A novel genetic model of selective COX-2 inhibition: comparison with COX-2 null mice

Prostaglandin H Synthase (PGHS) is a bi-functional enzyme with a cyclooxygenase (COX) activity and a functionally linked peroxidase (POX) activity that exists in two isoforms (COX-1, COX-2). Non-steroidal anti-inflammatory drugs (NSAIDs), including the selective COX-2 inhibitors, block COX activity while leaving POX activity unscathed. Recently, some selective COX-2 inhibitors were withdrawn from the market due to elevated cardiovascular risk in placebo-controlled trials. Mice deficient for PGHS2 were developed in 1995 and through numerous subsequent studies have revealed significant roles in renal development, ductus arteriosus patency/closure, skin carcinogenesis and cardiovascular function. In this short review, we compare a novel genetic COX-2 selective inhibition mouse model with the originally described COX-2 null mice in these different physiological functions.     

Cyclooxygenase-2 inhibitors: promise or peril?

The discovery of two isoforms of the cyclooxygenase enzyme, COX-1 and COX-2, and the development of COX-2-specific inhibitors as anti-inflammatories and analgesics have offered great promise that the therapeutic benefits of NSAIDs could be optimized through inhibition of COX-2, while minimizing their adverse side effect profile associated with inhibition of COX-1. While COX-2 specific inhibitors have proven to be efficacious in a variety of inflammatory conditions, exposure of large numbers of patients to these drugs in postmarketing studies have uncovered potential safety concerns that raise questions about the benefit/risk ratio of COX-2-specific NSAIDs compared to conventional NSAIDs. This article reviews the efficacy and safety profiles of COX-2-specific inhibitors, comparing them with conventional NSDAIDs.     

Cardiovascular and gastrointestinal effects of COX-2 inhibitors and NSAIDs: achieving a balance

Conventional 'nonselective' nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used for the treatment of pain and inflammation; however, the potential gastrointestinal risks associated with their use can be a cause for concern. In response to the adverse effects that can accompany nonselective NSAID use, selective cyclo-oxygenase (COX)-2 inhibitors were developed to target the COX-2 isoenzyme, thus providing anti-inflammatory and analgesic benefits while theoretically sparing the gastroprotective activity of the COX-1 isoenzyme. Data from large-scale clinical trials have confirmed that the COX-2 inhibitors are associated with substantial reductions in gastrointestinal risk in the majority of patients who do not receive aspirin. However, some or all of the gastrointestinal benefit of COX-2 inhibitors may be lost in patients who receive low, cardioprotective doses of aspirin, and recent evidence suggests that some of these agents, at some doses, may be associated with an increased risk for cardiovascular adverse events compared with no therapy. The risks and benefits of conventional NSAIDs and of COX-2 inhibitors must be weighed carefully; in clinical practice many patients who might benefit from NSAID or COX-2 therapy are likely to be elderly and at relatively high risk for gastrointestinal and cardiovascular adverse events. These patients are also more likely to be taking low-dose aspirin for cardiovascular prophylaxis and over-the-counter NSAIDs for pain. Identifying therapies that provide relief from arthritis related symptoms, confer optimum cardioprotection, and preserve the gastrointestinal mucosa is complex. Factors to consider include the interference of certain NSAIDs with the antiplatelet effects of aspirin, differences in the adverse gastrointestinal event rates among nonselective NSAIDs and selective COX-2 inhibitors, emerging data regarding the relative risks for cardiovascular events associated with these drugs, and the feasibility and cost of co-therapy with proton pump inhibitors.     

Podocyte-secreted angiopoietin-like-4 mediates proteinuria in glucocorticoid-sensitive nephrotic syndrome

The main manifestations of nephrotic syndrome include proteinuria, hypoalbuminemia, edema, hyperlipidemia and lipiduria. Common causes of nephrotic syndrome are diabetic nephropathy, minimal change disease (MCD), focal and segmental glomerulosclerosis (FSGS) and membranous nephropathy. Among the primary glomerular diseases, MCD is usually sensitive to glucocorticoid treatment, whereas the other diseases show variable responses. Despite the identification of key structural proteins in the glomerular capillary loop which may contribute to defects in ultrafiltration, many of the disease mechanisms of nephrotic syndrome remain unresolved. In this study, we show that the glomerular expression of angiopoietin-like-4 (Angptl4), a secreted glycoprotein, is glucocorticoid sensitive and is highly upregulated in the serum and in podocytes in experimental models of MCD and in the human disease. Podocyte-specific transgenic overexpression of Angptl4 (NPHS2-Angptl4) in rats induced nephrotic-range, and selective, proteinuria (over 500-fold increase in albuminuria), loss of glomerular basement membrane (GBM) charge and foot process effacement, whereas transgenic expression specifically in the adipose tissue (aP2-Angptl4) resulted in increased circulating Angptl4, but no proteinuria. Angptl4(-/-) mice that were injected with lipopolysaccharide (LPS) or nephritogenic antisera developed markedly less proteinuria than did control mice. Angptl4 secreted from podocytes in some forms of nephrotic syndrome lacks normal sialylation. When we fed the sialic acid precursor N-acetyl-D-mannosamine (ManNAc) to NPHS2-Angptl4 transgenic rats it increased the sialylation of Angptl4 and decreased albuminuria by more than 40%. These results suggest that podocyte-secreted Angptl4 has a key role in nephrotic syndrome.     

Evaluation of classical NSAIDs and COX-2 selective inhibitors on purified ovine enzymes and human whole blood.

Cyclooxygenase is the key enzyme in the biosynthesis of prostanoids, biologically active substances involved in several physiological processes and also in pathological conditions such as inflammation. It has been well known for 10 years that this enzyme exists under two forms: a constitutive (COX-1) and an inducible form (COX-2). Both enzymes are sensitive to inhibition by conventional non-steroidal anti-inflammatory drugs (NSAIDs). Observations were made that COX-1 was mainly involved in homeostatic processes, while the COX-2 expression was associated with pathological conditions leading to the development of COX-2 selective inhibitors. Several methods have been reported for the evaluation of the COX-1 and COX-2 inhibitory potency and selectivity of conventional or COX-2 selective NSAIDs. In this study, we evaluated the COXs inhibitory profile of both conventional NSAIDs and COX-2 selective inhibitors using two different in vitro methods: the first test was performed using purified enzymes while the second method consisted of a whole blood assay. The results obtained with reference drugs in these two assays will be discussed and compared in this article.     

Current state of therapy for pain and inflammation

Nonsteroidal anti-inflammatory drugs (NSAIDs), including both traditional nonselective NSAIDs and the selective cyclo-oxygenase (COX)-2 inhibitors, are among the most widely used medications in the USA. Traditional NSAIDs, although effective at relieving pain and inflammation, are associated with a significant increase in the risk for gastrointestinal adverse events. Throughout the 1990s these events were estimated to result in approximately 100,000 hospitalizations and 16,500 deaths each year nationally. Recent studies have indicated that the risk for serious NSAID gastropathy has declined substantially during the past decade as a result of a number of factors, including lower doses of NSAIDs, the use of gastroprotective agents such as proton pump inhibitors and misoprostol, and the introduction of the selective COX-2 inhibitors. One therapeutic approach that may reduce the risk for gastrointestinal side effects associated with traditional NSAIDs while retaining their efficacy is the inclusion of co-therapy with a proton pump inhibitor; these agents inhibit acid secretion and have been demonstrated to promote ulcer healing in patients with NSAID-related gastric ulcers. Alternatively, COX-2 selective agents have been used to treat patients at high risk for such events. Both nonselective and selective COX-2 inhibitors have now been shown to be associated with an increased risk for cardiovascular events. These studies, together with the outcomes of the recent US Food and Drug Administration decision to require 'black box' warnings regarding potential cardiovascular risks associated with NSAIDs, suggest that the use of COX-2 inhibitors as the sole strategy for gastroprotection in patients with arthritis and other pain syndromes must be reconsidered, particularly among those at risk for cardiovascular events.     

COX-2: Where are we in 2003? - Be strong and resolute: continue to use COX-2 selective inhibitors at recommended dosages in appropriate patients

Cyclooxygenase (COX)-2 selective inhibitors have been shown to have comparable efficacy to nonselective nonsteroidal anti-inflammatory drugs (NSAIDs) in the treatment of patients with osteoarthritis (OA) and rheumatoid arthritis (RA). Large outcome studies have shown that patients with OA and RA not taking low-dose aspirin have fewer symptomatic and complicated upper GI events when treated with COX-2 selective inhibitors than with nonselective NSAIDs. When used in recommended dosages, there is no convincing evidence that patients treated with COX-2 selective inhibitors have an increased incidence of cardiovascular thrombotic events, including non-fatal myocardial infarction, than patients treated with either placebo or nonselective NSAIDs other than naproxen. Co-therapy with low-dose aspirin is recommended in patients with OA and RA at increased risk for cardiovascular events; the need for gastroprotective therapy in such patients is controversial.     

COX-2: Where are we in 2003? - Be strong and resolute: continue to use COX-2 selective inhibitors at recommended dosages in appropriate patients

Cyclooxygenase (COX)-2 selective inhibitors have been shown to have comparable efficacy to nonselective nonsteroidal anti-inflammatory drugs (NSAIDs) in the treatment of patients with osteoarthritis (OA) and rheumatoid arthritis (RA). Large outcome studies have shown that patients with OA and RA not taking low-dose aspirin have fewer symptomatic and complicated upper GI events when treated with COX-2 selective inhibitors than with nonselective NSAIDs. When used in recommended dosages, there is no convincing evidence that patients treated with COX-2 selective inhibitors have an increased incidence of cardiovascular thrombotic events, including non-fatal myocardial infarction, than patients treated with either placebo or nonselective NSAIDs other than naproxen. Co-therapy with low-dose aspirin is recommended in patients with OA and RA at increased risk for cardiovascular events; the need for gastroprotective therapy in such patients is controversial.     

Changes in gene expression contribute to cancer prevention by COX inhibitors

Non-steroidal anti-inflammatory drugs (NSAIDs) are used primarily for the treatment of inflammatory diseases. However, certain NSAIDs also have a chemopreventive effect on the development of human colorectal and other cancers. NSAIDs inhibit cyclooxygenase-1 (COX-1) and/or cyclooxygenase-2 (COX-2) activity and considerable evidence supports a role for prostaglandins in cancer development. However, the chemopreventive effect of NSAIDs on colorectal and other cancers appears also to be partially independent of COX activity. COX inhibitors also alter the expression of a number of genes that influence cancer development. One such gene is NAG-1 (NSAID-Activated Gene), a critical gene regulated by a number of COX inhibitors and chemopreventive chemicals. Therefore, this article will discuss the evidence supporting the conclusion that the chemo-preventive activity of COX inhibitors is mediated, in part, by altered gene expression with an emphasis on NAG-1 studies. This review may also provide new insights into how chemicals and environmental factors influence cancer development. In view of the cardiovascular and gastrointestinal toxic side effects of COX-2 inhibitors and non-selective COX inhibitors, respectively, the results presented here may provide the basis for the development of a new family of anti-tumorigenic compounds acting independent of COX inhibition.     

The effectiveness of five strategies for the prevention of gastrointestinal toxicity induced by non-steroidal anti-inflammatory drugs: systematic review

Objectives To assess the effectiveness of five gastroprotective strategies for people taking non-steroidal anti-inflammatory drugs (NSAIDs)—H₂ receptor antagonists plus non-selective (or cyclo-oxygenase-1) NSAIDs; proton pump inhibitors plus non-selective NSAIDs; misoprostol plus non-selective NSAIDs; COX-2 selective NSAIDs; or COX-2 specific NSAIDs—in reducing serious gastrointestinal complications, symptomatic ulcers, serious cardiovascular or renal disease, and deaths, and improving quality of life.Data sources The Cochrane Library, Medline, Embase, Current Controlled Trials, and System for Information on Grey Literature in Europe (SIGLE) were searched to May 2002. Bibliographies and author contacts were used to identify further studies; non-English articles were included.Review methods Trial selection, data extraction, and quality assessment were performed independently, in duplicate. Articles were rejected only if the study was not a randomised controlled trial; did not assess a gastroprotective strategy versus placebo; included exclusively children or healthy volunteers; lasted less than 21 days; or no review outcomes were measured. Quality assessment included allocation concealment and baseline similarity.Random effects meta-analysis, meta-regression and subgrouping were used to pool effects and analyse associations with length of follow up, mean age, and baseline gastrointestinal status. Heterogeneity was examined and sensitivity analyses performed.Results Of 112 included randomised controlled trials (74 666 participants), five were judged to be at low risk of bias, and 138 deaths and 248 serious gastrointestinal events were reported overall. On comparing gastroprotective strategies versus placebo we found no evidence of effectiveness of H₂ receptor antagonists for any primary outcomes (few events reported); proton pump inhibitors may reduce the risk of symptomatic ulcers (relative risk 0.09, 95% confidence interval 0.02 to 0.47); misoprostol reduces the risk of serious gastrointestinal complications (0.57, 0.36 to 0.91) and symptomatic ulcers (0.36, 0.20 to 0.67); COX-2 selectives reduce the risk of symptomatic ulcers (0.41, 0.26 to 0.65) and COX-2 specifics reduce the risk of symptomatic ulcers (0.49, 0.38 to 0.62) and possibly serious gastrointestinal complications (0.55, 0.38 to 0.80). All strategies except COX-2 selectives reduce the risk of endoscopic ulcers (at least 3 mm in diameter).Conclusions Misoprostol, COX-2 specific and selective NSAIDs, and probably proton pump inhibitors significantly reduce the risk of symptomatic ulcers, and misoprostol and probably COX-2 specifics significantly reduce the risk of serious gastrointestinal complications, but data quality is low. More data on H₂ receptor antagonists and proton pump inhibitors are needed, as is better reporting of rare but important outcomes.     

Cyclooxygenase isoforms and atherosclerosis

Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used in the treatment of arthritis and pain. However, their long-term use is limited by gastrointestinal (GI) side effects such as gastric ulcers. NSAIDs act by inhibiting an enzyme called cyclooxygenase. Cyclooxygenase (COX) catalyses the generation of prostaglandins from arachidonic acid. Two isoforms of the enzyme exist--COX-1 and COX-2--both of which are targets for NSAIDs. Although they are associated with GI toxicity, NSAIDs have important antithrombotic and anti-inflammatory effects. The GI injury has been attributed to COX-1 inhibition and the anti-inflammatory effects to COX-2 inhibition. As COX-2 is traditionally viewed as an inducible enzyme, selective inhibition of COX-2 by 'coxibs' (selective COX-2 inhibitors) has been employed to achieve anti-inflammatory and analgesic effects without GI side effects. However, recently there have been suggestions that chronic administration of coxibs might increase the risk of cardiovascular events, such as atherosclerosis, compared with traditional NSAIDs. In vascular disease, there is increased expression of both COX-1 and COX-2, resulting in enhanced prostaglandin generation. The specific role of COX-1 and COX-2 in vascular regulation is still unknown but such knowledge is essential for the effective use of coxibs. Although more evidence is pointing to selective COX-1 inhibition as a therapeutic measure in inflammatory atherosclerosis, there are some studies that suggest that inhibition of COX-2 might have a potential benefit on atherosclerosis.     

The COX-2 inhibitor NS-398 causes T-cell developmental disruptions independent of COX-2 enzyme inhibition

Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit the function of cyclooxygenases, COX-1 and COX-2, which catalyze the first step in the synthesis of inflammatory mediators (PGE2). We sought to understand the roles of cyclooxygenases and NSAIDs in T-cell development. Our data show no significant defects in T-cell development in fetal thymic organ cultures of mice disrupted in both or either COX genes or in mice disrupted in either EP-1 or EP-2 receptor genes. On the other hand, NSAIDs reproducibly caused thymocyte developmental defects. However, the specific effects of the COX-2 inhibitors were not correlated with their potency for inhibition of COX-2 activity. We focused on the NS-398 COX-2 inhibitor and showed that its effects could not be reversed by exogenous PGE2. Furthermore, NS-398 was inhibitory even when its target, COX-2, was absent. These data show that the T-cell developmental effects of NS-398 are COX-2 and PGE2 independent.     

Stimulated recovery of perturbed haematopoiesis by inhibition of prostaglandin production — promising therapeutic strategy

Inhibitors of prostaglandin production, designated as classical non-steroidal anti-inflammatory drugs (NSAIDs) and acting on the base of non-selective inhibition of cyclooxygenases, have been found in numerous studies to potentiate recovery of perturbed haematopoiesis by removing the negative feedback control mediated by prostaglandins. However, classical NSAIDs show pronounced undesirable gastrointestinal side effects, which limits the possibility of their utilization for various pathophysiological states including myelosuppression. Specific cyclooxygenase-2 (COX-2) inhibitors, targeted at selective inhibition of this inducible cyclooxygenase isoform and having much better gastrointestinal side effect profile, have been found in recent studies to retain the haematopoiesis-stimulating effects of classical NSAIDs. These results suggest that the indication spectrum of selective COX-2 inhibitors may be extended to the indication of myelosuppression of various etiology. Combining the anti-tumour and haematopoiesis-stimulating activities in a single COX-2 inhibitor may have a positive clinical impact.     

Action at a Distance: MUTATIONS OF PERIPHERAL RESIDUES TRANSFORM RAPID REVERSIBLE INHIBITORS TO SLOW,TIGHT BINDERS OF CYCLOOXYGENASE-2*

Cyclooxygenase enzymes (COX-1 and COX-2) catalyze the conversion of arachidonic acid to prostaglandin G₂. The inhibitory activity of rapid, reversible COX inhibitors (ibuprofen, naproxen, mefenamic acid, and lumiracoxib) demonstrated a significant increase in potency and time dependence of inhibition against double tryptophan murine COX-2 mutants at the 89/90 and 89/119 positions. In contrast, the slow, time-dependent COX inhibitors (diclofenac, indomethacin, and flurbiprofen) were unaffected by those mutations. Further mutagenesis studies suggested that mutation at position 89 was principally responsible for the changes in inhibitory potency of rapid, reversible inhibitors, whereas mutation at position 90 may exert some effect on the potency of COX-2-selective diarylheterocycle inhibitors; no effect was observed with mutation at position 119. Several crystal structures with or without NSAIDs indicated that placement of a bulky residue at position 89 caused a closure of a gap at the lobby, and alteration of histidine to tryptophan at position 90 changed the electrostatic profile of the side pocket of COX-2. Thus, these two residues, especially Val-89 at the lobby region, are crucial for the entrance and exit of some NSAIDs from the COX active site.     

The ever-emerging anti-inflammatories. Have there been any real advances?

Gastrointestinal (GI) Adverse Drug Reactions (ADRs) from the NSAIDs are a major cause of morbidity and mortality in arthritic patients taking these drugs. The recent much heralded development of COX-2 selective drugs (celecoxib, rofecoxib), the objective of which has been to spare inhibition of the production of COX-1 derived mucosal protective prostaglandins, may have represented an advance in reducing the risk of serious ADRs--ulcers and bleeding--but does not appear to have reduced the incidence of symptomatic side-effects (nausea, vomiting, epigastric pain/heartburn, abdominal discomfort) which are a major reason for withdrawal from NSAID therapy, especially in the long term. The rationale of COX-2 selectivity from these newer drugs is controversial since there may be pharmacokinetic differences from established carboxylate-NSAIDs that accounts for their apparent lower ulcerogenicity. Moreover, concerns have been recently expressed that as COX-2 is important in ulcer healing, control of prostacyclin production and renal function that they may have adverse reactions from these effects. Indeed, recent reports of enhanced risk of congestive heart failure with rofecoxib are of importance and may relate to impaired prostacyclin production. Moreover, there are other therapeutic strategies that have yielded equally low ulcerogenic NSAIDs (e.g. the prodrug, nabumetone; the established COX-2 inhibitory drug, nimesulide) and even the well-established NSAIDs ibuprofen and diclofenac have relatively low upper GI ulcerogenicity and have been used as benchmark standards in comparative trials of the newer "Oxib" drugs (celecoxib, rofecoxib). Much research interest has centred on the nitric oxide-donating NSAIDs (NO-NSAIDs). The rationale for donating NSAIDs being to counteract the vasoconstriction effects of NSAIDs but this has yet to be fully evaluated. It is not certain that this "antidote" approach will be acceptable as there may also be systemic effects of the nitrobutoxyl--or other NO-donors that may have toxicological consequences. Another strategy is the development of mixed COX-5 lipoxygenase (LOX) inhibitors--the progenitors of which were benoxaprofen and BW-755C. The rationale of reducing the potential for lipoxygenase mediated actions in the stomach (e.g. vasoconstriction, leucocyte accumulation). Clearly, the need to develop newer NSAIDs with lower risks of ulcers and bleeding as well as symptomatic ADRs is still representing a major challenge.     

Indolyl esters and amides related to indomethacin are selective COX-2 inhibitors

Previous studies from our laboratory have revealed that esterification/amidation of the carboxylic acid moiety in the nonsteroidal anti-inflammatory drug, indomethacin, generates potent and selective COX-2 inhibitors. In the present study, a series of reverse ester/amide derivatives were synthesized and evaluated as selective COX-2 inhibitors. Most of the reverse esters/amides displayed time-dependent COX-2 inhibition with IC₅₀ values in the low nanomolar range. Replacement of the 4-chlorobenzoyl group on the indole nitrogen with a 4-bromobenzyl moiety resulted in compounds that retained selective COX-2 inhibitory potency. In addition to inhibiting COX-2 activity in vitro, the reverse esters/amides also inhibited COX-2 activity in the mouse macrophage-like cell line, RAW264.7. Overall, this strategy broadens the scope of our previous methodology of neutralizing the carboxylic acid group in NSAIDs as a means of generating COX-2-selective inhibitors and is potentially applicable to other NSAIDs.     

NSAIDS inhibit in vitro MSC chondrogenesis but not osteogenesis: implications for mechanism of bone formation inhibition in man

The non-steroidal anti-inflammatory drugs (NSAIDs) are widely used for analgesia but may inhibit bone formation. We investigated whether the reported NSAID effect on bone is related to inhibition of bone marrow mesenchymal stem cell (MSC) proliferation and osteogenic and chondrogenic differentiation and evaluated both cyclooxygenase (COX)-1 and COX-2 specific drugs. The effects of seven COX-1 and COX-2 inhibitors on MSC proliferation and osteogenic and chondrogenic differentiation were tested using Vybrant, sodium 3′-[1-(phenylaminocarbonyl)- 3,4-tetrazolium]-bis (4-methoxy-6-nitro) benzene sulfonic acid hydrate (XTT), functional and quantitative assays of MSC differentiation. The MSC expression of COX-1 and COX-2 and prostaglandin E2 (PGE-2) levels were evaluated serially during lineage differentiation by quantitative PCR and ELISA. None of the NSAIDs at broad range of concentration (range 10⁻³ to 100 μg/ml) significantly affected MSC proliferation. Surprisingly, MSC osteogenic differentiation inhibition was not evident. However, NSAIDs affected chondrogenic potential with a reduction in sulphated glycosaminoglycans (sGAG) content by 45% and 55% with diclofenac and ketorolac, respectively (P < 0.05 compared to controls). Parecoxib and meloxicam, more COX-2 specific reagents inhibited sGAG to a lesser degree, 22% and 27% respectively (P < 0.05 compared to controls). Cartilage pellet immunohistochemistry confirmed the above results. Pellet chondrogenesis was associated with increased COX-1 expression levels but not COX-2, and COX-1 specific drugs suppressed MSC PGE-2 more than COX-2 specific inhibitors. These findings suggest that NSAIDs may inhibit bone formation via blockage of MSC chondrogenic differentiation which is an important intermediate phase in normal endochondral bone formation.     

Design,Synthesis and Biological Evaluation of New N-Acyl Hydrazones with a Methyl Sulfonyl Moiety as Selective COX-2 Inhibitors

The mechanism of action of nonsteroidal anti-inflammatory drugs (NSAIDs) is inhibition of specific prostaglandin (PG) synthesis by inhibition of cyclooxygenase (COX) enzymes. The two COX isoenzymes show 60 % similarity. It is known that the nonspecific side effects of conventional NSAIDs are physiologically caused by inhibition of the COX-1 enzyme. Therefore, the use of COX-2 selective inhibitors is seen to be a more beneficial approach in reducing these negative effects. However, some of the existing COX-2 selective inhibitors show cardiovascular side effects. Therefore, studies on the development of new selective COX-2 inhibitors remain necessary. It is important to develop new COX-2 inhibitors in the field of medicinal chemistry. Accordingly, novel N-acyl hydrazone derivatives were synthesized as new COX-2 inhibitors in this study. The hydrazone structure, also known for its COX activity, is important in terms of many biological activities and was preferred as the main structure in the design of these compounds. A methyl sulfonyl pharmacophore was added to the structure in order to increase the affinity for the polar side pocket present in the COX-2 enzyme. It is known that methyl sulfonyl groups are suitable for polar side pockets. The synthesis of the compounds ( 3a – 3j ) was characterized by spectroscopic methods. Evaluation of in vitro COX-1/COX-2 enzyme inhibition was performed by fluorometric method. According to the enzyme inhibition results, the obtained compounds displayed the predicted selectivity for COX-2 enzyme inhibition. Compound 3j showed important COX-2 inhibition with a value of IC₅₀=0.143 uM. Interaction modes between the COX-2 enzyme and compound 3j were investigated by docking studies.     

In vitro antiproliferative activity against human colon cancer cell lines of representative 4-thiazolidinones. Part I

The characterization of two cyclooxygenase isoforms (COX), the rate-limiting enzyme for the synthesis of prostaglandins (PGs) from arachidonic acid, has allowed the development of COX-2 selective inhibitors as non-steroidal anti-inflammatory drugs (NSAIDs) with significant gastric tolerability. However, PGs are also important in cancer pathogenesis. Thus, there is an increasing interest in studying COX-2 inhibitors as potential drugs aimed at the prevention and treatment of cancer, especially colorectal cancer. The purpose of this study was to determine the inhibitory effects of some representative 4-thiazolidinones, already widely investigated as potential NSAIDs, on the growth of five human colon carcinoma cell lines with a different COX-2 expression, and to correlate them with COX-2 inhibitory properties. Our results preliminarily revealed that 2-phenylimino derivative 3 and 2,4-thiazolidindione 4 were the most active compounds. In particular, 3 mainly inhibited the HT29 cell line characterized by a high COX-2 expression, whereas 4 showed antiproliferative properties on all tested cell lines, suggesting molecular targets other than COX-2 inhibition.     

Inhibition of angiogenesis by nonsteroidal anti-inflammatory drugs: insight into mechanisms and implications for cancer growth and ulcer healing

Angiogenesis, the formation of new capillary blood vessels, is essential not only for the growth and metastasis of solid tumors, but also for wound and ulcer healing, because without the restoration of blood flow, oxygen and nutrients cannot be delivered to the healing site. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, indomethacin and ibuprofen are the most widely used drugs for pain, arthritis, cardiovascular diseases and, more recently, the prevention of colon cancer and Alzheimer disease. However, NSAIDs produce gastroduodenal ulcers in about 25% of users (often with bleeding and/or perforations) and delay ulcer healing, presumably by blocking prostaglandin synthesis from cyclooxygenase (COX)-1 and COX-2 (ref. 10). The hypothesis that the gastrointestinal side effects of NSAIDs result from inhibition of COX-1, but not COX-2 (ref. 11), prompted the development of NSAIDs that selectively inhibit only COX-2 (such as celecoxib and rofecoxib). Our study demonstrates that both selective and nonselective NSAIDs inhibit angiogenesis through direct effects on endothelial cells. We also show that this action involves inhibition of mitogen-activated protein (MAP) kinase (ERK2) activity, interference with ERK nuclear translocation, is independent of protein kinase C and has prostaglandin-dependent and prostaglandin-independent components. Finally, we show that both COX-1 and COX-2 are important for the regulation of angiogenesis. These findings challenge the premise that selective COX-2 inhibitors will not affect the gastrointestinal tract and ulcer/wound healing.