Sialylated Lewis x Antigen Bearing Glycoproteins in Human Plasma

• Published in: Journal of proteome research Vol. 9; no. 11; pp. 5960 - 5968
• Main Authors: Cho, Wonryeon, Jung, Kwanyoung, Regnier, Fred E
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 05-11-2010
• Subjects: Antibodies, Monoclonal; Breast Neoplasms - chemistry; Female; Glycoproteins - chemistry; Glycoproteins - immunology; Glycoproteins - isolation & purification; Humans; Lewis X Antigen - blood; Lewis X Antigen - immunology; Neoplasm Proteins - blood; Protein Conformation; sialylation; quantification; posttranslational modification; GlcNAc-β-(1,6)- branching; CHO-131 antibody; immunoaffinity chromatography; targeted proteomics; glycosylation; breast cancer; sialyl Lewis x antigen; plasma
• ISSN: 1535-3893; 1535-3907
• DOI: 10.1021/pr100747p

Recent studies have shown that antibodies targeting Lewis x (Lex) antigen are a valuable tool in the isolation and identification of glycoproteins in plasma. A focus of this study was to determine whether sialylated Lewis x (sLex) antigen carrying glycoproteins occur in human plasma and whether an antibody targeting this antigen could be used to isolate and identify glycoproteins bearing this antigen. An additional objective was to determine the degree to which proteins conjugated to Lex and sLex antigens are similar in structure. A specific anti-sLex antibody (anti-sLexAb), CHO-131, immobilized in an immunoaffinity column was used to select a set of specific sLex bearing proteins from human plasma, after which they were identified by either of two analytical strategies. One approach was to further resolve the affinity selected proteins by reversed phase chromatography (RPC), tryptic digest the RPC fractions, and identify peptide fragments by MALDI-MS/MS. The second was to tryptic digest the affinity selected protein fraction, further resolve the tryptic fragments by RPC, and identify peptides from RPC fractions by MALDI-MS/MS. Histidine-rich glycoprotein, plasminogen, apolipoprotein A-I, vitronectin, proteoglycan-4, clusterin, Ig gamma-2 chain C region, Ig mu chain C region, and interalpha-trypsin inhibitor heavy chain H4 were found to change three folds or more in association with breast cancer. Fifty percent of the glycoproteins carrying either sLex antigen from CHO-131 selection, Lex antigen from selection with TG-1 antibody, or both were found to be changed three folds or more in concentration in breast cancer plasma relative to controls.