Hormonal enzymatic systems in normal and cancerous human breast: control, prognostic factors, and clinical applications

The bioformation and transformation of estrogens and other hormones in the breast tissue as a result of the activity of the various enzymes involved attract particular attention for the role they play in the development and pathogenesis of hormonedependent breast cancer. The enzymatic process concerns the aromatase, which transforms androgens into estrogens; the sulfatase, which hydrolyzes the biologically inactive sulfates to the active hormone; the 17 beta-hydroxysteroid dehydrogenases, which are involved in the interconversion estradiol/estrone or testosterone/androstenedione; hydroxylases, which transform estrogens into mitotic and antimitotic derivatives; and sulfotransferases and glucuronidases, which, respectively convert into the biologically inactive sulfates and glucuronides. These enzymatic activities are more intense in the carcinoma than in the normal tissue. Concerning aromatase, the application of antiaromatase agents has been largely developed in the treatment of breast cancer patients, with very positive results. Various studies have shown that the activity levels of these enzymes and their mRNA can be involved as interesting prognostic factors for breast cancer. In conclusion, the application of new antienzymatic molecules can open attractive perspectives in the treatment of hormone-dependent breast cancer.