Distinct isoforms (COX-1 and COX-2) of cyclooxygenase: possible physiological and therapeutic implications

In vitro and ex vivo inhibition of canine cyclooxygenase isoforms by robenacoxib: a comparative study

In vitro whole blood canine assays were used to quantify the inhibitory actions of the novel non-steroidal anti-inflammatory drug (NSAID) robenacoxib on the cyclooxygenase (COX) isoenzymes, COX-1 and COX-2, in comparison with other drugs of the NSAID class. COX-1 activity was determined by measuring serum thromboxane (Tx)B(2) synthesis in blood samples allowed to clot at 37 degrees C for 1h. COX-2 activity was determined by measuring prostaglandin (PG)E(2) synthesis in blood samples incubated at 37 degrees C for 24h in the presence of lipopolysaccharide. The rank order of selectivity for inhibition of COX-2 versus COX-1 (IC(50) COX-1:IC(50) COX-2) for veterinary drugs was highest with robenacoxib (128.8) compared to deracoxib (48.5), nimesulide (29.2), S+ carprofen (17.6), meloxicam (7.3), etodolac (6.6), R- carprofen (5.8) and ketoprofen (0.88). Selectivity expressed as the clinically relevant ratio IC(20) COX-1:IC(80) COX-2 was highest for robenacoxib (19.8) compared to deracoxib (2.3), S+ carprofen (2.5), R- carprofen (2.1), nimesulide (1.8), etodolac (0.76), meloxicam (0.46) and ketoprofen (0.21). An in vivo pharmacokinetic ex vivo pharmacodynamic study in the dog established dosage and concentration-effect relationships for single oral doses of robenacoxib over the dosage range 0.5-8.0mg/kg. Values of C(max) and AUC were linearly related to dosage over the tested range. Robenacoxib did not inhibit serum TxB(2) synthesis (COX-1) ex vivo at dosages of 0.5-4.0mg/kg and produced only transient inhibition (at the 1h and 2h sampling times) at the 8mg/kg dosage. All dosages of robenacoxib (0.5-8mg/kg) produced marked, significant and dose related inhibition of PGE(2) synthesis (COX-2) ex vivo. The data demonstrate that in the dog robenacoxib is a highly selective inhibitor of the COX-2 isoform of COX, and significantly inhibits COX-2 and spares COX-1 in vivo when administered orally over the dosage range 0.5-4.0mg/kg.

Long-chain n-3 polyunsaturated fatty acids: new insights into mechanisms relating to inflammation and coronary heart disease

Evidence from observational studies, prospective cohort studies and randomized clinical intervention studies indicate that moderate doses of long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) significantly decrease risk of fatal coronary heart disease (CHD). Higher doses and longer duration of intervention may also protect from non-fatal CHD events. The exact mechanisms through which LC n-3 PUFA has an effect on CHD are not well established but may include a decrease in fasting and postprandial triacylglycerol levels, a decrease in arrhythmias, modulation of platelet aggregation and decreased synthesis of pro-inflammatory agents. The mechanistic relation between LC n-3 PUFA and inflammation has attracted great interest, and in vitro studies have revealed that these fatty acids decrease endothelial activation, affect eicosanoid metabolism (including epoxygenation pathways) and induce inflammatory resolution. However, the effects of LC n-3 PUFA on established biomarkers of inflammation and endothelial activation in vivo are not strong. Consequently we need new and more sensitive and systemic biomarkers to reveal the effects of LC n-3 PUFA on localized inflammatory processes.

Anti-gastric cancer effects of celecoxib, a selective COX-2 inhibitor, through inhibition of Akt signaling

BACKGROUND AND AIM

Previously, we showed that treatment with celecoxib significantly reduced the number of viable gastric cancer cells, in a dose- and time-dependent manner. However, the specific anti-cancer effects of celecoxib on gastric cancer cells have not been clarified. The present in vitro study was carried out to investigate the mechanism involved in the anti-gastric cancer effects of celecoxib.

METHODS

3-(4,5-Dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was carried out after treating AGS cells (human gastric cancer cell line, ATCC CRL 1739) with celecoxib or indomethacin, and the effect of prostaglandin E(2) or LY294002 (PI3K inhibitor) was evaluated. Western blot analysis of tAkt (total Akt), pAkt (phosphorylated Akt), pGSK3beta (phosphorylated glycogen synthase kinase-3beta), pFKHR (phosphorylated forkhead transcriptional factor), and caspase-9 was carried out at various concentrations (0, 5, 10, 25, or 50 micromol/L) of celecoxib or indomethacin-treatment for 24 or 48 h in AGS cells.

RESULTS

Celecoxib- or LY294002-induced cell death was found to occur in a dose-dependent manner in AGS cells, and these decreases were slightly recovered by the addition of PGE(2) (25 or 50 micromol/L). The expression of pAkt but not tAkt was lower in the celecoxib treated-AGS cells and the response was dose dependent (P < 0.05). The expression of pGSK3beta and pFKHR was also significantly decreased in the celecoxib treated-AGS cells. Procaspase 9 (47 kDa) was frequently cleaved into 37, 35 and 17 kDa fragments in the celecoxib-treatment group. However, these changes in cell signal transduction were not observed in the indomethacin treated-AGS cells.

CONCLUSION

The anti-cancer effects of celecoxib on gastric cancer cells might be partly mediated by downregulation of Akt, GSK3beta, FKHR, and upregulation of caspase-9, in the mitochondrial apoptotic pathway.

Signaling pathways modulated by fish oil in salt-sensitive hypertension

Although many studies have indicated that fish oil (FO) improves cardiovascular risk factors and reduces histopathological manifestations of injury in experimental renal injury models, potential mechanisms underlying this protective effect have not been adequately defined. The objective of this study was to identify potential signaling pathways that confer protection in the Dahl rat model of salt-sensitive hypertension. Male Dahl salt-sensitive rats (n = 10/group) were provided with formulated diets containing 8% NaCl, 20% protein, and 25% FO or 25% corn oil (CO) for 28 days. FO reduced blood pressure (-11% at 4 wk; P < 0.05), urine protein excretion (-45% at 4 wk; P < 0.05), plasma cholesterol and triglyceride levels (-54%, P < 0.001; and -58%, P < 0.05), and histopathological manifestations of renal injury, including vascular hypertrophy, segmental and global glomerular sclerosis, interstitial fibrosis, and tubular atrophy. Interstitial inflammation was significantly reduced by FO (-32%; P < 0.001), as assessed by quantitative analysis of ED1-positive cells in sections of the renal cortex. FO reduced tubulointerstitial proliferative activity, as assessed by Western blot analysis of cortical homogenates for PCNA (-51%; P < 0.01) and quantitative analysis of Mib-1-stained sections of the renal cortex (-42%; P < 0.001). Decreased proliferative activity was associated with reduced phospho-ERK expression (-37%; P < 0.005) and NF-kappaB activation (-42%; P < 0.05). FO reduced cyclooxygenase (COX)-2 expression (-63%; P < 0.01) and membrane translocation of the NADPH oxidase subunits p47(phox) and p67(phox) (-26 and -34%; P < 0.05). We propose that FO ameliorates renal injury in Dahl salt-sensitive rats through the inhibition of ERK, decreased NF-kappaB activation, inhibition of COX-2 expression, and decreased NADPH oxidase activation.

Application of immunohistochemistry to thyroid neoplasms

CONTEXT

Thyroid lesions with nodular architecture and follicular pattern of growth often pose difficulties in accurate diagnosis during the assessment of cytologic and histologic specimens. The diagnosis of follicular neoplasm on cytology or of follicular tumor of uncertain malignant potential on histology is likely to cause confusion among clinicians and delay effective management of these lesions. Occasionally, thyroid tumors represent unusual or metastatic lesions and their accurate diagnosis requires immunohistochemical confirmation.

OBJECTIVE

To review the literature on the applications of immunohistochemistry in the differential diagnosis of thyroid tumors.

DATA SOURCES

Relevant articles indexed in PubMed (National Library of Medicine) between 1976 and 2006.

CONCLUSIONS

Our review supports the use of ancillary techniques involving a panel of antibodies suitable for immunohistochemistry and molecular analysis in the assessment of thyroid nodules. These tools can improve diagnostic accuracy when combined with standard morphologic criteria.

Inflammatory response and meningioma tumorigenesis and the effect of cyclooxygenase-2 inhibitors

In this article the authors discuss the rationale and research supporting the hypothesis that meningioma tumorigenesis may, in part, be driven by overexpression of cyclooxygenase-2 (Cox-2) and that treatment with celecoxib, a selective Cox-2 inhibitor, may hold therapeutic promise. Because therapies for recurrent or aggressive meningiomas (atypical or malignant subtypes) such as chemotherapy and radiotherapy generally offer little therapeutic benefit, interest in targeting Cox-2 has grown. This rate-limiting enzyme of prostaglandin synthesis can be inhibited with nonsteroidal antiinflammatory drugs (NSAIDs) such as ibuprofen and celecoxib. Treatment with NSAIDs has been shown to curb the tumorigenic properties of prostaglandins in several cancer models via both Cox-2-dependent and -independent mechanisms. In addition, celecoxib is well tolerated in humans, making its use as a chronic therapy for meningiomas attractive.

The anti-cancer effect of COX-2 inhibitors on gastric cancer cells

Epidemiologic studies have shown that nonsteroidal anti-inflammatory drugs could reduce the risk of cancer development including gastric cancer. This study was performed to identify the antineoplastic mechanism in gastric cancer cells affected by celecoxib, a selective COX-2 inhibitor. MTT assay, ELISA for prostaglandin E(2) (PGE(2)), cell-cycle analyses, immunofluorescent staining, and flow cytometry were performed after treating human gastric cancer cell lines (AGS and MKN-45) with celecoxib or indomethacin. The viabilities of celecoxib-treated cells decreased in a dose- and time-dependent manner compared with indomethacin. Drop of PGE(2) levels was more prominent in the presence of indomethacin than in that of celecoxib. Celecoxib arrested the cell cycle in the G(0)-G(1) phase, which reduced cell numbers in the S phase. Moreover, celecoxib increased the apoptotic cell proportions, a 4-fold increase over control cells. The anticancer effects of celecoxib on gastric cancer cells appear to be mediated by cell-cycle arrest and apoptosis, and not by COX-2 or PGE(2) suppression alone.

Expression of cyclooxygenase-2 in canine nasal carcinomas

Cyclooxygenase(COX)-2 expression was evaluated in 24 paraffin-embedded canine nasal carcinoma tissue samples by immunohistochemistry. Several different tumor types were represented, including carcinomas, adenocarcinomas and squamous cell carcinomas. COX-2 expression was identified in 17/24 cases (71%). The proportion of positive cells expressing COX-2 ranged from 10 to 95% and COX-2 expression was predominantly localized in the cytoplasm. Treatment with a COX-2 inhibitor should be investigated, along with the utilization of COX-2 expression as a prognostic marker.

COX-2 inhibition: a possible role in the management of prostate cancer?

There is mounting evidence to support a role for cyclooxygenase-2 (COX-2) inhibitors (coxibs) in the management of prostate cancer. This review considers the current evidence base for the use of coxibs in prostate cancer as well as their adverse event profile. A systematic literature review using the search terms 'cyclooxygenase', 'COX-2', 'coxibs', 'cardiovascular risk', and 'prostate cancer' was performed using Medline. Celecoxib appears safer in terms of cardiovascular toxicity than other coxibs, and this may relate to its lower selectivity for the COX-2 enzyme. This lower selectivity also provides rationale for its putative broader anti-cancer effects, via non-COX-2-dependent pathways that affect cell cycle regulation, angiogenesis, and hypoxic modulation. There are also interacting relationships between COX-2, chronic inflammation, and prostate cancer. There is much promise for the coxibs as anti-cancer agents. The future might be to pharmacologically adapt these agents to exert their COX-2 independent mechanisms of action while minimizing their COX-2-dependent adverse cardiovascular effects.

Effect of short-term sequential administration of nonsteroidal anti-inflammatory drugs on the stomach and proximal portion of the duodenum in healthy dogs

OBJECTIVE

To evaluate effects of injection with a nonsteroidal anti-inflammatory drug (NSAID) followed by oral administration of an NSAID on the gastrointestinal tract (GIT) of healthy dogs.

ANIMALS

6 healthy Walker Hounds.

PROCEDURES

In a randomized, crossover design, dogs were administered 4 treatments consisting of an SC injection of an NSAID or control solution (day 0), followed by oral administration of an NSAID or inert substance for 4 days (days 1 through 4). Treatment regimens included carprofen (4 mg/kg) followed by inert substance; saline (0.9% NaCl) solution followed by deracoxib (4 mg/kg); carprofen (4 mg/kg) followed by carprofen (4 mg/kg); and carprofen (4 mg/kg) followed by deracoxib (4 mg/kg). Hematologic, serum biochemical, and fecal evaluations were conducted weekly, and clinical scores were obtained daily. Endoscopy of the GIT was performed before and on days 1, 2, and 5 for each treatment. Lesions were scored by use of a 6-point scale.

RESULTS

No significant differences existed for clinical data, clinicopathologic data, or lesion scores in the esophagus, cardia, or duodenum. For the gastric fundus, antrum, and lesser curvature, an effect of time was observed for all treatments, with lesions worsening from before to day 2 of treatments but improving by day 5.

CONCLUSIONS AND CLINICAL RELEVANCE

Sequential administration of NSAIDs in this experiment did not result in clinically important gastroduodenal ulcers. A larger study to investigate the effect of sequential administration of NSAIDs for longer durations and in dogs with signs of acute and chronic pain is essential to substantiate these findings.

Calcitriol and genistein actions to inhibit the prostaglandin pathway: potential combination therapy to treat prostate cancer

We present an overview of the prostaglandin (PG) pathway as a novel target for the treatment of prostate cancer (PCa) using a combination of calcitriol and genistein, both of which have known antiproliferative properties. Calcitriol inhibits the PG pathway in PCa cells in 3 separate ways: by decreasing cyclooxygenase-2 (COX-2) expression, stimulating 15-hydroxyprostaglandin dehydrogenase (15-PGDH) expression, and decreasing EP (PGE2) and FP (PGF(2alpha)) receptors. These actions of calcitriol result in reduced levels of biologically active PGE2, leading ultimately to growth inhibition of the PCa cells. We also demonstrate the advantages of using calcitriol in combination with genistein for the treatment of PCa. Genistein, a major component of soy, is a potent inhibitor of the activity of CYP24, the enzyme that initiates the degradation of calcitriol. This leads to increased half-life of bioactive calcitriol, thereby enhancing all of calcitriol's actions including those on the PG pathway. In addition to inhibiting CYP24 enzyme activity, genistein has its own independent actions on the PG pathway in PCa cells. Like calcitriol it inhibits COX-2 expression and activity, leading to decreased synthesis of PGE2. It also inhibits the EP and FP receptors, thereby reducing the biological function of PGE2. Thus, the combination of calcitriol and genistein acts additively to inhibit the PG pathway. Both calcitriol and genistein are relatively safe and have little toxicity associated with their intake. We postulate that the combination of calcitriol and genistein is an attractive therapeutic option for the treatment of PCa.

Nickel Compounds Render Anti-apoptotic Effect to Human Bronchial Epithelial Beas-2B Cells by Induction of Cyclooxygenase-2 through an IKKβ/p65-dependent and IKKα- and p50-independent Pathway

The carcinogenicity of nickel compounds has been well documented both in vitro and in vivo; however, the molecular mechanisms by which nickel compounds cause cancers are far from understood. Because suppression of apoptosis is thought to contribute to carcinogenesis, we investigated the mechanisms implicated in nickel-induced anti-apoptotic effect in human bronchial epithelial (Beas-2B) cells. We found that exposure of Beas-2B cells to nickel compounds resulted in increased cyclooxygenase-2 (COX-2) expression and that small interfering RNA (siCOX-2) knockdown of COX-2 expression resulted in increased cell sensitivity to nickel-triggered cell apoptosis, demonstrating that COX-2 induction has an anti-apoptotic effect on Beas-2B cells. Overexpression of IKKbeta-KM, a kinase inactive mutant of IKKbeta, blocked NF-kappaB activation and COX-2 induction by nickel compounds, indicating that activated NF-kappaB may be a mediator for COX-2 induction. To further explore the contribution of the NF-kappaB pathway in COX-2 induction and in protection from nickel exposure, mouse embryonic fibroblasts deficient in IKKbeta, IKKalpha, p65, and p50 were analyzed. Loss of IKKbeta impaired COX-2 induction by nickel exposure, whereas knockout of IKKalpha had a marginal effect. Moreover, the NF-kappaB p65, and not the p50 subunit, was critical for nickel-induced COX-2 expression. In addition, a deficiency of IKKbeta or p65 rendered cells more sensitive to nickel-induced apoptosis as compared with those in wild type cells. Finally, it was shown that reactive oxygen species H(2)O(2) were involved in both NF-kappaB activation and COX-2 expression. Collectively, our results demonstrate that COX-2 induction by nickel compounds occurs via an IKKbeta/p65 NF-kappaB-dependent but IKKalpha- and p50-independent pathway and plays a crucial role in antagonizing nickel-induced cell apoptosis in Beas-2B cells.

Increased cyclooxygenase-2 expression is correlated with suppressed antitumor immunity in cervical adenocarcinomas

Cyclooxygenase-2 (COX-2) inhibition suppressed the growth of various tumors. The augmentation of antitumor immunity by increasing cytotoxic lymphocytes may be an important mechanism for COX-2 inhibition. Among cervical cancers, adenocarcinomas present more aggressive behavior and overexpressed COX-2. The expression of COX-2 and the CD8+ lymphocyte infiltrations were evaluated in this study by immunohistochemistry. We studied COX-2 expression and CD8+ lymphocyte infiltration in 55 women with cervical adenocarcinomas. COX-2 expression and tumor stromal CD8+ lymphocytes were evaluated by semiquantified methods. Tumor intraepithelial lymphocytes were counted under microscopic field of x200. Correlations between these data and other clinicopathologic features were investigated. Thirty-seven out of 55 (67.3%) cervical adenocarcinomas significantly expressed COX-2. Patients who died within 5 years showed higher percentage of COX-2 expression than survivors (100% vs 58.1%, P < 0.05). Victims also showed lesser intraepithelial CD8+ lymphocyte counts than survived patients (3.4 vs 26.4, P < 0.05). COX-2 expression and tumor intraepithelial lymphocyte count were reversely correlated with each other (correlation index: -0.38, P < 0.01). Up-regulated COX-2 expression and lesser tumor intraepithelial CD8+ lymphocyte count are poor prognostic indicators for cervical adenocarcinoma patients. COX-2 may play an important role in the suppression of host antitumor immunity in cervical adenocarcinomas.

The omega-3 fatty acid docosahexaenoate attenuates endothelial cyclooxygenase-2 induction through both NADP(H) oxidase and PKC epsilon inhibition

A high intake of the omega-3 fatty acid docosahexaenoate [docosahexaenoic acid (DHA)] has been associated with systemic antiinflammatory effects and cardiovascular protection. Cyclooxygenase (COX)-2 is responsible for the overproduction of prostaglandins (PG) at inflammatory sites, and its expression is increased in atheroma. We studied the effects of DHA on COX-2 expression and activity in human saphenous vein endothelial cells challenged with proinflammatory stimuli. A>or=24-h exposure to DHA reduced COX-2 expression and activity induced by IL-1, without affecting COX-1 expression. DHA effect depended on the NF-kappaB-binding site in the COX-2 promoter. EMSAs confirmed that DHA attenuated NF-kappaB activation. Because MAPK, PKC, and NAD(P)H oxidase all participate in IL-1-mediated COX-2 expression, we also tested whether these enzymes were involved in DHA effects. Western blots showed that DHA blocked nuclear p65 NF-kappaB subunit translocation by decreasing cytokine-stimulated reactive oxygen species and ERK1/2 activation by effects on both NAD(P)H oxidase and PKCepsilon activities. Finally, to address the question whether DHA itself or DHA-derived products were responsible for these effects, we inhibited the most important enzymes involved in polyunsaturated fatty acid metabolism, showing that 15-lipoxygenase-1 products mediate part of DHA effects. These studies provide a mechanistic basis for antiinflammatory and possibly plaque-stabilizing effects of DHA.

Prognostic factors and COX-2 expression in advanced stage esophageal squamous cell carcinoma

Cyclooxygenase-2 (COX-2) is overexpressed in various types of human malignancies, including squamous cell carcinomas of the esophagus, but its clinicopathologic role in esophageal squamous cell carcinoma (ESCC) remains unclear. The aim of this study was to analyze expression of COX-2 in ESCC and to correlate this expression with clinicopathologic parameters and survival. From 1999 to 2003, endoscopic tissue samples from 110 patients with ESCC were collected for analysis. COX-2 expression was examined through immunohistochemical staining. Clinicopathologic data were analyzed to verify significance. COX-2 expression was detected in 50 of 110 ESCC specimens (45%). COX-2 expression was negative to weak in 73% (COX-2 low) and moderate to strong in 27% (COX-2 high) of tumors. Statistical differences between COX-2 high and COX-2 low were found according to status of the stage (stage IVM1a/IVM1b) (P=.001): cancer antigen (CA) 19-9 (normal/high) (P%.011), CA 12-5 (normal/high) (P=.011), and CA 15-3 (normal/high) (P=.035). Survival was significantly reduced among patients with high COX-2 expression (median overall survival, 3 mo) when compared with the COX-2 low group (median overall survival, 6 mo) (P=.0001). In the univariate analysis, age, body mass index, stage, COX-2, lactate dehydrogenase, CA 12-5, and CA 15-3 were significant factors for survival. With the use of COX regression analysis, only stage (P=.000), COX-2 (P=.000), lactate dehydrogenase (P=.023), and CA 15-3 (P=.002) were independent prognostic factors. Results showed that in patients with ESCC, COX-2 overexpression was significantly correlated with visceral metastases IVM1b). COX-2 overexpression is an unfavorable prognostic factor in ESCC.

Cyclooxygenase-2 Induction by Arsenite Is through a Nuclear Factor of Activated T-cell-dependent Pathway and Plays an Antiapoptotic Role in Beas-2B Cells

Arsenite is a well known metalloid human carcinogen, and epidemiological evidence has demonstrated its association with the increased incidence of lung cancer. However, the mechanism involved in its lung carcinogenic effect remains obscure. The current study demonstrated that exposure of human bronchial epithelial cells (Beas-2B) to arsenite resulted in a marked induction of cyclooxygenase (COX)-2, an important mediator for inflammation and tumor promotion. Exposure of the Beas-2B cells to arsenite also led to significant transactivation of nuclear factor of activated T-cells (NFAT), but not activator protein-1 (AP-1) and NFkappaB, suggesting that NFAT, rather than AP-1 or NFkappaB, is implicated in the responses of Beas-2B cells to arsenite exposure. Furthermore, we found that inhibition of the NFAT pathway by either chemical inhibitors, dominant negative mutants of NFAT, or NFAT3 small interference RNA resulted in the impairment of COX-2 induction and caused cell apoptosis in Beas-2B cells exposed to arsenite. Site-directed mutation of two putative NFAT binding sites between-111 to +65 in the COX-2 promoter region eliminated the COX-2 transcriptional activity induced by arsenite, confirming that those two NFAT binding sites in the COX-2 promoter region are critical for COX-2 induction by arsenite. Moreover, knockdown of COX-2 expression by COX-2-specific small interference RNA also led to an increased cell apoptosis in Beas-2B cells upon arsenite exposure. Together, our results demonstrate that COX-2 induction by arsenite is through NFAT3-dependent and AP-1- or NFkappaB-independent pathways and plays a crucial role in antagonizing arsenite-induced cell apoptosis in human bronchial epithelial Beas-2B cells.

Inhibition of cyclooxygenase-2 in experimental severe acute pancreatitis

BACKGROUND

The standard treatment for acute pancreatitis (AP) is still based on supportive care. The search for a new drug that could change the natural history of the disease is a continuing challenge for many researchers. The aim of this study is to evaluate the effect of a cyclooxygenase-2 (COX-2) inhibitor on experimental AP in rats.

METHODS

The animals were divided into 2 groups: Group 1 (n = 30)-animals with taurocholate-induced AP treated with parecoxib (40 mg/kg). Group 2 (n = 30)-animals with taurocholate-induced AP that received saline. The COX-2 inhibitor (parecoxib) was injected immediately after AP induction, through the penis dorsal vein. The parameters evaluated were histology, serum levels of amylase, IL-6 and IL-10, and mortality rate.

RESULTS

The serum levels of IL-6 and IL-10 in the parecoxib-treated group were lower than the control group. The amylase serum levels and the mortality rate remained unchanged in the treated animals. Histologic morphology also was unaltered, except for fat necrosis, which was higher in parecoxib-treated rats.

CONCLUSION

Inhibition of Cox-2 decreases the systemic release of inflammatory cytokines, but has a poor effect on the direct pancreas injury caused by taurocholate.

Cyclooxygenase-2 expression in astrocytomas. Relationship with microvascular parameters, angiogenic factors expression and survival

OBJECTIVE

Cyclooxygenase-2 (COX-2) is the enzyme isoform involved in the synthesis of prostaglandins (PGs) and thromboxane from arachidonic acid. The role of the up-regulation of COX-2 in the formation and progression of gliomas has been dealt with in earlier reports, which describe increased levels of PGs within gliomas. In the present study, we examined the expression of COX-2 in diffuse gliomas of astrocytic origin in relation to microvascular parameters, angiogenic factors and survival.

MATERIALS AND METHODS

A total of 83 cases of diffuse astrocytomas (grade II-IV) were analyzed by immunohistochemistry for the presence of COX-2.

RESULTS

COX-2 expression was detected in 79 cases (95%) with an increased expression in grade IV as compared to grades II/III (p=0.024). A positive correlation occurred between COX-2 and angiogenic factors such as vascular endothelial growth factor (VEGF) (p<0.0001) and hypoxia inducible factor (HIF)-1alpha (p=0.005), as well as the tumours' proliferative activity (expressed as the percentage of Ki-67 positive cells) (p=0.032), and total vascular area (TVA) (p=0.040). In univariate analysis, COX-2 was associated with shortened survival (p = 0.050). Multivariate survival analysis showed that the interaction model of COX-2 with grade along with age were the only significant prognostic indicators.

CONCLUSION

These results implicate COX-2 in the angiogenesis and biological aggressiveness of diffuse astrocytomas, and suggest that it would be worthwhile to examine how the inhibition of COX-2 expression may influence astrocytoma patients' survival.

Amyloid β peptide (25–35) activates protein kinase C leading to cyclooxygenase-2 induction and prostaglandin E2 release in primary midbrain astrocytes

Prostaglandins (PGs) are generated by the enzymatic activity of cyclooxygenase-1 and -2 (COX-1/2) and modulate several functions in the CNS such as the generation of fever, the sleep/wake cycle, and the perception of pain. Moreover, the induction of COX-2 and the generation of PGs has been linked to neuroinflammatory aspects of Alzheimer's disease (AD). Non-steroidal anti-inflammatory drugs (NSAIDs) that block COX enzymatic activity have been shown to reduce the incidence of AD in various epidemiological studies. While several reports investigated the expression of COX-2 in neurons and microglia, expression of COX-2 in astroglial cells has not been investigated in detail. Here we show that amyloid beta peptide 25-35 (Abeta(25-35)) induces COX-2 mRNA and protein synthesis and a subsequent release of prostaglandin E(2) (PGE(2)) in primary midbrain astrocytes. We further demonstrate that protein kinase C (PKC) is involved in Abeta(25-35)-induced COX-2/PGE(2) synthesis. PKC-inhibitors prevent Abeta(25-35)-induced COX-2 and PGE(2) synthesis. Furthermore Abeta(25-35) rapidly induces the phosphorylation and enzymatic activation of PKC in primary rat midbrain glial cells and in primary human astrocytes from post mortem tissue. Our data suggest that the PKC isoforms alpha and/or beta are most probably involved in Abeta(25-35)-induced expression of COX-2 in midbrain astrocytes. The potential role of astroglial cells in the phagocytosis of amyloid and the involvement of PGs in this process suggests that a modulation of PGs synthesis may be a putative target in the prevention of amyloid deposition.

Ascorbic acid enhances the inhibitory effect of aspirin on neuronal cyclooxygenase-2-mediated prostaglandin E2 production

Inhibition of neuronal cyclooxygenase-2 (COX-2) and hence prostaglandin E2 (PGE2) synthesis by non-steroidal anti-inflammatory drugs has been suggested to protect neuronal cells in a variety of pathophysiological situations including Alzheimer's disease and ischemic stroke. Ascorbic acid (vitamin C) has also been shown to protect cerebral tissue in a variety of experimental conditions, which has been attributed to its antioxidant capacity. In the present study, we show that ascorbic acid dose-dependently inhibited interleukin-1beta (IL-1beta)-mediated PGE2 synthesis in the human neuronal cell line, SK-N-SH. Furthermore, in combination with aspirin, ascorbic acid augmented the inhibitory effect of aspirin on PGE2 synthesis. However, ascorbic acid had no synergistic effect along with other COX inhibitors (SC-58125 and indomethacin). The inhibition of IL-1beta-mediated PGE2 synthesis by ascorbic acid was not due to the inhibition of the expression of COX-2 or microsomal prostaglandin E synthase (mPGES-1). Rather, ascorbic acid dose-dependently (0.1-100 microM) produced a significant reduction in IL-1beta-mediated production of 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha), a reliable indicator of free radical formation, suggesting that the effects of ascorbic acid on COX-2-mediated PGE2 biosynthesis may be the result of the maintenance of the neuronal redox status since COX activity is known to be enhanced by oxidative stress. Our results provide in vitro evidence that the neuroprotective effects of ascorbic acid may depend, at least in part, on its ability to reduce neuronal COX-2 activity and PGE2 synthesis, owing to its antioxidant properties. Further, these experiments suggest that a combination of aspirin with ascorbic acid constitutes a novel approach to render COX-2 more sensitive to inhibition by aspirin, allowing an anti-inflammatory therapy with lower doses of aspirin, thereby avoiding the side effects of the usually high dose aspirin treatment.

Comparison of oral and subcutaneous administration of buprenorphine and meloxicam for preemptive analgesia in cats undergoing ovariohysterectomy

OBJECTIVE

To compare the effectiveness of preoperative PO and SC administration of buprenorphine and meloxicam for prevention of postoperative pain-associated behaviors in cats undergoing ovariohysterectomy.

DESIGN

Randomized controlled study.

ANIMALS

51 female cats (4 to 60 months old; weight range, 1.41 to 4.73 kg [3.1 to 10.4 lb]).

PROCEDURE

Cats received 1 of 5 treatments at the time of anesthetic induction: buprenorphine PO (0.01 mg/kg [0.0045 mg/lb]; n = 10), buprenorphine SC (0.01 mg/kg; 10), meloxicam SC (0.3 mg/kg 10.14 mg/lb]; 10), meloxicam PO (0.3 mg/kg; 10), or 0.3 mL of sterile saline (0.9% NaCI) solution SC (control group; 11). Sedation scores and visual analog scale and interactive visual analog scale (IVAS) pain-associated behavior scores were assigned to each cat 2 hours before and at intervals until 20 hours after surgery.

RESULTS

Cats receiving meloxicam PO or SC had significantly lower IVAS scores (2.91 and 2.02, respectively), compared with IVAS scores for cats receiving buprenorphine PO (755). Pain-associated behavior scores for cats administered buprenorphine or meloxicam PO or SC preoperatively did not differ significantly from control group scores. Rescue analgesia was not required by any of the cats receiving meloxicam, whereas 3 of 10 cats receiving buprenorphine PO, 2 of 10 cats receiving buprenorphine SC, and 1 of 11 cats receiving the control treatment required rescue analgesia.

CONCLUSIONS AND CLINICAL RELEVANCE

On the basis of pain-associated behavior scores, cats receiving meloxicam PO or SC before ovariohysterectomy appeared to have less pain after surgery than those receiving buprenorphine PO preoperatively.

Immunohistochemical expression of cyclooxygenase 2 in follicular carcinomas of the thyroid

CONTEXT

Cyclooxygenase 2 (COX-2) has been shown to be up-regulated and/or overexpressed in a variety of human neoplasms. However, limited data exist on the role of COX-2 in follicular carcinomas of the thyroid. Studies in this area are potentially significant, since therapeutic agents that inhibit COX-2 are currently available and could play a role in treatment.

DESIGN

A retrospective clinicopathologic review with COX-2 immunohistochemical staining of 34 follicular carcinomas and 7 follicular adenomas with incomplete capsular penetration was performed.

RESULTS

The study included 41 patients (25 women; mean age, 50.9 years). All patients underwent gross total resection of the neoplasm. Fifteen carcinoma patients received adjuvant radiotherapy. Seven patients with follicular carcinomas developed recurrent disease: 3 patients were alive (mean follow-up, 10.1 years) and 4 patients died of metastatic disease (mean follow-up, 3.5 years). All remaining patients were disease free (mean follow-up, 5.9 years). Only 1 follicular adenoma with incomplete capsular penetration recurred (patient alive at 9 years). The remaining patients were disease free (mean follow-up, 4.9 years). The COX-2 staining was positive in 11 tumors (9 of 34 follicular carcinomas, 2 of 7 follicular adenomas with incomplete capsular penetration). A greater percentage of recurrences (36% COX-2 positive vs 13% COX-2 negative) and fatal tumors (18% COX-2 positive vs 7% COX-2 negative) occurred in patients who had COX-2-positive staining neoplasms.

CONCLUSION

Only a few follicular carcinomas (26%) and follicular adenomas with incomplete capsular penetration (29%) express COX-2 by immunohistochemical analysis. The data suggest that such expression of COX-2 may correlate with increased tumor recurrence and death; however, studies with larger numbers of patients will be needed to establish this.

Ubiquitous expression of cyclooxygenase-2 in meningiomas and decrease in cell growth following in vitro treatment with the inhibitor celecoxib: potential therapeutic application

OBJECT

Meningiomas are the second most common symptomatic primary central nervous system tumor in adults. Findings of epidemiological studies link meningiomas with a history of head trauma, indicating a causal relationship between the inflammatory response and meningioma tumorigenesis. Cyclooxygenase-2 (COX-2), an inducible inflammatory enzyme, converts arachidonic acid to prostaglandins, which have angiogenic, cell-proliferative, and antiapoptotic effects. The authors investigated COX-2 expression in meningiomas and the effects of celecoxib, a COX-2 inhibitor, on meningioma cell growth in vitro.

METHODS

Four meningioma surgical specimens were immunohistochemically stained and graded (0 to 4) for COX-2. In addition, a Western blot analysis was performed to detect the presence of COX-2. Human meningioma cells grown in cell culture were treated with vehicle or celecoxib (0.25-1 mM). An immunohistochemical analysis of COX-2, a methylthiotetrazole cell proliferation assay, a TUNEL apoptosis assay, and a Western blot analysis for the proapoptotic protein BAX were performed in vitro. One hundred eleven (87%) of 128 benign meningiomas and six (86%) of seven atypical meningiomas displayed a high COX-2 immunoreactivity (Grade 4 staining). In the Western blot analysis all four surgical specimens (100%) stained positive for a 70-kD band consistent with COX-2. Celecoxib inhibited cell growth in a dose-dependent fashion and induced apoptosis by Day 2, with no change noted in the expression of the BAX protein.

CONCLUSIONS

The COX-2 enzyme is universally expressed in meningiomas. Celecoxib inhibits meningioma growth in vitro in a dose-dependent fashion, with evidence of apoptosis. Inhibitors of COX-2 may have a role in the treatment of recurrent meningiomas.

Meloxicam: a selective COX-2 inhibitor non-steroidal anti-inflammatory drug

Meloxicam is a new non-steroidal anti-inflammatory drug (NSAID) that selectively inhibits the inducible isoform of the cyclo-oxygenase (COX)-2 enzyme. This enzyme has a major role in mediating the inflammatory response, while synthesis of prostaglandins required for normal physiological functioning of the stomach and kidneys is under the control of the constitutive isoform, COX-1. Other NSAIDs in clinical use show varying degrees of selectivity towards COX-1. Only meloxicam and (albeit to a lesser extent) nimesulide could be described as selective for COX-2. In comparative trials of patients with osteo- and rheumatoid arthritis, meloxicam has been found to be at least as effective as other NSAIDs, but with a greatly reduced incidence of gastrointestinal side-effects. There is no evidence that meloxicam causes any deterioration in renal function in patients with moderate degrees of renal failure, and no evidence of drug accumulation with continued use. Meloxicam's half-life of 20 h makes it ideal for once daily administration, and it is 99% converted to inactive metabolites prior to excretion. No clinically significant drug interactions have been detected, making it suitable for use in patients with co-existing pathology. Meloxicam's safety and tolerability make it a significant advance in the treatment of rheumatic disease.

Preclinical pharmacology of lumiracoxib: a novel selective inhibitor of cyclooxygenase-2

1. This manuscript presents the preclinical profile of lumiracoxib, a novel cyclooxygenase-2 (COX-2) selective inhibitor. 2. Lumiracoxib inhibited purified COX-1 and COX-2 with K(i) values of 3 and 0.06 microM, respectively. In cellular assays, lumiracoxib had an IC(50) of 0.14 microM in COX-2-expressing dermal fibroblasts, but caused no inhibition of COX-1 at concentrations up to 30 microM (HEK 293 cells transfected with human COX-1). 3. In a human whole blood assay, IC(50) values for lumiracoxib were 0.13 microM for COX-2 and 67 microM for COX-1 (COX-1/COX-2 selectivity ratio 515). 4. Lumiracoxib was rapidly absorbed following oral administration in rats with peak plasma levels being reached between 0.5 and 1 h. 5. Ex vivo, lumiracoxib inhibited COX-1-derived thromboxane B(2) (TxB(2)) generation with an ID(50) of 33 mg kg(-1), whereas COX-2-derived production of prostaglandin E(2) (PGE(2)) in the lipopolysaccharide-stimulated rat air pouch was inhibited with an ID(50) value of 0.24 mg kg(-1). 6. Efficacy of lumiracoxib in rat models of hyperalgesia, oedema, pyresis and arthritis was dose-dependent and similar to diclofenac. However, consistent with its low COX-1 inhibitory activity, lumiracoxib at a dose of 100 mg kg(-1) orally caused no ulcers and was significantly less ulcerogenic than diclofenac (P<0.05). 7. Lumiracoxib is a highly selective COX-2 inhibitor with anti-inflammatory, analgesic and antipyretic activities comparable with diclofenac, the reference NSAID, but with much improved gastrointestinal safety.

Effect of steroidal and non-steroidal drugs on the microglia activation pattern and the course of degeneration in the retinal degeneration slow mouse

BACKGROUND

In hereditary retinal degeneration, microglia cells become activated, migrate through the outer nuclear layer (ONL) and accumulate in the subretinal space. Although this inflammatory process is not likely to be responsible for the onset of photoreceptor apoptosis, cytotoxic substances secreted by activated microglia could potentially accelerate and perpetuate the degenerative process. Anti-inflammatory drugs have been shown to modulate the microglia response in neurodegenerative disorders and potentially ameliorate the disease progression in various animal model systems. In this study we wanted to test the impact of the most commonly used anti-inflammatory drugs (acetylsalicylate and prednisolone) on the microglia activation pattern, the rate of caspase-3-dependent photoreceptor apoptosis and the course of the degeneration in the retinal degeneration slow (rds) mouse retina.

METHODS

169 pigmented rds mice and 30 CBA wild-type mice were used for this study. The treatment groups were injected daily with either acetylsalicylate (200 mg/kg) or prednisolone (2 mg/kg) i.p. from day 0 up to 3 months. Animals were sacrificed at days 10, 14, 16, 18, 20, 30, 40, 60 and 90. Cryoprotected frozen sections were immunostained with F4/80 and cleaved caspase-3 antibodies. The main outcome measures were the total microglia count in the subretinal space, the total cleaved caspase-3-positive cells in the ONL and the averaged number of photoreceptor rows in the midperipheral retina.

RESULTS

Neither acetylsalicylate nor prednisolone reduced subretinal microglia accumulation in the rds mouse degeneration model. Moreover, they aggravated migration and accumulation in the early time course. The apoptotic cascade started earlier and was more pronounced in both treatment groups compared to the control group. The pace of retinal degeneration was not reduced in the treatment groups compared to the untreated control. In contrast, acetylsalicylate did significantly accelerate the photoreceptor cell degeneration in comparison to the prednisolone (p < 0.001) and to the control group (p < 0.001).

CONCLUSIONS

Acetylsalicylate and prednisolone do not decrease the microglia response in the rds mouse and are not neuroprotective. More research is needed to clarify the molecular mechanisms which lead to photoreceptor cell death and to elucidate the complex role of microglia in inherited retinal degeneration.

Different cell kinetic changes in rat stomach cancer after treatment with celecoxib or indomethacin: Implications on chemoprevention

AIM: Mechanisms underlying the chemopreventive effects of cyclooxygenase (COX) inhibitors remain elusive. We have previously shown that celecoxib but not indomethacin could prevent carcinogen-induced gastric cancer development in Wistar rats. This chemopreventive effect appeared to be independent of COX-2 and prostaglandin (PG) E2 suppression since the lowest PGE₂ was obtained in indomethacin group. This study compared the cell kinetic changes in stomachs of rats after treatment with celecoxib (5, 10, 20 mg/(kg·d)) or indomethacin (3 mg/(kg·d)) to gain more insights into the chemopreventive mechanism.

METHODS: The apoptosis and proliferation indexes in gastric tumor, adjacent non-cancer tissues and normal gastric tissues were determined. Apoptosis was quantified by apoptotic nuclei counting and TUNEL, whereas proliferation was determined by Ki67 immunostaining.

RESULTS: Treatment with either celecoxib or indomethacin inhibited gastric tumor proliferation by more than 65% (P<0.02). However, celecoxib caused a dose-dependent increase in apoptosis (P<0.05) which was not seen in indomethacin-treated tumors (P = 0.54). The highest apoptosis to proliferation ratio was seen in tumors treated with celecoxib at 10 mg/(kg·d). Treatment with this dose of celecoxib was associated with the lowest incidence of gastric cancer development.

CONCLUSION: Our findings suggest that the difference in chemopreventive effects of indomethacin and celecoxib in this animal model of gastric carcinogenesis is largely due to the differential cell kinetic changes, which does not correlate with the degree of COX-2 and PG suppression.

COX-2 expression correlates with VEGF-C and lymph node metastases in patients with head and neck squamous cell carcinoma

Recent observations suggest an implication of the cyclooxygenase-2 (COX-2) in tumor lymphangiogenesis through an upregulation of vascular endothelial growth factor-C expression. It is unknown whether this mechanism also acts in squamous cell carcinoma of the head and neck region. We performed a retrospective study of 70 patients with head and neck squamous cell carcinoma in order to investigate whether COX-2 immunohistochemical expression correlates with vascular endothelial growth factor-C expression. We also examined the association of the expression of these molecules with clinicopathologic parameters (especially lymph node status) and outcome for these patients. We performed immunostaining on formalin-fixed, paraffin-embedded tissue sections by the routine streptavidin-biotin peroxidase labeled procedure. Increased cyclooxygenase-2 expression was observed in 30 of the 68 tumor samples (44%), while high vascular endothelial growth factor-C expression occurred in 26 of the 68 tumor samples (38%). High expression of the two proteins was correlated with the presence of lymph node metastasis at the time of diagnosis, and the observed association was even stronger when there was overexpression for both the antibodies (P<0.001). High expression of vascular endothelial growth factor-C, but not of COX-2 was correlated with increased mortality in patients with oral-larynx squamous cell carcinoma. When multivariate Cox regression model was applied, the presence of lymph node metastasis at the time of diagnosis, combined with overexpression of both the antibodies, was the only independent prognostic factor for mortality of these patients. Our results suggest that a lymphangiogenic pathway, in which COX-2 overexpression stimulates vascular endothelial growth factor-C upregulation, probably exists in head and neck squamous cell carcinoma. Also, the predictive ability for mortality of regional lymph node metastasis can be improved with the combined evaluation of the immunohistochemical expression of these two proteins.

The risks and benefits of cyclo-oxygenase-2 inhibitors in prostate cancer: A review

Cyclo-oxygenase (COX), also referred to as prostaglandin (PG) endoperoxidase synthase, is a key enzymatic mediator in the production of arachidonic acids to PGs and eicosanoids. Two isoforms of COX exist, namely COX-1 and COX-2, which have distinct physiological functions and tissue distribution. Epidemiological studies suggest that regular consumption of aspirin and/or other non-steroidal anti-inflammatory drugs (NSAIDs), which inhibit COX, could notably reduce the risk of developing many cancers. COX-2 expression has been shown to increase in many cancers and cancer cell lines, including human prostate adenocarcinoma. COX-2 may also be upregulated in proliferative inflammatory atrophy (PIA) of the prostate, a pre-neoplastic lesion. The COX-2 pathway may therefore be a useful target for chemoprevention of prostate cancer, and there is much interest in exploring this with the use of COX-2 inhibitor drugs such as celecoxib. While there is concern regarding the cardiovascular toxicities of coxibs, there is no evidence that there is any increased risk with the use of celecoxib in the short-term neoadjuvant setting.

Phospholipase D Isozymes Mediate Epigallocatechin Gallate-induced Cyclooxygenase-2 Expression in Astrocyte Cells

Little is known about the effect of epigallocatechin-3 gallate (EGCG), a major constituent of green tea, on the expression of cyclooxygenase (COX)-2. Here, we studied the role of phospholipase D (PLD) isozymes in EGCG-induced COX-2 expression. Stimulation of human astrocytoma cells (U87) with EGCG induced formation of phosphatidylbutanol, a specific product of PLD activity, and synthesis of COX-2 protein and its product, prostaglandin E(2) (PGE(2)). Pretreatment of cells with 1-butanol, but not 3-butanol, suppressed EGCG-induced COX-2 expression and PGE synthesis. Furthermore, evidence that PLD was involved in EGCG-induced COX-2 expression was provided by the observations that COX-2 expression was stimulated by overexpression of PLD1 or PLD2 isozymes and treatment with phosphatidic acid (PA), and that prevention of PA dephosphorylation by 1-propranolol significantly potentiated COX-2 expression induced by EGCG. EGCG induced activation of p38 mitogen-activated protein kinase (p38 MAPK), and specific inhibition of p38 MAPK dramatically abolished EGCG-induced PLD activation, COX-2 expression, and PGE(2) formation. Moreover, protein kinase C (PKC) inhibition suppressed EGCG-induced p38 MAPK activation, COX-2 expression, and PGE(2) accumulation. The same pathways as those obtained (2)in the astrocytoma cells were active in primary rat astrocytes, suggesting the relevance of the findings. Collectively, our results demonstrate for the first time that PLD isozymes mediate EGCG-induced COX-2 expression through PKC and p38 in immortalized astroglial line and normal astrocyte cells.

ABT-963 [2-(3,4-Difluoro-phenyl)-4-(3-hydroxy-3-methyl-butoxy)-5-(4-methanesulfonyl-phenyl)-2H-pyridazin-3-one], A Highly Potent and Selective Disubstituted Pyridazinone Cyclooxgenase-2 Inhibitor

Nonsteriodal anti-inflammatory drugs (NSAIDs) are efficacious for the treatment of pain associated with inflammatory disease. Clinical experience with marketed selective cyclooxygenase-2 (COX-2) inhibitors (celecoxib, rofecoxib, and valdecoxib) has confirmed the utility of these agents in the treatment of inflammatory pain with an improved gastrointestinal safety profile relative to NSAID comparators. These COX-2 inhibitors belong to the same structural class. Each contains a core heterocyclic ring with two appropriately substituted phenyl rings appended to adjacent atoms. Here, we report the identification of vicinally disubstituted pyridazinones as potent and selective COX-2 inhibitors. The lead compound in the series, ABT-963 [2-(3,4-difluoro-phenyl)-4-(3-hydroxy-3-methyl-butoxy)-5-(4-methanesulfonyl-phenyl)-2H-pyridazin-3-one], has excellent selectivity (ratio of 276, COX-2/COX-1) in human whole blood, improved aqueous solubility compared with celecoxib and rofecoxib, high oral anti-inflammatory potency in vivo, and gastric safety in the animal studies. After oral administration, ABT-963 reduced prostaglandin E2 production in the rat carrageenan air pouch model (ED50 of 0.4 mg/kg) and reduced the edema in the carrageenan induced paw edema model with an ED30 of 1.9 mg/kg. ABT-963 dose dependently reduced nociception in the carrageenan hyperalgesia model (ED50 of 3.1 mg/kg). After 14 days of dosing in the adjuvant arthritis model, ABT-963 had an ED(50) of 1.0 mg/kg in reducing the swelling of the hind paws. Magnetic resonance imaging examination of the diseased paws in the adjuvant model showed that ABT-963 significantly reduced bone loss and soft tissue destruction. ABT-963 is a highly selective COX-2 inhibitor that may have utility in the treatment of the pain and inflammation associated with arthritis.

Expression of cyclooxygenase-2 (COX-2) in human esophageal cancer and in vitro inhibition by a specific COX-2 inhibitor, NS-398

BACKGROUND

The purpose of the present paper was to study the expression of cyclooxygenase-2 (COX-2) in normal squamous epithelium, squamous dysplasia and squamous cell carcinoma (SCC) of the esophagus, to elucidate the role of COX-2 in esophageal carcinogenesis, and to evaluate the in vitro effect and mechanism of a COX-2 inhibitor, NS-398, in inducing growth inhibition and apoptosis of human esophageal cancer cells.

METHODS

Biopsy specimens of esophageal dysplasia (n = 21), and surgical resections of SCC (n = 37) were compared with normal esophagus (n = 37) and analyzed by RT-PCR. Human esophageal cells were used for the study. Anti-proliferative effect was measured by MTT, apoptosis was determined by DNA fragmentation assay.

RESULTS

Marked COX-2 expression was shown in SCC and esophageal squamous dysplasia, and no marked COX-2 expression was observed in the normal squamous epithelium, respectively. NS-398 could inhibit esophageal cells growth in a dose-dependent manner, induce apoptosis, and elevate caspase-3 activity in vitro.

CONCLUSIONS

This study provides evidence that COX-2 is upregulated in the majority of cases of squamous dysplasia and SCC of esophagus, and that NS-398 can inhibit growth and induce apoptosis via activating caspase-3 activity in vitro. These results suggest that selective inhibitors of COX-2 may be an effective preventive and therapeutic option for esophageal carcinoma.

Gastric effects of the selective cyclooxygenase-2 inhibitor, celecoxib, in the rat

BACKGROUND

Recent studies have revealed that cyclooxygenase-2 is involved in the protection of the damaged gastric mucosa, mediating, in particular, the acceleration of ulcer healing and angiogenesis; therein, it has been suggested that selective cyclooxygenase-2 inhibitors, although safe in healthy stomach, may have deleterious effects on the injured gastric mucosa. Moreover, no information is available about direct effects of these drugs on gastric surface epithelium.

AIMS

To investigate the gastric effects of the selective cyclooxygenase-2 inhibitor, celecoxib, in healthy and damaged rat gastric mucosa.

METHODS

Gastric toxicity was studied in the rat by measuring gastric potential difference and mucosal lesions. Celecoxib was administered intragastrically, either in basal conditions or in combination with damaging (acetylsalicylic acid and ethanol) or protective (sodium nitroprusside and lipopolysaccharides from Escherichia coli) agents. The anti-inflammatory activity was evaluated in the carrageenan-induced paw oedema assay. The non-selective inhibitors indomethacin and acetylsalicylic acid were used for comparison.

RESULTS

In conscious rats celecoxib, indomethacin and acetylsalicylic acid significantly reduced the paw oedema induced by carrageenan. While acetylsalicylic acid and indomethacin significantly reduced basal gastric potential difference and caused gastric mucosal lesions, celecoxib was ineffective; moreover, it did not aggravate the direct damaging effect of intragastric ethanol or aspirin. Pretreatment with the non-selective nitric oxide synthase inhibitor N-nitro-L-argynine methyl ester did not significantly change the gastric effects of celecoxib. Both celecoxib and indomethacin prevented the gastroprotective effects induced by sodium nitroprusside (nitric oxide donor) or by bacterial lipopolysaccharides (inducer of nitric oxide synthesis). CONCLUSIONS. These data indicate that the selective cyclooxygenase-2 inhibitor celecoxib did not alter gastric mucosal barrier nor induced mucosal lesions in the healthy or nitric oxide-deficient rat gastric mucosa. However, cyclooxygenase-2 inhibition impaired nitric oxide-dependent gastroprotection, indicating that cyclooxygenase-2 derived prostaglandins may be involved in the gastric mucosal defence.

Cyclooxygenase-2 expression correlates with diminished survival in invasive breast cancer treated with mastectomy and radiotherapy

PURPOSE

To evaluate the relationship between cyclooxygenase-2 (COX-2) expression and pathologic features and outcome in invasive breast cancer.

METHODS AND MATERIALS

Formalin-fixed, paraffin-embedded tumor specimens from 23 women with invasive breast cancer were stained for COX-2 expression. All women underwent mastectomy and locoregional radiotherapy. The distribution (percentage of positive staining cells) and intensity of COX-2 expression within the tumor cells were compared with clinical factors, including stage, grade, lymph node involvement, and outcome.

RESULTS

For invasive breast cancer, the distribution and intensity of COX-2 tumor expression correlated significantly with diminished overall survival. The 5-year overall survival rate was 100% for patients with <75% of breast cancer cells expressing COX-2 compared with 49% for patients with > or =75% (p = 0.044). The 5-year overall survival rate was 100% for patients with COX-2 intensity <80 compared with 60% for patients with COX-2 intensity > or =80 (p = 0.018). The percentage and intensity of COX-2 expression also correlated significantly with disease-free survival. The percentage of cells expressing COX-2 was significantly greater in women <40 years old than in women > or =40 years old (81% vs. 59%, respectively, p = 0.04).

CONCLUSION

Both the distribution and the intensity of COX-2 expression correlated significantly with disease-free and overall survival in patients with invasive breast cancer. Younger patients with invasive breast cancer may have a greater percentage of COX-2 expression in their tumors.

Analgesic efficacy of a single dose of lumiracoxib compared with rofecoxib, celecoxib and placebo in the treatment of post-operative dental pain

This randomised, double-blind, placebo-controlled, parallel-group study compared the efficacy and tolerability of lumiracoxib (a novel COX-2 selective inhibitor) with rofecoxib, celecoxib and placebo in patients with moderate-to-severe post-operative dental pain. Following third molar extraction, patients received single oral doses of lumiracoxib 400 mg, rofecoxib 50 mg, celecoxib 200 mg or placebo (n = 355). Additional patients from a similar study, assigned to lumiracoxib, rofecoxib or placebo (n = 155), were included for analysis of the primary variable, Summed Pain Intensity Difference over the first 8 h post dose (SPID-8). For SPID-8, lumiracoxib was superior to rofecoxib (p < 0.05), celecoxib (p < 0.001) and placebo (p < 0.001). Lumiracoxib demonstrated the fastest onset of analgesia and the longest time to rescue medication use. Patient global evaluation of lumiracoxib was comparable to rofecoxib and superior to celecoxib and placebo. All treatments were well tolerated. Lumiracoxib 400 mg provides rapid, effective and sustained relief of post-operative dental pain, comparable or superior to rofecoxib.

COX-2 selective inhibitors: a literature review of analgesic efficacy and safety in oral-maxillofacial surgery

BACKGROUND

Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most commonly prescribed analgesic agents in surgical outpatients. Major limitations of NSAIDs are their gastrointestinal (GI) adverse events (perforation, ulceration, and bleeding), impairment of hemostatic function, and renal failure (with long-term therapy). A new class of NSAIDs, the COX-2 selective inhibitors (CSIs or Coxibs), have been developed with the aim of reducing the GI adverse events of traditional NSAIDs while maintaining their effective anti-inflammatory and analgesic properties.

OBJECTIVE

This is a narrative review of the literature aimed to discuss analgesic efficacy, clinical safety and cost-benefit ratio of CSIs in the treatment of post-oral surgery pain.

METHODS

Relevant drug and clinical studies of analgesic efficacy and safety of CSIs in the management of postoperative dental pain were identified through searches of MEDLINE/PubMed, in peer-reviewed journals of medicine and dentistry. The Food and Drug Administration Web site was searched for data of tolerability. Hand-searching included several dental journals and bibliographies of relevant studies. The last electronic search was conducted in April 2003.

RESULTS

Data from well-designed, randomized, controlled trials of CSIs on the management of post-oral surgery pain indicate that these drugs are as well-effective analgesic agents as traditional NSAIDs and offer clinical advantages in terms of GI safety and unimpaired platelet function. CSIs do not offer advantages of renal safety over traditional NSAIDs.

CONCLUSION

Although CSIs display analgesic efficacy similar to that of traditional NSAIDs in the treatment of acute, post-oral surgery pain, there is reasonable evidence that these new drugs are preferable in patients who are at an increased risk of developing serious upper-GI complications, in patients who take aspirin for cardiovascular comorbid conditions, and in those allergic to aspirin. Furthermore, CSIs may be given more safely than NSAIDs in perioperative settings, because of their lack of impairment of the blood-clotting. However, the high costs of CSIs available at present limit their routine use in the short period of postoperative dental pain-in most cases 2 to 4 days after surgery-because there is not an increased risk of developing serious GI complications with the use of cost-saving NSAIDs. The GI safety advantages of CSIs may improve the tolerability of long-duration analgesic therapies, such as cases of painful temporomandibular joint disorders and chronic orofacial pain. Further studies are needed to determine the cost-benefit ratio of using CSIs for the management of acute pain.

Contribution of conjugated linoleic acid to the suppression of inflammatory responses through the regulation of the NF-kappaB pathway

Data from a number of researchers have shown that conjugated linoleic acid (CLA) has some beneficial health activities in animal models. Because inflammatory responses are associated with pathophysiology of many diseases, the aim of this study is to explore the effect and mechanism of CLA in the regulation of lipopolysaccharide (LPS)-induced inflammatory responses in RAW 264.7 macrophages. The addition of increasing levels of CLA proportionally augmented the incorporation of CLA in cultures. CLA diminished LPS-induced mRNA and protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX2) as well as subsequent production of nitric oxide and prostaglandin E(2), respectively. We further examined the effect of CLA on LPS-induced NF-kappaB activation by Western blot and the electrophoretic mobility shift assay. The addition of CLA at 200 microM significantly diminished LPS-induced protein expression of the cytoplasmic phosphorylated inhibitor kappaBalpha and nuclear p65 as well as NF-kappaB nuclear protein-DNA binding affinity. In conclusion, our data suggest that CLA may inhibit LPS-induced inflammatory events in RAW 264.7 macrophages and this inhibitory activity of CLA, at least in part, occurs through CLA modulating the NF-kappaB activation and therefore negatively regulating expression of inflammatory mediators.

Cyclooxygenase-2 expression in squamous dysplasia and squamous cell carcinoma of the esophagus

Cyclooxygenase-2 (cox-2) overexpression has been observed in several types of human cancers and has been implicated in carcinogenesis. To elucidate the role of cox-2 in esophageal carcinogenesis, we evaluated the expression of cox-2 in normal squamous epithelium squamous epithelial dysplasia (n=47), and squamous cell carcinoma of the esophagus (n=86) by immunohistochemistry, reverse transcription-PCR assay, and western blotting. A significant overexpression of cox-2 was observed in esophageal squamous dysplasia and squamous cell carcinoma compared with normal squamous epithelium. The immunoreactive score of cox-2 expression, an index determined by intensity and positivity of cox-2 staining, was 0.71 +/- 0.46 (mean +/- SD) in normal squamous esophagus, 2.19 +/- 1.79 in squamous epithelial dysplasia, and 2.67 +/- 1.77 in squamous cell carcinoma. The results of immunohistochemistry were confirmed by a reverse transcription-PCR assay and western blotting analysis. Cox-2 expression level was correlated with proliferation activity assessed by proliferating cell nuclear antigen (PCNA) index and MIB-1 index in dysplastic lesion (r=0.55, P<0.01 with PCNA and r=0.72, P<0.01 with MIB-1) and carcinoma (r=0.56, P<0.01 with PCNA and r=0.72, P<0.01 with MIB-1). Elevated cox-2 expression was associated with high p53 expression (p<0.001) but not with clinicopathological features including age, sex, tumor size, histological grade, lymph node metastasis, and TNM stage. The results indicated that cox-2 may be involved in an early stage of squamous carcinogenesis of the esophagus, and that cox-2 overexpression was related to cell proliferation in esophageal squamous dysplasia and squamous cell carcinoma.

Synergistic inhibitory effect of ascorbic acid and acetylsalicylic acid on prostaglandin E2 release in primary rat microglia

Ascorbic acid (vitamin C) has been suggested to protect cerebral tissue in a variety of pathophysiological situations such as head trauma, ischemia or Alzheimer's disease. Most of these protective actions have been attributed to the antioxidative capacity of ascorbic acid. Besides the presence of elevated levels of oxygen radicals, prostaglandins produced by neurones and microglial cells seem to play an important role in prolonged tissue damage. We investigated whether ascorbic acid alone inhibits prostaglandin E2 (PGE2) synthesis and may augment the inhibitory effect of acetylsalicylic acid on prostaglandin synthesis. Ascorbic acid dose-dependently inhibited PGE2 synthesis in lipopolysaccharide-treated primary rat microglial cells (IC50 = 3.70 micro m). In combination with acetylsalicylic acid (IC50 = 1.85 micro m), ascorbic acid augmented the inhibitory effect of acetylsalicylic acid on PGE2 synthesis (IC50 = 0.25 micro m in combination with 100 micro m ascorbic acid). Ascorbic acid alone or in combination with acetylsalicylic acid did not inhibit cyclooxygenase-2 (COX-2) protein synthesis but inhibited COX-2 enzyme activity. Our results show that ascorbic acid and acetylsalicylic acid act synergistically in inhibiting PGE2 synthesis, which may help to explain a possible protective effect of ascorbic acid in various brain diseases.

Cyclooxygenase-2 and prostate carcinogenesis

In recent years a dramatic surge has occurred on studies defining to the role of cyclooxygenase (COX)-2 in causation and prevention of cancer. Prostaglandin (PG) endoperoxidase synthase also commonly referred to as COX is a key enzyme involved in the conversion of arachidonic acid to PGs and other eicosanoids. COX exists as two isoforms, namely COX-1 and COX-2 with distinct tissue distribution and physiological functions. COX-1 is constitutively expressed in many tissues and cell types and is involved in normal cellular physiological functions whereas COX-2 is pro-inflammatory in nature and is inducible by mitogens, cytokines, tumor promoters and growth factors. A large volume of data exists showing that COX-2 is overexpressed in a large number of human cancers and cancer cell lines. The possibility of COX-2 as a candidate player in cancer development and progression evolved from the epidemiological studies which suggest that regular use of aspirin or other non-steroidal anti-inflammatory drugs could significantly decrease the risk of developing cancers in experimental animals and in humans. In our recently published study (Prostate, 42 2000 73-78), we provided the first evidence that COX-2 is overexpressed in human prostate adenocarcinoma. Many other studies verified our initial observation and reported that compared to normal tissue, COX-2 is overexpressed in human prostate cancer. It should be noted that some recent work has suggested that COX-2 is only up-regulated in proliferative inflammatory atrophy of the prostate, but not in prostate carcinoma. In this scenario, COX-2 inhibitors could afford their effects against prostate carcinogenesis by modulating COX-2 activity in other cells in prostate. An exciting corollary to this ongoing work is that selective COX-2 inhibitors may exhibit chemopreventive and even chemotherapeutic effects against prostate carcinogenesis in humans.

Genetic alterations of human brain tumors as molecular prognostic factors

Despite a number of basic and clinical studies, it is still very difficult to improve the prognosis of patients with high-grade astrocytoma. However, the recent success of procarbazine, N-(2-chloroethyl)-N'-cyclohexyl-N-nitrosourea and vincristine (PCV) chemotherapy for oligodendrogliomas that have lost chromosomes 1p and 19q has encouraged the authors to evaluate the biological behavior of brain tumors by means of genetic analysis. Both the disorders of the p53/MDM2/p14(ARF) and the p16(INK4a)/RB signaling pathways have been found to play an essential role in tumorigenesis of various brain tumors. Herein, the authors summarize the genetic alterations of brain tumors by mainly focusing on two pathways that appear to affect significantly the patient prognosis.