Project description:Prostaglandins (PGD2, PGE2, PGF2α), prostacyclin (PGI2), and thromboxane A2 (TXA2) together form the prostanoid family of lipid mediators. As autacoids, these five primary prostanoids propagate intercellular signals and are involved in many physiological processes. Furthermore, alterations in their biosynthesis accompany a wide range of pathological conditions, which leads to substantially increased local levels during disease. Primary prostanoids are chemically instable and rapidly metabolized. Their metabolites are more stable, integrate the local production on a systemic level, and their analysis in various biological matrices yields valuable information under different pathological settings. Therefore, prostanoid metabolites may be used as diagnostic, predictive, or prognostic biomarkers in human disease. Although their potential as biomarkers is great and extensive research has identified major prostanoid metabolites that serve as target analytes in different biofluids, the number of studies that correlate prostanoid metabolite levels to disease outcome is still limited. We review the metabolism of primary prostanoids in humans, summarize the levels of prostanoid metabolites in healthy subjects, and highlight existing biomarker studies. Since analysis of prostanoid metabolites is challenging because of ongoing metabolism and limited half-lives, an emphasis of this review lies on the reliable measurement and interpretation of obtained levels.
Project description:Background and purposeLubiprostone, a prostaglandin E₁ derivative, is reported to activate ClC-2 chloride channels located in the apical membranes of a number of transporting epithelia. Lack of functioning CFTR chloride channels in epithelia is responsible for the genetic disease cystic fibrosis, therefore, surrogate channels that can operate independently of CFTR are of interest. This study explores the target receptor(s) for lubiprostone in airway epithelium.Experimental approachAll experiments were performed on the ventral tracheal epithelium of sheep. Epithelia were used to measure anion secretion from the apical surface as short circuit current or as fluid secretion from individual airway submucosal glands, using an optical method.Key resultsThe EP₄ antagonists L-161982 and GW627368 inhibited short circuit current responses to lubiprostone, while EP₁(,)₂(&)₃ receptor antagonists were without effect. Similarly, lubiprostone induced secretion in airway submucosal glands was inhibited by L-161982. L-161982 effectively competed with lubiprostone with a K(d) value of 0.058 µM, close to its value for binding to human EP₄ receptors (0.024 µM). The selective EP₄ agonist L-902688 and lubiprostone behaved similarly with respect to EP₄ receptor antagonists. Results of experiments with H89, a protein kinase A inhibitor, were consistent with lubiprostone acting through a G(s) -protein coupled EP₄ receptor/cAMP cascade.Conclusions and implicationsLubiprostone-induced short-circuit currents and submucosal gland secretions were inhibited by selective EP₄ receptor antagonists. The results suggest EP₄ receptor activation by lubiprostone triggers cAMP production necessary for CFTR activation and the secretory responses, a possibility precluded in CF tissues.
Project description:The lymphatic system is an important route for cancer dissemination, and lymph node metastasis (LNM) serves as a critical prognostic determinant in cancer patients. We investigated the contribution of COX-2-derived prostaglandin E2 (PGE2) in the formation of a premetastatic niche and LNM. A murine model of Lewis lung carcinoma (LLC) cell metastasis revealed that COX-2 is expressed in DCs from the early stage in the lymph node subcapsular regions, and COX-2 inhibition markedly suppressed mediastinal LNM. Stromal cell-derived factor-1 (SDF-1) was elevated in DCs before LLC cell infiltration to the lymph nodes, and a COX-2 inhibitor, an SDF-1 antagonist, and a CXCR4 neutralizing antibody all reduced LNM. Moreover, LNM was reduced in mice lacking the PGE2 receptor EP3, and stimulation of cultured DCs with an EP3 agonist increased SDF-1 production. Compared with WT CD11c+ DCs, injection of EP3-deficient CD11c+ DCs dramatically reduced accumulation of SDF-1+CD11c+ DCs in regional LNs and LNM in LLC-injected mice. Accumulation of Tregs and lymph node lymphangiogenesis, which may influence the fate of metastasized tumor cells, was also COX-2/EP3-dependent. These results indicate that DCs induce a premetastatic niche during LNM via COX-2/EP3-dependent induction of SDF-1 and suggest that inhibition of this signaling axis may be an effective strategy to suppress premetastatic niche formation and LNM.
Project description:Cancer-associated disturbance of prostanoid signaling provides an aberrant accumulation of prostanoids. This signaling consists of 19 target genes, encoding metabolic enzymes and G-protein-coupled receptors, and prostanoids (prostacyclin, thromboxane, and prostaglandins E2, F2α, D2, H2). The study addresses the systems biology analysis of target genes in 24 solid tumors using a data mining pipeline. We analyzed differential expression patterns of genes and proteins, promoter methylation status as well as tissue-specific master regulators and microRNAs. Tumor types were clustered into several groups according to gene expression patterns. Target genes were characterized as low mutated in tumors, with the exception of melanoma. We found at least six ubiquitin ligases and eight protein kinases that post-translationally modified the most connected proteins PTGES3 and PTGIS. Models of regulation of PTGIS and PTGIR gene expression in lung and uterine cancers were suggested. For the first time, we found associations between the patient's overall survival rates with nine multigene transcriptomics signatures in eight tumors. Expression patterns of each of the six target genes have predictive value with respect to cytostatic therapy response. One of the consequences of the study is an assumption of prostanoid-dependent (or independent) tumor phenotypes. Thus, pharmacologic targeting the prostanoid signaling could be a probable additional anticancer strategy.
Project description:Aging is a major risk factor for carotid artery disease that may lead to stroke and dementia. Vascular effects associated with aging include increased vasomotor tone, as well as enhanced contractility to endothelial vasoconstrictor prostanoids and reduced nitric oxide (NO) bioactivity partly due to increased oxidative stress. We hypothesized that vascular NADPH oxidase (Nox)-derived superoxide may be involved in prostanoid- and NO-related functional aging. NO-mediated relaxations and prostanoid-mediated contractions to acetylcholine as well as phenylephrine-dependent contractions were investigated in the carotid artery from young (4 months) and aged mice (24 months). Gene expression of Nox subunits and endothelial NO synthase (eNOS) was determined in the carotid artery and aorta. In young mice, the thromboxane-prostanoid receptor antagonist SQ 29,548 fully blocked acetylcholine-induced contractions while reducing responses to phenylephrine by 75 %. The Nox2-targeted inhibitor Nox2ds-tat and the superoxide scavenger tempol reduced acetylcholine-stimulated, prostanoid-mediated contractions by 85 and 75 %, respectively, and phenylephrine-dependent contractions by 45 %. Unexpectedly, in aged mice, the substantial Nox2-dependent component of acetylcholine- and phenylephrine-induced, prostanoid-mediated contractions was abolished. In addition, endothelium-dependent, NO-mediated relaxations were impaired with aging. The expression of Nox subunits was greater in the aorta compared with the carotid artery, in which Nox1 was undetectable. eNOS gene expression was reduced in the aorta of aged compared to young mice. In conclusion, aging decreases prostanoid-mediated contractility in the carotid artery involving a loss of Nox2 activity and is associated with impaired endothelium-dependent, NO-mediated relaxation. These findings may contribute to a better understanding of the pathophysiology of carotid artery disease and the aging process.
Project description:Prostaglandin signaling controls a wide range of biological processes from blood pressure homeostasis to inflammation and resolution thereof to the perception of pain to cell survival. Disruption of normal prostanoid signaling is implicated in numerous disease states. Prostaglandin signaling is facilitated by G-protein-coupled, prostanoid-specific receptors and the array of associated G-proteins. This review focuses on the expression, characterization, regulation, and mechanism of action of prostanoid receptors with particular emphasis on human isoforms.
Project description:We explored the involvement of FP receptor and endogenous prostaglandins (PGs) in transient ocular hypertension (OH) induced by PGE2 or PGF2α in mouse eyes. PGE2 and PGF2α were topically applied to induce transient OH in Wild-type (WT) and FP-, EP1-, EP2-, and EP3-deficient (knockout [KO]) mice. To suppress endogenous PG production, the non-steroidal anti-inflammatory drug nepafenac was applied topically before treatment. PGE2 and PGF2α induced significant OH in the WT, FPKO, and EP1-3KO mice compared to the control 30 min after instillation, and the increase in IOP at 30 or 60 min after instillation in FPKO mice was significantly higher than that in the WT mice. The effects of PGF2α on the increase in IOP were significantly weaker than those of PGE2, especially in EP1KO and EP3KO mice. Transient OH induced by PGE2 and PGF2α was significantly attenuated by nepafenac treatment in FPKO mice. Transient OH was induced by PGE2 and PGF2α in WT, FPKO, and EP1-3KO mice, which was enhanced in FPKO mice. This OH was significantly diminished by nepafenac treatment in FPKO mice, suggesting that FP receptor may have an important naïve physiological role in the eye, and could regulate IOP elevation during PG-associated ocular inflammation.