Abstract 2492: Discovery and validation of novel serum glycoprotein biomarkers for Barrett's esophagus and esophageal adenocarcinoma
Authors: Shah Alok K. , Chen David , Cao Kim-Anh Le , Choi Eunju , Nancarrow Derek , Whiteman David , Saunders Nicholas A. , Barbour Andrew P. , Hill Michelle M. 
Published: May 2015

BACKGROUND: Esophageal adenocarcinoma (EAC) is one of the most rapidly increasing cancers globally. The majority of EAC cases are diagnosed at very late stages during pathogenesis hence &lt;15% of the patients survive 5 year post-diagnosis. There is an urgent need to improve diagnosis of EAC and its pre-cancer metaplastic condition, Barrett's esophagus (BE). BE patients are monitored using upper gastro-esophageal endoscopy with biopsy for early neoplastic changes. However, being an asymptomatic condition, it is very difficult to identify BE patients for screening. Moreover, endoscopy is unsuitable for population screening due to high cost, requirement of technical expertise and patient non-compliance. The aim of this project is to identify serum biomarkers for diagnosis of BE and EAC, with the goal of translating to blood tests.

APPROACH & METHODOLOGY: We focused on alterations in circulatory protein glycosylation, using a panel of 20 lectins to isolate different glycan structures on serum glycoproteins, as reported recently [1, 2]. Serum samples from healthy (n = 9), BE (n = 10) and EAC (n = 10) patient groups were analyzed by lectin magnetic bead array-coupled mass spectrometry (LeMBA-MS/MS) [1, 2]. Data analysis was performed using a customized database and analysis package “GlycoSelect” which incorporates outlier detection and sparse Partial Least Squares regression discriminant analysis (sPLS-DA) [3].

RESULTS & DISCUSSION: We identified a ranked list of candidate glycobiomarkers that distinguish a) EAC from BE b) BE from healthy and c) EAC from healthy group. In general, glycoproteins bound several lectins, reflecting heterogeneity and multiplicity of glycosylation. Specific glycan structure changes were observed as loss and gain of binding to a single lectin while maintaining binding to other lectins. Top two candidate biomarkers were validated using orthogonal validation technique LeMBA-immunoblotting in an independent patient cohort (n = 80). The biomarkers showed Area under Receiver Operating Characteristic curve (AUROC) of 0.74 to discriminate EAC from BE and 0.71 to discriminate BE from healthy patient group. Future work will validate all candidate protein-lectin pairs using lectin-affinity array coupled with triple quadrupole quantitative mass spectrometry measurements for the independent patient cohort. The specificity and sensitivity of panels of glycoprotein biomarkers will be determined for formulating a serum screening test for BE and EAC.

[1] Choi et al., Electrophoresis 32, 3564-3575 (2011)

[2] Loo et al., J Proteome Res 9, 5496-5500 (2010)

[3] Lê Cao et al., BMC Bioinformatics 12, 253-268 (2011)

Citation Format: Alok K. Shah, David Chen, Kim-Anh Le Cao, Eunju Choi, Derek Nancarrow, David Whiteman, Nicholas A. Saunders, Andrew P. Barbour, Michelle M. Hill. Discovery and validation of novel serum glycoprotein biomarkers for Barrett's esophagus and esophageal adenocarcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2492. doi:10.1158/1538-7445.AM2014-2492