Pharmacological profile of JTE-522, a novel prostaglandin H synthase-2 inhibitor, in rats

Analgesic activity of myricetin isolated from Myrica rubra Sieb. et Zucc. leaves

Myrica rubra Sieb. et Zucc. leaves are commonly used as an astringent, antidiarrheic, and analgesics in folk medicine in China. In the present study, the analgesic activity of myricetin, a major compound in Myrica rubra Sieb. et Zucc. leaves was evaluated in vivo. The analgesic effect of myricetin was tested by a serial of models, such as acetic acid-induced writhing response, formalin-induced paw licking and hot plate test. The sedative activity was evaluated by pentobarbital-induced sleep time. Platelet aggregation induced by collagen and arachidonic acid was also performed in vitro. Myricetin showed a significant inhibition on chemical nociceptive models such as the acetic acid-induced writhing response and the licking time on the late phase in the formalin test in a dose-dependent manner, but did not manifest a signicant effect in hot plate test. Myricetin was also not able to increase the sleeping time induced by pentobarbital, which further indicated that the analgesic effect of myricetin was unrelated to sedation. In addition, myricetin inhibited the content of PGE2 in the peritoneal fluid and platelet aggregation induced by collagen and arachidonic acid in vitro. These results collectively demonstrated that myricetin possessed potent analgesic activity, which was related with peripheral analgesia, but, not with the opioid system. Myricetin may be a potent COX-1 inhibitor with anti-platelet activity.

Effect of the oral absorption of benzenesulfonanilide-type cyclooxygenase-1 inhibitors on analgesic action and gastric ulcer formation

A benzensulfonanilide-type cyclooxygenase-1 (COX-1)-selective inhibitor, ZXX2-77: 4-amino-4'-chloro-N-methylbenzenesulfonanilide (4a), has been reported as a novel analgesic that does not cause gastric damage. This compound has a weak analgesic effect but has potent in vitro COX-1 inhibitory activity. Since the reason for the weak analgesic effect in vivo was thought to be the low rate of oral absorption, the blood concentration of ZXX2-77 (4a) was measured in rats. It was found that the C(max) value (1.2 microM) of ZXX2-77 (4a) at a dose of 30 mg/kg did not reach the COX-1 IC(50) value (3.2 microM). On the other hand, ZXX2-79 (4b) (SO(2)NH derivative of ZXX2-77 (4a); 4-amino-4'-chlorobenzenesulfonanilide), which shows less potent COX inhibitory activities (COX-1 IC(50) = 12 microM, COX-2 IC(50) = 150 microM) than those of ZXX2-77 (4a) in vitro, was found to be more absorbable (C(max) = 16 microM at a dose of 30 mg/kg in rats) than ZXX2-77 (4a). Furthermore, ZXX2-79 (4b) not only showed a potent analgesic effect in a formalin test but also caused little gastric damage. These findings indicate that demethylated sulfonamide compounds are more easily absorbed than are N-methylated sulfonamide compounds and suggest that COX-1-selective inhibitors will be useful as analgesics that do not cause gastric damage.

Chenodeoxycholic acid stimulates the progression of human esophageal cancer cells: A possible mechanism of angiogenesis in patients with esophageal cancer

Bile acids are known to promote the growth of gastrointestinal cancer. However, the underlying mechanism remains unclear. We examined whether bile acids induce tumor growth via the cyclooxygenase (COX)-2 angiogenic pathway. In vitro, esophageal squamous cell carcinoma (ESCC) cells and esophageal adenocarcinoma cells were studied. Production of prostaglandin E2 (PGE2) and vascular endothelial growth factor (VEGF) in response to treatment with chenodeoxycholic acid (CDCA) was assessed by enzyme-linked immunosorbent assay (ELISA). COX-2 protein and VEGF protein were measured by immunoblot analysis, and COX-2 activity was measured by ELISA. In vivo, CDCA was administered to ESCC cell-bearing mice. Tumor tissues were analyzed immunohistochemically, and microvessel density was evaluated. Clinically, 134 patients with ESCC who underwent esophagectomy were studied. In vitro, CDCA induced the production of PGE2 and VEGF in dose- and time-dependent manners, and these effects were attenuated by a selective COX-2 inhibitor, mitogen-activated protein kinases inhibitor, or epidermal growth factor receptor inhibitor. CDCA-induced COX-2 in the cell lysate increased the secretion of VEGF into the culture medium. In vivo, CDCA markedly enhanced tumor growth and increased vascularization. Clinically, patients whose tumors expressed both COX-2 and VEGF had poor outcomes. Our results suggest that bile acids, important constituents of duodenal fluid, stimulate the development of human esophageal cancer by promoting angiogenesis via the COX-2 pathway.

Suppression of adjuvant-induced arthritic bone destruction by cyclooxygenase-2 selective agents with and without inhibitory potency against carbonic anhydrase II

In vitro assays revealed that COX-2 inhibitors with CA II inhibitory potency suppressed both differentiation and activity of osteoclasts, whereas that without the potency reduced only osteoclast differentiation. However, all COX-2 inhibitors similarly suppressed bone destruction in adjuvant-induced arthritic rats, indicating that suppression of osteoclast differentiation is more effective than that of osteoclast activity for the treatment.

INTRODUCTION

Cyclooxygenase (COX)-2 and carbonic anhydrase II (CA II) are known to play important roles in the differentiation of osteoclasts and the activity of mature osteoclasts, respectively. Because several COX-2 selective agents were recently found to possess an inhibitory potency against CA II, this study compared the bone sparing effects of COX-2 selective agents with and without the CA II inhibitory potency.

MATERIALS AND METHODS

Osteoclast differentiation was determined by the mouse co-culture system of osteoblasts and bone marrow cells, and mature osteoclast activity was measured by the pit area on a dentine slice resorbed by osteoclasts generated and isolated from bone marrow cells. In vivo effects on arthritic bone destruction were determined by radiological and histological analyses of hind-paws of adjuvant-induced arthritic (AIA) rats.

RESULTS

CA II was expressed predominantly in mature osteoclasts, but not in the precursors. CA II activity was inhibited by sulfonamide-type COX-2 selective agents celecoxib and JTE-522 similarly to a CA II inhibitor acetazolamide, but not by a methylsulfone-type COX-2 inhibitor rofecoxib. In vitro assays clearly revealed that celecoxib and JTE-522 suppressed both differentiation and activity of osteoclasts, whereas rofecoxib and acetazolamide suppressed only osteoclast differentiation and activation, respectively. However, bone destruction in AIA rats was potently and similarly suppressed by all COX-2 selective agents whether with or without CA II inhibitory potency, although only moderately by acetazolamide.

CONCLUSIONS

Suppression of osteoclast differentiation by COX-2 inhibition is more effective than suppression of mature osteoclast activity by CA II inhibition for the treatment of arthritic bone destruction.

Bilateral induction of the S-100A9 gene in response to spreading depression is modulated by the cyclooxygenase-2 activity

Cyclooxygenase-2 (COX-2) was reported to be induced in the infarcted human brain. Spreading depression (SD) is thought to play a role in this induction. In this study, we correlated the expression of SD-associated genes with COX-2 production in brains after SD. Rats were divided into 3 groups: rats that did not undergo SD (group I saline controls, n=7), rats that underwent unilateral SD as a result of KCl application (group II, n=9), and rats that were pretreated with the selective COX-2 inhibitor, JTE-522 3 h before the induction of SD (group III, n=7). The expression of the SD-associated genes, S-100A9, and mitogen-activated proteinkinase phosphatase (cpg21) was analyzed 2 h later using a cDNA array. In group II, COX-2 and cpg21 mRNA expression, as determined by RT-PCR, were significantly upregulated in the hemisphere undergoing SD. While the expression of S-100A9 mRNA was bilaterally upregulated in these animals, this expression was significantly reduced in group III, and was accompanied by reduced bilateral production of PGE(2). Thus, the bilateral induction of expression of the S-100A9 gene in response to SD was associated with COX-2 activation.

JTE-522, a selective COX-2 inhibitor, inhibits growth of pulmonary metastases of colorectal cancer in rats

Background

Epidemiological studies have shown that individuals who regularly consume NSAIDs have lower rates of mortality associated with colorectal cancer. Because COX-2 inhibitors prevent tumor growth through some mechanisms, we assessed the effect of JTE-522, a selective COX-2 inhibitor, on pulmonary metastases of colon cancer in a rat model.

Methods

A suspension of 5 × 10⁶ RCN-9 (rat colon cancer cells) was injected into the tail vein of 24 anesthetized male F344/DuCrj rats. Oral JTE-522 (0, 3, 10, or 30 mg/kg/day) was administered from the day before RCN-9 injection until the end of the study. Twenty-four days later, the lungs were removed from sacrificed rats and weighed. Pulmonary metastatic tumors were microscopically evaluated in the largest cross sections. We also performed immunohistochemical staining for both COX-2 and VEGF.

Results

JTE-522 dose-dependently decreased lung weight (p = 0.001) and the size of pulmonary metastatic tumors (p = 0.0002). However, the differences in the number of metastatic tumors among 4 groups were insignificant. Significant adverse effects of JTE-522 were undetectable. Immunohistochemical staining showed high levels of both COX-2 and VEGF in pulmonary metastatic tumors.

Conclusion

JTE-522 dose-dependently decreased the size, but not the number of pulmonary metastases. COX-2 inhibitors might block metastatic tumor growth, but not actual metastasis. Selective COX-2 inhibitors might be useful as therapeutic agents that inhibit the growth of metastatic tumors, as well as the tumorigenesis of colorectal cancer.

Transcriptional induction of FosB/DeltaFosB gene by mechanical stress in osteoblasts

Mechanical stress to bone plays a critical role in maintaining bone mass and strength. However, the molecular mechanism of mechanical stress-induced bone formation is not fully understood. In the present study, we demonstrate that FosB and its spliced variant DeltaFosB, which is known to increase bone mass by stimulating bone formation in vivo, is rapidly induced by mechanical loading in mouse hind limb bone in vivo and by fluid shear stress (FSS) in mouse calvarial osteoblasts in vitro both at the mRNA and protein levels. FSS induction of FosB/DeltaFosB gene expression was dependent on gadlinium-sensitive Ca(2+) influx and subsequent activation of ERK1/2. Analysis of the mouse FosB/DeltaFosB gene upstream regulatory region with luciferase reporter gene assays revealed that the FosB/DeltaFosB induction by FSS occurred at the transcriptional level and was conferred by a short fragment from -603 to -327. DNA precipitation assays and DNA decoy experiments indicated that ERK-dependent activation of CREB binding to a CRE/AP-1 like element (designated "CRE2") at the position of -413 largely contributed to the transcriptional effects of FSS. These results suggest that DeltaFosB participates in mechanical stress-induced intracellular signaling cascades that activate the osteogenic program in osteoblasts.

In vitro structure-activity relationship and in vivo studies for a novel class of cyclooxygenase-2 inhibitors: 5-aryl-2,2-dialkyl-4-phenyl-3(2H)furanone derivatives

5-Aryl-2,2-dialkyl-4-phenyl-3(2H)furanone derivatives were studied as a novel class of selective cyclooxygenase-2 inhibitors with regard to synthesis, in vitro SAR, antiinflammatory activities, pharmacokinetic considerations, and gastric safety. 1f, a representative compound for methyl sulfone derivatives, showed a COX-2 IC(50) comparable to that of rofecoxib. In case of 20b, a representative compound for sulfonamide derivatives, a potent antiinflammatory ED(50) of 0.1 mg kg(-1) day(-1) was observed against adjuvant-induced arthritis by a preventive model, positioning 20b as one of the most potent COX-2 inhibitors ever reported. Furthermore, 20b showed strong analgesic activity as indicated by its ED(50) of 0.25 mg/kg against carrageenan-induced thermal hyperalgesia in the Sprague-Dawley rat. 3(2H)Furanone derivatives showed due gastric safety profiles as selective COX-2 inhibitors upon 7-day repeat dosing. A highly potent COX-2 inhibitor of the 3(2H)furanone scaffold could be considered suitable for a future generation COX-2 selective arthritis medication with improved safety profiles.

Synthesis and structure-activity relationship of novel, highly potent metharyl and methcycloalkyl cyclooxygenase-2 (COX-2) selective inhibitors

A novel series of benzo-1,3-dioxolane metharyl derivatives was synthesized and evaluated for cyclooxygenase-2 (COX-2) and cyclooxygenase-1 (COX-1) inhibition in human whole blood (HWB). In the present study, structure-activity relationships (SAR) in the metharyl analogues were investigated. The spacer group and substitutions in the spacer group were found to be quite important for potent COX-2 inhibition. Compounds in which a methylene group (8a-c), carbonyl group (12a-c), or methylidene group (7a-c) connected cycloalkyl groups to the central benzo-1,3-dioxolane template were found to be potent and selective COX-2 inhibitors. Aryl-substituted compounds linked to the central ring by either a methylene or a carbonyl spacer resulted in potent, highly selective COX-2 inhibitors. In this series of substituted-(2H-benzo[3,4-d]1,3-dioxolan-5-yl))-1-(methylsulfonyl)benzene compounds, SAR studies demonstrated that substitution at the 3-position of the aryl group optimized COX-2 selectivity and potency, whereas substitution at the 4-position attenuated COX-2 inhibition. Mono- or difluoro substitution at meta position(s), as in 22c and 22h, was advantageous for both in vitro COX-2 potency and selectivity (e.g., COX-2 IC(50) for 22c = 1 microM and COX-1 IC(50) for 22c = 20 microM in HWB assay). Several novel compounds in the (2H-benzo[3,4-d]1,3-dioxolan-5-yl))-1-(methylsulfonyl)benzene series, as shown in structures 7c, 8a, 12a, 21c, 22c, 22e, and 22h, selectively inhibited COX-2 activity by 40-50% at a test concentration of 1 microM in an in vitro HWB assay.

JTE-522, a selective COX-2 inhibitor, interferes with the growth of lung metastases from colorectal cancer in rats due to inhibition of neovascularization: A vascular cast model study

The lung is a frequent site of metastasis from colorectal cancer, but angiogenesis of lung metastases has not been clarified. Some COX-2 inhibitors prevent tumor growth, although the inhibitory mechanism at the metastatic site is obscure. We investigated the microvascular structure of small lung metastases and the effect of JTE-522, a selective COX-2 inhibitor, on the angiogenesis of pulmonary metastases from colorectal cancer in rats. The tail veins of 25 male F344/DuCrj rats, aged 5 weeks, were injected with a tumor suspension containing 5 x 10(6) RCN-9, a rat colon cancer cell line. Three weeks later, pulmonary vascular resin corrosion casts were taken and the vascularity of metastases was studied using stereo and scanning electron microscopes. We investigated the effect of 0, 10 and 30 mg/kg/day of JTE-522 on the angiogenesis of pulmonary metastases in 3 groups of 5 male rats out of 25. JTE-522 reduced the diameter of tumor vessels as well as the number and size of metastatic tumors. The diameter of tumor vessels and the size of lung metastases significantly and positively correlated with neovascularization in the control group, but not in the JTE-522-treated groups. JTE-522 also affected type of vasculature of metastases, which differed depending on their size. JTE-522 interfered with the growth of hematogenous metastatic tumors by disrupting neovascularization. However, JTE-522 may have some important mechanisms other than inhibition of neovascularization. JTE-522 may be one of the therapeutic agents for the treatment of hematogenous metastasis of colorectal cancer.

JTE-522, a selective cyclooxygenase-2 inhibitor, inhibits induction but not growth and invasion of 1,2-dimethylhydrazine-induced tubular adenocarcinomas of colon in rats

We have previously demonstrated that JTE-522, a selective cyclooxygenase-2 (COX-2) inhibitor, inhibited development of aberrant crypt foci (ACF) in rats, a putative preneoplastic lesion in colon, and suggested its inhibitory potential in rat colon carcinogenesis. To evaluate the chemopreventive properties of JTE-522, the present study was design to evaluate the inhibitory effects of JTE-522 on rat colon tumorigenesis induced by 1,2-dimethylhydrazine (DMH). Rats at 6 weeks of age were divided into 4 groups. One week after the start of the experiment, all rats received DMH by s.c. injection at a dose of 40 mg/kg body weight once a week for 4 successive weeks. As the initiation and postinitiation treatment groups, groups 1-3 were fed diets containing 0, 50, or 150 ppm JTE-522, respectively, from the start of the study to the end. As the postinitiation treatment group, group 4 was given 150 ppm JTE-522 from 1 week after the last DMH injection to the end of the study. Forty weeks after the start of the experiment, administration of 150 ppm JTE-522 during both initiation and postinitiation stages significantly inhibited the incidences of tubular adenocarcinomas and total carcinomas, as well as total tumors in the colon. The inhibitory effect of JTE-522 was most prominent for tubular adenocarcinomas, but was not observed in the nontubular carcinomas (signet-ring cell and mucinous carcinomas). Almost equal inhibitory effects on tubular adenocarcinomas were also observed in the rats given 150 ppm JTE-522 during the postinitiation stage, suggesting that its major anticancer action is at the postinitiation phase. However, JTE-522 had no effect on the size or invasive extent of tubular adenocarcinomas. Furthermore, microarray analyses revealed that JTE-522 had no effect on gene expression levels in DMH-induced tubular adenocarcinomas. These findings suggest that JTE-522 possesses chemopreventive activity against induction but not progression of tubular adenocarcinomas in rat colon. In view of the significant inhibitory effects of JTE-522 on ACF, its major anticancer action may occur in the postinitiation stage but before the malignant conversion stage of DMH-induced colon carcinogenesis.

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.

Chemopreventive effect of JTE-522, a selective cyclooxygenase-2 inhibitor, on 1, 2-dimethylhydrazine-induced rat colon carcinogenesis

Selective COX-2 inhibitors have been suggested to be an effective strategy in the prevention of colon cancer without the adverse side effects of non-selective, nonsteroid anti-inflammatory drugs. The present experiment was designed to assess the potential chemopreventive properties of JTE-522, a new selective cyclooxygenase-2 inhibitor, on the induction of 1,2-dimethylhydrazine (DMH)-induced colonic aberrant crypt foci (ACF), a marker of rat colon carcinogenesis. A total of 80 male F344 rats were treated with 3 or 10 mg/kg of body weight JTE-522 or vehicle by oral gavage five times weekly from the start of the experiment. One week later, rats received s.c. injections of saline or 20 mg/kg of body weight DMH once weekly for four successive weeks. At the end of 12 weeks after the start of experiment, all rats were sacrificed and colons were evaluated for ACF. 10 mg/kg JTE522 significantly suppressed the total ACF/colon. No inhibitory effect was observed in the 3 mg/kg JTE-522 treatment group. This result suggests that JTE-522 possesses chemopreventive activity against colon carcinogenesis.

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.

Role of prostaglandin H2 synthase 2 in murine parturition: study on ovariectomy-induced parturition in prostaglandin F receptor-deficient mice

To determine the prostaglandin (PG) H2 synthase (generally referred to as cyclooxygenase [COX]) isozyme responsible for producing uterotonic PGs during parturition, we used PGF2alpha receptor-deficient mice, which exhibit parturition failure due to impaired withdrawal of serum progesterone at term. On ovariectomy-induced parturition in these mice, uterine COX-2 mRNA expression was drastically induced in the myometrium, whereas COX-1 mRNA expression in the endometrial epithelium decreased. The concomitant administration of progesterone with ovariectomy resulted in a delay in parturition and the disappearance of both the increase in COX-2 mRNA and the decrease in COX-1 mRNA. Thus, the expression of myometrial COX-2 and the occurrence of parturition are closely associated in this model. Furthermore, administration of the COX-nonselective inhibitor, indomethacin, or the COX-2-selective inhibitor, Dup-697 or JTE-522, effectively delayed ovariectomy-induced parturition in these mice. These findings suggest that COX-2-derived PGs contribute to the onset of parturition after the decrease in serum progesterone level.

Synergistic cytotoxicity and apoptosis of JTE-522, a selective cyclooxygenase-2 inhibitor, and 5-fluorouracil against bladder cancer

PURPOSE

Cyclooxygenase-2 (COX-2) is a key inducible enzyme involved in the production of prostaglandins that has 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. Since over expression of COX-2 has been demonstrated in bladder cancer, we reasoned that combination treatment with a COX-2 inhibitor and anticancer agents in bladder cancer cells may result in synergistic apoptosis. We examined whether the selective COX-2 inhibitor JTE-522 induces apoptosis in bladder cancer cells and whether JTE-522 may act synergistically with anticancer agents to achieve cytotoxicity and apoptosis in these cells.

MATERIALS AND METHODS

Cytotoxicity was determined by microculture tetrazolium dye assay. Synergy was assessed by isobolographic analysis.

RESULTS

COX-2 mRNA expression was observed in the HT1197 bladder cancer cell line. JTE-522 was cytotoxic in HT1197 cells. Treating HT1197 cells with JTE-522 combined with doxorubicin or mitomycin C did not show synergistic cytotoxicity. However, combination treatment of HT1197 cells with JTE-522 and 5-fluorouracil (5-FU) resulted in a synergistic cytotoxic effect. Synergy was also achieved in the T24 bladder cancer line. Synergistic cytotoxicity was noted irrespective of treatment sequence but the highest percent cytotoxicity was obtained when HT1197 cells were treated with JTE-522 and 5-FU simultaneously. The synergy achieved in cytotoxicity with JTE-522 and 5-FU was shown to be due to apoptosis. The mechanisms responsible for synergistic cytotoxicity and apoptosis was examined. Treating HT1197 cells with 5-FU enhanced expression of the pro-apoptotic molecule Bax, while JTE-522 treatment reduced expression of the anti-apoptotic molecule Bcl-XL, resulting in a significantly higher ratio of Bax-to-Bcl-XL.

CONCLUSIONS

This study shows that combination treatment of bladder cancer cells with the selective COX-2 inhibitor JTE-522 and 5-FU results in synergistic cytotoxicity and apoptosis due to the enhanced Bax-to-Bcl-XL expression ratio. These findings support the in vivo potential application of a combination of JTE-522 and 5-FU for bladder cancer.

Role of kinin and prostaglandin in cutaneous thermal nociception

Involvements of kinin and prostaglandin and their interaction in noxious thermal stimuli were investigated in noninflamed and inflamed rats. The nociceptive response was evaluated from the escape latency of foot withdrawal to the thermal stimuli with a beam of light. The escape latency in kininogens-deficient Brown Norway (B/N-) Katholiek rats was significantly longer than that in the normal strain, B/N-Kitasato rats. The latency in B/N-Kitasato rat was prolonged by administration of a bradykinin (BK) B2 receptor antagonist, FR173657 (30 mg/kg, p.o.), whereas it was shortened by pretreatment with a kininase II inhibitor, captopril (10 mg/kg, i.p.). Both agents did not affect the latency in B/N-Katholiek rats. In normal Sprague-Dawley (SD) rat, administration of indomethacin did not change the escape latency against the thermal stimuli. In contrast, administration of indomethacin or a relatively cyclooxygenase-1-selective inhibitor, mofezolac (10 mg/kg, p.o.) significantly reduced numbers of writhing reaction in mice induced by acetic acid solution. Injection of lipopolysaccharide (1 mg/kg, i.v.) resulted in shortening escape latency at 8 h after the injection in B/N-Kitasato rats. This hyperalgesia could be reversed by pretreatment of the rats with indomethacin, a cyclooxygenase-2-selective inhibitor JTE-522 (10 mg/kg, p.o.), or FR173657, but not with mofezolac. The hyperalgesia was not seen in B/N-Katholiek rats. These results indicate that kinin has major participation in peripheral skin thermal nociception under noninflamed condition, although cyclooxygenases may have little participation. Prostaglandins produced by cyclooxygenase-2 could coordinate with BK to elicit hyperalgesia during inflammation induced by lipopolysaccharide.

Cyclooxygenase-2 inhibitors attenuate increased blood pressure in renovascular hypertensive models, but not in deoxycorticosterone-salt hypertension

COX-2 is an inducible cyclooxygenase (COX) that has been reported to be expressed in the macula densa and surrounding cortical thick ascending limb in normotensive rats. The present study assessed the contribution of COX-2 in three different rat models of hypertension, each characterized by a different activation of the renal renin-angiotensin system. Mean blood pressure (MBP) in the rat 2 kidney-1 clip (2K1C) model was significantly reduced with a COX-2 selective inhibitor, NS-398 (10 mg/kg, p.o., twice a day) (vehicle-administered rats (n = 8): 154 +/- 6 mmHg; NS-398-administered rats (n = 5): 128 +/- 10 mmHg). By contrast, a COX-1 selective inhibitor, mofezolac, did not lower MBP. Increased plasma renin activity (23 +/- 8 ng/kg/h (n = 6) vs. sham operation, 2.4 +/- 0.9 ng/kg/h (n = 4)) was markedly reduced to 6.8 +/- 2.7 ng/ml/h (n = 5) by NS-398, but not by mofezolac. The development of 1 kidney-1 clip (1K1C) hypertension was also inhibited by NS-398 (vehicle (n = 12): 133 +/- 1 mmHg; NS-398 (n = 7): 122 +/- 3 mmHg) accompanied by a reduction in plasma renin activity (3.0 +/- 0.3 ng/ml/h, n = 4) to 1.0 +/- 0.2 ng/ml/h (n = 5). The COX-2 inhibitor increased urinary excretions in the 1K1C model, but not in the 2K1C model. In a deoxycorticosterone acetate (DOCA)-salt model, plasma renin activity was markedly suppressed to less than 0.3 ng/ml/h. The COX-2 inhibitor caused no significant changes in MBP, plasma renin activity, or urinary excretion, suggesting that COX-2 made a lesser contribution in this model. Increased expression of COX-2 mRNA and protein was observed in the kidneys of 1K1C and 2K1C rats, but not in DOCA-salt rats. These results suggest that COX-2 plays a significant role in the development of 2K1C and 1K1C renovascular hypertension, in addition to making a substantial contribution to the diuretic effect in the 1K1C model.

Pharmacokinetics and safety of JTE-522, a novel selective cyclooxygenase-2 inhibitor, in healthy male volunteers

AIMS

The pharmacokinetics and safety profile of JTE-522, 4-(4-cyclohexyl-2 methyloxazol-5-yl)-2-fluorobenzensulphonamide, a novel selective cyclooxygenase-2 inhibitor were investigated in healthy male volunteers.

METHODS

Initially, as a pilot study, five groups of two subjects were given oral doses of 3-100 mg of JTE-522. After safety assessment, subjects were given 150 and 200 mg of JTE-522. The effect of food-intake on the pharmacokinetics of JTE-522 at a dose of 150 mg was examined. In the multiple-dose study, subjects were given 150 mg of JTE-522 once a day for 7 days. Concentrations of unchanged JTE-522 in plasma, blood and urine were determined by high performance liquid chromatography (h.p.l.c.). Concentrations of metabolites were estimated with h.p.l.c. chromatograms and calibration curves for quantification of unchanged JTE-522.

RESULTS

In the course of this study, no serious abnormality attributable to the test drug was observed, suggesting that JTE-522 was well tolerated in healthy subjects. In a single-dose study, the concentrations of JTE-522 in blood were much higher than the corresponding concentrations in plasma. JTE-522 was readily distributed to blood cells and percentage distribution into blood cells was more than 99.0%. However, the values of Cmax in blood at doses of 100, 150, 200 mg JTE-522 were 15241, 20445 +/- 3918 (16333-24556), 20965 +/- 3260 (17544-24386) ng ml-1, respectively. These findings suggest that JTE-522 has a high affinity for blood cells and the distribution into blood cells is limited at the higher doses of over 100 mg. In a multiple dose study, pharmacokinetic parameters including t1/2 and AUC after the fourth administration were comparable with that of the seventh administration. Thus, these findings suggest the absence of accumulation on the multiple-dosing of JTE-522.

CONCLUSIONS

These results indicate that JTE-522 has an acceptable pharmacokinetic profile for clinical use without any serious adverse events as we verified in healthy young male volunteers.

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.

Prostacyclin synthase gene transfer modulates cyclooxygenase-2-derived prostanoid synthesis and inhibits neointimal formation in rat balloon-injured arteries

Previous studies have shown that prostacyclin (PGI(2)) synthase (PCS) gene transfer inhibits neointimal formation in balloon-injured arteries. However, the role of each cyclooxygenase (COX) isoform in this healing mechanism remains unknown. We hypothesized that overexpression of PCS may modulate COX-2-mediated prostaglandin (PG) metabolism. That is to say, excessive PGH(2) derived from COX-2 after balloon injury may be converted into PGI(2) rather than PGE(2) or thromboxane (TX) A(2) by overexpressed PCS. We examined the expression of COX isoforms and evaluated the role of COX-2 with regard to the effects of PCS gene transfer by using 4-(4-cyclohexyl-2-methyloxazol-5-yl)-2-fluorobenzenesulfonamide (JTE-522), a selective COX-2 inhibitor. Rats were divided into 4 groups in conjunction with PCS gene transfer and JTE-522 treatment. The PCS gene (30 microg) was transfected into rat balloon-injured arteries by a lipotransfection method. JTE-522 (30 mg/kg per day) was administered for 14 days after balloon injury. Immunohistochemical analysis demonstrated marked COX-2 expression on the neointima. PCS gene transfer markedly inhibited neointimal formation, but JTE-522 reversed this beneficial effect. PCS gene transfer augmented PGI(2) production and decreased PGE(2) production without affecting TXA(2) production, but JTE-522 inhibited this increase in PGI(2) production. In conclusion, PCS gene transfer modulated COX-2-mediated prostanoid synthesis and inhibited neointimal formation after balloon injury.

Suppression of N-nitrosomethylbenzylamine (NMBA)-induced esophageal tumorigenesis in F344 rats by JTE-522, a selective COX-2 inhibitor

Recent studies have demonstrated that overexpression of cyclooxygenase-2 (COX-2) and elevation of COX-2-mediated synthesis of prostaglandin E(2) (PGE(2)) were observed in various cancers including esophageal cancer, but their roles in carcinogenesis of the esophagi still remain unclear. To address the issue, we observed the reduction of N:-nitrosomethylbenzylamine (NMBA)-induced tumorigenesis in rat esophagi via JTE-522 (4-[4-cyclohexyl-2-methyloxazol-5-yl]-2-fluorobenzenesulfonamide), a selective COX-2 inhibitor. In this study, 54 F344 male rats were divided into nine groups; JTE-522 (3, 9 and 30 mg/kg) was administered orally. We also examined the effects of JTE-522 on COX-2 mRNA and synthesis of PGE(2). In the group in which JTE-522 was administered intermittently at a daily dose of 30 mg/kg, the number of NMBA-induced esophageal tumors per rat significantly reduced, to 62% (P< 0.05), but the size of the tumors was not significantly inhibited. In the group in which JTE-522 was administered continuously five times weekly for 24 weeks at a daily dose of 9 mg/kg, both the number and size of tumors significantly reduced, to 29 and 44%, respectively (P<0.05). Furthermore, JTE-522 suppressed not only tumor formation but also developing carcinomas (P<0.0021) [corrected]. In this study, treatment with NMBA alone resulted in an approximately 5-fold rise in expression of COX-2 mRNA detected by semi-quantitative RT-PCR analysis and an approximately 7-fold increase in the production of PGE(2) measured by ELISA compared with the normal esophageal mucosa. The up-regulated COX-2 expression did not decrease with the treatment of JTE-522 at the 3, 9 and 30 mg/kg doses; however, the increased levels of PGE(2) synthesis were significantly decreased by administering JTE-522 (P<0.01). Our study suggests that COX-2-mediated PGE(2) is important in NMBA-induced esophageal tumorigenesis in rats, and therefore may be a promising chemotherapeutic target for the prevention and treatment of esophageal cancer, especially with selective COX-2 inhibitors.

Cyclooxygenase-2 participates in the late phase of airway hyperresponsiveness after ozone exposure in guinea pigs

We examined the role of cyclooxygenase in airway hyperresponsiveness and inflammation after ozone exposure in guinea pigs using a non-selective (indomethacin) and a selective (JTE-522) cyclooxygenase-2 inhibitor. Spontaneously breathing guinea pigs were exposed to ozone (3 ppm) for 2 h after treatment with vehicle, indomethacin (10 mg/kg) or JTE-522 (10 mg/kg). Airway responsiveness to inhaled histamine (PC(200)) and bronchoalveolar lavage were assessed before, immediately and 5 h after ozone exposure. Ozone caused a significant airway hyperresponsiveness immediately after exposure, which persisted after 5 h. Neither JTE-522 nor indomethacin affected airway hyperresponsiveness immediately after ozone exposure, but significantly attenuated airway hyperresponsiveness 5 h after exposure, suggesting that cyclooxygenase-2 may participate in the late phase of airway hyperresponsiveness but not in the early phase. Ozone caused a significant increase in the concentration of prostaglandin E(2) and thromboxane B(2) in bronchoalveolar lavage fluid immediately after exposure, which decreased to the basal level 5 h after exposure. This increase in prostaglandin E(2) and thromboxane B(2) was significantly inhibited by JTE-522. An expression of cyclooxygenase-2 was detected not only after ozone exposure but also before, and there was no difference in the number of cyclooxygenase-2-positive cells at any time point. An exogenously applied thromboxane A(2) mimetic, U-46619 (10(-5) M), induced airway hyperresponsiveness 5 h after inhalation, but not immediately or 3 h after inhalation. These data suggest that cyclooxygenase-2 may be constitutively expressed before ozone exposure in guinea pig airway and may synthesize prostaglandin E(2) and thromboxane A(2) transiently under ozone stimulation and that thromboxane A(2) may, in turn, induce the late phase of airway hyperresponsiveness.

Anti-allodynic effects of oral COX-2 selective inhibitor on postoperative pain in the rat

PURPOSE

To examine the effect of a cyclooxygenase (COX)-2 inhibitor on the maintenance of mechanical allodynia induced by skin incision (an animal model of postoperative incident pain) in the rat. Also, to compare the effect of a COX-2 inhibitor with that of a nonselective COX-1 and COX-2 inhibitor and B2 receptor antagonist.

METHODS

A 1 cm longitudinal skin incision was made in the plantar aspect of the foot. JTE522 (1-100 mg x kg(-1)), a COX-2 inhibitor, indomethacin (1-30 mg x kg(-1)), a nonselective COX-1 and COX-2 inhibitor, or FR173657 (10 and 100 mg x kg(-1)), a bradykinin B2 receptor antagonist, was administered orally five minutes after the end of the surgery. The level of mechanical allodynia was assessed by measuring the frequency of foot withdrawal in response to the application of a 12.5 g on Frey filament at 2, 4, 6, 8 and 24 hr after the drug administration.

RESULTS

Oral administration of JTE522 or indomethacin attenuated the maximum response frequency in a dose-dependent manner at a dose between 1 and 30 mg x kg(-1) (P < 0.05). Oral FR 173657, (100 mg x kg(-1)), had no effect on the maximum response frequency.

CONCLUSION

These data indicated that a COX-2 inhibitor attenuated the level of mechanical allodynia in the rat model of postoperative pain.

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.

Inhibition of haematogenous metastasis of colon cancer in mice by a selective COX-2 inhibitor, JTE-522

It is proposed that non-steroidal anti-inflammatory drugs (NSAIDs) reduce colorectal tumorigenesis by inhibition of cyclooxygenase (COX). COX is a key enzyme in the conversion of arachidonic acid to prostaglandins and two isoforms of COX have been characterized, COX-1 and COX-2. Multiple studies have shown that COX-2 is expressed at high levels in colorectal tumours and play a role in colorectal tumorigenesis. Recently it has been reported that selective inhibition of COX-2 inhibits colon cancer cell growth. In this study we investigated the effect of a selective COX-2 inhibitor (JTE-522) on haematogenous metastasis of colon cancer. For this purpose, we selected a murine colon cancer cell line, colon-26, that constitutively expresses the COX-2 protein. The subclone P expressed a high level of COX-2 and the subclone 5 expressed a low level. The colon-26 subclones were injected into the tail vein of BALB/c mice. JTE-522 was given intraperitoneally every day from the day prior to cancer cell injection, and the mice were sacrificed 16 days after cell injection. Lung metastases were compared between groups with and without JTE-522. In the mice injected with subclone P, the number of lung metastatic nodules was significantly reduced in the treated group. However, in the mice injected with subclone 5, there was little difference between the control and the treated groups. These results indicate that there may be a direct link between inhibition of haematogenous metastasis of colon cancer and selective inhibition of COX-2, and that selective COX-2 inhibitors may be a novel class of therapeutic agents not only for colorectal tumorigenesis but also for haematogenous metastasis of colon cancer.

A selective cyclooxygenase-2 inhibitor suppresses tumor growth in nude mouse xenografted with human head and neck squamous carcinoma cells

The anti-tumor effect of a selective cyclooxygenase (COX)-2 inhibitor, JTE-522, was examined with the human head and neck squamous cell carcinoma cell line KB. KB cells do not produce prostaglandin (PG)-E2. In vitro, JTE-522 induced an increase of G1 phase-arrested cells, suppression of platelet-derived growth factor (PDGF) production and inhibition of telomerase activity. No cytotoxic effect was detected. In vivo, the growth of the tumor xenografted into nude mice was significantly suppressed by JTE-522. Suppression of angiogenesis at the periphery of the tumor, increase of G1-arrested cells and suppression of telomerase activity were observed, together with an increase of apoptotic cell death in the tumor. Immunological enhancement did not play a role. We concluded that the anti-tumor effect of JTE-522 was caused by anti-angiogenesis action, cell cycle arrest and inhibition of telomerase activity of the tumor cells. These combined effects might induce apoptosis.

Interpreting the clinical significance of the differential inhibition of cyclooxygenase-1 and cyclooxygenase-2

The International Consensus Meeting on the Mode of Action of COX-2 Inhibition (ICMMAC) brought together 17 international experts in arthritis, gastroenterology and pharmacology on 5 6 December 1997. The meeting was convened to provide a definition of COX-2 specificity and to consider the clinical relevance of COX-2-specific agents. These compounds are a new class of drugs that specifically inhibit the enzyme COX-2 while having no effect on COX-1 across the whole therapeutic dose range. The objectives of the meeting were to review the currently available data regarding the roles and biology of COX-1 and COX-2, and to foster a consensus definition on COX-2 specificity. At the present time, no guidelines exist for the in vitro and in vivo assessment of COX specificity, and it was felt that consensus discussion might clarify some of these issues. The meeting also reviewed recent clinical data on COX-2-specific inhibitors. The following article reflects discussion at this meeting and provides a consensus definition of COX-2-specific inhibitors.

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

Inhibitory activity and the mechanism of action of JTE-522 (4-(4-cyclohexyl-2-methyloxazol-5-yl)-2-fluorobenzenesulfonamid e), a novel selective cyclooxygenase (COX)-2 inhibitor, on human COX-1 and COX-2 were investigated and compared with those of reference compounds. In an enzyme assay, JTE-522 inhibited yeast-expressed human recombinant COX-2 with an IC50 value of 0.085 microM. In contrast, JTE-522 did not inhibit human COX-1 prepared from human platelets at concentrations up to 100 microM. In a cell-based assay, JTE-522 diminished lipopolysaccharide-induced prostaglandin E2 production in human peripheral blood mononuclear cells (COX-2) (IC50 value = 15.1 nM). On the other hand, JTE-522 was less potent at inhibiting calcium ionophore-induced thromboxane B2 production in washed human platelets (COX-1) (IC50 value = 6210 nM). JTE-522 showed highly selective inhibition of human COX-2, and its activity was more selective than that of other COX-2 inhibitors (NS-398 and SC-58635). Human recombinant COX-2 activity was attenuated by JTE-522 in a dose-dependent and time-dependent manner. In contrast, the inhibitory activity of JTE-522 on human COX-1 was not affected by preincubation time. COX-2 inhibition by JTE-522 could not be recovered by gel filtration. These results indicate that JTE-522 is a highly selective, time-dependent and irreversible inhibitor of human COX-2.

Effects of JTE-522, a specific inhibitor of cyclooxygenase-2, on the recurrence of allergic inflammation in rats

JTE-522, 4-(4-cyclohexyl-2-methyloxazol-5-yl)-2-fluorobenzenesulfonamide , is a selective inhibitor of cyclooxygenase-2 at the enzyme level (IC50 is 6.4 x 10(-7) M for sheep cyclooxygenase-2, but it does not inhibit sheep cyclooxygenase-1 at concentrations up to 10(-4) M). In rat peritoneal macrophages in culture, it markedly inhibited cyclooxygenase-2-dependent prostaglandin E2 production and weakly inhibited cyclooxygenase-1-dependent prostaglandin E2 production, as did the selective cyclooxygenase-2 inhibitor NS-398 ([N-2(cyclohexyloxy-4-nitrophenyl)]-methanesulfonamide). In addition, the anti-inflammatory activity of JTE-522 was evaluated, using a model of recurrent air pouch-type allergic inflammation in rats. JTE-522, injected into the pouch just after a second antigen challenge, suppressed the accumulation of pouch fluid, the infiltration of leukocytes and the prostaglandin E2 content in the pouch fluid, as did NS-398 and indomethacin. These findings indicated that JTE-522 is a selective cyclooxygenase-2 inhibitor in cell culture systems and that the suppression by JTE-522 of the recurrence of allergic inflammation is due to the inhibition of cyclooxygenase-2.