Cytokeratin 34βE12

Cytokeratin 34βE12 (CK34βE12) is a group of high molecular weight cytokeratins containing keratin 1, 5, 10, and 14, mainly existing in squamous epithelium, ductal epithelium, and stratified epithelium. As a specific biomarker of basal cells, CK34βE12 is highly expressed in benign hyperplasia of prostate and breast but lowly expressed in prostate cancer and breast cancer, which makes it become an effective indicator for distinguishing benign and malignant lesions. Moreover, the expression level of CK34βE12 is down-regulated with the increased tumor malignancy, which may be because its absence will disrupt the skeletal stability of cancer cells and lead to weakened intercellular adhesion, thereby promoting tumor infiltration and metastasis. However, CK34βE12 can be expressed in basal-like breast carcinoma, and its positivity indicates poor prognosis. In addition, the positivity rate of CK34βE12 in papillary thyroid carcinoma is significantly higher than that in other thyroid lesions, suggesting that it stimulates tumor growth by participating in cell cycle dysregulation.