Extensive uses of calcium titanate nanoparticles (CaTiO3-NPs) and erbium oxide nanoparticles (Er2O3-NPs) increase their release into the environment and human exposure, particularly through skin contact. However, there are almost no studies available on the effect of these nanoparticles on skin integrity. Therefore, this study was undertaken to estimate CaTiO3-NP- or Er2O3-NP-induced cytotoxicity and genotoxicity in normal human skin fibroblast (HSF) cells. Cell viability was measured using sulforhodamine B (SRB) assay, while the level of DNA damage was detected using the alkaline comet assay. The intracellular levels of reactive oxygen species (ROS) as well as the expression level of p53, Bax, and Bcl2 genes were detected. Although the viability of HSF cells was non-markedly changed after 24 h, prolonged treatment with CaTiO3-NPs or Er2O3-NPs for 72 h induced concentration-dependent death of HSF cells. Treatment of normal HSF cells with IC50/72 h of CaTiO3-NPs or Er2O3-NPs did not cause marked changes in the intracellular level of ROS, DNA damage parameters, and expression levels of apoptosis genes compared to their values in the untreated HSF cells. We thus concluded that CaTiO3-NPs or Er2O3-NPs cause time- and concentration-dependent cytotoxicity toward normal HSF cells. However, safe and non-genotoxic effects were demonstrated by the apparent non-significant changes in intracellular ROS level, DNA integrity, and apoptotic genes’ expression after exposure of normal HSF cells to nanoparticles. Thus, it is recommended that further studies be conducted to further understand the toxic and biological effects of CaTiO3-NPs and Er2O3-NPs.

Background The distinctive properties and high activity of calcium titanate nanoparticles (CaTiO3-NPs) increase their use in many products. However, the cytotoxic and genotoxic effects of CaTiO3-NPs in human cancer cell lines have not been well studied. Therefore, this study was conducted to explore CaTiO3-NPs induced cytotoxicity, genomic instability and apoptosis in human breast cancer (MCF-7) cells. Methods Sulforhodamine B (SRB) and the alkaline comet assays were done to study cell viability and DNA damage induction, respectively. Apoptosis induction and cell cycle distribution were analyzed using flow cytometry. The level of intracellular reactive oxygen species (ROS) was studied, and the expression levels of p53, Bax and Bcl2 genes were also measured. Results The results of the Sulforhodamine B (SRB) cytotoxicity assay showed that viability of MCF-7 cells was not affected by CaTiO3-NPs treatment for 24 h, however, exposure to CaTiO3-NPs for 72 h caused concentrations dependent death of MCF-7 cells. Treatment with CaTiO3-NPs for 72 h caused marked increases in intracellular ROS level and induced DNA damage. Treatment of MCF-7 cells with CaTiO3-NPs also caused MCF-7 cell cycle arrest at the G0 and S phases and s triggered apoptosis of MCF-7 cells by causing simultaneous increases in the expression levels of apoptotic p53 and Bax genes and a decrease in the expression level of anti-apoptotic Bcl2 gene. Conclusion Collectively, it was concluded that CaTiO3-NPs cause time- and concentration-dependent cytotoxic effects in human MCF-7 cells through induction of ROS generation, genomic instability and apoptosis. Thus it is recommended that further in vitro and in vivo studies are therefore recommended to understand the cytotoxic and biological effects of CaTiO3-NPs.