Tasmanian devil populations have suffered a devastating decline due to a contagious facial tumor disease, first observed in 1996. The scope has been such that the number of individuals has fallen by more than 80% between 1996 and 2016 Since then, the scientific community has tried to find a cure for this cancer, with some progress.
The team of Andrew Storfer, evolutionary geneticist and professor of Biology at the Washington State University (USA), has been studying for more than a decade how some populations of these carnivorous marsupials are developing genetic resistance to this communicable cancer.
But it was not until a year ago when the experts found something unusual when capturing and marking some specimens from an isolated region of Tasmania: these animals with facial tumors did not die. In fact, according to the researchers, for several months the tumors disappeared on their own. The study is the first step to characterize the genetic basis of the tumor regression trait.
“It was very rare and we wanted to check the genomic variation that could be causing these demons to improve spontaneously,” stresses Storfer. Thus, the scientists sequenced the genomes of seven Tasmanian demons that experienced tumor regression and three that did not.
The results, now published in the journal Genome Biology and Evolution, reveal that animals whose tumors declined had three highly differentiated genomic regions that contained multiple genes known to be related to the immune response and cancer risk in humans and other mammals. The study is the first step to characterize the genetic basis of the tumor regression trait.
“Some of the genes that we believe have a role in tumor regression in Tasmanian demons are also shared by humans,” says Mark Margres, a researcher at Clemson University and one of the authors of the work. Tumor regression is not a phenomenon unique to Tasmanian devils, although it is extremely rare.
According to the scientist, although the research is at a very early stage, it could eventually contribute to the development of drugs that trigger the regression response of the tumor in demons, humans and other mammals that do not have this genetic variant.
The next step in the investigation will be to analyze the tumor’s genome to see if there are specific mechanisms or mutations that lead to the disappearance of the tumor. Scientists hope that thanks to the better understanding of the genetic basis of tumor regression in Tasmanian demons, the general mechanisms underlying tumor regression in certain human cancers can be identified.