Cancer biomarker discovery from Sera of cancer patients.

Current screening methods for early detection of gastric cancer remain controversial and unsatisfactory, necessitating the need for novel non-invasive biomarkers. The rich diagnostic information in blood makes it the preferred source for candidate discovery. Available pre-fractionation strategies used to reduce complexity issue in blood often result in concomitant removal of potential biomarkers. Recent attention toward exosomes has revealed appealing properties and functions of these nanovesicles that are released by most cell types into the extracellular environment. We therefore propose the isolation and exploitation of blood-derived exosomes as an alternate pre-fractionation strategy and as potential biomarkers for early diagnosis of gastric cancer. With a lack of consensus in exosome isolation, we have evaluated several methods for enrichment and have found ExoQuickTM, a newly developed method, incompatible for proteomic analysis of exosomes. We thus developed an optimal ultracentrifugation-based method to isolate exosomes from blood samples. In this study, we present the first differential proteomic analysis of blood-derived exosomes from normal and diseased states and identified several potential gastric cancer-specific diagnostic biomarkers including 14-3-3, HLA-A and PIK3CA. Efforts in exosome purification and resulting proteomics description of gastric cancer-exosomes would provide new insights that will benefit future development platforms in similar blood-based discovery studies.Bachelor of Science in Biological Science