Cancer metastasis remains a critical area of study within the field of cancer research. The tumor microenvironment (TME), comprising various cell types and the extracellular matrix (ECM), plays a...Show moreCancer metastasis remains a critical area of study within the field of cancer research. The tumor microenvironment (TME), comprising various cell types and the extracellular matrix (ECM), plays a pivotal role in controlling tumor initiation and progression. Here we show an investigation into the mechanical phenotype of Hs 578T breast cancer cells within the TME, focusing particularly on the role of cell-ECM interactions in modulating cellular traction forces. Hs 578T cells with an integrin- α2 (ITGA2) stable knockout were utilized, and the resulting pressures were compared between the control and knockout at different collagen concentrations. Attention is hence given to the ITGA2 and its role in mediating cell-ECM interactions. Through the utilization of elastic hydrogel microparticles as localized stress sensors and advanced microscopy techniques, we show that increasing the collagen concentration results in increased traction forces exerted by control breast cancer cells. Conversely, the traction forces by ITGA2 Hs 578T knockout cells remain unaffected by changes in collagen concentration. Also, a linear relationship between the traction and its standard deviation, regardless of the Hs 578T cell type and collagen concentration, is observed. The findings contribute to a deeper understanding of cancer biomechanics, offering insights into potential therapeutic targets for inhibiting metastatic spread in breast cancer.Show less
In the process of metastasis, cancer cells may transmigrate through the endothelium barrier of the vascular walls and into the circulatory blood system. During this process, the cancer cells...Show moreIn the process of metastasis, cancer cells may transmigrate through the endothelium barrier of the vascular walls and into the circulatory blood system. During this process, the cancer cells interact with the endothelial cells, resulting in the alternation of their mechanical properties. Although this interaction has been broadly studied from the perspective of cancer cells, no thorough investigation of the endothelial mechanical properties has been performed. In this thesis, by using a micro-rheology AFM-based approach, we show that the properties of endothelial cells change when cultured in cancer cell conditioned medium, as well as when in contact with cancer cells. We found that the stiffness of endothelial cells increased when cultured in a low-dilution cancer cell medium, while it decreased in high-dilution medium. This change was also evident on the viscoelasticity of the cells, with the endothelial cells cultured in high dilution medium showing lower viscoelastic properties. Furthermore, endothelial cells in direct contact with a cancer cell showed an increased height, as a result of the cancer cell's transmigration through the monolayer. Our findings demonstrate that the properties of endothelial cells change indirectly due to cancer cell secreted substances, and directly during the cancer cells' physical transmigration. This indicates that the endothelium is actively responding to the presence of cancer cells, rather than being a passive barrier as once believed.Show less
To better understand tumor progression and metastasis, it is important to investigate the mechanical properties of its cellular components. Tumors generally consist of cancer cells and healthy...Show moreTo better understand tumor progression and metastasis, it is important to investigate the mechanical properties of its cellular components. Tumors generally consist of cancer cells and healthy cells, whose interactions are fundamental for their structure and functionality. It has been shown that in co-cultured spheroids, cells rearrange themselves and completely separate. To closely mimic the tumor micro-environment in-vitro, hetero-spheroids containing both cancer cells and fibroblasts were used. The forces generated during cell-cell interaction and their cell sorting were studied. The interaction between the two cell types was probed with cell-sized (15-30 μm) microparticles. Different seeding-times and number ratios were investigated. No significant difference in the stress fields applied by the two different cell types during their interaction was found. However, it was observed that there is a critical number ratio between 1:3 and 1:6, above which the two cell types tend to completely separate. Below the critical ratio, there were intermixed areas of both cell lines. These cell clusters tend to merge over time, however no complete phase separation of the two cell types was observed for a period of one week. These results show that there is a favourable rearrangement of the cells consisting tumor-like structures. This cell type separation could indicate the next steps towards understanding the clustering and detachment of the cancer cells from the primary tumor, during metastasis.Show less
