Screening and Identification of a Novel Anti-siglec-15 Human Antibody 3F1 and the Research on Its Antitumor Activity
35 Pages Posted: 28 Oct 2021
Siglec-15, as an important immunosuppressive molecule, is considered as an important target in the next generation of tumor immunotherapy. In this study, we screened multiple high affinity antibodies that specifically recognized human siglec-15 by using human phage antibody library with large capacity, and verified their binding, blocking and biological activities in vitro and in vivo. The results showed that the selected antibodies could effectively bind to siglec-15 overexpressed cell lines. As the reported ligands of siglec-15, the binding activity of siglec-15 and sialyl-Tn, CD44, MAG and LRRC4C can be blocked by 3 of the candidate antibodies, among them, 3F1 has a competitive advantage, which indicate 3F1 can effectively breaking down the tumor microenvironment by siglec-15 immunosuppressive signals. In addition, 3F1 antibody could reverse the inhibitory effect of siglec-15 on lymphocyte proliferation (especially CD4+T, CD8+T) and cytokine release (IFN-γ). In the tumor model of Balb/c Nude mice, mice were subcutaneously inoculated with genetically modified human non-small-cell lung carcinoma cell line H157 (overexpressed with siglec-15), compared with PBS group, 3F1 showed certain anti-tumor effect, moreover, the combination of 3F1 and ERBITUX showed significant antitumor effect (p<0.05). In conclusion, a novel human antibody 3F1 targeting human siglec-15 was obtained from phage display. The antibody has certain anti-tumor activity and is expected to be an innovative candidate drug targeting siglec-15 for tumor immunotherapy.
Funding: This research was supported by the National Natural Sciences Foundation of China grant (No. 31771010, No. 81700122).
Declaration of Interests: The authors declare no conflict of interest
Animal Care Committee Approval Statement: The Experimental Animal Management and use committee of my institute has reviewed the Animal Experiment Program and approved it.
Keywords: siglec-15, immune checkpoint molecules, tumor immunotherapy, human phage antibody library, ligands
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