Department of Oncology, University of Alberta, Edmonton T6G 1Z2, Canada.
Chembiochem. 2011 Nov 25;12(17):2692-8. doi: 10.1002/cbic.201100441. Epub 2011 Oct 13.
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.
AMD3100 是 CXCR4 受体的一种有效且选择性的拮抗剂；它已被证明可阻止 HIV 进入宿主 T 细胞的途径。该化合物及其类似物随后被发现可作为造血干细胞动员剂，最近又被发现可作为抗癌剂。在这里，我们研究了 AMD3100 的荧光衍生物 L(1)，它有可能通过使用光学成像模式来评估 AMD3100 在细胞表面的行为。L(1)的双核 Zn(II)、Cu(II)和 Ni(II)配合物也进行了研究，因为这些金属以前被证明可以增强 AMD3100 的结合特性。此外，Zn(II)和 Cu(II)分别已知可以增强和猝灭类似蒽基配体的荧光。虽然 L(1)表现出抑制抗 CXCR4 单克隆抗体 12G5 结合的能力（IC(50)=0.25-0.9 μM），但蒽基部分的掺入导致与 AMD3100 相比，对 CXCR4 的亲和力显著降低（IC(50)=10 nM）。与对照细胞系相比，在用过表达 CXCR4 的小鼠前 B 细胞孵育后，我们没有观察到荧光强度有显著增加。这限制了 L(1)作为荧光成像探针的用途。有趣的是，带总正电荷的 Zn(II)配合物在体外显示出稍高的特异性和降低的毒性，尽管对 CXCR4 的亲和力降低（IC(50)=1.8-5 μM）。我们认为蒽基部分的掺入有助于游离配体的亲脂性，从而导致其穿过质膜的转运。当配体与带电金属离子络合时，这种效应似乎会减弱。
