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BACKGROUND: Tobacco exposure (through smoking or chewing) is one of the predominant risk factors associated with the development of oral squamous cell carcinoma (OSCC). Despite the growing number of patients diagnosed with OSCC, there are few circulating biomarkers for identifying individuals at a higher risk of developing the disease. Successful identification of candidate molecular markers for risk assessment could aid in the early detection of oral lesions and potentially be used for community screening of high-risk populations. OBJECTIVE: Identification of differentially expressed proteins in the serum of oral cancer patients which can serve as biomarkers for the diagnosis of the onset of oral cancer among tobacco users. METHODS: We employed a tandem mass tag (TMT)-based quantitative proteomics approach to study alterations in the serum proteomes of OSCC patients based on their tobacco exposure habits (chewing and smoking) compared to healthy individuals with no history of using any form of tobacco or any symptoms of the disease. RESULTS: Mass spectrometry-based analysis resulted in the identification of distinct signatures in the serum of OSCC patients who either chewed or smoked tobacco. Pathway analysis revealed opposing effects of dysregulated proteins enriched in the complement-coagulation signaling cascades with a high expression of the Serpin family of proteins observed in OSCC patients who chewed tobacco compared to healthy individuals whereas these proteins showed decreased levels in OSCC patients who smoked. ELISA-based validation further confirmed our findings revealing higher expression of SERPINA6 and SERPINF1 across serum of OSCC patients who chewed tobacco compared to healthy individuals. CONCLUSIONS: : This study serves as a benchmark for the identification of serum-based protein markers that may aid in the identification of high-risk patients who either chew tobacco or smoke tobacco. [ABSTRACT FROM AUTHOR]

Background: Tobacco consumption in smoking and non‐smoking forms has been consequential in the rise of oral cancer cases. Among different forms, epidemiological studies from Middle Eastern countries and rural parts of northern India have reported increasing association of oral cancer with waterpipe (hookah) smoking. However, molecular mechanisms and role played by waterpipe smoking in the onset of oral carcinogenesis remains unexplored. Methods: In this study, immortalized normal human oral keratinocytes were chronically treated with extracts of two varieties of waterpipe tobacco—crude tobacco and processed shisha. Phenotypic changes and molecular aberrations were examined using cell culture‐based assays and mass spectrometry‐based quantitative proteomic analysis, respectively. Bioinformatics analysis was utilized to analyze proteomics data and identify dysregulated pathways. Results: Our data indicate that chronic treatment with waterpipe tobacco extracts increased proliferation, invasion, migration, and significant dysregulation of protein expression in oral keratinocytes. Altered expression of proteins involved in interferon signaling pathway were observed with both varieties of tobacco. Overexpression of cholesterol metabolism and vesicle‐mediated transport proteins were identified exclusively in cells treated with crude tobacco extract. Bioinformatics analyses revealed different oncogenic response in oral cells based on the type of waterpipe tobacco used. Conclusions: This study may serve as a useful resource in understanding the early onset of oral cancer attributed to waterpipe smoking. [ABSTRACT FROM AUTHOR]

Tobacco abuse is a major risk factor associated with the development of oral squamous cell carcinoma. Differences in molecular aberrations induced by tobacco exposure by chewing or smoking form are not well studied in case of oral cancer. We used tandem mass tag-based quantitative proteomic approach to delineate proteomic alterations in oral cancer patients based on their history of tobacco using habits (patients who chewed tobacco, patients who smoked tobacco, and those with no history of tobacco consumption). Our data identified distinct dysregulation of biological processes and pathways in each patient cohort. Bioinformatics analysis of dysregulated proteins identified in our proteomic study revealed dysregulation of collagen formation and antigen processing/presentation pathway in oral cancer patients who smoked tobacco, whereas proteins associated with the process of keratinization showed enrichment in patients who chewed tobacco. In addition, we identified overexpression of proteins involved in immune pathways and downregulation of muscle contraction-mediated signaling events in all three cohorts, irrespective of tobacco using habits. This study lays the groundwork for identification of protein markers that may aid in identification of high-risk patients for cancer development based on the history of tobacco exposure habits. [ABSTRACT FROM AUTHOR]