Aminopeptidase N (CD13) (CD13)

Aminopeptidase N (APN), also known as CD13, is a 150 kDa zinc-dependent type II transmembrane metalloprotease that plays a pivotal role in various physiological and pathological processes [1, 10]. In the context of oncology, APN is a critical marker of neo-angiogenesis, as it is highly upregulated on the endothelial cells of tumor-associated blood vessels but is virtually absent from mature, quiescent vasculature [4, 16]. This differential expression makes it an ideal target for ligand-directed drug delivery, particularly using the NGR (asparagine-glycine-arginine) peptide motif which specifically binds to the CD13 isoform found in tumors [6, 9]. Beyond its role in angiogenesis, APN facilitates tumor progression by degrading the extracellular matrix, promoting cell migration, and modulating the activity of cytokines and chemokines through its enzymatic activity [3, 16]. Therapeutic strategies targeting APN include small-molecule inhibitors like bestatin that block its catalytic function and NGR-peptide conjugates designed to deliver potent anti-tumor agents directly to the tumor microenvironment [7, 11].

Other names

ANPEPAlanyl aminopeptidaseCD13 antigengp150p150Microsomal aminopeptidaseMembrane alanyl aminopeptidase

Inhibition of the enzymatic activity of APN/CD13 to suppress tumor cell migration, invasion, and angiogenesis; targeted delivery of therapeutic agents to the tumor microenvironment via NGR-peptide motifs that bind specifically to the CD13 isoform expressed on angiogenic endothelial cells [4, 9, 11].