No abstract

The actin cytoskeleton is substantially modified in cancer cells because of changes in actin-binding protein abundance and functional activity. As a consequence, cancer cells have distinctive motility and mechanical properties, which are important for many processes, including invasion and metastasis. Here, we studied the effects of actin cytoskeleton alterations induced by specific nucleation inhibitors (SMIFH2, CK-666), cytochalasin D, Y-27632 and detachment from the surface by trypsinization on the mechanical properties of normal Vero and prostate cancer cell line DU145. The Young's modulus of Vero cells was 1300±900 Pa, while the prostate cancer cell line DU145 exhibited significantly lower Young's moduli (600±400 Pa). The Young's moduli exhibited a log-normal distribution for both cell lines. Unlike normal cells, cancer cells demonstrated diverse viscoelastic behavior and different responses to actin cytoskeleton reorganization. They were more resistant to specific formin-dependent nucleation inhibition, and reinforced their cortical actin after detachment from the substrate. This article is part of a Special Issue entitled: Mechanobiology.

The speculations on the role of MUC1, a substance which is overexpressed in glandular cancer cells, on the metastatic potential of such cells are rooted in data that seem to indicate that cell malignization correlates with a change from the apical localization of mucin MUC1 to a peripheral one. Nonetheless, the role of MUC1 in cancer metastasizing remains far from clear. The major hurdle remains the absence of adequate cell models. The aim of the present study was to create cell models that present different fragments of the human mucin MUC1 extracellular domain on their surface. Genetic constructions were generated on the basis of the plasmid vector pEGFP-N3. These constructions contain fusion genes coding for chimeric proteins composed of different combinations of mucin MUC1 functional domains and identification markers (FLAG-epitope, located at the N-terminus, and EGFP, located at the C-terminus of the chimeric proteins). These constructions were used for a stable transformation of HT-29 human cancer cells. The transformants obtained were characterized by flow cytometry. The low expression level of endogenous mucin MUC1 and the high expression level of recombinant proteins were confirmed by real-time PCR. The microscopic examination of the transformed cells confirmed the membrane localization of the fusion proteins. The resulting cell models could be used to investigate the role of the mucin MUC1 domains in cancer cell metastasizing. The obtained cells are used as an applicable model of MUC1-expressing cancers and might be used to study the role of different functional fragments of mucin MUC1 in metastasizing.

Studying the copy number of ribosomal protein L7/L12 was performed using monoclonal antibody 3G9 to the linear epitope on the C-terminal domain of this protein from Escherichia coli. Immunohistochemical study showed that Agrobacterium tumefaciens ribosomes include 6 copies of protein L7/L12. Our results suggest that the copy number of this protein has an evolutionary role.

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.