Dose‑dependent autophagic effectof titanium dioxide nanoparticles in humanHaCaT cells at non‑cytotoxic levels
2016 (English)In: Journal of Nanobiotechnology, ISSN 1477-3155, E-ISSN 1477-3155, Vol. 14, no 22, 1-13 p.Article in journal (Refereed) Published
Background: Interactions between nanoparticles and cells are now the focus of a fast-growing area of research.Though many nanoparticles interact with cells without any acute toxic responses, metal oxide nanoparticles includingthose composed of titanium dioxide (TiO2-NPs) may disrupt the intracellular process of macroautophagy.Autophagy plays a key role in human health and disease, particularly in cancer and neurodegenerative diseases. Weherein investigated the in vitro biological effects of TiO2-NPs (18 nm) on autophagy in human keratinocytes (HaCaT)cells at non-cytotoxic levels.Results: TiO2-NPs were characterized by transmission electron microscopy (TEM) and dynamic light scatteringtechniques. Cellular uptake, as evaluated by TEM and NanoSIMS revealed that NPs internalization led to the formationof autophagosomes. TiO2-NPs treatment did not reduce cell viability of HaCaT cells nor increased oxidative stress. Cellularautophagy was additionally evaluated by confocal microscopy using eGFP-LC3 keratinocytes, western blottingof autophagy marker LC3I/II, immunodetection of p62 and NBR1 proteins, and gene expression of LC3II, p62, NBR1,beclin1 and ATG5 by RT-qPCR. We also confirmed the formation and accumulation of autophagosomes in NPs treatedcells with LC3-II upregulation. Based on the lack of degradation of p62 and NBR1 proteins, autophagosomes accumulationat a high dose (25.0 μg/ml) is due to blockage while a low dose (0.16 μg/ml) promoted autophagy. Cellularviability was not affected in either case.Conclusions: The uptake of TiO2-NPs led to a dose-dependent increase in autophagic effect under non-cytotoxicconditions. Our results suggest dose-dependent autophagic effect over time as a cellular response to TiO2-NPs. Mostimportantly, these findings suggest that simple toxicity data are not enough to understand the full impact of TiO2-NPsand their effects on cellular pathways or function.
Place, publisher, year, edition, pages
BioMed Central, 2016. Vol. 14, no 22, 1-13 p.
Autophagy, Cell-nanoparticle interactions, Dose, Keratinocytes, Titanium dioxide nanoparticles
IdentifiersURN: urn:nbn:se:liu:diva-126342DOI: 10.1186/s12951-016-0174-0ISI: 000372577700001PubMedID: 27001369OAI: oai:DiVA.org:liu-126342DiVA: diva2:913705
FunderSwedish Research Council, 621-2011-5267
Funding agencies: Swedish Research Council-Natural Science; VR-NT; Carl Trygger Foundation; Oscar and Lilli Lamms Minne Foundation; Angpanneforening Research foundation; IKERBASQUE Basque Foundation for science; VINNOVA - County Councils of Ostergotland, Sweden; Linkoping 2016-03-222016-03-222016-04-20Bibliographically approved