What happens when a tumor suppressor gene loses its activity?

When a tumor suppressor gene loses its activity, it allows cells to proliferate uncontrollably. Tumor suppressor genes are crucial for regulating cell division, repairing DNA, and maintaining genomic stability. They function like brakes on cell growth and division. When these genes become nonfunctional due to mutations or other mechanisms, the regulatory control they provide is lost. This results in a failure to halt cell division when necessary, leading to unchecked cellular proliferation and the potential development of cancer.

In normal circumstances, tumor suppressor genes, such as p53 and BRCA1, monitor cell cycles and can initiate repair processes or trigger cell death if damage is detected. However, their inactivity removes these critical checks, allowing cells to continue dividing without proper regulation, significantly increasing the risk of tumors forming and growing uncontrollably.