Clues to Tasmanian devil cancer
2009-12-31 22:19
London - An international team of scientists has discovered the genetic marker for a deadly cancer ravaging Australia's Tasmanian devil population, and they say their findings pave the way for developing treatments.
Researchers analysed tumour cells taken from facial cancers in the animals, the world's largest marsupial carnivores, and found the disease probably starts in Schwann cells - a type of tissue that cushions and protects nerve fibres.
"Our findings represent a big step forward in the race to save the devils from extinction," Elizabeth Murchison, who works with the US Cold Spring Harbour Laboratory and the Australian National University, wrote in the study.
Protection level for devils raised
Tasmanian devils - popularised by Looney Tunes' fierce cartoon character "Taz" - are the size of a small dog. Deadly facial tumour disease (DFTD) has ravaged the wild population, confined to the island state of Tasmania, since the 1990s.
Australia raised protection levels for devils in May and listed them as endangered due to DFTD.
DFTD is a unique type of cancer, transmitted from animal to animal via biting or other physical contact, which transfers living cancer cells between individuals.
Only two cancers are known to spread in this way - the other is found in dogs. The devils' tumours are mostly found on the face and mouth, but often spread to internal organs.
Writing in the journal Science, the researchers said that, with no diagnostic tests, treatments or vaccines currently available, the disease could wipe out the entire species in 25 to 35 years.
The team's genetic analysis confirmed that tumours spread from animal to animal are genetically identical because they originate from a single line of cells.
Genetic readout
Using advanced sequencing technology, the team identified the originating cell by comparing the "transcriptome" - the complete set of genes that are turned on in tumour cells - with a genetic readout of other tissues.
The scientists found the tumours' genetic signature best matched that of Schwann cells, but said they were still unclear about how these nervous system cells spawned cancer.
Identifying the genetic marker could help accurately diagnose the disease and help to develop treatments, they said.
"Now that we've taken a good look at the tumours' genetic profile, we can start hunting for genes and pathways involved in tumour formation," said Greg Hannon, who worked on the study.
The study will also help scientists distinguish between DFTD and other types of devil cancers, helping them to identify and isolate affected animals and contain the disease's spread.