BRAINCAKEAbnormal Methylation and Cancer
Tumours can form without any mutation in the base sequence, because abnormal methylation can wrongly switch genes on or off. It contributes to tumour formation in two ways.
1. Hypermethylation of tumour suppressor genes
Increased methylation of the promoter of a tumour suppressor gene stops transcription factors binding and condenses the chromatin. The gene is not transcribed, so the protein that slows cell division is not made. Cells divide uncontrollably and a tumour forms. Hypermethylation of tumour suppressor genes, such as BRCA1, is found in many cancers, including some breast cancers.
2. Hypomethylation of oncogenes
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Key terms in this lesson
- mutation
- A random change in the base sequence of DNA (a gene mutation) or in the structure or number of chromosomes (a chromosome mutation).
More in Control of Gene Expression
- DNA Methylation
- Histone Acetylation
- Epigenetics and Disease
- Benign and Malignant Tumours
- Tumour Suppressor Genes
- Oncogenes
- Oestrogen and Breast Cancer
- Epigenetic Treatments for Cancer
All 18 lessons in Control of Gene Expression · All AQA A-level Biology topics