Quantitative Proteomic Analysis of Non,Tobacco Associated Oral Squamous Cell Carcinoma Reveals Deregulation of Cytoskeletal and Apoptotic Proteins

Abstract

Background: The exact etiology of non,tobacco associated oral squamous cell carcinoma (NT,OSCC) is still unknown. The lack of established biomarkers for oral NT,OSCC has resulted in less effective management and poor prognosis. Here, we report for the first time a panel of potential markers identified from the quantitative proteomic analysis of NT,OSCC using two,dimensional gel,electrophoresis (2D,GE) using matrix,assisted laser desorption/ ionization, time of flight (MALDI,TOF) coupled with mass spectrometry (MS) and further analysis using protein analysis through evolutionary relationships (PANTHER) database. Objective: To quantitatively analyze the proteomic profile of non,tobacco associated oral squamous cell carcinoma. Methods: Twenty fresh tissue samples were collected from healthy controls and NT,OSCC, ten each, and were subjected to proteomic analysis. Sample quantification for the presence of protein was done using Bradford assay and bovine serum albumin was used as a standard protein to obtain the standard graph. Fractionation of protein was done using sodium dodecyl sulphate – polyacrylamide gel electrophoresis (SDS,PAGE) and they were separated based on their molecular weight. MS analysis was done and the purified peptides were analysed using MALDI,TOF. PANTHER database for functional classification and pathway analysis was done for identification of protein expression. Results: Our approach of combining 2D,GE with MS identified four candidate proteins including keratin, alpha,1,antitrypsin (AAT), S100 and serpin B5 with significant differential expression in NT,OSCC as compared with healthy controls. The results showed that the levels of these proteins were significantly upregulated in NT,OSCC when compared to the healthy controls that suggests that these proteins can be used as candidate targets for NT,OSCC therapeutics. Conclusion: The differentially expressed proteins are found to be involved in apoptotic signalling pathways, cytoskeletal dynamics and are known to play a critical role in oral tumorigenesis. Put together, the results provide available baseline information for understanding the development and progression of NT,OSCC. These identified proteins on further validation may be used as potential biomarkers in future for early detection and predicting therapeutic outcome of patients with NT,OSCC.