TY - JOUR A1 - Bartel, Karin A1 - Pein, Helmut A1 - Popper, Bastian A1 - Schmitt, Sabine A1 - Janaki-Raman, Sudha A1 - Schulze, Almut A1 - Lengauer, Florian A1 - Koeberle, Andreas A1 - Werz, Oliver A1 - Zischka, Hans A1 - Müller, Rolf A1 - Vollmar, Angelika M. A1 - Schwarzenberg, Karin von T1 - Connecting lysosomes and mitochondria – a novel role for lipid metabolism in cancer cell death JF - Cell Communication and Signaling N2 - Background The understanding of lysosomes has been expanded in recent research way beyond their view as cellular trash can. Lysosomes are pivotal in regulating metabolism, endocytosis and autophagy and are implicated in cancer. Recently it was discovered that the lysosomal V-ATPase, which is known to induce apoptosis, interferes with lipid metabolism in cancer, yet the interplay between these organelles is poorly understood. Methods LC-MS/MS analysis was performed to investigate lipid distribution in cells. Cell survival and signaling pathways were analyzed by means of cell biological methods (qPCR, Western Blot, flow cytometry, CellTiter-Blue). Mitochondrial structure was analyzed by confocal imaging and electron microscopy, their function was determined by flow cytometry and seahorse measurements. Results Our data reveal that interfering with lysosomal function changes composition and subcellular localization of triacylglycerids accompanied by an upregulation of PGC1α and PPARα expression, master regulators of energy and lipid metabolism. Furthermore, cardiolipin content is reduced driving mitochondria into fission, accompanied by a loss of membrane potential and reduction in oxidative capacity, which leads to a deregulation in cellular ROS and induction of mitochondria-driven apoptosis. Additionally, cells undergo a metabolic shift to glutamine dependency, correlated with the fission phenotype and sensitivity to lysosomal inhibition, most prominent in Ras mutated cells. Conclusion This study sheds mechanistic light on a largely uninvestigated triangle between lysosomes, lipid metabolism and mitochondrial function. Insight into this organelle crosstalk increases our understanding of mitochondria-driven cell death. Our findings furthermore provide a first hint on a connection of Ras pathway mutations and sensitivity towards lysosomal inhibitors. KW - lysosome KW - V-ATPase KW - mitochondria KW - fission KW - apoptosis KW - lipid metabolism KW - cardiolipin Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-221524 VL - 17 ER - TY - JOUR A1 - Oelschlaegel, Diana A1 - Weiss Sadan, Tommy A1 - Salpeter, Seth A1 - Krug, Sebastian A1 - Blum, Galia A1 - Schmitz, Werner A1 - Schulze, Almut A1 - Michl, Patrick T1 - Cathepsin inhibition modulates metabolism and polarization of tumor-associated macrophages JF - Cancers N2 - Stroma-infiltrating immune cells, such as tumor-associated macrophages (TAM), play an important role in regulating tumor progression and chemoresistance. These effects are mostly conveyed by secreted mediators, among them several cathepsin proteases. In addition, increasing evidence suggests that stroma-infiltrating immune cells are able to induce profound metabolic changes within the tumor microenvironment. In this study, we aimed to characterize the impact of cathepsins in maintaining the TAM phenotype in more detail. For this purpose, we investigated the molecular effects of pharmacological cathepsin inhibition on the viability and polarization of human primary macrophages as well as its metabolic consequences. Pharmacological inhibition of cathepsins B, L, and S using a novel inhibitor, GB111-NH\(_2\), led to changes in cellular recycling processes characterized by an increased expression of autophagy- and lysosome-associated marker genes and reduced adenosine triphosphate (ATP) content. Decreased cathepsin activity in primary macrophages further led to distinct changes in fatty acid metabolites associated with increased expression of key modulators of fatty acid metabolism, such as fatty acid synthase (FASN) and acid ceramidase (ASAH1). The altered fatty acid profile was associated with an increased synthesis of the pro-inflammatory prostaglandin PGE\(_2\), which correlated with the upregulation of numerous NF\(_k\)B-dependent pro-inflammatory mediators, including interleukin-1 (IL-1), interleukin-6 (IL-6), C-C motif chemokine ligand 2 (CCL2), and tumor necrosis factor-alpha (TNFα). Our data indicate a novel link between cathepsin activity and metabolic reprogramming in macrophages, demonstrated by a profound impact on autophagy and fatty acid metabolism, which facilitates a pro-inflammatory micromilieu generally associated with enhanced tumor elimination. These results provide a strong rationale for therapeutic cathepsin inhibition to overcome the tumor-promoting effects of the immune-evasive tumor micromilieu. KW - cathepsin KW - activity-based probes KW - tumor-associated macrophage KW - autophagy KW - lysosome KW - lipid metabolism KW - inflammation Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-213040 SN - 2072-6694 VL - 12 IS - 9 ER - TY - THES A1 - Finkl, Sophia T1 - Untersuchungen zur Funktion und Expression von miR-200b im Prostatakarzinom unter besonderer Beachtung von miR-200b als Prognosemarker bei Hochrisiko-Erkrankten und des Enzyms SOAT1 als Zielstruktur von miR-200b T1 - Studies on the function and expression of miR-200b in prostate carcinoma with special attention to miR-200b as a prognostic marker in high-risk disease patients and the enzyme SOAT1 as a target of miR-200b N2 - Die miR-200b zeigte sich in zwei unabhängigen Prostatakarzinomkollektiven herabreguliert und in dem verwendeten Hochrisiko Kollektiv erwies sich miR-200b zudem in uni- und multivariaten Analysen in einem retrospektiven Versuchsansatz als geeigneter Marker zur Abschätzung der Prognose des Prostatakarzinoms. Mittels in vitro Experimenten konnten tumorsuppressive Funktionen von miR-200b bestätigt werden, da miR-200b überexprimierende Prostatakarzinom Zelllinien eine geringere Proliferation und eine geringere Autophagie zeigten. Zusätzlich konnte auf funktioneller Ebene, SOAT1 als Zielgen von miR-200b definiert werden. Die funktionelle Bedeutung der miR-200b vermittelten Regulation der SOAT1 Expression konnte in weiteren Experimenten bestätigt werden, indem eine Sensitivierung gegenüber der antiproliferativen Wirkung von SOAT1 Inhibitoren in miR-200b überexprimierenden Prostatakarzinom-Zellen beobachtet werden konnte. Mit diesen Ergebnissen konnte ein Model entwickelt werden, welches einen möglichen Erklärungsansatz der Bedeutung, der von miR-200b vermittelten SOAT1 Regulation für den Fettstoffwechsel des Prostatakarzinoms liefern könnte. N2 - The miR-200b was shown to be downregulated in two independent prostate cancer collectives and in the high-risk collective, miR-200b was also found to be a suitable marker to estimate the prognosis of prostate cancer in univariate and multivariate analyses in a retrospective experimental approach. Using in vitro experiments, tumor suppressive functions of miR-200b could be confirmed, as miR-200b overexpressing prostate carcinoma cell lines showed lower proliferation and autophagy. In addition, at the functional level, SOAT1 could be defined as a target gene of miR-200b. The functional significance of miR-200b mediated regulation of SOAT1 expression was confirmed in further experiments by observing sensitivity to the antiproliferative effect of SOAT1 inhibitors in miR-200b overexpressing prostate carcinoma cells. With these results, a model could be developed that could provide a possible explanation of the importance of SOAT1 regulation mediated by miR-200b for lipid metabolism in prostate carcinoma. KW - Prostatakrebs KW - Prostatakarzinom KW - miR-200b KW - SOAT1 KW - prostate cancer KW - lipid metabolism Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-257418 ER -