Karen Seibert

Pfizer Inc., New York City, New York, United States

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Publications (88)454.96 Total impact

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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 12/2010; 26(51). DOI:10.1002/chin.199551108
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    ABSTRACT: In this manuscript, we report the discovery of the substituted 2-trifluoromethyl-2H-benzopyran-3-carboxylic acids as a novel series of potent and selective cyclooxygenase-2 (COX-2) inhibitors. 5c-(S) (SD-8381) was advanced into clinical studies due to its superior in vivo potency. The high plasma protein binding (>99% bound) of 5c-(S) has resulted in a surprisingly long human half life t(1/2)=360 h.
    Bioorganic & medicinal chemistry letters 12/2010; 20(23):7155-8. DOI:10.1016/j.bmcl.2010.07.053 · 2.65 Impact Factor
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 08/2010; 26(34). DOI:10.1002/chin.199534126
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 08/2010; 30(33). DOI:10.1002/chin.199933149
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 08/2010; 30(32). DOI:10.1002/chin.199932122
  • ChemInform 04/2010; 27(18). DOI:10.1002/chin.199618087
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    ABSTRACT: A new class of selective cyclooxygenase-2 (COX-2) inhibitors has been identified by high throughput screening. Structurally distinct from previously described selective COX-2 inhibitors, these benzopyrans contain a carboxylic acid function and CF3 functionality. The compound SC-75,416 is a representative of this class. A range if in vitro and in vivo tests were employed to characterize its potency and selectivity. Using human recombinant enzymes, this compound displays a concentration that provides 50% inhibition (IC50) of 0.25 microM for COX-2 and 49.6 microM for COX-1. A mutation of the side pocket residues in COX-2 to COX-1 had little effect on potency suggesting that these inhibitors bind in a unique manner in COX-2 distinct from COX-2 inhibiting diaryl heterocycles. Using rheumatoid arthritic synovial cells stimulated with interleukin-1beta (IL-1beta) and washed platelets the compound displayed IC50 of 3 nM and 400 nM respectively. Potency and selectivity was maintained but predictably right shifted in whole blood with IC50 of 1.4 microM for lipopolysaccharide (LPS) stimulated induction of COX-2 and >200 microM for inhibition of platelet thromboxane production. SC-75,416 is 89% bioavailable and its in vivo half life is sufficient for once a day dosing. In the rat air pouch model of inflammation, the compound inhibited PGE2 production with an effective dose that provides 50% inhibition (ED50) of 0.4 mg/kg, while sparing gastric prostaglandin E2 (PGE2) production with an ED50 of 26.5 mg/kg. In a model of acute inflammation and pain caused by carrageenan injection into the rat paw, the compound reduced edema and hyperalgesia with ED50s of 2.7 and 4 mg/kg respectively. In a chronic model of arthritis the compound demonstrated an ED50 of 0.081 mg/kg and an ED(80) of 0.38 mg/kg. In a model of neuropathic pain, SC-75,416 had good efficacy. This compound's unique chemical structure and effect on COX enzyme binding and activity as well as its potency and selectivity may prove useful in treating pain and inflammation.
    European Journal of Pharmacology 06/2008; 588(1):93-8. DOI:10.1016/j.ejphar.2008.03.057 · 2.68 Impact Factor
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    ABSTRACT: The discovery of a second isoform of cyclooxygenase (COX) led to the search for compounds that could selectively inhibit COX-2 in humans while sparing prostaglandin formation from COX-1. Celecoxib and rofecoxib were among the molecules developed from these efforts. We report here the pharmacological properties of a third selective COX-2 inhibitor, valdecoxib, which is the most potent and in vitro selective of the marketed COX-2 inhibitors that we have studied. Recombinant human COX-1 and COX-2 were used to screen for new highly potent and in vitro selective COX-2 inhibitors and compare kinetic mechanisms of binding and enzyme inhibition with other COX inhibitors. Valdecoxib potently inhibits recombinant COX-2, with an IC(50) of 0.005 microM; this compares with IC values of 0.05 microM for celecoxib, 0.5 microM for rofecoxib, and 5 microM for etoricoxib. Unique binding interactions of valdecoxib with COX-2 translate into a fast rate of inactivation of COX-2 (110,000 M/s compared with 7000 M/s for rofecoxib and 80 M/s for etoricoxib). The overall saturation binding affinity for COX-2 of valdecoxib is 2.6 nM (compared with 1.6 nM for celecoxib, 51 nM for rofecoxib, and 260 nM for etoricoxib), with a slow off-rate (t(1/2) approximately 98 min). Valdecoxib inhibits COX-1 in a competitive fashion only at very high concentrations (IC(50) = 150 microM). Collectively, these data provide a mechanistic basis for the potency and in vitro selectivity of valdecoxib for COX-2. Valdecoxib showed similar activity in the human whole-blood COX assay (COX-2 IC(50) = 0.24 microM; COX-1 IC(50) = 21.9 microM). We also determined whether this in vitro potency and selectivity translated to significant potency in vivo. In rats, valdecoxib demonstrated marked potency in acute and chronic models of inflammation (air pouch ED(50) = 0.06 mg/kg; paw edema ED(50) = 5.9 mg/kg; adjuvant arthritis ED(50) = 0.03 mg/kg). In these same animals, COX-1 was spared at doses greater than 200 mg/kg. These data provide a basis for the observed potent anti-inflammatory activity of valdecoxib in humans.
    Journal of Pharmacology and Experimental Therapeutics 04/2005; 312(3):1206-12. DOI:10.1124/jpet.104.076877 · 3.86 Impact Factor
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    ABSTRACT: Non-steroidal anti-inflammatory drugs (NSAIDs) specifically inhibit cyclooxygenase (COX) activity and are widely used as anti-arthritics, post-surgical analgesics, and for the relief of acute musculoskeletal pain. Recent studies suggest that non-specific NSAIDs, which inhibit both COX-1 and COX-2 isoforms, delay bone healing. The objectives of this study were 2-fold; first, to measure the relative changes in the normal expression of COX-1 and COX-2 mRNAs over a 42 day period of fracture healing and second, to compare the effects of a commonly used non-specific NSAID, ketorolac, with a COX-2 specific NSAID, Parecoxib (a pro-drug of valdecoxib), on this process. Simple, closed, transverse fractures were generated in femora of male Sprague-Dawley rats weighing approximately 450 g each. Total RNA was prepared from the calluses obtained prior to fracture and at 1, 3, 5, 7, 10, 14, 21, 35 and 42 days post-fracture and levels of COX-1 and COX-2 mRNA were measured using real time PCR. While the relative levels of COX-1 mRNA remained constant over a 21-day period, COX-2 mRNA levels showed peak expression during the first 14 days of healing and returned to basal levels by day 21. Mechanical properties of the calluses were then assessed at 21 and 35 days post-fracture in untreated animals and animals treated with either ketorolac or high or low dose parecoxib. At both 21 and 35 days after fracture, calluses in the group treated with the ketorolac showed a significant reduction in mechanical strength and stiffness when compared with controls (p<0.05). At the 21-day time point, calluses of the parecoxib treated animals showed a lower mean mechanical strength than controls, but the inhibition was not statistically significant. Based on physical analysis of the bones, 3 of 12 (25%) of the ketorolac-treated and 1 of 12 (8%) of the high dose parecoxib-treated animals showed failure to unite their fractures by 21 days, while all fractures in both groups showed union by 35 days. Histological analysis at 21 days showed that the calluses in the ketorolac-treated group contained substantial amounts of residual cartilage while neither the control nor the parecoxib-treated animals showed comparable amounts of cartilage at this stage. These results demonstrate that ketorolac and parecoxib delay fracture healing in this model, but in this study daily administration of ketorolac, a non-selective COX inhibitor had a greater affect on this process. They further demonstrate that a COX-2 selective NSAID, such as parecoxib (valdecoxib), has only a small effect on delaying fracture healing even at doses that are known to fully inhibit prostaglandin production.
    Journal of Orthopaedic Research 07/2003; 21(4):670-5. DOI:10.1016/S0736-0266(03)00003-2 · 2.97 Impact Factor
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    ABSTRACT: Two compounds (celecoxib and valdecoxib) from the diarylheterocycle class of cyclooxygenase inhibitors were radiolabeled and used to characterize their binding to cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2), several single-point variants of COX-2 (Val523Ile, Tyr355Ala, Arg120Ala, Arg120Gln, Arg120Asn) and one triple-point variant of COX-2 [Val523Ile, Arg513His, Val434Ile (IHI)]. We demonstrate highly specific and saturable binding of these inhibitors to COX-2. Under the same assay conditions, little or no specific binding to COX-1 could be detected. The affinity of [(3)H]celecoxib for COX-2 (K(D) = 2.3 nM) was similar to the affinity of [(3)H]valdecoxib (K(D) = 3.2 nM). The binding to COX-2 seems to be both rapid and slowly reversible with association rates of 5.8 x 10(6)/M/min and 4.5 x 10(6)/M/min and dissociation rates of 14 x 10(-3)/min (t(1/2) = 50 min) and 7.0 x 10(-3)/min (t(1/2) = 98 min) for [(3)H]celecoxib and [(3)H]valdecoxib, respectively. These association rates increased (4- to 11-fold) when the charged arginine residue located at the entrance to the main hydrophobic channel was mutated to smaller uncharged amino acids (Arg120Ala, Arg120Gln, and Arg120Asn). Mutation of residues located within the active site of COX-2 that define a 'side pocket' (Tyr355Ala, Val523Ile, IHI) of the main channel had a greater effect on the dissociation rate than the association rate. These mutations, which modified the shape of and access to the 'side pocket', affected the binding affinity of [(3)H]valdecoxib more than that of [(3)H]celecoxib. These binding studies provide direct insight into the properties and binding constants of celecoxib and valdecoxib to COX-2.
    Molecular Pharmacology 05/2003; 63(4):870-7. DOI:10.1124/mol.63.4.870 · 4.12 Impact Factor
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    ABSTRACT: Prostaglandin E(2) (PGE(2)) is the major prostaglandin produced both centrally and in the periphery in models of acute and chronic inflammation, and its formation in both locations is blocked by cyclooxygenase-2 (COX-2) inhibitors such as celecoxib. In animal models of inflammation, PGE(2) inhibition in the brain may occur secondarily to a peripheral action by inhibiting local PG formation that elicits increased firing of pain fibers and consequent activation of PG synthesis in the central nervous system (CNS). Celecoxib was studied in the kainate-induced seizure model in the rat, a model of direct central prostaglandin induction, to determine whether it can act directly in the CNS. In the kainate-treated rat brain there was increased PGE(2), PGF(2alpha), and PGD(2) production, with COX activity and PGE(2) formation increased about 7-fold over normal. We quantitated mRNA levels for enzymes involved in the prostaglandin biosynthetic pathways and found that both COX-2 and PGE synthase (PGEs) mRNA levels were increased in the brain; no changes were found for expression of COX-1 or PGD synthase mRNA. By Western blot analysis, COX-2 and PGEs were induced in total brain, hippocampus, and cortex, but not in the spinal cord. Immunohistological studies showed that COX-2 protein expression was enhanced in neurons. Dexamethasone treatment reduced the expression of both COX-2 and PGEs in kainate-treated animals. Celecoxib reduced the elevated PGE(2) levels in brain of kainate-treated rats and inhibited induced COX activity, demonstrating the ability of this compound to act on COX-2 in CNS. Doses of celecoxib that inhibited brain COX-2 were lower than those needed for anti-inflammatory activity in adjuvant arthritis, demonstrating a potent direct central action of the compound.
    Journal of Pharmacology and Experimental Therapeutics 10/2002; 302(3):846-52. DOI:10.1124/jpet.302.3.846 · 3.86 Impact Factor
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    ABSTRACT: To examine cyclooxygenase-2 (COX-2) enzyme expression, its regulation by interleukin-1 beta (IL-1 beta), and the role of prostaglandin E(2) (PGE(2)) in proteoglycan degradation in human osteoarthritic (OA) cartilage. Samples of human OA articular cartilage, meniscus, synovial membrane, and osteophytic fibrocartilage were obtained at knee arthroplasty and cultured ex vivo with or without IL-1 beta and COX inhibitors. COX expression was evaluated by immunohistochemistry and Western blot analysis. The enzymatic activity of COX was measured by conversion of arachidonic acid to PGE(2). Cartilage degradation was evaluated by measuring the accumulation of sulfated glycosaminoglycans in the medium. IL-1 beta induced robust expression of COX-2 and PGE(2) in OA meniscus, synovial membrane, and osteophytic fibrocartilage explants, whereas low levels were produced in OA articular cartilage. IL-1 beta also induced cartilage proteoglycan degradation in OA synovial membrane-cartilage cocultures. Increased proteoglycan degradation corresponded to the induction of COX-2 protein expression in, and PGE(2) production from, the synovial membrane. Dexamethasone, neutralizing IL-1 beta antibody, or the selective COX-2 inhibitor, SC-236, attenuated both the IL-1 beta-induced PGE(2) production and cartilage proteoglycan degradation in these cocultures. The addition of PGE(2) reversed the inhibition of proteoglycan degradation caused by SC-236. IL-1 beta-induced production of COX-2 protein and PGE(2) was low in OA articular cartilage compared with that in the other OA tissues examined. IL-1 beta-mediated degradation of cartilage proteoglycans in OA synovial membrane-cartilage cocultures was blocked by the selective COX-2 inhibitor, SC-236, and the effect of SC-236 was reversed by the addition of exogenous PGE(2). Our data suggest that induction of synovial COX-2-produced PGE(2) is one mechanism by which IL-1 beta modulates cartilage proteoglycan degradation in OA.
    Arthritis & Rheumatology 08/2002; 46(7):1789-803. DOI:10.1002/art.10356 · 7.87 Impact Factor
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    ABSTRACT: To understand the potential role of cyclooxygenase (COX) in normal and inflammatory human diseases, we characterized the expression of COX-1 and COX-2 in biopsies of osteoarthritis, atherosclerosis, and cancer. Tissues were prepared for immunohistochemistry by standard methods, and representative cases assayed via Western blot and quantitative RT-PCR. COX-2 was not detected in normal human tissues with few exceptions. Moderate to marked COX-2 was observed in the macula densa (MD) and thick ascending limb (TAL) in human fetal kidneys, but was not detected in neonatal and adult MD and TALs. Low level, constitutive COX-2 was detected in colonic epithelium, peribronchial glands, and pancreatic ductal epithelium. Low to moderate COX-2 was detected basally in the cortex, hippocampus, hypothalamus, and spinal cord, and in reproductive tissues during ovulation, implantation and labor. No COX-2 was detected in the existing vasculature in normal tissues, and was also not expressed throughout the ductus arteriosus. COX-2 was markedly induced in human tissues of osteoarthritis, atherosclerosis and cancer. COX-2 was prominently expressed in the synovium, fibrocartilage of osteophytes, and in the blood vessels in the osteoarthritic (OA) knee joint. COX-2 was also prominently detected in the macrophages/foam cells in atherosclerotic plaques, and in the endothelium overlying and immediately adjacent to the fibrofatty lesion. Moderate- to intense COX-2 expression was consistently observed in the inflammatory cells, neoplastic lesions, and blood vessels in all epithelial-derived human cancers studied. In contrast, COX-1 was relatively ubiquitously observed in both normal and pathophysiological conditions. These data collectively imply COX-2 plays an important role in mediating a variety of inflammatory diseases, and imply COX-2 inhibitors may be effective in the prevention and/or treatment of OA, heart disease, and epithelial cancers.
    Advances in Experimental Medicine and Biology 02/2002; 507:177-84. · 2.01 Impact Factor
  • Advances in Experimental Medicine and Biology 02/2002; 507:365-9. · 2.01 Impact Factor
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    ABSTRACT: Cyclooxygenase (COX) performs the critical initial reaction in the arachidonic metabolic cascade, leading to formation of proinflammatory prostaglandins, thromboxanes, and prostacyclins. The discovery of a second COX isoform (COX-2) associated with inflammation led to agents that selectively inhibit COX-2. Cyclooxygenase-2 inhibitors are also being developed for canine applications. To assess the compound potency on canine enzymes, canine COX-1 and COX-2 were cloned, expressed, and purified. Cyclooxygenase-1 was cloned from a canine kidney complementary DNA (cDNA) library, with 96 % sequence homology to human COX-1. Cyclooxygenase-2 was cloned from canine kidney and lipopolysaccharide-stimulated macrophage cDNA libraries, with a 93 % sequence homology to human COX-2. The arachidonic acid Michaelis constants for canine COX-1 and COX-2 were 4.8 and 6.6 micrometer, respectively, compared with 9.6 and 10.2 micrometer for ovine. Inhibition results indicated that, for all compounds tested, there was no significant difference between potencies determined for canine enzymes and those for human enzymes.
    Veterinary therapeutics: research in applied veterinary medicine 02/2002; 3(3):270-80. · 1.69 Impact Factor
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    ABSTRACT: Increased prostaglandins (PGs) are associated with many inflammatory pathophysiological conditions; and are synthesized from arachidonic acid by either of 2 enzymes, cyclooxygenase-1 (COX-1) or -2 (COX-2). Recent epidemiologic, expression, and pharmacologic studies suggest COX-2 derived metabolites also play a functional role in the maintenance of tumor viability, growth and metastasis. Archival and/or prospectively collected human tissues were prepared for immunohistochemistry, and representative cases assayed via Western blot, RT-PCR, or TAQman analysis. Consistent overexpression of COX-2 was observed in a broad range of premalignant, malignant, and metastatic human epithelial cancers. COX-2 was detected in ca. 85% of the hyperproliferating, dysplastic, and neoplastic epithelial cells, and in the existing and angiogenic vasculature within and adjacent to hyperplastic/neoplastic lesions. These data collectively imply COX-2 may play an important role during premalignant hyperproliferation, as well as the later stages of invasive carcinoma and metastasis in various human epithelial cancers.
    Prostaglandins Leukotrienes and Essential Fatty Acids 02/2002; 66(1):13-8. DOI:10.1054/plef.2001.0335 · 1.98 Impact Factor
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    ABSTRACT: Cyclo-oxygenase (COX) enzymes are the targets for non-steroidal anti-inflammatory drugs (NSAIDs). These drugs demonstrate a variety of inhibitory mechanisms, which include simple competitive, as well as slow binding and irreversible inhibition. In general, most NSAIDs inhibit COX-1 and -2 by similar mechanisms. A unique class of diarylheterocyclic inhibitors has been developed that is highly selective for COX-2 by virtue of distinct inhibitory mechanisms for each isoenzyme. Several of these inhibitors, with varying selectivity, have been utilized to probe the mechanisms of COX inhibition. Results from analysis of both steady-state and time-dependent inhibition were compared. A generalized mechanism for inhibition, consisting of three sequential reversible steps, can account for the various types of kinetic behaviour observed with these inhibitors.
    Biochemical Journal 09/2001; 357(Pt 3):709-18. DOI:10.1042/0264-6021:3570709 · 4.78 Impact Factor
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    ABSTRACT: Recent chemopreventive studies in our laboratories showed that the COX-2 inhibitor, celecoxib, inhibited the induction of mammary cancer by 7,12-dimethylbenz(a)anthracene (DMBA). In this study, we examined the relative chemopreventive effect of varying doses of celecoxib on the development and growth of DMBA-induced rat mammary tumors. At 10 days prior to receiving a single intragastric dose of 15 mg DMBA/rat, female Sprague-Dawley rats were fed a control chow diet or diets containing 250, 500, 1000 or 1500 ppm celecoxib until termination of the experiment. Administration of increasing doses of celecoxib inhibited mammary tumor incidence and multiplicity as well as tumor volume in a dose-dependent manner. At 122 days post DMBA-intubation, mammary tumor incidence was 100% in the control rats compared to 80%, 50%, 45% and 25% in rats receiving 250, 500, 1000 or 1500 ppm celecoxib, respectively (p<0.001). Similarly, tumor multiplicity and tumor volume were significantly reduced by increasing the dose of celecoxib from 250 to 1500 ppm in the diet. The control rats had an average of 3.46 tumors/rat compared to 1.80, 1.00, 0.75 and 0.50 tumors/rat in animals receiving 250, 500, 1000 or 1500 ppm celecoxib, respectively (p<0.001). Average tumor volumes in rats fed 250, 500, 1000 or 1500 ppm celecoxib were 0.42, 0.34, 0.31 and 0.16 cm3 compared to 1.29 cm3 in the control rats (p<0.001). There was a concomitant increase in the steady-state serum concentration of celecoxib with the dose. These results indicate that, in this rat model, the chemopreventive effect of celecoxib against breast cancer is dose-dependent and that celecoxib is effective even at lower dose levels.
    Anticancer research 01/2001; 21(5):3425-32. · 1.87 Impact Factor
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    ABSTRACT: Epidemiological and experimental studies have shown that non-steroidal anti-inflammatory drugs (NSAIDs) reduce the relative risk of human cancer, including breast cancer. Recently, research studies in our laboratories have shown that the selective cyclooxygenase-2 (COX-2) blocker, Celecoxib, given daily in the diet, significantly inhibited the induction of rat mammary tumors by 7, 12-dimethylbenz(a)anthracene (DMBA). These studies were extended to evaluate Celecoxib for its effectiveness as an antineoplastic agent in this rat mammary tumor model. We examined the growth inhibitory effects of Celecoxib, given daily in the diet, on the volume and the number of established mammary tumors, vis-a-vis the cancer load (CL). Tumors continued to grow actively in control rats fed chow diet only. In contrast, the Celecoxib-supplemented diet (1500 mg/kg diet) significantly decreased the size of the mammary tumors in rats over the 6 week treatment period, resulting in an average reduction in tumor volume of approximately 32%, relative to the baseline volume (p<0.04). At the end of the 6 week treatment period, average tumor volume was 1.45 cm3 and 0.13 cm3 in the control and Celecoxib treated rats respectively. Tumor regression occurred in 90% of the rats. In addition, new tumors continued to emerge in the control group, in contrast to their significantly decreasing numbers in the Celecoxib treated group over the same time period (p<0.05). These results indicate that Celecoxib has significant antineoplastic activity, in addition to its anticarcinogenic effects.
    Oncology Reports 11/2000; 7(6):1377-81. DOI:10.3892/or.7.6.1377 · 2.19 Impact Factor
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    ABSTRACT: Epidemiological studies have shown that nonsteroidal anti-inflammatory drugs (NSAIDs) may have a role in the prevention of human cancers. A number of preclinical studies have also suggested that inhibition of cyclooxygenase (COX) with NSAIDs has an anticancer effect in animal models of colon, urinary bladder, skin, and breast. In these studies, we evaluated the COX-2 inhibitor celecoxib in two rodent models of urinary bladder cancer. Male B6D2F1 mice treated with N-butyl-N-(4-hydroxybutyl)-nitrosamine (OH-BBN) developed transitional and squamous cell urinary bladder cancers, many of which grew rapidly and caused substantial morbidity that required sacrifice of the mice. Groups of mice received various daily doses of celecoxib in the diet (1250, 500, or 200 mg/kg of diet) beginning 7 days before the initiation of 12 weekly doses of OH-BBN. Mice were checked weekly for the presence of palpable urinary bladder masses. The study was terminated at 8 months following the initial treatment with OH-BBN. The percentage of mice with large palpable bladder lesions, which necessitated sacrifice of the mice, was 40% in the OH-BBN control group. In contrast, only 10% of all celecoxib-treated mice required sacrifice before the scheduled termination of the experiment, implying that all three doses of celecoxib inhibited the formation of large palpable lesions. Celecoxib did not significantly alter the incidence of preneoplastic bladder lesions, but did dose-dependently decrease the total number of urinary bladder cancers/mouse, palpable plus microscopic, by 77, 57, and 43% at dosages of 1250, 500, and 200 mg of celecoxib/kg of diet, respectively. In the second model, female Fischer-344 rats were administered OH-BBN twice/week for a period of 8 weeks. After 8 months, all rats developed preneoplastic lesions, whereas roughly 60% of the rats developed relatively small urinary bladder cancers. Rats were treated continually with celecoxib in the diet (500 or 1000 mg/kg of diet) beginning either 1 week prior to the initial OH-BBN treatment or beginning 1 week following the last OH-BBN treatment. Neither celecoxib treatment regimen significantly altered the number of preneoplastic lesions. Whereas celecoxib treatment initiated prior to OH-BBN administration decreased cancer incidence roughly 65%, celecoxib treatment initiated beginning 1 week after the last dose of OH-BBN profoundly decreased cancer incidence (>95%). Celecoxib did not alter the body weights of the mice or rats, or cause other signs of toxicity at any of the doses studied. Taken together these results demonstrate that: (a) celecoxib effectively inhibits tumor growth and enhances survival in the mouse model of urinary bladder cancer; and (b) celecoxib profoundly inhibits development of urinary bladder cancers in the rat model even when administered following the last dose of OH-BBN. Clinical trials will be necessary to determine whether COX-2 inhibitors will provide a clinical benefit in human bladder cancer.
    Cancer Research 10/2000; 60(20):5599-602. · 9.28 Impact Factor

Publication Stats

14k Citations
454.96 Total Impact Points

Institutions

  • 2005
    • Pfizer Inc.
      New York City, New York, United States
  • 1996–2002
    • University of Missouri - St. Louis
      Saint Louis, Michigan, United States
  • 2000
    • University of Alabama at Birmingham
      • Department of Surgery
      Birmingham, AL, United States
  • 1995–2000
    • Monsanto Company
      Saint Louis, Michigan, United States
  • 1997
    • Skokie Hospital
      Skokie, Illinois, United States
  • 1991–1992
    • Washington University in St. Louis
      San Luis, Missouri, United States
  • 1990–1991
    • University of Washington Seattle
      • Department of Pharmacology
      Seattle, WA, United States