Aromatase Inhibitors

摘要

Aromatase enzyme is the product of CYP19 gene, which is highly expressed in human placenta and in granulose cells of ovarian follicles, where its expression depends on cyclical gonadotrophin stimulation. Aromatase is also present, at lower levels, in several non-glandular tissues, including skin and adipose tissue, liver, muscle, brain, normal breast and breast cancer tissue [1]. The aromatase enzyme is responsible for the conversion of androstenedione and testosterone to the estrogens, estrone(El) and estradiol(E2), respectively. In postmenopausal women, this conversion occurs primarily in peripheral tissues while estrogen production in premenopausal women is primarily in the ovary.Aromatase inhibitors (AIs) are antioestrogenic agents, which exert their action by inhibiting aromatase enzyme. It was first developed in 1960's and over last four decades more potent and selective AIs with less toxic effects have evolved. AIs are a newer class of drugs that inhibit the function of the aromatase enzyme. In postmenopausal women, AIs can suppress most of the peripheral aromatase activity, leading to profound estrogen deprivation.