Today, I would like to take on the disease that is on everyone’s mind, whether or not they are directly a victim of it: cancer. Research in cancer has now shed some insightful light on its pathogenesis, linking humans and dogs in an interesting way. Now more than just man’s best friend, dogs have been shown to share a genetic link sharing certain forms of cancer with humans.
The research is currently taking place at the University of Minnesota under Dr. Jaime Modiano and North Carolina State University under Dr. Matthew Breen. Their collaboration has already resulted in their work being published in the journal Chromosome Research.
Forms of human cancer are currently associated with alterations in the number and structure of genes. At the most elementary level, genomes can be subdivided into chromosomes, which are akin to ordered filing cabinets. Genes would then be the bookmarks that separate these. Breen and Modiano’s research has successfully shown that cancer in dogs also undergoes the same genome alterations and organization.
The similarity in dog and human genomes is much more apparent from a chromosomal perspective. We have 46 chromosomes, whereas dogs have 78. During duplication, chromosomes are rearranged and relocated in a process called translocation. As in a mutation, this can cause a cell to become abnormal, and consequently cause cancer.
The researchers found that the genetic shuffling in cancers of the blood and bone marrow in dogs, such as chronic lymphocytic leukemia (CLL), chronic myelogenous leukemia (CML) and Burkitt’s lymphoma (BL) share the exact abnormalities as that in humans. Breen and Modiano’s research has shown that the same translocation occurs in both dogs and humans for these three cancer forms.
Their research is innovative in that it bridges the gap between molecular and evolutionary biology. Modiano was quoted as saying, “We believe the implication of this finding is that cancer may be the consequence of generations of genetic evolution that has occurred similarly in dogs and humans. This means that to some degree, cancer may be inevitable in some humans and dogs just because of the way our genomes have developed since the separation from a common ancestor.”
Dogs, which develop cancer spontaneously, also happen to be great research subjects. Today’s modern breeds have selective breeding, which restricts and preserves their gene pool to a few genes. Compare this to Ashkenazi Jews, whose restricted gene pool makes them much more susceptible to disorders like Cystic Fibrosis (CF). The same holds true for the modern breed of dogs.
The pathogenetic link between the two species is important because it is a lot easier to identify cancer-related genes in dogs, whose genome is less grandiose than ours. Once identified, the genes can be easily tracked in humans and a much deeper understanding of cancer can be retrieved. If refined, this has the ability to make cancer prognosis much quicker and more efficient.
The researchers are now working on isolating the risk factors of several forms of cancers in dogs, with the ultimate goal of applying that to their human counterparts. But their work is much more than that. If molecular and evolutionary biology can come together in such a uniquely revealing way, then we can unlock a lot more than cancer.