New histone deacetylase inhibitors as potential therapeutic tools for advanced prostate carcinoma

The anti-epileptic drug valproic acid is also under trial as an anti-cancer agent due to its histone deacetylase (HDAC) inhibitory properties. However, the effects of valproic acid (VPA) are limited and concentrations required for exerting anti-neoplastic effects in vitro may not be reached in tumour patients. In this study, we tested in vitro and in vivo effects of two VPA-derivatives (ACS2, ACS33) on pre-clinical prostate cancer models. PC3 and DU-145 prostate tumour cell lines were treated with various concentrations of ACS2 or ACS33 to perform in vitro cell proliferation 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays and to evaluate tumour cell adhesion to endothelial cell monolayers. Analysis of acetylated histones H3 and H4 protein expression was performed by western blotting. In vivo tumour growth was conducted in subcutaneous xenograft mouse models. Tumour sections were assessed by immunohistochemistry for histone H3 acetylation and proliferation. ACS2 and ACS33 significantly up-regulated histone H3 and H4 acetylation in prostate cancer cell lines. In micromolar concentrations both compounds exerted growth arrest in PC3 and DU-145 cells and prevented tumour cell attachment to endothelium. In vivo, ACS33 inhibited the growth of PC3 in subcutaneous xenografts. Immunohistochemistry and western blotting confirmed increased histone H3 acetylation and reduced proliferation. ACS2 and ACS33 represent novel VPA derivatives with superior anti-tumoural activities, compared to the mother compound. This investigation lends support to the clinical testing of ACS2 or ACS33 for the treatment of prostate cancer.

Anti-inflammatory and gastrointestinal effects of a novel diclofenac derivative

S-diclofenac (2-[(2,6-dichlorophenyl)amino]benzeneacetic acid 4-(3H-1,2,dithiol-3-thione-5-yl)phenyl ester; ACS 15) is a novel molecule comprising a hydrogen sulfide (H2S)-releasing dithiol-thione moiety attached by an ester linkage to diclofenac. S-diclofenac administration inhibited lipopolysaccharide-induced inflammation (as evidenced by reduced lung and liver myeloperoxidase activity) and caused significantly less gastric toxicity than diclofenac. S-diclofenac did not affect blood pressure or heart rate of the anesthetized rat. S-diclofenac administration downregulated expression of genes encoding enzymes which synthesize nitric oxide, prostanoids, and H2S; reduced plasma IL-1beta/TNF-alpha; and elevated plasma IL-10. Reduced liver NF-kappaB p65 and AP-1/c-fos DNA-binding activity was also observed. These effects were mimicked in large part by a combination of diclofenac plus an H2S-releasing moiety (ADT-OH). Incubation of S-diclofenac (100 microM) with rat plasma or liver homogenate caused a time-dependent release of H2S, which was inhibited by sodium fluoride (10 mM). Administration of S-diclofenac (47.2 micromol/kg, i.p.) to conscious rats significantly increased plasma H2S concentration (at 45 min and 6 h). We propose that H2S release from S-diclofenac in vivo contributes to the observed effects.

Nitroaspirin corrects immune dysfunction in tumor-bearing hosts and promotes tumor eradication by cancer vaccination

Active suppression of tumor-specific T lymphocytes can limit the immune-mediated destruction of cancer cells. Of the various strategies used by tumors to counteract immune attacks, myeloid suppressors recruited by growing cancers are particularly efficient, often resulting in the induction of systemic T lymphocyte dysfunction. We have previously shown that the mechanism by which myeloid cells from tumor-bearing hosts block immune defense strategies involves two enzymes that metabolize L-arginine: arginase and nitric oxide (NO) synthase. NO-releasing aspirin is a classic aspirin molecule covalently linked to a NO donor group. NO aspirin does not possess direct antitumor activity. However, by interfering with the inhibitory enzymatic activities of myeloid cells, orally administered NO aspirin normalized the immune status of tumor-bearing hosts, increased the number and function of tumor-antigen-specific T lymphocytes, and enhanced the preventive and therapeutic effectiveness of the antitumor immunity elicited by cancer vaccination. Because cancer vaccines and NO aspirin are currently being investigated in independent phase I/II clinical trials, these findings offer a rationale to combine these treatments in subjects with advanced neoplastic diseases.

Liver delivery of NO by NCX-1000 protects against acute liver failure and mitochondrial dysfunction induced by APAP in mice

1. NCX-1000, (3alpha, 5beta, 7beta)-3,7-dihydroxycholan-24oic acid[2-methoxy-4-[3-[4-(nitroxy)butoxy]-3-oxo-1-propenyl]phenyl ester, is a nitric oxide (NO)-derivative of ursodeoxyxholic acid (UDCA) that selectively release NO in the liver. 2. Here, we demonstrated that administering mice with 40 micromol kg(-1) NCX-1000, but not UDCA, improves liver histopathology and reduces mortality caused by 330 micromol kg(-1) APAP from 60 to 25% (P<0.01). Administration of NCX-1000, in a therapeutic manner, that is, 2 h after acetaminophen (APAP) intoxication reduced mortality, improved liver histopathology and prevented liver IFN-gamma, TNF-alpha, Fas/Fas ligand and inducible nitric oxide synthase (iNOS) mRNA accumulation caused by APAP. 3. In vitro exposure of primary cultures of mouse hepatocytes to APAP, 6.6 mm, resulted in apoptosis followed by necrosis. Loss of cell viability correlates with early mitochondrial membrane potential (Deltapsi(m)) hyperpolarization followed by depolarization and cytochrome c translocation from mitochondria to cytosol. APAP-induced apoptosis associated with procaspase-3 and -9 cleavage, appearance of truncated Bid and activation of poly(ADP-ribose) polymerase (PARP). 4. Treating primary culture of hepatocytes with 5 microm cyclosporine and 10 microm trifluoperazine for eight resulted in significant reduction of apoptosis induced by APAP suggesting that loss of Deltapsim was mechanistically involved in apoptosis induced by APAP in vitro. 5. NCX-1000, but not UDCA, concentration-dependently (ED(50)=16 microm) protected against Deltapsi(m) depolarization and reduced transition from apoptosis to necrosis caused by 6.6 mm APAP. 6. Treating primary cultures of hepatocytes with the NO-donor DETA-NO, 100 microm, reduced apoptosis induced by APAP and prevented caspase activation. 7. In conclusion, NCX-1000 is effective in protecting against APAP-induced hepatotoxicity when administered in a therapeutic manner. This protection may involve the inhibition of apoptosis and the maintenance of mitochondrial integrity.

NSAIDs increase GM-CSF release by human synoviocytes: comparison with nitric oxide-donating derivatives

Non-steroidal anti-inflammatory drugs (NSAIDs) are used to treat the condition of rheumatoid arthritis, where levels of prostaglandin E2 (PGE2) and granulocyte macrophage-colony stimulating factor (GM-CSF) are elevated in the synovial fluid. NO-NSAIDs are a new class of cyclooxygenase (COX)-inhibitors developed by coupling a nitric oxide (NO)-donating moiety to conventional NSAIDs. We show that, in cytokine-treated synoviocytes (from non-rheumatic patients), NO-naproxen and NO-flurbiprofen like their parent compounds concentration-dependently reduce the levels of PGE2 (an index of COX-2 activity), with a corresponding rise in the release of GM-CSF. Unlike acetylsalicylic acid (ASA), NO-ASA reduces the levels of PGE2, without increasing GM-CSF release, although cell viability is reduced at the highest concentration (1 mM). The effects of NSAIDs and NO-NSAIDs on GM-CSF release were attributable to the PGE2 mediated cyclic (c) AMP pathway because PGE2 reversed the effects of COX blockade. Second, phosphodiesterase inhibitors 3-isobutyl-1-methylxanthine (IBMX) and Ro-201724 (both of which elevate cAMP levels) decreased GM-CSF release, in the presence of PGE2. Finally, neither sodium nitroprusside nor zaprinast (both of which elevate cGMP levels) affected GM-CSF or PGE2 release. Our findings demonstrate that GM-CSF is regulated by NSAIDs and NO-NSAIDs via inhibition of COX and appears to be mediated via the cAMP pathway. NO-ASA is the exception, because it does not increase GM-CSF release, although at millimolar concentrations cell viability is reduced.

Positional Isomerism Markedly Affects the Growth Inhibition of Colon Cancer Cells by Nitric Oxide-Donating Aspirin in Vitro and in Vivo

NO-donating aspirin (NO-ASA), a novel pharmacological agent currently undergoing clinical testing, consists of ASA to which a nitrate group is covalently linked via a spacer molecule. We synthesized the three positional isomers of NO-ASA with respect to the -CH(2)ONO(2) group (ortho, meta, and para) and examined whether this isomerism affects the biological activity of NO-ASA on HT-29 human colon cancer cells. The ortho- and para-isomers showed similar IC(50) values (1-5 microM) for cell growth inhibition over 72 h, whereas the IC(50) of the meta-isomer was 200 to 500 microM. The ortho- and para-isomers inhibited cell proliferation more potently than the meta-isomer. All three induced apoptosis but the ortho- and para-isomers also induced atypical cells (they maintain their shape but have diminished or absent nuclear material). Treatment for 3 weeks of Min (Apc(min)(/+)) mice, a model of intestinal cancer, with equimolar amounts of meta- and para-NO-ASA decreased the number of tumors in the small intestine by 36 and 59% (P < 0.01), respectively, compared with vehicle-treated controls, thus confirming their in vitro differences in potency. A structure-activity study of the three isomers revealed that substituting an aliphatic for the aromatic spacer or removing the -ONO(2) group profoundly diminished NO-ASA's ability to inhibit cell growth, whereas removal of the acetyl group on the ASA moiety did not affect cell growth inhibition. Thus, positional isomerism is critical for the pharmacological properties of NO-ASA against colon cancer and it should be taken into consideration in rational drug design.

The effects and metabolic fate of nitroflurbiprofen in healthy volunteers

OBJECTIVE

Nitric oxide-donating nonsteroidal anti-inflammatory drugs (NO-NSAIDs) are a new class of cyclooxygenase (COX) inhibitors. To investigate whether these drugs actually release nitric oxide (NO), we labeled the nitroxy group of nitroflurbiprofen with nitrogen 15 to determine the metabolic fate of this compound in humans.

METHOD

Six healthy volunteers who fasted were given an oral dose of 15 N-nitroflurbiprofen (100 mg). Samples of blood, urine, and gastric headspace gas were taken over a 24-hour period to determine the levels of nitroflurbiprofen, flurbiprofen, total nitrate/nitrite, 15 N-nitrate/nitrite, COX activity, and gastric NO. In a crossover study (1 week apart), a further 6 healthy volunteers who fasted were given an oral dose of nitroflurbiprofen (100 mg) or flurbiprofen (65 mg) and levels of gastric NO were determined.

RESULTS

Nitroflurbiprofen was undetectable in the systemic circulation. Levels of 15 N-nitrate/nitrite (5.2% +/- 1.5% enrichment) and flurbiprofen (2.4 +/- 0.7 microg/mL) peaked at 4 hours in the plasma and gradually decreased thereafter. In unstimulated blood, the plasma levels of thromboxane B 2 (COX-1 activity) were 2 to 3 ng/mL, and after calcium ionophore stimulation, large amounts of thromboxane B 2 were produced (112 +/- 31 ng/mL). Prostaglandin E 2 was undetectable in unstimulated blood. After lipopolysaccharide stimulation, the plasma levels of prostaglandin E 2 increased to 15 +/- 4 ng/mL. The metabolite flurbiprofen inhibited plasma COX-1 activity for the duration of the study period (maximum inhibition at 4 hours), whereas COX-2 activity recovered after 6 hours. In the crossover study, levels of gastric NO were higher in subjects given nitroflurbiprofen, when compared with those given flurbiprofen. (The area under the curve for gastric NO was 435 +/- 107 ppm . h versus 305 +/- 94 ppm . h [95% confidence interval of the difference, 89-172 ppm . h; P < .001]).

CONCLUSION

Nitroflurbiprofen was undetectable in the systemic circulation, suggesting metabolism to 15 N-nitrate/nitrite and flurbiprofen in the presystemic circulation. Levels of gastric NO were significantly higher after ingestion of nitroflurbiprofen than flurbiprofen.

Comparison of the antinociceptive activity of two new NO-releasing derivatives of the NSAID S-ketoprofen in rats

1 Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenase (COX) enzymes inducing analgesic, anti-inflammatory and antipyretic actions. They are not devoid of severe side effects and so, the search for new compounds with similar or higher effectiveness and a lower incidence of undesired actions is important. Nitric oxide (NO)-releasing NSAIDs resulted from this search. 2 We have compared the antinociceptive effectiveness of cumulative doses of two new NO-releasing derivatives of S-ketoprofen, HCT-2037 and HCT-2040, using the recording of spinal cord nociceptive reflexes in anesthetized and awake rats and after intravenous and oral administration. 3 S-ketoprofen and HCT-2040 were equieffective in reducing responses to noxious mechanical stimulation after i.v. administration in anesthetized animals (ID50s: 1.3+/-0.1 and 1.6+/-0.2 micromol kg(-1) respectively), but did not modify wind-up. HCT-2037 was two-fold more potent (ID50 of 0.75+/-0.1 micromol kg(-1)) in responses to mechanical stimuli and very effective in reducing wind-up (63+/-17% of control; P<0.01; MED: 0.4 micromol kg(-1)), indicating a greater activity than the parent compound. 4 In awake animals with inflammation, HCT-2037 p.o. fully inhibited mechanical allodynia, 91+/-12% reduction, and hyperalgesia, 94+/-8% reduction. Equivalent doses of S-ketoprofen only partially reduced either allodynia (50+/-11%) or hyperalgesia (40+/-4%). The effect on responses to noxious thermal stimulation was similar for the two compounds. 5 We conclude that the molecular changes made in the structure of S-ketoprofen including an NO moiety in its structure, improve the antinociceptive profile of the compound opening new perspectives in a safer use of NSAIDs as analgesic drugs.

Nitric oxide-releasing aspirin derivative, NCX 4016, promotes reparative angiogenesis and prevents apoptosis and oxidative stress in a mouse model of peripheral ischemia

BACKGROUND

Recently, nitric oxide (NO) donors have been developed that mimic the physiological intracellular release of NO. We evaluated whether one of these new compounds, consisting of aspirin coupled to an NO-releasing moiety (NCX 4016), would protect limbs from supervening arterial occlusion.

METHODS AND RESULTS

Mice were assigned to receive regular chow or chow containing NCX 4016 or aspirin (both at 300 mumol/kg body weight, daily) throughout the 3-week experimental period. One week after randomization, they underwent surgical excision of the left femoral artery. Limb blood flow recovery (laser Doppler flowmetry) was accelerated by NCX 4016 as compared with aspirin or vehicle (P<0.05). In controls, histological analysis revealed a 35% increase in the capillary density of ischemic muscles compared with contralateral ones, indicative of spontaneous angiogenesis. Neovascularization was enhanced by NCX 4016 (91%; P<0.05 versus vehicle), but not by aspirin (51%; P=NS versus vehicle). Furthermore, NCX 4016 reduced endothelial cell (EC) apoptosis (4.3+/-1.0 versus 8.7+/-2.0 in aspirin and 12.6+/-3.3 ECs/1000 cap in vehicle; P<0.05 for either comparison) as well as caspase-3 mRNA levels in ischemic muscles ([caspase-3/GAPDH]*100 = 0.09+/-0.04 versus 2.30+/-0.44 in aspirin and 2.30+/-0.32 in vehicle; P<0.01 for either comparison). Nitrite levels and the ratio of reduced to oxidized glutathione were selectively increased in ischemic muscles by NCX 4016. Vascular endothelial growth factor-A expression was reduced by aspirin, with this effect being blunted by NCX 4016.

CONCLUSIONS

Pretreatment with the new oral NO-releasing aspirin derivative stimulates reparative angiogenesis and prevents apoptosis and oxidative stress, thereby alleviating the consequences of supervening arterial occlusion.

Nitric oxide-releasing aspirin inhibits vasoconstriction in perfused tail artery of normotensive and spontaneously hypertensive rats

The aim of this study was to investigate the capacity of the 2-(acetyloxy)benzoic acid 3-(nitrooxymethyl)phenyl ester (NCX 4016), a nitric oxide (NO)-releaser derivative of aspirin, to decrease blood pressure in spontaneously hypertensive rats (SHR) and to counteract the adrenergic vasoconstriction in perfused tail artery of these animals. Oral treatment for 10 consecutive days with NCX 4016 (100 micromol/kg) in SHR and their genetic controls Wistar Kyoto (WKY) rats resulted in a reduction of blood pressure in SHR but not in WKY rats. In SHR, the NCX 4016 treatment increased the serum nitrite/nitrate and diminished the serum thromboxane B2, whereas aspirin did not change blood pressure but abolished the serum thromboxane B2. Perfused tail arteries excised from vehicle-treated SHR exhibited a significant impairment of endothelium-dependent vasorelaxant function. These vessels, prepared from SHR or WKY rats treated orally with NCX 4016 (10, 30 and 100 micromol/kg for 7 consecutive days), revealed a dose-dependent decrease in vasoconstriction in response to transmural nerve stimulation and norepinephrine, whereas aspirin was ineffective. Furthermore, in tail arteries of both SHR and WKY rats treated orally with NCX 4016 (100 micromol/kg for 7 consecutive days), the cGMP increased significantly. In conclusion, NCX 4016, by releasing NO and increasing cGMP in vascular tissue, reduces sympathetic-mediated vasoconstriction in resistance vessels and lowers blood pressure in SHR.

Nitric oxide (NO)-releasing statin derivatives, a class of drugs showing enhanced antiproliferative and antiinflammatory properties

Inhibitors of 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase, namely statins, exert pleiotropic actions beyond lipid-lowering effects. Their pharmacological activity on atherosclerotic plaque stability and vascular inflammation appears to be mediated, at least in part, by nitric oxide (NO). With the aim of enhancing the nonlipid-lowering properties of selected statins, we introduced a NO-releasing moiety into the structure of pravastatin (NCX 6550) and fluvastatin (NCX 6553). NO release was evaluated as nitrosylhemoglobin adduct formation by using EPR spectroscopy in rat blood. Both compounds produced a linear time-dependent increase in nitrosylhemoglobin formation, which is consistent with slow NO release kinetics. In PC12 cells, unlike their native statins, both compounds stimulated cGMP formation (NCX 6550, EC(50) = 2.3 +/- 0.2 microM; NCX 6553, EC(50) = 2.7 +/- 0.2 microM). Moreover, NCX 6550 potently inhibited cell proliferation in rat aortic smooth muscle cells (IC(50) = 2.2 +/- 0.3 microM) with a mechanism that involved both the polyamine and HMG-CoA reductase signaling pathways. Hence, mevalonate or putrescine partially reverted the effects of NCX 6550 and their combination was fully effective. In RAW 264.7 murine macrophage cells stimulated with lipopolysaccharide (1 microg/ml), NCX 6550, but not pravastatin, significantly decreased inducible NO synthase and cyclooxygenase-2 protein expression as well as nitrite accumulation. All together, the data show that the previously undescribed NO-releasing statins retain HMG-CoA reductase inhibitory activity and release bioactive NO slowly. Among the additional properties, compared with native statins, the NO-releasing statins show enhanced antiinflammatory effects. Thus, NO-releasing statins represent an interesting class of drugs having potential in the therapy of disorders associated with endothelial dysfunction and vascular inflammation.

Cooperation between aspirin-triggered lipoxin and nitric oxide (NO) mediates antiadhesive properties of 2-(Acetyloxy)benzoic acid 3-(nitrooxymethyl)phenyl ester (NCX-4016) (NO-aspirin) on neutrophil-endothelial cell adherence

2-(Acetyloxy)benzoic acid 3-(nitrooxymethyl)phenyl ester (NCX-4016) is a nitric oxide (NO)-releasing derivative of aspirin that inhibits cyclooxygenase (COX) activity and releases NO. Acetylation of COX-2 by aspirin activates a transcellular biosynthetic pathway that switches eicosanoid biosynthesis from prostaglandin E(2) to 15-epi-lipoxin (LX)A(4) or aspirin-triggered lipoxin (ATL). Here, we demonstrate that exposure of neutrophil (PMN)/human umbilical vein endothelial cell (HUVEC) cocultures to aspirin and NCX-4016 triggers ATL formation and inhibits cell-to-cell adhesion induced by endotoxin (LPS) and interleukin (IL)-1beta by 70 to 90%. However, although selective and nonselective COX-2 inhibitors (celecoxib, rofecoxib, and naproxen) or N-t-butoxycarbonylmethionine-leucine-phenylalanine (Boc-1), an LXA(4) receptor antagonist, reduced the antiadhesive properties of aspirin by approximately 70%, antiadhesive effects of NCX-4016 were only marginally affected ( approximately 30%) by COX inhibitors and Boc-1, implying that COX-independent mechanisms mediate the antiadhesive properties of NCX-4016. Indeed, NCX-4016 causes a long-lasting (up to 12 h) release of NO and cGMP accumulation in HUVEC. Scavenging NO with 10 mM hemoglobin, in the presence of celecoxib, reduced the antiadhesive properties of NCX-4016 by approximately 80%. Confirming a role for NO, the NO donor diethylenetriamine-NO also inhibited PMN/HUVEC adhesion by approximately 80%. NCX-4016, but not aspirin, decreased DNA binding of nuclear factor-kappaB (NF-kappaB) on gel shift analysis and HUVEC's overexpression of CD54 and CD62E induced by LPS/IL-1beta. Reduction of binding of the two NF-kappaB subunits p50-p50 and p50-p65 was reversed by dithiothreitol, implying S-nitrosylation as mechanism of inhibition. In summary, our results support that ATL and NO are formed at the PMN/HUVEC interface after exposure to NCX-4016 and mediate the antiadhesive properties of this compound.

Enhanced Anti-Inflammatory Potency of a Nitric Oxide-Releasing Derivative of Flunisolide: Role of Nuclear Factor-κB

Glucocorticoids remain among the most commonly used anti-inflammatory drugs, despite significant adverse effects. Other anti-inflammatory drugs, including aspirin, have been coupled through an ester linkage to a nitric oxide-releasing moiety, resulting in an increase in potency and a decrease in adverse effects. Prednisolone has similarly been modified, with marked improvement of its therapeutic index. In the present study, we have evaluated whether a nitric oxide-releasing derivative of another glucocorticoid, flunisolide, would increase its potency as an anti-inflammatory agent and would decrease its systemic toxicity. To evaluate anti-inflammatory potency and efficacy, the carrageenan-airpouch model in the rat was used. Flunisolide and NCX-1024 (flunisolide-21-[4'-(nitrooxymethyl) benzoate]) were compared across a range of doses, with both direct injection into the airpouch and oral administration. The ability of these agents to protect the stomach against indomethacin-induced damage also was assessed. Effects of oral administration of the two drugs on body weight gain and adrenal suppression were also evaluated. With direct application into the airpouch, NCX-1024 was found to be 41 times more potent than flunisolide in reducing leukocyte accumulation and prostaglandin E2 generation. The increased potency may be related to an enhanced ability of NCX-1024 to prevent nuclear factor-kappaB activation. When given orally, the two compounds exhibited similar potency. However, orally administered NCX-1024 was more potent at protecting against indomethacin-induced gastric damage, caused less reduction of body weight, and, unlike flunisolide, did not cause adrenal atrophy. These studies suggest that NCX-1024 may be an attractive alternative to conventional glucocorticoids, particularly for applications involving topical administration.

The Distinct Alterations Produced in Cardiovascular Functions by Prednisolone and Nitro-prednisolone (NCX-1015) in the Rat Highlight a Causal Role for Endothelin-1

Daily administration of prednisolone, but not the derivative NCX-1015 (or prednisolone 21-[4'-nitrooxymethyl]benzoate), to rats resulted in a time- and dose-dependent increase in mean arterial blood pressure (MABP), significant after 1 week for the dose of 6.9 micromol/kg i.p. (n = 10; P < 0.05), and 3 weeks for the lower dose of 1.38 micromol/kg. A similar dichotomy of behavior was observed with respect to myocardial contractility and renal vascular resistance, in either case augmented by 3-week treatment with prednisolone but not NCX-1015. In contrast, both NCX-1015 and prednisolone reduced plasma levels of corticosterone in a dose- (dose range of 0.69-6.9 micromol/kg i.p.) and time-dependent (1-3 weeks) manner. Similar profiles were obtained for plasma nitrate values, although they were increased selectively after NCX-1015 administration. In contrast, prednisolone, but not NCX-1015, augmented plasma endothelin 1 (ET-1) with a profile that mirrored the changes observed in MABP and renal blood flow. Supply in the drinking water of the ET-1 receptor type A (ETA) antagonist FR139317 [(R-2-[(R)-2-[(S)-2-[[1-(hexahydro-1H-azepinyl)]-carbonyl]amino-4-methylpentanoyl]-amino-3-(2-pyridil)propionic] or mixed ETA/B, but not of selective ETB, antagonists prevented the changes produced by a 21-day treatment with prednisolone. In conclusion, this study indicates 1) a lack of occurrence of cardiovascular alterations by nitro-releasing derivative of prednisolone (NCX-1015), and 2) a functional link between prednisolone effects and the endogenous endothelin-1 system.

A Nitric Oxide-Releasing Salbutamol Elicits Potent Relaxant and Anti-Inflammatory Activities

Beta2-adrenoceptor agonists are widely used in the treatment of pulmonary diseases. We have investigated the relaxant and anti-inflammatory activities of NCX-950 (alpha'-[[(1,1-dimethylethy)amino]methyl]-4-hydroxy-1,3-benzenedimethanol nitrate) (a nitric oxide-releasing salbutamol) in human isolated bronchi and on lipopolysaccharide (LPS)-induced acute airway inflammation in mice. NCX-950 (10(-8)-10(-5) M) elicited a relaxation of human isolated bronchi moderately higher than salbutamol, which was reduced by a beta-adrenergic blocking drug, propranolol, but not by an inhibitor of guanylate cyclase, ODQ (1H-[1,2,4]oxadiazolo[4,3-] quinolaxin-1-one). The treatment of mice with NCX-950 (1, 10, and 100 microM aerosol) markedly inhibited the neutrophil influx induced by LPS aerosol in bronchoalveolar lavage (BAL) fluid, whereas salbutamol at equimolar doses elicited a moderate inhibition. Pretreatment of mice with NCX-950 (100 microM) also significantly reduced tumor necrosis factor-alpha, interleukin-6 (IL-6), transforming growth factor-beta, and matrix metalloproteinase-9 release in BAL fluid, whereas salbutamol was ineffective. Propranolol, but not ODQ, suppressed the inhibitory activity of NCX-950 on neutrophil influx and IL-6 release in BAL fluids. A nitric oxide-releasing sildenafil NCX-911 [(5-[2-ethoxy-5-(4-methylpiperidinylsulfonyl)phenyl]-1-methyl-3-n-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one nitrate)], but not sildenafil (100 microM) also reduced the neutrophil influx following LPS exposure in mice. This study reported that NCX-950 elicits potent relaxant and anti-inflammatory activities compared with salbutamol, and these effects may be mainly due to the activation of the beta2-adrenoceptor rather than the cGMP pathway.

The Nitric Oxide-Releasing Naproxen Derivative Displays Cardioprotection in Perfused Rabbit Heart Submitted to Ischemia-Reperfusion

In this study, the pharmacological activity of HCT-3012 [(S)-6-methoxy-alpha-methyl-2-naphtaleneacetic acid 4-(nitrooxy)butyl ester], a nitric oxide (NO)-releasing derivative of naproxen, was compared with that of naproxen in a model of acute ischemia (40 min) and reperfusion (20 min) of the rabbit heart. HTC-3012 (3-100 microM), in spite of inhibition of 6-keto-prostaglandin F(1alpha) generation by the cardiac tissues, brought about a dose-dependent normalization of coronary perfusion pressure, associated with a reduction of ventricular contracture during ischemia with remarkable improvement of left ventricular developed pressure at reperfusion. These beneficial effects were accompanied by a substantial release of nitrite/nitrate in the heart perfusates, indicating that NO has been released by HCT-3012 and donated to the cardiac tissue. These events were paralleled by a significant reduction of creatine kinase activity in heart perfusates during reperfusion. Naproxen (10-100 microM) aggravated the myocardial damage in ischemic reperfused hearts, severely depressing the postischemic ventricular dysfunction. Perfusion of the heart with N(G)-monomethyl-l-arginine (10 microM) caused a marked aggravation of myocardial damage of the reperfused hearts, and this effect was dose dependently prevented by HCT-3012 but not by naproxen. The results of the present experiments clearly indicate that HCT-3012, by donating NO, displays a noticeable anti-ischemic effect in reperfused ischemic rabbit hearts. The safer gastrointestinal profile of HCT-3012 and its ability to control experimental hypertension, suggest that this compound may have therapeutical potential in cardiovascular disease, namely in the prevention of myocardial ischemic events, and may represent a better alternative to conventional nonsteroidal anti-inflammatory drugs.

Antioxidant activity of nitro derivative of aspirin against ischemia-reperfusion in hamster cheek pouch microcirculation

Aspirin that has been chemically combined with a nitric oxide (NO) donor (NCX-4016) has been shown to inhibit cyclooxygenase and prostaglandin generation while maintaining the inhibitory effects of aspirin. The possible role of reactive oxygen species (ROS) in the action of NCX-4016 in ischemia-reperfusion (I/R) has not been studied. Furthermore, we were interested in comparing the effects of a conventional NO donor [2,2'-hydroxynitrosohydrazino-bis-etanamine (DETA/NO)] and NCX-4016 at the microvascular level in the hamster cheek pouch visualized by using an intravital fluorescent microscopy technique. Microvascular injury was assessed by measuring diameter change, the perfused capillary length (PCL), and leukocyte adhesion. Animals were treated with NCX-4016 (100 mg/kg or 30 mg.kg(-1).day(-1) for 5 days po) or DETA-NO (0.5 mg/kg). Mean arterial blood pressure increased slightly but significantly after NCX-4016 treatment. During 5- and 15-min reperfusion, lipid peroxides in the systemic blood increased by 72 and 89% vs. baseline, respectively, and were still higher than in basal conditions after 30-min reperfusion in the I/R group. Pretreatment with NCX-4016 maintained ROS at normal levels; increased arteriolar diameter, blood flow, and PCL; and decreased leukocyte adhesion (P < 0.05). DETA-NO decreased ROS during 30-min reperfusion; however, later there was a significant increase during reperfusion. DETA-NO decreased leukocyte adhesion (P < 0.05) but microvascular permeability increased after 30 min of reperfusion. In conclusion, NCX-4016 attenuates oxidative stress and prevents arteriolar constriction during I/R, whereas DETA-NO increases lipid peroxides in the systemic blood and permeability after reperfusion.

Nitric oxide-releasing non steroidal anti-inflammatory drugs: a new generation of anti-tumoral molecules

Colorectal cancer is the second most common cause of cancer-related mortality in the west. The high incidence and mortality make effective prevention an important public-health and economic issue. The regular intake of aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) has been associated with decreased incidence of certain types of cancer particularly those with an inflammatory component, and then are among the few agents known to be chemopreventive. Nitric oxide-releasing non-steroidal anti-inflammatory drugs (NO-NSAIDs) are new chemical entities obtained by adding a nitric oxide-releasing moiety to classical molecules. This new class of molecules has been demonstrated to be much more safe than NSAIDs due to their ability to reduce gastric toxicity. They could therefore represent an alternative to classical NSAIDs treatment. In this review, we sumarise the recent findings in the mechanisms and pathways involved in the antitumoral effects of both NSAIDs and NO-NSAIDs as well as the clinical trials performed with these compounds.

A nitric oxide‐releasing derivative of enalapril, NCX 899, prevents progressive cardiac dysfunction and remodeling in hamsters with heart failure

Nitric oxide (NO) production is known to be impaired in heart failure. A new compound (NCX 899), a NO-releasing derivative of enalapril was characterized, and its actions were evaluated in Bio 14.6 cardiomyopathic (CM) hamsters with heart failure. The hamsters were randomized to oral treatment for 4 weeks with vehicle (n=11), NCX 899 (NCX, 25 mg/kg, n=10), or enalapril (25 mg/kg, n=10). In the vehicle group, fractional shortening by echocardiography decreased (-23.6+/-2.0%) and LV end-diastolic dimension) increased (+10.9+/-1.0%), whereas fractional shortening increased (+17.5+/-4.4%) in NCX and was unchanged in the enalapril group (both P<0.01 vs. vehicle). End-diastolic dimension decreased only in NCX. LV contractility (LVdP/dt max and Emax) was significantly greater in NCX than in enalapril or vehicle, while relaxation (Tau) was shortened in both NCX and enalapril vs. vehicle. ACE activity was inhibited equally by NCX and enalapril in the CM hamster, and plasma nitrate levels were increased only in NCX (P<0.05 vs. enalapril and vehicle). In aortic strips endothelium-independent relaxation occurred only with NCX. The superior effects of NO-releasing enalapril (NCX) vs. enalapril alone to enhance vascular effects, increase LV contractility and prevent unfavorable remodeling and are consistent with vascular delivery of exogenous NO. NCX 899 may hold promise for the future treatment of heart failure.

NCX-1000, a nitric oxide-releasing derivative of ursodeoxycholic acid, ameliorates portal hypertension and lowers norepinephrine-induced intrahepatic resistance in the isolated and perfused rat liver

BACKGROUND/AIMS

We studied whether acute administration of NCX-1000, a nitric oxide (NO)-releasing derivative of ursodeoxycholic acid (UDCA), to animals with established liver cirrhosis decreases intrahepatic resistance and modulates hepatic vascular hypereactivity to norepinephrine (NE).

METHODS

Four-week bile duct ligated (BDL) cirrhotic and control, sham-operated, rats were treated orally with 28 mg/kg per day NCX-1000 or 15 mg/kg per day UDCA for 5 days. Isolated normal and cirrhotic livers were perfused with NE, from 10 nM to 30 microM, in a recirculating system.

RESULTS

NCX-1000 administration to BDL cirrhotic rats decreased portal pressure (P<0.01) without affecting mean arterial pressure and heart rate. In the isolated perfused liver system, administration of NE resulted in a dose-dependent increase of intrahepatic resistance. Vasoconstriction caused by 30 microM NE was reduced by 60% in animals treated with NCX-1000 (P<0.001), while UDCA was uneffective. The same portal pressure lowering effect was documented in cirrhotic and sham operated rats. Administration of NCX-1000 to BDL and sham operated rats resulted in a similar increase of nitrite/nitrate and cGMP concentrations in the liver.

CONCLUSIONS

By selectively delivering NO to the liver, NCX-1000 increases cGMP concentrations and effectively counteracts the effect of endogenous vasoconstrictors on the hepatic vascular tone.

Low doses of nitroparacetamol or dexketoprofen trometamol enhance fentanyl antinociceptive activity

We have reported that subeffective doses of the nonsteroidal anti-inflammatory drug (NSAID) dexketoprofen trometamol enhances micro-opioid receptor agonist fentanyl antinociception. The aim of this study was to assess if this effect can also be observed with other new cyclooxygenase-inhibitors such as nitroparacetamol, and in responses to high intensity electrical stimulation (wind-up). Single motor units were recorded in male Wistar rats under alpha-chloralose anaesthesia. The antinociceptive effect of fentanyl was studied alone and in the presence of subeffective doses of dexketoprofen trometamol or nitroparacetamol. In responses to noxious mechanical stimulation, the potency of fentanyl was enhanced by more than threefold in the presence of the NSAIDs and no significant recovery was observed after 45 min. The opioid antagonist naloxone and the alpha(2)-adrenoceptor antagonist atipamezol did not reverse the effect. The enhancement of the effect of fentanyl in wind-up was lower though significant. We conclude that the co-administration of subeffective doses of new cyclooxygenase-inhibitors and the micro-opioid receptor agonist fentanyl should be considered as a potential pain therapy.

Effect of nitric oxide-donating agents on human monocyte cyclooxygenase-2

COX-2 is involved in inflammation and ischemic cardiovascular disease. As NO regulates COX activity in various cells, we investigated the effect of NO-donors and the novel NO-aspirin NC-4016 on human monocyte COX-2. Whole blood was incubated with LPS and PGE(2) was measured in plasma as an index of monocyte COX-2 activity. Serum TxB(2) was assessed as an index of platelet COX-1 activity. SNP, DetaNONOate, and NO-aspirin inhibited dose-dependently PGE(2) production while aspirin was ineffective. The guanylyl-cyclase inhibitor ODQ partially reversed the suppression of COX-2 activity by NO-aspirin, demonstrating a role of cGMP increase. NC-4016 and aspirin inhibited platelet COX-1 comparably while NO-donors were ineffective. COX-2 expression was not affected by NO-donors or NO-aspirin while aspirin or the selective COX-2-inhibitor DUP697 increased it. In conclusion, Nitroaspirin inhibits monocyte COX-2 activity by a cGMP-dependent mechanism. This might represent an advantage over aspirin, given the possible detrimental role of COX-2 in cardiovascular disease.

Glucocorticoid receptor nitration leads to enhanced anti-inflammatory effects of novel steroid ligands

It has recently emerged that posttranslational modification of proteins via nitration of tyrosine residues can alter their function. In this study, we describe that specific nitration of the glucocorticoid receptor (GR) by NCX-1015, a novel NO-donating prednisolone derivative (prednisolone 21-[4'-(nitrooxymethyl)benzoate), results in an enhancement of GR-mediated events. Incubation of PBMC and U937 cells with 1-10 micro M NCX-1015 caused faster activation of GR as assessed by augmented 1) binding to [(3)H]dexamethasone, 2) dissociation from heat shock protein 90, and 3) nuclear translocation. PBMCs treated with NCX-1015 contained GR that had undergone tyrosine nitration. The chemistry facilitating the increase in steroid binding capacity observed with NCX-1015 is specific, because changing the position of the NO-donating group or ubiquitous nitration by addition of an NO donor was unable to mimic this event. In vivo treatment with NCX-1015 provoked GR nitration and faster heat shock protein 90 dissociation as assessed in peritoneal cells. Accordingly, NCX-1015, but not prednisolone or other derivatives, produced a rapid inhibition of the early neutrophil recruitment and mediator generation in a model of peritonitis. In conclusion, we report here for the first time that posttranslational modification of GR by this novel nitrosteroid is associated with its enhanced anti-inflammatory activity.

Nitric oxide-donating non-steroidal anti-inflammatory drugs: the case of nitroderivatives of aspirin

Nitric oxide (NO) acts as a key signalling mechanism in a number of cells and tissues in the mammalian organism. Modulation of the biosynthesis of NO has emerged to be relevant to the treatment of a variety of human diseases. In the attempt to reduce the serious side effects of non-steroidal anti-inflammatory drugs (NSAIDs), especially in the gastrointestinal tract, a NO-releasing moiety has been linked to conventional NSAIDs. A prototypical example is that of NO-releasing derivatives of aspirin. Thanks to the cytoprotective action of NO such compounds do not produce gastric damage and are emerging as an interesting novel group of drugs for their unique pharmacological properties.