What are Cytokeratins?
Cytokeratins are a subset of intermediate filament proteins found in the intracytoplasmic cytoskeleton of epithelial tissue. They are essential for maintaining the structural integrity of
epithelial cells. Comprising a complex family of more than 20 different polypeptides, cytokeratins are expressed in specific pairs, reflecting the type and differentiation status of the epithelial tissue.
Why are Cytokeratins Important in Histology?
Cytokeratins serve as valuable biomarkers in histology. They help in identifying the
origin and type of epithelial cells in various tissues. This makes them indispensable in diagnostic pathology, particularly in the classification of
tumors. For instance, cytokeratin expression patterns can differentiate between epithelial tumors and those of mesenchymal origin.
How are Cytokeratins Classified?
Cytokeratins are classified into two main types: Type I and Type II. Type I cytokeratins are acidic, while Type II are basic or neutral. They pair with each other to form a heterodimer. This classification is based on their isoelectric point and molecular weight. Each cytokeratin is assigned a number, such as CK8, CK18, etc., which provides information on their specific
biochemical properties.
What is the Role of Cytokeratins in Cellular Function?
Cytokeratins contribute significantly to cellular function by maintaining cell shape, enabling intracellular transport, and facilitating
cell signal transduction. They also play a critical role in the mechanical resilience of epithelial cells, enabling them to withstand various stressors. Additionally, cytokeratins participate in cell-cell and cell-matrix interactions, influencing cell movement and proliferation.
How are Cytokeratins Used in Diagnostics?
In diagnostic pathology, immunohistochemistry (IHC) is commonly used to detect cytokeratin expression. Specific antibodies target different cytokeratin proteins, allowing pathologists to determine the
tissue origin of tumors. For example, CK7 and CK20 are often used in conjunction to help diagnose and differentiate between various types of carcinomas, such as distinguishing ovarian from colorectal cancer.
Can Cytokeratins Predict Prognosis?
The expression pattern of cytokeratins can sometimes predict the prognosis of certain cancers. For instance, the presence or absence of certain cytokeratins can indicate the aggressiveness of a tumor. CK19 expression, for example, has been associated with poorer prognosis in some types of cancer. However, it is important to note that cytokeratin expression should be interpreted alongside other clinical and pathological features for a comprehensive assessment.What are Some Challenges in Using Cytokeratins?
While cytokeratins are powerful diagnostic tools, there are challenges associated with their use. One such challenge is the
heterogeneity of expression within tumors, which can complicate interpretation. Additionally, cross-reactivity of antibodies in immunohistochemistry can lead to false positives or negatives. Therefore, careful selection and validation of antibodies are crucial for accurate diagnosis.
Future Directions in Cytokeratin Research
Research on cytokeratins continues to evolve, with a focus on understanding their role in cancer biology and therapeutic applications. Advances in
molecular techniques and high-throughput screening are likely to uncover new functions of cytokeratins and their potential as therapeutic targets. Additionally, exploring the role of cytokeratin mutations and their impact on cell biology remains a promising area of study.
