Oncologists at the University of Minnesota and North Carolina State University have found one more association between dogs and
humans other than friendship and companionship 葉he same basis for certain type
They said that the similarities and genetic links
between canine and human cancers may provide crucial insights to help fight the
The team of researchers, led by Jaime Modiano, V.M.D.,
Ph.D., University of Minnesota College of Veterinary Medicine and Cancer
Center, and Matthew Breen, Ph.D., North Carolina State University's Center for
Comparative Medicine and Translational Research, also said that getting cancer
may be inevitable for some humans and dogs, because of the way the genomes have
It is known that genomes have been divided into
chromosomes that play the role of nature's biological filing cabinets with
genes located in specific places.
"Many forms of human cancer are associated with
specific alterations to the number or structure of chromosomes and the genes
they contain. We have developed reagents to show that the same applies to dog
cancers, and that the specific genome reorganization which occurs in comparable
human and canine cancers shares a common basis," said Breen.
The researchers specifically discovered that the
genetic changes occurring in dogs diagnosed with certain cancers of the blood
and bone marrow, including chronic myelogenous leukemia (CML), Burkitt's
lymphoma (BL), and chronic lymphocytic leukemia (CLL), are almost the same as
the genetic abnormalities in humans diagnosed with the same cancers.
"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," said Modiano.
He added: "Since we know now that dogs and humans seem
to share a common pathogenetic basis for some cancers, we believe that studying
dog cancers may allow us to identify cancer-associated genes more easily in dog
populations than in human populations. Once identified, we may be able to
translate these findings to human cancers as we seek to provide a greater level
of insight into cancer risk, diagnosis, and prognosis."
Researchers believe that the dogs are good research
subjects because they develop the disease spontaneously, and a number of the
contemporary breeds have developed over the past few hundred years using
restricted gene pools. And this selective breeding has conserved the genetics of
a breed. It has also resulted in making some breeds more susceptible to certain
Researchers found an opportunity to compare the
genomes and study the evolutionary genetic changes associated with cancer, due
to all these factors along with the large number of similarities between the
genomes of dogs and humans.
While the human genome has 46 chromosomes, the dog
genome contains 78 chromosomes and quiet a few times, chromosomes can become
rearranged or relocated in the normal duplication process of cells. This
rearrangement or relocation is known as translocation and it can cause a cell
to lose its normal function, becoming abnormal, and possibly developing into
"Interestingly, we found that the same translocation
of chromosomes happens in dogs as in humans for the three blood and bone marrow
cancers we studied," said Modiano.
Concluding, the researchers said that despite millions
of years of divergence, the evolving genomes of dogs and humans seem to have
retained the mechanism associated with cancer, and also these retained changes
in the genomes have similar effects in both dogs and humans.
"Like ourselves, our pet dogs suffer from a wide range
of spontaneous cancers. For thousands of years humans and dogs have shared a
unique bond. In the 21st century this relationship is now strengthened to one
with a solid biomedical basis; the genome of the dog may hold the keys to
unlocking some of nature's most intriguing puzzles about cancer," said Breen.
The findings of this
study are published in the current issue of the journal Chromosome Research, a
special edition on comparative cytogenetics and genomics research by scientists
from around the world.