Characterization of cell surface structure and its relation to cytoskeleton elasticity in cancer cells

Abstract

The alterations observed in tumour cells include the number of processes introducing abnormalities in cellular morphology, structure and growth profiles. Despite continuous efforts, the molecular mechanism of the metastasis is still not understood completely. That is the reason why there is an urgent need for the search of new scientific approaches in the cancer progression investigations. The development of various biochemical and biological methods increases the chance to detect cancer, however, in past decades, single cell biomechanics has gained large significance since certain diseases are known to manifest in altered biomechanical properties. Stiffness of single cells is one of the major properties that changes during cancerous progression. Studies have demonstrated that biomechanics can bring both data describing mechanisms underlying cancer progression and tools for its detection and diagnosis at the single cell level. However, one of the emerging directions is to correlate cellular biomechanics with biochemical and biophysical properties of single cells.The main objective of the presented thesis is to study how single cell deformability is linked with cellular surface properties, and how these changes correlate with cancer progression. Thus, the elasticity of melanoma cells was measured by means of atomic force microscopy (AFM). Measurements were carried out for three groups of cells encompassing cells originating from primary tumour sites i.e. from radial and vertical growth phases (RGP and VGP, respectively), and those derived from skin and lung metastasis. The results were compared with properties of melanocytes (cells from which melanoma originates). The surface properties were determined using time of flight secondary ions mass spectrometry(ToF SIMS). The use of ToF SIMS has required to develop a dedicated sample preparation protocol enablingmeasurements of biological material in the high vacuum environment. The final results show the correlation between single cell deformability and surface biochemical properties of melanoma cells. They confirm the hypothesis that cancer progression causes alterations in the morphological and mechanical properties of cancerous cells and these differences are connected with changes in the cellular surface composition.