RESUMO
The canine transmissible venereal tumor (CTVT) is a cancer lineage that arose several millennia ago and survives by "metastasizing" between hosts through cell transfer. The somatic mutations in this cancer record its phylogeography and evolutionary history. We constructed a time-resolved phylogeny from 546 CTVT exomes and describe the lineage's worldwide expansion. Examining variation in mutational exposure, we identify a highly context-specific mutational process that operated early in the cancer's evolution but subsequently vanished, correlate ultraviolet-light mutagenesis with tumor latitude, and describe tumors with heritable hyperactivity of an endogenous mutational process. CTVT displays little evidence of ongoing positive selection, and negative selection is detectable only in essential genes. We illustrate how long-lived clonal organisms capture changing mutagenic environments, and reveal that neutral genetic drift is the dominant feature of long-term cancer evolution.
Assuntos
Evolução Clonal/genética , Doenças do Cão/classificação , Doenças do Cão/genética , Tumores Venéreos Veterinários/classificação , Tumores Venéreos Veterinários/genética , Animais , Doenças do Cão/epidemiologia , Cães , Exossomos , Expressão Gênica , Mutagênese , Filogenia , Seleção Genética , Tumores Venéreos Veterinários/epidemiologiaRESUMO
The purpose of this paper is to establish criteria that could guide the diagnosis, prognosis and treatment of canine mammary neoplasias. It was elaborated during the Mammary Pathology Meeting: Diagnosis, Prognosis and Treatment of the Canine Mammary Neoplasm, held on November 6th and 7th, 2010 in Belo Horizonte MG, Brazil, sponsored by the Laboratory of Comparative Pathology UFMG, with the support of the Brazilian Association of Veterinary Pathology (ABPV) and Brazilian Association of Veterinary Oncology (ABROVET). Academics from several regions of Brazil were present and contributed to this work.