Abstract 4565: Tissue protein biomarkers of neoplastic progression in Barrett's esophagus

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Abstract The incidence rate of esophageal adenocarcinoma (EAC) has risen by 350% since 1970, outpacing all other cancers (www.nci.gov). There are approximately 15,000 new cases of esophageal cancer per year in the United States, half of which are EAC. The incidence of EAC is 4 cases per 100,000 person years. This cancer is associated with a dismal prognosis, with an overall five-year survival of less than 15%. Although the survival rate depends on the stage of disease, more than 50% of patients present with dysphagia (difficulty swallowing) secondary to obstruction from the tumor and with incurable disease. Upon review of the Surveillance Epidemiology and End Results database for the last 27 years, it is ominous that the incidence rate for esophageal cancer is mirrored precisely by the age-adjusted mortality for a given year. Currently, risk for esophageal cancer is determined solely by the histologic appearance of Barrett's esophagus (BE), however there is a large degree of intra- and inter-observer variability among pathologists. The ability to identify and validate protein biomarkers of disease progression from Barrett's metaplasia to esophageal adenocarcinoma, when treatment outcome is still favorable, would result in a reduction in mortality by aiding in the identification of new diagnostic and treatment options for this disease. We hypothesized that signature protein biomarkers predictive of BE progression could be identified in tissue biopsies that correlate with the metaplasia-dysplasia-carcinoma pathway, which may provide a more reliable set of diagnostic tools, prognostic markers, and therapeutic targets for EAC. Cells from formalin-fixed paraffin embedded (FFPE) tissue sections from defined histological regions of metaplasia (n=9), dysplasia (n=10) and adenocarcinoma (n=12) of the esophagus were procured by laser capture microdissection. A mass spectrometry (MS)-friendly heat-induced/enzyme-mediated antigen retrieval method developed in our laboratory was utilized to produce global tryptic digests from the LCM-procured cells. The digests were randomized and analyzed by high-resolution liquid chromatography-tandem mass spectrometry with an Orbitrap MS, resulting in the identification of an average of 2015 peptides and 652 proteins per sample, with an average relative standard deviation of 15%. Spectral counting and hierarchical cluster analysis enabled the identification of over 80 proteins whose abundances significantly change as a function of neoplastic progression of BE. Several of these putative BE progression biomarkers were validated by quantitative multiple reaction monitoring MS and/or immunohistochemistry, including mucin 5 A/C and 2, cytokeratin 20 and galectin 3. This study is the largest and most comprehensive discovery-driven proteomic analysis of Barrett's esophagus tissue where multiple candidates of progression have been validated by orthogonal techniques. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4565.