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Edward E Knaus - One of the best experts on this subject based on the ideXlab platform.
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design and synthesis of new rofecoxib analogs as selective cyclooxygenase 2 cox 2 inhibitors replacement of the methanesulfonyl pharmacophore by a n acetylsulfonamido bioisostere
Journal of pharmacy & pharmaceutical sciences : a publication of the Canadian Society for Pharmaceutical Sciences, 2007Co-Authors: Afshin Zarghi, P Praveen N Rao, Edward E KnausAbstract:PURPOSE A group of 3,4-diaryl- 2(5H)furanones were synthesized to determine whether a N-acetylsulfonamido (SO2NHCOCH3) moiety could be used as a bioisosteric replacement for the traditional sulfonamide (SO2NH2) and methanesulfonyl (SO2CH3) COX-2 pharmacophores. METHODS In vitro COX-1 and COX-2 isozyme inhibition studies were carried out to acquire structure activity relationship data with respect to the point of attachment of the Nacetylsulfonamide moiety at the para and metapositions of the C-4 phenyl ring in conjunction with a variety of substituents (H, F, Cl, Me, OMe) at the para position of the C-3 phenyl ring. RESULTS COX-1 and COX-2 inhibition studies showed that all compounds were selective inhibitors of COX-2 since no inhibition of COX-1 was observed at a concentration of 100 microM. The relative COX-2 potency, and COX-2 selectivity index, profiles for the C-4 para acetamidophenyl compounds, with respect to the C-3 phenyl parasubstituent was H > F > Cl. The point of attachment of the SO2NHCOCH3 substituent on the C-4 phenyl ring was a determinant of COX-2 potency, and COX-2 selectivity, where the relative activity profile was para acetylsulfonamido > meta acetylsulfonamido. 4-[4-(NAcetylsulfonamido) phenyl]-3-phenyl-2(5H)furanone was identified as a more potent (IC50 = 0.32 microM), and selective (S.I. > 313), COX-2 inhibitor than the parent reference compound rofecoxib (IC50 = 0.43 microM, S.I. > 232). CONCLUSIONS The SO2NHCOCH3 moiety i) is a novel COX-2 pharmacophore that also has the potential to serve as a prodrug moiety to the traditional SO2NH2 COX-2 pharmacophore, and ii) it could serve as a useful COX-2 pharmacophore to study the structure-function relationship of the COX-2 isozyme in view of its potential to acetylate the NH2 moiety of amino acid residues such as Gln192 or Arg513 that line the pocket of the secondary COX-2 binding site.
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synthesis and structure activity relationship studies of 1 3 diarylprop 2 yn 1 ones dual inhibitors of cyclooxygenases and lipoxygenases
Journal of Medicinal Chemistry, 2006Co-Authors: P Praveen N Rao, Qiaohong Chen, Edward E KnausAbstract:A group of 1,3-diarylprop-2-yn-1-ones (13, 17, 23, 26 and 27) possessing a C-3 p-SO2Me COX-2 pharmacophore were designed, synthesized and evaluated as potential dual inhibitors of cyclooxygenase-1/2 (COX-1/2) and 5/15-lipoxygenases (5/15-LOX) that exhibit vivo antiinflammatory and analgesic activities. Among this class of compounds, 3-(4-methanesulfonylphenyl)-1-(4-fluorophenyl)prop-2-yn-1-one (13h) was identified as a potent and selective inhibitor of COX-2 (COX-2 IC50 = 0.1 μM; SI = 300), being 5-fold more potent than rofecoxib (COX-2 IC50 = 0.5 μM; SI > 200). In a rat carrageenan-induced paw edema assay 13h exhibited moderate antiinflammatory activity (26% inhibition of inflammation) at 3 h after administration of a 30 mg/kg oral dose. A related dual COX-1/2 and 5/15-LOX inhibitor 3-(4-methanesulfonylphenyl)-1-(4-cyanophenyl)prop-2-yn-1-one (13g, COX-1 IC50 = 31.5 μM; COX-2 IC50 = 1.0 μM; SI = 31.5; 5-LOX IC50 = 1.0 μM; 15-LOX IC50 = 3.2 μM) exhibited more potent antiinflammatory activity (ED50 = 90 mg...
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synthesis and biological evaluation of 3 4 diphenyl 1 2 5 oxadiazole 2 oxides and 3 4 diphenyl 1 2 5 oxadiazoles as potential hybrid cox 2 inhibitor nitric oxide donor agents
Bioorganic & Medicinal Chemistry, 2005Co-Authors: Carlos A Velazquez, P Praveen N Rao, Robert Mcdonald, Edward E KnausAbstract:A group of 3,4-diphenyl-1,2,5-oxadiazole-2-oxides (3,4-diphenylfuroxans) and the corresponding N-desoxy 3,4-diphenyl-1,2,5-oxadiazoles (3,4-diphenylfurazans) analogs, were synthesized for in vitro evaluation as hybrid cyclooxygenase (COX) inhibitor/nitric oxide donor agents. Reaction of 1-[4-(methylsulfonyl)phenyl]-2-phenylethene with an aqueous sodium nitrite solution in acetic acid afforded a mixture (3:1 ratio) of the inseparable 4-[4-(methylsulfonyl)phenyl]-3-phenyl-1,2,5-oxadiazole-2-oxide (13a) and 3-[4-(methylsulfonyl)phenyl]-4-phenyl-1,2,5-oxadiazole-2-oxide (13b) regioisomers. A group of related regioisomers possessing either a p-aminosulfonylphenyl (16) or a p-azidosulfonylphenyl (17), moiety were obtained by chlorosulfonation of the unsubstituted 3,4-diphenylfuroxan (10) and subsequent reaction with either ammonium hydroxide or sodium azide, respectively. The methanesulfonyl regioisomers 13a,b [COX-1 IC50=11.6 microM; COX-2 IC50=0.12 microM; COX-2 selectivity index (SI)=97] and aminosulfonyl regioisomers 16 (COX-1 IC50=9.8 microM; COX-2 IC50=0.78 microM; COX-2 SI=12), like the reference drug celecoxib (COX-1 IC50=33.1 microM; COX-2 IC50=0.07 microM; COX-2 SI=472), were potent in vitro COX-2 inhibitors with a good COX-2 selectivity index. Release of nitric oxide (NO) from the 3,4-diphenylfuroxan compounds (10, 13a,b, 16, 17) was thiol-dependent since the % NO released was higher upon incubation in the presence of l-cysteine (0.57-3.18%) compared to that in phosphate buffer solution at pH7.4 (0.06-0.15%). Molecular modeling (docking) studies show that the methanesulfonyl (MeSO2) COX-2 pharmacophore present in regioisomers 13a,b is positioned in the vicinity of the COX-2 secondary pocket. The in vitro NO release data, COX-1/COX-2 inhibition and COX-2 SI structure-activity relationships acquired, and molecular modeling docking studies suggest that the 1,2,5-oxadiazole-2-oxide (furoxan) ring possesses beneficial features that should be present in a suitable central ring template (bioisostere) pertinent to the design novel hybrid COX-2 inhibitor/nitric oxide donor agents with a low ulcerogenicity profile that may be free from adverse cardiovascular effects.
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design and synthesis of novel celecoxib analogues as selective cyclooxygenase 2 cox 2 inhibitors replacement of the sulfonamide pharmacophore by a sulfonylazide bioisostere
Bioorganic & Medicinal Chemistry, 2003Co-Authors: Md Jashim Uddin, P Praveen N Rao, Edward E KnausAbstract:A group of celecoxib analogues in which the para-SO(2)NH(2) substituent on the N(1)-phenyl ring was replaced by a para-sulfonylazido (SO(2)N(3)) 4, or a meta-SO(2)N(3) 8, substituent were designed for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors. In vitro COX-1 and COX-2 inhibition studies showed that 4-[5-(4-methylphenyl)-3-trifluoromethyl-1H-pyrazol-1-yl]benzenesulfonyl azide (4) with a para-SO(2)N(3) substituent was a selective COX-1 inhibitor. In contrast, 3-[5-(4-methylphenyl)-3-trifluoromethylpyrazol-1-yl]benzenesulfonyl azide (8a) having a meta-SO(2)N(3) substituent (COX-1 IC(50) >100microM; COX-2 IC(50)=5.16microM; COX-2 selectivity index >19.3) is a selective COX-2 inhibitor. A molecular modeling (docking) study showed that the SO(2)N(3) group of 8a inserts deep inside the secondary pocket of the COX-2 binding site. The SO(2)N(3) moiety of 8a can undergo a dual H-bonding interaction via one of its SO(2) oxygen-atoms, and an electrostatic (ion-ion) interaction via the terminal azido (N(3)) nitrogen-atom, to the guanidino NH(2) of Arg(513) in the secondary pocket of COX-2. These observations indicate that an appropriately positioned SO(2)N(3) moiety is a novel alternative bioisostere to the traditional SO(2)NH(2) and SO(2)Me pharmacophores present in selective COX-2 inhibitors, that are only capable of H-bonding interactions with the COX-2 isozyme, for use in drug design.
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design and synthesis of novel rofecoxib analogs as potential cyclooxygenase cox 2 inhibitors replacement of the methylsulfonyl pharmacophore by a sulfonylazide bioisostere
Journal of Heterocyclic Chemistry, 2003Co-Authors: Md Jashim Uddin, P Praveen N Rao, Edward E KnausAbstract:A group of rofecoxib analogs, having a sulfonylazide (SO2N3) substituent in place of the methanesulfonyl (SO2CH3) pharmacophore at the meta-position viz 3-(4-methyl, 4-methoxy, or 4-ethoxyphenyl)-4-(3-sulfonylazidophenyl)-2(5H)furanone (7a-c) and para-position viz 3-phenyl-4-(4-sulfonylazidophenyl)-2(5H)furanone (7d), 3-(4-fluoro, or 4-chlorophenyl)-4-(4-sulfonylazidophenyl)-2(5H)furanone (7e-f) of the C–4 phenyl ring, and 4-(1-oxido-4-pyridyl)-3-phenyl-2(5H)furanone (12) were designed and synthesized for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors. In vitro COX-1/COX-2 enzyme inhibition studies showed that 3-phenyl-4-(4-sulfonylazidophenyl)-2(5H)furanone (7d) inhibited COX-1 selectively (COX-1 IC50 = 0.6659 μM; COX-2 IC50 > 100 μM) and 3-(4-fluorophenyl)-4-(4-sulfonylazidophenyl)-2(5H)furanone (7e) inhibited both enzymes (COX-1 IC50 = 0.8494 μM; COX-2 IC50 = 1.7661 μM). A molecular modeling study was performed where 3-(4-fluorophenyl)-4-(4-sulfonylazidophenyl)-2(5H)furanone (7e) was docked in the active site of murine COX-2 isozyme, which showed that the sulfonylazido group inserts deep into the 2°-pocket of COX-2 where it undergoes both H-bonding (Gln192, Phe518) and weak electrostatic (Arg513) interactions.
Dan A Dixon - One of the best experts on this subject based on the ideXlab platform.
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the mrna stability factor hur inhibits microrna 16 targeting of cox 2
Molecular Cancer Research, 2012Co-Authors: Lisa E Young, Ashleigh E Moore, Lena Sokol, Nicole Meisnerkober, Dan A DixonAbstract:Commonly observed in colorectal cancer is the elevated expression of the prostaglandin (PG) synthase COX-2. In normal intestinal epithelium, the COX-2 mRNA is targeted for rapid decay through the 3′-untranslated region (3′-UTR) adenylate- and uridylate (AU)-rich element (ARE), whereas in tumors ARE-mediated decay is compromised. Here we show that the COX-2 ARE can mediate degradation through microRNA (miRNA)-mediated regulation. We identified miR-16 to bind the COX-2 3′-UTR and inhibit COX-2 expression by promoting rapid mRNA decay. In colorectal cancer cells and tumors, miR-16 levels were decreased approximately twofold and miR-16 expression in cancer cells attenuated COX-2 expression and PG synthesis. The COX-2 ARE is also bound by the RNA-binding protein HuR. In colorectal cancer tumors, HuR is overexpressed and localized within the cytoplasm, where it promotes ARE-mRNA stabilization. Under conditions of HuR overexpression, miR-16 was unable to promote rapid mRNA decay through the COX-2 ARE. Ribonucleoprotein immunoprecipitation of HuR showed direct association with miR-16 that was reversed when cytoplasmic trafficking of HuR was inhibited. Furthermore, this interaction between HuR and miR-16 promoted the downregulation of miR-16. These new results identify miR-16 as a central posttranscriptional regulator of COX-2 and show the ability of elevated levels of HuR to antagonize miR-16 function. Along with insight into altered ARE-mediated mRNA decay observed in colorectal cancer, these findings provide a new explanation for tumor-derived loss of miR-16. Mol Cancer Res; 10(1); 167–80. ©2011 AACR .
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green tea polyphenol epigallocatechin 3 gallate inhibits cyclooxygenase 2 expression in colon carcinogenesis
Molecular Carcinogenesis, 2006Co-Authors: Guang Peng, Dan A Dixon, Stephanie J Muga, Theresa J Smith, Michael J WargovichAbstract:Tea, one of the most widely consumed beverages worldwide, has been shown to have anti-cancer activity in various cancers including colon cancer. It has been demonstrated that overexpression of the inducible isoform of cyclooxygenase (COX-2) occurs during colon tumorigenesis and inhibition of COX-2 by non-steroidal anti-inflammatory drugs (NSAIDs) is chemopreventive. To determine whether the anti-cancer effect associated with green tea impacted COX-2 expression levels, human colorectal cancer cell lines HT-29 and HCA-7, were treated with (−)-epigallocatechin-3-gallate (EGCG), the most abundant and effective polyphenol of green tea. EGCG significantly inhibited constitutive COX-2 mRNA and protein overexpression. The inhibitory effects of EGCG on signaling pathways controlling COX-2 expression were examined. We observed that EGCG downregulated the ERK1/2 and Akt pathways in colon cancer cells. The effect of EGCG on COX-2 expression resulted in decreased COX-2 promoter activity via inhibition of nuclear factor κB (NF-κB) activation. EGCG also promoted rapid mRNA decay mediated through the COX-2 3′untranslated region (3′UTR). In conclusion, these data suggest that inhibition of COX-2 is a mechanism for the anti-proliferative effect of green tea and emphasizes the role that dietary factors have as anti-cancer agents. © 2006 Wiley-Liss, Inc.
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regulation of cyclooxgenase 2 mrna stability by taxanes evidence for involvement of p38 mapkapk 2 and hur
Journal of Biological Chemistry, 2003Co-Authors: Kotha Subbaramaiah, Dan A Dixon, Timothy P Marmo, Andrew J DannenbergAbstract:Taxanes are widely used to treat malignancies and are known to modulate the transcription of several genes. We investigated the effects of taxanes (docetaxel and paclitaxel) on cyclooxygenase-2 (COX-2) transcription and mRNA stability in human mammary epithelial cells. As reported previously for paclitaxel, docetaxel stimulated COX-2 transcription by an AP-1-dependent mechanism. Treatment with taxanes also enhanced the stability of COX-2 mRNA. To define the mechanism by which taxanes stabilized COX-2 mRNA, transient transfections were carried out using luciferase expression constructs containing the COX-2 3'-untranslated region (3'-untranslated region (UTR)). The stabilizing effects of taxanes were localized to the AU-rich region of COX-2 3'-UTR. RNA binding studies indicated that taxanes stimulated the binding of HuR to the AU-rich region of the COX-2 3'-UTR. Overexpression of antisense HuR suppressed taxane-mediated induction of COX-2 3'-UTR activity. We next investigated the signal transduction pathway responsible for taxane-mediated induction of COX-2. Taxanes enhanced protein kinase C activity; overexpressing dominant negative PKC-alpha suppressed taxane-mediated stimulation of both COX-2 3'-UTR and 5'-promoter activities. Interestingly, ERK1/2, JNK, and p38 MAPKs were important for taxane-mediated activation of COX-2 transcription, but only p38 MAPK appeared to be responsible for the increase in COX-2 mRNA stability. MAPKAPK-2, a known target of p38 MAPK, contributed to increased COX-2 mRNA stability following taxane treatment. SB 202190, a selective p38 MAPK inhibitor, and dexamethasone suppressed taxane-mediated stimulation of the COX-2 3'-UTR and binding of HuR. Taken together, these data indicate that taxanes induce COX-2 by stimulating both transcription and mRNA stability. To the best of our knowledge, this is the first evidence that taxanes can promote stabilization of mRNA in addition to modulating gene transcription.
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regulation of cyclooxygenase 2 expression by the translational silencer tia 1
Journal of Experimental Medicine, 2003Co-Authors: Dan A Dixon, Guy A Zimmerman, Glen C Balch, Nancy Kedersha, Paul Anderson, Daniel R Beauchamp, Stephen M PrescottAbstract:The cyclooxygenase-2 (COX-2) enzyme catalyzes the rate-limiting step of prostaglandin formation in inflammatory states, and COX-2 overexpression plays a key role in carcinogenesis. To understand the mechanisms regulating COX-2 expression, we examined its posttranscriptional regulation mediated through the AU-rich element (ARE) within the COX-2 mRNA 3′-untranslated region (3′UTR). RNA binding studies, performed to identify ARE-binding regulatory factors, demonstrated binding of the translational repressor protein TIA-1 to COX-2 mRNA. The significance of TIA-1-mediated regulation of COX-2 expression was observed in TIA-1 null fibroblasts that produced significantly more COX-2 protein than wild-type fibroblasts. However, TIA-1 deficiency did not alter COX-2 transcription or mRNA turnover. Colon cancer cells demonstrated to overexpress COX-2 through increased polysome association with COX-2 mRNA also showed defective TIA-1 binding both in vitro and in vivo. These findings implicate that TIA-1 functions as a translational silencer of COX-2 expression and support the hypothesis that dysregulated RNA-binding of TIA-1 promotes COX-2 expression in neoplasia.
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altered expression of the mrna stability factor hur promotes cyclooxygenase 2 expression in colon cancer cells
Journal of Clinical Investigation, 2001Co-Authors: Dan A Dixon, Neal D Tolley, Peter H King, L B Nabors, T M Mcintyre, Guy A Zimmerman, Stephen M PrescottAbstract:Cyclooxygenase-2 (COX-2) expression is normally tightly regulated. However, constitutive overexpression plays a key role in colon carcinogenesis. To understand the molecular nature of enhanced COX-2 expression detected in colon cancer, we examined the ability of the AU-rich element-containing (ARE-containing) 3' untranslated region (3'UTR) of COX-2 mRNA to regulate rapid mRNA decay in human colon cancer cells. In tumor cells displaying enhanced growth and tumorigenicity that is correlated with elevated COX-2, vascular endothelial growth factor (VEGF), and IL-8 protein levels, the corresponding mRNAs were transcribed constitutively and turned over slowly. The observed mRNA stabilization is owing to defective recognition of class II-type AREs present within the COX-2, VEGF, and IL-8 3'UTRs; c-myc mRNA, containing a class I ARE decayed rapidly in the same cells. Correlating with cellular defects in mRNA stability, the RNA-binding of trans-acting cellular factors was altered. In particular, we found that the RNA-stability factor HuR binds to the COX-2 ARE, and overexpression of HuR, as detected in tumors, results in elevated expression of COX-2, VEGF, and IL-8. These findings demonstrate the functional significance rapid mRNA decay plays in controlling gene expression and show that dysregulation of these trans-acting factors can lead to overexpression of COX-2 and other angiogenic proteins, as detected in neoplasia.
P Praveen N Rao - One of the best experts on this subject based on the ideXlab platform.
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design and synthesis of new rofecoxib analogs as selective cyclooxygenase 2 cox 2 inhibitors replacement of the methanesulfonyl pharmacophore by a n acetylsulfonamido bioisostere
Journal of pharmacy & pharmaceutical sciences : a publication of the Canadian Society for Pharmaceutical Sciences, 2007Co-Authors: Afshin Zarghi, P Praveen N Rao, Edward E KnausAbstract:PURPOSE A group of 3,4-diaryl- 2(5H)furanones were synthesized to determine whether a N-acetylsulfonamido (SO2NHCOCH3) moiety could be used as a bioisosteric replacement for the traditional sulfonamide (SO2NH2) and methanesulfonyl (SO2CH3) COX-2 pharmacophores. METHODS In vitro COX-1 and COX-2 isozyme inhibition studies were carried out to acquire structure activity relationship data with respect to the point of attachment of the Nacetylsulfonamide moiety at the para and metapositions of the C-4 phenyl ring in conjunction with a variety of substituents (H, F, Cl, Me, OMe) at the para position of the C-3 phenyl ring. RESULTS COX-1 and COX-2 inhibition studies showed that all compounds were selective inhibitors of COX-2 since no inhibition of COX-1 was observed at a concentration of 100 microM. The relative COX-2 potency, and COX-2 selectivity index, profiles for the C-4 para acetamidophenyl compounds, with respect to the C-3 phenyl parasubstituent was H > F > Cl. The point of attachment of the SO2NHCOCH3 substituent on the C-4 phenyl ring was a determinant of COX-2 potency, and COX-2 selectivity, where the relative activity profile was para acetylsulfonamido > meta acetylsulfonamido. 4-[4-(NAcetylsulfonamido) phenyl]-3-phenyl-2(5H)furanone was identified as a more potent (IC50 = 0.32 microM), and selective (S.I. > 313), COX-2 inhibitor than the parent reference compound rofecoxib (IC50 = 0.43 microM, S.I. > 232). CONCLUSIONS The SO2NHCOCH3 moiety i) is a novel COX-2 pharmacophore that also has the potential to serve as a prodrug moiety to the traditional SO2NH2 COX-2 pharmacophore, and ii) it could serve as a useful COX-2 pharmacophore to study the structure-function relationship of the COX-2 isozyme in view of its potential to acetylate the NH2 moiety of amino acid residues such as Gln192 or Arg513 that line the pocket of the secondary COX-2 binding site.
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synthesis and structure activity relationship studies of 1 3 diarylprop 2 yn 1 ones dual inhibitors of cyclooxygenases and lipoxygenases
Journal of Medicinal Chemistry, 2006Co-Authors: P Praveen N Rao, Qiaohong Chen, Edward E KnausAbstract:A group of 1,3-diarylprop-2-yn-1-ones (13, 17, 23, 26 and 27) possessing a C-3 p-SO2Me COX-2 pharmacophore were designed, synthesized and evaluated as potential dual inhibitors of cyclooxygenase-1/2 (COX-1/2) and 5/15-lipoxygenases (5/15-LOX) that exhibit vivo antiinflammatory and analgesic activities. Among this class of compounds, 3-(4-methanesulfonylphenyl)-1-(4-fluorophenyl)prop-2-yn-1-one (13h) was identified as a potent and selective inhibitor of COX-2 (COX-2 IC50 = 0.1 μM; SI = 300), being 5-fold more potent than rofecoxib (COX-2 IC50 = 0.5 μM; SI > 200). In a rat carrageenan-induced paw edema assay 13h exhibited moderate antiinflammatory activity (26% inhibition of inflammation) at 3 h after administration of a 30 mg/kg oral dose. A related dual COX-1/2 and 5/15-LOX inhibitor 3-(4-methanesulfonylphenyl)-1-(4-cyanophenyl)prop-2-yn-1-one (13g, COX-1 IC50 = 31.5 μM; COX-2 IC50 = 1.0 μM; SI = 31.5; 5-LOX IC50 = 1.0 μM; 15-LOX IC50 = 3.2 μM) exhibited more potent antiinflammatory activity (ED50 = 90 mg...
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synthesis and biological evaluation of 3 4 diphenyl 1 2 5 oxadiazole 2 oxides and 3 4 diphenyl 1 2 5 oxadiazoles as potential hybrid cox 2 inhibitor nitric oxide donor agents
Bioorganic & Medicinal Chemistry, 2005Co-Authors: Carlos A Velazquez, P Praveen N Rao, Robert Mcdonald, Edward E KnausAbstract:A group of 3,4-diphenyl-1,2,5-oxadiazole-2-oxides (3,4-diphenylfuroxans) and the corresponding N-desoxy 3,4-diphenyl-1,2,5-oxadiazoles (3,4-diphenylfurazans) analogs, were synthesized for in vitro evaluation as hybrid cyclooxygenase (COX) inhibitor/nitric oxide donor agents. Reaction of 1-[4-(methylsulfonyl)phenyl]-2-phenylethene with an aqueous sodium nitrite solution in acetic acid afforded a mixture (3:1 ratio) of the inseparable 4-[4-(methylsulfonyl)phenyl]-3-phenyl-1,2,5-oxadiazole-2-oxide (13a) and 3-[4-(methylsulfonyl)phenyl]-4-phenyl-1,2,5-oxadiazole-2-oxide (13b) regioisomers. A group of related regioisomers possessing either a p-aminosulfonylphenyl (16) or a p-azidosulfonylphenyl (17), moiety were obtained by chlorosulfonation of the unsubstituted 3,4-diphenylfuroxan (10) and subsequent reaction with either ammonium hydroxide or sodium azide, respectively. The methanesulfonyl regioisomers 13a,b [COX-1 IC50=11.6 microM; COX-2 IC50=0.12 microM; COX-2 selectivity index (SI)=97] and aminosulfonyl regioisomers 16 (COX-1 IC50=9.8 microM; COX-2 IC50=0.78 microM; COX-2 SI=12), like the reference drug celecoxib (COX-1 IC50=33.1 microM; COX-2 IC50=0.07 microM; COX-2 SI=472), were potent in vitro COX-2 inhibitors with a good COX-2 selectivity index. Release of nitric oxide (NO) from the 3,4-diphenylfuroxan compounds (10, 13a,b, 16, 17) was thiol-dependent since the % NO released was higher upon incubation in the presence of l-cysteine (0.57-3.18%) compared to that in phosphate buffer solution at pH7.4 (0.06-0.15%). Molecular modeling (docking) studies show that the methanesulfonyl (MeSO2) COX-2 pharmacophore present in regioisomers 13a,b is positioned in the vicinity of the COX-2 secondary pocket. The in vitro NO release data, COX-1/COX-2 inhibition and COX-2 SI structure-activity relationships acquired, and molecular modeling docking studies suggest that the 1,2,5-oxadiazole-2-oxide (furoxan) ring possesses beneficial features that should be present in a suitable central ring template (bioisostere) pertinent to the design novel hybrid COX-2 inhibitor/nitric oxide donor agents with a low ulcerogenicity profile that may be free from adverse cardiovascular effects.
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design and synthesis of novel celecoxib analogues as selective cyclooxygenase 2 cox 2 inhibitors replacement of the sulfonamide pharmacophore by a sulfonylazide bioisostere
Bioorganic & Medicinal Chemistry, 2003Co-Authors: Md Jashim Uddin, P Praveen N Rao, Edward E KnausAbstract:A group of celecoxib analogues in which the para-SO(2)NH(2) substituent on the N(1)-phenyl ring was replaced by a para-sulfonylazido (SO(2)N(3)) 4, or a meta-SO(2)N(3) 8, substituent were designed for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors. In vitro COX-1 and COX-2 inhibition studies showed that 4-[5-(4-methylphenyl)-3-trifluoromethyl-1H-pyrazol-1-yl]benzenesulfonyl azide (4) with a para-SO(2)N(3) substituent was a selective COX-1 inhibitor. In contrast, 3-[5-(4-methylphenyl)-3-trifluoromethylpyrazol-1-yl]benzenesulfonyl azide (8a) having a meta-SO(2)N(3) substituent (COX-1 IC(50) >100microM; COX-2 IC(50)=5.16microM; COX-2 selectivity index >19.3) is a selective COX-2 inhibitor. A molecular modeling (docking) study showed that the SO(2)N(3) group of 8a inserts deep inside the secondary pocket of the COX-2 binding site. The SO(2)N(3) moiety of 8a can undergo a dual H-bonding interaction via one of its SO(2) oxygen-atoms, and an electrostatic (ion-ion) interaction via the terminal azido (N(3)) nitrogen-atom, to the guanidino NH(2) of Arg(513) in the secondary pocket of COX-2. These observations indicate that an appropriately positioned SO(2)N(3) moiety is a novel alternative bioisostere to the traditional SO(2)NH(2) and SO(2)Me pharmacophores present in selective COX-2 inhibitors, that are only capable of H-bonding interactions with the COX-2 isozyme, for use in drug design.
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design and synthesis of novel rofecoxib analogs as potential cyclooxygenase cox 2 inhibitors replacement of the methylsulfonyl pharmacophore by a sulfonylazide bioisostere
Journal of Heterocyclic Chemistry, 2003Co-Authors: Md Jashim Uddin, P Praveen N Rao, Edward E KnausAbstract:A group of rofecoxib analogs, having a sulfonylazide (SO2N3) substituent in place of the methanesulfonyl (SO2CH3) pharmacophore at the meta-position viz 3-(4-methyl, 4-methoxy, or 4-ethoxyphenyl)-4-(3-sulfonylazidophenyl)-2(5H)furanone (7a-c) and para-position viz 3-phenyl-4-(4-sulfonylazidophenyl)-2(5H)furanone (7d), 3-(4-fluoro, or 4-chlorophenyl)-4-(4-sulfonylazidophenyl)-2(5H)furanone (7e-f) of the C–4 phenyl ring, and 4-(1-oxido-4-pyridyl)-3-phenyl-2(5H)furanone (12) were designed and synthesized for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors. In vitro COX-1/COX-2 enzyme inhibition studies showed that 3-phenyl-4-(4-sulfonylazidophenyl)-2(5H)furanone (7d) inhibited COX-1 selectively (COX-1 IC50 = 0.6659 μM; COX-2 IC50 > 100 μM) and 3-(4-fluorophenyl)-4-(4-sulfonylazidophenyl)-2(5H)furanone (7e) inhibited both enzymes (COX-1 IC50 = 0.8494 μM; COX-2 IC50 = 1.7661 μM). A molecular modeling study was performed where 3-(4-fluorophenyl)-4-(4-sulfonylazidophenyl)-2(5H)furanone (7e) was docked in the active site of murine COX-2 isozyme, which showed that the sulfonylazido group inserts deep into the 2°-pocket of COX-2 where it undergoes both H-bonding (Gln192, Phe518) and weak electrostatic (Arg513) interactions.
John A Di Battista - One of the best experts on this subject based on the ideXlab platform.
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leukotriene b4 blt receptor signaling regulates the level and stability of cyclooxygenase 2 cox 2 mrna through restricted activation of ras raf erk p42 auf1 pathway
Journal of Biological Chemistry, 2010Co-Authors: Beibei Zhai, Huiqing Yang, Arturo Mancini, Qingwen He, John Antoniou, John A Di BattistaAbstract:Recent studies suggest that active resolution of the inflammatory response in animal models of arthritis may involve leukotriene B4 (LTB4)-dependent stimulation of “intermediate” prostaglandin production, which in turn favors the synthesis of “downstream” anti-inflammatory and pro-resolving lipoxins, resolvins, and protectins. We explored a putative mechanism involving LTB4-dependent control of cyclooxygenase-2 (COX-2) expression, the rate-limiting step in inflammatory prostaglandin biosynthesis. Indeed, LTB4 potently up-regulated/stabilized interleukin-1β-induced COX-2 mRNA and protein expression under conditions of COX-2 inhibitor-dependent blockade of PGE2 release in human synovial fibroblasts (EC50 = 16.5 ± 1.7 nm for mRNA; 19 ± 2.4 nm for protein, n = 4). The latter response was pertussis toxin-sensitive, and semi-quantitative reverse transcription-PCR confirmed the quantitative predominance of the BLT2 receptor. Transfection experiments, using human COX-2 promoter plasmids and chimeric luciferase-COX-2 mRNA 3′-untranslated region (3′-UTR) reporter constructs, revealed that LTB4 exerted its stabilizing effect at the post-transcriptional level through a 116-bp adenylate/uridylate-rich sequence in the proximal region of the COX-2 3′-UTR. Using luciferase-COX-2 mRNA 3′-UTR reporter constructs and Ras/c-Raf expression and mutant constructs, we showed that the Ras/c-Raf/MEK1/2/ERK1/2 signaling pathway mediated LTB4-dependent COX-2 mRNA stabilization. Knockdown experiments with specific short hairpin RNAs confirmed that LTB4 stabilization of COX-2 mRNA was apparently mediated through the RNA-binding protein, p42 AUF1. The nuclear export of p42 AUF1 was driven by c-Raf/MEK1/2/ERK1/2 signaling and sensitive to leptomycin B treatment, suggesting a CRM1-dependent mechanism. We conclude that LTB4 may support the resolution phase of the inflammatory response by stabilizing COX-2, ensuring a reservoir of ambient pro-resolution lipid mediators.
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prostaglandin e 2 regulates the level and stability of cyclooxygenase 2 mrna through activation of p38 mitogen activated protein kinase in interleukin 1 beta treated human synovial fibroblasts
Journal of Biological Chemistry, 2001Co-Authors: Wissam H Faour, Arturo Mancini, Manon De Ladurantaye, Maritza Quintero, John A Di BattistaAbstract:The p38 MAPK mediates transcriptional and post-transcriptional control of cyclooxygenase-2 (COX-2) mRNA following interleukin-1(IL-1)/lipopolysaccharide cellular activation. We explored a positive feedback, prostaglandin E(2) (PGE(2))-dependent stabilization of COX-2 mRNA mediated by the p38 MAPK cascade in IL-1 beta-stimulated human synovial fibroblasts. We observed a rapid (5 min), massive (>30-fold), and sustained (>48 h) increase in COX-2 mRNA, protein, and PGE(2) release following a recombinant human (rh) IL-1 beta signal that was inhibited by NS-398, a COX-2 inhibitor, and SB202190, a selective, cell-permeable p38 MAPK inhibitor. PGE(2) completely reversed NS-398-mediated inhibition but not SB202190-dependent inhibition. The eicosanoid didn't potentiate IL-1 beta-induced COX-2 expression nor did it activate COX-2 gene expression in quiescent cells. Transfection experiments with a human COX-2 promoter construct revealed a minor element of p38 MAPK-dependent transcriptional control after IL-1 beta stimulation. p38 MAPK synergized with the cAMP/cAMP-dependent protein kinase cascade to transactivate the COX-2 promoter. When human synovial fibroblasts were activated with rhIL-1 beta for 3-4 h (steady state) followed by washout, the elevated levels of COX-2 mRNA declined rapidly (<2 h) to control levels. If PGE(2), unlike EP2/3 agonists butaprost and sulprostone, was added to fresh medium, COX-2 mRNA levels remained elevated for up to 16 h. SB202190 or anti-PGE(2) monoclonal antibody compromised the stabilization of COX-2 mRNA by PGE(2). Deletion analysis using transfected chimeric luciferase-COX-2 mRNA 3'-untranslated region reporter constructs revealed that IL-1 beta increased reporter gene mRNA stability and translation via AU-containing distal regions of the untranslated region. This response was mediated entirely by a PGE(2)/p38 MAPK-dependent process. We conclude that the magnitude and duration of the induction of COX-2 mRNA, protein, and PGE(2) release by rhIL-1 beta is primarily the result of PGE(2)-dependent stabilization of COX-2 mRNA and stimulation of translation, a process involving a positive feedback loop mediated by the EP4 receptor and the downstream kinases p38 MAPK and, perhaps, cAMP-dependent protein kinase.
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prostaglandin e2 regulates the level and stability of cyclooxygenase 2 mrna through activation of p38 mitogen activated protein kinase in interleukin 1β treated human synovial fibroblasts
Journal of Biological Chemistry, 2001Co-Authors: Wissam H Faour, Arturo Mancini, Manon De Ladurantaye, Maritza Quintero, John A Di BattistaAbstract:The p38 MAPK mediates transcriptional and post-transcriptional control of cyclooxygenase-2 (COX-2) mRNA following interleukin-1(IL-1)/lipopolysaccharide cellular activation. We explored a positive feedback, prostaglandin E(2) (PGE(2))-dependent stabilization of COX-2 mRNA mediated by the p38 MAPK cascade in IL-1 beta-stimulated human synovial fibroblasts. We observed a rapid (5 min), massive (>30-fold), and sustained (>48 h) increase in COX-2 mRNA, protein, and PGE(2) release following a recombinant human (rh) IL-1 beta signal that was inhibited by NS-398, a COX-2 inhibitor, and SB202190, a selective, cell-permeable p38 MAPK inhibitor. PGE(2) completely reversed NS-398-mediated inhibition but not SB202190-dependent inhibition. The eicosanoid didn't potentiate IL-1 beta-induced COX-2 expression nor did it activate COX-2 gene expression in quiescent cells. Transfection experiments with a human COX-2 promoter construct revealed a minor element of p38 MAPK-dependent transcriptional control after IL-1 beta stimulation. p38 MAPK synergized with the cAMP/cAMP-dependent protein kinase cascade to transactivate the COX-2 promoter. When human synovial fibroblasts were activated with rhIL-1 beta for 3-4 h (steady state) followed by washout, the elevated levels of COX-2 mRNA declined rapidly (<2 h) to control levels. If PGE(2), unlike EP2/3 agonists butaprost and sulprostone, was added to fresh medium, COX-2 mRNA levels remained elevated for up to 16 h. SB202190 or anti-PGE(2) monoclonal antibody compromised the stabilization of COX-2 mRNA by PGE(2). Deletion analysis using transfected chimeric luciferase-COX-2 mRNA 3'-untranslated region reporter constructs revealed that IL-1 beta increased reporter gene mRNA stability and translation via AU-containing distal regions of the untranslated region. This response was mediated entirely by a PGE(2)/p38 MAPK-dependent process. We conclude that the magnitude and duration of the induction of COX-2 mRNA, protein, and PGE(2) release by rhIL-1 beta is primarily the result of PGE(2)-dependent stabilization of COX-2 mRNA and stimulation of translation, a process involving a positive feedback loop mediated by the EP4 receptor and the downstream kinases p38 MAPK and, perhaps, cAMP-dependent protein kinase.
Aubrey R Morrison - One of the best experts on this subject based on the ideXlab platform.
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the proximal region of the 3 untranslated region of cyclooxygenase 2 is recognized by a multimeric protein complex containing hur tia 1 tiar and the heterogeneous nuclear ribonucleoprotein u
Journal of Biological Chemistry, 2003Co-Authors: Stephen J Acton, Aubrey R MorrisonAbstract:Abstract Cyclooxygenase-2 (COX-2) is an early response gene induced in renal mesangial cells by interleukin-1β (IL-1β). The 3′-untranslated region (3′-UTR) of COX-2 mRNA plays an important role in IL-1β induction by regulating message stability and translational efficiency. The first 60 nucleotides of the 3′-UTR of COX-2 are highly conserved and contain multiple copies of the regulatory sequence AUUUA. Introduction of the 60-nucleotide sequence into the 3′-UTR of a heterologous reporter gene resulted in a 70% decrease in reporter gene expression. Electrophoretic mobility shift assays (EMSAs) demonstrated that mesangial cell nuclear fractions contain a multimeric protein complex that bound this region of COX-2 mRNA in a sequence-specific manner. We identified four members of the protein-RNA complex as HuR, TIA-1, TIAR, and the heterogeneous nuclear ribonucleoprotein U (hnRNP U). Treatment of mesangial cells with IL-1β caused an increase in cytosolic HuR, which was accompanied by an increase in COX-2 mRNA that co-immunoprecipitated with cytosolic HuR. Therefore, we propose that HuR binds to the proximal region of the 3′-UTR of COX-2 following stimulation by IL-1β and increases the expression of COX-2 mRNA by facilitating its transport out of the nucleus.
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the proximal region of the 3 untranslated region of cyclooxygenase 2 is recognized by a multimeric protein complex containing hur tia 1 tiar and the heterogeneous nuclear ribonucleoprotein u
Journal of Biological Chemistry, 2003Co-Authors: Steven J Cok, Stephen J Acton, Aubrey R MorrisonAbstract:Cyclooxygenase-2 (COX-2) is an early response gene induced in renal mesangial cells by interleukin-1beta (IL-1beta). The 3'-untranslated region (3'-UTR) of COX-2 mRNA plays an important role in IL-1beta induction by regulating message stability and translational efficiency. The first 60 nucleotides of the 3'-UTR of COX-2 are highly conserved and contain multiple copies of the regulatory sequence AUUUA. Introduction of the 60-nucleotide sequence into the 3'-UTR of a heterologous reporter gene resulted in a 70% decrease in reporter gene expression. Electrophoretic mobility shift assays (EMSAs) demonstrated that mesangial cell nuclear fractions contain a multimeric protein complex that bound this region of COX-2 mRNA in a sequence-specific manner. We identified four members of the protein-RNA complex as HuR, TIA-1, TIAR, and the heterogeneous nuclear ribonucleoprotein U (hnRNP U). Treatment of mesangial cells with IL-1beta caused an increase in cytosolic HuR, which was accompanied by an increase in COX-2 mRNA that co-immunoprecipitated with cytosolic HuR. Therefore, we propose that HuR binds to the proximal region of the 3'-UTR of COX-2 following stimulation by IL-1beta and increases the expression of COX-2 mRNA by facilitating its transport out of the nucleus.
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the 3 untranslated region of murine cyclooxygenase 2 contains multiple regulatory elements that alter message stability and translational efficiency
Journal of Biological Chemistry, 2001Co-Authors: Steven J Cok, Aubrey R MorrisonAbstract:Renal mesangial cells regulate their expression of the pro-inflammatory gene cyclooxygenase-2 (COX-2) through mechanisms involving gene transcription and post-transcriptional events. Post-transcriptional regulation of COX-2 is dependent, in part, on sequences within the 3′-untranslated region (3′-UTR) of the COX-2 mRNA. Insertion of the entire 3′-UTR of COX-2 into the 3′-UTR of luciferase resulted in a 70% decrease in luciferase enzymatic activity. Measurement of steady-state reporter gene mRNA levels suggested that the loss of activity was due to decreased translational efficiency. Deletion analysis identified the first 60 nucleotides of the 3′-UTR of COX-2 as a major translational control element. This region of the 3′-UTR of COX-2 is highly conserved across species; is AU-rich; and contains multiple repeats of the regulatory sequence AUUUA, reported to confer post-transcriptional control. In addition, we identified regions of the 3′-UTR of COX-2 outside of the first 60 nucleotides that altered message stability. Some of these regions contained AUUUA consensus sequences, whereas others did not, and represent novel control elements. These results suggest that expression of COX-2 in mesangial cells depends on the complex integration of multiple signals derived from the 3′-UTR of the message.
