PO.CL05.05 · 临床研究
药理学靶向CTPS1可引发巨噬细胞介导的抗白血病免疫
Pharmacological targeting of CTPS1 elicits macrophage-mediated anti-leukemia immunity
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
免疫疗法在急性髓系白血病（AML）中疗效有限，部分原因是巨噬细胞等固有免疫细胞保持无活性状态。核苷酸代谢调控关键的细胞过程，而胞苷三磷酸合成酶1（CTPS1）作为负责从头合成CTP的酶，对细胞增殖至关重要。我们此前（Liu，2024 ASH）已证明，高CTPS1活性促进AML生长并抑制抗肿瘤免疫。因此，CTPS1抑制剂STP-B以一种免疫依赖的方式显著延长了免疫健全白血病小鼠的生存期。在TCGA各类癌症中，CTPS1表达与M1巨噬细胞特征呈负相关。在此，我们表明STP-B发挥抗AML活性的途径包括：（1）诱导髓系分化，尤其是通过dNTP失衡促进M1样巨噬细胞极化；（2）通过阻断CTPS1介导的IRF3和组蛋白H1脱酰胺化来激活IFN-I信号。在同基因MLL-AF9（MA9）模型中，每日口服STP-B（100 mg/kg，3周）降低了白血病负荷，并显著增加了CD11b⁺F4/80⁺巨噬细胞，富集了M1样亚群。巨噬细胞清除完全消除了生存获益。与抗CD47联合产生了强烈的协同作用。对MA9细胞和非恶性髓系细胞的转录组分析显示M1相关基因（Il6、Il1a、Cxcl9、Cxcl10）被诱导。在离体条件下，STP-B处理的BMDMs对MA9细胞的吞噬作用显著增强。为评估对人类造血的影响，对植入CD34⁺脐带血的NSG小鼠给予STP-B治疗。虽然人CD45⁺总水平未变，但髓系（CD33⁺CD11b⁺）、单核细胞（CD14⁺CD64⁺）和HLA-DR⁺CD86⁺ M1样巨噬细胞群体增加，且髓系转录因子和人M1基因表达更高。THP-1细胞的代谢组学分析证实STP-B显著降低了细胞内CTP，表明存在核苷酸失衡。核糖核苷酸还原酶抑制部分恢复了平衡，逆转了分化，并抑制了STP-B诱导的M1基因表达，支持一种核苷酸驱动的分化机制。GSEA显示IFN-I应答基因被诱导。STP-B增加了gammaH2AX和核内S9.6染色，与CTPS1介导的组蛋白H1脱酰胺化受抑制所导致的DNA损伤一致。STP-B还阻断了CTPS1依赖的IRF3脱酰胺化，增强了ISG表达。用谷氨酰胺酶缺陷的CTPS1突变体重建CTPS1敲除的THP-1细胞同样增加了ISGs，表明CTPS1的脱酰胺化活性抑制IFN信号。综上所述，这些发现表明STP-B促进巨噬细胞定型和固有免疫激活，将STP-B定义为一种具有强大免疫刺激特性的白血病消融剂。
查看英文原文 English abstract
Immunotherapy has limited efficacy in acute myeloid leukemia (AML), partly because innate immune cells such as macrophages remain inactive. Nucleotide metabolism regulates key cellular processes, and cytidine triphosphate synthase 1 (CTPS1), the enzyme responsible for de novo CTP synthesis, is essential for cell proliferation. We previously showed (Liu, 2024 ASH) that high CTPS1 activity promotes AML growth and suppresses antitumor immunity. Accordingly, the CTPS1 inhibitor STP-B significantly prolonged the survival of immunocompetent leukemic mice in an immune-dependent manner. Across TCGA cancers, CTPS1 expression negatively correlated with M1-macrophage signatures.Here, we show that STP-B exerts anti-AML activity by (1) inducing myeloid differentiation, especially M1-like macrophage polarization through dNTP imbalance, and (2) activating IFN-I signaling by blocking CTPS1-mediated deamidation of IRF3 and histone H1. In a syngeneic MLL-AF9 (MA9) model, daily oral STP-B (100 mg/kg, 3 weeks) reduced leukemia burden and markedly increased CD11b⁺F4/80⁺ macrophages, enriching the M1-like subset. Macrophage depletion completely abolished the survival benefit. Combination with anti-CD47 produced strong synergy. Transcriptomic analysis of MA9 cells and non-malignant myeloid cells showed induction of M1-associated genes (Il6, Il1a, Cxcl9, Cxcl10). Ex vivo, STP-B-treated BMDMs displayed significantly enhanced phagocytosis of MA9 cells. To evaluate human hematopoietic effects, CD34⁺ cord blood-engrafted NSG mice were treated with STP-B. While total human CD45⁺ levels were unchanged, myeloid (CD33⁺CD11b⁺), monocyte (CD14⁺CD64⁺), and HLA-DR⁺CD86⁺ M1-like macrophage populations increased, with higher expression of myeloid transcription factors and human M1 genes. Metabolomic profiling of THP-1 cells confirmed that STP-B markedly reduced intracellular CTP, indicating nucleotide imbalance. Ribonucleotide reductase inhibition partially restored balance, reversed differentiation, and suppressed STP-B-induced M1-gene expression, supporting a nucleotide-driven differentiation mechanism. GSEA demonstrated induction of IFN-I-responsive genes. STP-B increased gammaH2AX and nuclear S9.6 staining, consistent with DNA damage caused by inhibition of CTPS1-mediated histone H1 deamidation. STP-B also blocked CTPS1-dependent IRF3 deamidation, enhancing ISG expression. Reconstitution of CTPS1-knockout THP-1 cells with a glutaminase-deficient CTPS1 mutant similarly increased ISGs, indicating that CTPS1 deamidation activity suppresses IFN signaling. Together, these findings show that STP-B promotes macrophage specification and innate immune activation, defining STP-B as a leukemia-ablating agent with strong immunostimulatory properties.
利益披露 Disclosure
M. Liu, None.