Some human cancers such as cervical cancer may be considered to be 'catchable', as they are initiated by viruses transmitted between people – in the case of cervical cancer, by certain types of papilloma virus. What is unusual about CTVT in dogs, however, is that no virus is involved – the cancer itself is effectively passed on.
In a paper published in the journal Cell, veterinarian researcher Dr Claudio Murgia conducted forensic DNA tests on tumour tissues from 16 dogs affected by CTVT. The dogs were being treated for the cancer by vets in Italy, India and Kenya who provided the biopsies. He found that in all cases, the tumours were genetically different from the affected dog – in other words, the cancer had come from a different dog. A further analysis of 40 tumours archived in vet labs in five continents showed that the tumours were genetically almost identical and demonstrated that CTVT originally came from a single source and has since spread across the globe.
To trace this source, the UCL team worked with geneticists and computer experts in Chicago and compared the DNA in the tumours to that in specific dog breeds. They found that the cancer most likely first arose in either a wolf or an 'old' Asian dog breed such as a Husky or Shih Tzu. The number of mutations accumulated in the DNA also enabled the researchers to obtain a rough estimate the age of the disease, which came out at around 1,000 years and not less than 250 years old.
CTVT is a serious but seldom fatal disease. Unless the dogs are already in poor condition, the tumours usually regress three to nine months after their appearance, leaving the dogs immune to re-infection. But that leaves enough time for the dogs and bitches to pass the tumour on through further sexual encounters. The tumour is rarely seen in pedigree dogs because they are not allowed casual sex, but it is relatively common in strays. It does not occur in the UK, because quarantine regulations (for rabies) effectively screened it out.
Professor Robin Weiss of the UCL Division of Infection and Immunity, who led the research team, says: "It appears that man's best friend can be its own worst enemy. Our study shows that CTVT has become a parasite that has long outlived its original host.
"Our discovery is of much broader significance than simply a disease in dogs. Firstly, CTVT represents the longest-lived cancer 'clone' known to science. It contradicts the current view that cancer cells generate more and more mutations and inevitably become more aggressive if untreated.
"Secondly, recent research in Australia has revealed the existence of a newly emerged tumour in Tasmanian Devils that also appears to be caused by transmissible cancer cells, in this case by biting. Devils are an endangered marsupial species and there are fears that the new tumour might finally kill them off altogether. The methods used at UCL for dogs could help to determine whether the Devil tumour is also a 'parasitic' cancer.
"Thirdly, our findings also show that cancer cells can evade immune responses and CTVT is particularly smart in this regard. On rare occasions cancer cells have been transmitted from one human to another by hiding in organ transplants. Because the recipient is treated with immunosuppressants in order to prevent rejection, the transferred cancer cells can then grow into tumours just like CTVT. That is why people who have suffered from cancer should not become organ donors."
Jenny Gimpel | EurekAlert!
'Y' a protein unicorn might matter in glaucoma
23.10.2017 | Georgia Institute of Technology
Microfluidics probe 'cholesterol' of the oil industry
23.10.2017 | Rice University
Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
23.10.2017 | Event News
17.10.2017 | Event News
10.10.2017 | Event News
23.10.2017 | Life Sciences
23.10.2017 | Physics and Astronomy
23.10.2017 | Health and Medicine