• Journal of Life Science
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• v.26 no.4
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• pp.490-495
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• 2016

Brefeldin A (BFA), a lactone antibiotic isolated from the fungus Eupenicillium brefeldianum, inhibits the transport of secreted and membrane proteins from the endoplasmic reticulum (ER) to the Golgi apparatus. BFA disrupts Golgi function, the accumulation of unfolded proteins in ER, and the induction of ER stress. Prolonged ER stress induces apoptosis at least in part through the transcription factor C/EBP (CCAAT/enhancer binding protein) homologous protein (CHOP),which is activated by the unfolded protein response (UPR). In this paper, we demonstrate that BFA-induced endoplasmic reticulum stress leads to different CHOP expression in primary astrocyte cells and C6 glioma cells. BFA induced lower CHOP expression levels in primary astrocyte cells than in C6 glioma cells; however, other ER stress inducers (thapsigargin and tunicamycin) resulted in similar expression patterns in these two cell types. Interestingly, the three different ER stress inducers (BFA, thapsigargin, and tunicamycin) induced similar levels of CHOP mRNA expression in primary astrocyte cells. The ubiquitin-proteasome inhibitor MG132 also markedly up-regulated the BFA-mediated CHOP protein expression in primary astrocyte cells. BFA also induced higher proteasome activity in primary astrocyte cells than in C6 glioma cells. Taken together, our results suggest that higher proteasomal activity might down-regulate BFA-induced CHOP expression in primary astrocyte cells.

• Molecules and Cells
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• v.27 no.1
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• pp.113-118
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• 2009

In this study, we have shown the transcriptional regulation of the human GD3 synthase (hST8Sia I) induced by valproic acid (VPA) in human neuroblastoma SK-N-BE(2)-C cells. To elucidate the mechanism underlying the regulation of hST8Sia I gene expression in VPA-stimulated SK-N-BE(2)-C cells, we characterized the promoter region of the hST8Sia I gene. Functional analysis of the 5'-flanking region of the hST8Sia I gene by the transient expression method showed that the -1146 to -646 region, which contains putative binding sites for transcription factors c-Ets-1, CREB, AP-1 and NF-${\kappa}B$, functions as the VPA-inducible promoter of hST8Sia I in SK-N-BE(2)-C cells. Site-directed mutagenesis and electrophoretic mobility shift assay indicated that the NF-${\kappa}B$ binding site at -731 to -722 was crucial for the VPA-induced expression of hST8Sia I in SK-N-BE(2)-C cells. In addition, the transcriptional activity of hST8Sia I induced by VPA in SK-N-BE(2)-C cells was strongly inhibited by SP600125, which is a c-Jun N-terminal kinase (JNK) inhibitor, and $G{\ddot{O}}6976$, which is a protein kinase C (PKC) inhibitor, as determined by RT-PCR (reverse transcription-polymerase chain reaction) and luciferase assays. These results suggest that VPA markedly modulated transcriptional regulation of hST8Sia I gene expression through PKC/JNK signal pathways in SK-N-BE(2)-C cells.

• Korean Journal of Biological Psychiatry
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• v.6 no.1
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• pp.67-73
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• 1999

The cAMP-dependent protein kinase(PKA) is an intracellular enzyme with serine-threonine kinase activity that plays a key role in cell growth, differentiation, and apoptosis in eukaryotes. In order to understand the PKA signal transduction pathway regulating cell life cycle and identify its role, we focused on the characterization of up-/down-regulated genes by PKA using the differential display polymerase chain reaction. Seven differentially expressed sequence tags(DEST) have been obtained. Among these DESTs, 2 DESTs were homologous to the sequence of genes from BLAST search result. KC1-5 DEST that was up-regulated in A123.7 cells was highly corresponded to mouse apoptosis-related gene(MA-3) or mouse mRNA for topoisomerase inhibitor suppressed(TIS). MA-3 was induced in various types of apoptosis, specially in NGF-deprived apoptotic PC12 cells. TIS was down-regulated in the RVC lymphoma cells incubated with topoisomerase inhibitor that induces DNA strand breakages. PG1-1 DEST that was highly expressed in PC12 cells was corresponded to transposon Tn10 3'-end. Tnansposon Tn10 was up-regulated in differentiated myeloblastic ML-1 cells by 12-O-tetradecanoylphorbol-13-acetate. This study illuminates that MA-3/TIS was down-regulated by PKA activity, and transposon Tn10 was up-regulated by it.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.16
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• pp.6581-6586
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• 2014

Background: The istone deacetylase (HDAC) inhibitor trichostatin A (TSA) is known to mediate the regulation of gene expression and antiproliferation activity in cancer cells. Kr$\ddot{u}$ppel-like factor 4 (klf4) is a zinc finger-containing transcription factor of the SP/KLF family, that is expressed in a variety of tissues and regulates cell proliferation, differentiation, tumorigenesis, and apoptosis. It may either either function as a tumor suppressor or an oncogene depending on genetic context of tumors. Aims: In this study, we tested the possibility that TSA may increase klf4 expression and cancer cell growth inhibition and apoptosis in SKOV-3 and A549 cells. Materials and Methods: The cytotoxicity of TSA was determined using the MTT assay test, while klf4 gene expression was assessed by real time PCR andto ability of TSA to induce apoptosis using a Vybrant Apoptosis Assay kit. Results: Our results showed that TSA exerted dose and time dependent cytotoxicity effect on SKOV-3 and A549 cells. Moreover TSA up-regulated klf4 expression. Flow cytometric analysis demonstrated that apoptosis was increased after TSA treatment. Conclusions: Taken together, this study showed that TSA increased klf4 expression in SKOV3 and A549 cell lines, consequently, klf4 may played a tumor-suppressor role by increasing both cell growth inhibition and apoptosis. This study sheds light on the details of molecular mechanisms of HDACI-induced cell cycle arrest and apoptosis.

• Journal of Korean Neurosurgical Society
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• v.59 no.3
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• pp.259-268
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• 2016

Objective : Accumulation of advanced glycation end-products (AGE) and mitochondrial glycation is importantly implicated in the pathological changes of the brain associated with diabetic complications, Alzheimer disease, and aging. The present study was undertaken to determine whether sildenafil, a type 5 phosphodiesterase type (PDE-5) inhibitor, has beneficial effect on neuronal cells challenged with AGE-induced oxidative stress to preserve their mitochondrial functional integrity. Methods : HT-22 hippocampal neuronal cells were exposed to AGE and changes in the mitochondrial functional parameters were determined. Pretreatment of cells with sildenafil effectively ameliorated these AGE-induced deterioration of mitochondrial functional integrity. Results : AGE-treated cells lost their mitochondrial functional integrity which was estimated by their MTT reduction ability and intracellular ATP concentration. These cells exhibited stimulated generation of reactive oxygen species (ROS), disruption of mitochondrial membrane potential, induction of mitochondrial permeability transition, and release of the cytochrome C, activation of the caspase-3 accompanied by apoptosis. Western blot analyses and qRT-PCR demonstrated that sildenafil increased the expression level of the heme oxygenase-1 (HO-1). CoPP and bilirubin, an inducer of HO-1 and a metabolic product of HO-1, respectively, provided a similar protective effects. On the contrary, the HO-1 inhibitor ZnPP IX blocked the effect of sildenafil. Transfection with HO-1 siRNA significantly reduced the protective effect of sildenafil on the loss of MTT reduction ability and MPT induction in AGE-treated cells. Conclusion : Taken together, our results suggested that sildenafil provides beneficial effect to protect the HT-22 hippocampal neuronal cells against AGE-induced deterioration of mitochondrial integrity, and upregulation of HO-1 is involved in the underlying mechanism.

• Advances in Traditional Medicine
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• v.10 no.4
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• pp.254-262
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• 2010

Artemisia capillaris (A. capillaries) is known to play roles in many cellular events, such as cell proliferation, differentiation, and apoptosis. We investigated the antifibrogenic efficacy of A. capillaris in the immortalized human hepatic stellate cell line LX2. Cell proliferation was determined by the MTT assay. Cell cycle was analyzed by the flow cytometry. Apoptotic cells were measured using a cell death detection ELISA. Caspase activity was detected by a colorimetric assay. The mRNA level of Bcl-2 and Bax mRNA were measured by real-time PCR. MEK and ERK protein were detected by Western blot analysis. We provide evidence that A. capillaris induces cell cycle arrest, apoptosis, and potently inhibits the mitogen-activated protein kinase pathway. A. capillaris inhibited cell proliferation of LX2 cells in a dose- and time-dependent manner, increased the apoptosis fraction at cell cycle analysis with an accompanying DNA fragmentation, and resulted in a significant decrease in Bcl-2 mRNA levels and an increase in Bax expression. Exposure of LX2 cells to A. capillaris induced caspase-3 activation, but co-treatment of A. capillaris with the pan-caspase inhibitor Z-VAD-FMK, and the caspase-3 inhibitor Z-DEVE-FMK, blocked apoptosis. A. capillaris down-regulated Mcl-1 protein levels and inhibited phosphorylation of MEK/ERK, suggesting that it mediates cell death in LX2 cells through the down-regulation of Mcl-1 protein via a MEK/ERK-independent pathway.

• International Journal of Oral Biology
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• v.39 no.1
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• pp.15-22
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• 2014

Aggregatibacter actinomycetemcomitans is an important pathogen in the development of localized aggressive periodontitis. Lipopolysaccharide (LPS) is a virulent factor of periodontal pathogens that contributes to alveolar bone loss and connective tissue degradation in periodontal disease. Our present study was designed to investigate the cytokine expression and signaling pathways regulated by A. actinomycetemcomitans LPS (Aa LPS). Cytokine gene expression profiling in RAW 264.7 cells was performed by microarray analyses. The cytokine mRNA and protein levels and related signaling pathways induced by Aa LPS were measured by RT-PCR, ELISA and western blotting. Microarray results showed that Aa LPS strongly induced the expression of NF-${\kappa}B$, NF-${\kappa}B$-related genes, inflammatory cytokines, TNF-${\alpha}$ and IL-$1{\beta}$ in RAW 264.7 cells. NF-${\kappa}B$ inhibitor pretreatment significantly reduced the levels of TNF-${\alpha}$ and IL-$1{\beta}$ mRNA and protein. In addition, the Aa LPS-induced TNF-${\alpha}$ and IL-$1{\beta}$ expression was inhibited by p38/JNK MAP kinase inhibitor pretreatment. These results show that Aa LPS stimulates TNF-${\alpha}$ and IL-$1{\beta}$ expression through NF-${\kappa}B$ and p38/JNK activation in RAW 264.7 cells, suggesting the essential role of this pathway in the pathogenesis of localized aggressive periodontitis.

• Journal of Physiology & Pathology in Korean Medicine
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• v.16 no.6
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• pp.1177-1183
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• 2002

We investigated the effects of Sabaek-san (SBS) water extract on the cell proliferation of human lung carcinoma A549 cells. SBS treatment resulted in the inhibition of cell proliferation in a concentration-dependent manner. This anti-proliferative effect of A549 cells by SBS treatment was associated with morphological changes such as membrane shrinking and cell rounding up. DNA flow cytometric histograms showed that population of G1 phase of the cell cycle was increased by SBS treatment in a concentration-dependent manner. SBS treatment induced a marked accumulation of tumor suppressor p53 and a concomitant induction of cyclin-dependent kinase (Cdk) inhibitor p21WAF1/CIP, which appears to be transcriptionally upregulated and is p53 dependent. In addition, SBS treatment resulted in down-regulation of cyclooxygenase-2 (COX-2) as determined by RT-PCR analysis. The present results indicated that SBS-induced inhibition of lung cancer cell proliferation is associated with the blockage of G1/S progression the induction of apoptosis.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.15
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• pp.6327-6330
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• 2015

Background: Glioblastoma is a highly aggressive and malignant brain tumor. Risk factors are largely unknown however, although several biomarkers have been identified which may support development, angiogenesis and invasion of tumor cells. One of these biomarkers is PAI-1.4G/5G and A-844G are two common polymorphisms in the gene promotor of PAI 1 that may be related to high transcription and expression of this gene. Studies have shown that the prevalence of the 4G and 844G allele is significantly higher in patients with some cancers and genetic disorders. Materials and Methods: We here assessed the association of 4G/5G and A-844G polymorphisms with glioblastoma cancer risk in Iranians in a case-control study. All 71 patients with clinically confirmed and 140 volunteers with no history and symptoms of glioblastoma as control group were screened for 4G/5G and A-844G polymorphisms of PAI-1, using ARMS-PCR. Genotype and allele frequencies of case and control groups were analyzed using the DeFinetti program. Results: Our results showed significant associations between 4G/5G (p=0.01824) and A-844G (p = 0.02012) polymorphisms of the PAI-1 gene with glioblastoma cancer risk in our Iranian population. Conclusions: The results of this study supporting an association of the PAI-1 4G/5G (p=0.01824) and A-844G (p = 0.02012) polymorphisms with increasing glioblastoma cancer risk in Iranian patients.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.20
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• pp.8595-8601
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• 2014

Background: miR-200a expression is frequently altered in numerous cancers. The aim of the present study was to determine the role of microRNA-200a in advanced ovarian carcinomas. Materials and Methods: We measured miR-200a expression in 72 matched normal ovarian tissues and advanced ovarian carcinomas, and also two ovarian carcinoma cell lines (SKOV3 and SKOV3.ip1 - the latter being more invasive and metastatic than the parental SKOV3) by stem-loop real-time RT-PCR based on TaqMan microRNA assay using U6 as a reference. Levels of miR-200a expression were compared by disease stage, tumor grade, histology, and lymph node involvement. To evaluate the role of microRNA-200a, cell proliferation and invasion of SKOV-3 and SKOV-3.ip1 were analyzed with miR-200a inhibitor/mimic transfected cells. Results: Of 72 paired samples, 65 cancer tissues overexpressed microRNA-200a greater than two fold in comparison with matched normal epithelium. Specifically, patients with lymph node metastasis showed significant elevation. The level correlated with clinicopathological features, including high tumor grade, late disease stage, most notably with lymph node metastasis, but not with tumor histology. In addition, SKOV-3.ip1 cells also overexpressed miR-200a compared with SKOV-3, and miR-200a inhibitor transfected SKOV-3.ip1 cells showed significant reduction in cellular proliferation and invasion, while a miR-200a mimic stimulated the opposite behavior. Conclusions: We provide definitive evidence that miR-200a is up-regulated in a significant proportion of advanced ovarian carcinomas, and that elevated miR-200a expression facilitates tumor progression. Our findings support the notion that miR-200a is an onco-microRNA for ovarian cancer, and elevation is a useful potential diagnostic indicator. This study also provides a solid basis for further functional analysis of miR-200a in advanced ovarian cancer.