Functions
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 the following:
- Repression of genes that are essential for the continuing of the cell cycle. If these genes are not expressed, the cell cycle does not continue, effectively inhibiting cell division.
- Coupling the cell cycle to DNA damage. As long as there is damaged DNA in the cell, it should not divide. If the damage can be repaired, the cell cycle can continue.
- If the damage cannot be repaired, the cell should initiate apoptosis (programmed cell death) to remove the threat it poses for the greater good of the organism.
- Some proteins involved in cell adhesion prevent tumor cells from dispersing, block loss of contact inhibition, and inhibit metastasis. These proteins are known as metastasis suppressors.
- DNA repair proteins are usually classified as tumor suppressors as well, as mutations in their genes increase the risk of cancer, for example mutations in HNPCC, MEN1 and BRCA. Furthermore, increased mutation rate from decreased DNA repair leads to increased inactivation of other tumor suppressors and activation of oncogenes.
Read more about this topic: Tumor Suppressor Genes
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