tumor suppressor gene
A gene whose loss of function or inactivation removes normal constraints on cell growth and contributes to cancer development.
Full Definition
A tumor suppressor gene is a normal gene that functions to prevent uncontrolled cell division and maintain genomic stability. When tumor suppressor genes are inactivated through mutations, deletions, or epigenetic silencing, cells lose important regulatory mechanisms that normally prevent malignant transformation. Classic examples include TP53 (the 'guardian of the genome'), RB1, APC, and BRCA1/BRCA2. Unlike oncogenes, tumor suppressor genes typically require loss of both copies (following Knudson's two-hit hypothesis) to contribute to cancer development, though some show haploinsufficiency where loss of a single copy is sufficient.
Usage
Usage note: Emphasize functional loss rather than activation; contrast with oncogene mechanisms.
In Context
- "Biallelic inactivation of the tumor suppressor gene TP53 was observed in the aggressive tumor subtype." — Molecular characterization study
- "The patient's family history suggested a hereditary tumor suppressor gene syndrome." — Genetic counseling note