Proteomic identification of salivary biomarkers in 20 patients with Oral Squamous Cell Carcinoma

Objectives. Saliva has been proposed as a potential diagnostic fluid combined with proteomic analysis. The aim of this study is to assess the proteomic salivary profile using SELDI-TOF-MS technology in patients with Oral Squamous Cell Carcinoma (OSCC), grouped in relation to the TNM staging and compared with healthy subjects. Methods. In this secondary hospital based case-control study, patients with confirmed histopathological diagnosis of primary untreated OSCC as “cases” and healthy age- and sex-matched subjects as “controls” were consecutively enrolled, after informed consent. Saliva (5 mL) was collected by spitting directly into a clean 15 mL conical tube, aliquoted and stored at -80°C until use. SELDI-TOF Q10 ProteinChip system was used to screen for differentially expressed proteins in the saliva samples according to the manufacturer’s instructions (BioRad Inc). Univariate statistics and Roc plot were used for data analysis. Results. Twenty cases (6 M, 14 F, middle age 66.8 yy) and 20 controls (8 M, 12 F, middle age 61.9 yy) were included. In cases, seven were early-EsOSCC (3 stage I and 4 stage II) and 13 were late-LsOSCC (7 stage III and 6 stage IV). Proteomic analysis showed significant statistical differences in peptide profile in control vs OSCC and in EsOSCC vs LsOSCC samples (p<0.05). The differentiated pattern between overall OSCC and controls consisted of one peptide peak (8940-ROC:1), between EsOSCC and controls of four peptide peaks (7096-ROC 0.93; 12712–ROC:0.89; 8086 – ROC: 0.93 and 11002 – ROC:0.93) and between LsOSCC and EsOSCC of one peptide peak (6026-ROC 0.80). Conclusions. Although with limitation of the small sample size, this first study suggests that saliva contains proteomic signatures that could serve as biomarkers for OSCC at different stages. Once validated on a large clinical cohort, oral fluid proteomic based on SELDI-TOF-MS technology may be extensively used as a promising new non-invasive tool for early diagnosis in oral cancer patients.