Abstract

Tasmanian devil Facial Tumour Disease

The Tasmanian devil (Sarcophilus harrisii), is the world’s largest remaining marsupial carnivore and is endemic to the island state of Tasmania, Australia. Wild populations are at risk of extinction since the recent emergence of a terrifying transmissible cancer, Devil Facial Tumour Disease (DFTD). DFTD is characterised by the appearance of large, locally invasive tumours on the face, neck and mouth of affected animals. Metastasis to abdominal and thoracic viscera is common and mean survival time after the appearance of initial lesions is less than six months. Mortality rates are 100% and no disease resistance has been reported.

Remarkably, all tumours share an identical, highly rearranged karyotype, regardless of the sex of the animal or progression of the tumour. Several chromosomes, including both sex chromosomes are apparently lost, presumably rearranged in four unidentified marker chromosomes. This suggests that, rather than arising spontaneously in affected animals, DFTD is a clonal cell line transmitted between animals by biting.

We are investigating the extent of the chromosome rearrangements in the tumour using chromosome painting. By identifying breakage and fusion points we hope to determine which genes may have been disrupted to give DFTD its extraordinary malignant characteristics. We are complementing cytogenetic studies with molecular approaches including cDNA and miRNA sequencing with the aim of identifying tumour pathways and biomarkers for early diagnosis, therapy or vaccination.