The clastogenicity of 4NQO is cell-type dependent and linked to cytotoxicity, length of exposure and p53 proficiency

Abstract

4-Nitroquinoline 1-oxide (4NQO) is used as a positive control in various genotoxicity assays because of its known mutagenic and carcinogenic properties. The chemical is converted into 4-hydroxyaminoquinoline 1-oxide and gives rise to three main DNA adducts, N-(deoxyguanosin-8-yl)-4AQO, 3-(desoxyguanosin-N 2-yl)-4AQO and 3-(deoxyadenosin-N 6-yl)-4AQO. This study was designed to assess the shape of the dose–response curve at low concentrations of 4NQO in three human lymphoblastoid cell lines, MCL-5, AHH-1 and TK6 as well as the mouse lymphoma L5178Y cell line in vitro. Chromosomal damage was investigated using the in vitro micronucleus assay, while further gene mutation and DNA damage studies were carried out using the hypoxanthine–guanine phosphoribosyltransferase forward mutation and comet assays. 4NQO showed little to no significant increases in micronucleus induction in the human lymphoblastoid cell lines, even up to 55±5% toxicity. A dose–response relationship could only be observed in the mouse lymphoma cell line L5178Y after 4NQO treatment, even at concentrations with no reduction in cell viability. Further significant increases in gene mutation and DNA damage induction were observed. Hence, 4NQO is a more effective point mutagen than clastogen, and its suitability as a positive control for genotoxicity testing has to be evaluated for every individual assay.

Development and Application of TK6-derived Cells Expressing Human Cytochrome P450s for Genotoxicity Testing

“…However, AHH-1 cells and their derivate cells (including MCL-5 cells) contain a heterozygous mutation at the TP53 locus (Guest and Parry, 1999;Morris et al, 1996). Compared with TK6 cells, AHH-1 and MCL-5 cells showed a higher level of MN formation and lower cytotoxicity after 4-nitroquinoline 1oxide treatment (Brü sehafer et al, 2016), suggesting that the mutation may compromise the function of p53 and thus restrain the application of these cell lines in genotoxicity tests.…”

No difference in 4‐nitroquinoline induced tumorigenesis between germ‐free and colonized mice

“…4NQO is metabolically converted to 4-hydroxyaminoquinolone 1-oxide, which induces gene mutations through the formation of bulky adducts on purines. 27,28 Since we found no difference in the number and size of tumors in germ-free and conventionally housed mice, our data suggests that the oral microbiome does not play a role in altering the mutagenic properties of 4NQO. Our study followed a standard protocol for 4NQO induced oral cancer with a follow-up time of 10 weeks after the end of treatment.…”

“…There was no statistically significant difference in the number and size of tumors between germ‐free and conventionally housed mice ( P > 0.05). 4NQO is metabolically converted to 4‐hydroxyaminoquinolone 1‐oxide, which induces gene mutations through the formation of bulky adducts on purines . Since we found no difference in the number and size of tumors in germ‐free and conventionally housed mice, our data suggests that the oral microbiome does not play a role in altering the mutagenic properties of 4NQO.…”

Inhibitory Effects of Water Extracts of Longan Leaves on Mutation and Tyrosinase

“…For example, molasses has displayed antimutagenic activity against different mutagens induced mutations of S. typhimurium TA 98 and TA 100 [13]. In this study, 4-hydroxyaminoquinoline 1-oxide (4-NQO) produced the ultimate mutagenic compound, which binds to DNA generating stable quinoline-purine mono adducts [26]. On the other hand, 2-AA undergoes the biotransformation pathway by a cytochrome P450-dependent monooxygenase to produce a nitrene moiety, which can bind to DNA [13].…”