Estrogen Metabolism and Carcinogenesis in Breast Tissue

Estrogens are synthesised primarily by the enzyme aromatase in ovarian and peripheral adipose tissue and circulate in equilibrium between the more potent 17β-estradiol and the less active estrone. In breast tissue, phase I enzymes such as CYP1A1 and CYP1B1 catalyse hydroxylation at the C2 and C4 positions, yielding catechol estrogens. These catechols may be oxidised to reactive quinones that form depurinating DNA adducts, leaving apurinic sites prone to mutagenesis. Protective phase II pathways, including methylation by catechol-O-methyltransferase (COMT) and conjugation by UDP-glucuronosyltransferases, normally limit quinone accumulation. Disruption of this balance through genetic polymorphisms, environmental endocrine disruptors or inflammatory signalling can shift metabolism towards quinone generation and DNA damage. Concurrently, oestrogen receptor α (ERα) mediates proliferative signals, further promoting clonal expansion of initiated cells. Together, genotoxic metabolite formation and receptor-driven growth underpin the initiation and progression of hormone-driven breast carcinogenesis. Understanding the interplay between metabolic activation, detoxification and receptor signalling has yielded novel biomarkers of risk and informed preventive strategies, including dietary modulation and targeted enzyme inhibitors.

Research from Nature Portfolio

Recent studies employing single-cell transcriptomics have revealed that luminal epithelial subpopulations in early breast lesions exhibit elevated expression of CYP1B1 alongside reduced COMT, indicating a microenvironment predisposed to quinone formation. In parallel, mass spectrometry imaging applied to preclinical mammary models has mapped the spatial and temporal distribution of catechol estrogen-quinones in situ, demonstrating peak adduct formation in periductal regions following hormonal stimulation. A complementary proteomic investigation has identified phosphorylation of ERα at specific serine residues that facilitates recruitment of DNA repair proteins to sites of estrogen-DNA adducts, suggesting a direct link between receptor activation and the cellular response to genotoxic metabolites.

Estrogen Metabolism and Carcinogenesis in Breast Tissue publication trend

The graph below shows the total number of articles in estrogen metabolism and carcinogenesis in breast tissue across all publications each year (not limited to Nature Index journals).

Technical terms

Aromatase: Enzyme that converts androgens to oestrogens, critical for local estrogen synthesis in breast tissue.

Catechol estrogen-3,4-quinone: Oxidised form of catechol estrogens that reacts with DNA to form depurinating adducts.

Depurinating DNA adduct: Covalent attachment of a metabolite to a purine base that destabilises the glycosidic bond, leading to base loss.

Apurinic site: A location in DNA where a purine base has been removed, prone to error-prone repair and mutation.

Catechol-O-methyltransferase (COMT): Phase II enzyme that methylates catechol estrogens, preventing quinone formation.

References

1. Depurinating estrogen‐DNA adducts, generators of cancer initiation: their minimization leads to cancer prevention. Clinical and Translational Medicine (2016).
2. The 3,4-Quinones of Estrone and Estradiol Are the Initiators of Cancer whereas Resveratrol and N-acetylcysteine Are the Preventers. International Journal of Molecular Sciences (2021).
3. Urine Biomarkers of Risk in the Molecular Etiology of Breast Cancer. Breast Cancer Basic and Clinical Research (2009).
4. Estrogenized HSA induced high-affinity autoantibodies in breast cancer - Novel biomarker for early detection. Frontiers in Oncology (2024).
5. A pilot study of urinary estrogen metabolites (16alpha-OHE1 and 2-OHE1) in postmenopausal women with and without breast cancer.. Environmental Health Perspectives (1997).