A mutation in the p53 tumor suppressor gene of AHH-1 tk+− human lymphoblastoid cells

Morris, Suzanne M.; Manjanatha, Mugimane G.; Shelton, Sharon D.; Domon, Olen E.; McGarrity, Lynda J.; Casciano, Daniel A.

doi:10.1016/0027-5107(96)00133-9

Cited by 18 publications

(8 citation statements)

References 21 publications

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“…AHH-1 is a human lymphoblastoid TK +/− cell line that constitutively expresses a high level of native CYP1A1 ( 18 ). AHH-1 cells carry a heterozygous mutation in the TP53 locus ( 19–21 ). The human lymphoblastoid cell line MCL-5 is derived from AHH-1 by stable transfection with human cytochromes (CYP1A2, CYP2A6, CYP3A4 and CYP2E1) and microsomal epoxide hydrolase ( 18 ).…”

Section: Methodsmentioning

confidence: 99%

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

Brüsehafer¹,

Manshian²,

Doherty

et al. 2015

MUTAGE

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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.

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Section: Methodsmentioning

confidence: 99%

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

Brüsehafer¹,

Manshian²,

Doherty

et al. 2015

MUTAGE

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“…The human lymphoblastoid AHH-1/TK þ/À and MCL-5 cell lines, which were established by Crespi and Thilly [1984], both originated from AHH-1 cells and both can be used for assaying TK mutation. MCL-5 is a p53 wild-type cell line, while AHH-1 is heterozygous for the p53 gene and expresses both wild-type and mutant (282Trp) p53 protein [Morris et al, 1996]. The spontaneous TK mutant frequency in AHH-1 cells is about 17 Â 10 À6 , which is fivefold higher than that of MCL-5 cells [Dobo et al, 1995].…”

Section: Role Of P53 In Maintaining Genomic Stabilitymentioning

confidence: 98%

Generation of loss of heterozygosity and its dependency on p53 status in human lymphoblastoid cells

Honma

2005

Environ and Mol Mutagen

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Loss of heterozygosity (LOH) is a critical event in the development of human cancers. LOH is thought to result from either a large deletion or recombination between homologous alleles during repair of DNA double-strand breaks (DSBs). These types of genetic alterations produce mutations in the TK gene mutation assay, which detects a wide mutational spectrum, ranging from point mutations to LOH-type mutations. TK6, a human lymphoblastoid cell line, is heterozygous for the thymidine kinase (TK) gene and has a wild-type p53 gene. The related cell lines, TK6-E6 and WTK-1, which are p53-deficient and p53-mutant (Ile237), respectively, are also heterozygous for the TK gene and LOH-type mutation can be detected in these cells. Therefore, comparative studies of TK mutation frequency and spectrum with these cell lines are useful for elucidating the role of p53 in generating LOH and maintaining genomic stability in human cells. We demonstrate here that LOH and its associated genomic instability strongly depend on the p53 status in these cells. TK6-E6 and WTK-1 are defective in the G1/S checkpoint and in apoptosis. Unrepaired DSBs that escape from the checkpoint can potentially initiate genomic instability after DNA replication, resulting in LOH and a variety of chromosome changes. Moreover, genomic instability is enhanced in WTK-1 cells. It is likely that the mutant p53 protein in WTK-1 cells increases LOH in a dominant-negative manner due to its abnormal recombination capacity. We discuss the mutator phenotype and genomic instability associated with p53 inactivation with the goal of elucidating the mechanisms of mutation and DNA repair in untargeted mutagenesis.

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“…However, a chronic study is likely to involve comparisons between smaller exposures, meaning a reduction effect is more difficult to detect within a dataset of the same size. That hormesis and adaptive responses should be regarded as distinct processes, rather than manifestations of a single process, is also reflected in studies in yeast, where a dose of hydrogen peroxide that induces a clear adaptive response to a subsequent high-dose challenge does not induce hormesis in the original sense of a biphasic curve from single exposures to each dose 37 . Thus, one may see hormetic treatments that do not induce an adaptive response, and one may see an adaptive response with no concomitant hormesis.…”

Section: J-shaped Dose-responses Are Observed Infrequently In Our Labmentioning

confidence: 98%

“…Previous publications have also identified the involvement of p53 in genotoxicity dose-responses for TK6 cells [28,31]. It is unclear whether p53 was responsible for Thomas et al's dose-response; unlike TK6 cells, AHH-1 cells are heterozygous for p53 function due to a base pair substitution at codon 282, with consequences including loss of the G1 checkpoint and delayed apoptotic cell death [37]. Indeed, more efficient repair of apurinic/apyrimidic sites by MPG in wild-type p53 cells than mutant p53 cells [38] may explain why a different mechanism may be responsible for Thomas et al's J-shaped dose-response.…”

Section: P53 Status May Contribute To the J-shaped Dose-responsementioning

confidence: 99%

Investigation of J-shaped dose-responses induced by exposure to the alkylating agent N -methyl- N -nitrosourea

Chapman

Hoffmann

Doak

et al. 2017

Mutation Research/Genetic Toxicology and Environmental Mutagene

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Hormesis is defined as a biphasic dose-response where biological effects of low doses of a stressor demonstrate the opposite effect to high-dose effects of the same stressor. Hormetic, or J-shaped, dose-response relationships are relatively rarely observed in toxicology, resulting in a limited understanding and even some skepticism of the concept. Low dose-response studies for genotoxicity endpoints have been performed at Swansea University for over a decade. However, no statistically significant decreases below control genotoxicity levels have been detected until recently. A hormetic-style dose-response following a 24h exposure to the alkylating agent N-methyl-N-nitrosourea (MNU) was observed in a previous study for HPRT mutagenesis in the human lymphoblastoid cell line AHH-1. A second recent study demonstrated a J-shaped dose-response for the induction of micronuclei by MNU in a 24h treatment in a similar test system. Following mechanistic investigations, it was hypothesized that p53 may be responsible for the observed hormetic phenomenon. As genotoxic carcinogens are a major causative factor of many cancers, consideration of hormesis in carcinogenesis could be important in safety assessment. The data examined here offer possible insights into hormesis, including its estimated prevalence, underlying mechanisms and lack of generalizability.

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A mutation in the p53 tumor suppressor gene of AHH-1 tk+− human lymphoblastoid cells

Cited by 18 publications

References 21 publications

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

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

Generation of loss of heterozygosity and its dependency on p53 status in human lymphoblastoid cells

Investigation of J-shaped dose-responses induced by exposure to the alkylating agent N -methyl- N -nitrosourea

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