Tunneling nanotubes (TNTs) are long, thin tubular cell protrusions that connect cells and enable them to communicate with each other by transferring cellular and non-cellular components. TNTs participate in physiological and pathological processes, so understanding the properties of TNTs and the effects on their formation is crucial for the development of drugs for targeted delivery. In this thesis, we aimed to determine the influence of the inflammatory cytokine TNF-α, tumor necrosis factor α, on the formation of TNTs in normal and cancer urothelial cells. The cell line of normal urothelial cells SV HUC-1 and cancer urothelial cells T24 were treated with 1, 10, 20, 30 and 50 ng/mL TNF-α for 24 hours. TNTs were labeled with phalloidin, which binds to actin filaments, and the number of TNTs and the length of TNTs were analyzed by fluorescence microscopy. In SV-HUC-1 and T24 cells, the number of TNTs was higher than in control cells after treatment with all concentrations of TNF-α. A statistically significant increase in TNT number was observed when SV-HUC-1 cells were treated with 1 ng/mL TNF-α, with the number of TNTs increasing threefold compared to the control. A statistically significant increase in the number of TNTs formed was induced in T24 cells by treatment with 20 and 30 ng/mL TNF-α, with the number of TNTs increasing twofold compared to the control. No change in length of TNTs occurred in any cell line after treatment with TNF-α. TNFAIP2, tumor necrosis factor α induced protein 2, participates in the TNF-α/NF-κB signaling pathway, and its expression after treatment with TNF-α was analyzed by western blotting. Decreased TNFAIP2 expression was demonstrated in SV-HUC-1 cells when treated with 1 and 20 ng/mL TNF-α, while increased TNFAIP2 expression was demonstrated in T24 cells when treated with 10 and 50 ng/mL TNF-α. By performing a luminescent cell viability assay, we demonstrated that TNF-α has no cytotoxic effect for the used TNF-α concentrations. SV-HUC-1 cell viability was significantly increased by treatment with 10 ng/mL TNF-α, and T24 by treatment with 1, 10, 20, 30 and 50 ng/mL TNF-α. We found that TNF-α is an inducer of TNT formation in normal and cancer urothelial cells. This laid the foundation for further research into the role of the TNF-α in TNT mediated cell communication in urothelial cells.
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