Pinpointing the genes involved in human brain cancer can be like looking for a needle in a haystack, and sometimes the needle you find may not be the right one. By comparing human and canine genomes, researchers at North Carolina State University have discovered that a gene commonly believed to be involved in meningiomas-tumors that affect the meninges, or thin covering, of the human brain and account for one out of four adult brain tumors -may not be as key for tumor formation as previously thought, and they've narrowed the search for the real culprit.
Meningiomas are intracranial tumors, meaning that they do not grow within brain tissue itself, but in the space between the brain and the skull. In humans, they are associated with genetic defects of large segments of chromosomes, which makes isolating the specific genes involved extremely difficult. Humans suffering from meningioma frequently lose one copy of almost the entire length of human chromosome 22. This chromosome is made of almost 50 million base pairs of DNA that code for more than 500 genes.
"The dog has been man's best friend for centuries, and now the genome of the dog could well be man's next best friend," says Dr. Matthew Breen, professor of genomics at NC State.
"With so much genetic material to consider, one can see why figuring out which genes play a key role in meningiomas is extremely difficult," says Breen. "By looking at tumors seen in both humans and dogs we have a simple way to narrow the search: we compare the affected areas of a human chromosome with related areas on dog chromosomes. This works because dogs and humans are genetically similar and both get the same kinds of cancers. While we share much of our genetic material, the DNA of a dog is organized differently to our own and this makes it possible to isolate smaller 'shared' regions of genetic data rather than looking at an entire chromosome."
Breen, NC State colleagues Rachael Thomas and vet
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North Carolina State University