GATA-3

GATA3 (GATA binding protein 3) is a protein found in the nucleus of specific cells. It plays a crucial role in regulating how these cells grow and develop by controlling the activity of specific genes. GATA3 is especially important in the normal development of breast tissue, the urinary tract (urothelium), and certain immune cells.​

What types of normal tissues express GATA3?

GATA3 is normally expressed by cells in the following types of tissue:​

• Breast tissue, particularly in the cells lining the ducts and glands.

• The lining of the urinary tract, including the bladder and ureters.

• Specific immune cells, such as T cells.

• Other tissues, including parts of the skin, kidneys, and reproductive organs.

How do pathologists test for GATA3?

Pathologists use a technique called immunohistochemistry (IHC) to detect GATA3 in tissue samples. This method involves applying special antibodies to the tissue that bind specifically to the GATA3 protein. If GATA3 is present, the antibodies will attach to it and produce a color change that can be seen under a microscope. The presence of GATA3 is typically observed in the nucleus of the cell.​ Cells that express GATA3 will be described as positive (or reactive) while those that do not express the protein will be described as negative (or nonreactive).

What types of tumors express GATA3?

GATA3 is commonly found in several types of tumors, including:​

• Breast cancer: Most breast cancers, especially those that are estrogen receptor-positive, show GATA3 expression.

• Urothelial carcinoma: Many cancers of the urinary tract lining, such as bladder cancer, express GATA3.

• Paragangliomas and pheochromocytomas: These rare tumors of nerve tissue often show GATA3 positivity.

• Skin-related tumors: Certain skin cancers, including basal cell carcinoma and skin adnexal tumors, may express GATA3.

• Other tumors: Some cancers of the kidney (such as chromophobe renal cell carcinoma), salivary glands, and reproductive organs can also express GATA3, although less commonly.​

Because GATA3 is present in various tumor types, pathologists often use it in conjunction with other markers to help determine the tumor’s origin.​

Why is GATA3 important in a pathology report?

When pathologists test a tumor for GATA3, the results can provide valuable information about the tumor’s origin and type.

• In cases where cancer has metastasized (spread) and the original site is unknown, GATA3 positivity can suggest a breast or urothelial origin.

• In breast cancer, GATA3 expression is often associated with hormone receptor-positive tumors, which may respond well to hormone therapies.

• The presence or absence of GATA3 can aid in distinguishing between different tumor types that may appear similar under the microscope.​

Overall, GATA3 is a valuable tool for pathologists to aid in the diagnosis of certain cancers and inform treatment decisions.​