CD82

CD82, also known as KAI1, is a cell-surface glycoprotein in the tetraspanin family. Like other tetraspanins, it spans the plasma membrane four times and has two extracellular loops that mediate interactions with other proteins. CD82 is widely expressed, with notable presence on leukocytes, platelets, epithelial and endothelial cells, and it is also enriched in exosomes.

Functionally, CD82 participates in organizing tetraspanin-enriched microdomains on the cell surface, coordinating the assembly of multiprotein complexes that regulate adhesion, migration, and signaling. It interacts with various partners, including integrins (such as α3β1 and α6β1) and other tetraspanins (CD9, CD81). Through these interactions, CD82 can influence the clustering and signaling of growth-factor receptors and cytokine receptors, thereby modulating cell behavior.

In cancer, CD82 was identified as a metastasis suppressor gene in prostate cancer. In several tumor types, reduced CD82 expression correlates with higher metastatic potential, and experimental restoration of CD82 can suppress metastasis in animal models. The proposed mechanisms include alteration of cell motility and invasion, changes in cell–substrate adhesion, and regulation of signaling pathways that control proliferation and matrix remodeling.

Clinically, CD82 is studied as a potential prognostic marker in some cancers due to its association with metastasis. Therapeutic strategies aiming to enhance CD82 function or mimic its effects are the subject of preclinical investigation, but results are context-dependent and not universally applicable.