Cancer Jumps Between Sea Creatures in Polluted Waters

Jim Crocker
28th February, 2024

Cancer Jumps Between Sea Creatures in Polluted Waters

Blue Mussel (Mytilus edulis), one of the two species studied.

Photo adapted from: Jonathan Layman / CC BY (Source)
Cancer isn’t always limited to an individual. In rare cases, cancer cells can be transmitted between individuals, acting as a parasite. This phenomenon, known as transmissible cancer, has been observed in a few species, including dogs[2][3], Tasmanian devils[4], and now, increasingly, in marine bivalves – specifically mussels. Understanding how these cancers spread is crucial for mitigating their impact on vulnerable populations and ecosystems. Researchers at Univ Montpellier recently investigated the spread of Mytilus trossulus Bivalve Transmissible Neoplasia 2 (MtrBTN2), a cancer affecting several mussel species globally[1]. The study focused on a hybrid zone where two mussel species, Mytilus edulis and Mytilus galloprovincialis, coexist along the French Atlantic coast. The goal was to determine where the cancer is most prevalent and identify factors contributing to its propagation. The study found that MtrBTN2 affected both mussel species at similar rates in the studied area, likely due to the close proximity of the two species. However, a significant difference emerged when comparing natural mussel beds to those in port environments. Ports exhibited a much higher prevalence of the cancer, with one shuttle landing dock appearing as a potential hotspot. Cancer was rarely found in natural beds, except for two sites located near this hotspot, suggesting the disease was spreading outwards from the port. This finding suggests ports act as key locations for the transmission of MtrBTN2. Several factors within ports may contribute to this. High mussel density provides more opportunities for cell-to-cell transfer. Stressful conditions, such as pollution or fluctuating salinity, could weaken mussel immune systems, making them more susceptible to infection. Sheltered locations and buffered temperatures may also create favorable conditions for cancer cell survival and transmission. Importantly, the researchers propose that ships play a role in spreading the cancer through a process called biofouling. Biofouling refers to the accumulation of organisms, like mussels, on submerged surfaces, including ship hulls. As ships travel between locations, they can carry infected mussels – and therefore the cancerous cells – to new areas, effectively creating artificial pathways for disease propagation. This is similar to how other invasive species are spread globally. The concept of transmissible cancers challenges traditional understandings of cancer biology. Historically, cancer was considered a disease of the individual, arising from mutations within their own cells. However, studies on canine transmissible venereal tumor (CTVT) revealed that, in some cases, the infectious agent is the cancer cell itself[2][3]. Genetic analysis showed that CTVT cells are distinct from the host’s cells and represent a single, ancient clonal lineage that has spread across continents. The remarkable stability of the CTVT genome, despite its aneuploid (abnormal chromosome number) nature, suggests specific adaptations that allow it to survive and propagate as a parasite. The MtrBTN2 study builds on this understanding by demonstrating how environmental factors and human activities can influence the spread of a transmissible cancer in a marine environment. The identification of ports as epidemiological hubs highlights the need for preventative measures, such as controlling biofouling on docks and ship hulls, to limit the further dissemination of this marine pathogen.

HealthEcologyMarine Biology

References

Main Study

1) Marine transmissible cancer navigates urbanized waters, threatening spillover.

Published 28th February, 2024

https://doi.org/10.1098/rspb.2023.2541

Related Studies

2) Clonal origin and evolution of a transmissible cancer.

Journal: Cell, Issue: Vol 126, Issue 3, Aug 2006

3) Origins and evolution of a transmissible cancer.

https://doi.org/10.1111/j.1558-5646.2009.00724.x

4) A second transmissible cancer in Tasmanian devils.

https://doi.org/10.1073/pnas.1519691113


Related Articles

An unhandled error has occurred. Reload 🗙