Hepatotoxicity of perfluorooctanoic acid and two emerging alternatives based on a 3D spheroid model

• Published in: Environmental pollution (1987) Vol. 246; pp. 955 - 962
• Main Authors: Sun, Sujie, Guo, Hua, Wang, Jianshe, Dai, Jiayin
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-03-2019
• Subjects: Animals; Apoptosis - drug effects; Apoptosis - genetics; Caprylates - chemistry; Caprylates - toxicity; Cell Line; Environmental Pollutants - chemistry; Environmental Pollutants - toxicity; Fluorocarbons - chemistry; Fluorocarbons - toxicity; Hepatotoxicity; HFPO-DA; Liver - drug effects; Liver - metabolism; Mice; Models, Biological; Oxidative Stress - drug effects; Oxidative Stress - genetics; Perfluorooctanoic acid; PFO4DA; PPAR alpha - metabolism; Reactive Oxygen Species - metabolism; Signal Transduction - drug effects; Signal Transduction - genetics; Spheroid; HFPO-DA; Spheroid; PFO4DA; Perfluorooctanoic acid; Hepatotoxicity
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2018.12.065

Perfluorooctanoic acid (PFOA) toxicity is of considerable concern due to its wide application, environmental persistence, and bioaccumulation. In the current study, we used a scaffold-free three-dimensional (3D) spheroid model of mouse liver cells (AML12) to explore the toxicity of PFOA and emerging alternatives (HFPO-DA and PFO4DA). Comparing the short-term (24 and 72 h treatment) toxicity of PFOA between conventional 2D monolayer cells and 3D spheroids, we found that spheroids had higher EC50 values and lower ROS levels after treatment, indicating their greater resistance to PFOA. Cell viability (i.e., adenosine triphosphate (ATP) content and lactate dehydrogenase (LDH) leakage) and liver-specific function (i.e., albumin secretion) were stable in spheroids through 28 day of culture. However, under 100 and 200 μM-PFOA treatment for 28 day, ROS levels, LDH leakage, and caspase3/7 activity all increased significantly. As a sensitive parameter, ROS showed a significant increase at 21 day, even in the 50 μM-PFOA group. Consistent with the elevation of ROS and caspase3/7, the expressions of oxidative stress- and apoptosis-related genes, including Gsta2, Nqo1, Ho-1, caspase3, p53, and p21, were induced in dose- and time-dependent manners after PFOA exposure. The peroxisome proliferator-activated receptor alpha (PPARα) pathway was also activated after treatment, with significant induction of its target genes, Fabp4 and Scd1. Similar to PFOA, both HFPO-DA and PFO4DA activated the PPARα pathway, induced ROS levels, and initiated cell damage, though at a relatively lower extent than that of PFOA. Our results imply that the 3D spheroid model is a valuable tool in chronic toxicological studies.
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•PFOA toxicity differed between the 3D spheroid model and 2D monolayer cells.•ROS was a sensitive PFOA parameter in spheroids after long-term exposure.•PFOA activated the PPARα pathway in spheroids after long-term exposure.•HFPO-DA and PFO4DA hepatotoxicities were lower than that of PFOA.•The spheroid model is a feasible in vitro approach in chronic toxicological studies.