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Similar to a contagious disease Animals can transmit cancer
Cancer is not one of the infectious diseases, so there is usually no risk of infection for humans. In contrast, it looks different in animals, because it has been known for some time that e.g. In dogs an infectious form of cancer exists. Now scientists from the Columbia University Medical Center (CUMC) have discovered that mussels can also transmit the disease to other specimens. In view of the new results, the question arises, from an expert's point of view, what this could mean for the contagion of cancer in humans.
Cancer in humans is usually non-communicable
Even animals can get cancer. While the disease is not transmissible in humans, there is an infectious form in dogs, for example, which is the so-called "sticker sarcoma" which is rare in Europe. This is transmitted by mucosal contact mainly during sexual intercourse, as can dogs infected by mutual licking and touching the genitals with the tumor cells.
Certain clams can apparently transmit cancer in other ways. This has now been found by US scientists in a new study. (Image: tetxu / fotolia.com) Researchers are studying different mussel species
Now US researchers have discovered another species that appears to be able to infect other species of their species with cancer. The scientists from Columbia University in New York report in the journal "Nature" that these are shells that can pass on a leukemia-like disease.
Michael Metzger and his colleagues focused their investigation on three types of shellfish that they had collected in different regions of Spain and Canada: a mussel species (Mytilus trossulus), the common cockle (Cerastoderma edule) and the golden carpet mussel (Polititapes aureus ). They examined which animals had cancer and then analyzed the genome of the cancer cells as well as that from the healthy tissue. Whether an animal is affected or not can be recognized by an excess of large, altered cells in the circulation. The blood and lymph body fluid of the animals ("hemolymph") appears thickened and cloudy in the case of a disease and the tissue is gradually proliferated by cancer cells.
Results indicate transferability
It turned out that certain genetic characteristics were different in the altered tissue than in the tissue of the healthy animals. In the tumors of different mussel species, however, the scientists discovered a coincidence of the characteristics. This could therefore indicate that the cancer cells were transferred between individual animals, the researchers said.
In addition, they found out that the Golden Carpet Shell infectious cancer cells from the spotted carpet shell (Venerupis corrugata) - a related, yet distinct species in which in the wild, no cancer has yet been detected. According to the experts, the spotted carpet shell may have managed to find a way to fight cancer in the course of evolution, which then transmits it in a different way.
Transmission between different species was previously considered an exception
"Now that we've seen the spread of cancer among several marine species, our future research will focus on the mutations responsible for these cancerous cell transplants," said lead author of the study, Dr. Ing. Stephen Goff, according to a CUMC release. So far, it has been assumed that a tumor is usually limited to one species and that transmission between different species is an exception.
The results of the new study now reveal a total of eight infectious tumor types in animals. In addition to five forms in four types of shells, in recent years science has already been able to detect two transmissible forms of cancer in mammals. It is a facial tumor that threatens to eradicate the marsupial "Tasmanian devil" (Sarcophilus harrisii) and the described "sticker sarcoma", which is found in dogs worldwide.
Cancer does not respect borders
"We thought these things are happening now and in nature and that it's a coincidence. But now the findings that these appear to be fairly common among bivalve mollusks change the perspective, "said molecular biologist Elizabeth Murchison of the University of Cambridge (UK), commenting on the article in" Nature "..
The finding that cancer could possibly jump back and forth between different species was "shocking" to the expert and led to the question of what that could mean for humans. So far, a transmission from person to person has become known only in rare cases, for example, after an organ transplant - cases, each of which concerned only the two persons involved. However, cancer risk "is inherent in multicellular organisms, and the basic evolutionary drive of this disease does not respect individual boundaries, nor even species boundaries," Murchison continued. (No)