A novel therapeutic monoclonal antibody targeting PZR demonstrates potent anti-metastatic efficacy in triple-negative breast cancer

BACKGROUND: Metastasis is the leading cause of mortality in triple-negative breast cancer (TNBC). PZR, a member of the immunoglobulin super-family, promotes the migration, invasion, and metastasis of cancer cells. Whether targeting PZR can inhibit TNBC dissemination remains unclear. In this study, we developed a novel anti-PZR monoclonal antibody (mAb) and humanized it to explore its impact on TNBC metastasis. METHODS: Recombinant PZR-ECD protein was used to generate anti-PZR monoclonal antibodies, whose binding affinity was evaluated by SPR. Their effects on cell migration were assessed via Trans-well assays. Antibody specificity was confirmed by western blotting, Co-IP, and FACS. PZR mediated TNBC cell interactions with the ECM were examined through cell adhesion experiments. The therapeutic efficacy of the PZR antibody was evaluated in a TNBC metastasis mouse model. RESULTS: Our findings revealed that the mouse anti-PZR mAb (12F6) exhibited high-affinity binding to the recombinant PZR protein. The 12F6 mAb specifically recognized the native PZR protein expressed by TNBC cells and was efficiently internalized by PZR-positive TNBC cells. Furthermore, 12F6 significantly inhibited the migration and metastasis of PZR-positive TNBC cells in both in vitro and in vivo settings. PZR was found to interact with integrin β1, promoting the fibronectin-dependent adhesion and FAK activation of TNBC cells. The humanized 12F6 antibody (Hu12F6) maintained comparable binding affinity to PZR in comparison with the parental 12F6 antibody and effectively inhibited the migration and metastasis of PZR-positive TNBC cells in both in vitro and in vivo experiments. CONCLUSIONS: The results of our study support a model by which PZR interacting with integrin β1 enhances fibronectin-dependent integrin signaling and biological functions. Hu12F6 by blocking the interaction between PZR and integrin β1 may offer a novel therapeutic strategy to treat PZR-positive metastatic cancers including TNBC.