2023-10-05 10:39:57
Contagious cancers were recently discovered thanks to advances in the field of genetics that allow us to determine in which individual a cancer cell originated. Currently only known contagious cancers in dogs, Tasmanian devils and several marine species.
For the first time, the transmissible cockle cancers that can spread through water, uncovering new insights into how these cancers have spread among animal populations for hundreds, possibly thousands, of years.
These cockle tumors have a very unstructured genome
The study, carried out by researchers from the Center for Research in Molecular Medicine and Chronic Diseases, CiMUS, at the University of Santiago de Compostela and collaborators from several countries, found that these cockle tumors are highly genetically unstable.
The work found that these tumors of cockles have a very unstructured genome, allowed them to describe the tissue in which these contagious cancers originated and some mechanisms that contagious cancer cells use to prevent their extinction.
The importance of this study has led the journal Nature Cancer, in which to date only studies in humans or, at most, in model organisms had a place, to publish for the first time a work carried out in an invertebrate species that does not represent a typical model such as the cockle. The research shares pages in this magazine with another work with similar characteristics, but carried out in another species, the north american clam.
They created the first high-quality reference genome of the cockle
The team led by Jose Tubio It also created the first high-quality reference genome of the cockle that will allow future studies on other genetic issues of the species.
Cancers that can survive high levels of chromosomal instability
Cockles belong to one of the oldest groups of animals on Earth, bivalve mollusks, which have inhabited the Earth for more than 500 million years and first appeared about 300 million years before the dinosaurs. These animals can contract transmissible cancers that spread through cells
live cancerous, which pass from one cockle to another through seawater. Cancers cannot be transmitted to humans and only spread among susceptible cockles.
This study focused on the common cockle (For the success of Cerastoderma) and the researchers collected around 7,000 cockles in 36 locations in 11 countries from the entire European coast and North Africa, from Morocco to Russia, in the search for these tumors, finding infected animals in Spain, Portugal, France, England and Ireland. Interestingly, the researchers also identified several cockles that had unexpectedly been coinfected by cells from two types of cancer at the same time.
They identified several cockles that had unexpectedly been coinfected by cells from two types of cancer at the same time
The most unexpected finding was finding that these cockle tumors have a very unstructured genome. Cancer cells within a single tumor contain very different numbers of chromosomessomething that is not seen in other contagious cancers.
Image taken in the research laboratory. / CiMUS
Some cells contained as few as 11 chromosomes and others as many as 354 while the number of chromosomes in healthy cells of a normal cockle is always 38. This is surprising, since human cancer cells cannot survive high levels of chromosomal instability, although Moderate levels often make tumors more likely to spread to other organs and become resistant to treatment.
Researchers will continue studying the genomics of these cancers to understand how contagious cockle cancer cells survive the effects of genomic instability to understand this in all forms of cancer, including human. They also observed a mutational signature described in human brain and myeloid tumors.
Very old tumors
Genetic analysis of tumor evolution also allowed researchers to find Strategies that cancer uses to avoid its extinctionFor example, evidence that cancer cells have stolen mitochondria (the small organelles that generate the cell’s energy) from their host cockles at least seven times in the past.
The two contagious cockle cancers are leukemias, that is, they originated in the hemolymph tissue
As for the origin, the researchers found that the two contagious cockle cancers are leukemias, that is, they originated in the hemolymph tissue (the “blood” of cockles). This suggests that cancer takes advantage of the opportunity offered by hemolymph to spread throughout the body.
Although it is difficult to accurately estimate the age of cancers of cockle, the findings of this study suggest that these cancers probably emerged centuries or even millennia ago.
In conclusion, it is believed that these contagious cancers originated in the hemolymphhave spread slowly through European cockle populations, accumulating diverse mutations and occasionally capturing mitochondria from host cells as replacements for their own when damaged.
These results have been generated within the framework of the European project Scuba Cancers which was funded by the European Research Council (ERC) with 1.5 million euros to investigate the genetic causes that cause a cancer cell to spread from one individual to another.
Reference:
A.L. Bruzos, M. Santamarina, D. Garcia-Souto, et al. “Somatic evolution of marine transmissible leukaemias in the common cockle, Cerastoderma edule”. Nature Cancer. DOI: 10.1038/s43018-023-00641-9
Fuente:
University of Santiago de Compostela
Rights: Creative Commons.
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