Drouillard Donovan, Halyko Michael, Cinquegrani Elizabeth, Poimenidou Maria, Emosivbe Miracle, McAllister Donna, Peterson Francis C, Marchese Adriano, Dwinell Michael B
Department of Microbiology & Immunology, Medical College of Wisconsin, Milwaukee, WI, USA.
Center for Immunology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, 53122, USA.
Sci Rep. 2025 Jul 22;15(1):26625. doi: 10.1038/s41598-025-12005-7.
Acute myeloid leukemia (AML) is a malignancy of immature myeloid blast cells with stem-like and chemoresistant cells being retained in the bone marrow through CXCL12-CXCR4 signaling. Current CXCR4 inhibitors that mobilize AML cells into the bloodstream have failed to improve patient survival, likely reflecting persistent chemokine receptor localization on target cells. Here we characterize the signaling properties of CXCL12-locked dimer (CXCL12-LD), a bioengineered variant of the naturally occurring oligomer of CXCL12. CXCL12-LD, in contrast to wild-type or locked monomer variants, was unable to induce chemotaxis in AML cells. CXCL12-LD binding to CXCR4 decreased G protein, β-arrestin, and intracellular calcium mobilization signaling pathways, and indicated the locked dimer is a partial agonist of CXCR4. Despite these partial agonist properties, CXCL12-LD increased CXCR4 internalization compared to wild-type and monomeric CXCL12. Analysis of a previously published AML transcriptomic data showed CXCR4 positive AML cells co-express genes involved in survival, proliferation, and maintenance of a blast-like state. The CXCL12-LD partial agonist effectively mobilized stem cells into the bloodstream in mice suggesting a potential role for their use in targeting CXCR4. Together, our results suggest that enhanced internalization by CXCL12-LD partial agonist can avoid pharmacodynamic tolerance and may identify new avenues to better target GPCRs.
急性髓系白血病（AML）是一种未成熟髓系母细胞的恶性肿瘤，通过CXCL12 - CXCR4信号通路，具有干细胞样和化疗耐药性的细胞保留在骨髓中。目前能够将AML细胞动员到血液中的CXCR4抑制剂未能提高患者生存率，这可能反映了趋化因子受体在靶细胞上的持续定位。在此，我们描述了CXCL12锁定二聚体（CXCL12 - LD）的信号特性，CXCL12 - LD是CXCL12天然存在的寡聚体的一种生物工程变体。与野生型或锁定单体变体相比，CXCL12 - LD无法诱导AML细胞的趋化性。CXCL12 - LD与CXCR4的结合降低了G蛋白、β - 抑制蛋白和细胞内钙动员信号通路，并表明锁定二聚体是CXCR4的部分激动剂。尽管具有这些部分激动剂特性，但与野生型和单体CXCL12相比，CXCL12 - LD增加了CXCR4的内化。对先前发表的AML转录组数据的分析表明，CXCR4阳性AML细胞共表达参与存活、增殖和维持母细胞样状态的基因。CXCL12 - LD部分激动剂有效地将干细胞动员到小鼠血液中，表明其在靶向CXCR4方面具有潜在作用。总之，我们的结果表明，CXCL12 - LD部分激动剂增强的内化作用可以避免药效学耐受性，并可能为更好地靶向GPCRs找到新途径。
