• Tuberculosis and Respiratory Diseases
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• v.62 no.1
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• pp.33-42
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• 2007

Background: Heme oxygenase-1 (HO-1) is known to modulates the cellular functions, including cell proliferation and apoptosis. It is known that a high level of HO-1 expression is found in many tumors, and HO-1 plays an important role in rapid tumor growth on account of its antioxidant and antiapoptotic effects. Cisplatin is a widely used anti-cancer agent for the treatment of lung cancer. However, the development of resistance to cisplatin is a major obstacle to its use in clinical treatment. We previously demonstrated that inhibiting HO-1 expression through the transcriptional activation of Nrf2 induces apoptosis in A549 cells. The aim of this study was to determine of the inhibiting HO-1 enhance the chemosensitivity of A549 cells to cisplatin. Materials and Methods: The human lung cancer cell line, A549, was treated cisplatin, and the cell viability was measured by a MTT assay. The change in HO-1, Nrf2, and MAPK expression after the cisplatin treatment was examined by Western blotting. HO-1 inhibition was suppressed by ZnPP, which is a specific pharmacologic inhibitor of HO activity, and small interfering RNA (siRNA). Flow cytometry analysis and Western blot were performed in to determine the level of apoptosis. The level of hydrogen peroxide ($H_2O_2$) generation was monitored fluoimetrically using 2',7'-dichlorofluorescein diacetate. Results: The A549 cells showed more resistance to the cisplatin treatment than the other cell lines examined, whereas cisplatin increased the expression of HO-1 and Nrf2, as well as the phosphorylation of MAPK in a time-dependent fashion. Inhibitors of the MAPK pathway blocked the induction of HO-1 and Nrf2 by the cisplatin treatment in A549 cells. In addition, the cisplatin-treated A549 cells transfected with dither the HO-1 small interfering RNA (siRNA) or ZnPP, specific HO-1 inhibitor, showed in a more significantly decrease in viability than the cisplatin-only-treated group. The combination treatment of ZnPP and cisplatin caused in a marked increase in the ROS generation and a decrease in the HO-1 expression. Conclusion: Cisplatin increases the expression of HO-1, probably through the MAPK-Nrf2 pathway, and the inhibition of HO-1 enhances the chemosensitivity of A549 cells to cisplatin.

• Journal of Life Science
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• v.21 no.4
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• pp.486-493
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• 2011

Nitric oxide (NO) donors are a potent inducer of heme oxygenase-1 (HO-1). However, it is unclear whether or not HO-1 expression induced by NO donors is a direct consequence of NO released by NO donors. Here, we investigated the effects of NO donors on the expression of HO-1 in primary rat articular chondrocytes. NO donors (SIN-1, SNAP, and SNP) significantly induced the accumulation of HO-1 protein accompanied by an increase in HO-1 mRNA. NO donor-induced HO-1 expression exerted cytoprotection against NO and/or superoxide-induced cell death. Guanylate cyclase signaling was not associated with Nrf2 and HO-1 expression in NO donor-treated chondrocytes. Interestingly, NO scavenger carboxy-PTIO and SOD mimetic TEMPOL markedly inhibited NO donor-induced HO-1 expression in chondrocytes. In addition, NO donor-induced HO-1 expression was completely abrogated by the peroxynitrite scavenger MnTBAP. Since peroxynitrite can be physiologcally formed in the cell through reaction of NO with superoxide, we analyzed whether or not peroxynitrite could directly induce HO-1 expression in chondrocytes. Peroxynitrite treatment in chondrocytes evoked doseand time-dependent Nrf2 and HO-1 expression. These results indicate that HO-1 expression induced by NO donors in rat articular chondrocytes is due to NO-mediated peroxynitrite rather than NO.

• Biomolecules & Therapeutics
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• v.22 no.6
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• pp.497-502
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• 2014

In the present study, we found that the natural compound arctigenin inhibited hydrogen peroxide-induced reactive oxygen species (ROS) production in rat primary astrocytes. Since hemeoxygenase-1 (HO-1) plays a critical role as an antioxidant defense factor in the brain, we examined the effect of arctigenin on HO-1 expression in rat primary astrocytes. We found that arctigenin increased HO-1 mRNA and protein levels. Arctigenin also increases the nuclear translocation and DNA binding of Nrf2/c-Jun to the antioxidant response element (ARE) on HO-1 promoter. In addition, arctigenin increased ARE-mediated transcriptional activities in rat primary astrocytes. Further mechanistic studies revealed that arctigenin increased the phosphorylation of AKT, a downstream substrate of phosphatidylinositol 3-kinase (PI3K). Treatment of cells with a PI3K-specific inhibitor, LY294002, suppressed the HO-1 expression, Nrf2 DNA binding and ARE-mediated transcriptional activities in arctigenin-treated astrocyte cells. The results collectively suggest that PI3K/AKT signaling pathway is at least partly involved in HO-1 expression by arctigenin via modulation of Nrf2/ARE axis in rat primary astrocytes.

• BMB Reports
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• v.47 no.2
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• pp.98-103
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• 2014

Orostachys japonicus shows various biological activities. However, the molecular mechanisms remain unknown in LPS-stimulated macrophages. Here, we investigated the anti-oxidizing effect of the dichloromethane (DCM) and hexane fractions from O. japonicus (OJD and OJH) against oxidative stress in RAW 264.7 cells stimulated by LPS. OJD and OJH significantly increased the expression of heme oxygenase-1 (HO-1) in a dose- and time-dependent manner. Additionally, it was found that the expression of HO-1 was stimulated by Nrf2 activated via degradation of Keap1. ERK and p38 inhibitors repressed HO-1 induced by OJD and OJH in LPS-stimulated cells, respectively. In conclusion, these results suggest that OJD and OJH may block oxidative damage stimulated by LPS, via increasing the expression of HO-1 and Nrf2, and MAPK signaling pathway.

• Journal of Microbiology and Biotechnology
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• v.28 no.8
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• pp.1310-1317
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• 2018

The stems of Dendrobium moniliforme have been used in traditional herbal medicine for the treatment of fever and lack of body fluid in Korea. In this study, we investigated anti-inflammatory effects of the aqueous extract of D. moniliforme stems (DM) in response to lipoteichoic acid (LTA), a major constituent of the cell wall of Gram-positive bacteria. DM inhibited LTA-induced expression of a pro-inflammatory mediator inducible nitric oxide synthase (iNOS) in the murine macrophages. And DM induced expression of heme oxygenase-1 (HO-1) at the transcriptional level. Conversely, the knockdown of HO-1 expression by siRNA markedly reversed the inhibitory effects of DM on LTA-induced iNOS expression. We also demonstrated that nuclear translocation of Nrf2 was increased following treatment with DM. In addition, DM-mediated Nrf2 activation and HO-1 expression were suppressed by PI3K/Akt and p38 inhibitors; treatment with DM also resulted in phosphorylation of Akt and p38. These results suggest that DM inhibits the expression of iNOS in LTA-stimulated macrophages, and that these effects are mediated by the upregulation of HO-1 expression via PI3K/Akt/p38-Nrf2 signaling.

• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2317-2320
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• 2013

Thiourea and vinyl sulfoxide derivatives were designed based on the structures of sulforaphane and gallic acid, prepared and tested for HO-1 inducing activity as a measure of Nrf2 activation, and inhibitory effect on NO production as a measure of anti-inflammatory activity. Both series of compounds showed moderate activity on HO-1 induction, and no inhibitory effect on NO production. Interestingly the thiourea compound 6d showed better HO-1 induction (71% SFN) than the corresponding isothiocyanate compound 6a (55% SFN). Overall, it seemed that more efficient electrophile is needed to get more effective Nrf2 activator.

• Biomolecules & Therapeutics
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• v.24 no.3
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• pp.268-282
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• 2016

In the present study, we investigated the anti-inflammatory properties of Eucommia ulmoides Oliv. Bark. (EUE) in lipopolysaccharide (LPS)-stimulated microglial BV-2 cells and found that EUE inhibited LPS-mediated up-regulation of pro-inflammatory response factors. In addition, EUE inhibited the elevated production of pro-inflammatory cytokines, mediators, and reactive oxygen species (ROS) in LPS-stimulated BV-2 microglial cells. Subsequent mechanistic studies revealed that EUE suppressed LPS-induced phosphorylation of mitogen-activated protein kinases (MAPKs), phosphoinositide-3-kinase (PI3K)/Akt, glycogen synthase $kinase-3{\beta}$ ($GSK-3{\beta}$), and their downstream transcription factor, nuclear factor-kappa B ($NF-{\kappa}B$). EUE also blocked the nuclear translocation of $NF-{\kappa}B$ and inhibited its binding to DNA. We next demonstrated that EUE induced the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and upregulated heme oxygenase-1 (HO-1) expression. We determined that the significant up-regulation of HO-1 expression by EUE was a consequence of Nrf2 nuclear translocation; furthermore, EUE increased the DNA binding of Nrf2. In contrast, zinc protoporphyrin (ZnPP), a specific HO-1 inhibitor, blocked the ability of EUE to inhibit NO and $PGE_2$ production, indicating the vital role of HO-1. Overall, our results indicate that EUE inhibits pro-inflammatory responses by modulating MAPKs, PI3K/Akt, and $GSK-3{\beta}$, consequently suppressing $NF-{\kappa}B$ activation and inducing Nrf2-dependent HO-1 activation.

• Journal of Physiology & Pathology in Korean Medicine
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• v.27 no.6
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• pp.745-751
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• 2013

Safflower (Carthamus tinctorius L.) seeds have been used in Korea and China for promoting bone formation and protection. This study was designed to examine the Nrf-2 mediated anti-oxidative effects of Korean and Chinese safflower seeds. Water and ethanol extracts of safflower seeds were treated to RAW 264.7 cells. Nrf-2 transcriptional activity was measured by reporter gene assay and western blot analysis. Semi-quantitive RT-PCR analysis was adopted to measure Nrf-2 dependent gene expressions. Water extracts of safflower seeds have strongly induced the activation of Nrf-2 transcription than ethanol extracts. Especially, water extracts of Korean safflower seeds has more strongly increased the expression of nuclear Nrf-2. Water extracts of Korea and China safflower seeds have also increased the expression of Nrf-2-dependent genes such as GCLC, NQO-1 and HO-1 in RAW 264.7 cells. However, all kinds of safflower seeds extracts did not increase intracellular ROS production. These results demonstrate that the antioxidant effects of safflower seeds are not related with ROS production, rather it is mediated by the direct activation of Nrf-2.

• The Korean Journal of Physiology and Pharmacology
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• v.24 no.6
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• pp.481-492
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• 2020

The present study aimed to examine the effect of allyl isothiocyanate (AITC) on chronic obstructive pulmonary disease and to investigate whether upregulation of multidrug resistance-associated protein 1 (MRP1) associated with the activation of the PARK7 (DJ-1)/nuclear factor erythroid 2-related factor 2 (Nrf2) axis. Lung function indexes and histopathological changes in mice were assessed by lung function detection and H&E staining. The expression levels of Nrf2, MRP1, heme oxygenase-1 (HO-1), and DJ-1 were determined by immunohistochemistry, Western blotting and reverse transcription-quantitative polymerase chain reaction. Next, the expression of DJ-1 in human bronchial epithelial (16HBE) cells was silenced by siRNA, and the effect of DJ-1 expression level on cigarette smoke extract (CSE)-stimulated protein degradation and AITC-induced protein expression was examined. The expression of DJ-1, Nrf2, HO-1, and MRP1 was significantly decreased in the wild type model group, while the expression of each protein was significantly increased after administration of AITC. Silencing the expression of DJ-1 in 16HBE cells accelerated CSE-induced protein degradation, and significantly attenuated the AITC-induced mRNA and protein expression of Nrf2 and MRP1. The present study describes a novel mechanism by which AITC induces MRP1 expression by protecting against CS/CSE-mediated DJ-1 protein degradation via activation of the DJ-1/Nrf2 axis.

• BMB Reports
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• v.45 no.11
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• pp.647-652
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• 2012

We previously reported that MSTO-211H cells have a higher capacity to regulate Nrf2 activation in response to changes in the cellular redox environment. To further characterize its biological significance, the response of Nrf2, a transcription factor that regulates ARE-containing genes, on the synergistic cytotoxic effect of clofarabine and resveratrol was investigated in mesothelioma cells. The combination treatment showed a marked growth-inhibitory effect, which was accompanied by suppression of Nrf2 activation and decreased expression of heme oxygenase-1 (HO-1). While transient overexpression of Nrf2 conferred protection against the cytotoxicity caused by their combination, knockdown of Nrf2 expression using siRNA enhanced their cytotoxic effect. Pretreatment with Ly294002, a PI3K inhibitor, augmented the decrease in HO-1 level by their combination, whereas no obvious changes were observed in Nrf2 levels. Altogether, these results suggest that the synergistic cytotoxic effect of clofarabine and resveratrol was mediated, at least in part, through suppression of Nrf2 signaling.