Hard-bitten. When Tasmanian devils bite each other, they can spread a deadly cancer.
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Tasmanian devils can be fierce, but they are no match for a contagious cancer that decimated their population. Scientists have identified the cell type that gave rise to these tumors -. A discovery that can stimulate the development of a test or vaccine for the deadly disease
The stocky Tasmanian devil in black and white is an Australian carnivore related to kangaroos and koalas. In the mid 190s, researchers began to notice that animals die of what became known as the disease of the facial tumor devil (DFTD), a cancer that produces unsightly growths on the head and kills within months. According to some forecasts, DFTD could wipe out wild Tasmanian devils within 40 years.
DFTD is unusual because it is spread from animal to animal, but not by a virus, as some human cancers. Instead, the demons seem to spread the cancer cells themselves, mainly through bite. Rogue cells then settle into their new host and develop into tumors. But the type of cell that spawned the cancer has been a mystery.
To delve into the genealogy of cancer, molecular biologist Elizabeth Murchison of the Sanger Institute Wellcome Trust in the UK and colleagues used a called deep sequencing technique. Their approach was to analyze microRNAs - small strands of RNA that help control the activity of genes - from healthy tissue and tumors DftD. Each type of tissue in the body usually shows a characteristic pattern of miRNA production, and the team found that tumors of the devil clustered with samples from the nervous system.
The researchers also reduces the origins of DftD by determining which genes were turned on in cells of normal and cancerous devil. In their activity profile gene, tumors were most similar to the Schwann cells that isolate the nerves outside of the brain and the spinal cord by secreting an oily substance called myelin. For example, tumors periaxin make the distinctiveness of Schwann cell protein, which is part of the biochemical pathway of the myelin-how. The researchers reported in the last week the number of Science that DFTD probably first started when a Schwann cell or one of its less specialized precursor cells become cancerous.
Tasmanian devils are subject to a variety of tumors, and the results could lead to methods to quickly distinguish animals with DFTD, said Murchison. "We found specific genes that allow us to distinguish between what transmissible cancer and other types of cancer in the demons." She and colleagues suggest a diagnostic test that screens for periaxin. Another possible advantage is a vaccine that stimulates the immune system to eliminate the devil DftD cells -. Something, it seems to be
"It is a beautiful piece of work," says oncologist viral Robin Weiss of University College London. By revealing which genes are active in tumors, the study could also provide clues to how cancer cells survive and why they can jump from animal to animal, said Hamish McCallum disease ecologist at the School of Environment Griffith Australia. at the same time, says McCallum, results raise a question: "This is clearly something that cancer can play, so why is it so rare?"
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