Identification of the function and regulatory network of circ_009773 in DNA damage induced by nanoparticles of neodymium oxide.

The health hazards of nanoparticles of neodymium oxide (NPs-Nd2O3) have aroused public concern in recent years. Exposure to NPs-Nd2O3 can change the level of reactive oxygen species (ROS) that cause DNA damage and alter whole transcriptome expression profiles for micro (mi)RNA, circular (circ)RNA, long noncoding (lnc)RNA, and mRNA. However, there have been no reports to our knowledge about the role of circRNAs in DNA damage caused by NPs-Nd2O3. In our study, we analyzed the circRNA expression profile of human bronchial epithelial cells(16HBE)exposed to 40 μg/ml NPs-Nd2O3. Our results indicated that exposure produced 1025 up-regulated and 890 down-regulated circRNAs. Real-time quantitative polymerase chain reaction (qRT-PCR) was applied to verify some of the significantly changed circRNAs and demonstrated that circ_009773 was apparently down-regulated. Through exploration of its host gene function, we found that circ_009773 may be related to DNA damage. Functional experiments found that circ_009773 regulated NPs-Nd2O3-induced DNA damage in 16HBE cells. A circ_009773-associated competing endogenous (ce)RNA network was constructed based on one differentially expressed (DE) circRNA, 74 DE miRNAs and 208 DE mRNAs. Module analysis identified hub genes related to DNA damage and repair and a protein-protein interaction (PPI) network was created.