• Toxicological Research
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• 제33권2호
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• pp.79-96
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• 2017

A variety of xenobiotic chemicals, such as polycyclic aromatic hydrocarbons (PAHs), aryl- and heterocyclic amines and tobacco related nitrosamines, are ubiquitous environmental carcinogens and are required to be activated to chemically reactive metabolites by xenobiotic-metabolizing enzymes, including cytochrome P450 (P450 or CYP), in order to initiate cell transformation. Of various human P450 enzymes determined to date, CYP1A1, 1A2, 1B1, 2A13, 2A6, 2E1, and 3A4 are reported to play critical roles in the bioactivation of these carcinogenic chemicals. In vivo studies have shown that disruption of Cyp1b1 and Cyp2a5 genes in mice resulted in suppression of tumor formation caused by 7,12-dimethylbenz[a]anthracene and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, respectively. In addition, specific inhibitors for CYP1 and 2A enzymes are able to suppress tumor formation caused by several carcinogens in experimental animals in vivo, when these inhibitors are applied before or just after the administration of carcinogens. In this review, we describe recent progress, including our own studies done during past decade, on the nature of inhibitors of human CYP1 and CYP2A enzymes that have been shown to activate carcinogenic PAHs and tobacco-related nitrosamines, respectively, in humans. The inhibitors considered here include a variety of carcinogenic and/or non-carcinogenic PAHs and acethylenic PAHs, many flavonoid derivatives, derivatives of naphthalene, phenanthrene, biphenyl, and pyrene and chemopreventive organoselenium compounds, such as benzyl selenocyanate and benzyl selenocyanate; o-XSC, 1,2-, 1,3-, and 1,4-phenylenebis(methylene)selenocyanate.

• Archives of Pharmacal Research
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• 제25권5호
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• pp.561-571
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• 2002

The action mechanisms of several chemopreventive agents derived from herbal medicine and edible plants have become attractive issues in cancer research. Tea is the most widely consumed beverage worldwide. Recently, the cancer chemopreventive actions of tea have been intensively investigated. It have been demonstrated that the active principles of tea were attributed to their tea polyphenols. Recently, tremendous progress has been made in elucidating the molecular mechanisms of cancer chemoprevention by tea and tea polyphenols. The suppression of various tumor biomarkers including growth factor receptor tyrosine kinases, cytokine receptor kinases, P13K, phosphatases, ras, raf, MAPK cascades, NㆍFB, IㆍB kinase, PKA, PKB, PKC, c-jun, c-fos, c-myc, cdks, cyclins, and related transducing proteins by tea polyphenols has been studied in our laboratory and others. The IㆍB kinase (IKK) activity in LPS-activated murine macrophages (RAW 264.7 cells) was found to be inhibited by various tea polyphenols including (-) epigallocatechin-3-gallate (EGCG), theaflavin (TF-1), theaflavin-3-gal-late (TF-2) and theaflavin-3,3'-digallate (TF-3). TF-3 inhibited IKK activity in activated macrophages more strongly than did the other tea polyphenols. TF-3 inhibited both IKK1 and IKK2 activity and prevented the degradation of IㆍBㆍand IㆍBㆍin activated macrophage cells. The results suggested that the inhibition of IKK activity by TF-3 and other tea polyphenols could occur by a direct effect on IKKs or on upstream events in the signal transduction pathway. TF-3 and other tea polyphenols blocked phosphorylation of IB from the cytosolic fraction, inhibited NFB activity and inhibited increases in inducible nitric oxide synthase levels in activated macrophage. TF-3 and other tea polyphenols also inhibited strongly the activities of xanthine oxidase, cyclooxygenase, EGF-receptor tyrosine kinase and protein kinase C. These results suggest that TF-3 and other tea polyphenols may exert their cancer chemoprevention through suppressing tumor promotion and inflammation by blocking signal transduction. The mechanisms of this inhibition may be due to the blockade of the mitogenic and differentiating signals through modulating EGFR function, MAPK cascades, NFkB activation as wll as c-myc, c-jun and c-fos expression.

• Journal of Ginseng Research
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• 제37권2호
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• pp.187-193
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• 2013

The effect of Korean red ginseng (KRG) on diabetic renal damage was investigated using streptozotocin (STZ)-induced diabetic rats. The diabetic rats showed loss of body weight gain, and increases in kidney weight and urine volume, whereas the oral administration of KRG at a dose of 100 or 250 mg/kg of body weight per day for 28 d prevented these diabetes-induced physiological abnormalities. Among the kidney function parameters, elevated plasma levels of urea nitrogen and creatinine in diabetic control rats tended to be lowered in KRG-treated rats. In addition, administration of KRG at a dose of 100 mg/kg body weight in the diabetic rats showed significant decreases in serum glucose and tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$), implying that KRG might prevent the pathogenesis of diabetic complications caused by impaired glucose metabolism and oxidative stress. KRG also significantly reduced advanced glycation end product (AGE) formation and secretion from kidney of diabetic rats. Furthermore, KRG decreased the levels of N-(carboxymethyl) lysine and expression of AGE receptor. KRG also reduced the overexpression of cyclooxygenase-2 and inducible nitric oxide synthase in the kidney via deactivation of nuclear factor-kappa B. We also found that KRG prevented STZ-induced destruction of glomerular structure and significantly suppressed high glucose-induced fibronectin production. Taken together, KRG ameliorates abnormalities associated with diabetic nephropathy through suppression of inflammatory pathways activated by TNF-${\alpha}$ and AGEs. These findings indicate that KRG has a beneficial effect on pathological conditions associated with diabetic nephropathy.

• Nutrition Research and Practice
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• 제12권2호
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• pp.101-109
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• 2018

BACKGROUD/OBJECTIVES: The objective of this study was to investigate the effects of vitamin C on inflammation, tumor development, and dysbiosis of intestinal microbiota in an azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced inflammation-associated early colon cancer mouse model. MATERIALS/METHODS: Male BALB/c mice were injected intraperitoneally with AOM [10 mg/kg body weight (b.w)] and given two 7-d cycles of 2% DSS drinking water with a 14 d inter-cycle interval. Vitamin C (60 mg/kg b.w. and 120 mg/kg b.w.) was supplemented by gavage for 5 weeks starting 2 d after the AOM injection. RESULTS: The vitamin C treatment suppressed inflammatory morbidity, as reflected by disease activity index (DAI) in recovery phase and inhibited shortening of the colon, and reduced histological damage. In addition, vitamin C supplementation suppressed mRNA levels of pro-inflammatory mediators and cytokines, including cyclooxygenase-2, microsomal prostaglandin E synthase-2, tumor necrosis $factor-{\alpha}$, Interleukin $(IL)-1{\beta}$, and IL-6, and reduced expression of the proliferation marker, proliferating cell nuclear antigen, compared to observations of AOM/DSS animals. Although the microbial composition did not differ significantly between the groups, administration of vitamin C improved the level of inflammation-related Lactococcus and JQ084893 to control levels. CONCLUSION: Vitamin C treatment provided moderate suppression of inflammation, proliferation, and certain inflammation-related dysbiosis in a murine model of colitis associated-early colon cancer. These findings support that vitamin C supplementation can benefit colonic health. Long-term clinical studies with various doses of vitamin C are warranted.

• Biomolecules & Therapeutics
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• 제22권6호
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• pp.525-531
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• 2014

In the present study, we investigated whether apigenin significantly affects tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$)-induced production and gene expression of MUC5AC mucin in airway epithelial cells. Confluent NCI-H292 cells were pretreated with apigenin for 30 min and then stimulated with TNF-${\alpha}$ for 24 h or the indicated periods. The MUC5AC mucin gene expression and mucin protein production were measured by reverse transcription - polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. Apigenin significantly inhibited MUC5AC mucin production and down-regulated MUC5AC gene expression induced by TNF-${\alpha}$ in NCI-H292 cells. To elucidate the action mechanism of apigenin, effect of apigenin on TNF-${\alpha}$-induced nuclear factor kappa B (NF-${\kappa}B$) signaling pathway was also investigated by western blot analysis. Apigenin inhibited NF-${\kappa}B$ activation induced by TNF-${\alpha}$. Inhibition of inhibitory kappa B kinase (IKK) by apigenin led to the suppression of inhibitory kappa B alpha ($I{\kappa}B{\alpha}$) phosphorylation and degradation, p65 nuclear translocation. This, in turn, led to the down-regulation of MUC5AC protein production in NCI-H292 cells. Apigenin also has an influence on upstream signaling of IKK because it inhibited the expression of adaptor protein, receptor interacting protein 1 (RIP1). These results suggest that apigenin can regulate the production and gene expression of mucin through regulating NF-${\kappa}B$ signaling pathway in airway epithelial cells.

• Journal of Ginseng Research
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• 제39권1호
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• pp.14-21
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• 2015

Background: Colorectal cancer is a leading cause of cancer-related death, and inflammatory bowel disease is a risk factor for this malignancy. We previously reported colon cancer chemoprevention potential using American ginseng (AG) in a xenograft mice model. However, the nude mouse model is not a gut-specific colon carcinogenesis animal model. Methods: In this study, an experimental colitis and colitis-associated colorectal carcinogenesis mouse model, chemically induced by azoxymethane/dextran sodium sulfate (DSS) was established and the effects of oral AG were evaluated. The contents of representative ginseng saponins in the extract were determined. Results: AG significantly reduced experimental colitis measured by the disease activity index scores. This suppression of the experimental colitis was not only evident during DSS treatment, but also very obvious after the cessation of DSS, suggesting that the ginseng significantly promoted recovery from the colitis. Consistent with the anti-inflammation data, we showed that ginseng very significantly attenuated azoxymethane/DSS-induced colon carcinogenesis by reducing the colon tumor number and tumor load. The ginseng also effectively suppressed DSS-induced proinflammatory cytokines activation using an enzyme-linked immunosorbent assay array, in which 12 proinflammatory cytokine levels were assessed, and this effect was supported subsequently by real-time polymerase chain reaction data. Conclusion: AG, as a candidate of botanical-based colon cancer chemoprevention, should be further investigated for its potential clinical utility.

• Archives of Pharmacal Research
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• 제27권7호
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• pp.683-692
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• 2004

Curcumin (diferuloylmethane) is a major naturally-occurring polyphenol of Curcuma species, which is commonly used as a yellow coloring and flavoring agent in foods. Curcumin has shown anti-carcinogenic activity in animal models. Curcumin possesses anti-inflammatory activity and is a potent inhibitor of reactive oxygen-generating enzymes such as lipoxygenase/cyclooxygenase, xanthine dehydrogenase/oxidase and inducible nitric oxide synthase; and an effective inducer of heme oxygenase-1. Curcumin is also a potent inhibitor of protein kinase C(PKC), EGF(Epidermal growth factor)-receptor tyrosine kinase and LĸB kinase. Subsequently, curcumin inhibits the activation of NF(nucleor factor)KB and the expressions of oncogenes including c-jun, c-fos, c-myc, NIK, MAPKs, ERK, ELK, PI3K, Akt, CDKs and iNOS. It is proposed that curcumin may suppress tumor promotion through blocking signal transduction path-ways in the target cells. The oxidant tumor promoter TPA activates PKC by reacting with zinc thiolates present within the regulatory domain, while the oxidized form of cancer chemopreventive agent such as curcumin can inactivate PKC by oxidizing the vicinal thiols present within the catalytic domain. Recent studies indicated that proteasome-mediated degradation of cell proteins playa pivotal role in the regulation of several basic cellular processes including differentiation, proliferation, cell cycling, and apoptosis. It has been demonstrated that curcumin-induced apoptosis is mediated through the impairment of ubiquitin-proteasome pathway. Curcumin was first biotransformed to dihydrocurcumin and tetrahydrocurcumin and that these compounds subsequently were converted to monoglucuronide conjugates. These results suggest that curcumin-glucuronide, dihydrocurcumin-glucuronide, tetrahydrocurcumin-glucuronide and tetrahydrocurcumin are the major metabolites of curcumin in mice, rats and humans.

• 한방비만학회지
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• 제18권2호
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• pp.74-82
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• 2018

Objectives: The objective of this study is to investigate the effects of Silbi-um (SBU) extract on the alcoholic fatty liver induced by EtOH administration for 8 weeks. Methods: Male Sprague Dawley rats were used. All animals were randomly divided into 3 groups; Normal, EtOH and EtOH+SBU. The rats of EtOH group were daily treated with ethanol of 25% (v/v) for 8 weeks (n=10). EtOH+SBU group was orally treated with SBU water extract after ethanol administration (n=10). The rats of Normal group were treated with saline (n=10). After 8 weeks, the mean body weight, liver weight, and liver-body weight ratio were calculated. The serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) of all groups were measured. The morphological alterations were observed using hematoxylin and eosin (H&E) and Oil Red O staining. Moreover, the alteration of tumor necrosis $factor-{\alpha}$ ($TNF-{\alpha}$) levels were analyzed immunohistochemistrically. Results: The histological data showed that liver sections from EtOH group displayed severe steatosis. SBU extract significantly inhibited the progression of the alcoholic liver injury. The increased serum level of ALT and AST induced by ethanol administration were decreased by SBU extract. Furthermore, SBU extract significantly decreased the liver concentrations of $TNF-{\alpha}$. Conclusions: SBU water extract attenuated the alcohol induced fatty liver by improving hepatic lipid metabolism via suppression of $TNF-{\alpha}$ protein. SBU could be effective in protecting the liver from alcoholic fatty liver.

• Molecules and Cells
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• 제42권1호
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• pp.56-66
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• 2019

Histidine triad nucleotide-binding protein (HINT) is a member of the histidine triad (HIT) superfamily, which has hydrolase activity owing to a histidine triad motif. The HIT superfamily can be divided to five classes with functions in galactose metabolism, DNA repair, and tumor suppression. HINTs are highly conserved from archaea to humans and function as tumor suppressors, translation regulators, and neuropathy inhibitors. Although the structures of HINT proteins from various species have been reported, limited structural information is available for fungal species. Here, to elucidate the structural features and functional diversity of HINTs, we determined the crystal structure of HINT from the pathogenic fungus Candida albicans (CaHINT) in complex with zinc ions at a resolution of $2.5{\AA}$. Based on structural comparisons, the monomer of CaHINT overlaid best with HINT protein from the protozoal species Leishmania major. Additionally, structural comparisons with human HINT revealed an additional helix at the C-terminus of CaHINT. Interestingly, the extended C-terminal helix interacted with the N-terminal loop (${\alpha}1-{\beta}1$) and with the ${\alpha}3$ helix, which appeared to stabilize the dimerization of CaHINT. In the C-terminal region, structural and sequence comparisons showed strong relationships among 19 diverse species from archea to humans, suggesting early separation in the course of evolution. Further studies are required to address the functional significance of variations in the C-terminal region. This structural analysis of CaHINT provided important insights into the molecular aspects of evolution within the HIT superfamily.

• Biomolecules & Therapeutics
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• 제30권5호
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• pp.465-472
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• 2022

Melanoma is one of the most aggressive skin cancers. Hypoxia contributes to the aggressiveness of melanoma by promoting cancer growth and metastasis. Upregulation of cyclin D1 can promote uncontrolled cell proliferation in melanoma, whereas stimulation of cytotoxic T cell activity can inhibit it. Epithelial mesenchymal transition (EMT) plays a critical role in melanoma metastasis. Hypoxia-inducible factor-1α (HIF-1α) is a main transcriptional mediator that regulates many genes related to hypoxia. CoCl₂ is one of the most commonly used hypoxia-mimetic chemicals in cell culture. In this study, inhibitory effects of IDF-11774, an inhibitor of HIF-1α, on melanoma growth and metastasis were examined using cultured B16F10 mouse melanoma cells and nude mice transplanted with B16F10 melanoma cells in the presence or absence of CoCl₂-induced hypoxia. IDF-11774 reduced HIF-1α upregulation and cell survival, but increased cytotoxicity of cultured melanoma cells under CoCl₂-induced hypoxia. IDF-11774 also reduced tumor size and local invasion of B16F10 melanoma in nude mice along with HIF-1α downregulation. Expression levels of cyclin D1 in melanoma were increased by CoCl₂ but decreased by IDF-11774. Apoptosis of melanoma cells and infiltration of cytotoxic T cells were increased in melanoma after treatment with IDF-11774. EMT was stimulated by CoCl₂, but restored by IDF11774. Overall, IDF-11774 inhibited the growth and metastasis of B16F10 melanoma via HIF-1α downregulation. The growth of B16F10 melanoma was inhibited by cyclin D1 downregulation and cytotoxic T cell stimulation. Metastasis of B16F10 melanoma was inhibited by EMT suppression.