Influence of C60 Nanofilm on the Expression of Selected Markers of Mesenchymal–Epithelial Transition in Hepatocellular Carcinoma

Simple Summary Understanding the relationship between hepatocellular carcinoma recurrence and the process of cellular phenotypic transformation is crucial for developing effective therapy. The main problem is that marginal cancer cells with strong migratory activity remain in the post-resection tumour bed. The degraded extracellular matrix of the liver combined with the presence of cytokines causes the abnormal transduction of signals into the cell and, consequently, cell migration through the vascular basement membrane. We have previously shown that growth factors induce the transformation of epithelial cells to a mesenchymal phenotype. In this study, for the first time, the effect of fullerene surfaces on the invasion of HepG2 and SNU-449 cells with epithelial and mesenchymal phenotypes was compared. It is predicted that fullerene C60, as a material that inhibits the secretion of the transforming growth factor, may reduce the invasion of mesenchymal cells and not affect epithelial cells by reducing the expression of extracellular matrix proteases. Our study aimed to determine the effect of the fullerene surface on reducing cell invasion by inducing mesenchymal–epithelial transition. Epithelial cells concentrated at the primary site of the tumours are an easier target for radioembolisation therapy. Abstract The epithelial–mesenchymal transition (EMT) is a process in which epithelial cells acquire the ability to actively migrate via a change to the mesenchymal phenotype. This mechanism occurs in an environment rich in cytokines and reactive oxygen species but poor in nutrients. The aim of this study was to demonstrate that the use of a fullerene C60 nanofilm can inhibit liver cancer cell invasion by restoring their non-aggressive, epithelial phenotype. We employed epithelial and mesenchymal HepG2 and SNU-449 liver cancer cells and non-cancerous mesenchymal HFF2 cells in this work. We used enzyme-linked immunosorbent assays (ELISAs) to determine the content of glutathione and transforming growth factor (TGF) in cells. We measured the total antioxidant capacity with a commercially available kit. We assessed cell invasion based on changes in morphology, the scratch test and the Boyden chamber invasion. In addition, we measured the effect of C60 nanofilm on restoring the epithelial phenotype at the protein level with protein membranes, Western blotting and mass spectrometry. C60 nanofilm downregulated TGF and increased glutathione expression in SNU-449 cells. When grown on C60 nanofilm, invasive cells showed enhanced intercellular connectivity; reduced three-dimensional invasion; and reduced the expression of key invasion markers, namely MMP-1, MMP-9, TIMP-1, TIMP-2 and TIMP-4. Mass spectrometry showed that among the 96 altered proteins in HepG2 cells grown on C60 nanofilm, 41 proteins are involved in EMT and EMT-modulating processes such as autophagy, inflammation and oxidative stress. The C60 nanofilm inhibited autophagy, showed antioxidant and anti-inflammatory properties, increased glucose transport and regulated the β-catenin/keratin/Smad4/snail+slug and MMP signalling pathways. In conclusion, the C60 nanofilm induces a hybrid mesenchymal–epithelial phenotype and could be used in the prevention of postoperative recurrences.