Cyclooxygenase-2 independent effects of cyclooxygenase-2 inhibitors on oxidative stress and intracellular glutathione content in normal and malignant human B-cells

We recently reported that inhibition of Cyclooxygenase-2 (Cox-2) reduced human B-CLL proliferation and survival. Herein, we investigated the mechanisms whereby small molecule Cox-2 selective inhibitors, SC-58125 (a Celebrex analog) and CAY10404 blunt survival of human B-cell lymphomas and chronic lymphocytic leukemia B-cells. SC-58125 and OSU03012 (a Celebrex analog that lacks Cox-2 inhibitory activity) both decreased intracellular glutathione (GSH) content in malignant human B-cells, as well as in Cox-2 deficient mouse B-cells. This new finding supports Cox-2 independent effects of SC-58125. Interestingly, SC-58125 also significantly increased B-cell reactive oxygen species (ROS) production, suggesting that ROS are a pathway that reduces malignant cell survival. Addition of GSH ethyl ester protected B lymphomas from the increased mitochondrial membrane permeability and reduced survival induced by SC-58125. Moreover, the SC-58125-mediated GSH depletion resulted in elevated steady-state levels of the glutamate cysteine ligase catalytic subunit mRNA and protein. These new findings of increased ROS and diminished GSH levels following SC-58125 exposure support novel mechanisms whereby a Cox-2 selective inhibitor reduces malignant B-cell survival. These observations also support the concept that certain Cox-2 selective inhibitors may have therapeutic value in combination with other drugs to kill malignant B lineage cells.

Conjugated linoleic acid reduces phorbol ester-induced prostaglandin F2alpha production by bovine endometrial cells

Recent interest in conjugated linoleic acid (CLA) research stems from the well-documented anticarcinogenic, antiatherogenic, antidiabetic, and antiobesity properties of CLA in animal models. The objective of this study was to examine the effects of 2 CLA isomers (cis-9,trans-11 and trans-10,cis-12) on phorbol 12,13-dibutyrate (PDBu)-induced PGF2alpha production in cultured bovine endometrial (BEND) cells. Confluent BEND cells were incubated in the absence (control) or presence of 100 microM each of linoleic acid, cis-9,trans-11 CLA, or trans-10,cis-12 CLA for 24 h. After incubation, cells were rinsed and then stimulated with PDBu (100 ng/mL) for 6 h. Compared with untreated cells, PDBu stimulated PGF2alpha secretion (+25-fold) within 6 h. The increases in PGF(2alpha) secretion were paralleled by signifi-cant induction of prostaglandin endoperoxide synthase-2 (PGHS-2) mRNA (+63-fold) and protein (+1.6-fold) expression. In spite of stimulatory effects on PGHS-2 and peroxisome proliferator-activated receptor delta (PPARdelta) mRNA responses, CLA greatly decreased PGF2alpha production by PDBu-stimulated BEND cells. There was no evidence for PDBu or CLA modulation of PPARdelta protein synthesis in cultured BEND cells. Results indicated that CLA modulation of PGF2alpha production by BEND cells was not mediated through PGHS-2 or PPARdelta gene repression.

Suppression of lipopolysaccharide-induced of inducible nitric oxide synthase and cyclooxygenase-2 by Sanguis Draconis, a dragon's blood resin, in RAW 264.7 cells

Sanguis Draconis (SD) is a kind of dragon's blood resin that is obtained from Daemomorops draco (Palmae). It is used in traditional medicine and has shown anti-inflammatory activity in some diseases. In this study, we examined the effects of Sanguis Dranonis ethanol extract (SDEE) on LPS-induced inflammation using RAW 264.7 cells. Our data indicated that SDEE inhibits LPS-stimulated NO, PGE2, IL-1 beta and TNF-alpha release, and iNOS and COX-2 expression. Furthermore, SDEE suppressed the LPS-induced p65 expression of NF-kappa B, which was associated with the inhibition of I kappa B-alpha degradation. We also found that the expression of HO-1 was significantly increased in RAW 264.7 cells by SDEE. These results suggest among possibilities of anti-inflammation that SDEE inhibits the production of NO and PGE2 by the down-regulation of iNOS and COX-2 gene expression via the suppression of NF-kappaB (p65) activation. SDEE can induce HO-1 over-expression in macrophage cells, which indicates that it may possess antioxidant properties. This result means that SEDD its anti-inflammatory effects in macrophages may be through a novel mechanism that involves the action of HO-1. Thus, SD could provide a potential therapeutic approach for inflammation-associated disorders.

Differential effects of selective cyclooxygenase-2 inhibitors in inhibiting proliferation and induction of apoptosis in oral squamous cell carcinoma

Cyclooxygenase-2 (COX-2), an enzyme that catalyzes the synthesis of prostaglandins, is made inducible by various stimuli such as inflammation. Although COX-2 is commonly overexpressed in a variety of premalignant and malignant conditions including oral leukoplakia and squamous cell carcinoma, relatively little research has compared the effects of various COX-2 inhibitors (celecoxib, NS-398, nimesulide and meloxicam). Therefore, we investigated the effects of four different selective COX-2 inhibitors on the growth of KB cells, derived from oral squamous cell carcinoma (OSCC) and its mechanisms. Celecoxib and NS-398 strongly suppressed the proliferation of KB cells at 10-100 microM, whereas nimesulide and meloxicam are less potent proliferation inhibitors. Only celecoxib induced apoptosis of the KB cells, as detected on the basis of DNA fragmentation, caspase-3/7 activation and cleaved poly(ADP-ribose) polymerase (PARP) fragmentation. All four COX-2 inhibitors increased COX-2 protein expression but suppressed prostaglandin (PG) E2 production in the KB cells, suggesting that the pro-apoptotic effect of celecoxib was unrelated to the inhibition of COX-2. Mechanistically, a high level of p53 protein and a low level of multidrug-resistant protein 1 (MRP1) and breast cancer resistant protein (BCRP) mRNA in KB cells with celecoxib may explain the differential effect of these selective COX-2 inhibitors in KB cells. Taken together, celecoxib is a good therapeutic candidate for treating OSCC through the suppression of cell proliferation and the induction of apoptosis in a COX-2 independent manner.

Antiproliferative and proapoptotic effects of rapamycin and celecoxib in malignant melanoma cell lines

Inhibitors of cyclooxygenase 2 (COX 2) and the mammalian target of rapamycin (mTOR) show direct and indirect antitumor effects in a variety of cancers. This study was designed to investigate the effects of the mTOR antagonist rapamycin and the COX 2 inhibitor celecoxib on cell growth and apoptosis in malignant melanoma. Cell proliferation was analysed by the cell proliferation ELISA BrdU and alamarBlue assay and apoptosis was measured by caspase 3 and 7 activity in two out of six melanoma cell lines (A375 and Mel Ho) that were selected for the heterogeneous levels of the COX 2 mRNA expression. The quantitative real-time reverse transcription polymerase chain reaction showed a 337-fold higher COX 2 mRNA level in the A375 than in the Mel Ho melanoma cells. However, both celecoxib and rapamycin caused significant growth inhibition in the two cell lines. By combining both agents, additive growth inhibitory effects were observed in the A375 cells. Treatment with celecoxib, but not rapamycin, increased apoptosis in the two cell lines. Our data indicate that rapamycin and celecoxib inhibit melanoma cell growth as single agents and a combination of both drugs have additive antitumor effects. Notably, the antiproliferative and proapoptotic effects of celecoxib seem to be independent of the COX 2 expression. Both rapamycin and celecoxib represent promising drugs for the palliative therapy of metastasised malignant melanoma and should be considered for future trials.

Piper cubeba demonstrates anti-estrogenic and anti-inflammatory properties

This present study aims to investigate if P9605, an ethanolic extract of PIPER CUBEBA L, exhibits anti-estrogenic and anti-inflammatory properties. We found that P9605 significantly inhibited growth induced by beta-estradiol in MCF-7, a human breast cancer cell line. It inhibited aromatase activity, which is responsible for transforming androgens into estrogens. Competitive binding assays also indicated P9605 binding to both human recombinant estrogen a and beta receptors. Furthermore, this extract inhibited the activities of cyclo-oxygenases (COX-1 and COX-2) and 5-lipo-oxygenase (5-LOX), also it attenuated the induction of interleukin 6 (IL-6) in differentiated THP-1 cells stimulated by lipopolysaccharide (LPS). Taken together with our previous results, P9605 possesses anti-androgenic, anti-estrogenic and anti-inflammatory properties. These results support the potential use of P9605 in phytotherapy against benign prostatic hyperplasia (BPH).

The protective role of Kangen-karyu against fructose-induced metabolic syndrome in a rat model

The protective effect of Kangen-karyu extract and its mechanisms against fructose-induced metabolic syndrome have been investigated using a rat model. Male Wistar rats were fed a high fructose (65%) diet or standard chow for one week, and for two subsequent weeks were treated with 50 or 100 mg kg(-1) body weight/day Kangen-karyu extract or vehicle. Serum glucose, glycosylated protein, triglyceride (TG), total cholesterol, and blood pressure levels of high-fructose-fed rats were increased compared with those of normal rats. However, Kangen-karyu extract ameliorated the high-fructose-induced metabolic syndrome including hyperglycaemia and hypertriglyceridaemia. In addition, the increase of hepatic TG content in rats given the high fructose diet was significantly inhibited with the regulation of sterol regulatory element-binding protein (SREBP)-1 expression by Kangen-karyu extract. On the other hand, peroxisome proliferator-activated receptor alpha and SREBP-2 protein levels were not affected by the feeding of the high fructose diet or Kangen-karyu extract. Moreover, Kangen-karyu extract administration to high-fructose-fed rats markedly reduced the thiobarbituric acid-reactive substance levels in serum, hepatic homogenate, and mitochondria. Furthermore, it inhibited the increase of cyclooxygenase (COX)-2 with the regulation of nuclear factorkappa B (NF-kappaB) and bcl-2 proteins in the liver, suggesting that the protective potential of Kangenkaryu extract against metabolic syndrome would be attributed to the regulation of COX-2, NF-kappaB, and bcl-2 signalling pathways. This study indicated that Kangen-karyu extract significantly improved high-fructose-induced metabolic syndrome such as hyperglycaemia, hyperlipidaemia, and hypertension through the reductions of TG and cholesterol contents with the regulation of hepatic SREBP-1 protein and the NF-kappaB signalling pathway.

Antiinflammatory effects of Bu-zhong-yi-qi-tang in patients with perennial allergic rhinitis

Bu-zhong-yi-qi-tang, an ancient formula of Chinese medicine usually used in the treatment of allergic diseases, was evaluated in the treatment of patients with perennial allergic rhinitis. In this study, 60 patients allergic to house dust mite allergen confirmed by skin test and MAST test were recruited and randomized. An experimental group of 36 patients was treated with Bu-zhong-yi-qi-tang, whereas a control group of 24 patients was treated with a non-effective formula Ping-wei-san for 3 months. The nasal symptomatic scores and the responses of polymorphonuclear neutrophils (PMN) to IL-4-stimulation were measured after treatment. The nasal symptomatic scores in the experimental group were significantly improved (3.78+/-0.09 before treatment vs. 0.57+/-0.06 after treatment). In contrast, no change was found in symptomatic scores in the control group (3.17+/-0.12 before treatment vs. 2.79+/-0.14 after treatment). Moreover, total serum IgE and the IL-4-stimulated production of PGE(2) and LTC(4) by PMN was significantly suppressed in the experimental group after treatment compared to the control group. The COX-2 mRNA expression in IL-4-stimulated PMN was also significantly suppressed after Bu-zhong-yi-qi-tang treatment. These results suggest that Bu-zhong-yi-qi-tang but not Ping-wei-san was beneficial to the patients with perennial allergic rhinitis via suppressed nasal inflammation by an antiinflammatory effect.

Dynamic compression influences interleukin-1beta-induced nitric oxide and prostaglandin E2 release by articular chondrocytes via alterations in iNOS and COX-2 expression

Interleukin-1beta (IL-1beta) induces the release of nitric oxide (.NO) and prostaglandin E2 (PGE2) by chondrocytes and this effect can be reversed with the application of dynamic compression. Previous studies have indicated that integrins may play a role. In addition, IL-1beta upregulates the expression of iNOS and COX-2 mRNA via upstream activation of p38 MAPK. The current study examines the involvement of these pathways in mediating .NO and PGE2 release in IL-1beta stimulated bovine chondrocytes subjected to dynamic compression. Bovine chondrocytes were seeded in agarose constructs and cultured with 0 or 10 ng.ml(-1) IL-1beta with or without the application of 15% dynamic compressive strain at 1 Hz. Selected inhibitors were used to interrogate the role of alpha5beta1 integrin signalling and p38 MAPK activation in mediating the release of .NO and PGE2 in response to both IL-1beta and dynamic compression. The relative expression levels of iNOS and COX-2 were assessed using real-time quantitative PCR. Nitrite, a stable end product of .NO, was measured using the Griess assay and PGE2 release was measured using an enzyme immunoassay. IL-1beta enhanced .NO and PGE2 release and this effect was reversed by the application of dynamic compression. Co-incubation with an integrin binding peptide (GRGDSP) abolished the compression-induced effect. Real-time quantitative PCR analysis revealed that IL-1beta enhanced iNOS and COX-2 mRNA levels, with the maximum expression at 6 or 12 hours. Dynamic compression reduced this effect via a p38 MAPK sensitive pathway. These results suggest that dynamic compression acts to abrogate of .NO and PGE2 release by directly influencing the expression levels of iNOS and COX-2.

Targeting cyclooxygenase-2 in hematological malignancies: rationale and promise

There is much interest in the potential use of Cox-2 selective inhibitors in combination with other cancer therapeutics. Malignancies of hematopoietic and non-hematopoietic origin often have increased expression of cyclooxygenase-2 (Cox-2), a key modulator of inflammation. For example, hematological malignancies such as chronic lymphocytic leukemia, chronic myeloid leukemia, Hodgkin's lymphoma, non-Hodgkin's lymphoma and multiple myeloma often highly express Cox-2, which correlates with poor patient prognosis. Expression of Cox-2 enhances survival and proliferation of malignant cells, while negatively influencing anti-tumor immunity. Hematological malignancies expressing elevated levels of Cox-2 potentially avoid immune responses by producing factors that enhance angiogenesis and metastasis. Cellular immune responses regulated by natural killer cells, cytotoxic T lymphocytes, and T regulatory cells are also influenced by Cox-2 expression. Therefore, Cox-2 selective inhibitors have promising therapeutic potential in patients suffering from certain hematological malignancies.

Hepatocyte growth factor induces anoikis resistance by up-regulation of cyclooxygenase-2 expression in uterine endometrial cancer cells

Cyclooxygenase-2 (COX-2) has been implicated in the promotion of carcinogenesis. Although the role of COX-2 in endometrial cancer remains unclear, recent experiments suggest that COX-2 antagonizes cell apoptosis, increases the invasiveness of malignant cells, and promotes angiogenesis. Hepatocyte growth factor (HGF) is a mesenchymal-derived cytokine and the interaction between HGF and its tyrosine kinase receptor, c-Met proto-oncogene, is associated with tumor progression and metastasis. To investigate the molecular mechanism of HGF-induced anoikis resistance, we analyzed the signal transduction and COX-2 expression in endometrial cancer cells. Here, we show i) the expression of COX-2 protein significantly increased in a dose-dependent manner after HGF stimulation in endometrial cancer cell lines (HEC-IB and RL95-2), reaching 200-270% stimulation at the highest doses of HGF tested (40 ng/ml); ii) flow cytometry and TUNEL analyses revealed that HGF significantly inhibited anoikis of RL95-2 cells; iii) phosphatidylinositol 3-kinase (PI3K) inhibitor (LY294002), but not mitogen-activated protein kinase/ERK kinase (MEK) inhibitor (PD98059), specifically blocked HGF-mediated anoikis resistance in RL95-2 cells; and iv) COX-2 inhibitor, Meloxicam, abrogated HGF-mediated anoikis resistance. Our data suggest that HGF induces anoikis resistance in endometrial cancer cells possibly through PI3K/Akt pathway-dependent up-regulation of COX-2 expression.

Vasoactive intestinal peptide inhibits cyclooxygenase-2 expression in activated macrophages, microglia, and dendritic cells

Prostaglandin E2 (PGE2) is a potent lipid mediator produced by the inducible form of the enzyme cyclooxygenase (COX-2) in inflammatory cells. PGE2 and COX-2 are critical mediators in the pathogenesis of several inflammatory and degenerative diseases, and have therefore emerged as therapeutic targets for the treatment of such disorders. Vasoactive intestinal peptide (VIP) is a well-known anti-inflammatory neuropeptide that protects against several immune disorders by regulating a wide panel of inflammatory mediators. In this work we show the inhibitory effect of VIP on COX-2 expression and subsequent production of PGE2 by macrophages, dendritic cells, and microglia activated with different inflammatory stimuli. This inhibitory effect is exerted at the transcriptional level and mediated through the VIP receptor VPAC1. VIP downregulates NFkappaB-dependent gene activation of the COX-2 promoter. These findings demonstrate a novel property of VIP that might contribute to their anti-inflammatory effects in vivo, i.e., the inhibition of the inducible COX-2/PGE2 system.

Effect of altering dietary omega-6/omega-3 fatty acid ratios on prostate cancer membrane composition, cyclooxygenase-2, and prostaglandin E2

PURPOSE

To determine whether altering the dietary content of omega-6 (n-6) and omega-3 (n-3) polyunsaturated fatty acids affects the growth of androgen-sensitive prostate cancer xenografts, tumor membrane fatty acid composition, and tumor cyclooxygenase-2 and prostaglandin E(2) (PGE(2)) levels.

EXPERIMENTAL DESIGN

Individually caged male severe combined immunodeficiency mice were fed isocaloric 20% kcal fat diets with the fat derived either primarily from n-6 fatty acids (n-6 group) or with the fat consisting of n-6 and n-3 fatty acids in a ratio of 1:1 (n-3 group), and injected s.c. with Los Angeles Prostate Cancer 4 (LAPC-4) cells. Tumor volumes and mouse weights were measured weekly, caloric intake was measured 3 days per week, and tumors and serum were harvested at 8 weeks postinjection.

RESULTS

Tumor growth rates, final tumor volumes, and serum prostate-specific antigen levels were reduced in the n-3 group relative to the n-6 group. The n-3 group tumors had decreased proliferation (Ki67 staining) and increased apoptosis (terminal nucleotidyl transferase-mediated nick end labeling staining). In vitro proliferation of LAPC-4 cells in medium containing n-3 group serum was reduced by 22% relative to LAPC-4 cells cultured in medium containing serum from the n-6 group. The n-6/n-3 fatty acid ratios in serum and tumor membranes were lower in the n-3 group relative to the n-6 group. In addition, n-3 group tumors had decreased cyclooxygenase-2 protein and mRNA levels, an 83% reduction in PGE(2) levels, and decreased vascular endothelial growth factor expression.

CONCLUSION

These results provide a sound basis for clinical trials evaluating the effect of dietary n-3 fatty acids from fish oil on tumor PGE(2) and membrane fatty acid composition, and serum and tumor biomarkers of progression in men with prostate cancer.

[What is new about nonsteroidal antiinflamatory drugs?]

NSAIDs contain nonselective cyclooksygenase inhibitors (for COX-1 and COX-2), inhibitors to the preferential COX-2, the coxibs (sulphonamides, methylsulphones, phenylacethic acid derivatives) with 1000 fold selectivities for COX-2. COX-2 enzyme isoform are constitutively expressed in normal gastric tissue in animals and humans, in the cardiovascular system, renal, central nervous system and other. COX-2 is involved in the ischemic preconditioning mechanism and sulphones have a prooxidant activity. COX-2 inhibitors increased risk for thrombotic cardiovascular events. Long-term study VIGOR, CLASS, TARGET MEDAL revealed that celecoxib, rofecoxib, lumiracoxib, etoricoxib significantly reduced the risk of major gastrointestinal effects (ulcers, perforations, bleeding) than nonselective NSAIDs, but the rates of complicated upper gastrointestinal events were similar for etoricoxib and diclofenac. Only in VIGOR trial incidence of cardiovascular events was greater. No evidence that concomitant ASA reduced risk for cardivascular events. Potential differences in cardiovascular outcomes with the selective COX-2 inhibitors may be due to differences in the drugs molecular structures, pharmacokinetics and pharmacodynamics. In the "prothrombotic environment" contribution disorders in the balance between thromboxan A2 and prostacyclin, increased aggregation plaque, hypertension, endothelial cell dysfunction, impaired angiogenesis. Moreover COX-2 may plays a crucial role in atherosclerotic plaque stability or instability. The cardiovascular risk may be dose related and depends on duration therapy, variable selectivity for COX-2.

COX-2 expression in cystic kidneys is dependent on dietary n-3 fatty acid composition☆

Dietary n-3 fatty acids generally attenuate elevated cyclooxygenase-2 (COX-2) levels in disease states. However, models of renal cystic disease (RCD) exhibit reduced renal COX-2 expression. Therefore, the in vivo regulation of COX-2 expression by dietary n-3 fatty acids was examined. In archived tissues from dietary studies, COX-2 protein and gene expression was up-regulated in diseased pcy mouse and Han:SPRD-cy rat kidneys when given diets containing eicosapentaenoic acid (EPA) and/or docosahexaenoic acid (DHA), but not those containing alpha-linolenic acid (ALA), compared to control diets with linoleic acid (LA). The presence of disease was necessary to elicit these effects as COX-2 expression was unaltered by diet in normal kidneys. The effects were specific for COX-2, since COX-1 levels were unaltered by these dietary manipulations in either model. Thus, in RCD, diets containing EPA and DHA but not ALA appear to specifically up-regulate renal COX-2 gene and protein levels in vivo.

Novel selective inhibitors of hydroxyxanthone derivatives for human cyclooxygenase-2

AIM

To screen the selective inhibitors for human cyclooxygenase-2 ((h)COX-2) utilizing molecular simulation.

METHODS

Eight xanthone derivatives, compounds A-H, were employed by the structure-based research methodology. Resveratrol and NS-398 were selected as the control compounds for COX-1 and COX-2, respectively. The docking results were scored and the interaction energies of the complexes were calculated by CHARMm forcefield.

RESULTS

NS-398 could not dock into the active site of COX-1. However, resveratrol, the specific selective compound for COX-1, gained lower interaction energy while docked in COX-1. The lower interaction energies were investigated, while compound B and F were docked into the catalytic sites of COX-1 and COX-2, respectively. Compound A, 1,3,6,7-tetrahydroxyxanthone, revealed high inhibitory potency to both COX-1 and COX-2.

CONCLUSION

The conformations of the docking would influence the values of interaction energies. The hydrogen bond could also increase the stability of the whole complex, which might suggest that compound B had a suitable conformation in the tunnel-like active site of COX-1. Compound F, a potent agent for COX-2, revealed a strong hydrogen bond with Ser516 in human COX-2 to form a stable complex.

NF-kappaB-inducing kinase regulates cyclooxygenase 2 gene expression in macrophages by phosphorylation of PU.1

Selective expression of cyclooxygenase 2 (COX-2) by macrophages could have an important role in the pathobiology of inflammation. We reported a functional synergism between PU.1 and other transcription factors that contributes to COX-2 gene expression in macrophages. PU.1 resides in the nuclear compartment and is activated by phosphorylation to bind to cognate DNA elements containing a 5'-GGAA/T-3' motif, but the involved kinase has not been discovered. We tested the hypothesis that NF-kappaB-inducing kinase (NIK) regulates COX-2 gene expression in macrophages through inducible phosphorylation of PU.1. Our initial experiments showed an in vitro protein-protein binding interaction between myc-NIK and GST-PU.1. Purified myc-NIK had a strong in vitro kinase activity for purified GST-PU.1, and this activity and production of COX-2 protein is blocked by treatment with a nonspecific kinase inhibitor, 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole. We used short interfering RNA to develop a stable NIK knockdown macrophage cell line that had an approximately 50% decrease in COX-2 protein production and decreased generation of PGD(2), and this was correlated with decreased binding of activated PU.1 to the COX-2 promoter in response to treatment with endotoxin. These findings suggest a novel role for NIK in mediating COX-2 gene expression in endotoxin-treated macrophages by a mechanism that involves phosphorylation of PU.1.

Targeting NOX, INOS and COX-2 in inflammatory cells: chemoprevention using food phytochemicals

Biological, biochemical and physical stimuli activate inflammatory leukocytes, such as macrophages, resulting in induction and synthesis of proinflammatory proteins and enzymes, together with free radicals, as innate immune responses. On the other hand, chronic and dysregulated activation of some inducible enzymes, including NADPH oxidase (NOX), inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2, have been shown to play pivotal roles in the development of certain inflammatory diseases such as oncogenesis. While the use of synthetic agents, especially those targeting molecules, is an attractive and reasonable approach to prevent carcinogenesis, it should be noted that traditional herbs and spices also exist along with their active constituents, which have been demonstrated to disrupt inflammatory signal transduction pathways. In this mini-review, the molecular mechanisms of activation or induction of NOX, iNOS and COX-2, as well as some food phytochemicals with marked potential to regulate those key inflammatory molecules, are highlighted. For example, 1'-acetoxychavicol acetate, which occurs in the rhizomes of the subtropical Zingiberaceae plant, has been shown to attenuate NOX-derived superoxide generation in macrophages, as well as lipopolysaccharide-induced nitric oxide and prostaglandin E(2) production through the suppression of iNOS and COX-2 synthesis, respectively. Notably, this phytochemical has exhibited a wide range of cancer prevention activities in several rodent models of inflammation-associated carcinogenesis. Herein, the cancer preventive potentials of several food phytochemicals targeting the induction of NOX, iNOS and COX-2 are described.

Curcumin augments gemcitabine cytotoxic effect on pancreatic adenocarcinoma cell lines

BACKGROUND AND AIM

Gemcitabine, the first-line agent in pancreatic adenocarcinoma, has shown limited clinical benefit. Cyclooxygenase-2 (COX-2) represent one of the most promising targets for cancer prevention and treatment. In this study, we investigated whether the phytochemical curcumin, a natural COX-2 inhibitor, can potentiate gemcitabine effect on survival of human pancreatic cancer cells.

METHODS

P34 (high COX-2 expression) and Panc-1 (low COX-2 expression) pancreatic cancer cell lines were exposed to different concentrations of gemcitabine (0.1-10 microM), curcumin (0-50 microM), and their combination. Cell viability was evaluated by XTT assay. Cell cycle and apoptosis were assessed by flow cytometry. COX-2, EGFR, and p-ERK1/2 expression was measured by Western blot analysis.

RESULTS

Curcumin increased the inhibitory effect of gemcitabine on cell viability as well as its pro-apoptotic effect in COX-2 positive, p34 cells, but not in COX-2 negative, Panc-1 cells. In p34 cells, combination of curcumin and gemcitabine downregulated both COX-2 and p-ERK1/2 in a dose-dependent manner.

CONCLUSION

The increased cytotoxic effect of the combination on cell survival and on the induction of apoptosis in COX-2 expressing pancreatic cancer cells is probably associated with downregulation of COX-2 and p-ERK1/2 levels. This finding may contribute to the development of an effective treatment of pancreatic adenocarcinoma.

Prostacyclin, atherothrombosis, and cardiovascular disease

Prostacyclin (PGI(2)) is a major product of COX-2 catalyzed metabolism of arachidonic acid in the endothelium. Recent studies have demonstrated that PGI(2) protects against atherothrombosis. The prostacyclin receptor knockout mice exhibit increased atherosclerosis, enhanced thrombosis, and enhanced proliferative response to carotid vascular injury with increased intima to media ratios [1-3]. Moreover, the recent withdrawal of rofecoxib (Vioxx) due to increased cardiovascular events further supports the critical role of prostacyclin in inhibiting atherothrombosis in humans. Such studies have paralleled intense chemical biology studies to develop more stable prostacyclin analogues. Indeed a number of these analogues are currently being successfully used for the treatment of pulmonary hypertension. In this review we will summarize the current literature on some principles of prostacyclin analogue development, our current understanding of the receptor, and recent developments which implicate prostacyclin in atherothrombotic protection. More than 68 million Americans suffer from cardiovascular disease, which causes more deaths, disability and economic loss than any other group of diseases. Further clinical investigations of orally stable prostacyclin analogues for treatment of cardiovascular diseases other than pulmonary hypertension may now be warranted.

Suppression of IL-1β-induced COX-2 expression by trichostatin A (TSA) in human endometrial stromal cells

OBJECTIVE

Over-production of cyclooxygenase-2 (COX-2) plays an important role in the positive feedback loop that leads to proliferation and inflammation in endometriosis. Following our observation that histone deacetylase inhibitors (HDACIs) trichostatin A (TSA) and valproic acid (VPA) can suppress proliferation of endometrial stromal cells, we sought to determine whether TSA suppresses IL-1beta-induced COX-2 expression in endometrial stromal cells.

STUDY DESIGN

In vitro study using a recently established immortalized endometrial stromal cell line. The stromal cells were pretreated with TSA before stimulation with IL-1beta, and COX-2 gene and protein expression was measured by real-time quantitative RT-PCR and Western blot analysis, respectively.

RESULTS

IL-1beta stimulated COX-2 expression in a concentration-dependent manner in endometrial stromal cells. The induced COX-2 gene and protein expression were suppressed by TSA pretreatment.

CONCLUSIONS

TSA suppresses IL-1beta-induced COX-2 gene and protein expression in endometrial stromal cells. This finding, coupled with the findings that TSA and another HDACI, valproic acid, suppress proliferation and induce cell cycle arrest, suggests that HDACIs are a promising class of compound that has therapeutic potential for endometriosis.

Eugenol Modulates Cyclooxygenase-2 Expression Through the Activation of Nuclear Factor Kappa B in Human Osteoblasts

Because eugenol is a major component of root canal sealers and retrograde filling materials, its effects on periapical bone healing are therefore of concern. In this study, the effects of eugenol on the activation of nuclear factor kappa B (NF-kappaB) and the expression of cyclooxygenase-2 (COX-2) in human osteoblasts were investigated. The results showed that eugenol activated the nuclear translocation of NF-kappaB. In addition, COX-2 protein expression in osteoblasts was induced by eugenol in a dose-dependent manner. Furthermore, the eugenol-modulated COX-2 expression was inhibited by an NF-kappaB inhibitor, N-acetylcysteine. Taken together, eugenol might induce COX-2 expression through the activation of NF-kappaB in human osteoblasts. These results suggest that eugenol might be involved in periapical healing by impairing the functions of osteoblasts.

Temporospatial patterns of COX-2 expression and pyramidal cell degeneration in the rat hippocampus after trimethyltin administration

The temporospatial profile of cyclooxygenase-2 (COX-2) expression and neuronal degeneration following trimethyltin (TMT) administration was investigated in the rat hippocampus region. In the CA1 region, significant COX-2 expression was detected on day 3 after TMT administration but pyramidal cell degeneration was detected only on day 5 and thereafter. In the CA3 region, on the other hand, the constitutive COX-2 expression remained unchanged, and more severe pyramidal cell degeneration started on day 3. Concomitant with these observations, we observed that the coadministration of a COX-2 inhibitor prevented such neuronal degeneration only in the CA1 region and not in the CA3 region. In addition, COX-2 inhibition did not affect the increase in the plasma corticosterone concentration after TMT administration. Furthermore, the COX-2 inhibitor did not alleviate TMT-induced locomotor hyperactivity in rats, for which inhibitors of corticosterone synthesis are known to be effective. These data suggest that the COX-2-dependent pathway appears to assist TMT-induced degeneration of CA1 pyramidal cells but not CA3 pyramidal cells in a corticosterone-independent manner.

MEK activation suppresses CPT11-induced apoptosis in rat intestinal epithelial cells through a COX-2-dependent mechanism

Resistance to chemotherapeutic agents is one of the distinct features of cancer cells. We evaluate the role of activated MEK-ERK signaling in Camptotecin/irinotecan (CPT-11)-induced cell death using constitutively activated MEK1-transfected normal rat intestinal epithelial cells (IEC-caMEK cells). A CPT-11-induced inhibitory concentration of 50% was determined by WST assay. Apoptosis was evaluated by DNA staining and fragmented DNA analysis. Protein expressions were analyzed by western blotting. We also examined the role of cyclooxygenase-2 in the cell systems. IEC-caMEK cells possessed survival advantages compared to control cells. Apoptosis was remarkably suppressed in IEC-caMEK cells. Western blot analysis revealed increased expression of Bcl-2, Bcl-xL, Mcl-1, and COX-2 and decreased expression of Bak in IEC-caMEK cells. The COX-2 selective inhibitor ameliorated the antiapoptotic nature of IEC-caMEK cells. MEK activation suppressed CPT-11-induced apoptosis in IEC-caMEK cells via a COX-2- dependent mechanism. Therefore, MEK-ERK signaling may contribute to the drug-resistant nature of cancer cells.