Proteomic Analysis in Cellular Carcinogenesis Model of OSCC

Objective: To investigate the proteomic profiles of differentially expressed proteins in the in vitro cellular model of oral squamous cell carcinoma (OSCC).

Methods: Based on the first in vitro cellular carcinogenesis model of oral squamous cell carcinoma in China, comparative proteomic analysis was performed using two-dimensional gel electrophoresis and liquid chromatography-tandem mass chromatography to separate and identify differentially expressed proteins. The identified proteins were classified according to the Gene Ontology Convention to three ontologies of cellular component, molecular function, and biological process. Further five proteins were validated by Western blotting and immunohistochemistry in the cellular carcinogenesis model and tissue samples from OSCC patients.

Results: Fifty-four protein spots were separated, and 44 proteins were identified. Decreased expression of 23 proteins was found during cancerization from immortalized oral epithelial cells to squamous cancerous cells, and increased expression of 19 proteins was found during the cancerization. According to the Gene Ontology Convention, cytoplasmic proteins were the most common proteins in the category of cellular component; protein binding proteins and phosphatase active proteins were the most common proteins in the category of molecular function; cell signaling and transduction proteins, cell adhesion and motility proteins, and metabolic process proteins were the most common proteins in the category of biological process. Further validation of five identified proteins (ANXA1, ANXA2, CTSB, KRT17, and S100A6) in the cellular carcinogenesis model and cancerous tissues from oral squamous cell carcinoma patients confirmed the comparative proteomic results. Moreover, Annexin A1 and A2 expressions were found correlating with the pathological differentiation grade of cancerous tissues.

Conclusions: This work provides a dynamic protein file of differentially expressed proteins to perform further investigations on mechanism researches of OSCC cancerization, as well as potential biomarkers for clinical diagnosis or prognostic monitoring.