Estrogen synthesis genes: P-450 Aromatase

Recent models of estrogen insufficiency have challenged traditional concepts of estrogen action. Studies of humans with natural mutations in the genes that encode the estrogen receptor or cytochrome P450 aromatase, and of estrogen receptor and aromatase knockout mouse models, have revealed hitherto unexpected roles for estrogen in both males and females. For example, the critical role of estrogen in the spermatogenic process would suggest that this hormone might more appropriately be termed an androgen in this context. Additionally, it is important to realize that in postmenopausal women (as in men), estrogen no longer functions as a circulating endocrine hormone; rather, it is produced in a variety of extragonadal sites (such as adipose tissue or bone) where it acts locally as a paracrine, autocrine or intracrine factor. This has great significance for our understanding of the biology of estrogen-dependent diseases such as breast cancer.