Tumor suppressor gene
Oncology · Genetics · Molecular Biology
Say it: TOO-mur suh-PRES-ur JEEN
A tumor suppressor gene makes a protein that restrains cell division or repairs damage, so losing both working copies can help a cell turn cancerous.
UK spelling: tumour suppressor gene
Also: antioncogene, tumor suppressor
Definition
What is a tumor suppressor gene?
A tumor suppressor gene is a gene whose protein keeps cell growth in check. If oncogenes are the accelerator of cell division, tumor suppressors are the brakes. Their products halt the cell cycle at checkpoints, help repair damaged DNA, or trigger apoptosis, a programmed cell death, when damage is too severe to fix.
Cancer can develop when these brakes fail. Mutations or deletions that destroy the gene's function are loss-of-function changes, and because one working copy is usually enough, both copies normally have to be lost. This is the two-hit idea, proposed by Alfred Knudson from studies of retinoblastoma, an eye cancer of young children. In the inherited form, a child is born with one faulty copy of the RB1 gene in every cell, so a single further hit in a retinal cell is enough; in the sporadic form, both hits happen by chance in the same cell.
The best-known tumor suppressor is p53, which pauses the cell cycle after DNA damage and is faulty in about half of human tumors. Inherited faults in BRCA1 or BRCA2 raise the risk of breast and ovarian cancer.
Word parts
Where does the term “tumor suppressor gene” come from?
- tumor
- a swellingLatin tumor
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Terms that go with it
- OncogeneAn oncogene is a mutated or overactive form of a normal growth-promoting gene that pushes cells to divide uncontrollably and can cause cancer.
- CancerCancer is a group of diseases in which abnormal cells divide without control, invade nearby tissue and can spread to distant parts of the body.
- Cell cycleThe cell cycle is the ordered series of growth, DNA copying and division stages that a cell passes through to produce two daughter cells.
- ApoptosisApoptosis is programmed cell death, a controlled process in which a cell dismantles itself in an orderly way without harming its neighbors.
- MutationA mutation is a lasting change in an organism's DNA sequence, ranging from a single altered base to large rearrangements of chromosomes.
- AlleleAn allele is any of the alternative forms of a gene or DNA sequence that can occupy the same position, or locus, on a chromosome.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- NHGRI Talking Glossary: Tumor Suppressor Gene
- OpenStax Biology 2e, 10.4 Cancer and the Cell Cycle
- MedlinePlus Genetics: RB1 gene
- Cancer Research UK: Genes, DNA and cancer
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