title: Differential Genomic Effects of Six Different TiO2 Nanomaterials on Human Liver HepG2 Cells.
abstract: Human HepG2 cells were exposed to six TiO2 nanomaterials (with dry primary particle sizes ranging from 22 to 214 nm, either 0.3, 3, or 30 μg/mL) for 3 days. Some of these canonical pathways changed by nano-TiO2 in vitro treatments have been already reported in the literature, such as NRF2-mediated stress response, fatty acid metabolism, cell cycle and apoptosis, immune response, cholesterol biosynthesis, and glycolysis. But this genomic study also revealed some novel effects such as protein synthesis, protein ubiquitination, hepatic fibrosis, and cancer-related signaling pathways. More importantly, this genomic analysis of nano-TiO2 treated HepG2 cells linked some of the in vitro canonical pathways to in vivo adverse outcomes: NRF2-mediated response pathways to oxidative stress, acute phase response to inflammation, cholesterol biosynthesis to steroid hormones alteration, fatty acid metabolism changes to lipid homeostasis alteration, G2/M cell checkpoint regulation to apoptosis, and hepatic fibrosis/stellate cell activation to liver fibrosis.
authors.affiliation: National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27711, USA. thai.sheau-fung@epa.gov.
authors.forename: Sheau-Fung
authors.initials: SF
authors.lastname: Thai
authors.affiliation: National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27711, USA.
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Wallace
authors.affiliation: National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27711, USA.
authors.forename: Carlton P
authors.initials: CP
authors.lastname: Jones
authors.affiliation: National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27711, USA.
authors.forename: Hongzu
authors.initials: H
authors.lastname: Ren
authors.affiliation: Department of Chemical & Materials Engineering, University of Kentucky, Lexington, KY, 40506, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Grulke
authors.affiliation: National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27711, USA.
authors.forename: Benjamin T
authors.initials: BT
authors.lastname: Castellon
authors.affiliation: National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27711, USA.
authors.forename: James
authors.initials: J
authors.lastname: Crooks
authors.affiliation: National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27711, USA.
authors.forename: Kirk T
authors.initials: KT
authors.lastname: Kitchin
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D063646:Carcinogenesis / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D002453:Cell Cycle / Q000187:drug effects* / Q000235:genetics; D002784:Cholesterol / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects* / Q000235:genetics / Q000276:immunology; D056945:Hep G2 Cells; D006801:Humans; D007113:Immunity, Innate / Q000187:drug effects / Q000235:genetics; D008103:Liver Cirrhosis; D053858:Metabolic Networks and Pathways / Q000187:drug effects* / Q000235:genetics / Q000276:immunology; D053768:Metal Nanoparticles / Q000633:toxicity*; D018384:Oxidative Stress; D010316:Particle Size; D015398:Signal Transduction; D014025:Titanium / Q000633:toxicity*
chemical_list: C009495:titanium dioxide; D002784:Cholesterol; D014025:Titanium
keywords: Genomic effects; Nano-TiO2; Nanoparticles; Signaling pathways; mRNA expression profiling