Tasmanian devils are more susceptible to transmissible cancers
Transmissible cancers are cancers that can spread from one animal to another in the same species. Although rare, these types of cancers can be devastating to species populations, as has been evidenced by two transmissible cancers found among Tasmanian devils.
In some parts of Tasmania, 90 percent of devils have been wiped out by transmissible cancers. Their continued decline puts the entire Tasmanian ecosystem at risk because of the important role the devils play as scavengers.
Researchers from the University of Cambridge set out to understand what risk factors made Tasmanian devils more susceptible to transmissible cancers than other species.
“When the first one was discovered, we thought that transmissible cancers were extremely rare and that Tasmanian devils were just really unlucky to get this cancer,” said Elizabeth Murchison, the study’s senior researcher. “But the emergence of the second one made us wonder whether Tasmanian devils might be particularly at risk for developing this kind of disease.”
The results were published in the journal Cancer Cell and show that the transmissible cancers studied may have occurred in Tasmanian devils for a variety of reasons, including a lack of genetic diversity and instinctive biting behaviors among the animals.
The researchers also identified certain drugs that could help treat and prevent the diseases which could be crucial for the species’ survival.
Tasmanian devils are known for biting each other in the face when they fight, which turned out to be the way the cancers spread. The wound healing processes may actually motivate the cancer cells to divide and form tumors.
The two transmissible cancers are similar in origin but likely developed years apart, according to the study.
The team compared the two cancers using genetic and functional comparison methods in order to see what environmental and human-caused changes might have influenced susceptibility among the Tasmanian devils.
Although the researchers could not find any genomic markers that explain the spread of the cancers, they did find that the cancers have similar mutational processes and respond to the same drugs.
“It really pointed to some kind of problem that the devils have with this kind of cell’s regulation, which probably gives them a greater risk of developing this type of disease,” said Murchison.
Other factors that give the Tasmanian devil an unfair disadvantage include a lack of genetic diversity after humans tried to wipe out the species and changed the landscape when the island was first settled.
“When white people first settled in Tasmania, they’d hear these screams at night. And they thought there must be a devilish creature out there,” said Maximilian Stammnitz, the study’s first author. “Their immune systems may be less poised to detect foreign tumor cell grafts, compared to other species that have more genetic diversity.”
The research has important implications both in better understanding transmissible cancers but also in treating and preventing cancers among Tasmanian devils.
Image Credit: Maximilian Stammnitz