• Biomolecules & Therapeutics
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• v.17 no.4
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• pp.379-387
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• 2009

We have previously reported that N-ethylmaleimide (NEM) induces apoptosis through activation of $K^+$, $Cl^-$-cotransport (KCC) in HepG2 human hepatoblastoma cells. In this study we investigated the possible role of phospholipase $A_2$ ($PLA_2$)-arachidonic acid (AA) signals in the mechanism of the NEM-induced apoptosis. In these experiments we used arachidonyl trifluoromethylketone ($AACOCF_3$), bromoenol lactone (BEL) and p-bromophenacyl bromide (BPB) as inhibitors of the calcium-dependent cytosolic $PLA_2$ ($cPLA_2$), the calcium-independent $PLA_2$ ($iPLA_2$) and the secretory $PLA_2$ ($sPLA_2$), respectively. BEL significantly inhibited the NEM-induced apoptosis, whereas $AACOCF_3$ and BPB did not. NEM increased AA liberation in a dose-dependent manner, which was markedly prevented only by BEL. In addition AA by itself induced $K^+$ efflux, a hallmark of KCC activation, which was comparable to that of NEM. The NEM-induced apoptosis was not significantly altered by treatment with indomethacin (Indo) and nordihydroguaiaretic acid (NDGA), selective inhibitors of cyclooxygenase (COX) and lipoxygenase (LOX), respectively. Treatment with AA or 5,8,11,14-eicosatetraynoic acid (ETYA), a non-metabolizable analogue of AA, significantly induced apoptosis. Collectively, these results suggest that AA liberated through activation of $iPLA_2$ may mediate the NEMinduced apoptosis in HepG2 cells.

• Archives of Pharmacal Research
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• v.21 no.6
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• pp.664-670
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• 1998

The role of intracellular $Ca^{2+}$, in the regulation of tumor cell proliferation by products of arachidonic acid (AA) metabolism was investigated using U-373 MG human as trocytoma cells. Treatment with nordihydroguaiaretic acid (NDGA), a lipoxygenase (LOX) inhibitor, or caffeic acid (CA), a specific 5-LOX inhibitor, suppressed proliferation of the tumor cells in a dose-dependent manner. However, indomethacin (indo), a cyclooxygenase (COX) inhibitor, did not significantly alter proliferation of the tumor cells. At anti-proliferative concentrations, NDGA and CA significantly inhibited intracellular $Ca^{2+}$ release induced by carbachol, a known intracelluar $Ca^{2+}$ agonist in the tumor cells. Exogenous administration of leukotriene $B_4(LTB_4)$, an AA metabolite of LOX pathway, enhanced proliferation of the tumor cells in a concentration-dependent fashion. In addition, $LTB_4$, induced intracelluar $Ca^{2+}$ release. Intracellular $Ca^{2+}$-inhibitors, such as an intracellular $Ca^{2+}$ chelator (BAPTA) and intracellular $Ca^{2+}$-release inhibitors (dantrolene and TMB-8), significantly blocked the LTB4-induced enhancement of cell proliferation and intracellular $Ca^{2+}$ release. These results suggest that LOX activity may be critical for cell proliferation of the human astrocytoma cells and that intracelluar $Ca^{2+}$ may play a major role in the mechanism of action of LOX.

• Korean Journal of Pharmacognosy
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• v.32 no.4 s.127
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• pp.311-315
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• 2001

The root of Astragalus membranaceus Bunge (Leguminosae), which has been used for the treatment of hypertension, chronic hepatitis, duodenal ulcers, chronic nephritis and promotion of immunity in folk remedies. Cyclooxygenase (COX-2) is responsible for the production of large amounts of proinflammatory prostaglandins (PGs) at the inflammatory site. Thus, a logical approach to the treatment of inflammatory disease should involve the inhibitors of COX-2. To develop new COX-2 inhibitors from natural products, Astragali Radix was screened by inhibiting prostaglandin $E_2(PGE_2)$ generation in the culture medium using enzyme immunometric assay. Two isoflavone glycosides, $7,2'-dihydroxy-3',4'-dimethoxyisoflavan-7-O-{\beta}-D-glucoside$ and $calycosin-7-O-{\beta}-D-glucoside$ isolated from Astragali Radix inhibited COX-2 activity.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.20 no.1
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• pp.25-36
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• 1994

It is weal known that bacterial lipopolysaccharide (LPS) stimulates prostaglandin synthesis in various experimental system via enhancing the expression of cylooxygenase-2 (COX-2). This study was designed to characterize U)5-induced prostaglandin synthesis in mouse peritoneal macrophages LPS-stimulated prostaglandin synthesis in macrophages with short term exposure was not so much prominent, but there was a burst in prostaglandin synthesis 8 hours after the LPS treatment and this u·as accompanied with the increase of cyclooxygenase activity, Dexamethasone markedly inhibited prostaglandin synthesis in this system. Metabolic label ins data supported above observations and thus, it could be concluded that LPS induces the do novo synthesis of COX-2 by which it stimulates the prostaglandin synthesis in mouse peritoneal macrophages, These data suggested that this experimental model system could be used for the screening procedure of COX-2 selective inhibitors. Ketoprofen, a non steroidal anti inflammatory agent, appeared to inhibit COX-1 relatively more selectively than COX-2.

• Molecules and Cells
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• v.23 no.3
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• pp.398-404
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• 2007

Cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) are involved in various pathophysiological processes such as inflammation and carcinogenesis. In a search for inhibitors of COX-2 and iNOS production we found that extracts of Stewartia koreana strongly inhibited NO and $PGE_2$ production in LPS-treated macrophage RAW 264.7 cells. We have now shown that the mRNA and protein levels of iNOS and COX-2 are reduced by the Stewartia koreana extract (SKE). SKE inhibited expression of an NF-${\kappa}B$ reporter gene in response to LPS, and gel mobility shift assays revealed that SKE reduced NF-${\kappa}B$ DNA-binding activity. The extract also inhibited LPS-induced phosphorylation of $I{\kappa}B-{\alpha}$ and nuclear translocation of p65. Administration of the extract reduced the symptoms of arthritis in a collagen-induced arthritic mouse model. These results indicate that Stewartia extracts contain potentially useful agents for preventing and treating inflammatory diseases.

• Archives of Plastic Surgery
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• v.38 no.4
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• pp.351-358
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• 2011

Purpose: The inflammatory phase is considered an integral part of adult wound healing, but fetal wound healing studies have shown scarless healing results in the absence of the inflammation process. The COX-2 pathway is an essential component of inflammation. The purpose of this study is to identify the effect of a topical selective COX-2 inhibitor on inflammation in rabbit skin wound healing and scarring. Methods: Full-thickness wounds were made on 6 New Zealand rabbits' ears. Topical 5% celecoxib + vehicle (experimental tissue) and vehicle only (controlled tissue) were applied daily for 14d on each side of the ears. Scar samples were harvested at 2 wks, 4 wks, and 8 wks after the wounding. Each sample was stained with hematoxylin and eosin and the Masson's trichrome stain to evaluate inflammation and scar formation. Results: Histological analysis demonstrated a significant reduction of inflammation, neovascularization, and scar elevation in the experimental tissue as compared to the control. Additionally, experimental tissue exhibited faster improvement of collagen organization similar to that of normal tissue. Conclusion: This study suggests that the topical application of a selective COX-2 inhibitor on a rabbit ear wound resulted in decreased inflammation and had a positive effect on the reduction of scar formation.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2001.11a
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• pp.3-6
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• 2001

Inflammation is an outcome or an end effect of disruption of complex immunological balance. A variety of approaches to control immunological unbalance have been tried, and some of them are in practice in the clinic. Since inflammatory disorders are reflection of very complex immunological responses, it should be difficult to have such disorders under complete control. Thus, most of the drugs, being marketed and under development, possess some degrees of undesired side offsets originating from disruption of immunological balance. Steroids are excellent drugs suppressing inflammation in short term, however, long-term use of steroids would incur a serious side effect of "rebound". Another example is TNF-${\alpha}$-neutralizing agents, such as enbrel and infliximab. TNF-${\alpha}$ has been known to play a key role in the exacerbation of inflammation, and knock-out of TNF-${\alpha}$ is regarded essential to control of chronic inflammation. The TNF-${\alpha}$-neutralizing drugs in the market are regarded very efficient in the management of rheumatoid arthritis. Upon long term use, however, those drugs cause sepsis to a certain proportion of patients. It is ironical that a high plasma level of TNF-${\alpha}$ is known to be responsible for sepsis, and that the drugs scavenging TNF-${\alpha}$ cause sepsis. The above two examples illustrate well the difficulty of discovering an anti-inflammatory drug without unwanted immunological side effects. An anti-inflammatory drug would make a case in the market, as long as the drug has huge therapeutic benefits compared to its expected but unwanted immunological side effects, where cyclooxygenase-2 inhibitors are positioning. In this presentation, will be discussed general aspects of cyclooxygenase-2 inhibition in conjunction with 3(2Η)furanone derivatives, a novel class of COX-2 inhibitors.

• Tuberculosis and Respiratory Diseases
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• v.86 no.4
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• pp.304-318
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• 2023

Background: Cancer-associated fibroblasts (CAFs) are key components of the tumor microenvironment and significantly contribute to immune evasion. We investigated the effects of CAFs on the immune function of CD4+ and CD8+ T cells in non-small cell lung cancer (NSCLC). Methods: We isolated CAFs and normal fibroblasts (NFs) from tumors and normal lung tissues of NSCLC patients, respectively. CAFs were co-cultured with activated T cells to evaluate their immune regulatory function. We investigated the effect of CAF conditioned medium (CAF-CM) on the cytotoxicity of T cells. CAFs were also co-cultured with activated peripheral blood mononuclear cells and further incubated with cyclooxygenase-2 (COX2) inhibitors to investigate the potential role of COX2 in immune evasion. Results: CAFs and NFs were isolated from the lung tissues (n=8) and lymph nodes (n=3) of NSCLC patients. Immune suppressive markers, such as COX2 and programmed death-ligand 1 (PD-L1), were increased in CAFs after co-culture with activated T cells. Interestingly, CAFs promoted the expression of programmed death-1 in CD4+ and CD8+ T cells, and strongly inhibited T cell proliferation in allogenic and autologous pairs of CAFs and T cells. CAF-CM decreased the cytotoxicity of T cells. COX2 inhibitors partially restored the proliferation of CD4+ and CD8+ T cells, and downregulated the expression of COX2, prostaglandin E synthase, prostaglandin E2, and PD-L1 in CAFs. Conclusion: CAFs promote immune evasion by suppressing the function of CD4+ and CD8+ T cells via their effects on COX2 and PD-L1 in NSCLC. The immunosuppressive function of CAFs could be alleviated by COX2 inhibitors.

• Journal of Pharmaceutical Investigation
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• v.33 no.2
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• pp.105-112
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• 2003

Selective COX (cyclooxygenase)-2 inhibitors including celecoxib have been shown to induce apoptosis and cell cycle changes in various tumor cells. New inhibitors are recently being developed as chemomodulating agents. We evaluated celecoxib and screened 150 synthetic compounds for anti-proliferative activities in vitro. Effects of celecoxib on COX activity, cell growth, cell cycle distribution, and apoptosis induction were determined in A549 COX-2 overexpressing human non-small cell lung cancer (NSCLC) cells. The COX inhibition of celecoxib increased with concentration up to 82% at $1\;{\mu}M$ after 24 hr exposure. Forty ${\mu}M$ and $50\;{\mu}M$ of ce1ecoxib induced $G_1$ arrest, and TUNEL-positive apoptotic cells, respectively. Among 150 compounds, several compounds were selected for having greater COX-2 inhibitory activity and higher selectivity than celecoxib with growth inhibitory activity. Celecoxib showed concentration-dependent COX inhibitory activity, and ability to induce cell cycle arrest and apoptosis in human NSCLC cells in vitro. Among synthetic analogues screened, several compounds showed promising in vitro activity as COX-2 inhibitory anticancer agents, which warrant further evaluation in vitro and in vivo.

• The Korean Journal of Pharmacology
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• v.32 no.3
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• pp.425-431
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• 1996

Human neutrophil elastases (HNElastase, EC 3.4.21.37), a causative factor of inflammatory diseases, are regulated by plasma proteinase inhibitors, alpha-proteinase inhibitor and ${\alpha}_2-macroglobulin$. Under certain pathological conditions, however, released enzymes or abnormal function of inhibitors may cause various inflammatory disease. NSAIDs have been clinically applied for treatment of inflammatory diseases. Inhibition of cyclooxygenase is a known mechanism of action of NSAIDs in the treatment of inflammatory disease. In in vitro experiments, HNElastase was inhibited by naproxen, phenylbutazone, and oxyphenbutazone, but ibuprofen, ketoprofen, aspirin, salicylic acid, and tolmetin did not inhibit elastase. HNElastase was also inhibited by chelating agents, EDTA & EGTA, and tetracyclines. Removal of divalent metal ions by EDTA caused inhibition of elastase, and reconstitution of the metal ions recovered the enzyme activity to a certain level. Frequencies and contours in the Raman spectra of various conditions of human neutrophil elastase undergo drastic changes upon partial removal and/or reconstitution of calcium and zinc ions. The metal ion content dependent activities and change of the contour of the Raman spectrogram suggest us that the mechanism of action of a chelator or chelator-like agents on neutrophil elastase may be related to the conformational change at/or near the active site, especially -C=O radical or -COOH radical.