Involvement of TGF-β and ROS in G1 Cell Cycle Arrest Induced by Titanium Dioxide Nanoparticles Under UVA Irradiation in a 3D Spheroid Model

Abstract

Yuanyuan Ren,1 Runqing Geng,1 Qunwei Lu,1,2 Xi Tan,1 Rong Rao,1 Hong Zhou,1 Xiangliang Yang,1,3 Wei Liu1,3 1College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China; 2Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China; 3National Engineering Research Center for Nanomedicine, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of ChinaCorrespondence: Qunwei LuKey Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of ChinaEmail [email protected] LiuCollege of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of ChinaTel [phone]Fax [phone]Email [email protected]: As one of the most widely produced engineered nanomaterials, titanium dioxide nanoparticles (nano-TiO2) are used in biomedicine and healthcare products, and as implant scaffolds; therefore, the toxic mechanism of nano-TiO2 has been extensively investigated with a view to guiding application. Three-dimensional (3D) spheroid models can simplify the complex physiological environment and mimic the in vivo architecture of tissues, which is optimal for the assessment of nano-TiO2 toxicity under ultraviolet A (UVA) irradiation.Methods and Results: In the present study, the toxicity of nano-TiO2 under UVA irradiation was investigated in 3D H22 spheroids cultured in fibrin gels. A significant reduction of approximately 25% in spheroid diameter was observed following treatment with 100 μg/mL nano-TiO2 under UVA irradiation after seven days of culture. Nano-TiO2 under UVA irradiation triggered the initiation of the TGF-β/Smad signaling pathway, increasing the expression levels of TGF-β 1, Smad3, Cdkn1a, and Cdkn2b at both the mRNA and protein level, which resulted in cell cycle arrest in the G1 phase. In addition, nano-TiO2 under UVA irradiation also triggered the production of reactive oxygen species (ROS), which were shown to be involved in cell cycle regulation and the induction of TGF-β 1 expression.Conclusion: Nano-TiO2 under UVA irradiation induced cell cycle arrest in the G1 phase and the formation of smaller spheroids, which were associated with TGF-β/Smad signaling pathway activation and ROS generation. These results reveal the toxic mechanism of nano-TiO2 under UVA irradiation, providing the possibility for 3D spheroid models to be used in nanotoxicology studies.Keywords: nano-TiO2, cell cycle arrest, TGF-β signaling pathway, reactive oxygen species, 3D spheroid culture

Keywords

• nano-tio2
• cell cycle arrest
• tgf-β signaling pathway
• reactive oxygen species
• 3d spheroid culture