Cyclooxygenase Isozymes Research Articles

Degree of Cyclooxygenase-2 Inhibition Modulates Blood Pressure Response to Celecoxib and Naproxen.

Non-steroidal anti-inflammatory drugs (NSAIDs) increase the risk of adverse cardiovascular events via suppression of cyclooxygenase (COX)-2-derived prostacyclin (PGI2) formation in heart, vasculature, and kidney. The Prospective Randomized Evaluation of Celecoxib Integrated Safety versus Ibuprofen Or Naproxen (PRECISION) trial and other large clinical studies compared the cardiovascular risk of traditional NSAIDs (i.e. naproxen), which inhibit both COX isozymes, with NSAIDs selective for COX-2 (i.e. celecoxib). However, whether pharmacologically equipotent doses were used - that is, whether a similar degree of COX-2 inhibition was achieved - was not considered. We compared drug target inhibition and blood pressure response to celecoxib at the dose used by most patients in PRECISION with the lowest recommended naproxen dose for osteoarthritis, which is lower than the dose used in PRECISION. Sixteen healthy participants (19-61 years) were treated with celecoxib (100 mg every 12h), naproxen (250 mg every 12h), or placebo administered twice daily for seven days in a double-blind, crossover design randomized by order. On Day 7 when drug levels had reached steady state, the degree of COX inhibition was assessed ex vivo and in vivo. Ambulatory blood pressure was measured throughout the final 12h dosing interval. Both NSAIDs inhibited COX-2 activity relative to placebo, but naproxen inhibited COX-2 activity to a greater degree (62.9±21.7%) than celecoxib (35.7±25.2%; p<0.05). Similarly, naproxen treatment inhibited PGI2 formation in vivo (48.0±24.9%) to a greater degree than celecoxib (26.7±24.6%; p<0.05). Naproxen significantly increased blood pressure compared to celecoxib (differences in least-square means of mean arterial pressure: 2.5 mm Hg (95% CI: 1.5, 3.5); systolic blood pressure: 4.0 mm Hg (95% CI: 2.9, 5.1); diastolic blood pressure: 1.8 mm Hg (95% CI: 0.8, 2.8); p<0.05 for all). The difference in systolic blood pressure relative to placebo was associated with the degree of COX-2 inhibition (p<0.05). Celecoxib 200 mg/day inhibited COX-2 activity to a lesser degree than naproxen 500 mg/day, resulting in a less pronounced blood pressure increase. While the PRECISION trial concluded the non-inferiority of celecoxib regarding cardiovascular risk, this is based on a comparison of doses that are not equipotent.ClinicalTrials.gov identifier: NCT02502006 (https://clinicaltrials.gov/study/NCT02502006).

Prostanoids in Cardiac and Vascular Remodeling.

Prostanoids are biologically active lipids generated from arachidonic acid by the action of the COX (cyclooxygenase) isozymes. NSAIDs, which reduce the biosynthesis of prostanoids by inhibiting COX activity, are effective anti-inflammatory, antipyretic, and analgesic drugs. However, their use is limited by cardiovascular adverse effects, including myocardial infarction, stroke, hypertension, and heart failure. While it is well established that NSAIDs increase the risk of atherothrombotic events and hypertension by suppressing vasoprotective prostanoids, less is known about the link between NSAIDs and heart failure risk. Current evidence indicates that NSAIDs may increase the risk for heart failure by promoting adverse myocardial and vascular remodeling. Indeed, prostanoids play an important role in modulating structural and functional changes occurring in the myocardium and in the vasculature in response to physiological and pathological stimuli. This review will summarize current knowledge of the role of the different prostanoids in myocardial and vascular remodeling and explore how maladaptive remodeling can be counteracted by targeting specific prostanoids.

Nonsteroidal Anti-inflammatory Drug (NSAID) Toxicity in Emergency Room

Nonsteroidal anti-inflammatory medicines, collectively referred to as NSAIDs in academic context, exhibit chemical diversity while concurrently manifesting comparable therapeutic and harmful effects. All pharmaceutical substances under this particular category function by diminishing inflammation, alleviating pain, and reducing fever by means of inhibiting enzymes responsible for the creation of endoperoxides, often referred to as cyclooxygenase (COX) enzymes. The two cyclooxygenase isozymes, COX-1 and COX-2, are responsible for the conversion of arachidonic acid into its endoperoxide metabolites. These metabolites include prostacyclin, prostaglandins, and thromboxane, each exhibiting a wide range of biological activities such as inflammation, regulation of smooth muscle tone, and promotion of thrombosis. The COX-1 enzyme is consistently produced and is recognized as the main provider of prostanoids required for maintaining physiological balance, such as safeguarding the stomach epithelium. In contrast, the COX-2 enzyme is capable of being induced, leading to a substantial increase in the synthesis of prostanoids in circumstances characterized by stress and inflammation. Nonsteroidal anti-inflammatory drugs (NSAIDs) may induce toxicity via the same pharmacological mechanisms that contribute to their therapeutic efficacy. This review aims to discuss NSAIDs toxicity in details, its symptoms, and possible management in the emergency room.

Cyclooxygenases and platelet functions.

Cyclooxygenase (COX) isozymes, i.e., COX-1 and COX-2, are encoded by separate genes and are involved in the generation of the same products, prostaglandin (PG)G2 and PGH2 from arachidonic acid (AA) by the COX and peroxidase activities of the enzymes, respectively. PGH2 is then transformed into prostanoids in a tissue-dependent fashion due to the different expression of downstream synthases. Platelets present almost exclusively COX-1, which generates large amounts of thromboxane (TX)A2, a proaggregatory and vasoconstrictor mediator. This prostanoid plays a central role in atherothrombosis, as shown by the benefit of the antiplatelet agent low-dose aspirin, a preferential inhibitor of platelet COX-1. Recent findings have shown the relevant role played by platelets and TXA2 in developing chronic inflammation associated with several diseases, including tissue fibrosis and cancer. COX-2 is induced in response to inflammatory and mitogenic stimuli to generate PGE2 and PGI2 (prostacyclin), in inflammatory cells. However, PGI2 is constitutively expressed in vascular cells in vivo and plays a crucial role in protecting the cardiovascular systems due to its antiplatelet and vasodilator effects. Here, platelets' role in regulating COX-2 expression in cells of the inflammatory microenvironment is described. Thus, the selective inhibition of platelet COX-1-dependent TXA2 by low-dose aspirin prevents COX-2 induction in stromal cells leading to antifibrotic and antitumor effects. The biosynthesis and functions of other prostanoids, such as PGD2, and isoprostanes, are reported. In addition to aspirin, which inhibits platelet COX-1 activity, possible strategies to affect platelet functions by influencing platelet prostanoid receptors or synthases are discussed.

Comparison of COX-2 Selective and Traditional NSAIDs on Experimental Gastric Ulcer Healing in Humans

Background: Nonsteroidal anti-inflammatory drugs impair gastrointestinal ulcers healing. This study evaluated the role of cyclooxygenase isozymes COX- 1 and COX-2 in the healing of acute gastric ulcers in humans. Methods: This was an open-label, endoscopist-blind, parallel-group study, age and sex matched at baseline in normal volunteers. At endoscopy, we took four large jumbo forceps gastric mucosal biopsies (2 from each of the antrum and corpus). Subjects received celecoxib 200mg bid), naproxen 500mg bid), nabumetone 1000mg bid or placebo until end of study. Endoscopies were performed after 5 days and every 3 days until complete re-epithelialization of all lesions or 30 days. Survival analysis was used to compare time-to-healing defined as the day with complete re-epithelialization of all ulcers. Results: Fifty-two subjects completed the study, each received four biopsyinduced gastric ulcers (204 total ulcers; the majority included the muscularis mucosa). The mean time-to-healing was 9.4 ± 0.4 days with placebo, 10.5 ± 0.4 with celecoxib, 11.1 ± 0.6 with naproxen, and 12.3 ± 0.9 with nabumetone. The time to healing of each ulcer or all ulcers was significantly delayed compared to placebo with naproxen (p=0.01) and nabumetone (p=0.002) but not with celecoxib (p=0.07). Conclusion: The COX-1 preferential inhibitor naproxen and the balanced COX-1/COX-2 inhibitor nabumetone significantly delayed the healing of ulcers. With the COX-2 specific inhibitor celecoxib, healing was delayed but not significantly. Synthesis of COX-1 derived prostaglandins appears to be important in the healing of gastric ulcers in humans.

Drug Repurposing: A Network-based Approach to Amyotrophic Lateral Sclerosis.

The continuous adherence to the conventional "one target, one drug" paradigm has failed so far to provide effective therapeutic solutions for heterogeneous and multifactorial diseases as amyotrophic lateral sclerosis (ALS), a rare progressive and chronic, debilitating neurological disease for which no cure is available. The present study is aimed at finding innovative solutions and paradigms for therapy in ALS pathogenesis, by exploiting new insights from Network Medicine and drug repurposing strategies. To identify new drug-ALS disease associations, we exploited SAveRUNNER, a recently developed network-based algorithm for drug repurposing, which quantifies the proximity of disease-associated genes to drug targets in the human interactome. We prioritized 403 SAveRUNNER-predicted drugs according to decreasing values of network similarity with ALS. Among catecholamine, dopamine, serotonin, histamine, and GABA receptor modulators, as well as angiotensin-converting enzymes, cyclooxygenase isozymes, and serotonin transporter inhibitors, we found some interesting no customary ALS drugs, including amoxapine, clomipramine, mianserin, and modafinil. Furthermore, we strengthened the SAveRUNNER predictions by a gene set enrichment analysis that confirmed modafinil as a drug with the highest score among the 121 identified drugs with a score > 0. Our results contribute to gathering further proofs of innovative solutions for therapy in ALS pathogenesis.

Analysis of mRNA expression levels for cyclooxygenase isozymes and prostanoid synthases in the rat hypothalamic paraventricular nucleus after restraint stress

Analysis of mRNA expression levels for cyclooxygenase isozymes and prostanoid synthases in the rat hypothalamic paraventricular nucleus after restraint stress

NSAID-Gut Microbiota Interactions.

Nonsteroidal anti-inflammatory drugs (NSAID)s relieve pain, inflammation, and fever by inhibiting the activity of cyclooxygenase isozymes (COX-1 and COX-2). Despite their clinical efficacy, NSAIDs can cause gastrointestinal (GI) and cardiovascular (CV) complications. Moreover, NSAID use is characterized by a remarkable individual variability in the extent of COX isozyme inhibition, therapeutic efficacy, and incidence of adverse effects. The interaction between the gut microbiota and host has emerged as a key player in modulating host physiology, gut microbiota-related disorders, and metabolism of xenobiotics. Indeed, host–gut microbiota dynamic interactions influence NSAID disposition, therapeutic efficacy, and toxicity. The gut microbiota can directly cause chemical modifications of the NSAID or can indirectly influence its absorption or metabolism by regulating host metabolic enzymes or processes, which may have consequences for drug pharmacokinetic and pharmacodynamic properties. NSAID itself can directly impact the composition and function of the gut microbiota or indirectly alter the physiological properties or functions of the host which may, in turn, precipitate in dysbiosis. Thus, the complex interconnectedness between host–gut microbiota and drug may contribute to the variability in NSAID response and ultimately influence the outcome of NSAID therapy. Herein, we review the interplay between host–gut microbiota and NSAID and its consequences for both drug efficacy and toxicity, mainly in the GI tract. In addition, we highlight progress towards microbiota-based intervention to reduce NSAID-induced enteropathy.

Druggable Prostanoid Pathway.

Prostanoids (prostaglandins, prostacyclin and thromboxane) belong to the oxylipin family of biologically active lipids generated from arachidonic acid (AA). Protanoids control numerous physiological and pathological processes. Cyclooxygenase (COX) is a rate-limiting enzyme involved in the conversion of AA into prostanoids. There are two COX isozymes: the constitutive COX-1 and the inducible COX-2. COX-1 and COX-2 have similar structures, catalytic activities, and subcellular localizations but differ in patterns of expression and biological functions. Non-selective COX-1/2 or traditional, non-steroidal anti-inflammatory drugs (tNSAIDs) target both COX isoforms and are widely used to relieve pain, fever and inflammation. However, the use of NSAIDs is associated with various side effects, particularly in the gastrointestinal tract. NSAIDs selective for COX-2 inhibition (coxibs) were purposefully designed to spare gastrointestinal toxicity, but predisposed patients to increased cardiovascular risks. These health complications from NSAIDs prompted interest in the downstream effectors of the COX enzymes as novel drug targets. This chapter describes various safety issues with tNSAIDs and coxibs, and discusses the current development of novel classes of drugs targeting the prostanoid pathway, including nitrogen oxide- and hydrogen sulfide-releasing NSAIDs, inhibitors of prostanoid synthases, dual inhibitors, and prostanoid receptor agonists and antagonists.

Synthesis and biological evaluation of tetrazole derivatives as TNF-α, IL-6 and COX-2 inhibitors with antimicrobial activity: Computational analysis, molecular modeling study and region-specific cyclization using 2D NMR tools

A group of tetrazole bearing compounds were synthesized and evaluated for their in vitro cyclooxygenase (COX) isozymes (COX-1/COX-2) inhibitory activity, in vitro anti-inflammatory activity through measuring levels of expression of IL-6 and TNF-α and antimicrobial activity. Cyclization of pyridine derivative 5b was confirmed using 2D NMR such as NOESY and HMBC experiments. Within the synthesized compounds, compound 7c was identified as effective and selective COX-2 inhibitors (COX-2 IC50 = 0.23 uM; COX-2 selectivity index = 16.91). Moreover 7c was the most effective derivative on TNF-α (37.6 pg/ml). While, the most active compound on IL-6 was isoxazole derivative 6 (42.8 pg/ml). Dual inhibitory activity on both IL-6 and TNF-α was exhibited by compounds 2 and 3 (IL-6 = 47.5 and 82.7 pg/ml, respectively) and (TNF-α = 31.7 and 33.8 pg/ml, sequentially).Additionally, compound 7a, showed broad spectrum antimicrobial activity against Gram positive cocci, Gram positive rods and yeast fungus (inhibition zone = 20 and 19 mm). None of the test compounds exhibited activity against Gram negative rods. Compounds 3 and 7c exhibited good antifungal activity at MIC equal to 64.5 µg/ml. While compound 6 showed antibacterial activities against Micrococcus lysodicticus and Bacillus subtilis at MIC = 32.25 and 64.5 µg/ml, respectively.Computational analysis was used to predict molecular properties and bioactivity of the target compounds. To confirm the mode of action of the synthesized compounds as anti-inflammatory agents, molecular docking was done. Appreciable binding interactions were observed for compound 7c containing COX-2 pharmacophore (SO2NH2), with binding energy −10.6652 Kcal/mol, forming two hydrogen bonding interactions with His90 and Tyr355 amino acids. It was fully fitted within COX-2 active site having the highest COX-2 selectivity index between all the test compounds (S.I. = 16.91).

Structural alterations based on naproxen scaffold: Synthesis, evaluation of antitumor activity and COX-2 inhibition, and molecular docking

A new series of non-carboxylic naproxen analogues, bearing a variety of ring systems, such as oxadiazoles 3a–c and 6a–c, cycloalkanes 4a–d, cyclic imides 5a–c, and triazoles 7–9 and 10a–c, was synthesized. In addition, in vitro antitumor activity and cyclooxygenase isozymes (COX-1/COX-2) inhibition assay of the target compounds 3–10 was studied. The results of the antitumor activity assays indicated that compounds 4b, 6c, 10b, and 10c exhibited the greatest antitumor activities against the tested cell lines MCF-7, MDA-231, HeLa, and HCT-116, with an IC50 range of 4.83–14.49 μM. By comparison, the reference drugs doxorubicin, afatinib, and celecoxib yielded IC50 values of 3.18–26.79, 6.20–11.40, and 22.79–42.74 μM, respectively. Furthermore, in vitro COX-1/COX-2 inhibition testing showed that the compounds 4b, 6c, 10b, and 10c exhibited effective COX-2 inhibition, with IC50 values of 0.40–1.20 μM, and selectivity index (SI) values of >62.50–20.83, using celecoxib as a reference drug (IC50 = 0.11 μM; COX-2 SI: >227.20). Compounds 6c and 10c, which were potent COX-2 inhibitors, were docked into the COX-2 binding site, where these compounds exhibited strong interactions.

Proteomic Analysis Shows Constitutive Secretion of MIF and p53-associated Activity of COX-2−/− Lung Fibroblasts

The differential expression of two closelyassociated cyclooxygenase isozymes, COX-1 and COX-2, exhibited functions beyond eicosanoid metabolism. We hypothesized that COX-1 or COX-2 knockout lung fibroblasts may display altered protein profiles which may allow us to further differentiate the functional roles of these isozymes at the molecular level. Proteomic analysis shows constitutive production of macrophage migration inhibitory factor (MIF) in lung fibroblasts derived from COX-2−/− but not wild-type (WT) or COX-1−/− mice. MIF was spontaneously released in high levels into the extracellular milieu of COX2−/− fibroblasts seemingly from the preformed intracellular stores, with no change in the basal gene expression of MIF. The secretion and regulation of MIF in COX-2−/− was “prostaglandin-independent.” GO analysis showed that concurrent with upregulation of MIF, there is a significant surge in expression of genes related to fibroblast growth, FK506 binding proteins, and isomerase activity in COX-2−/− cells. Furthermore, COX-2−/− fibroblasts also exhibit a significant increase in transcriptional activity of various regulators, antagonists, and co-modulators of p53, as well as in the expression of oncogenes and related transcripts. Integrative Oncogenomics Cancer Browser (IntroGen) analysis shows downregulation of COX-2 and amplification of MIF and/or p53 activity during development of glioblastomas, ependymoma, and colon adenomas. These data indicate the functional role of the MIF-COX-p53 axis in inflammation and cancer at the genomic and proteomic levels in COX-2-ablated cells. This systematic analysis not only shows the proinflammatory state but also unveils a molecular signature of a pro-oncogenic state of COX-1 in COX-2 ablated cells.

Role of LPS-elicited signaling in triggering gastric mucosal inflammatory responses to H. pylori: modulatory effect of ghrelin.

Infection with Helicobacter pylori is a primary culprit in the etiology of gastric disease, and its cell-wall lipopolysaccharide (LPS) is recognized as a potent endotoxin responsible for triggering a pattern of the mucosal inflammatory responses. The engagement by the LPS of gastric mucosal Toll-like receptor 4 (TLR4) leads to initiation of signal transduction events characterized by the activation of mitogen-activated protein kinase (MAPK) cascade, induction of phosphoinositide-specific phospholipase C (PLC)/protein kinase C (PKC)/phosphatidylinositol 3-kinase (PI3K) pathway, and up-regulation in Src/Akt. These signaling events in turn exert their influence over H. pylori-elicited excessive generation of NO and PGE2 caused by the disturbances in nitric oxide synthase and cyclooxygenase isozyme systems, increase in epidermal growth factor receptor transactivation, and the induction in matrix metalloproteinase-9 (MMP-9) release. Interestingly, the extent of gastric mucosal inflammatory response to H. pylori is influenced by a peptide hormone, ghrelin, the action of which relays on the growth hormone secretagogue receptor type 1a (GHS-R1a)-mediated mobilization of G-protein dependent transduction pathways. Yet, the signals triggered by TLR-4 activation as well as those arising through GHS-R1a stimulation converge at MAPK and PLC/PKC/PI3K pathways that form a key integration node for proinflammatory signals generated by H. pylori LPS as well as for those involved in modulation of inflammation by ghrelin. Hence, therapeutic targeting these signals' convergence and integration node could provide a novel and attractive opportunities for developing more effective treatments of H. pylori-related gastric disease.

Regulatory mechanism of the gastric hyperemic response following barrier disruption: roles of cyclooxygenase-1, the prostaglandin E2/EP1 receptor and sensory neurons.

We herein reviewed the mechanism underlying the gastric hyperemic response following barrier disruption, with a focus on cyclooxygenase (COX) isozymes, prostaglandin (PG) E2, and capsaicin-sensitive afferent neurons. Mucosal damage was induced by exposing the stomach to 20 mM taurocholate (TC) with 50 mM HCl. The TC treatment disrupted surface epithelial cells, and then increased acid back-diffusion and mucosal blood flow (GMBF) in the stomachs of rats or wild-type mice. This hyperemic response in the rat stomach was inhibited by indomethacin without affecting acid back-diffusion, which resulted in the aggravation of lesions. The effect of indomethacin was mimicked by loxoprofen and the selective COX-1 inhibitor, SC-560, but not by the selective COX-2 inhibitor, celecoxib. The GMBF responses induced by TC were similarly observed in the stomachs of wild-type mice and EP3 receptor knockout mice, but not in mice lacking the EP1 receptor or pretreated with an EP1 antagonist. The increase in the GMBF response associated with acid back-diffusion after the TC treatment was also inhibited by the chemical ablation of capsaicin-sensitive afferent neurons, but not capsazepine, a TRPV1 antagonist. Thus, endogenous PGE2 produced by COX-1 plays a role in the gastric hyperemic response following barrier disruption of the stomach by interacting with capsaicin-sensitive afferent neurons, mainly through EP1 receptors, and facilitating the GMBF response to acid back-diffusion. These findings have also contributed to a deeper understanding of mucosal defensive mechanisms following barrier disruption and the development of new strategies for the treatment of gastrointestinal diseases.

New insights into the use of currently available non-steroidal anti-inflammatory drugs.

Non-steroidal anti-inflammatory drugs (NSAIDs), which act via inhibition of the cyclooxygenase (COX) isozymes, were discovered more than 100 years ago. They remain a key component of the pharmacological management of acute and chronic pain. The COX-1 and COX-2 isozymes have different biological functions; analgesic activity is primarily (although not exclusively) associated with inhibition of COX-2, while different side effects result from the inhibition of COX-1 and COX-2. All available NSAIDs, including acetaminophen and aspirin, are associated with potential side effects, particularly gastrointestinal and cardiovascular effects, related to their relative selectivity for COX-1 and COX-2. Since all NSAIDs exert their therapeutic activity through inhibition of the COX isozymes, strategies are needed to reduce the risks associated with NSAIDs while achieving sufficient pain relief. A better understanding of the inhibitory activity and COX-1/COX-2 selectivity of an NSAID at therapeutic doses, based on pharmacokinetic and pharmacodynamic properties (eg, inhibitory dose, absorption, plasma versus tissue distribution, and elimination), and the impact on drug tolerability and safety can guide the selection of appropriate NSAIDs for pain management. For example, many NSAIDs with moderate to high selectivity for COX-2 versus COX-1 can be administered at doses that maximize efficacy (~80% inhibition of COX-2) while minimizing COX-1 inhibition and associated side effects, such as gastrointestinal toxicity. Acidic NSAIDs with favorable tissue distribution and short plasma half-lives can additionally be dosed to provide near-constant analgesia while minimizing plasma concentrations to permit recovery of COX-mediated prostaglandin production in the vascular wall and other organs. Each patient’s clinical background, including gastrointestinal and cardiovascular risk factors, should be taken into account when selecting appropriate NSAIDs. New methods are emerging to assist clinicians in the selection of appropriate NSAIDs and their doses/schedules, such as biomarkers that may predict the response to NSAID treatment in individual patients.

Importance of cyclooxygenase-1/prostacyclin in modulating gastric mucosal integrity under stress conditions.

We investigated the roles of cyclooxygenase (COX) isozymes and prostaglandins (PGs) and their receptors in mucosal defense against cold-restraint stress (CRS)-induced gastric lesions. Male C57BL/6 wild-type (WT) mice and those lacking COX-1 or COX-2 as well as those lacking EP1, EP3, or IP receptors were used after 18 h fasting. Animals were restrained in Bollman cages and kept in a cold room at 10°C for 90 min. CRS induced multiple hemorrhagic lesions in WT mouse stomachs. The severity of these lesions was significantly worsened by pretreatment with the nonselective COX inhibitors (indomethacin, loxoprofen) or selective COX-1 inhibitor (SC-560), while neither of the selective COX-2 inhibitors (rofecoxib and celecoxib) had any effect. These lesions were also aggravated in animals lacking COX-1, but not COX-2. The expression of COX-2 mRNA was not detected in the stomach after CRS, while COX-1 expression was observed under normal and stressed conditions. The gastric ulcerogenic response to CRS was similar between EP1 or EP3 knockout mice and WT mice, but was markedly worsened in animals lacking IP receptors. Pretreating WT mice with iloprost (the PGI2 analog) significantly prevented CRS-induced gastric lesions in the presence of indomethacin. PGE2 also reduced the severity of these lesions, and the effect was mimicked by the EP4 agonist, AE1-329. These results suggest that endogenous PGs derived from COX-1 play a crucial role in gastric mucosal defense during CRS, and this action is mainly mediated by PGI2 /IP receptors and partly by PGE2 /EP4 receptors.

Fractals and self-organized criticality in anti-inflammatory drugs

Nonsteroidal anti-inflammatory drugs (NSAIDs) act through inhibiting prostaglandin synthesis, a catalytic activity possessed by two distinct cyclooxygenase (COX-1 and COX-2) isozymes encoded by separate genes. The discovery of COX-2 launched a new era in NSAID pharmacology, resulting in the synthesis, marketing, and widespread use of COX-2 selective inhibitors. Extensive structural studies of the biology of prostaglandin synthesis and inhibition have explained some of the differences between COX-1 and COX-2 functionality, but others are still unexplained. Notably these include molecular differences that cause COX-1 inhibitors to produce a slight decrease, and COX-2 inhibitors to induce a significant increase, in heart attacks and strokes. These differences were unexpected because of the 60% overall COX-1 and COX-2 sequence similarity and the 1–2 conservation of catalytic sites. Hydropathic analysis shows important bicyclic differences between COX-1 and COX-2 on a large scale outside the catalytic pocket. These differences involve much stronger amphiphilic interactions in COX-2 than in COX-1, and may explain the selective antiplatelet effectiveness of COX-2. Success of the non-Euclidean structural analysis is the result of using the new Brazilian hydropathicity scale based on self-organized criticality (SOC) of universal protein modules.

Staurosporine synergistically potentiates the deoxycholate-mediated induction of COX-2 expression.

Colorectal cancer is a major cause of cancer‐related death in western countries, and thus there is an urgent need to elucidate the mechanism of colorectal tumorigenesis. A diet that is rich in fat increases the risk of colorectal tumorigenesis. Bile acids, which are secreted in response to the ingestion of fat, have been shown to increase the risk of colorectal tumors. The expression of cyclooxygenase (COX)‐2, an inducible isozyme of cyclooxygenase, is induced by bile acids and correlates with the incidence and progression of cancers. In this study, we investigated the signal transduction pathways involved in the bile‐acid‐mediated induction of COX‐2 expression. We found that staurosporine (sts), a potent protein kinase C (PKC) inhibitor, synergistically potentiated the deoxycholate‐mediated induction of COX‐2 expression. Sts did not increase the stabilization of COX‐2 mRNA. The sts‐ and deoxycholate‐mediated synergistic induction of COX‐2 expression was suppressed by a membrane‐permeable Ca2+ chelator, a phosphoinositide 3‐kinase inhibitor, a nuclear factor‐κB pathway inhibitor, and inhibitors of canonical and stress‐inducible mitogen‐activated protein kinase pathways. Inhibition was also observed using PKC inhibitors, suggesting the involvement of certain PKC isozymes (η, θ, ι, ζ, or μ). Our results indicate that sts exerts its potentiating effects via the phosphorylation of p38. However, the effects of anisomycin did not mimic those of sts, indicating that although p38 activation is required, it does not enhance deoxycholate‐induced COX‐2 expression. We conclude that staurosporine synergistically enhances deoxycholate‐induced COX‐2 expression in RCM‐1 colon cancer cells.

Regulation of COX-2 expression by miR-146a in lung cancer cells.

Prostaglandins are a class of molecules that mediate cellular inflammatory responses and control cell growth. The oxidative conversion of arachidonic acid to prostaglandin H2 is carried out by two isozymes of cyclooxygenase, COX-1 and COX-2. COX-1 is constitutively expressed, while COX-2 can be transiently induced by external stimuli, such as pro-inflammatory cytokines. Interestingly, COX-2 is overexpressed in numerous cancers, including lung cancer. MicroRNAs (miRNAs) are small RNA molecules that function to regulate gene expression. Previous studies have implicated an important role for miRNAs in human cancer. We demonstrate here that miR-146a expression levels are significantly lower in lung cancer cells as compared with normal lung cells. Conversely, lung cancer cells have higher levels of COX-2 protein and mRNA expression. Introduction of miR-146a can specifically ablate COX-2 protein and the biological activity of COX-2 as measured by prostaglandin production. The regulation of COX-2 by miR-146a is mediated through a single miRNA-binding site present in the 3' UTR. Therefore, we propose that decreased miR-146a expression contributes to the up-regulation and overexpression of COX-2 in lung cancer cells. Since potential miRNA-mediated regulation is a functional consequence of alternative polyadenylation site choice, understanding the molecular mechanisms that regulate COX-2 mRNA alternative polyadenylation and miRNA targeting will give us key insights into how COX-2 expression is involved in the development of a metastatic condition.

Nonsteroidal Anti-Inflammatory Drugs and the Heart

Aspirin has been on the market for 115 years. Beginning with the marketing of indomethacin for the treatment of rheumatoid arthritis in 1963, at least 20 other nonsteroidal anti-inflammatory drugs (NSAIDs) with aspirin-like actions have been developed over the past 50 years,1 culminating with the introduction of a new class of selective inhibitors of cyclooxygenase (COX)-2, the coxibs, approximately 15 years ago.2 The NSAIDs represent the single most crowded family of drugs sharing the same therapeutic activities and mechanism of action, perhaps reflecting the unmet therapeutic need in the area of pain management and the large interindividual variability in response to these agents. NSAIDs provide symptomatic relief of pain and inflammation associated with a variety of human disorders, including the rheumatic diseases. Their shared therapeutic actions (ie, analgesic, anti-inflammatory, and antipyretic) are usually accompanied by mechanism-based adverse effects that can, at least in part, be attenuated as a function of individual pharmacokinetic or pharmacodynamic properties.1 Nuances in the tolerability of different NSAIDs had been described in the precoxib era on the basis of clinical trials of a few hundred patients treated for up to a few months with soft end points. More recently, however, important differences in safety have been demonstrated in head-to-head randomized comparisons of individual coxibs and 1 or more traditional NSAIDs that involved tens of thousands of patients treated for up to a few years with hard end points. Even more significantly, the interpretation of the effects of NSAIDs has been greatly enhanced by the availability, for the first time, of large, placebo-controlled trials that aimed to assess the potential for chemoprevention of colorectal cancer by rofecoxib or celecoxib. As a result of these developments, the whole field of NSAIDs has been illuminated during the past 15 years. Although epidemiological studies had previously associated …