Expression Of Prostaglandin E2 Synthase Research Articles

ARID1A, Prostaglandin E2, and Its Receptor as Possible Predictors of Malignant Transformation of the Endometrium in Endometriosis.

We studied the expression of ARID1A, prostaglandin E2 synthase, and prostaglandin E2 receptor in the endometrium and ovarian, peritoneal, and intestinal endometrioid heterotopies in women with endometriosis of young and middle reproductive age. ARID1A protein is a tumor suppressor, its expression reduced in different types of cancer. Prostaglandin E2 synthase and prostaglandin E2 receptor are involved in the signaling cascade of inflammatory reactions presumably underlying the development of endometriosis. In endometrioid heterotopies, expression of ARID1A was reduced in 1.2-4.0 times, the expression of prostaglandin E2 synthase and prostaglandin E2 receptor was reduced in 2.9-5.2 times These findings suggest that ARID1A, prostaglandin E2 synthase, and prostaglandin E2 receptor can be used as predictors of malignant transformation of endometrioid heterotopies in women with endometriosis.

Coupling of oxidative stress responses to tricarboxylic acid cycle and prostaglandin E2 alterations in Caenorhabditis elegans under extremely low-frequency electromagnetic field

Purpose: With all-pervasive presence of extremely low-frequency electromagnetic field (ELF-EMF) in modern life, ELF-EMF has been regarded as an essential factor which may induce changes in many organisms. The objective of the present study was to investigate the physiological responses of Caenorhabditis elegans (C. elegans) to 50 Hz, 3 mT ELF-EMF exposure.Materials and methods: Worms were exposed to ELF-EMF from the egg stage until reaching the fourth larva (L4) stage. After exposure, expressions of the tricarboxylic acid (TCA) cycle enzymes were examined by qRT-PCR and western blot analysis. Two lipid metabolites were detected by GC-MS. Reactive oxygen species (ROS) level was detected by dichlorofluorescein staining and worm antioxidant system was investigated by enzymatic activity analysis, including detection of the superoxide dismutase and catalase (CAT) activity and the total antioxidant capacity (T-AOC).Results: The TCA cycle enzyme, fumarase was found with decreased expression under ELF-EMF exposure. And arachidonic acid (ArA) and prostaglandin E2(PGE2) showed elevated concentrations, with increased expression of prostaglandin E2 synthase (PGES-2) in ELF-EMF exposed worms. Significant elevation of ROS level was identified accompanied with the significant depression of T-AOC in response to ELF-EMF.Conclusions: Our results suggested that exposure to 50 Hz, 3 mT ELF-EMF in C. elegans can elicit disruptions of the TCA cycle metabolism and PGE2 formation, coupling ELF-EMF-induced oxidative stress responses. Our study probably will attract increasing attentions to the controllable application of ELF-EMF associated with health and disease.

Formation of the early canine CL and the role of prostaglandin E2 (PGE2) in regulation of its function: An in vivo approach

The mechanisms governing corpus luteum (CL) function in domestic dogs remain not fully elucidated. The upregulated expression of cyclooxygenase 2 and prostaglandin (PG) E2 synthase (PGES) at the beginning of the canine luteal phase indicated their luteotrophic roles, and the steroidogenic activity of PGE2 in the early canine CL has been confirmed in vitro. Recently, by applying a cyclooxygenase 2 (COX2)-specific inhibitor (firocoxib [Previcox]; Merial) from the day of ovulation until the midluteal phase, the luteotrophic effects of PGs have been shown in vivo. This is a follow-up study investigating the underlying endocrine mechanisms associated with the firocoxib-mediated effects on the canine CL. Experimental groups were formed with ovariohysterectomies performed on Days 5, 10, 20, or 30 of firocoxib treatments (10 mg/kg bw/24h; TGs = treated groups). Untreated dogs served as controls. A decrease of steroidogenic acute regulatory (STAR) protein expression was observed in TGs. The expression of PGE2 synthase was significantly suppressed in TGs 5 and 10, and both PGE2 and PGF2α levels were decreased in luteal homogenates, particularly from CL in TG 5. Similarly, expression of the prolactin receptor (PRLR) was diminished in TGs 5 and 20. The expression of PGE2 receptors PTGER2 (EP2) and PTGER4 (EP4), the PG- transporter (PGT), and 15-hydroxy PG dehydrogenase (HPGD) was not affected in TGs. Our results substantiate a direct luteotrophic role of PGs in the early canine CL, i.e., by upregulating the steroidogenic machinery. Additionally, the possibility of an indirect effect on PRL function arises from the increased prolactin receptor expression in response to PGE2 treatment in canine lutein cells observed in vitro.

Role of the prostaglandin E2/E-prostanoid 2 receptor signalling pathway in TGFβ-induced mice mesangial cell damage.

The prostaglandin E2 receptor, EP2 (E-prostanoid 2), plays an important role in mice glomerular MCs (mesangial cells) damage induced by TGFβ1 (transforming growth factor-β1); however, the molecular mechanisms for this remain unknown. The present study examined the role of the EP2 signalling pathway in TGFβ1-induced MCs proliferation, ECM (extracellular matrix) accumulation and expression of PGES (prostaglandin E2 synthase). We generated primary mice MCs. Results showed MCs proliferation promoted by TGFβ1 were increased; however, the production of cAMP and PGE2 (prostaglandin E2) was decreased. EP2 deficiency in these MCs augmented FN (fibronectin), Col I (collagen type I), COX2 (cyclooxygenase-2), mPGES-1 (membrane-associated prostaglandin E1), CTGF (connective tissue growth factor) and CyclinD1 expression stimulated by TGFβ1. Silencing of EP2 also strengthened TGFβ1-induced p38MAPK (mitogen-activated protein kinase), ERK1/2 (extracellular-signal-regulated kinase 1/2) and CREB1 (cAMP responsive element-binding protein 1) phosphorylation. In contrast, Adenovirus-mediated EP2 overexpression reversed the effects of EP2-siRNA (small interfering RNA). Collectively, the investigation indicates that EP2 may block p38MAPK, ERK1/2 and CREB1 phosphorylation via activation of cAMP production and stimulation of PGE2 through EP2 receptors which prevent TGFβ1-induced MCs damage. Our findings also suggest that pharmacological targeting of EP2 receptors may provide new inroads to antagonize the damage induced by TGFβ1.

Prostaglandin E2 EP1 receptor enhances TGF-β1-induced mesangial cell injury.

Increasing evidence indicates that transforming growth factor-β1 (TGF-β1) is a pivotal mediator in the pathogenesis of renal fibrosis. Mesangial cells (MCs) are important for glomerular function under both physiological and pathological conditions. Studies have found that the expression level of prostaglandin E2 (PGE2) in MCs increases under high glucose conditions, that PGE2 affects the proliferation and hypertrophy of MCs mainly through the EP1 pathway, and that the proliferation of MCs and the accumulation of extracellular matrix are the main events leading to glomerular fibrosis. In this study, we investigated the effects and mechanisms of action of the EP1 receptor, which is induced by transforming growth factor (TGF)-β1, on the proliferation of mouse MCs, the accumulation of extracellular matrix and the expression of PGE2 synthase. Primary mouse glomerular MCs were isolated from EP1 receptor-deficient mice (EP1-/- mice, in which the EP1 receptor was knocked down) and wild-type (WT) mice (WT MCs). In our preliminary experiments, we found that cell proliferation, as well as the mRNA and protein expression of cyclin D1, proliferating cell nuclear antigen (PCNA), fibronectin (FN), collagen I (ColI), membrane-associated PGE2 synthase-1 (mPGES-1) and cyclooxygenase-2 (COX-2) in the WT MCs were significantly increased following treatment with 10 ng/ml TGF-β1 for 24 h. Compared with the WT MCs, following the knockdown of the EP1 gene, the TGF-β1-induced MC injury was markedly suppressed. The aforementioned changes were notably enhanced following treatment with the EP1 agonist, 17-phenyl trinor PGE2 ethyl amide. Additionally, TGF-β1 induced extracellular signal-regulated kinase (ERK) phosphorylation. We found that the TGF-β1-induced ERK phosphorylation was alleviated by EP1 knockdown and promoted by EP1 expression. These results suggest that the EP1 receptor plays a role in the proliferation of mouse MCs, in the accumulation of extracellular matrix and in the expression of mPGES-1 induced by TGF-β1. Its mechanisms of action are possibly related to the reinforcement of ERK phosphorylation.

Oxytocin and tumor necrosis factor α stimulate expression of prostaglandin E2 synthase and secretion of prostaglandin E2 by luminal epithelial cells of the porcine endometrium during early pregnancy

Oxytocin (OXT) and tumor necrosis factor α (TNF) have been implicated in the control of luteolysis by stimulating endometrial secretion of luteolytic prostaglandin F(2α) (PGF(2α)). Nevertheless, OXT concentration in porcine uterine lumen increases markedly on days 11-12 of pregnancy, and TNF is expressed in endometrium during pregnancy. The objective of the study was to determine the effect of OXT and TNF on expression of the enzymes involved in PG synthesis: PG-endoperoxide synthase 2 (PTGS2), PGE(2) synthase (mPGES-1) and PGF synthase, and PGE(2) receptor (PTGER2), as well as on PG secretion by endometrial luminal epithelial cells (LECs) on days 11-12 of the estrous cycle and pregnancy. LECs isolated from gilts on days 11-12 of the estrous cycle (n=8) and pregnancy (n=7) were treated with OXT (100 nmol/l) and TNF (0.6 nmol/l) for 24 h. OXT increased PTGS2 mRNA and mPGES-1 protein contents, as well as PGE(2) secretion but only on days 11-12 of pregnancy. TNF stimulated PTGS2 and mPGES-1 mRNA, as well as mPGES-1 protein expression and PGE(2) release on days 11-12 of pregnancy and the estrous cycle. In addition, expressions of PTGER2 and PTGER4 were determined in corpus luteum (CL). Abundance of PTGER2 mRNA and PTGER4 protein in CL was upregulated on day 14 of pregnancy versus day 14 of the estrous cycle. This study indicates that TNF and OXT regulate PGE(2) synthesis in LECs during early pregnancy. PGE(2) secreted by LECs, after reaching ovaries, could have a luteoprotective effect through luteal PTGER2 and PTGER4, or may directly promote uterine function and conceptus development.

Impaired expression of prostaglandin E2 synthesis and degradation enzymes in urothelial cells from patients with interstitial cystitis.

The differentiated superficial cells of the urothelium restrict urine flow into the bladder wall. We have demonstrated that urothelial cells isolated from bladders of patients with interstitial cystitis (IC) fail to release PGE2 in response to tryptase. We measured protein expression of 15‐hydroxyprostaglandin dehydrogenase (PGDH), cyclooxygenase‐2 (COX‐2) and prostaglandin E2 synthase (PGES) in immortalized urothelial cells isolated from the bladders of IC patients (SR22A, SM28) or normal subjects (PD07i, PD08i) during differentiation produced by increased calcium and fetal bovine serum in the culture medium for 1, 3 and 7 days. PGES expression increased during differentiation in normal and IC urothelial cells. COX‐2 expression also increased in cells from normal patients following differentiation. Remarkably, no COX‐2 expression was detectable in IC cells. PGDH decreased in normal cells after 1 and 3 days of differentiation, but returned to normal after 7 days. PGDH expression was unchanged during differentiation at 1 and 3 days, but was more than 2‐fold higher at 7 days compared to day 0 in the IC cells. Urothelial cells isolated from IC patients demonstrated no PGE2 release in response to tryptase under any of the experimental conditions studied. Taken together, our results indicate that PGE2 release is compromised during differentiation in IC urothelium and may contribute to impaired barrier function.

Transglutaminase II interacts with rac1, regulates production of reactive oxygen species, expression of snail, secretion of Th2 cytokines and mediates in vitro and in vivo allergic inflammation

Transglutaminase II (TGase II) is a protein cross-linking enzyme with diverse biological functions. Here we report the role of TGase II in allergic inflammation. Antigen stimulation induced expression and activity of TGase II by activation of NF-κB in rat basophilic leukemia (RBL2H3) cells. This induction of TGase II was dependent on FcɛRI and EGFR. Interaction between TGase II and rac1 was induced following antigen stimulation. TGase II was responsible for the increased production of reactive oxygen species, expression of prostaglandin E2 synthase (PGE2 synthase) and was responsible for increased secretion of prostaglandin E2. ChIP assay showed that TGase II, through interaction with NF-κB, was responsible for the induction of histone deacetylase-3 (HDAC3) and snail by direct binding to promoter sequences. HDAC3 and snail induced by TGase II, exerted transcriptional repression on E-cadherin. Snail exerted negative effect on expression of MMP-2, and secretion of Th2 cytokines. Inhibition of matrix metalloproteinase-2 (MMP-2) inhibited secretion of Th2 cytokines. In vivo induction of TGase II was observed in Balb/c mouse model of IgE antibody-induced passive cutaneous anaphylaxis. Chemical inhibition of TGase II exerted negative effect on IgE-dependent passive cutaneous anaphylaxis. Chemical inhibition of TGase II by cystamine exerted negative effect on Balb/c mouse model of phorbol myristate acetate (PMA)-induced atopic dermatitis. These results suggest novel role of TGase II in allergic inflammation and TGase II can be developed as target for the development of allergy therapeutics.

Effect of the conceptus on uterine prostaglandin-F2α and prostaglandin-E2 release and synthesis during the periimplantation period in the pig

The present study was conducted to evaluate the effect of the conceptus on uterine prostaglandin-F2alpha (PGF2alpha) and prostaglandin-E2 (PGE2) release and the expression of prostaglandin synthase enzymes during the periimplantation period in the pig. A surgically generated model with conceptuses developing in only one of the uterine horns was created. The highest concentration of PGF2alpha and PGE2 was found in the gravid uterine horn, compared with the non-gravid horn and the intact horn of cyclic gilts. Endometrial concentration of both PGs in pregnant gilts was elevated regardless of the conceptus in the uterine horn, whereas only myometrial PGE2 concentration increased during pregnancy. Expression of prostaglandin-E2 synthase (mPGES-1) mRNA in the endometrium was upregulated during the oestrous cycle, while protein expression presented a similar pattern to that of PGE2 concentration in the uterine flushings. Prostaglandin-F2alpha synthase (PGFS) mRNA and protein expression in the endometrium did not differ between pregnancy and oestrous cycle but PGFS mRNA in the myometrium increased during pregnancy both in the gravid and the non-gravid uterine horns. We suggest a local effect of the conceptus on PG release pathways but also a more systemic effect within the whole uterus with regard to PG synthesis and accumulation in uterine tissues.

Genetic and Epigenetic Regulation of the Human Prostacyclin Synthase Promoter in Lung Cancer Cell Lines

The importance of the arachidonic acid pathway has been established in colon and lung cancers, as well as in inflammatory diseases. In these diseases, prostacyclin I(2) (PGI2) and prostaglandin E(2) (PGE2) are thought to have antagonistic activities, with PGI2 exerting anti-inflammatory and antiproliferative activities, whereas PGE2 is proinflammatory and antiapoptotic. In human lung cancer, prostacyclin synthase (PGIS) and PGI2 are down-regulated, whereas PGE2 synthase (PGES) and PGE2 are up-regulated. Murine carcinogenesis models of human lung cancer reciprocate the relationship between PGIS and PGES expression. PGIS-overexpressing transgenic mice are protected from carcinogen- and tobacco smoke-induced lung tumor formation, suggesting that PGI2 may play a role in chemoprevention. We investigated several potential mechanisms for the down-regulation of PGIS in human lung cancer. Using transcription reporter assays, we show that single nucleotide polymorphisms in the PGIS promoter can affect transcriptional activity. In addition, PGIS expression in several human lung cancer cell lines is silenced by CpG methylation, and we have mapped these sites across the variable number of tandem repeats (VNTR) sequence in the promoter, as well as CpGs within exon 1 and the first intron. Finally, using fluorescence in situ hybridization, we show that human lung cancer cell lines and lung cancer tissues do not have a loss of the PGIS genomic region but multiple copies. These results show that an individual's PGIS promoter haplotype can play an important role in the predisposition for lung cancer and CpG methylation provides an epigenetic mechanism for the down-regulated PGIS expression.

Expression of enzymes of cyclooxygenase pathway and secretion of prostaglandin E 2 and F 2α by porcine myometrium during luteolysis and early pregnancy

Past studies of uterine prostaglandin (PGs) and pig reproduction have focused on endometrial rather than myometrial PGs. This study documents the synthesis and secretion of myometrial prostaglandins (PGs) in pigs and the involvement of oxytocin (OT) in these processes. Cyclooxygenase-2 (COX-2) expression was similar in myometrial explants from cyclic and pregnant pigs (days 14–16) and OT (10 −7 M) in vitro significantly increased COX-2 protein regardless of reproductive state. Basal expression of prostaglandin E 2 synthase (PGES) was higher during pregnancy than during luteolysis. Conversely, prostaglandin F synthase (PGFS) was highest during luteolysis and lower in myometrium from gravid animals. OT had no influence on the expression of PGES and PGFS. In another tissue culture experiment, myometrial slices produced more PGE 2 than PGF 2α regardless of reproductive state of the female. OT stimulated PGE 2 production in myometrium harvested during luteolysis and increased PGF 2α production in all tissues examined. Progesterone (P 4; 10 −5 M) blocked stimulatory effect of OT on myometrial PG release. Myometrial OTr mRNA was higher ( P = 0.03) during luteolysis than during pregnancy. In conclusion: (1) oxytocin increases myometrial COX-2 expression, but does not influence the expression of terminal enzymes of PGs synthesis (PGES and PGFS); (2) porcine myometrium preferentially produces PGs during early pregnancy and secretes more PGE 2 than PGF 2α; (3) myometrial OT and OTr support secretion of PGs from myometrium during luteolysis.