Funktionelle Charakterisierung der zellulären Rolle des Kandidatengens Valosin containing protein im Pankreaskarzinom

Pancreatic ductal adenocarcinoma still has an extremely poor prognosis. The 5-year survival rate is around 9 %. The disease is often diagnosed in advanced stages, because in many cases there are no early symptoms and PDAC metastasizes early. Yet also cases which are diagnosed in early stages and thus are primarily resectable, show high mortality rates. One of the reasons for this aggressive behavior is its high resistance against chemotherapy. Therefore, within the last years researchers tried to identify cellular structures, which could be targeted by new antineoplastic agents. A potential structure is the protein “Valosin-containing protein” (VCP), which could be identified in an shRNA-based screening in a former dissertation of the AG Buchholz. A central role of VCP in proteasomal degradation, its overexpression in various tumor entities and its association with dismal prognosis were shown in several prior publications. In this dissertation a statistically significant increased expression of VCP in tissue samples of PDAC compared to samples of healthy pancreatic tissue and chronic pancreatitis could be shown. It could be shown that all three used siRNAs led to a sufficient knockdown of VCP-mRNA in various PDAC-cell lines. MTT- and BrdU-assays were used to determine whether this knockdown had influence on the viability and proliferation of the tumor cells. In all three used cell lines a statistically significant decrease of cell viability and cell proliferation could be detected, when cells were transfected with siRNA1 and siRNA3. Apoptosis as a reason of reduced cell viability could be excluded by performing western blots. With the help of Western Blots, a remarkable upregulation of the cell cycle protein p21 and a downregulation of Cyclin D1 could be demonstrated in these cell populations, which showed reduced cell proliferation. It was noticeable, that the functional assays could not detect any effect on cell viability or cell proliferation when the cells had been transfected with siRNA2. Off-target-effects were discussed as one possible reason. Finally, with the reduction of cell viability and cell proliferation this thesis showed two potential ways, how the downregulation of VCP could mediate antitumoral effects. The identification of the exact mocluar mechanisms is part of future experiments and analyses.