Cytokeratin 17

Cytokeratin 17 (CK17) is a high molecular weight intermediate filament protein primarily exists in the basal cells of stratified and pseudostratified epithelia, It has various functions such as stabilizing cell structure, regulating cell cycle, and participating in immune response. In clinical practice, CK17 is mainly used as an important diagnostic indicator for oral squamous cell carcinoma, esophageal squamous cell carcinoma, lung squamous cell carcinoma, and other squamous cell carcinoma, and its expression level is positively correlated with the malignancy of the tumor. This may be because CK17 induces cell proliferation by regulating tumor suppressor protein P27 and promotes tumor angiogenesis by stimulating endothelial cell activity. Meanwhile, CK17 is believed to specifically label cervical stem cells, and its expression decreases with cell maturation. So it is highly expressed in cervical immature squamous metaplasia but lowly expressed in cervical intraepithelial neoplasia, which makes it useful for assisting in identification. In addition, CK17 becomes a new biomarker for urothelial carcinoma and is closely associated with muscle infiltration.