Aromatase: Contributions to Physiology and Disease in Women and Men

Aromatase (estrogen synthetase; EC 1.14.14.1) catalyzes the demethylation of androgens' carbon 19, producing phenolic 18-carbon estrogens. Aromatase is most widely known for its roles in reproduction and reproductive system diseases, and as a target for inhibitor therapy in estrogen-sensitive diseases including cancer, endometriosis, and leiomyoma (141, 143). However, all tissues contain estrogen receptor-expressing cells, the majority of genes have a complete or partial estrogen response element that regulates their expression (61), and there are plentiful nonreceptor effects of estrogens (79); therefore, the effect of aromatase through the provision of estrogen is almost universal in terms of health and disease. This review will provide a brief but comprehensive overview of the enzyme, its role in steroidogenesis, the problems that arise with its functional mutations and mishaps, the roles in human physiology of aromatase and its product estrogens, its current clinical roles, and the effects of aromatase inhibitors. While much of the story is that of the consequences of the formation of its product estrogens, we also will address alternative enzymatic roles of aromatase as a demethylase or nonenzymatic actions of this versatile molecule. Although this short review is meant to be thorough, it is by no means exhaustive; rather, it is meant to reflect the cutting-edge, exciting properties and possibilities of this ancient enzyme and its products.