• Molecules and Cells
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• 제41권12호
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• pp.1008-1015
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• 2018

$I{\kappa}B$, a cytoplasmic inhibitor of nuclear factor-${\kappa}B$ ($NF-{\kappa}B$), is reportedly degraded via the proteasome. However, we recently found that long-term incubation with proteasome inhibitors (PIs) such as PS-341 or MG132 induces $I{\kappa}B{\alpha}$ degradation via an alternative pathway, lysosome, which results in $NF-{\kappa}B$ activation and confers resistance to PI-induced lung cancer cell death. To enhance the anti-cancer efficacy of PIs, elucidation of the regulatory mechanism of PI-induced $I{\kappa}B{\alpha}$ degradation is necessary. Here, we demonstrated that PI up-regulates nuclear factor (erythroid-derived 2)-like 2 (Nrf2) via both de novo protein synthesis and Kelch-like ECH-associated protein 1 (KEAP1) degradation, which is responsible for $I{\kappa}B{\alpha}$ degradation via macroautophagy activation. PIs increased the protein level of light chain 3B (LC3B, macroautophagy marker), but not lysosome-associated membrane protein 2a (Lamp2a, the receptor for chaperone-mediated autophagy) in NCI-H157 and A549 lung cancer cells. Pretreatment with macroautophagy inhibitor or knock-down of LC3B blocked PI-induced $I{\kappa}B{\alpha}$ degradation. PIs up-regulated Nrf2 by increasing its transcription and mediating degradation of KEAP1 (cytoplasmic inhibitor of Nrf2). Overexpression of dominant-negative Nrf2, which lacks an N-terminal transactivating domain, or knock-down of Nrf2 suppressed PI-induced LC3B protein expression and subsequent $I{\kappa}B{\alpha}$ degradation. Thus, blocking of the Nrf2 pathway enhanced PI-induced cell death. These findings suggest that Nrf2-driven induction of LC3B plays an essential role in PI-induced activation of the $I{\kappa}B$/$NF-{\kappa}B$ pathway, which attenuates the anti-tumor efficacy of PIs.

• 한국수정란이식학회지
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• 제32권4호
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• pp.257-265
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• 2017

Ferulic Acid (FA) is a metabolite of phenylalanine and tyrosine, a phenolic compound commonly found in fruits and vegetables. Several studies have shown that FA has various functions such as antioxidant effect, prevention of cell damage from irradiation, protection from cell damage caused by oxygen deficiency, anti-inflammatory action, anti-aging action, liver protective effect and anti-cancer action. In this study, we investigated the maturation rate, intracellular glutathione (GSH) and reactive oxygen species (ROS) of porcine oocytes by adding FA to the in vitro maturation (IVM) medium and examined subsequent embryonic developmental competence at 5% oxygen through parthenogenesis. There is no significant difference between the control group ($0{\mu}M$) and treatment groups ($5{\mu}M$, $10{\mu}M$, $20{\mu}M$) on maturation rates. Intracellular GSH levels in oocyte treated with $5{\mu}M$ of FA significantly increased (P < 0.05), and $20{\mu}M$ of FA revealed significant decrease (P < 0.05) in intracellular ROS levels compared with the control group. Oocytes treated with FA exhibited significantly higher cleavage rates (79.01% vs 89.19%, 92.20%, 90.89%, respectively) than the control group. Oocytes treated with $10{\mu}M$ showed significantly higher blastocyst formation rates (28.3% vs 40.3%, respectively) after PA than the control group. Total cell numbers in blastocyst of $10{\mu}M$ FA displayed significantly higher (39.4 vs 51.9, respectively) than the control group. In conclusion, these results suggested that treatment with FA during IVM improved the developmental potential of porcine embryos by increasing intracellular GSH synthesis and reducing ROS levels. Also, there was an improvement of cleavage rate, blastocyst formation and total cell numbers in blastocysts. It might be associated with Keap1-Nrf2 pathway as an antioxidant regulate pathway that plays a crucial role in determining the sensitivity of cells to oxidative damages by regulating the basal and inducible expression of enzymes which is related to detoxification and anti-oxidative effects, stress response enzymes and/or proteins and ABC transporters.

• Molecules and Cells
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• 제46권3호
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• pp.142-152
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• 2023

Nuclear factor erythroid 2-related factor 2 (Nrf2) mediates the cellular antioxidant response, allowing adaptation and survival under conditions of oxidative, electrophilic and inflammatory stress, and has a role in metabolism, inflammation and immunity. Activation of Nrf2 provides broad and long-lasting cytoprotection, and is often hijacked by cancer cells, allowing their survival under unfavorable conditions. Moreover, Nrf2 activation in established human tumors is associated with resistance to chemo-, radio-, and immunotherapies. In addition to cancer cells, Nrf2 activation can also occur in tumor-associated macrophages (TAMs) and facilitate an anti-inflammatory, immunosuppressive tumor immune microenvironment (TIME). Several cancer cell-derived metabolites, such as itaconate, L-kynurenine, lactic acid and hyaluronic acid, play an important role in modulating the TIME and tumor-TAMs crosstalk, and have been shown to activate Nrf2. The effects of Nrf2 in TIME are context-depended, and involve multiple mechanisms, including suppression of proinflammatory cytokines, increased expression of programmed cell death ligand 1 (PD-L1), macrophage colony-stimulating factor (M-CSF) and kynureninase, accelerated catabolism of cytotoxic labile heme, and facilitating the metabolic adaptation of TAMs. This understanding presents both challenges and opportunities for strategic targeting of Nrf2 in cancer.

• Toxicological Research
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• 제23권3호
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• pp.207-214
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• 2007

Chronic oxidative stress produced by exposure to environmental chemicals or pathophysiological states can lead animals to aging, carcinogenesis and degenerative diseases. Indirect antioxidative mechanisms, in which natural or synthetic agents are used to coordinately induce the expression of cellular antioxidant capacity, have been shown to protect cells and organisms from oxidative damages. Electrophile and free radical detoxifying enzymes, which were originally identified as the products of genes induced by cancer chemopreventive agents, are members of this protective system. The NFE2 family transcription factor Nrf2 was found to govern expression of these detoxifying enzymes, and screening for Nrf2-regulated genes has identified many gene categories involved in maintaining cellular redox potential and protection from oxidative damage as Nrf2 downstream genes. Further, studies using Nrf2-deficient mice revealed that these mutant mice showed more susceptible phenotypes towards exposure to environmental chemicals/carcinogens and in oxidative stress related disease models. With the finding that cancer chemopreventive efficacy of indirect antioxidants (enzyme inducers) is lost in the absence of Nrf2, a central role of Nrf2 in the antioxidative protective system has been firmly established. Promising results from cancer prevention clinical trials using enzyme inducers propose that pharmacological interventions that modulate Nrf2 can be an effective strategy to protect tissues from oxidative damage.

• Nutrition Research and Practice
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• 제11권3호
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• pp.206-213
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• 2017

BACKGROUN/OBJECTIVES: Although studies have revealed that black garlic is a potent antioxidant, its antioxidant mechanism remains unclear. The objective of this study was to determine black garlic's antioxidant activities and possible antioxidant mechanisms related to nuclear factor erythroid 2-like factor 2 (Nrf2)-Keap1 complex. METHODS/MATERIALS: After four weeks of feeding rats with a normal fat diet (NF), a high-fat diet (HF), a high-fat diet with 0.5% black garlic extract (HF+BGE 0.5), a high-fat diet with 1.0% black garlic extract (HF+BGE 1.0), or a high-fat diet with 1.5% black garlic extract (HF+BGE 1.5), plasma concentrations of glucose, insulin,homeostatic model assessment of insulin resistance (HOMA-IR) were determined. As oxidative stress indices, plasma concentrations of thiobarbituric acid reactive substances (TBARS) and 8-isoprostaglandin $F2{\alpha}$ (8-iso-PGF) were determined. To measure antioxidant capacities, plasma total antioxidant capacity (TAC) and activities of antioxidant enzymes in plasma and liver were determined. The mRNA expression levels of antioxidant related proteins such as Nrf2, NAD(P)H: quinone-oxidoreductase-1 (NQO1), heme oxygenase-1 (HO-1), glutathione reductase (GR), and glutathione S-transferase alpha 2 (GSTA2) were examined. RESULTS: Plasma glucose level, plasma insulin level, and HOMA-IR in black garlic supplemented groups were significantly (P < 0.05) lower than those in the HF group without dose-dependent effect. Plasma TBARS concentration and TAC in the HF+BGE 1.5 group were significantly decreased compared to those of the HF group. The activities of catalase and glutathione peroxidase were significantly (P < 0.05) increased in the HF+BGE 1.0 and HF+BGE 1.5 groups compared to those of the HF group. The mRNA expression levels of hepatic Nrf2, NQO1, HO-1, and GSTA2 were significantly (P < 0.05) increased in the HF with BGE groups compared to those in the HF group. CONCLUSIONS: The improvements of blood glucose homeostasis and antioxidant systems in rats fed with black garlic extract were related to mRNA expression levels of Nrf2 related genes.

• IMMUNE NETWORK
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• 제11권6호
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• pp.376-382
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• 2011

Background: Carbon monoxide (CO) is a cytoprotective and homeostatic molecule with important signaling capabilities in physiological and pathophysiological situations. CO protects cells/tissues from damage by free radicals or oxidative stress. NAD(P)H:quinone oxidoreductase (NQO1) is a highly inducible enzyme that is regulated by the Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway, which is central to efficient detoxification of reactive metabolites and reactive oxygen species (ROS). Methods: We generated NQO1 promoter construct. HepG2 cells were treated with CO Releasing Molecules-2 (CORM-2) or CO gas and the gene expressions were measured by RT-PCR, immunoblot, and luciferase assays. Results: CO induced expression of NQO1 in human hepatocarcinoma cell lines by activation of Nrf2. Exposure of HepG2 cells to CO resulted in significant induction of NQO1 in dose- and time-dependent manners. Analysis of the NQO1 promoter indicated that an antioxidant responsible element (ARE)-containing region was critical for the CO-induced Nrf2-dependent increase of NQO1 gene expression in HepG2 cells. Conclusion: Our results suggest that CO-induced Nrf2 increases the expression of NQO1 which is well known to detoxify reactive metabolites and ROS.

• 대한한방내과학회지
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• 제42권1호
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• pp.1-10
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• 2021

Objective: This study was conducted to investigate the effect of Chaenomelis Fructus (CF) water extract on thioacetamide (TAA)-treated rats. Methods: Rats were divided into five groups: one normal group (n=8) and four with TAA-induced hepatic injury. These treatment groups were administered distilled water (n=8); silymarin 100 mg/kg (n=8); CF 100 mg/kg (n=8); and CF 200 mg/kg (n=8). In the TAA groups, the acute liver injury was induced via IP injection (200 mg/kg), and the silymarin and CF extract were then orally administered for three days. Subsequently, serum levels of GOT, GPT, and ammonia were confirmed as well as protein expressions using liver tissue. Results: In the liver injury-induced rats, CF administration reduced tissue damage and serum levels of GOT, GPT, and ammonia. In addition, CF increased the anti-oxidant proteins Nrf2, Keap1, HO-1, and catalase and significantly regulated matrix metalloproteinases (MMP-2 and MMP-9) and their tissue inhibitors (TIMP-1 and TIMP-2). Conclusions: In this animal model of liver injury induced by TAA, CF extract is determined to have a hepatoprotective effect by increasing anti-oxidant proteins that relieve damage and by regulating the expression of matrix metalloproteinases.

• The Korean Journal of Physiology and Pharmacology
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• 제20권3호
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• pp.229-236
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• 2016

Resveratrol (RSV) may provide numerous protective effects against chronic inflammatory diseases. Due to local hypoxia and hypertonicity, the renal medulla is subject to extreme oxidative stress, and aldehyde products formed during lipid peroxidation, such as 4-hydroxy-2-hexenal (HHE), might be responsible for tubular injury. This study aimed at investigating the effects of RSV on renal and its signaling mechanisms. While HHE treatment resulted in decreased expression of Sirt1, AQP2, and nuclear factor erythroid 2-related factor 2 (Nrf2), mouse cortical collecting duct cells (M1) cells treated with HHE exhibited increased activation of p38 MAPK, extracellular signal regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and increased expression of NOX4, $p47^{phox}$, Kelch ECH associating protein 1 (Keap1) and COX2. HHE treatment also induced $NF-{\kappa}B$ activation by promoting $I{\kappa}B-{\alpha}$ degradation. Meanwhile, the observed increases in nuclear $NF-{\kappa}B$, NOX4, $p47^{phox}$, and COX2 expression were attenuated by treatment with Bay 117082, N-acetyl-l-cysteine (NAC), or RSV. Our findings indicate that RSV inhibits the expression of inflammatory proteins and the production of reactive oxygen species in M1 cells by inhibiting $NF-{\kappa}B$ activation.

• The Korean Journal of Physiology and Pharmacology
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• 제20권1호
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• pp.15-23
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• 2016

Acetaminophen (APAP) overdose is one of the most common causes of acute liver failure. The study aimed to investigate the protective effect of carnosic acid (CA) on APAP-induced acute hepatotoxicity and its underlying mechanism in mice. To induce hepatotoxicity, APAP solution (400 mg/kg) was administered into mice by intraperitoneal injection. Histological analysis revealed that CA treatment significantly ameliorated APAP-induced hepatic necrosis. The levels of both alanine aminotransferase (ALT) and aspartate transaminase (AST) in serum were reduced by CA treatment. Moreover, CA treatment significantly inhibited APAP-induced hepatocytes necrosis and lactate dehydrogenase (LDH) releasing. Western blot analysis showed that CA abrogated APAP-induced cleaved caspase-3, Bax and phosphorylated JNK protein expression. Further results showed that CA treatment markedly inhibited APAP-induced pro-inflammatory cytokines TNF-${\alpha}$, IL-$1{\beta}$, IL-6 and MCP-1 mRNA expression and the levels of phosphorylated $I{\kappa}B{\alpha}$ and p65 protein in the liver. In addition, CA treatment reduced APAP- induced hepatic malondialdehyde (MDA) contents and reactive oxygen species (ROS) accumulation. Conversely, hepatic glutathione (GSH) level was increased by administration of CA in APAP-treated mice. Mechanistically, CA facilitated Nrf2 translocation into nuclear through blocking the interaction between Nrf2 and Keap1, which, in turn, upregulated anti-oxidant genes mRNA expression. Taken together, our results indicate that CA facilitates Nrf2 nuclear translocation, causing induction of Nrf2-dependent genes, which contributes to protection from acetaminophen hepatotoxicity.

• 생약학회지
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• 제51권4호
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• pp.349-359
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• 2020

Gastroesophageal reflux disease (GERD) is a disease that stomach contents continually refluxing, and is currently on the rise worldwide. The purpose of this study is to find natural materials that can reduce side effects and effectively treat chronic acid reflux esophagitis (CARE), one of GERD. First, the antioxidant activity was confirmed by varying the mixing ratio of Coptidis Rhizoma and Evodiae Fructus, which are effective against chronic reflux esophagitis. After, animal experiments were conducted using a 1:1 (CE) and 1:2 (CEE) combination ratio of Coptidis Rhizoma and Evodiae Fructus, which had the best antioxidant efficacy. Gross lesion of esophageal mucosa after CE or CEE treatment showed a superior enhancement compared with that of CARE control rats. Additionally, its inhibited MAPK phosphorylation and led NF-κB inactivation through the suppression of IκBα phosporylation by regulating Nrf2/Keap-1, and NF-κB inactivation induced reduced protein expressions including inflammatory mediators and cytokines. Moreover, its improved esophageal barrier function through upregulating protein expressions of tight junction protein, whereas downregulating protein expressions of MMPs. Taken together, a mixture of Coptidis Rhizoma and Evodiae Fructus can attenuate the esophageal mucosal ulcer by inhibiting MAPK and NF-κB pathway, and upregulating proteins associated with tight junction.