Evaluation of a Fluorescent Derivative of AMD3100 and its Interaction with the CXCR4 Chemokine Receptor

Abstract

AMD3100 is a potent and selective antagonist of the CXCR4 receptor; it has been shown to block the route of entry of HIV into host T-cells. This compound and its analogues have since been found to act as haematopoietic stem cell mobilisation agents and, more recently, as anti-cancer agents. Here, we have examined a fluorescent derivative of AMD3100, L(1), which offered the potential to assess the behaviour of AMD3100 at the cell surface by using optical imaging modalities. The binuclear Zn(II) , Cu(II) and Ni(II) complexes of L(1) have also been investigated as these metals have been previously shown to enhance the binding properties of AMD3100. Furthermore, Zn(II) and Cu(II) are known to enhance and quench, respectively, the fluorescence of similar anthracenyl-based ligands. Whilst L(1) demonstrates an ability to inhibit the binding of the anti-CXCR4 monoclonal antibody 12G5 (IC(50) =0.25-0.9 μM), the incorporation of an anthracenyl moiety resulted in a significantly reduced affinity for CXCR4 compared to AMD3100 (IC(50) =10 nM). We observed no significant increase in fluorescence intensity following incubation with murine pre-B cells overexpressing CXCR4 compared to a control cell line. This limits the usefulness of L(1) as a fluorescent imaging probe. Interestingly, the Zn(II) complex, which carries an overall +4 charge, revealed marginally higher specificity and reduced toxicity in vitro compared to the free ligand, albeit with reduced affinity for CXCR4 (IC(50) =1.8-5 μM). We suggest that the incorporation of an anthracenyl group contributes to the lipophilic character of the free ligand, thereby resulting in transport across the plasma membrane. This effect is seemingly diminished when the ligand is complexed to charged metal ions.

Different Patterns of HIV-1 Replication in MACROPHAGES is Led by Co-Receptor Usage

“…The prototype bicyclam CXCR4 inhibitor and agonist stromal derived factor (SDF-1alpha) AMD3100, (1-1*-[1,4-phenylenebis(methylene)]-bis(1,4,8,11-tetraazacyclotetradecane) octahydrochloride dihydrate]) synthesized at Johnson Matthey [48,49,50], and the CCR5 inhibitor, N,N-dimethyl-N-[4-[[[2-(4-methylphenyl)-6,7-dihydro-5H-benzocyclohepten-8-yl] carbonil]amino]benzyl] tetrahydro-2H-pyran-4-aminium chloride (TAK779), a nonpeptide compound with a small molecular weight (Mr 531.13), (Takeda Chemical Industries, Ltd., Osaka, Japan) [51,52], were suspended and aliquoted in Phosphate-buffered saline (PBS) solution, and used to 5 µM and 2 and 10 µg/mL, respectively.…”

New AMD3100 derivatives for CXCR4 chemokine receptor targeted molecular imaging studies: synthesis, anti-HIV-1 evaluation and binding affinities

“…A rhodamine conjugated to a reinforced cyclam competes with anti-CXCR4 antibodies during binding competition when labelled with copper(II) 18 and a fluorescent AMD3100 analogue with an anthracenyl moiety used as a spacer shows a significant reduction of the affinity probably due to the lipophilic character of the anthracenyl group. 19 In this study, new CXCR4 antagonists are investigated as potent anti-HIV agents and platforms for conjugation in molecular imaging agent design. The syntheses of new AMD3100 analogues functionalised on the phenyl moiety by an ester or an ethylenediamine moiety are discussed and we report the influence of the functionalisation on the affinity towards the CXCR4 chemokine receptor and antiviral potency against an X4 HIV-1 strain.…”

Modulators of CXCR4 and CXCR7/ACKR3 Function

“…Another fluorescent derivative of AMD3100 has also been reported by (Knight et al (2011) and used an anthracene moiety to link two cyclam rings (Fig. 7).…”