Selective Cyclooxygenase-2 Inhibitor Nimesulide Research Articles

Acute heat trauma model in rats, gender-dependent thermoresistance, and screening of potential thermoprotectors

Heat trauma (HT) is an urgent medical and social problem. Heat damage is a widespread effect of the environment on humans, driven by global warming, military conflicts, technological disasters, work in hot environments, and engagement in extreme sports and tourism. The aim of the study: to propose a model of acute HT in rats that does not cause the death of animals, to determine the dependence of thermoresistance on gender, and to compare the effectiveness of the thermoprotective effects of a range of non-steroidal anti-inflammatory drugs (NSAIDs), paracetamol, and glucosamine hydrochloride in this model. Materials and Methods: The experiment was conducted on adult white rats of both genders. Acute HT was modelled by using a specially developed method involving heat exposure to animals at +55 °C for 30 minutes, followed by a recovery period of 60 minutes. Rectal temperature was measured every 15 minutes. The degree of hyperthermia in males and females was determined. The presence and intensity of the thermoprotective effect of glucosamine hydrochloride (G h/ch), diclofenac sodium, acetylsalicylic acid (ASA), nimesulide, etoricoxib, celecoxib, and paracetamol were evaluated through intragastric administration 60 minutes before heat exposure. The results were analyzed using the STATISTICA 12.0 program. Results: It was established that heat exposure at +55 °C for 30 minutes effectively replicates acute HT in rats without causing animal fatalities, adhering to bioethical requirements. Body temperature increases by 10-13 %, characterized as a heat stroke. Occasionally, thermoresistant animals are encountered, where the temperature increase during the first 15 minutes of exposure is less than 1 °C. These animals should not be used for further modelling of heat trauma. Male rats are more sensitive to the effect of high environmental temperatures than females, exhibiting greater hyperthermia (temperature increase of 5.03±0.39°C compared to 3.72±0.22 °C in females, p<0.01). The thermoprotective effect of glucosamine hydrochloride depends on gender, being more pronounced in males. Among the 6 tested COX inhibitors, the most significant thermoprotective effect was observed in the highly selective COX-2 inhibitor celecoxib and the weakly selective central inhibitor paracetamol, warranting in-depth research into their impact on organ and system states following heat trauma, as well as the mechanisms of their thermoprotective action. The thermoprotective effect is not associated with selectivity towards COX (cyclooxygenase): it is not observed in the highly selective COX-2 inhibitor etoricoxib and moderately selective COX-2 inhibitor nimesulide, as well as in non-selective COX inhibitors such as diclofenac sodium and aspirin, which also slows down the recovery of body temperature after heat exposure. Conclusions: A convenient and simple model of acute HT in rats is proposed, demonstrating higher thermosensitivity and a more pronounced thermoprotective effect of glucosamine hydrochloride in males. A significant thermoprotective effect was identified in celecoxib and paracetamol, surpassing other investigated NSAIDs. The mechanism and specific features of this effect require further clarification

Chronic cyclooxygenase-2 inhibition prevents the worsening of hypertension and endothelial dysfunction induced by ouabain in resistance arteries of spontaneously hypertensive rats

AimPrevious studies raise cyclooxygenase (COX) activation as a possible mechanism involved in the pathophysiology of ouabain-induced hypertension. We hypothesized that inhibition of COX-2 activity might prevent ouabain-induced vascular dysfunction and worsening of hypertension in spontaneously hypertensive rats (SHR). MethodsSHR were exposed to ouabain or vehicle and treated or not with the selective COX-2 inhibitor nimesulide for 5 weeks. Systolic blood pressure was measured by plethysmography. Vascular reactivity by wire myograph and protein expression by Western-blot were assessed in mesenteric resistance arteries (MRA) of groups. Thromboxane A2 (TXA2) production by ELISA was evaluated in MRA supernatants of groups. ResultsNoradrenaline-induced maximal contraction (Emax) was greater in MRA from SHR receiving ouabain than those of vehicle group. In situ inhibition of COX-2, TXA2 synthase, or TP receptor reduced the Emax to noradrenaline in MRA of ouabain to vehicle levels. TXA2 production was higher in ouabain than in vehicle group. Ouabain enhanced expression of cytoplasmic tyrosine kinase Src (c-Src)/ERK1/2/COX-2/TXA2 synthase/TP receptor in SHR MRA, but did not change NFkB/iKB ratio. Anticontractile effect of nitric oxide (NO) was smaller in MRA from ouabain- than vehicle-treated SHR, as well as eNOS and nNOS expression. Nimesulide co-treatment prevented the ouabain-induced worsening of hypertension and noradrenaline MRA hypercontractility in SHR. ConclusionOuabain worsen hypertension and induce MRA hypercontractility in SHR associated with upregulated c-Src/ERK1/2/COX-2/TXA2 synthase/TXA2/TP receptor axis. These effects were prevented by COX-2 inhibition.

COX-2 plays a role in angiogenic DBA+ uNK cell subsets activation and pregnancy protection in LPS-exposed mice

IntroductionAlthough uterine Natural Killer (uNK) cells have cytoplasmic granules rich in perforin and granzymes, these cells do not degranulate in normal pregnancy. DBA lectin+ uNK cells produce angiogenic factors which stimulate remodeling of uterine arterioles to increase blood flow within the growing feto-placental unit. We sought to investigate the importance of COX-2 on mouse pregnancy inoculated with Gram-negative bacteria Lipopolysaccharide (LPS) by treating with a selective COX-2 inhibitor (nimesulide). MethodsWe have combined histochemical, immunohistochemical, stereological, morphometric, behavioral, and litter analyses to investigate mouse pregnancy inoculated with LPS with or without pre-treatment with nimesulide 30 min before LPS injections, focusing on DBA+ uNK cell response and viability of the pregnancy. ResultsLPS caused sickness behavior, an immature DBA+ uNK influx, decreased mature DBA+ uNK cell numbers, and triggered a new DBAlow uNK appearance. These effects of LPS, except the sickness behavior, were prevented by nimesulide. COX-2 inhibition also prevented the down-regulation of uNK perforin and spiral arteriole α-actin expression stimulated by LPS. While the litter size from Nimesulide + LPS-treated mothers was significantly smaller compared to those from LPS-treated group, nimesulide alone showed no effect on the offspring. DiscussionCollectively, our data indicate that COX-2 changes angiogenic DBA+ uNK cells in order to protect mouse pregnancy after LPS injection.

Role of phosphorylated extracellular signal-regulated kinase, calcitonin gene-related peptide and cyclooxygenase-2 in experimental rat models of migraine.

Although migraine is a common neurological condition, the pathomechanism is not yet fully understood. Activation of the trigeminovascular system (TVS) has an important function in this disorder and neurogenic inflammation and central sensitization are important mechanisms underlying this condition. Nitroglycerin (NTG) infusion in rats closely mimics a universally accepted human model of migraine. Electrical stimulation of the trigeminal ganglion (ESTG) of rats can also activate TVS during a migraine attack. Numerous studies have revealed that phosphorylated extracellular signal-regulated kinase (p-ERK), calcitonin gene-related peptide (CGRP) and cyclooxygenase-2 (COX-2) are involved in pain and nociceptive pathways. However, few studies have examined whether p-ERK, CGRP and COX-2 are involved in neurogenic inflammation and central sensitization. In the present study, the expression of p-ERK, CGRP and COX-2 was detected in the dura mater, trigeminal ganglion (TG) and spinal trigeminal nucleus caudalis in NTG-induced rats and ESTG models by immunohistochemistry. The three areas considered were crucial components of the TVS. The selective COX-2 inhibitor nimesulide was used in ESTG rats to examine the association between p-ERK, CGRP and COX-2. The results demonstrated that p-ERK, CGRP and COX-2 mediated neurogenic inflammation and central sensitization in migraine. In addition, the expression of p-ERK and CGRP was attenuated by the COX-2 inhibitor.

Cyclooxygenase-1 inhibition attenuates angiotensin II-salt hypertension and neurogenic pressor activity in the rat

Cyclooxygenase (COX)-derived prostanoids contribute to angiotensin II (ANG II) hypertension (HTN). However, the specific mechanisms by which prostanoids act are unclear. ANG II-induced HTN is caused partly by increased sympathetic nervous system activity, especially in a setting of high dietary salt intake. This study tested the hypothesis that COX-derived prostanoids cause ANG II-salt sympathoexcitation and HTN. Experiments were conducted in conscious rats. Infusion of ANG II (150 ng·kg(-1)·min(-1) sc) caused a marked HTN in rats on 2% salt diet, but a much smaller increase in blood pressure in rats on 0.4% salt diet. The nonselective COX inhibitor ketoprofen (2 mg/kg sc) given throughout the ANG-II infusion period attenuated HTN development in rats on 2% NaCl diet, but not in rats on 0.4% NaCl diet. The acute depressor response to ganglion blockade was used to assess neurogenic pressor activity in rats on 2% NaCl diet. Ketoprofen-treated rats showed a smaller fall in arterial pressure in response to ganglion blockade during ANG-II infusion than did nontreated controls. In additional experiments, ketoprofen-treated rats exhibited smaller increases in plasma norepinephrine levels and whole body norepinephrine spillover than we previously reported in ANG II-salt HTN. Finally, the effects of the selective COX-1 inhibitor SC560 (10 mg·kg(-1)·day(-1) ip) and the selective COX-2 inhibitor nimesulide (10 mg·kg(-1)·day(-1) ip) were investigated. Treatment with SC560 but not nimesulide significantly reduced blood pressure and the depressor response to ganglion blockade in ANG II-salt HTN rats. The results suggest that COX-1 products are critical for sympathoexcitation and the full development of ANG II-salt HTN in rats.

Effect and mechanism of nimesulide combined with cisplatin on proliferation and apoptosis of lung cancer

Objective To evaluate the effects of selective cyclooxygenase-2 inhibitor nimesulide lone and combined with cisplatin on tumor growth,and Ki67 and Caspase-3 expression in lung cancer xenografts in nude mice. Methods The mice were randomly divided into 4 groups:the control group,the nimesulide group,the cisplatin group and the nimesulide combined with cisplatin group. A549 cells were injected into BALB/c nude mice subcutaneously.On the 21st day after treatment tumor tissues were collected,and the xenografts growth were observed. The expression of Ki67 and Caspase-3 were detected by immunohistochemical method.Results Nimesulide combined with cisplatin could significantly inhibited the xenografts growth compared with nimesulide or cisplatin.The tumor inhibition rate was 44.33％ in the nimesulide group,53.61％ in the cisplatin group and 80.41％ in the nimesulide combined with cisplatin group (P ＜ 0.05).Immunohistochemical analysis showed that the expression rates of Caspase-3 was significantly increased in the nimesulide combined with cisplatin group (67.43 ± 23.57 ) ％,the cisplatin group (48.40 ± 20.37 ) ％,and the nimesulide group (38.65 ± 15.37)％,compared with the control group (27.63 ± 13.03)％ (P ＜ 0.05).The expression rate of Caspase-3 was significantly increased in the nimesulide combined with cisplatin group compared with the nimesulide group or the cisplatin group (P ＜ 0.05 ).The expression rate of Ki67 was significantly decreased in the nimesulide group combined with cisplatin group (24.34 ± 15.90)％,the cisplatin group (40.85 ± 22.47)％ and the nimesulide group (53.33 ± 19.67)％ compared with the control group ( 80.43 ± 16.88 ) ％ ( P ＜ 0.05 ).The expression of Ki67 was significantly decreased in the nimesulide combined with cisplatin group compared with the nimesulide group or the cisplatin group ( P ＜ 0.05 ).Conclusion Nimesulide can inhibit human lung cancer A549 cells xenografts in nude mice growth,Nimesulide enhanced the inhibitory effects of cisplatin.The mechanism may be related to inhibition of tumor cell Ki-67 expression,increased expression of Caspase-3,inhibition of tumor cell proliferation,and inducing tumor cell apoptosis. Key words: Lung neoplasms ; Cisplatin ; Cell proliferation ; Apoptosis ; Nimesulide

Endothelium-dependent contraction induced by acetylcholine in the chicken ductus arteriosus involves cyclooxygenase-1 activation and TP receptor stimulation

In numerous vascular beds, acetylcholine (ACh) evokes the simultaneous release of endothelium-derived relaxing and contracting factors (EDRF and EDCF, respectively). We aimed to determine whether ACh evokes the release of an EDCF in the chicken ductus arteriosus (DA) and to identify its nature. Isolated rings DA from 19-d chicken embryos (total incubation: 21-d) were studied in a wire myograph. Low concentrations of ACh (30 nM–1 µM) elicited a relaxation, which was followed by a contraction at higher concentrations (3 µM–0.1 mM). Both relaxation and contraction were abolished by removal of endothelium and were sensitive to the antimuscarinic agents atropine and 4-DAMP (M 3-receptor antagonist). ACh-induced contraction was impaired in the presence of the non-selective inhibitor of cyclooxygenase (COX) indomethacin, the selective COX-1 inhibitor valeryl salicylate, and the thromboxane (TX)/prostaglandin (PG) H 2 (TP) receptor blocker SQ-29458, whereas the response was not affected by the selective COX-2 inhibitor nimesulide, the TX synthase inhibitor furegrelate, the H 2O 2 scavenger PEG-catalase, the nitric oxide synthase inhibitor L-NAME, or the soluble guanylate cyclase inhibitor ODQ. Enzyme immunoassay determined that, under basal conditions, the chicken DA produced PGE 2, PGF 2α and TXB 2 (stable metabolite of TXA 2). Prostanoid production was inhibited by indomethacin but was not significantly affected by ACh. We conclude that in the chicken DA, stimulation of muscarinic receptors by ACh induces an endothelium-dependent relaxation followed by an endothelium-dependent contraction. The contraction involves COX-1 activation and TP receptor stimulation.

Cyclooxygenase-2 Derived PGE2 and PGI2 Play an Important Role Via EP2 and PPARδ Receptors in Early Steps of Oil Induced Decidualization in Mice

Differentiation of endometrial stromal cells into decidual cells (decidualization) is prerequisite for blastocyst implantation. Different prostanoids are shown to be involved in the cascade of events found in implantation and decidualization. Previous reports described that cyclooxygenase-2 (COX2) derived prostacyclin (PGI2) plays an important role via peroxisome proliferator activated receptor (PPARδ) nuclear receptor in implantation and decidualization. Herein, we investigated the role of COX2 derived PGE2 and PGI2 and examined the protein expression and regulation of COX1, COX2, membrane-bound prostaglandin E synthase (mPGES-1), prostaglandin I synthase (PGIS), PGE2 receptor (EP2) and PPARδ in hormone primed oil infused uterine horn as well as in non-infused uterine horn (control horn). Our results show that selective COX2 inhibitor (Nimesulide) inhibits decidualization while COX1 inhibitor (SC560) does not affect decidualization. COX2, mPGES-1, PGIS, EP2 and PPARδ immunostaining are strongly observed at 24 h and 48 h in oil-induced horn and than significantly reduced at 72 h and 120 h and absent in non-infused horn. However COX1 immunostaining is observed in infused as well as in non-infused horn. Our immunohistochemical studies corroborated well with follow up western blotting of the same proteins. PGE2 and PGI2 products were also elevated at 24 h and 48 h after oil induction in infused horn in comparison to control horn. Our data suggest that COX2 derived both PGE2 and PGI2 mediate its function via EP2 and PPARδ receptors in early steps of decidualization in mice.

Effects of cyclooxygenase inhibition on canine coronary artery blood flow and thrombosis

This study was designed to determine the effect of inhibitors of cyclooxygenase (COX)-1, COX-2, and the nonselective COX inhibitor naproxen on coronary vasoactivity and thrombogenicity under baseline and lipopolysaccharide (LPS)-induced inflammatory conditions. We hypothesize that endothelial COX-1 is the primary COX isoform in the canine normal coronary artery, which mediates arachidonic acid (AA)-induced vasodilatation. However, COX-2 can be induced and overexpressed by inflammatory mediators and becomes the major local COX isoform responsible for the production of antithrombotic prostaglandins during systemic inflammation. The interventions included the selective COX-1 inhibitor SC-560 (0.3 mg/kg iv), the selective COX-2 inhibitor nimesulide (5 mg/kg iv), or the nonselective COX inhibitor naproxen (3 mg/kg iv). The selective prostacyclin (IP) receptor antagonist RO-3244794 (RO) was used as an investigational tool to delineate the role of prostacyclin (PGI(2)) in modulating vascular reactivity. AA-induced vasodilatation of the left circumflex coronary artery was suppressed to a similar extent by each of the COX inhibitors and RO. The data suggest that AA-induced vasodilatation in the normal coronary artery is mediated by a single COX isoform, the constitutive endothelial COX-1, which is reported to be susceptible to COX-2 inhibitors. The effect of the COX inhibitors on thrombus formation was evaluated in a model of carotid artery thrombosis secondary to electrolytic-induced vessel wall injury. Pretreatment with LPS (0.5 mg/kg iv) induced a systemic inflammatory response and prolonged the time-to-occlusive thrombus formation, which was reduced in the LPS-treated animals by the administration of nimesulide. In contrast, neither SC-560 nor naproxen influenced the time to thrombosis in the animals pretreated with LPS. The data are of significance in view of reported adverse cardiovascular events observed in clinical trials involving the use of selective COX-2 inhibitors, thereby suggesting that the endothelial constitutive COX-1 and the inducible vascular COX-2 serve important functions in maintaining vascular homeostasis.

Effect of cyclooxygenase on “window of implantation” in mouse

The major determinants of uterine receptivity are the ovarian progesterone and estrogen hormones, respectively. Different prostaglandins (PGs) have been elucidated in reproduction and also in this process of implantation in various ways. The blastocyst undergoes implantation on the uterine epithelium in defined hormone prepared period known as “implantation window”. However, any definitive role of PGs in the window of receptivity remains elusive. It is demonstrated herein that selective COX1 inhibitor (SC560) and selective COX2 inhibitor (nimesulide) separately had no significant effect on blastocyst implantation while combination of both inhibitors in lower dose showed partial delay in implantation by more than 24 h and became implanted beyond the window of implantation, i.e. on D6 but these implantation sites were significantly reduced on D10 and the pregnancy is lost in significant number. However, the higher doses of inhibitors in combination completely prevented implantation. Embryos retrieved from these treated mice showed significantly lower number of embryonic cells (77±3.3 and 65.2±3.9) than the optimum number of embryonic cells (93.4±2.6). The lower doses of both the inhibitors reduced uterine PGE 2 and PGI 2 content on D5 but did not inhibit as efficiently as higher doses. In addition, our immunohistochemistry result shows that there was no COX1 and COX2 localization on D5 of treated mice but COX2 begins expressing on D6 like normal D5 of pregnancy. Therefore, we can conclude that embryos implanted after the delay showed defective post-implantation development because of lower number of embryonic cells of implanting blastocyst and implantation beyond the proper time in window of receptivity.

Therapeutic effect of nimesulide on colorectal carcinogenesis in experimental murine ulcerative colitis

Patients with ulcerative colitis (UC) exhibit an increased risk for the development of cancer of the colon and rectum. Cyclooxygenase (COX)-2 inhibitors are known to suppress sporadic colorectal cancer, but it is unknown whether selective COX-2 inhibitors exhibit a preventive effect in UC-associated neoplasia. This study investigated the preventive effect of nimesulide, a selective COX-2 inhibitor, on colorectal carcinogenesis in an experimental model of murine UC. Chronic colitis was induced in mice by administration of four cycles of dextran sulfate sodium (DSS) (each cycle: 5% DSS for 7 days and then distilled water for 14 days). The mice were killed 120 days after the completion of the fourth cycle. The mice were divided into the following five groups: group A served as a disease control; group B received a diet mixed with 400 p.p.m. of nimesulide during the whole period; group C received nimesulide during the four cycles of DSS administration (active phase); group D received nimesulide for 120 days from the end of the fourth cycle (remission phase); group E received no agents including DSS and served as a normal control. The incidence of dysplasia and/or cancer was 28%, 15%, 11.8%, 6.7% and 0% in groups A-E, respectively. In group D, nimesulide significantly suppressed the occurrence of dysplasia and/or cancer (P < 0.05). Strong COX-2 expression was detected by immunohistochemistry in cancer and dysplastic lesions while diffusely weak COX-2 expression was also found in the residual colon (i.e. lesion-free colon). The mucosal concentration of prostaglandin E(2) was significantly lower in groups B and D than in group A. The administration of the selective COX-2 inhibitor nimesulide (especially during the remission phase) exerts a suppressive effect on the development of dysplasia and/or cancer in a murine model of DSS-induced colitis. These findings may have relevance to long-standing UC in humans.

ラット食道腺癌発癌モデルにおけるcyclooxygenase(COX）-2発現と選択的COX-2阻害剤による化学予防の検討

ラット食道腺癌発癌モデルにおけるcyclooxygenase(COX）-2発現と選択的COX-2阻害剤による化学予防の検討

Delayed Progression of Pancreatic Intraepithelial Neoplasia in a Conditional KrasG12D Mouse Model by a Selective Cyclooxygenase-2 Inhibitor

Pancreatic ductal adenocarcinomas are thought to arise from noninvasive, intraductal precursor lesions called pancreatic intraepithelial neoplasias (PanIN). The study of PanINs holds great promise for the identification of early detection markers and effective cancer-preventing strategies. Cyclooxygenase-2 (COX-2) represents an intriguing target for therapeutic and preventive approaches in various human malignancies. The aim of the present study was to evaluate the efficacy of a selective COX-2 inhibitor to prevent the progression of PanINs in a conditional Kras(G12D) mouse model. Offspring of LSL-KRAS(G12D) x PDX-1-Cre intercrosses were randomly allocated to a diet supplemented with the selective COX-2 inhibitor nimesulide (400 ppm) or a control diet. After 10 months, animals were sacrificed. Successful recombination in the pancreas was evaluated by PCR. The pancreas of KRAS(G12D);PDX-1-Cre mice was analyzed for the presence of murine PanINs. Animals fed the COX-2 inhibitor had significantly fewer PanIN-2 and PanIN-3 lesions than control animals (P < 0.05). Ten percent of all pancreatic ducts in the nimesulide-fed animals showed PanIN-2 or PanIN-3 lesions, whereas 40% of the pancreatic ducts in the control animals had PanIN-2 or PanIN-3 lesions. Intrapancreatic prostaglandin E(2) levels were reduced in nimesulide-fed animals. Immunohistochemistry confirmed COX-2 expression in early and late PanINs. In summary, we found that the selective COX-2 inhibitor nimesulide delays the progression of pancreatic cancer precursor lesions in a preclinical animal model. These data highlight the importance of COX-2 in the development of pancreatic cancer. Inhibition of COX-2 may represent an intriguing strategy to prevent pancreatic cancer in high-risk patients.

Inhibition of human Neuroblastoma in SCID mice by low-dose of selective Cox-2 inhibitor Nimesulide

Neuroblastoma is the most common solid tumor of infants and carries a poor prognosis especially in advanced stages. The present recommended therapies carry a high risk of side effects that is associated with long-term morbidity. We evaluated the efficacy of a low dose of the selective cyclooxygenase-2 inhibitor Nimesulide in preventing human Neuroblastoma tumor growth in Severe Combined Immune-deficient mice. Mice containing established tumors (SH-SY5Y cells) treated with 20 mg/kg Nimesulide every 4th day beginning on day 1 of cell injections resulted in a 65% reduction of tumor growth compared to the DMSO treated control mice (P<0.05) but did not significantly reduce tumor growth when Nimesulide was started once tumors reached 1 cm. There was a reduction in the level of cyclooxygenase-2 protein and induction of effecter caspases in tumors treated with Nimesulide. However, there was no change in the levels of X-Inhibitor-of-Apoptosis-Protein, Smac/Diablo, or proteins of the PI3/Akt pathway following Nimesulide treatment. In Conclusion, low doses of Nimesulide can potentially be used as a chemopreventive agent for human Neuroblastoma.

Inhibition of cytotoxicity of cisplatin by cyclooxygenase-2 inhibitor nimesulide in head and neck cancer cell lines

Although head and neck cancer is a common malignancy, investigations have not yet improved the poor prognosis of patients. Therefore, it is important to find new cancer treatment modalities. Recent studies showed that cyclooxygenase, especially its isoform cyclooxygenase-2, is involved in tumorigenesis, tumor growth and metastasis. Inhibition of this enzyme by cyclooxygenase inhibitors has been shown to be antiproliferative in numerous cancer cell lines. The aim of this study was to investigate if the selective cyclooxygenase-2 inhibitor nimesulide could enhance cytotoxicity of the standard chemotherapeutic agent cisplatin. Head and neck squamous cell cancer cells were incubated with nimesulide and/or cisplatin, and counted after 24, 48 and 72 h treatment. Visualization of apoptotic cells was done by immunohistochemistry. We demonstrated that nimesulide inhibits the cytotoxic effect of cisplatin in HNSCC cells. Therefore, COX-2 inhibitor nimesulide may not be a good partner for cisplatin in combination therapy for cancer.

The effect of selective cyclooxygenase-2 inhibitor nimesulide on breast cancer induced by dimethylbenzoic acid in rats

To study the effect of nimesulide (NIM) on the tumorigenesis of mammary tumors induced by dimethylbenzoic acid (DMBA), and to investigate possible mechanisms of NIM against tumors. The studied rats were randomly divided into four groups: experimental control group, NIM group, diet and drug of NIM control group. The incidence of mammary tumor was observed. RT-PCR, Western blot were used to detect 8 cancerous tissues in every group, randomly. The expressions of cylooxygenase-2 (COX-2) were assessed by immunohistochemistry. The levels of prostaglandin E(2) (PGE(2)) in blood plasma and tumor tissues were determined by means of radio-immunity assay. The apoptosis index and the proliferation index were evaluated by TUNEL assay, immunohistochemical staining for proliferating cell nuclear antigen (PCNA), respectively. The incidence of mammary tumor was 69.2% in experimental control group, 40.3% in NIM group. There was obviously decreased incidence in NIM group; The expressions of COX-2 mRNA and protein were significantly down-regulated in NIM group compared with experimental control group. The increased levels of PGE(2) synthesis in blood plasma and tumor tissues were significantly decreased by administering NIM (P < 0.05). The apoptosis index was obviously higher, the proliferation index was markedly less in NIM group than experimental control group. Nimesulide could inhibit the tumorigenesis and development of DMBA-induced mammary tumors by inhibition of proliferation and induction of apoptosis. COX-2 and COX-2-mediated PGE(2) synthesis may play an important role in rat DMBA-induced breast cancer.

Wide therapeutic time window for nimesulide neuroprotection in a model of transient focal cerebral ischemia in the rat

Results from several studies indicate that cyclooxygenase-2 (COX-2) is involved in ischemic brain injury. The purpose of this study was to evaluate the neuroprotective effects of the selective COX-2 inhibitor nimesulide on cerebral infarction and neurological deficits in a standardized model of transient focal cerebral ischemia in rats. Three doses of nimesulide (3, 6 and 12 mg/kg; i.p.) or vehicle were administered immediately after stroke and additional doses were given at 6, 12, 24, 36 and 48 h after ischemia. In other set of experiments, the effect of nimesulide was studied in a situation in which its first administration was delayed for 3–24 h after ischemia. Total, cortical and subcortical infarct volumes and functional outcome (assessed by neurological deficit score and rotarod performance) were determined 3 days after ischemia. The effect of nimesulide on prostaglandin E 2 (PGE 2) levels in the injured brain was also investigated. Nimesulide dose-dependently reduced infarct volume and improved functional recovery when compared to vehicle. Of interest is the finding that neuroprotection conferred by nimesulide (reduction of infarct size and neurological deficits and improvement of rotarod performance) was also observed when treatment was delayed until 24 h after ischemia. Further, administration of nimesulide in a delayed treatment paradigm completely abolished PGE 2 accumulation in the postischemic brain, suggesting that COX-2 inhibition is a promising therapeutic strategy for cerebral ischemia to target the late-occurring inflammatory events which amplify initial damage.

Optimal suppression of thromboxane a2formation by aspirin during percutaneous transluminal coronary angioplasty: no additional effect of a selective cyclooxygenase-2 inhibitor

ObjectivesWe examined the contribution of cyclooxygenase (COX)-1 and -2 to the generation of prostacyclin, thromboxane (Tx) A2, and 8-epi prostaglandin (PG) F2αduring percutaneous transluminal coronary angioplasty (PTCA). BackgroundBoth TxA2and 8-epi PGF2αactivate platelets and are mitogenic, whereas prostacyclin is a platelet inhibitor, and therefore may influence the outcome of PTCA. MethodsTwenty-one patients undergoing PTCA while receiving aspirin 300 mg daily or aspirin plus the selective COX-2 inhibitor nimesulide were compared with 13 patients treated only with fradafiban, a glycoprotein IIb/IIIa antagonist. Urine was analyzed for the metabolites of TxA2(Tx-M) and prostacyclin (PGI-M) and for the isoprostane, 8-epi PGF2α. ResultsIn the fradafiban group, there was a marked increase in Tx-M during PTCA (mean, 1,973; 95% confidence interval [CI] 112 to 3,834 rising to mean 7,645; 95% CI 2,009 to 13,281 pg/mg creatinine, p = 0.018). The Tx-M excretion was similarly reduced by aspirin and the combination of aspirin and nimesulide. In contrast, the combination of nimesulide and aspirin inhibited PGI-M excretion to a greater extent than aspirin (p = 0.001). Urinary 8-epi PGF2αexcretion was elevated following PTCA compared with normal subjects (p = 0.002) and appeared to be unaffected by any of the treatments. ConclusionsThe increase in TxA2during PTCA is primarily COX-1 dependent, and aspirin alone is effective in suppressing its formation. In contrast, prostacyclin generation is both COX-1 and COX-2 dependent. The inhibition of COX-1 and COX-2 did not prevent the production of 8-epi PGF2α, suggesting that this is not enzymatically derived. The persistent generation of 8-epi PGF2αmay contribute to the thrombosis and restenosis that complicate PTCA.

The selective cyclooxygenase-2 inhibitor nimesulide induces apoptosis in pancreatic cancer cells independent of COX-2.

Selective cyclooxygenase-2 (COX-2) inhibition reduces the growth of many cancer cell lines, and this effect may be mediated through induction of apoptosis. This study was designed to investigate the effects of the COX-2 inhibitor nimesulide on the growth of human pancreatic cancer cells. Reverse transcriptase-polymerase chain reaction analysis, northern blotting, and immunoblotting were used to demonstrate COX-2 mRNA and protein in two pancreatic cancer cell lines: BxPC-3 and MIA PaCa-2. The effect of nimesulide on cell growth was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and cell count. Apoptosis was determined by FACS analysis, DNA laddering, and assessment of the floating cell/attached cell ratio. Caspase-3 activation was evaluated by measuring caspase-3 cellular activity and by determining the effects of two caspase inhibitors on cell viability. COX-2 mRNA was detected in both cell lines. Immunoblotting confirmed COX-2 protein expression in only the BxPC-3 cell line. Nimesulide decreased cell viability and inhibited cell growth in both cell lines. Incubation with 100 micromol/L nimesulide increased the fraction of apoptotic cells and the floating cell/attached cell ratio in both cell lines. DNA laddering was observed after incubation with nimesulide for 96 hours. There was no increase in caspase-3 activity within 96 hours. The selective COX-2 inhibitor nimesulide is antimitogenic in pancreatic cancer cells, which is independent of COX-2 expression. This effect in part is mediated by the induction of apoptosis.

Neuroprotective efficacy of nimesulide against hippocampal neuronal damage following transient forebrain ischemia

Cyclooxygenase-2 is involved in the inflammatory component of the ischemic cascade, playing an important role in the delayed progression of the brain damage. The present study evaluated the pharmacological effects of the selective cyclooxygenase-2 inhibitor nimesulide on delayed neuronal death of hippocampal CA1 neurons following transient global cerebral ischemia in gerbils. Administration of therapeutically relevant doses of nimesulide (3, 6 and 12 mg/kg; i.p.) 30 min before ischemia and at 6, 12, 24, 48 and 72 h after ischemia significantly (P<0.01) reduced hippocampal neuronal damage. Treatment with a single dose of nimesulide given 30 min before ischemia also resulted in a significant increase in the number of healthy neurons in the hippocampal CA1 sector 7 days after ischemia. Of interest is the finding that nimesulide rescued CA1 pyramidal neurons from ischemic death even when treatment was delayed until 24 h after ischemia (34±9% protection). Neuroprotective effect of nimesulide is still evident 30 days after the ischemic episode, providing the first experimental evidence that cyclooxygenase-2 inhibitors confer a long-lasting neuroprotection. Oral administration of nimesulide was also able to significantly reduce brain damage, suggesting that protective effects are independent of the route of administration. The present study confirms the ability of cyclooxygenase-2 inhibitors to reduce brain damage induced by cerebral ischemia and indicates that nimesulide can provide protection when administered for up to 24 h post-ischemia.