Cheng Kexuan, Guo Jiazheng, Li Yating, Kang Qinglin, Wang Rong, Luo Longlong, Wang Wei, Lu Jiansheng
Laboratory of Advanced Biotechnology, Beijing Institute of Biotechnology, Beijing 100081, China.
College of Public Health, Zhengzhou University, Zhengzhou 450001, China.
Int J Mol Sci. 2025 May 24;26(11):5068. doi: 10.3390/ijms26115068.
Immune checkpoint inhibitors like programmed cell death 1 (PD-1) antibodies have revolutionized cancer treatment, but patient response rates remain limited. Sialic acid-binding Ig-like lectin 15 (Siglec-15) has emerged as a promising new immune checkpoint target. Through phage display technology using a Bactrian camel immunized with recombinant human Siglec-15, we generated six anti-Siglec-15 camelid nanobodies and constructed chimeric heavy-chain antibodies by fusing the VHH domains with human IgG-Fc. Following expression in HEK293-F cells and purification, three antibodies (S1, S5, S6) demonstrated specific binding to both human and murine Siglec-15 in ELISA and biolayer interferometry assays. In a xenograft model established by subcutaneous inoculation of NCI-H157-S15 cells into BALB/c nude mice, these antibodies showed distinct tumor targeting and significant blockade of Siglec-15 interactions with CD44, MAG, sialyl-Tn, and LRR4C ligands. All three antibodies exhibited anti-tumor effects, with S1 showing the most potent activity. S1-treated mice had significantly smaller tumor volumes and weights compared to controls. The S1, S5, and S6 treatment groups showed enhanced anti-tumor immunity, with reduced TGF-β, IL-6, and IL-10 levels. Notably, S1 treatment significantly increased tumor-associated macrophages in tumor tissues ( < 0.05). In conclusion, S1 exhibits remarkable anti-tumor activity and has the potential to be developed as a cancer immunotherapy targeting Siglec-15.
程序性细胞死亡蛋白1（PD-1）抗体等免疫检查点抑制剂彻底改变了癌症治疗方式，但患者的反应率仍然有限。唾液酸结合免疫球蛋白样凝集素15（Siglec-15）已成为一个有前景的新免疫检查点靶点。通过使用重组人Siglec-15免疫双峰驼的噬菌体展示技术，我们制备了六种抗Siglec-15骆驼科纳米抗体，并通过将VHH结构域与人IgG-Fc融合构建了嵌合重链抗体。在HEK293-F细胞中表达并纯化后，三种抗体（S1、S5、S6）在酶联免疫吸附测定（ELISA）和生物膜干涉测量分析中显示出与人及小鼠Siglec-15的特异性结合。在将NCI-H157-S15细胞皮下接种到BALB/c裸鼠中建立的异种移植模型中，这些抗体表现出明显的肿瘤靶向性，并显著阻断了Siglec-15与CD44、MAG、唾液酸化Tn和LRR4C配体的相互作用。所有三种抗体均表现出抗肿瘤作用，其中S1表现出最强的活性。与对照组相比，接受S1治疗的小鼠肿瘤体积和重量明显更小。S1、S5和S6治疗组显示出增强的抗肿瘤免疫力，TGF-β、IL-6和IL-10水平降低。值得注意的是，S1治疗显著增加了肿瘤组织中的肿瘤相关巨噬细胞（P<0.05）。总之，S1表现出显著的抗肿瘤活性，有潜力被开发成为一种靶向Siglec-15的癌症免疫疗法。
