• Asian Pacific Journal of Cancer Prevention
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• v.13 no.5
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• pp.2379-2383
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• 2012

Objective: To investigate possible signal pathway involvement in multi-drug resistant P-glycoprotein (P-gp) expression induced by cyclooxygenase-2 (COX-2) in a human gastric adenocarcinoma cell line stimulated with pacliaxel (TAX). Methods: The effects of TAX on SGC7901 cell growth with different doses was assessed by MTT assay, along with the effects of the COX-2 selective inhibitor NS-398 and the nuclear factor-KB (NF-KB) pathway inhibitor pyrrolidine dithiocarbamate (PDTC). Influence on COX-2, NF-KB p65 and P-gp expression was determined by Western blotting. Results: TAX, NS-398 and PDTC all reduced SGC7901 growth, with dosedependence. With increasing dose of TAX, the expression of COX-2, p65 and P-gp showed rising trends, this being reversed by NS-398. PDTC also caused decrease in expression of p65 and P-gp over time. Conclusion: COX-2 may induce the expression of P-gp in SGC7901 cell line via the NF-kappa B pathway with pacliaxel stimulation.

• BMB Reports
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• v.48 no.2
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• pp.109-114
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• 2015

The COX-2/$PGE_2$ pathway has been implicated in the occurrence and progression of cancer. The underlying mechanisms facilitating the production of COX-2 and its mediator, $PGE_2$, in cancer survival remain unknown. Herein, we investigated $PGE_2$-induced COX-2 expression and signaling in HL-60 cells following menadione treatment. Treatment with $PGE_2$ activated anti-apoptotic proteins such as Bcl-2 and Bcl-xL while reducing pro-apoptotic proteins, thereby enhancing cell survival. $PGE_2$ not only induced COX-2 expression, but also prevented casapse-3, PARP, and lamin B cleavage. Silencing and inhibition of COX-2 with siRNA transfection or treatment with indomethacin led to a pronounced reduction of the extracellular levels of $PGE_2$, and restored the menadione- induced cell death. In addition, pretreatment of cells with the MEK inhibitor PD98059 and the PKA inhibitor H89 abrogated the $PGE_2$-induced expression of COX-2, suggesting involvement of the MAPK and PKA pathways. These results demonstrate that $PGE_2$ signaling acts in an autocrine manner, and specific inhibition of $PGE_2$ will provide a novel approach for the treatment of leukemia.

• International Journal of Oral Biology
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• v.31 no.1
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• pp.21-26
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• 2006

Periodontopathogens including Porphyromonas gingivalis interact with host periodontal cells and the excessive subsequent host responses contribute a major part to the development of periodontal diseases. Cyclooxygenase(COX)-2-synthesized $PGE_2$ has detrimental activities in terms of periodontal pathogenesis. The present study investigated induction of COX-2 expression by P. gingivalis in human monocytic THP-1 cells. Live P. gingivalis increased expression of COX-2, but not that of COX-1, which was demonstrated at both mRNA and protein levels. Elevated levels of $PGE_2$ were released from P. gingivalis-infected THP-1 cells. Pharma-cological inhibition of p38 mitogen-activated protein kinase(MAPK) and extracellular signal-regulated kinase(ERK) substantially attenuated P. gingivalis-induced COX-2 mRNA expression. Indeed, activation of p38 MAPK and ERK was observed in P. gingivalis-infected THP-1 cells. Also, P. gingivalis induced activation of nuclear $factor-{\kappa}B\;(NF-{\kappa}B)$ which is an important transcription factor for COX-2. These results suggest that COX-2 expression is up regulated in P. gingivalis-infected monocytic cells, at least in part, via p38 MAPK, ERK, and $NF-{\kappa}B$.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.8
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• pp.4539-4543
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• 2013

Background: Transitional cell carcinoma (TCC) is the most predominant type of urinary bladder tumor. As cyclooxygenase (COX)-2 is recently introduced as an attractive target molecule in bladder TCC, we evaluated the immunohistochemical expression of this marker and its association with several clinicopathological characteristics. Materials and Methods: This cross-sectional study was performed in the Pathology department of Sina Hospital in Tehran, Iran during 2006-2011. Ninety-two paraffin embedded blocks were selected from patients with urinary bladder TCC who underwent cystectomy or transurethral resection (TUR). Then, we assessed COX-2 expression by immunohistochemical staining using antibody against COX-2. Staining in more than 5% of tumor cells was considered as positive expression. Results: COX-2 was expressed in 50 % of our patients. This marker was markedly expressed in high grade bladder TCC (62.1%) versus other grades and there was statistically a significant difference in COX-2 expression between various grades (p=0.008). In addition, patients' age, lymphatic and perineurial invasion were associated with the expression of COX-2 (p=0.001, 0.015 and 0.039, respectively). However, other parameters such as stage, tumor size, venous invasion and lymph node metastasis did not show any significant relationship with this marker (all, p>0.05). Conclusions: COX-2 was expressed in urinary bladder TCC especially in high grade forms, advocating its probable role in the differentiation of this tumor. Accordingly, COX-2 could be a valuable biological target molecule in the evaluation and treatment of patients with bladder TCC.

• Journal of fish pathology
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• v.26 no.1
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• pp.19-30
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• 2013

Megalocytivirus is a major fish pathogen in marine aquaculture of Asian countries including Korea. Despite of many species affected by this pathogen, little is known interaction between megalocytivirus and the fish immune system. One of the cyclooxygenase isoforms, named COX-2, is playing an important role in immune regulation, and distinct from COX-1 isoform of constitutive activity. COX-2 enzyme is induced by various inflammatory signals, including injection of lipopolysaccharide or infection by pathogenic agents. We cloned COX-2 gene in rock bream using degenerated primers designed from reported sequences of other fish species in PCR followed with 5'- and 3'-end RACE-PCR. The full length of cDNA of rbCOX2 (rock bream COX-2) gene are 2655 bp and that translates into 609 amino acids. The rbCOX-2 genomic organization are found to span 10 exons separated by 9 introns. We also studied if the experimental infection of rock bream with megalocytivirus could affect the expression of COX-2 gene. When injected with LPS, expression of the COX-2 gene was reached peak level at 1 day post injection and showed 13.10 fold increased level compared with that of control. While, when injected with megalocytivirus, we were not able to find significantly increased COX-2 gene expression different from that of control. Cloned and analyzed COX-2 gene in rock bream will help to understand defence mechanisms in fish after viral infection and will also support the development of the measures for treatment and prevention of viral infection.

• Korean Journal of Clinical Laboratory Science
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• v.44 no.4
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• pp.229-238
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• 2012

Cyclooxygenase(COX-2) is an inducible enzyme that catalyzes the synthesis of prostaglandins (PGs) from arachidonic acid. Over-expression of COX-2 has been reported to be associated with progressive hepatic fibrosis in chronic hepatic C infection and rat liver fibrosis induced by carbon tetrachloride($CCl_4$). Recently, it is well known that mast cell products can stimulate the proliferation of hepatic stellate cells and key players in liver fibrosis. But little is known regarding their role in $CCl_4$-induced liver fibrosis in rat. Our aim was to investigate the relation between COX-2 expression and mast cells during liver fibrosis after $CCl_4$ treatment. Thirty Wistar rats were divided into five groups (non-treated 0, 2, 4, 6 and 8-week after $CCl_4$-treatment). Reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry were used to assess the expression of ${\alpha}$-smooth muscle actin (${\alpha}$-SMA), collagen-1 and COX-2 in liver tissue from $CCl_4$-treated rats. The density of collagen and mast cells were determined using a computerized image analysis system in liver sections stained with picrosirius red and toluidine blue, respectively. The expression levels of ${\alpha}$-SMA, collagen-1 and COX-2 mRNA were significantly higher at 2 wk in $CCl_4$-treated groups than non-treated group. The number of mast cells in liver tissues increased gradually from 2 wk to 6 wk depending on the fibrosis severity but decreased abruptly at 8 wk. The significant increase of collagen-1 and ${\alpha}$-SMA mRNA expression in $CCl_4$-treated rats was continued until 6 wk while the COX-2 mRNA was significantly decreased at 8 wk. These results suggest that increased mast cells are closely associated with COX-2 over-expression during hepatic fibrogenesis of $CCl_4$-treated rats.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.1
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• pp.30-40
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• 2008

The objectives of this study was to check up the effect of celecoxib, COX-2 inhibitor, on the pathogenesis of oral squamous cell carcinoma. After mefenamic acid, aspirin and celecoxib, COX-2 inhibitor, were inoculated to HN 22 cell line, the following results were obtained through tumor cell viability by wortmannin, growth curve of tumor cell line, apoptotic index, PGE2 synthesis, total RNA extraction, RT-PCR analysis and TEM features. 1. When wortmannin and celecoxib were given together, the survival rate of tumor cells was lowest about 47 %. So wortmannin had an effect on the decrease of survival rate of tumor cells. 2. In growth curve, the slowest growth was observed in celecoxib inoculated group. 3. The synthesis of PGE2 was decreased in all group and the obvious suppression and highest apoptotic index was observed in celecoxib inoculated group. 4. Suppression of expression of COX-2 mRNA was evident in celecoxib inoculated group. But that of COX-1,2 mRNA was observed in mefenamic acid inoculated group and aspirin inoculated group. 5. In celecoxib inoculated group, mRNA expression of AKT1 was decreased and that of PTEN & expression of caspase 3 and 9 was evidently increased. Depending on above results, when celecoxib was inoculated to oral squamous cell carcinoma cell line, an increase of mRNA expression of caspase 3,9 and PTEN is related to a decrease of mRNA expression of AKT1. Wortmannin had an effect on the decrease of survival rate of tumor cells. Celecoxib might induce apoptosis of tumor cell by suppression of AKT1 pathway and COX-2 inhibition. This results suggested that COX-2 inhibitor might be significantly effective in chemoprevention of oral squamous cell carcinoma.

• Tuberculosis and Respiratory Diseases
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• v.66 no.4
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• pp.274-279
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• 2009

Background: Uteroglobin (UG) is a secretary protein that has strong immunomodulatory properties, and which is synthesized in most epithelia including lung tissue. Overexpression of UG is associated with decreased expression of cyclooxygenase (COX)-2 and suppression of cancer cell growth. Indoleamine 2,3-dioxygenase (IDO) catalyzes tryptophan along the kynurenine pathway, and both the reduction in local tryptophan and the production of tryptophan metabolites contribute to the immunosuppressive effects of IDO. Methods: In this study, we investigated the pattern of expression of COX-2 and IDO, and the effect of UG transduction in the expression of COX-2 and IDO in several non-small cell lung cancer cell lines, especially A549. Results: Both COX-2 and IDO were constitutionally expressed in A549 and H460 cells, and was reduced by UG transduction. In A549 cells, the slightly increased expression of COX-2 and IDO with the instillation of interferon-gamma (IFN-$\gamma$) was reduced by UG transduction. However, the reduced expression of COX-2 and IDO by UG transduction was not increased with IFN-$\gamma$ instillation in A549 cells. In both the A549 COX-2 sense and the A549 COX-2 anti-sense small interfering RNA (siRNA)-transfected cells, IDO was expressed; expression was reduced by UG transduction, irrespective of the expression of COX-2. Conclusion: The results suggest that the anti-proliferative function of UG may be associated with the immune tolerance pathway of IDO, which is independent of the COX-2 pathway.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2003.11a
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• pp.96-96
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• 2003

Previously, wogonin (5,7-dihydroxy-8-methoxyflavone) was found to suppress proinflammatory enzyme expression including cyclooxygenase-2 (COX-2), contributing to in vivo anti-inflammatory activity against skin inflammation. However, the detailed effect on each skin cell type has not been understood. Therefore, present investigation was carried out to find the effect of wogonin on inflammation-associated gene expression from skin fibroblasts in culture using reverse transcriptase-polymerase chain reaction. As a result, it was found that wogonin (10 - 100 ${\mu}$M) clearly down-regulated COX -2 expression from NIH/3T3 cells treated with 12-O-tetradecanoylphorbol 13-acetate, interleukin-1${\beta}$ or tumor necrosis factor-a. But, the expression levels of COX-1, interleukin-1${\beta}$ and fibronectin were not significantly affected. This finding was well correlated with significant reduction of prostaglandin E$_2$(PGE$_2$) production by wogonin. As a comparison, NS-398 (selective cyclooxygenase-2 inhibitor) did not suppress COX -2 expression and other gene levels, while PGE$_2$production was potently reduced at 0.1 - 10 ${\mu}$M. All these results suggest that COX -2 down-regulation of skin fibroblasts may be, at least in part, one of anti-inflammatory mechanisms of wogonin against skin inflammation.

• The Korean Journal of Physiology and Pharmacology
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• v.9 no.4
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• pp.215-221
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• 2005

We investigated the effects of testosterone and dihydrotestosterone on inflammatory response of iNOS and COX-2 expression in rat vascular smooth muscle cells. Rat vascular smooth muscle cells (VSMC) stimulated with bacterial lipopolysaccharide $(LPS;\;10{\mu}g/ml)$ for 24 hours were incubated with increasing amounts of testosterone and dihydrotestosterone (1 and 100 nM). LPS was found to induce inflammatory response of iNOS and COX-2 mRNA and protein in VSMC. These processes were affected by male sex steroid hormones. For 3 hours, however, pretreatment of the cells with 100 nM each of testosterone and dihydrotestosterone suppressed LPS induced iNOS and COX-2 protein expression. RT-PCR analysis revealed that testosterone and dihydrotestosterone did not inhibit mRNA expression of iNOS and COX-2 stimulated by 24 hours of LPS incubation. Proliferation rate was slower in VSMC treated with testosterone and dihydrotestosterone. Testosterone enhanced androgen receptor expression, and LPS significantly reduced androgen receptor protein expression in VSMC. These results indicate that the expression of both iNOS and COX-2 proteins was suppressed by testosterone and dihydrotestosterone in LPS stimulated VSMC and leading to reduction of vascular inflammation.