Tumor suppressor genes, or antioncogenes, tell healthy cells:
- When to slow down growth
- When to repair DNA
- When to destroy themselves (a process called
apoptosisthat’s used for abnormal or unneeded cells)
If tumor suppressor genes get turned off due to mutations, cells are at risk of becoming cancerous and growing uncontrollably.
Most cancer cells have more than
Many types of tumor suppressor genes have been discovered, and researchers will very likely discover more of these genes in the future. Read on to learn more about the role tumor suppressor genes play in cancer development and treatment.
Every cell in your body contains long strands of tightly coiled DNA called chromosomes that carry your genetic information. You have 23 pairs of chromosomes in all your cells except for your sex cells. These cells only contain one pair of 23 chromosomes.
Your chromosomes contain approximately
Two main types of gene mutations are known to lead to the development of cancer:
- Tumor suppressor genes. These genes tell your cells when it’s time to slow down replication (copying themselves), repair DNA, or destroy themselves. Cancer can develop if these genes are turned off when they should be on.
- Oncogenes. These genes tell your cells when it’s time to grow. Cancer can develop if these genes are turned on when they should be turned off.
There are currently 73 known tumor suppressor genes
The University of Texas Tumor Suppressor Gene Database lists 73 tumor suppressor genes that may play a role in cancer development. It’s very likely that more genes will be discovered in the future.
Tumor suppressor genes are broadly divided into five categories:
- Genes that control the progression of a specific stage of the cell cycle
- Genes that inhibit the replication of the cell
- Genes that stop the cell cycle in response to DNA damage
- Genes that signal for the self-destruction of the cell
- Genes that repair mistakes in DNA
Tumor suppressor gene mutations have been identified in
Mutations in tumor suppressor genes can lead to tumor genesis, or the uncontrolled growth of cells. You have two copies of most genes in your body, one from each of your parents. Research has found that one copy of most tumor suppressor genes is enough to control cell division (a form of replication). This is called the two-hit hypothesis.
Many tumor suppressor genes have been studied, and it’s likely that many more haven’t been discovered yet. Some of the more well-known genes include:
|Retinoblastoma (RB) genes||Retinoblastoma and osteosarcomas||The |
|Tumor protein P53 (TP53) gene||Bladder cancer, breast cancer, brain cancers, and many others||This is the most commonly mutated gene in cancer cells. Mutations in TP53 are found in more than half of cancers.|
|Phosphatase and tensin homolog (PTEN) gene||Breast cancer, glial tumors, prostate cancer, melanoma, endometrial cancer||According to a |
|Cadherin 1 (CDH1) gene (also known as E-cadherin gene)||Hereditary diffuse gastric cancer||According to the American Society of Clinical Oncology, men with this gene have an estimated 67%–80% chance of developing stomach cancer by age 80, and women have a 56%–83% risk of developing stomach cancer by this age. Women also have a 39%–52% risk of developing lobular breast cancer.|
|Neurofibromin 1 and 2 (NF1 and NF2) genes||Neurofibroma, brain tumors||Neurofibromatosis type 1 (caused by NF1 mutations) affects about |
Gene mutations can be inherited or acquired.
- Inherited gene mutations. Inherited gene mutations are present in the egg or sperm before they come together to create the first cell of your body. Every other cell in your body replicates from this first cell and carries the same mutations.
- Acquired gene mutations. Acquired mutations develop later in your life. They occur in a single cell and are then passed to any other cells that develop from this mutation.
Most tumor suppressor gene mutations are acquired not inherited. But most genes linked to inherited cancers are tumor suppressor genes. Most oncogene mutations are also acquired.
Researchers are continuing to improve their understanding of why some genes mutate. Mutations in the
Chemotherapy has long been a mainstream cancer treatment, but it often causes debilitating side effects due to damage to healthy cells. In recent years, researchers have been exploring how to use targeted therapies to treat cancer.
Targeted therapies use drugs to target cancer cells while leaving healthy cells mostly undamaged. Targeted gene therapy modifies specific genes in cancer cells.
Translating cancer research into new treatments is a long process. However, there’s been steady progress in developing drugs to target the TP53 gene and some other tumor suppressor genes.
Tumor suppressor genes tell healthy cells when to destroy themselves, slow their growth, or repair DNA. Mutations to these genes can cause cells to become cancerous and multiply out of control.
More than 70 types of tumor suppressor genes may play a role in the development of cancer. Researchers are examining ways to target tumor suppressor genes to treat cancer.