The long-term goal of this project is to provide a basis for the development of novel intervention strategies for the most common type of pancreatic cancer, ductal adenocarcinoma. This cancer has a mortality of near 100% because diagnostic markers to identify the disease at an early stage are not available. We have combined the two risk factors for this cancer, smoking and drinking, by exposing hamsters in utero to the tobacco-carcinogen NNK and ethanol, resulting in the development of pancreatic ductal adenocarcinoma. Inhibitors of arachidonic acid (AA) metabolism reduced the pancreatic cancer incidence up to 50% while a beta-blocker reduced the cancer incidence to zero. In accord with these findings, the growth of cell lines derived from human pancreatic adenocarcinomas and immortalized normal human pancreatic duct epithelia were under beta-adrenergic control via the release of AA. Based on these novel findings, we propose three specific aims.
Aim 1 will test the hypothesis that dietary n-3-polyunsaturated fatty acids (n-3-PUFAs) inhibit pancreatic carcinogenesis via reduction of tissue AA content and eicosanoid formation. This hypothesis will be tested in a bioassay in our hamster model, consisting of four dietary groups after completion of the tumor induction period (positive control, AA, n-3-PUFA, eicosapentaenoic acid EPA, AA+EPA). Pancreatic and liver tissues will be analyzed for fatty acids, AA-metabolites, AA-metabolizing enzymes and presence of pancreatic cancer. Data generated by this study will provide important information for dietary prevention of pancreatic cancer.
Aim 2 will determine the downstream mitogenic signals activated by beta-adrenergic stimulation in cell lines from normal human pancreatic duct epithelia, pancreatic adenocarcinomas and will assess how these pathways are modulated by chronic exposure to NNK and ethanol. To achieve this goal, expression and activation levels of beta-adrenergic signaling components that have been described in other cell types will be assessed in the presence and absence of specific stimulators and inhibitors. Data generated will provide a basis for novel pharmacologic and molecular pancreatic cancer intervention strategies.
Aim 3 will study the pathogenesis of pancreatic ductal adenocarcinoma in our hamster model by histopathology and identify early markers of the disease by molecular analysis of pancreatic duct cells, pancreatic islet cells and pancreatic acinar cells harvested at various stages during tumor development by laser capture microscopy. Data generated by these studies will help identify early markers of pancreatic cancer development that provide a basis for the early detection of this deadly malignancy. ? ?
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