CK7

Overview of Cytokeratin 7 (CK7) in medical diagnostics

Cytokeratin 7 (CK7) is a type of protein expressed in the epithelial cells of the human body. It is part of the cytokeratin family, which are intermediate filament proteins that provide structural support to cells. CK7 is often used as a biomarker in immunohistochemistry to help diagnose various types of cancer and to determine the origin of metastatic tumors.

Structure and Function

CK7 is a member of the type II cytokeratins, which are typically found in simple epithelia lining the cavities of internal organs, glandular tissues, and the respiratory tract. The primary function of CK7, like other cytokeratins, is to maintain the structural integrity of epithelial cells and to participate in cellular processes such as cell signaling, apoptosis, and cellular differentiation.

Expression Patterns

CK7 is expressed in a variety of epithelial tissues, including the lung, breast, ovary, and endometrium. It is typically not expressed in the gastrointestinal tract or prostate. This expression pattern makes CK7 a useful marker in distinguishing between different types of epithelial tumors.

Clinical Significance

In the context of cancer diagnosis, CK7 is used in conjunction with other markers, such as CK20, to help identify the tissue of origin of a tumor. For example, a CK7-positive and CK20-negative profile is often seen in primary lung and breast carcinomas, while a CK7-negative and CK20-positive profile is more typical of colorectal carcinomas.

Diagnostic Use

CK7 is commonly used in the diagnostic workup of:

• Lung cancer
• Breast cancer
• Ovarian cancer
• Endometrial cancer

In immunohistochemistry, CK7 staining can help pathologists determine whether a tumor is primary or metastatic, and can aid in the differential diagnosis of adenocarcinomas.

Also see

• Cytokeratin 20
• Immunohistochemistry
• Tumor markers
• Epithelial cell
• Intermediate filament