dinoprost and Glioma

Topics: Animals; Antineoplastic Agents; Astrocytes; Astrocytoma; Cell Survival; Cyclooxygenase Inhibitors; Dinoprost; F2-Isoprostanes; Fatty Acids; gamma-Linolenic Acid; Glioma; Ibuprofen; Lipoxygenase Inhibitors; Oxidative Stress; Radiation Tolerance; Rats; Tumor Cells, Cultured

The cytotoxic effects of cis-parinaric acid, a plant-derived 18-carbon polyunsaturated fatty acid, were assessed in vitro on normal and neoplastic glia. After being incubated for 24 hours in the presence of 12 mumol/L cis-parinaric acid, 36B10 glioma cultures demonstrated nearly 90% toxicity (unpaired Student's t test, P < 0.001). Similar results were obtained after the exposure of C6 rat glioma cultures, A172 human glioma cultures, and U-937 human monocytic leukemia cultures to cis-parinaric acid. In contrast, fetal rat astrocytes incubated with 12 mumol/L cis-parinaric acid demonstrated no significant toxicity (3% reduction, P = 0.12); fetal rat astrocytes showed only 20% toxicity after exposure to 40 mumol/L cis-parinaric acid (P = 0.001). The cytotoxic effects of cis-parinaric acid were antagonized with the addition of equimolar concentrations of alpha-tocopherol. Enzyme immunoassay of treated 36B10 glioma supernatant fluid for 8-isoprostane (a known oxidative metabolite) demonstrated a 10-fold increase of 8-isoprostane over 24 hours (123.0 +/- 10.3 versus 10.0 +/- 0.7 pg/ml for control, P < 0.001). These studies indicate that cis-parinaric acid may be significantly cytotoxic to malignant glioma cells in concentrations that spare normal astrocytes and that the mechanism of cytotoxicity is related to an oxidative process. The selective cytotoxic effect of cis-parinaric acid we describe represents the first step in the development of new chemotherapeutic agents for gliomas; these new agents act by preferentially enhancing lipid peroxidation in neoplastic cells.

Topics: Animals; Antineoplastic Agents; Arachidonic Acids; Astrocytes; Brain Neoplasms; Cell Line; Cell Survival; Dinoprost; Dose-Response Relationship, Drug; F2-Isoprostanes; Fatty Acids, Unsaturated; Glioma; Humans; Lipid Peroxidation; Rats; Tumor Cells, Cultured

Effects of increased levels of arachidonic acid (AA) were analyzed in vitro by employment of C6 glioma cells and astrocytes from primary culture. The cells were suspended in a physiological medium added with arachidonic acid (AA) in a concentration range from 0.01 to 0.5 mM. The concentration profiles of the fatty acid and AA-metabolites were subsequently followed for 90 min. AA was measured by gas chromatography, whereas the AA-metabolites PGF2 alpha and LTB4 by radioimmunoassay (RIA). Following administration of AA at 0.05 or 0.1 mM the medium was completely cleared from the fatty acid within 10 to 15 min. However, when 0.5 mM were added, AA concentrations of 0.36 +/- 0.055 mM were found at 20 min, while 0.275 +/- 0.045 mM at 90 min. Addition of AA (0.1 mM) to cell-free medium was also associated with a steady decline of its concentration, although the decrease was markedly delayed as compared to the clearance in the presence of glial cells. AA was subjected to dose-dependent metabolisation in the cell suspension as demonstrated by the production of PGF2 alpha and LTB4. Following addition of 0.01 or 0.5 mM, concentrations of PGF2 alpha increased to a 1.9- or 4.9-fold level within 10 min, whereas those of LTB4 rose to a 1.3- or 33.7-fold level. This was attenuated or completely blocked, respectively, by the cyclo- and lipoxygenase inhibitor BW 755C. Formation of both metabolites from AA was also observed when studying astrocytes from primary culture. The current findings demonstrate an impressive efficacy of C6 glioma cells and astrocytes to clear arachidonic acid from the suspension medium and to convert the lipid compound into prostaglandins and leukotrienes. Uptake and metabolisation of AA by the glial elements may play an important role in vivo, for example in cerebral ischemia.

Topics: 4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyrazol-3-amine; Arachidonic Acid; Astrocytes; Culture Media; Cyclooxygenase Inhibitors; Dinoprost; Glioma; Kinetics; Leukotriene B4; Lipoxygenase Inhibitors; Tumor Cells, Cultured

Astrocytes have been identified as the primary source of brain angiotensinogen (Ao), but the regulation of the secretion of this protein from astrocytes is poorly defined. In this study, the rat C6 glioma cell line was used as an astrocyte model to investigate the regulation of Ao secretion. C6 cultures secreted Ao at a rate of 4.05 +/- 1.52 (mean +/- SD) ng of Ao/10(6) cells/24 h as determined by a direct radioimmunoassay. This rate was not significantly altered by the hormones thyroxine, estradiol, angiotensin II, growth hormone, and prostaglandins or by increased levels of intracellular cyclic AMP. Treatment with the synthetic glucocorticoid dexamethasone (DEX; 10(-6) M) reduced the rate of Ao secretion to 1.82 +/- 0.28 ng of Ao/10(6) cells/24 h. By comparison, the basal secretion rate for rat H4 hepatoma cells was 142.4 +/- 10.0 ng of Ao/10(6) cells/24 h, and this increased fourfold (572.4 +/- 173.1 ng/10(6) cells/24 h) in the presence of 10(-6) M DEX. Both these inhibitory (C6) and stimulatory (H4) actions of DEX were dose related. The inhibition observed in C6 cells was mimicked by RU28362, a pure glucocorticoid agonist, and reversed by the antagonist RU486, demonstrating that DEX was functioning as a true glucocorticoid. The action of DEX was also antagonized by the cyclic AMP analogue N6,2'-O-dibutyryladenosine 3':5'-cyclic monophosphate (dBcAMP) (control, DEX, and DEX + dBcAMP, 3.58 +/- 0.73, 1.69 +/- 0.82, and 4.93 +/- 1.88 ng of Ao/10(6) cells/24 h, respectively, and by the beta-adrenergic agonist isoprenaline, which stimulates cyclic AMP production.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 1-Methyl-3-isobutylxanthine; Alprostadil; Angiotensinogen; Animals; Bucladesine; Cyclic AMP; Dexamethasone; Dinoprost; Dose-Response Relationship, Drug; Glioma; Isoproterenol; Liver Neoplasms, Experimental; Mifepristone; Rats; Tumor Cells, Cultured

Angiotensin II (AII) can release arachidonic acid metabolites such as prostacyclin (PGI2) and PGE2 from cells in cultures. It has recently been reported that the AT1 selective nonpeptide AII receptor antagonist losartan had similar effects. The present study was undertaken to further evaluate the effects of AII and losartan on cells which synthesize prostaglandins, including vascular smooth muscle, endothelial, and glial cells. Inhibition of specific [125I]AII binding was demonstrated in porcine smooth muscle cell (PSMC) suspensions with unlabeled AII and losartan. The IC50 values were 1.3 x 10(-9) mol/L and 7.7 x 10(-9) mol/L, respectively. PD123177 (an AT2 selective antagonist) had no effect on binding. AII produced a concentration-related increase in calcium mobilization (fura-2 fluorescence) which was blocked by losartan (IC50 = 8.4 x 10(-8) mol/L) but not by PD123177 (10(-6) mol/L). AII (10(-7) to 10(-5) mol/L) stimulated the basal release of PGI2 by 100%. This response was blocked by losartan (10(-6) to 10(-5) mol/L) but not by PD123177 (10(-6) to 10(-5) mol/L) and neither agent stimulated basal release in PSMC. Similar effects of AII and antagonists were observed upon receptor binding and PGE2 release in primary rat astrocyte (RA) cultures. AII did not release PGI2 from porcine endothelial cells, bovine pulmonary arterial endothelial cells, or rat C6 glioma cells. Losartan had no significant effect at 10(-5) mol/L. By contrast, bradykinin or the calcium ionophore A23187 dramatically increased PGI2 release in each of these cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Angiotensin II; Angiotensin Receptor Antagonists; Animals; Arachidonic Acids; Astrocytes; Biphenyl Compounds; Calcimycin; Cattle; Cells, Cultured; Dinoprost; Dose-Response Relationship, Drug; Endothelium, Vascular; Epoprostenol; Glioma; Imidazoles; Iodine Radioisotopes; Losartan; Macrophages; Male; Muscle, Smooth, Vascular; Prostaglandins; Pyridines; Radioimmunoassay; Radioligand Assay; Rats; Rats, Sprague-Dawley; Receptors, Angiotensin; Swine; Tetrazoles; Thromboxanes; Tumor Cells, Cultured

The accumulation of inositol phosphates (IPs) in response to prostaglandins (PGs) was studied in NG108-15 cells preincubated with myo-[3H]inositol. As a positive control, bradykinin caused accumulation of IPs transiently at an early phase (within 1 min) and continuously during a late phase (15-60 min) of incubation in the cells. PGD2 and PGF2 alpha did not significantly cause the accumulation of IPs at an early phase but significantly stimulated inositol bisphosphate (IP2) and inositol monophosphate (IP) formation at late phase of incubation. The maximum stimulation was obtained at greater than 10(-7) M concentrations of these PGs, the levels being three-and twofold for IP2 and IP1, respectively. 9 alpha, 11 beta-PGF2 has a slight effect but PGE2 and the metabolites of PGD2 and PGF2 alpha have no effect up to 10(-6)M. The effects of PGD2 and PGF2 alpha were not additive, but the effect of each PG was additive to that of bradykinin at a late phase of incubation. Inositol 1-monophosphate was mainly identified in the stimulation by 10(-5) M PGD2 and 10(-5) M PGF2 alpha, whereas both inositol 1-monophosphate and inositol 4-monophosphate were produced in the stimulation by 10(5) M bradykinin. Depletion of extracellular Ca2+ diminished the stimulatory effect of PGD2 and PGF2 alpha and late-phase effect of bradykinin, but simple Ca2+ influx into the cells by high K+, ionomycin, or A23187 failed to cause such late-phase effects. These results suggest that PGD2 and PGF2 alpha specifically stimulate hydrolysis of inositol phospholipids.

Topics: Animals; Bradykinin; Calcium; Chromatography, High Pressure Liquid; Dinoprost; Dose-Response Relationship, Drug; Egtazic Acid; Glioma; Hybrid Cells; Inositol Phosphates; Isomerism; Neuroblastoma; Prostaglandin D2; Stimulation, Chemical; Time Factors; Tumor Cells, Cultured

Various prostaglandins (PGs) (10 nM-30 microM) were added to NG108-15 cells in culture, and changes in the levels of intracellular cyclic GMP and Ca2+ were investigated. Exposure of the cells to PGF2 alpha, PGD2, and PGE2 (10 microM) transiently increased the cyclic GMP content 7.5-, 3.9-, and 3.1-fold, respectively. Furthermore, the increased levels of cyclic GMP correlated well with the rise in cytosolic free Ca2+ concentrations induced by the PGs. Other PGs (10 microM), including metabolites and synthetic analogs, which had no effect on intracellular Ca2+, failed to increase the cyclic GMP content in the cells. When extracellular Ca2+ was depleted from the culture medium, the PG-induced increase in cyclic GMP level was almost completely abolished. In addition, treatment of the cells with quin 2 tetraacetoxymethyl ester dose-dependently inhibited the PG-induced cyclic GMP formation. The increase in cyclic GMP content caused by treatment of the cells with a high K+ level (50 mM) was completely blocked by voltage-dependent Ca2+ entry blockers, such as verapamil (10 microM), nifedipine (1 microM), and diltiazem (100 microM); however, the PG (10 microM)-induced increase in cyclic GMP content was not affected by such Ca2+ entry blockers. These findings indicate that PG-induced cyclic GMP formation may require the rise in intracellular Ca2+ level and that the voltage-dependent Ca2+ channels may not be involved in the PG-induced rise in Ca2+ content.

Topics: Aminoquinolines; Animals; Calcium; Cyclic GMP; Diltiazem; Dinoprost; Dinoprostone; Fluorescent Dyes; Glioma; Hybrid Cells; Kinetics; Mice; Neuroblastoma; Nifedipine; Potassium; Prostaglandin D2; Prostaglandins; Prostaglandins D; Prostaglandins E; Prostaglandins F; Rats; Tumor Cells, Cultured; Verapamil

Five cultured human glioma cell lines were investigated for their reaction to prostaglandin (PG) D2 and E2. In all cases a suppressive effect on DNA synthesis as assessed by 3H-thymidine incorporation was seen with all test substances as early as six hours after the addition of the compounds in doses of usually 10(-5) M. A dose response curve was generated in four cases and showed an estimated ED 50 of about 5 X 10(-6)M. The effect was most pronounced at 12 hours after which the cultures began to recover except those which had been incubated with PGD2. In those cultures which had been exposed to PGD2 virtually no thymidine incorporation was seen after 24 hours and as long as 72 hours. In another set of experiments, the effect of PGD 2, PGE 2, two synthetic PGD 2 analogues, with a chlorine substitution in position 9 (DACl) or with a fluoride substitution in position 9 (DAF) and a synthetic prostacyclin-analogue (Iloprost) was investigated after single and repeated addition of the compounds. A second administration after 12 hours of incubation did not result in a further decrease in 3H-thymidine incorporation like that observed during that first incubation period. In general the cells recovered after 24 hours total incubation time except those which had received PGD 2 or repeated doses of PGE 2. Only in those cells which had been treated with PGD 2, an almost complete blockade of 3H-thymidine incorporation was seen even after the single administration. Parallel evaluation of the cells by flow cytometry showed effects on cell cycle distribution at different times of the incubation.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Cell Division; Cell Line; Dinoprost; Dinoprostone; Glioma; Humans; Prostaglandin D2; Prostaglandins D; Prostaglandins E; Prostaglandins F; Prostaglandins, Synthetic; Thymidine

The cellular cGMP content increased in response to a variety of receptor agonists, which activate [e.g., prostaglandin (PG) E1, E2, and F2 alpha] or inhibit (e.g., alpha-adrenergic, muscarinic, and opiate agonists) adenylate cyclase in neuroblastoma X glioma hybrid NG108-15 cells. The responses were additive when PGF2 alpha and enkephalin were mixed. The inhibitory guanine nucleotide regulatory protein (Ni) is involved in adenylate cyclase inhibition; this function of Ni is lost when it is ADP-ribosylated by islet-activating protein (IAP), pertussis toxin [H. Kurose, T. Katada, T. Amano, and M. Ui (1983) J. Biol. Chem. 258, 4870-4875]. The cGMP rise induced by stimulation of the receptors linked to adenylate cyclase inhibition was also diminished by IAP; the time course and dose response for the IAP-induced diminution were the same between adenylate cyclase inhibition and cGMP generation. Ni thus appears to mediate guanylate cyclase activation as well as adenylate cyclase inhibition initiated via the same receptors. Melittin also increased cGMP. No additivity was shown when enkephalin and melittin were combined, suggesting that phospholipase A2 might play a role in Ni-mediated guanylate cyclase activation. On the other hand, the PGF2 alpha-induced cGMP rise was associated with increased incorporation of 32Pi into phosphatidylinositol; was not affected by cholera toxin, IAP or forskolin; and showed no additivity when combined with A23187, which increased cGMP by itself. PGs would occupy receptors linked to phosphatidylinositol breakdown, thereby increasing the availability of intracellular Ca2+, which is responsible for guanylate cyclase activation. Thus, dual pathways are proposed for a receptor-mediated cGMP rise in NG108-15 cells.

Topics: Adenylate Cyclase Toxin; Animals; Bacterial Toxins; Calcimycin; Cyclic AMP; Cyclic GMP; Dinoprost; Enkephalins; Glioma; Hybrid Cells; Melitten; Mice; Neuroblastoma; Pertussis Toxin; Phospholipids; Prostaglandins F; Rats; Receptors, Cell Surface; Virulence Factors, Bordetella

The effect of prostaglandin (PG) D2 on neuronal functions was investigated in neuroblastoma X glioma NG108-15 hybrid cells. PGD2 caused a sustained increase in miniature end-plate potentials (MEPPs) recorded from cultured striated muscle cells which had formed junctions with NG108-15 cells. PGD2 initially hyperpolarized and then depolarized NG108-15 cells. The time course of depolarization fitted well to the facilitative phase of MEPPs. The same action on synaptic transmission and membrane potentials was detected with PGF2 alpha but not with PGE1. PGD2 (10(-4)M) produced a 3-fold increase of adenylate cyclase activity in NG108-15 cell homogenates through its receptors that are distinct from those of PGE1 and PGI2. These results show that PGD2 facilitates MEPP frequency from NG108-15 cells due to depolarization, and suggest that PGD2 may act as a physiological neuromodulator for synaptic transmission in vivo.

Topics: Adenylyl Cyclases; Alprostadil; Animals; Cell Line; Dinoprost; Epoprostenol; Glioma; Hybrid Cells; Kinetics; Membrane Potentials; Mice; Muscles; Neuroblastoma; Prostaglandin D2; Prostaglandins D; Prostaglandins E; Prostaglandins F; Rats; Synapses; Synaptic Transmission

Tumour cell-rich platelet-free preparations were isolated from 21 fresh samples of human intracranial tumours using enzymic digestion, followed by discontinuous density gradient centrifugation on Percoll and (14 preparations) adherence on plastic. Of the disaggregated cells 79.8 to 97.7% (mean 86.2%) were tumour cells, and mean cell viability was 82.6%. All the tumours produced prostaglandin (PG), E2, F2 alpha, 6 oxo F1 alpha and Thromboxane B2 during 16 hours of incubation but the amount varied widely. Highest production of PGE2 and TXB2 per 10(5) cells was by the eight meningiomas in which the prostanoid profile closely resembled that of circulating monocytes.

Topics: 6-Ketoprostaglandin F1 alpha; Astrocytoma; Brain Neoplasms; Dinoprost; Dinoprostone; Glioblastoma; Glioma; Humans; Meningeal Neoplasms; Meningioma; Monocytes; Prostaglandins; Prostaglandins E; Prostaglandins F; Thromboxane B2; Thromboxanes