title: TiO2 nanoparticles induce DNA double strand breaks and cell cycle arrest in human alveolar cells.
abstract: TiO2 nanoparticles (NPs) have the second highest global annual production (∼3000 tons) among the metal-containing NPs. These NPs are used as photocatalysts for bacterial disinfection, and in various other consumer products including sunscreen, food packaging, therapeutics, biosensors, surface cleaning agents, and others. Humans are exposed to these NPs during synthesis (laboratory), manufacture (industry), and use (consumer products, devices, medicines, etc.), as well as through environmental exposures (disposal). Hence, there is great concern regarding the health effects caused by exposure to NPs and, in particular, to TiO2 NPs. In the present study, the genotoxic potential of TiO2 NPs in A549 cells was examined, focusing on their potential to induce ROS, different types of DNA damage, and cell cycle arrest. We show that TiO2 NPs can induce DNA damage and a corresponding increase in micronucleus frequency, as evident from the comet and cytokinesis-block micronucleus assays. We demonstrate that DNA damage may be attributed to increased oxidative stress and ROS generation. Furthermore, genomic and proteomic analyses showed increased expression of ATM, P53, and CdC-2 and decreased expression of ATR, H2AX, and Cyclin B1 in A549 cells, suggesting induction of DNA double strand breaks. The occurrence of double strand breaks was correlated with cell cycle arrest in G2/M phase. Overall, the results indicate the potential for genotoxicity following exposure to these TiO2 NPs, suggesting that use should be carefully monitored.
authors.affiliation: Institute of Life Sciences, Ahmedabad University, University Road, Navrangpura, Ahmedabad, Gujarat, India.
authors.forename: Krupa
authors.initials: K
authors.lastname: Kansara
authors.forename: Pal
authors.initials: P
authors.lastname: Patel
authors.forename: Darshini
authors.initials: D
authors.lastname: Shah
authors.forename: Ritesh K
authors.initials: RK
authors.lastname: Shukla
authors.forename: Sanjay
authors.initials: S
authors.lastname: Singh
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Kumar
authors.forename: Alok
authors.initials: A
authors.lastname: Dhawan
mesh_terms: D059447:Cell Cycle Checkpoints / Q000187:drug effects*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects*; D004249:DNA Damage / Q000187:drug effects; D006801:Humans; D053768:Metal Nanoparticles / Q000009:adverse effects*; D015162:Micronucleus Tests; D009153:Mutagens / Q000009:adverse effects*; D018384:Oxidative Stress / Q000187:drug effects; D040901:Proteomics; D011650:Pulmonary Alveoli / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D014025:Titanium / Q000009:adverse effects*
chemical_list: D009153:Mutagens; D017382:Reactive Oxygen Species; C009495:titanium dioxide; D014025:Titanium
keywords: DNA double strand breaks; TiO2 NPs; cell cycle arrest; genotoxicity; micronucleus; oxidative stress