Estrogen receptor (ER)

The estrogen receptor (ER) is a protein found inside and on the surface of certain cells. It is a nuclear hormone receptor that is activated by the hormone estrogen. There are two main types of estrogen receptors: ERα (alpha) and ERβ (beta). When activated by estrogen, these receptors are involved in the transcription of specific genes, playing an important role in various physiological processes.

What does the estrogen receptor do?

The estrogen receptor changes its shape upon binding with estrogen, allowing it to bind to specific DNA sequences called estrogen response elements (EREs). This binding can regulate the expression of genes involved in a wide range of biological functions, including:

• Reproductive and sexual development: Influencing the development and function of the reproductive system.
• Bone density: Regulating bone metabolism and maintaining bone density.
• Cardiovascular health: Playing a role in maintaining cardiovascular health by affecting blood vessels and heart function.
• Brain function: Involved in protecting neural functions and mood regulation.

Types of cells that normally express estrogen receptor

Estrogen receptors are expressed in various tissues, reflecting estrogen’s widespread role in the body. Normal cells that commonly express estrogen receptors include breast, endometrial, ovarian, bone, heart, and brain cells.

Types of tumors that express estrogen receptor

The expression of estrogen receptors is an important factor in the growth of certain types of tumors, particularly those in tissues sensitive to estrogen, such as:

• Breast cancer: ER-positive breast cancers depend on estrogen for their growth.
• Endometrial cancer: Some types of cancer in the uterus have cells that express ERs.
• Ovarian cancer: Certain ovarian cancers express estrogen receptors, though less commonly than breast and endometrial cancers.

How do pathologists test for estrogen receptors in a tissue sample and why is testing important?

Pathologists test for the presence of estrogen receptors in tissue samples using immunohistochemistry (IHC). This technique involves the use of antibodies that specifically bind to the estrogen receptor protein. The presence of these receptors can then be visualized under a microscope, usually indicated by a staining pattern in the cells.

Testing for estrogen receptors in tumors, particularly in breast cancer, is critically important for several reasons:

• Diagnosis and prognosis: ER status helps in understanding the behavior of the cancer and predicting the patient’s prognosis. ER-positive cancers often have a better prognosis and may grow more slowly.
• Treatment planning: ER-positive cancers may respond to hormone therapy aimed at blocking the effects of estrogen or lowering its levels in the body. Drugs such as tamoxifen or aromatase inhibitors are commonly used in treating ER-positive breast cancer.

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About this article

Doctors wrote this article to help you read and understand your pathology report. Contact us if you have questions about this article or your pathology report. For a complete introduction to your pathology report, read this article.

Other helpful resources

Atlas of pathology