Search

\(\textbf{Background:}\) Pancreatic cancer development is associated with characteristic alterations like desmoplastic reaction and immune escape which are mediated by the cell-cell communication mechanism and by the microenvironment of the cells. The whole of released components are important determinants in these processes. Especially the extracellular vesicles released by pancreatic cancer cells play a role in cell communication and modulate cell growth and immune responses. \(\textbf{Results:}\) Here, we present the proteomic description of affinity purified extracellular vesicles from pancreatic tumour cells, compared to the secretome, defined as the whole of the proteins released by pancreatic cancer cells. The proteomic data provide comprehensive catalogues of hundreds of proteins, and the comparison reveals a special proteomic composition of pancreatic cancer cell derived extracellular vesicles. The functional analysis of the protein composition displayed that membrane proteins, glycoproteins, small GTP binding proteins and a further, heterogeneous group of proteins are enriched in vesicles, whereas proteins derived from proteasomes and ribosomes, as well as metabolic enzymes, are not components of the vesicles. Furthermore proteins playing a role in carcinogenesis and modulators of the extracellular matrix (ECM) or cell-cell interactions are components of affinity purified extracellular vesicles. \(\textbf{Conclusion:}\) The data deepen the knowledge of extracellular vesicle composition by hundreds of proteins that have not been previously described as vesicle components released by pancreatic cancer cells. Extracellular vesicles derived from pancreatic cancer cells show common proteins shared with other vesicles as well as cell type specific proteins indicating biomarker candidates and suggesting functional roles in cancer cell stroma interactions.

In dieser Arbeit wurden Interaktionspartneranalysen des darmspezifischen Cadherin-17 und Analysen zum Mechanismus des Ektodomänen-Sheddings des Fat1-Cadherins, sowie dessen Verwendbarkeit als Tumorbiomarker für das Pankreaskarzinom untersucht. Mit Hilfe von Co-Immunopräzipitation Cadherin-17 positiver Proteinkomplexe und anschließender massenspektrometrischer Analyse dieser, wurden vier Kataloge mit über 800 Proteinen erstellt. Exemplarisch wurden die Proteine pIgR und Keratin8 als mögliche Interaktionspartner getestet. Beide Proteine interagieren nicht. Am Fat1-Ektodomänen-Shedding sind die Proteasen ADAM9, ADAM10 und PCSK5 beteiligt und alle Proteine zeigen eine erhöhte Expression in Pankreastumoren. Lösliches Fat1 konnte erstmals im Serum von Pankreaskarzinompatienten gezeigt und mit einem, in Kooperation entwickelten Sandwich-ELISA, sensitiv nachgewiesen werden. Nur wenige Patienten zeigten einen erhöhten Fat1-Spiegel, die meisten davon aber einen geringen Spiegel für CA19-9. In this thesis analysis of possible interaction partners of the intestine specific cadherin Cadherin-17 as well as analysis of the mechanism of the cadherin Fat1 ectodomain and its possible usability as a novel biomarker for pancreatic cancer were analyzed. Four protein catalogues with over 800 proteins were generated using co-immunoprecipitation and a possible interaction between Cadherin-17 and the proteins pIgR and keratin8 were tested. Unfortunately the proteins do not interact. The ectodomain of the giant cadherin fat1 is shed by the proteases ADAM9, ADAM10 and PCSK5 and all those proteins show an increased expression in pancreatic cancer. A sensitive Sandwich-ELISA was established to detect soluble fat1 in sera through a cooperation. Fat1 could be used as a panel marker with CA19-9 for the patients with the highest Fat1-level showed diminished CA19-9-levels.