Effects of oestrogens and anti-oestrogens on normal breast tissue from women bearing BRCA1 and BRCA2 mutations

• Published in: British journal of cancer 2006-04, Vol.94 (7), p.1021-1028
• Main Authors: Bramley, M, Clarke, R B, Howell, A, Evans, D G R, Armer, T, Baildam, A D, Anderson, E
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Breast - drug effects; Breast - physiology; Breast cancer; Breast Neoplasms - genetics; Breast Neoplasms - prevention & control; Cancer Research; Cell Proliferation; Drug Resistance; Endocrine therapy; Epidemiology; Estradiol - analogs & derivatives; Estradiol - pharmacology; Estradiol - physiology; Estrogen Antagonists - pharmacology; Estrogen Receptor alpha - biosynthesis; Family medical history; Female; Fulvestrant; Gene Expression Regulation - drug effects; Genes, BRCA1; Genes, BRCA2; Humans; Medical research; Medical sciences; Middle Aged; Molecular Medicine; Mutation; Oncology; Oophorectomy; Prevention; Receptors, Progesterone - biosynthesis; Risk Factors; Steroids; Tamoxifen - pharmacology; Translational TherapeuticsTranslational Therapeutics; translational-therapeutics; Tumors; Womens health
• ISSN: 0007-0920; 1532-1827
• DOI: 10.1038/sj.bjc.6603042

There is considerable interest in whether anti-oestrogens can be used to prevent breast cancer in women bearing mutations in the BRCA1 and BRCA2 genes. The effects of oestradiol (E 2 ), tamoxifen (TAM) and fulvestrant (FUL) on proliferation and steroid receptor expression were assessed in normal breast epithelium taken from women at varying risks of breast cancer and implanted into athymic nude mice, which were treated with E 2 in the presence and absence of TAM or FUL. Tissue samples were taken at various time points thereafter for assessment of proliferative activity and expression of oestrogen and progesterone receptors (ER α and PgR) by immunohistochemistry. Oestradiol increased proliferation in the breast epithelium from women carrying mutations in the BRCA1/2 genes, those otherwise at increased risk and those at population risk of breast cancer. This increase was reduced by both TAM and FUL in all risk groups. In the absence of E 2 , PgR expression was reduced in all risk groups but significantly more so in the BRCA -mutated groups. Subsequent E 2 treatment caused a rapid, complete induction of PgR expression in the population-risk group but not in the high-risk or BRCA -mutated groups in which PgR induction was significantly delayed. These data suggest that the mechanisms by which E 2 induces breast epithelial PgR expression are impaired in BRCA1/2 mutation carriers, whereas those regulating proliferation remain intact. We conclude that early anti-oestrogen treatment should prevent breast cancer in very high-risk women.