Aberrant Expression of Mucin Core Proteins and O-Linked Glycans Associated with Progression of Pancreatic Cancer

Abstract

Purpose Mucin expression is a common feature of most adenocarcinomas and features prominently in current attempts to improve diagnosis and therapy of pancreatic cancer and other adenocarcinomas. We investigated the expression of a number of mucin core proteins and associated O-linked glycans expressed in pancreatic adenocarcinoma (PA) – sialyl Tn (STn), Tn, T antigen, sialyl Lewis A (CA19-9), sialyl Lewis C (SLeC), Lewis X (LeX) and sialyl Lewis X (SLeX) – during the progression of pancreatic cancer from early stages to metastatic disease. Experimental Design Immunohistochemical analyses of mucin and associated glycan expression on primary tumor and liver metastatic tumor samples were performed with matched sets of tissues from 40 autopsy patients diagnosed with PA, 14 surgically resected tissue samples, and 8 normal pancreata. Results There were significant changes in mucin expression patterns throughout disease progression. MUC1 and MUC4 were differentially glycosylated as the disease progressed from early PanINs to metastatic disease. De novo expression of several mucins correlated with increased metastasis indicating a potentially more invasive phenotype, and we demonstrate the expression of MUC6 in acinar cells undergoing acinar to ductal metaplasia. A “cancer field-effect” that included changes in mucin protein expression and glycosylation in the adjacent normal pancreas was also seen. Conclusions There are significant alterations in mucin expression and post-translational processing during progression of pancreatic cancer from early lesions to metastasis. The results are presented in the context of how mucins influence the biology of tumor cells and their microenvironment during progression of pancreatic cancer.

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