Figure 5. Siglec-7/9 receptor blockade restricts PCa tumor growth in humanized mouse models.

(A) Schematic diagram depicting the implantation of PCa cells into NSG mice, followed by injection of PBMC and CD8⁺ T cell mixture and subsequent administration of anti-Siglec-7 and anti-Siglec-9 mAbs or IgG antibodies on specific days. (B) Representative images of PC3 tumors upon treatment with anti-Siglec-7/9 antibodies (n = 12) compared with IgG control (n = 12). (C) PC3 tumor growth curve and corresponding (D) tumor weight. (E) Representative images of 22Rv1 tumors upon treatment with anti-Siglec-7/9 antibodies (n = 8) compared with IgG control (n = 10). (F) 22Rv1 tumor growth curve, and corresponding (G) tumor weight. (H) Schematic diagram depicting control experiment without PBMC and CD8⁺ T cell injection. Control experiment no difference in (I) PC3 tumor growth and (J) tumor weight between anti-Siglec-7/9 antibody (n = 8) and IgG1 isotype control treatment (n = 10). (K) IHC staining of PC3 tumors treated with anti-Siglec-7/9 antibodies showing increased apoptosis (cleaved caspase 3), decreased proliferation (Ki67), decreased vascularization (CD31), and increased immune cell infiltration, including CD4⁺ and CD8⁺ T cells, compared with IgG1 control. Magnification, × 40. (L) IHC staining of 22Rv1 tumors treated with anti-Siglec-7/9 antibodies showing increased apoptosis (cleaved caspase 3), decreased proliferation (Ki67), decreased vascularization (CD31), increased macrophage (CD68) infiltration, and enhanced CD8⁺ T cell numbers compared with IgG1 control. Data were analyzed by unpaired Student’s t test and presented as mean ± SEM. **P ≤ 0.01; ***P ≤ 0.001.