Detection of Host-specific Immunogenic Proteins in OSCC Patients' Sera

Objective: Oral cancer is a highly prevalent cancer in the world, and often remains undetected until the later stages. Therefore, the identification of suitable and reliable OSCC biomarkers are essential to allow early detection and treatment, in order to reduce the mortality rates of OSCC. This study was conducted to identify novel OSCC biomarkers in order to promote the development of specific diagnostic tests for the early detection of oral cancer. In addition to providing potential biomarkers for the early detection of oral cancers, our study contributes to the understanding of ‘naturally occurring antibodies’ in cancer. Methods: In the present study, serum samples from OSCC patients (n=25) and healthy controls (n=25) were subjected to two-dimensional electrophoresis (2-DE) and silver staining. Potential immunogenic proteins were subsequently identified by immunoblotting with pooled sera. Spots of interest were sequenced via MALDI-TOF mass spectrometry and analyzed using MASCOT database search. Results: Several proteins were identified upon comparing control and patient sera: alpha-1-B-glycoprotein (ABG), heptoglobin (HAP), CLU, leucine-rich α2-glycoprotein (LRG), retinol-binding protein 4 precursor (RBP4), PRO2044, and proapolipoprotein (Proapo-AI). Immunoblot revealed five host-specific proteins: C3, CLU RBP4, HAP, and Proapo-AI. Furthermore, five non-host factors were detected, including antigens from Acinetobacter lwoffii, Burkholderia multivorans, Myxococcus xanthus, Laribacter hongkogenisis, and Streptococcus salivarius. Conclusion: Taken together, our serological approach has identified several immunogenic biomarkers that could facilitate detection of early stage OSCC.