• Molecules and Cells
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• v.23 no.2
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• pp.198-206
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• 2007

Hydroquinone is a toxic compound and a major benzene metabolite. We report that it strongly inhibits the activation of macrophages and associated cells. Thus, it suppressed the production of proinflammatory cytokines [tumor necrosis factor (TNF)-${\alpha}$, interleukin (IL)-$1{\beta}$, IL-3, IL-6, IL-10, IL-12p40, IL-23], secretion of toxic molecules [nitric oxide (NO) and reactive oxygen species (ROS)] and the activation and expression of CD29 as judged by cell-cell adhesion and surface staining experiments. The inhibition was due to the induction of heme oxygenase (HO)-1 in LPS-activated macrophages, since blocking HO-1 activity with ZnPP, an HO-1 specific inhibitor, abolished hydroquinone's NO inhibitory activity. In addition, hydroquinone and inhibitors (wortmannin and LY294002) of the phosphatidylinositol-3 kinase (PI3K)/Akt pathway had very similar inhibitory effects on LPS-induced and CD29-mediated macrophage responses, including the phoshorylation of Akt. Therefore, our data suggest that hydroquinone inhibits macrophage-mediated immune responses by modulating intracellular signaling and protective mechanisms.

• The Korean Journal of Physiology and Pharmacology
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• v.27 no.6
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• pp.513-520
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• 2023

Cornuside is a secoiridoid glucoside compound extracted from the fruits of Cornus officinalis. Cornuside has immunomodulatory and anti-inflammatory properties; however, its potential therapeutic effects on diabetic nephropathy (DN) have not been completely explored. In this study, we established an in vitro model of DN through treating mesangial cells (MMCs) with glucose. MMCs were then treated with different concentrations of cornuside (0, 5, 10, and 30 μM). Cell viability was determined using cell counting kit-8 and 5-ethynyl-2'-deoxyuridine assays. Levels of proinflammatory cytokines, including interleukin (IL)-6, tumor necrosis factor-α, and IL-1β were examined using enzyme-linked immunosorbent assay. Reverse transcription quantitative real-time polymerase chain reaction and Western blotting were performed to detect the expression of AKT and nuclear factor-kappa B (NF-κB)-associated genes. We found that cornuside treatment significantly reduced glucose-induced increase in MMC viability and expression of pro-inflammatory cytokines. Moreover, cornuside inhibited glucose-induced phosphorylation of AKT and NF-κB inhibitor alpha, decreased the expression of proliferating cell nuclear antigen and cyclin D1, and increased the expression of p21. Our study indicates that the anti-inflammatory properties of cornuside in DN are due to AKT and NF-κB inactivation in MMCs.

• Molecules and Cells
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• v.43 no.10
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• pp.856-869
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• 2020

To elucidate the mechanism of action of HOXA11-AS in modulating the cisplatin resistance of nasopharyngeal carcinoma (NPC) cells. HOXA11-AS and miR-454-3p expression in NPC tissue and cisplatin-resistant NPC cells were measured via quantitative reverse transcriptase polymerase chain reaction. NPC parental cells (C666-1 and HNE1) and cisplatin-resistant cells (C666-1/DDP and HNE1/DDP) were transfected and divided into different groups, after which the MTT method was used to determine the inhibitory concentration 50 (IC₅₀) of cells treated with different concentrations of cisplatin. Additionally, a clone formation assay, flow cytometry and Western blotting were used to detect DDP-induced changes. Thereafter, xenograft mouse models were constructed to verify the in vitro results. Obviously elevated HOXA11-AS and reduced miR-454-3p were found in NPC tissue and cisplatin-resistant NPC cells. Compared to the control cells, cells in the si-HOXA11-AS group showed sharp decreases in cell viability and IC₅₀, and these results were reversed in the miR-454-3p inhibitor group. Furthermore, HOXA11-AS targeted miR-454-3p, which further targeted c-Met. In comparison with cells in the control group, HNE1/DDP and C666-1/DDP cells in the si-HOXA11-AS group demonstrated fewer colonies, with an increase in the apoptotic rate, while the expression levels of c-Met, p-Akt/Akt and p-mTOR/mTOR decreased. Moreover, the si-HOXA11-AS-induced enhancement in sensitivity to cisplatin was abolished by miR-454-3p inhibitor transfection. The in vivo experiment showed that DDP in combination with si-HOXA11-AS treatment could inhibit the growth of xenograft tumors. Silencing HOXA11-AS can inhibit the c-Met/AKT/mTOR pathway by specifically upregulating miR-454-3p, thus promoting cell apoptosis and enhancing the sensitivity of cisplatin-resistant NPC cells to cisplatin.

• Journal of Embryo Transfer
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• v.24 no.1
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• pp.57-64
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• 2009

This study was carried out to investigate expression of apoptosis-related differentially expressed gene (DEG) in ovaries of Korean cattle with follicular and luteal cysts and to identify the relationship between cyst and apoptosis using microarray, real-time PCR, TUNEL staining, and Western blot analysis. Microarray data showed that PIK3R2 and AKT1 were significantly up-regulated in follicular cyst, and TNF-RAF2, PRLR, FOXL2, STK4, and COL4A3 were up-regulated whereas INHA, CIDEB, BCL10, and FASLG were down-regulated in luteal cyst. Real-time PCR was performed to validate DEGs altered in luteal cyst. Of nine DEGs, four DEGs down-regulated in luteal cyst showed a positive corelation between microarray data and real-time PCR data. In this study, we focused on INHA, among many DEGs, which was highly down-regulated in both follicular and luteal cysts. Real-time PCR and micro array data showed that INHA was down-regulated by 12.3-fold and by 1.4-fold, respectively, in the bovine follicular cyst. TUNEL assay and Western blot analysis for ERK, JNK, p38, PI3K, and Akt, which were used to detect whether apoptosis is occurred, showed no significant changes in cystic ovaries (p>0.05). In the expression and activity of caspase-3, Bax, Bel-2, and Bel-xL, there was no significant changes between follicular cystic ovary and normal ovary. Rather, the expression levels of PI3K and p-Akt were decreased in follicular cystic ovary. These results suggest that deficiency of apoptosis in cystic ovary is associated with decreased expression of apoptotic effectors.

• Journal of Life Science
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• v.29 no.4
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• pp.402-409
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• 2019

Korean red ginseng made from steaming and drying fresh ginseng has long been used as a traditional herbal medicine due to its effects on the immune, endocrine, and central nerve systems and its anti-inflammatory activity. In this study, we investigated the molecular mechanism responsible for the anti-inflammatory effects of a formulated Korean red ginseng extract (RGE) in response to lipoteichoic acid (LTA), a cell wall component of gram-positive bacteria. RGE inhibited LTA-induced nitric oxide (NO) secretion and inducible nitric oxide synthase (iNOS) expression in BV-2 microglial cells, without affecting cell viability. RGE also inhibited nuclear translocation of nuclear factor kappa B ($NF-{\kappa}B$) p65 and degradation of $I{\kappa}B-{\alpha}$. In addition, RGE increased the expression of heme oxygenase-1 (HO-1) in a dose-dependent manner, and the inhibitory effect of RGE on iNOS expression was abrogated by small interfering RNA-mediated knockdown of HO-1. Moreover, RGE induced nuclear translocation of nuclear factor E2-related factor 2 (Nrf2), a transcription factor that regulates HO-1 expression. Furthermore, the phosphoinositide-3-kinase (PI-3K) inhibitor and mitogen-activated protein kinase (MAPK) inhibitors suppressed RGE-mediated expression of HO-1, and RGE enhanced the phosphorylation of Akt, extracellular signal-regulated kinases (ERKs), p38, and c-JUN N-terminal kinases (JNKs). These results suggested that RGE suppressed the production of NO, a proinflammatory mediator, by inducing HO-1 expression via PI-3K/Akt- and MAPK-dependent signaling in LTA-stimulated microglia. The findings indicate that RGE could be used for the treatment of neuroinflammation induced by grampositive bacteria and that it may have therapeutic potential for various neuroinflammation-associated disorders.

• Natural Product Sciences
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• v.26 no.3
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• pp.221-229
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• 2020

This study was undertaken to investigate the protective effect of rice bran oil (RBO) on amyloid β protein (Aβ) (25-35)-induced memory impairment and brain damage in an ICR mouse model. Memory impairment was produced by intracerebroventricular microinjection of 15 nmol Aβ (25-35) and assessed using the passive avoidance test. Treatment with RBO at 0.1, 0.5, or 1 mL/kg (p.o. daily for 8 days) protected against Aβ (25-35)-induced memory impairment. Furthermore, Aβ (25-35)-induced decreases in glutathione and increases in lipid peroxidation and cholinesterase activity in brain tissue were inhibited by RBO, and Aβ (25-35)-induced increases of phosphorylated mitogen-activated protein kinases (MAPKs) and inflammatory factors, and changes in the levels of apoptosis-related proteins were significantly inhibited by RBO. Furthermore, Aβ (25-35) suppressed the PI3K/Akt pathway and the phosphorylation of CREB, but increased phosphorylation of tau (p-tau) in mice brain; these effects were significantly inhibited by administration of RBO. These results suggest that RBO inhibits Aβ (25-35)-induced memory impairment by inducing anti-apoptotic and anti-inflammatory effects, promoting PI3K/Akt/CREB signaling, and thus, inhibiting p-tau formation.

• Molecules and Cells
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• v.41 no.11
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• pp.964-970
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• 2018

Atherosclerosis preferentially involves in prone area of low and disturbed blood flow while steady and high levels of laminar blood flow are relatively protected from atherosclerosis. Disturbed flow induces endoplasmic reticulum (ER) stress and the unfolded protein response (UPR). ER stress is caused under stress that disturbs the processing and folding of proteins resulting in the accumulation of misfolded proteins in the ER and activation of the UPR. Prolonged or severe UPR leads to activate apoptotic signaling. Recent studies have indicated that disturbed flow significantly up-regulated $p-ATF6{\alpha}$, $p-IRE1{\alpha}$, and its target spliced XBP-1. However, the role of laminar flow in ER stress-mediated endothelial apoptosis has not been reported yet. The present study thus investigated the role of laminar flow in ER stress-dependent endothelial cell death. The results demonstrated that laminar flow protects ER stress-induced cleavage forms of PARP-1 and caspase-3. Also, laminar flow inhibits ER stress-induced $p-eIF2{\alpha}$, ATF4, CHOP, spliced XBP-1, ATF6 and JNK pathway; these effects are abrogated by pharmacological inhibition of PI3K with wortmannin. Finally, nitric oxide affects thapsigargin-induced cell death in response to laminar flow but not UPR. Taken together, these findings indicate that laminar flow inhibits UPR and ER stress-induced endothelial cell death via PI3K/Akt pathway.

• BMB Reports
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• v.53 no.7
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• pp.373-378
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• 2020

Phosphorylation of the signaling component by protein kinase often leads to a kinase cascade or feedback loop. 3-Phosphoinositide-dependent kinase 1 (PDK1) signaling pathway diverges into various kinases including Akt and p70 S6 kinase (p70S6k). However, the PDK1 feedback mechanism remains elusive. Here, we demonstrated that UNC-51-like kinase (ULK1), an autophagy initiator kinase downstream of mechanistic target of rapamycin (mTOR), directly phosphorylated PDK1 on serine 389 at the linker region. Furthermore, our data showed that this phosphorylation affected the kinase activity of PDK1 toward downstream substrates. These results suggest a possible negative feedback loop between PDK1 and ULK1.

• Biomolecules & Therapeutics
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• v.26 no.4
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• pp.389-398
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• 2018

p-Cresol, found at high concentrations in the serum of chronic kidney failure patients, is known to cause cell senescence and other complications in different parts of the body. p-Cresol is thought to mediate cytotoxic effects through the induction of autophagy response. However, toxic effects of p-cresol on mesenchymal stem cells have not been elucidated. Thus, we aimed to investigate whether p-cresol induces senescence of mesenchymal stem cells, and whether melatonin can ameliorate abnormal autophagy response caused by p-cresol. We found that p-cresol concentration-dependently reduced proliferation of mesenchymal stem cells. Pretreatment with melatonin prevented pro-senescence effects of p-cresol on mesenchymal stem cells. We found that by inducing phosphorylation of Akt and activating the Akt signaling pathway, melatonin enhanced catalase activity and thereby inhibited the accumulation of reactive oxygen species induced by p-cresol in mesenchymal stem cells, ultimately preventing abnormal activation of autophagy. Furthermore, preincubation with melatonin counteracted other pro-senescence changes caused by p-cresol, such as the increase in total 5'-AMP-activated protein kinase expression and decrease in the level of phosphorylated mechanistic target of rapamycin. Ultimately, we discovered that melatonin restored the expression of senescence marker protein 30, which is normally suppressed because of the induction of the autophagy pathway in chronic kidney failure patients by p-cresol. Our findings suggest that stem cell senescence in patients with chronic kidney failure could be potentially rescued by the administration of melatonin, which grants this hormone a novel therapeutic role.

• Molecules and Cells
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• v.40 no.8
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• pp.567-576
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• 2017

The $Na^+/H^+$ exchanger is responsible for maintaining the acidic tumor microenvironment through its promotion of the reabsorption of extracellular $Na^+$ and the extrusion of intracellular $H^+$. The resultant increase in the extracellular acidity contributes to the chemoresistance of malignant tumors. In this study, the chemosensitizing effects of cariporide, a potent $Na^+/H^+-exchange$ inhibitor, were evaluated in human malignant mesothelioma H-2452 cells preadapted with lactic acid. A higher basal level of phosphorylated (p)-AKT protein was found in the acid-tolerable H-2452AcT cells compared with their parental acid-sensitive H-2452 cells. When introduced in H-2452AcT cells with a concentration that shows only a slight toxicity in H-2452 cells, cariporide exhibited growth-suppressive and apoptosis-promoting activities, as demonstrated by an increase in the cells with pyknotic and fragmented nuclei, annexin V-PE(+) staining, a $sub-G_0/G_1$ peak, and a $G_2/M$ phase-transition delay in the cell cycle. Preceding these changes, a cariporide-induced p-AKT down-regulation, a p53 up-regulation, an ROS accumulation, and the depolarization of the mitochondrial-membrane potential were observed. A pretreatment with the phosphatidylinositol-3-kinase (PI3K) inhibitor LY294002 markedly augmented the DNA damage caused by the cariporide, as indicated by a much greater extent of comet tails and a tail moment with increased levels of the p-histone H2A.X, $p-ATM^{Ser1981}$, $p-ATR^{Ser428}$, $p-CHK1^{Ser345}$, and $p-CHK2^{Thr68}$, as well as a series of pro-apoptotic events. The data suggest that an inhibition of the PI3K/AKT signaling is necessary to enhance the cytotoxicity toward the acidtolerable H-2452AcT cells, and it underlines the significance of proton-pump targeting as a potential therapeutic strategy to overcome the acidic-microenvironment-associated chemotherapeutic resistance.