May 2014
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With an increasing recognition of the association between oral and systemic diseases, attention has turned to saliva as an alternative diagnostic medium for a diverse array of health conditions [Malamud D, Tabak LA, 1993]. Compared with blood, saliva collection is non-invasive, easy to collect with multiple sampling opportunities, does not need pre-processing and is ideal for 3 rd world countries [T Pfaffe, J Cooper-White, P Beyerlein, K Kostner, C Punyadeera, 2011]. Within our group, we are developing diagnostic tools to detect heart failure (HF) and head and neck squamous cell carcinoma (HNSCC). Heart Failure (HF) is a major global public health concern that accounts for a substantial number of hospitalizations, major healthcare resource utilization and cost. HNSCC encompasses a diverse group of aggressive tumours and it is well established that tumour cells secrete biomolecules into the saliva [Simona Principe, Angela Bik-Yu Hui, Jeff Bruce, Ankit Sinha, Fei-Fei Liu1, and Thomas Kislinger, 2013]. Currently, there are no early diagnostic tests to detect these diseases. We have recently identified an HF specific peptide (NT-proBNP) in the saliva of HF patients, which is not detectable in saliva from healthy controls [ Punyadeera, 2012]. DNA methylation and microRNAs (miRNAs) are the most extensively studied epigenetic biomarkers in HNSCC [Yanning Ma, Xian Wang and Hongchuan Jin]. We collected saliva (resting saliva and buccal swabs, DNA • SAL™) from HNSCC patients and healthy controls and interrogated CpG hypermethylation events in tumour suppressor genes using a sensitive methylation-specific PCR (MSP) assay. RASSF1a, DAPK1 and p16, showed an overall specificity of 87% and sensitivity of 80%. In addition, miR-9 and miR-191 provided good discriminative power with AUC values of 0.76 and 0.73 respectively (p<0.01) for discriminating HNSCC patients from healthy controls. In conclusion, we demonstrate that human saliva is useful as an alternative biological fluid to detect HF and HNSCC. Financial support from the Queensland Government Smart Futures Fellowship Programme (QGSFF), Queensland Centre for Head and Neck Cancer and the University of Queensland Diamantina Institute Strategic Funds. We also like to thank Ms Dana Middleton (clinical trial coordinator) and staff at the ENT Department at the Princess Alexandra Hospital, Woolloongabba, Australia.