Figure 2-1 - uploaded by Franziska Lautenschlaeger
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Schematic of a cell and its components. Cells are highly complex, densely packed structures, which are considered as the smallest unit of life. Picture copyright by 2003 Pearson Education (http://www.biologyjunction.com/cell_model_instructions.htm).
Source publication
This thesis was released from embargo in July 2012
Citations
... Transwell Migration Assay(Lautenschlaeger 2011) ...
Alteration in glycosylation pattern is one of the hallmarks of breast cancer. The levels and the abnormal expressions of glycan were found in breast cancer patients. Glycosylation defect can affect different glycosylated proteins which are implicated in cancerogenesis. Changes in intracellular Ca2+ levels can regulate different cellular processes. SOC channels are implicated in breast cancer proliferation, migration and survival. CO-OCS is a new glycosylation inhibitor with more selectivity toward theα- glucosidases exhibited anti-cancer activities in breast cancer cells without affecting the normal mammary cells. The objective of my thesis is investigating the related molecular mechanisms by which CO-OCS induced its anti-tumour effects.CO-OCS impaired breast cancer migration through decrease β1-integrin expression and the activation of FAK and ERK1/2 signalling pathways. CO-OCS also induced anti-migratory effect via Stim1 protein expression down-regulation leading to inhibition of SOCE. Additionally, CO-OCS affected the expression of both Orai1 and Stim1 proteins leading to anti-proliferative effects and cell cycle arrest in G1 and G2/M phase respectively. Moreover, CO-OCS affected the expression of Stim1 at the protein level without affecting its transcript level. GRP78 implicated in CO-OCS apoptotic death. The expression of Stim1 regulated the apoptosis induced by CO-OCS via modulating GRP78 expression. Orai1 down-regulation promoted CO-OCS necrotic effect. CO-OCS induced ER- calcium depletion due to increase in ER calcium leak via the Translocon; Anisomycin (Translocon inhibitor) decreased the apoptosis induced by CO-OCS. In conclusion, these results show that in breast cancer, by targeting Stim1, Orai1 and GRP78, CO-OCS reduced cell proliferation and induced apoptosis and necrosis cell death. Stim1 favours CO-OCS apoptotic effect while Orai1 protected from necrosis induced by CO-OCS. The inhibition of Translocon decreased CO-OCS apoptotic cell death via restoring the ER calcium homeostasis
... Arrows indicate direction of stress. Figure layout adapted from[80]. ...
This thesis describes a method for quantifying the passive mechanical properties of suspended cells with a microfluidic device consisting of a parallel array of micron-sized constrictions. Using a high-speed camera, the flow speed, cell deformation and cell entry time into a constriction were measured while cells passed through the microconstriction array (~ 100 cells/min). From the flow speed and the occupation state of the constrictions with cells, the driving pressure across each constriction was continuously computed. Cell entry time into microconstrictions decreased with increasing driving pressure and decreasing cell size according to a power-law. From this power-law relationship, cell elasticity and fluidity (power-law exponent) were estimated. A more detailed analysis confirmed that cells have non-linear material properties, which means that cell stiffness increases with increasing stress and strain, for example. To avoid biased measurements due to stress and strain stiffening, 2-dimensional histogram matching was developed, which compares only cell populations from two measurements that experienced both the same stress and the same strain. The high sensitivity of the setup to cell cytoskeletal and cell nuclear changes was then shown with drugs that depolymerize or stabilize these cell components. Moreover, the influence of both measurement and culture parameters on cell mechanical properties was investigated systematically and revealed that most parameters, for instance measurement medium and timing, must be tightly controlled. Finally, through a fluorescence extension of the setup, the correlation of cell mechanical properties with fluorescently tagged intracellular proteins was achieved. An increase in cell stiffness and a decrease in cell fluidity in a dose-dependent manner was found for the overexpression of the nuclear proteins histone 2B and lamin A. In summary, in this work, passive cell mechanical properties were analyzed with a microconstriction setup on a quantitative and high-throughput basis. Therefore, it builds the foundation of a widespread use of this measurement tool in biology and medicine.
