Sex hormone receptors (SHR)

Sex hormone receptors in breast tissue primarily include the estrogen receptor (ER), progesterone receptor (PR), and androgen receptor (AR). These receptors are members of the nuclear receptor superfamily and function as ligand-inducible transcription factors that regulate the expression of genes involved in cell growth, differentiation, and survival. In normal breast development, these receptors mediate the effects of circulating hormones to coordinate ductal and alveolar growth. In the context of breast cancer, the overexpression or overactivation of these receptors, particularly ER-alpha, drives tumor proliferation and progression. Consequently, they serve as critical therapeutic targets and diagnostic biomarkers; ER-positive and PR-positive status often dictates the use of endocrine therapies such as selective estrogen receptor modulators (SERMs) and selective estrogen receptor degraders (SERDs). Emerging research also highlights the role of the androgen receptor as a potential target in specific breast cancer subtypes, including triple-negative breast cancer. Targeting these receptors allows for precise management of hormone-sensitive malignancies, though resistance remains a significant clinical challenge.

Other names

Sex steroid receptorsNuclear sex hormone receptorsEstrogen, progesterone, and androgen receptorsSteroid hormone receptors

Drugs targeting sex hormone receptors primarily act as competitive antagonists or selective modulators that block the binding of endogenous hormones (estrogens, progestogens, or androgens) to the receptor's ligand-binding domain. This prevents the receptor from translocating to the nucleus or binding to hormone response elements on DNA, thereby inhibiting the transcription of genes that drive cell proliferation. Some agents, such as selective estrogen receptor degraders (SERDs), also induce the ubiquitination and subsequent proteasomal degradation of the receptor protein.