A suicide gene, in genetics, will cause a cell to kill itself through apoptosis. Activation of these genes can be due to many processes, but the main cellular "switch" to induce apoptosis is the p53 protein.
Stimulation or introduction (through gene therapy) of suicide genes is a potential way of treating cancer or other proliferative diseases..
By introducing the gene into a malignant tumor, the tumor would reduce in size and possibly disappear completely, provided all the individual cells have received a copy of the gene. This depends on the effectiveness of the vector (usually a virus) in reaching all the cells, and distinguishing adequately between malignant cells and those of normal tissue.
When the DNA sample in the virus is taken from the patient's own healthy cells, the virus does not need to be able to differentiate between cancer cells and healthy ones. In addition, the advantage is that it is also able to prevent metastasis upon the death of a tumor.