Min-Young Seong (Daegu Gyeongbuk Institute of Science and Technology (DGIST))

Min-Sik Kim (Daegu Gyeongbuk Institute of Science and Technology (DGIST))

Min-Young Seong (Daegu Gyeongbuk Institute of Science and Technology (DGIST))

JunHee Kim (Daegu Gyeongbuk Institute of Science and Technology (DGIST))

Min-Sik Kim (Daegu Gyeongbuk Institute of Science and Technology (DGIST))

Gastrointestinal (GI) cancers exhibit high incidence and mortality. Since survival declines precipitously as disease advances, early diagnosis is essential. However, the plasma proteome of elderly patients exhibits extreme biological variance due to aging, comorbidities, and medication use, making consistent biomarker discovery highly challenging. This study aims to identify novel GI cancer biomarkers for elderly patients by overcoming these analytical hurdles. To mitigate signal interference from high-abundance proteins, we optimized a Strong-Anion Exchange (SAX) magnetic bead-based depletion method. We pooled plasma samples from 40 patients per cancer type (colorectal, gastric, and liver) to minimize individual variance, followed by Data-Independent Acquisition (DIA) mass spectrometry. Gene Ontology Biological Process (GOBP) analysis revealed distinct pathways specific to each cancer type. Furthermore, proteins commonly up-regulated across all three cancers were heavily enriched in protein catabolic processes and T-cell mediated immune responses, which are associated with the tumor microenvironment (TME). Based on proteins up-regulated compared to age-matched healthy controls, we derived a list of clinically applicable signature peptides and narrowed biomarker candidates through rigorous filtering. Ultimately, these candidates will be validated via individual profiling to establish a robust biomarker panel for elderly GI cancer patients.