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[524] Application of a Global Proteomic Approach to Archival Precursor Lesions: Upregulation of DMBT-1 and TG2 in Pancreatic Cancer Precursors

WL Cheung, DB Krizman, H Alvarez, BL Hood, MM Darfler, TD Veenstra, J Mollenhauer, N Habbe, G Feldman, A Maitra. Johns Hopkins University School of Medicine, Baltimore, MD; Expression Path Incorporated, Gaithersburg, MD; NCI, Frederick, MD; Deutschen Krebsforschungszentrum, Heidelberg, Germany

Background: Pancreatic cancer is a fatal disease; hence, early detection is a critical determinant of improved survival. A variety of non-invasive precursor lesions of pancreatic adenocarcinoma have been identified, which provide a unique opportunity for intervention prior to onset of invasive cancer. Biomarker discovery in precursor lesions has been hampered by the ready availability of fresh specimens, and limited yields of nucleic acids or proteins suitable for large scale screening.
Design: Therefore, we decided to use the Liquid Tissue, a novel technique for protein extraction from archival formalin-fixed material, in order to perform global proteomic analysis of an intraductal papillary mucinous neoplasm (IPMN), a non-invasive pancreatic cancer precursor. Approximately, 30,000 epithelial cells were collected from an archival IPMN by manual microdissection, and a soluble Liquid Tissue lysate representative of the total protein complement was prepared. 500ng of the protein extract was analyzed by High resolution liquid chromatography and tandem mass spectrometry (LC-MS/MS). In addition, tissue microarrays (TMAs) comprised of 35 archival IPMNs was used for validation of candidate markers by immunohistochemistry.
Results: The LC-MS/MS of the IPMN Liquid Tissue lysate resulted in the identification of 3545 peptides corresponding to 399 unique proteins (range of 1 to 16 peptides for each protein). Manual curation established that a subset of proteins expressed in the non-invasive IPMN had been reported as upregulated in invasive pancreatic cancer by previous mRNA and protein expression profiling studies. From this list, we decided to perform immunohistochemical labeling for two of the proteins in this enriched pancreatic cancer-associated subset - Deleted in Malignant Brain Tumors (DMBT1) and Tissue Transglutaminase (TG2) - confirmed their overexpression in archival IPMN tissues.
Conclusions: Global proteomics analysis using Liquid Tissue reagents and LC-MS/MS is a feasible approach for unbiased biomarker discovery (forward proteomics) in limited archival material, particularly applicable to precursor lesions of cancer.
Category: Gastrointestinal

Monday, March 3, 2008

Poster # 87, Monday Morning