Evaluation of an in vitro three-dimensional HepaRG spheroid model for genotoxicity testing using the high-throughput CometChip platform

Main Article Content

Ji-Eun Seo, Xiaobo He, Levan Muskhelishvili, Pritpal Malhi, Nan Mei, Mugimane Manjanatha, Matthew Bryant, Tong Zhou, Timothy Robison, Xiaoqing Guo
[show affiliations]

Abstract

Three-dimensional (3D) culture systems are increasingly being used for genotoxicity studies due to improved cell-to-cell interactions and tissue-like structures that are limited or lacking in 2D cultures. The present study optimized a 3D culture system using metabolically competent HepaRG cells for in vitro genotoxicity testing. 3D HepaRG spheroids, formed in 96- or 384-well ultra-low attachment plates, were exposed to various concentrations of 34 test articles, including 8 direct-acting and 11 indirect-acting genotoxicants/carcinogens as well as 15 compounds that show different genotoxic responses in vitro and in vivo. DNA damage was evaluated using the high-throughput CometChip assay with concurrent cytotoxicity assessment by the ATP assay in both 2D and 3D cultures. 3D HepaRG spheroids maintained a stable phenotype for up to 30 days with higher levels of albumin secretion, cytochrome P450 gene expression, and enzyme activities compared to 2D cultures. 3D spheroids also demonstrated a higher sensitivity than 2D cultures for detecting both direct- and indirect-acting genotoxicants/carcinogens, indicating a better prediction of in vivo genotoxicity responses. When DNA damage dose-response data were quantified using PROAST software, 3D spheroids generally had lower or similar benchmark dose values compared to 2D HepaRG cells and were more comparable with primary human hepatocytes. These results demonstrate that 3D models can be adapted to the CometChip technology for high-throughput genotoxicity testing and that 3D HepaRG spheroids may be used as a reliable and pragmatic in vitro approach to better support the hazard identification and risk assessment of potential human genotoxic carcinogens.

Article Details

How to Cite
Seo, J.-E. (2022) “Evaluation of an in vitro three-dimensional HepaRG spheroid model for genotoxicity testing using the high-throughput CometChip platform”, ALTEX - Alternatives to animal experimentation, 39(4), pp. 583–604. doi: 10.14573/altex.2201121.
Section
Articles
References

Baharvand, H., Hashemi, S. M., Kazemi Ashtiani, S. et al. (2006). Differentiation of human embryonic stem cells into hepatocytes in 2D and 3D culture systems in vitro. Int J Dev Biol 50, 645-652. doi:10.1387/ijdb.052072hb

Bemis, J. C., Avlasevich, S. L., Labash, C. et al. (2018). Glycosylphosphatidylinositol (GPI) anchored protein deficiency serves as a reliable reporter of Pig-a gene mutation: Support from an in vitro assay based on L5178Y/Tk+/- cells and the CD90.2 antigen. Environ Mol Mutagen 59, 18-29. doi:10.1002/em.22154

Besaratinia, A. and Pfeifer, G. P. (2007). A review of mechanisms of acrylamide carcinogenicity. Carcinogenesis 28, 519-528. doi:10.1093/carcin/bgm006

Bhalli, J. A., Shaddock, J. G., Pearce, M. G. et al. (2013). Sensitivity of the Pig-a assay for detecting gene mutation in rats exposed acutely to strong clastogens. Mutagenesis 28, 447-455. doi:10.1093/mutage/get022

Breslin, S. and O’Driscoll, L. (2013). Three-dimensional cell culture: The missing link in drug discovery. Drug Discov Today 18, 240-249. doi:10.1016/j.drudis.2012.10.003

Buick, J. K., Williams, A., Meier, M. J. et al. (2021). A modern genotoxicity testing paradigm: Integration of the high-throughput cometchip® and the TGx-DDI transcriptomic biomarker in human HhepaRG™ cell cultures. Front Public Health 9, 694834. doi:10.3389/fpubh.2021.694834

Chao, C. and Engelward, B. P. (2020). Applications of cometchip for environmental health studies. Chem Res Toxicol 33, 1528-1538. doi:10.1021/acs.chemrestox.9b00393

Conway, G. E., Shah, U. K., Llewellyn, S. et al. (2020). Adaptation of the in vitro micronucleus assay for genotoxicity testing using 3D liver models supporting longer-term exposure durations. Mutagenesis 35, 319-330. doi:10.1093/mutage/geaa018

Cox, C. R., Lynch, S., Goldring, C. et al. (2020). Current perspective: 3D spheroid models utilizing human-based cells for investigating metabolism-dependent drug-induced liver injury. Front Med Technol 2, 611913. doi:10.3389/fmedt.2020.611913

Culp, S. J. (2004). NTP technical report on the toxicity studies of malachite green chloride and leucomalachite green (CAS Nos. 569-64-2 and 129-73-7) administered in feed to F344/N rats and B6C3F1 mice. Toxic Rep Ser, 1-F10.

Custer, L., Roberts, D., and Nicotra, S. (2015). In vivo follow-up testing for in vitro mutagenic and clastogenic reagents EDAC and HOPO. Abstracts from the Environmental Mutagenesis and Genomics Society, 46th Annual Meeting. Environ Mol Mutagen 56, S44. doi:10.1002/em.21969

David, R., Talbot, E., Allen, B. et al. (2018). The development of an in vitro Pig-a assay in L5178Y cells. Arch Toxicol 92, 1609-1623. doi:10.1007/s00204-018-2157-4

Dertinger, S. D., Phonethepswath, S., Avlasevich, S. L. et al. (2012). Efficient monitoring of in vivo Pig-a gene mutation and chromosomal damage: Summary of 7 published studies and results from 11 new reference compounds. Toxicol Sci 130, 328-348. doi:10.1093/toxsci/kfs258

Dertinger, S. D., Avlasevich, S. L., Torous, D. K. et al. (2019). 3Rs friendly study designs facilitate rat liver and blood micronucleus assays and Pig-a gene mutation assessments: Proof-of-concept with 13 reference chemicals. Environ Mol Mutagen 60, 704-739. doi:10.1002/em.22312

Ding, W., Levy, D. D., Bishop, M. E. et al. (2015). In vivo genotoxicity of estragole in male F344 rats. Environ Mol Mutagen 56, 356-365. doi:10.1002/em.21918

Dobo, K. L., Cheung, J. R., Gunther, W. C. et al. (2018). 2-hydroxypyridine-N-oxide (HOPO): Equivocal in the ames assay. Environ Mol Mutagen 59, 312-321. doi:10.1002/em.22179

Dobo, K. L., Coffing, S., Gunther, W. C. et al. (2019). 2-hydroxypyridine n-oxide is not genotoxic in vivo. Environ Mol Mutagen 60, 588-593. doi:10.1002/em.22294

ECHA, T. E. C. A. (2021). N'-(ethylcarbonimidoyl)-N,N-dimethylpropane-1,3-diamine monohydrochloride. https://echa.europa.eu/registration-dossier/-/registered-dossier/23229/23227/23227/23221

Edmondson, R., Broglie, J. J., Adcock, A. F. et al. (2014). Three-dimensional cell culture systems and their applications in drug discovery and cell-based biosensors. Assay Drug Dev Technol 12, 207-218. doi:10.1089/adt.2014.573

EFSA, S. C., Hardy, A., Benford, D. et al. (2017). Update: Use of the benchmark dose approach in risk assessment. EFSA J 15, e04658. doi:10.2903/j.efsa.2017.4658

Eichenbaum, G., Johnson, M., Kirkland, D. et al. (2009). Assessment of the genotoxic and carcinogenic risks of p-nitrophenol when it is present as an impurity in a drug product. Regul Toxicol Pharmacol 55, 33-42. doi:10.1016/j.yrtph.2009.05.018

El Ramy, R., Ould Elhkim, M., Lezmi, S. et al. (2007). Evaluation of the genotoxic potential of 3-monochloropropane-1,2-diol (3-MCPD) and its metabolites, glycidol and beta-chlorolactic acid, using the single cell gel/comet assay. Food Chem Toxicol 45, 41-48. doi:10.1016/j.fct.2006.07.014

Elia, M. C., Storer, R. D., McKelvey, T. W. et al. (1994). Rapid DNA degradation in primary rat hepatocytes treated with diverse cytotoxic chemicals: Analysis by pulsed field gel electrophoresis and implications for alkaline elution assays. Environ Mol Mutagen 24, 181-191. doi:10.1002/em.2850240307

Elje, E., Hesler, M., Runden-Pran, E. et al. (2019). The comet assay applied to HepG2 liver spheroids. Mutat Res Genet Toxicol Environ Mutagen 845, 403033. doi:10.1016/j.mrgentox.2019.03.006

Ellis-Hutchings, R., Giuliani, J., Hayashi, M. et al. (2018). The role of ethyl acrylate induced GSH depletion in the rodent forestomach and its impact on MTD and in vivo genotoxicity in developing an adverse outcome pathway (AOP). Regul Toxicol Pharmacol 92, 173-181. doi:10.1016/j.yrtph.2017.11.012

FDA/CDER (2013). Pharmacology Review(s): Secondary pharmacology and toxicology review for NDA 204‐820. https://www.accessdata.fda.gov/drugsatfda_docs/nda/2014/204820Orig1s000PharmR.pdf

Fowler, P., Smith, K., Young, J. et al. (2012). Reduction of misleading (“false”) positive results in mammalian cell genotoxicity assays. I. Choice of cell type. Mutat Res 742, 11-25. doi:10.1016/j.mrgentox.2011.10.014

Gi, M., Fujioka, M., Kakehashi, A. et al. (2018). In vivo positive mutagenicity of 1,4-dioxane and quantitative analysis of its mutagenicity and carcinogenicity in rats. Arch Toxicol 92, 3207-3221. doi:10.1007/s00204-018-2282-0

Goncharova, R. I., Zabrejko, S., Kozachenko, V. I. et al. (1988). Mutagenic effects of dimethyl terephthalate on mouse somatic cells in vivo. Mutat Res 204, 703-709. doi:10.1016/0165-1218(88)90076-6

Graupner, A., Instanes, C., Dertinger, S. D. et al. (2014). Single cell gel electrophoresis (SCGE) and Pig-a mutation assay in vivo-tools for genotoxicity testing from a regulatory perspective: A study of benzo[a]pyrene in Ogg1(-/-) mice. Mutat Res Genet Toxicol Environ Mutagen 772, 34-41. doi:10.1016/j.mrgentox.2014.07.010

Guillouzo, A., Corlu, A., Aninat, C. et al. (2007). The human hepatoma heparg cells: A highly differentiated model for studies of liver metabolism and toxicity of xenobiotics. Chem Biol Interact 168, 66-73. doi:10.1016/j.cbi.2006.12.003

Gunness, P., Mueller, D., Shevchenko, V. et al. (2013). 3D organotypic cultures of human heparg cells: A tool for in vitro toxicity studies. Toxicol Sci 133, 67-78. doi:10.1093/toxsci/kft021

Guo, X., Heflich, R. H., Dial, S. L. et al. (2016). Quantitative analysis of the relative mutagenicity of five chemical constituents of tobacco smoke in the mouse lymphoma assay. Mutagenesis 31, 287-296. doi:10.1093/mutage/gev039

Guo, X., Seo, J. E., Petibone, D. et al. (2020). Performance of HepaRG and HepG2 cells in the high-throughput micronucleus assay for in vitro genotoxicity assessment. J Toxicol Environ Health A 83, 702-717. doi:10.1080/15287394.2020.1822972

Habas, K., Brinkworth, M. H. and Anderson, D. (2017). In vitro responses to known in vivo genotoxic agents in mouse germ cells. Environ Mol Mutagen 58, 99-107. doi:10.1002/em.22075

Hartmann, A. and Speit, G. (1997). The contribution of cytotoxicity to DNA-effects in the single cell gel test (comet assay). Toxicol Lett 90, 183-188. doi:10.1016/s0378-4274(96)03847-7

Hu, T., Kaluzhny, Y., Mun, G. C. et al. (2009). Intralaboratory and interlaboratory evaluation of the EpiDerm 3D human reconstructed skin micronucleus (RSMN) assay. Mutat Res 673, 100-108. doi:10.1016/j.mrgentox.2008.12.003

IARC (1993). Some naturally occurring substances: Food items and constituents, heterocyclic aromatic amines and mycotoxins. IARC Monogr Eval Carcinog Risks Hum 56, 165-242.

IARC (1994). Some industrial chemicals. IARC Monogr Eval Carcinog Risks Hum 60, 389-433.

IARC (1999). Re-evaluation of some organic chemicals, hydrazine and hydrogen peroxide. IARC Monogr Eval Carcinog Risks Hum 71.

IARC (2000). Some antiviral and antineoplastic drugs, and other pharmaceutical agents. IARC Monogr Eval Carcinog Risks Hum 76.

IARC (2012). Arsenic, metals, fibres, and dusts. IARC Monogr Eval Carcinog Risks Hum 100C, 121-145.

IARC (2013). Some chemicals present in industrial and consumer products, food and drinking-water. IARC Monogr Eval Carcinog Risks Hum 101, 9-549.

IARC (2019a). Isobutyl nitrite, beta-picoline, and some acrylates. IARC Monogr Eval Carcinog Risks Hum 122, 97-135.

IARC (2019b). Styrene, styrene-7,8-oxide, and quinoline. IARC Monogr Eval Carcinog Risks Hum 121, 37-295.

Itoh, S. and Hattori, C. (2019). In vivo genotoxicity of 1,4-dioxane evaluated by liver and bone marrow micronucleus tests and Pig-a assay in rats. Mutat Res Genet Toxicol Environ Mutagen 837, 8-14. doi:10.1016/j.mrgentox.2018.09.004

Ivanov, D. P., Parker, T. L., Walker, D. A. et al. (2014). Multiplexing spheroid volume, resazurin and acid phosphatase viability assays for high-throughput screening of tumour spheroids and stem cell neurospheres. PLoS One 9, e103817. doi:10.1371/journal.pone.0103817

Kanojia, D. and Vaidya, M. M. (2006). 4-nitroquinoline-1-oxide induced experimental oral carcinogenesis. Oral Oncol 42, 655-667. doi:10.1016/j.oraloncology.2005.10.013

Kirkland, D., Pfuhler, S., Tweats, D. et al. (2007). How to reduce false positive results when undertaking in vitro genotoxicity testing and thus avoid unnecessary follow-up animal tests: Report of an ECVAM workshop. Mutat Res 628, 31-55. doi:10.1016/j.mrgentox.2006.11.008

Kirkland, D. (2011). Improvements in the reliability of in vitro genotoxicity testing. Expert Opin Drug Metab Toxicol 7, 1513-1520. doi:10.1517/17425255.2011.627855

Kirkland, D., Kasper, P., Martus, H. J. et al. (2016). Updated recommended lists of genotoxic and non-genotoxic chemicals for assessment of the performance of new or improved genotoxicity tests. Mutat Res Genet Toxicol Environ Mutagen 795, 7-30. doi:10.1016/j.mrgentox.2015.10.006

Kirkland, D., Uno, Y., Luijten, M. et al. (2019). In vivo genotoxicity testing strategies: Report from the 7th international workshop on genotoxicity testing (IWGT). Mutat Res Genet Toxicol Environ Mutagen 847, 403035. doi:10.1016/j.mrgentox.2019.03.008

Koppen, G., Azqueta, A., Pourrut, B. et al. (2017). The next three decades of the comet assay: A report of the 11th international comet assay workshop. Mutagenesis 32, 397-408. doi:10.1093/mutage/gex002

Lauschke, V. M., Hendriks, D. F., Bell, C. C. et al. (2016). Novel 3D culture systems for studies of human liver function and assessments of the hepatotoxicity of drugs and drug candidates. Chem Res Toxicol 29, 1936-1955. doi:10.1021/acs.chemrestox.6b00150

Le Hegarat, L., Dumont, J., Josse, R. et al. (2010). Assessment of the genotoxic potential of indirect chemical mutagens in HepaRG cells by the comet and the cytokinesis-block micronucleus assays. Mutagenesis 25, 555-560. doi:10.1093/mutage/geq039

Le Hegarat, L., Mourot, A., Huet, S. et al. (2014). Performance of comet and micronucleus assays in metabolic competent HepaRG cells to predict in vivo genotoxicity. Toxicol Sci 138, 300-309. doi:10.1093/toxsci/kfu004

Leite, S. B., Wilk-Zasadna, I., Zaldivar, J. M. et al. (2012). Three-dimensional HepaRG model as an attractive tool for toxicity testing. Toxicol Sci 130, 106-116. doi:10.1093/toxsci/kfs232

Liu, W., Xi, J., Cao, Y. et al. (2019). An adaption of human-induced hepatocytes to in vitro genetic toxicity tests. Mutagenesis 34, 165-171. doi:10.1093/mutage/gey041

Malinen, M. M., Kanninen, L. K., Corlu, A. et al. (2014). Differentiation of liver progenitor cell line to functional organotypic cultures in 3D nanofibrillar cellulose and hyaluronan-gelatin hydrogels. Biomaterials 35, 5110-5121. doi:10.1016/j.biomaterials.2014.03.020

Mandon, M., Huet, S., Dubreil, E. et al. (2019). Three-dimensional HepaRG spheroids as a liver model to study human genotoxicity in vitro with the single cell gel electrophoresis assay. Sci Rep 9, 10548. doi:10.1038/s41598-019-47114-7

Manjanatha, M. G., Aidoo, A., Shelton, S. D. et al. (2006). Genotoxicity of acrylamide and its metabolite glycidamide administered in drinking water to male and female big blue mice. Environ Mol Mutagen 47, 6-17. doi:10.1002/em.20157

Martins, C., Cacao, R., Cole, K. J. et al. (2012). Estragole: A weak direct-acting food-borne genotoxin and potential carcinogen. Mutat Res 747, 86-92. doi:10.1016/j.mrgentox.2012.04.009

Masuda-Herrera, M. J., Dobo, K. L., Kenyon, M. O. et al. (2019). In vivo mutagenicity testing of arylboronic acids and esters. Environ Mol Mutagen 60, 766-777. doi:10.1002/em.22320

Mittelstaedt, R. A., Mei, N., Webb, P. J. et al. (2004). Genotoxicity of malachite green and leucomalachite green in female Big Blue B6C3F1 mice. Mutat Res 561, 127-138. doi:10.1016/j.mrgentox.2004.04.003

Monarca, S., Pool-Zobel, B. L., Rizzi, R. et al. (1991). In vitro genotoxicity of dimethyl terephthalate. Mutat Res 262, 85-92. doi:10.1016/0165-7992(91)90112-h

Moore, M. M., Amtower, A., Doerr, C. L. et al. (1988). Genotoxicity of acrylic acid, methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate in L5178Y mouse lymphoma cells. Environ Mol Mutagen 11, 49-63. doi:10.1002/em.2850110107

Moore, M. M., Pottenger, L. H. and House-Knight, T. (2019). Critical review of styrene genotoxicity focused on the mutagenicity/clastogenicity literature and using current organization of economic cooperation and development guidance. Environ Mol Mutagen 60, 624-663. doi:10.1002/em.22278

Morita, T. and Hayashi, M. (1998). 1,4-dioxane is not mutagenic in five in vitro assays and mouse peripheral blood micronucleus assay, but is in mouse liver micronucleus assay. Environ Mol Mutagen 32, 269-280. doi:10.1002/(sici)1098-2280(1998)32:3<269::aid-em10>3.0.co;2-8

Morita, T., Hamada, S., Masumura, K. et al. (2016). Evaluation of the sensitivity and specificity of in vivo erythrocyte micronucleus and transgenic rodent gene mutation tests to detect rodent carcinogens. Mutat Res Genet Toxicol Environ Mutagen 802, 1-29. doi:10.1016/j.mrgentox.2016.03.008

Muller, L., Kasper, P., Muller-Tegethoff, K. et al. (1994). The genotoxic potential in vitro and in vivo of the allyl benzene etheric oils estragole, basil oil and trans-anethole. Mutat Res 325, 129-136. doi:10.1016/0165-7992(94)90075-2

Nair, A. R., Degheselle, O., Smeets, K. et al. (2013). Cadmium-induced pathologies: Where is the oxidative balance lost (or not)? Int J Mol Sci 14, 6116-6143. doi:10.3390/ijms14036116

Ngo, L. P., Owiti, N. A., Swartz, C. et al. (2020). Sensitive cometchip assay for screening potentially carcinogenic DNA adducts by trapping DNA repair intermediates. Nucleic Acids Res 48, e13. doi:10.1093/nar/gkz1077

Nohmi, T. (2018). Thresholds of genotoxic and non-genotoxic carcinogens. Toxicol Res 34, 281-290. doi:10.5487/TR.2018.34.4.281

NTP (1993). Toxicology and carcinogenesis studies of p-nitrophenol (cas no. 100-02-7) in swiss-webster mice (dermal studies). Natl Toxicol Program Tech Rep Ser 417, 1-161. https://ntp.niehs.nih.gov/ntp/htdocs/lt_rpts/tr417.pdf

NTP (1998). NTP toxicology and carcinogenesis studies of technical grade sodium xylenesulfonate (cas no. 1300-72-7) in F344/N rats and B6C3F1 mice (dermal studies). Natl Toxicol Program Tech Rep Ser 464, 1-272. https://www.ncbi.nlm.nih.gov/pubmed/12579200

NTP (2022a). Testing Status of Dimethyl terephthalate 10553-L. https://ntp.niehs.nih.gov/go/ts-10553-l

NTP (2022b). Testing Status of 1,4-Dioxane 10568-P (TR-080). https://ntp.niehs.nih.gov/go/ts-10568-p

NTP (2022c). Testing Status of Phthalic anhydride 10421-A. https://ntp.niehs.nih.gov/go/ts-10421-a

OECD (2017). Overview on genetic toxicology TGs. OECD Series on Testing and Assessment, No. 238. OECD Publishing, Paris. doi:10.1787/9789264274761-en

OECD (2020). The in vivo erythrocyte Pig-a gene mutation assay – Part 1 – Detailed Review Paper and Retrospective Performance Assessment. Series on Testing and Assessment, No. 315. https://www.oecd.org/officialdocuments/publicdisplaydocumentpdf/?cote=env/jm/mono(2020)6&doclanguage=en

OEHHA (2015). Diaminotoluenes (DATs). The Office of Environmental Health Hazard Assessment (OEHHA). https://oehha.ca.gov/media/downloads/proposition-65/chemicals/082815diaminotolueneshid.pdf

Onami, S., Cho, Y. M., Toyoda, T. et al. (2014). Absence of in vivo genotoxicity of 3-monochloropropane-1,2-diol and associated fatty acid esters in a 4-week comprehensive toxicity study using F344 gpt delta rats. Mutagenesis 29, 295-302. doi:10.1093/mutage/geu018

Ott, L. M., Ramachandran, K. and Stehno-Bittel, L. (2017). An automated multiplexed hepatotoxicity and CYP induction assay using heparg cells in 2D and 3D. SLAS Discov 22, 614-625. doi:10.1177/2472555217701058

Ozcagli, E., Alpertunga, B., Fenga, C. et al. (2016). Effects of 3-monochloropropane-1,2-diol (3-MCPD) and its metabolites on DNA damage and repair under in vitro conditions. Food Chem Toxicol 89, 1-7. doi:10.1016/j.fct.2015.12.027

Parish, S. T., Aschner, M., Casey, W. et al. (2020). An evaluation framework for new approach methodologies (NAMs) for human health safety assessment. Regul Toxicol Pharmacol 112, 104592. doi:10.1016/j.yrtph.2020.104592

Peng, C., Arthur, D., Liu, F. et al. (2013). Genotoxicity of hydroquinone in A549 cells. Cell Biol Toxicol 29, 213-227. doi:10.1007/s10565-013-9247-0

Pfuhler, S., Fellows, M., van Benthem, J. et al. (2011). In vitro genotoxicity test approaches with better predictivity: Summary of an IWGT workshop. Mutat Res 723, 101-107. doi:10.1016/j.mrgentox.2011.03.013

Pfuhler, S., van Benthem, J., Curren, R. et al. (2020). Use of in vitro 3D tissue models in genotoxicity testing: Strategic fit, validation status and way forward. Report of the working group from the 7th international workshop on genotoxicity testing (IWGT). Mutat Res Genet Toxicol Environ Mutagen 850-851, 503135. doi:10.1016/j.mrgentox.2020.503135

Przybojewska, B., Dziubaltowska, E. and Kowalski, Z. (1984). Genotoxic effects of ethyl acrylate and methyl acrylate in the mouse evaluated by the micronucleus test. Mutat Res 135, 189-191. doi:10.1016/0165-1218(84)90120-4

Ramaiahgari, S. C., Waidyanatha, S., Dixon, D. et al. (2017). From the cover: Three-dimensional (3D) HepaRG spheroid model with physiologically relevant xenobiotic metabolism competence and hepatocyte functionality for liver toxicity screening. Toxicol Sci 159, 124-136. doi:10.1093/toxsci/kfx122

Robison, T. W., Heflich, R. H., Manjanatha, M. G. et al. (2021). Appropriate in vivo follow-up assays to an in vitro bacterial reverse mutation (ames) test positive investigational drug candidate (active pharmaceutical ingredient), drug-related metabolite, or drug-related impurity. Mutat Res Genet Toxicol Environ Mutagen 868-869, 503386. doi:10.1016/j.mrgentox.2021.503386

Schulte-Hubbert, R., Kupper, J. H., Thomas, A. D. et al. (2020). Estragole: DNA adduct formation in primary rat hepatocytes and genotoxic potential in HepG2-CYP1A2 cells. Toxicology 444, 152566. doi:10.1016/j.tox.2020.152566

Seo, J. E., Tryndyak, V., Wu, Q. et al. (2019). Quantitative comparison of in vitro genotoxicity between metabolically competent heparg cells and HepG2 cells using the high-throughput high-content cometchip assay. Arch Toxicol 93, 1433-1448. doi:10.1007/s00204-019-02406-9

Seo, J. E., Wu, Q., Bryant, M. et al. (2020). Performance of high-throughput cometchip assay using primary human hepatocytes: A comparison of DNA damage responses with in vitro human hepatoma cell lines. Arch Toxicol 94, 2207-2224. doi:10.1007/s00204-020-02736-z

Seo, J. E., Davis, K., Malhi, P. et al. (2021). Genotoxicity evaluation using primary hepatocytes isolated from rhesus macaque (Macaca mulatta). Toxicology 462, 152936. doi:10.1016/j.tox.2021.152936

Severin, I., Jondeau, A., Dahbi, L. et al. (2005). 2,4-diaminotoluene (2,4-dat)-induced DNA damage, DNA repair and micronucleus formation in the human hepatoma cell line HepG2. Toxicology 213, 138-146. doi:10.1016/j.tox.2005.05.021

Shah, U. K., Seager, A. L., Fowler, P. et al. (2016). A comparison of the genotoxicity of benzo[a]pyrene in four cell lines with differing metabolic capacity. Mutat Res Genet Toxicol Environ Mutagen 808, 8-19. doi:10.1016/j.mrgentox.2016.06.009

Shah, U. K., Mallia, J. O., Singh, N. et al. (2018). A three-dimensional in vitro HepG2 cells liver spheroid model for genotoxicity studies. Mutat Res Genet Toxicol Environ Mutagen 825, 51-58. doi:10.1016/j.mrgentox.2017.12.005

Shelby, M. D., Erexson, G. L., Hook, G. J. et al. (1993). Evaluation of a three-exposure mouse bone marrow micronucleus protocol: Results with 49 chemicals. Environ Mol Mutagen 21, 160-179. doi:10.1002/em.2850210210

Shi, J., Krsmanovic, L., Bruce, S. et al. (2011). Assessment of genotoxicity induced by 7,12-dimethylbenz(a)anthracene or diethylnitrosamine in the Pig-a, micronucleus and comet assays integrated into 28-day repeat dose studies. Environ Mol Mutagen 52, 711-720. doi:10.1002/em.20678

Shigano, M., Ishii, N., Takashima, R. et al. (2016). Results of rat Pig-a/PIGRET assay with a single dose regimen of 1,3-propane sultone and 2-acetyl aminofluorene. Mutat Res Genet Toxicol Environ Mutagen 811, 75-79. doi:10.1016/j.mrgentox.2016.04.001

Shimada, T. and Fujii-Kuriyama, Y. (2004). Metabolic activation of polycyclic aromatic hydrocarbons to carcinogens by cytochromes P450 1A1 and 1B1. Cancer Sci 95, 1-6. doi:10.1111/j.1349-7006.2004.tb03162.x

Slob, W. (2017). A general theory of effect size, and its consequences for defining the benchmark response (BMR) for continuous endpoints. Crit Rev Toxicol 47, 342-351. doi:10.1080/10408444.2016.1241756

Smart, D. J., Ahmedi, K. P., Harvey, J. S. et al. (2011). Genotoxicity screening via the γH2AX by flow assay. Mutat Res 715, 25-31. doi:10.1016/j.mrfmmm.2011.07.001

Stampar, M., Tomc, J., Filipic, M. et al. (2019). Development of in vitro 3D cell model from hepatocellular carcinoma (HepG2) cell line and its application for genotoxicity testing. Arch Toxicol 93, 3321-3333. doi:10.1007/s00204-019-02576-6

Suh, M., Proctor, D., Chappell, G. et al. (2018). A review of the genotoxic, mutagenic, and carcinogenic potentials of several lower acrylates. Toxicology 402-403, 50-67. doi:10.1016/j.tox.2018.04.006

Umemura, T., Kuroiwa, Y., Tasaki, M. et al. (2007). Detection of oxidative DNA damage, cell proliferation and in vivo mutagenicity induced by dicyclanil, a non-genotoxic carcinogen, using gpt delta mice. Mutat Res 633, 46-54. doi:10.1016/j.mrgentox.2007.05.007

Villarini, M., Pagiotti, R., Dominici, L. et al. (2014). Investigation of the cytotoxic, genotoxic, and apoptosis-inducing effects of estragole isolated from fennel (Foeniculum vulgare). J Nat Prod 77, 773-778. doi:10.1021/np400653p

Wang, H., Han, Q., Chen, Y. et al. (2021). Novel insights into cytochrome P450 enzyme and solute carrier families in cadmium-induced liver injury of pigs. Ecotoxicol Environ Saf 211, 111910. doi:10.1016/j.ecoenv.2021.111910

Wang, Y., Revollo, J., McKinzie, P. et al. (2018). Establishing a novel Pig-a gene mutation assay in L5178YTk+/- mouse lymphoma cells. Environ Mol Mutagen 59, 4-17. doi:10.1002/em.22152

Weng, M. W., Lee, H. W., Choi, B. et al. (2017). AFB1 hepatocarcinogenesis is via lipid peroxidation that inhibits DNA repair, sensitizes mutation susceptibility and induces aldehyde-DNA adducts at p53 mutational hotspot codon 249. Oncotarget 8, 18213-18226. doi:10.18632/oncotarget.15313

WHO (2021). Toxicological evaluation of certain veterinary drug residues in food. WHO Food Additives Series 45. http://www.inchem.org/documents/jecfa/jecmono/v45je04.htm

Wills, J. W., Long, A. S., Johnson, G. E. et al. (2016). Empirical analysis of BMD metrics in genetic toxicology part II: In vivo potency comparisons to promote reductions in the use of experimental animals for genetic toxicity assessment. Mutagenesis 31, 265-275. doi:10.1093/mutage/gew009

Yamamoto, M. and Wakata, A. (2016). Evaluation of in vivo gene mutation with etoposide using Pig-a and PIGRET assays. Mutat Res Genet Toxicol Environ Mutagen 811, 29-34. doi:10.1016/j.mrgentox.2016.06.006

Yusuf, A. T., Vian, L., Sabatier, R. et al. (2000). In vitro detection of indirect-acting genotoxins in the comet assay using Hep G2 cells. Mutat Res 468, 227-234. doi:10.1016/s1383-5718(00)00052-8