Abstract
In neutrophils, growth-related protein-α (CXCL1) and interleukin-8 (CXCL8), are potent chemoattractants (Cytokine14:27–36, 2001; Biochemistry42:2874–2886, 2003) and can stimulate myeloperoxidase release via activation of the G protein-coupled receptors CXCR1 and CXCR2. The role of CXCR1 and CXCR2 in the pathogenesis of inflammatory responses has encouraged the development of small molecule antagonists for these receptors. The data presented herein describe the pharmacology of 2-hydroxy-N,N-dimethyl-3-{2-[[(R)-1-(5-methyl-furan-2-yl)-propyl]amino]-3,4-dioxo-cyclobut-1-enylamino}-benzamide (Sch527123), a novel antagonist of both CXCR1 and CXCR2. Sch527123 inhibited chemokine binding to (and activation of) these receptors in an insurmountable manner and, as such, is categorized as an allosteric antagonist. Sch527123 inhibited neutrophil chemotaxis and myeloperoxidase release in response to CXCL1 and CXCL8 but had no effect on the response of these cells to C5a or formyl-methionyl-leucyl-phenylalanine. The pharmacological specificity of Sch527123 was confirmed by testing in a diversity profile against a panel of enzymes, channels, and receptors. To measure compound affinity, we characterized [3H]Sch527123 in both equilibrium and nonequilibrium binding analyses. Sch527123 binding to CXCR1 and CXCR2 was both saturable and reversible. Although Sch527123 bound to CXCR1 with good affinity (Kd = 3.9 ± 0.3 nM), the compound is CXCR2-selective (Kd = 0.049 ± 0.004 nM). Taken together, our data show that Sch527123 represents a novel, potent, and specific CXCR2 antagonist with potential therapeutic utility in a variety of inflammatory conditions.
Footnotes
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Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
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doi:10.1124/jpet.106.118927.
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ABBREVIATIONS: IL-8, interleukin-8 (CXCL8); CXCL5, endothelial-cell derived neutrophil activating protein 78; fMLP, formyl-methionyl-leucyl-phenylalanine; CXCL6, granulocyte chemotactic protein-2; CXCL1-3, growth-related protein-α,-β, and -γ;[35S]GTPγS, guanosine 5′-[γ-35S]-triphosphate, triethylammonium salt; IL-3, interleukin-3; MPO, myeloperoxidase; CXCL7, neutrophil-activating peptide-2; FBS, fetal bovine serum; RLU, relative light intensity unit; WGA-SPA, wheat germ agglutinin bead-scintillation proximity assay; Sch527123, 2-hydroxy-N,N-dimethyl-3-{2-[[(R)-1-(5-methyl-furan-2-yl)-propyl]amino]-3,4-dioxo-cyclobut-1-enylamino}-benzamide; repertaxin, (R)(–)-2-(4-isobutylphenyl)propionyl meth-anesulfonamide; SB-225002, N-(2-hydroxy-4-nitrophenyl)-N′-(2-bromophenyl)urea; SB-332235, N-(2-hydroxy-3-sulfamyl-4-chlorophenyl)-N′-(2,3-dichlorophenyl)urea; SB-468477, N-(2-hydroxy-3-dimethylsulfonylamido-4-chlorophenyl)-N′-(2-bromophenyl)-N″-cyanoguanidine; h, human; PMN, neutrophil(s); HPLC, high-performance liquid chromatography; 873140, 4-{[4-({(3R)-1-butyl-3-[(R)-cyclohexyl(hydroxy)methyl]-2,5-dioxo-1,4,9-triazaspiro[5,5]undec-9-yl}methyl)phenyl]oxy}benzoic acid hydrochloride; CCL5, regulated on activation normal T cell expressed and secreted; TAK-220, 1-acetyl-N-{3-[4-(4-carbamoylbenzyl)piperidin-1-yl]propyl}-N-(3-chloro-4-methylphenyl)piperidine-4-carboxamide.
- Received December 21, 2006.
- Accepted May 7, 2007.
- The American Society for Pharmacology and Experimental Therapeutics
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