Selective Cyclooxygenase-2 Inhibitor Celecoxib Research Articles

Cyclooxygenase-2 (COX-2) Inhibitors Reduce Immune Tolerance through Indoleamine 2,3-dioxygenase (IDO)

Purpose: Cyclooxygenase-2 (COX-2) and its metabolite, PGE2 affect multiple tumorigenesis, including angiogenesis, invasion, and tumor-induced immune suppression. Their overexpression is association with impaired immune cell function in many tumors. Indoleamine 2,3-dioxygenase (IDO) is an emerging immuno-regulatory enzyme that can catalyze the initial rate-limiting step in tryptophan catabolism, by causing tryptophan depletion can block T lymphocyte activation, and thus, enable tumor cells to escape from immune system. Although the potential of immunosuppression associated with tumorproduced COX-2 has been suggested, the mechanism of immunosuppression in tumor immunology is not yet well defined. Thus, we hypothesized that the tumor immunity of COX-2 could be partly due to IDO-dependent immune tolerance. To test this hypothesis, we evaluated IDO expression in cancer cells treated with selective COX-2 inhibitor. Materials and Methods: The A549 human adenocarcinoma cell line, murine Lewis lung carcinoma (LLC) cell line and C57Bl/6 mice were used for in vitro and in vivo studies. In vitro studies, A549 cells were treated with various concentrations of COX-2 inhibitor (PTPBS) or PGE 2. IDO enzyme activity and protein expression were checked by IDO enzyme activity assay and Western blotting. In vivo study, the 20 mice were randomized into normal control, LLC inoculated control, and low and high selective COX-2 inhibitor (celecoxib 25 or 250 mg/kg/day) treated LLL inoculated mice groups (n=5 per group). At one month, mice were sacrificed and tumor mass was isolated for quantification of IDO expression by immunohistochemical stain and western blotting. Results: In vitro studies, PTPBS treated A549 cells showed a significant decreased in IDO enzyme activity and expression but PGE 2 treated A549 cells showed increased in IDO expression. In vivo studies, the tumor mass and lung metastasis were attenuated by celecoxib (respectively, p＜0.05, p＜0.01). Compared with the LLC inoculated control group, mice treated with celecoxib had significant reductions in IDO expression of tumor mass (IDO immunohistochemical stain and western blotting ). Conclusion: The present study reveals that COX-2 inhibitor serves to restore the tumor-induced IDO expression and promotes antitumor reactivity in an immunocompetent murine lung cancer model. These findings further support the suggestion that COX-2 inhibitor is a potential pharmacological immunotherapy in cancer. (J Lung Cancer 2007;6(1):15 �� 23)

Radiosensitization of human glioma cells by cyclooxygenase-2 (COX-2) inhibition: Independent on COX-2 expression and dependent on the COX-2 inhibitor and sequence of administration

Purpose: Patients with a malignant glioma have a very poor prognosis. Cyclooxygenase-2 (COX-2) protein is regularly upregulated in gliomas and might be a potential therapeutic target. The effects of three selective COX-2 inhibitors were studied on three human glioma cell lines.Materials and methods: The selective COX-2 inhibitors NS-398, Celecoxib and Meloxicam and three human glioma cell lines (D384, U251 and U87) were used. Cell growth was assessed by a proliferation assay, the interaction with radiation (0 – 6 Gy) was studied using the clonogenic assay and cell cycle distribution was determined by FACS (fluorescence-activated cell sorting) analysis.Results: All COX-2 inhibitors reduced proliferation of the glioma cell lines irrespective of their COX-2 expression level. Incubation with 200 μM NS-398 24 h before radiation enhanced radiation-induced cell death of D384 cells and 750 μM Meloxicam resulted in radiosensitization of D384 and U87 cells. No radiosensitization was observed with COX-2 inhibitor administration after radiotherapy. Treatment of D384 with NS-398 (200 μM) or Celecoxib (50 μM) and U87 with NS-398 (200 μM) after radiation resulted even in radioprotection.Conclusions: Effectiveness of COX-2 inhibitors on cell proliferation and radio-enhancement was independent of COX-2 protein expression. The sequence of COX-2 inhibitor addition and irradiation is very important.

Cyclooxygenase inhibition lowers prostaglandin E2 release from articular cartilage and reduces apoptosis but not proteoglycan degradation following an impact load in vitro

This study investigated the release of prostaglandin E2 (PGE2) from cartilage following an impact load in vitro and the possible chondroprotective effect of cyclooxygenase-2 (COX-2) inhibition using non-steroidal anti-inflammatory drugs (NSAIDs).Explants of human articular cartilage were subjected to a single impact load in a drop tower, and then cultured for 6 days in the presence of either a selective COX-2 inhibitor (celecoxib; 0.01, 0.1, 1.0 and 10 μM) or a non-selective COX inhibitor (indomethacin; 0.1 and 10 μM). The concentrations of PGE2 and glycosaminoglycans (GAGs), a measure of cartilage breakdown, were measured in the explant culture medium at 3 and 6 days post-impact. Apoptotic cell death was measured in frozen explant sections by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) method.PGE2 levels were increased by more than 20-fold in the medium of explants at both 3 (p = 0.012) and 6 days (p = 0.004) following impact, compared with unloaded controls. In the presence of celecoxib and indomethacin, the PGE2 levels were reduced in a dose-related manner. These inhibitors, however, had no effect in reducing the impact-induced release of GAGs from the cartilage matrix. Addition of celecoxib and indomethacin significantly reduced the number of trauma-induced apoptotic chondrocytes in cartilage explant sections.In this study, a marked increase in PGE2 was measured in the medium following an impact load on articular cartilage, which was abolished by the selective COX-2 inhibitor, celecoxib, and non-selective indomethacin. These inhibitors reduced chondrocyte apoptosis but no change was observed in the release of GAGs from the explants, suggesting that the COX/PGE2 pathway is not directly responsible for cartilage breakdown following traumatic injury. Our in vitro study demonstrates that it is unlikely that COX-2 inhibition alone would slow down or prevent the development of secondary osteoarthritis.

The Selective Cyclooxygenase-2 Inhibitor Celecoxib Reduces Bone Resorption, but not Bone Formation, in Ovariectomized Mice in Vivo

Suppression of increased bone resorption is an important issue in treatment of post-menopausal osteoporosis. Celecoxib is a highly selective inhibitor of cyclooxygenase-2 (COX-2), and inhibits osteoclastogenesis in vitro. In the present study, to test whether celecoxib can suppress elevated bone resorption caused by estrogen deficiency in vivo, celecoxib (4 mg/kg) or its vehicle was administered to sham-operated or ovariectomized (OVX) mice (model of post-menopausal osteoporosis). The treatment with celecoxib or vehicle was started immediately after the sham operation or ovariectomy, and lasted for 4 weeks. At 2 and 4 weeks after surgery, OVX mice administered vehicle had significantly higher levels of C-telopeptide, a marker of bone resorption in serum, than sham-operated mice administered vehicle (37% and 60% higher, respectively; p<0.01). At 2 and 4 weeks after surgery, celecoxib treatment significantly decreased serum C-telopeptide levels in OVX mice, but not in sham-operated mice (45% and 41%, respectively; p<0.001). In contrast, in both sham-operated and OVX mice, celecoxib did not significantly affect serum osteocalcin levels (a marker of bone formation) or bone mineral density (BMD) of the femur, which was evaluated by peripheral quantitative computed tomography (pQCT). In conclusion, treating OVX mice with celecoxib significantly suppressed the increase in serum levels of the bone resorption marker, but did not affect levels of the bone formation marker. Also, celecoxib did not prevent the decrease of femoral BMD in OVX mice. The present study suggests the possibility that celecoxib may be used to prevent bone loss caused by estrogen deficiency.

Nitric oxide deficiency promotes vascular side effects of cyclooxygenase inhibitors

AbstractThe cardiovascular safety of COX-2 selective and nonselective nonsteroidal anti-inflammatory drugs (NSAIDs) has recently been called into question. The factors that predispose to adverse events by NSAIDs are unknown. Because patients with arthritis have decreased nitric oxide (NO) bioavailability, the in vivo effects of NSAIDs on murine vascular tone and platelet activity in the presence or absence of NO were examined. Here, we show that acute hypertensive and prothrombotic activities of the COX-2–selective inhibitor celecoxib are revealed only after in vivo inhibition of NO generation. The nonselective NSAID indomethacin was hypertensive but antithrombotic when NO was absent. In vitro myography of aortic rings confirmed that vasoconstriction required inhibition of both NOS and COX-2 and was abolished by supplementation with exogenous NO. These data indicate that NO suppresses vascular side effects of NSAIDs, suggesting that risk will be greatest in patients with impaired vascular function associated with decreased NO bioavailability.

Cardiovascular and Cerebrovascular Events in the Randomized, Controlled Alzheimer's Disease Anti-Inflammatory Prevention Trial (ADAPT)

Objectives:The Alzheimer's Disease Anti-inflammatory Prevention Trial (ADAPT) was designed to evaluate the conventional NSAID naproxen sodium and the selective COX-2 inhibitor celecoxib for primary prevention of Alzheimer's dementia (AD). On 17 December 2004, after the Adenoma Prevention with Celecoxib (APC) trial reported increased cardiovascular risks with celecoxib, the ADAPT Steering Committee suspended treatment and enrollment. This paper reports on cardiovascular and cerebrovascular events in ADAPT.Design:ADAPT is a randomized, placebo-controlled, parallel chemoprevention trial with 1–46 mo of follow-up.Setting:The trial was conducted at six field sites in the United States: Baltimore, Maryland; Boston, Massachusetts; Rochester, New York; Seattle, Washington; Sun City, Arizona; and Tampa, Florida.Participants:The 2,528 participants were aged 70 y and older with a family history of AD.Interventions:Study treatments were celecoxib (200 mg b.i.d.), naproxen sodium (220 mg b.i.d.), and placebo.Outcome measures:Outcome measures were deaths, along with nonfatal myocardial infarction (MI), stroke, congestive heart failure (CHF), transient ischemic attack (TIA), and antihypertensive treatment recorded from structured interviews at scheduled intervals. Cox proportional hazards regression was used to analyze these events individually and in several composites.Results:Counts (with 3-y incidence) of participants who experienced cardiovascular or cerebrovascular death, MI, stroke, CHF, or TIA in the celecoxib-, naproxen-, and placebo-treated groups were 28/717 (5.54%), 40/713 (8.25%), and 37/1070 (5.68%), respectively. This yielded a hazard ratio (95% confidence interval [CI]) for celecoxib of 1.10 (0.67–1.79) and for naproxen of 1.63 (1.04–2.55). Antihypertensive treatment was initiated in 160/440 (47.43%), 147/427 (45.00%), and 164/644 (34.08%). This yielded hazard ratios (CIs) of 1.56 for celecoxib (1.26–1.94) and 1.40 for naproxen (1.12–1.75).Conclusions:For celecoxib, ADAPT data do not show the same level of risk as those of the APC trial. The data for naproxen, although not definitive, are suggestive of increased cardiovascular and cerebrovascular risk.

Risk of Cardiovascular Events in Patients Receiving Celecoxib: A Meta-Analysis of Randomized Clinical Trials

Some nonsteroidal anti-inflammatory drugs (NSAIDs), including cyclooxygenase-2 selective inhibitors, have been associated with increased cardiovascular (CV) events in recent clinical trials or observational studies. To determine whether the cyclooxygenase-2 selective inhibitor celecoxib affects CV risk, the incidence of CV events was analyzed in patients treated with celecoxib, placebo, or nonselective NSAIDs in the clinical trial database for celecoxib using defined Antiplatelet Trialists' Collaboration end points of nonfatal myocardial infarction, nonfatal stroke, and CV death. Patient data were derived from studies in osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, low back pain, and Alzheimer's disease. This meta-analysis included (1) 7,462 patients exposed to celecoxib 200 to 800 mg/day for 1,268 patient-years compared with 4,057 patients treated with placebo for 585 patient-years, and (2) 19,773 patients treated with celecoxib 200 to 800 mg/day for 5,651 patient-years compared with 13,990 patients treated with nonselective NSAIDs (diclofenac, ibuprofen, naproxen, ketoprofen, and loxoprofen) for 4,386 patient-years. CV events were adjudicated by a 3-member expert end point committee (WBW, JSB, PBG) blinded to treatment group and study. The incidence rates of the combined CV events were not significantly different between patients treated with celecoxib and placebo or between those treated with celecoxib and nonselective NSAIDs. Event rates were similar for adjudicated and nonadjudicated data. Dose of celecoxib, the use of aspirin, or the presence of CV risk factors did not alter these results. In conclusion, these analyses failed to demonstrate an increased CV risk with celecoxib relative to placebo and demonstrated a comparable rate of CV events with celecoxib treatment compared with nonselective NSAIDs.

Efficacy of celecoxib in the treatment of CNS lymphomas: an in vivo model

The incidence of primary central nervous system lymphomas (PCNSLs) has increased over the past several decades. Unfortunately, even with the most effective therapeutic regimen (that is, methotrexate with wholebrain radiation therapy), PCNSL recurs within a few years in more than half of the treated patients and is eventually fatal. Because PCNSL usually occurs in older patients and in those with acquired immunodeficiency syndrome, combination treatments in which both chemo- and radiation therapy are used is often poorly tolerated and results in a significant reduction in the quality of life. Recently, it has been demonstrated that the selective cyclooxygenase- 2 inhibitor celecoxib (Celebrex), can block the growth of lymphoma cells in vitro. To create an experimental animal model in vivo for the PCNSL study, the authors intracranially injected a human B-cell lymphoma cell line into nude mice. Their data demonstrate that this experimental model is an excellent one for human PCNSL with brain and leptomeningeal involvement. They also evaluated the feasibility of using celecoxib as a therapeutic agent in the treatment of PCNSL. Nude mice with intracranial lymphomas were treated with celecoxib contained in the animal chow. The treated animals demonstrated significantly prolonged survival times compared with the untreated animals. Based on the authors' data, celecoxib may be a promising therapeutic agent for the treatment of PCNSL.

Cyclooxygenase-2 directly regulates gene expression of P450 Cyp19 aromatase promoter regions pII, pI.3 and pI.7 and estradiol production in human breast tumor cells

The present studies evaluated the direct effects of the presence of human cyclooxygenase-2 (Cox-2) on gene expression of specific promoter regions of the P450 Cyp19 enzyme aromatase enzyme and its product, estradiol, in Cox-2 null estrogen-dependent MCF-7 breast tumor cells and in a stable clone of MCF-7 cells containing transfected Cox-2 cDNA, designated as MCF-7/Cox-2 Clone 10. Clone 10 human breast tumor cells have significantly increased gene expression of total mRNA of the P450 Cyp19 enzyme aromatase, with high levels of gene expression of specific aromatase promoter (p) regions pII, pI.3, and p1.7, with no significant change in mRNA levels of p1.4. Clone 10 human breast tumor cells produced significantly increased amounts of both prostaglandin E 2 (PGE 2) derived from Cox-2 enzyme activity and estradiol derived from aromatase enzyme activity ( p < 0.01), compared to MCF-7/vector control cells. The greatest inhibition of PGE 2 or estradiol production was observed by the combination of the selective Cox-2 inhibitor celecoxib (25 μM) and the aromatase inhibitor, formestane (10 nM) ( p < 0.01). The greatest anti-proliferative effect in Cox-2 null MCF-7/vector control cells was observed with the combination of 25 μM celecoxib and 10 nM formestane but not with 10 μM celecoxib, suggesting that there are Cox-2-independent mechanisms involved in the anti-proliferative effect of this agent at doses greater than 10 μM. Celecoxib (25 μM) also significantly inhibited proliferation of MCF-7/Cox-2 Clone 10 human breast tumor cells, with no further anti-proliferative activity with the addition of 10 nM formestane observed at either 24 or 48 h of treatment. These studies demonstrate that Cox-2 directly regulates gene expression of specific aromatase promoter regions and regulates aromatase enzyme activity. Agents that inhibit Cox-2 or block the biological effects of PGE 2 may be useful in significantly limiting aromatase activity and proliferation of human breast tumor cells regardless of the presence of Cox-2. In addition, the unique human breast tumor cell model used in these studies may be a useful tool in identifying the spectrum of activities of agents that block the biological effects of PGE 2 and estradiol.

Cyclooxygenase-2 plays an essential part in cardioprotection of delayed phase of recombinant human erythropoietin preconditioning in rats

Aims: To study the cardioprotection of recombinant human erythropoietin (rhEPO) preconditioning (EPC) and to investigate the role and possible mechanism of cyclooxygenase (COX)-2 in the delayed phase of EPC. Methods:...

Synthesis and biological evaluation of a novel class of rofecoxib analogues as dual inhibitors of cyclooxygenases (COXs) and lipoxygenases (LOXs)

A group of 4-(4-methanesulfonylphenyl)-3-phenyl-2(5H)furanones possessing an acetyl, 3-oxobut-1-ynyl, [hydroxyl(or alkoxy)imino]alkyl, [hydroxyl(or alkoxy)imino]alkynyl, and N-alkoxy(or N-phenoxy)carbonyl-N-hydroxy-N-ethylamino substituents at the para-position of the C-3 phenyl ring of rofecoxib were synthesized. This group of compounds was designed for evaluation as dual inhibitors of cyclooxygenases (COXs) and lipoxygenases (LOXs) that exhibit in vivo anti-inflammatory and analgesic activities. In vitro COX-1/COX-2, and 5-LOX/15-LOX, isozyme inhibition structure–activity relationships identified 3-[4-(1-hydroxyimino)ethylphenyl]-4-(4-methanesulfonylphenyl)-2(5H)furanone (17a) having an optimal combination of COX-2 (COX-2 IC50=1.4μM; COX-2 SI>71), and 5-LOX and 15 LOX (5-LOX IC50=0.28μM; 15-LOX IC50=0.32μM), inhibitory effects. It was also discovered that 3-[4-(3-hydroxyiminobut-1-ynyl)phenyl]-4-(4-methanesulfonylphenyl)-2(5H)furanone (18a) possesses dual COX-2 (IC50=2.7μM) and 5-LOX (IC50=0.30μM) inhibitor actions. Further in vivo studies employing a rat carrageenan-induced paw edema model showed that the oxime compounds (17a, 18a) were more potent anti-inflammatory agents than the 5-LOX inhibitor caffeic acid, and 15-LOX inhibitor nordihydroguaiaretic acid (NDGA), but less potent than the selective COX-2 inhibitor celecoxib. The results of this investigation showed that incorporation of a para-oxime moiety on the C-3 phenyl ring of rofecoxib provides a suitable template for the design of dual inhibitors of the COX and LOX enzymes.

Selective COX-2 inhibitor celecoxib prevents experimental autoimmune encephalomyelitis through COX-2-independent pathway

Cyclooxygenase (COX) is a key enzyme of arachidonic acid metabolism and exists as two distinct isoforms. COX-1 is constitutively expressed in most tissues, whereas COX-2 is inducibly expressed at the site of inflammation. Selective inhibitors of COX-2 have been developed and have been used as anti-inflammatory agents. Here, we show that a new-generation COX-2 inhibitor, celecoxib, inhibited experimental autoimmune encephalomyelitis (EAE). Celecoxib, but not other COX-2 inhibitors such as nimesulid, prevented myelin oligodendrocyte glycoprotein (MOG) induced EAE when administrated orally on the day of disease induction. Moreover, celecoxib inhibited EAE in COX-2-deficient mice, indicating that celecoxib inhibited EAE in a COX-2-independent manner. In celecoxib-treated mice, interferon-gamma (IFN-gamma) production from MOG-specific T cells was reduced and MOG-specific IgG1 was elevated compared with vehicle-treated mice. Infiltration of inflammatory cells into the central nervous system and the expression of adhesion molecules, P-selectin and intercellular adhesion molecule-1 (ICAM-1), and a chemokine, monocyte chemoattractant peptide-1 (MCP-1), were inhibited when mice were treated with celecoxib. These results suggest that celecoxib may be useful as a new additional therapeutic agent for multiple sclerosis.

Changes in Antitumor Response in C57BL/6J-Min/+ Mice during Long-term Administration of a Selective Cyclooxygenase-2 Inhibitor

Selective cyclooxygenase-2 (COX-2) inhibitors are widely prescribed for severe arthritis and are currently under study in human chemoprevention trials. Recently, long-term use of these agents has come under scrutiny due to reports of treatment-associated cardiovascular toxicity. On short-term administration, the selective COX-2 inhibitor celecoxib inhibits adenoma growth in animal tumor models, including the C57BL/6J-Min/+ (Min/+) mouse. With uninterrupted long-term celecoxib administration, intestinal tumors in Min/+ mice initially regressed and then recurred to levels comparable with untreated controls. Celecoxib treatment initially suppressed COX-2 and prostaglandin E2 (PGE2) expression, but long-term use produced significantly higher levels of these molecules and reactivated PGE2-associated growth factor signaling pathways in tumor and normal tissues. These results indicate that COX-2 is an important chemoprevention target and that inhibition of this enzyme alters a paracrine enterocyte regulatory pathway. Chronic uninterrupted celecoxib treatment, however, induces untoward effects that enhance early progression events in intestinal tumorigenesis and may contribute to treatment toxicity.

Accounting for the increase in NSAID expenditure: substitution or leakage?

BackgroundNational Institute of Health and Clinical Excellence (NICE) guidance stated that a new form of non-steroidal anti-inflammatory drug (NSAID) (selective COX-2 inhibitors) should only be an option for arthritis patients at high risk of a gastro-intestinal (GI) event. Total expenditure on NSAIDs has risen by 57% over five years, to £247 million in 2004. We assess whether this expenditure increase can be accounted for by substitution – an increased prescribing of two (more expensive) selective COX-2 inhibitors (celecoxib and rofecoxib) and a simultaneous equivalent reduction in the prescribing volume of three (cheaper) older NSAIDs (diclofenac, ibuprofen and naproxen).MethodsQuarterly prescription data was collated from January 1999 to September 2004. Over this period, the level of correlation between the total prescribing volumes for i) celecoxib and rofecoxib, and ii) diclofenac, ibuprofen, and naproxen were compared, the change in total expenditure on the five NSAIDs was also estimated. The latter was apportioned into that which was estimated to have arisen due to i) substitution, and ii) increased NSAID prescription volume.ResultsTotal prescription volumes for the two NSAID groups were negatively correlated (r = -0.97, p < 0.001). In the last quarter there were 1.23 million prescriptions for celecoxib and rofecoxib, and 0.46 million fewer prescriptions for naproxen, diclofenac, and ibuprofen (than in the first quarter, when celecoxib and rofecoxib were not prescribed). Total expenditure for the five NSAIDs was £32.7 million higher in the last quarter, than the first, £12.2 million of which was estimated to be due to substitution, and £20.4 million due to increased volume.ConclusionThe introduction of celecoxib and rofecoxib was associated with a reduction in the prescription volume for naproxen, diclofenac, and ibuprofen. However, overall quarterly prescription volume for these five NSAIDs increased by 0.76 million, and we estimate that quarterly expenditure increased by £20.4 million more than would have been expected if overall NSAID volume had remained constant. This suggests that the prescription of both celecoxib and rofecoxib may have 'leaked' to population groups who would not previously have received an older NSAID.

Detection of Overexpressed COX‐2 in Precancerous Lesions of Hamster Pancreas and Lungs by Molecular Imaging: Implications for Early Diagnosis and Prevention

The enzyme cyclooxygenase-2 (COX-2) is overexpressed in many cancers, cardiovascular disease, neurodegenerative disorders, and arthritis. Selective inhibitors of COX-2 have been developed as therapeutics or preventive agents for these diseases. However, recent reports have revealed a significant increase in cardiovascular mortality in long-term users of the COX-2 inhibitors Vioxx and Celebrex, emphasizing the need for noninvasive tests that allow the identification of individuals whose COX-2 levels are overexpressed prior to assignment to treatment with these drugs. In this study, we have prepared a radioiodinated analogue of the selective COX-2 inhibitor celecoxib, and verified its binding to the COX-2 enzyme in vitro. Biodistribution studies in hamsters demonstrated significantly higher levels of radiotracer in animals treated with the tobacco carcinogen NNK in lung, pancreas, and liver. Assessment of COX-2 levels by whole-body planar nuclear imaging two hours after injection of the radiotracer was suggestive of a distinct increase in COX-2 in the pancreas and liver of a hamster treated for 10 weeks with NNK, in the lungs and liver of a second animal, and in the liver only, in two additional animals from the same treatment group. Immunostains showed selective overexpression of COX-2 in pre-neoplastic lesions of the pancreas and lungs in only those animals that showed tracer accumulation in these organs and in the livers of all NNK-treated hamsters. Immunostains for COX-1 yielded detectable reactions in the intestinal epithelium but not in pancreas, lungs, or liver, supporting the specificity of the tracer for COX-2. Our data provide proof of principle for the hypothesis that molecular imaging with radiolabeled COX-2 inhibitors can be used for the noninvasive monitoring of overexpressed COX-2 levels.

Downregulation of survivin expression and concomitant induction of apoptosis by celecoxib and its non-cyclooxygenase-2-inhibitory analog, dimethyl-celecoxib (DMC), in tumor cells in vitro and in vivo

Background2,5-Dimethyl-celecoxib (DMC) is a close structural analog of the selective cyclooxygenase-2 (COX-2) inhibitor celecoxib (Celebrex®) that lacks COX-2-inhibitory function. However, despite its inability to block COX-2 activity, DMC is able to potently mimic the anti-tumor effects of celecoxib in vitro and in vivo, indicating that both of these drugs are able to involve targets other than COX-2 to exert their recognized cytotoxic effects. However, the molecular components that are involved in mediating these drugs' apoptosis-stimulatory consequences are incompletely understood.ResultsWe present evidence that celecoxib and DMC are able to down-regulate the expression of survivin, an anti-apoptotic protein that is highly expressed in tumor cells and known to confer resistance of such cells to anti-cancer treatments. Suppression of survivin is specific to these two drugs, as other coxibs (valdecoxib, rofecoxib) or traditional NSAIDs (flurbiprofen, indomethacin, sulindac) do not affect survivin expression at similar concentrations. The extent of survivin down-regulation by celecoxib and DMC in different tumor cell lines is somewhat variable, but closely correlates with the degree of drug-induced growth inhibition and apoptosis. When combined with irinotecan, a widely used anticancer drug, celecoxib and DMC greatly enhance the cytotoxic effects of this drug, in keeping with a model that suppression of survivin may be beneficial to sensitize cancer cells to chemotherapy. Remarkably, these effects are not restricted to in vitro conditions, but also take place in tumors from drug-treated animals, where both drugs similarly repress survivin, induce apoptosis, and inhibit tumor growth in vivo.ConclusionIn consideration of survivin's recognized role as a custodian of tumor cell survival, our results suggest that celecoxib and DMC might exert their cytotoxic anti-tumor effects at least in part via the down-regulation of survivin – in a manner that does not require the inhibition of cyclooxygenase-2. Because inhibition of COX-2 appears to be negligible, it might be worthwhile to further evaluate DMC's potential as a non-coxib alternative to celecoxib for anti-cancer purposes.

A Phase II Study with Antioxidants, Both in the Diet and Supplemented, Pharmaconutritional Support, Progestagen, and Anti-Cyclooxygenase-2 Showing Efficacy and Safety in Patients with Cancer-Related Anorexia/Cachexia and Oxidative Stress

To test the efficacy and safety of an integrated treatment based on a pharmaconutritional support, antioxidants, and drugs, all given orally, in a population of advanced cancer patients with cancer-related anorexia/cachexia and oxidative stress. An open early-phase II study was designed according to the Simon two-stage design. The integrated treatment consisted of diet with high polyphenols content (400 mg), antioxidant treatment (300 mg/d alpha-lipoic acid + 2.7 g/d carbocysteine lysine salt + 400 mg/d vitamin E + 30,000 IU/d vitamin A + 500 mg/d vitamin C), and pharmaconutritional support enriched with 2 cans per day (n-3)-PUFA (eicosapentaenoic acid and docosahexaenoic acid), 500 mg/d medroxyprogesterone acetate, and 200 mg/d selective cyclooxygenase-2 inhibitor celecoxib. The treatment duration was 4 months. The following variables were evaluated: (a) clinical (Eastern Cooperative Oncology Group performance status); (b) nutritional [lean body mass (LBM), appetite, and resting energy expenditure]; (c) laboratory [proinflammatory cytokines and leptin, reactive oxygen species (ROS) and antioxidant enzymes]; (d) quality of life (European Organization for Research and Treatment of Cancer QLQ-C30, Euro QL-5D, and MFSI-SF). From July 2002 to January 2005, 44 patients were enrolled. Of these, 39 completed the treatment and were assessable. Body weight increased significantly from baseline as did LBM and appetite. There was an important decrease of proinflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-alpha, and a negative relationship worthy of note was only found between LBM and IL-6 changes. As for quality of life evaluation, there was a marked improvement in the European Organization for Research and Treatment of Cancer QLQ-C30, Euro QL-5D(VAS), and multidimensional fatigue symptom inventory-short form scores. At the end of the study, 22 of the 39 patients were "responders" or "high responders." The minimum required was 21; therefore, the treatment was effective and more importantly was shown to be safe. The efficacy and safety of the treatment have been shown by the study; therefore, a randomized phase III study is warranted.

Cyclooxygenase-2 selective inhibition suppresses restoration of tibial trabecular bone formation in association with restriction of osteoblast maturation in skeletal reloading after hindlimb elevation of mice

To clarify the role of cyclooxygenase-2 (COX-2) in acute recovery of trabecular bone in reloaded hindlimbs of tail-suspended mice, we administered a COX-2 selective inhibitor in the mice during the reloading period after unloading. Experiments were conducted on 140 male C57BL/6J mice (8 weeks old). They were divided into ground control (GC) and unloading by tail suspension (UL) groups. On day 7, Group GC was divided into Groups GC + Vehicle (Veh) and GC + Celecoxib (Cel), while Group UL mice were fed on the ground [reloading (RL)] after 7-day unloading and were then divided into Groups RL + Veh and RL + Cel. Bone histomorphometry, osteogenic cell development, and mRNA expression of osteogenic molecules were assessed. At 5 days after reloading, the increase of bone formation rate and the ratio of osteocalcin mRNA expression per CFU-f colony in Group RL + Cel were significantly decreased compared with those in Group RL + Veh, while alkaline phosphatase-positive (ALP +) CFU-f formation and the ratios of cbfa-1, osterix, and type 1 collagen mRNA expression per CFU-f colony increased to the same levels in both RL groups. At 14 days after reloading, decreased bone volume by unloading in RL + Veh recovered to the same level as that of GC + Veh, but that in RL + Cel did not recover completely. The increase of c -fos mRNA expression in bone marrow cells at 1, 24, and 48 h after reloading, osteocalcin mRNA at 6 h, and osterix mRNA at 24 h were suppressed by COX-2 inhibitor. These data indicate that the COX-2 selective inhibitor celecoxib suppresses the restoration of tibial trabecular bone formation and the acute recovery of trabecular bone. These actions are closely related to restriction of c- fos and osteocalcin mRNA expressions and osteoblast differentiation in bone marrow cells.

The selective Cox-2 inhibitor Celecoxib suppresses angiogenesis and growth of secondary bone tumors: An intravital microscopy study in mice

BackgroundThe inhibition of angiogenesis is a promising strategy for the treatment of malignant primary and secondary tumors in addition to established therapies such as surgery, chemotherapy, and radiation. There is strong experimental evidence in primary tumors that Cyclooxygenase-2 (Cox-2) inhibition is a potent mechanism to reduce angiogenesis. For bone metastases which occur in up to 85% of the most frequent malignant primary tumors, the effects of Cox-2 inhibition on angiogenesis and tumor growth remain still unclear. Therefore, the aim of this study was to investigate the effects of Celecoxib, a selective Cox-2 inhibitor, on angiogenesis, microcirculation and growth of secondary bone tumors.MethodsIn 10 male severe combined immunodeficient (SCID) mice, pieces of A549 lung carcinomas were implanted into a newly developed cranial window preparation where the calvaria serves as the site for orthotopic implantation of the tumors. From day 8 after tumor implantation, five animals (Celecoxib) were treated daily with Celecoxib (30 mg/kg body weight, s.c.), and five animals (Control) with the equivalent amount of the CMC-based vehicle. Angiogenesis, microcirculation, and growth of A549 tumors were analyzed by means of intravital microscopy. Apoptosis was quantified using the TUNEL assay.ResultsTreatment with Celecoxib reduced both microvessel density and tumor growth. TUNEL reaction showed an increase in apoptotic cell death of tumor cells after treatment with Celecoxib as compared to Controls.ConclusionCelecoxib is a potent inhibitor of tumor growth of secondary bone tumors in vivo which can be explained by its anti-angiogenic and pro-apoptotic effects. The results indicate that a combination of established therapy regimes with Cox-2 inhibition represents a possible application for the treatment of bone metastases.

R(+)-Methanandamide Elicits a Cyclooxygenase-2-Dependent Mitochondrial Apoptosis Signaling Pathway in Human Neuroglioma Cells

Cannabinoids have been associated with tumor regression and apoptosis of cancer cells. Recently, we have shown that R(+)-methanandamide (R(+)-MA) induces apoptosis of H4 human neuroglioma cells via a mechanism involving de novo expression of the cyclooxygenase-2 (COX-2) enzyme. The present study investigated a possible involvement of a mitochondrial-driven pathway in this process. Cell death was determined by the WST-1 cell viability test, and changes in apoptotic parameters [i.e., release of mitochondrial cytochrome c, activation of caspases, cleavage of poly(ADP-ribose) polymerase (PARP)] were detected by Western blotting. H4 cells treated with R(+)-MA showed typical signs of mitochondrial apoptosis, i.e., release of mitochondrial cytochrome c into the cytosol and activation of initiator caspase-9. Moreover, activation of the executor caspase-3 was observed following cannabinoid treatment. Cells were fully protected from apoptotic cell death by the caspase-3 inhibitor Ac-DEVD-CHO, indicating a crucial role for caspase-3 activation in R(+)-MA-elicited apoptosis. Furthermore, cleavage of the caspase-3 target protein PARP was registered. All of the aforementioned effects were substantially reduced by the selective COX-2 inhibitor celecoxib (1 muM) at a pharmacologically relevant, nonapoptotic concentration. R(+)-MA-induced apoptosis is mediated via a mitochondrial-dependent pathway that becomes activated, at least in part, through up-regulation of the COX-2 enzyme.