Immunohistochemical Validation of Proteomic Analysis in Pancreatic Ductal Dysplasia (PanIN)
JF Coleman, R Chen, TA Brentnall, MP Bronner. Cleveland Clinic Foundation, Cleveland, OH; University of Washington, Seattle, WA
Background: Pancreatic ductal adenocarcinoma is an insidious disease, often diagnosed at a late stage and with an almost uniformly and rapidly fatal prognosis. Methods of early detection hold promise for improved outcomes, but more reliable biomarkers of early tumorigenesis are needed. Interrogation of the pancreatic ductal neoplasia proteome offers a promising approach for biomarker discovery.
Design: Using an isotope-coded affinity tagging (ICAT) proteomics strategy, the differential expression of peptides between dysplastic ductal tissue and normal pancreatic tissue was determined. Annexin V and laminin were selected for morphologic validation. Tissue microarrays and standard immunohistochemistry were used to semiquantitatively characterize these markers in 73 surgically-resected pancreatic adenocarcinomas and 40 non-neoplastic pancreatic controls. Carcinoma, dysplasia, normal ducts, and their surrounding stroma were graded for the intensity of immunohistochemical staining (0-3), as well as the approximate percentage of positive cells (25%, 50%, 75%, 100%). A cumulative score for each tissue was calculated as the mean of the product of the intensity and percentage grades. The score distributions of adenocarcinoma, high-grade dysplasia (PanIN III), low-grade dysplasia (PanIN II) and their associated stroma were compared with normal controls by chi-square testing.
Results: Annexin V immunohistochemical staining of normal control ductal epithelium (mean 2.58) was significantly higher than low-grade dysplasia (2.43, p=0.04), high-grade dysplasia (2.0, p<0.01), and adenocarcinoma (2.23, p=0.04). Laminin staining of the normal control periductal stroma (mean 1.03) was significantly decreased relative to adenocarcinoma (1.92, p<0.01), high-grade dysplasia (1.96, p<0.01), and low-grade dysplasia (1.9, p<0.01).
Conclusions: ICAT-based proteomic strategies continue to yield biomarkers of interest for pancreatic ductal neoplasia, as confirmed by this immunohistochemical validation of annexin V and laminin.
Category: Liver & Pancreas
Monday, March 9, 2009 9:30 AM
Poster Session I Stowell-Orbison/Autopsy Award # 205, Monday Morning