A single clonal lineage of transmissible cancer identified in two marine mussel species in South America and Europe.

Marisa A Yonemitsu,Rachael M Giersch,Nuria Vázquez,Annette F Muttray,Maryline Houssin,Carol Reinisch,Nicolas Bierne,Fernando T Avilés,Michael J Metzger,James Sherry,Gloria Arriagada,Florencia Cremonte,Stephen P Goff,Alexis Simon,Maria Polo-Prieto,Erika Av Burioli,Susan A Baldwin,Nicolás Merino-Véliz,Maurine Hammel

doi:10.7554/elife.47788

Abstract

Transmissible cancers, in which cancer cells themselves act as an infectious agent, have been identified in Tasmanian devils, dogs, and four bivalves. We investigated a disseminated neoplasia affecting geographically distant populations of two species of mussels (Mytilus chilensis in South America and M. edulis in Europe). Sequencing alleles from four loci (two nuclear and two mitochondrial) provided evidence of transmissible cancer in both species. Phylogenetic analysis of cancer-associated alleles and analysis of diagnostic SNPs showed that cancers in both species likely arose in a third species of mussel (M. trossulus), but these cancer cells are independent from the previously identified transmissible cancer in M. trossulus from Canada. Unexpectedly, cancers from M. chilensis and M. edulis are nearly identical, showing that the same cancer lineage affects both. Thus, a single transmissible cancer lineage has crossed into two new host species and has been transferred across the Atlantic and Pacific Oceans and between the Northern and Southern hemispheres.

Highlights

Cancers normally arise from mutations in an organism’s own cells, and they either regress or continue to grow until they kill the host organism
We investigated disseminated neoplasia found in M. chilensis from Argentina and Chile, as well as M. edulis from France and the Netherlands, to determine if these cancers are transmissible cancers or conventional cancers and, if transmissible, whether these cancers represent new cases of the same lineage of transmissible cancer previously reported in Canada or whether they are novel cancer lineages
Disseminated neoplasia has been previously shown to be due to a transmissible cancer lineage in four bivalve species, including Mytilus trossulus (Metzger et al, 2016; Metzger et al, 2015), and the current study greatly extends both our understanding of cross-species transmission of cancer and our understanding of the potential for geographic spread of transmissible cancers (Figure 7)

Summary

Introduction

Cancers normally arise from mutations in an organism’s own cells, and they either regress or continue to grow until they kill the host organism. Cancer Biology Microbiology and Infectious Disease eLife digest Cancer cells can grow and spread in one individual, but they normally do not spread to others. There are cancers in Tasmanian devils, dogs and bivalve shellfish that can spread to other members of the same species. In these creatures, cancer from one individual evolved the ability to spread throughout the population. Cancer from one individual evolved the ability to spread throughout the population These cancer cells infect animals like a pathogen

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