S100A4 spielt eine zentrale Rolle für die Metastasierung des Dickdarmkrebses. Die Hemmung der S100A4 Expression stellt damit einen vielversprechenden therapeutischen Ansatz dar. Die vorliegende Arbeit präsentiert Niklosamid und Calcimycin als neue Inhibitoren der S100A4 Transkription. In Kolonkarzinomzellen, die mit einem der beiden Inhibitoren behandelt wurden, wurde die S100A4 Expression konzentrations- und zeitabhängig unterdrückt. Des Weiteren war die Zellmigration und -invasion in Abhängigkeit von S100A4 in behandelten Zellen vermindert. Niklosamid und Calcimycin Behandlung verhinderten die Zellproliferation und die Koloniebildung von Kolonkarzinomzellen. Beide Inhibitoren hemmten den konstitutiv aktiven Wnt Pathway von Kolonkarzinomzellen. Calcimycin Behandlung verminderte die Expression von beta-catenin. Niklosamid hemmte die Bildung des beta-catenin/TCF Komplexes und unterband damit die Expression von Wnt Pathway Genen, wie z.B. S100A4. Im Rahmen dieser Arbeit wurde ein in vivo Tiermodell entwickelt, mit dem die S100A4-induzierte Metastasierung mit Hilfe von nicht-invasivem Biolumineszenz Imaging visualisiert werden konnte. In diesem Model konnte gezeigt werden, dass Niklosamid signifikant die S100A4 Expression im Tumor vermindert und damit die Metastasierung hemmt. Des Weiteren zeigt diese Arbeit, dass S100A4 die Expression des Wnt Pathway Antagonisten DKK-1 in Kolonkarzinomzellen hemmt. DKK-1 selbst konnte als endogener Inhibitor der S100A4 Expression identifiziert werden. Zusammenfassend beschreibt die vorliegende Arbeit einen neuen regulativen Mechanismus im Wnt Pathway, der die S100A4 Expression im Kolonkarzinom fördert. Diese Beobachtung verdeutlicht die Notwendigkeit für wirksame S100A4 Inhibitoren, wie Niklosamid und Calcimycin, die das Potenzial haben, in einer klinischen Anwendung die Metastasierung von Kolonkarzinompatienten mit erhöhter S100A4 Expression zu hemmen und damit deren Überlebenschance wesentlich zu verbessern. / S100A4 promotes metastasis in colon cancer patients thereby reducing their five-year survival chances to less than 10%. Consequently, inhibition of S100A4 expression is a promising strategy for anti-metastatic treatment of colon cancer patients. The present study characterizes the small molecules niclosamide and calcimycin as transcriptional inhibitors of S100A4 which reduced S100A4 expression concentration- and time-dependently. Niclosamide and calcimycin treatment restricted cell migration, invasion and wound healing capabilities in a S100A4-specific manner, and inhibited cell proliferation and colony formation of colon cancer cells. Both small molecule inhibitors interfere with the constitutively active Wnt pathway. Targeting β-catenin expression by calcimycin or interfering with the β-catenin/TCF transcription activating complex by niclosamide resulted in reduced Wnt target gene transcription, among them S100A4. The study further presents a human colon cancer xenograft mouse model for monitoring S100A4-induced metastasis formation via non-invasive bioluminescence imaging. Treatment of xenograft mice with niclosamide resulted in a significant reduction of the S100A4 mRNA level in the tumor accompanied by inhibition of metastasis formation. Moreover, this study presents evidence that S100A4 is an inhibitor of DKK-1 expression. In colon cancer cells DKK-1 and S100A4 expression was negatively correlated. Ectopic S100A4 overexpression inhibited DKK-1 expression. Targeting S100A4 via shRNA recovered the repressed DKK-1 expression and vice versa. In summary, the study describes a novel positive feedback loop in the Wnt pathway regulation formed by S100A4 repressing its antagonist DKK-1. This novel mechanism further strengthens the need for S100A4 inhibitors such as niclosamide or calcimycin. Consequently, such small molecules provide immense potential for the treatment of colon cancer patients who are at high risk for S100A4-induced colon cancer metastasis.

This work was focused on the preparation of model stabilized phospholipid membranes formed on porous polycarbonate carrier. 1,2-dipalmitoyl-sn-glycero-3-phosphocholin was used for their formation in hydrophilic pores of polycarbonate carrier. For characterization of the formation of phospholipid layers, their changes and a study of transport processes, electrochemical impedance spectroscopy and voltammetry were used. Transport of cadmium and copper ions was studied in the presence and in the absence of ionophore calcimycin which was incorporated into the formed of phospholipid membrane. Because these ions are often bound in complexes with various substances, such as low molecular weight organic acids (LMWOAs), this work was also focused on the transport of copper and cadmium ions across the model phospholipid membranes in the presence of malic acid, citric acid and oxalic acid at different pH. Besides the use of ionophore, some pilot experiments were performed to realize the transfer of copper ions using two peptides, nisin and transportan 10. Formation of phospholipid membranes and the transport processes were characterized by two proposed electric equivalent circuits which correspond to the covered and to the uncovered polycarbobate carrier. Keywords: Phospholipids, Membranes, Ionophore, Peptid....