WHAT ARE TUMOR SUPPRESSOR GENES?
The three main types of TSGs are as follows:
- Genes that inhibit cell growth
- Genes that repair damaged DNA
- Genes that instruct cells to die (programmed cell death)
TSGs are recessive at the cellular level, which means the TSG copy from the mom and the copy from the dad must mutate for a cell to become cancerous. There is approximately a one-in-a-million chance that a single copy of a TSG will mutate in a cell. Even if such an event occurs, the second copy of the TSG can maintain the gene’s tumor-suppressing function. Collectively, the chance of both copies of a TSG developing a loss of function is one in a billion.
Some TSGs associated with cancer include the TP53 gene, the phosphatase and tensin homolog (PTEN) gene, and the BRCA1 and BRCA2 breast cancer genes.
TP53 gene
The tumor-suppressor TP53 gene is the “guardian of the genome”. This gene leads to the development of the p53 protein, which is involved in repairing the damaged DNA. Without DNA repair, the p53 protein initiates programmed cell death and removes the damaged cells. But, if cells have p53 mutations and damaged DNA evades detection, the cells will not self-destruct, resulting in the development of cancer cells that divide uncontrollably, potentially spreading in the body.
Approximately 50% of human cancers arise from damage to the TP53 gene. Similarly, most cancers in dogs are due to mutations of the TP53 gene, and experts have found TP53 mutations in various cat tumors, including mammary cancers.
Phosphatase and Tensin Homolog (PTEN) gene
The PTEN gene instructs the production of the tumor-suppressor PTEN protein, which controls biological processes such as cell death, metabolism, and growth. If PTEN is not functioning correctly, cells will divide and grow uncontrollably. PTEN mutation in dogs can cause mammary and vascular cancers, while the role of the PTEN gene in feline cancers is not known.
BRCA1 and BRCA2 genes
The proteins arising from the BRCA1 and BRCA2 genes repair damaged DNA. Mutations in these genes are associated with mammary tumor development in dogs.
Gaining a greater understanding of the cause of your pet’s cancer allows you to understand the biology behind cancer. Your newfound knowledge also gives you the confidence to discuss your furry friend’s diagnosis and treatment options with your vet.
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Last Updated: November 14, 2022
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The following sources were referenced to write the content on this page:
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