Cytokeratin 7

Cytokeratin 7 (CK7) is an alkaline keratin that mainly exists in glandular epithelium and transitional epithelium. It has various functions such as maintaining morphology, regulating proliferation, and mediating migration. In clinical practice, CK7 is an effective indicator to differentiate adenocarcinoma and squamous cell carcinoma. It has been widely used in the diagnosis of lung adenocarcinoma, pancreatic cancer, breast cancer, ovarian cancer, endometrial cancer and other adenocarcinoma tissues, and plays an important role in distinguishing primary and metastatic tumors. However, CK7 can be expressed in esophageal squamous cell carcinoma, and the patients have lower survival rate, indicating that cancer cells with altered expression patterns have more malignant biological behavior. In addition, the early mainstream believed that CK7 expression deletion was a pathological feature of primary liver cancer and colorectal cancer, but recent research found some tumors with CK7 positivity, and the patients have worse prognosis, which may be because cancer cells differentiate into CK7+ stem cells with high invasive potential as they progress malignant.