Home » Pet Health » Genes and Cancer » What are Oncogenes?


Proto-oncogenes are genes that provide instructions to produce proteins responsible for normal cell division and programmed cell death. There are at least 30 different proto-oncogenes in cats, approximately 61 in dogs, and 40 in humans.

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:

    1. 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.
    1. 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.
    1. 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.
    1. 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.

The Pet Cancer Foundation’s Website Editorial team is comprised of veterinarians, veterinary oncologists, and veterinary technicians, as well as scientific writers and editors who have attained their PhD’s in the life sciences, along with general editors and research assistants. All content found in this section goes through an extensive process with multiple review stages, to ensure this extended resource provides pet families with the most up-to-date information publicly available.

The team listing of those contributing to the information on this page is here:

Keep Your Pets Healthy Editorial Team

Last Updated: October 8, 2022

The Pet Cancer Foundation’s medical resource for pet owners is protected by copyright.

For reprint requests, please see our Content Usage Policy.

The Pet Cancer Foundation’s Medical Illustration team is comprised of medical illustration specialists and graphic designers that work in consultation with our team of experts to create the medical art found throughout our website. Though not all medical concepts require the assistance of imagery, when a page does contain a medical illustration, credit to the artist and our medical art director will be noted here.

The Pet Cancer Foundation’s medical imagery is protected by copyright and cannot be used without prior approval that includes a mutually signed licensing agreement. Please review our Content Usage Policy.

The following sources were referenced to write the content on this page:

Botezatu, A, Iancu, IV, Popa, O, Plesa, A, Manda, D, Huica, I, Vladoiu, S, Anton, G & Badiu, C 2015, Mechanisms of oncogene activation, DOI: 10.5772/61249.

Breen, M & Modiano, JF 2008, ‘Evolutionarily conserved cytogenetic changes in hematological malignancies of dogs and humans–man and his best friend share more than companionship’, Chromosome Res, vol. 16, no. 1, pp. 145–154.

Brown, R, Curry, E, Magnani, L, Wilhelm-Benartzi, CS, & Borley, J 2014, ‘Poised epigenetic states and acquired drug resistance in cancer’, Nat Rev Cancer, vol. 14, no. 11, pp. 747–753

Chial, H 2008, ‘Proto-oncogenes to oncogenes to cancer’, Nature Education, vol. 1, no. 1, p. 33.

Das, S, Idate, R, Cronise, KE, Gustafson, DL & Duval, DL 2019, ‘Identifying candidate druggable targets in canine cancer cell lines using whole-exome sequencing’, Mol Cancer Ther, vol. 18, no. 8, pp. 1460-1471.

Davenport, MP, Ward, RL & Hawkins, NJ 2002, ‘The null oncogene hypothesis and protection from cancer’, J Med Genet, vol. 39, no. 1, pp. 12-14.

Shortt, J & Johnstone, RW 2012, ‘Oncogenes in cell survival and cell death’, Cold Spring Harb Perspect Biol, vol. 4, no. 12, p. a009829.

Kim, JH, Megquier, K, Thomas, R, Sarver, AL, Song, JM, Kim, YT, Cheng, N, Schulte, AJ, Linden, MA, Murugan, P, Oseth, L, Forster, CL, Elvers, I, Swofford, R, Turner-Maier, J, Karlsson, EK, Breen, M, Lindblad-Toh, K, & Modiano, JF 2021, ‘Genomically complex human angiosarcoma and canine hemangiosarcoma establish convergent angiogenic transcriptional programs driven by novel gene fusions’, Mol Cancer Res, vol. 19, no. 5, pp. 847–861.

Megquier, K, Turner-Maier, J, Swofford, R, Kim, JH, Sarver, AL, Wang, C, Sakthikumar, S, Johnson, J, Koltookian, M, Lewellen, M, Scott, MC, Schulte, AJ, Borst L, Tonomura, N, Alfoldi, J, Painter, C, Thomas, R, Karlsson, EK, Breen, M, Modiano, JF, Elvers, I, & Lindblad-Toh, K 2019, ‘Comparative genomics reveals shared mutational landscape in canine hemangiosarcoma and human angiosarcoma’, Mol Cancer Res, vol. 17, no. 12, pp. 2410–2421.

Morrison, WB 2002, Cancer in dogs and cats: medical and surgical management, Teton NewMedia, Jackson, WY.

Nagaraja, SS & Nagarajan, D 2021, Epigenetics and metabolomics, 1 edn, Associated Press, New York.

Pophali, PA, Marinelli, LM, Ketterling, RP, Meyer, RG, McPhail, ED, Kurtin, PJ, Mwangi, R, Maurer, MJ, Habermann, T & King, RL 2020, ‘High level MYC amplification in B-cell lymphomas: is it a marker of aggressive disease?’, Blood Cancer J, vol. 10, no. 1, pp. 5–13.

Thomas, R, Seiser, EL, Motsinger-Reif, A, Borst, L, Valli, VE, Kelley, K, Suter, SE, Argyle, D, Burgess, K, Bell, J, Lindblad-Toh, K, Modiano, JF & Breen, M 2011, ‘Refining tumor-associated aneuploidy through genomic recoding of recurrent DNA copy number aberrations in 150 canine non-Hodgkin lymphomas’, Leuk Lymphoma, vol. 52, no. 7, pp. 1321–1335.

Willis, RE 2012, ‘Human gene control by vital oncogenes: revisiting a theoretical model and its implications for targeted cancer therapy’, Int J Mol Sci, vol. 13, no. 1, pp. 316-335.

Zhao, JM, Gilad, AA, McMahon, MT, Bulte, JWM & van Zijl, PCM 2008, Molecular Imaging in Oncology, CRC Press, Florida.

Barkbase!, last updated 2018, viewed Oct. 8, 2022, http://www.BarkBase.org

The Pet Cancer Foundation’s medical resource for pet owners is protected by copyright.

For reprint requests, please see our Content Usage Policy.