What are the TP53 gene and p53 protein? What does a positive TP53 mutation mean in cancer?

The TP53 gene contains instructions (genetic code) for making a protein called tumor protein p53. This protein functions as a tumor suppressor , controlling cell growth and proliferation (for example, preventing excessively rapid proliferation).

The P53 protein binds directly to DNA and is present in every cell nucleus in our body. If cellular DNA is damaged by carcinogens such as toxic chemicals, radiation or the sun's ultraviolet (UV) rays, p53 determines whether DNA will be repaired or the damaged cell will undergo programmed cell death (apoptosis). If DNA can be repaired, p53 activates other genes to correct the damage. If not, the protein prevents cell division and signals entry into apoptosis. Mutated or damaged DNA is prevented from dividing, helping p53 prevent tumor development.

P53 is so important in regulating cell division and preventing tumor formation that it has been called the guardian of DNA as its name.

More than %50 of all cancers show mutations in the TP53 tumor suppressor gene. Most commonly in bladder cancer, biliary tract cancer, head and neck cancers, ovarian cancer and Li-Fraumeni syndrome, TP53 mutations are seen.

Although the most researched cancer gene since its discovery in 1979, no cancer drug targeting TP53 has yet been developed. Different TP53 gene copy numbers in different mammals also change cancer rates; the reason elephants rarely develop cancer is that their TP53 gene copy number is approximately 20 times greater than in humans.

TP53 mutations in breast, head-and-neck, liver, blood and bone marrow cancers have been associated with a poor disease course (prognosis).

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