Oestrogen receptor and oestrogen regulated proteins in human breast cancer: a review

Area of Science:

• Endocrinology
• Oncology
• Molecular Biology

Background:

• Oestrogens influence breast growth and are key drivers in many breast cancers, forming the basis for endocrine therapy.
• Oestrogen receptors (ER) mediate oestrogen effects by binding DNA and altering gene expression, potentially involving growth factors.
• ER status in tumors is assessed via various methods, including assays and immunohistochemistry, to guide treatment.

Purpose of the Study:

• To explore the role of oestrogen receptors in breast cancer growth and endocrine therapy.
• To investigate the predictive value of oestrogen receptor status for treatment response and prognosis.
• To examine the functional integrity of the oestrogen response pathway by measuring regulated substances.

Main Methods:

• Determining oestrogen receptor status using cytosolic radioligand binding assays, enzyme-linked immunoassay, and immunohistochemistry.
• Measuring messenger RNA (mRNA) levels related to oestrogen-regulated genes.
• Assessing the expression of oestrogen-regulated substances like progesterone receptor, plasminogen activator, and cathepsin D.

Main Results:

• Tumour oestrogen receptor content is a significant predictor of response to endocrine therapy and prognosis, though not absolute.
• Some ER-negative tumors paradoxically respond to endocrine therapy, possibly due to low/heterogeneous receptor expression.
• A substantial proportion of ER-positive tumors do not respond to therapy, suggesting ER pathway dysfunction.

Conclusions:

• Oestrogen receptor status is crucial but not definitive for predicting endocrine therapy outcomes in breast cancer.
• Assessing oestrogen-regulated substances provides insights into the functional status of the oestrogen response pathway.
• Further research into ER pathway integrity is needed to optimize breast cancer treatment strategies.