Tumor suppressor gene

Tumor suppressor gene is a type of gene that protects a cell from one step on the path to cancer. When this gene mutates to cause a loss or reduction in its function, the cell can progress to cancer, usually in combination with other genetic changes. The loss of these genes may be even more critical than proto-oncogene/oncogene activation for the formation of many types of human cancer cells.

Function

Tumor suppressor genes, or more precisely, the proteins for which they code, either have a dampening or repressive effect on the regulation of the cell cycle or promote apoptosis, and sometimes do both. The functions of tumor suppressor proteins fall into several categories including: repression of genes that are essential for the continuing of the cell cycle, coupling the cell cycle to DNA damage, and maintenance of genomic integrity, cell adhesion, and inhibition of angiogenesis.

Types

There are two types of tumor suppressor genes:

• Gatekeeper genes: These genes directly regulate the growth of tumors. When these genes mutate, cells grow and divide too rapidly or in an uncontrolled way.
• Caretaker genes: These genes are involved in repairing damaged DNA. Mutations in these genes can lead to genetic instability and the development of cancer.

Examples

Some of the most commonly known tumor suppressor genes include:

• TP53 (also known as p53): This gene codes for a protein that regulates the cell cycle and functions as a tumor suppressor.
• BRCA1 and BRCA2: These genes are involved in the repair of damaged DNA, and mutations in these genes can lead to breast and ovarian cancer.
• APC: This gene helps control how often a cell divides, how it attaches to other cells within a tissue, or whether a cell moves within or away from a tissue.

See also

• Oncogene
• Proto-oncogene
• Cancer
• Genetic mutation

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