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Studies on the development of safe anti-inflammatory agents targeting the inhibition of the mPGES-1 enzyme responsible for PGE2 production are increasing day by day. Moreover, selective inhibition of the mPGES-1 enzyme which modulates the tumor microenvironment and inhibits tumor growth, making the mPGES-1 enzyme one of the important macromolecular targets in cancer therapy. The aim of our study was to develop selective mPGES-1 inhibitors and to determine their in silico mPGES-1 enzyme inhibition potential. In this study, the binding affinities of 14 novel designed 5-benzylidene-2-(arylsulfonylhydrazono)thiazolidine-4-one derivatives were investigated against mPGES-1 and COX-2 enzymes by computer-aided molecular modeling studies. Among the designed compounds 1-14, it was presented with in silico data that compound 8-14, which does not interact with the active site of the COX-2 enzyme, exhibited selective binding with mPGES-1 enzyme. Moreover, compounds 10-13 have been suggested as selective mPGES-1 inhibitors with a better in silico binding energy than the first discovered mPGES-1 inhibitor MK886. Finally, ADMET profiles of compounds 1-14 were calculated. None of these compounds violated the Lipinski and Veber rules. [ABSTRACT FROM AUTHOR]

5-Aminolevulinic acid (5-ALA) induces the accumulation of a large amount of protoporphyrin IX (PpIX) in tumors, which has been used in the treatment of several cancers. 5-ALA is commonly used for fluorescence-guided tumor resection in clinical neurosurgery and for photodynamic therapy based on the generation of cytotoxic oxygen. The purpose of this study was to identify the mechanisms of 5-ALA-induced immune response in macrophages in malignant glioma. Intracellular levels of 5-ALA-induced PpIX in C3H/HeN murine peritoneal macrophages were measured by the median fluorescence intensity using flow cytometry and confocal laser scanning microscopy. Macrophages were cultured in vitro with or without 0.5 mM 5-ALA, 0.1 μg/mL lipopolysaccharide, and 20% glioma-conditioned medium. Levels of immunosuppressive prostaglandin E 2 (PGE 2), interleukin-10, and transforming growth factor β were measured using enzyme immunoassay in the culture supernatant. In addition, macrophages and RSV-M mouse glioma cells were co-cultured in vitro with cell culture inserts with or without 5-ALA (0.1 and 0.5 mM) and lipopolysaccharide (0.1 μg/mL). We found that 5-ALA-induced PpIX accumulated in macrophages and significantly suppressed PGE 2 production and expression of both cyclooxygenase-2 and microsomal prostaglandin E synthase-1. 5-ALA treatment also suppressed PGE 2 production by glioma-conditioned medium. 5-ALA suppressed RSV-M glioma cell proliferation in a concentration-dependent manner. These results indicate that 5-ALA suppressed PGE 2 production by macrophages via the downregulation of cyclooxygenase-2 and microsomal prostaglandin E synthase-1 expression levels. This is a novel mechanism to induce effective immune response against glioma in macrophages. [ABSTRACT FROM AUTHOR]

Stress and glucocorticoids suppress adult neurogenesis in the hippocampus. However, the molecular mechanisms underlying stress-induced impairment of adult neurogenesis are poorly understood. We previously suggested that cyclooxygenase (COX)-2 is a common mediator of stresses in the brain. Here, using a lipopolysaccharide (LPS)-induced acute infectious stress model, we evaluated the roles of COX-2 and its major downstream product prostaglandin E2 (PGE2) in adult neurogenesis and the influence of glucocorticoids on COX-2-related signaling. Treatment of rats with LPS significantly decreased neurogenesis in the dentate gyrus (DG) of the hippocampus, and this inhibitory effect of LPS on neurogenesis was reversed by the glucocorticoid receptor antagonist RU486. Moreover, RU486 significantly enhanced the increase in messenger RNA (mRNA) levels of COX-2 and microsomal prostaglandin E synthase (mPGES)-1 in the hippocampus following LPS stimulation. Administration of AH6809, a selective antagonist of the PGE2 EP2 receptor, as well as NS398, a COX-2 selective inhibitor, exacerbated the suppression of proliferation of neural progenitor cells (NPCs) in the DG. Gene expression of EP1, EP2, and EP3, but not EP4, receptors was also increased following LPS stimulation. Immunohistochemical studies indicated that NPCs expressed EP2 receptor, whereas the majority of cells expressing COX-2 and mPGES-1 were mature neurons in the DG. These results suggest that acute infectious stress upregulates COX-2-related signaling in neurons in the DG, which plays a protective role in neurogenesis through EP2 receptor at least partially. In addition, LPS-induced glucocorticoids suppress this COX-2-related signaling, resulting in decreased neurogenesis. [ABSTRACT FROM AUTHOR]

COX-2 inhibitors exhibit anticancer effects in various cancer models but due to the adverse side effects associated with these inhibitors, targeting molecules downstream of COX-2 (such as mPGES-1) has been suggested. Even after calls for mPGES-1 inhibitor design, to date there are only a few published inhibitors targeting the enzyme and displaying anticancer activity. In the present study, we have deployed both ligand and structure-based drug design approaches to hunt novel drug-like candidates as mPGES-1 inhibitors. Fifty-four compounds with tested mPGES-1 inhibitory value were used to develop a model with four pharmacophoric features. 3D-QSAR studies were undertaken to check the robustness of the model. Statistical parameters such asr2= 0.9924,q2= 0.5761 andFtest = 1139.7 indicated significant predictive ability of the proposed model. Our QSAR model exhibits sites where a hydrogen bond donor, hydrophobic group and the aromatic ring can be substituted so as to enhance the efficacy of the inhibitor. Furthermore, we used our validated pharmacophore model as a three-dimensional query to screen the FDA-approved Lopac database. Finally, five compounds were selected as potent mPGES-1 inhibitors on the basis of their docking energy and pharmacokinetic properties such as ADME and Lipinski rule of five. [ABSTRACT FROM PUBLISHER]

Inflammatory stimuli induce prostaglandin E 2 (PGE 2 ) synthesis by upregulating cycloxgenase-2 (COX-2) and microsomal PGE synthase-1 (mPGES-1). Glycogen synthase kinase-3 (GSK-3) reportedly plays an important role in inflammatory reactions, whereas the role of this enzyme in inflammatory PGE 2 production remains unclear. In the present study, therefore, we examined whether inhibition of GSK-3 can reduce inflammatory PGE 2 production in vitro and in vivo . When macrophage-like cells differentiated from THP-1 were stimulated with lipopolysaccharide (LPS), PGE 2 production and the expression levels of COX-2 and mPGES-1 were markedly elevated. GSK-3 inhibitors LiCl and SB216763 strongly suppressed their protein levels through inhibition of mRNA expressions. Subsequently, we examined the effect of GSK-3 inhibitors on nuclear factor κB (NF-κB) and early growth response-1 (Egr-1). The GSK-3 inhibitors had no significant effect on the NF-κB pathway, whereas they significantly decreased the expression level of Egr-1. Pharmacological and genetic inhibitions of GSK-3 also strongly suppressed PGE 2 production in cultured peritoneal macrophages and in inflammatory air pouches made under the skin of living mice. These results suggested that GSK-3 plays a key role in PGE 2 production by increasing COX-2 and mPGES-1 probably through Egr-1-mediated transcription and GSK-3 inhibitors may be potential as novel anti-inflammatory drugs. [ABSTRACT FROM AUTHOR]

Prostaglandin (PG) signalling is involved in human and animal cancer development. PG E2 (PGE2) tumour-promoting activity has been confirmed and its production is controlled by Cyclooxygenase-2 (COX-2) and microsomal PGE synthase-1 (mPGES-1). Evidence suggests that mPGES-1 and COX-2 contribute to carcinogenesis through the EP2 receptor. The aim of our study was to detect by immunohistochemistry COX-2, mPGES-1 and EP2 receptor expression in canine ( n = 46) and feline ( n = 50) mammary tumours and in mammary non-neoplastic tissues. COX-2 positivity was observed in 83% canine and 81% feline mammary carcinomas, mPGES-1 in 75% canine and 66% feline mammary carcinomas and the EP2 receptor expression was observed in 89% canine and 54% feline carcinomas. The frequency of COX-2, EP2 receptor and mPGES-1 expression was significantly higher in carcinomas than in non-neoplastic tissues and adenomas. COX-2, mPGES-1 and EP2 receptor expression was strongly associated. These findings support a role of the COX-2/PGE2 pathway in the pathogenesis of these tumours. [ABSTRACT FROM AUTHOR]

Background: Microglia recognize pathogen-associated molecular patterns such as double-stranded RNA (dsRNA) present in some viruses. Polyinosinic-polycytidylic acid [poly(I:C)] is a synthetic analog of dsRNA that activates different molecules, such as retinoic acid-inducible gene I, melanoma differentiation-associated gene 5, and toll-like receptor-3 (TLR3). Poly(I:C) increases the expression of different cytokines in various cell types. However, its role in the regulation of the production of inflammatory mediators of the arachidonic acid pathway by microglia is poorly understood. Methods: In the present study, we evaluated the effect of poly(I:C) on the production of prostaglandin E2 (PGE2) and the inducible enzymes cyclooxygenase-2 (COX-2) and microsomal prostaglandin E synthase-1 (mPGES-1) in primary rat microglia. Microglia were stimulated with different concentrations of poly(I:C) (0.1-10 μg/ml), and the protein levels of COX-2 and mPGES-1, as well as the release of PGE2, were determined by western blot and enzyme immunoassay (EIA), respectively. Values were compared using one-way ANOVA with post hoc Student-Newman-Keuls test. Results: Poly(I:C) increased the production of PGE2, as well as mPGES-1 and COX-2 synthesis. To investigate the mechanisms involved in poly(I:C)-induced COX-2 and mPGES-1, we studied the effects of various signal transduction pathway inhibitors. Protein levels of COX-2 and mPGES-1 were reduced by SB203580, SP600125, and SC514 (p38 mitogen-activated protein kinase (MAPK), c-Jun N-terminal kinase (JNK), and IκB kinase (IKK) inhibitors, respectively), as well as by PD98059 and PD0325901 (mitogen-activated protein kinase kinase (MEK) inhibitors). Rapamycin, a mammalian target of rapamycin (mTOR) inhibitor, enhanced the synthesis of COX-2. Inhibition of phosphatidylinositol 3-kinase (PI3K) by LY294002 or dual inhibition of PI3K/mTOR (with NVP-BEZ235) enhanced COX-2 and reduced mPGES-1 immunoreactivity. To confirm the data obtained with the inhibitors, we studied the phosphorylation of the blocked kinases by western blot. Poly(I:C) increased the phosphorylation of p38 MAPK, extracellular signal-regulated kinase (ERK), JNK, protein kinase B (Akt), and IκB. Conclusions: Taken together, our data demonstrate that poly(I:C) increases the synthesis of enzymes involved in PGE2 synthesis via activation of different signaling pathways in microglia. Importantly, poly(I:C) activates similar pathways also involved in TLR4 signaling that are important for COX-2 and mPGES-1 synthesis. Thus, these two enzymes and their products might contribute to the neuropathological effects induced in response to dsRNA, whereby the engagement of TLR3 might be involved. [ABSTRACT FROM AUTHOR]

Liver X receptors (LXRs) are nuclear receptors that act as ligand-dependent transcription factors forming permissive heterodimers with retinoid X receptors (RXRs). In this study we aimed to assess the effect of LXR/RXR activation on the transcriptional induction of pro-inflammatory genes including cyclooxygenase-2 (COX-2) and microsomal prostaglandin E 2 synthase-1 (mPGES-1) in activated macrophages. Our study shows that LXR ligands such as oxysterols, GW3965 or TO901317, as well as RXR ligands like 9cis retinoic acid or SR11237, decreased LPS-induced expression of COX-2 and mPGES-1. Consequently, LPS-dependent PGE 2 production was substantially reduced in macrophages treated with LXR/RXR ligands. The inhibitory effects of LXR/RXR activation on LPS-induced expression of COX-2 and mPGES-1 in macrophages, occurred by a mechanism involving interference with transcriptional activation of these genes. LXR/RXR activation interfered with the activity of transcription factors essential in the up-regulation of the expression of pro-inflammatory genes in these cells, such as NFκB, but also Egr-1, which had not been previously associated with LXR-mediated gene repression. As this transcription factor is involved in the regulation of a variety of genes involved in inflammatory processes, LXR and RXR-mediated interference with Egr-1 signaling could represent an important event mediating the anti-inflammatory effects of these receptors in macrophages. [ABSTRACT FROM AUTHOR]

The inhibitory effect of 15-deoxy-Δ 12,14 -prostaglandin J 2 (15d-PGJ 2 ) on proinflammatory gene expression has been extensively documented and frequently ascribed to its ability to prevent NF-κB pathway activation. We and others have previously demonstrated that it was frequently independent of the peroxisome proliferator activated receptor (PPAR)γ activation. Here, we provide evidence that induction of intracellular heat shock protein (HSP)70 by oxidative stress is an additional regulatory loop supporting the anti-inflammatory effect of 15d-PGJ 2 in chondrocytes. Using real-time quantitative PCR and Western blotting, we showed that 15d-PGJ 2 stimulated HSP70, but not HSP27 expression while increasing oxidative stress as measured by spectrofluorimetry and confocal spectral imaging. Using N -acetylcysteine (NAC) as an antioxidant, we demonstrated further that oxidative stress was thoroughly responsible for the increased expression of HSP70. Finally, using an HSP70 antisense strategy, we showed that the inhibitory effect of 15d-PGJ 2 on IL-1-induced activation of the NF-κB pathway, COX-2 and mPGES-1 expression, and PGE 2 synthesis was partly supported by HSP70. These data provide a new anti-inflammatory mechanism to support the PPARγ-independent effect of 15d-PGJ 2 in chondrocyte and suggest a possible feedback regulatory loop between oxidative stress and inflammation via intracellular HSP70 up-regulation. This cross talk is consistent with 15d-PGJ 2 as a putative negative regulator of the inflammatory reaction. [ABSTRACT FROM AUTHOR]

Artesunate is a semi-synthetic derivative of artemisinin used to treat malaria, and has been shown to possess anti-inflammatory activity. In this study, we have investigated the effect of artesunate on PGE 2 production/COX-2 protein expression in LPS + IFNγ-activated BV2 microglia. To further understand the mechanism of action of this compound, we investigated its interference with NF-κB and p38 MAPK signalling pathways. PGE 2 production was determined using EIA, while protein expressions of inflammatory targets like COX-2, mPGES-1, IκB, p38 and MAPKAPK2 were evaluated using western blot. An NF-κB-bearing luciferase reporter gene assay was used to test the effect of artesunate on NF-κB-mediated pro-inflammatory gene expression in HEK293 cells stimulated with TNFα (1 ng/ml). Artesunate (2 and 4 μM), significantly ( p <0.01) suppressed PGE 2 production in LPS + IFNγ-activated BV2 microglia. This effect was found to be mediated via reduction in COX-2 and mPGES-1 proteins. Artesunate also produced significant inhibition of TNFα and IL-6 production in activated BV2 microglia. Further investigations showed that artesunate (0.5–4 μM) significantly ( p <0.001) reduced NF-κB-driven luciferase expression, and inhibited IκB phosphorylation and degradation, through inhibition of IKK. Artesunate inhibited phosphorylation of p38 MAPK and its substrate MAPKAPK2 following stimulation of microglia with LPS + IFNγ. Taken together, we have shown that artesunate prevents neuroinflammation in BV2 microglia by interfering with NF-κB and p38 MAPK signalling. [ABSTRACT FROM AUTHOR]

Fever is a hallmark of inflammatory and infectious diseases. The febrile response is triggered by prostaglandin E2 synthesis mediated by induced expression of the enzymes cyclooxygenase-2 (COX-2) and microsomal prostaglandin E synthase 1 (mPGES-1). The cellular source for pyrogenic PGE2 remains a subject of debate; several hypotheses have been forwarded, including immune cells in the periphery and in the brain, as well as the brain endothelium. Here we generated mice with selective deletion of COX-2 and mPGES1 in brain endothelial cells. These mice displayed strongly attenuated febrile responses to peripheral immune challenge. In contrast, inflammationinduced hypoactivity was unaffected, demonstrating the physiological selectivity of the response to the targeted gene deletions. These findings demonstrate that PGE2 synthesis in brain endothelial cells is critical for inflammation-induced fever. [ABSTRACT FROM AUTHOR]

Abstract: Cyclooxygenase-2 (COX-2) is known to correlate with a poor prognosis of prostate cancer and contribute to tumor metastasis. However, the precise mechanism of this phenomenon remains unknown. We have previously reported that host stromal microsomal prostaglandin E synthase-1 (mPGES-1) appeared critical for tumor-associated angiogenesis and tumor growth. Here, we tested whether or not mPGES-1 has a critical role in lung metastasis formation of prostate cancer. Murine prostate cancer cells (RM9) were intravenously injected and lung metastasis was estimated by counting colonies in the lungs. Mice treated with a selective COX-2 inhibitor, celocoxib, were suppressed lung metastasis compared to vehicle mice. This lung metastasis formation was also reduced in mPGES-1 knockout (mPGES-1 KO) mice, compared with wild type (WT) mice. This was accompanied with reduced angiogenesis around the metastasized colonies of RM9. Plasma protein levels and metastasized lung tissue mRNA levels of vascular endothelial growth factor (VEGF) and stromal cell derived factor-1 (SDF-1) were significantly suppressed in mPGES-1 KO mice in comparison with WT mice. In addition, the expressions of matrix metalloproteinases (MMP)-9, and metalloproteinases (MMP)-2 were down-regulated in metastatic lungs in mPGES-1 KO mice. These results suggested that host mPGES-1 was essential for MMP-2 and MMP-9 up-regulation that enhances tumor metastasis. mPGES-1 appears to be critical for tumor metastasis in prostate cancers. mPGES-1 inhibitors may be useful to protect against prostate cancer metastasis. [Copyright &y& Elsevier]

Cyclooxygenase (COX)-2-derived prostaglandin E2 (PGE2) supports the growth of a spectrum of cancers. The potential benefit of COX-2-inhibiting non-steroidal anti-inflammatory drugs (NSAIDs) for cancer treatment is however limited by their well-known cardiovascular side-effects. Therefore, targeting microsomal PGE synthase 1 (mPGES-1), the downstream enzyme in the COX-2-dependent pathway of PGE2 production might be attractive, although conflicting data regarding a potential tumor-supporting function of mPGES-1 were reported. We determined the impact of mPGES-1 in human DU145 prostate cancer cell growth. Surprisingly, knockdown of mPGES-1 did not alter growth of DU145 monolayer cells, but efficiently inhibited the growth of DU145 multicellular tumor spheroids (MCTS). Opposed to MCTS, monolayer cells did not secrete PGE2 due to a lack of COX-2 expression, which was induced during spheroid formation. Pharmacological inhibition of COX-2 and mPGES-1 supported the crucial role of PGE2 for growth of MCTS. The functionality of spheroid-derived PGE2 was demonstrated by its ability to inhibit cytotoxic T cell activation. When investigating mechanisms of spheroid-induced COX-2 induction, we observed that among microenvironmental factors neither glucose deprivation, hypoxia nor tumor cell apoptosis enhanced COX-2 expression. Interestingly, interfering with apoptosis in spheroids triggered a shift towards necrosis, thus augmenting COX-2 expression. We went on to demonstrate that necrotic cells induced COX-2 mRNA expression and PGE2 secretion from live tumor cells. In conclusion, necrosis-dependent COX-2 upregulation in MCTS promoted PGE2-dependent tumor growth and inhibited activated cytotoxic T cells. Hence, blocking mPGES-1 as a therapeutic option may be considered for COX-2/mPGES-1-positive solid cancers. [ABSTRACT FROM AUTHOR]

Abstract: Prostanoids play pivotal roles in inflammation and pain. Cyclooxygenase (COX) inhibitors, the nonsteroidal anti-inflammatory drugs (NSAIDs), depress prostanoid formation and are widely used to treat inflammatory pain. However, their therapeutic benefit is offset by serious side-effects, primarily gastrointestinal and cardiovascular complications. Pathway elements downstream of the COX enzymes, particularly the terminal synthases and receptors of prostaglandin E2, have been proposed as alternative targets for the development of novel NSAID like drugs. Here, we summarize the current knowledge on the roles of individual prostanoids in modulating inflammatory pain. [Copyright &y& Elsevier]

Abstract: We previously suggested that cyclooxygenase (COX)-2 plays a role as a common mediator of stresses in the brain. In the present study, we evaluated the possible involvement of COX-2-related signaling in the activation of the hypothalamic–pituitary–adrenal (HPA) axis under three different stress conditions, namely infectious (lipopolysaccharide, LPS), hypoglycemic (2-deoxy-d-glucose, 2DG) and restraint (1h) stresses in rats. Both an unselective COX inhibitor (indomethacin) and a selective COX-2 inhibitor (NS-398) significantly attenuated the increase of serum corticosterone levels after LPS and restraint stresses, but not after 2DG injection. COX-2 and microsomal prostaglandin E synthase (mPGES)-1 mRNA levels in the hypothalamus were significantly increased after LPS injection in intact rats. In adrenalectomized (ADX) rats, the expression of both genes was significantly increased after 2DG and restraint stresses, which was blocked by treatment with corticosterone. Interleukin-1β (IL-1β) mRNA levels in the hypothalamus in intact rats were increased only by LPS injection, though those in ADX rats were increased by all three stress stimuli. These results suggest that the relationship between COX-2-related signaling and activation of the HPA axis is stress–specific, and that COX-2-related signaling preferably mediates infectious and restraint stresses. Furthermore, the expression of COX-2 and mPGES-1 mRNA under the infectious stress condition was not negatively regulated by endogenous glucocorticoids, likely due to an increase in IL-1β levels. [Copyright &y& Elsevier]

Prostaglandin E (PGE) is a bioactive lipid that elicits a wide range of biological effects associated with inflammation and cancer. PGE exerts diverse effects on cell proliferation, apoptosis, angiogenesis, inflammation, and immune surveillance. This review concentrates primarily on gastrointestinal cancers, where the actions of PGE are most prominent, most likely due to the constant exposure to dietary and environmental insults and the intrinsic role of PGE in tissue homeostasis. A discussion of recent efforts to elucidate the complex and interconnected pathways that link PGE signaling with inflammation and cancer is provided, supported by the abundant literature showing a protective effect of NSAIDs and the therapeutic efficacy of targeting mPGES-1 or EP receptors for cancer prevention. However, suppressing PGE formation as a means of providing chemoprotection against all cancers may not ultimately be tenable, undoubtedly the situation for patients with inflammatory bowel disease. Future studies to fully understand the complex role of PGE in both inflammation and cancer will be required to develop novel strategies for cancer prevention that are both effective and safe. [ABSTRACT FROM AUTHOR]

Accumulating evidence suggests that sphingosine kinase 1 (SphK1) plays a key role in carcinogenesis by regulating cyclooxygenase-2 (COX-2) expression. Recent clinical studies have revealed that COX-2 inhibitors cause adverse cardiovascular side effects, likely due to inhibition of prostacyclin (PGI2). In this work, we investigated the roles of SphK1 inhibition on blood pressure (BP). The results show that lack of SphK1 expression did not exacerbate angiotensin II (Ang II)-induced acute hypertension, whereas celecoxib, a COX-2 inhibitor, augmented and sustained higher BP in mice. Interestingly, SphK1-knockout mice inhibited prostaglandin E2 (PGE2) but not PGI2 production in response to Ang II, whereas celecoxib blocked both PGE2 and PGI2 production. Mechanistically, SphK1 down-regulation by siRNA in human umbilical vein endothelial cells decreased cytokine-induced PGE2 production primarily through inhibition of microsomal PGE synthase-1 (mPGES-1), not COX-2. SphK1 down-regulation also decreased MKK6 expression, which phosphorylates and activates P38 MAPK, which, in turn, regulates early growth response-1 (Egr-1), a transcription factor of mPGES-1. Together, these data indicate that SphK1 regulates PGE2 production by mPGES-1 expression via the p38 MAPK pathway, independent of COX-2 signaling, in endothelial cells, suggesting that SphK1 inhibition may be a promising strategy for cancer chemoprevention with lack of the adverse cardiovascular side effects associated with coxibs [ABSTRACT FROM AUTHOR]

Abstract: Ethnopharmacological relevance: Anacardium occidentale is used in traditional African medicine for the treatment of arthritis, fever, aches, pains, and inflammation of the extremities. Aim of the study: In this study, we investigated the molecular mechanisms responsible for anti-inflammatory effects of a stem bark extract of A. occidentale (ANE) in LPS-stimulated microglia. Materials and methods: Nitric oxide (NO), prostaglandin E2 and cytokine (TNFα and IL-6) production were evaluated in supernatants from LPS-stimulated BV-2 cells. Cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS) and microsomal prostaglandin E2 synthase (mPGES-1) protein expressions in rat primary microglia were measured using western blot. The effects of ANE on NF-κB activation and nuclear translocation were evaluated in the luciferase reporter gene assay and ELISA, while ability of ANE to influence IκB phosphorylation was determined using ELISA specific for phospho-IκB. The involvement of MAPK phosphorylation in the anti-inflammatory actions of ANE was evaluated using specific ELISA for phospho-p38, phospho-p42/44 and phospho-JNK. The MTT assay was used to determine the effect of ANE on BV-2 microglia viability. Results: ANE (25–100μg/ml) produced significant (p<0.05) reduction in the production of NO, PGE2, TNFα and IL-6 in BV-2 microglia stimulated with LPS for 24h. Pre-treatment with ANE caused a significant (p<0.05) inhibition of COX-2, iNOS and mPGES-1 protein expressions in the rat primary microglia. Further experiments showed that ANE inhibited COX-2 and iNOS protein expression via IκB-mediated nuclear translocation and transactivation of NF-κB. Our studies also revealed that ANE produced significant (p<0.05) and dose-dependent inhibition of p38, p42/44 and JNK MAPK phosphorylation in LPS-activated BV-2 microglia. Conclusions: We conclude that ANE has an anti-inflammatory property related to inhibition of inflammation-associated cytokine production as well as iNOS and COX-2 gene expression by blocking NF-κB and MAPK pathways in the microglia. It is also suggested that mPGES-1 inhibition contributes to the effect of ANE on PGE2 production in the microglia. [Copyright &y& Elsevier]

Summary: Accumulating evidence suggests that cyclooxygenase (COX)-2 is involved in the pathogenesis of human and canine osteosarcoma. The aim of this study was to investigate the expression of COX-2 in normal, reactive and neoplastic canine bone and the events downstream to COX-2 that lead to prostaglandin E2 (PGE2) production. COX-2, microsomal PGE2 synthase-1 (mPGES-1) and the PGE2 receptor (EP2) were assessed by immunohistochemistry in 12 samples of normal bone, 14 cases of fracture callus and 27 appendicular osteosarcomas. No immunoreactivity to COX-2, mPGES-1 or EP2 receptor was observed in normal bone. Fifty percent of reactive bone samples expressed COX-2 and 57% expressed mPGES-1 and EP2 receptor, although with weak labelling intensity. Ninety-three percent of osteosarcomas expressed COX-2, while mPGES-1 was expressed by 85% and EP2 receptor by 89% of the tumours. The data confirm that COX-2 is expressed at high level in osteosarcoma and support the use of COX-2 inhibitors to improve the response to chemotherapy. The possibility of blocking the EP2 or the selective inhibition of mPGES-1, rather than COX-2 activity, might decrease the incidence of adverse effects that occur due to the inhibition of prostanoids other than PGE2. [Copyright &y& Elsevier]

Abstract: The imidazoquinoline derivative 1 was found as a novel mPGES-1 inhibitor. Optimization of 1 led to the identification of the 2-chlorophenyl group at the C(2)-position and the quinolone structure at the C(4)-position. Compound 33, the most potent synthesized compound, showed excellent mPGES-1 inhibition (IC50 =9.1nM) with high selectivity (>1000-fold) over both COX-1 and COX-2. [Copyright &y& Elsevier]

Abstract: Endometriosis is one of the most common gynecological diseases in women of reproductive age. Although cyclooxygenase (COX)-2 inhibitors are effective in the treatment of endometriosis, the adverse cardiovascular effects associated with these inhibitors have limited their use. Microsomal prostaglandin E synthase-1 (mPGES-1) is an inducible enzyme downstream of COX-2 in prostaglandin E2 biosynthesis. Previously, we developed mPGES-1 knockout mice (mPGES-1−/−) and have identified for the first time the roles of ectopic lesion- and host-associated mPGES-1 in angiogenesis and the growth of endometrial tissues. When mPGES-1−/− endometrial fragments were implanted into wild type (WT) mice (mPGES-1−/−→WT), or WT fragments implanted into mPGES-1−/− mice (WT→mPGES-1−/−), the growth of the implants was suppressed at days 14 and 28 after implantation, compared toWT→WT transplantation. An even greater degree of suppression was observed in mPGES-1−/− endometrial fragments implanted into mPGES-1−/− mice (mPGES-1−/−→mPGES-1−/−). After WT-WT implantation, mPGES-1 expression was localized at the border of the implanted endometrial tissues. Microvessel density, determined by CD31 immunostaining, was markedly suppressed in the mPGES-1−/− endometrial fragments implanted into mPGES-1−/− mice, with some suppression also observed in the mPGES-1−/−→WT and WT→mPGES-1−/− groups. The expression of vascular endothelial growth factor (VEGF-A) was significantly reduced in mPGES-1−/− endometrial tissues implanted into mPGES-1−/− mice at days 14 and 28, in comparison to the WT→WT group. These results suggested that mPGES-1 enhanced angiogenesis and growth of the endometrial implant, and indicate that mPGES-1 may be a good therapeutic target for endometriosis. [Copyright &y& Elsevier]

Purpose: In addition to cyclooxygenase-2 (COX-2) which is related to prostaglandin E2 synthesis, other enzymes such as cytosolic phospholipase A2 (cPLA2), microsomal prostaglandin E2 synthase-1 (mPGES-1), and 15-prostaglandin dehydrogenase (15-PGDH) have been suggested to be related to carcinogenesis of colorectal cancer (CRC). The aim of this study was to investigate the roles of cPLA2, COX-2, mPGES-1, and 15-PGDH in tumor progression. Materials and Methods: cPLA2, COX-2, mPGES-1, 15-PGDH, and vascular endothelial growth factor (VEGF) expressions were immunohistochemically examined in 89 CRC, and their expressions were compared with each other or clinicopathologic parameters as well as VEGF as tumor progression parameters. Results: cPLA2 was expressed in 54.5%, COX-2 in 80.5%, mPGES-1 in 96.4%, 15-PGDH in 46.1%, and VEGF in 65.9%. The expression of cPLA2 correlated with VEGF expression. COX-2 expression was correlated with the depth of invasion, tumor stage, cPLA2, and VEGF expressions. Moreover, VEGF revealed the highest expression in the tissues positive for both cPLA2 and COX-2. Furthermore, 15-PGDH expression was inversely correlated with VEGF expression. Conclusion: The present study demonstrates that cPLA2 and mPGES-1, in addition to COX-2, are constitutively overexpressed, and that 15-PGDH might be attenuated in colorectal cancer. Furthermore, cPLA2 and 15-PGDH as well as COX-2 could have an important role in tumor progression. [ABSTRACT FROM AUTHOR]

In our recent studies, we focused our attention on the synthesis of several γ-hydroxybutenolides designed on the basis of petrosaspongiolide M 1 (PM) structure that has been recognized to potently inhibit the inflammatory process through the selective PLA2 enzyme inhibition. By means of a combination of computational methods and efficient synthetic strategies, we generated small collections of PM modified analogs to identify new potent PLA2 inhibitors, suitable for clinical development. In the course of the biological screening of our compounds, we discovered a potent and selective inhibitor of mPGES-1 expression, the benzothiophene γ-hydroxybutenolide 2, which so far represents the only product, together with resveratrol, able to reduce PGE2 production through the selective downregulation of mPGES-1 enzyme. In consideration that microsomal prostaglandin E synthase 1 ( mPGES-1) is one of the most strategic target involved both in inflammation and in carcinogenesis processes, we decided to explore the biological effects of some structural changes of the γ-hydroxybutenolide 2, hoping to improve its biological profile. This optimization process led to the identification of three strictly correlated compounds 14g, 16g, and 18 with higher inhibitory potency on PGE2 production on mouse macrophage cell line RAW264.7 through the selective modulation of mPGES-1 enzyme expression. [ABSTRACT FROM AUTHOR]

Abstract: Cerebral microvascular endothelial cells play an active role in maintaining cerebral blood flow, microvascular tone and blood brain barrier (BBB) functions. Endogenous N-acyl-dopamines like N-arachidonoyl-dopamine (NADA) and N-oleoyl-dopamine (OLDA) have been recently identified as a new class of brain neurotransmitters sharing endocannabinoid and endovanilloid biological activities. Endocannabinoids are released in response to pathogenic insults and may play an important role in neuroprotection. In this study we demonstrate that NADA differentially regulates the release of PGE2 and PGD2 in the microvascular brain endothelial cell line, b.end5. We found that NADA activates a redox-sensitive p38 MAPK pathway that stabilizes COX-2 mRNA resulting in the accumulation of the COX-2 protein, which depends on the dopamine moiety of the molecule and that is independent of CB1 and TRPV1 activation. In addition, NADA inhibits the expression of mPGES-1 and the release of PGE2 and upregulates the expression of L-PGD synthase enhancing PGD2 release. Hence, NADA and other molecules of the same family might be included in the group of lipid mediators that could prevent the BBB injury under inflammatory conditions and our findings provide new mechanistic insights into the anti-inflammatory activities of NADA in the central nervous system and its potential to design novel therapeutic strategies to manage neuroinflammatory diseases. [Copyright &y& Elsevier]

The transcription factor NF-κB is activated in neurons and promotes neuronal death in cerebral ischemia. Its target genes include cytosolic phospholipase A-2 (cPLA-2), cyclooxygenase-2 (COX-2), and microsomal prostaglandin E2 synthase-1 (mPGES-1), three genes that are involved in the synthesis of prostaglandin E2 (PGE2). In our study, oxygen glucose deprivation (OGD), an in vitro model of cerebral ischemia, activated NF-κB activity in primary cortical neurons. Furthermore, OGD and the NF-κB activator tumor necrosis factor stimulated the expression of cPLA-2, cyclooxygenase-2 (COX-2), and mPGES-1 and increased the release of PGE2 from neurons. Expression of a constitutively active IκB kinase (IKK) or the NF-κB subunit p65 in neurons stimulated the transcription of cPLA-2, COX-2, and mPGES-1. Finally, inhibition of IKK in neurons blocked the induction of the three genes involved in PGE2 synthesis in vivo. In summary, NF-κB controls the neuronal expression of three genes involved in PGE2 synthesis in cerebral ischemia. [ABSTRACT FROM AUTHOR]

Inflammation is closely linked to the abnormal phospholipid metabolism chain of cyclooxygenase-2/microsomal prostaglandin E 2 synthase-1/prostaglandin E 2 (COX-2/mPGES-1/PGE 2). In clinical practice, non-steroidal anti-inflammatory drugs (NSAIDs) as upstream COX-2 enzyme activity inhibitors are widely used to block COX-2 cascade to relieve inflammatory response. However, NSAIDs could also cause cardiovascular and gastrointestinal side effects due to its inhibition on other prostaglandins generation. To avoid this, targeting downstream mPGES-1 instead of upstream COX is preferable to selectively block overexpressed PGE 2 in inflammatory diseases. Some mPGES-1 inhibitor candidates including synthetic compounds, natural products and existing anti-inflammatory drugs have been proved to be effective in in vitro experiments. After 20 years of in-depth research on mPGES-1 and its inhibitors, ISC 27864 have completed phase II clinical trial. In this review, we intend to summarize mPGES-1 inhibitors focused on their inhibitory specificity with perspectives for future drug development. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Anorexia–cachexia syndrome is a very common symptom observed in individuals affected by chronic inflammatory diseases. The present study was designed to address the possible involvement of the inducible microsomal prostaglandin E synthase-1 (mPGES-1) in the hypopaghia observed during these pathological states. To this end, we used a model of cancer-induced anorexia and we report here that despite the absence of up-regulation of the mPGES-1 enzyme within the brain during anorexia–cachexia syndrome, mPGES-1 knock-out mice exhibit resistance to tumor-induced anorexia and maintain their body mass. [Copyright &y& Elsevier]

Knee osteoarthritis (OA) results, at least in part, from overloading and inflammation leading to cartilage degradation. Prostaglandin E2 (PGE2) is one of the main catabolic factors involved in OA in which metalloproteinase (MMP) is crucial for cartilage degradation. Its synthesis is the result of cyclooxygenase (COX) and prostaglandin E synthase (PGES) activities whereas NAD+-dependent 15 hydroxy-prostaglandin dehydrogenase (15-PGDH) is the key enzyme implicated in the catabolism of PGE2. Among the isoforms described, COX-1 and cytosolic PGES are constitutively expressed whereas COX-2 and microsomal PGES type 1 (mPGES-1) are inducible in an inflammatory context. We investigated the regulation of the COX, PGES and 15-PGDH and MMP-2, MMP-9 and MMP-13 genes by mechanical stress applied to cartilage explants. Mouse cartilage explants were subjected to compression (0.5 Hz, 1 MPa) from 2 to 24 h. After determination of the PGE2 release in the media, mRNA and proteins were extracted directly from the cartilage explants and analyzed by real-time RT-PCR and western blot respectively. Mechanical compression of cartilage explants significantly increased PGE2 production in a time dependent manner. This was not due to the synthesis of IL-1, since pretreatment with IL1-Ra did not alter the PGE2 synthesis. Interestingly, COX-2 and mPGES-1 mRNA expression significantly increased after 2 hours, in parallel with protein expression. Moreover, we observed a delayed overexpression of 15-PGDH just before the decline of PGE2 synthesis after 18 hours suggesting that PGE2 synthesis could be altered by the induction of 15-PGDH expression. MAPK are involved in signaling, since specific inhibitors partially inhibited COX-2 and mPGES-1 expressions. Lastly, compression induced MMP-2, -9, -13 mRNA expressions in cartilage. We conclude that dynamic compression induces pro-inflammatroy mediators release and matrix degradating enzymes synthesis. Notably, compression increases mPGES-1 mRNA and protein expression in cartilage explants. Thus, the mechanosensitive mPGES-1 enzyme represents a potential therapeutic target in osteoarthritis. [ABSTRACT FROM AUTHOR]

Summary: Studies have linked microsomal prostaglandin E synthase (mPGES)–1 with gastric cancer. The purpose of this study was to determine mPGES-1, mPGES-2, and cytosolic PGES (cPGES) expression in gastric cancer and to evaluate the correlation between mPGES-1 and mPGES-2 expression and clinicopathological factors and cyclooxygenase-2 expression. PGES protein expression was examined by Western blot in gastric cancer cell lines and in biopsy samples from patients with gastric cancer. mPGES-1, mPGES-2, and cPGES protein localizations were examined immunohistochemically in 129 archival gastric cancer surgical resections. mPGES-1 protein expression was found in gastric cancer biopsies and cancer cell lines with differentiated or undifferentiated adenocarcinoma. There was no mPGES-1 expression in nonneoplastic biopsies. All cell lines and tissue samples expressed mPGES-2 and cPGES. Immunohistochemical analysis showed cancer cells expressed mPGES-1 in 47% of cases. mPGES-2 immunoreactivity was seen both in nonneoplastic glandular epithelium and cancer cells; however, cancer cell immunoreactivity was significantly more pronounced in 29% of cases. cPGES expression was constitutive both in nonneoplastic and neoplastic tissues, with no significant variation among cases. mPGES-1 and mPGES-2 expression correlated with cyclooxygenase-2 expression. mPGES-1 and mPGES-2 expression, and tumor-node-metastasis stage had independent prognostic significance under multivariate analysis in patients with gastric cancer overall and in patients with differentiated cancers. However, only tumor-node-metastasis stage and mPGES-2 expression retained independent prognostic significance in patients with poorly differentiated cancers. mPGES-1 and mPGES-2 correlate with clinicopathological factors and may be valuable prognostic factors in gastric cancer. [Copyright &y& Elsevier]

Abstract: The aim of the present study was to investigate the impact of the deletion of the microsomal prostaglandin E synthase-1 (mPGES-1) gene on lipopolysaccharide (LPS)-induced neuronal activation in central nervous structures. The mPGES-1 catalyses the conversion of COX-derived PGH2 to PGE2 and has been described as a regulated enzyme whose expression is stimulated by proinflammatory agents. Using the immediate-early gene c-fos as a marker of neuronal activation, we determined whether deletion of the mPGES-1 gene altered the neuronal activation induced by LPS in structures classically recognized as immunosensitive regions. No significant difference in the c-Fos immunostaining was observed in the brain of saline-treated mPGES-1+/+, mPGES-1+/− and mPGES-1−/− mice. However, we observed that LPS-induced neuronal activation was reduced in most of the centres known as immunosensitive nuclei in mPGES-1−/− mice compared with heterozygous and wild-type mice. The decrease in the number of c-Fos positive nuclei occurred particularly in the caudal ventrolateral medulla, the medial, intermediate and central parts of the nucleus tractus solitarius, area postrema, parabrachial nucleus, locus coeruleus, paraventricular nucleus of the hypothalamus, ventromedial preoptic area, central amygdala, bed nucleus of the stria terminalis and to a lesser extent in the ventrolateral part of the nucleus tractus solitarius and rostral ventrolateral medulla. These results suggest that the mPGES-1 enzyme is strongly needed to provide sufficient PGE2 production required to stimulate immunosensitive brain regions and they are discussed with regard to the recent works reporting impaired sickness behavior in mPGES-1−/− mice. [Copyright &y& Elsevier]

PGE2 is involved in initiation and progression of labor in many species. Biosynthesis of PGE2 is mediated by cyclooxygenases (COX) and prostaglandin E synthases (PGES). mPGES-1 and COX-2 form an inducible pathway for PGE2 production in many cell systems. In this study we investigated whether mPGES-1 is involved in cytokine induced PGE2 biosynthesis in human trophoblast cells. We have evaluated the cellular and intracellular co-localization of mPGES-1 and COX-2, as well as cPGES and COX-1 in human trophoblast cells by dual immunofluorescent staining. The effect of IL-1β on mPGES-1 and COX-2 co-localization, such as would occur with infection, and the regulatory effects of pro-inflammatory cytokines IL-1β and TNF-α on transcriptional activity of mPGES-1 and COX-2 in these cells were also studied. We found that in cultured unstimulated trophoblasts, some cells expressed predominantly either mPGES-1 or COX-2, though there were cells co-expressing both enzymes. With IL-1β treatment, mPGES-1 and COX-2 became more consistently co-localized. mPGES-1 was not transcriptionally co-induced with COX-2 by the cytokine treatment. We conclude that mPGES-1 is not involved in the inducible COX-2 mediated pathway for PGE2 biosynthesis at the transcriptional level, however, the treatment with IL-1β results in a higher degree of co-ordination of the mPGES-1 and COX-2 protein immunolocalization, eliciting PGE2 synthesis. [Copyright &y& Elsevier]

Cyclooxygenase-2 (COX-2), the rate-limiting enzyme for prostanoid biosynthesis, plays a key role in gastrointestinal carcinogenesis. Among various prostanoids, prostaglandin E2 (PGE2) appears to be most responsible for cancer development. To investigate the role of PGE2 in gastric tumorigenesis, we constructed transgenic mice simultaneously expressing COX-2 and microsomal prostaglandin E synthase (mPGES)-1 in the gastric epithelial cells. The transgenic mice developed metaplasia, hyperplasia and tumorous growths in the glandular stomach with heavy macrophage infiltrations. Although gastric bacterial counts in the transgenic mice were within the normal range, treatment with antibiotics significantly suppressed activation of the macrophages and tumorous hyperplasia. Importantly, the antibiotics treatment did not affect the macrophage accumulation. Notably, treatment of the transgenic mice with lipopolysaccharides induced proinflammatory cytokines through Toll-like receptor 4 in the gastric epithelial cells. These results indicate that an increased level of PGE2 enhances macrophage infiltration, and that they are activated through epithelial cells by the gastric flora, resulting in gastric metaplasia and tumorous growth. Furthermore, Helicobacter infection upregulated epithelial PGE2 production, suggesting that the COX-2/mPGES-1 pathway contributes to the Helicobacter-associated gastric tumorigenesis. [ABSTRACT FROM AUTHOR]

Over the past two decades the interest has waned in therapeutically targeting cyclooxygenase-2 (COX-2) due to growing concerns over the potential cardiovascular and cerebrovascular toxicities of the long-term use of COX-2 inhibitors. Attention thus has recently been shifted downstream to the prostaglandin signaling pathways for new druggable anti-inflammatory targets aiming for higher therapeutic specificity. Prostaglandin E2 (PGE 2) is robustly synthesized in the ischemic cortex by quickly induced COX-2 and microsomal prostaglandin E synthase-1 (mPGES-1) following cerebral ischemia. The elevated PGE 2 , in turn, divergently regulates the excitotoxic injury and neuroinflammation by acting on four membrane-bound G protein-coupled receptors (GPCRs), namely, EP1-EP4. Markedly, all four EP receptors have been implicated in the excitotoxicity-associated brain inflammation and injury in animal models of cerebral ischemia. However promising, these preclinical studies have not yet led to a clinical trial targeting any PGE 2 receptor for ischemic stroke. The goal of this article is to review the recent progress in understanding the pathogenic roles of PGE 2 in cerebral ischemia as well as to provide new mechanistic insights into the PGE 2 signaling via these four GPCRs in neuronal excitotoxicity and inflammation. We also discuss the feasibility of targeting EP1-EP4 receptors as an emerging delayed treatment, together with the first-line reperfusion strategy, to manage acute ischemic stroke with potentially extended window as well as improved specificity. [ABSTRACT FROM AUTHOR]

• PGE2 may play a prominent role in BCa. • PGE2 is involved in tumor growth, cisplatin resistance, and immunosuppression. • Clinical trials have had mixed results with efficacy. • Trials combining PGE2 inhibition and immunosuppression or chemotherapy are warranted. • Novel therapeutics and biomarkers of efficacy are needed to reduce PGE2 levels. Bladder cancer (BCa) is a common solid tumor marked by high rates of recurrence, especially in non-muscle invasive disease. Prostaglandin E 2 (PGE 2) is a ubiquitously present lipid mediator responsible for numerous physiological actions. Inhibition of cyclooxygenase (COX) enzymes by the non-steroidal anti-inflammatory (NSAID) class of drugs results in reduced PGE 2 levels. NSAID usage has been associated with reductions in cancers such as BCa. Clinical trials using NSAIDs to prevent recurrence have had mixed results, but largely converge on issues with cardiotoxicity. The purpose of this review is to understand the basic science behind how and why inhibitors of PGE 2 may be effective against BCa, and to explore alternate therapeutic modalities for addressing the role of PGE 2 without the associated cardiotoxicity. We will address the role of PGE 2 in a diverse array of cancer-related functions including stemness, immunosuppression, proliferation, cellular signaling and more. [ABSTRACT FROM AUTHOR]