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1.  8-Hydroxydeoxyguanosine: Not mere biomarker for oxidative stress, but remedy for oxidative stress-implicated gastrointestinal diseases 
Reactive oxygen species (ROS) attack guanine bases in DNA easily and form 8-hydroxydeoxyguanosine (8-OHdG), which can bind to thymidine rather than cytosine, based on which, the level of 8-OHdG is generally regarded as a biomarker of mutagenesis consequent to oxidative stress. For example, higher levels of 8-OHdG are noted in Helicobacter pylori-associated chronic atrophic gastritis as well as gastric cancer. However, we have found that exogenous 8-OHdG can paradoxically reduce ROS production, attenuate the nuclear factor-κB signaling pathway, and ameliorate the expression of proinflammatory mediators such as interleukin (IL)-1, IL-6, cyclo-oxygenase-2, and inducible nitric oxide synthase in addition to expression of nicotinamide adenine dinucleotide phosphate oxidase (NOX)-1, NOX organizer-1 and NOX activator-1 in various conditions of inflammation-based gastrointestinal (GI) diseases including gastritis, inflammatory bowel disease, pancreatitis, and even colitis-associated carcinogenesis. Our recent finding that exogenous 8-OHdG was very effective in either inflammation-based or oxidative-stress-associated diseases of stress-related mucosal damage has inspired the hope that synthetic 8-OHdG can be a potential candidate for the treatment of inflammation-based GI diseases, as well as the prevention of inflammation-associated GI cancer. In this editorial review, the novel fact that exogenous 8-OHdG can be a functional molecule regulating oxidative-stress-induced gastritis through either antagonizing Rac-guanosine triphosphate binding or blocking the signals responsible for gastric inflammatory cascade is introduced.
PMCID: PMC3261525  PMID: 22294836
8-hydroxydeoxyguanosine; Oxidative stress; Inflammation; Carcinogenesis; Prevention
2.  Comparison of anti-oxidant activities of seventy herbs that have been used in Korean traditional medicine 
Nutrition Research and Practice  2008;2(3):143-151.
Many herbs have been used as therapeutics in Korean traditional medicine. In view of their clinical indications, anti-oxidant activity may contribute to their pharmacological effects. However, anti-oxidant information on these plants has not been available. In this study, seventy herbs which have been used in Korean traditional medicine were selected and screened for anti-oxidant activity using their water extracts. The anti-oxidant activity was assessed by their ability to inhibit three oxidation reactions; luminol/Fenton reagent, 2, 7-dichlorodihydrofluorescein (DCHF)/Fenton reagent and DCHF/peroxynitrite. In each assay, 70 herbs were divided into two groups; anti-oxidant group which inhibited the respective oxidation reaction and was majority (about 60 herbs), and pro-oxidant group which enhanced the oxidation reaction but was minority (more or less 10 herbs). When the herbs were listed in the order of their anti-oxidant strength, the orders obtained from each assay were found to be quite similar. The upper top rankers (more or less 10 herbs) in each assay showed strong activity compared to the others. The uppermost rankers in each assay were Rubus coreanus Miquel/ Rubus schizostylus, Schisandra chinensis Baillon/ Schizandra chinensis and Terminalia chebula Retzius/ Terminalia chebula. Of the pro-oxidant herbs, about 4-5 herbs were strongly pro-oxidant, which enhanced the control oxidation reactions to 150-300%. But the meaning of this observation is not known since few of them in one assay were also anti-oxidant in other assays. The results obtained in the present study may serve as information for understanding pharmacological effects of these herbs and developing new drugs from them.
PMCID: PMC2814189  PMID: 20126599
Anti-oxidants; herbs; chemiluminescence; peroxynitrite; Fenton reagent
3.  Interleukin-6 Induces S100A9 Expression in Colonic Epithelial Cells through STAT3 Activation in Experimental Ulcerative Colitis 
PLoS ONE  2012;7(9):e38801.
Intestinal epithelium is essential for maintaining normal intestinal homeostasis; its breakdown leads to chronic inflammatory pathologies, such as inflammatory bowel diseases (IBDs). Although high concentrations of S100A9 protein and interleukin-6 (IL-6) are found in patients with IBD, the expression mechanism of S100A9 in colonic epithelial cells (CECs) remains elusive. We investigated the role of IL-6 in S100A9 expression in CECs using a colitis model.
IL-6 and S100A9 expression, signal transducer and activator of transcription 3 (STAT3) phosphorylation, and infiltration of immune cells were analyzed in mice with dextran sulfate sodium (DSS)-induced colitis. The effects of soluble gp130-Fc protein (sgp130Fc) and S100A9 small interfering (si) RNA (si-S100A9) on DSS-induced colitis were evaluated. The molecular mechanism of S100A9 expression was investigated in an IL-6-treated Caco-2 cell line using chromatin immunoprecipitation assays.
IL-6 concentrations increased significantly in the colon tissues of DSS-treated mice. sgp130Fc or si-S100A9 administration to DSS-treated mice reduced granulocyte infiltration in CECs and induced the down-regulation of S100A9 and colitis disease activity. Treatment with STAT3 inhibitors upon IL-6 stimulation in the Caco-2 cell line demonstrated that IL-6 mediated S100A9 expression through STAT3 activation. Moreover, we found that phospho-STAT3 binds directly to the S100A9 promoter. S100A9 may recruit immune cells into inflamed colon tissues.
Elevated S100A9 expression in CECs mediated by an IL-6/STAT3 signaling cascade may play an important role in the development of colitis.
PMCID: PMC3433486  PMID: 22962574
4.  A Case of Pulmonary MALT Lymphoma Arising from Lymphocytic Interstitial Pneumonitis 
Pulmonary mucosa-associated lymphoid tissue-derived (MALT) lymphoma is a rare disease. This disorder is considered to be a model of antigen-driven lymphoma, which is driven either by autoantigens or by chronic inflammatory conditions. Low-grade B-cell MALT lymphoma may develop from a nonneoplastic pulmonary lymphoproliferative disorder, such as lymphocytic interstitial pneumonitis (LIP). A recent estimate predicts that less than 5% of LIP patients acquire malignant, low-grade, B-cell lymphoma. In Korea, there has been no previous report of malignant low-grade, B-cell lymphoma, acquired from LIP. Here, we present the case of a patient with LIP that developed into pulmonary MALT lymphoma, six years after diagnosis.
PMCID: PMC3492375  PMID: 23166544
Lymphoma; Lymphoproliferative Disorders; Lung Diseases, Interstitial; Lymphoid Tissue
5.  Typical and Atypical Manifestations of Intrathoracic Sarcoidosis 
Korean Journal of Radiology  2009;10(6):623-631.
Sarcoidosis is a systemic disorder of unknown cause that is characterized by the presence of noncaseating granulomas. The radiological findings associated with sarcoidosis have been well described. The findings include symmetric, bilateral hilar and paratracheal lymphadenopathy, with or without concomitant parenchymal abnormalities (multiple small nodules in a peribronchovascular distribution along with irregular thickening of the interstitium). However, in 25% to 30% of cases, the radiological findings are atypical and unfamiliar to most radiologists, which cause difficulty for making a correct diagnosis. Many atypical forms of intrathoracic sarcoidosis have been described sporadically. We have collected cases with unusual radiological findings associated with pulmonary sarcoidosis (unilateral or asymmetric lymphadenopathy, necrosis or cavitation, large opacity, ground glass opacity, an airway abnormality and pleural involvement) and describe the typical forms of the disorder as well. The understanding of a wide range of the radiological manifestations of sarcoidosis will be very helpful for making a proper diagnosis.
PMCID: PMC2770817  PMID: 19885319
Sarcoidosis; Thorax; Computed tomography (CT)
6.  Chronic Exposure to the Herbicide, Atrazine, Causes Mitochondrial Dysfunction and Insulin Resistance 
PLoS ONE  2009;4(4):e5186.
There is an apparent overlap between areas in the USA where the herbicide, atrazine (ATZ), is heavily used and obesity-prevalence maps of people with a BMI over 30. Given that herbicides act on photosystem II of the thylakoid membrane of chloroplasts, which have a functional structure similar to mitochondria, we investigated whether chronic exposure to low concentrations of ATZ might cause obesity or insulin resistance by damaging mitochondrial function. Sprague-Dawley rats (n = 48) were treated for 5 months with low concentrations (30 or 300 µg kg−1 day−1) of ATZ provided in drinking water. One group of animals was fed a regular diet for the entire period, and another group of animals was fed a high-fat diet (40% fat) for 2 months after 3 months of regular diet. Various parameters of insulin resistance were measured. Morphology and functional activities of mitochondria were evaluated in tissues of ATZ-exposed animals and in isolated mitochondria. Chronic administration of ATZ decreased basal metabolic rate, and increased body weight, intra-abdominal fat and insulin resistance without changing food intake or physical activity level. A high-fat diet further exacerbated insulin resistance and obesity. Mitochondria in skeletal muscle and liver of ATZ-treated rats were swollen with disrupted cristae. ATZ blocked the activities of oxidative phosphorylation complexes I and III, resulting in decreased oxygen consumption. It also suppressed the insulin-mediated phosphorylation of Akt. These results suggest that long-term exposure to the herbicide ATZ might contribute to the development of insulin resistance and obesity, particularly where a high-fat diet is prevalent.
PMCID: PMC2664469  PMID: 19365547
7.  LYR71, a derivative of trimeric resveratrol, inhibits tumorigenesis by blocking STAT3-mediated matrix metalloproteinase 9 expression 
Experimental & Molecular Medicine  2008;40(5):514-522.
Tumor migration/invasion is the main cause of tumor progression and STAT3 is needed to enhance tumor migration/invasion by up-regulating MMP-9. Thus, agents that inhibit STAT3 activation may be used as an anticancer drug. We present herein that 6-methyl-2-propylimino-6, 7-dihydro-5H-benzo [1, 3]-oxathiol-4-one (LYR71) , a derivative of trimeric resveratrol, has an anticancer activity through inhibition of STAT3 activation. We found that LYR71 suppressed STAT3 activation and inhibited the expression and activity of MMP-9 in RANTES-stimulated breast cancer cells. In addition, LYR71 reduced RANTES-induced MMP-9 transcripts by blocking STAT3 recruitment, dissociating p300 and deacetylating histone H3 and H4 on the MMP-9 promoter. Furthermore, LYR71 inhibited tumor migration/invasion in RANTES-treated breast cancer cells and consequently blocked tumor progression in tumor-bearing mice. Taken together, the results of this study suggest that LYR71 can be therapeutically useful due to the inhibition effect of STAT3-mediated MMP-9 expression in breast cancer cells.
PMCID: PMC2679359  PMID: 18985009
chemokine CCL5; LYR71; matrix metalloproteinase 9; neoplasm metastasis; STAT3 transcription factor
8.  STAT3 inhibits the degradation of HIF-1α by pVHL-mediated ubiquitination 
Experimental & Molecular Medicine  2008;40(5):479-485.
Hypoxia-inducible factor 1α (HIF-1α) is rapidly degraded by the ubiquitin-proteasome pathway under normoxic conditions. Ubiquitination of HIF-1α is mediated by interaction with von Hippel-Lindau tumor suppressor protein (pVHL). In our previous report, we found that hypoxia-induced active signal transducer and activator of transcription3 (STAT3) accelerated the accumulation of HIF-1α protein and prolonged its half-life in solid tumor cells. However, its specific mechanisms are not fully understood. Thus, we examined the role of STAT3 in the mechanism of pVHL-mediated HIF-1α stability. We found that STAT3 interacts with C-terminal domain of HIF-1α and stabilizes HIF-1α by inhibition of pVHL binding to HIF-1α. The binding between HIF-1α and pVHL, negative regulator of HIF-1α stability, was interfered dose-dependently by overexpressed constitutive active STAT3. Moreover, we found that the enhanced HIF-1α protein levels by active STAT3 are due to decrease of poly-ubiquitination of HIF-1α protein via inhibition of interaction between pVHL and HIF-1α. Taken together, our results suggest that STAT3 decreases the pVHL-mediated ubiquitination of HIF-1α through competition with pVHL for binding to HIF-1α, and then stabilizes HIF-1α protein levels.
PMCID: PMC2679355  PMID: 18985005
anoxia; hypoxia-inducible factor1, α subunit; neoplasms; STAT3 transcription factor; ubiquitination; von Hippel-Lindau tumor suppressor protein
9.  Polyvinyl Alcohol Embolization Adjuvant to Oily Chemoembolization in Advanced Hepatocellular Carcinoma with Arterioportal Shunts 
Korean Journal of Radiology  2007;8(4):311-319.
To assess the feasibility and safety of polyvinyl alcohol (PVA) embolization adjuvant to transarterial oily chemoembolization (P-TACE) in advanced hepatocellular carcinoma (HCC) with arterioportal shunts (APS).
Materials and Methods
Nineteen patients who underwent PVA embolization for APS before a routine chemoembolization (TACE) procedure were retrospectively reviewed. 10 of these 19 patients underwent follow-up TACE or P-TACE after P-TACE (Group A), but nine patients underwent only initial P-TACE because of progression of HCC and/or underlying liver cirrhosis (Group B). Hepatic function tests, APS grades, and portal flow directions were evaluated before and after P-TACE sessions. Complications after procedures and survival days were also evaluated.
In group A, APS grade was improved in eight patients and five of six patients with hepatofugal flow showed restored hepatopetal flow postoperatively. No immediate complication was developed in either group. Transient hepatic insufficiency developed in eight (42.1%) of 19 patients after P-TACE, and seven (87.5%) of these eight recovered within two weeks under conservative care. The mean and median survival time all study subjects was 280 days and 162 days.
P-TACE is feasible and safe in advanced HCC patients with APS.
PMCID: PMC2627160  PMID: 17673842
Shunts, arterioportal; Hepatic arteries, chemotherapeutic embolization; Liver neoplasms, chemotherapeutic embolization
11.  Human AP endonuclease suppresses DNA mismatch repair activity leading to microsatellite instability 
Nucleic Acids Research  2005;33(16):5073-5081.
The multifunctional mammalian apurinic/apyrimidinic (AP) endonuclease (APE) participates in the repair of AP sites in the cellular DNA as well as participating in the redox regulation of the transcription factor function. The function of APE is considered as the rate-limiting step in DNA base excision repair. Paradoxically, an unbalanced increase in APE protein leads to genetic instability. Therefore, we investigated the mechanisms of genetic instability that are induced by APE. Here, we report that the overexpression of APE protein disrupts the repair of DNA mismatches, which results in microsatellite instability (MSI). We found that expression of APE protein led to the suppression of the repair of DNA mismatches in the normal human fibroblast cells. Western blot analysis revealed that hMSH6 protein was markedly reduced in the APE-expressing cells. Moreover, the addition of purified Mutα (MSH2 and MSH6 complex) to the extracts from the APE-expressing cells led to the restoration of mismatch repair (MMR) activity. By performing MMR activity assay and MSI analysis, we found that the co-expression of hMSH6 and APE exhibited the microsatellite stability, whereas the expression of APE alone generated the MSI-high phenotype. The APE-mediated decrease in MMR activity described here demonstrates the presence of a new and highly effective APE-mediated mechanism for MSI.
PMCID: PMC1201336  PMID: 16147991
12.  Retroperitoneal Malignant Mesenchymoma: A Case of Mesenchymal Mixed Tumor with Osteosarcoma, Leiomyosarcoma, Liposarcoma and Fibrosarcoma 
Korean Journal of Radiology  2002;3(4):264-266.
Malignant mesenchymoma is an interesting but very rare tumor in which malignant differentiation has occurred twice or more. We report a case of retroperitoneal malignant mesenchymoma consisting of osteosarcoma, leiomyosarcoma, liposarcoma and fibrosarcoma. Abdominal CT showed a large retroperitoneal mass with two separate and distinct parts, namely an area of prominent calcification and one of clearly enhancing solid components. The mass contained histologically distinct tumorous components with no histologic admixure at the interfaces. The densely calcified nodule corresponded to osteosarcoma, and the non-calcified clearly enhancing nodules to leiomyosarcoma, liposarcoma and fibrosarcoma.
PMCID: PMC2713850  PMID: 12514345
Malignant mesenchymoma; Retroperitoneum, CT; Sarcoma

Results 1-13 (13)