The development of serological biomarkers for pancreatic cancer could improve the clinical control of this disease by optimizing the process of diagnosis and treatment. The current best blood test uses the marker CA19-9, which detects the total level of the carbohydrate antigen sialyl Lewis a. The clinical usefulness of CA19-9 is limited due to its occasional elevation in non-cancer conditions as well as its low levels in some pancreatic cancer patients. Therefore, in this dissertation work, we aimed to improve the detection of pancreatic cancer over the standard marker CA19-9. We used a novel strategy to develop biomarkers. The central hypothesis supporting this strategy is that by measuring the particular glycan on selected protein, we can improve the detection of pancreatic cancer compared to using the measurement of protein or glycan alone. The strategy enables us to examine the relationship between the changes in glycan and protein levels, It got implemented with the aid of a high-throughput sandwich assay which is based on antibody microarray technology and assisted by glycan binding proteins. The specificities of the glycan binding proteins were determined from a motif-based analysis.In the first half of the study, we focused on three mucin proteins, MUC1, MUC5ac and MUC16 and profiled their glycosylation changes that were associated with pancreatic cancer. The elevations in glycosylation fell into 6 major groups which were determined by the specificities of the detection glycan binding proteins. Despite the overall elevation for all 6 groups of glycans, distinct patterns of alteration were found among the three mucins. Indeed, the complementary elevation of glycan identified on the carrier mucin improved the detection of pancreatic cancer more than using the protein detection alone. This part of the study suggests that the three mucins are carriers of glycosylations associated with pancreatic cancer. In the second half of the dissertation, we focused on the glycan CA19-9 and studied its prevalence on the three mucins and other proteins. Our aim was to develop a biomarker panel to distinguish pancreatic cancer from pancreatitis. A total of 420 individual samples including late-stage cancer, early-stage cancer, pancreatitis, and healthy control were obtained from 3 independent institutions for these studies. A complementarity strategy was developed for panel selection. We developed a biomarker panel enhancing the detection of pancreatic cancer than using the standard CA19-9 assay. We also identified a novel carrier protein for CA19-9, Apolipoprotein B-100, which did not contribute to the elevation of total CA19-9 in pancreatic cancer. ApoB represents the group of CA19-9 carriers irrelevant to pancreatic cancer development. Altogether, this part of study highlights the necessity of examining CA19-9 on carriers associated with pancreatic cancer. In conclusion, this research demonstrates the effectiveness of a platform for glycan biomarker development. The platform features include high-throughput measurements of specific glycan changes on particular proteins and a complementarity strategy for selecting biomarker panels. The panel identified in this dissertation enhances the detection of pancreatic cancer and provides advanced patient stratification for future marker development.
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