Ancient Dog Cancer Hints at First Canine Host
Researchers have provided the first whole-genome sequence of a transmissible tumor that originated in a single dog over 10,000 years ago and continues to spread among domestic dogs to this day. Canine transmissible venereal tumor, or CTVT, is one of two known transmissible cancers; it spreads within domestic dog populations by the transfer of living cancer cells, typically during sex. Though these cancer cells have a genome sequence derived from a dog, they are now living on their own in many dog species, as parasitic organisms. Inside the tumor DNA code, however, the genome of their very first host continues to survive. In their investigation, the researchers found almost two million somatic mutations -- over a hundred times more somatic mutations than found in most human tumors. The work of Murchison et al., which reveals the origins, history, and evolution of the world's oldest known cancer cell line, highlights the ability of the mammalian somatic genome to adapt and persist in a new ecological niche (here, the canine host).
[Image: Dogs genetically most similar to the tumor (top to bottom): Siberian husky; Alaskan Malamute; depiction of the CTVT founder; Shar-pei; dingo; Chow chow; and Akita. CREDIT: The tree is modified from vonHoldt et al. by P. Huey/Science.]
Researchers have provided the first whole-genome sequence of a transmissible tumor that originated in a single dog over 10,000 years ago and continues to spread among domestic dogs to this day. Canine transmissible venereal tumor, or CTVT, is one of two known transmissible cancers; it spreads within domestic dog populations by the transfer of living cancer cells, typically during sex. Though these cancer cells have a genome sequence derived from a dog, they are now living on their own in many dog species, as parasitic organisms. Inside the tumor DNA code, however, the genome of their very first host continues to survive. In their investigation, the researchers found almost two million somatic mutations -- over a hundred times more somatic mutations than found in most human tumors. The work of Murchison et al., which reveals the origins, history, and evolution of the world's oldest known cancer cell line, highlights the ability of the mammalian somatic genome to adapt and persist in a new ecological niche (here, the canine host).
[Image: Dogs genetically most similar to the tumor (top to bottom): Siberian husky; Alaskan Malamute; depiction of the CTVT founder; Shar-pei; dingo; Chow chow; and Akita. CREDIT: The tree is modified from vonHoldt et al. by P. Huey/Science.]
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