• Journal of Life Science
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• v.28 no.2
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• pp.162-169
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• 2018

Many cytoplasmic proteins are targeted to the cytoplasmic membrane of the trans-Golgi network (TGN) via an N-terminal short helix. We previously showed that the 20 N-terminal amino acids of Aplysia phosphodiesterase 4 (ApPDE4) long form are sufficient for its targeting to the plasma membrane and the TGN. The N-terminus of the ApPDE4 long form binds to PI4P and sulfatide in vitro. Therefore, in order to decipher the roles of sulfatide in Golgi complex targeting, we examined the cellular localization of sulfatide-binding peptides. In this study, we found that enhanced green fluorescent protein (EGFP) fused to the C-terminus of modified sulfatide- and heparin-binding peptides (mHSBP-EGFP) was localized to the TGN. On the other hand, its mutant, in which tryptophan was replaced with an alanine, leading to the impairment of heparin and sulfatide binding, was localized to cytosol. We also found that the TGN targeting of mHSBP-EGFP is impaired by the treatment of antimycin A, phenylarsine oxide (PAO), and adenosine but not a high concentration of wortmannin. These results suggest that PAO and adenosine-sensitive kinases, including phosphatidylinositol 4-kinase II, may play key roles in the recruitment of mHSBP-EGFP.

• Journal of radiological science and technology
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• v.26 no.1
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• pp.91-97
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• 2003

The purpose of this study is to investigate the mechanism of inhibition of chondrogenic differentiation by X-irradiation. Cultures of chick limb bud mesenchymal cells were exposed to various dose of X-ray and chondrogenesis was examined. X-irradiation inhibited accumulation of proteoglycan based on the observation of alcian blue staining and expression of chondorcyte specific-type II collagen. X-irradiation also inhibited expression of protein kinase $C{\alpha}$ while expression of $PKC{\lambda}({\iota}),\;{\varepsilon}$ was not altered. Expression of Erk-1 was not changed by X-irradiation but phosphorylation of Erk-1 was increased. In addition, inhibition of Erk-1 phosphorylation by PD98059 overcame inhibitory effect of X-irradiation on the chondrogenic differentiation. PNA staining data showed that X-irradiation inhibited cellular aggregation. Taken together, these results suggest that X-irradiation inhibits chondrogenic differentiation by inhibiting cellular aggregation and suppressing expression of $PKC{\alpha}$ and promoting phosphorylation of Erk-1. In addition to above pathway, our results also suggest that X-irradiation may exerts its inhibitory effect by another signaling pathways.

• International Journal of Oral Biology
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• v.30 no.2
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• pp.47-57
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• 2005

Leptin, the product of the obese gene, is a circulating hormone secreted primarily from adipocytes. Several results suggest that leptin is important mediators of bone metabolism. The present study was undertaken to determine the effects of leptin on anti-osteoclastogenesis using murine precursors cultured on Ca-P coated plates and on the production of osteoprotegerin (OPG) in osteoblastic cells. Additionally, this study examined the possible involvement of prostaglandin $E_2\;(PGE_2)$/protein kinase C (PKC)-mediated signals on the effect of leptin on anti-osteoclastogenesis to various culture systems of osteoclast precursors. Osteoclast generation was determined by counting tartrate-resistant acid phosphatase positive [TRAP (+)] multinucleated cells (MNCs). Osteoclastic activity was determined by measuring area of resorption pits formed by osteoclasts on Ca-P coated plate. The number of 1,25-dihydroxycholecalciferol $(1,25[OH]_2D_3)$- or $PGE_2$-induced TRAP (+) MNCs in the mouse bone marrow cell culture decreased significantly after treatment with leptin. The number of receptor activator of NF-kB ligand (RANKL)-induced TRAP (+) MNCs in M-CSF dependent bone marrow macrophage (MDBM) cell or RAW264.7 cell culture decreased significantly with leptin treatment. Indomethacin inhibited osteoclast generation induced by $1,25[OH]_2D_3$ and dexamethasone, however, no significant differences were found in the leptin treated group when compared to the corresponding indomethacin group. Phorbol 12-myristate 13-acetate (PMA), a PKC activator, inhibited osteoclast generation induced by $1,25[OH]_2D_3$. The number of TRAP (+) MNCs decreased significantly with treatment by PMA at concentrations of 0.01 and $0.1{\mu}M$ in culture. Leptin inhibited PMA-mediated osteoclast generation. Isoquinoline-5-sulfonic 2-methyl-1-piperazide dihydrochloride (H7) had no effect on osteoclast generation induced by $1,25[OH]_2D_3$. Cell culture treatment with leptin resulted in no significant differences in osteoclast generation compared to the corresponding H7 group. Indomethacin showed no significant effect on TRAP (+) MNCs formation from the RAW264.7 cell line. PMA inhibited TRAP (+) MNCs formation induced by RANKL in the RAW264.7 cell culture. H7 had no effect on osteoclast generation from the RAW264.7 cell line. There was no difference compared with the corresponding control group after treatment with leptin. $1,25[OH]_2D_3$- or $PGE_2$-induced osteoclastic activity decreased significantly with leptin treatment at a concentration of 100 ng/ml in mouse bone marrow cell culture. Indomethacin, PMA, and H7 significantly inhibited osteoclastic activity induced by $1,25[OH]_2D_3$ in mouse bone marrow cell culture. No significant differences were found between the leptin treated group and the corresponding control group. The secretion of OPG, a substance known to inhibit osteoclast formation, was detected from the osteoblasts. Treatment by leptin resulted in significant increases in OPG secretion by osteoblastic cells. Taken these results, leptin may be an important regulatory cytokines within the bone marrow microenvironment.

• BMB Reports
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• v.32 no.4
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• pp.339-344
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• 1999

We studied the effects of ginsenosides in immature rats based upon the previous results that ginseng has a suppressive or anticonvulsive activity. To examine the suppressive effect of ginsenosides on kainic acid-induced seizures, the severities and frequencies were observed for 4 h after injection of kainic acid (KA; i.p., 2 mg/kg b.w.) using 10-day-old male Sprague-Dawley rats ($22{\pm}2\;g$). Protopanaxadiol saponins such as ginsenoside-Rb1 (Rb1), ginsenoside-Rb2 (Rb2), ginsenoside-Rc (Rc), and ginsenoside-Rd(Rd) generally reduced the seizure activities while protopanaxatriol saponins such as ginsenoside-Rg1 (Rg1) and ginsenoside-Re (Re) rather increased stereotypic "paddling-like" movements. When vinyl-GABA (v-G) was injected together with Rb1 or Rc, KA-induced seizure severities were additionally reduced only by the injection of Rc, but not by Rb1. The level of gamma isozyme of protein kinase C (PKC-${\gamma}$) in the hippocampus increased about three times as much as that of normal rats at 4 h after KA injection. The increased level of PCK-${\gamma}$ by KA was significantly reduced to about 35% by the coinjection with v-G alone, but it was not changed by v-G together with Rb1 or Rc. The increased level of PKC-${\gamma}$ at 4 h after injection of KA was not consistent with the reduction of seizure severities between Rb1 and Rc. These results suggest that Rc and Rb1 may reduce seizure severity independent of PKC-${\gamma}$ levels, and Rc may additionally act with v-G regarding the GABA metabolism during the stage of KA-induced seizures in the immature rats.

• Journal of Acupuncture Research
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• v.27 no.6
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• pp.31-42
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• 2010

Objectives : The aim of this study was to investigate the anti-obesity potential and mechanisms of action of Rhizoma Atractylodis(RA) herbal acupuncture in high fat diet- induced obese ICR mice. Methods : Sample solutions for herbal acupuncture were prepared from the Rhizoma Atractylodis water extract powder at concentration of 150mg/kg and 300mg/kg with distilled water. Five week-old ICR mice acclimatized to the laboratory environment for 1 week were allocated into four groups: regular diet group (RD), high fat diet group(HFD), groups fed HFD with 150mg/kg RA herbal acupuncture treatment (RAE 150) and with 300mg/kg RA herbal acupuncture treatment(RAE 300). Herbal acupuncture groups were injected with either 150mg/kg or 300mg/kg of Rhizoma Atractylodis(RA) subcutaneously onto both Sinsu($BL_{23}$) alternately on the same time everyday for 30days. Body weight, gross appearance of epididymal fat area, blood glucose, insulin, insulin resistance(HOMA-IR), non-esterified fatty acid, cholesterol, triglyceride, AST, ALT, histological analysis of white adipose tissue, gene expression responsible for adipocyte differentiation and AMPK activation were analyzed. Results : RA herbal acupuncture inhibited the development of weight gain, hyperglycemia, hyperinsulinemia, hyperlipidemia, increases of AST and ALT, and the enlargement of fat cell size induced by HFD. Also, RA herbal acupuncture inhibited the expression of PPAR-${\gamma}$, C/$EBP{\alpha}$, aP2, LPL, FAS, SCD-1 and enhanced the activation of AMP-activated protein kinase. Conclusions : The results of this study demonstrate that RA herbal acupuncture can exert the anti-obesity effect and it is partially mediated by activation of AMPK and inhibition of the gene expressions responsible for adipocyte differentiation. Further studies will be required to ascertain the nti-obesity effect and mechanisms of action of RA herbal acupuncture in animal models and human for aclinical application.

• Journal of Microbiology and Biotechnology
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• v.10 no.1
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• pp.27-34
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• 2000

The chloroform and methanol (2;1, v/v) extract from an edible plant, Actinidia arguta Planchon, appeared to possess antitumor activity against human leukemias Jurkat T and U937 cells through inducing apoptosis. The substance in the solvent extract was purified by silica gel column chromatography, preparative TLC, and Sephadex LH-20 column chromatography. Characteristics of the substance analyzed by UV scanning analysis, $^1H$ and $^{13}C$ NMR spectra suggested that the substance belongs to the chlorophyll derivatives-like group. The $IC_{50}$ value of the chlorophyll derivative (Cp-D) determined by MTT assay was $15\mu\textrm{g}/ml$ for Jurkat, $10\mu\textrm{g}/ml$ for U937, and $11.4\mu\textrm{g}/ml$ for HL-60m and was more toxic to these leukemias than to solid tumors or normal fibroblast. In order to elucidate cellular mechanisms underlying the cytotoxicity, the effect of the Cp-D on Jurkat T cells was investigated. When cells were treated with the Cp-D at a concentration of $15\mu\textrm{g}/ml$, [3H]thymidine incorporation declined rapidly and wa undetectable in 1h. However, no significant changes were made in the cell cycle distribution of the cells by 24h. The sub-Gl peak representing apoptotic cells began to be detectable in 36h, at which time apoptotic DNA fragmentation was also detected on agarose gel electrophoresis, demonstrating that the cytotoxic effect of the Cp-D is attributable to the induced apoptosis. Under the same conditions, although the protein level of cyclin-dependent kinases such as cdc4, csk6, cdk2, and cdc2 was not significantly changed until 24h, the kinase activity of all c안 rapidly declined and reached a minimum level within 1-6h and then recovered to the initial level by 12h and sustained until 24h. These results suggest that inactivation of cdks at an inappropriate time during the cell cycle progression in jurkat T cells following a treatment with the Cp-D leads to induction of apoptotic cell death.

• Environmental Mutagens and Carcinogens
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• v.22 no.2
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• pp.65-69
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• 2002

To elucidate the effect of microsphere coinjection on the administration of oligodeoxynucleotides (ODN), we have investigated biodistribution of ［S-35］-labeled antisense ODN targeted to cAMP-dependent protein kinase (PKA) RI-$\alpha$ subunit in nude mice xenografted with WiDr (human colon cancer, ATCC CCL218). The strategy of using microsphere has been proposed for cancer treatment as a carrier of therapeutic ODN so that it could offer an advantage with respect to maintaining constant ODN levels in blood and obtaining higher therapeutic ODN concentration at tumor sites. Comparative biodistribution studies were performed in nude mice (female, 20 g of body weight, n = 4-6) xenografted with WiDr cancer cells, when 0.1 $\mu$Ci (specific activity, 2.94 mCi/$\mu$mole) of ［S-35］-labeled RI-$\alpha$ antisense ODN was injected alone or with microsphere (PLG-18, polylactic copolymer with cationic surfactant DDAB18). Peak tumor uptake of ［S-35］-labeled ODN was significantly increased from 17.7% (at 6 h) of injected dose per gram of tissue (ID/g) to 42.5% (at 24 h) ID/g when microsphere was coinjected with ODN. The different biodistribution in the kidney accumulation (e.g., 100.2% ID/g for ODN alone and 54.9%/ID/g for microshpere coinjection) may contribute to higher blood concentration (e.g., 21.5%ID/$m\ell$ for ODN alone and 37.5%ID/$m\ell$ for microsphere coinjection) of radiolabeled ODN. Of importance is the fact that the whole body retention of radioactivity increased with microsphere coinjection from 50.8%ID/g to 68.0%ID/g after 24-h of injection. This decreased kidney accumulation and increased whole body retention of ［S-35］-labeled ODN resulted in a significant improvement of ODN targeting to the tumor site. In conclusion, the coinjection of microsphere appears to be an important carrier system in vehiculation of antisense oligonucleotide to the tumor tissue in vivo.

• BMB Reports
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• v.51 no.10
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• pp.532-537
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• 2018

Prostaglandin $E_2$ ($PGE_2$), a major product of cyclooxygenase-2 (COX-2), plays an important role in the carcinogenesis of many solid tumors, including colorectal cancer. Because $PGE_2$ functions by signaling through $PGE_2$ receptors (EPs), which regulate tumor cell growth, invasion, and migration, there has been a growing amount of interest in the therapeutic potential of targeting EPs. In the present study, we investigated the role of EP4 on the effectiveness of cordycepin in inhibiting the migration and invasion of HCT116 human colorectal carcinoma cells. Our data indicate that cordycepin suppressed lipopolysaccharide (LPS)-enhanced cell migration and invasion through the inactivation of matrix metalloproteinase (MMP)-9 as well as the down-regulation of COX-2 expression and $PGE_2$ production. These events were shown to be associated with the inactivation of EP4 and activation of AMP-activated protein kinase (AMPK). Moreover, the EP4 antagonist AH23848 prevented LPS-induced MMP-9 expression and cell invasion in HCT116 cells. However, the AMPK inhibitor, compound C, as well as AMPK knockdown via siRNA, attenuated the cordycepin-induced inhibition of EP4 expression. Cordycepin treatment also reduced the activation of CREB. These findings indicate that cordycepin suppresses the migration and invasion of HCT116 cells through modulating EP4 expression and the AMPK-CREB signaling pathway. Therefore, cordycepin has the potential to serve as a potent anti-cancer agent in therapeutic strategies against colorectal cancer metastasis.

• Toxicological Research
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• v.22 no.1
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• pp.23-30
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• 2006

Among poly aromatic hydrocarbons, dioxin and PCBs are the most controversial environmental pollutants in our modern life. These pollutants are known as human carcinogens, and liver is the most sensitive target in animal cancer models. Specific aims of the study were focused on the mechanism of carcinogenesis in hepatocytes and the structure-activity relation among these diverse environmental chemicals. Because key mechanisms of dioxin-induced carcinogenesis in human epithelial cell model are the alteration of signal transduction pathway and PKC isoforms, the alteration of the signal transduction pathways and other factors associated with carcinogenesis were studied. Rat hepatocytes cultured under the sandwich protocols were exposed with the various concentration of dioxins and PCBs, and signal transduction pathway, protein kinase C isoforms, oxidant stress, and apoptotic nuclei were evaluated. Since it is important to understand the structure-activity relation among these chemicals to properly assess the carcinogenic potentials, the study analyzed the parameters associated with carcinogenic processes, based on their structural characteristics. In addition, signal transduction pathways and PKC isoforms involved in inhibition of UV-induced apoptosis were also analyzed to elaborate the tumor promotion mechanism of these chemicals. Induction of apoptosis by UV irradiation was optimal at $60\;J/m^2$ in primary hepatocyte in culture. Compared to non coplanar PCBs such as PCB 114 and PCB 153, coplanar PCBs such as PCB 77 and PCB126 showed a stronger inhibition of apoptosis induced by UV irradiation. Production of reactive oxygen species (ROS) was more stimulated by non-coplanar PCBs than coplanar PCBs with the most potent induction of ROS by chlorinated non-coplanar PCB. As compared to the level of induction by PCB126, non-coplanar PCB153 showed a higher increase of intracellular concentrations. Besides the alteration of intracellular calcium concentration, translocation of PKC from cytosolic fraction to membrane fraction was clearly observed upon the exposure of non-coplanar PCB. Taken together, the present study demonstrated that there is a potent structure-activity relationship among PCB congeners and the mechanism of PAH-induced carcinogenesis is structure-specific. The study suggested that more diverse pathways of PAH-induced carcinogenesis should be taken into account beyond the boundary of Ah receptor dogma to assess the health impact of PAH with more accuracy.

• BMB Reports
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• v.46 no.6
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• pp.316-321
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• 2013

Gastric cancer remains the main cause of cancer death all around the world, and upregulated activation of the nonreceptor tyrosine kinase c-SRC (SRC) is a key player in the development. In this study, we found that expression of Src is also increased in clinical gastric cancer samples, with the protein level increased more significantly than that at the RNA level. Further study revealed that miR34a and miR203, two tumor suppressive miRNAs, inversely correlate with the expression of Src. Restoration of miR34a and miR203 decreased Src expression in gastric cancer cell lines, which in turn inhibited cell growth and cell migration. In summary, our study here revealed that posttranscriptional regulation of Src contributes to the deregulated cell growth and metastasis in gastric cancer, and targeting Src by miR34a or miR203 mimics would be a promising strategy in therapy.