Prostaglandin-endoperoxide Synthase 2 Gene Research Articles

Abstract 1870: Association of prostaglandin-endoperoxide synthase 2 (PTGS-2) polymorphisms with colorectal cancer risk and immunohistochemical detection of PTGS-2 in Chinese colorectal cancer patients

Abstract PTGS-2 is an rate-limiting enzyme that can be induced by several factors including mitogens, cytokines, growth factors and tumor promoters. It catalyzes the formation of Prostaglandin E2 (PGE2) that favors carcinogenic processes. Overexpression of PTGS-2 gene encoding PTGS-2 enzyme was observed in several human malignancies including colorectal cancer. Various functional genetic polymorphisms present in the PTGS-2 gene were shown to influence the expression level of the PTGS-2 protein and affect the individuals’ susceptibility to developing colorectal cancer. Whole gene screening in the healthy local Chinese subjects had identified 26 SNPs, which were tagged by 15 tag SNPs. Among these tag single nucleotide polymorphisms (SNPs), two were found in the 5′ upstream region [−1424 A>G (rs689465), −1329 A>G (rs689466)], five were in the intronic region [IVS1+145A>G (rs11567820), IVS2-22C>G (rs20427), IVS3+36C>T, IVS9+146C>T and IVS9-164G>T], two were in the coding region [306G>C (rs5277) and 1759G>A(rs3218625)], four were in the 3′ untranslated region (UTR) [*427T>C (rs5275), *2267G>T (rs4648302), *2358T>A (rs13306038), *2368_*2369insA] and two were located in the 3′ downstream region [*+2868G>A (rs4648308), *+4038_*4039insTA] of the PTGS-2 gene. This study aimed to investigate the association between fifteen PTGS-2 tag SNPs and one functional SNP [-899G>C (rs20417)] with (1) the risk of developing colorectal cancer and (2) the expression level of PTGS-2 protein in the tumor resections in Chinese colorectal cancer patients (N=90). The genetic association analysis indicated that patients harboring the heterozygous genotype (TC) of *427T>C (rs5275) SNP had a significant reduced risk in colorectal cancer predisposition (codominant model: Odds Ratio (OR)=0.51; 95% Confidence Interval (CI)=0.25-1.03; P=0.033 and overdominant model: OR=0.47; 95% CI=0.24-0.95; P=0.033). However, this SNP was not found to be significantly associated with the PTGS-2 expression in the tumor resections of the patients (N=48). No significant correlation was observed between other investigated tag SNPs with colorectal cancer risk and PTGS-2 protein expression. The findings of this study suggest that *427T>C (rs5275) might be a biomarker for colorectal cancer predisposition in the local Chinese colorectal cancer patients. Further conformational investigations in larger cohort should be performed to validate the findings of the present study. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1870. doi:1538-7445.AM2012-1870

PTGS2 (Prostaglandin Endoperoxide Synthase-2) Expression in Term Human Amnion in Vivo Involves Rapid mRNA Turnover, Polymerase-II 5′-Pausing, and Glucocorticoid Transrepression

The in vivo role of glucocorticoids in controlling prostaglandin endoperoxide synthase-2 (PTGS2) expression in the human amnion is unclear despite extensive studies using in vitro models. We addressed this issue by determining PTGS2 mRNA levels and gene transcriptional activity, RNA polymerase-II (pol-II) binding, pol-II C-terminal domain (CTD) phosphorylation, histone acetylation, and histone methylation at the PTGS2 gene in fresh amnion and in amnion explants incubated with dexamethasone for 24 h after delivery, when adaptation from in vivo to in vitro conditions occurred. PTGS2 mRNA turnover changed during incubation involving the initial rapid decrease and subsequent rebound of the transcription rate and stabilization of mRNA. pol-II accumulated in the 5'-region of the gene, which indicated postinitiation pausing. pol-II binding, 5'-accumulation, C-terminal domain Ser-5 and Ser-2 phosphorylation, and histone acetylation decreased rapidly and did not reverse during the transcriptional rebound, suggesting that the transcriptional mechanism altered in vitro. Dexamethasone decreased PTGS2 gene activity and mRNA levels. Glucocorticoid receptor-α (GRα) was bound to the PTGS2 promoter but did not affect pol-II recruitment, pausing, or the epigenetic marks. GRα binding, however, decreased initiating (Ser-5) and elongating (Ser-2) pol-II phosphorylation. The ability of the PTGS2 promoter to bind GRα in response to dexamethasone diminished during incubation. We conclude that PTGS2 mRNA turnover is accelerated in vivo, but the underlying mechanisms are not sustained beyond 24 h in explants. Glucocorticoids chronically transrepress PTGS2 gene activity in vivo in part by interfering with transcription initiation and elongation. Glucocorticoid transrepression of PTGS2 may be important for pregnancy maintenance and the timing of parturition.

Association between Prostaglandin-endoperoxide Synthase 2 (PTGS2) Polymorphisms and Blood Pressure in Korean Population

Blood pressure refers to the force exerted by circulating blood on the walls of blood vessels, and chronical elevation of blood pressure is known as hypertension. Although hypertension is affected by genetic and environmental factors, the genetic background of hypertension is not fully understood. One of the candidate genetic factors, Prostaglandin-endoperoxide synthase 2 (PTGS2), is a membrane-bou nd enzyme, catalyzing the conversion of arachidonic acid to prostaglandin, and recently SNPs of PTGS2 gene was associated with hypertension in Japanese population. Therefore the association of PTGS2 polymorphisms was investigated with blood pressure in healthy Korean subjects, 470 unrelated individuals randomly selected from Ansung and Ansan cohorts. The 25 SNPs of PTGS2 gene were identified by the sequencing analysis of 24 Korean samples. Among identified polymorphisms, three SNPs (rs689466, -1329A＞G; rs5275, +6365T＞C; rs4648308, +8806G＞ A) were selected for further association analysis, and rs689466 located in promoter region was associated with blood pressure as well as triglyceride level in the blood. By in silico analysis, rs689466 locates in v-Myb transcription factor binding site, and the v-Myb site disappears when the SNP is changed from A to G nucleotide. Individuals with A/G and G/G genotype in rs689466 have higher blood pressure than those with A/A genotype, and the regression p-value is 0.008 for systolic and 0.004 for diastolic blood pressure. In summary, the PTGS2 polymorphism (rs689466) is associated with blood pressure in Asian populations based on this and Japanese studies, shedding light on it as a genetic risk marker of hypertension.

Prosequencing™ of Polymorphisms in the COX-2 Gene ( PTGS2 ) with Reported Clinical Relevance

Genetic variants in the prostaglandin-endoperoxide synthase 2 (PTGS2) gene, which codes for COX-2, have been identified to modulate the response to COX-2-inhibiting drugs and to be possible risk factors for the incidence or prognosis of cardiovascular or neoplastic diseases, Alzheimer's disease, multiple sclerosis, asthma or osteoarthritis. Clinical evidence thus suggests a clinical importance of COX-2 genetics reaching from disease risk or prognostics up to a personalized therapy with COX-2 inhibitors. The aim of this study was to develop rapid and reliable screening assays for PTGS2 mutations with reported clinical consequences. SNPs (dbSNP-IDs rs689465, rs689466, rs3918304, rs20415, rs20417, rs5270, rs2745557, rs5277, rs2066826, rs4648276, rs5273, rs5275, rs4648298, rs689469) and a nucleotide-deletion variant (rs20431) were chosen according to reported functional associations. For this selection of variants spanning the whole PTGS2 gene range, Pyrosequencing assays were established in DNA from 350 healthy unrelated Caucasians. In all 350 DNA samples, the 15 PTGS2 polymorphisms were identified correctly as verified by control samples obtained by conventional sequencing. In silico haplotype analysis based on ten SNPs of greater than 1% observed frequencies identified two haploblocks with a linkage disequilibrium of D' = 0.59. Approximately 50% of the reconstructed haplotypes consisted of non-mutated alleles. The presently developed Pyrosequencing assays allow for quick and reliable detection of PTGS2 genotypes and may promote further research toward personalized approaches to pathophysiological conditions involving COX-2.

Association of prostaglandin-endoperoxide synthase 2 (PTGS2) polymorphisms and Alzheimer's disease in Chinese

Cyclooxygenase-2 (COX-2, encoded by the gene prostaglandin-endoperoxide synthase 2, PTGS2) is a key enzyme in the conversion of arachidonic acid to prostaglandins. The prostaglandins produced by COX-2 are involved in inflammation and pain response in different tissues in the body. Enhanced COX-2 expression had been found in regions of brains from patients with Alzheimer's disease (AD). Here, we proceeded to test the hypothesis that polymorphisms of the PTGS2 gene predispose to AD. IVS5−275 T>G and Ex10+837 T>C in addition to three tagging SNPs from HapMap database, which provided a comprehensive coverage of genetic variations in the PTGS2 gene in Chinese were genotyped among 257 AD patients and 244 age-matched healthy Chinese subjects. Genetic associations were analyzed by χ 2-test and haplotypes analysis. Although the previously reported protective polymorphism (rs20417, −765 G/C) for AD in PTGS2 gene was not polymorphic in the Chinese population, SNPs in both the promoter (−2319 G>T) and 3′ region (Ex10+837 T>C) of PTGS2 were associated with the risk of AD ( p = 0.01 and 0.03, respectively). Carriers of Ex10+837 T allele had a 1.5-fold increase in the risk of AD. This study suggested that PTGS2 gene was a predisposition gene and arachidonic acid metabolism might be involved in the pathogenesis of AD. It provided further evidence to support a role of inflammation in the development and progression of AD.

Polymorphisms of prostaglandin-endoperoxide synthase 2 gene, and prostaglandin-E receptor 2 gene, C-reactive protein concentrations and risk of atherothrombosis: a nested case-control approach.

Recent data have shown an association between polymorphisms of prostaglandin-endoperoxide synthase-2 gene (PTGS2; alias COX-2), and prostaglandin-E receptor-2 gene (PTGER2) and risk of atherothrombotic disorders. We evaluated two PTGS2 (rs20417, rs689470), and three PTGER2 (rs708494/uS5, rs708495/uS7, and chr14: 50 764 013/uS10) gene polymorphisms among 600 Caucasian male participants of the Physicians' Health Study with incident myocardial infarction (MI) or ischemic stroke and 600 age- and smoking-matched controls who remained free of all reported cardiovascular disease. Genotype distributions were in Hardy-Weinberg equilibrium in the control groups. Genotype and allele distribution were similar between cases and controls. The polymorphisms tested were in linkage disequilibrium. Results from the adjusted haplotype-based conditional logistic regression analysis showed a modest association of the PTGER2 2-1-1 haplotype with reduced risk of MI (odds ratio = 0.50, 95% CI; CI = 0.26-0.97, P = 0.04), and the 2-2-1 haplotype with reduced risk of ischemic stroke (odds ratio = 0.68, 95% CI = 0.47-0.99, P = 0.048). In contrast to prior data, we found no evidence for an association of the PTGS2 polymorphisms/haplotypes tested with risk of incident MI nor with ischemic stroke. However, we found suggestive evidence for an association of specific PTGER2 haplotypes with reduced risk of these outcomes. Although these prospective data implicate the potential involvement of prostaglandin-E receptor-2 gene variation in atherothrombosis, external validation of our findings is needed.

Association of Polymorphisms in Epidermal Growth Factor, Prostaglandin-endoperoxide Synthase 2 and Prolactin Receptor Genes with Semen Quality in Duroc Boars

The quality characteristics of semen are important indicators of the fertility of a boar. Development of genetic markers for the semen quality in boars will be beneficial to the improvement of porcine fertility. We investigated the relationship between the polymorphisms of epidermal growth factor (EGF), prostaglandin-endoperoxide synthase 2 (PTGS2) and prolactin receptor (PRLR) genes, and semen quality traits in boars. The genomic DNA of 233 boars (157 Duroc and 86 Landrace) from a central testing station was subjected to genotyping for surveying gene frequency. The EGF, PTGS2 and PRLR genotypes were determined using the restriction fragment length polymorphism method. Thirty-seven normal, mature Duroc boars from an AI center were also genotyped and their semen quality traits were collected. The effect of genotype on semen quality traits was analyzed by the least-squares means method using data corrected for season. The frequencies of the AA genotype of EGF, PTGS2 and PRLR in Duroc boars were 0.14, 0.01 and 0.66, respectively. In Landrace, the frequencies of the AA genotype were 0.03, 0.09 and 0.62, respectively. Boars with the BB genotype in EGF, with the AB genotype in PTGS2 and with the AA genotype in PRLR had significantly better semen quality with a higher percentage of normal sperm and a lower percentage of immature sperm than those with other genotypes. These findings imply that polymorphisms of EGF, PTGS2 and PRLR genes might be used as markers for improving the semen quality of boars. (Asian-Aust. J. Anim. Sci. 2006. Vol 19, No. 6 : 793-798)

248 PUBLICATION Pyruvate kinase activity in colon, stomach and breast tissue as a marker of malignancy

Oxytocin (OXT) has been used to prolong the luteal phase in mares, but its mechanism of action is unknown. The aim of this study was to evaluate the effect of chronic exogenous OXT administration to mid-luteal phase mares on luteal maintenance. Also, endometrial expression of prostaglandin endoperoxide synthase 2 (PTGS2), prostaglandin F2α, E2 and I2 synthases (AKR1C3, PTGES, and PTGIS), oxytocin receptor (OXTR), progesterone receptor (PGR), and estrogen receptors 1 (ESR1) and 2 (ESR2) were assessed in mares experiencing luteal maintenance 2 weeks after chronic exogenous OXT administration. Control mares (n = 5; C group) received 6 mL of saline im, whereas OXT (60 units/mare) was administered im (n = 6; OXT group), every 12 hours, on days 7 to 14 postovulation. After endometrial biopsy in groups C (Day 10) and OXT (Day 24), luteolysis occurred within 3 or 6 days, respectively. Luteal maintenance took place in 4 of 6 (67%) of OXT-treated mares. Progesterone in C group was the highest on biopsy day (P < 0.05). In OXT mares, PTGS2, ESR1 (P < 0.05), PTGES, PTGIS, PGR, and ESR2 (P < 0.01) gene transcription decreased, whereas OXTR increased (P < 0.05) in comparison with the C group. In OXT-treated mares, endometrial ESR2 protein expression decreased (P < 0.05), but OXTR increased (P < 0.05) compared with control animals. In both experimental groups, PTGS2 was mainly immunolocalized in surface epithelium, whereas AKR1C3, PTGES, PTGIS, and PGR were in surface and glandular epithelia. ESR1 and ESR2 were found in glandular epithelium and OXTR in stromal cells. High immunolabeling for PTGES, PTGIS, PGR, and OXTR and low for ESR2 was detected in endometrium of OXT-group mares with extended diestrus. Prolonged luteal function associated with chronic OXT treatment may be related to different spatial expression of OXTR and PGR in the endometrium. The observed reduction of endometrial ESR2 may be responsible for the maintenance of PGR in luminal and glandular epithelium. Also, ESR2 may attenuate the transcriptional activity of ESR1 in mare endometrium. This study offers new knowledge on the endometrial expression of ovarian steroids and OXT receptors in OXT pharmacologically induced luteal maintenance in the mare.

Dexamethasone Inhibits Interleukin-1-Dependent Prostaglandin Endoperoxide Synthase-2 Gene Expression by Cultured Rat Whole Ovarian Dispersates

Dexamethasone Inhibits Interleukin-1-Dependent Prostaglandin Endoperoxide Synthase-2 Gene Expression by Cultured Rat Whole Ovarian Dispersates

P-292 Dexamethasone inhibits interleukin-1-dependent prostaglandin endoperoxide synthase-2 gene expression by cultured rat whole ovarian dispersates

P-292 Dexamethasone inhibits interleukin-1-dependent prostaglandin endoperoxide synthase-2 gene expression by cultured rat whole ovarian dispersates

An E-box Region within the Prostaglandin Endoperoxide Synthase-2 (PGS-2) Promoter Is Required for Transcription in Rat Ovarian Granulosa Cells

The prostaglandin endoperoxide synthase-2 (PGS-2) gene encodes an isoform of prostaglandin synthase that is transiently induced by protein kinase A (luteinizing hormone/cAMP) and protein kinase C (gonadotropin-releasing hormone) agonists in granulosa cells of ovulating follicles. The promoter of the rat PGS-2 gene contains a CAAT enhancer-binding protein consensus site (CAAT box) which can confer hormone inducibility to a PGS-2.CAT reporter gene, as well as a putative E-box region. To determine if the E-box region was involved in hormone induced trans-activation of the rat PGS-2 gene, constructs with the CAAT box and E-box regions (-192 PGS-2.CAT), only the putative E-box (-110 PGS-2.CAT), or neither region (-52 PGS-2.CAT) were transiently transfected into rat granulosa cell cultures. CAT activity was induced in both the -192 and -110 PGS-2*CAT vectors by luteinizing hormone (10-fold) and gonadotropin-releasing hormone (6-fold), whereas CAT activity of the -52 PGS-2.CAT construct did not differ from the promoterless vector (pCAT-Basic). Deletion of 1 base pair from the E-box within the -110 PGS-2.CAT construct, as well as point mutations within the CAAT box, E-box, or both regions of the -192 PGS-2.CAT construct, demonstrated that the E-box is critical for basal transcription, and that regions, in addition to the CAAT box, are involved in hormone induction of the PGS-2 gene. An oligonucleotide spanning the rat PGS-2 E-box bound two specific protein complexes which were supershifted in the presence of antibody specific for the upstream stimulatory factor. Thus, in rat granulosa cells, the PGS-2 E-box region appears to interact with upstream cis-acting elements other than the CAAT box to confer hormonal regulation of the gene. The E-box region of the rat PGS-2 promoter does not contain ATF/CRE activity found in the human and mouse PGS-2 promoters, but is critical for basal transcription of the PGS-2 gene in rat granulosa cells and binds the upstream stimulatory factor (as do E-box regions of other genes regulated in the ovary).

Assignment of the Human Prostaglandin-Endoperoxide Synthase 2 (PTGS2) Gene to 1q25 by Fluorescence in Situ Hybridization

A major mechanism for the regulation of prostaglandin synthesis occurs at the level of cyclooxygenase, also known as prostaglandin-endoperoxide synthase (PTGS). Two isoforms of PTGS have been identified: PTGS1, encoded by a 2.8-kb mRNA and a mitogen-inducible form, PTGS2, encoded by a 4.5-kb mRNA. We report here the assignment of the human PTGS2 gene to chromosome 1q25 by fluorescence in situ hybridization (FISH). We note with interest the physical proximity of the PTGS2 gene to that of cytosolic phospholipase A2 (cPLA2), which we have previously mapped to chromosome 1q24-q25. In contrast, the PTGS1 gene has been mapped to chromosome 9. Since cPLA2 and PTGS2 are key enzymes in the synthesis of prostaglandins and thromboxane, the possible implication of this proximity could mean that polymorphic markers already determined for the cPLA2 gene may also prove to be useful as markers for the PTGS2 gene as well. 10 refs., 1 fig.

Transcriptional regulation of the rat prostaglandin endoperoxide synthase 2 gene in granulosa cells. Evidence for the role of a cis-acting C/EBP beta promoter element.

The promoter of the rat prostaglandin endoperoxide synthase 2 (PGS-2) gene has recently been shown to confer gonadotropic hormone (follicle-stimulating hormone (FSH), luteinizing hormone (LH), cAMP) inducibility when ligated to a CAT (chloramphenicol acetyltransferase) reporter gene and transfected into primary cultures of differentiated granulosa cells. To delineate cis-acting elements and trans-activating factors mediating this response, deletions of the active promoter region (-192/-53 base pairs upstream of the transcriptional start site) were tested for their ability to bind protein of granulosa cell nuclear extracts and activate reporter gene activity. Electrophoretic mobility shift assays revealed that the DNA subregion -142/-120 inhibited protein/DNA binding observed between granulosa cell nuclear extracts and the labeled PGS-2 fragment -192/-53. The subregion -142/-120 acting element C/EBP beta, 5'-TTATGCAAT-3'. Point mutations within the C/EBP beta element abolished protein/DNA binding and resulted in a 50% loss of forskolin/LH/FSH inducibility of reporter gene activity. C/EBP beta mRNA and protein were induced rapidly in granulosa cells in vivo by an ovulatory dose of human chorionic gonadotropin (hCG). Collectively, these results indicate that C/EPB beta appears to play a key role in regulating induction of the PGS-2 gene in granulosa cells prior to ovulation.