STAT6

STAT6 (Signal Transducer and Activator of Transcription 6) is a protein found in cells. It plays a key role in transmitting signals from outside a cell to its nucleus, where genetic material is stored. This signaling helps regulate how cells grow, divide, and respond to their environment. STAT6 is especially important in controlling immune system functions and inflammation.

What types of normal cells and tissue express STAT6?

In healthy tissues, STAT6 is mainly found in immune system cells, such as specific white blood cells. It helps these cells communicate and respond to signals like infections or other immune challenges. However, STAT6 can also be active in other cell types when responding to inflammation or similar signals.

What types of tumours express STAT6?

STAT6 expression is a key feature of some specific types of tumours, including:

• Solitary fibrous tumor: Nearly all solitary fibrous tumours (98–100%), regardless of their location or appearance under the microscope, show strong and diffuse STAT6 expression.
• Dedifferentiated liposarcoma: About 11–14% of dedifferentiated liposarcomas show STAT6 expression. This occurs because the gene for STAT6 is located close to another gene called MDM2 on chromosome 12, and their proximity can influence each other.
• Deep fibrous histiocytoma: About 10% of deep fibrous histiocytomas show weak STAT6 expression.

Why do pathologists test for STAT6?

Pathologists test for STAT6 to help identify specific types of tumours, especially solitary fibrous tumours. These tumors are often difficult to diagnose based on their appearance alone, so testing for STAT6 provides a strong clue to confirm the diagnosis. Testing for STAT6 can also help distinguish solitary fibrous tumours from others that may look similar but require different treatments.

How do pathologists test for STAT6?

STAT6 is detected using a technique called immunohistochemistry (IHC). In this process, antibodies are applied to a tissue sample. These antibodies are designed to bind to STAT6 if it is present. A chemical reaction then creates a color change, allowing pathologists to see STAT6 under the microscope.

In a pathology report, the results for STAT6 are typically described as “positive” or “negative”:

• STAT6-positive: This means the tumour cells produce STAT6.
• STAT6-negative: This means STAT6 is not detected, which may point to other types of tumours or conditions.