Abnormal methylation of cancer-related genes can cause tumour growth

Methylation means adding a methyl group onto something.
Methylation of DNA is an important method of regulating gene expression - it can control whether or not a gene is transcribed and translated.
When methylation is happening normally, it plays a key role in many processes in the body. It's only when it happens too much (hypermethylation) or too little (hypomethylation) that it becomes a problem.
The growth of tumours can be caused by abnormal methylation of certain cancer related genes:

When tumour suppressor genes are hypermethylated, the genes are not transcribed - so the proteins they produce to slow cell division aren't made. This means that cells are able to divide uncontrollably and tumours can develop.

Hypomethylation of proto-oncogenes causes them to act as oncogenes - increasing the production of the proteins that encourage cell division. This stimulates cells to divide uncontrollably, which causes the formation of tumours.

	Created by Lucy Nove over 7 years ago

A2 Biology (Mutations and Gene Expression) Note on Cancer, created by Lucy Nove on 29/01/2017.