Identification of blood-protein carriers of the CA 19-9 antigen and characterization of prevalence in pancreatic diseases.

The current best serum marker for pancreatic cancer, CA 19-9, detects a carbohydrate antigen on multiple protein carriers. Better knowledge of the protein carriers of the CA 19-9 antigen in various disease states may lead to improved diagnostic tests. To identify proteins that carry the CA 19-9 antigen, we immunoprecipitated the CA 19-9 antigen from pooled sera and identified the associated proteins using MS. Among the high-confidence identifications, we confirmed the presence of the CA 19-9 antigen on Apolipoprotein B-100 by antibody arrays and Western blot and on kininogen, ARVCF, and Apolipoprotein E by antibody arrays. We characterized the frequency and levels of the CA 19-9 antigen on the four proteins across various patient groups (pancreatic cancer, pancreatitis, and healthy controls) using antibody arrays. Nearly, 10-25% of the subjects showed elevations of the antigen on each protein, but the elevations were not associated with disease state or total CA 19-9 levels. These results contribute to our knowledge of the carrier proteins of an important functional glycan and the rate at which the glycan is displayed. This work also demonstrates a strategy for using the complementary methods of MS and antibody microarrays to identify protein carriers of glycans and assess the diagnostic value of measuring glycans on individual proteins.

Andrews P, Brand RE, Haab BB, Hurley M, Kaul K, Maupin KA, Moser AJ, Partyka K, Yue T, Zeh H


Proteomics, 2011, 11 (18)

Version 5.1.0