Modulation of oxidant status by meloxicam in experimentally induced arthritis

Synthesis, Spectroscopic and Biological Investigation of a New Ca(II) Complex of Meloxicam as Potential COX-2 Inhibitor

Drug development on basis of coordination compounds provides versatile structural and functional properties as compared to other organic compounds. In the present study, a new Ca(II) complex of meloxicam was synthesized and characterized by elemental analysis, FT-IR, UV–Vis, ¹³C NMR, SEM–EDX, powder XRD and thermal analysis (TGA). The Ca(II) complex was investigated for its in vitro, in vivo biological activities and in silico docking analysis against COX-1 and COX-2. The spectral analysis indicates that the meloxicam acts as a deprotonated bidentate ligand (coordinated to the metal atom through the amide oxygen and the nitrogen atom of the thiazolyl ring) in the complex. SEM–EDX and powder XRD analysis depicted crystalline morphology of Ca(II) complex with a crystalline size of 32.86 nm. The in vitro biological activities were evaluated by five different antioxidant methods and COX inhibition assay, while in vivo activities were evaluated by carrageenan-, histamine- and PGE₂-induced paw edema methods and acetic acid-induced writhing test. The Ca(II) complex showed prominent antioxidant activities and was found to be more selective toward COX-2 (43.77) than COX-1 as compared to meloxicam. It exhibited lower toxicity (LD₅₀ 1000 mg/Kg) and significantly inhibited carrageenan- and PGE₂-induced inflammation at 10 mg/Kg (P < 0.05), but no significant effect was observed on histamine-induced inflammation. Moreover, Ca(II) complex significantly reduced the number of writhes induced by acetic acid (P < 0.05). The in silico molecular docking data revealed that Ca(II) complex obstructed COX-2 (dock score 6438) more effectively than COX-1 (dock score 5732) as compared to meloxicam alone.

Effects of buprenorphine on model development in an adjuvant-induced monoarthritis rat model

Complete Freund’s adjuvant (CFA)-induced arthritis in rats is a common animal model for studying chronic inflammatory pain. However, modelling of the disease is associated with unnecessary pain and impaired animal wellbeing, particularly in the immediate post-induction phase. Few attempts have been made to counteract these adverse effects with analgesics. The present study investigated the effect of buprenorphine on animal welfare, pain-related behaviour and model-specific parameters during the disease progression in a rat model of CFA-induced monoarthritis. The aim was to reduce or eliminate unnecessary pain in this model, in order to improve animal welfare and to avoid suffering, without compromising the quality of the model. Twenty-four male Sprague Dawley rats were injected with 20 μl of CFA into the left tibio-tarsal joint to induce monoarthritis. Rats were treated with either buprenorphine or carprofen for 15 days during the disease development, and were compared to a saline-treated CFA-injected group or a negative control group. Measurements of welfare, pain-related behaviour and clinical model-specific parameters were collected. The study was terminated after 3 weeks, ending with a histopathologic analysis. Regardless of treatment, CFA-injected rats displayed mechanical hyperalgesia and developed severe histopathological changes associated with arthritis. However, no severe effects on general welfare were found at any time. Buprenorphine treatment reduced facial pain expression scores, improved mobility, stance and lameness scores and it did not supress the CFA-induced ankle swelling, contrary to carprofen. Although buprenorphine failed to demonstrate a robust analgesic effect on the mechanical hyperalgesia in this study, it did not interfere with the development of the intended pathology.

A Review of the Effects of Pain and Analgesia on Immune System Function and Inflammation: Relevance for Preclinical Studies

One of the most significant challenges facing investigators, laboratory animal veterinarians, and IACUCs, is how to balance appropriate analgesic use, animal welfare, and analgesic impact on experimental results. This is particularly true for in vivo studies on immune system function and inflammatory disease. Often times the effects of analgesic drugs on a particular immune function or model are incomplete or don't exist. Further complicating the picture is evidence of the very tight integration and bidirectional functionality between the immune system and branches of the nervous system involved in nociception and pain. These relationships have advanced the concept of understanding pain as a protective neuroimmune function and recognizing pathologic pain as a neuroimmune disease. This review strives to summarize extant literature on the effects of pain and analgesia on immune system function and inflammation in the context of preclinical in vivo studies. The authors hope this work will help to guide selection of analgesics for preclinical studies of inflammatory disease and immune system function.

Blood Glutathione Peroxidase Activity in Patients with Osteoarthritis Treated with Oxicams

PURPOSE

The main objective of this study was the comparison of the influence for three non-steroidal anti-inflammatory drugs (NSAIDs) belonging to the oxicam class, namely piroxicam and tenoxicam, as non-selective inhibitors of cyclooxygenase (COX), and meloxicam, a selective COX-2 inhibitor, on glutathione peroxidase (GPx) activity in patients with osteoarthritis of the knee.

MATERIAL/METHODS

Thirty adult subjects clinically and radiographically diagnosed with knee osteoarthritis, who were not previously subjected to any treatment, were enrolled. They were divided in three groups, each with ten subjects. The serum levels of GPx were assessed at baseline and after twenty days of treatment. The first group received piroxicam at a dose of 20 mg orally daily, the second group was treated with tenoxicam at a dose of 20 mg orally daily, and in the third group meloxicam was administrated in a dose of 15 mg orally daily.

RESULTS

After the treatment, it was observed an increase of the GPx activity in all groups. The group treated with meloxicam presented the highest rise in the GPx level (p = 0.052).

CONCLUSIONS

The 20 days study concerning the effects of treatment with NSAIDs belonging to the oxicam class in subjects with knee osteoarthritis revealed that piroxicam, tenoxicam and meloxicam determined a slightly increase in the GPx activity, although this rise had no statistical significance.

Meloxicam inhibits fipronil-induced apoptosis via modulation of the oxidative stress and inflammatory response in SH-SY5Y cells

Oxidative stress and inflammatory responses have been identified as key elements of neuronal cell apoptosis. In this study, we investigated the mechanisms by which inflammatory responses contribute to apoptosis in human neuroblastoma SH-SY5Y cells treated with fipronil (FPN). Based on the cytotoxic mechanism of FPN, we examined the neuroprotective effects of meloxicam against FPN-induced neuronal cell death. Treatment of SH-SY5Y cells with FPN induced apoptosis via activation of caspase-9 and -3, leading to nuclear condensation. In addition, FPN induced oxidative stress and increased expression of cyclooxygenase-2 (COX-2) and tumor necrosis factor-α (TNF-α) via inflammatory stimulation. Pretreatment of cells with meloxicam enhanced the viability of FPN-exposed cells through attenuation of oxidative stress and inflammatory response. FPN activated mitogen activated protein kinase (MAPK) and inhibitors of MAPK abolished FPN-induced COX-2 expression. Meloxicam also attenuated FPN-induced cell death by reducing MAPK-mediated pro-inflammatory factors. Furthermore, we observed both nuclear accumulation of p53 and enhanced levels of cytosolic p53 in a concentration-dependent manner after FPN treatment. Pretreatment of cells with meloxicam blocked the translocation of p53 from the cytosol to the nucleus. Together, these data suggest that meloxicam may exert anti-apoptotic effects against FPN-induced cytotoxicity by both attenuating oxidative stress and inhibiting the inflammatory cascade via inactivation of MAPK and p53 signaling.

Cyclooxygenase-2 inhibition improves antioxidative defense during experimental hypercholesterolemia

Scientific literature shows that inflammation and oxidative stress contribute in the pathogenesis of atherosclerosis. The oxidative stress is the consequence of an imbalance between the free radical generation and elimination. One source of free oxygen radicals is cyclooxygenase (COX)-2 and, therefore, inhibiting the activity of this enzyme is likely to reduce oxidative stress. In the present study an experimental rabbit model of hypercholesterolemia was developed and the effects of COX-2 inhibitors, nimesulide and celecoxib were observed on the activities of antioxidant enzymes, superoxide dismutase (SOD), glutathione peroxidase (GPx) and total antioxidant status (TAS). Rabbits were divided into four groups- control, saline, nimesulide and celecoxib, with all groups fed a high cholesterol diet, which only received saline. Low activities of SOD, GPx and TAS were measured in the hypercholesterolemic rabbits pretreated with saline. In the same group, a reciprocal relationship was observed between the LDL-cholesterol concentration and the plasma activities of GPx, SOD and TAS. Rabbits in nimesulide and celecoxib group showed significantly higher activities of SOD, GPx and TAS in hypercholesterolemic rabbits compared to saline group (p<0.05). Our study shows that selective and timely use of COX-2 inhibitors would be useful in preventing the onset and development of atherosclerosis by enhancing antioxidant defence system.

Evaluation of the reproductive toxicity of naproxen sodium and meloxicam in male rats

Nonsteroidal anti-inflammatory drugs that are cyclooxygenase (COX) enzyme inhibitors have generally been used in short-term pain management and also to treat inflammation chronically. It is known that COX enzyme and prostaglandins play important roles in the regulation of reproductive functions in females. However, there are relatively few studies for the male reproductive system, and the results of these studies are contradictory. In this study, sperm count and motility, COX-1, COX-2, prostaglandin E1 (PGE1), prostaglandin E2 (PGE2), and prostaglandin F2α (PGF2α) levels in testis tissue, plasma follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone levels, and histopathological examination of testis tissue were evaluated after naproxen sodium and meloxicam administration in male rats. Also, testis superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), and glutathione (GSH) levels were measured to investigate the oxidation status. According to our results, sperm count and motility were significantly decreased in treatment groups. Plasma hormone levels did not show any statistical differences between the groups. COX-1, PGE2, and PGF2α levels were significantly decreased, while the decreases in COX-2 and PGE1 levels did not show any significance statistically. Testis SOD, catalase, GPx, and GSH levels were decreased significantly. According to the results of histopathological examination, damage in seminiferous tubules, where spermatogenesis developed, was observed. In conclusion, naproxen sodium and meloxicam decreased the sperm count and motility and also induced the damage of seminiferous tubules as a direct effect without affecting plasma hormone levels in our study. The mechanism of the reproductive toxicity induced by these agents may be based on the inhibition of prostaglandin synthesis and the induction of oxidative stress can be emphasized as a secondary factor.

Meloxicam exerts neuroprotection on spinal cord trauma in rats

Traumatic injury to the central nervous system results in the delayed dysfunction and neuronal death. Impaired mitochondrial function, generation of reactive oxygen species (ROS), and lipid peroxidation occur soon after traumatic spinal cord injury (SCI), while the activation of compensatory molecules that neutralize ROS occurs at later time points. The aim of the current study was to investigate the putative neuroprotective effect of the COX2 inhibitor meloxicam in a rat model of SCI. In order to induce SCI, a standard weight-drop method that induced a moderately severe injury (100 g/cm force) at T10, was used. Injured animals were given either 2 mg/kg meloxicam or saline 30 min postinjury by intraperitoneal injection. At seven days postinjury, neurological examination was performed and rats were decapitated. Spinal cord samples were taken for histological examination or determination of malondialdehyde (MDA) and glutathione (GSH) levels, myeloperoxidase (MPO) activity and DNA fragmentation. Formation of ROS in spinal cord tissue samples was monitored by using a chemiluminescence (CL) technique. SCI caused a significant decrease in spinal cord GSH content, which was accompanied with significant increases in CL, MDA levels, MPO activity, and DNA damage. On the other hand, meloxicam treatment reversed all these biochemical parameters as well as SCI-induced histopathological alterations. Furthermore, impairment of the neurological functions due to SCI was improved by meloxicam treatment. The present study suggests that meloxicam, reduces SCI-induced oxidative stress and exerts neuroprotection by inhibiting lipid peroxidation, GSH depletion, and DNA fragmentation.

Anti-fibrotic effect of meloxicam in a murine lung fibrosis model

A murine lung fibrosis model has been induced by challenging male Swiss albino mice with a fibrotic dose of bleomycin (10 mg/kg body weight, s.c.) twice weekly for 6 weeks. The model has been characterized and confirmed biochemically, histologically and morphometrically. Keeping in mind that inflammation is the forerunner of lung fibrosis, we have investigated the possible anti-fibrotic effect of meloxicam; a selective COX-2 inhibitor, in this lung fibrosis paradigm. When administered ahead of bleomycin challenge, meloxicam significantly reduced the lung content of hydroxyproline; the backbone of collagen matrix. This was further confirmed by the lower collagen deposition as revealed by histochemical examination of lung sections. Meloxicam had also anti-oxidant effect as shown by increase in lung reduced glutathione (GSH) level and decreases in lung malonedialdehyde (MDA) content and myeloperoxidase (MPO) activity. Besides, meloxicam has shown an apparent angiostatic activity. Histologically, meloxicam lessened lung inflammation and fibrotic changes induced by bleomycin. Taken together, one could conclude that meloxicam has shown anti-fibrotic effect in the bleomycin lung fibrosis model. Apart from its well-known anti-inflammatory potential, this anti-fibrotic action of meloxicam resides most probably, at least partly, in its anti-oxidant and angiostatic effects.

The non-psychoactive cannabis constituent cannabidiol is an orally effective therapeutic agent in rat chronic inflammatory and neuropathic pain

Cannabidiol, the major psycho-inactive component of cannabis, has substantial anti-inflammatory and immunomodulatory effects. This study investigated its therapeutic potential on neuropathic (sciatic nerve chronic constriction) and inflammatory pain (complete Freund's adjuvant intraplantar injection) in rats. In both models, daily oral treatment with cannabidiol (2.5-20 mg/kg to neuropathic and 20 mg/kg to adjuvant-injected rats) from day 7 to day 14 after the injury, or intraplantar injection, reduced hyperalgesia to thermal and mechanical stimuli. In the neuropathic animals, the anti-hyperalgesic effect of cannabidiol (20 mg/kg) was prevented by the vanilloid antagonist capsazepine (10 mg/kg, i.p.), but not by cannabinoid receptor antagonists. Cannabidiol's activity was associated with a reduction in the content of several mediators, such as prostaglandin E(2) (PGE(2)), lipid peroxide and nitric oxide (NO), and in the over-activity of glutathione-related enzymes. Cannabidiol only reduced the over-expression of constitutive endothelial NO synthase (NOS), without significantly affecting the inducible form (iNOS) in inflamed paw tissues. Cannabidiol had no effect on neuronal and iNOS isoforms in injured sciatic nerve. The compound's efficacy on neuropathic pain was not accompanied by any reduction in nuclear factor-kappaB (NF-kappaB) activation and tumor necrosis factor alpha (TNFalpha) content. The results indicate a potential for therapeutic use of cannabidiol in chronic painful states.

Interaction between inhibitors of inducible nitric oxide synthase and cyclooxygenase in adjuvant-induced arthritis in female albino rats: an isobolographic study

We studied the interaction of S-methylisothiourea (a selective inducible nitric oxide synthase inhibitor) with rofecoxib (a selective cyclooxygenase-2 inhibitor) and mefenamic acid (a non-selective cyclooxygenase inhibitor) in adjuvant-induced arthritis in female albino Wistar rats, applying the isobolographic analysis. Each drug was effective in reducing the progressive increase in paw volume less than 50% except rofecoxib, when used alone. Log dose-response curve was obtained for each drug along with the corresponding ED(25). Following isobolographic analysis, combination of S-methylisothiourea with rofecoxib and mefenamic acid revealed supra-additive or synergistic interaction. Experimental ED(25) of the combinations was significantly lower than the theoretical ED(25) of the corresponding drug combination which substantiated the synergistic type of interaction between inducible nitric oxide synthase and cyclooxygenase in adjuvant-induced arthritis in female albino rats. Results suggest that NO regulates the cyclooxygenase enzyme activity as the activity of cyclooxygenase enzymes in the LPS-stimulated leukocyte lysates was significantly low or hardly detectable in the presence of varying concentrations of S-methylisothiourea. Simultaneous inhibition of inducible nitric oxide synthase and cyclooxygenase appears to offer an alternative approach for ameliorating the progression of arthritis.

Oxidative-nitrosative stress and poly(ADP-ribose) polymerase (PARP) activation in experimental diabetic neuropathy: the relation is revisited

Poly(ADP-ribose) polymerase (PARP) activation, an important factor in the pathogenesis of diabetes complications, is considered a downstream effector of oxidative-nitrosative stress. However, some recent findings suggest that it is not necessarily the case and that PARP activation may precede and contribute to free radical and oxidant-induced injury. This study evaluated the effect of PARP inhibition on oxidative-nitrosative stress in diabetic peripheral nerve, vasa nervorum, aorta, and high glucose-exposed human Schwann cells. In vivo experiments were performed in control rats and streptozocin (STZ)-induced diabetic rats treated with and without the PARP inhibitor 3-aminobenzamide (ABA) (30 mg . kg(-1) . day(-1) i.p. for 2 weeks after 2 weeks of untreated diabetes). Human Schwann cells (HSC) (passages 7-10; ScienCell Research Labs) were cultured in 5.5 or 30 mmol/l glucose with and without 5 mmol/l ABA. Diabetes-induced increase in peripheral nerve nitrotyrosine immunoreactivity, epineurial vessel superoxide and nitrotyrosine immunoreactivities, and aortic superoxide production was reduced by ABA. PARP-1 (Western blot analysis) was abundantly expressed in HSC, and its expression was not affected by high glucose or ABA treatment. High-glucose-induced superoxide production and overexpression of nitrosylated and poly(ADP-ribosyl)ated protein, chemically reduced amino acid-(4)-hydroxynonenal adducts, and inducible nitric oxide synthase were decreased by ABA. We concluded that PARP activation contributes to superoxide anion radical and peroxynitrite formation in peripheral nerve, vasa nervorum, and aorta of STZ-induced diabetic rats and high- glucose-exposed HSC. The relations between oxidative-nitrosative stress and PARP activation in diabetes are bi- rather than unidirectional, and PARP activation cannot only result from but also lead to free radical and oxidant generation.

Inhibition of cyclooxygenase-2 improves cardiac function after myocardial infarction in the mouse

Cyclooxygenase (COX)-2 is expressed in the heart in animal models of ischemic injury. Recent studies have suggested that COX-2 products are involved in inflammatory cell infiltration and fibroblast proliferation in the heart. Using a mouse model, we questioned whether 1) myocardial infarction (MI) in vivo induces COX-2 expression chronically, and 2) COX-2 inhibition reduces collagen content and improves cardiac function in mice with MI. MI was produced by ligation of the left anterior descending coronary artery in mice. Two days later, mice were treated with 3 mg/kg NS-398, a selective COX-2 inhibitor, or vehicle in drinking water for 2 wk. After the treatment period, mice were subjected to two-dimensional M-mode echocardiography to determine cardiac function. Hearts were then analyzed for determination of infarct size, interstitial collagen content, brain natriuretic peptide (BNP) mRNA, myocyte cross-sectional area, and immunohistochemical staining for transforming growth factor (TGF)-β and COX-2. COX-2 protein, detected by immunohistochemistry, was increased in MI versus sham hearts. MI resulted in increased left ventricular systolic and diastolic dimension and decreased ejection fraction, fractional shortening, and cardiac output. NS-398 treatment partly reversed these detrimental changes. Myocyte cross-sectional area, a measure of hypertrophy, was decreased by 30% in the NS-398 versus vehicle group, but there was no effect on BNP mRNA. The interstitial collagen fraction increased from 5.4 ± 0.4% in sham hearts to 10.4 ± 0.9% in MI hearts and was decreased to 7.9 ± 0.6% in NS-398-treated hearts. A second COX-2 inhibitor, rofecoxib (MK-0966), also decreased myocyte cross-sectional area and interstitial collagen fraction. TGF-β, a key regulator of collagen synthesis, was increased in MI hearts. NS-398 treatment reduced TGF-β immunostaining by 40%. NS-398 treatment had no effect on infarct size. These results suggest that COX-2 products contribute to cardiac remodeling and functional deficits after MI. Thus selected inhibition of COX-2 may be a therapeutic target for reducing myocyte damage after MI.

Cyclooxygenase-2 (COX-2) in acute myocardial infarction: cellular expression and use of selective COX-2 inhibitor

Our previous work has shown strong expression of COX-2 in the myocardium of patients with end-stage ischemic heart failure. The purpose of this study was to determine the cellular expression of this enzyme in the setting of acute myocardial infarction (AMI) and determine the role of COX-2 in experimental animals using a selective COX-2 inhibitor. Experimental AMI was induced in rats by ligating the left coronary artery. Animals were either treated with a selective COX-2 inhibitor (5 mg x kg(-1) x day(-1)) or vehicle. Three days after ligation, cardiac function was assessed and infarct size was determined. Myocardial specimens were immunostained with antiserum to COX-2. Plasma concentration of prostanoids was measured by enzyme immunoassay. There was strong expression of COX-2 in the myocytes, endocardium, vascular endothelial cells, and macrophages in the infarcted zone of the myocardium. In contrast, little expression was seen in the myocardium of control rats. Animals treated with the COX-2 inhibitor showed a significant improvement in left ventricular (LV) end-diastolic pressure (P < 0.05) and LV systolic pressure (P < 0.01), and a reduction in infarct size (P < 0.05). Inhibition of COX-2 significantly decreased plasma concentration of thromboxane B2 (P < 0.05); however, it did not affect 6-keto-prostaglandin F1alpha. Induction of COX-2 during AMI appears to contribute to myocardial injury, and treatment with the specific inhibitor of the enzyme ameliorated the course of the disease.

Rethinking cystic fibrosis pathology: the critical role of abnormal reduced glutathione (GSH) transport caused by CFTR mutation

Though the cause of cystic fibrosis (CF) pathology is understood to be the mutation of the CFTR protein, it has been difficult to trace the exact mechanisms by which the pathology arises and progresses from the mutation. Recent research findings have noted that the CFTR channel is not only permeant to chloride anions, but other, larger organic anions, including reduced glutathione (GSH). This explains the longstanding finding of extracellular GSH deficit and dramatically reduced extracellular GSH:GSSG (glutathione disulfide) ratio found to be chronic and progressive in CF patients. Given the vital role of GSH as an antioxidant, a mucolytic, and a regulator of inflammation, immune response, and cell viability via its redox status in the human body, it is reasonable to hypothesize that this condition plays some role in the pathogenesis of CF. This hypothesis is advanced by comparing the literature on pathological phenomena associated with GSH deficiency to the literature documenting CF pathology, with striking similarities noted. Several puzzling hallmarks of CF pathology, including reduced exhaled NO, exaggerated inflammation with decreased immunocompetence, increased mucus viscoelasticity, and lack of appropriate apoptosis by infected epithelial cells, are better understood when abnormal GSH transport from epithelia (those without anion channels redundant to the CFTR at the apical surface) is added as an additional explanatory factor. Such epithelia should have normal levels of total glutathione (though perhaps with diminished GSH:GSSG ratio in the cytosol), but impaired GSH transport due to CFTR mutation should lead to progressive extracellular deficit of both total glutathione and GSH, and, hypothetically, GSH:GSSG ratio alteration or even total glutathione deficit in cells with redundant anion channels, such as leukocytes, lymphocytes, erythrocytes, and hepatocytes. Therapeutic implications, including alternative methods of GSH augmentation, are discussed.

Effects of captopril on interleukin-6, leukotriene B(4), and oxidative stress markers in serum and inflammatory exudate of arthritic rats: evidence of antiinflammatory activity

We previously demonstrated that captopril (CP) exhibited a high ability to inhibit enzymatically generated leukotrienes, particularly LTB(4), from stimulated intact human neutrophils. This finding together with the immunosuppressive effect of CP have proposed a possible antiinflammatory activity for the drug. Thus, the present study was conducted to investigate the effect of CP on immunologically mediated chronic inflammation; two models were chosen, namely, Freund's adjuvant arthritis and mixed-type hypersensitivity in rat. The effect of CP was assessed on the basis of physical parameter (paw edema) and biochemical markers in blood and inflammatory exudate. CP was given daily during the course of inflammation development. It was administered ip at three doses, viz. 1, 10, and 100 mg/kg. The results claimed that CP succeeded in suppressing edema evolution in hind paws of Freund's arthritic animals, during all phases of the disease. During the chronic phase of inflammation, in either model, CP reduced the elevated serum and exudate (local) LTB(4) and IL-6 levels. The effect on LTB(4) was more pronounced in the exudate and tended to be dose-related. The antiarthritic effect of CP was also accompanied by augmentation of serum level of protein thiols, with reduction or normalization of elevated systemic and/or local levels of lipid peroxide, superoxide dismutase, and glutathione. It could be concluded that long-term treatment with CP confers a good antiinflammatory activity against arthritis in rat, leading to improvement of the oxidative stress induced by the arthritic insult. The reparative effect of the drug could be mediated via reduction of LTB(4) and IL-6.

Biochemistry of cyclooxygenase (COX)-2 inhibitors and molecular pathology of COX-2 in neoplasia

Several types of human tumors overexpress cyclooxygenase (COX) -2 but not COX-1, and gene knockout transfection experiments demonstrate a central role of COX-2 in experimental tumorigenesis. COX-2 produces prostaglandins that inhibit apoptosis and stimulate angiogenesis and invasiveness. Selective COX-2 inhibitors reduce prostaglandin synthesis, restore apoptosis, and inhibit cancer cell proliferation. In animal studies they limit carcinogen-induced tumorigenesis. In contrast, aspirin-like nonselective NSAIDs such as sulindac and indomethacin inhibit not only the enzymatic action of the highly inducible, proinflammatory COX-2 but the constitutively expressed, cytoprotective COX-1 as well. Consequently, nonselective NSAIDs can cause platelet dysfunction, gastrointestinal ulceration, and kidney damage. For that reason, selective inhibition of COX-2 to treat neoplastic proliferation is preferable to nonselective inhibition. Selective COX-2 inhibitors, such as meloxicam, celecoxib (SC-58635), and rofecoxib (MK-0966), are NSAIDs that have been modified chemically to preferentially inhibit COX-2 but not COX-1. For instance, meloxicam inhibits the growth of cultured colon cancer cells (HCA-7 and Moser-S) that express COX-2 but has no effect on HCT-116 tumor cells that do not express COX-2. NS-398 induces apoptosis in COX-2 expressing LNCaP prostate cancer cells and, surprisingly, in colon cancer S/KS cells that does not express COX-2. This effect may due to induction of apoptosis through uncoupling of oxidative phosphorylation and down-regulation of Bcl-2, as has been demonstrated for some nonselective NSAIDs, for instance, flurbiprofen. COX-2 mRNA and COX-2 protein is constitutively expressed in the kidney, brain, spinal cord, and ductus deferens, and in the uterus during implantation. In addition, COX-2 is constitutively and dominantly expressed in the pancreatic islet cells. These findings might somewhat limit the use of presently available selective COX-2 inhibitors in cancer prevention but will probably not deter their successful application for the treatment of human cancers.

Inhibition of cyclooxygenase-2 improves cardiac function in myocardial infarction

Induction of cyclooxygenase-2 (COX-2) in ischemic myocardium is thought to increase the production of proinflammatory prostanoids and contribute significantly to the ischemic inflammation. Left ventricular myocardial infarction (MI) was created by ligating the left coronary artery in Lewis rats. Hemodynamic measurements at 4 weeks showed better cardiac function in the group treated with a selective COX-2 inhibitor (DFU; 5 mg/kg/day) for 2 weeks after induction of MI compared to the vehicle treated group. These results suggest that induction of COX-2 contributes to myocardial dysfunction, and that selective inhibition of COX-2 could constitute an important therapeutic target for the treatment of MI.