Abstract
We have studied the mechanism of action of Arg*-Arg-Nal2-Cys(1×)-Tyr-Gln-Lys-(d-Pro)-Pro-Tyr-Arg-Cit-Cys(1×)-Arg-Gly-(d-Pro)* (POL3026), a novel specific β-hairpin mimetic CXC chemokine receptor (CXCR)4 antagonist. POL3026 specifically blocked the binding of anti-CXCR4 monoclonal antibody 12G5 and the intracellular Ca2+ signal induced by CXC chemokine ligand 12. POL3026 consistently blocked the replication of human immunodeficiency virus (HIV), including a wide panel of X4 and dualtropic strains and subtypes in several culture models, with 50% effective concentrations (EC50) at the subnanomolar range, making POL3026 the most potent CXCR4 antagonist described to date. However, 1-[[4-(1,4,8,11-tetrazacyclotetradec-1-ylmethyl)phenyl]methyl]-1,4,8,11-tetrazacyclotetradecane (AMD3100)-resistant and stromal cell-derived factor-1α-resistant HIV-1 strains were cross-resistant to POL3026. Time of addition experiments and a multiparametric evaluation of HIV envelope function in the presence of test compounds confirmed the activity of POL3026 at an early step of virus replication: interaction with the coreceptor. Generation of HIV-1 resistance to POL3026 led to the selection of viruses 12- and 25-fold less sensitive and with mutations in gp120, including the V3 loop region. However, POL3026 prevented the emergence of CXCR4-using variants from an R5 HIV-1 strain that may occur in the presence of anti-HIV agents targeting CC chemokine receptor 5.
Footnotes
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This work was supported in part by the Spanish Ministerio de Educación y Ciencia project BFU2006-00966 (to J.A.E.) and SAF2007-63622-C2 (to B.C.), the Fondo de Investigación Sanitaria Red Temática Cooperativa de Investigacion en SIDA and PI060624, and the European TRIoH Consortium (LSHB-CT-2003-503480). G.M. and I.C.-C. are recipients of scholarships from Generalitat de Catalunya.
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ABBREVIATIONS: HIV, human immunodeficiency virus; CCR, CC chemokine receptor; CXCR, CXC chemokine receptor; FCS, fetal calf serum; SI, syncytium-inducing; PBMC, peripheral blood mononuclear cells; SDF-1, stromal cell-derived factor-1; MIP, macrophage inflammatory protein; RANTES, regulated on activation normal T cell expressed and secreted; RT, reverse transcriptase; AZT, 3-Azido-3-deoxythymidine; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium; PBS, phosphate-buffered saline; ELISA, enzyme-linked immunosorbent assay; wt, wild type; MDM, monocyte-derived macrophages; mAb, monoclonal antibody; POL3026, Arg*-Arg-Nal2-Cys(1×)-Tyr-Gln-Lys-(d-Pro)-Pro-Tyr-Arg-Cit-Cys(1×)-Arg-Gly-(d-Pro)*; AMD3100, 1-[[4-(1,4,8,11-tetrazacyclotetradec-1-ylmethyl)phenyl]methyl]-1,4,8,11-tetrazacyclotetradecane; ALX-40-4-C, Ac-(D-Arg)9-NH2; TAK-779, dimethyl-[[4-[[3-(4-methylphenyl)8,9-dihydro-7H-benzo[7]annulene-6-carbonyl]amino]-phenyl]methyl]-(oxan-4-yl)azanium chloride.
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↵ The online version of this article (available at http://molpharm.aspetjournals.org) contains supplemental material.
- Received October 25, 2007.
- Accepted December 27, 2007.
- The American Society for Pharmacology and Experimental Therapeutics
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