Expression Of Microsomal Prostaglandin Research Articles

PGE2 pathway mediates oxidative stress-induced ferroptosis in renal tubular epithelial cells.

Prostaglandin E2 (PGE2) is one of the most abundant prostaglandins and has been implicated in various diseases. Here, we aimed to explore the role of the PGE2 pathway in mediating ferroptosis during acute kidney injury. When renal tubular epithelial cells stimulated by H2 O2 , the contents of glutathione (GSH) and glutathione peroxidase 4 (GPX4) decreased, whereas the level of lipid peroxide increased. Ferrostatin-1 can effectively attenuate these changes. In this process, the expression levels of cyclooxygenase (COX)-1 and COX-2 were up-regulated. Meanwhile, the expression of microsomal prostaglandin E synthase-2 was elevated, whereas the expression of microsomal prostaglandin E synthase-1 and cytosolic prostaglandin E synthase were down-regulated. Furthermore, the expression of 15-hydroxyprostaglandin dehydrogenase decreased. An excessive accumulation of PGE2 promoted ferroptosis, whereas the PGE2 inhibitor pranoprofen minimized the changes for COX-2, GSH, GPX4 and lipid peroxides. A decrease in the levels of the PGE2 receptor E-series of prostaglandin 1/3 partially restored the decline of GSH and GPX4 levels and inhibited the aggravation of lipid peroxide. Consistent with the in vitro results, increased PGE2 levels led to increased levels of 3,4-methylenedioxyamphetamine, Fe2+ accumulation and decreased GSH and GPX4 levels during renal ischaemia/reperfusion injury injury in mice. Our results indicate that the PGE2 pathway mediated oxidative stress-induced ferroptosis in renal tubular epithelial cells.

Different effects of strength and endurance exercise training on COX-2 and mPGES expression in mouse brain are independent of peripheral inflammation.

Acute endurance exercise has been shown to modulate cyclooxygenase (COX)-2 expression, which is suggested to affect neuronal plasticity and learning. Here, we investigated the effect of regular strength and endurance training on cerebral COX-2 expression, inflammatory markers in the brain, and circulating cytokines. Male C57BL/6N mice were assigned to either a sedentary control group (CG), an endurance training group (EG; treadmill running for 30 min/day, 5 times/wk, 10 wk), or a strength training group (SG; strength training by isometric holding, same duration as EG). Four days after the last bout of exercise, blood and brain were collected and analyzed using real-time PCR, Western blot, and a multiplexed immunoassay. In EG, COX-2 mRNA expression in the cortex/hippocampus increased compared with CG. A significant increase of COX-2 protein levels was observed in both cortex/hippocampus and hypothalamus of mice from the SG. Nuclear factor (NF)κB protein levels were significantly increased in mice from both exercise groups (hypothalamus). A significant increase in the expression of microsomal prostaglandin E synthase (mPGES), an enzyme downstream of COX-2, was found in the hypothalamus of both the EG and SG. While most inflammatory factors, like IL-1α, IL-18, and IL-2, decreased after training, a positive association was found between COX-2 mRNA expression (cortex/hippocampus) and plasma IL-6 in the EG. Taken together, this study demonstrates that both endurance as well as strength training induces COX-2 expression in the cortex/hippocampus and hypothalamus of mice. A potential mediator of COX-2 expression after training might be circulating interleukin (IL)-6. However, further research is necessary to elucidate the role of inflammatory pathways on brain plasticity after training.

Abstract 1632: Microsomal prostaglandin E synthase 1: a novel therapeutic target of neuroblastoma

Abstract Background: Tumor promoting inflammation is important for Neuroblastoma development and progression. We have previously shown that the inflammatory prostaglandin E2 (PGE2) acts as an autocrine survival factor in NB and that high expression of microsomal prostaglandin E synthase-1 (mPGES-1), essential for PGE2 synthesis, is coupled to poor clinical outcome in high risk NB. We have also shown that mPGES-1 promotes growth and survival of several malignancies. In this study we investigate the impact of specific PGE2 targeting in NB by using a novel mPGES-1 inhibitor in vivo. Methods: The in vivo effect of the mPGES-1 inhibitor on tumor growth was carried out using the MYCN driven transgenic mouse model that spontaneously develops an aggressive form of neuroblastoma (tg TH-MYCN model). Protein and mRNA expression of mPGES-1 and the COX enzymes in the tumors was determined by immunohistochemistry (IHC) and RT-qPCR. Infiltration and polarization of macrophages in treated and nontreated tumors was assessed by IHC using the PAN-marker F4/80 and the M2 polarized macrophage marker CD206. The effect of mPGES-1 inhibition on angiogenesis was determined by IHC by using the endothelial marker CD31. Results: Expression of mPGES-1 and COX-1 could be detected in tumours from the tg TH-MYCN model. By treating the animals with the mPGES-1 inhibitor we could significantly delay the tumor growth with reduced tumor weights at sacrifice compared to tumors from untreated control animals. To study the effect of inflammation we analyzed macrophage abundance and polarization in the treated and untreated tumors. There was no diffrence in the total level of macrophage infiltration while a significant decrese of M2 polarized macrophages was seen in the treated tumors. Furthermore, mPGES-1 inhibition significantly reduced angiogenesis in the tumors. Conclusion: Our results demonstrate that specific PGE2 inhibition by targeting mPGES-1 is a way of reducing NB growth. Note: This abstract was not presented at the meeting. Citation Format: Anna Kock, Karin Larsson, Raouf Joan, Marina Korotkova, John-Inge Johnsen, Per-Johan Jakobsson, Per Kogner. Microsomal prostaglandin E synthase 1: a novel therapeutic target of neuroblastoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1632. doi:10.1158/1538-7445.AM2015-1632

Abstract 1666: Suppression of cyclooxygenase-2 by dual-specificity phosphatase-2 ameilorates cancer malignancy

Abstract Aberrant production of cyclooxygenase-2 (COX-2) and COX-2-derived prostaglandin E2 (PGE2) have been demonstrated to contribute to tumor development and malignancy in many human cancers. However, the initiating factor responsible for maintaining high levels of COX-2 expression during cancer development remains enigmatic. We hypothesize that aberrant expression of COX-2 in cancer cells is initiated by hypoxia, a common phenomenon occurs in very early stage during cancer development. Herein, we present data demonstrating that levels of COX-2 in cancer cells are induced by hypoxia in a hypoxia-inducible factor-1α (HIF-1α)-dependent manner. Intriguingly, HIF-1α does not directly induce COX-2 promoter activity. In contrast, induction of COX-2 expression is mediated by HIF-1α-induced downregulation of dual specificity phosphatase-2 (DUSP-2), a MAPK-specific phosphatase. Forced expression of DUSP2 reduces the levels of COX-2, while knockdown of DUSP2 induces COX-2 expression in cancer cells. Moreover, depletion of DUSP2 also induces the expression of microsomal prostaglandin E synthase (mPGES) and consequently increases the production of PGE2. Further study reveals that re-induction of DUSP2 abolishes hypoxia-induced COX-2 expression and PGE2 production. To test the hypothesis that COX-2 mediates loss-of-DUSP2-induced tumorigenesis, a selective COX-2 inhibitor, NS-398, was used to block the function of COX-2 in the DUSP2-knockdown xenograft mouse model. Knockdown of DUSP2 markedly enhances tumor growth while treatment with NS-398 reverses loss-of-DUSP2-induced tumor development in vivo. Taken together, our data indicate that DUSP2, a negative regulator of COX-2, plays a critical tumor suppressive role and hypoxia, a common stress during cancer development, suppresses DUSP2 to initiate COX-2 overexpression and promote cancer progression. Our findings suggest that preventing DUSP2 from hypoxia-mediated downregulation or re-induction of DUSP2 during cancer development may represent a potential approach for cancer therapy. Citation Format: Yo-Hua Li, Shih-Chieh Lin, Shaw-Jenq Tsai. Suppression of cyclooxygenase-2 by dual-specificity phosphatase-2 ameilorates cancer malignancy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1666. doi:10.1158/1538-7445.AM2014-1666

Expression of Microsomal Prostaglandin E Synthase-1 in the Spinal Cord in a Transgenic Mouse Model of Amyotrophic Lateral Sclerosis

Prostaglandin E2 (PGE2) is a key molecule involved in the neuroinflammatory processes that characterize amyotrophic lateral sclerosis (ALS). Although PGE2 synthesis is regulated by PGE2 synthases (PGESs), the pathological role of PGESs in ALS still remains unknown. Experiments were performed to elucidate the expression of PGESs and the localization of microsomal PGES-1 (mPGES-1) in neurons and glial cells in the spinal cord of ALS model (G93A) mice. Neurological symptom was observed in G93A mice from 14 weeks by the tail suspension test, and rotarod performances were decreased at 16 weeks and older. Western blotting revealed that the level of mPGES-1 was increased in G93A mice at 15 weeks and older. In contrast, the levels of cytosolic PGES and mPGES-2 did not change at any age. Immunohistochemical analysis demonstrated that age-dependent expression of mPGES-1 was found in motor neurons in G93A mice at 11 and 15 weeks. Immunoreactivity of mPGES-1 was also co-localized in Iba1-positive microglia in G93A mice at 15 weeks. These results suggest that mPGES-1 in motor neurons may play a role in the pathogenesis of ALS and that mPGES-1 may work sequentially in motor neurons and activated microglia to produce ALS symptoms in G93A mice.

A selective cyclooxygenase‐2 inhibitor prevents inflammation‐related squamous cell carcinogenesis of the forestomach via duodenogastric reflux in rats

Duodenal reflux causes inflammation-related squamous cell carcinogenesis in the forestomach of rats without any carcinogens. The aim of this study was to investigate the efficacy of a selective cyclooxygenase (COX)-2 inhibitor, meloxicam, in preventing this carcinogenesis. A series of 188 rats underwent a surgical duodenogastric reflux procedure and were divided into 2 groups. One group was given commercial chow (control group), and the other was given experimental chow containing meloxicam (0.3 mg/kg body weight/day) (meloxicam group). The animals were sequentially sacrificed at Weeks 20, 30, 40, 50, and 60 after surgery. The forestomach was examined for the presence of carcinoma, the incidence of reflux-related morphological changes, COX-2 expression, and its activity. At Week 60, squamous cell carcinoma developed in 8 of 21 animals (38%) in the control group, but none of 20 (0%) in the meloxicam group (P<.05). In addition, basal cell dysplasia developed in 19 of 21 (90%) animals in the control group, but only 4 of 20 (20%) in the meloxicam group (P<.01). COX-2 immunoreactivity was predominantly detected in macrophages in the epithelial stroma. Compared with nonsurgical rats, RNA expression of COX-2 in the epithelium was up-regulated, reaching peak at an early stage of Week 20 in both groups (P<.005). The expression of microsomal prostaglandin E synthase-1 was lower in the meloxicam group than in the control group. PGE2 production was significantly suppressed throughout the experiment in the meloxicam group compared with the control group (P<.005). Meloxicam was effective in preventing reflux-induced squamous cell carcinogenesis via an inflamed squamous epithelium.

Expression of Microsomal Prostaglandin E Synthase-1 in Fibroblasts of Rabbit Alkali-Burned Corneas

Prostaglandin E2 is related to wound healing. Three different prostaglandin E synthases have been identified: microsomal prostaglandin E synthase (mPGES)-1, mPGES-2, and cytosolic prostaglandin E synthase. This study examined mPGES-1 expression in the cornea during the reparative process that occurs after an alkali burn. mPGES-1 messenger RNA (mRNA) and protein expression levels were examined by reverse transcription-polymerase chain reaction and Western blot analysis. Localization of mPGES-1 mRNA was examined by in situ hybridization. Using immunostaining, the localization of mPGES-1, cyclooxygenase (COX)-2, and alpha-smooth muscle actin (alpha-SMA) protein was studied. Although mPGES-1 mRNA is expressed in normal cornea, after a corneal injury, a progressive increase of mPGES-1 mRNA occurs. In this study, 2-6 weeks after injury, mPGES-1 mRNA was detected in the stromal spindle cells. Western blot analysis also showed that mPGES-1 protein expression was observed in normal cornea, with an increase noted from 2 to 4 weeks after corneal injury. mPGES-1 immunoreactivity was negative in normal cornea; however, starting at 2 weeks after injury, positive staining of the stromal spindle cells was noted. Although COX-2 and alpha-SMA immunoreactivities were negative in the stroma of normal cornea, after injury, staining was observed in the stromal spindle cells. alpha-SMA-positive cells and myofibroblasts express mPGES-1 mRNA and protein, and in addition, mPGES-1 colocalized with COX-2, suggesting that myofibroblasts synthesize prostaglandin E2 and may act on and accelerate corneal wound healing.

Association between adenomatosis polyposis coli functional status and microsomal prostaglandin E synthase‐1 expression in colorectal cancer

Bioactive metabolites downstream of cyclooxygenase-2 (COX-2) generated prostaglandin H(2) (PGH(2)), in particular prostaglandin E(2) (PGE(2)), are thought to play critical roles during the development of colorectal tumors. Previous reports reveal that defects of the tumor suppressor adenomatosis polyposis coli (APC) contribute to COX-2 upregulation in colon tumor cells. We investigated whether a similar relation was present between APC functional status and the expression of microsomal prostaglandin E synthase-1 (mPGES-1), which acts downstream of COX-2 and catalyses the terminal conversion of PGH(2) into PGE(2). Surprisingly, mPGES-1 mRNA and protein levels were upregulated upon induction of a wild type-APC carrying vector in HT29 colon cancer cells, and downregulated following siRNA silencing of APC in HCT-116 cells. mPGES-1 was overall enhanced in human colorectal tumor specimens versus corresponding non-tumor mucosa and, in accordance with data on HT29 and HCT116 cells, higher levels of mPGES-1 were observed among tumors carrying wild type versus mutant APC. RNAi silencing of beta-catenin and luciferase assays regarding the mPGES-1 promoter region did not reveal a role for APC or beta-catenin/Tcf in controlling mPGES-1 gene transcription. However, RNA degradation assays in HT29 cells revealed a suppressed degradation of mPGES-1 in the presence of wild type APC, implying that mPGES-1 mRNA is stabilized in the APC wild type state. Collectively, we demonstrate a novel association between APC functional status and mPGES-1 expression in colorectal tumor cells, being most likely related to reduced mPGES-1 mRNA degradation rate in the APC wild type state.

Chemoprevention of glandular stomach carcinogenesis through duodenogastric reflux in rats by a COX‐2 inhibitor

Duodenogastric reflux (DGR) causes glandular stomach carcinogenesis in rats without carcinogens. We aimed to investigate how this carcinogenesis might be prevented by a selective COX-2 inhibitor, meloxicam. A series of 188 Fisher 344 rats underwent a surgical DGR procedure and were divided into 2 groups. One group was given commercial chow (control group), and the other an experimental chow containing meloxicam [0.3 mg/kg bw/day] (meloxicam group). The animals were sequentially sacrificed at weeks 20, 30, 40, 50 and 60 after surgery. The stomachs were removed and examined for the presence of carcinoma, incidence of reflux-induced morphologic changes, COX-2 expression and its activity. Adenocarcinoma in the glandular stomach developed in 7 of 21 animals (33%) in the control group at week 60, but none of 20 (0%) in the meloxicam group (p < 0.01). Moreover, reflux-induced gastritis was definitely alleviated in the meloxicam group compared with the control group. COX-2 immunoreactivity was predominantly detected in stromal cells such as macrophages and fibroblasts. Compared with nonsurgical rats, RNA expression of COX-2 in the mucosa increased, reaching peak at an early phase of week 20 in both groups (p < 0.005). Expression of microsomal prostaglandin E synthase-1 was lower in the meloxicam group than in the control group. PGE(2) production was significantly suppressed throughout the experiment in the meloxicam group compared with the control group (p < 0.01). Gastric carcinogenesis via duodenal reflux was mediated by the COX-2 pathway in rats. Administration of meloxicam prevented this carcinogenesis by suppressing the inflammatory process.

Neuroprotective role of bradykinin because of the attenuation of pro‐inflammatory cytokine release from activated microglia

Bradykinin (BK) has been reported to be a mediator of brain damage in acute insults. Receptors for BK have been identified on microglia, the pathologic sensors of the brain. Here, we report that BK attenuated lipopolysaccharide (LPS)-induced release of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta from microglial cells, thus acting as an anti-inflammatory mediator in the brain. This effect was mimicked by raising intracellular cAMP or stimulating the prostanoid receptors EP2 and EP4, while it was abolished by a cAMP antagonist, a prostanoid receptor antagonist, or by an inhibitor of the inducible cyclooxygenase (cyclooxygenase-2). BK also enhanced formation of prostaglandin E(2) and expression of microsomal prostaglandin E synthase. Expression of BK receptors and EP2/EP4 receptors were also enhanced. Using physiological techniques, we identified functional BK receptors not only in culture, but also in microglia from acute brain slices. BK reduced LPS-induced neuronal death in neuron-microglia co-cultures. This was probably mediated via microglia as it did not affect TNF-alpha-induced neuronal death in pure neuronal cultures. Our data imply that BK has anti-inflammatory and neuroprotective effects in the central nervous system by modulating microglial function.

Expression of microsomal prostaglandin E synthase-1 in muscle tissue of patients with idiopathic inflammatory myopathies

Expression of microsomal prostaglandin E synthase-1 in muscle tissue of patients with idiopathic inflammatory myopathies

Effects of anti-rheumatic treatments on expression of microsomal prostaglandin E synthase-1 in rheumatoid arthritis synovium

Effects of anti-rheumatic treatments on expression of microsomal prostaglandin E synthase-1 in rheumatoid arthritis synovium

Expression of Microsomal Prostaglandin E Synthase in Bovine Endometrium: Coexpression with Cyclooxygenase Type 2 and Regulation by Interferon-

Prostaglandins (PGs) are important regulators of reproductive functions. In ruminants, interferon (IFN)-τ is the embryonic signal responsible for recognition of pregnancy. This is effected by a reduction of the production of PGF2α relative to PGE2. This may be accomplished by a decrease in PGF2α production, but a stimulation of PGE2 via the PGE synthase might also be involved. The purpose of the present study was to confirm the presence of PGE synthase (PGES) in the bovine endometrium, identify the factors affecting its expression, and compare it with that of cyclooxygenase-2 (COX-2). This was done by Northern blot analysis using primary cultures of bovine epithelial and stromal cells of the endometrium and bovine endometrial cell line. PGES mRNA expression was increased in the presence of lipopolysaccharides, TNF-α, and IFN-τ in stromal cells and IFN-τ in epithelial cells. In stromal cells, IFN-τ induced a rapid increase of PGES and COX-2 mRNA expression. In bovine endometrial cells, phorbol 12-myristate 13-actetate increased PGES mRNA, COX-2 mRNA and PGE2 production. These results suggest that in endometrial cells, the expression of PGE synthase is correlated with that of COX-2 and is an important enzyme for the production of PGE2. Increasing this production will modulate the PGE2/PGF2α ratio and contribute to establishment of pregnancy.

Expression of microsomal prostaglandin E synthase in bovine endometrium: coexpression with cyclooxygenase type 2 and regulation by interferon-tau.

Prostaglandins (PGs) are important regulators of reproductive functions. In ruminants, interferon (IFN)-tau is the embryonic signal responsible for recognition of pregnancy. This is effected by a reduction of the production of PGF(2alpha) relative to PGE(2.) This may be accomplished by a decrease in PGF(2alpha) production, but a stimulation of PGE(2) via the PGE synthase might also be involved. The purpose of the present study was to confirm the presence of PGE synthase (PGES) in the bovine endometrium, identify the factors affecting its expression, and compare it with that of cyclooxygenase-2 (COX-2). This was done by Northern blot analysis using primary cultures of bovine epithelial and stromal cells of the endometrium and bovine endometrial cell line. PGES mRNA expression was increased in the presence of lipopolysaccharides, TNF-alpha, and IFN-tau in stromal cells and IFN-tau in epithelial cells. In stromal cells, IFN-tau induced a rapid increase of PGES and COX-2 mRNA expression. In bovine endometrial cells, phorbol 12-myristate 13-actetate increased PGES mRNA, COX-2 mRNA and PGE(2) production. These results suggest that in endometrial cells, the expression of PGE synthase is correlated with that of COX-2 and is an important enzyme for the production of PGE(2). Increasing this production will modulate the PGE(2)/PGF(2alpha) ratio and contribute to establishment of pregnancy.