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Prostaglandin E 2 (PGE 2 ) is known to increase glioblastoma (GBM) cell proliferation and migration while cyclooxygenase (COX) inhibition decreases proliferation and migration. The present study investigated the effects of COX inhibitors and PGE 2 receptor antagonists on GBM cell biology. Cells were grown with inhibitors and dose response, viable cell counting, flow cytometry, cell migration, gene expression, Western blotting, and gelatin zymography studies were performed. The stimulatory effects of PGE 2 and the inhibitory effects of ibuprofen (IBP) were confirmed in GBM cells. The EP2 and EP4 receptors were identified as important mediators of the actions of PGE 2 in GBM cells. The concomitant inhibition of EP2 and EP4 caused a significant decrease in cell migration which was not reverted by exogenous PGE 2 . In T98G cells exogenous PGE 2 increased latent MMP2 gelatinolytic activity. The inhibition of COX1 or COX2 caused significant alterations in MMP2 expression and gelatinolytic activity in GBM cells. These findings provide further evidence for the importance of PGE 2 signalling through the EP2 and the EP4 receptor in the control of GBM cell biology. They also support the hypothesis that a relationship exists between COX1 and MMP2 in GBM cells which merits further investigation as a novel therapeutic target for drug development.

Prostanoids derived from the activity of cyclooxygenases and their respective synthases contribute to both active inflammation and immune response in the tumor microenvironment. Their synthesis, deactivation and role in glioma biology have not yet been fully explored and require further study. Using quantitative real time PCR, gas chromatography/ electron impact mass spectrometry and liquid chromatography/ electrospray ionization tandem mass spectrometry, we have further characterized the prostanoid pathway in grade IV glioblastoma (GBM). We observed significant correlations between high mRNA expression levels and poor patient survival for microsomal PGE synthase 1 (mPGES1) and prostaglandin reductase 1 (PTGR1). Conversely, high mRNA expression levels for 15-hydroxyprostaglandin dehydrogenase (15-HPGD) were correlated with better patient survival. GBMs had a higher quantity of the prostanoid precursor, arachidonic acid, versus grade II/III tumors and in GBMs a significant positive correlation was found between arachidonic acid and PGE 2 content. GBMs also had higher concentrations of TXB 2 , PGD 2 , PGE 2 and PGF 2α versus grade II/III tumors. A significant decrease in survival was detected for high versus low PGE 2 , PGE 2 + PGE 2 deactivation products (PGEMs) and PGF 2α in GBM patients. Our data show the potential importance of prostanoid metabolism in the progression towards GBM and provide evidence that higher PGE 2 and PGF 2α concentrations in the tumor are correlated with poorer patient survival. Our findings highlight the potential importance of the enzymes 15-HPGD and PTGR1 as prognostic biomarkers which could be used to predict survival outcome of patients with GBM., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: The World Health Organization classifies glioblastoma (GBM) as a grade IV astrocytoma. Despite the advances in chemotherapy, surgery, and radiation treatments that improve a patient's length of survival, the overall trajectory of the disease remains unchanged. GBM cells produce significant levels of various types of bioactive lipids. Prostaglandin D 2 (PGD 2 ) influences both pro- and anti-tumorigenic activities in the cell; however, its role in GBM is unclear. Therefore, this study aimed to identify the impact of PGD 2 on GBM cell activities in vitro., Methods: First we looked to identify the presence of the PGD 2 synthesis pathway through RT-PCR, immunohistochemistry, and HPLC-MS/MS in three GBM cell lines. Then, to observe PGD 2 's effects on cell count and apoptosis/mitosis (Hoechst 33342 stain), and migration (Transwell Assay), the cells were treated in vitro with physiological (<1μM) and/or supraphysiological (>1μM) concentrations of PGD 2 over 72h. HPLC-MS/MS was used to identify the lipid composition of patients with either Grade II/III gliomas or GBM., Results: We identified the presence of endogenous PGD 2 with its corresponding enzymes and receptors. Exogenous PGD 2 both increased cell count (<1μM) and decreased cell count (10μM) in a concentration-dependent manner. There were no significant effects on apoptosis. A significant decrease in mitotic activity was seen only in U251MG, and a significant increase was seen in migration with 5μM PGD 2 treatments. A very significant increase of PGD 2 was seen from Grade II/III gliomas to GBM., Conclusions: Our study demonstrates that prostaglandin D 2 possesses a dynamic, concentration-dependent effect in GBM cell activities. The increase of PGD 2 production in GBM patients suggests a pro-tumorigenic role of PGD 2 in glioma growth and invasion. Therefore, prostaglandin signaling in GBM requires further investigation to identify new targets for more effective therapies., (Copyright © 2017 Elsevier Inc. All rights reserved.)