Chronic exposure of the oral mucosa to
carcinogens in tobacco is linked to
inflammation and development of oral premalignant lesions (OPLs) with high risk of progression to
cancer; there is currently no clinical methodology to identify high-risk lesions. We hypothesized that identification of differentially expressed
proteins in OPLs in relation to normal oral tissues using proteomic approach will reveal changes in multiple cellular pathways and aid in
biomarker discovery. Isobaric mass tags (iTRAQ)-labeled oral dysplasias and normal tissues were compared against pooled normal control by online liquid chromatography and tandem mass spectrometry. Verification of
biomarkers was carried out in an independent set of samples by immunohistochemistry, immunoblotting, and RT-PCR. We identified 459 nonredundant
proteins in OPLs, including structural
proteins, signaling components,
enzymes, receptors,
transcription factors, and chaperones. A panel of three best-performing
biomarkers identified by iTRAQ analysis and verified by immunohistochemistrystratifin (SFN), YWHAZ, and hnRNPKachieved a sensitivity of 0.83, 0.91, specificity of 0.74, 0.95, and predictive value of 0.87 and 0.96, respectively, in discriminating dysplasias from normal tissues, thereby confirming their utility as potential OPL
biomarkers. Pathway analysis revealed direct interactions between all the three
biomarkers and their involvement in two major networks involved in
inflammation, signaling, proliferation, regulation of gene expression, and
cancer. In conclusion, our work on determining the OPL
proteome unraveled novel networks linking
inflammation and development of epithelial dysplasia and their key regulatory
proteins may serve as novel chemopreventive/therapeutic targets for early intervention. Additionally, we identified and verified a panel of OPL
biomarkers that hold promise for large-scale validation for ultimate clinical use.