RNA-sequencing reveals long-term effects of silver nanoparticles on human lung cells

Cytotoxicity and Transcriptomic Analysis of Silver Nanoparticles in Mouse Embryonic Fibroblast Cells

The rapid development of nanotechnology has led to the use of silver nanoparticles (AgNPs) in biomedical applications, including antibacterial, antiviral, anti-inflammatory, and anticancer therapies. The molecular mechanism of AgNPs-induced cytotoxicity has not been studied thoroughly using a combination of cellular assays and RNA sequencing (RNA-Seq) analysis. In this study, we prepared AgNPs using myricetin, an anti-oxidant polyphenol, and studied their effects on NIH3T3 mouse embryonic fibroblasts as an in vitro model system to explore the potential biomedical applications of AgNPs. AgNPs induced loss of cell viability and cell proliferation in a dose-dependent manner, as evident by increased leakage of lactate dehydrogenase (LDH) from cells. Reactive oxygen species (ROS) were a potential source of cytotoxicity. AgNPs also incrementally increased oxidative stress and the level of malondialdehyde, depleted glutathione and superoxide dismutase, reduced mitochondrial membrane potential and adenosine triphosphate (ATP), and caused DNA damage by increasing the level of 8-hydroxy-2′-deoxyguanosine and the expressions of the p53 and p21 genes in NIH3T3 cells. Thus, activation of oxidative stress may be crucial for NIH3T3 cytotoxicity. Interestingly, gene ontology (GO) term analysis revealed alterations in epigenetics-related biological processes including nucleosome assembly and DNA methylation due to AgNPs exposure. This study is the first demonstration that AgNPs can alter bulk histone gene expression. Therefore, our genome-scale study suggests that the apoptosis observed in NIH3T3 cells treated with AgNPs is mediated by the repression of genes required for cell survival and the aberrant enhancement of nucleosome assembly components to induce apoptosis.

Cytotoxic Potential and Molecular Pathway Analysis of Silver Nanoparticles in Human Colon Cancer Cells HCT116

Silver nanoparticles (AgNPs) have gained attention for use in cancer therapy. In this study, AgNPs were biosynthesized using naringenin. We investigated the anti-colon cancer activities of biogenic AgNPs through transcriptome analysis using RNA sequencing, and the mechanisms of AgNPs in regulating colon cancer cell growth. The synthesized AgNPs were characterized using UV⁻visible spectroscopy (UV⁻vis), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and transmission electron microscopy (TEM). The AgNPs were spherical with sizes of 2⁻10 nm. Cytotoxicity assays indicated that the AgNPs in HCT116 colorectal cancer cells were very effective at low concentrations. The viability and proliferation of colon cancer cells treated with 5 µg/mL biogenic AgNPs were reduced by 50%. Increased lactate dehydrogenase leakage (LDH), reactive oxygen species (ROS) generation, malondialdehyde (MDA), and decreased dead-cell protease activity and ATP generation were observed. This impaired mitochondrial function and DNA damage led to cell death. The AgNPs upregulated and downregulated the most highly ranked biological processes of oxidation⁻reduction and cell-cycle regulation, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that AgNPs upregulated GADD45G in the p53 pathway. Thus, the AgNP tumor suppressive effects were mediated by cell apoptosis following DNA damage, as well as by mitochondrial dysfunction and cell-cycle arrest following aberrant regulation of p53 effector proteins. It is of interest to mention that, to the best of our knowledge, this study is the first report demonstrating cellular responses and molecular pathways analysis of AgNPs in HCT116 colorectal cancer cells.