Acetylsalicylic Acid and its Potential for Chemoprevention of Colorectal Carcinoma.

BACKGROUND: Non-steroidal anti-inflammatory drugs (NSAID) represent a group of medicaments inhibiting cyclooxygenase (COX) enzyme, and, in parallel, these drugs show also analgesic, antipyretic and anti-inflammatory effects. Due to their efficiency, good tolerance and easy availability, they belong to the worlds most used drugs. For decades, evidence of their anti-tumor activity has been growing, with the largest amount of published work being related to colorectal cancer (CRC). Based on both in vitro and in vivo experiments and data obtained from epidemiological and clinical studies, potential application of NSAID as chemo-preventive treatment for CRC patients is recently discussed in order to prevent development or recurrence of precanceroses and tumors. Promising treatment for such indication would be acetylsalicylic acid (ASA), which is the oldest, more than 100 years used member of the NSAID family. Nonselective irreversible COX inhibition is an important but probably not solely mechanism of its anticancer activity. Notably, wider use of ASA in chemoprevention is also prevented due to particular concerns about gastrointestinal and renal toxicity caused especially by its long-term use. AIMS: This review introduces the role of COX in tumor biology of CRC and highlights the results of the most interesting experiments illustrating the anti-tumor effect of ASA. Moreover, our work evaluates the most important published clinical analyzes of the ASA chemopreventive effect on CRC and discusses the current state. Key words: non-steroidal anti-inflammatory agents - acetylsalicylic acid - colorectal carcinoma - cyclooxygenase - chemoprevention This work was supported by the projects MEYS - NPS I - LO1413, MH CZ - DRO (MMCI, 00209805) and by Czech Science Foundation project no. 16-14829S. The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers. Accepted: 10. 9. 2017.

Functional characterization of the oxidative capacity of mitochondria and glycolytic assessment in benthic aquatic organisms.

The metabolism of benthic aquatic invertebrates, populating transitional water ecosystems, is influenced by both physiological and environmental factors, thus involving an adjustment of physiological processes which has a metabolic cost. In order to discover changes in metabolic pathways in response to specific factors, it's firstly necessary characterizing the principal cellular metabolic activities of the small benthic aquatic organisms. We approach here the bioenergetic state issue of two benthic organisms, i.e. Lekanesphaera monodi and Gammarus insensibilis, evidencing that no apparent and statistically significative differences between them in aerobic as well in glycolytic capacities are detected, except for COX activity.

Interaction of nonsteroidal anti-inflammatory drugs with membranes: in vitro assessment and relevance for their biological actions.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most commonly used drugs in the world due to their anti-inflammatory, analgesic and antipyretic properties. Nevertheless, the consumption of these drugs is still associated with the occurrence of a wide spectrum of adverse effects. Regarding the major role of membranes in cellular events, the hypothesis that the biological actions of NSAIDs may be related to their effect at the membrane level has triggered the in vitro assessment of NSAIDs-membrane interactions. The use of membrane mimetic models, cell cultures, a wide range of experimental techniques and molecular dynamics simulations has been providing significant information about drugs partition and location within membranes and also about their effect on diverse membrane properties. These studies have indeed been providing evidences that the effect of NSAIDs at membrane level may be an additional mechanism of action and toxicity of NSAIDs. In fact, the pharmacokinetic properties of NSAIDs are closely related to the ability of these drugs to interact and overcome biological membranes. Moreover, the therapeutic actions of NSAIDs may also result from the indirect inhibition of cyclooxygenase due to the disturbing effect of NSAIDs on membrane properties. Furthermore, increasing evidences suggest that the disordering effects of these drugs on membranes may be in the basis of the NSAIDs-induced toxicity in diverse organ systems. Overall, the study of NSAIDs-membrane interactions has proved to be not only important for the better understanding of their pharmacological actions, but also for the rational development of new approaches to overcome NSAIDs adverse effects.

A novel ex vivo skin model for the assessment of the potential transcutaneous anti-inflammatory effect of topically applied Harpagophytum procumbens extract.

Using ex vivo skin as a model, this work tested the hypothesis that the major pharmacologically active components of topically applied Harpagophytum procumbens (H. procumbens) can elicit anti-inflammatory responses in deeper tissues post-transcutaneous delivery. Using Franz-type diffusion cells, ethanol extract of powdered H. procumbens tuber was dosed onto freshly excised porcine skin. After 24 h the receptor phase was recovered, analysed for the major glycosides of DC, then used directly to dose further freshly excised skin membranes. After 6h the skin was recovered and probed for the expression of the three major enzymes involved in the inflammatory factors: cyclooxygenase (COX-2) and its product prostaglandin E2 (PGE-2), lipoxygenase (5-LOX), and inducible nitric oxide (iNOS), using immunocytochemistry and Western blotting analyses. It was found that the receptor phase at 24 h contained (0.8, 25, 1.8, 3 x 10(-3)) micromol mL(-1) of harpagoside, harpagide, verbascoside, 8-O-p-coumaroyl-harpagide, respectively. When applied to skin, this solution effectively inhibited the expression of COX-2 and its product PGE-2. However, it did not have a significant effect on either 5-LOX or iNOS compared to control samples (PBS only). These data support the hypothesis that the transcutaneous delivery of H. procumbens can treat inflammation in deeper tissues such as in arthritis. Moreover, a novel ex vivo model has been described for assessing the potential anti-inflammatory activity of permeants delivered to deeper subcutaneous regions.

Noninvasive assessment of the role of cyclooxygenases in cardiovascular health: a detailed HPLC/MS/MS method.

A robust method for the routine quantitation of a selected group of urinary eicosanoid metabolites of interest to cardiovascular research in human and mouse is described and discussed. Included are the addition of stable isotope-labeled internal standards, solid phase extraction, and quantitation by liquid chromatography/tandem mass spectrometry using selected reaction monitoring (SRM) techniques.

Strategies for efficient lead structure discovery from natural products.

This investigation aims to evaluate strategies for an efficient selection of bioactive compounds from the multitude and biodiversity of the plant kingdom. Statistics prove natural products (NPs) as a source leading most consistently to successful development of new drugs. However, there are several reasons why the interest in finding bioactive NPs has generally declined at several major pharmaceutical companies. Their substantial argument is that the research in this field is time-consuming, highly complex and ineffective. A more rational and economic search for new lead structures from nature must therefore be a priority in order to overcome these problems. In this paper, different strategies are described to exploit the molecular diversity of bioactive secondary metabolites, namely classical pharmacognostic approaches and computational methods. The latter include various data mining tools, like virtual screening filtering experiments using pharmacophore models, docking studies, and neural networks, which help to establish a relationship between chemical structure and biological activity. The strengths and weaknesses of these methods will be shown in this review. Focusing on selected targets within the arachidonic acid cascade (phospholipase A(2), 5-lipoxygenase, cyclooxygenase-1 and -2), several studies of successful discoveries in the field of anti-inflammatory NPs were scrutinized for the applied strategies. Both the compilation of relevant published data and recent studies supported by our own research clearly demonstrate the benefits of the synergistic effect of a hybridization of these strategies for an effective drug discovery from natural ingredients.

Assessment of the antiplatelet effects of low to medium dose aspirin in the early and late phases after ischaemic stroke and TIA.

Vascular events commonly recur in stroke patients on aspirin, and may reflect incomplete inhibition of platelet function with aspirin therapy. The platelet function analyser (PFA-100) activates platelets by aspirating a blood sample at a moderately high shear rate through a capillary to a biologically active membrane with a central aperture. The membrane is coated with collagen, and either ADP (C-ADP) or epinephrine (C-EPI). The time taken for activated platelets to adhere, aggregate, and occlude the aperture is called the closure time. Previous studies have shown that aspirin prolongs the C-EPI closure time, without prolongation of the C-ADP closure time, in the majority of control subjects. We hypothesised that the PFA-100 would provide a sensitive assay for the detection of early and convalescent phase cerebrovascular disease (CVD) patients who had incomplete inhibition of platelet function with aspirin. We investigated potential cyclooxygenase-dependent and -independent mechanisms that might influence the responsiveness to aspirin using the PFA-100. Patients were studied during the early (< or = 4 weeks, n=57) and convalescent phases ((< or = 3 months, n=46) after ischaemic stroke or TIA. To investigate potential mechanisms that could contribute to aspirin responsiveness on the PFA-100, we measured von Willebrand factor antigen levels, and carried out platelet aggregometry experiments in platelet-rich plasma in response to sodium arachidonate (1 mM) and ADP (5 microM). Sixty percent of patients in the early phase and 43% of patients in the convalescent phase did not have prolonged C-EPI closure times on 75-300 mg of aspirin daily, and were defined as aspirin non-responders. Median C-ADP closure times were significantly shorter in aspirin non-responders than aspirin-responders in both the early and convalescent phases after symptom onset (P=0.008), suggesting platelet hyper-reactivity to collagen or ADP in the aspirin non-responder subgroup. There was a significant inverse relationship between plasma von Willebrand factor antigen levels and C-EPI closure times in both early and convalescent phase CVD patients (P=0.008). Mean von Willebrand factor antigen levels were significantly higher in aspirin non-responders than aspirin responsive patients in the early (P=0.001), but not convalescent phase (P=0.2) after stroke and TIA. None of the patients studied were defined as being aspirin-resistant using sodium arachidonate- or ADP-induced platelet aggregometry. A large proportion of ischaemic CVD patients have incomplete inhibition of platelet function with low to medium dose aspirin using the PFA-100. The results suggest that cyclooxygenase-independent mechanisms, including elevated von Willebrand factor antigen levels, play an important role in mediating aspirin non-responsiveness on the PFA-100.

Pre-clinical assessment of DRF 4367, a novel COX-2 inhibitor: evaluation of pharmacokinetics, absolute oral bioavailability and metabolism in mice and comparative inter-species in vitro metabolism.

The aim of this study was to characterize the pharmacokinetics and determine the absolute bioavailability and metabolism of DRF 4367, a novel COX-2 inhibitor, in mice. In addition, the in vitro metabolism of DRF 4367 was studied in mouse, rat, dog, monkey and human liver microsomes. Following oral administration, maximum concentrations of DRF 4367 were achieved after about 1 h. Upon intravenous (IV) administration, the concentration of DRF 4367 declined in a bi-exponential fashion with a terminal elimination half-life of 4.0 h. The elimination half-life was unchanged with route of administration. The volume of distribution and systemic clearance of DRF 4367 in mice were 0.80 l h(-1) kg(-1) and 0.14 l kg(-1), respectively, after IV administration. The absolute oral bioavailability of DRF 4367 was 44%. In all species of liver microsomes examined, the primary route of metabolism for DRF 4367 was demethylation of benzyl methoxy to form a hydroxy metabolite (M1). The formation of this metabolite was mediated by CYP2D6 and CYP2C19 enzymes. M1 was not found to possess COX-2 inhibitory activity. Chemical-inhibition studies showed that quinidine (selective for CYP2D6) and ticlopidine (selective for CYP2C19) inhibited the formation of the hydroxy metabolite of DRF 4367, whereas potent inhibitors selective for other forms of CYP did not inhibit this oxidative reaction. Upon oral or IV administration of DRF 4367 to mice, unchanged DRF 4367, M1, the O-glucuronide conjugate of M1 (M1-G) and the O-sulfate conjugate of M1 (M1-S) were identified in bile.

Medical and pharmacy expenditures after implementation of a cyclooxygenase-2 inhibitor prior authorization program.

STUDY OBJECTIVE: To evaluate the effects of a cyclooxygenase (COX)-2 inhibitor prior authorization (PA) program on direct medical and pharmacy costs. DESIGN: Prospective, pre- and postimplementation cohort study with reference group. SETTING: Large corporation in the Midwest. PATIENTS: Of 26,375 continuously enrolled members, 737 used a COX-2 inhibitor in the 3 months before January 1, 2003, when the PA program was implemented. MEASUREMENT AND MAIN RESULTS: The PA program limits coverage for a COX-2 inhibitor to members with a documented risk for a nonselective nonsteroidal antiinflammatory drug (NSAID)-induced gastrointestinal adverse event. All pharmacy and medical claims and costs were analyzed from the payer's perspective for a 15-month period. Separate pharmacy cost comparisons and medical cost comparisons were made between the 3-month quarter before PA program implementation and each follow-up quarter after PA program implementation. In the 3 months after PA program implementation, 620 (84.1%) of 737 members had no claims for a COX-2 inhibitor, and during this period their pharmacy and medical costs initially declined 40.0% (p < 0.001) and 18.7% (p < 0.001), respectively, and remained significantly lower. Among a subgroup of 156 members who tried to fill a COX-2 inhibitor prescription but were denied coverage, pharmacy and medical costs initially declined, 48.1% (p < 0.001) and 10.3% (p < 0.001), respectively, with pharmacy costs remaining significantly lower; however, overall medical expenditures increased, then returned to baseline. No change was noted in physician outpatient encounters, and two members had an emergency department visit for abdominal pain with no gastrointestinal ulcerations or bleeds during the 12-month follow-up. CONCLUSION: Among members denied coverage for a COX-2 inhibitor after implementation of a PA program, pharmacy costs declined without a medical cost increase associated with gastrointestinal diagnoses.

COX-2 selective inhibitors in the treatment of arthritis: a rheumatologist perspective.

COX-2 selective inhibitors were developed in order to provide similar efficacy to traditional nonselective nonsteroidal anti-inflammatory drugs (NSAIDs) but with improved upper gastrointestinal safety. This paper presents an overview of randomized clinical trials demonstrating the efficacy of COX-2 selective inhibitors for the treatment of patients with arthritis, particularly osteoarthritis and rheumatoid arthritis. In osteoarthritis and rheumatoid arthritis, COX-2 selective inhibitors have been shown to be more effective than placebo and similarly effective as standard doses of nonselective NSAIDs. There are currently few randomized clinical trials comparing the efficacy of the 2 first-generation COX-2 selective inhibitors, celecoxib and rofecoxib, in osteoarthritis. Of 4 head-to-head studies comparing the 2 agents, 3 indicated similar efficacy, while the other demonstrated superiority of rofecoxib at a dose of 25 mg qd compared with celecoxib at a dose of 200 mg qd. There are no clinical trials comparing the efficacy of different agents for treatment of patients with rheumatoid arthritis. Some studies have also demonstrated efficacy for COX-2 selective inhibitors in patients with ankylosing spondylitis and gout. In aggregate, these data show that COX-2 selective inhibitors provide effective relief of pain in patients with osteoarthritis and rheumatoid arthritis, with efficacy that is similar to traditional NSAIDs. Cost-effectiveness and cost-utility studies suggest, however, that their use should be limited to patients at high risk of serious upper gastrointestinal side effects, including complicated ulcers.

Assessment of cyclooxygenase-2 expression in canine hemangiosarcoma, histiocytic sarcoma, and mast cell tumor.

To determine whether cyclooxygenase-2 (COX-2) is expressed in canine hemangiosarcoma (HSA), histiocytic sarcoma (HS), and grade-II mast cell tumor (MCT), we performed immunohistochemistry using COX-2 antibodies in the aforementioned tumors. Twenty cases of each tumor type were selected initially from the Laboratory of Pathology archives of cases submitted through the Matthew J. Ryan Veterinary Hospital of the University of Pennsylvania. Immunohistochemistry was performed, using a polyclonal antiprostaglandin endoperoxide synthase immunoglobulin G COX-2 antibody. Sections from the kidneys of young dogs, in which the macula densa stains positive for COX-2, served as positive controls. Slides were reviewed by a single pathologist (M. H. Goldschmidt) and graded for COX-2 expression according to previously established scales. Descriptive data is given for each tumor type. COX-2 expression was identified in 0 of 19 HSA, 1 of 20 HS, and 1 of 17 grade-II MCT. Although COX-2 has been shown to be overexpressed in selected human sarcomas and hematopoeitic tumors, these results indicate that canine HSA, HS, and MCT do not express COX-2 in any appreciable fashion.

Consumption of the putative chemopreventive agent curcumin by cancer patients: assessment of curcumin levels in the colorectum and their pharmacodynamic consequences.

Curcumin, a constituent of the spice turmeric, has been shown to reduce the adenoma burden in rodent models of colorectal cancer accompanied by a reduction of levels of the oxidative DNA adduct 3-(2-deoxy-beta-di-erythro-pentafuranosyl)-pyr[1,2-alpha]-purin-10(3H)one (M(1)G) and of expression of the enzyme cyclooxygenase-2 (COX-2). We tested the hypothesis that pharmacologically active levels of curcumin can be achieved in the colorectum of humans as measured by effects on levels of M(1)G and COX-2 protein. Patients with colorectal cancer ingested curcumin capsules (3,600, 1,800, or 450 mg daily) for 7 days. Biopsy samples of normal and malignant colorectal tissue, respectively, were obtained at diagnosis and at 6 to 7 hours after the last dose of curcumin. Blood was taken 1 hour after the last dose of curcumin. Curcumin and its metabolites were detected and quantitated by high-performance liquid chromatography with detection by UV spectrophotometry or mass spectrometry. M(1)G levels and COX-2 protein expression were measured by immunoslot blot and Western blotting, respectively. The concentrations of curcumin in normal and malignant colorectal tissue of patients receiving 3,600 mg of curcumin were 12.7 +/- 5.7 and 7.7 +/- 1.8 nmol/g, respectively. Curcumin sulfate and curcumin glucuronide were identified in the tissue of these patients. Trace levels of curcumin were found in the peripheral circulation. M(1)G levels were 2.5-fold higher in malignant tissue as compared with normal tissue (P < 0.05 by ANOVA). Administration of curcumin (3,600 mg) decreased M(1)G levels from 4.8 +/- 2.9 adducts per 107 nucleotides in malignant colorectal tissue to 2.0 +/- 1.8 adducts per 107 nucleotides (P < 0.05 by ANOVA). COX-2 protein levels in malignant colorectal tissue were not affected by curcumin. The results suggest that a daily dose of 3.6 g curcumin achieves pharmacologically efficacious levels in the colorectum with negligible distribution of curcumin outside the gut.

Embryopathy in experimental diabetic gestation: assessment of PGE2 level, gene expression of cyclooxygenases and apoptosis.

The causes of, and predisposing conditions for, increased congenital anomalies in embryos of experimental diabetic gestation are not fully identified. In the present study, some possible factors involved in diabetes-induced embryopathy are explored. The concentration of PGE2, the gene expression of cyclooxygenases (COX-1 and COX-2) and level of apoptosis (measured by caspase-3 activity) are assessed during organogenesis in the embryos of streptozotocin-induced diabetic rats. The concentrations of PGE2 in the embryos of diabetic rats were lower than controls, with the lowest values in malformed embryos and their associated membranes (yolk sacs). The pattern of change in PGE2 was similar in the embryos of the control and diabetic groups, which showed a steady decline between days 9 and 11 of gestation. These changes in PGE2 were accompanied by a small decrease in COX-1 expression in all embryos and associated membranes during the same gestational period. Expression of COX-2, which was below normal in diabetic embryos, decreased between days 9 and 11 of gestation in all groups. In the membranes of non-malformed embryos, COX-2 expression peaked on day 10 of gestation. It was found that there was little or no detectable COX-2 expression in the membranes of malformed embryos on day 9 of gestation and although its expression was detectable on the following days it was much lower than in the other groups. Caspase-3 activity increased substantially between days 9 and 11 of gestation. Embryos from the experimentally diabetic group showed higher activity than did controls, with the largest increases in the malformed embryos. It would appear that COX-2 expression and PGE2 concentration (in both embryo and associated membranes) play a significant role in organ formation. The data presented here suggest that an unhealthy placenta may be instrumental in the development of malformed embryos.

Efficacy of oral rofecoxib versus intravenous ketoprofen as an adjuvant to PCA morphine after urologic surgery.

BACKGROUND: Adjunctive use of nonsteroidal anti-inflammatory drugs has become increasingly popular in the perioperative period because of their opioid-sparing effects. This randomized, controlled, double-dummy study was designed to evaluate the cost-effectiveness of using oral rofecoxib as an alternative to intravenous ketoprofen for pain management in patients undergoing urologic surgery. METHODS: Seventy patients were randomly assigned to receive either a placebo (Control) or rofecoxib 50 mg po (Rofecoxib) 1 h prior to surgery. After a standardized spinal anesthetic, patients in the Control group received ketoprofen 100 mg IV q 8 h for 24 h, while the Rofecoxib group received an equivolume of saline at 8-h intervals for 24 h. Both groups were allowed to self-administer morphine (1 mg IV boluses) using a PCA delivery system. The need for 'rescue' analgesic medication, as well as pain scores [using an 11-point verbal rating scale (VRS) (0 = none to 10-severe)], were recorded at 1, 2, 6, 12, and 24-h intervals after surgery. In addition, the incidences of side-effects were recorded at the end of the study period. RESULTS: Total amount of morphine required in the initial 24-h postoperative period was nonsignificantly reduced in the Rofecoxib group (29 +/- 2 vs. 37 +/- 4 mg). More importantly, the percentage of patients reporting moderate-to-severe pain (VRS score > or =4) during the study period was lower in the Rofecoxib group (12 vs. 22%, P < 0.05). The daily cost of rofecoxib (USD 1.14 for 50-mg dose) was also significantly less than ketoprofen (USD 3.06 for three 100-mg doses). CONCLUSION: Premedication with oral rofecoxib (50 mg) is a cost-effective alternative to the parenteral nonselective NSAID, ketoprofen (100 mg q 8 h), when used as an adjuvant to PCA morphine for pain management after urologic surgery.

A free energy based computational pathway from chemical templates to lead compounds: a case study of COX-2 inhibitors.

Automation of lead compound design in silico given the structure of the protein target and a definition of its active site vies for the top of the wish list in any drug discovery programme. We present here an enumeration of steps starting from chemical templates and propose a solution at the state of the art, in the form of a system independent comprehensive computational pathway. This methodology is illustrated with cyclooxygenase-2 (COX-2) as a target. We built candidate molecules including a few Non Steroidal Anti-inflammatory Drugs (NSAIDs) from chemical templates, passed them through empirical filters to assess drug-like properties, optimized their geometries, derived partial atomic charges via quantum calculations, performed Monte Carlo docking, carried out molecular mechanics and developed free energy estimates with Molecular Mechanics Generalized Born Solvent Accessibility (MMGBSA) methodology for each of the candidate molecules. For the case of aspirin, we also conducted molecular dynamics on the enzyme, the drug and the complex with explicit solvent followed by binding free energy analysis. Collectively, the results obtained from the above studies viz. sorting of drugs from non-drugs, semi-quantitative estimates of binding free energies, amply demonstrate the viability of the strategy proposed for lead selection/design for biomolecular targets.