Clinical significance of estrogen receptor β in breast and prostate cancer from biological aspects

Breast and prostate cancers are among the most common of all cancers. They are referred to as hormone-dependent cancers, because estrogen and androgen are involved in their development and growth. The effects of these hormones are mediated by their respective receptors, estrogen receptor (ER) and androgen receptor. Around 18years ago, a second ER, ER, which has a very similar structure to ER, was discovered. Its function has been investigated using a variety of methods and biological systems, leading to our present understanding that ER can interact with or inhibit ER and androgen receptor function directly and/or indirectly, suppress cell growth, and influence responsiveness to endocrine therapy. In order to apply the inhibition of cell growth function to cancer treatment, several specific ER agonists have been synthesized and are being tested for effectiveness in cancer treatment. We need to keep our eyes on ER.