Friday, July 27, 2012

PTEN

There have been many studies conducted related to the PTEN gene. These studies found that this gene plays a crucial role in normal cell functioning. However, mutation or lacking PTEN can lead to serious health conditions in the human body. Stem cell loss, deregulation and some forms of cancer are found to be caused by major changes in the PTEN gene. The PTEN gene belongs to the protein tyrosine phosphatase gene family.

Other Names


PTEN has other names aside from phosphatase and tensin homolog. It is also called PTEN1, PTEN_HUMAN, PTEN-MMAC1 protein, BZS, TEP1, TEP1 phosphatase, MHAM, MMAC1 and mutated in multiple advanced cancers 1.

(Image from: PTEN)

PTEN Functions


Phosphatase and tensin homolog is a protein encoded by the PTEN gene in humans. PTEN mutation can lead to the development of many types of cancer. The PTEN gene provides the instructions for enzyme production in all body tissues. This enzyme is a tumor suppressor. It ensures that cells divide and grow at a normal rate. Additionally, it removes the phosphate groups that consist of one phosphorus and three oxygen atoms. As a result, it modifies lipids and other proteins. In this mechanism of action, the PTEN enzyme is a phosphatase.


The PTEN gene plays a key role in chemical pathways during cell division and destruction. A good functioning gene signals the cells to divide and self-destruct. Moreover, PTEN has also been found to control cell migration or movement, the formation of new blood vessels and cell adhesion to surrounding tissues. Many studies found that PTEN has something to do with stabilizing cell genetic formation. Altogether, these functions effectively stop the uncontrolled cell growth that can otherwise lead to tumor formation.

The Clinical Significance of PTEN


Cancer stems from abnormal cell growth. A functioning PTEN gene can stop this cell mutation. In some types of cancer, the PTEN gene is either lost or dysfunctional. This means cell proliferation is increased, and cell death is reduced. PTEN has often been found to be inactive in cases of prostate cancer, endometrial cancer and glioblastoma. In fact, about 70 percent of men with prostate cancer have at least one missing PTEN gene at the time of diagnosis. Meanwhile, reduced PTEN expression is found in both lung and breast cancer. The PTEN mutation may also cause an inherited predisposition to cancer.

There are also certain non-cancerous conditions found to be caused by PTEN mutations. This includes Cowden syndrome. People with this condition have over 70 mutations in their PTEN gene. These mutations include missing base pairs. This stimulates the PTEN gene to produce proteins that are not functioning properly or not working at all. These dysfunctional proteins will not be able to control cell division and instruct abnormal cells to self-destruct. This condition often leads to tumor growth in the thyroid, breast and uterus.

Non-cancerous tumors like hamartomas are also caused by PTEN gene mutations. These tumors cause disorders like Proteus-like syndrome and Bannayan-Riley-Ruvalcaba syndrome. These disorders are called PTEN hamartoma tumor syndromes.


Recent studies have also shown that PTEN has a key role in the developmental disorder autism. PTEN mutation and abnormal changes were found in 3 out of 18 people with autism. This includes classical autism called Rett Syndrome and other similar conditions. Additionally, PTEN mutation is also evident in people who have an unusually large head circumference. This is known as macrocephaly. However, these findings still need to be verified. It is yet unclear as to how PTEN mutation leads to the development of these disorders.

People with PTEN mutations should be given extra care. They should get genetic counseling and testing for PTEN mutations. This is particularly true for people with Cowden syndrome and other disorders with manifesting PTEN abnormalities. With this, there is a high possibility that they can prevent the development of these disorders.


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