Oncogenes and proto-oncogenes
There are two main types of genes involved in the development of cancer: oncogenes and tumour suppressor genes.
- Oncogenes result in unregulated cell division.
A normal cell carries two copies of the proto-oncogene. Proto-oncogenes code for proteins that control cell division in a normal and regulated way.
Mutations or the loss of regulation of these genes can leave them permanently active and the cell begins to divide uncontrollably.
Proto-oncogenes that become permanently active through mutation are called oncogenes.
Only one of the two copies of each proto-oncogene needs to mutate into an oncogene for unregulated cell division to occur and a cancer to develop.
An oncogene arises from a gain of function mutation. It is so named because the mutation leads to permanent or increased expression of a protein.
Oncogenes code for a wide range of proteins, such as trans-membrane receptors and transcription factors.