Effect of metamizol on promyelocytic and terminally differentiated granulocytic cells. Comparative analysis with acetylsalicylic acid and diclofenac

Metamizol is an analgesic and antipyretic agent that can induce agranulocytosis in certain patients. However, its effects on granulocyte viability and differentiation have been poorly evaluated. Here we analysed the effects of metamizol and its active metabolite, 4-methylaminoantipyrine (MAA), on the viability of HL60 promyelocytes and their dimethyl sulphoxide-induced differentiated granulocytes. Metamizol and MAA at 75 microM (above the peak of plasmatic concentration after 2g intake) did not alter granulocytic differentiation of HL60 cells. Only at concentrations above 100 microM, well over the pharmacological range, metamizol-induced apoptosis in about 30% of the HL60 promyelocytes, while HL60-granulocytic terminally differentiated cells were more resistant to this apoptotic action. When the effects of metamizol were compared with those of acetylsalicylic acid (ASA) and diclofenac on cell viability, at equivalent concentrations used in analgesic and antipyretic therapy (75 microM for metamizol, and ASA and 3 microM for diclofenac) their apoptotic effects were similar. Again, the HL60 promyelocytes were more sensitive to apoptosis than granulocytic differentiated cells, as measured by the percentage of sub-G(1) cells detected by flow cytometry and by determination of caspase activity as a function of poly(ADP-ribose) polymerase cleavage. Furthermore, when human blood-derived granulocytes were treated with metamizol, MAA, and ASA at 75 microM or diclofenac at 3 microM, less than 10% of apoptotic granulocytes were detected, whereas at toxicological/suprapharmacological concentrations (10mM), about 90% of granulocytes were apoptotic. These results demonstrate that metamizol, MAA, ASA, and diclofenac, at pharmacological concentrations, neither affect the granulocytic differentiation process nor induce relevant apoptosis on terminally differentiated granulocytes.     

Do altering in ornithine decarboxylase activity and gene expression contribute to antiproliferative properties of COX inhibitors?

Two isoforms of cyclooxygenase (COX) participate in growth control; COX-1 is constitutively expressed in most cells, and COX-2 is an inducible enzyme in response to cellular stimuli. An induction of COX-2 found in neoplastic tissues results in increased cell growth, inhibition of apoptosis, activation of angiogenesis, and decreased immune responsiveness. Although both COX-1 and COX-2 inhibitors are suppressors of cell proliferation and appear to be chemopreventive agents for tumorigenesis, the molecular mechanisms mediating antiproliferative effect of COX inhibitors are still not well defined. This study contrasts and compares the effects of aspirin and celecoxib, inhibitors of COX-1 and COX-2, in rat hepatoma HTC-IR cells. The following were assessed: cell proliferation and apoptosis, ornithine decarboxylase (ODC) activity, and pattern expression of three immediate-early genes, c-myc, Egr-1, and c-fos. We have shown that the treatment of hepatocytes in vitro with the selective COX-2 inhibitor, celecoxib, was associated with induction of apoptosis and complete inhibition of cellular proliferation. Aspirin exhibited a small antiproliferative effect that was not associated with apoptosis. Treatment with celecoxib produced dose- and time-dependent decrease in ODC activity. In addition, at higher drug concentration the decrease in ODC activity was greater in proliferating than in resting cells. Much lesser inhibitory effect on ODC activity was observed in aspirin-treated cells. The two COX inhibitors did not change c-myc expression, significantly decreased the expression of Egr-1, and differentially altered expression of c-fos; aspirin did not change, but celecoxib dramatically decreased the levels of c-fos-mRNA. Our study revealed that celecoxib and aspirin share the ability to inhibit ODC activity and alter the pattern of immediate-early gene expression. It seems that some of the observed effects are likely to be related to COX-independent pathways. The precise mechanisms of action of COX inhibitors should be defined before using these drugs for cancer chemopreventive therapy.     

Suppression of dextran sodium sulfate-induced colitis in mice by zerumbone, a subtropical ginger sesquiterpene, and nimesulide: separately and in combination

Ulcerative colitis (UC) and Crohn's disease are inflammatory disorders of unknown cause and difficult to treat, though some synthetic chemicals, including ligands for peroxisome proliferator-activated receptors (PPARs), are anticipated to be useful drugs. In contrast, few food phytochemicals have been reported to suppress colitis in animal models. The present study was undertaken to explore the suppressive efficacy of zerumbone (ZER), a sesquiterpenoid present in the rhizome of Zingiber zerumbet Smith that is used as a condiment in Southeast Asian countries and known to be a potent suppressant of cyclooxygenase (COX)-2 and inducible nitric oxide synthase expression in cell culture systems. Acute colitis was induced by exposing female ICR mice to 5% DSS in drinking water for 1 week. One week prior to DSS administration, the experimental mice were fed ZER alone, nimesulide (NIM, a selective COX-2 inhibitor) alone, or both in combination (1000 ppm each) for a total of 2 weeks. Inflammatory biomarkers, i.e. interleukin (IL)-1alpha and IL-1beta, tumor necrosis factor (TNF)-alpha, and prostaglandin (PG)E(2) and PGF(2alpha) in colonic mucosa were quantified by an enzyme-linked immunosorbent assay in conjunction with histological alterations. Oral feeding of ZER significantly lowered the levels of IL-1beta [inhibitory rate (IR)=34%], TNF-alpha (IR=29%), and PGE(2) (IR=73%) and suppressed DSS-induced colitis, whereas NIM suppressed the histological changes induced by DSS without affecting inflammatory biomarkers. However, their treatment in combination was most effective for suppressing these biomarkers. Our results suggest that ZER is a novel food factor for mitigating experimental UC and that use of a combination of agents, with different modes of actions, may be an effective anti-inflammatory strategy.     

Novel anti-inflammatory actions of nobiletin,a citrus polymethoxy flavonoid,on human synovial fibroblasts and mouse macrophages

We previously reported that nobiletin (5,6,7,8,3',4'-hexamethoxy flavone), a citrus polymethoxy flavonoid, effectively interferes with the production of promatrix metalloproteinase (proMMP)-9/progelatinase B in rabbit synovial fibroblasts [J. Rheumatol. 27 (2000) 20]. In this paper, we further examine the effects of nobiletin on the production of cyclooxygenases (COXs), prostaglandin (PG) E(2), and proinflammatory cytokines in human synovial fibroblasts and the mouse macrophage J774A.1 cell line. Nobiletin suppressed the interleukin (IL)-1-induced production of PGE(2) in human synovial cells in a dose-dependent manner (<64 microM). Additionally, it selectively downregulated COX-2, but not COX-1 mRNA expression. Nobiletin also interfered with the lipopolysaccharide-induced production of PGE(2) and the gene expression of proinflammatory cytokines including IL-1alpha, IL-1beta, TNF-alpha and IL-6 in mouse J774A.1 macrophages. In addition, nobiletin downregulated the IL-1-induced gene expression and production of proMMP-1/procollagenase-1 and proMMP-3/prostromelysin-1 in human synovial fibroblasts. In contrast, production of the endogenous MMP inhibitor, TIMP-1, was augmented by nobiletin. These anti-inflammatory actions of nobiletin are very similar to those of anti-inflammatory steroids such as dexamethasone, and the upregulation of TIMP-1 production is a unique action of nobiletin. Therefore, these results further support the notion that nobiletin is likely to be a candidate for characterization as a novel immunomodulatory and anti-inflammatory drug.     

Infectivity enhanced, cyclooxygenase-2 promoter-based conditionally replicative adenovirus for pancreatic cancer

BACKGROUND AND AIMS: Pancreatic cancer is one of the most aggressive human malignancies. Conditionally replicative adenoviruses (CRAds) have shown some promise in the treatment of cancers. However, to date, their application for pancreatic cancer has met several obstacles: one is lack of a good control element to regulate replication, and the other is relatively low adenoviral infectivity. Thus, we constructed infectivity enhanced cyclooxygenase (COX)-2 promoter-based CRAds to develop a safe and effective therapeutic modality. METHODS: The CRAds were designed to achieve COX-2 promoter-controlled E1 expression for regulated replication (COX-2 CRAds). The infectivity-enhanced CRAds also have an RGD-4C motif in the adenoviral fiber-knob region. The selectivity and efficacy of these constructs were analyzed with cell lines in vitro. The in vivo therapeutic effect and viral replication were analyzed with a xenograft model. Pathology of the major organs and E1 RNA levels in the liver were also studied after systemic administration. RESULTS: The COX-2 CRAds showed a selective cytocidal effect in vitro in COX-2-positive cells and killed most of the pancreatic cancer cells. In vivo, intratumoral administration of the infectivity-enhanced COX-2 CRAds (10(9) particles) showed a strong antitumor effect comparable to wild-type virus, whereas the COX-2 CRAds without infectivity enhancement showed a limited effect. Viral replication was confirmed in the xenograft tumors. Systemic administration did not cause any detectable toxicity; the E1 RNA level in the liver after COX-2 CRAd administration was minimal. CONCLUSIONS: Infectivity-enhanced COX-2 CRAd is a promising agent for the treatment of pancreatic cancer.     

Cyclooxygenase-2 promotes angiogenesis in pTa/T1 urothelial bladder carcinoma but does not predict recurrence

OBJECTIVE: To investigate the effect of cyclooxygenase-2 (COX-2) on microvessel density (MVD) and on the clinical prognosis in patients with non-muscle invasive urothelial carcinoma of the bladder, as COX-2 expression is significantly greater in epithelial tumours and there is increasing evidence that COX-2 might contribute to tumour neovascularization. PATIENTS AND METHODS: We assessed tumour samples from 110 patients undergoing transurethral resection for primary pTa/pT1 bladder carcinoma (pTa, 84; pT1, 26; grade 1, 22; grade 2, 81; grade 3, seven). Paraffin sections were assessed immunohistochemically using antibodies against COX-2, CD34 (endothelial cells) and CD105 (proliferating vessels). COX-2 expression was quantified by the number of stained cells (negative, +, ++) and the MVD calculated as vessels per field. RESULTS: Of the 110 tumours, 45 (41%) had no immunostaining for COX-2, 40 had faint staining with at least isolated positive cells (+) and 25 stained ++. COX-2 positive tumours had significantly greater vascularization for proliferating vessels. In COX-2 negative tumours the MVD was 22.1, identified by CD34 immunostaining, and 3.4 for proliferating vessels (CD105), whereas COX-2 positive tumours had a MVD of 18.3 (CD34), and of 5.8, respectively (CD105). Complete follow-up data were available in 91 patients; after a mean follow-up of 25 months, 18 (20%) had tumour recurrences. There was no significant difference in the recurrence rates or disease-free survival between COX-2-positive (19%, 25.6 months) or -negative patients (21%, 25.2 months). CONCLUSION: These results confirm the involvement of COX-2 in angiogenesis in bladder cancer, as COX-2 promoted blood vessel proliferation in the tumour zone, and indicate the usefulness of COX-2-inhibiting drugs in preventing and treating superficial bladder cancer.     

Differential activation of subtype purinergic receptors modulates Ca(2+) mobilization and COX-2 in human microglia

We have studied modulation of purinergic receptors (P(2Y) and P(2X) subtypes) on changes in intracellular Ca(2+) [Ca(2+)](i) and expression and production of COX-2 in human microglia. Measurements using Ca(2+)-sensitive spectrofluorometry showed adenosine triphosphate (ATP) to cause rapid transient increases in [Ca(2+)](i). Application of ATP plus the P(2X) antagonist, pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), or treatment with adenosine diphosphate-beta-S (ADP-beta-S), a selective P(2Y) agonist, led to a considerable prolongation in [Ca(2+)](i) responses compared with ATP. The prolonged time courses were consistent with sustained activation of store-operated channels (SOC) since SKF96365, an inhibitor of SOC, blocked this component of the response. RT-PCR data showed that microglia expressed no COX-2 either constitutively or following treatment of cells with ATP (100 microM for 8 h). However, treatment using ATP plus PPADS or with ADP-beta-S led to marked expression of COX-2. The enhanced COX-2 with ATP plus PPADS treatment was absent in the presence of SKF96365 or using Ca(2+)-free solution. Immunocytochemistry, using a specific anti-COX-2 antibody, also revealed a pattern of purinergic modulation whereby lack of P(2X) activation enhanced the production of COX-2 protein. These results suggest that modulation of subtypes of purinergic receptors regulates COX-2 in human microglia with a link involving SOC-mediated influx of Ca(2+).     

Implication of cyclooxygenase-2 on enhanced proliferation of neural progenitor cells in the adult mouse hippocampus after ischemia

Global ischemia promotes neurogenesis in the dentate gyrus of the adult mouse hippocampus. Cyclooxygenase (COX)-2, the principal isoenzyme in the brain, modulates inflammation, glutamate-mediated cytotoxicity, and synaptic plasticity. We demonstrated that delayed treatment with different classes of COX inhibitor significantly blunted enhancement of dentate gyrus proliferation of neural progenitor cells after ischemia. COX-2 immunoreactivity was observed in both neurons and astrocytes in the dentate gyrus, but not in neural progenitor cells in the subgranular zone. Moreover, in the postischemic dentate gyrus of heterozygous and homozygous COX-2 knockout mice, proliferating bromodeoxyuridine-positive cells were significantly fewer than in wild-type littermates. These results demonstrate that COX-2 is an important modulator in enhancement of proliferation of neural progenitor cells after ischemia.