Mutagenicity Of Acrylonitrile Research Articles

Analysis of Biomarkers of DNA Damage and Mutagenicity in Mice Exposed to Acrylonitrile.

Acrylonitrile (ACN), which is a widely used industrial chemical, induces cancers in the mouse via unresolved mechanisms. For this report, complementary and previously described methods were used to assess in vivo genotoxicity and/or mutagenicity of ACN in several mouse models, including (i) female mice devoid of cytochrome P450 2E1 (CYP2E1), which yields the epoxide intermediate cyanoethylene oxide (CEO), (ii) male lacZ transgenic mice, and (iii) female (wild-type) B6C3F1 mice. Exposures of wild-type mice and CYP2E1-null mice to ACN at 0, 2.5 (wild-type mice only), 10, 20, or 60 (CYP2E1-null mice only) mg/kg body weight by gavage for 6 weeks (5 days/week) produced no elevations in the frequencies of micronucleated erythrocytes, but induced significant dose-dependent increases in DNA damage, detected by the alkaline (pH >13) Comet assay, in one target tissue (forestomach) and one nontarget tissue (liver) of wild-type mice only. ACN exposures by gavage also caused significant dose-related elevations in the frequencies of mutations in the hypoxanthine-guanine phosphoribosyltransferase (Hprt) reporter gene of T-lymphocytes from spleens of wild-type mice; however, Hprt mutant frequencies were significantly increased in CYP2E1-null mice only at a high dose of ACN (60 mg/kg) that is lethal to wild-type mice. Similarly, drinking water exposures of lacZ transgenic mice to 0, 100, 500, or 750 ppm ACN for 4 weeks caused significant dose-dependent elevations in Hprt mutant frequencies in splenic T-cells; however, these ACN exposures did not increase the frequency of lacZ transgene mutations above spontaneous background levels in several tissues from the same animals. Together, the Comet assay and Hprt mutant frequency data from these studies indicate that oxidative metabolism of ACN by CYP2E1 to CEO is central to the induction of the majority of DNA damage and mutations in ACN-exposed mice, but ACN itself also may contribute to the carcinogenic modes of action via mechanisms involving direct and/or indirect DNA reactivity.

Mutagenicity of acrylonitrile and its metabolite 2-cyanoethylene oxide in human lymphoblasts in vitro

The mutagenicity of the rat carcinogen acrylonitrile (ACN) and its metabolite 2-cyanoethylene oxide (CNEtO) was assessed in vitro in human lymphoblasts using the heterozygous thymidine kinase ( tk) locus as a genetic marker. ACN was tested in both the presence and absence of an Aroclor-induced rat-liver homogenate S9. In the absence of S9, ACN was not mutagenic over the concentration range tested (0.4–1.5 mM × 2 h). In the presence of S9, the mutagenic response of ACN was enhanced, resulting in a significant response at a concentration of 1.4 mM × 2 h. CNEtO, the proposed ultimate mutagenic metabolite of ACN, induced a significant mutagenic response without activation at 100 μM and 150 μM × 2 h. Two phenotypic classes of spontaneous and CNEtO-induced tk −/− mutants were observed; one class of mutants ( tk n) had a normal growth rate relative to wild-type while the second class ( tk s) grew at a slower rate. The molecular nature of these two phenotypic classes was investigated by Southern blot analysis. CNEtO-induced tk n mutant clones (11/12) and 7/9 tk n spontaneous mutants had no detectable alterations in their tk restriction fragment pattern. In contrast, 25/26 tk s mutants analyzed (spontaneous and CNEtO-induced) had lost a 14.8-kb polymorphic fragment of the + tk allele.

Metabolism and mutagenicity of acrylonitrile: An in vivo study

The mutagenic activity present in urine of animals treated with acrylonitrile (ACN) is tentatively related to the excretion of three urinary metabolites: thiocyanate (SCN-), hydroxyethylmercapturic acid (OH-MA), and cyanoethylmercapturic acid (CN-MA). It is shown that the route of administration and animal species affect SCN- excretion but not the excretion of hydroxyethyl- and cyanoethylmercapturic acids or the mutagenicity of urine from ACN-treated animals. Various pretreatments (phenobarbital, CoCl2, diethylmaleate, trichloroacetonitrile) decrease the mutagenicity of urine from ACN-treated animals and decrease the excretion of SCN- and OH-MA. None of the quantified urinary metabolites is responsible for urinary mutagenicity.

Role of glutathione in the in vivo and in vitro mutagenicity of acrylonitrile

Role of glutathione in the in vivo and in vitro mutagenicity of acrylonitrile

Mutagenicity of acrylonitrile in mouse

The capacity of acrylonitrile (ACN) to produce chromosome aberrations in mammals was studied in somatic and germ cells of male NMRI mice. Induction of chromosome aberrations was followed in bone marrow cells 6, 18, 24, 48 and 72 h after an i.p. injection of 20 or 30 mg/kg acrylonitrile, and polychromatic erythrocytes were examined for the presence of micronuclei 24, 30 and 48 h after injection. The dominant lethal test served to detect chromosome aberrations in meiotic and postmeiotic male germ cells. All the tests utilized yielded negative results, so that it may be concluded that acute treatment with acrylonitrile has no clastogenic effects on male mouse cells in vivo.

Effect of various factors influencing the mutagenicity of acrylonitrile (ACN)

Effect of various factors influencing the mutagenicity of acrylonitrile (ACN)

Impact of microsomal enzymes on the mutagenicity of acrylonitrile, butadiene and styrene

Impact of microsomal enzymes on the mutagenicity of acrylonitrile, butadiene and styrene

Mutagenicity of acrylonitrile: Milvy, P. & Wolff, M. (1977). Mutagenic studies with acrylonitrile. Mutation Res.48, 271

Mutagenicity of acrylonitrile: Milvy, P. & Wolff, M. (1977). Mutagenic studies with acrylonitrile. Mutation Res.48, 271

Liver extract mediated mutagenicity of acrylonitrile

Liver extract mediated mutagenicity of acrylonitrile

Liver extract mediated mutagenicity of acrylonitrile

The mutagenic activity of acrylonitrile vapours towards Salmonella typhimurium strains strictly depends upon the presence of a liver postmitochondrial fraction. The reversion rate varies according to the animal species from which the S9 fraction is obtained as well as to the pretreatment of the animals. The comparatively weak activating effect of the microsomal fraction and the inability of both SKF525A and carbon monoxide to inhibit the S9 mediated mutagenicity of acrylonitrile (ACN) suggest that the cytochrome P-450-dependent monooxygenases do not play a major role in the metabolic activation of ACN into a mutagenic intermediate (s).

Mutagenicity of acrylonitrile

Incubation of Salmonella typhimurium strains in an atmosphere of 0.2% gaseous acrylonitrile increased the numbers of his+ revertants/plate only in the presence of a fortified S9 liver fraction. The mutagenic effect was particularly pronounced with strains TA1530, TA1535 and TA1950 and much weaker with strains TA100, TA98 and TA1978. The results of bacterial fluctuation tests confirmed the necessity of the presence of S9 mix and showed the particular sensitivity of TA1530. The reversion rate varied with the S9 mix composition, the animal species utilized and the type of pretreatments applied to the animals. The mutagenicity of acrylonitrile in S. typhimurium is therefore microsome-mediated and is particularly discernable with strains sensitive to base-substitution mutagens.

Mutagenicity of acrylonitrile (cyanoethylene) in Escherichia coli

Mutagenicity of acrylonitrile (cyanoethylene) in Escherichia coli

Mutagenic studies with acrylonitrile

The mutagenicity of acrylonitrile (vinyl cyanide, propenenitrile) has been demonstrated in the Ames Salmonella typhimurium/liver microsome assay system. Acrylonitrile, in the presence of a mouse liver homogenate produced mutations in the TA 1535, TA 1538 and TA 1978 strains. Exposure of the bacteria was achieved by spotting the acrylonitrile on a “lawn” of Salmonella, by shaking a reaction mixture consisting of bacteria, liver homogenate and acrylonitrile, and by exposing the homogenate and bacteria to an atmosphere containing the acrylonitrile. Mutagenesis by this latter method was observed at exposures as low as 57 ppm, less than three times the TLV of 20 ppm that is designated in the United States.

Mutagenicity of acrylonitrile in bacteria

Mutagenicity of acrylonitrile in bacteria