Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0596263 (carcinogenesis)
 64,820 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The preparation and characteristics of compound-specific and group-specific antibodies against 7-alkylguanines (7-alkGua) are described. A compound-specific antibody against 7-methylguanine was prepared using a hapten bound to carrier protein through the N2 position. In a competitive enzyme-linked immunosorbent assay (ELISA) 7-methylguanine (7-MeGua) showed 50% inhibition (I50%) at 10 pmol/well at room temperature, but the inhibition was found to be 40 times better at 4 degrees C (I50% at 250 fmol/well). When the antibody was bound to protein A-Sepharose CL4B 7-MeGua was retained in immunoaffinity columns. A group-specific antibody to 7-alkGua was prepared using 7-(2-carboxyethyl)guanine (7-CEGua) bound to carrier protein via the carboxyl group. In a competitive ELISA, this antibody cross-reacted well with 7-CEGua, 7-ethylguanine (7-EtGua), 7-(2-hydroxyethyl)guanine (7-HOEtGua) and 7-(2',3'-dihydroxy)-propylguanine (7-DHPGua) and some inhibition was seen with 7-MeGua. Immunoaffinity columns prepared from this antibody retained a number of 7-alkGua of diverse structure. 7-EtGua in calf thymus DNA treated with diethylsulphate and ethylnitrosourea was isolated by immunoaffinity purification and quantified by HPLC-fluorescence. These results illustrate the potential of immunoaffinity purification for both individual DNA adducts and groups of adducts.
Carcinogenesis 1994 May
PMID:Preparation of compound-specific and group-specific antibodies to 7-methylguanine and related 7-alkylguanines and their use in immunoaffinity purification. 820 Jan 1

Cyanoethylene oxide (CEO), a putative toxic and carcinogenic metabolite of acrylonitrile, is a direct-acting mutagen. The focus of this study was to elucidate potential adducts responsible for the mutagenic effect of CEO by characterizing products from the reaction of CEO with nucleotides. The reaction of CEO with the 5'-monophosphates of deoxyguanosine, deoxyadenosine, deoxycytidine or deoxythymidine resulted in the formation of at least one adduct for each nucleotide. Using two-dimensional NMR spectroscopy and fast atom bombardment mass spectrometry, CEO-nucleotide adducts (approximately 25% modification) were characterized as 2-cyano-2-hydroxyethyl phosphodiesters. The isolate from the reaction of deoxyguanosine-5'-monophosphate (dGMP) with CEO contained a second adduct, identified as N7-(2-cyano-2-hydroxyethyl)-dGMP. Single and double strand breaks, which were observed in supercoiled pBR322 plasmid DNA exposed to CEO (> 50 mM), may arise following formation of cyanohydroxyethyl phosphotriester adducts. The characterization of these phosphodiester adducts in vitro may provide insight into the intermediates responsible for the genotoxic effect of CEO in vivo.
Carcinogenesis 1994 Feb
PMID:Characterization of phosphodiester adducts produced by the reaction of cyanoethylene oxide with nucleotides. 831 18

Many xenobiotics exert their toxic effects through interaction with DNA in the cells of the exposed organism. This interaction may lead to the formation DNA adducts. Some of these may give rise to mutations that initiate cell transformation and, ultimately, the formation of tumors. Sensitive methods for determining DNA adducts are indispensable for the study of chemical mutagenesis and carcinogenesis and for biomonitoring human exposure to genotoxic agents. Alkylating agents form an important class of genotoxic compounds. They react preferentially at the N7-position of guanine. Under neutral or acidic conditions, the adducts can be readily released from the DNA backbone as the free base N7-alkylguanine (N7-AlkGua). The imidazole ring of N7-alkyldeoxyguanosine (N7-AlkdGuo) can be opened under alkaline conditions, which results in formation of a more stable adduct in DNA. To develop immunochemical methods for the detection of N7-alkylations, we immunized mice with various alkylguanosines in the ring-opened form (RON7-AlkdGuo). Antibodies were selected to detect adducts in isolated DNA by competitive ELISA and in single cells by immunofluorescence microscopy (IFM). Various monoclonal antibodies were characterized in detail with respect to specificity and sensitivity toward methylated, ethylated, and hydroxyethylated DNAs. The antibodies showed extensive cross-reactivity toward N7-(m)ethyl- and N7-(2-hydroxyethyl)guanine modifications in the ring-opened form. The limits of detection in the direct and competitive ELISA were 5-10 and 1-2 adducts per 10(6) nucleotides, respectively. The detection limit of the IFM method was about 20 adducts per 10(6) nucleotides(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Determining N7-alkylguanine adducts by immunochemical methods and HPLC with electrochemical detection: applications in animal studies and in monitoring human exposure to alkylating agents. 831 36

Cyanoethylene oxide (CEO), the putative toxic and carcinogenic metabolite of acrylonitrile, is a direct-acting mutagen. CEO reacted with deoxythymidine (dT) to form a single adduct (approximately 3% dT modified). Using two-dimensional NMR spectroscopy and fast atom bombardment mass spectrometry, this adduct was identified as N3-(2-cyano-2-hydroxyethyl)deoxythymidine. Subsequently, degradation of the adduct yielded N3-(2,2-dihydroxyethyl)deoxythymidine, a hydrated form of N3-(oxoethyl)deoxythymidine. N3-(2-cyano-2-hydroxyethyl)deoxythymidine was also detected in the reaction of [2,3-14C]CEO with calf thymus DNA. Small UV peaks, not present in the control, were detected from the reaction of CEO with dA, dG and dC. However, neither their retention times nor spectral characteristics corresponded with the standards used in this study. Characterization of this cyano-hydroxyethyl adduct and its degradation product following in vitro exposure of nucleosides to CEO may provide insight as to the types of adducts that could be assessed as biomarkers in vivo, and the modifications responsible for the mutational effects of CEO.
Carcinogenesis 1993 Jul
PMID:Characterization of an adduct and its degradation product produced by the reaction of cyanoethylene oxide with deoxythymidine and DNA. 833 Mar 51

Immunoaffinity gels were prepared by coupling monoclonal antibody (Mab) EM-6-47 to protein A-Sepharose, and were used to make small columns retaining 3-alkyladenines (3-alkAde) of diverse structure. An analytical procedure for determination of 3-methyladenine (3-MeAde), 3-ethyladenine (3-EtAde), 3-(2-hydroxyethyl)adenine (3-HOEtAde) and 3-benzyladenine (3-BzAde) was developed. Deuterated internal standards (d3-3-MeAde, d5-3-EtAde, d4-3-HOEtAde and d7-3-BzAde) were synthesized and added to urine samples prior to immunoaffinity purification. 3-alkAde were separated and quantitated as tert-butyl-dimethylsilyl (TBDMS) derivatives by capillary gas chromatography-low resolution mass spectrometry (GC-MS). Detection limits for 3-MeAde, 3-EtAde and 3-HOEtAde were 0.2 pmol/ml urine and for 3-BzAde, 1 pmol/ml urine. Studies in two volunteers showed that 3-MeAde and 3-HOEtAde were excreted almost quantitatively (> 90%) within 24 h, that 3-EtAde was less well excreted (67-74%) and that 3-BzAde was poorly excreted (21-25%). Studies on basal levels of 3-alkAde urinary excretion in three volunteers showed that 3-MeAde was > 90% derived from the diet as the preformed product. 3-HOEtAde was present at approximately 10 nmol/day and was reduced to approximately 1 nmol/day when the diet was standardized suggesting that it is also dietary in origin. 3-BzAde was not detected in human urine. 3-EtAde was not only excreted at low levels (< 1 nmol/day) but was also only very slightly affected by diet. This general and sensitive method will be useful in biomonitoring studies in subjects exposed to alkylating agents of diverse structure.
Carcinogenesis 1993 Feb
PMID:Immunoaffinity purification and gas chromatography-mass spectrometric quantification of 3-alkyladenines in urine: metabolism studies and basal excretion levels in man. 843 61

We have used a combination of thin-layer chromatography (TLC) and high pressure liquid chromatography (HPLC) to achieve separation of 32P-postlabelled 7-methylguanine and 7-(2-hydroxyethyl)-guanine adducts. The level of these two adducts was determined in human total white blood cells (mean values 0.7 to 1.5 adducts per 10(7) normal nucleotides) and isolated lymphocytes (mean values 1.1 to 12 adducts per 10(7) normal nucleotides). The separation of these two adducts revealed that the level of 7-(2-hydroxyethyl)-guanine was twice the level of 7-methylguanine adducts in total white blood cells, whereas, in isolated lymphocytes it was at least four times more than the 7-methylguanine adduct. The combined level of these two adducts in the lymphocytes of non-smokers was 1.1 to 8.4 adducts per 10(7) normal nucleotides and in the lymphocytes of smokers, the level was 5.6 to 12 adducts per 10(7) normal nucleotides. We also report detection of three unidentified adducts in the samples analysed, and at least one of these adducts seemed to be related to smoking. The chromatographic behaviour and depurination at neutral pH indicated the probable 7-alkylguanine or 3-alkyladenine nature of these unidentified adducts.
Carcinogenesis 1996 Mar
PMID:Separation of 7-methyl- and 7-(2-hydroxyethyl)-guanine adducts in human DNA samples using a combination of TLC and HPLC. 863 Nov 34

A selected ion monitoring gas chromatography-mass spectrometry (GC-MS) procedure was developed to determine the interaction product formed by acrylonitrile (ACN) with the N-terminal amino group in haemoglobin. The product, N-(2-cyanoethyl)valine (CEV), was analysed following its release from the protein by a modified Edman degradation procedure. Quantitation was achieved using N-(2-cyanoethyl)-[2H8]Val-Leu-Ser as internal standard. The limit of detection of the assay was 1 pmol CEV/g globin. A close to linear dose-response relationship was found for adduct formation in rats treated with ACN by gavage. On the basis of a linear extrapolation, a dose of 1 mg/kg body wt yielded 248 pmol CEV/g globin. Two groups of workers who were exposed to ACN contained 1984 +/- SD 2066 (n = 9) and 2276 +/- SD 1338 (n = 7) pmol CEV/g globin respectively. These values were highly significantly greater (P < 0.01 following a one-way analysis of variance with a logarithmic transformation of the data) than those in a group of control workers in the same factory (31.1 +/- SD 18.5 pmol CEV/g globin, n = 11). The concentrations of N-terminal CEV in globin samples from 13 smoking and 10 non-smoking mothers and from their newborns were determined. Adduct levels in the smokers averaged 217 +/- 85.1 pmol CEV/g globin, significantly higher than the levels in non-smokers, which were undetectable. Individual values in the mothers were very highly correlated with the levels in their babies (which averaged 99.5 +/- 53.8 pmol CEV/g globin), which demonstrates that transplacental transfer of ACN occurs. Significant correlations were also found between the number of cigarettes smoked per day by the mother and the CEV levels in both the mothers' and newborns' globin. There was, however, no correlation between the CEV levels and those of the ethylene oxide adduct N-(2-hydroxyethyl)valine in samples from either the mothers or babies.
Carcinogenesis 1996 Dec
PMID:Monitoring of exposure to acrylonitrile by determination of N-(2-cyanoethyl)valine at the N-terminal position of haemoglobin. 900 3

The formation of N7-(2-hydroxyethyl)guanine (7-HEG) in DNA was investigated previously in target and non-target tissues of F-344 rats and B6C3F1 mice exposed to >/=ISOdia>/=10 p.p.m. concentrations of ethylene oxide (EO) using fluorescence-linked high-performance liquid chromatography [V.E. Walker et al. (1992) Cancer Res., 52, 4238-4334]. In order to study the dose-responses for 7-HEG at lower exposures, a highly sensitive and specific gas chromatography coupled with high-resolution mass spectrometry (GC-HRMS) assay was developed. DNA was extracted from liver, brain, lung and spleen of B6C3F1 mice and F-344 rats exposed to 0, 3, 10, 33 or 100 p.p.m. EO for 4 weeks (6 h/day, 5 days/week). Analysis of DNA from control rodents showed that endogenous 7-HEG varied from 0.2 +/- 0.1 to 0.3 +/- 0.2 pmol/micromol guanine in tissues of rats and mice. 7-HEG exhibited tissue- and species-specific dose-response relationships in EO-exposed animals. Linear dose-response relationships were evident in mouse liver, brain and spleen at exposures between 3 and 100 p.p.m. Mouse lung exhibited a slightly sublinear response between 33 and 100 p.p.m. EO. The relationships were linear in liver and spleen of rats between 3 and 100 p.p.m. EO, but were slightly sublinear in brain and lung between 33 and 100 p.p.m. EO. The number of 7-HEG adducts present in rats exposed to 3 p.p.m. EO was 5.3-12.5 times higher than endogenous 7-HEG in unexposed controls. In contrast, mice exposed to 3 p.p.m. EO only had 1.3- to 2.5-fold greater numbers of 7-HEG adducts. The factors driving the exposure-response relationships are also likely to affect carcinogenic and mutagenic responses of rodents to EO. Likewise, a better understanding of the relationships between 7-HEG derived from low exposures to EO and endogenously formed 7-HEG may be important for the accurate extrapolation of risk to humans.
Carcinogenesis 1999 Sep
PMID:Molecular dosimetry of endogenous and ethylene oxide-induced N7-(2-hydroxyethyl) guanine formation in tissues of rodents. 1046 25

The purposes of the present study were: (i) to investigate the potential use of several biomarkers as quantitative indicators of the in vivo conversion of ethylene (ET) to ethylene oxide (EO); (ii) to produce molecular dosimetry data that might improve assessment of human risk from exogenous ET exposures. Groups (n = 7/group) of male F344 rats and B6C3F1 mice were exposed by inhalation to 0 and 3000 p. p.m. ET for 1, 2 or 4 weeks (6 h/day, 5 days/week) or to 0, 40, 1000 and 3000 p.p.m. ET for 4 weeks. N:-(2-hydroxyethyl)valine (HEV), N:7-(2-hydroxyethyl) guanine (N7-HEG) and HPRT: mutant frequencies were assessed as potential biomarkers for determining the molecular dose of EO resulting from exogenous ET exposures of rats and mice, compared with background biomarker values. N7-HEG was quantified by gas chromatography coupled with high resolution mass spectrometry (GC-HRMS), HEV was determined by Edman degradation and GC-HRMS and HPRT: mutant frequencies were measured by the T cell cloning assay. N7-HEG accumulated in DNA with repeated exposure of rodents to 3000 p.p.m. ET, reaching steady-state concentrations around 1 week of exposure in most tissues evaluated (brain, liver, lung and spleen). The dose-response curves for N7-HEG and HEV were supralinear in exposed rats and mice, indicating that metabolic activation of ET was saturated at exposures >/=1000 p.p.m. ET. Exposures of mice and rats to 200 p.p.m. EO for 4 weeks (as positive treatment controls) led to significant increases in HPRT: mutant frequencies over background in splenic T cells from exposed rats and mice, however, no significant mutagenic response was observed in the HPRT: gene of ET-exposed animals. Comparisons between the biomarker data for both unexposed and ET-exposed animals, the dose-response curves for the same biomarkers in EO-exposed rats and mice and the results of the rodent carcinogenicity studies of ET and EO suggest that too little EO arises from exogenous ET exposure to produce a significant mutagenic response or a carcinogenic response under standard bioassay conditions.
Carcinogenesis 2000 Sep
PMID:Biomarkers of exposure and effect as indicators of potential carcinogenic risk arising from in vivo metabolism of ethylene to ethylene oxide. 1096 97

Long-term inhalation studies in rodents have presented unequivocal evidence of experimental carcinogenicity of ethylene oxide, based on the formation of malignant tumors at multiple sites. However, despite a considerable body of epidemiological data only limited evidence has been obtained of its carcinogenicity in humans. Ethylene oxide is not only an important exogenous toxicant, but it is also formed from ethylene as a biological precursor. Ethylene is a normal body constituent; its endogenous formation is evidenced by exhalation in rats and in humans. Consequently, ethylene oxide must also be regarded as a physiological compound. The most abundant DNA adduct of ethylene oxide is 7-(2-hydroxyethyl)guanine (HOEtG). Open questions are the nature and role of tissue-specific factors in ethylene oxide carcinogenesis and the physiological and quantitative role of DNA repair mechanisms. The detection of remarkable individual differences in the susceptibility of humans has promoted research into genetic factors that influence the metabolism of ethylene oxide. With this background it appears that current PBPK models for trans-species extrapolation of ethylene oxide toxicity need to be refined further. For a cancer risk assessment at low levels of DNA damage, exposure-related adducts must be discussed in relation to background DNA damage as well as to inter- and intraindividual variability. In rats, subacute ethylene oxide exposures on the order of 1 ppm (1.83 mg/m3) cause DNA adduct levels (HOEtG) of the same magnitude as produced by endogenous ethylene oxide. Based on very recent studies the endogenous background levels of HOEtG in DNA of humans are comparable to those that are produced in rodents by repetitive exogenous ethylene oxide exposures of about 10 ppm (18.3 mg/m3). Experimentally, ethylene oxide has revealed only weak mutagenic effects in vivo, which are confined to higher doses. It has been concluded that long-term human occupational exposure to low airborne concentrations to ethylene oxide, at or below current occupational exposure limits of 1 ppm (1.83 mg/m3), would not produce unacceptable increased genotoxic risks. However, critical questions remain that need further discussions relating to the coherence of animal and human data of experimental data in vitro vs. in vivo and to species-specific dynamics of DNA lesions.
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PMID:Carcinogenicity and genotoxicity of ethylene oxide: new aspects and recent advances. 1105 37


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