COX-2 Inhibitors and Cardiovascular Risk

Vasoconstrictor prostanoids

In cardiovascular diseases and during aging, endothelial dysfunction is due in part to the release of endothelium-derived contracting factors that counteract the vasodilator effect of the nitric oxide. Endothelium-dependent contractions involve the activation of endothelial cyclooxygenases and the release of various prostanoids, which activate thromboxane prostanoid (TP) receptors of the underlying vascular smooth muscle. The stimulation of TP receptors elicits not only the contraction and the proliferation of vascular smooth muscle cells but also diverse physiological/pathophysiological reactions, including platelet aggregation and activation of endothelial inflammatory responses. TP receptor antagonists curtail endothelial dysfunction in diseases such as hypertension and diabetes, are potent antithrombotic agents, and prevent vascular inflammation.

Rofecoxib, but not celecoxib, increases the risk of thromboembolic cardiovascular events in young adults-a nationwide registry-based study

PURPOSE

To examine the risk of thromboembolic cardiovascular events in users of coxibs and NSAIDs in a nationwide cohort.

METHODS

Data were synchronised from three nationwide databases, the Icelandic Medicines Registry (IMR), The Icelandic National Patient Registry (INPR) and the Registry for Causes of Death at Statistics Iceland (RCD), for prescriptions for NSAIDs or coxibs with respect to hospitalisation for unstable angina pectoris, myocardial infarction and cerebral infarction over a 3-year period. The Cox proportional hazards model and Poisson regression were used to analyse the data.

RESULTS

A total of 108,700 individuals received prescriptions for NSAIDs or coxibs (ATC code M01A), of whom 78,539 received one drug only (163,406 person-years). Among those receiving only one drug 426 individuals were discharged from hospital with endpoint diagnoses. In comparison to diclofenac, the incidence ratios, adjusted for age and gender, were significantly higher for cerebral infarction (2.13; 95% CI 1.54-2.97; P < 0.001), for myocardial infarction (1.77; 95% CI 1.34-2.32; P < 0.001) and for unstable angina pectoris (1.52; 95% CI 1.01-2.30; P = 0.047) for patients who used rofecoxib. For naproxen users, the incidence ratio was 1.46 for myocardial infarction (95% CI 1.03-2.07; P = 0.03), but was reduced in ibuprofen users (0.63; 95% CI 0.40-1.00; P = 0.05). The youngest users of rofecoxib (< or =39 years) had the highest hazard ratio (HR) for cardiovascular events (8.34; P < 0.001), while those > or =60 years had a lower but still significantly elevated HR (1.35; P = 0.001).

CONCLUSION

This Icelandic nationwide registry-based study amounting to 163,406 patient-years showed increased risk of cardiovascular events, i.e. cerebral infarction, myocardial infarction and unstable angina pectoris, among rofecoxib and naproxen users in comparison to diclofenac users. The added risk was most pronounced in young adults using rofecoxib.

Increased prevalence of metabolic syndrome in individuals with osteoarthritis: an analysis of NHANES III data

BACKGROUND

Osteoarthritis (OA) and cardiovascular disease (CVD) share age and obesity as risk factors, but may also be linked by pathogenic mechanisms involving metabolic abnormalities and systemic inflammation. This study compared the prevalence of OA and metabolic syndrome (MetS) in subjects with OA versus the general population without OA to determine whether having OA predicts increased cardiovascular risk.

METHODS

National Health and Nutrition Examination Survey III data were used as a representative sample of the general US population. Subjects included adults aged > or = 18 years with records of history, physical, radiographic, and laboratory data adequate to assess for diagnoses of MetS and OA. Logistic regression was used to examine the association between MetS and population-weighted variables.

RESULTS

The general population sample included 7714 subjects (weighted value representing 174.9 million population), of whom 975 subjects had OA (weighted value 17.5 million) and 6739 did not (weighted value 157.4 million). Metabolic syndrome was prevalent in 59% of the OA population and 23% of the population without OA. Each of the 5 cardiovascular risk factors that comprise MetS was more prevalent in the OA population versus the population without OA: hypertension (75% vs 38%), abdominal obesity (63% vs 38%), hyperglycemia (30% vs 13%), elevated triglycerides (47% vs 32%), and low high-density lipoprotein cholesterol (44% vs 38%). Metabolic syndrome was more prevalent in subjects with OA regardless of sex or race. The association between OA and MetS was greater in younger subjects and diminished with increasing age. Having OA at age 43.8 years (mean age of the general population) was associated with a 5.26-fold (SE = 1.58, P < 0.001) increased risk of MetS. This association remained strong when obesity was controlled for in additional regression models.

CONCLUSIONS

Osteoarthritis is associated with an increased prevalence of MetS, particularly in younger individuals. Global cardiovascular risk should be assessed in individuals aged < or = 65 years with OA, and should be considered when prescribing analgesics for OA patients.

Protocols to assess the gastrointestinal side effects resulting from inhibition of cyclo-oxygenase isoforms

A prevalent unwanted action of cyclo-oxygenase (COX) inhibitors, as exemplified by the non-steroidal anti-inflammatory drugs (NSAIDs), is their potential to produce gastrointestinal side effects in clinical use. The injury provoked by such agents includes rapid superficial disruption to the surface layer of the gastric mucosa, the production of acute gastric erosions in the corpus region and the formation of ulcers in the antral region of the stomach. The small intestine is also adversely affected, with a developing enteropathy over a more protracted period that causes lesions and inflammation in the gut. From experimental work, the interactive mechanisms of such damage in the stomach differ distinctly from those that underlie the intestinal injury, yet the damage in both regions involves the inhibition of both COX-1 and COX-2 isoforms. This chapter outlines the in vivo methods that can be used to identify the potential for novel NSAIDs and selective COX-inhibitors to produce acute gastric corpus lesions and more-chronic antral ulcers in the rat, as well as causing small intestinal enteropathy. Such methods can also be utilized to evaluate the ability of novel agents to prevent the gastrointestinal injury provoked by NSAIDs or COX-inhibitors.

Epidermal growth factor-induced cyclooxygenase-2 expression in oral squamous cell carcinoma cell lines is mediated through extracellular signal-regulated kinase 1/2 and p38 but is Src and nuclear factor-kappa B independent

The intracellular signalling cascade(s) mediating epidermal growth factor (EGF)-induced cyclooxygenase-2 (COX-2) expression is poorly defined in oral carcinomas. Investigation of two different oral squamous cell carcinoma (OSCC) cell lines with high EGF-induced COX-2 expression revealed, however, that this expression was dependent on two mitogen-activated protein kinase (MAPK) pathways [extracellular signal-regulated kinase 1/2 (ERK1/2) and p38] because combined inhibition of these pathways was needed to abolish EGF-induced COX-2 expression. Surprisingly, inhibition of phosphoinositide-3 kinase (PI3K) increased EGF-induced COX-2 expression in the basaloid OSCC cell line (C12), suggesting a PI3K-controlled, inhibitory COX-2-regulating pathway. Neither the transcription factor nuclear factor-kappaB (NF-kappaB), nor Src, was involved in EGF-induced COX-2 expression. The results suggest that EGF-induced COX-2 expression is regulated by several pathways, and emphasizes that individual tumors use different strategies for intracellular signalling.

New drugs for migraine

After the triptans, a calcitonin gene-related peptide blocker (telcagepant) is the first acute medicine that has been developed primarily for treatment of acute migraine. Otherwise, the new drugs have been developed first for other purposes, like anticonvulsants, antihypertensives and antidepressants used for migraine prophylaxis. For acute attacks, a new way to administer a traditional drug like dihydroergotamine is under way, and documentation of efficacy in migraine has been gained for some commonly used painkillers and anti-inflammatory drugs, and for some herbal extracts. Based on insights into the basic pathophysiological mechanisms of the disorder, some drugs have been developed which seem promising in early phase II studies (NOS inhibitors and 5HT1F-receptor agonists). In the future, development and enhancements of existing medicines must be accompanied by increased efforts to develop truly new migraine drugs based on knowledge of the pathophysiology if one wishes to reduce substantially the great burden migraine poses on patients and society.

Absence of myeloid COX-2 attenuates acute inflammation but does not influence development of atherosclerosis in apolipoprotein E null mice

OBJECTIVE

The role of myeloid cell cyclooxygenase-2 (COX-2) in the progression of atherosclerosis has not been clearly defined.

METHODS AND RESULTS

We investigated the role of COX-2 expressed in the myeloid lineage in the development of atherosclerosis using a myeloid-specific COX-2(-/-) (COX-2(-M/-M)) mouse on a hyperlipidemic apolipoprotein (apo) E(-/-) background (COX-2(-M/-M)/apoE(-/-)). Myeloid COX-2 depletion resulted in significant attenuation of acute inflammation corresponding with decreased PGE(2) levels in an air pouch model. COX-2 depletion in myeloid cells did not influence development of atherosclerosis in COX-2(-M/-M)/apoE(-/-) when compared to apoE(-/-) littermates fed either chow or western diets. The unanticipated lack of contribution of myeloid COX-2 to the development atherosclerosis is not attributable to altered maintenance, differentiation, or mobilization of myeloid and lymphoid populations. Moreover, myeloid COX-2 depletion resulted in unaltered serum prostanoid levels and cellular composition of atherosclerotic lesions of COX-2(-M/-M)/apoE(-/-) mice.

CONCLUSIONS

Our results suggest that COX-2 expression in myeloid cells, including macrophages, does not influence the development of atherosclerosis in mice.

DOCK2 is a microglial specific regulator of central nervous system innate immunity found in normal and Alzheimer's disease brain

Neuroinflammation is a hallmark of several neurodegenerative diseases, including Alzheimer's disease (AD). Strong epidemiological and experimental evidence supports the use of nonsteroidal anti-inflammatory drugs to reduce AD risk. However, poor outcome in clinical trials and toxicity in a prevention trial have shifted focus away from these cyclooxygenase (COX) inhibitors to seek additional therapeutic targets in the prostaglandin pathway. Previously, the prostaglandin E2 receptor, EP2, was shown to regulate neuroinflammation and reduce Abeta plaque burden in transgenic mice. Unfortunately, widespread EP2 distribution and a direct effect on COX2 induction make EP2 a less desirable target. In this study, we link dedicator of cytokinesis 2 (DOCK2) to the prostaglandin pathway in the brain. Additionally, we show that DOCK2 regulates microglial innate immunity independent of COX2 induction and that DOCK2+ microglia are associated with human AD pathology. Together, these results suggest DOCK2 as a COX2 expression-independent therapeutic target for neurodegenerative diseases such as AD.

Evidence for an ionic intermediate in the transformation of fatty acid hydroperoxide by a catalase-related allene oxide synthase from the Cyanobacterium Acaryochloris marina

Allene oxides are reactive epoxides biosynthesized from fatty acid hydroperoxides by specialized cytochrome P450s or by catalase-related hemoproteins. Here we cloned, expressed, and characterized a gene encoding a lipoxygenase-catalase/peroxidase fusion protein from Acaryochloris marina. We identified novel allene oxide synthase (AOS) activity and a by-product that provides evidence of the reaction mechanism. The fatty acids 18.4omega3 and 18.3omega3 are oxygenated to the 12R-hydroperoxide by the lipoxygenase domain and converted to the corresponding 12R,13-epoxy allene oxide by the catalase-related domain. Linoleic acid is oxygenated to its 9R-hydroperoxide and then, surprisingly, converted approximately 70% to an epoxyalcohol identified spectroscopically and by chemical synthesis as 9R,10S-epoxy-13S-hydroxyoctadeca-11E-enoic acid and only approximately 30% to the 9R,10-epoxy allene oxide. Experiments using oxygen-18-labeled 9R-hydroperoxide substrate and enzyme incubations conducted in H2(18)O indicated that approximately 72% of the oxygen in the epoxyalcohol 13S-hydroxyl arises from water, a finding that points to an ionic intermediate (epoxy allylic carbocation) during catalysis. AOS and epoxyalcohol synthase activities are mechanistically related, with a reacting intermediate undergoing a net hydrogen abstraction or hydroxylation, respectively. The existence of epoxy allylic carbocations in fatty acid transformations is widely implicated although for AOS reactions, without direct experimental support. Our findings place together in strong association the reactions of allene oxide synthesis and an ionic reaction intermediate in the AOS-catalyzed transformation.

Postmarketing surveillance of serious adverse events associated with the use of rofecoxib from 1999-2002

OBJECTIVE

The authors performed a postmarketing database analysis to evaluate the incidence of cardiovascular and other serious adverse events (SAEs) reported to the US Food and Drug Administration's Adverse Event Reporting System (AERS) involving the use of rofecoxib.

RESEARCH DESIGN AND METHODS

The authors studied all adverse events involving rofecoxib reported to the AERS from inception of the drug until 2002. An emphasis was placed on cardiovascular and other SAEs of interest categorized using the high level group terms hemorrhage, edema, thrombosis, embolism, and death.

RESULTS

There were 31,024 reports of SAEs associated with the use of rofecoxib, which was considered primary suspect in 97.8% of these reports. There were 3915, 3677, 1653, 1917, and 233 reports of hemorrhage, edema, death, thrombosis, and embolism, respectively. Relative to the overall population in this dataset, reports of hemorrhage, death, thrombosis, and embolism consisted of a greater proportion of males. The mean age for patients that reported hemorrhage, death, and thrombosis was older, whereas the mean age for embolism and edema was younger than the overall population in this dataset. Aspirin was the most commonly reported concomitant medication (7.4% of reports) followed by acetaminophen (5.4%). Reports containing concomitant use of anti-coagulants, Cox-1, and nonselective inhibitors (each p < 0.001) but not Cox-2 inhibitors were associated with increased age while only anti-coagulants and Cox-1 inhibitors (each p < 0.001) were associated with more males. Reports containing concomitant use of an anti-coagulant or an NSAID accounted for a disproportionate incidence of hemorrhage, edema, embolism, and death. Most notably, the odds of a hemorrhagic event for those reporting concomitant use of an anti-coagulant, Cox-1, non-selective, or Cox-2 inhibitor was 3.05 (p < 0.001), 3.07 (p < 0.001), 2.07 (p < 0.001), and 1.18 (p < 0.001), respectively. Some weaknesses of this type of analysis are the retrospective nature of such a study, the inability to find causality, and that the data can contains multiple reports from any one individual.

CONCLUSIONS

It can be postulated that in addition to the risk of heart attack and stroke, rofecoxib users were at increased risk of hemorrhage, in addition to other thrombotic and embolic adverse events, which was exacerbated in those taking blood thinners or NSAIDs.

Renal and cardiovascular characterization of COX-2 knockdown mice

Selective cyclooxygenase-2 (COX-2) inhibitors (coxibs) increase the incidence of cardiovascular and cerebrovascular events. Complete disruption of the murine gene encoding COX-2 ( Ptgs2) leads to renal developmental problems, as well as female reproductive anomalies and patent ductus arteriosus of variable penetrance in newborns, thus rendering this genetic approach difficult to compare with coxib administration. Here, we created hypomorphic Ptgs2 (COX-2Neo/Neo) mice in which COX-2 expression is suppressed to an extent similar to that achieved with coxibs, but not eliminated, in an attempt to circumvent these difficulties. In LPS-challenged macrophages and cytokine-stimulated endothelial cells obtained from COX-2Neo/Neo mice, COX-2 expression was reduced 70–90%, and these mice developed a mild renal phenotype compared with COX-2 mice possessing an active site mutation (COX-2Y385F/Y385F), with minimal signs of renal dysfunction as measured by FITC-inulin clearance and blood urea nitrogen. These COX-2 knockdown mice displayed an increased propensity for thrombogenesis compared with their wild-type (COX-2+/+) littermates observed by intravital microscopy in cremaster muscle arterioles upon ferric chloride challenge. Measurement of urinary prostanoid metabolites indicated that COX-2Neo/Neo mice produced 50% less prostacyclin but similar levels of PGE2 and thromboxane compared with COX-2+/+ mice in the absence of any blood pressure and ex vivo platelet aggregation abnormalities. COX-2Neo/Neo mice, therefore, provide a genetic surrogate of coxib therapy with disrupted prostacyclin biosynthesis that predisposes to induced arterial thrombosis.

Emerging roles of PGE2 receptors in models of neurological disease

This review presents an overview of the emerging field of prostaglandin signaling in neurological diseases, focusing on PGE(2) signaling through its four E-prostanoid (EP) receptors. A large number of studies have demonstrated a neurotoxic function of the inducible cyclooxygenase COX-2 in a broad spectrum of neurological disease models in the central nervous system (CNS), from models of cerebral ischemia to models of neurodegeneration and inflammation. Since COX-1 and COX-2 catalyze the first committed step in prostaglandin synthesis, an effort is underway to identify the downstream prostaglandin signaling pathways that mediate the toxic effect of COX-2. Recent epidemiologic studies demonstrate that chronic COX-2 inhibition can produce adverse cerebrovascular and cardiovascular effects, indicating that some prostaglandin signaling pathways are beneficial. Consistent with this concept, recent studies demonstrate that in the CNS, specific prostaglandin receptor signaling pathways mediate toxic effects in brain but a larger number appear to mediate paradoxically protective effects. Further complexity is emerging, as exemplified by the PGE(2) EP2 receptor, where cerebroprotective or toxic effects of a particular prostaglandin signaling pathway can differ depending on the context of cerebral injury, for example, in excitotoxicity/hypoxia paradigms versus inflammatory-mediated secondary neurotoxicity. The divergent effects of prostaglandin receptor signaling will likely depend on distinct patterns and dynamics of receptor expression in neurons, endothelial cells, and glia and the specific ways in which these cell types participate in particular models of neurological injury.

Cyclooxygenase inhibitors repress vascular hyaluronan-synthesis in murine atherosclerosis and neointimal thickening

Hyaluronan (HA) is a key molecule of the extracellular matrix that is thought to be critically involved in both atherosclerosis and restenosis. Recently, it has been demonstrated that the cyclooxygenase (COX) products, prostacyclin and prostaglandin E(2), induce HA synthesis in vitro by transcriptional up-regulation of HA-synthase 2 (HAS2) and HAS1. The relative roles in atherosclerotic and restenotic artery disease of tissue specifically expressed COX-1 and COX-2 are still under debate. Thus, the present study aimed to investigate the effect of COX isoform inhibition on HA-accumulation and regulation of HAS isoform expression in two models of pathologic artery remodelling in vivo. Firstly, ApoE-deficient mice were treated with a prototypic isoform non-selective inhibitor, indomethacin or with a prototypic COX-2 selective inhibitor, rofecoxib, for 8 weeks. Aortic HAS mRNA expression and HA-accumulation in atherosclerotic aortic root lesions were analyzed. Secondly, neointimal hyperplasia was induced by carotid artery ligation in ApoE-deficient mice on a high fat diet and the effects of the COX inhibitors were determined after 4 weeks of treatment. Intimal HA-accumulation was markedly reduced in both models by indomethacin and rofecoxib. This coincided with a strong inhibition of HAS1 mRNA expression in both models and with decreased HAS2 mRNA in the aorta of ApoE-deficient mice. HAS3 was not affected. The repression of HA-accumulation by both COX-2 selective and non-selective COX inhibition implicates COX-2 in the regulation of HA synthesis via stimulation of HAS1 and HAS2 expression in vivo. Modulation of vascular HA-accumulation might play a role in chronic effects of COX inhibitors on the progression of atherosclerosis.

Osteoarthritis: An Update on Data Currently Reshaping Practice

Osteoarthritis is common, has considerable health consequences, and will affect increasing numbers of persons in coming years. Nonpharmacological interventions are of paramount importance in achieving adequate symptom control. Acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) play a pivotal role in osteoarthritis pharmacotherapy. Acetaminophen, due to its safety profile, should be adequately trialed before resorting to NSAIDs. NSAIDs and celecoxib, a selective inhibitor of cyclooxygenase-2, should be selected thoughtfully so as to balance the likelihood of treatment success with gastrointestinal bleeding and cardiovascular events. Celecoxib may be used when the risk for gastrointestinal bleeding is high and the risk of cardiovascular events low. Otherwise, NSAIDs, usually naproxen, should be paired with a gastroprotective agent. Topical NSAIDs, including a recently approved diclofenac patch and gel, may also be useful when systemic exposure is undesirable. The role of glucosamine and chondroitin is controversial and the data conflicting. Other modalities, such as tramadol, opioids, and viscosupplementation should be tailored to the patient and clinical situation. Appropriate deployment of agents in the osteoarthritis armamentarium can maximize efficacy and safety thereby improving the disease burden for patients.

Eicosanoid signalling pathways in the heart

Myocardial phospholipids serve as primary reservoirs of arachidonic acid (AA), which is liberated through the rate-determining hydrolytic action of cardiac phospholipases A2 (PLA2s). A predominant PLA2 in myocardium is calcium-independent phospholipase A2beta (iPLA2beta), which, through its calmodulin (CaM) and ATP-binding domains, is regulated by alterations in local cellular Ca2+ concentrations and cardiac bioenergetic status, respectively. Importantly, iPLA2beta has been demonstrated to be activated by ischaemia through elevation of the concentration of myocardial fatty acyl-CoA, which abrogates Ca2+/CaM-mediated inhibition of iPLA2beta. AA released by PLA2-catalysed hydrolysis of phospholipids serves as a precursor for eicosanoids generated by pathways dependent on cyclooxygenases (COX), lipoxygenases (LOX), and cytochromes P450 (CYP). Eicosanoids initiate and propagate diverse signalling cascades, primarily through their interaction with cellular receptors and ion channels. However, during pathologic states such as ischaemia or congestive heart failure, eicosanoids contribute to multiple maladaptive changes including inflammation, alterations of cellular growth programmes, and activation of multiple transcriptional events leading to the deleterious sequelae of these pathologic states. This review summarizes the central roles of myocardial PLA(2)s in eicosanoid signalling in the heart, the major COX, LOX, and CYP pathways of eicosanoid generation in the myocardium, and the effects of important eicosanoids on receptor-, ion channel-, and transcription-mediated processes that facilitate cardiac hypertrophy, mediate ischaemic preconditioning, and precipitate arrhythmogenesis in response to pathologic stimuli.

Pharmacological targeting of the integrated protein kinase B, phosphatase and tensin homolog deleted on chromosome 10, and transforming growth factor-beta pathways in prostate cancer

Prostate cancer is a highly heterogenous disease in which a patient-tailored care program is much desired. Central to this goal is the development of novel targeted pharmacological interventions. To develop these treatment strategies, an understanding of the integration of cellular pathways involved in both tumorigenesis and tumor suppression is crucial. Of further interest are the events elicited by drug treatments that exploit the underlying molecular pathology in cancer. This review briefly describes the evidence that suggests integration of three established pathways: the tumorigenic phosphoinositide 3-kinase/protein kinase B (AKT) pathway, the tumor suppressive phosphatase and tensin homolog deleted on chromosome 10 pathway, and the tumor suppressive transforming growth factor-beta pathway. More importantly, we discuss novel pharmaceutical agents that target key points of integration in these three pathways. These new therapeutic strategies include the use of agents that target iron to inhibit proliferation via multiple mechanisms and suppression of AKT by cytosolic phospholipase A(2)-alpha inhibitors.

Rosmarinic acid antagonizes activator protein-1-dependent activation of cyclooxygenase-2 expression in human cancer and nonmalignant cell lines

One mechanism through which bioactive food components may exert anticancer effects is by reducing the expression of the proinflammatory gene cyclooxygenase-2 (COX-2), which has been regarded as a risk factor in tumor development. Rosmarinic acid (RA) is a phenolic derivative of caffeic acid present in rosemary (Rosmarinus officinalis). Previous research documented that RA may exert antiinflammatory effects. However, the mechanisms of action of RA on COX-2 expression have not been investigated. Here, we report that in colon cancer HT-29 cells, RA (5, 10, and 20 micromol/L) reduced the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced COX-2 promoter activity (P < 0.05) and protein levels (P < 0.05). In addition, the cotreatment with RA reduced (5 micromol/L, P < 0.05; 10 and 20 micromol/L, P < 0.01) TPA-induced transcription from a control activator protein-1 (AP-1) promoter-luciferase construct and repressed binding of the AP-1 factors c-Jun (10 micromol/L; P < 0.01) and c-Fos (10 micromol/L; P < 0.05) to COX-2 promoter oligonucleotides harboring a cAMP-response element (CRE). The anti-AP1 effects of RA were also examined in a nonmalignant breast epithelial cell line (MCF10A) in which RA antagonized the stimulatory effects of TPA on COX-2 protein expression (5 micromol/L, P < 0.05; 10 and 20 micromol/L, P < 0.01), the recruitment of c-Jun and c-Fos (10 micromol/L; P < 0.01) to the COX-2/CRE oligonucleotides, and activation of the extracellular signal-regulated protein kinase-1/2 (ERK1/2) (10 micromol/L; P < 0.01), a member of the mitogen-activated protein kinase pathway. Additionally, RA antagonized ERK1/2 activation in colon HT-29 and breast MCF-7 cancer cells (10 micromol/L; P < 0.01). Thus, we propose that RA may be an effective preventative agent against COX-2 activation by AP-1-inducing agents in both cancer and nonmalignant mammary epithelial cells.

RNA viruses and the mitogenic Raf/MEK/ERK signal transduction cascade

The Raf/MEK/ERK signal transduction cascade belongs to the mitogen-activated protein kinase (MAPK) cascades. Raf/MEK/ERK signaling leads to stimulus-specific changes in gene expression, alterations in cell metabolism or induction of programmed cell death (apoptosis), and thus controls cell differentiation and proliferation. It is induced by extracellular agents, including pathogens such as RNA viruses. Many DNA viruses are known to induce cellular signaling via this pathway. As these pathogens partly use the DNA synthesis machinery for their replication, they aim to drive cells into a proliferative state. In contrast, the consequences of RNA virus-induced Raf/MEK/ERK signaling were less clear for a long time, but since the turn of the century the number of publications on this topic has rapidly increased. Research on this virus/host-interaction will broaden our understanding of its relevance in viral replication. This important control center of cellular responses is differently employed to support the replication of several important human pathogenic RNA viruses including influenza, Ebola, hepatitis C and SARS corona viruses.

Celecoxib analogs that lack COX-2 inhibitory function: preclinical development of novel anticancer drugs

Celecoxib is an NSAID that was developed as a selective inhibitor of COX-2 and approved by the FDA for the treatment of various forms of arthritis and the management of acute or chronic pain. In addition, it was more recently approved as an oral adjunct to prevent colon cancer development in patients with familial adenomatous polyposis and is presently being investigated for its chemotherapeutic potential in the therapy of advanced cancers. However, in laboratory studies it was discovered that celecoxib was able to suppress tumor growth in the absence of any apparent involvement of COX-2, and additional pharmacologic activities associated with this drug were found. Intriguingly, the two pharmacologic effects, inhibition of COX-2 and suppression of tumor growth, were found to reside in different structural aspects of the celecoxib molecule and, therefore, could be separated. This dualism enabled the synthesis of close structural analogs of celecoxib that exhibited increased antitumor potency in the absence of COX-2 inhibition. In theory, such compounds should be superior to celecoxib for antitumor purposes because they might reduce gastrointestinal and cardiovascular risks and the life-threatening side effects that appear during the long-term use of selective COX-2 inhibitors. In this review, the authors present the status of preclinical development of anticancer analogs of celecoxib that are COX-2 inactive, with an emphasis on 2,5-dimethyl-celecoxib (DMC) and OSU-03012.

Inflammatory angiogenesis in atherogenesis--a double-edged sword

The adventitia and the outer layers of media of an atherosclerosis-prone arterial wall are vascularized by vasa vasorum. Upon growth of an atherosclerotic lesion in the intima, neovascular sprouts originating from the adventitial vasa vasorum enter the lesion, the local proangiogenic micromilieu in the lesion being created by intramural hypoxia, by increased intramural oxidant stress, and by inflammatory cell infiltration (macrophages, T cells and mast cells). The angiogenic factors present in the lesions include various growth factors, chemokines, cytokines, proteinases, and several other factors possessing direct or indirect angiogenic activities, while the current list of antiangiogenic factors is smaller. An imbalance between endogenous inducers and inhibitors of angiogenesis, with a predominance of the former ones, is essential for the development of neovessels during the progression of the lesion. By providing oxygen and nutrients to the cells of atherosclerotic lesions, neovascularization initially tends to prevent cellular death and so contributes to plaque growth and stabilization. However, the inflammatory cells may induce rupture of the fragile neovessels, and so cause intraplaque hemorrhage and ensuing plaque destabilization. Pharmacological inhibition of angiogenesis in atherosclerotic plaques with ensuing inhibition of lesion progression has been achieved in animal models, but clinical studies aiming at regulation of angiogenesis in the atherosclerotic arterial wall can be designed only after we have reached a firm conclusion about the role of angiogenesis at various stages of lesion development--good or bad.