Cryptic RGDKGE epitope of denatured type I collagen (RGDKGE epitope)

The cryptic RGDKGE epitope is a specific peptide sequence located within the alpha-chain of type I collagen that is inaccessible in the native, triple-helical conformation of the protein (Brooks et al., 1998). Exposure of this epitope occurs through biochemical denaturation or proteolytic degradation by matrix metalloproteinases (MMPs), such as MMP-2 and MMP-9, which are frequently upregulated in the tumor microenvironment and sites of chronic inflammation (Xu et al., 2001). Once exposed, the RGDKGE sequence functions as a high-affinity ligand for integrin alpha-v beta-3 (αvβ3), facilitating endothelial cell adhesion, migration, and proliferation necessary for angiogenesis (Hangai et al., 2002). Therapeutic strategies targeting this epitope, such as the monoclonal antibody TRC093 (HUIV26), aim to selectively disrupt these interactions to inhibit pathological vessel growth and tumor expansion while sparing healthy tissues where collagen remains intact (Tracon Pharmaceuticals). This selectivity offers a potential safety advantage over broad-spectrum anti-angiogenic agents by specifically targeting the remodeled extracellular matrix associated with disease states.

Other names

HUIV26 epitopeXL313 epitopeDenatured type I collagen neoepitopeCryptic collagen siteProteolyzed collagen epitope

Selective binding to the exposed RGDKGE motif prevents integrin alpha-v beta-3 mediated endothelial cell attachment to denatured collagen, inducing apoptosis and inhibiting angiogenesis.