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Tumor suppressor genes, or antioncogenes, tell healthy cells:

  • When to slow down growth
  • When to repair DNA
  • When to destroy themselves (a process called apoptosis that’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 60 mutations. A challenge for researchers is finding which mutations cause certain types of cancer. Mutations in tumor suppressor genes are one of the two main types of mutations that lead to cancerous changes in cells. Mutations to oncogenes, which tell cells when it’s time to grow, are the second main type.

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 20,000 genes that hold instructions for your cells. Certain genes are turned on and off in each cell depending on the cell’s function. A change or damage to a gen is called a gene mutation.

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:

  1. Genes that control the progression of a specific stage of the cell cycle
  2. Genes that inhibit the replication of the cell
  3. Genes that stop the cell cycle in response to DNA damage
  4. Genes that signal for the self-destruction of the cell
  5. Genes that repair mistakes in DNA

Tumor suppressor gene mutations have been identified in many types of cancer, including:

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:

GeneAssociated cancersNotes
Retinoblastoma (RB) genesRetinoblastoma and osteosarcomasThe majority of these cancers have mutations in RB genes.
Tumor protein P53 (TP53) geneBladder cancer, breast cancer, brain cancers, and many othersThis 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) geneBreast cancer, glial tumors, prostate cancer, melanoma, endometrial cancerAccording to a 2020 study, this gene is mutated in 35% of endometrial cancers, 32% of glial tumors, and 17% of prostate cancers.
Cadherin 1 (CDH1) gene (also known as E-cadherin gene)Hereditary diffuse gastric cancerAccording 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) genesNeurofibroma, brain tumorsNeurofibromatosis type 1 (caused by NF1 mutations) affects about 1 in 2,500 to 3,000 people.

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 TP53 gene have been linked to ultraviolet light exposure and tobacco smoke.

Targeted gene therapy is a promising area of cancer research that may allow doctors to deliver more personalized treatment.

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.

Currently, nearly all targeted gene therapies target oncogenes and not tumor suppressor genes. It’s easier for researchers to develop methods to turn off oncogenes than it is for them to turn on tumor suppressor genes.

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.