Profile of JTE-522 as a human cyclooxygenase-2 inhibitor

Investigation of the anti-inflammatory and analgesic activities of promising pyrazole derivative

The development of new COX-2 inhibitors with analgesic and anti-inflammatory efficacy as well as minimal gastrointestinal, renal and cardiovascular toxicity, is of vital importance to patients suffering from chronic course pain and inflammatory conditions. This study aims at evaluating the therapeutic activity and adverse drug reactions associated with the use of the newly synthesized pyrazole derivative, compound AD732, E-4-[3-(4-methylphenyl)-5-hydroxyliminomethyl-1H-pyrazol-1-yl]benzenesulfonamide, as compared to indomethacin and celecoxib as standard agents. Anti-inflammatory activity was assessed using carrageenan-induced rat paw edema and cotton pellet granuloma tests; formalin-induced hyperalgesia and hot plate tests were done to study analgesic activity. In vitro tests to determine COX-1/COX-2 selectivity and assessment of renal and gastric toxicity upon acute exposure to AD732 were also conducted. Compound AD732 exhibited promising results; higher anti-inflammatory and analgesic effects compared to standard agents, coupled with the absence of ulcerogenic effects and minimal detrimental effects on renal function. Additionally, compound AD732 was a less potent inhibitor of COX-2 in vitro than celecoxib, which may indicate lower potential cardiovascular toxicity. It may be concluded that compound AD732 appears to be a safer and more effective molecule with promising potential for the management of pain and inflammation.

AK106-001616, a Potent and Selective Inhibitor of Cytosolic Phospholipase A2: In Vivo Efficacy for Inflammation, Neuropathic Pain, and Pulmonary Fibrosis

3-[3-Amino-4-(indan-2-yloxy)-5-(1-methyl-1H-indazol-5-yl)-phenyl]-propionic acid (AK106-001616) is a novel, potent, and selective inhibitor of the cytosolic phospholipase A₂ (cPLA₂) enzyme. Unlike traditional nonsteroidal anti-inflammatory drugs and selective cyclooxygenase-2 inhibitors, AK106-001616 reduced prostaglandin E₂ (PGE₂) and leukotriene B₄ (LTB₄) production by stimulated cells. The suppression of PGE₂ and LTB₄ production was also confirmed using an air pouch model in rats administered a single oral dose of AK106-001616. AK106-001616 alleviated paw swelling in a rat adjuvant-induced arthritis (AIA) model. The maximum effect of the inhibitory effect of AK106-001616 was comparable with that of naproxen on paw swelling in a rat AIA model. Meanwhile, the inhibitory effect of AK106-001616 was more effective than that of naproxen in the mouse collagen antibody-induced arthritis model with leukotrienes contributing to the pathogenesis. AK106-001616 dose dependently reversed the decrease in paw withdrawal threshold not only in rat carrageenan-induced hyperalgesia, but also in a rat neuropathic pain model induced by sciatic nerve chronic constriction injury (CCI). However, naproxen and celecoxib did not reverse the decrease in the paw withdrawal threshold in the CCI model. Furthermore, AK106-001616 reduced the disease score of bleomycin-induced lung fibrosis in rats. In addition, AK106-001616 did not enhance aspirin-induced gastric damage in fasted rats, increase blood pressure, or increase the thromboxane A₂/ prostaglandin I₂ ratio that is thought to be an underlying mechanism of thrombotic cardiovascular events increased by selective cyclooxygenase-2 inhibitors. Taken together, these data demonstrate that oral AK106-001616 may provide valuable effects for wide indications without attendant gastrointestinal and cardiovascular risks.

Discovery of new indomethacin-based analogs with potentially selective cyclooxygenase-2 inhibition and observed diminishing to PGE2 activities

New ring-extended analogs of indomethacin were designed based on the structure of active binding site of both COX-1 and COX-2 isoenzymes and the interaction pattern required for selective inhibition of COX-2 to improve its selectivity against COX-2. The strategy adopted for designing the new inhibitors involved i) ring extension of indomethacin to reduce the possibility of analogs to be accommodated into the narrow hydrophobic tunnel of COX-1, ii) deletion of carboxylic acid to reduce the possibility of inhibitor to form salt bridge with Arg120 and eventually prevent COX-1 inhibition, and iii) introduction of methylsulfonyl group to increase the opportunity of the analogs to interact with the polar side pocket that's is crucial for inhibition process of COX-2. The three series of tetrahydrocarbazoles involving 4, 5, 9, 10 and 12 were synthesized in quantitative yields adopting limited number of reaction steps, and applying laboratory friendly reaction conditions. In vitro and in vivo assays for data profiling the new candidates revealed the significant improvement in the potency and selectivity against COX-2 of 6-methoxytetrahydrocarbazole 4 (IC₅₀ = 0.97 μmol) to verify the effect of ring extension in comparison to indomethacin (IC₅₀ = 2.63 μmol), and 6-methylsulfonyltetrahydrocarbazole 10a (IC₅₀ = 0.28 μmol) to verify the effect of ring extension and introduction of methylsulfonyl group. 9-(4-chlorobenzoyl)-6-(methylsulfonyl)-1,2,3,9-tetrahydro-4H-carbazol-4-one 12a showed the most potential and selective activity against COX-2 (IC₅₀ = 0.23 μmol) to be with superior potency to Celecoxib (IC₅₀ = 0.30 μmol). Consistently, 12a was the most active with all the other anti-inflammatory test descriptors and its activity in diminishing the PGE2 with the other analogs confirmed the elaboration of new class of selective COX-2 inhibitors beyond the diarylsulfonamides as a previously common class of selective COX-2 inhibitors. Molecular docking study revealed the high binding score of compound 12a (-30.78 kcal/mol), with less clash contribution (7.2) that is close to indomethacin. Also, 12a showed low conformation entropy score (1.40). Molecular dynamic (MD) simulation identified the equilibrium of both potential and kinetic energies.

Synthesis, evaluation and modeling of some triazolothienopyrimidinones as anti-inflammatory and antimicrobial agents

AIM

New triazolotetrahydrobenzothienopyrimidinone derivatives were synthesized.

EXPERIMENTAL

Their structures were confirmed, and their anti-inflammatory, antimicrobial activities and ulcerogenic potentials were evaluated.

RESULTS

Compounds 7a, 10a and 11a showed minimal ulcerogenic effect and high selectivity toward human recombinant COX-2 over COX-1 enzyme with IC₅₀ values of 1.39, 1.22 and 0.56 μM, respectively. Their docking outcome correlated with their biological activity and confirmed the high selectivity binding toward COX-2. Compound 12b displayed antimicrobial activity comparable to that of ampicillin against Escherichia coli while compounds 6 and 11c were similar to ampicillin against Staphylococcus aureus. In addition, compounds 7a, 9a, 10b and 11c showed dual anti-inflammatory/antimicrobial activities.

CONCLUSION

This work represents a promising matrix for developing new potential anti-inflammatory, antimicrobial and dual antimicrobial/anti-inflammatory candidates. [Formula: see text].

Cyclooxygenase-2 inhibitors: a literature and patent review (2009 - 2010)

INTRODUCTION

COXs catalyze the complex conversion of arachidonic acid to prostaglandins and thromboxanes, which trigger as autacoids with autocrine and paracrine biological effects many physiological and pathophysiological responses. The structural similarities of the COX-1 and -2 enzymes make the search for selective inhibitors for COX-2 versus -1 a formidable challenge.

AREAS COVERED

The present review provides a survey of the development of novel COX-2 inhibitors covering literature and patents between 2009 and 2010. The presence of a central, typically 1,2-diaryl substituted, heterocycle or carbocycle as a characteristic structural motif in many selective COX-2 inhibitors represents the basis of their classification in this review. The classification in this review includes COX-2 inhibitors based on five- and six-membered heterocycles, benzoheterocycles (e.g., benzopyrans, benzopyranones, indoles and quinolines), quinones, chalcones, natural products and miscellaneous. When available, COX-2 inhibitors are presented with their related COX-2 inhibitory potency and selectivity.

EXPERT OPINION

The availability of detailed information on the crystal structure of the COX-2 enzyme with various substrates, cofactors and inhibitors, and the recently reported increased risk of cardiovascular events associated with selective COX-2 inhibitors will further stimulate development of COX-2 inhibitors with favorable COX-2 inhibition profiles without adverse effects to the cardiovascular system.

A novel COX-2 inhibitor pyrazole derivative proven effective as an anti-inflammatory and analgesic drug

The introduction of new COX-2 inhibitors with high efficacy and enhanced safety profile would be a great achievement in the development of anti-inflammatory drugs. This study was designed to screen and assess the anti-inflammatory and analgesic activities as well as some of the expected side effects of some pyrazole derivatives, newly synthesized as potential COX-2 inhibitors at the Faculty of Pharmacy, Alexandria University and compared to indomethacin and celecoxib. Twelve compounds were screened for their anti-inflammatory activity using carrageenan-induced paw oedema and cotton pellet granuloma tests. On the basis of their apparent anti-inflammatory activity, four compounds with different substitutions were selected for the evaluation of their analgesic activity using the formalin-induced hyperalgesia and hot-plate tests. Compound AD 532, ((4-(3-(4-Methylphenyl)-4-cyano-1H-pyrazol-1-yl)benzenesulfonamide)), showed very promising results. In the single-dose and subchronic toxicity studies, compound AD 532 showed no ulcerogenic effect and produced minimal effects on renal function. Furthermore, compound AD 532 was a less potent inhibitor of COX-2 in vitro than celecoxib, which may indicate lower potential cardiovascular toxicity. It is concluded that compound AD 532 appears to be a promising and safe option for the management of chronic inflammatory conditions. This study recommends more in-depth investigation into the therapeutic effects and toxicity profile of this compound including its cardiovascular toxicity.

Synthesis of some pyrazolyl benzenesulfonamide derivatives as dual anti-inflammatory antimicrobial agents

Four series of pyrazolylbenzenesulfonamide derivatives were synthesized and evaluated for their anti-inflammatory activity using cotton pellet induced granuloma and carrageenan-induced rat paw edema bioassays. Moreover, COX-1 and COX-2 inhibitory activity, ulcerogenic effect and acute toxicity were also determined. Furthermore, the target compounds were screened for their in-vitro antimicrobial activity against Eischerichia coli, Staphylococcus aureus and Candida albicans. Compounds 4-(3-Phenyl-4-cyano-1H-pyrazol-1-yl)benzenesulfonamide 9a and 4-(3-Tolyl-4-cyano-1H-pyrazol-1-yl)benzenesulfonamide 9b were not only found to be the most active dual anti-inflammatory antimicrobial agents in the present study with good safety margin and minimal ulcerogenic effect but also exhibited good selective inhibitory activity towards COX-2. A docking pose for 9a and 9b separately in the active site of the human COX-2 enzyme was also obtained. Therefore, these compounds would represent a fruitful matrix for the development of dual anti-inflammatory antimicrobial candidates with remarkable COX-2 selectivity.

Structure-based pharmacophore of COX-2 selective inhibitors and identification of original lead compounds from 3D database searching method

A four-point pharmacophore of COX-2 selective inhibitors was derived from a training set of 16 compounds, using the Catalyst program. It consists of a H bond acceptor, two hydrophobic groups and an aromatic ring, in accordance with SAR data of the compounds and with topology of the COX-2 active site. This hypothesis, combined with exclusion volume spheres representing important residues of the COX-2 binding site, was used to virtually screen the Maybridge database. Eight compounds were selected for an in vitro enzymatic assay. Five of them show COX-2 inhibition close to that of nimesulide and rofecoxib, two reference COX-2 selective inhibitors. As a result, structure-based pharmacophore generation was able to identify original lead compounds, inhibiting the COX-2 isoform.

Recruitment of a prostaglandin E receptor subtype, EP3-expressing bone marrow cells is crucial in wound-induced angiogenesis

E-type prostaglandins have been reported to be proangiogenic in vivo. Thus, we examined prostaglandin receptor signaling relevant to wound-induced angiogenesis. Full-thickness skin wounds were created on the backs of mice, and angiogenesis in wound granulation tissues was estimated. Wound closure and re-epithelization in EP3 receptor knockout mice (EP3-/-) were significantly delayed compared with their wild-type (WT) mice, whereas those in EP1-/-, EP2-/-, and EP4-/- were not delayed. Wound-induced angiogenesis estimated with CD31 immunohistochemistry in EP3-/- mice was significantly inhibited compared with that in WT mice. Immunoreactive vascular endothelial growth factor (VEGF) in wound granulation tissues in EP3-/- mice was markedly less than that in WT mice. Wound closure in WT mice was delayed significantly by VEGF neutralizing antibody compared with control IgG. Wound-induced angiogenesis and wound closure were significantly suppressed in EP3-/- bone marrow transplantation mice compared with those in WT bone marrow transplantation mice. These were accompanied with the reductions in accumulation of VEGF-expressing cells in wound granulation tissues and in mobilization of VEGF receptor 1-expressing leukocytes in peripheral circulation. These results indicate that the recruitment of EP3-expressing cells to wound granulation tissues is critical for surgical wound healing and angiogenesis via up-regulation of VEGF.

Does a selective cyclooxygenase-2 inhibitor (tiracoxib) induce clinically sufficient suppression of adenomas in patients with familial adenomatous polyposis? A randomized double-blind placebo-controlled clinical trial

BACKGROUND

There have been few placebo-controlled randomized double-blind studies of the clinical effects of selective cyclooxygenase-2 (COX-2) inhibitors on the regression of colorectal tumors. This study was designed to examine the regressive effect of a selective COX-2 inhibitor, tiracoxib (JTE-522), on colorectal polyps in patients with familial adenomatous polyposis (FAP), and its safety.

METHODS

Sixty-one patients with FAP diagnosed by Japanese criteria were assigned randomly to receive placebo or JTE-522, at either 150 mg or 200 mg, once daily orally for 26 weeks. Prior to and at the end of the medication period, endoscopy was performed. Adenomas located near an india-ink tattoo injected at the first colonoscopy were identified and measured. The response variables were the percent changes from the baseline in polyp numbers and in specified polyp diameters. Any adverse events that appeared in at least four persons were taken into consideration and compared between the JTE-522 treatment groups and the placebo group.

RESULTS

No change in polyp number (median, 0) was observed in any of the three groups. There were no differences between the placebo group and the two treatment groups in the change in polyp size. JTE-522 was well tolerated.

CONCLUSION

Our findings, in keeping with other reports on COX-2 inhibitors, indicated that the inhibition of a COX-2 with a moderate dose of a selective COX-2 inhibitor did not induce clinically sufficient regression of adenomas in patients with FAP in a limited (6-month) medication period.

Bile Acid Promotes the Proliferation of Squamous Cell Carcinoma of the Esophagus, Independent of its Inducing COX-2 Expression

BACKGROUND

We have reported G1 progression and cyclooxygenase-2 (COX-2) induction during carcinogenesis of the squamous epithelium of the esophagus. As bile acid induces COX-2 expression and promotes carcinogenesis in the digestive tract, we investigated the effect of bile acid on the proliferation of squamous cell carcinoma of the esophagus (ESCC).

MATERIALS AND METHODS

MTT assay, Western blot analysis of COX-2 and cell cycle-related molecules in the G1 phase (Rb, CDC25A, cyclin D1), and CDK2 kinase assay were performed on chenodeoxycholic acid (CDCA) exposure to ESCC cell lines (TE2R, TE3, TE13, TE15).

RESULTS

In the presence of gradient bile acid concentration (up to 100 microm), growth of ESCC cell lines was stimulated at a low concentration (maximally at 20-30 microm), but suppressed at a higher concentration. Only a low dose of bile acid induced the expression of cyclin D1 and CDC25A and showed high Rb phosphorylation and high CDK2 kinase activity. In contrast, bile acid progressively induced COX-2 expression in a dose-dependent manner, regardless of its biphasic effects on cell proliferation, and a COX-2 specific inhibitor (JTE-522) did not suppress growth stimulation by a low dose of bile acid.

CONCLUSIONS

Bile acid at a low dose stimulates the proliferation of ESCC by inducing G1-regulating molecules. However, COX-2 expression, which is also induced by bile acid, does not affect cell proliferation. Further work is needed to elucidate its role in carcinogenesis.

A synergic inhibitory-effect of combination with selective cyclooxygenase-2 inhibitor and S-1 on the peritoneal metastasis for scirrhous gastric cancer cells

An inhibitory-effect of a selective cyclooxygenase-2 (COX-2) inhibitor on peritoneal metastasis of scirrhous gastric carcinoma was investigated in vivo. Peritoneal metastasis had developed after intraperitoneal inoculation of scirrhous gastric cancer cells, OCUM-2MD3, in nude mice. COX-2 inhibitor and/or S-1 were administered orally in nude mice with peritoneal metastasis. Oral administration of COX-2 inhibitor and S-1 significantly prolonged survival rates of these nude mice, compared with either alone. These findings suggested that combining S-1 and COX-2 inhibitor administration obtain a synergistic inhibitory-effect on the peritoneal metastasis of scirrhous gastric carcinoma.

Inhibitory effect of a selective cyclooxygenase inhibitor on the invasion-stimulating activity of orthotopic fibroblasts for scirrhous gastric cancer cells

The cyclooxygenase (COX)-2 inhibitor has been reported to impede the progression of gastric cancer, but underlying mechanisms remain unclear. We therefore investigated the effect of a COX-2 inhibitor, JTE-522, on the ability of orthotopic fibroblasts to stimulate invasion of scirrhous gastric carcinoma cells. The human scirrhous gastric cancer cell lines OCUM-2D or OCUM-2M, and human gastric fibroblasts (NF-21) were cultured in the absence or presence of JTE-522 at various concentrations. Cancer cells were then assayed for invasiveness in vitro by invasion assay. The effect of prostaglandins (PG) on growth factor production in NF-21 cells was examined by ELISA. Finally, the effects of orally administrated JTE-522 on orthotopically transplanted tumors were examined in nude mice. NF-21 cells stimulated invasion by OCUM-2D cells, an effect suppressed by JTE-522 at 5 x 10(-6) M. Hepatocyte growth factor (HGF) and PGE2 production by NF-21 cells were suppressed by JTE-522 (P < 0.01). PGE2 stimulated HGF production by NF-21 cells in a dose-dependent manner. JTE-522 significantly suppressed orthotopic tumor growth and lymph node metastasis, and also decreased HGF expression by fibroblasts within the gastric tumor. In conclusion, we found that gastric fibroblasts stimulated invasiveness in scirrhous gastric cancer cells, whereas a selective COX-2 inhibitor inhibited this paracrine effect by decreasing fibroblast PGE2 production, resulting in downregulation of HGF production.

ENHANCED SENSITIVITY OF BLADDER CANCER CELLS TO CISPLATIN MEDIATED CYTOTOXICITY AND APOPTOSIS IN VITRO AND IN VIVO BY THE SELECTIVE CYCLOOXYGENASE-2 INHIBITOR JTE-522

PURPOSE

Cyclooxygenase-2 (COX-2) is a key inducible enzyme involved in the production of prostaglandins and its inhibitors have been shown to induce apoptosis in various cancer cells. Several anticancer agents also mediate apoptosis and may share the common intracellular pathways leading to apoptosis with COX-2 inhibitors. We reasoned that combination treatment of bladder cancer cells with COX-2 inhibitors and anticancer agents may result in synergistic apoptosis. We examined whether the selective COX-2 inhibitor JTE-522 (4-(4-cyclohexyl-2-methyloxazol-5-yl)-2-fluorobenzenesulfonamide) synergizes with anticancer agents in cytotoxicity and apoptosis against bladder cancer cells in vitro and in vivo.

MATERIALS AND METHODS

Cytotoxicity was determined by the microculture tetrazolium dye assay.

RESULTS

Combination treatment of T24 bladder cancer cells with JTE-522 and cis-diamminedichloroplatinum (II) (CDDP) resulted in a synergistic cytotoxic effect. Synergy achieved in cytotoxicity with JTE-522 and CDDP was shown to be due to apoptosis. Treatment of T24 cells with JTE-522 decreased expression of the anti-apoptotic molecule Bcl-2. The in vivo significant growth inhibitory effect of JTE-522 and CDDP against the T24 line heterotransplanted in SCID mice was also observed.

CONCLUSIONS

This study demonstrates that combination treatment of bladder cancer cells with the selective COX-2 inhibitor JTE-522 and CDDP results in synergistic cytotoxicity and apoptosis in vitro and in vivo. These findings support the potential clinical application of a combination of JTE-522 and CDDP for the treatment of bladder cancer as a new form of therapy with more selective cytotoxicity and fewer collateral side effects.

Production of prostaglandinE2 via bile acid is enhanced by trypsin and acid in normal human esophageal epithelial cells

Several reports suggest that duodenogastroesophageal reflux may produce esophagitis, Barrett's esophagus and esophageal carcinoma. And it is well known that the incidence of adenocarcinoma arising from Barrett's esophagus has been increasing during the past decade. On the other hand, cyclooxygenase-2 and prostaglandins, produced by the catalytic reaction of cyclooxygenase-2, are considered to relate to carcinogenesis of the digestive tract and other malignant tumors. Recent reports suggest that cyclooxygenase-2 is induced in Barrett's esophagus and esophageal carcinoma. The purpose of this study is to investigate the reaction of cyclooxygenase-2 expression and prostaglandinE2 production on normal human esophageal epithelial cells cultured with gastroduodenal components. Normal human esophageal epithelial cells were cultured with chenodeoxycholic acid, trypsin and in acidic condition, individually and with different combinations of these three factors. After culturing, cyclooxygenase-2 expression in the cells and amount of prostglandinE2 in culture media was evaluated by immunoblotting and enzyme-immunoassay, respectively after culturing the cells. Cyclooxygenase-2 expression was up-regulated by bile acid and prostaglandinE2 production was enhanced by bile acid with trypsin, acidic condition or both of these components, without a synergistic effect on cyclooxygenase-2 expression. Production of prostaglandinE2 via these factors was suppressed by the cyclooxygenase-2 selective inhibitor JTE-522. The results suggest that duodenogastroesophageal reflux may induce cyclooxygenase-2 expression and prostaglandinE2 production in esophageal epithelial cells, cyclooxygenase-2 specific inhibitors may have a chemopreventive effect on esophageal carcinoma.

Design, synthesis and biological evaluation of some pyrazole derivatives as anti-inflammatory-antimicrobial agents

The synthesis of novel series of structurally related 1H-pyrazolyl derivatives is described. All the newly synthesized compounds were tested for their in vivo anti-inflammatory activity by two different bioassays namely; cotton pellet-induced granuloma and sponge implantation model of inflammation in rats. In addition, COX-1 and COX-2 inhibitory activities, ulcerogenic effects and acute toxicity were determined. The same compounds were evaluated for their in vitro antimicrobial activity against Escherichia coli, as an example of Gram negative bacteria, Staphylococcus aureus as an example of Gram positive bacteria, and Candida albicans as a representative of fungi. The combined anti-inflammatory data from local and systemic in vivo animal models showed that compounds 4, 5, 8, 9, 11 and 12a exhibited anti-inflammatory activity comparable to that of indomethacin with no or minimal ulcerogenic effects and high safety margin (LD(50)>500 mg/Kg). In addition, compounds 4, 7, 10, 12a and 12b displayed appreciable antibacterial activities when compared with ampicillin, especially against S. aureus. Compounds 4 and 12a are the most distinctive derivatives identified in the present study because of their remarkable in vivo and in vitro anti-inflammatory potency and their pronounced antibacterial activities comparable to ampicillin against Gram positive. On the other hand, compound 12a exhibited good selective inhibitory activity against COX-2 enzyme. Therefore, such compound would represent a fruitful matrix for the development of anti-inflammatory-antimicrobial candidates.

Cyclooxygenase 2 is a key enzyme for inflammatory cytokine-induced angiogenesis

Cyclooxygenase1 (COX1) and COX2 mediate the rate-limiting step in arachidonic acid metabolism. Expression of COX2 mRNA and protein is often enhanced in various human cell types by inflammatory cytokines such as interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNFalpha). IL-1beta enhanced expression of various prostanoids and this expression was blocked by COX2 selective inhibitors. IL-1beta markedly induced angiogenesis in vitro and in vivo, which was significantly inhibited by COX2 selective inhibitors but not by a vascular endothelial growth factor (VEGF) receptor tyrosine kinase inhibitor. In contrast, COX2 selective inhibitors only partially blocked VEGF-induced angiogenesis. EP2, EP4 (prostaglandin E2 receptors) agonists and thromboxane A2 (TXA2) receptor agonists induced angiogenesis in vitro and in vivo; IL-1beta-induced angiogenesis was blocked by an EP4 antagonist and a TXA2 receptor antagonist. IL-1beta induced much less angiogenesis in cornea of COX2 knockout mice than that of wild-type mice. This is the first report that COX2 and some prostanoids play a key role in IL-1beta-induced angiogenesis.

Selective inhibition of cyclooxygenase (COX)-2 inhibits endothelial cell proliferation by induction of cell cycle arrest

High-level expression of cyclooxygenase (COX)-2 is reported in 80-90% of colorectal adenocarcinomas. Selective inhibition of COX-2 was shown to reduce colorectal tumorigenesis in different models of carcinogenesis and to prevent metastasis in xenograft tumor models, as well as to suppress in vitro induced angiogenesis. Recently, COX-2 was reported to be expressed not only in malignant epithelial cells, but also in the neovasculature that feeds the tumor in a variety of solid human cancers. Thus, one of the possible mechanisms by which selective COX-2 inhibitor reduces tumor growth and metastasis is through inhibition of tumor angiogenesis. Although a report suggested a possible role of endothelial COX-1 in the process of angiogenesis, in a recent study, the selective inhibition of COX-2 was shown to strongly inhibit angiogenesis by inducing endothelial cell (EC) apoptosis. In the present study, using human umbilical vein endothelial cells (HUVECs) as a model of angiogenesis, we investigated the potential antiangiogenic effect of the selective COX-2 inhibitor and its mechanism of action, and clearly demonstrated that selective inhibition of COX-2 caused a dose-dependent decrease in the proliferative activity of ECs, as well as an inhibition of capillary-like tube formation. The inhibitory effect on EC proliferation was dependent on the cell cycle arrest to the G1 phase and not on cell apoptosis.

Suppression of pancreatic cancer cell invasion by a cyclooxygenase-2-specific inhibitor

Pancreatic cancer is characterized by invasive and metastatic potential. In this study, effects of the COX-2 inhibitor JTE-522 on cell viability, invasion, and invasion-related cellular properties were determined. JTE-522 (10 microM) induced a 75-90% reduction in invasion, compared to cells treated with a vehicle only, in the COX-2-expressing cells. In contrast, this inhibitor caused no significant reduction in cells lacking COX-2. Determinants of cell invasion, such as cell motility, adhesion to the extracellular matrix, and gelatinolytic activity of metalloproteinase, were also modulated in COX-2-positive pancreatic cancer cells. Thus, COX-2-specific inhibitors may be a useful anti-invasive therapeutic option in pancreatic cancer.

COX-2/VEGF-dependent facilitation of tumor-associated angiogenesis and tumor growth in vivo

Nonsteroidal anti-inflammatory drugs are known to suppress the occurrence and progression of malignancies such as colorectal cancers. However, the precise mechanism of these actions remains unknown. We have evaluated the role of an inducible cyclo-oxygenase (COX-2) in tumor-associated angiogenesis and tumor growth, and identified the downstream molecules involved using a ddy mouse model of sponge angiogenesis, which mimics tumor angiogenesis and is COX-2 and vascular endothelial growth factor (VEGF) dependent. In this model, VEGF expression was down-regulated by selective COX-2 inhibition with NS-398. To find out the involvement of COX-2/VEGF pathway in tumor-associated angiogenesis, we estimated angiogenesis occurring around implanted Millipore chambers containing sarcoma-180 (S-180) cells or Lewis lung carcinoma cells. Daily oral administration of NS-398 or of aspirin, a nonselective COX inhibitor, suppressed angiogenesis seen around the Millipore chambers. S-180 cells implanted in ddy mice formed substantial tumors with extensive angiogenesis markedly suppressed by aspirin and COX-2 inhibitors NS-398 and JTE522, but not by mofezolac, an inhibitor of constitutive COX-1. Tumor-associated angiogenesis was also significantly suppressed by a neutralizing antibody against VEGF. S-180 tumor growth in the subcutaneous tissues was also suppressed by aspirin, COX-2 selective inhibitors, and the VEGF antibody, but not by the COX-1 inhibitor. These results demonstrate that the inhibition of the COX-2/VEGF-dependent pathway was effective in tumor-associated angiogenesis, tumor growth, and tumor metastasis.

JTE-522, a cyclooxygenase-2 inhibitor, is an effective chemopreventive agent against rat experimental liver fibrosis1

BACKGROUND & AIMS

The aim of this study was to assess the effects of cyclooxygenase (COX)-2 inhibition on rat experimental liver fibrogenesis.

METHODS

We investigated the inhibitory effects of a selective COX-2 inhibitor, JTE-522, on liver fibrosis induced by a choline-deficient, l-amino acid-defined diet (CDAA). Inhibitory effect was also tested in a second model of thioacetamide (TAA)-induced liver fibrosis.

RESULTS

CDAA induced liver fibrosis and preneoplastic foci at 12 weeks and cirrhosis at 36 weeks. Hepatocellular carcinoma was noted in 13 of 15 rats (87%). JTE-522 significantly inhibited fibrosis and development of preneoplastic lesions in a dose-dependent manner and completely inhibited generation of cirrhosis and hepatocellular carcinoma at both low and high doses (10 and 30 mg/kg body wt/day, respectively). JTE-522 administrated only from 12 weeks to 36 weeks also prevented cirrhosis and formation of hepatocellular carcinoma. JTE-522 itself did not cause local or systemic gross or histopathologic changes at 36 weeks. Mechanistic studies indicated that the CDAA model displayed up-regulation of several biomarkers, including COX-2, arachidonate metabolite (prostaglandin E(2)), serum aspartate aminotransferase, and c-myc expression. The model also showed an increased proportion of activated hepatic stellate cells, proliferating cell nuclear antigen index, and CD45-positive inflammatory cells in the liver. JTE-522 effectively diminished these changes. JTE-522 exhibited similar antifibrosis effects in the TAA model.

CONCLUSIONS

Our results suggest that COX-2 is involved in CDAA- and TAA-induced liver fibrosis. Our data also indicate that JTE-522 is a potent chemopreventive agent of rat liver fibrosis with low toxicity.

Anti-inflammatory effect and low ulcerogenic activity of etodolac, a cyclooxygenase-2 selective non-steroidal anti-inflammatory drug, on adjuvant-induced arthritis in rats

Adjuvant arthritic rats are known to be more susceptible to gastric damage induced by non-steroidal anti-inflammatory drugs (NSAIDs) than are normal rats. We compared the relative gastric safety profile of etodolac with those of meloxicam, diclofenac sodium and indometacin in adjuvant arthritic rats and normal rats or mice. As a measure of the safety profiles of NSAIDs, we used the safety index, the ratio of the dose that elicits gastric mucosal lesions to the effective dose as an anti-inflammatory or analgesic compound. The anti-inflammatory or analgesic effects of NSAIDs were assessed by paw swelling in adjuvant arthritic rats, and either carrageenin-induced paw edema or brewer's yeast-induced hyperalgesia, as well as acetic acid-induced writhing, in normal rats or mice. In addition, we also investigated the effects of these NSAIDs on human COX-1 and COX-2 activity. Etodolac and other NSAIDs inhibited paw swelling and caused gastric mucosal lesions in adjuvant arthritic rats in a dose-dependent manner. Etodolac showed the highest UD(50) value and safety index among these NSAIDs in arthritic rats. In normal rats, etodolac also showed the highest UD(50) value and safety index, except when its effects were assessed by acetic acid-induced writhing. Etodolac and meloxicam showed selectivity for human COX-2 over COX-1. In contrast, diclofenac sodium and indometacin were selective for COX-1. These results suggest that etodolac, a COX-2 selective NSAID, has anti-inflammatory effects with a better safety profile for the stomach than do non-selective NSAIDs, including diclofenac sodium and indometacin, in adjuvant arthritic as well as normal rats.

Host prostaglandin E(2)-EP3 signaling regulates tumor-associated angiogenesis and tumor growth

Nonsteroidal antiinflammatories are known to suppress incidence and progression of malignancies including colorectal cancers. However, the precise mechanism of this action remains unknown. Using prostaglandin (PG) receptor knockout mice, we have evaluated a role of PGs in tumor-associated angiogenesis and tumor growth, and identified PG receptors involved. Sarcoma-180 cells implanted in wild-type (WT) mice formed a tumor with extensive angiogenesis, which was greatly suppressed by specific inhibitors for cyclooxygenase (COX)-2 but not for COX-1. Angiogenesis in sponge implantation model, which can mimic tumor-stromal angiogenesis, was markedly suppressed in mice lacking EP3 (EP3(-/-)) with reduced expression of vascular endothelial growth factor (VEGF) around the sponge implants. Further, implanted tumor growth (sarcoma-180, Lewis lung carcinoma) was markedly suppressed in EP3(-/-), in which tumor-associated angiogenesis was also reduced. Immunohistochemical analysis revealed that major VEGF-expressing cells in the stroma were CD3/Mac-1 double-negative fibroblasts, and that VEGF-expression in the stroma was markedly reduced in EP3(-/-), compared with WT. Application of an EP3 receptor antagonist inhibited tumor growth and angiogenesis in WT, but not in EP3(-/-). These results demonstrate significance of host stromal PGE(2)-EP3 receptor signaling in tumor development and angiogenesis. An EP3 receptor antagonist may be a candidate of chemopreventive agents effective for malignant tumors.

Inhibitory effect of a selective cyclooxygenase-2 inhibitor on liver metastasis of colon cancer

COX-2 overexpression is recognized in various cancers, but the role of COX-2 in the progression of cancer, including the liver metastasis of colon cancer, is not clearly understood. We examined the role of COX-2 in the mechanism of liver metastasis of colon cancer, using a highly metastasizable colon carcinoma cell line, LM-H3. A COX-2 inhibitor, JTE-522, inhibited cell proliferation and invasion of LM-H3 in vitro and clearly reduced the number of metastatic nodules on the surface of nude mouse livers in vivo. We also examined the effects of JTE-522 on the production of growth factors and MMPs through the use of ELISA and gelatin zymography, respectively. JTE-522 downregulated PDGF production by LM-H3 but had no influence on VEGF production. JTE-522 also inhibited MMP-2 secretion by LM-H3. JTE-522 downregulated PGE(2) production, but the associated changes in PGE(2) did not affect PDGF and VEGF production by LM-H3. We conclude that JTE-522 downregulated the cell proliferation and invasive potential of LM-H3 by reducing the production of PDGF and MMP-2 and hypothesize that these inhibitory effects on the production of PDGF and MMP-2 can lead to inhibition of liver metastasis of colon cancer. These data indicate that the COX-2 inhibitor JTE-522 has a high potential for use as a clinical agent for the treatment of liver metastasis of colon cancer.

4-(4-cycloalkyl/aryl-oxazol-5-yl)benzenesulfonamides as selective cyclooxygenase-2 inhibitors: enhancement of the selectivity by introduction of a fluorine atom and identification of a potent, highly selective, and orally active COX-2 inhibitor JTE-522(1)

A series of 4-(4-cycloalkyl/aryl-oxazol-5-yl)benzenesulfonamide derivatives were synthesized and evaluated for their abilities to inhibit cyclooxygenase-2 (COX-2) and cyclooxygenase-1 (COX-1) enzymes. In this series, substituent effects at the ortho position to the sulfonamide group on the phenyl ring were examined. Most substituents reduced or lost both COX-2 and COX-1 activities. In contrast, introduction of a fluorine atom preserved COX-2 potency and notably increased COX1/COX-2 selectivity. This work led to the identification of a potent, highly selective, and orally active COX-2 inhibitor JTE-522 [9d, 4-(4-cyclohexyl-2-methyloxazol-5-yl)-2-fluorobenzenesulfonamide], which is currently in phase II clinical trials for the treatment of rheumatoid arthritis, osteoarthritis, and acute pain.

Cyclooxygenase-2 expression during allergic inflammation in guinea-pig lungs

Prostaglandins and thromboxanes are important modulators of airway physiology. The synthesis of these mediators depends on two isoforms of cyclooxygenase (COX), constitutive COX-1 and inducible COX-2. COX-2 expression has been observed in various inflammatory diseases, but not all aspects of the expression and the role of COX-2 in conditions of allergic inflammation such as asthma are clear. In the present study, we examined the 72-h kinetics of the expression of COX-isoform mRNA in ovalbumin-sensitized and -challenged guinea-pig lungs. The sensitized animals showed a robust and transient induction of COX-2 mRNA expression within 1 h after ovalbumin challenge, whereas their COX-1 mRNA levels remained unchanged. Upregulation of the level and activity of COX-2 protein followed the induction of COX-2 mRNA. Lung slices harvested from ovalbumin-challenged animals released more prostaglandin D(2) and prostaglandin E(2) spontaneously or in response to A23187 (10 microM) ex vivo than did those from unchallenged animals. This response was significantly blocked by the COX-2 selective inhibitors, NS-398 and JTE-522. In vivo administration of NS-398 significantly inhibited the accumulation of eosinophils and neutrophils in the lungs. In conclusion, de novo COX-2 expression during allergic inflammation modifies prostanoid synthesis in the lung and airway pathophysiology.

4-Aryl/cycloalkyl-5-phenyloxazole derivatives as selective COX-2 inhibitors

A series of 4-aryl/cycloalkyl-5-phenyloxazole derivatives was synthesized and evaluated for their ability to inhibit cyclooxygenase-2 (COX-2) and cyclooxygenase-1 (COX-1). These compounds were found to be potent and selective COX-2 inhibitors.

Cyclooxygenase-2 downregulates inducible nitric oxide synthase in rat intestinal epithelial cells

Cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression has been demonstrated in inflamed intestinal mucosa. Although regulation of COX-2 and iNOS expression has been studied extensively, the interplay between these two enzymes remains unclear. Because they play crucial roles in inflammation and/or carcinogenesis, we investigated whether COX-2 regulates iNOS expression and evaluated the effects of COX-2 inhibitor and arachidonic acid (AA) on iNOS induction. The COX-2 gene coding region was stably transfected into rat intestinal epithelial cells (RIE sense cells). After interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS) administration, iNOS and COX-2 expression was evaluated by Western blotting. PGE(2) was measured by the enzyme immunoassay (EIA) method. Expression of IFN response factor-1, phosphorylated extracellular signal-related kinase-1 and -2, and Ikappa-Balpha was evaluated. Activator protein-1 and nuclear factor-kappaB (NF-kappaB) were examined by gel mobility shift assay; a supershift assay was performed to identify the NF-kappaB complex components. JTE-522 or AA was added before IFN-gamma and LPS administration, and effects on iNOS and PGE(2) induction were evaluated by Western blotting or EIA. iNOS protein and mRNA expression was inhibited in RIE sense cells. Although NF-kappaB activation was suppressed and Ikappa-Balpha protein was more stable, respectively, in RIE sense cells, no difference was noted in other transcription factors. JTE-522 increased iNOS protein expression in RIE cells. We conclude that COX-2 suppressed iNOS expression in RIE cells through suppression of NF-kappaB by stabilizing Ikappa-Balpha.

Cyclooxygenase-2 stimulates production of amyloid beta-peptide in neuroblastoma x glioma hybrid NG108-15 cells

Cyclooxygenase (COX) synthesizes bioactive prostaglandins from arachidonic acid, and there are COX-1 and COX-2 isoforms with distinct pathophysiological functions. Recent studies demonstrated that COX-2 expression was up-regulated in the brain of patients with Alzheimer's disease. We established mouse neuroblastoma x rat glioma hybrid NG108-15 cells stably expressing human COX-2. The COX-2-expressing cells showed 3- to 4-fold increases in both COX activity and prostaglandin E(2) production. The mRNA level of amyloid precursor protein (APP) was elevated by approximately 2-fold in the COX-2-expressing cells compared with mock-transfected cells. Amyloid beta-peptide and a secreted form of APP, both derived from APP by proteolysis was also increased. Interestingly, neurite outgrowth was stimulated in the COX-2-expressing cells with concomitant reduction of the cell proliferation rate. A selective COX-2 inhibitor (JTE-522) and a nonselective COX inhibitor (indomethacin) suppressed production of amyloid beta-peptide and a secreted form of APP by inhibition of APP mRNA level, suggesting that COX-2 plays important roles in the neurodegenerative processes of Alzheimer's disease.

Biochemistry of cyclooxygenase (COX)-2 inhibitors and molecular pathology of COX-2 in neoplasia

Several types of human tumors overexpress cyclooxygenase (COX) -2 but not COX-1, and gene knockout transfection experiments demonstrate a central role of COX-2 in experimental tumorigenesis. COX-2 produces prostaglandins that inhibit apoptosis and stimulate angiogenesis and invasiveness. Selective COX-2 inhibitors reduce prostaglandin synthesis, restore apoptosis, and inhibit cancer cell proliferation. In animal studies they limit carcinogen-induced tumorigenesis. In contrast, aspirin-like nonselective NSAIDs such as sulindac and indomethacin inhibit not only the enzymatic action of the highly inducible, proinflammatory COX-2 but the constitutively expressed, cytoprotective COX-1 as well. Consequently, nonselective NSAIDs can cause platelet dysfunction, gastrointestinal ulceration, and kidney damage. For that reason, selective inhibition of COX-2 to treat neoplastic proliferation is preferable to nonselective inhibition. Selective COX-2 inhibitors, such as meloxicam, celecoxib (SC-58635), and rofecoxib (MK-0966), are NSAIDs that have been modified chemically to preferentially inhibit COX-2 but not COX-1. For instance, meloxicam inhibits the growth of cultured colon cancer cells (HCA-7 and Moser-S) that express COX-2 but has no effect on HCT-116 tumor cells that do not express COX-2. NS-398 induces apoptosis in COX-2 expressing LNCaP prostate cancer cells and, surprisingly, in colon cancer S/KS cells that does not express COX-2. This effect may due to induction of apoptosis through uncoupling of oxidative phosphorylation and down-regulation of Bcl-2, as has been demonstrated for some nonselective NSAIDs, for instance, flurbiprofen. COX-2 mRNA and COX-2 protein is constitutively expressed in the kidney, brain, spinal cord, and ductus deferens, and in the uterus during implantation. In addition, COX-2 is constitutively and dominantly expressed in the pancreatic islet cells. These findings might somewhat limit the use of presently available selective COX-2 inhibitors in cancer prevention but will probably not deter their successful application for the treatment of human cancers.

The analgesic effect profile of FR122047, a selective cyclooxygenase-1 inhibitor, in chemical nociceptive models

The pharmacological profile of the analgesic agent, 1-[(4, 5-bis(4-methoxyphenyl)-2-thiazoyl)carbonyl]-4-methylpiperazine hydrochloride (FR122047), was investigated. In recombinant human cyclooxygenase enzyme assays, the inhibition of prostaglandin E(2) formation by FR122047 was 2300 times more selective for cyclooxygenase-1 than cyclooxygenase-2. Oral administration of FR122047 (3.2-100 mg/kg) dose dependently reduced the phase 2 response (10-60 min) of the formalin test in rats. This effect was 3 times less potent than that of indomethacin. FR122047 (1-32 mg/kg; p. o.) showed a dose-dependent analgesic effect against the acetic acid-induced writhing response in mice. Furthermore, FR122047 (0. 01-10 mg/kg, p.o.) inhibited the increase in 6-keto prostaglandin F(1alpha) level in acetic acid-injected mouse peritoneal cavity. However, a selective cyclooxygenase-2 inhibitor, NS-398, had no effect in these cyclooxygenase-1 sensitive pain models. These results suggest that FR122047, a selective cyclooxygenase-1 inhibitor, shows an analgesic effect in chemical nociceptive models and may be a useful analgesic agent.