It seems like a crazy and mystical theory, but scientists are now examining an organism – perhaps the first example of the effect they have proposed under the name “Scandal“.
Scandal (short for ) “Devoted by CANcer Development animals“) means the species that differentiates from the development of cancer. This hypothesis suggests that future cancer cells are not just ordinary mutant cells.
With its aggressive and intense spread, cancer will find an evolutionary way not to be killed when the patient dies. Instead, he will find a way to survive, with a metastatic leap outside the patient’s body.
The cancer can then develop into separate multicellular organisms. From here, it will have the ability to roam between hosts, not just within one species but between different species.
The Scandal Hypothesis was presented by scientist Alexander Panchin and colleagues at the Russian Academy of Sciences in a new paper in the journal Biology Direct.
According to Panchin’s forecast, the Scandal will occur according to a 3-step scenario. In the first step, cancer will start as a disease and progress to become an infectious disease. The goal is not to get killed after the first host dies.
This is what we see with Devil’s Face Tumor (DFTD), which infects Tasmanian devils. These cancer cells can be passed from one individual to another within the same Tasmanian species through their bite.
In addition, a research team led by geneticist Elizabeth Murchison at the University of Cambridge recently discovered genital tumors in dogs (CTVT). This is a form of cancer that can be transmitted sexually.
Murchison said genital cancer tumors in dogs have even been transmitted as far back as 8,500 years. In a 2014 paper, Murchison and his co-authors described CTVT as “the oldest and most widespread cancer in the natural world“.
In the second step, the cancer will metastasize from species to species. Athena Aktipis, a professor at Arizona State University, said: “Although the spread of cancer between different species seems unlikely,”never happened before”.
Activists have studied the evolution of cancer for years. He gave an example of a patient infected with HIV who later became infected with tapeworms who developed cancer. The tumor then spreads from the tapeworm to the patient.
Cases of cancer from worms have been reported repeatedly in people with compromised immune systems. And activists suspect what we know may be just the tip of the iceberg.
According to him, cancer if met with the right conditions can become a form of parasite. Like CTVT and DFTD, for example, they must “is a parasite, a kind of parasitic organism“, said the activist.
The third step in the Panchin and colleagues Scandal hypothesis, which is also the least likely and as yet unproven, is that cancer will evolve into organisms, first unicellular, then multicellular.
“We understand that this is a very unlikely scenario“, Panchin said. That’s because in order to be multicellular organisms, tumors had to evolve to have different cell types. But just because it’s impossible doesn’t mean it can’t happen.
“I think it’s very possible that a group of transmissible cancer cells could evolve“, said the activist.
To find evidence for the existence of multicellular organisms that once evolved from cancerous tumors, Panchin looked to marine parasites called Myxosporeans.
Myxosporeans are mysterious parasites that infect everything from fish to worms. It was once thought to be a protozoan, that is, not a plant, or an animal, or a fungus.
However, in 1995, Mark Siddall, a scientist from the Virginia Institute of Marine Science, and his colleagues argued that Myxosporeans were exotic members of the cnidaria, a group that includes jellyfish and screaming corals. Since then, genetic studies have cemented its place on the evolutionary tree.
But even if Myxosporeans are considered cnidarians, their genomes are small, measuring only 22.5 megabases, one-twentieth the size of closely related cnidarians.
Furthermore, Myxosporeans lost several genes considered essential for multicellular life. So Panchin thinks maybe this is a species that evolved from a single cell form, and there are further indications that the starting point was a cancerous tumor.
First, infectious cancers are not limited to mammals, but are also found in molluscs. It is therefore very likely that Myxosporeans were once tumors in their cnidarian relatives.
Therefore this parasite can completely bypass step 1 and step 2 in the Scandal hypothesis. Now, the only evidence to look for is the traces of the 3rd jump.
To do that, Panchin and his team compared the genomes of five Myxosporeans with those of three protozoa and 29 other simple animals. They found that Myxosporeans did not contain genes that promote apoptosis.
Apoptosis is a natural process in aging cells that kills itself to prevent mutations from developing into cancer. In cancer tumor cells, this apoptotic gene is also missing.
So if Myxosporeans did evolve from a tumor, it would have lost the same apoptotic gene. Of all the simple unicellular and multicellular organisms that Panchin’s team examined, incidentally only Myxosporeans lacked this apoptotic gene.
“Even looking at simple animal parasites, we don’t see the degree of deficiency of cancer-related genes.“, she says.
However, this evidence is insufficient to conclude that Myxosporeans are truly organisms that evolved from cancerous tumors. Due to the lack of apoptotic genes in Myxosporeans and tumors it could only be a coincidence, unless Panchin and his team demonstrated a causal mechanism between them.
Nonetheless, the Aktipis argues that by the coincidence that Panchin discovered, “We should at least consider the possibility that some of the parasitic organisms we see today may have evolved from infectious cancers.”
That means scientists will have to broaden their search to include other simple multicellular organisms, not just Myxosporeans. “This article is the start of this quest”said Activist.
Even if the data eventually show that Myxosporeans were not organisms that evolved from cancerous tumors, Panchin notes that the Scandal hypothesis is still possible in other species.
“We hope that at some point some zoologists investigating another strange animal will say, “Maybe those people are wrong about Myxosporeans, but this creature, obviously, is an advanced stage of cancer.“.
Referring quantama magazine