HF rats (P < 0.001). The chromophore was identified as hemoglobin. Transmission electron microscopy and H&E staining revealed that the osPVS of HF rats (P < 0.001) possessed more red blood cells (RBCs) than that of the sham rats. In particular, immature RBC number increased in the HF rats (90.7 vs. 42.3%; P < 0.001). Altogether, the results showed that the osPVS in HF rats increased in its size, density, and the proportion of immature RBCs in the PNs, which may indicate that the PVS has erythropoietic activity. Our study will help to elucidate the physiological roles of PVS in normal and disease states associated with HF.
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http://dx.doi.org/10.1007/978-3-319-55231-6_53DOI Listing
January 2018

Kv3.4 is modulated by HIF-1α to protect SH-SY5Y cells against oxidative stress-induced neural cell death.

Sci Rep 2017 05 18;7(1):2075. Epub 2017 May 18.

Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, 08826, Korea.

The Kv3.4 channel is characterized by fast inactivation and sensitivity to oxidation. However, the physiological role of Kv3.4 as an oxidation-sensitive channel has yet to be investigated. Here, we demonstrate that Kv3.4 plays a pivotal role in oxidative stress-related neural cell damage as an oxidation-sensitive channel and that HIF-1α down-regulates Kv3.4 function, providing neuroprotection. MPP and CoCl are reactive oxygen species (ROS)-generating reagents that induce oxidative stress. However, only CoCl decreases the expression and function of Kv3.4. HIF-1α, which accumulates in response to CoCl treatment, is a key factor in Kv3.4 regulation. In particular, mitochondrial Kv3.4 was more sensitive to CoCl. Blocking Kv3.4 function using BDS-II, a Kv3.4-specific inhibitor, protected SH-SY5Y cells against MPP-induced neural cell death. Kv3.4 inhibition blocked MPP-induced cytochrome c release from the mitochondrial intermembrane space to the cytosol and mitochondrial membrane potential depolarization, which are characteristic features of apoptosis. Our results highlight Kv3.4 as a possible new therapeutic paradigm for oxidative stress-related diseases, including Parkinson's disease.
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http://dx.doi.org/10.1038/s41598-017-02129-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5437029PMC
May 2017

Highly Luminescent Folate-Functionalized Au Nanoclusters for Bioimaging.

Adv Healthc Mater 2017 Aug 15;6(16). Epub 2017 May 15.

Department of Chemistry, Yonsei University, Seoul, 03722, Republic of Korea.

Gold nanoclusters are emerging as new materials for biomedical applications because of promises offered by their ultrasmall size and excellent biocompatibility. Here, the synthesis and optical and biological characterizations of a highly luminescent folate-functionalized Au cluster (Au -FA) are reported. The Au -FA clusters are synthesized by functionalizing the surface of Au (SG) clusters, where SG is glutathione, with benzyl chloroformate and folate. The functionalized clusters are highly water-soluble and exhibit remarkably bright luminescence with a quantum yield of 42%, significantly higher than any other water-soluble gold clusters protected with thiolate ligands. The folate groups conjugated to the gold cluster give rise to additional luminescence enhancement by energy transfer sensitization. The brightness of Au -FA is found to be 4.77 mM cm , nearly 8-fold brighter than that of Au (SG) . Further biological characterizations have revealed that the Au -FA clusters are well-suited for bioimaging. The Au -FA clusters exhibit excellent photostability and low toxicity; nearly 80% cell viability at 1000 ppm of the cluster. Additionally, the Au -FA clusters show target specificity to folate-receptor positive cells. Finally, the time-course in vivo luminescence images of intravenous-injected mice show that the Au -FA clusters are renal-clearable, leaving only 8% of them remained in the body after 24 h post-injection.
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http://dx.doi.org/10.1002/adhm.201700203DOI Listing
August 2017

Regulation of voltage-gated potassium channels attenuates resistance of side-population cells to gefitinib in the human lung cancer cell line NCI-H460.

BMC Pharmacol Toxicol 2017 02 21;18(1):14. Epub 2017 Feb 21.

Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, Korea.

Background: Side-population (SP) cells that exclude anti-cancer drugs have been found in various tumor cell lines. Moreover, SP cells have a higher proliferative potential and drug resistance than main population cells (Non-SP cells). Also, several ion channels are responsible for the drug resistance and proliferation of SP cells in cancer.

Methods: To confirm the expression and function of voltage-gated potassium (Kv) channels of SP cells, these cells, as well as highly expressed ATP-binding cassette (ABC) transporters and stemness genes, were isolated from a gefitinib-resistant human lung adenocarcinoma cell line (NCI-H460), using Hoechst 33342 efflux.

Results: In the present study, we found that mRNA expression of Kv channels in SP cells was different compared to Non-SP cells, and the resistance of SP cells to gefitinib was weakened with a combination treatment of gefitinib and Kv channel blockers or a Kv7 opener, compared to single-treatment gefitinib, through inhibition of the Ras-Raf signaling pathway.

Conclusions: The findings indicate that Kv channels in SP cells could be new targets for reducing the resistance to gefitinib.
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http://dx.doi.org/10.1186/s40360-017-0118-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5319158PMC
February 2017

Targeted Genome Engineering to Control VEGF Expression in Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells: Potential Implications for the Treatment of Myocardial Infarction.

Stem Cells Transl Med 2017 03 3;6(3):1040-1051. Epub 2017 Jan 3.

Department of Biochemistry, BK21 PLUS Program for Creative Veterinary Science Research and Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University, Seoul, South Korea.

Human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) exhibit potency for the regeneration of infarcted hearts. Vascular endothelial growth factor (VEGF) is capable of inducing angiogenesis and can boost stem cell-based therapeutic effects. However, high levels of VEGF can cause abnormal blood vessel growth and hemangiomas. Thus, a controllable system to induce therapeutic levels of VEGF is required for cell therapy. We generated an inducible VEGF-secreting stem cell (VEGF/hUCB-MSC) that controls the expression of VEGF and tested the therapeutic efficacy in rat myocardial infarction (MI) model to apply functional stem cells to MI. To introduce the inducible VEGF gene cassette into a safe harbor site of the hUCB-MSC chromosome, the transcription activator-like effector nucleases system was used. After confirming the integration of the cassette into the locus, VEGF secretion in physiological concentration from VEGF/hUCB-MSCs after doxycycline (Dox) induction was proved in conditioned media. VEGF secretion was detected in mice implanted with VEGF/hUCB-MSCs grown via a cell sheet system. Vessel formation was induced in mice transplanted with Matrigel containing VEGF/hUCB-MSCs treated with Dox. Moreover, seeding of the VEGF/hUCB-MSCs onto the cardiac patch significantly improved the left ventricle ejection fraction and fractional shortening in a rat MI model upon VEGF induction. Induced VEGF/hUCB-MSC patches significantly decreased the MI size and fibrosis and increased muscle thickness, suggesting improved survival of cardiomyocytes and protection from MI damage. These results suggest that our inducible VEGF-secreting stem cell system is an effective therapeutic approach for the treatment of MI. Stem Cells Translational Medicine 2017;6:1040-1051.
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http://dx.doi.org/10.1002/sctm.16-0114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5442764PMC
March 2017

Ultrastructure of the Subcutaneous Primo-Vascular System in Rat Abdomen.

Adv Exp Med Biol 2016 ;923:319-325

Department of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, 151-742, Republic of Korea.

Recently, we identified the primo-vascular system (PVS), a novel vascular network, in rat subcutaneous tissues. Little is known about the subcutaneous PVS (sc-PVS). Here, we examined the ultrastructure of the sc-PVS in the hypodermis at the rat abdominal midline by electron microscopy. On the surface of sc-PVS, we observed three types of cells: microcells (5-6 μm), large elliptical cells (>20 μm), and erythrocyte (3-4 μm). The inside of the sc-PVS was filled with numerous cells, which can be classified into three major groups: leucocytes, mast cells, and erythrocytes. The dense leucocytes and mast cells were easily noticed. The extracellular matrix of the sc-PVS was mainly composed of extensive fibers (79 ± 6.5 nm) tightly covered by micro- (0.5-1 μm) and nanoparticles (10-100 nm). In conclusion, the ultrastructural features, such as the resident cells on and in the sc-PVS and fiber meshwork covered by particles, indicate that sc-PVS might act as a circulatory channel for the flow and delivery of numerous cells and particles. Our findings will help understand the nature of various sc-PVS beneath-the-skin layers and how they relate to acupuncture meridians.
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http://dx.doi.org/10.1007/978-3-319-38810-6_42DOI Listing
November 2017

The Role of KV7.3 in Regulating Osteoblast Maturation and Mineralization.

Int J Mol Sci 2016 Mar 18;17(3):407. Epub 2016 Mar 18.

Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742, Korea.

KCNQ (KV7) channels are voltage-gated potassium (KV) channels, and the function of KV7 channels in muscles, neurons, and sensory cells is well established. We confirmed that overall blockade of KV channels with tetraethylammonium augmented the mineralization of bone-marrow-derived human mesenchymal stem cells during osteogenic differentiation, and we determined that KV7.3 was expressed in MG-63 and Saos-2 cells at the mRNA and protein levels. In addition, functional KV7 currents were detected in MG-63 cells. Inhibition of KV7.3 by linopirdine or XE991 increased the matrix mineralization during osteoblast differentiation. This was confirmed by alkaline phosphatase, osteocalcin, and osterix in MG-63 cells, whereas the expression of Runx2 showed no significant change. The extracellular glutamate secreted by osteoblasts was also measured to investigate its effect on MG-63 osteoblast differentiation. Blockade of KV7.3 promoted the release of glutamate via the phosphorylation of extracellular signal-regulated kinase 1/2-mediated upregulation of synapsin, and induced the deposition of type 1 collagen. However, activation of KV7.3 by flupirtine did not produce notable changes in matrix mineralization during osteoblast differentiation. These results suggest that KV7.3 could be a novel regulator in osteoblast differentiation.
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http://dx.doi.org/10.3390/ijms17030407DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4813262PMC
March 2016

Voltage-Gated K+ Channel, Kv3.3 Is Involved in Hemin-Induced K562 Differentiation.

PLoS One 2016 5;11(2):e0148633. Epub 2016 Feb 5.

Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, Korea.

Voltage-gated K+ (Kv) channels are well known to be involved in cell proliferation. However, even though cell proliferation is closely related to cell differentiation, the relationship between Kv channels and cell differentiation remains poorly investigated. This study demonstrates that Kv3.3 is involved in K562 cell erythroid differentiation. Down-regulation of Kv3.3 using siRNA-Kv3.3 increased hemin-induced K562 erythroid differentiation through decreased activation of signal molecules such as p38, cAMP response element-binding protein, and c-fos. Down-regulation of Kv3.3 also enhanced cell adhesion by increasing integrin β3 and this effect was amplified when the cells were cultured with fibronectin. The Kv channels, or at least Kv3.3, appear to be associated with cell differentiation; therefore, understanding the mechanisms of Kv channel regulation of cell differentiation would provide important information regarding vital cellular processes.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0148633PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4743930PMC
July 2016

Identification of Primo-Vascular System in Abdominal Subcutaneous Tissue Layer of Rats.

Evid Based Complement Alternat Med 2015 25;2015:751937. Epub 2015 Aug 25.

Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 151-742, Republic of Korea.

The primo-vascular system (PVS) is a novel network identified in various animal tissues. However, the PVS in subcutaneous tissue has not been well identified. Here, we examined the putative PVS on the surface of abdominal subcutaneous tissue in rats. Hemacolor staining revealed dark blue threadlike structures consisting of nodes and vessels, which were frequently observed bundled with blood vessels. The structure was filled with various immune cells including mast cells and WBCs. In the structure, there were inner spaces (20-60 µm) with low cellularity. Electron microscopy revealed a bundle structure and typical cytology common with the well-established organ surface PVS, which were different from those of the lymphatic vessel. Among several subcutaneous (sc) PVS tissues identified on the rat abdominal space, the most outstanding was the scPVS aligned along the ventral midline. The distribution pattern of nodes and vessels in the scPVS closely resembled that of the conception vessel meridian and its acupoints. In conclusion, our results newly revealed that the PVS is present in the abdominal subcutaneous tissue layer and indicate that the scPVS tissues are closely correlated with acupuncture meridians. Our findings will help to characterize the PVS in the other superficial tissues and its physiological roles.
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http://dx.doi.org/10.1155/2015/751937DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4561983PMC
September 2015

Gold nanoparticles promote osteogenic differentiation in human adipose-derived mesenchymal stem cells through the Wnt/β-catenin signaling pathway.

Int J Nanomedicine 2015 7;10:4383-92. Epub 2015 Jul 7.

Laboratory of Veterinary Pharmacology, Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University, Seoul, South Korea.

Gold nanoparticles (AuNPs) are attractive materials for use in biomedicine due to their physical properties. Increasing evidence suggests that several nanoparticles induce the differentiation of human mesenchymal stem cells into osteoblasts and adipocytes. In this study, we hypothesized that chitosan-conjugated AuNPs promote the osteogenic differentiation of human adipose-derived mesenchymal stem cells. For the evaluation of osteogenic differentiation, alizarin red staining, an alamarBlue(®) assay, and a quantitative real-time polymerase chain reaction analysis were performed. In order to examine specific signaling pathways, immunofluorescence and a western blotting assay were performed. Our results demonstrate that chitosan-conjugated AuNPs increase the deposition of calcium content and the expression of marker genes related to osteogenic differentiation in human adipose-derived mesenchymal stem cells at nontoxic concentrations. These results indicate that chitosan-conjugated AuNPs promote osteogenesis through the Wnt/β-catenin signaling pathway. Therefore, chitosan-conjugated AuNPs can be used as a reagent for promoting bone formation.
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http://dx.doi.org/10.2147/IJN.S78775DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4500612PMC
April 2016

Expression, refolding, and characterization of a small laccase from Thermus thermophilus HJ6.

Protein Expr Purif 2015 Oct 11;114:37-43. Epub 2015 Jun 11.

Department of Smart-Biohealth, Dong-Eui University, Busan 614-714, Republic of Korea; Department of Biotechnology & Bioengineering, Dong-Eui University, Busan 614-714, Republic of Korea. Electronic address:

An open reading frame of the Thermus thermophilus HJ6 hypothetical laccase, which composed of 729 bases, was cloned and expressed as a fusion protein with six histidine residues in Escherichia coli SoluBL21™ cells. The resulting insoluble bodies were separated from cellular debris by centrifugation and solubilized with 6M guanidine HCl. The solubilized protein was refolded by a simple on-column refolding procedure using Ni-chelation affinity chromatography and then the refolded protein was purified by gel filtration chromatography. It showed a single band with a molecular mass of 27kDa in SDS-PAGE. The results from UV-visible absorption and electron paramagnetic resonance (EPR) analysis suggested that the enzyme had the typical copper sites, type-1, 2, and 3 Cu(II) of laccase. The purified enzyme exhibited the laccase activity with the optimal catalytic temperature at 75°C. The optimum pH for the oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and syringaldazine was 4.5 and 6.0, respectively. The recombinant protein showed high thermostability, and the half-life of heat inactivation was about 50min at 85°C. The enzyme oxidized various known laccase substrates, its lowest Km value being for syringaldazine, highest kcat value for guaiacol, and highest kcat/Km for 2,6-dimethoxy-phenol. The enzyme reaction was strongly inhibited by the metal chelators and the thiol compounds.
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http://dx.doi.org/10.1016/j.pep.2015.06.004DOI Listing
October 2015

Enhanced astroglial GABA uptake attenuates tonic GABAA inhibition of the presympathetic hypothalamic paraventricular nucleus neurons in heart failure.

J Neurophysiol 2015 Aug 10;114(2):914-26. Epub 2015 Jun 10.

Department of Physiology, School of Medicine, Chungnam National University, Daejeon, Republic of Korea;

γ-Aminobutyric acid (GABA) generates persistent tonic inhibitory currents (Itonic) and conventional inhibitory postsynaptic currents in the hypothalamic paraventricular nucleus (PVN) via activation of GABAA receptors (GABAARs). We investigated the pathophysiological significance of astroglial GABA uptake in the regulation of Itonic in the PVN neurons projecting to the rostral ventrolateral medulla (PVN-RVLM). The Itonic of PVN-RVLM neurons were significantly reduced in heart failure (HF) compared with sham-operated (SHAM) rats. Reduced Itonic sensitivity to THIP argued for the decreased function of GABAAR δ subunits in HF, whereas similar Itonic sensitivity to benzodiazepines argued against the difference of γ2 subunit-containing GABAARs in SHAM and HF rats. HF Itonic attenuation was reversed by a nonselective GABA transporter (GAT) blocker (nipecotic acid, NPA) and a GAT-3 selective blocker, but not by a GAT-1 blocker, suggesting that astroglial GABA clearance increased in HF. Similar and minimal Itonic responses to bestrophin-1 blockade in SHAM and HF neurons further argued against a role for astroglial GABA release in HF Itonic attenuation. Finally, the NPA-induced inhibition of spontaneous firing was greater in HF than in SHAM PVN-RVLM neurons, whereas diazepam induced less inhibition of spontaneous firing in HF than in SHAM neurons. Overall, our results showed that combined with reduced GABAARs function, the enhanced astroglial GABA uptake-induced attenuation of Itonic in HF PVN-RVLM neurons explains the deficit in tonic GABAergic inhibition and increased sympathetic outflow from the PVN during heart failure.
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http://dx.doi.org/10.1152/jn.00080.2015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4533111PMC
August 2015

Silencing of voltage-gated potassium channel KV9.3 inhibits proliferation in human colon and lung carcinoma cells.

Oncotarget 2015 Apr;6(10):8132-43

Laboratory of Veterinary Pathology, Seoul National University, Seoul, Korea.

Voltage-gated potassium (Kv) channels are known to be involved in cancer development and cancer cell proliferation. KV9.3, an electronically silent subunit, forms heterotetramers with KV2.1 in excitable cells and modulates its electrophysiological properties. However, the role of KV9.3 alone in non-excitable cancer cells has not been studied. Here, we evaluated the effect of silencing KV9.3 on cancer cell proliferation in HCT15 colon carcinoma cells and A549 lung adenocarcinoma cells. We confirmed the expression of KV9.3 mRNA in HCT15 and A549 cells and showed that silencing KV9.3 using small interfering RNA caused G0/G1 cell cycle arrest and alterations in cell cycle regulatory proteins in both HCT15 and A549 cells without affecting apoptosis. Also, stable knockdown of KV9.3 expression using short-hairpin RNA inhibited tumor growth in SCID mouse xenograft model. Using a bioinformatics approach, we identified Sp1 binding sites in the promoter region of the gene encoding KV9.3. We further found that Sp1 bound to this region and showed that the Sp1 inhibitor, mithramycin A, induced a concentration-dependent decrease in KV9.3 expression. Taken together, these data suggest that knockdown of KV9.3 inhibits proliferation in colon carcinoma and lung adenocarcinoma cell lines and may be regulated by Sp1.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4480740PMC
http://dx.doi.org/10.18632/oncotarget.3517DOI Listing
April 2015

Nuclear localization and functional characteristics of voltage-gated potassium channel Kv1.3.

J Biol Chem 2015 May 31;290(20):12547-57. Epub 2015 Mar 31.

From the Laboratories of Veterinary Pharmacology and

It is widely known that ion channels are expressed in the plasma membrane. However, a few studies have suggested that several ion channels including voltage-gated K(+) (Kv) channels also exist in intracellular organelles where they are involved in the biochemical events associated with cell signaling. In the present study, Western blot analysis using fractionated protein clearly indicates that Kv1.3 channels are expressed in the nuclei of MCF7, A549, and SNU-484 cancer cells and human brain tissues. In addition, Kv1.3 is located in the plasma membrane and the nucleus of Jurkat T cells. Nuclear membrane hyperpolarization after treatment with margatoxin (MgTX), a specific blocker of Kv1.3 channels, provides evidence for functional channels at the nuclear membrane of A549 cells. MgTX-induced hyperpolarization is abolished in the nuclei of Kv1.3 silenced cells, and the effects of MgTX are dependent on the magnitude of the K(+) gradient across the nuclear membrane. Selective Kv1.3 blockers induce the phosphorylation of cAMP response element-binding protein (CREB) and c-Fos activation. Moreover, Kv1.3 is shown to form a complex with the upstream binding factor 1 in the nucleus. Chromatin immunoprecipitation assay reveals that Sp1 transcription factor is directly bound to the promoter region of the Kv1.3 gene, and the Sp1 regulates Kv1.3 expression in the nucleus of A549 cells. These results demonstrate that Kv1.3 channels are primarily localized in the nucleus of several types of cancer cells and human brain tissues where they are capable of regulating nuclear membrane potential and activation of transcription factors, such as phosphorylated CREB and c-Fos.
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http://dx.doi.org/10.1074/jbc.M114.561324DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4432276PMC
May 2015

Low Non-NMDA Receptor Current Density as Possible Protection Mechanism from Neurotoxicity of Circulating Glutamate on Subfornical Organ Neurons in Rats.

Korean J Physiol Pharmacol 2015 Mar 25;19(2):177-81. Epub 2015 Feb 25.

Department of Veterinary Pharmacology, College of Veterinary Medicine, Seoul National University, Seoul 151-742, Korea.

The subfornical organ (SFO) is one of circumventricular organs characterized by the lack of a normal blood brain barrier. The SFO neurons are exposed to circulating glutamate (60~100 µM), which may cause excitotoxicity in the central nervous system. However, it remains unclear how SFO neurons are protected from excitotoxicity caused by circulating glutamate. In this study, we compared the glutamate-induced whole cell currents in SFO neurons to those in hippocampal CA1 neurons using the patch clamp technique in brain slice. Glutamate (100 µM) induced an inward current in both SFO and hippocampal CA1 neurons. The density of glutamate-induced current in SFO neurons was significantly smaller than that in hippocampal CA1 neurons (0.55 vs. 2.07 pA/pF, p<0.05). To further identify the subtype of the glutamate receptors involved, the whole cell currents induced by selective agonists were then compared. The current densities induced by AMPA (0.45 pA/pF) and kainate (0.83 pA/pF), non-NMDA glutamate receptor agonists in SFO neurons were also smaller than those in hippocampal CA1 neurons (2.44 pA/pF for AMPA, p<0.05; 2.34 pA/pF for kainate, p< 0.05). However, the current density by NMDA in SFO neurons was not significantly different from that of hippocampal CA1 neurons (1.58 vs. 1.47 pA/pF, p>0.05). These results demonstrate that glutamate-mediated action through non-NMDA glutamate receptors in SFO neurons is smaller than that of hippocampal CA1 neurons, suggesting a possible protection mechanism from excitotoxicity by circulating glutamate in SFO neurons.
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http://dx.doi.org/10.4196/kjpp.2015.19.2.177DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4342738PMC
March 2015

Colloidal gold nanoparticle conjugates of gefitinib.

Colloids Surf B Biointerfaces 2014 Nov 23;123:61-7. Epub 2014 Aug 23.

Department of Chemistry, Soongsil University, Seoul 156-743, South Korea. Electronic address:

Gefitinib (GF) is a US Food and Drug Administration-approved epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor for treating the lung cancers. We fabricated colloidal gold nanoparticle (AuNP) conjugates of the GF anticancer drug by self-assembly to test their potency against A549, NCI-H460, and NCI-H1975 lung cancer cells. GF adsorption on AuNP surfaces was examined by UV-vis absorption spectra and surface-enhanced Raman scattering. Density functional theory calculations were performed to estimate the energetic stabilities of the drug-AuNP composites. The N1 nitrogen atom of the quinazoline ring of GF was calculated to be more stable than the N3 in binding Au cluster atoms. The internalizations of GF-coated AuNPs were examined by transmission electron and dark-field microscopy. A cell viability test of AuNP-GF conjugates with the EGFR antibody exhibited much higher reductions than free GF for A549, NCI-H460, and NCI-H1975 lung cancer cells after treatment for 48.
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http://dx.doi.org/10.1016/j.colsurfb.2014.08.021DOI Listing
November 2014

Peptide nucleic acid-mediated aggregation of reduced graphene oxides and label-free detection of DNA mutation.

J Phys Chem B 2014 Jun 29;118(23):6297-301. Epub 2014 May 29.

Department of Chemical and Biomolecular Engineering, Yonsei University , Seoul, Republic of Korea.

We have investigated peptide nucleic acid (PNA)-mediated aggregation of reduced graphene oxide (rGO) sheets. Addition of PNA into suspension of rGOs resulted in aggregation of rGOs, which could be easily detected with the naked eye. To elucidate the mechanism of rGO aggregation, we monitored the reaction by transmission electron microscopy, zeta potential measurement, and UV-vis spectroscopy. Our findings suggest that PNA adsorbed on the rGO surface and then acted as a cross-linker to induce aggregation. We also tested the effects of different nucleic acids on rGO aggregation and found that not only the single-stranded DNA, but also the PNA-DNA complex, could stabilize the suspension against aggregation through electrostatic repulsion. Based on our understanding on rGO aggregation, we attempted to detect mutations in epidermal growth factor receptor (EGFR) by designing PNA probe to be complementary to the mutant type DNA sequence. Our results showed that PNA-mediated rGO aggregation could successfully be used to detect mutations in EGFR with high selectivity and sensitivity.
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http://dx.doi.org/10.1021/jp501820jDOI Listing
June 2014

Adsorption and desorption of tyrosine kinase inhibitor erlotinib on gold nanoparticles.

J Colloid Interface Sci 2014 Jul 20;425:96-101. Epub 2014 Mar 20.

Department of Chemistry, Soongsil University, Seoul 156-743, Republic of Korea. Electronic address:

We investigated interfacial behaviors of erlotinib (EL) on gold nanoparticles (AuNPs) by means of Raman spectroscopy. The adsorption reactions and structures of EL on AuNP surfaces were examined by UV-Vis absorption spectroscopy and surface-enhanced Raman scattering (SERS). Density functional theory calculations were performed to estimate the energetic stabilities of the drug-AuNP composites. Among the binding units in EL, the acetylenic C≡C group was calculated to be the most strongly binding on the AuNP cluster atoms, consistent with the SERS spectra. The concentration-dependent SERS spectra indicated that ∼10(-5) M of EL exhibited the highest SERS signals. The attached EL appeared to desorb more efficiently with 2mM glutathione than with cell culture media. The lack of a strong SERS signal of EL in the dark-field microscopy images of AuNP-EL complexes suggested almost complete desorption of EL inside cells.
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http://dx.doi.org/10.1016/j.jcis.2014.03.032DOI Listing
July 2014

Umbilical-cord-blood-derived mesenchymal stem cells seeded onto fibronectin-immobilized polycaprolactone nanofiber improve cardiac function.

Acta Biomater 2014 Jul 19;10(7):3007-17. Epub 2014 Mar 19.

Department of Veterinary Biochemistry, BK21 Plus and Research Institute of Veterinary Science, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea. Electronic address:

Stem cells seeded onto biofunctional materials have greater potency for therapeutic applications. We investigated whether umbilical-cord-blood-derived mesenchymal stem cell (UCB-MSC)-seeded fibronectin (FN)-immobilized polycaprolactone (PCL) nanofibers could improve cardiac function and inhibit left ventricle (LV) remodeling in a rat model of myocardial infarction (MI). Aligned nanofibers were uniformly coated with poly(glycidyl methacrylate) by initiated chemical vapor deposition followed by covalent immobilization of FN proteins. The degree of cell elongation and adhesion efficacy were improved by FN immobilization. Furthermore, genes related to angiogenesis and mesenchymal differentiations were up-regulated in the FN-immobilized PCL nanofibers in comparison to control PCL nanofibers in vitro. 4 weeks after the transplantation in the rat MI model, the echocardiogram showed that the UCB-MSC-seeded FN-immobilized PCL nanofiber group increased LV ejection fraction and fraction shortening as compared to the non-treated control and acellular FN-immobilized PCL nanofiber groups. Histological analysis indicated that the implantation of UCB-MSCs with FN-immobilized PCL nanofibers induced a decrease in MI size and fibrosis, and an increase in scar thickness. This study indicates that FN-immobilized biofunctional PCL nanofibers could be an effective carrier for UCB-MSC transplantation for the treatment of MI.
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http://dx.doi.org/10.1016/j.actbio.2014.03.013DOI Listing
July 2014

Serum starvation-induced voltage-gated potassium channel Kv7.5 expression and its regulation by Sp1 in canine osteosarcoma cells.

Int J Mol Sci 2014 Jan 10;15(1):977-93. Epub 2014 Jan 10.

Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742, Korea.

The KCNQ gene family, whose members encode Kv7 channels, belongs to the voltage-gated potassium (Kv) channel group. The roles of this gene family have been widely investigated in nerve and muscle cells. In the present study, we investigated several characteristics of Kv7.5, which is strongly expressed in the canine osteosarcoma cell line, CCL-183. Serum starvation upregulated Kv7.5 expression, and the Kv7 channel opener, flupirtine, attenuated cell proliferation by arresting cells in the G0/G1 phase. We also showed that Kv7.5 knockdown helps CCL-183 cells to proliferate. In an effort to find an endogenous regulator of Kv7.5, we used mithramycin A to reduce the level of the transcription factor Sp1, and it strongly inhibited the induction of Kv7.5 in CCL-183 cells. These results suggest that the activation of Kv7.5 by flupirtine may exert an anti-proliferative effect in canine osteosarcoma. Therefore, Kv7.5 is a possible molecular target for canine osteosarcoma therapy.
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http://dx.doi.org/10.3390/ijms15010977DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3907850PMC
January 2014

Gold nanorod-assembled PEGylated graphene-oxide nanocomposites for photothermal cancer therapy.

Photochem Photobiol 2014 May-Jun;90(3):659-66. Epub 2013 Dec 5.

Department of Chemistry, Soongsil University, Seoul, Korea.

Gold nanorod-attached PEGylated graphene-oxide (AuNR-PEG-GO) nanocomposites were tested for a photothermal platform both in vitro and in vivo. Cytotoxicity of AuNR was reduced after encapsulation with PEG-GO along with the removal of cetyltrimethylammonium bromide (CTAB) from AuNR by HCl treatment. Cellular internalization of the CTAB-eliminated AuNR-PEG-GO nanocomposites was examined using dark-field microscopy (DFM), confocal Raman microscopy and transmission electron microscopy (TEM). To determine the photothermal effect of the AuNR-PEG-GO nanocomposites, A431 epidermoid carcinoma cells were irradiated with Xe-lamp light (60 W cm(-2)) for 5 min after treatment with the AuNR-PEG-GO nanocomposites for 24 h. Cell viability significantly decreased by ~40% when the AuNR-PEG-GO-encapsulated nanocomposites were irradiated with light as compared with the cells treated with only the AuNR-PEG-GO nanocomposites without any illumination. In vivo tumor experiments also indicated that HCl-treated AuNR-PEG-GO nanocomposites might efficiently reduce tumor volumes via photothermal processes. Our graphene and AuNR nanocomposites will be useful for an effective photothermal therapy.
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http://dx.doi.org/10.1111/php.12212DOI Listing
July 2015