WHAT ARE ONCOGENES?
Alterations in proto-oncogenes give rise to oncogenes. Any genetic change to DNA leads to a less functional or non-functional protein, which can devastate a cell. Mutations to proto-oncogenes can lead the cells to permanent activation, triggering uncontrolled cell division, evasion of cell death, or both. These processes can lead to cancer.
Mechanisms of oncogene activation are diverse. A proto-oncogene may become an oncogene in one of the following four ways:
- Point mutation – This process involves the insertion or deletion of nucleotide bases (the rungs of the ladder in the DNA structure) in the DNA sequence of the proto-oncogene. These mutations can be inherited from parent animals or occur in the cell during cell division. Point mutations can lead to uncontrolled cell division, escape from programmed cell death, immune evasion, and accelerated tumor growth. In dogs, researchers link point mutations to canine hemangiosarcoma.
- Gene amplification – This mechanism occurs when there is an increase in the number of copies of a gene on chromosomes. If there is a chromosomal abnormality, amplification can occur. The consequence of increased gene numbers is the overproduction of proteins, resulting in cancer development. Reports show that gene amplification is the cause of some canine lymphomas.
- Chromosomal translocation – This process involves the movement of a gene from its original location on a chromosome to a new site during cell division. If the relocation inappropriately alters the function of a gene, it can make a cell cancerous. Translocations play a particularly significant role in the early developmental stage of cancer. In dogs, chromosomal translocations can lead to chronic myeloid leukemia, Burkitt’s lymphoma, and chronic lymphocytic leukemia.
- Epigenetic Changes – Epigenetics examines how our environment and behavior can cause changes to our genes. Sometimes, epigenetic changes cause an alteration to DNA structure in a way that leads to the formation of oncogenes, which drive a higher growth and survival rate than normal cells, leading to cancer. The onset and progression of different cancer types are associated with several epigenetic changes.
Researchers have demonstrated that point mutations and translocations occur early in tumor progression compared to gene amplification, which frequently occurs in metastatic cancers and other difficult-to-treat tumors. Interestingly, some cancer-related epigenetic changes are reversible, which increases the number of potential treatment options. Furthermore, there is currently an epigenetic resource that examines the canine genome and provides information that helps researchers develop targeted therapies that could act as a new way to treat cancer in dogs. To date, canine cancer can be treated with surgery, radiotherapy, hyperthermia, photodynamic therapy, immunotherapy, and chemotherapy.
Understanding genetic changes in your pet will help you identify the source of your pet’s cancer. It will also allow you to speak confidently to your vet and appreciate potential treatment options.
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Last Updated: October 8, 2022
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The following sources were referenced to write the content on this page:
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