PO-082 Salivary extracellular vesicles from oral cancer patients: exclusive signature of the infrared spectrum

Abstract

IntroductionExtracellular vesicles (EVs), like exosomes, are attributed crucial paracrine and endocrine effects, which are of utmost importance in cancer. EVs carry markers that characterise their parental cells, and as such they also have a central diagnostic value. EVs are found in all body fluids, including saliva. EVs from oral cancerous cells are expected to concentrate in saliva. Our aim was to determine whether the infrared (IR) spectra of salivary EVs from oral cancer (OC) patients were significantly different from IR spectra of healthy individuals (HI).Material and methodsWhole saliva samples were collected from 9°C patients and 8 HI. Saliva was further collected from additional 12°C patients and pooled together to one sample. In parallel, saliva was pooled from 5 additional HI. EVs were pelleted from samples of saliva (17 individual samples and 2 pools) using differential centrifugation (12,000 × g followed by 120,000 × g). The mid-IR absorbance spectra were measured in the range of 700cm-1 to 5,000cm-1, using MIR8025 Oriel Fourier transformation infrared (FTIR) equipped with a PIKE MIRacle ZnSe attenuated total reflectance (ATR) attachment.Results and discussionsIndividual and pooled pellets from OC patients showed a similar pattern of spectroscopy which was different from that of the HI (individual and pooled). The IR spectra of cancer versus healthy was consistently different in the 1025 (cancer peak) and 1080 (healthy peak) cm-1 region, 1,745 cm-1, 2,855 cm-1 and 2,925 cm-1 (low-to-absent in cancer), and in the region of 1,540 cm-1 (higher peak in cancer). A linear discriminant analysis (LDA) model showed a sensitivity of 90% and specificity of 100%.ConclusionA specific IR spectral signature for OC salivary EVs was shown for the first time in this pilot study. The high sensitivity and specificity of the outcomes warrant further analysis that may yield an efficient, reproducible and non-invasive clinical tool for the diagnosis of oral cancer at its very early stages or in oral lesions with potential for malignant transformation.