Proteomic Profiling of Pancreatic Cancer: Validation of a Neuronal Signature.
David Rundell, Christopher Thompson, Shaiju Vareed, Vadiraja B Bhat, Vihas Vasu, Mohsen Shabahang, James McLoughlin, Arun Sreekumar, Arundhati Rao. Scott & White Hospital, Temple, TX; Medical College of Georgia, Augusta; Agilent Technologies, Wilmington, DE
Background: Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer death in the United States with a 5 year survival rate of 4%. Biomarkers that are detectable early in the course of disease have the potential to markedly improve clinical outcomes.
Design: We profiled the secretory proteome of pancreatic duct fluid in 25 samples (18 carcinomas and 7 benign) using a MudPIT approach with HPLC-Chip nano ESI-MS/MS analysis. A total of 433 proteins were detected of which 56 were found to be significantly elevated in PDAC. Alpha Synuclein (SNCA) was in this differential set and was further investigated as potential marker.
SNCA expression was correlated to tissue expression by immunoblot and immunohistochemistry. Tissue microarrays (TMA) from 76 PDAC, 9 pancreas mucinous cystadenomas, 17 intraductal papillary mucinous neoplasms (IPMN), 6 intraductal papillary mucinous carcinomas (IPM) with and without invasion, 45 benign pancreatitis cases and 44 carcinomas from other sites were examined. SNCA staining was scored as the sum of the intensity (0-3+) and extent (0-4+). Positive staining was defined to be a total score of 5 or greater. Additionally tumors were stained with HMB-45 and Fontana-Masson to investigate neurological differentiation in SNCA positive PDAC.
Results: Immunoblot analysis confirmed elevated levels of SNCA in tissues from pancreatic adenocarcinoma patients compared to controls. Weak to no staining was noted for SNCA in a vast majority (∼95 %) of the pancreatitis specimens (n=28) while approximately 83% of the PDAC specimens (n=76) exhibited a positive staining pattern. No neuronal differentiation was identified in the SNCA positive cases. There was positive staining in 13 of the IPMN and IPM carcinomas and all of the mucinous cystic neoplasms. Positive staining was noted in a majority of the colon (5 of 6), gastric (5 of 6) and lung adenocarcinomas (6 of 6). No staining was noted in hepatocellular and urothelial carcinomas and only a minority of breast ductal carcinomas (2 of 6) showed positive staining for SNCA.
Conclusions: Synuclein A is overexpressed in pancreatic duct fluid and tissues derived from patients with pancreatic adenocarcinoma and pancreatic mucinous tumors indicating that this protein may be involved in the dysregulated growth of pancreatic neoplasms. Mechanistic understanding the role of SNCA in PDAC, GI and lung adenocarcinomas may reveal prognostically relevant pathways.
Category: Special Category - Pan-genomic/Pan-proteomic approaches to Cancer
Tuesday, March 1, 2011 8:15 AM
Platform Session: Section H 1, Tuesday Morning