Yu Wei-Bang, Ye Zi-Han, Shi Jia-Jie, Deng Wei-Qing, Chen Jun, Lu Jin-Jian
State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macau, China.
Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.
Biochem Pharmacol. 2025 Jun;236:116898. doi: 10.1016/j.bcp.2025.116898. Epub 2025 Mar 25.
CD47 is a crucial anti-phagocytic signal in regulating macrophage responses and its manipulation offers the therapeutic potential in cancer treatment. However, in many cases, blockade of CD47 by itself is insufficient to activate macrophage effectively, indicating other unidentified phagocytosis-regulating factors to resist the macrophage activity. In this study, a genome-wide human CRISPR-Cas9 library was developed for comprehensive screening of phagocytosis-regulating factors in the context of CD47 blockade. The screening results identified GSTK1 as a potential anti-phagocytic signal counteracting the efficacy of CD47-based phagocytosis. The disruption of GSTK1 significantly increased the phagocytosis rate of cancer cells by macrophages in combination with anti-CD47 antibody. Further mechanism investigation unveiled that GSTK1 blockade increased the membrane exposure of calreticulin in different cancer cells, which might be the primary mechanism driving enhanced macrophage-mediated phagocytosis. To this end, siGSTK1-loaded nanoparticles (siGSTK1-LNPs) were designed to suppress the GSTK1 expression efficiently. The comparable phagocytosis efficacy was also observed when combining siGSTK1-LNPs with anti-CD47 antibody. Above all, GSTK1 blockade was identified as a promising and feasible stimulus for enhancing the effectiveness of anti-CD47 antibody, introducing a novel and effective combination approach in cancer immunotherapy.
CD47是调节巨噬细胞反应的关键抗吞噬信号，对其进行调控具有癌症治疗潜力。然而，在许多情况下，单独阻断CD47不足以有效激活巨噬细胞，这表明存在其他未知的吞噬作用调节因子来抵抗巨噬细胞活性。在本研究中，构建了全基因组人类CRISPR-Cas9文库，用于在CD47阻断的背景下全面筛选吞噬作用调节因子。筛选结果确定GSTK1是一种潜在的抗吞噬信号，可抵消基于CD47的吞噬作用。破坏GSTK1可显著提高巨噬细胞与抗CD47抗体联合作用时对癌细胞的吞噬率。进一步的机制研究表明，阻断GSTK1可增加不同癌细胞中钙网蛋白的膜暴露，这可能是增强巨噬细胞介导的吞噬作用的主要机制。为此，设计了负载siGSTK1的纳米颗粒（siGSTK1-LNPs）以有效抑制GSTK1表达。将siGSTK1-LNPs与抗CD47抗体联合使用时，也观察到了类似的吞噬效果。最重要的是，阻断GSTK1被认为是增强抗CD47抗体疗效的一种有前景且可行的刺激因素，为癌症免疫治疗引入了一种新的有效联合方法。
