Tumor suppressor genes

Definition

Tumor suppressor genes are segments of DNA that encode proteins which help regulate cell growth, division, and repair. They play a crucial role in maintaining genomic stability by inhibiting uncontrolled cell proliferation, and when these genes are mutated or inactivated, the risk of tumor development increases significantly.

5 Must Know Facts For Your Next Test

1. Common examples of tumor suppressor genes include TP53, BRCA1, and BRCA2, which are linked to various cancers when mutated.
2. The two-hit hypothesis suggests that both alleles of a tumor suppressor gene must be inactivated to lead to cancer development.
3. Tumor suppressor genes can prevent cancer by activating DNA repair pathways, promoting apoptosis, and controlling the cell cycle.
4. Mutations in tumor suppressor genes can be inherited (germline mutations) or acquired (somatic mutations), affecting cancer risk in individuals.
5. The loss of function in tumor suppressor genes is a critical step in the multi-stage process of carcinogenesis, contributing to tumor progression and metastasis.

Review Questions

• How do tumor suppressor genes contribute to the regulation of the cell cycle and prevention of cancer?
  • Tumor suppressor genes contribute to the regulation of the cell cycle by encoding proteins that monitor and control cell growth and division. These proteins help ensure that cells only divide when conditions are appropriate and prevent damaged cells from proliferating. When functioning properly, tumor suppressor genes activate DNA repair mechanisms or trigger apoptosis if damage is irreparable, which ultimately reduces the risk of cancer development.
• Discuss the implications of mutations in tumor suppressor genes on an individual's cancer risk and treatment options.
  • Mutations in tumor suppressor genes significantly increase an individual's risk of developing certain cancers, as these mutations can impair the gene's ability to control cell growth and repair DNA damage. Understanding these mutations allows for targeted therapies and personalized treatment strategies. For instance, individuals with BRCA1 mutations may consider preventive surgeries or specific drug therapies that exploit vulnerabilities associated with their genetic predisposition.
• Evaluate the relationship between tumor suppressor genes and oncogenes in the context of carcinogenesis.
  • The relationship between tumor suppressor genes and oncogenes is critical in understanding carcinogenesis. Tumor suppressor genes act as the brakes on cell division, while oncogenes serve as accelerators. When tumor suppressor genes lose their function due to mutations or deletions, unchecked activation of oncogenes can lead to uncontrolled cell proliferation. This duality highlights the balance required for normal cellular function and how its disruption through genetic alterations can culminate in cancer.

Related terms

Oncogenes: Oncogenes are mutated forms of normal genes (proto-oncogenes) that promote uncontrolled cell growth and division, often leading to cancer.

Apoptosis: Apoptosis is the process of programmed cell death that removes damaged or unwanted cells, a function often regulated by tumor suppressor genes.

DNA Repair Genes: DNA repair genes are responsible for fixing DNA damage and maintaining genomic integrity, working alongside tumor suppressor genes to prevent cancer.