Downregulation Of Cyclooxygenase-2 Expression Research Articles

MBP-1 Suppresses Growth and Metastasis of Gastric Cancer Cells through COX-2

The c-Myc promoter binding protein 1 (MBP-1) is a transcriptional suppressor of c-myc expression and involved in control of tumorigenesis. Gastric cancer is one of the most frequent neoplasms and lethal malignancies worldwide. So far, the regulatory mechanism of its aggressiveness has not been clearly characterized. Here we studied roles of MBP-1 in gastric cancer progression. We found that cell proliferation was inhibited by MBP-1 overexpression in human stomach adenocarcinoma SC-M1 cells. Colony formation, migration, and invasion abilities of SC-M1 cells were suppressed by MBP-1 overexpression but promoted by MBP-1 knockdown. Furthermore, the xenografted tumor growth of SC-M1 cells was suppressed by MBP-1 overexpression. Metastasis in lungs of mice was inhibited by MBP-1 after tail vein injection with SC-M1 cells. MBP-1 also suppressed epithelial-mesenchymal transition in SC-M1 cells. Additionally, MBP-1 bound on cyclooxygenase 2 (COX-2) promoter and downregulated COX-2 expression. The MBP-1-suppressed tumor progression in SC-M1 cells were through inhibition of COX-2 expression. MBP-1 also exerted a suppressive effect on tumor progression of other gastric cancer cells such as AGS and NUGC-3 cells. Taken together, these results suggest that MBP-1-suppressed COX-2 expression plays an important role in the inhibition of growth and progression of gastric cancer.

Dihydro- N-caffeoyltyramine down-regulates cyclooxygenase-2 expression by inhibiting the activities of C/EBP and AP-1 transcription factors

Dihydro- N-caffeoyltyramine (DHCT), a novel phenolic amide isolated from the root bark of Lycium chinense Miller, has potent antioxidative activity and anti-fungal effects. In the present study, we investigated the effects of DHCT on phorbol 12-myristate 13-acetate (PMA)-induced pro-inflammatory protein cyclooxygenase (COX-2) expression in macrophages. Treatment with DHCT suppressed PMA-mediated induction of COX-2 mRNA and protein. PMA-inducible production of PGE 2 was inhibited by DHCT in a dose-dependent manner. Transient transfections and electrophoretic mobility shift assays indicated that the inhibitory effects of DHCT were mediated via CCAAT/enhancer-binding protein (C/EBP) and activator protein 1 (AP-1). DHCT reduced PMA-induced C/EBPβ protein expression and c-jun/c-fos gene and protein expression. Furthermore, DHCT significantly inhibited PMA-induced activation of the mitogen activated protein (MAP) kinases (ERK and JNK). Thus, DHCT is an effective agent to attenuate COX-2 production mediated by the transcription factors C/EBP and AP-1, and these results enhance our understanding of the anti-inflammatory and anti-cancer properties by DHCT.

Down-Regulation of Cyclooxygenase-2 is Involved in Ischemic Postconditioning Protection Against Renal Ischemia Reperfusion Injury in Rats

Ischemic postconditioning (IPostC) is a phenomenon whereby rapid intermittent interruptions of blood flow in the early phase of reperfusion protect an organ from ischemia-reperfusion injury. In the present study, we investigated whether the protective effect of IPostC was associated with the cyclooxygenase-2 (COX-2) pathway by evaluating its expression following renal ischemia-reperfusion in rats. Animals underwent 45 minutes of renal pedicle occlusion followed by reperfusion for 1.5, 3, 6, 12, or 24 hours. IPostC was performed by six 10-second cycles of reperfusion and 10 seconds of renal pedicle occlusion at the end of ischemia. Blood and kidney samples were collected at each reperfusion time point. The protein expression of COX-1 and COX-2 were evaluated by Western blotting. Our data showed that IPostC attenuated the renal dysfunction and decreased COX-2 expression induced by ischemia-reperfusion insults. The results indicated that the protective effect of IPostC was related to down-regulation of COX-2 expression.

Extremely low frequency electromagnetic fields modulate expression of inducible nitric oxide synthase, endothelial nitric oxide synthase and cyclooxygenase-2 in the human keratinocyte cell line HaCat: potential therapeutic effects in wound healing

Extremely low frequency (ELF) electromagnetic fields (EMF) are known to produce a variety of biological effects. Clinical studies are ongoing using EMF in healing of bone fractures and skin wounds. However, little is known about the mechanisms of action of ELF-EMF. Several studies have demonstrated that expression and regulation of nitric oxide synthase (NOS) and cyclooxygenase-2 (COX-2) are vital for wound healing; however, no reports have demonstrated a direct action of ELF-EMF in the modulation of these inflammatory molecules in human keratinocytes. The present study analysed the effect of ELF-EMF on the human keratinocyte cell line HaCaT in order to assess the mechanisms of action of ELF-EMF and to provide further support for their therapeutic use in wound healing. Exposed HaCaT cells were compared with unexposed control cells. At different exposure times, expression of inducible NOS (iNOS), endothelial NOS (eNOS) and COX-2 was evaluated by Western blot analysis. Modulation of iNOS and eNOS was monitored by evaluation of NOS activities, production of nitric oxide (NO) and O(2)(-) and expression of activator protein 1 (AP-1). In addition, catalase activity and prostaglandin (PG) E(2) production were determined. Effects of ELF-EMF on cell growth and viability were monitored. The exposure of HaCaT cells to ELF-EMF increased iNOS and eNOS expression levels. These ELF-EMF-dependent increased expression levels were paralled by increased NOS activities, and increased NO production. In addition, higher levels of AP-1 expression as well as a higher cell proliferation rate were associated with ELF-EMF exposure. In contrast, ELF-EMF decreased COX-2 expression, PGE(2) production, catalase activity and O(2)(-) production. Mediators of inflammation, such as reactive nitrogen and PGE(2), and keratinocyte proliferation are critical for the tissue regenerative processes. The ability of ELF-EMF to upmodulate NOS activities, thus nitrogen intermediates, as well as cell proliferation, and to downregulate COX-2 expression and the downstream intermediate PGE(2), highlights the potential therapeutic role of ELF-EMF in wound healing processes.

Involvement of the ERK1/2 Pathway During Oxytocin-Induced PGF2alpha Production in the Bovine Endometrial Epithelial Cell Line bEEL.

In ruminants, oxytocin (OT) initiates the pulsatile release of progstaglandin F2α (PGF2α) from the endometrial epithelial cells through the G protein coupled oxytocin receptor (OTR) that is up-regulated during the luteolytic phase. It has been proposed that the embryonic signal interferon tau exerts its antiluteolytic effect by disrupting the OT signaling axis. In this respect, we have studied the signaling pathway of OT-induced PGF2α production in bovine endometrial epithelial cell line (bEEL) using kinase inhibitors. Uncoupling OTR with suramin (100μM) inhibited OT (500nM)-induced PGF2α release confirming mediation through G protein subunits. OT induces intracellular Ca2+ mobilization suggesting Gαq/11 mediated signaling as was shown for myometrial OTRs. Surprisingly, however, neither the Ca2+ chelator BAPTA nor a PKC inhibitor had any effect on OT-induced PGF2α release. In contrast, the MEK inhibitor PD 98059 (10μM) and Raf1 inhibitor GW5074 (1μM) practically abolished OT-induced PGF2α production in bEEL cells, thus pointing at the involvement of the of ERK pathway. Inhibition of the small GTPase Ras by munanmyin (1μM) inhibited PGF2α by 50%; whereas LY 294002 (25μM) and AG1879 (10μM) inhibited OT-induced PGF2α production by 80-90% indicating the involvement of PI3K and Src, respectively. In addition, pertussis toxin (PTX 200 ngml-1) inhibited PGF2α production by 50% suggesting a role for Gαi/o; however, increasing intracellular cAMP by 8 bromo cAMP, forskolin or IBMX did not inhibit OT-induced PGF2α production suggesting involvement of Gαo rather than Gαi as the PTX sensitive subtype. Surprisingly, the inhibition of OT-induced PGF2α production was not accompanied by down regulation of COX2 expression. Therefore, phosphorylation of cPLA2, inhibition of COX2 activity, or uncoupling of PGF synthase from COX2 might be considered as alternate mechanisms behind the reduced PGF2α production. Our results suggest that OT-induced PGF2α production in bEEL cells is mediated principally through Gβ γ subunit initiating phosphorylation of downstream molecules such as PI3K, Src, Ras, Raf1, MEK and ERK kinases and co-regulated by PTX sensitive Gα. (poster)

Sulforaphane down-regulates COX-2 expression by activating p38 and inhibiting NF-κB-DNA-binding activity in human bladder T24 cells

Cyclooxygenase-2 (COX-2) overexpression has been associated with the grade, prognosis and recurrence of transitional cell carcinoma (TCC) of the bladder. In this study, sulforaphane, a dietary isothiocyanate, down-regulated COX-2 expression in human bladder transitional cancer T24 cells at both transcriptional- and translational levels. Sulforaphane (5-20 microM) induced nuclear translocation of NF-kappaB and reduced its binding to the COX-2 promoter, a key mechanism for suppressing COX-2 expression by sulforaphane. Moreover, sulforaphane increased expression of p38 and phosphorylated-p38 protein. A specific inhibitor of p38 MAPK, SB202190, was used to further investigate its pivotal role in sulforaphane-mediated down-regulation of COX-2. Exposure of T24 cells to SB202190 1 hour prior to sulforaphane treatment abolished the effect of sulforaphane on COX-2 mRNA down-regulation, but enhanced COX-2 transcription. Furthermore, SB202190 alone induced NF-kappaB translocation to the nucleus, promoted NF-kappaB binding to the COX-2 promoter and resulted in up-regulation of COX-2 expression. Taken together, these data suggest that p38 is essential in sulforaphane-mediated COX-2 suppression and provide new insights into the molecular mechanisms of sulforaphane in the chemoprevention of bladder cancer.

Docosahexaenoic acid suppresses arachidonic acid-induced proliferation of LS-174T human colon carcinoma cells

To investigate the impact of arachidonic acid (AA) and docosahexaenoic acid (DHA) and their combination on colon cancer cell growth. The LS-174T colon cancer cell line was used to study the role of the prostaglandin precursor AA and the omega-3 polyunsaturated fatty acid DHA on cell growth. Cell viability was assessed in XTT assays. For analysis of cell cycle and cell death, flow cytometry and DAPI staining were applied. Expression of cyclooxygenase-2 (COX-2), p21 and bcl-2 in cells incubated with AA or DHA was examined by real-time RT-PCR. Prostaglandin E(2) (PGE(2)) generation in the presence of AA and DHA was measured using a PGE(2)-ELISA. AA increased cell growth, whereas DHA reduced viability of LS 174T cells in a time- and dose-dependent manner. Furthermore, DHA down- regulated mRNA of bcl-2 and up-regulated p21. Interestingly, DHA was able to suppress AA-induced cell proliferation and significantly lowered AA-derived PGE(2) formation. DHA also down-regulated COX-2 expression. In addition to the effect on PGE(2) formation, DHA directly reduced PGE(2)-induced cell proliferation in a dose-dependent manner. These results suggest that DHA can inhibit the pro-proliferative effect of abundant AA or PGE(2).

Apigenin, a non-mutagenic dietary flavonoid, suppresses lupus by inhibiting autoantigen presentation for expansion of autoreactive Th1 and Th17 cells

IntroductionLupus patients need alternatives to steroids and cytotoxic drugs. We recently found that apigenin, a non-mutagenic dietary flavonoid, can sensitize recurrently activated, normal human T cells to apoptosis by inhibiting nuclear factor-kappa-B (NF-κB)-regulated Bcl-xL, cyclooxygenase 2 (COX-2), and cellular FLICE-like inhibitory protein (c-FLIP) expression. Because sustained immune activation and hyperexpression of COX-2 and c-FLIP contribute to lupus, we treated SNF1 mice that spontaneously develop human lupus-like disease with apigenin.MethodsSNF1 mice with established lupus-like disease were injected with 20 mg/kg of apigenin daily and then monitored for development of severe nephritis. Histopathologic changes in kidneys, IgG autoantibodies to nuclear autoantigens in serum and in cultures of splenocytes, along with nucleosome-specific T helper 1 (Th1) and Th17 responses, COX-2 expression, and apoptosis of lupus immune cells were analyzed after apigenin treatment.ResultsApigenin in culture suppressed responses of Th1 and Th17 cells to major lupus autoantigen (nucleosomes) up to 98% and 92%, respectively, and inhibited the ability of lupus B cells to produce IgG class-switched anti-nuclear autoantibodies helped by these Th cells in presence of nucleosomes by up to 82%. Apigenin therapy of SNF1 mice with established lupus suppressed serum levels of pathogenic autoantibodies to nuclear antigens up to 97% and markedly delayed development of severe glomerulonephritis. Apigenin downregulated COX-2 expression in lupus T cells, B cells, and antigen-presenting cells (APCs) and caused their apoptosis. Autoantigen presentation and Th17-inducing cytokine production by dendritic cells were more sensitive to the inhibitory effect of apigenin in culture, as evident at 0.3 to 3 μM, compared with concentrations (10 to 100 μM) required for inducing apoptosis.ConclusionsApigenin inhibits autoantigen-presenting and stimulatory functions of APCs necessary for the activation and expansion of autoreactive Th1 and Th17 cells and B cells in lupus. Apigenin also causes apoptosis of hyperactive lupus APCs and T and B cells, probably by inhibiting expression of NF-κB-regulated anti-apoptotic molecules, especially COX-2 and c-FLIP, which are persistently hyperexpressed by lupus immune cells. Increasing the bioavailability of dietary plant-derived COX-2 and NF-κB inhibitors, such as apigenin, could be valuable for suppressing inflammation in lupus and other Th17-mediated diseases like rheumatoid arthritis, Crohn disease, and psoriasis and in prevention of inflammation-based tumors overexpressing COX-2 (colon, breast).

DHA and EPA Down-regulate COX-2 Expression through Suppression of NF-κB Activity in LPS-treated Human Umbilical Vein Endothelial Cells

Inflammatory processes of vascular endothelial cells play a key role in the development ofatherosclerosis. We determined the anti-inflammatory effects and mechanisms of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on LPS-treated human umbilical vein endothelial cells (HUVECs) to evaluate their cardioprotective potential. Cells were pretreated with DHA, EPA, or troglitazone prior to activation with LPS. Expression of COX-2, prostaglandin E(2) (PGE(2)) and IL-6 production, and NF-kappaB activity were measured by Western blot, ELISA, and luciferase activity, respectively. Results showed that EPA, DHA, or troglitazone significantly reduced COX-2 expression, NF-kappaB luciferase activity, and PGE(2) and IL-6 production in a dose-dependent fashion. Interestingly, low doses (10 microM) of DHA and EPA, but not troglitozone, significantly increased the activity of NF-kappaB in resting HUVECs. Our study suggests that while DHA, EPA, and troglitazone may be protective on HUVECs under inflammatory conditions in a dose-dependent manner. However there may be some negative effects when the concentrations are abnormally low, even in normal endothelium.

Triptolide inhibits COX‐2 expression and PGE2 release by suppressing the activity of NF‐κB and JNK in LPS‐treated microglia

Activated microglia participate in neuroinflammation which contributes to neuronal damage in neurodegenerative diseases. Inhibition of microglial activation may have potential anti-inflammatory effects. Our laboratory has previously reported that triptolide, a natural biologically active compound extracted from Tripterygium wilfordii, could protect dopaminergic neurons from inflammation-mediated damage. However, the mechanism by which triptolide inhibits inflammation remains unknown. We reported here that inhibition of prostaglandin E(2) (PGE(2)) production could be a potential mechanism of triptolide to suppress inflammation. Triptolide suppressed c-jun NH2-terminal kinase (JNK) phosphorylation, cyclooxygenase 2 (COX-2) expression and PGE(2) production in microglial cultures treated with lipopolysaccharide (LPS). Triptolide also greatly inhibited the transcriptional activity, but not the DNA-binding activity of nuclear factor-kappaB (NF-kappaB) in microglia following LPS stimulation. These results indicate that triptolide might suppress NF-kappaB activity to down-regulate COX-2 expression. The LPS-stimulated transcriptional activity of NF-kappaB was suppressed by inhibition of p38MAPK, but not by that of JNK and extracellular signal-regulated kinase. Furthermore, the LPS-induced PGE(2) production was reduced by inhibiting these kinases. Taken together, these results suggest that triptolide may suppress neuroinflammation via a mechanism that involves inactivation of two parallel signaling pathways: p38-NF-kappaB-COX-2-PGE(2) and JNK-PGE(2).

ShRNA-targeted Cyclooxygenase (COX)-2 inhibits proliferation, reduces invasion and enhances chemosensitivity in laryngeal carcinoma cells

Cyclooxygenase-2 (COX-2), one isoform of cyclooxygenase proinflammatary enzymes, is a causal factor for tumor development, invasion, metastasis, and chemoresistance. It is frequently overexpressed in a variety of human malignancies, including laryngeal carcinoma. To investigate its possibility as a therapeutic target for the treatment of laryngeal carcinoma, we employed RNA interference technology to downregulate endogenous gene COX-2 expression in laryngeal carcinoma cells and analyzed its phenotypical changes. Results showed that shRNA-mediated downregulation of COX-2 expression in human laryngeal carcinoma cells significantly inhibited cell proliferation and colony formation in vitro and reduced the potential of tumorigenicity in vivo. The specific downregulation led to cell arrest in the G(0)/G(1) phase of cell cycle and final apoptosis induction. The increased apoptosis was associated with the ratios of Bcl-2 or Bcl-xL/Bax. In the present study, we also observed that the downregulation of COX-2 could obviously enhanced the cytotoxic effect of Taxanes both in vitro and in vivo. All these results suggest that knockdown of COX-2 expression can lead to potent antitumor activity and chemosensitizing activity to taxanes in human laryngeal carcinomas.

Screening of KMU-4, 6, 7 on inflammatory responses in IFN-γ and LPS-induced mouse peritoneal macrophages

Korean Marine Plants (KMU-4, 6, 7) obtained from an herb which widely used in medicine for the treatment of a variety of pathologies. In this study, using mouse peritoneal macrophages, we have examined whether KMU-4, 6, 7 affects nitric oxide (NO) and COX-2 induced IFN- and LPS and cell viability. KMU-6 inhibits IFN- and LPS-induced NO. We found that KMU-6 had a little effect on COX-2 expression. These finding means that KMU-6 can be used in controlling macrophages mediated inflammatory disease. The present results indicate that KMU-6 has an inhibitory effect on the production of NO through down-regulation of COX-2 expression in LPS stimulated mouse peritoneal macrophages.

Silymarin downregulates COX-2 expression and attenuates hyperlipidemia during NDEA-induced rat hepatocellular carcinoma

Silymarin is a naturally available bioflavonoid and is a strong antioxidant with a capacity to inhibit the formation of tumors in several cancer models. In the present study, we investigated whether dietary supplementation of silymarin has any role in lipid components, lipid-metabolizing enzymes, free fatty acid profile, and expression of cyclooxygenase-2 (COX-2) in N-nitrosodiethylamine (NDEA)-induced hepatocellular carcinoma in rats. NDEA-induced rats showed severe hyperlipidemia along with upregulated expression of COX-2 as revealed by western blotting and immunohistochemistry. Dietary silymarin supplementation attenuated this hyperlipidemia and downregulated the expression of COX-2. Thus we conclude that compounds like silymarin with potent hypolipidemic effect are strong candidates as chemopreventive agents for the treatment of liver cancer.

Protective effect of curcumin against high glucose‐induced endoplasmic reticulum stress by downregulation of COX‐2 expression in huvecs

Cell Biology InternationalVolume 32, Issue 3 p. S14-S14 Protective effect of curcumin against high glucose-induced endoplasmic reticulum stress by downregulation of COX-2 expression in huvecs Ying Fan, Ying Fan Department of Physiology, Zhejiang University School of Medicine, Hangzhou, China National Education Base for Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, ChinaSearch for more papers by this authorXiang Hong Meng, Xiang Hong Meng Department of Physiology, Zhejiang University School of Medicine, Hangzhou, ChinaSearch for more papers by this authorWen Liang Chen, Wen Liang Chen Department of Physiology, Zhejiang University School of Medicine, Hangzhou, ChinaSearch for more papers by this authorLi Zhu, Li Zhu Department of Physiology, Zhejiang University School of Medicine, Hangzhou, ChinaSearch for more papers by this authorYue Liang Shen, Yue Liang Shen Department of Physiology, Zhejiang University School of Medicine, Hangzhou, ChinaSearch for more papers by this authorYing Ying Chen, Ying Ying Chen Department of Physiology, Zhejiang University School of Medicine, Hangzhou, ChinaSearch for more papers by this author Ying Fan, Ying Fan Department of Physiology, Zhejiang University School of Medicine, Hangzhou, China National Education Base for Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, ChinaSearch for more papers by this authorXiang Hong Meng, Xiang Hong Meng Department of Physiology, Zhejiang University School of Medicine, Hangzhou, ChinaSearch for more papers by this authorWen Liang Chen, Wen Liang Chen Department of Physiology, Zhejiang University School of Medicine, Hangzhou, ChinaSearch for more papers by this authorLi Zhu, Li Zhu Department of Physiology, Zhejiang University School of Medicine, Hangzhou, ChinaSearch for more papers by this authorYue Liang Shen, Yue Liang Shen Department of Physiology, Zhejiang University School of Medicine, Hangzhou, ChinaSearch for more papers by this authorYing Ying Chen, Ying Ying Chen Department of Physiology, Zhejiang University School of Medicine, Hangzhou, ChinaSearch for more papers by this author First published: 02 January 2013 https://doi.org/10.1016/j.cellbi.2008.01.069Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume32, Issue3March 2008Pages S14-S14 RelatedInformation

Unravelling perinatal programming of the kidney

to the editor: I read with great interest the paper of Baserga et al. ([1][1]), which describes the effect of uterine artery ligation in the pregnant rat on fetal cyclooxygenase-2 (COX-2) expression and blood pressure. This is an important subject and the study presents interesting results, but I

Effects of an ophthalmic formulation of meloxicam on COX-2 expression, PGE2 release, and cytokine expression in a model of acute ocular inflammation

Aim:To determine the efficacy of meloxicam ophthalmic formulation on COX-2 activity and expression, inflammation-related cytokines expression and inflammation in an ocular inflammation model.Methods:Ocular inflammation was induced in New Zealand rabbits...

Lef1 regulates COX-2 transcription in chondrocytes

Although the involvement of Wnt/β-catenin signaling pathway in the regulation of COX-2 expression has been suggested, the underlying molecular mechanisms are still unclear. Here, we demonstrate that lymphoid enhancer-binding factor 1 (Lef1) in concert with β-catenin is associated with the transcriptional regulation of the gene encoding COX-2 in mouse chondrocytes. Our results show that co-overexpression of Lef1 and β-catenin synergistically upregulates COX-2 expression. Furthermore, decrease of Lef1 expression using Lef1 siRNA results in the downregulation of COX-2 expression. Using bioinformatic analysis, we identified a conserved Lef1-binding site that is mapped at the 3′ region of the genomic COX-2 locus. In vivo and in vitro binding of Lef1 at the predicted binding site was proved using chromatin immunoprecipitation assays and electrophoretic mobility shift assays, respectively. Moreover, binding of Lef1 and β-catenin to the Lef1-binding site transactivates COX-2 promoter activity. Our results indicate a pivotal role of Lef1 in the regulation of COX-2 transcription in arthritic chondrocytes.

Uteroplacental insufficiency alters nephrogenesis and downregulates cyclooxygenase-2 expression in a model of IUGR with adult-onset hypertension

Clinical and animal studies indicate that intrauterine growth restriction (IUGR) following uteroplacental insufficiency (UPI) reduces nephron number and predisposes toward renal insufficiency early in life and increased risk of adult-onset hypertension. In this study, we hypothesized that the inducible enzyme cyclooxygenase-2 (COX-2), a pivotal protein in nephrogenesis, constitutes a mechanism through which UPI and subsequent glucocorticoid overexposure can decrease nephron number. We further hypothesized that UPI downregulates the key enzyme 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2), which converts corticosterone to inert 11-dehydrocorticosterone, thereby protecting both the glucocorticoid receptor (GR) and the mineralocorticoid receptor (MR) from the actions of corticosterone. Following bilateral uterine ligation on the pregnant rat, UPI significantly decreased renal COX-2, 11beta-HSD2, and GR mRNA and protein levels, but upregulated expression of MR at birth. At day 21 of life, 11beta-HSD2, GR, and also MR mRNA and protein levels were downregulated. UPI did not affect blood pressures (BP) at day 21 of life but significantly increased systolic BP in both genders at day 140. We conclude that in our animal model, UPI decreases fetal COX-2 expression during a period of active nephrogenesis in the IUGR rat, which is also characterized by decreased nephron number and adult-onset hypertension.

MAP kinase subtypes and Akt regulate diosgenin-induced apoptosis of rheumatoid synovial cells in association with COX-2 expression and prostanoid production

In the present study, we investigated the signalling pathways involved in diosgenin-induced apoptosis in human rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS) in vitro with particular interest on Akt and MAPKs activation in relation to arachidonic acid metabolism via COX-2 pathway. MAPK activation was measured by ELISA quantification in diosgenin-treated human RA FLS. Expression of Akt and phospho-Akt was analyzed by Western blot analysis. Nuclear factor-kappaB (NF-kappaB) translocation was evaluated by electromobility shift assay. The prostanoid production (COX-2 activity) was measured by quantitative ELISA. Diosgenin-induced apoptosis in the presence of MAPK or Akt inhibitors was detected by a quantitative determination of DNA fragmentation. Treatment of human RA FLS with 40 microM diosgenin caused an activation of p38 and JNK and an inhibition of ERK phosphorylation. Akt and NF-kappaB are potentially required for diosgenin-induced apoptosis in human RA FLS because 40 microM diosgenin abrogated Akt phosphorylation which correlated with an inhibition of NF-kappaB nuclear translocation. SB203580 and SP600125 (p38 and JNK inhibitors) reduced diosgenin-induced DNA fragmentation whereas U0126 and LY294002 (MEK and PI3 kinase/Akt inhibitors) caused an amplification of proapoptotic effect of diosgenin. Diosgenin increased COX-2 activity resulting in PGE2 and 6-keto-PGF1alpha overproduction in human RA FLS. All MAPK inhibitors markedly reduced diosgenin-induced PGE2 and 6-keto-PGF1alpha synthesis except for SP600125 on 6-keto-PGF1alpha production. These results provide, for the first time, strong evidence that a combined association implicating a MEK inhibitor (U0126) and diosgenin is the most effective in inducing very strong apoptosis with down-regulation of COX-2 expression and activity in human RA FLS.

Epigallocatechin Gallate Inhibits Phorbol Ester‐Induced Activation of NF‐κB and CREB in Mouse Skin

The modulation of intracellular signaling network involved in an inappropriate expression of cyclooxygenase-2 (COX-2) is a pragmatic approach for chemoprevention with a wide variety of dietary phytochemicals. Epigallocatechin gallate (EGCG), a major green tea polyphenol, is one of the most extensively investigated chemopreventive agents. Our previous study revealed that EGCG inhibited expression of COX-2 and activation of mitogen-activated protein kinases (MAPKs) in mouse skin stimulated with a prototype tumor promotor 12-O-tetradecanoylphorbol-13-acetate (TPA). This study was aimed at identifying transcription factors as molecular targets of EGCG in downregulating COX-2 expression. We found that EGCG inhibited TPA-induced DNA binding of NF-kappaB and CREB in mouse skin in vivo. EGCG also suppressed TPA-induced phosphorylation and subsequent degradation of IkappaBalpha, and prevented nuclear translocation of p65. We also examined whether extracellular signal-regulated protein kinase (ERK) and p38 MAPK, which are known to regulate activation of NF-kappaB, can also modulate CREB DNA binding. Pretreatment with U0126 and SB203580, pharmacological inhibitors of ERK and p38 MAPK, respectively, showed that SB203580, but not U0126, attenuated TPA-induced CREB DNA binding in mouse skin. Taken together, EGCG inhibited TPA-induced DNA binding of NF-kappaB and CREB by blocking activation of p38 MAPK, which may provide a molecular basis of COX-2 inhibition by EGCG in mouse skin in vivo.