Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Rauter, T.
Investigating the Stress-Resistance of the Cancer Cell Secretory Pathway
PhD-Studium (Doctor of Philosophy); Humanmedizin; [ Dissertation ] Graz Medical University; 2021. pp. 123
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- Autor*innen der Med Uni Graz:
- Betreuer*innen:
- Graier Wolfgang
- Malli Roland
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- Abstract:
- Secretory proteins are a large and important part of the human proteome. They are either membrane-associated or soluble proteins and most of them first target the endoplasmic reticulum (ER) to enter the classical secretory pathway. Cargo proteins start their journey through this pathway from the ER to the Golgi via vesicular structures, representing the initial step in this process. Modern, high-resolution imaging techniques in combination with innovative genetically encoded, fluorescent protein (FP)-based tools allow the synchronization and real-time visualization of such trafficking events. It has been shown that many tumor cells rely heavily on protein secretion to maintain cancer-specific hallmarks like high growth and proliferation rates and also enable metastasis. Despite this knowledge about the role of the secretory pathway in cancer cells, not a lot is known about its general energy supply and specifically its resistance to stress. In this thesis, we applied state-of-the-art techniques to allow a closer look into the complex interrelation between metabolic activity and early secretory trafficking events in cancer cells as well as test the sensitivity of ER-to-Golgi transport to energy and Ca2+ stresses. The experiments revealed a yet unseen stability of secretory transport under significant energy stress by nutrient starvation, mimicking a situation tumor cells might encounter during their life. Surprisingly, the cancer cell model also displayed high efficiency in ER-to-Golgi trafficking upon short-term Ca2+ stress induction. However, treatment with the antimetabolite 2-deoxy-D-glucose (2-DG) effectively and almost completely abolished secretory transport of luminal and transmembrane cargo constructs, underlining the importance of the glycolysis-based energy supply to maintain effective protein trafficking in cells exhibiting the Warburg effect. We further demonstrated the impact of 2-DG on the cellular Ca2+ homeostasis and the motility of vesicular structures within cells. Furthermore, the structural integrity of ER and the microtubule network, as a crucial mediator of directed, long-distance intracellular transport, were investigated under severe energy stress. In an attempt to complement high-resolution fluorescence imaging methods, a novel genetically-encoded sensor based on new FP-technologies was introduced opening up new possibilities. By applying innovative methodical approaches we demonstrated a high stress-resistance of the secretory pathway in the cancer cell model. These new insights into ER-to-Golgi transport efficiency under energy and Ca2+ stress also emphasize the importance of the secretory pathway as a potential target in future cancer therapy.