Abstract (eng)
Ovarian cancer is the number one cause of death within the group of gynecological cancers. Due to a wide variety of molecular characteristics ovarian cancer is a very heterogenous disease whit a lot of challenges in treatment. Even tough cisplatin is one of the most potential drugs used in ovarian cancer treatment, the late onset of therapy and evolving resistance within the tumor often results in poor prognosis for the patient. Since the ovary is surrounded by a very motile environment within the abdomen, physical forces play a central role in the tumor microenvironment. Extracellular mechanical stimulation is translated through the mechanotransducing apparatus (cytoskeleton, mechanical gated ion channels, mechanosensitive proteins) to appropriate cellular responses via altering protein localization and/or affecting multiple intracellular signaling pathways. The main goal of this thesis was to investigate the effects of physical stressors, especially shear stress, on ovarian cancer cells. Experiments were carried out using the epithelial non-serous SKOV3 and high-grade serous OVCAR3 ovarian cancer cell lines. First, the effect of shear stress on cytotoxicity of cisplatin was evaluated. The results of cisplatin treatment showed some significant differences between static and shear stress-exposed cells in the SKOV3 cell line, but not in OVCAR3 cell line. Secondly, to explore the intracellular pathways activated through shear stress, immunofluorescence was performed. As first, morphological features like nuclear area and actin cytoskeleton were assessed. Furthermore, the analysis was deepened on structural proteins like Caveolin-1, the mechano-gated ion channel Piezo1, as well as on mechanosensitive transcription factors and related proteins (YAP1, Ajuba, Nrf2). Lastly, a variety of posttranslational modifications like farnesylation, acetylation and phosphorylation was evaluated in order to identify possible regulatory events. Taken together, our data showed significant differences between the two cell lines with regard to shear stress-induced cellular responses. Generally, OVCAR3 cells responded faster than SKOV3 cells, with morphometric rearrangement of the nucleus after 3h of incubation and YAP1 translocation. However, no effect could be seen in the cisplatin treatment. SKOV3 on the other hand sustained Nrf2 nuclear translocation after shear stress, which could be the main factor in modulated cytotoxicity of cisplatin in SKOV3 after shear stress exposure. Summarizing the results, multiple responses to shear stress might be involved in the pathophysiology of ovarian cancer and more experiments are needed to elucidate the pathways to further understand the heterogeneity of this lethal disease.