Titanium-Dioxide Nanoparticles Suppress Entosis in MCF-7 Human Breast Adenocarcinoma Culture

TiO 2 nanoparticles are widely used in industry, pharmacology, and medicine. Recently, it has been proposed to use TiO 2 nanoparticles for targeted delivery of chemotherapeutic drugs, which can lead to an increase in the local concentration of TiO 2 and influence the processes occurring in the tumor, including entosis (the invasion of one tumor cell into another). In this work, we studied the effect of TiO 2 nanoparticles (particles of the mineral anatase less than 25 nm in size and particles consisting of a mixture of anatase and rutile less than 75 nm in size at a concentration of 1, 10, or 100 μg/mL for 72 h ) on the process of entosis in human breast MCF-7 adenocarcinoma cell culture. Cultivation of cells in the presence of different types of TiO 2 nanoparticles slows down proliferation and causes a decrease in the number of entoses. Elemental analysis by analytical electron microscopy revealed the presence of TiO 2 in the endosomal compartment, in the cytosol and in the extracellular space. Immunochemical staining showed that both types of TiO 2 nanoparticles at a concentration of 10 μg/mL disrupt the formation of adhesive contacts, including those in the early stages of entosis. The impact of anatase particles induces the translocation of the p53 protein into the cell nuclei. In general, the TiO 2 nanoparticles used in the work inhibit entosis in MCF-7 culture cells, disrupting adhesive contacts and interfering with the process of invasion. However, it can be assumed that disruption of adhesive contacts can enhance the mobility of tumor cells and metastasis.