Project description:The mode of action of silver nanoparticles (AgNPs) is suggested to be exerted through both Ag+ and AgNP dependent mechanisms. Ingestion is one of the major NP exposure routes, and potential effects are often studied using Caco-2 cells, a well-established model for the gut epithelium. MCF-7 cells are epithelial breast cancer cells with extensive well-characterized toxicogenomics profiles. In the present study we aimed to gain a deeper understanding of the cellular molecular responses in Caco-2 and MCF-7 cells after AgNP exposure in order to evaluate whether epithelial cells derived from different tissues demonstrated similar responses. These insights could possibly reduce the size of cell panels for NP hazard identification screening purposes. AgNPs of 20, 30, 60, and 110 nm, and AgNO3 were exposed for 6h and 24h. AgNPs were shown to be taken up and dissolve intracellularly. Compared with MCF-7 cells, Caco-2 cells showed a higher sensitivity to AgNPs, slower gene expression kinetics, and absence of NP size-dependent responses. However, on a molecular level, no significant differences were observed between the two cell types. Transcriptomic analysis showed that Ag(NP) exposure caused (oxidative) stress responses, possibly leading to cell death in both cell lines. There was no indication for effects specifically induced by AgNPs. Responses to AgNPs appeared to be induced by silver ions released from the AgNPs. In conclusion, differences in mRNA responses to AgNPs between Caco-2 and MCF-7 cells were mainly related to timing and magnitude, but not to a different underlying mechanism. In total 73 samples are analyzed (24 different samples all n=3; except for 1 sample with n=4). Twelve of the 24 different samples are extracted from Caco-2 cells, 6 samples at t=6h and 6 at t=24h The other 12 different of the 24 samples are extracted from MCF-7 cells, 6 samples at t=6h and 6 at t=24h For each cell type and each timepoint one of the 6 samples was a negative control sample

Project description:In spite of many reports on the toxicity of silver nanoparticles (AgNPs), the mechanisms underlying the toxicity are far from clear. The present study conducted transcriptome and microRNAome sequencing for Euplotes vannus to understand the molecular mechanisms by which this protist copes with AgNPs exposure. By transcriptome profiling, 1884 and 5834 differentially expressed genes (DEGs) were identified after one hour and 12 hours exposure to 15 mg/L AgNPs, respectively. From microRNAsome profiling, totally 16 differentially expressed microRNAs were identified under AgNPs stress.In spite of many reports on the toxicity of silver nanoparticles (AgNPs), the mechanisms underlying the toxicity are far from clear. The present study conducted transcriptome and microRNAome sequencing for Euplotes vannus to understand the molecular mechanisms by which this protist copes with AgNPs exposure. By transcriptome profiling, 1884 and 5834 differentially expressed genes (DEGs) were identified after one hour and 12 hours exposure to 15 mg/L AgNPs, respectively. The DEGs were significantly enriched in macropinocytosis and phagocytic vesicles suggesting that the uptake of AgNPs may be mediated by endocytic pathways, while the differential expression of ABC transporters and copper-transporting ATPase implicates active efflux transport of Ag. Several DNA repair pathways were also significantly enriched with differentially expressed cell cycle control genes implying that exposure to AgNPs might have caused DNA damage and G2/M cell cycle arrest. The damage might have resulted from increased ROS production, as evidenced by elevated expression of several antioxidants genes to combat oxidative stress. From microRNAsome profiling, totally 16 differentially expressed microRNAs were identified under AgNPs stress. Integrated analysis of the microRNA and mRNA expression profiles found that the differentially expressed microRNAs target a series of genes involved in many important biological processes, suggesting that E. vannus exposure elicited a broad post-transcriptional regulatory mechanism through microRNAs–mRNAs–biological functions network to cope with the toxicity of AgNPs.

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Different responses of Caco-2 and MCF-7 cells to silver nanoparticles are based on highly similar mechanisms of action

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