<b>ITRAQ and PRM-based quantitative saliva proteomics in gastric cancer: biomarker discovery.</b>

This study focuses on salivary proteomics as a non-invasive and cost-effective approach for the early detection of gastric cancer (GC). Using a combination of iTRAQ-based proteomic analysis and PRM validation, the researchers systematically profiled the salivary proteomes of GC patients and healthy controls to identify differentially expressed proteins (DEPs). Bioinformatics tools, including GO, KEGG, and PPI network analyses, were applied to explore the biological significance of these proteins. Importantly, four candidate proteins S100A8, S100A9, CST4, and CST5 were highlighted as potential diagnostic biomarkers. Interestingly, CST4 and CST5 showed an inverse expression pattern between saliva and tumor tissues/blood, suggesting complex regulatory mechanisms. This research contributes to the growing field of saliva-based diagnostics and provides novel insights into biomarker discovery for early GC detection.