Abstract
Nicotine's genotoxic potential has been extensively studied in vitro. While the results of mammalian cell‐based studies have inferred that it can potentially damage chromosomes, in general and with few exceptions, adverse DNA effects have been observed primarily at supraphysiological concentrations in nonregulatory assays that provide little information on its mode‐of‐action (MoA). In this study, a modern‐day regulatory genotoxicity assessment was conducted using a flow cytometry‐based in vitro micronucleus (MN) assay, Good Laboratory Practice study conditions, Chinese hamster ovary cells of known provenance, and acceptance/evaluation criteria from the current OECD Test Guideline 487. Nicotine concentrations up to 3.95 mM had no effect on background levels of DNA damage; however, concentrations above the point‐of‐departure range of 3.94–4.54 mM induced increases in MN and hypodiploid nuclei, indicating a possible aneugenicity hazard. Follow‐up experiments designed to elucidate nicotine's MoA revealed cellular vacuolization, accompanying distortions in microtubules, inhibition of tubulin polymerization, centromere‐positive DNA, and multinucleate cells at MN‐inducing concentrations. Vacuoles likely originated from acidic cellular compartments (e.g., lysosomes). Remarkably, genotoxicity was suppressed by chemicals that raised the luminal pH of these organelles. Other endpoints (e.g., changes in phosphorylated histones) measured in the study cast doubt on the biological relevance of this apparent genotoxicity. In addition, three major nicotine metabolites, including cotinine, had no MN effects but nornicotine induced a nicotine‐like profile. It is possible that nicotine's lysosomotropic properties drive the genotoxicity observed in vitro; however, the potency and mechanistic insights revealed here indicate that it is likely of minimal physiological relevance for nicotine consumers. Environ. Mol. Mutagen. 2019. © 2019 The Authors. Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society.
Highlights
Nicotine is one of the principal alkaloids found in tobacco plants, and it represents a prevalent chemical constituent of cigarettes, smoking cessation aids, inhalers, oral tobacco products, heated tobacco products, and electronic nicotine delivery systems (Federal Food, Drug, and Cosmetic Act 2009)
While data generated in the bacterial reverse mutation (Ames) test consistently demonstrated that nicotine is non-mutagenic and purport a lack of direct DNA reactivity (Florin et al 1980; Riebe et al 1982; Doolittle et al 1995; Yim and Hee 2001), studies carried out in mammalian cells have generally inferred that it has the potential to damage chromosomes
Chinese hamster ovary (CHO)-WBL cells were exposed to concentrations of nicotine up to 9.86 mM for 24 hr prior to harvesting nuclei species for enumeration by flow cytometry
Summary
Nicotine is one of the principal alkaloids found in tobacco plants, and it represents a prevalent chemical constituent of cigarettes, smoking cessation aids, inhalers, oral tobacco products, heated tobacco products, and electronic nicotine delivery systems (Federal Food, Drug, and Cosmetic Act 2009). While data generated in the bacterial reverse mutation (Ames) test consistently demonstrated that nicotine is non-mutagenic and purport a lack of direct DNA reactivity (Florin et al 1980; Riebe et al 1982; Doolittle et al 1995; Yim and Hee 2001), studies carried out in mammalian cells have generally inferred that it has the potential to damage chromosomes. Other in vitro rodent cell studies revealed an apparent causal relationship between nicotine exposure and DNA damage (Mailhes et al 2000; Barley et al 2004; Sudheer et al 2007a, 2007b). The translatability of these rodent cell effects to human cell systems has been illustrated (Kleinsasser et al 2005; Ginzkey et al 2013; Sobkowiak et al 2014; Yu et al 2016). In vitro organotypic cell cultures (e.g., nasal, gingival, and respiratory cells) that partially recapitulate the cellular environment that is first
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
