Tumor Suppressor Gene

A tumor suppressor gene is a normal gene that helps protect cells from becoming cancerous by controlling cell growth, repairing damaged DNA, or triggering the death of cells that are too damaged to fix. When both copies of a tumor suppressor gene are lost or disabled, the cell loses an important brake on uncontrolled growth, and cancer becomes more likely. In mesothelioma, several tumor suppressor genes (most notably BAP1, CDKN2A, and NF2) are commonly inactivated.

Origin

The concept emerged from Alfred Knudson's 1971 "two-hit hypothesis," developed while studying retinoblastoma in children. Knudson proposed that cancer can arise when both copies of a protective gene are knocked out, a framework that defined the modern understanding of tumor suppressor genes.

Significance in Asbestos Context

Asbestos fibers damage cells in ways that can disable tumor suppressor genes, and the loss of these genes is a hallmark of mesothelioma tumor biology. Pathologists routinely test mesothelioma biopsies for loss of BAP1 (by immunohistochemistry) and CDKN2A (by FISH) because the absence of these proteins helps distinguish malignant mesothelioma from benign reactive tissue, a critical diagnostic distinction. Patients should know whether these tests were performed on their tissue, because the results often appear in pathology reports and can support both diagnosis and the link to asbestos exposure. Inherited mutations in BAP1 also identify families with elevated mesothelioma risk, which may be relevant to relatives.

Example Sentence

The pathology report noted loss of the BAP1 tumor suppressor gene, which confirmed the mesothelioma diagnosis and prompted her oncologist to recommend genetic counseling for her children.

Related Terms

BAP1, CDKN2A, NF2, Immunohistochemistry, FISH, Two-Hit Hypothesis

Notes

• Ask your pathologist or oncologist whether BAP1 and CDKN2A testing was performed on your biopsy; if not, request it, as these results strengthen the diagnosis and may guide treatment.
• If you have a confirmed BAP1 loss, ask whether the mutation is somatic (only in the tumor) or germline (inherited). Germline BAP1 mutations have implications for blood relatives and warrant genetic counseling.
• Preserve copies of all pathology reports, immunohistochemistry results, and molecular testing reports; these documents are often central evidence in asbestos claims and in qualifying for clinical trials.
• Loss of specific tumor suppressor genes may make you eligible for targeted therapies or clinical trials. Ask your oncologist about trials that select patients by BAP1 or CDKN2A status.