PTEN (gene)

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PTEN structure (PDB entry 1D5R visualized using PyMOL).

PTEN (phosphatase and tensin homolog (mutated in multiple advanced cancers 1)) is a human gene that acts as a tumor suppressor gene, which means that it helps regulate the cycle of cell division by keeping cells from growing and dividing too rapidly or in an uncontrolled way. The protein made by the PTEN gene is found in almost all tissues in the body. The PTEN protein modifies other proteins and lipids (fats) in cells by removing phosphate groups (clusters of one phosphorous and three oxygen atoms), making the PTEN protein a type of enzyme called a phosphatase. More specifically it is a phosphodiesterase and an inhibitor of the phospho-AKT pathway by removing the 3' phosphate group of phosphatidylinositol (3,4,5)-trisphosphate (PtdIns (3,4,5)P₃).

When the PTEN enzyme is functioning properly, it acts as part of a chemical pathway that signals cells to stop dividing and causes cells to undergo programmed cell death (apoptosis) when necessary. These functions prevent uncontrolled cell growth that can lead to the formation of tumors. There is also evidence that the protein made by the PTEN gene may play a role in cell movement (migration) and sticking (adhesion) of cells to surrounding tissues. PTEN is one of the most commonly lost tumour suppressors in human cancer, and its deregulation is also implicated in several other diseases.

The PTEN gene is located on the long (q) arm of chromosome 10 at position 23.3, from base pair 89,613,174 to base pair 89,716,381.

[edit] Related conditions

Cowden syndrome: Researchers have found more than 70 mutations in the PTEN gene in people with Cowden syndrome. These mutations can be changes in a small number of base pairs (the building blocks of DNA) or, in some cases, deletions of a large number of base pairs. Most of these mutations cause the PTEN gene to make a protein that does not function properly or does not work at all. The defective protein is unable to stop cell division or signal abnormal cells to die, which can lead to tumor growth, particularly in the breast, thyroid or uterus.

Other disorders: Mutations in the PTEN gene cause several other disorders that, like Cowden syndrome, are characterized by the development of noncancerous tumors called hamartomas. These disorders include Bannayan-Riley-Ruvalcaba syndrome, Proteus syndrome, and Proteus-like syndrome. Together, the disorders caused by PTEN mutations are called PTEN hamartoma tumor syndromes, or PHTS. Mutations responsible for these syndromes cause the resulting protein to be nonfunctional or absent. The defective protein allows the cell to divide in an uncontrolled way and prevents damaged cells from dying, which can lead to the growth of tumors.

Noninherited (somatic) mutations in the PTEN gene may play a role in the development of several types of cancer in people who do not have a PTEN hamartoma tumor syndrome. For example, research suggests that changes in the PTEN gene are involved in the early stages of endometrial (uterine) cancer.

[edit] References

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Leslie NR, Downes CP (2004). "PTEN function: how normal cells control it and tumour cells lose it". Biochem J 382 (Pt 1): 1-11. PMID 15193142.
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Waite KA, Eng C (2002). "Protean PTEN: form and function". Am J Hum Genet 70 (4): 829-44. PMID 11875759.
Zhou XP, Waite KA, Pilarski R, Hampel H, Fernandez MJ, Bos C, Dasouki M, Feldman GL, Greenberg LA, Ivanovich J, Matloff E, Patterson A, Pierpont ME, Russo D, Nassif NT, Eng C (2003). "Germline PTEN promoter mutations and deletions in Cowden/Bannayan-Riley-Ruvalcaba syndrome result in aberrant PTEN protein and dysregulation of the phosphoinositol-3-kinase/Akt pathway". Am J Hum Genet 73 (2): 404-11. PMID 12844284.