Knowra Tumor suppressor gene Tumor suppressor gene A gene whose normal activity restrains cell proliferation, preserves genome integrity, or promotes cell death. Cancer can arise when its function is lost or reduced.
Two-hit hypothesis : A model in which both functional copies of a tumor suppressor gene must be inactivated to remove its protective effect. It explains why inherited risk can coexist with a later, acquired mutation in the remaining copy.
Allele : One of two or more alternative versions of a genetic sequence at a particular genomic location. Tumor suppressor genes often have two alleles whose functions can be lost separately.
Li-Fraumeni syndrome : An inherited cancer predisposition syndrome usually caused by a germline pathogenic variant in TP53. It demonstrates how inheriting one altered tumor suppressor allele raises cancer risk across multiple tissues.
Oncogene : A gene whose abnormal activation can drive cancer-promoting growth, survival, or signaling. Oncogenes promote cancer through excessive activity, unlike tumor suppressors, which promote it through lost activity.
Loss of heterozygosity : The loss of one parental allele in a cell, often leaving a formerly heterozygous genomic region with only one allele type. It is a common way a tumor cell eliminates the intact copy of a tumor suppressor gene.
Somatic mutation : A genetic alteration acquired by a non-reproductive cell and passed to its descendants through cell division. Such mutations can disable a tumor suppressor in a developing tumor without being inherited.
Hereditary breast and ovarian cancer syndrome : An inherited cancer predisposition syndrome most commonly associated with pathogenic variants in BRCA1 or BRCA2. It links inherited loss of DNA-repair tumor suppression to elevated breast and ovarian cancer risks.
Gain-of-function mutation : A genetic alteration that increases a gene product’s activity or gives it a new function. Many oncogenic mutations activate growth signals, whereas tumor suppressor mutations usually reduce protective function.
TP53 : A gene encoding p53, a protein that coordinates cellular responses to DNA damage, stress, and abnormal growth signals. Its protein can halt the cell cycle, promote repair, or trigger cell death when damage is severe.
Cell cycle : The ordered sequence of growth, DNA replication, and division through which a cell produces daughter cells. Many tumor suppressor proteins control checkpoints that govern cell-cycle progression.
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