Porcine pancreatic ductal epithelial cells transformed with KRASG12D and SV40T are tumorigenic.

We describe our initial studies in the development of an orthotopic, genetically defined, large animal model of pancreatic cancer. Primary pancreatic epithelial cells were isolated from pancreatic duct of domestic pigs. A transformed cell line was generated from these primary cells with oncogenic KRAS and SV40T. The transformed cell lines outperformed the primary and SV40T immortalized cells in terms of proliferation, population doubling time, soft agar growth, transwell migration and invasion. The transformed cell line grew tumors when injected subcutaneously in nude mice, forming glandular structures and staining for epithelial markers. Future work will include implantation studies of these tumorigenic porcine pancreatic cell lines into the pancreas of allogeneic and autologous pigs. The resultant large animal model of pancreatic cancer could be utilized for preclinical research on diagnostic, interventional, and therapeutic technologies.

Role of keratan sulfate expression in human pancreatic cancer malignancy.

Keratan sulfate (KS) is a sulfated linear polymer of N-acetyllactosamine. Proteoglycans carrying keratan sulfate epitopes were majorly observed in cornea, cartilage and brain; and mainly involved in embryonic development, cornea transparency, and wound healing process. Recently, expression of KS in cancer has been shown to be highly associated with advanced tumor grade and poor prognosis. Therefore, we aimed to identify the expression of KS epitope in human pancreatic cancer primary and metastatic tumor lesions. Immunohistochemical analysis of KS expression was performed on primary pancreatic tumors and metastatic tissues. We observed an increased expression of KS epitope on primary tumor tissues compared to uninvolved normal and tumor stroma; and is associated with worse overall survival. Moreover, lung metastatic tumors show a higher-level expression of KS compared to primary tumors. Interestingly, KS biosynthesis specific glycosyltransferases expression was differentially regulated in metastatic pancreatic tumors. Taken together, these results indicate that aberrant expression of KS is predictive of pancreatic cancer progression and metastasis and may serve as a novel prognostic biomarker for pancreatic cancer.

Loss of E-cadherin and epithelial to mesenchymal transition is not required for cell motility in tissues or for metastasis.

Loss of E-cadherin has been long considered to be a major hallmark of epithelial-mesenchymal transition (EMT) and has been reported in various cancers. P120 catenin regulates E-cadherin stability on the cell surface and also plays a role in intracellular signaling by modulating nuclear transcription. We recently characterized the nature of interactions between p120 catenin and Mucin 1 (MUC1) in pancreatic cancer. Expression of different p120 catenin isoforms with and without MUC1 induced distinct morphologies, cell adhesion, and dynamic properties of motility along with different metastatic properties in vivo. Re-expression of p120 catenin isoform 3A in the context of MUC1 expression in a p120 catenin-deficient cell line stabilized expression of E-cadherin. However, orthotopic implantation of tumors using this stable cell line produced large metastatic lesions to the liver, which exceeded the volume of the primary tumor, suggesting down regulation of E-cadherin is not required for tumor metastasis. Here we extend those studies by showing that ectopic expression of E-cadherin does not block in vitro invasion of the pancreatic cancer cells, and instead accelerated the rate of tumor invasion. Furthermore, results from 23 cases of human pancreatic primary tumor specimens revealed that most tumors exhibiting metastatic activity retained epithelial morphology and E-cadherin gene expression. Our results indicate that loss of E-cadherin and EMT are not required for metastasis and that an epithelial morphology can be maintained during the process of tumor cell movement.

Aberrant expression of mucin core proteins and o-linked glycans associated with progression of pancreatic cancer.

PURPOSE: Mucin expression is a common feature of most adenocarcinomas and features prominently in current attempts to improve diagnosis and therapy for 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-sialyl Tn (STn), Tn, T antigen, sialyl Lewis A (CA19-9), sialyl Lewis C (SLeC), Lewis X (LeX), and sialyl LeX (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 conducted with matched sets of tissues from 40 autopsy patients diagnosed with pancreatic adenocarcinoma, 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 pancreatic intraepithelial neoplasias to metastatic disease. De novo expression of several mucins correlated with increased metastasis indicating a potentially more invasive phenotype, and we show 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 posttranslational 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.

Molecular pathology of early pancreatic cancer.

We describe the pathology of early pancreatic cancer and present an overview of known molecular alterations that occur in these lesions. There are three defined precursor lesions in current models of pancreatic cancer: pancreatic intraepithelial neoplasia (PanIN), mucinous cystic neoplasms (MCN), and intraductal papillary mucinous neoplasms (IPMN). Molecular alterations detected in these lesions include: telomeres, K-ras and downstream targets, p16/CDKN2A, p53, SMAD4/DPC4, microRNAs, mucins and their post-translational processing, inflammatory cytokines, CEACAM, and epigenetic alterations. We summarize previous analyses of these markers as diagnostic markers of disease, and suggest areas of future study.