Proteomics Analysis of Oral Epithelial Cells Collected by Brush Biopsy

Exfoliated epithelial cells from the oral mucosa collected non-invasively by a cytological brush contain valuable diagnostic molecular messages reflective of the carcinogenesis process in the oral cavity. Objective: To identify these messages, histological and RNA analysis have been previously applied to these samples. However, prior to this report, no protein analysis using proteomic technologies has been performed. Methods: Seeking to determine the feasibility for analysis by mass spectrometry-based proteomics we investigated methods for processing cells obtained by cytological brush from 4 individuals with healthy mucosa and 4 individuals with oral leukoplakia. Results: We found that “on brush” cell lysis followed by tryptic digestion maximized protein recovery, leading to the identification by liquid chromatography tandem mass spectrometry of 45 and 36 proteins from oral leukoplakia and healthy samples. Several proteins identified exclusively from the leukoplakia cells are known to play in role in the transition of oral lesions to malignancy, demonstrating the ability to detect different protein signatures specific to the state of the collected cells. Conclusions: These results demonstrate the feasibility of combining oral brush cytology and proteomics analysis, laying a foundation for expanded studies seeking to identify protein markers diagnostic of the transition from a healthy oral epithelium to malignancy.