Abstract
Devil Facial Tumour Disease (DFTD) is an emerging infectious disease that provides an excellent example of how diagnostic techniques improve as disease-specific knowledge is generated. DFTD manifests as tumour masses on the faces of Tasmanian devils, first noticed in 1996. As DFTD became more prevalent among devils, karyotyping of the lesions and their devil hosts demonstrated that DFTD was a transmissible cancer. The subsequent routine diagnosis relied on microscopy and histology to characterise the facial lesions as cancer cells. Combined with immunohistochemistry, these techniques characterised the devil facial tumours as sarcomas of neuroectodermal origin. More sophisticated molecular methods identified the origin of DFTD as a Schwann cell, leading to the Schwann cell-specific protein periaxin to discriminate DFTD from other facial lesions. After the discovery of a second facial cancer (DFT2), cytogenetics and the absence of periaxin expression confirmed the independence of the new cancer from DFT1 (the original DFTD). Molecular studies of the two DFTDs led to the development of a PCR assay to differentially diagnose the cancers. Proteomics and transcriptomic studies identified different cell phenotypes among the two DFTD cell lines. Phenotypic differences were also reflected in proteomics studies of extracellular vesicles (EVs), which yielded an early diagnostic marker that could detect DFTD in its latent stage from serum samples. A mesenchymal marker was also identified that could serve as a serum-based differential diagnostic. The emergence of two transmissible cancers in one species has provided an ideal opportunity to better understand transmissible cancers, demonstrating how fundamental research can be translated into applicable and routine diagnostic techniques.
Highlights
During their training, medical students are taught the importance of extracting an accurate patient’s clinical history
More complex procedures include the extraction of genetic material, which can be analysed by molecular techniques such as polymerase chain reaction (PCR) and sequencing
Of the multiple neuroectodermal markers identified in Devil Facial Tumour Disease (DFTD), we found that periaxin was consistently expressed by DFTD cells [7]
Summary
Medical students are taught the importance of extracting an accurate patient’s clinical history. The history will reveal valuable clues to a skilled medical practitioner that will inform a potential diagnosis, and the appropriate laboratory tests will confirm the diagnosis. This process is relevant to diagnosing infectious diseases and cancer, as a prompt and accurate diagnosis relies on the correct laboratory test. Biomarkers primarily in the blood (e.g., IgG for myeloma) but occasionally in the urine (e.g., Beta-2 microglobulin for leukaemia) or in the cerebrospinal fluid (e.g., fibrin for bladder cancer) can assist in diagnosis and monitoring Molecular tests such as PCR, chromosomal analysis, fluorescent in situ hybridisation (FISH) and genetic sequencing provide additional diagnostic data. Similar studies of cancer of wild animals are not usually afforded such luxuries, except when interesting cases arise, such as transmissible cancers in dogs and Tasmanian devils
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