Uroplakin III

Uroplakin Ⅲ (UPK3) is a highly conserved urinary tract epithelial cell specific glycoprotein, and it is a crucial component in maintaining normal structure and function of the bladder. Some research has found that UPK3 can form plaque structures together with other UPK subtypes, which will cover the transitional epithelial cells on the surface of mucosa. When the bladder dilates, plaques can fuse with intracellular vesicles to expand the cell surface area and prevent damage. When it contracts, plaques are stored in the form of vesicles inside the cell. In clinical practice, UPK3 is mainly used for the diagnosis of primary and metastatic urothelium derived tumors. Especially, it has become a specific biomarker for bladder transitional cell carcinoma (BTCC). But UPK3 has low sensitivity, so it is often used in combination with GATA3, P63, S100P, UPK2, and other antibodies. Meanwhile, some scholars pointed out that the expression level of UPK3 is down-regulated with increased tumor invasiveness, speculated that its expression deletion can promote tumor angiogenesis. This indicates that UPK3 can be used as an indicator to evaluate the malignancy of BTCC.