BRAINCAKEOestrogen and Breast Cancer
Oestrogen stimulates the growth and division of breast cells as part of normal development. Increased oestrogen concentrations are linked to the development of some breast cancers.
After the menopause, the ovaries stop producing oestrogen, but fat cells in the breast continue to produce it. Women who are exposed to more oestrogen over their lifetime, for example because of higher body fat, early puberty or a late menopause, have a higher risk of breast cancer.
How increased oestrogen may lead to a tumour:
• Oestrogen binds to the oestrogen receptor, which acts as a transcription factor. It can switch on genes that promote cell division, such as proto-oncogenes. If such a gene is mutated, or is over-expressed because of high oestrogen, cells divide uncontrollably.
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Key terms in this lesson
- positive feedback
- A control mechanism in which a change in a factor brings about effects that amplify the change further, rather than reversing it.
- mutation
- A random change in the base sequence of DNA (a gene mutation) or in the structure or number of chromosomes (a chromosome mutation).
- genotype
- The genetic constitution of an organism, i.e. the particular combination of alleles it possesses.
More in Control of Gene Expression
- DNA Methylation
- Histone Acetylation
- Epigenetics and Disease
- Benign and Malignant Tumours
- Tumour Suppressor Genes
- Oncogenes
- Abnormal Methylation and Cancer
- Epigenetic Treatments for Cancer
All 18 lessons in Control of Gene Expression · All AQA A-level Biology topics