EpCAM (also known as CD326) is a type I transmembrane glycoprotein composed of 314 amino acids, serving as an adhesion molecule between epithelial cells of the same antigen. It has a molecular weight of 39-42. EpCAM consists of intracellular, extracellular, and transmembrane domains, exhibiting various biological functions such as accelerating the cell cycle, promoting cell proliferation, differentiation, migration, and immune escape. Most tumors exhibit EpCAM expression, with epithelial tissue tumors showing high expression, non-epithelial tissue tumors showing weak expression or no expression, while some mesenchymal tumors only display weak positivity.
In fact, the expression of EpCAM is a dynamic process. When tumor cells migrate into the bloodstream, their EpCAM expression is downregulated compared to primary or metastatic tumors. For instance, after high EpCAM-expressing colorectal cancer cells enter the bloodstream, there is a significant decrease in EpCAM expression level, and they can be selected and enriched through CD44+ and CD47+.
