Novel Antibody Exerts Antitumor Effect through Downregulation of CD147 and Activation of Multiple Stress Signals.

CD147 is an immunoglobulin-like receptor that is highly expressed in various cancers and involved in the growth, metastasis, and activation of inflammatory pathways via interactions with various functional molecules, such as integrins, CD44, and monocarboxylate transporters. Through screening of CD147-targeting antibodies with antitumor efficacy, we discovered a novel rat monoclonal antibody #147D. This humanized IgG4-formatted antibody, h4#147D, showed potent antitumor efficacy in xenograft mouse models harboring the human PDAC cell line MIA PaCa-2, HCC cell line Hep G2, and CML cell line KU812, which featured low sensitivity to the corresponding standard-of-care drugs (gemcitabine, sorafenib, and imatinib, respectively). An analysis of tumor cells derived from MIA PaCa-2 xenograft mice treated with h4#147D revealed that cell surface expression of CD147 and its binding partners, including CD44 and integrin α3ß1/α6ß1, was significantly reduced by h4#147D. Inhibition of focal adhesion kinase (FAK), activation of multiple stress responsible signal proteins such as c-JunN-terminal kinase (JNK) and mitogen-activated protein kinase p38 (p38MAPK), and expression of SMAD4, as well as activation of caspase-3 were obviously observed in the tumor cells, suggesting that h4#147D induced tumor shrinkage by inducing multiple stress responsible signals. These results suggest that the anti-CD147 antibody h4#147D offers promise as a new antibody drug candidate.