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Class III β-tubulin (TUBB3) is a marker of drug resistance expressed in a variety of solid tumors. Originally, it was described as an important element of chemoresistance to taxanes. Recent studies have revealed that TUBB3 is also involved in an adaptive response to a microenvironmental stressor, e.g. low oxygen levels and poor nutrient supply in some solid tumors, independently of the microtubule targeting agent. Furthermore, it has been demonstrated that TUBB3 is a marker of biological aggressiveness associated with modulation of metastatic abilities in colon cancer. The epithelial-to-mesenchymal transition (EMT) is a basic cellular process by which epithelial cells lose their epithelial behavior and become invasive cells involved in cancer metastasis. Snail is a zinc-finger transcription factor which is able to induce EMT through the repression of E-cadherin expression. In the presented studies we focused on the analysis of the TUBB3 role in EMT-induced colon adenocarcinoma cell lines HT-29 and LS180. We observed a positive correlation between Snail presence and TUBB3 upregulation in tested adenocarcinoma cell lines. The cellular and behavioral analysis revealed for the first time that elevated TUBB3 level is functionally linked to increased cell migration and invasive capability of EMT induced cells. Additionally, the post-transcriptional modifications (phosphorylation, glycosylation) appear to regulate the cellular localization of TUBB3 and its phosphorylation, observed in cytoskeleton, is probably involved in cell motility modulation.

Chronic inflammation promotes endothelial plasticity, leading to the development of several diseases, including fibrosis and cancer in numerous organs. The basis of those processes is a phenomenon called the endothelial–mesenchymal transition (EndMT), which results in the delamination of tightly connected endothelial cells that acquire a mesenchymal phenotype. EndMT-derived cells, known as the myofibroblasts or cancer-associated fibroblasts (CAFs), are characterized by the loss of cell–cell junctions, loss of endothelial markers, and gain in mesenchymal ones. As a result, the endothelium ceases its primary ability to maintain patent and functional capillaries and induce new blood vessels. At the same time, it acquires the migration and invasion potential typical of mesenchymal cells. The observed modulation of cell shape, increasedcell movement, and invasion abilities are connected with cytoskeleton reorganization. This paper focuses on the review of current knowledge about the molecular pathways involved in the modulation of each cytoskeleton element (microfilaments, microtubule, and intermediate filaments) during EndMT and their role as the potential targets for cancer and fibrosis treatment.

Aberrant expression of thymosin beta4 (Tbeta4) has recently been found to be associated with colorectal carcinoma (CRC) progression evidently due to an increase of the motility and invasion of tumor cells and the induction of a proangiogenic phenotype of endothelial cells. Both mechanisms depend upon matrix-degrading proteases, particularly plasmin and matrix metalloproteinases (MMPs) that are responsible for extensive tissue remodeling. Cleavage of ECM macromolecules weakens the structural integrity of tissues and exposes cryptic domains of extracellular components, which elicit biological responses distinct from intact molecules. Interestingly, signaling via integrins (alphaVbeta3, alpha5beta1) in CRC cells (HT29, CX1.1) is induced by Tbeta4 and VEGF-A only when they grow in 3D fibrin gels but not in 2D ones. The cells growing in 3D fibrin gels release upon Tbeta4 significant amounts of active MMPs (MMP-2, MMP-9, and MMP-7) that cause extensive proteolysis in their close vicinity. As evidenced by a variety of approaches (transfection experiments, coimmunoprecipitation, gene silencing with siRNA), we found that this involves interaction of Tbeta4 with Ku80, which has recently been described by us to mediate Tbeta4 intracellular activity.

In this study we evaluated efficiency of DNAzymes to modulate motility of cancer cells, an important factor in the progression and metastasis of cancers. For this purpose we targeted β1 integrins that are predominant adhesive receptors in various carcinoma cell lines (CX1.1, HT29, LOVO, LS180, PC-3). To evaluate invasiveness of cancer cells, we used a transwell migration assay that allowed analyzing chemotactic migration of colon carcinoma cell lines across an ECM-coated membrane. Their adhesive properties were also characterized by the analysis of adhesion to fibronectin, laminin and collagen. In addition, the expression of major integrin subunits, selected intact β1 integrins, and other adhesive receptors (ICAM, E-selectin, uPAR) was analyzed by flow cytometry. Inhibition of β1 integrin expression by DNAzyme to β1 mRNA almost abolished the invasiveness of the CX1.1, HT29, LS180, LOVO and PC-3 cells in vitro. These data show that DNAzymes to β1 integrin subunit can be used to inhibit invasiveness of carcinoma cells.

Receptors of the β1 integrin family are involved in many tumor-promoting activities. There are several approaches currently used to control integrin activity, and thus to potentially restrain tumor metastasis and angiogenesis. In this study, we compared inhibitory efficiencies of siRNA and DNAzymes against the β1 integrin subunit (DEβ1), in a mouse xenograft model. Both inhibitors were used under their most favorable conditions, in terms of concentrations, incubation time and lack of cytotoxic effects. Transfection of siRNAβ1 or DEβ1 remarkably inhibited the growth of both PC3 and HT29 colon cancer cells in vitro, and decreased their capability of initiating tumor formation in the mouse xenograft model. siRNAβ1 appeared to be slightly more efficient than DEβ1 when tested in vitro, however it was comparably less proficient in blocking the tumor growth in vivo. We conclude the DNAzyme, due to its greater resistance to degradation in extra- and intracellular compartments, to be a superior inhibitor of tumor growth in long lasting experiments in vivo when compared to siRNA, while the latter seems to be more efficient in blocking β1 expression during in vitro experiments using cell cultures.

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