tumor suppressor gene
A gene whose normal function prevents uncontrolled cell growth and whose inactivation contributes to cancer development.
Full Definition
Tumor suppressor genes encode proteins that regulate cell division, promote DNA repair, or trigger apoptosis in damaged cells. Unlike oncogenes, these genes prevent cancer when functioning normally. The classic model requires both copies to be inactivated (Knudson's two-hit hypothesis) for cancer to develop, though some show haploinsufficiency. Key tumor suppressors include TP53 (guardian of the genome), RB1 (cell cycle control), and BRCA1/2 (DNA repair). Loss of tumor suppressor function through mutation, deletion, or epigenetic silencing is a hallmark of cancer.
Usage
Usage note: Contrast clearly with oncogenes, which promote cancer when activated or overexpressed.
In Context
- "TP53, the most frequently mutated tumor suppressor gene, was altered in 54% of cases." — Cancer genomics study
- "Loss of tumor suppressor gene function often requires biallelic inactivation." — Molecular pathology textbook