Cerium Dioxide Nanoparticles Modulate Ribosomal DNA Transcriptional Activity in Cultured Human Skin Fibroblasts

The study investigates the effect of cerium dioxide (CeO₂) nanoparticles on ribosomal DNA (rDNA) transcriptional activity and the status of ribosomal genes in human skin fibroblasts. Nano-CeO₂ has attracted attention due to its antioxidant and redox properties; however, its impact on rDNA has so far remained virtually unexplored. Fibroblasts from ten adult donors were incubated with nano-CeO₂ for 3 and 24 h, and the copy number of ribosomal genes and their functional state were assessed using real-time quantitative PCR and non-radioactive quantitative hybridization; the interaction of the nanoparticles with the cells was also assessed by fluorescence microscopy. It was shown that exposure to CeO₂ nanoparticles leads to functional changes in rDNA transcription and rRNA abundance, indicating modulation of ribosomal biogenesis and consistent with a model of altered balance between transcriptionally active and inactive rDNA copies, although this study did not directly measure ribosome content or rDNA fraction distribution. The observed effects are likely mediated by the antioxidant and redox properties of the nanoparticles. Thus, nano-CeO₂ can be considered a compound capable of modulating the functional state of ribosomal genes in normal human cells.