Identification of candidate biomarkers for the early detection of nasopharyngeal carcinoma by quantitative proteomic analysis

Nasopharyngeal carcinoma (NPC) is a major head and neck cancer with high occurrence in Southeast Asia and southern China. To identify novel biomarkers for the early detection of NPC patients, 2D-DIGE combined with MALDI-TOF-MS analysis was performed to identify differentially expressed proteins in the carcinogenesis and progression of NPC using LCM-purified normal nasopharyngeal epithelial tissues and various stages of NPC biopsies. As a result, 26 differentially expressed proteins were identified, of which two proteins with sharp expressional changes in the carcinogenic process, ENO1 and CYPA, were validated by western blot analysis and identified as critical seed proteins in the functional network. Immunohistochemistry assay was further performed to detect the expression of the two proteins with a tissue microarray that included various stages of NPC tissues. The ability of these proteins to detect NPC early was evaluated via a receiver operating characteristic analysis. The results indicated that the combination of the two proteins could perfectly discriminate NNET and AH from stage I of NPC with high sensitivity and specificity, which is more effective than using either of the two proteins individually. In summary, the combination of ENO1 and CYPA can serve as potential molecular markers for the early detection of NPC. (C) 2014 Elsevier B.V. All rights reserved.