Tumour suppressor genes

• Tumour suppressor genes slow down cell division, repair mistakes in DNA and control apoptosis (programmed cell death).
• Tumour suppressor genes have the opposite role to proto-oncogenes.
• A normal tumour suppressor gene maintains normal rates of cell division, preventing the formation of tumours. If a tumour suppressor gene becomes mutated, it is inactivated and consequently stops controlling cell division. This allows cells to grow out of control, potentially forming tumours.
• Mutated cells that form as a result of an abnormal tumour suppressor gene are typically structurally and functionally different to normal cells. While most of these cells die, some can survive and produce clones of themselves and form tumours.
• Most cancers are caused by acquired mutations of tumour suppressor genes, not inherited.
• One major difference between oncogenes and tumour suppressor genes is that whilst oncogenes cause cancer as a result of the activation of proto-oncogenes, tumour suppressor genes cause cancer when inactivated.