Effects Of Cyclooxygenase Inhibitors Research Articles

Abstract 4960: COX-2 inhibition with celecoxib delays the progression of invasive mammary carcinoma in a murine model of collagen dense stroma.

Abstract Breast cancer is the most common invasive cancer in women causing over 40,000 deaths yearly in the United States. Increased mammographic density correlates with over four-fold greater risk for breast cancer, making it one of the most important risk factors known for this disease. High breast density is correlated to increased collagen in the breast tissue, and we have found that increased collagen in the Col1a1tm1jae mouse model promotes mammary tumor formation and progression. Elevated collagen density in vitro increases expression of PTGS2 (prostaglandin-endoperoxide synthase 2), the gene for COX-2, by over four fold. COX-2 over-expression is observed in 40% of invasive breast carcinoma cases and correlates with poor prognosis. Based on these findings, we hypothesized that inhibition of COX-2 may be an effective therapy in the context of mammary tumors arising in dense tissue. Celecoxib is a selective non-steroidal anti-inflammatory drug (NSAID) that specifically inhibits COX-2. To understand the mechanism by which COX-2 affects cell signaling and response to collagen matrix density, we utilized our previously characterized model of MMTV-PyVT tumors on a wild type (wt) or Col1a1tm1jae background. Col1a1tm1jae heterozygote and wt littermates were randomly assigned at 11 weeks of age to treatment with placebo or celecoxib at 400mg per kilogram body weight. Oral treatment was given daily for 21 days. We found that MMTV-PyVT tumors responded to celecoxib in a manner that is regulated by matrix density (p-value <.0001). Tumors that arose on the dense Col1a1tm1jae background were larger and more invasive (p-value <.0001). Endpoint tumor size was diminished in mice treated with a daily dose of celecoxib, which delayed the development of tumors and changed the structure of the dense matrix. The effect of celecoxib was not as prominent for masses which developed on the low density wt background. Immunohistochemistry of relevant markers in these tissues is ongoing and will further our understanding of the effects of COX-2 inhibition in dense matrices. These findings suggest that COX-2 has a direct role in modulating the configuration of dense matrices which promote a more invasive cancer effect. Moreover, these findings suggest that COX-2 may be an effective therapeutic target for women with dense breast tissue. Citation Format: Karla Esbona, David R. Inman, Kevin W. Eliceiri, Lee G. Wilke, Patricia J. Keely. COX-2 inhibition with celecoxib delays the progression of invasive mammary carcinoma in a murine model of collagen dense stroma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4960. doi:10.1158/1538-7445.AM2013-4960

Abstract 2746: Microsomal prostaglandin E2 synthase-1 may provide a novel specific therapeutic target in neuroblastoma.

Abstract Background: Neuroblastoma (NB) cells are enriched in the omega-6 fatty acid arachidonic acid, the substrate for the cyclooxygenase (COX) enzymes and prostaglandin biosynthesis. The inducible isoform, COX-2 is overexpressed in NB and NB cells produce prostaglandin E2 (PGE2) that acts as an autocrine and/or paracrine survival and proliferation factor. Downstream of the COX enzymes, specific synthases are responsible for the production of the respective prostaglandins. Microsomal prostaglandin E2 synthase-1 (mPGES-1) specifically converts PGH2 to PGE2 and is thought to primarily couple to COX-2. The aim of this study was to investigate if inhibition of mPGES-1 could represent an alternative therapeutic approach to COX- inhibition in NB. Methods: Western blot and immunohistochemistry were used for protein detection. Cell viability of seven NB cell-lines treated with the mPGES-1 inhibitor CAY1052 was determined by MTT-assay. Stable mPGES-1 knockdown SK-N-BE2 clones were established using shRNA and the clonogenic capacity was analysed by clonogenic assay. To study the in vivo effect of COX inhibition, four week old homozygous TH-MYCN mice were treated with 10mg/L diclofenac for two weeks. Ex vivo analyses of COX-metabolites in tumors were performed by LC-MS/MS. Results: Expression of mPGES-1 in human NB tumors and in NB cell lines could be detected. Inhibition of mPGES-1 reduced NB cell growth in vitro and knockdown of mPGES-1 significantly reduced the clonogenic capacity. Expression of COX-1, COX-2 and mPGES-1 in TH-MYCN tumors could be detected and treatment with the dual COX-inhibitor diclofenac significantly reduced tumour weight, compared to untreated animals. Ex vivo analysis of tumor tissues from treated animals revealed a significantly decreased level of COX metabolites compared to controls. The expression of mPGES-1was not affected by the treatment. Furthermore, cells staining positive for cleaved caspase-3 were more prevalent in treated tumors indicating apoptosis Induction. Conclusion: We found that mPGES-1 is expressed in NB, with a potential role for PGE2 synthesis and tumor growth. mPGES-1 represents an alternative therapeutic target for inhibiting NB growth through specific PGE2 inhibition and the TH-MYCN model is well suited for in vivo studies with this purpose. Citation Format: Anna Kock, Agnes Rasmuson, Marina Korotkova, Helena Idborg, John Inge Johnsen, Per-Johan Jakobsson, Per Kogner. Microsomal prostaglandin E2 synthase-1 may provide a novel specific therapeutic target in neuroblastoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2746. doi:10.1158/1538-7445.AM2013-2746

Effects of COX-2 inhibitor on ventilator-induced lung injury in rats

Mechanical ventilation especially with large tidal volume has been demonstrated to activate inflammatory response inducing lung injury, which could be attenuated by cyclooxygenase (COX)-2 inhibitors. As the main small integral membrane proteins that selectively conduct water molecules' transportation, aquaporin (AQP)-1 downregulation significantly related to lung edema and inflammation. This study aims to investigate the role of AQP1 in ventilator-induced lung injury in rats and evaluates the effects of COX-2 inhibition. Forty rats were allocated into four groups, where rats in Groups LD (low volume+DMSO) and LN (low volume+NS-398) were given intravenously 2ml DMSO and 8mg/kg NS-398 (a specific COX-2 inhibitor, dissolved in 2ml DMSO) before 4-hour lower tidal volume ventilation (8ml/kg), respectively, while DMSO and NS-398 were administrated in the same manner before 4-hour injurious ventilation (40ml/kg) in Groups HD (high volume+DMSO) and HN (high volume+NS-398). The arachidonic acid metabolites (6-keto prostaglandin F1α, thromboxane B2), inflammatory cytokines (tumor necrosis factor-α, interleukin-1β, 6, 8) and total protein levels in bronchoalveolar lavage (BAL) fluid and COX-2 mRNA and AQP1 protein expression in lung tissue were detected; water content and lung morphology were also evaluated. Compared to Groups LD and LN, the rats in Groups HD and HN suffered obvious lung morphological changes with higher wet-to-dry weight ratio and lung injury score, and the levels of arachidonic acid metabolites, inflammatory cytokines and total protein in BAL fluid were increased, the expression of COX-2 mRNA was significantly upregulated and AQP1 protein was downregulated in lung tissue (p<0.05). The changes in BAL fluid and the severity of lung injury were attenuated, and AQP1 expression was upregulated in Group HN as compared to HD (p<0.05). Ventilation with large tidal volume causes inflammatory mediator production and AQP1 downregulation, which could be attenuated by COX-2 inhibition.

The anti‐inflammatory effect of cyclooxygenase inhibitors in fibroblast‐like synoviocytes from the human temporomandibular joint results from the suppression of PGE2 production

Background Non-steroidal anti-inflammatory drugs (NSAIDs) have been widely used for the management of pain and inflammation. However, little remains known about the effects of NSAIDs on synovitis of the human temporomandibular joint (TMJ). The aims of this study were to investigate the potential anti-inflammatory effects of NSAIDs on synovitis of the TMJ and the inflammatory effects of PGE2 on fibroblast-like synoviocytes (FLS) derived from the TMJ.Methods Human synovial tissue was obtained from patients with internal derangement who underwent arthroscopy of the TMJ. FLSs were prepared from the tissues using the outgrowth method. A COX inhibitor (indomethacin or celecoxib) was added to the IL-1β-stimulated cells in culture. The cells were also stimulated with PGE2 or an EP agonist. The PGE2 production and COX-2 and IL-6 expression levels were examined using enzyme-linked immunosorbent assays, real-time PCR, and a microarray analysis.Results COX inhibitors decreased not only PGE2 production, but also the expression of COX-2 and IL-6 in FLS stimulated with IL-1β. EP2 and EP4 were both expressed in the FLS, and the treatment with EP2 and EP4 agonists induced IL-6 production in these cells.Conclusion The COX inhibitors indomethacin and celecoxib reduce the expression of inflammatory factors, such as COX-2 and IL-6, in FLS from the TMJ via suppression of PGE2 production. EP2 and EP4 were the main receptors for PGE2 present in the FLS. The approach used in this study may be useful for revealing how drugs such as NSAIDs affect the cellular functions of FLS from the TMJ.

COX-2-derived prostaglandins do not contribute to coronary flow regulation in diabetic rats: Distinct secretion patterns of PGI2 and PGE2

The role of cyclooxygenase-2 (COX-2) in restoring the functions of impaired endothelium is attracting considerable attention, notably the function of COX-2-derived vasodilatory prostaglandins is disputed in the context of the regulation function in the impaired vascular beds. We have examined the hypothesis that COX-2 activity contributes more to vasodilation in hyperglycemic animals than in healthy counterparts, and that COX-2 derived vasodilatory prostaglandins (PGI2 and PGE2) are responsible for this effect. Using the Langendorff heart perfusion system, the effects of COX-2 inhibition were monitored on both basal and bradykinin-induced coronary flows in Sprague–Dawley rats given 8-week streptozotocin-induced diabetes and in age-matched controls (n=15). Secretions of PGI2 and PGE2, both total and the COX-2 dependent pools, have also been compared. The selective COX-2 inhibitor, N-[2-(cyclohexyloxy)-4-nitrophenyl]-methanesulfonamide (NS-398), had no effect on coronary flow in the diabetic group of animals. Thus, the compensatory role of COX-2 in regulation of vascular tone in experimental diabetes found in other experimental models was not confirmed. However, COX-2 activity significantly contributed to PGI2 synthesis in healthy rats, with prostacyclin secretion being two-fold decreased by NS-398. Contrary to our hypothesis, neither prostacyclin nor PGE2 production differed between the experimental groups under the basal conditions. Bradykinin had no effect on the secretion of PGI2 in either group, but increased PGE2 synthesis in healthy animals, although not in the streptozotocin group. PGE2 production in response to bradykinin was COX-2-dependent in control animals. We conclude that, in rats with 8-week streptozotocin-induced diabetes, the activity of COX-2 in coronary vasculature is not significantly enhanced.

Phenolics content and antioxidant and anti-inflammatory activities of legume fractions

Two faba bean (Vicia faba L.) subspecies major and minor and lentil seeds grown in Algeria were separated into cotyledons and hulls. These fractions, together with their corresponding whole seeds, were extracted with two solvents, aqueous (70%) acetone and (80%) ethanol, and evaluated for antioxidant activity in relation to their phenolic contents. Acetone selectively extracted tannins from faba beans. The hulls always exhibited high antioxidant activity, measured using the reducing power (RP), antiradical activity (DPPH) or oxygen radical absorbance capacity (ORAC) assays. Aqueous ethanol (80%) extract of lentil hulls exhibited high antioxidant and anti-inflammatory activities preferentially inhibiting 15-LOX (IC50, 55μg/ml), with moderate COX-1 (IC50, 66μg/ml) and COX-2 (IC50, 119μg/ml) inhibitory effects on the COX pathway, whereas faba bean hull extracts exerted relatively mild LOX inhibitory activity.

The effects of cyclooxygenase inhibitors on the brain inflammatory response following traumatic brain injury in rats.

Cytokines such as IL-1β are involved in inflammatory responses. This study evaluated the role of two different kinds of drugs (ibuprofen and celecoxib) on brain IL-10 and IL-1β after traumatic brain injury (TBI) in male rats. Rats were assigned into 6 groups: intact, sham, TBI, and treated rats with vehicle, celecoxib or iboprophen. Cytokine concentrations were quantified by ELISA kits. Groups showed no significant difference in brain IL-10 either after TBI induction or after treatment with ibuprofen or celecoxib. Serum IL-10 in vehicle or ibuprofen treated animals was lower than in sham groups (P< 0.01). Brain IL-1β decreased after treatment by ibuprofen or celecoxib (P< 0.001). There was no statistical difference in serum IL-1β in TBI and intact. Serum IL-1β significantly decreased in rats that received celecoxib compared to TBI group (P< 0.01). Based on our study IL-1β can decrease through both cyclooxygenase 1 (COX-1) and COX-2 pathway but serum IL-1β can decrease only by COX-2 pathway.

Effects of Cyclooxygenase Inhibitors in Combination with Taxol on Expression of Cyclin D1 and Ki-67 in a Xenograft Model of Ovarian Carcinoma

The present study was designed to investigate the effects of cyclooxygenase (COX) inhibitors in combination with taxol on the expression of cyclin D1 and Ki-67 in human ovarian SKOV-3 carcinoma cells xenograft-bearing mice. The animals were treated with 100 mg/kg celecoxib (a COX-2 selective inhibitor) alone, 3 mg/kg SC-560 (a COX-1 selective inhibitor) alone by gavage twice a day, 20 mg/kg taxol alone by intraperitoneally (i.p.) once a week, or celecoxib/taxol, SC-560/celecoxib, SC-560/taxol or SC-560/celecoxib/taxol, for three weeks. To test the mechanism of the combination treatment, the index of cell proliferation and expression of cyclin D1 in tumor tissues were determined by immunohistochemistry. The mean tumor volume in the treated groups was significantly lower than control (p < 0.05), and in the three-drug combination group, tumor volume was reduced by 58.27% (p < 0.01); downregulated cell proliferation and cyclin D1 expression were statistically significant compared with those of the control group (both p < 0.01). This study suggests that the effects of COX selective inhibitors on the growth of tumors and decreased cell proliferation in a SKOV-3 cells mouse xenograft model were similar to taxol. The three-drug combination showing a better decreasing tendency in growth-inhibitory effect during the experiment may have been caused by suppressing cyclin D1 expression.

Effect of cyclooxygenase-2 inhibitor in anti-leukemia

Cyclooxygenase-2 (COX-2) plays an important role in the development of leukemia.COX-2 inhibitor plays a certain anti-leukemia role in the process.Many studies show that COX-2 inhibitor plays antileukemia role by inhibiting the proliferation of leukemia cell,promoting apoptosis,affecting cell cycle,inhibiting cell metastasis and reversing cell drug resistance and so on.Therefore,the researches about the anti-leukemia mechanisms of COX-2 inhibitor will provide a new target in clinical prevention and treatment of leukemia. Key words: Leukemia; Cell cycle; Apoptosis

The Role of Cyclooxygenase-2 in Mechanical Ventilation–Induced Lung Injury

Mechanical ventilation is necessary for patients with acute respiratory failure, but can cause or propagate lung injury. We previously identified cyclooxygenase-2 as a candidate gene in mechanical ventilation-induced lung injury. Our objective was to determine the role of cyclooxygenase-2 in mechanical ventilation-induced lung injury and the effects of cyclooxygenase-2 inhibition on lung inflammation and barrier disruption. Mice were mechanically ventilated at low and high tidal volumes, in the presence or absence of pharmacologic cyclooxygenase-2-specific inhibition with 3-(4-methylsulphonylphenyl)-4-phenyl-5-trifluoromethylisoxazole (CAY10404). Lung injury was assessed using markers of alveolar-capillary leakage and lung inflammation. Cyclooxygenase-2 expression and activity were measured by Western blotting, real-time PCR, and lung/plasma prostanoid analysis, and tissue sections were analyzed for cyclooxygenase-2 staining by immunohistochemistry. High tidal volume ventilation induced lung injury, significantly increasing both lung leakage and lung inflammation relative to control and low tidal volume ventilation. High tidal volume mechanical ventilation significantly induced cyclooxygenase-2 expression and activity, both in the lungs and systemically, compared with control mice and low tidal volume mice. The immunohistochemical analysis of lung sections localized cyclooxygenase-2 expression to monocytes and macrophages in the alveoli. The pharmacologic inhibition of cyclooxygenase-2 with CAY10404 significantly decreased cyclooxygenase activity and attenuated lung injury in mice ventilated at high tidal volume, attenuating barrier disruption, tissue inflammation, and inflammatory cell signaling. This study demonstrates the induction of cyclooxygenase-2 by mechanical ventilation, and suggests that the therapeutic inhibition of cyclooxygenase-2 may attenuate ventilator-induced acute lung injury.

Abstract 4663: The cyclooxygenase-2 inhibitor, celecoxib, suppresses proliferation and induces apoptosis in endometrial cancer cells

Abstract INTRODUCTION: Obesity is associated with increased risk and worse outcomes for women with endometrial cancer. Inflammation may play a critical role in obesity-driven cancers; thus, the anti-inflammatory effects of COX-2 inhibitors may be a novel treatment strategy that is particularly beneficial in endometrial cancer patients. As a result, our objective was to evaluate the effect of COX-2 inhibitors on proliferation and apoptosis in endometrial cancer cell lines. METHODS: Two endometrial cancer cell lines (ECC-1 and Ishikawa) were used in these studies. Cell proliferation was assessed by MTT assay after exposure to the COX-2 inhibitor, celecoxib. Cell cycle progression was evaluated by flow cytometry. Apoptosis was assessed by ELISA for caspase-3. hTERT mRNA expression was assessed by real-time PCR. Western immunoblotting was performed to determine the effect of celecoxib on COX-2 expression in the endometrial cancer cell lines. RESULTS: Celecoxib significantly inhibited proliferation in a dose-dependent manner in both endometrial cancer cell lines (IC50 5-10 μM for ECC-1, 10-20 μM for Ishikawa; p&amp;lt;0.005 for each). Treatment with celecoxib resulted in G1 cell cycle arrest, induction of apoptosis and inhibition of hTERT mRNA expression. Western immunoblot analysis demonstrated that celecoxib treatment suppresses COX-2 expression in both endometrial cancer cell lines. CONCLUSION: Celecoxib potently inhibits cell growth via G1 arrest, decreases telomerase activity and increases apoptotic cell death in endometrial cancer cells. This work suggests that celecoxib may be a novel chemotherapeutic agent for endometrial cancer prevention and treatment, especially given the interplay between obesity, inflammation and cancer risk. 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 4663. doi:1538-7445.AM2012-4663

Modulation of TTX-sensitive voltage-dependent Na+ channels by β-bungarotoxin in rat cerebellar neurons

BackgroundThe modulation of voltage-dependent Na+ channels by lipid metabolites such as arachidonic acid or eicosanoids plays a role in physiological functions as well as in degenerative diseases. So far TTX-resistant channels were found mainly to be regulated by lipid metabolites.ResultsWe investigated the lipid-dependent modulation of TTX-sensitive (TTX-s) Na+ channels using β-bungarotoxin (β-BuTX, 10 pM), which has an intrinsic phospholipase-A2 activity, and indomethacin (10 μM), which blocks cyclooxygenase activity in primary cerebellar neurons. To investigate TTX-s Na+ channels, whole-currents were measured under K+-free conditions and blocked by 10 nM TTX. The currents resulting from calculating the difference of currents measured in the presence and the absence of TTX were used for further analysis. Application of indomethacin mainly changed the current kinetics but has only minor effects on voltage-dependence. In contrast β-BuTX increased the maximal current amplitude and shifted the voltage-dependent activation towards more negative potentials. The effects of β-BuTX were blocked by indomethacin. Analysis of lipid metabolites which accumulate by treatment with β-BuTX using MALDI-TOF MS showed an increase of cyclooxygenase reaction products in relation to arachidonic acid.ConclusionsIn summary, we conclude that TTX-sensitive Na+ channels can be directly modulated by cyclooxygenase reaction products leading to higher activity at less depolarized potentials and subsequent higher excitability of neurons. Since activation of cyclooxygenase is also involved in pathways leading to apoptotic cells death this could play a role in degenerative diseases of the CNS and highlights a possible protective effect of cyclooxygenase inhibition.

Effect of selective and non-selective cyclooxygenase inhibitors on doxorubicin-induced cardiotoxicity and nephrotoxicity in rats

Context: Doxorubicin (DX) is a highly effective chemotherapeutic agent used widely in the treatment of solid tumors; however, its optimal use was associated with cardiotoxicity and nephrotoxicity. The exact mechanism of DX-induced cardiotoxicity and nephrotoxicity is not fully explored. Induction of cyclooxygenase-2 (COX-2) activity in either cardiac or renal tissue by DX has been previously reported, indicating a possible role of COX-2 in DX-induced tissue injury. However, the nature of this role in either tissue injury is an issue of controversy.Objective: This study was the first that simultaneously evaluated the effects of a selective COX-2 inhibitor, nimesulide, and a non-selective COX-inhibitor, indomethacin, on DX-induced cardiotoxicity and nephrotoxicity in male Wistar rats.Materials and methods: Rats were allocated into four groups. Control group, DX group (received 15 mg/kg, ip), DX + nimesulide (10 mg/kg/day, po) group, and DX + indomethacin (2 mg/kg/day, po) group. Nimesulide and indomethacin were started at the same day of DX injection and continued for 5 days.Results: The results of the present study showed that inhibition of COX-2 either by selective or non-selective COX-2 inhibitor ameliorated DX-induced cardiotoxicity but aggravated DX-induced nephrotoxicity in rats, as evidenced biochemically and histopathologically.Discussion and conclusion: Our study indicates that production of COX-2 is organ specific; consequently, the differential effect of COX-inhibitors should be considered in DX-treated patients. However, a wide scale experiment is needed for further confirmation and testing other members of COX-inhibitors (e.g. celecoxib and diclofenac).

Effects of cyclooxygenase inhibitors on survival time in ovarian cancer xenograft-bearing mice

The present study was designed to investigate whether cyclooxygenase (COX) inhibitors (coxibs) could prolong survival time by attenuating the tumor growth of ovarian cancer xenograft-bearing mice. Tumor growth and survival time were observed and compared in mice which were treated with a COX-1 inhibitor (SC-560) and a COX-2 inhibitor (celecoxib) every other day for a 21 day period from the day of tumor formation. The trial lasted a total of 121 days. The combination therapy resulted in statistically significant inhibition of tumor size compared with the control group (P<0.05). Additionally, single treatment of SC-560 or celecoxib significantly prolonged the mean survival time of mice compared with the control group (P<0.05). We suggest that COX-1 and COX-2 inhibitors may improve survival and inhibit tumor growth, and that the tumor growth inhibition by coxibs may be the contributing factor for the prolonged survival time in mouse xenograft models.

Celecoxib, a selective cyclooxygenase-2 inhibitor, lowers plasma cholesterol and attenuates hepatic lipid peroxidation during carbon-tetrachloride–associated hepatotoxicity in rats

Cyclooxygenase-2 (COX-2) expression and prostaglandin production are suggested to play important, complex roles in the pathogenesis of various liver diseases. Studies on the effects of COX-2 inhibitors on the progression of liver fibrosis present controversial results, and the proposed therapeutic potential of these agents in chronic liver disease is predicated largely on their effectiveness in modulating hepatic stellate cell activation in vitro. This study investigated the modulatory effect of celecoxib, a selective COX-2 inhibitor, in CCl4-mediated hepatotoxicity in rats. Thirty Wistar albino rats, weighing 120–180 g, were assigned into five groups of 6 rats/group. Groups 1 and 2 received saline (10 mL/kg) and CCl4 (80 mg/kg), respectively. Group 3 was given celecoxib (5.7 mg/kg), whereas groups 4 and 5 were pretreated with 2.9 and 5.7 mg/kg/day of celecoxib, respectively, 1 hour before CCl4 treatment. Plasma aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase activities increased significantly by 118.5, 150.0, and 51.3%, respectively, with an accompanying decrease (P < 0.05) in total protein and albumin after CCl4 treatment. Hepatotoxicity was associated with a significant increase in plasma cholesterol, hepatic lipid peroxidation (LPO), and severe hepatic necrosis with marked fatty and cellular (i.e., mononuclear cells) infiltration. Although celecoxib neither reduced CCl4-induced increases in marker enzymes of hepatotoxicity nor significantly attenuated hepatic necrosis, it, however, was effective in reducing elevated cholesterol by 16.5 and 20.8% and LPO by 12.9 and 35.5% at 2.9 and 5.7 mg/kg, respectively. Data suggest that COX-2 inhibitors may be effective in controlling hypercholesterolemia and peroxidative changes associated with liver injury.

Effects of cyclooxygenase inhibition on cardiovascular function in a hypercholesterolemic swine model of chronic ischemia

The cardiovascular effects of cyclooxygenase (COX) inhibition remain controversial, especially in the setting of cardiovascular comorbidities. We examined the effects of nonselective and selective COX inhibition on cardiovascular function in a hypercholesterolemic swine model of chronic ischemia. Twenty-four intact male Yorkshire swine underwent left circumflex ameroid constrictor placement and were subsequently given either no drug (HCC; n = 8), a nonselective COX inhibitor (440 mg/day naproxen; HCNS; n = 8), or a selective COX-2 inhibitor (200 mg/day celecoxib; HCCX; n = 8). After 7 wk, myocardial functional was measured and myocardium from the nonischemic ventricle and ischemic area-at-risk (AAR) were analyzed. Regional function as measured by segmental shortening was improved in the AAR of HCCX compared with HCC. There was no significant difference in perfusion to the nonischemic ventricle between groups, but myocardial perfusion in the AAR was significantly improved in the HCCX group compared with controls at rest and during pacing. Endothelium-dependent microvessel relaxation was diminished by ischemia in HCC animals, but both naproxen and celecoxib improved vessel relaxation in the AAR compared with controls, and also decreased the vasoconstrictive response to serotonin. Thromboxane levels in the AAR were decreased in both HCNS and HCCX compared with HCC, whereas prostacyclin levels were decreased only in HCNS, corresponding to a decrease in prostacyclin synthase expression. Chronic ischemia increased apoptosis in Troponin T negative cells and intramyocardial fibrosis, both of which were reduced by celecoxib administration in the AAR. Capillary density was decreased in both the HCNS and HCCX groups. Protein oxidative stress was decreased in both HCNS and HCCX, whereas lipid oxidative stress was decreased only in the HCCX group. Thus nonselective and especially selective COX inhibition may have beneficial myocardial effects in the setting of hypercholesterolemia and chronic ischemia. Whether these effects modulate cardiovascular risk in patients taking these drugs remains to be seen, but evidence to date suggests that they do not.

Effect of cyclooxygenase inhibition on CXCR3 ligand secretion in breast cancer.

45 Background: In murine cancer models, the two IFN-γ inducible chemokines CXCL9 and CXCL10, those bind to the common receptor CXCR3, recruit NK cells and tumor-suppressive lymphocytes into the tumor site and impair tumor growth and metastatic spread. In human breast cancer (BC), we and others have shown that high levels of CXCL9 mRNA correlate with favorable prognosis and the number of infiltrating lymphocytes. Raising the intratumoral level of CXCR3 ligands might therefore be a feasible way to enhance the infiltration by tumor-suppressive immune cells and to improve immune intervention in breast cancer. Inhibition of cyclooxygenases (COX) has been shown to inhibit tumor growth and metastases formation in a lymphocytic and IFN-γ dependent manner. We therefore tested whether COX inhibition induces CXCR3 ligand secretion from breast cancer cells. Methods: Human MCF-7 and MDA-MB 231 BC cells were stimulated with IFN-γ with or without prostaglandin E2 (PGE2) or COX inhibitors (indomethacin, aspirin, celecoxib). CXCL9 and CXCL10 release was measured by ELISA. COX-1 and COX-2 expression was measured in 45 BC samples and correlated with intratumoral CXCR3 ligand concentration. Results: Prostaglandin E2 inhibits CXCL10 and CXCL9 release from breast cancer cells. Aspirin and indomethacin enhance the INF-γ mediated secretion of these CXCR3 ligands by inhibition of endogenous cyclooxygenases. Celecoxib has this effect only at low concentrations, at higher concentrations is shows PGE2 agonistic effects. In human breast cancer samples, COX-2 overexpression inversely correlates with CXCR3 ligand concentration, which shows that the mechanism of PGE2 induced CXCL9/CXCL10 suppression might also be relevant in vivo. Conclusions: Suppressing endogenous PGE2 by cyclooxygenase inhibition increases CXCL9 and CXCL10 release from breast cancer cells and is therefore a feasible way to enhance the infiltration of breast tumors by tumor-suppressive lymphocytes. However, our results show that unselective COX inhibitors might be more suitable than the COX-2 specific celecoxib. Clinical trials are now warranted to clarify the mechanisms and therapeutic efficacy of COX inhibition in breast cancer.

Effects of cyclooxygenase inhibition on vascular responses evoked in fingers of men and women by iontophoresis of α1‐ and α2‐adrenoceptor agonists

In 10 men and nine women aged 20-23 years, we aimed to establish whether endogenous prostanoids synthesised by cyclooxygenase (COX) affect responses evoked in the finger by α(1)- or α(2)-adrenoceptor agonists. Cutaneous red cell flux (cRCF) was recorded in dorsal finger during iontophoresis of phenylephrine (PE) or clonidine (0.5 mm, seven 0.1 mA pulses followed by one 0.2 mA pulse: 30 s each at 60 s intervals) before and after the COX inhibitor aspirin (600 mg p.o.). In men, PE evoked a biphasic mean increase/decrease in cRCF before but a monophasic mean decrease in cRCF of 30-40% after aspirin (P < 0.05). In women in the low oestrogen (E(2)) phase of the menstrual cycle, PE evoked a decrease in cRCF (30-40%; P < 0.05) that was unchanged by aspirin, whereas in the high E(2) phase, PE evoked no change before but a graded decrease in cRCF (30-40%; P < 0.05) after aspirin. Clonidine evoked a decrease in cRCF (∼30%; P < 0.05) in men before, but not after, aspirin. Clonidine evoked both increases and decreases in cRCF before and after aspirin in women in the low and high E(2) phases (P > 0.05). We propose that finger vasoconstriction evoked by extraluminal α(1)-adrenoceptor stimulation is blunted by vasodilator COX products in young men and overcome by their action in women in the high, but not low E(2), phase of the menstrual cycle. By contrast, α(2)-adrenoceptor stimulation evokes finger vasoconstriction that is mediated by vasoconstrictor COX products in young men, but evokes no consistent response in women in the low or high E(2) phases of the menstrual cycle.

Synthesis, Characterisation and Biological Evaluation of Copper and Silver Complexes based on Acetylsalicylic Acid

Metalcarbonyl complexes with ligands derived from acetylsalicylic acid demonstrated high cytotoxic potential against various tumor cell lines and strong inhibition of the cyclooxygenase enzymes COX-1 and 2. In this study we tried to achieve comparable effects with [alkyne]silver or copper trifluoromethanesulfonate complexes which are more hydrophilic then the uncharged metalcarbonyl derivatives. All compounds were evaluated for growth inhibition against breast (MCF-7, MDA-MB 231) and colon cancer (HT-29) cell lines and for COX-1 and COX-2 inhibitory effects at isolated isoenzymes. Pure ligands showed neither cytotoxic nor COX-inhibitory effects. While the silver complexes of (but-2-ynyl)-2-acetoxybenzoate (But-ASS-Ag) and (but-2-yne-1,4-diyl)-bis(2-acetoxybenzoate) (Di-ASS-But-Ag) were strong cytostatics, only the copper complex Di-ASS-But-Cu was active. At the COX enzymes the complexes were more effective than their ligands and aspirin.

Effects of catechin, diclofenac and celecoxib on the proliferation of MCF-7 and LTED MCF-7 cells

Breast cancer is common among women especially after menopause. Inflammation is now considered as a risk factor of cancer and cyclooxygenase-2 (COX-2) enzymes are highly expressed in many cancers. COX-2 is the inducible enzyme responsible for the synthesis of pro-inflammatory prostaglandins. There are evidences that COX inhibitors especially those which inhibit COX-2 have a role in the management of cancers. Since breast tumors are generally estrogen sensitive, whether or not their response to COX inhibitors is changed when they are under the condition of estrogen deprivation. This in vitro study aimed to investigate the effects of different COX inhibitors, i.e . catechin − selective COX-1 inhibitor, diclofenac − COX-1/COX-2 inhibitor, and celecoxib − selective COX-2 inhibitor, at concentrations of 10 −10–10 −4 M on the proliferation of MCF-7 cells and long-term estrogen-deprived (LTED) MCF-7 cells. The effects of these COX inhibitors were assessed on day 2 and day 6 of incubation using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method. Morphological features of these cells on day 2 of incubation with COX inhibitors were visualized after Ho33342 staining and apoptosis was confirmed by DNA fragmentation. The results indicated that diclofenac and celecoxib, but not catechin, at high concentrations could effectively inhibit the proliferation of both cell types. Celecoxib was, however, the only drug used in this study that could markedly induce DNA fragmentation in LTED MCF-7 cells at the highest concentration (10 −4 M). This study provides the in vitro evidence to support the beneficial effect of COX-2 inhibitors against breast tumors whether or not at the estrogen-deprived stage.