Tumor suppressor genes are genes that normally prevent uncontrolled cell growth and division, thereby protecting the body from cancer. Functions of tumor suppressor genes Regulate the cell cycle Stop cells from dividing when they should not. Example: p53 halts the cell cycle when DNA is damaged. Promote DNA repair Detect and help repair damaged DNA before the cell divides. Induce apoptosis (programmed cell death) Trigger the death of cells with severe DNA damage to prevent cancer development. Maintain genomic stability Prevent accumulation of mutations in the genome. Key point Cancer can develop when both copies of a tumor suppressor gene are inactivated or lost (the "two-hit hypothesis"), removing the normal brakes on cell proliferation. Examples TP53 (p53) – "guardian of the genome" RB1 – regulates the cell cycle BRCA1 and BRCA2 – involved in DNA repair In short: Tumor suppressor genes act as the "brakes" of the cell cycle, preventing abnormal cell growth and cancer formation.
