Publications by authors named "Seong-il Suh"

76 Publications

Miconazole induces autophagic death in glioblastoma cells via reactive oxygen species-mediated endoplasmic reticulum stress.

Oncol Lett 2021 Apr 25;21(4):335. Epub 2021 Feb 25.

Department of Microbiology, School of Medicine, Keimyung University, Dalseogu, Daegu 42601, Republic of Korea.

Miconazole is an antifungal agent that is used for the treatment of superficial mycosis. However, recent studies have indicated that miconazole also exhibits potent anticancer effects in various types of cancer via the activation of apoptosis. The main aim of the present study was to observe the effect of miconazole on autophagic cell death of cancer cells. Cytotoxicity was measured by viable cell counting after miconazole treatment in glioblastoma cell lines (U343MG, U87MG and U251MG). Induction of autophagy was analyzed by examining microtubule-associated protein light chain 3 (LC3)-II expression levels using western blotting and by detecting GFP-LC3 translocation using a fluorescence microscope. Intracellular ROS production was measured using a fluorescent probe, 2',7'-dichlorodihydrofluorescein diacetate. It was found that miconazole induced autophagic cell death in the U251MG glioblastoma cell line via the generation of reactive oxygen species (ROS) and endoplasmic reticulum (ER) stress response. An association between miconazole-induced ROS production and autophagy was also identified; in particular, pretreatment of the cells with a ROS scavenger resulted in a reduction in the levels of LC3-II. Miconazole-induced ER stress was associated with increases in binding immunoglobulin protein (BiP), inositol-requiring enzyme 1α (IRE1α) and CHOP expression, and phospho-eIF2α levels. The inhibition of ER stress via treatment with 4-phenylbutyric acid or BiP knockdown reduced miconazole-induced autophagy and cell death. These findings suggest that miconazole induces autophagic cell death by inducing an ROS-dependent ER stress response in U251MG glioma cancer cells and provide new insights into the potential antiproliferative effects of miconazole.
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http://dx.doi.org/10.3892/ol.2021.12596DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7933777PMC
April 2021

Usefulness of bile as a biomarker via ferroptosis and cysteine prenylation in cholangiocarcinoma; role of diagnosis and differentiation from benign biliary disease.

Surg Oncol 2020 Sep 23;34:174-181. Epub 2020 Apr 23.

Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, Keimyung University Dongsan Medical Center, Daegu, South Korea.

Background: Cholangiocarcinoma (CCA) is a malignant cancer of the biliary tract with a poor prognosis. Herein, we investigated possible mechanism of extrahepatic CCA (eCCA) by dysregulated iron metabolism and post-translational modifications (PTMs). Further, we evaluated potential biomarkers in the bile fluid for diagnosis of eCCA and differentiation between eCCA and benign biliary disease.

Methods: From August 2018 to April 2019, we obtained bile fluids from 46 patients; 28 patients with eCCA (eCCA group) and 18 patients with common bile duct stone (Control group) via percutaneous transhepatic biliary drainage. We examined the levels of reduced glutathione (GSH), peroxide, ferrous iron [Fe], glutathione peroxidase (GP) and farnesyl transferase/geranylgeranyl transferase type-1 subunit alpha (FNTA) concentration in bile fluids to clarify the mechanism of ferroptosis and prenylation.

Results: The remarkable difference of PTMs was that FNTA which means prenylated cysteine as regulator was significantly decreased in eCCA than that of control. In addition, level of GSH, peroxide, GP and ferrous iron [Fe] were significantly depleted in eCCA than control. These results demonstrate that PTM, dysregulated iron metabolism and GP-regulated ferroptosis with GSH depletion through cysteine modification in bile are possible mechanisms of eCCA. Liquid Chromatography (LC)-Mass Spectrometry (MS) analysis, several oncogenic pathways including MYC target, apoptosis, fatty acid metabolism, P53 and mTORC1 were enriched in eCCA.

Conclusions: In conclusion, redox-dependent modification of cysteine and ferroptosis in bile fluids are possible mechanisms of eCCA. Several protein and oncogenic pathways related to PTM which are seen in eCCA tissues were also enriched in bile fluids. It suggests that bile fluid represents the oncogenic characteristics of eCCA tissues. Therefore, bile fluids have a role of a biomarker for diagnosis in eCCA, especially, differentiation of eCCA from benign biliary stricture.
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http://dx.doi.org/10.1016/j.suronc.2020.04.019DOI Listing
September 2020

Juglone induces cell death of Acanthamoeba through increased production of reactive oxygen species.

Exp Parasitol 2015 Dec 7;159:100-6. Epub 2015 Sep 7.

Department of Microbiology, Keimyung University School of Medicine, Daegu, Republic of Korea. Electronic address:

Juglone (5-hydroxy-1,4-naphthoquinone) is a major chemical constituent of Juglans mandshruica Maxim. Recent studies have demonstrated that juglone exhibits anti-cancer, anti-bacterial, anti-viral, and anti-parasitic properties. However, its effect against Acanthamoeba has not been defined yet. The aim of this study was to investigate the effect of juglone on Acanthamoeba. We demonstrate that juglone significantly inhibits the growth of Acanthamoeba castellanii at 3-5 μM concentrations. Juglone increased the production of reactive oxygen species (ROS) and caused cell death of A. castellanii. Inhibition of ROS by antioxidant N-acetyl-l-cysteine (NAC) restored the cell viability. Furthermore, our results show that juglone increased the uptake of mitochondrial specific dye. Collectively, these results indicate that ROS played a significant role in the juglone-induced cell death of Acanthamoeba.
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http://dx.doi.org/10.1016/j.exppara.2015.09.005DOI Listing
December 2015

Biofilm Formation and Colistin Susceptibility of Acinetobacter baumannii Isolated from Korean Nosocomial Samples.

Microb Drug Resist 2015 Aug 25;21(4):452-7. Epub 2015 Feb 25.

2 Department of Microbiology, Keimyung University School of Medicine , Daegu, Republic of Korea.

Biofilm formation, a virulence factor of Acinetobacter baumannii, is associated with long-term survival in hospital environments and provides resistance to antibiotics. Standard tests for antibiotic susceptibility involve analyzing bacteria in the planktonic state. However, the biofilm formation ability can influence antibiotic susceptibility. Therefore, here, the biofilm formation ability of A. baumannii clinical isolates from Korea was investigated and the susceptibility of biofilm and planktonic bacteria to colistin was compared. Of the 100 clinical isolates examined, 77% exhibited enhanced biofilm formation capacity relative to a standard A. baumannii strain (ATCC 19606). Differences between the minimal inhibitory concentrations and minimal biofilm-inhibitory concentrations of colistin were significantly greater in the group of A. baumannii that exhibited enhanced biofilm formation than the group that exhibited less ability for biofilm formation. Thus, the ability to form a biofilm may affect antibiotic susceptibility and clinical failure, even when the dose administered is in the susceptible range.
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http://dx.doi.org/10.1089/mdr.2014.0236DOI Listing
August 2015

Tigecycline inhibits proliferation of Acanthamoeba castellanii.

Parasitol Res 2015 Mar 7;114(3):1189-95. Epub 2015 Jan 7.

Department of Microbiology, Keimyung University School of Medicine, 1095 Dalgubeol-daero, Dalseo-gu, Daegu, 704-701, Republic of Korea.

Acanthamoeba is an opportunistic protozoan parasite responsible for different diseases in humans, such as granulomatous amoebic encephalitis and amoebic keratitis. Tigecycline, a third-generation tetracycline antibiotic, has potential activity to treat most of the antibiotic resistant bacterial infections. The effects of tigecycline in eukaryotic cells as well as parasites are less well studied. In the present study, we tested the effects of tigecycline on trophozoites of Acanthamoeba castellanii. The inhibitory effect of tigecycline on Acanthamoeba was determined by resazurin reduction and trypan blue exclusion assays. We found that tigecycline significantly inhibited the growth of Acanthamoeba (46.4 % inhibition at the concentration of 100 μM) without affecting cell viability and induction of encystation, whereas other tetracycline groups of antibiotics such as tetracycline and doxycycline showed no inhibitory effects. Furthermore, tigecycline decreased cellular adenosine triphosphate (ATP) level by 26 % than the control and increased mitochondrial mass, suggesting mitochondrial dysfunction in tigecycline-treated cells. These findings suggest that mitochondrial dysfunction with decreased ATP production might play an important mechanism of tigecycline in suppression of Acanthamoeba proliferation.
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http://dx.doi.org/10.1007/s00436-014-4302-1DOI Listing
March 2015

Genome-wide association study of medication adherence in chronic diseases in the korean population.

Genomics Inform 2014 Sep 30;12(3):121-6. Epub 2014 Sep 30.

Department of Microbiology, Keimyung University School of Medicine, Daegu 704-701, Korea.

Medication adherence is generally defined as the extent of voluntary cooperation of a patient in taking medicine as prescribed. Adherence to long-term treatment with chronic disease is essential for reducing disease comorbidity and mortality. However, medication non-adherence in chronic disease averages 50%. This study was conducted a genome-wide association study to identify the genetic basis of medication adherence. A total of 235 medication non-adherents and 1,067 medication adherents with hypertension or diabetes were used from the Korean Association Resource project data according to the self-reported treatment status of each chronic disease, respectively. We identified four single nucleotide polymorphisms with suggestive genome-wide association. The most significant single nucleotide polymorphism was rs6978712 (chromosome 7, p = 4.87 × 10(-7)), which is located proximal to the GCC1 gene, which was previously implicated in decision-making capability in drug abusers. Two suggestive single nucleotide polymorphisms were in strong linkage disequilibrium (r(2) > 0.8) with rs6978712. Thus, in the aspect of decision-making in adherence behavior, the association between medication adherence and three loci proximal to the GCC1 gene seems worthy of further research. However, to overcome a few limitations in this study, defining the standardized phenotype criteria for self-reported adherence should be performed before replicating association studies.
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http://dx.doi.org/10.5808/GI.2014.12.3.121DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4196376PMC
September 2014

Chloroquine has a cytotoxic effect on Acanthamoeba encystation through modulation of autophagy.

Antimicrob Agents Chemother 2014 Oct 11;58(10):6235-41. Epub 2014 Aug 11.

Department of Microbiology, Keimyung University School of Medicine, Daegu, Republic of Korea

Encystation of Acanthamoeba castellanii is associated with resistance to chemotherapeutic agents. Blocking the encystation process could potentiate the efficacy of chemotherapeutic agents and biocides. During encystation, autophagy is highly stimulated and required for proper encystation of Acanthamoeba. In this study, the cytotoxic effect of chloroquine, a well-known autophagy-inhibitory drug, was tested in A. castellanii. Chloroquine was able to selectively reduce cell survival during the encystation of A. castellanii. However, A. castellanii trophozoites and mature cysts were resistant to chloroquine. Chloroquine treatment led to an increase in the number and size of lysosomes in encysting cells. Moreover, chloroquine inhibited the degradation of long-lived proteins in the encysting cells. Decreased autophagic flux, indicated by an increased number of lysosomes and decreased degradation of long-lived proteins, may be the mechanism by which cell death is induced by chloroquine in encysting Acanthamoeba. These results suggest a potential novel therapeutic application of chloroquine as an anti-Acanthamoeba drug. Our findings also suggest that targeting autophagy could be a therapeutic strategy against Acanthamoeba infection.
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http://dx.doi.org/10.1128/AAC.03164-14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4187977PMC
October 2014

Translational suppression of HIF-1α by miconazole through the mTOR signaling pathway.

Cell Oncol (Dordr) 2014 Aug 29;37(4):269-79. Epub 2014 Jul 29.

Department of Microbiology, Keimyung University School of Medicine, 1095 Dalgubeol-daero, Dalseo-gu, Daegu, 704-701, Republic of Korea.

Background: Miconazole is an imidazole antifungal agent that has amply been used in the treatment of superficial mycosis. Preliminary data indicate that miconazole may also induce anticancer effects. As yet, however, little is known about the therapeutic efficacy of miconazole on cancer and the putative mechanism(s) involved. Here, we show that miconazole suppresses hypoxia inducible factor-1α (HIF-1α) protein translation in different cancer-derived cells.

Methods: The effect of miconazole on HIF-1α expression was examined by Western blotting and reverse transcriptase polymerase chain reaction assays in human U87MG and MCF-7 glioma and breast cancer-derived cell lines, respectively. The transcriptional activity of the HIF-1 complex was confirmed using a luciferase assay. To assess whether angiogenic factors are increased under hypoxic conditions in these cells, vascular endothelial growth factor (VEGF) levels were measured by ELISA. Metabolic labeling was performed to examine HIF-1α protein translation and global protein synthesis. The role of the mammalian target of rapamycin (mTOR) signaling pathway was examined to determine translation regulation of HIF-1α after miconazole treatment.

Results: Miconazole was found to suppress HIF-1α protein expression through post-transcriptional regulation in U87MG and MCF-7 cells. The suppressive effect of HIF-1α protein synthesis was found to be due to inhibition of mTOR. Miconazole significantly inhibited the transcriptional activity of the HIF-1 complex and the expression of its target VEGF. Moreover, miconazole was found to suppress global protein synthesis by inducing phosphorylation of the translation initiation factor 2α (eIF2α).

Conclusion: Our data indicate that miconazole plays a role in translational suppression of HIF-1α. We suggest that miconazole may represent a novel therapeutic option for the treatment of cancer.
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http://dx.doi.org/10.1007/s13402-014-0182-8DOI Listing
August 2014

Identification of lysosomotropic compounds based on the distribution and size of lysosomes.

Biochem Biophys Res Commun 2014 Jul 27;450(1):189-94. Epub 2014 May 27.

Department of Microbiology, School of Medicine, Keimyung University, Daegu, Republic of Korea; Institute for Cancer Research, School of Medicine, Keimyung University, Daegu, Republic of Korea. Electronic address:

Lysosomal accumulation of drugs with their specific physicochemical properties is of key importance to drug distribution in the body. Several attempts have been made to treat various human diseases by employing the accumulation of lysosomal drugs, and many methods to identify lysosomal accumulation of drugs have been proposed. Among those, the use of high-content screening has increased tremendously because of improved efficiency and accuracy as well as the development of automatic image acquisition and analytical techniques. Conventional methods to identify lysosomal accumulation of drugs by evaluating changes in the lysosomal area are unable to maximize the advantages of phenotypic high-content screening. Lysosomal distribution and the size of lysosomes are affected by lysosomal accumulating drugs. Therefore, we present image acquisition conditions and analytical methods to utilize lysosomal distribution and size as parameters for identifying lysosomal accumulating drugs. These two parameters will help to improve the reliability of the screening methods for identifying lysosomal accumulation of drugs by maximizing usage of information from image-based screening.
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http://dx.doi.org/10.1016/j.bbrc.2014.05.091DOI Listing
July 2014

Minocycline inhibits angiogenesis in vitro through the translational suppression of HIF-1α.

Arch Biochem Biophys 2014 Mar 8;545:74-82. Epub 2014 Jan 8.

Department of Microbiology, Keimyung University School of Medicine, Daegu, Republic of Korea. Electronic address:

Minocycline was recently found to be effective against cancer. However, the precise molecular mechanisms of minocycline in cancer are poorly understood. Hypoxia-inducible factor-1 (HIF-1, a heterodimeric transcription factor composed of HIF-1α and β) activates the transcription of genes that are involved in angiogenesis in cancer. In this study, we found that minocycline significantly inhibits HIF-1α protein expression and suppresses HIF-1 transcriptional activity. The tube formation assay showed that minocycline has anti-angiogenic activity and suppresses hypoxia-induced vascular endothelial growth factor (VEGF) expression. The metabolic labeling assay showed that minocycline reduces HIF-1α protein translation and global protein synthesis. In addition, minocycline suppresses mTOR signaling and increases the phosphorylation of eIF2α, which is known to be related to the translational regulation of HIF-1α expression. These findings collectively indicate that minocycline is a potential inhibitor of HIF-1α and provide new insight into the discovery of drugs for cancer treatment.
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http://dx.doi.org/10.1016/j.abb.2013.12.023DOI Listing
March 2014

Pentamidine reduces expression of hypoxia-inducible factor-1α in DU145 and MDA-MB-231 cancer cells.

Cancer Lett 2011 Apr 12;303(1):39-46. Epub 2011 Feb 12.

Chronic Disease Research Center, School of Medicine, Keimyung University, Daegu 704-701, Republic of Korea.

Pentamidine is an aromatic diamine used for the treatment of human protozoa infections. Recently, pentamidine has been reported to exhibit anticancer properties. In this study, we report that pentamidine inhibits expression of hypoxia-inducible factor (HIF)-1α in cancer cells. Pentamidine decreased HIF-1α protein translation and enhanced its protein degradation in DU145 prostate cancer and MDA-MB-231 breast cancer cells. In parallel with reduction of de novo synthesis of HIF-1α, pentamidine was able to suppress global protein translation, an effect accompanied by the reduction of eIF4F complex formation and also the induction of eIF2α phosphorylation. These results show that pentamidine is a potential inhibitor of HIF-1α and its potential as a cancer therapeutic reagent warrants further study.
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http://dx.doi.org/10.1016/j.canlet.2011.01.008DOI Listing
April 2011

Manganese-mediated up-regulation of HIF-1alpha protein in Hep2 human laryngeal epithelial cells via activation of the family of MAPKs.

Toxicol In Vitro 2010 Jun 10;24(4):1208-14. Epub 2010 Feb 10.

Department of Medical Genetic Engineering, Keimyung University School of Medicine, 194 Dongsan-dong, Jung-gu, Daegu 700-712, South Korea.

High exposure of manganese is believed to be a risk factor for respiratory diseases. Evidence suggests that overexpression of HIF-1alpha transcription factor is linked to pulmonary inflammation and vascular change. In this study, we investigated the effect of manganese-chloride (manganese) on expression and activity of HIF-1alpha in various human airway cells, including Hep2 (laryngeal), H292 (bronchial), and A549 (lung). Profoundly, while manganese treatment led to low or little effect on induction of HIF-1alpha protein in H292 or A549 cells, it strongly induced HIF-1alpha protein expression in Hep2 cells. Mn treatment, however, did not induce HIF-1alpha mRNA expression in Hep2 cells. Luciferase experiments further demonstrated that manganese treatment increased the HRE-driven luciferase activity, suggesting that the induced HIF-1 is functional. Interestingly, manganese treatment also caused activation of p38 MAPK, JNK-1/2, ERK-1/2, and ATF-2, but not of PKB or NF-kappaB in Hep2 cells. Importantly, the manganese-mediated expression and activity of HIF-1alpha protein were largely blocked by treatment with the inhibitor of p38 MAPK (SB203580), JNK-1/2 (SP600125), or ERK-1/2 (PD98059), suggesting roles of these MAPKs in the manganese-induced HIF-1alpha protein expression and activity. Moreover, treatment with SP600125 or SB203580, but not PD98059, had partial inhibitory effects on the stability of HIF-1alpha protein induced by manganese, suggesting that p38 MAPK and JNK-1/2 also contribute to the Mn-mediated HIF-1alpha protein stability. These results suggest that manganese is able to up-regulate HIF-1alpha at the protein level in Hep2 cells and the up-regulation is largely dependent of activities of the family of MAPKs.
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http://dx.doi.org/10.1016/j.tiv.2010.02.008DOI Listing
June 2010

Differential effects of 5-fluorouracil on glucose transport and expressions of glucose transporter proteins in gastric cancer cells.

Anticancer Drugs 2010 Mar;21(3):270-6

Department of Biotechnology, School of Life Sciences and Biotechnology, Korea University, Seoul, Korea.

Although 5-fluorouracil (5-FU) is a widely used chemotherapeutic agent in the treatment of gastric cancer, the underlying mechanism for 5-FU resistant phenotype, has yet to be elucidated. We hypothesized that the sensitivity of gastric cancer to 5-FU treatment might be related to the rate of glucose transport (GLUT), and investigated the expressions of GLUT1, 2, 3, and 4 in two different gastric cancer cells (SNU-216, moderately differentiated gastric adenocarcinoma; and SNU-668, signet ring cell gastric carcinoma). Immunohistochemistry of GLUT1 and GLUT4 and immunoblot analysis of glycogen synthase kinase 3 were also performed. Hexokinase activity was measured. We found that 5-FU suppressed glucose uptake in SNU-216, while it stimulated GLUT in SNU-668. Further analysis revealed that 5-FU decreased the expression levels of GLUT1, 2, and 4 in SNU-216 cells and increased the expression levels of GLUT1, 2, and 4 in SNU-668 cells. Consistent with GLUT expression levels, immunohistochemistry analysis showed that 5-FU increased GLUT1 and GLUT4 levels in SNU-216 and decreased GLUT1 and GLUT4 levels in SNU-668. We also observed that glycogen synthase kinase 3 activity was decreased in SNU-216 and increased in SNU-668 with 5-FU treatment. No significant difference in hexokinase activities was observed with 5-FU treatment. Taken together, these results suggest that 5-FU exerts differential effects on GLUT depending on gastric cancer cell types, which may indicate a possible explanation, at least in part, for the differing responses to 5-FU chemotherapy in gastric cancer.
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http://dx.doi.org/10.1097/CAD.0b013e328334562cDOI Listing
March 2010

Silibinin inhibits expression of HIF-1alpha through suppression of protein translation in prostate cancer cells.

Biochem Biophys Res Commun 2009 Dec 22;390(1):71-6. Epub 2009 Sep 22.

Chronic Disease Research Center, School of Medicine, Keimyung University, Daegu 700-712, Republic of Korea.

Silibinin is a polyphenolic flavonoid isolated from the milk thistle (Silybum marianum) and is reported to exhibit anticancer properties. Recently, it has been reported that silibinin inhibits hypoxia-inducible factor-1alpha (HIF-1alpha) expression in cancer cells. However, the precise mechanism by which silibinin decreases HIF-1 expression is not fully understood. In this study, silibinin inhibited basal and hypoxia induced expression levels of HIF-1alpha protein in LNCaP and PC-3 prostate cancer cells, while the rate of HIF-1alpha protein degradation and mRNA levels were not affected. We found that the decrease in HIF-1 protein by silibinin correlated with suppression of de novo synthesis of HIF-1alpha protein. Silibinin inhibited global protein synthesis coincided with reduction of eIF4F complex formation and induction of phosphorylation of the translation initiation factor 2alpha (eIF-2alpha) which can cause inhibition of general protein synthesis. These results suggest that silibinin's activity to inhibit HIF-1alpha protein expression is associated with the suppression of global protein translation.
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http://dx.doi.org/10.1016/j.bbrc.2009.09.068DOI Listing
December 2009

Differential down-regulation of COX-2 and MMP-13 in human skin fibroblasts by glucosamine-hydrochloride.

J Dermatol Sci 2009 Oct 4;56(1):43-50. Epub 2009 Aug 4.

Department of Medical Genetic Engineering, Keimyung University School of Medicine, 194 Dongsan-dong, Jung-gu, Daegu, 700-712, South Korea.

Background: Evidence suggests anti-inflammatory effects of glucosamine (GS) on inflammatory diseases. COX-2 is an enzyme to produce prostaglandins. MMPs are the family of matrix metalloproteinases degradable of ECM. Excess expression of COX-2 or MMPs involves in skin inflammation.

Objective: We evaluated whether GS-HCl modulates expression of COX-2 and/or MMPs by IL-1beta or PMA in human skin fibroblasts (HSF) or keratinocytes (HaCaT).

Methods: HSF or HaCaT cells were exposed to IL-1beta or PMA without or with GS-HCl. COX-2 or MMPs protein and mRNA expression, respectively, were analyzed by Western blot and RT-PCR. MTS assay was utilized to assess the cytotoxicity of GS-HCl on HSF cells.

Results: In HSF cells, IL-1beta treatment induced COX-2 and MMP-13 expressions in association with activation of ERKs, p38 MAPK, JNKs, and NF-kappaB. PMA treatment also induced COX-2 and MMP-13 expressions in association with p38 MAPK activation. Of interest, treatment with GS-HCl (10mM) led to blockage of p38 MAPK activation, accumulation of 66kDa COX-2 protein variant (without affecting COX-2 mRNA expression), and transcriptional down-regulation of MMP-13 in the IL-1beta- or PMA-treated HSF cells. Distinctly, pharmacological inhibition of p38 MAPK with SB203580 was associated with transcriptional down-regulation of COX-2 and MMP-13 in the IL-1beta- or PMA-treated HSF cells. In addition, the GS-HCl-mediated COX-2 protein modification was observed in both endogenous and PMA-induced COX-2 in HaCaT cells.

Conclusions: GS-HCl differentially down-regulates COX-2 and MMP-13 expression in the IL-1beta- or PMA-treated human skin fibroblasts via the p38 MAPK-independent COX-2 translational inhibition and the p38 MAPK-dependent MMP-13 transcriptional suppression, respectively.
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http://dx.doi.org/10.1016/j.jdermsci.2009.06.017DOI Listing
October 2009

Melatonin down-regulates HIF-1 alpha expression through inhibition of protein translation in prostate cancer cells.

J Pineal Res 2009 May 25;46(4):415-21. Epub 2009 Mar 25.

Chronic Disease Research Center, School of Medicine, Keimyung University, Daegu, Korea.

Melatonin, the main secretory product of the pineal gland, has been shown to exert an oncostatic activity in cancer cells. Recently, several studies have shown that melatonin has antiangiogenic properties. However, the mechanism by which melatonin exerts antiangiogenenic effects is not understood. Hypoxia inducible factor (HIF)-1 is a transcription factor which mediates adaptive response to changes in tissue oxygenation. HIF-1 is a heterodimer formed by the association of a constitutively expressed HIF-1 beta subunit and a HIF-1 alpha subunit, the expression of which is highly regulated. In this study, pharmacologic concentrations of melatonin was found to inhibit expression of HIF-1 alpha protein under both normoxic and hypoxic conditions in DU145, PC-3, and LNCaP prostate cancer cells without affecting HIF-1 alpha mRNA levels. Consistent with the reduction in HIF-1 alpha protein levels, melatonin inhibited HIF-1 transcriptional activity and the release of vascular endothelial growth factor. We found that the suppression of HIF-1 alpha expression by melatonin correlated with dephosphorylation of p70S6K and its direct target RPS6, a pathway known to regulate HIF-1 alpha expression at the translational level. Metabolic labeling assays indicated that melatonin inhibits de novo synthesis of HIF-1 alpha protein. Taken together, these results suggest that the pharmacologic concentration of melatonin inhibits HIF-1 alpha expression through the suppression of protein translation in prostate cancer cells.
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http://dx.doi.org/10.1111/j.1600-079X.2009.00678.xDOI Listing
May 2009

D-glucosamine down-regulates HIF-1alpha through inhibition of protein translation in DU145 prostate cancer cells.

Biochem Biophys Res Commun 2009 Apr 28;382(1):96-101. Epub 2009 Feb 28.

Chronic Disease Research Center, School of Medicine, Keimyung University, 194 Dongsan-Dong, Jung-Gu, Daegu 700-712, Republic of Korea.

D-glucosamine has been reported to inhibit proliferation of cancer cells in culture and in vivo. In this study we report a novel response to D-glucosamine involving the translation regulation of hypoxia inducible factor (HIF)-1alpha expression. D-glucosamine caused a decreased expression of HIF-1alpha under normoxic and hypoxic conditions without affecting HIF-1alpha mRNA expression in DU145 prostate cancer cells. D-glucosamine inhibited HIF-1alpha accumulation induced by proteasome inhibitor MG132 and prolyl hydroxylase inhibitor DMOG suggesting D-glucosamine reduces HIF-1alpha protein expression through proteasome-independent pathway. Metabolic labeling assays indicated that D-glucosamine inhibits translation of HIF-1alpha protein. In addition, D-glucosamine inhibited HIF-1alpha expression induced by serum stimulation in parallel with inhibition of p70S6K suggesting D-glucosamine inhibits growth factor-induced HIF-1alpha expression, at least in part, through p70S6K inhibition. Taken together, these results suggest that D-glucosamine inhibits HIF-1alpha expression through inhibiting protein translation and provide new insight into a potential mechanism of the anticancer properties of D-glucosamine.
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http://dx.doi.org/10.1016/j.bbrc.2009.02.129DOI Listing
April 2009

Sanguinarine induces apoptosis in A549 human lung cancer cells primarily via cellular glutathione depletion.

Toxicol In Vitro 2009 Mar 24;23(2):281-7. Epub 2008 Dec 24.

Department of Medical Genetic Engineering, Keimyung University School of Medicine, 194 Dongsan-dong, Jung-gu, Daegu 700-712, Republic of Korea.

Sanguinarine is a plant-derived benzophenanthridine alkaloid and has been shown to possess anti-tumor activities against various cancer cells. In this study, we investigated whether sanguinarine induces apoptosis in A549 human lung cancer cells. Treatment of A549 cells with sanguinarine induced apoptosis in a dose- and time-dependent manner. Treatment with sanguinarine led to activation of caspases and MAPKs as well as increased MKP-1 expression. Importantly, pretreatment with z-VAD-fmk, a pan caspase inhibitor suppressed the sanguinarine-induced apoptosis in A549 cells. Moreover, pretreatment with NAC, a sulfhydryl group-containing reducing agent strongly suppressed the apoptotic response and caspase activation to sanguinarine. However, the sanguinarine-mediated cytotoxicity in A549 cells was not protected by pharmacological inhibition of MAPKs or MKP-1 siRNA-mediated knockdown of MKP-1. These results collectively suggest that sanguinarine induces apoptosis in A549 cells through cellular glutathione depletion and the subsequent caspase activation.
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http://dx.doi.org/10.1016/j.tiv.2008.12.013DOI Listing
March 2009

Global gene expression patterns and induction of innate immune response in human laryngeal epithelial cells in response to Acinetobacter baumannii outer membrane protein A.

FEMS Immunol Med Microbiol 2008 Oct 9;54(1):45-52. Epub 2008 Jul 9.

Department of Pharmacology, Eulji University School of Medicine, Korea.

The outer membrane protein A of Acinetobacter baumannii (AbOmpA) is an important pathogen-associated molecular pattern that induces host cell death. We determined the gene expression profiles of human laryngeal epithelial HEp-2 cells in response to the sublethal concentration of recombinant AbOmpA (rAbOmpA) and investigated the molecular mechanisms by which rAbOmpA induces an innate immune response. The microarray analysis showed that rAbOmpA sequentially regulated a relatively small set of genes, including those associated with signal transductions and molecules involved in immune response. Among the differentially expressed genes involved in innate immune responses, the surface expression of Toll-like receptor 2 and the production of inducible nitric oxide synthase (iNOS) were prominently observed. However, rAbOmpA did not induce the production of proinflammatory cytokines and chemokines. rAbOmpA activated c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase mitogen-activated protein kinases (MAPKs). Inhibition of JNK MAPK suppressed iNOS production in the rAbOmpA-treated HEp-2 cells. These results suggest that interaction of laryngeal epithelial cells with AbOmpA has a significant impact on the induction of innate immunity during the early stages of A. baumannii infection.
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http://dx.doi.org/10.1111/j.1574-695X.2008.00446.xDOI Listing
October 2008

Cadmium specifically induces MKP-1 expression via the glutathione depletion-mediated p38 MAPK activation in C6 glioma cells.

Neurosci Lett 2008 Aug 23;440(3):289-93. Epub 2008 May 23.

Chronic Disease Research Center, Keimyung University School of Medicine, 194 Dongsan-dong, Jung-gu, Daegu, Republic of Korea.

Cadmium is a toxic heavy metal and an environmental pollutant. Mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1) is a negative regulator of the family of MAPK. In this study, we investigated the effect of heavy metals on MKP-1 expression in C6 rat glioma cells. Cadmium treatment induced MKP-1 at both protein and mRNA levels while cobalt or manganese treatment did not, suggesting the specificity. Cadmium treatment also depleted intracellular GSH and activated p38 MAPK, JNKs, and AKT. Profoundly, pretreatment with thiol-containing compounds NAC or GSH, but not vitamin E, blocked GSH depletion, 38 MAPK activation and MKP-1 expression by cadmium. Moreover, pharmacological inhibition of p38 MAPK by SB203580 suppressed the cadmium-induced MKP-1. Collectively, these results demonstrate that cadmium specifically induces MKP-1 by transcriptional up-regulation in C6 cells in a mechanism associated with the glutathione depletion-dependent p38 MAPK activation.
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http://dx.doi.org/10.1016/j.neulet.2008.05.064DOI Listing
August 2008

The significance of gastric juice analysis for a positive challenge by a standard oral challenge test in typical cow's milk protein-induced enterocolitis.

J Korean Med Sci 2008 Apr;23(2):251-5

Department of Pediatrics, Institute for Medical Science, Dongsan Medical Center, Keimyung University School of Medicine, Daegu, Korea.

This study was performed to investigate the significance of gastric juice analysis (GJA) as a diagnostic criterion of a positive challenge in a standard oral cow's milk challenge (OCC) to confirm typical cow's milk protein-induced enterocolitis (CMPIE). Data from 16 CMPIE patients (aged 14 to 44 days) were analyzed. A standard OCC was openly executed using 0.15 g/kg of protein. Three symptoms (vomiting, lethargy, and bloody or pus-like stool), and four laboratory findings (GJA [3 hr], changes in peripheral blood absolute neutrophil count [ANC] [6 hr], C-reactive protein [6 hr], and stool smear test for occult blood or leukocytes) were observed after OCC. Before OCC, baseline studies were conducted; a stool smear test, blood sampling, and GJA. Positive OCC results were; vomiting (87.5%) (observed 1-3 hr after OCC), lethargy (62.5%) (1-3 hr), bloody or pus-like stool (43.8%) (6-10 hr), abnormal GJA (93.8%), an ANC rise >3,500 cells/microL (93.8%), and an abnormal stool smear test (75.0%). A single GJA test after a standard OCC is a sensitive diagnostic criterion of a positive challenge, and may provide an early confirmatory diagnosis of CMPIE. An investigation of positive OCC outcomes helps to find out a diagnostic algorithm of criteria of a positive challenge in CMPIE.
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http://dx.doi.org/10.3346/jkms.2008.23.2.251DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2526446PMC
April 2008

Indexes of suspicion of typical cow's milk protein-induced enterocolitis.

J Korean Med Sci 2007 Dec;22(6):993-7

Department of Pediatrics, Dongsan Medical Center, Keimyung University School of Medicine, Daegu, Korea.

This study was performed to identify clinical factors that facilitate the diagnosis of typical cow's milk protein-induced enterocolitis (CMPIE). Data from 142 consecutive patients (aged 15 to 45 days, cow's milk formula- or cow's milk and breast milk mixed-fed) admitted due to vomiting and/or diarrhea were retrospectively analyzed. These 142 subjects were divided into three groups: the CMPIE, infection, and non-infection group. Each group was composed of 16 (11.3%), 102 (71.8%), and 24 (16.9%) patients, respectively. On admission, poor weight gain (p=0.003), hypoalbuminemia (p=0.035), peripheral leukocytosis (p=0.012), and metabolic acidosis (p=0.015) were found to be more significant in the CMPIE group than those in other two groups. In CMPIE, serum albumin levels decreased from 3.3+/-0.9 g/dL on admission to 2.6+/-0.3 g/dL during admission (p<0.05), and methemoglobinemia was observed in 3 patients (18.8%) (p=0.012). Multiple logistic regression analysis showed that the independent predictors of CMPIE versus the infection group were failure to gain weight (OR, 10.75 [95% CI, 1.53-66.12]) (p= 0.014) and hypoalbuminemia (OR, 9.53 [95% CI, 1.62-49.01]) (p=0.010). The early recognition of indexes of suspicion for CMPIE may be of help in the diagnosis and treatment of this disorder.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2694639PMC
http://dx.doi.org/10.3346/jkms.2007.22.6.993DOI Listing
December 2007

12-O-tetradecanoyl phorbol 13-acetate induces the expression of B7-DC, -H1, -H2, and -H3 in K562 cells.

Int J Oncol 2007 Dec;31(6):1439-47

Chronic Disease Research Center and Institute for Medical Science, Keimyung University School of Medicine, Daegu, Korea.

Induction of the B7 family molecules by 12-O-tetradecanoyl phorbol 13-acetate (TPA) has been reported, however, the mechanism by which TPA up-regulates these molecules remains poorly understood. In this study, the expression of B7-DC, -H1, -H2, and -H3 in response to TPA was markedly induced in K562 cells. TPA also induced activation of ERK, p38 mitogen-activated protein kinase (MAPK), JNK, phosphatidylinositol-3-kinase (PI-3K), or nuclear factor (NF)-kappaB. Pre-treatments with protein kinase C (PKC) inhibitors significantly inhibited TPA-induced expression of B7-DC, -H1, -H2, and -H3 mRNA as well as TPA-induced phosphorylation of ERK, p38 MAPK, JNK, and PI-3K. TPA-induced expression of B7-DC, -H1, -H2, and -H3 mRNA was abrogated by pre-treatments with inhibitors of ERK and p38 MAPK. However, inhibition of PI-3K and JNK only caused decrease of TPA-induced B7-DC mRNA and B7-H3 mRNA, respectively. TPA-induced degradation of IkappaB-alpha was markedly abrogated by treatments with PKC inhibitors, but not by treatments with inhibitors of ERK, p38 MAPK, JNK, or PI-3K. NF-kappaB inhibitors significantly attenuated the expression of B7-DC, -H1, -H2, and -H3 mRNA in response to TPA. These results suggest that TPA induces the expression of B7-DC, -H1, -H2, and -H3 mRNA in K562 cells via activation of PKC, ERK, p38 MAPK, and NF-kappaB. Distinctly, the expression of B7-DC mRNA and -H3 mRNA in response to TPA is also PI-3K- and JNK-dependent, respectively.
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December 2007

Dexamethasone suppresses interleukin-1beta-induced human beta-defensin 2 mRNA expression: involvement of p38 MAPK, JNK, MKP-1, and NF-kappaB transcriptional factor in A549 cells.

FEMS Immunol Med Microbiol 2007 Oct 23;51(1):171-84. Epub 2007 Jul 23.

Chronic Disease Research Center and Institute for Medical Science, School of Medicine Keimyung University, Daegu, Korea.

Human beta-defensin (HBD)-2 is an inducible antimicrobial peptide that plays an important role in innate immunity. Glucocorticoids, on the other hand, exert immunosuppressive and anti-inflammatory actions. We have previously reported that interleukin (IL)-1beta induces HBD-2 mRNA expression through the activation of nuclear factor-kappaB (NF-kappaB) transcriptional factor, as well as p38 mitogen-activated protein kinase (MAPK), c-Jun N-terminal kinase (JNK), or phosphatidylinositol-3-kinase/AKT in A549 cells. In this study, we further investigated whether dexamethasone (Dex) controls IL-1beta-induced HBD-2 mRNA expression in A549 cells and the molecular mechanism associated with it. Dex suppressed IL-1beta-induced HBD-2 mRNA expression, which is mediated by a glucocorticoid receptor, at the transcriptional level. Interestingly, Dex attenuated IL-1beta-mediated activation of p38 MAPK and JNK, but not of AKT. Dex increased the expression of MAPK phosphatase (MKP)-1, which dephosphorylated p38 MAPK, but not JNK, by IL-1beta. However, although Dex did not inhibit the nuclear translocation of p65 NF-kappaB in response to IL-1beta, it profoundly inhibited NF-kappaB promoter- and HBD-2 promoter-driven luciferase activities. These results suggest that Dex acts to inhibit IL-1beta-induced HBD-2 mRNA expression through blockage of the nuclear transcriptional activation of p65 NF-kappaB as well as through inactivation of p38 MAPK and JNK. Specifically, Dex-induced MKP-1 expression is responsible for the inactivation of p38 MAPK, but not JNK, in response to IL-1beta in A549 cells.
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http://dx.doi.org/10.1111/j.1574-695X.2007.00293.xDOI Listing
October 2007

Glucosamine hydrochloride specifically inhibits COX-2 by preventing COX-2 N-glycosylation and by increasing COX-2 protein turnover in a proteasome-dependent manner.

J Biol Chem 2007 Sep 16;282(38):27622-32. Epub 2007 Jul 16.

Chronic Disease Research Center and Institute for Medical Science, Keimyung University School of Medicine, Daegu, South Korea.

COX-2 and its products, including prostaglandin E(2), are involved in many inflammatory processes. Glucosamine (GS) is an amino monosaccharide and has been widely used for alternative regimen of (osteo) arthritis. However, the mechanism of action of GS on COX-2 expression remains unclear. Here we describe a new action mechanism of glucosamine hydrochloride (GS-HCl) to tackle endogenous and agonist-driven COX-2 at protein level. GS-HCl (but not GS sulfate, N-acetyl GS, or galactosamine HCl) resulted in a shift in the molecular mass of COX-2 from 72-74 to 66-70 kDa and concomitant inhibition of prostaglandin E(2) production in a concentration-dependent manner in interleukin (IL)-1beta-treated A549 human lung epithelial cells. Remarkably, GS-HCl-mediated decrease in COX-2 molecular mass was associated with inhibition of COX-2 N-glycosylation during translation, as assessed by the effect of tunicamycin, the protein N-glycosylation inhibitor, or of cycloheximide, the translation inhibitor, on COX-2 modification. Specifically, the effect of low concentration of GS-HCl (1 mM) or of tunicamycin (0.1 microg/ml) to produce the aglycosylated COX-2 was rescued by the proteasomal inhibitor MG132 but not by the lysosomal or caspase inhibitors. However, the proteasomal inhibitors did not show an effect at 5 mM GS-HCl, which produced the aglycosylated or completely deglycosylated form of COX-2. Notably, GS-HCl (5 mM) also facilitated degradation of the higher molecular species of COX-2 in IL-1beta-treated A549 cells that was retarded by MG132. GS-HCl (5 mM) was also able to decrease the molecular mass of endogenous and IL-1beta- or tumor necrosis factor-alpha-driven COX-2 in different human cell lines, including Hep2 (bronchial) and H292 (laryngeal). However, GS-HCl did not affect COX-1 protein expression. These results demonstrate for the first time that GS-HCl inhibits COX-2 activity by preventing COX-2 co-translational N-glycosylation and by facilitating COX-2 protein turnover during translation in a proteasome-dependent manner.
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http://dx.doi.org/10.1074/jbc.M610778200DOI Listing
September 2007

D-glucosamine inhibits proliferation of human cancer cells through inhibition of p70S6K.

Biochem Biophys Res Commun 2007 Sep 5;360(4):840-5. Epub 2007 Jul 5.

Chronic Disease Research Center and Institute for Medical Science, School of Medicine, Keimyung University, Daegu 700-712, Republic of Korea.

Although D-glucosamine has been reported as an inhibitor of tumor growth both in vivo and in vitro, the mechanism for the anticancer effect of D-glucosamine is still unclear. Since there are several reports suggesting D-glucosamine inhibits protein synthesis, we examined whether D-glucosamine affects p70S6K activity, an important signaling molecule involved in protein translation. In the present study, we found D-glucosamine inhibited the activity of p70S6K and the proliferation of DU145 prostate cancer cells and MDA-MB-231 breast cancer cells. D-glucosamine decreased phosphorylation of p70S6K, and its downstream substrates RPS6, and eIF-4B, but not mTOR and 4EBP1 in DU145 cells, suggesting that D-glucosamine induced inhibition of p70S6K is not through the inhibition of mTOR. In addition, D-glucosamine enhanced the growth inhibitory effects of rapamycin, a specific inhibitor of mTOR. These findings suggest that D-glucosamine can inhibit growth of cancer cells through dephosphorylation of p70S6K.
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http://dx.doi.org/10.1016/j.bbrc.2007.06.137DOI Listing
September 2007

Protective effects of several components of Gastrodia elata on lipid peroxidation in gerbil brain homogenates.

Phytother Res 2007 Oct;21(10):960-4

Department of Microbiology, School of Medicine, Keimyung University, Taegu, 700-712 South Korea.

Gastrodia elata (GE) Blume, a traditional herbal agent, has been used mainly in anticonvulsive treatment in Asia. Recently, extracts of GE were evaluated for their potential as neuroprotectives and antioxidants. This study was designed to examine the antioxidant effect of the ether fraction of the methanol extract (EFME) of GE along with its major constituents vanillin, vanillyl alcohol, hydroxybenzaldehyde and hydroxybenzyl alcohol. In experiment 1, gerbils were treated with EFME of GE at a dosage of 500 mg/kg/day for 2 weeks. Oxidative stress was induced with H(2)O(2) or ferrous ion, and lipid peroxidation was measured. In experiment 2, oxidative stress was induced with various concentrations of H(2)O(2) or ferrous ammonium sulfate, and lipid peroxidation was measured. To compare the antioxidant potency, the inhibitory concentration 50% (IC(50)) was determined. EFME of GE reduced auto-peroxidation and H(2)O(2)-induced lipid peroxidation. However, it did not significantly reduce ferrous ammonium sulfate-induced lipid peroxidation. The order of antioxidation potency was as follows: hydroxybenzyl alcohol > vanillyl alcohol > vanillin > hydroxybenzaldehyde. In the case of hydroxybenzaldehyde, its antioxidant effect was more potent than that of melatonin. The excellent antioxidant effects of GE and its main constituents may have potential in the treatment of lipid peroxidation-associated neurological disease.
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http://dx.doi.org/10.1002/ptr.2193DOI Listing
October 2007

Advanced criteria for clinicopathological diagnosis of food protein-induced proctocolitis.

J Korean Med Sci 2007 Apr;22(2):213-7

Department of Pediatrics, Dongsan Medical Center, Keimyung University School of Medicine, 194 Dongsan-dong, Jung-gu, Daegu, Korea.

The clinicopathological findings in previous studies concerning food protein-induced proctocolitis (FPIPC) are quite diverse in terms of results and conclusions. The aim of this study was to suggest advanced clinicopathological diagnostic criteria that facilitate the early confirmation of FPIPC. Data of 38 FPIPC patients, who had received sigmoidoscopy and biopsy, was analyzed. Microscopic findings were compared with observations of previous studies. Feeding at onset of bleeding was exclusively breast-fed (94.7%) and formula-fed or mixed-fed (5.3%). Endoscopic abnormalities were observed in all patients; nodular hyperplasias with circumscribed and/or central pit-like erosions in 94.7% and erythema in 5.3%. Histopathological findings were; lymphoid aggregates in 94.7%, eosinophils in lamina propria of >or=60 cells/10 HPF in 97.4% and of >20 cells/HPF in 63.2%, epithelial or muscularis mucosa eosinophil infiltration in 97.4%, and crypt abscess in 2.6%. The majority of FPIPC patients are exclusively breast-fed and nodular hyperplasias with erosions may be a disease specific endoscopic finding. Histologic diagnosis of FPIPC is compatible with eosinophils in the lamina propria of >or=60 cells/10 high power fields; however, >20 cells/HPF is not an appropriate diagnostic criterion.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2693584PMC
http://dx.doi.org/10.3346/jkms.2007.22.2.213DOI Listing
April 2007

Triptolide suppresses interleukin-1beta-induced human beta-defensin-2 mRNA expression through inhibition of transcriptional activation of NF-kappaB in A549 cells.

Int J Mol Med 2007 May;19(5):757-63

Chronic Disease Research Center and Institute for Medical Science, Keimyung University School of Medicine, Daegu, Korea.

The immunosuppressive effect of triptolide has been associated with suppression of T-cell activation. However, the immunosuppressive effects of triptolide on innate immunity in the epithelial barrier remain to be elucidated. Human beta-defensin (HBD)-2 is an inducible antimicrobial peptide and plays an important role in the innate immunity. We have previously demonstrated that IL-1beta induced HBD-2 mRNA expression in A549 cells through activation of nuclear factor-kappaB (NF-kappaB) transcriptional factor as well as p38 mitogen-activated protein kinase (MAPK), c-Jun N-terminal kinase (JNK), or phosphatidylinositol-3-kinase (PI3K). In this study, we investigated effects of triptolide on IL-1beta-induced HBD-2 mRNA expression in A549 cells. Triptolide inhibited IL-1beta-induced HBD-2 mRNA expression in a dose-dependent manner. Addition of triptolide did not suppress activation of p38 MAPK, JNK, or PI3K in response to IL-1beta. Triptolide inhibited IL-1beta-induced MAPK phosphatase-1 expression at the transcriptional level and resulted in sustained phosphorylation of JNK or p38 MAPK, explaining the little effect of triptolide on IL-1beta-induced phosphorylation of these kinases. Although triptolide partially suppressed IL-1beta-mediated degradation of IkappaB-alpha and nuclear translocation of p65 NF-kappaB, triptolide potently inhibited NF-kappaB promoter-driven luciferase activity in A549 cells. These results collectively suggest that the inhibitory effect of triptolide on IL-1beta-induced HBD-2 mRNA expression in A549 cells seems to be at least in part mediated through nuclear inhibition of NF-kappaB transcriptional activity, but not inhibition of p38 MAPK, JNK, or PI3K. This inhibition may explain the ability of triptolide to diminish innate immune response.
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May 2007