SALIVARY PROTEOME ANALYSIS BY 2D-PAGE AND SELDI-TOF/MS TO SEARCH POTENTIAL BIOMARKERS OF ORAL SQUAMOUS CELL CARCINOMA

Abstract

Aim. Oral squamous cell carcinoma (OSCC) is the most common malignant tumor of the oral cavity and is a neoplasia characterized by a poor prognosis. In fact, the estimated survival rate is 44% after 5 years from the diagnosis. The prognosis of the disease is significantly related to the stage in which the disease is diagnosed. Moreover the therapies are not very efficient and are so invasive, disfiguring and debilitating that in the survivors the quality of life is poor. Nowadays there is not a reliable and non-invasive method for early diagnosis of oral squamous cell carcinoma and the simple visual examination of the oral cavity is characterized by a low sensitivity and specificity, also because in a significant number of patients the early stages of oral carcinogenesis are not associated with clearly evident clinical abnormalities. The aim of the study was to determine the potential biomarkers of early and non-invasive diagnosis and to use a test that was less subject to the clinical experience of the examiner. Furthermore, we tried to use the saliva as a biological matrix to make a rapid, simple and economic diagnosis. Materials and methods. In the current study, we analysed 65 saliva samples of patients with OSCC (25 stage I and II, 40 stage III and IV) and 34 healthy controls (HS). Stage I and II OSCC patients were classified as Early Stage OSCC (ES-OSCC), while stage III and IV patients were classified as Late Stage OSCC (LS-OSCC). All samples were collected and processed for proteomics research. Each sample has undergone an ethanol frozen precipitation to be purified and then was made a 2D-PAGE electrophoresis. Separated proteins were eluted for SELDI-TOF mass spectrometry analysis. Protein profiles of all samples were analysed using BIORAD DataManagerTM software (Ver 3.5). Results. From this analysis we identified a list of differently expressed mass peaks (clusters). We noted the presence of protein spots in gel of samples ES-OSCC. No spots were found in LS-OSCC and HS samples. After a passive elution of spots, we identified the same peaks more expressed in ES-OSCC: 13512, 13509, 14168, 14041, 14040, 13649, 13652, 13,493, 10899 and 10895 m/z. The same peaks were more expressed in ES-OSCC rather than in LS-OSCC. Conclusions. Overall, our data confirm that the salivary proteome of patients with OSCC seems to be different in each stage of oral cancer progression. These data also indicate a strong association between the levels of salivary marker of 13512, 13509, 14168, 14041, 14040, 13649, 13652, 13,493, 10899 and 10895 m/z and the OSCC. For this reason, if confirmed on large series of patients, these biomarkers can be useful for a rapid and non-invasive diagnosis of the disease.