Anti-CD146 monoclonal antibody AA98 inhibits angiogenesis via suppression of nuclear factor-κB activation

Abstract

Our previous study showed that an anti-CD146 monoclonal antibody (mAb), AA98, which was raised against the vascular endothelial cells stimulated by a conditioned medium from hepatocarcinoma SMMC 7721 cells (SMMC 7721-CM), inhibited cell migration, angiogenesis, and tumor growth. However, the underlying mechanism was not elucidated. The objective of this study was to understand the mechanism by which mAb AA98 inhibits the endothelial cell migration and angiogenesis that is induced by SMMC 7721-CM. Using confocal imaging and biochemical studies, we found that SMMC 7721-CM induced nuclear factor KB (NF-KB) activation through the upstream p38 mitogen-activated protein kinase pathway, leading to the up-regulation of matrix metalloproteinase 9 and intercellular adhesion molecule 1 expression. Interestingly, all these activities stimulated by SMMC 7721-CM could be effectively inhibited by mAb AA98 in a dose-and time-dependent manner. Our data showed that the engagement of mAb AA98 with membrane protein CD146 inhibited p38 mitogen-activated protein kinase phosphorylation, suppressed NF-KB activation, and downregulated matrix metalloproteinase 9 and intercellular adhesion molecule 1 expression, suggesting that the suppression of NF-KB is a critical point for the inhibitory function of mAb AA98 on endothelial cell migration, angiogenesis, and tumor metastasis. These results will provide clues for a better understanding of the mechanisms underlying tumor angiogenesis as well as antiangiogenesis therapy.

Soluble Melanoma Cell Adhesion Molecule (sMCAM/sCD146) Promotes Angiogenic Effects on Endothelial Progenitor Cells through Angiomotin

“…Likewise, a reciprocal regulation of MelCAM and Akt has been described in human melanoma (28). Finally, biochemical studies revealed that CD146 was required for the activation of p38/IKK/NFB signaling cascade and up-regulation of NFB downstream proangiogenic genes in response to tumor secretions (29). Examination of the angiomotin structure shows that it is lacking catalytic motifs and can therefore apparently not transduce signals by itself.…”

Recognition of CD146 as an ERM-binding protein offers novel mechanisms for melanoma cell migration

“…Anfosso et al (1998) found that CD146 crosslinking by a monoclonal antibody (mAb), named Sendo1, triggers the phosphorylation of FAK through association with Fyn. Moreover, our previous works revealed that CD146 mediates tumor secretion-induced p38/IkB kinase/nuclear factor-kB signaling cascade, which is pivotal in inducing endothelial cell activation, leading to tumor angiogenesis (Yan et al, 2003;Bu et al, 2006;Zheng et al, 2009). Nevertheless, fully understanding of CD146 signaling relies on the identifications of not only the ligand, but also intracellular binding partners and effectors.…”

Generation and Characterization of a Panel of Monoclonal Antibodies Against Distinct Epitopes of Human CD146

“…(22) Further studies revealed that the mechanism of AA98-mediated anti-angiogenesis might involve its inhibition of CD146 dimerization, (23) MAPK phosphorylation, and NFB activation. (24) These evidences bring new insight into the function of CD146 in vascular and cancer biology.…”