Aromatase in aging women

Area of Science:

• Endocrinology
• Molecular Biology
• Cell Biology

Background:

• Estrogen production significantly decreases after ovarian function ceases during menopause.
• Aromatase, an enzyme, is crucial for converting androgens to estrogens in various human tissues, including adipose tissue, skin, and brain.
• Extraglandular aromatase activity, particularly in adipose tissue, becomes a primary source of estrogen with aging and increased body weight.

Purpose of the Study:

• To review the molecular and cellular mechanisms of estrogen formation by aromatase.
• To discuss the physiological and clinical relevance of aromatase expression and estrogen biosynthesis.
• To explore the complex regulation of aromatase expression through alternative promoter usage.

Main Methods:

• Review of scientific literature on aromatase function, expression, and regulation.
• Analysis of aromatase's role in extraglandular estrogen production.
• Examination of promoter usage and its impact on cellular estrogen levels.

Main Results:

• Aromatase in adipose tissue and skin contributes significantly to peripheral estrogen formation, increasing with body weight and age.
• Elevated estrogen levels due to aromatase activity are linked to uterine bleeding, endometrial hyperplasia, and cancer in obese postmenopausal women.
• Aromatase expression in adipose tissue, skin, and bone plays a key role in modulating postmenopausal bone loss.
• Dysregulated aromatase expression in specific tissues (breast carcinoma, endometriosis, endometrial cancer) leads to increased local estrogen concentrations, promoting steroid-responsive tissue growth.
• Local estrogen synthesis in the brain via aromatase influences cognitive and hypothalamic functions.
• Aromatase expression is regulated by distinct promoters (e.g., promoter II in ovaries, promoter I.1 in placenta, promoters I.3/I.4 in adipose tissue).
• Promoter usage can be modulated by hormones, prostaglandins, glucocorticoids, cytokines, and the presence of carcinoma.

Conclusions:

• Aromatase is a critical enzyme in estrogen biosynthesis with diverse physiological roles and clinical implications.
• Complex regulation of aromatase expression via alternative promoters contributes to tissue-specific estrogen production and disease pathogenesis.
• Understanding aromatase mechanisms is vital for managing estrogen-related conditions, including menopausal symptoms, bone loss, and hormone-dependent cancers.