Potent aneugenicity of 1-methylpyrene in human cells dependent on metabolic activation by endogenous enzymes
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GENOTOXICITY AND CARCINOGENICITY
Potent aneugenicity of 1‑methylpyrene in human cells dependent on metabolic activation by endogenous enzymes Zihuan Li1 · Hang Yu1 · Meiqi Song1 · Hansruedi Glatt2,3 · Jianjun Liu4 · Yungang Liu1 Received: 25 August 2020 / Accepted: 8 October 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract 1-Methylpyrene (1-MP) is a common environmental pollutant and animal carcinogen. After sequential activation by cytochromes P450 and sulfotransferases, it induced gene mutations and micronuclei in mammalian cells. The type of micronuclei formed, entire chromosomes or fragments, was not analysed. In this study, 1-MP and its primary metabolite, 1-hydroxymethylpyrene (1-HMP), were investigated for the induction of centromere-positive and -negative micronuclei in the human hepatoma cell line HepG2 and its derivative C3A, expressing relevant enzymes at higher levels. Under a shortexposure (9 h)/long-recovery regime (2 cell cycles in total), 1-MP and 1-HMP provided negative test results in HepG2 cells. However, they induced micronuclei in C3A cells, the effect being blocked by 1-aminobenzotriazole (inhibitor of cytochromes P450s) and reduced by pentachlorophenol (inhibitor of sulfotransferases). Immunofluorescence staining of centromere protein B in the micronuclei revealed purely clastogenic effects under this regime. Unexpectedly, 1-MP and 1-HMP at concentrations 1/5–1/4 of that required for micronuclei formation led to mitotic arrest and spindle aberrations, as detected by immunofluorescence staining of β- and γ-tubulin. Following extended exposure (72 h, 2 cell cycles, no recovery), damage to the spindle apparatus and centrosomes was detected at even lower concentrations, with concurrent formation of micronuclei. At low concentrations (1–8 µM 1-MP, 0.25–0.5 µM 1-HMP), the micronuclei induced were unexceptionally centromere-positive. Thus, the chromosome-damaging mechanism of 1-MP was regime and concentration dependent: potently aneugenic under persistent exposure, while clastogenic at higher concentrations following a short-exposure/long-recovery regime. This is a convincing evidence for the existence of metabolic activation-dependent aneugens. Keywords Centrioles · Centromere protein B · Chromosome loss · 1-Methylpyrene · Micronuclei · Spindle body · Activation-dependent aneugenicity Zihuan Li and Hang Yu contributed to this work equally. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00204-020-02933-w) contains supplementary material, which is available to authorized users. * Yungang Liu [email protected] 1
Department of Toxicology, School of Public Health, Southern Medical University, 1023 S. Shatai Road, Guangzhou 510515, China
2
Department of Nutritional Toxicology, German Institute of Human Nutrition (DIfE), Arthur‑Scheunert‑Allee 114‑116, 14558 Nuthetal, Germany
3
Department of Food Safety, Federal Institute for Risk Assessment (BfR), Max‑Dohrn‑Straße 8‑10, 10589 Berlin, Germany
4
Key Laboratory of M
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