The inhibitory effect of celecoxib on mouse hepatoma H22 cell line on the arachidonic acid metabolic pathwayThis paper is one of a selection of papers published in this special issue entitled “Second International Symposium on Recent Advances in Basic, Clinical, and Social Medicine” and has undergone the Journal's usual peer review process.

2010 ◽  
Vol 88 (4) ◽  
pp. 603-609 ◽  
Author(s):  
Zhigang Xu ◽  
Ming Zhang ◽  
Xiaoyan Lv ◽  
Dan Xiang ◽  
Xuewen Zhang ◽  
...  

Celecoxib is a selective inhibitor of cyclooxygenase-2 (COX-2). It may reduce the risk of cancer formation by affecting the metabolism of arachidonic acid (AA), which has been implicated in the development of cancer. Accordingly, this study was designed to determine the effects of celecoxib on the AA pathway in mouse hepatoma H22 cells. Celecoxib was found to inhibit the proliferation of H22 cells in a dose- and time-dependent manner. Low doses (50 and 100 µmol·L–1) of celecoxib caused an increase in the expression of cytosolic phospholipase A2 (cPLA2), but did not affect the expression of COX-2 in terms of the mRNA and protein levels. Surprisingly, the amount of AA was elevated and the level of prostaglandin E2 (PGE2) was unaltered in the culture supernatant. At higher celecoxib doses (200 and 400 µmol·L–1), the mRNA and protein of both COX-2 and cPLA2 were inhibited. The concentration of AA was increased, and PGE2 level was depressed in H22 cells. The ratio of AA to PGE2 was increased in a dose-dependent manner. Our findings suggest that the imbalance between AA and PGE2, characterized by increased AA at a low dosage and decreased PGE2 at a high dosage of celecoxib, was an important indicator of cytotoxicity of celecoxib on H22 cells.

2003 ◽  
Vol 228 (7) ◽  
pp. 786-794 ◽  
Author(s):  
Wieslaw Kozak ◽  
David M. Aronoff ◽  
Olivier Boutaud ◽  
Anna Kozak

Cytochrome P-450 monooxygenase (epoxygenase)-derived arachidonic acid (AA) metabolites, including 11,12-epoxyeicosatrienoic acid (11,12-EET), possess anti-inflammatory and antipyretic properties. Prostaglandin E2 (PGE2), a cyclooxygenase (COX)-derived metabolite of AA, is a well-defined mediator of fever and inflammation. We have tested the hypothesis that 11,12-EET attenuates synthesis of PGE2 in monocytes, which are the cells that are indispensable for induction of fever and initiation of inflammation. Monocytes isolated from freshly collected rat blood were stimulated with lipopolysaccharide (LPS; 100 ng/2 × 105 cells) to induce COX-2 and stimulate generation of PGE2. SKF-525A, an inhibitor of epoxygenases, significantly augmented the lipopolysaccharide-provoked synthesis of PGE2 in cell culture in a concentration-dependent manner. It did not affect, however, elevation of the expression of COX-2 protein in monocytes stimulated with LPS. 11,12-EET also did not affect the induction of COX-2 in monocytes incubated with lipopolysaccharide. However, 11,12-EET suppressed, in a concentration-dependent fashion, the generation of PGE2 in incubates. Preincubation of a murine COX-2 preparation for 0–5 min with three concentrations of 11,12-EET (1, 5, and 10 μM) inhibited the oxygenation of [14C]-labeled AA by the enzyme. The inhibitory effect of 11,12-EET on COX-2 was time-and-concentration-dependent, suggesting a mechanism-based inhibition. Based on these data, we conclude that 11,12-EET suppresses generation of PGE2 in monocytes via modulating the activity of COX-2. These data support the hypothesis that epoxygenasederived AA metabolites constitute a negative feedback on the enhanced synthesis of prostaglandins upon inflammation.


2003 ◽  
Vol 284 (2) ◽  
pp. C302-C309 ◽  
Author(s):  
Lyne I. Lemieux ◽  
Sherine S. Rahal ◽  
Chris R. J. Kennedy

Increased glomerular prostaglandin E2 (PGE2) production is associated with the progression of diseases such as membranous nephropathy, nephrotic syndrome, and anti-Thy1 nephritis. We investigated the signaling pathways that regulate the synthesis and actions of PGE2 in glomerular podocytes. To study its actions, we assessed the ability of PGE2 to regulate the production of its own precursor, arachidonic acid (AA), in a mouse podocyte cell line. PGE2 dose-dependently reduced phorbol ester (PMA)-mediated AA release. Inhibition of PMA-stimulated AA release by PGE2 was found to be cAMP/PKA-dependent, because PGE2 significantly increased levels of this second messenger, whereas the inhibitory actions of PGE2 were reversed by PKA inhibition and reproduced by the cAMP-elevating agents forskolin and IBMX. PGE2 synthesis in this podocyte cell line increased fourfold at 60 min in response to PMA, coinciding with upregulation of cyclooxygenase (COX)-2 but not COX-1 levels. However, PGE2 synthesis was significantly reduced by COX-1-selective inhibition, yet to a lesser extent by COX-2-selective inhibition. Our findings suggest that PMA-stimulated PGE2 synthesis in mouse podocytes requires both basal COX-1 activity and induced COX-2 expression, and that PGE2 reduces PMA-stimulated AA release in a cAMP/PKA-dependent manner. Such an autocrine regulatory loop might have important consequences for podocyte and glomerular function in the context of renal diseases involving PGE2 synthesis.


Endocrinology ◽  
2005 ◽  
Vol 146 (3) ◽  
pp. 1532-1540 ◽  
Author(s):  
Anne Florin ◽  
Magali Maire ◽  
Aline Bozec ◽  
Ali Hellani ◽  
Sonia Chater ◽  
...  

In the present study we investigated whether fetal exposure to flutamide affected messenger and protein levels of claudin-11, a key Sertoli cell factor in the establishment of the hemotesticular barrier, at the time of two key events of postnatal testis development: 1) before puberty (postnatal d 14) during the establishment of the hemotesticular barrier, and 2) at the adult age (postnatal d 90) at the time of full spermatogenesis. The data obtained show that claudin-11 expression was inhibited in prepubertal rat testes exposed in utero to 2 and 10 mg/kg·d flutamide. However, in adult testes, the inhibition was observed only with 2, and not with 10, mg/kg·d of the antiandrogen. It is shown here that these differences between prepubertal and adult testes could be related to dual and opposed regulation of claudin-11 expression resulting from positive control by androgens and an inhibitory effect of postmeiotic germ cells. Indeed, testosterone is shown to stimulate claudin-11 expression in cultured Sertoli cells in a dose- and time-dependent manner (maximum effect with 0.06 μm after 72 h of treatment). In contrast, postmeiotic germ cells potentially exert a negative effect on claudin-11 expression, because adult rat testes depleted in spermatids (after local irradiation) displayed increased claudin-11 expression, whereas in a model of cocultured Sertoli and germ cells, spermatids, but not spermatocytes, inhibited claudin-11 expression. The apparent absence of claudin-11 expression changes in adult rat testes exposed to 10 mg/kg·d flutamide therefore could result from the antagonistic effects of 1) the inhibitory action of the antiandrogen and 2) the stimulatory effect of the apoptotic germ cells on claudin-11 expression. Together, due to the key role of claudin-11 in the hemotesticular barrier, the present findings suggest that such regulatory mechanisms may potentially affect this barrier (re)modeling during spermatogenesis.


2002 ◽  
Vol 172 (1) ◽  
pp. 95-104 ◽  
Author(s):  
AM Ronco ◽  
PF Moraga ◽  
MN Llanos

We have previously demonstrated that the release of arachidonic acid (AA) from human chorionic gonadotropin (hCG)-stimulated Leydig cells occurs in a dose- and time-dependent manner. In addition, the amount of AA released was dependent on the hormone-receptor interaction and the concentration of LH-hCG binding sites on the cell surface. The present study was conducted to evaluate the involvement of phospholipase A(2) (PLA(2)) and G proteins in AA release from hormonally stimulated rat Leydig cells, and the possible role of this fatty acid in cAMP production. Cells were first prelabelled with [(14)C]AA to incorporate the fatty acid into cell phospholipids, and then treated in different ways to evaluate AA release. hCG (25 mIU) increased the release of AA to 180+/-12% when compared with AA released from control cells, arbitrarily set as 100%. Mepacrine and parabromophenacyl bromide (pBpB), two PLA(2) inhibitors, decreased the hormone-stimulated AA release to 85+/-9 and 70+/-24% respectively. Conversely, melittin, a PLA(2) stimulator, increased the release of AA up to 200% over control. The inhibitory effect of mepacrine on the release of AA was evident in hCG-treated Leydig cells, but not in the melittin-treated cells. To determine if the release of AA was also mediated through a G protein, cells were first permeabilized and subsequently treated with pertussis toxin or GTPgammaS, a non-hydrolyzable analog of GTP. Results demonstrate that GTPgammaS was able to induce a similar level of the release of AA as hCG. In addition, pertussis toxin completely abolished the stimulatory effect of hCG on the release of AA, indicating that a member of the G(i) family was involved in the hCG-dependent release of AA. Cells treated with PLA(2) inhibitors did not modify cAMP production, but exogenously added AA significantly reduced cAMP production from hCG-treated Leydig cells, in a manner dependent on the concentration of AA and hCG. Results presented here suggest an involvement of PLA(2) and G proteins in the release of AA from hCG-stimulated Leydig cells, and under particular conditions, regulation of cAMP production by this fatty acid in these cells.


2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Hai Yang Yu ◽  
Kyoung-Sook Kim ◽  
Young-Choon Lee ◽  
Hyung-In Moon ◽  
Jai-Heon Lee

Oleifolioside A, a new triterpenoid compound isolated fromDendropanax morbiferaLeveille (D. morbifera), was shown in this study to have potent inhibitory effects on lipopolysaccharide (LPS-)stimulated nitric oxide (NO) and prostaglandin E2(PGE2) production in RAW 264.7 macrophages. Consistent with these findings, oleifolioside A was further shown to suppress the expression of LPS-stimulated inducible nitric oxide synthase (iNOS) and cyclooxigenase-2 (COX-2) in a dose-dependent manner at both the protein and mRNA levels and to significantly inhibit the DNA-binding activity and transcriptional activity of NF-κB in response to LPS. These results were found to be associated with the inhibition of the degradation and phosphorylation of IκB-αand subsequent translocation of the NF-κB p65 subunit to the nucleus. Inhibition of NF-κB activation by oleifolioside A was also shown to be mediated through the prevention of p38 MAPK and ERK1/2 phosphorylation. Taken together, our results suggest that oleifolioside A has the potential to be a novel anti-inflammatory agent capable of targeting both the NF-κB and MAPK signaling pathways.


PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1925 ◽  
Author(s):  
Jing Shao ◽  
Hongxiang Wang ◽  
Guolin Yuan ◽  
Zhichao Chen ◽  
Qiubai Li

Cytochrome P450 (CYP) epoxygenases and the metabolites epoxyeicosatrienoic acids (EETs) exert multiple biological effects in various malignancies. We have previously found EETs to be secreted by multiple myeloma (MM) cells and to be involved in MM angiogenesis, but the role of the arachidonic acid cytochrome P450 epoxygenase pathway in the proliferation and mobility of MM cells remains unknown. In the present study, we found that MM cell lines generated detectable levels of 11,12-EET/14,15-EET and that increased levels of EETs were found in the serum of MM patients compared to healthy donors. The addition of exogenous EETs induced significantly enhanced proliferation of MM cells, whereas 17-octadecynoic acid (17-ODYA), an inhibitor of the CYP epoxygenase pathway, inhibited the viability and proliferation of MM cells. Moreover, this inhibitory effect could be successfully reversed by exogenous EETs. 17-ODYA also inhibited the motility of MM cells in a time-dependent manner, with a reduction of the gelatinolytic activity and protein expression of the matrix metalloproteinases (MMP)-2 and MMP-9. These results suggest the CYP epoxygenase pathway to be involved in the proliferation and invasion of MM cells, for which 17-ODYA could be a promising therapeutic drug.


2012 ◽  
Vol 32 (suppl_1) ◽  
Author(s):  
Liang Hu ◽  
Michael A Nardi ◽  
Michael Merolla ◽  
Yajaira Suarez ◽  
Jeffrey Berger

Arachidonic acid (AA) is converted to thromboxane A2 via the cyclooxygenase pathway; however its exact mechanism of platelet activation is uncertain. Inhibition of this pathway via aspirin highlights the importance of this pathway in decreasing thrombotic events. In the present study, we investigate the effect of AA on platelet activity indicators (leukocyte- and monocyte-platelet aggregation [LPA, MPA] and reticulated platelets [RP]), as well as the expression (mRNA and protein) of platelet markers PF4 and Par-1, previously well established platelet transcripts with quantitative determinations. To this end, whole blood was incubated with AA (150mM) for 30 min at room temperature in the absence or presence of aspirin (1mM) prior to addition of antibodies for platelet activity indicators, and isolating platelets for mRNA and protein expression. LPA and MPA were significantly increased after AA stimulation in a dose dependent manner, and were inhibited by aspirin treatment. AA significantly increased PF4 and Par-1 protein level as determined by flow cytometry and western blot assays. Pretreatment with aspirin also attenuated this increase in protein levels. Surprisingly, AA stimulation significantly increased thiazole orange staining (a measure of nucleic acids), another marker of increased platelet activity. Importantly, these results suggest that AA-mediated platelet activation produced an overall increase in platelet total RNA content. To confirm these findings, we analyzed the mRNA expression of PF4 and Par-1 by quantitative real time PCR from platelets treated with AA. Interestingly, AA significantly up-regulated the platelet mRNA transcripts of PF4 and Par-1 by 40% to 60%, and pretreatment with aspirin completely attenuated this effect supporting the specificity of the AA effect on platelet RNA. Altogether, these data suggest that platelet mRNA is affected by AA stimulation, which is attenuated by pretreatment with aspirin. However, the mechanisms responsible for the increased mRNA levels and expression of PF4 and Par-1 (processing of pre-RNA to mRNA) require further investigation. Importantly, our findings provide novel insight regarding platelet activation and a better understanding of mediators in the processes of thrombosis and hemostasis.


2004 ◽  
Vol 24 (8) ◽  
pp. 926-933 ◽  
Author(s):  
Kon Chu ◽  
Sang-Wuk Jeong ◽  
Keun-Hwa Jung ◽  
So-Young Han ◽  
Soon-Tae Lee ◽  
...  

The selective cyclooxygenase-2 (COX-2) inhibitor has been reported to have antiinflammatory, neuroprotective, and antioxidant effects in ischemia models. In this study, the authors examined whether a selective COX-2 inhibitor (celecoxib) reduces cerebral inflammation and edema after intracerebral hemorrhage (ICH), and whether functional recovery is sustained with longer treatment. ICH was induced using collagenase in adult rats. Celecoxib (10 or 20 mg/kg) was administered intraperitoneally 20 minutes, 6 hours, and 24 hours after ICH and then daily thereafter. Seventy-two hours after ICH induction, the rats were killed for histologic assessment and measurement of brain edema and prostaglandin E2. Behavioral tests were performed before and 1, 7, 14, 21, and 28 days after ICH. The brain water content of celecoxib-treated rats decreased both in lesioned and nonlesioned hemispheres in a dose-dependent manner. Compared with the ICH-only group, the number of TUNEL-positive, myeloperoxidase-positive, or OX42-positive cells was decreased in the periphery of hematoma and brain prostaglandin E2 level was reduced in the celecoxib-treated group. Celecoxib-treated rats recovered better by the behavioral tests at 7 days after ICH throughout the 28-day period, and the earlier the drug was administered, the better the functional recovery. Evidence of similar effects in an autologous blood–injected model showed that direct collagenase toxicity was not the major cause of inflammation or cell death. These data suggest that celecoxib treatment after ICH reduces prostaglandin E2 production, brain edema, inflammation, and perihematomal cell death in the perihematomal zone and induces better functional recovery.


2008 ◽  
Vol 294 (6) ◽  
pp. F1441-F1447 ◽  
Author(s):  
ZhiJian Wang ◽  
Yuan Wei ◽  
John R. Falck ◽  
Krishnam Raju Atcha ◽  
Wen-Hui Wang

We used the patch-clamp technique to study the effect of arachidonic acid (AA) on basolateral 18-pS K channels in the principal cell of the cortical collecting duct (CCD) of the rat kidney. Application of AA inhibited the 18-pS K channels in a dose-dependent manner and 10 μM AA caused a maximal inhibition. The effect of AA on the 18-pS K channel was specific because application of 11,14,17-eicosatrienoic acid had no effect on channel activity. Also, the inhibitory effect of AA on the 18-pS K channels was abolished by blocking cytochrome P-450 (CYP) epoxygenase with N-methylsulfonyl-6-(propargyloxyphenyl)hexanamide (MS-PPOH) but was not affected by inhibiting CYP ω-hydroxylase or cyclooxygenase. The notion that the inhibitory effect of AA was mediated by CYP epoxygenase-dependent metabolites was further supported by the observation that application of 100 nM 11,12-epoxyeicosatrienoic acid (EET) mimicked the effect of AA and inhibited the basolateral 18-pS K channels. In contrast, addition of either 5,6-, 8,9-, or 14,15-EET failed to inhibit the 18-pS K channels. Moreover, application of 11,12-EET was still able to inhibit the 18-pS K channels in the presence of MS-PPOH. This suggests that 11,12-EET is a mediator for the AA-induced inhibition of the 18-pS K channels. We conclude that AA inhibits basolateral 18-pS K channels by a CYP epoxygenase-dependent pathway and that 11,12-EET is a mediator for the effect of AA on basolateral K channels in the CCD.


1999 ◽  
Vol 8 (6) ◽  
pp. 287-294 ◽  
Author(s):  
Pravit Akarasereenont ◽  
Kitirat Techatrisak ◽  
Sirikul Chotewuttakorn ◽  
Athiwat Thaworn

Prostaglandins (PGS) have numerous cardiovascular and inflammatory effects. Cyclooxygenase (COX), which exists as COX-1 and COX-2 isoforms, is the first enzyme in the pathway in which arachidonic acid is converted to PGs. Prostaglandin E2 (PGE2) exerts a variety of biological activities for the maintenance of local homeostasis in the body. Elucidation of PGE2 involvement in the signalling molecules such as COX could lead to potential therapeutic interventions. Here, we have investigated the effects of PGE2 on the induction of COX-2 in human umbilical vein endothelial cells (HUVEC) treated with interleukin-1β (IL-1β 1 ng/ml). COX activity was measured by the production of 6-keto-PGF1α, PGE2, PGF2α and thromboxane B2 (TXB2) in the presence of exogenous arachidonic acids (10 μM for 10 min) using enzyme immunoassay (EIA). COX-1 and COX-2 protein was measured by immunoblotting using specific antibody. Untreated HUVEC contained only COX-1 protein while IL-1β treated HUVEC contained COX-1 and COX-2 protein. PGE2 (3 μM for 24 h) did not affect on COX activity and protein in untreated HUVEC. Interestingly, PGE2 (3 μM for 24 h) can inhibit COX-2 protein, but not COX-1 protein, expressed in HUVEC treated with IL1 β. This inhibition was reversed by coincubation with forskolin (100 μM). The increased COX activity in HUVEC treated with IL-1β was also inhibited by PGE2 (0.03, 0.3 and 3 μM for 24 h) in a dose-dependent manner. Similarly, forskolin (10, 50 or 100 μM) can also reverse the inhibition of PGE2 on increased COX activity in IL-1β treated HUVEC. The results suggested that (i) PGE2 can initiate negative feedback regulation in the induction of COX-2 elicited by IL-1β in endothelial cells, (ii) the inhibition of PGE2 on COX-2 protein and activity in IL-1β treated HUVEC is mediated by cAMP and (iii) the therapeutic use of PGE2 in the condition which COX-2 has been involved may have different roles.


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