Cyclooxygenase-2 (COX-2) Protein Expression byWestern Blotting

Phospholipases A2(PLA2) are key enzymes for production of lipid mediators. We previously demonstrated that a snake venom sPLA2named MT-III leads to prostaglandin (PG)E2biosynthesis in macrophages by inducing the expression of cyclooxygenase-2 (COX-2). Herein, we explored the molecular mechanisms and signaling pathways leading to these MT-III-induced effects. Results demonstrated that MT-III induced activation of the transcription factor NF-κB in isolated macrophages. By using NF-κB selective inhibitors, the involvement of this factor in MT-III-induced COX-2 expression and PGE2production was demonstrated. Moreover, MT-III-induced COX-2 protein expression and PGE2release were attenuated by pretreatment of macrophages with SB202190, and Ly294002, and H-7-dihydro compounds, indicating the involvement of p38MAPK, PI3K, and PKC pathways, respectively. Consistent with this, MT-III triggered early phosphorylation of p38MAPK, PI3K, and PKC. Furthermore, SB202190, H-7-dihydro, but not Ly294002 treatment, abrogated activation of NF-κB induced by MT-III. Altogether, these results show for the first time that the induction of COX-2 protein expression and PGE2release, which occur via NF-κB activation induced by the sPLA2-MT-III in macrophages, are modulated by p38MAPK and PKC, but not by PI3K signaling proteins.

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Ghrelin Regulates Cyclooxygenase-2 Expression and Promotes Gastric Cancer Cell Progression

Computational and Mathematical Methods in Medicine ◽

10.1155/2021/5576808 ◽

2021 ◽

Vol 2021 ◽

pp. 1-9

Author(s):

Huanqing Li ◽

Xiaohong Zhang ◽

Li Feng

Keyword(s):

Gastric Cancer ◽

Protein Expression ◽

Gastric Cancer Cell ◽

Molecular Targets ◽

Cyclooxygenase 2 ◽

Akt Inhibitor ◽

Flow Cytometry Assay ◽

Ags Cells ◽

Cell Progression ◽

Cox 2

Aim. To research the molecular mechanism of ghrelin in apoptosis, migratory, and invasion of gastric cancer (GC) cells. Methods. After GC AGS cells were handled with ghrelin (10–8 M), cyclooxygenase-2 inhibitor NS398 (100 μM), and Akt inhibitor perifosine (10uM), the rates of apoptosis were detected by TUNEL assay and flow cytometry assay. We assessed the expressions of PI3K, p-Akt, and COX-2 proteins by making use of Western blot analysis. The cell migratory and invasion were detected by using wound-healing and transwell analysis. Results. The migratory and invasion were increased in ghrelin-treated cells, while the rates of apoptosis were decreased. GC AGS cells treated with ghrelin showed an increase in protein expression of p-Akt, PI3K, and COX-2. After cells were treated with Akt inhibitor perifosine, the protein expression of p-Akt, PI3K, and COX-2 and the cell migratory, invasion, and apoptosis were partly recovered. After cells were treated with cyclooxygenase-2 inhibitor NS398, the protein expression of COX-2 and the cell migratory and invasion were decreased, while the rates of apoptosis were increased. Conclusion. Ghrelin regulates cell migration, invasion, and apoptosis in GC cells through targeting PI3K/Akt/COX-2. Ghrelin increases the expression of COX-2 in GC cells by targeting PI3K/Akt. Ghrelin is suggested to be one of the molecular targets in GC.

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Prostaglandin E2 EP3 receptor regulates cyclooxygenase-2 expression in the kidney

AJP Renal Physiology ◽

10.1152/ajprenal.00634.2011 ◽

2012 ◽

Vol 303 (3) ◽

pp. F449-F457 ◽

Cited By ~ 12

Author(s):

Carlos P. Vio ◽

Mariana Quiroz-Munoz ◽

Catherina A. Cuevas ◽

Carlos Cespedes ◽

Nicholas R. Ferreri

Keyword(s):

Protein Expression ◽

Negative Feedback ◽

Fold Increase ◽

Treated Group ◽

Cyclooxygenase 2 ◽

Thick Ascending Limb ◽

Sprague Dawley ◽

Mrna Accumulation ◽

Cox 2 ◽

Ep3 Receptor

Cyclooxygenase-2 (COX-2) is constitutively expressed and highly regulated in the thick ascending limb (TAL). As COX-2 inhibitors (Coxibs) increase COX-2 expression, we tested the hypothesis that a negative feedback mechanism involving PGE2 EP3 receptors regulates COX-2 expression in the TAL. Sprague-Dawley rats were treated with a Coxib [celecoxib (20 mg·kg−1·day−1) or rofecoxib (10 mg·kg−1·day−1)], with or without sulprostone (20 μg·kg−1·day−1). Sulprostone was given using two protocols, namely, previous to Coxib treatment (prevention effect; Sulp7-Coxib5 group) and 5 days after initiation of Coxib treatment (regression effect; Coxib10-Sulp5 group). Immunohistochemical and morphometric analysis revealed that the stained area for COX-2-positive TAL cells (μm2/field) increased in Coxib-treated rats (Sham: 412 ± 56.3, Coxib: 794 ± 153.3). The Coxib effect was inhibited when sulprostone was used in either the prevention (285 ± 56.9) or regression (345 ± 51.1) protocols. Western blot analysis revealed a 2.1 ± 0.3-fold increase in COX-2 protein expression in the Coxib-treated group, an effect abolished by sulprostone using either the prevention (1.2 ± 0.3-fold) or regression (0.6 ± 0.4-fold vs. control, P < 0.05) protocols. Similarly, the 6.4 ± 0.6-fold increase in COX-2 mRNA abundance induced by Coxibs ( P < 0.05) was inhibited by sulprostone; prevention: 0.9 ± 0.3-fold ( P < 0.05) and regression: 0.6 ± 0.1 ( P < 0.05). Administration of a selective EP3 receptor antagonist, L-798106, also increased the area for COX-2-stained cells, COX-2 mRNA accumulation, and protein expression in the TAL. Collectively, the data suggest that COX-2 levels are regulated by a novel negative feedback loop mediated by PGE2 acting on its EP3 receptor in the TAL.

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p38 and EGF receptor kinase-mediated activation of the phosphatidylinositol 3-kinase/Akt pathway is required for Zn2+-induced cyclooxygenase-2 expression

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00197.2005 ◽

2005 ◽

Vol 289 (5) ◽

pp. L883-L889 ◽

Cited By ~ 37

Author(s):

Weidong Wu ◽

Robert A. Silbajoris ◽

Young E. Whang ◽

Lee M. Graves ◽

Philip A. Bromberg ◽

...

Keyword(s):

Protein Expression ◽

Signaling Pathways ◽

Intracellular Signaling ◽

Egf Receptor ◽

Cyclooxygenase 2 ◽

Dominant Negative ◽

Phosphatidylinositol 3 Kinase ◽

Akt Phosphorylation ◽

Intracellular Signaling Pathways ◽

Cox 2

Cyclooxygenase 2 (COX-2) expression is induced by physiological and inflammatory stimuli. Regulation of COX-2 expression is stimulus and cell type specific. Exposure to Zn2+ has been associated with activation of multiple intracellular signaling pathways as well as the induction of COX-2 expression. This study aims to elucidate the role of intracellular signaling pathways in Zn2+-induced COX-2 expression in human bronchial epithelial cells. Inhibitors of the phosphatidylinositol 3-kinase (PI3K) potently block Zn2+-induced COX-2 mRNA and protein expression. Overexpression of adenoviral constructs encoding dominant-negative Akt kinase downstream of PI3K or wild-type phosphatase and tensin homolog deleted on chromosome 10, an important PI3K phosphatase, suppresses COX-2 mRNA expression induced by Zn2+. Zn2+ exposure induces phosphorylation of the tyrosine kinases, including Src and EGF receptor (EGFR), and the p38 mitogen-activated protein kinase. Blockage of these kinases results in inhibition of Zn2+-induced Akt phosphorylation as well as COX-2 protein expression. Overexpression of dominant negative p38 constructs suppresses Zn2+-induced increase in COX-2 promoter activity. In contrast, the c-Jun NH2-terminal kinase and the extracellular signal-regulated kinases have minimal effect on Akt phosphorylation and COX-2 expression. Inhibition of p38, Src, and EGFR kinases with pharmacological inhibitors markedly reduces Akt phosphorylation induced by Zn2+. However, the PI3K inhibitors do not show inhibitory effects on p38, Src, and EGFR. These data suggest that p38 and EGFR kinase-mediated Akt activation is required for Zn2+-induced COX-2 expression and that the PI3K/Akt signaling pathway plays a central role in this event.

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Mycoplasma fermentans MALP-2 Induces Heme Oxygenase-1 Expression via Mitogen-Activated Protein Kinases and Nrf2 Pathways To Modulate Cyclooxygenase 2 Expression in Human Monocytes

Clinical and Vaccine Immunology ◽

10.1128/cvi.00716-12 ◽

2013 ◽

Vol 20 (6) ◽

pp. 827-834 ◽

Cited By ~ 11

Author(s):

Xiaohua Ma ◽

Xiaoxing You ◽

Yanhua Zeng ◽

Jun He ◽

Liangzhuan Liu ◽

...

Keyword(s):

Protein Expression ◽

Protein Kinases ◽

Heme Oxygenase ◽

Inflammatory Responses ◽

Cyclooxygenase 2 ◽

Heme Oxygenase 1 ◽

Related Factor ◽

Mitogen Activated Protein Kinases ◽

Mitogen Activated Protein ◽

Cox 2

ABSTRACTHeme oxygenase-1 (HO-1) is a stress-inducible rate-limiting enzyme in heme degradation that confers cytoprotection against oxidative injury and performs a vital function in the maintenance of cell hemostasis. Increasing numbers of reports have indicated that mycoplasma-derived membrane lipoproteins/lipopeptides, such as macrophage-activating lipopeptide-2 (MALP-2), function as agents that stimulate the immune system by producing various inflammatory mediators, such as cytokines and cyclooxygenase 2 (COX-2), which play roles in the pathogenesis of inflammatory responses during mycoplasma infection. Here, we report that MALP-2 induced HO-1 mRNA and protein expression and upregulated HO-1 enzyme activity in THP-1 cells. Specific inhibitors of mitogen-activated protein kinases (MAPKs), SB203580, PD98059, and SP600125, significantly abolished HO-1 expression. In addition, MALP-2 also induced NF-E2-related factor 2 (Nrf2) translocation, and the silencing of Nrf2 expression in THP-1 cells decreased the levels of MALP-2-mediated HO-1 expression. Furthermore, COX-2 protein expression levels were upregulated in THP-1 cells in response to MALP-2, and transfection with small interfering RNAs of HO-1 significantly increased COX-2 accumulation. These results demonstrate that MALP-2 induces HO-1 expression via MAPKs and Nrf2 pathways and, furthermore, that MALP-2-induced COX-2 expression was modulated by HO-1 in THP-1 cells.

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Soy Saponins Meditate the Progression of Colon Cancer in Rats by Inhibiting the Activity of β-Glucuronidase and the Number of Aberrant Crypt Foci but Not Cyclooxygenase-2 Activity

ISRN Oncology ◽

10.1155/2013/645817 ◽

2013 ◽

Vol 2013 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Yu-Wei Guo ◽

Yue-Hwa Chen ◽

Wan-Chun Chiu ◽

Hsiang Liao ◽

Shyh-Hsiang Lin

Keyword(s):

Colon Cancer ◽

Protein Expression ◽

Research Methods ◽

Colonic Mucosa ◽

Cyclooxygenase 2 ◽

Aberrant Crypt Foci ◽

Preneoplastic Lesions ◽

Pge2 Level ◽

Cox 2 ◽

Different Doses

Objective. The effect of extracted crude soybean saponins on preneoplastic lesions, aberrant crypt foci (ACF), and the related mechanism were investigated. Research Methods and Procedures. Rats were assigned into five groups according to different doses of extracted crude soybean saponins and received 1,2-dimethylhydrazine (DMH) injection in week 5. In week 15, all rats were sacrificed. The number of ACFs, the cyclooxygenase-2 (COX-2) protein expression, the level of prostaglandins E2 (PGE2), and the activity of β-glucuronidase were examined. Results. Results revealed that the consumption of extracted crude soybean saponins decreased the number of ACFs and the activity of β-glucuronidase in rats, while the expression of COX-2 protein and PGE2 level were not affected. Conclusions. Soybean saponins were effective in inhibiting colon cancer by downregulating the activity of β-glucuronidase in colonic mucosa but not the COX-2 protein expression and PGE2 level.

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Induction of Cyclooxygenase-2 in Thick Ascending Limb Cells by Adrenalectomy

Journal of the American Society of Nephrology ◽

10.1681/asn.v124649 ◽

2001 ◽

Vol 12 (4) ◽

pp. 649-658

Author(s):

CARLOS P. VIO ◽

SHAO-JIAN AN ◽

CARLOS CÉSPEDES ◽

JOHN C. MCGIFF ◽

NICHOLAS R. FERRERI

Keyword(s):

Protein Expression ◽

Renal Tissue ◽

Cyclooxygenase 2 ◽

Prostaglandin E ◽

Thick Ascending Limb ◽

Selective Marker ◽

Mrna Accumulation ◽

Cox 2 ◽

Morphologic Analysis ◽

Intact Rats

Abstract. Adrenalectomized (ADX) and sham-operated rats received either dexamethasone (DEX) or vehicle. Renal tissue was used for morphologic analysis, assessment of cyclooxygenase-2 (COX-2) protein expression and mRNA accumulation, and quantitation of COX-2 activity. In untreated or shamoperated rats, COX-2 protein was observed in a subset of tubular epithelial cells (<2%), which were located mainly in the cortex. All COX-2-positive cells also expressed Tamm-Horsfall glycoprotein, a highly selective marker for thick ascending limb (TAL) cells. After ADX, >30% of TAL cells expressed COX-2 in a manner consistent with recruitment of COX-2-positive TAL cells toward the medulla. Treatment of ADX rats with DEX reduced the number of COX-2-positive cells to that observed in sham-operated or intact rats. COX-2 mRNA accumulation was increased by ADX and partially attenuated by treatment with DEX. Western blot analysis of cortical microsomes revealed a substantial increase in COX-2 expression in ADX rats, compared with ADX/DEX-treated, sham-operated, or intact rats. The increase in COX-2 protein expression was associated with a twofold increase in prostaglandin E2 formation by cortical microsomes obtained from ADX rats, compared with sham-operated rats. It is concluded that ADX induces expression of enzymatically active COX-2, such that expression occurs in the cortical TAL and proceeds in a defined pattern toward the outer medullary TAL. It is suggested that ADX induces expression of TAL cells that, in the basal state, do not express COX-2 protein.

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