• 약학회지
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• 제56권2호
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• pp.80-85
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• 2012

Previously, we have reported that arachidonic acid (AA) appears to be involved in the induction of apoptosis in HepG2 human hepatoblastoma cells. In this study we investigated the possible role of the NADPH oxidase, a membranebound enzyme generating reactive oxygen species (ROS), in the mechanism of AA-induced apoptosis in HepG2 cells. Apoptotic cell death induced by AA was significantly suppressed by various inhibitors of the NADPH oxidase, diphenylene iodonium (DPI), apocynin (Apo) and neopterine (NP). In addition, these inhibitors of the NADPH oxidase completely blunted the AA-induced ROS elevation. Next, we investigated the implication of metabolic pathway of AA in these AA actions. Both apoptosis and ROS production induced by AA were not significantly altered by treatment with indomethacin (Indo) or nordihydroguaiaretic acid (NDGA), selective inhibitors of cyclooxygenase (COX) and lipoxygenase (LOX), respectively, suggesting that AA metabolites produced by COX or LOX may not have an essential role in the AA-induced apoptosis and ROS generation. Collectively, these results suggest that the NADPH oxidase may be a key player in the mechanism of AA-induced apoptosis in HepG2 cells. These results further suggest that NADPH oxidase may be a good target for the management of human hepatomas.

• 대한약리학회지
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• 제23권1호
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• pp.33-44
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• 1987

면역보체가 결합되어 있는 zymosan 또는 열로 응집된 IgG에 의하여 활성화된 호중구에서의 NADPH oxidase 의존적인 $O_{\overline{2}}$의 생성과 탐식작용은 칼슘의 흡수과정과 일치하였다. 활성화된 백혈구의 반응은 세포외 칼슘 농도에 따라 항진되었으며, 이는 칼슘의 킬레이트제인 EGTA나 EDTA에 의하여 유의하게 억제되었다. 활성화된 백혈구로부터 $O_{\overline{2}}$의 생성은 dantrolene과 chlorpromazine에 의하여 억제되었다. 칼슘 길항제인 bepredil, diltiazem, verapamil, nifedipine, nimodipine은 효과적으로 활성화된 백혈구의 칼슘흡수, $O_{\overline{2}}$ 생성 그리고 탐식 작용을 억제하였고 NADPH oxidase 활성도 또한 억제하였다. 그러므로, 칼슘 길항제는 칼슘 유입을 억제하거나 칼슘의 세포내 재분포 및 NADPH oxidase 반응계에 작용하여 활성화된 백혈구에서의 $O_{\overline{2}}$의 생성과 백혈구의 탐식작용을 억제할 것으로 시사되었다.

• Plant Biotechnology Reports
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• 제2권2호
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• pp.113-122
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• 2008

Nitric oxide (NO) affects the growth and development of plants and also affects plant responses to various stresses. Because NO induces root differentiation, we examined whether or not it is involved in increased ROS generation. Treatments with sodium nitroprusside (SNP), an NO donor, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), a specific NO scavenger, and $N{\omega}-nitro-{\text\tiny{L}}-arginine$ methyl ester hydrochloride (${\text\tiny{L}}-NAME$), an NO synthase (NOS) inhibitor, revealed that NO is involved in the adventitious root growth of mountain ginseng. Supply of an NO donor, SNP, activates NADPH oxidase activity, resulting in increased generation of $O_2{^{{\cdot}-}}$, which subsequently induces growth of adventitious roots. Moreover, treatment with diphenyliodonium chloride (DPI), an NADPH oxidase inhibitor, individually or with SNP, inhibited root growth, NADPH oxidase activity, and $O_2{^{{\cdot}-}}$ anion generation. Supply of the NO donor, SNP, did not induce any notable isoforms of enzymes; it did, however, increase the activity of pre-existing bands of NADPH oxidase, superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, and glutathione reductase. Enhanced activity of antioxidant enzymes induced by SNP supply seems to be responsible for a low level of $H_2O_2$ in the adventitious roots of mountain ginseng. It was therefore concluded that NO-induced generation of $O_2{^{{\cdot}-}}$ by NADPH oxidase seems to have a role in adventitious root growth of mountain ginseng. The possible mechanism of NO involvement in $O_2{^{{\cdot}-}}$ generation through NADPH oxidase and subsequent root growth is discussed.

• BMB Reports
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• 제30권3호
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• pp.182-187
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• 1997

The NADPH oxidase of phagocytes catalyzes the reduction of oxygen to $O_2^-$ at the expense of NADPH. The enzyme is dormant in resting neutrophils and becomes activated on stimulation. During activation, $p47^{phox}\;(\underline{ph}agocyte\;\underline{ox}idase\;factor)$, a cytosolic oxidase subunit, becomes extensively phosphorylated at a number of serines located between S303-S379. Oxidase activation can also be achieved by the addition of phosphorylated recombinant $p47^{phox}$ by protein kinase C in the cell-free system in the presence of $GTP{\gamma}S$. The cell-free activation is inhibited by wortmannin and LY294002. specific inhibitors of phosphatidylinositol 3kinase (PI 3-kinasel) These results indicate that PI 3-kinase may playa pivotal role in the activation of NADPH oxidase.

• 약학회지
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• 제55권6호
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• pp.485-491
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• 2011

Previously, we have reported that apigenin, a natural flavonoid found in a variety of vegetables and fruits, stimulated melanogenesis through the activation of $K^+-Cl^-$-cotransport (KCC) in B16 melanoma cells. In this study we investigated the possible involvement of reactive oxygen species (ROS) in the mechanism of apigenin-induced melanogenesis in B16 cells. Apigenin elevated intracellular ROS level in a dose-dependent manner. Treatment with various inhibitors of NADPH oxidase, diphenylene iodonium (DPI), apocynin (Apo) and neopterine (NP) significantly inhibited both the generation of ROS and melanogenesis induced by apigenin. In addition these inhibitors profoundly inhibited apigenin-induced $Cl^-$-dependent $K^+$ efflux, a hallmark of KCC activity. However, the apigenin-induced ROS generation was not significantly affected by treatment with a specific KCC inhibitor R-(+)-[(2-n-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)oxy]acetic acid (DIOA). These results indicate that the ROS production may be a upstream regulator of the apigenin-induced KCC stimulation, and in turn, melanogenesis in the B16 cells. Taken together, these results suggest that the NADPH oxidase-mediated ROS production may play an important role in the apigenin-induced melanogenesis in B16 cells. These results further suggest that NADPH oxidase may be a good target for the management of hyperpigmentation disorders.

• BMB Reports
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• 제31권3호
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• pp.227-232
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• 1998

The leukocyte NADPH oxidase of neutrophils is a membrane-bound enzyme that catalyzes the production of $O_2^-$ from oxygen using NADPH as an electron donor. Dormant in resting neutrophils, the enzyme acquires catalytic activity when the cells are exposed to appropriate stimuli. During activation, the cytosolic oxidase components $p47^{phox}$ and $p67^{phox}$ migrate to the plasma membrane, where they associate with cytochrome $b_{558}$, a membrane-bound flavohemoprotein, to assemble the active oxidase. The oxidase can be activated in a cell-free system; the activating agent usually employed is an anionic amphiphile such as sodium dodecyl sulfate (SDS). Because $p47^{phox}$ can translocate by itself during activation, the conformational change in $p47^{phox}$ may be responsible for the activation of NADPH oxidase. We show here that the treatment of $p47^{phox}$ with SDS leads to an increase in the reactivity of the sutbydryl group of cysteines toward N-ethylmaleimide, indicating that the conformational change occurs when $p47^{phox}$ is exposed to SDS. We propose that this change in conformation results in the appearance of a binding site through which $p47^{phox}$ interacts with cytochrome $b_{558}$during the activation process.

• Archives of Pharmacal Research
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• 제28권10호
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• pp.1183-1189
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• 2005

Although plant-derived phenolic acids have been reported to have anti-cancer activity, the exact mechanism is not completely understood. In this study, we investigated the role for reactive oxygen species (ROS) as a mediator of the apoptosis induced by caffeic acid (CA) and ferulic acid (FA), common phenolic acids in plants in HepG2 human hepatoma cells. CA and FA reduced cell viability, and induced apoptotic cell death in a dose-dependent manner. In addition, they evoked a dose-related elevation of intracellular ROS. Treatment with various inhibitors of NADPH oxidase (diphenylene iodonium, apocynin, neopterine) significantly blunted both the generation of ROS and the induction of apoptosis induced CA and FA. These results suggest that ROS generated through activation of NADPH oxidase may play an essential role in the apoptosis induced by CA and FA in HepG2 cells. These results further suggest that CA and FA may be valuable for the therapeutic management of human hepatomas.

• 생명과학회지
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• 제21권11호
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• pp.1625-1630
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• 2011

CoPP는 다양한 세포에서 HO-1의 유전자 발현과 활성을 증가시키는 강력한 유도제로 알려져 있다. HO-1는 세포 및 조직의 손상을 보호한다는 연구가 활발히 진행되고 있으나, 그 작용 기전에 대해서는 아직 잘 모르고 있다. 본 논문에서는 porphyrin 계열의 CoPP의 자극에 의해 유도되는 HO-1 유전자 발현에서 NADPH oxidase의 활성이 미치는 영향을 인간 간암세포주 HepG2에서 조사하였다. 배양 중인 HepG2 세포에서 CoPP는 HO-1의 발현을 농도의존적으로 증가시키는 것을 확인하였다. NADPH oxidase 저해제로 잘 알려져 있는 DPI를 전처리한 후 CoPP로 자극한 세포에서는 HO-1의 발현이 강력하게 억제되는 것으로 나타났다. DPI의 이런 억제 효과가 HO-1의 전사 조절인자 Nrf2의 활성에도 영향을 줄 수 있기 때문에 DPI를 전처리 한 후 CoPP 자극에 의한 Nrf2의 핵으로의 이동을 분석하였다. 그 결과, DPI는 CoPP에 의해 유도되는 Nrf2의 핵으로의 이동과 세포 내 존재하는 양을 감소시키는 것을 확인하였다. 다른 HO-1 발현 유도제로 알려져 있는 hemin에 의한 자극의 경우에도 DPI는 HepG2 세포의 HO-1의 발현을 억제하는 효과를 나타내었다. 그리고, $p47^{phox}$에 대한 siRNA를 사용하여 효과적으로 $p47^{phox}$ 유전자 발현을 knockdown 시켜서 NADPH oxidase의 활성을 억제시키는 방법을 사용하였다. 그 결과, $p47^{phox}$ silencing한 세포에 CoPP를 처리한 경우는 control siRNA를 처리한 세포와 비교할 때 HO-1 발현이 현저히 감소됨을 관찰할 수 있었다. 마지막으로, 세포 내 ROS 생성을 억제하는 GSHmee가 처리된 세포에서는 CoPP나 hemin이 Nrf2의 활성을 증가시키지 못하였고, 그 결과 HO-1의 발현을 유도하지 못하는 것을 알 수 있었는데, 이는 ROS가 CoPP나 hemin에 의한 HO-1 유전자 발현 과정에 중요한 역할을 한다는 것을 의미한다. 이를 종합해 볼 때, 인간 간암세포주 HepG2에서 CoPP나 hemin의 자극에 의한 HO-1 유전자의 발현에는 NADPH oxidase의 활성이 요구된다는 것을 알 수 있고, 그 활성은 세포 내 ROS를 생성시키는 것으로 역할을 한다고 여겨진다.

• The Korean Journal of Physiology and Pharmacology
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• 제13권2호
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• pp.99-106
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• 2009

Although anti-atherogenic effects of cilostazol have been suggested, its effects on the expression of SR in macrophages are unclear. This study investigated the role of cilostazol on CD36 expression of murine macrophages enhanced by HNE, a byproduct of lipid peroxidation. The stimulation of macrophages with HNE led to an increased expression of CD36, which was significantly attenuated by NAC, an antioxidant. Moreover, the increased production of ROS by HNE was completely abolished by NADPH oxidase inhibitors, DPI and apocynin, as well as by the 5-LO inhibitor, MK886, but not by inhibitors for other oxidases. This suggested that NADPH-oxidase and 5-LO were major sources of ROS induced by HNE. In addition, HNE-enhanced expression of CD36 was reduced by these inhibitors, which indicated a role for NADPH oxidase and 5-LO on CD36 expression. In our present study, cilostazol was a significant inhibitor of ROS production, as well as CD36 expression induced by HNE. An increase in NADPH oxidase activity by HNE was significantly attenuated by cilostazol, however cilostazol had no effect on HNE-enhanced 5-LO activity. Together, these results suggest that cilostazol attenuates HNE-enhanced CD36 expression on murine macrophages thorough inhibition of NADPH oxidase-derived ROS generation.

• 생명과학회지
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• 제17권6호통권86호
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• pp.778-782
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• 2007

Diphenyleneiodonium (DPI)는 NADPH oxidase 같은 flavoenzymes의 저해제로써 널리 사용되고 있다. 본 연구에서는 인간 대장암 세포주 HCT-116 (wild-type p53)와 HT-29 (p53 mutant) 및 인간 유방암 세포주인 MCF-7(wild-type p53)의 세포성장 과정에서의 DPI의 효과를 살펴보았다. DPI는 농도 및 시간 의존적으로 암세포주의성장을 막았으며 G2/M phase에서 cell cycle arrest를 일으켰다. Cell cycle arrest의 가장 높은 값은 DPI 처리후 12 시간에서 관찰할 수 있었다. 한편 DPI는 아폽토시스 그리고 cell cycle arres 에 관여하는 유전자 발현에 관여하는 p53의 표현을 크게 증가시켰으며, 이는 DPI처리 후 6시간 후 부터 관찰할 수 있었다. 그러나 NADPH oxidase의 조합을 억제하는 catechol 계인 apocynin은 p53의 발현을 유도하지 못하였다. 이것은 DPI에 의해 유도되는 p53의 발현증가는 NADPH oxidase활성의 저해와 관련되어 있지 않다는 것을 의미한다. 결론적으로 DPI는 HCT-116, HCT-15 및 MCF-7 암세포주에서 ROS에 비 의존적으로 wild-type p53 발현의 증가를 유도하며, 이 증가된 p53은 DPI에 의해 유도되는 성장 억제 및 C2/M phase에서의 cell cycle arrset과정의 조절기전에 관여한다는 것을 시사한다.