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Background: Doxorubicin is a widely used anticancer drug due to its broad spectrum of antitumor activity. Various mechanisms have been proposed for its cytostatic activity, including DNA intercalation, topoisomerase II inhibition, generation of free radicals and apoptosis. The present study aims to further clarify the cytostatic activity of doxorubicin by its specific effect on (a) DNA damage, (b) micronucleation and (c) apoptosis, using a combination of different methods and cell systems such as human lymphocytes and HL-60 human leukemic cells. DNA lesions were analyzed by the alkaline comet assay in combination with formamidopyrimidine (Fpg) and human 8-oxoguanine (hOGG1) repair enzymes. Micronucleation was investigated by the Cytokinesis-Block Micronucleus assay (CBMN) in combination with Fluorescence In Situ Hybridization analysis. Impairment on mitotic apparatus was investigated by double immunofluorescence of β- and γ-tubulin. Apoptotic cell frequency was determined by the CBMN cytome assay. Complementary to the above, caspase-3 level was investigated by Western blot., Results: It was found that doxorubicin generates DNA breakage induced by oxidative damage in DNA bases, which can be repaired by the Fpg and hOGG1 enzymes. Increased micronucleus frequency was identified mainly through chromosome breakage and, at a lesser extent, through chromosome delay. Analysis of mitotic spindle showed disturbance of chromosome orientation and centrosome duplication and/or separation, leading to aneuploidy. Enhanced frequency of apoptotic leukemic cells was also observed. Caspase-3 seems to be involved in the generation of apoptosis., Conclusions: The aforementioned findings derived from different treatment schedules, doses and time of exposure on primary versus transformed cells extend our knowledge about doxorubicin genotoxicity and contribute to the better understanding of the mechanisms by which doxorubicin induces genotoxic effects on human cells.

We have recently shown that retinoic acid induces micronucleation mainly via chromosome breakage (Alakhras et al. Cancer Lett 2011; 306: 15-26). To further study retinoic acid clastogenicity and evaluate DNA damaging potential we investigated the ability of (a) all-trans retinoic acid and its steroidal analogue EA-4 to induce DNA fragmentation by using Comet assay under alkaline unwinding and neutral condition electrophoresis, and (b) the retinoids under study to induce small (0-1 kb) DNA fragments. Two cell lines, C2C12 mouse cells and HL-60 human leukemic cells were used in this study. We found that all-trans retinoic acid and its steroidal analogue EA-4 (a) provoke DNA migration due to DNA fragmentation as it is shown by the increased values of Comet parameters, and (b) induce significantly small-size fragmented genomic DNA as indicated by the quantification of necrotic/apoptotic small DNA segments in both cell systems. A different response between the two cell lines was observed in relation to retinoid ability to increase the percentage of DNA in the tail as well as break DNA in to small fragments. Our findings confirm the ability of retinoic acid to provoke micronucleation by disrupting DNA into fragments, among which small pieces of double-stranded DNA up to 1 kb are identified., (Copyright © 2013 John Wiley & Sons, Ltd.)

We have comparatively investigated the aneugenic activity of two anticancer drugs, nocodazole (NOC) and paclitaxel (PTX), and the antifungal griseofulvin with promising role in cancer treatment (GF), which affect microtubule dynamics in different ways. The comparison was achieved in HFFF2 human fibroblasts, MCF-7 human breast cancer cells and C2C12 mouse myoblasts, and focused on three issues: (i) induction of chromosome delay by estimation of MN frequency using CREST analysis; (ii) disturbance of spindle organization with Aurora-A/β-tubulin immunofluorescence; and (iii) alterations in the expression of Aurora-A, β- and γ-tubulin by western blotting. They induced chromosome delay, provoked metaphase arrest and promoted microtubule disorganization, reflecting their common characteristic of generating aneuploidy. In particular, NOC induced mainly monopolar metaphases, although PTX induced only multipolar metaphases. GF generated different types of abnormal metaphases, exhibiting cell specificity. Additionally, NOC decreased the expression of Aurora-A and β-tubulin, while the opposite held true for PTX and GF. γ-Tubulin expression was not modulated owing to NOC treatment, whereas PTX and GF increased γ-tubulin expression. Our findings throw a light on the manifestation of the aneugenicity of the studied compounds through centrosome proliferation/separation and protein expression, reflecting their different effects on microtubule dynamics., (Copyright © 2012 John Wiley & Sons, Ltd.)

Previous findings showed that the anticancer drugs p-N,N-bis(2-chloroethyl) amino-l-phenylalanine (melphalan, MEL) and p-N,N-bis(2-chloroethyl)aminophenylbutyric acid (chlorambucil, CAB) belonging to the nitrogen mustard group, in addition to their clastogenic activity, also exert aneugenic potential, nondisjunction and chromosome delay. Their aneugenic potential is mainly mediated through centrosome defects. To further investigate their aneugenicity we (a) studied whether apoptosis is a mechanism responsible for the elimination of damaged cells generated by MEL and CAB and (b) investigated if proteins that regulate chromosome segregation are involved in the modulation of their aneugenic potential. Apoptosis was studied by Annexin-V/Propidium Iodide staining and fluorescence microscopy. The involvement of apoptosis on the exclusion of cells with genetic damage and centrosome disturbances was analyzed by DAPI staining and immunofluorescence of β- and γ-tubulin in the presence of pan-caspase inhibitor. The expressions of Aurora-A, Aurora-B, survivin and γ-tubulin were studied by western blot. We found that (a) apoptosis is not the mechanism of choice for selectively eliminating cells with supernumerary centrosomes, and (b) the proteins Aurora-A, Aurora-B and survivin are involved in the modulation of MEL and CAB aneugenicity. These findings are important for the understanding of the mechanism responsible for the aneugenic activity of the anticancer drugs melphalan and chlorambucil., (Copyright © 2011 John Wiley & Sons, Ltd.)

The aim of our study is to: (a) investigate whether ATRA and its steroidal analogue EA-4 enhance micronucleation in human lymphocytes and mouse cells in vitro and clarify the micronucleation mechanism by FISH and CREST analysis respectively, and (b) analyze their effect on spindle organization by immunofluorescence of β- and γ-tubulin in mouse cells. We found that they: (a) induce micronucleation mainly via chromosome breakage and chromosome delay in a lesser extent, (b) disturb microtubule network, chromosome orientation and centrosome duplication/separation, (c) accumulate cell cycle at ana-telophases, which exert micronucleation, multiple γ-tubulin signals, nucleoplasmic bridges and multinucleation, and (d) generate multinucleated and multimicronucleated interphase cells., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

p-N,N-bis(2-chloroethyl)aminophenylacetic acid (PHE), a nitrogen mustard analogue and chlorambucil's active metabolite used as chemotherapeutic agent, has been shown that, in addition to its clastogenic activity, induces chromosome delay. In the present study an efford has been made (a) to investigate if the steroidal analogues of PHE (EA-92, EA-97, AK-333, AK-409 and AK-433) exert the same genetic activity as the parent compound, (b) to further analyze the aneugenic activity of nitrogen mustard analogues, (c) to investigate the mechanism by which they exert aneugenic potential and (d) to correlate the genetic activity with chemical structure. For this purpose the Cytokinesis Block Micronucleus (CBMN) assay was conducted in human lymphocytes in vitro and the micronucleus (MN) frequency was determined to investigate their genetic activity. The mechanism of micronucleation was determined in combination with Fluorescence In Situ Hybridization (FISH) using pancentromeric DNA probe. Since one of the mechanisms that chemicals cause aneuploidy is through alterations in the mitotic spindle, we also investigated the effect of the above compounds on the integrity and morphology of the mitotic spindle using double immunofluorescence of beta- and gamma-tubulin in C(2)C(12) mouse cell line. We found that PHE and its steroidal analogues, EA-92, EA-97, AK-333, AK-409 and AK-433, affect cell proliferation in human lymphocytes and C(2)C(12) mouse cells. All studied compounds are capable of inducing chromosome breakage events, as indicated by the enhanced C(-)MN frequencies. The less lipophilic compounds are the most genetically active molecules. PHE and only two of the studied analogues, AK-409 and AK-433, the most hydrophilic ones, showed aneugenic potential, by increasing the frequencies of MN containing a whole chromosome. The aneugenic potential of the above referred analogues is associated with amplification of centrosome number, since they caused high multipolar metaphase frequencies., (Copyright 2010 Elsevier B.V. All rights reserved.)

Melphalan (MEL), chlorambucil (CAB) and p-N,N-bis(2-chloroethyl)aminophenylacetic acid (PHE) are nitrogen mustard analogues, which are clinically used as chemotherapeutic agents. They also exert carcinogenic activity. The aim of this study was to investigate the aneugenic potential of the above drugs and the possible mechanism responsible for this activity. The Cytokinesis Block Micronucleus (CBMN) assay in combination with fluorescence in situ hybridization (FISH) was used in human lymphocyte cultures to evaluate micronucleus (MN) frequency. Pancentromeric probe (alpha-satellite) was applied to identify chromosomes in micronuclei and an X-chromosome specific centromeric probe was used to asses micronucleation and non-disjunction of this chromosome in binucleated cells. The effect of the above compounds on the organization of mitotic apparatus, as a possible target of chemicals with aneugenic potential, was investigated in C(2)C(12) mouse cell line by double immunofluorescence of alpha- and gamma-tubulin. We found that the studied drugs increased MN frequency in a linear dose-dependent manner primarily by chromosome breakage and in a lesser extent by an aneugenic mechanism. Non-disjunction and micronucleation of X-chromosome were also induced. Abnormal metaphase cells were linearly increased with concentration and characterized by abnormal centrosome number. Interphase cells with micronuclei and abnormal centrosome number were also observed. Since nitrogen mustards are highly reactive agents, with low selectivity and form covalent bonds with different nucleophilic sites in proteins and nucleic acids, it is reasonable to consider that one possible pathway for nitrogen mustard analogues to exert their aneugenic activity is through reaction with nucleophilic moieties of proteins or genes that are involved in the duplication and/or separation of centrosomes, resulting in abnormal centrosome number. Based on our results the carcinogenicity of nitrogen mustard analogues studied may be attributed not only to their activity to trigger gene mutation and chromosome breakage, but also to their aneugenic potential. Further studies are warranted to clarify the above two hypotheses.

Hypertension is often treated with diuretics, like hydrochlorothiazide (HCTZ). Previous results on the in vitro genotoxicity of HCTZ are equivocal. In the present study, we have evaluated the genotoxicity of HCTZ in cultured human lymphocytes using the Cytokinesis Blocked Micronucleus (CBMN) assay. In addition, micronucleus (MN) induction was analyzed by Fluorescence In Situ Hybridization (FISH) with an alpha-satellite DNA centromeric probe to distinguish between clastogenic and aneugenic effects. Lymphocyte cultures from 32 healthy adults were exposed to 5 and 40 microg/ml HCTZ. Age, gender, and smoking were evaluated as factors affecting the MN analysis. We found that HCTZ increased MN frequencies. FISH analysis revealed that HCTZ exerts its genotoxicity more strongly at the 40 microg/ml concentration, and principally through chromosome delay (aneugenicity). Multiregression analysis of our results confirmed the known effect of age and gender on MN induction in human lymphocytes. Smoking was also a confounding factor for MN induction, especially for centromere-negative MN frequencies. Under the experimental conditions used, only age had a clear positive effect on the response of lymphocytes to HCTZ. These data indicate that HCTZ produces micronuclei in cultured human lymphocytes by a mechanism that involves chromosome delay and to a lesser extent through chromosome breakage., ((c) 2005 Wiley-Liss, Inc.)

We report a 72-year-old male patient with a 47,XYY/45,X/46,XY mosaicism associated with short stature, exostoses, type E brachydactyly, gynecomastia, cryptorchidism, mild mental retardation, and a paranoid personality and conversion disorder. Since his prevalent cell line was 47,XYY (about 75%), our patient could be karyotypically classified as a case of 47,XYY syndrome. In view of the striking similarity of the clinical features of this case and those of a XYY case previously reported by Ikegawa et al (1992), it seems reasonable to suggest that these patients are representatives of a novel syndrome with a XYY karyotype.

CYP1A1 plays an important role in the metabolic activation of polycyclic aromatic hydrocarbons (PAH), carcinogenic components of air pollution. The influence of CYP1A1 genotype (*2A, *2B and *4) on the levels of lymphocyte bulky DNA adducts and the frequency of cells with aberrant chromosomes was assessed in 194 non-smoking subjects in whom recent exposure to environmental tobacco smoke (ETS) and airborne particulate-associated PAH were measured during two consecutive seasons (winter and summer). While CYP1A1*4 had no consistent effect on either biomarker of genetic damage, the levels of both biomarkers responded in a parallel fashion to changes in exposure/CYP1A1*2A genotype combinations during both seasons. Specifically, the levels of both biomarkers were increased in carriers of at least one CYP1A1*2A allele, as compared with CYP1A1*1 homozygotes, in subjects with ETS exposures >0.8 h/day during the previous 4 days and mean personal exposure to benzo[a]pyrene <0.9 ng/m3 during the previous 24 h (all P < 0.05). Outside these exposure limits the differential effect in CYP1A1*2A variants was lost. Although the numbers of subjects with the CYP1A1*2B polymorphism was small, the same trend appeared to be followed in this case. These effects are interpreted as resulting from differential induction of CYP1A1 expression in CYP1A1*2A and CYP1A1*2A/*2B carriers by components of ETS-polluted air at levels of exposure readily suffered by large segments of the general population and suggest that subjects with these genotypes may have increased susceptibility to the genotoxic effects of ETS.

Three steroidal esters with a common alkylating agent (chlorambucil's active metabolite, PHE) and PHE were studied with regard to their genetic activity in human lymphocyte cultures treated in vitro. The cytokinesis block micronucleus assay was used in combination with fluorescence in situ hybridization and the cytosine arabinoside method (ARA-C). The aim of this study was (i) to examine if the modified analogs (EA-72 and SOT-19) of the parent compound (ASE) exerted the same genetic activity with ASE and to correlate the genetic activity with the chemical structure, (ii) to investigate whether these steroidal esters are able to induce excision repairable lesions, through the alkylation of DNA, and (iii) to collect data in order to evaluate the exact role of the steroidal skeleton on the expression of the antileukemic activity. We found that PHE and its steroidal esters are cytotoxic for human lymphocyte cultures, as indicated by the reduction of Cytokinesis Blocked Proliferation Index, PHE being the most cytotoxic molecule. All studied compounds are capable of inducing both chromosome breakage and chromosome delay as indicated by the increased CMN and CMN frequencies. The steroidal derivatives gave reduced genetic activity. The conjugate ketone at the B ring of the steroidal skeleton resulted in decreased genetic activity mainly due to decreased chromosome delay. All studied compounds are capable of inducing DNA excision repair.

Acitretin is widely used in the systemic treatment of severe forms of psoriasis and other skin disorders. ASE, namely 3beta-hydroxy-13alpha-amino-13,17-seco-5alpha-androstan-17-oic-13,17-lactam-p-bis(2-chloro-ethyl)amino phenylacetate (AzaSteroidalEster, NSC-71964), is an alkylating agent with antineoplastic activity and mutagenic properties. The aim of this study was to investigate the possible genotoxic and/or antigenotoxic effects of acitretin in human lymphocyte cultures in vitro, using sister chromatid exchange (SCE) and cytokinesis-blocked micronucleus (CBMN) assays. Micronucleus (MN) analysis was achieved in combination with fluorescence in situ hybridization (FISH), using an alpha-satellite DNA pancentromeric probe. It was found that acitretin alone demonstrated no clastogenic or aneugenic activity. However, simultaneous incubation of lymphocyte cultures with ASE and acitretin resulted in a reduction of ASE-induced SCEs. For MN analysis lymphocytes were treated with ASE and acitretin at 21 and 41 h after culture initiation, corresponding to G1 and G2 phases, respectively, and lasted until cell harvest. Acitretin caused a decrease in ASE-induced MN when treatment of cells started at 41 h, but exerted no effect on them when treatment started at 21 h. These findings suggest that acitretin exerts antigenotoxic effects in human lymphocyte cultures, the expression of which may be related to the cycle phase of the cells upon onset and duration of the treatment, at least as far as MN frequency is concerned.

Little is known about the impact of genetic variation on the genetic damage induced by urban air pollution or environmental tobacco smoke (ETS) in exposed populations. The levels of bulky DNA adducts ( 32P-postlabelling, nuclease P1 enrichment) and chromosomal aberrations were measured in lymphocytes of 194 non-smoking students living in the city of Athens, and the rural region of Halkida, Greece. In these individuals personal exposure to PAH was also measured. Furthermore, genetic polymorphisms were examined in cytochromes P450 1A1, 1B1, in the GSTM1, GSTP1 and GSTT1 as well as in microsomal epoxy hydrolase (EPHX) genes. Subjects with the CYP1*2A mutant genotype also suffering significant ETS exposure tended to exhibit higher adduct levels and % aberrant cells. In contrast, CYP1B1 polymorphisms seemed to have an impact on the DNA adduct levels only among individual with negligible ETS exposure. Subjects carrying both the CYP1*2A mutant genotype and the GSTM1 null genotype tended to have higher DNA adduct levels. A similar effect was also observed with the combined CYP1A1*2A/GSTP1 (Ile/Val) and the CYP1A1*2A/mEH "slow" polymorphisms. In both cases, the effect was more pronounced among subjects with higher levels of ETS exposure. Stepwise restriction of the observations to subjects characterised by (a) GSTP1 mutant, (b) GSTM1 null, (c) mEH "slow" (His139His) genotypes and (d) ETS exposure resulted in a significant trend of increasing DNA adduct levels only among individuals with at least one CYP1A1*2A mutated allele, illustrating the importance and complexity of gene-exposure and gene-gene interactions in determining the level of genotoxic damage on an individual levels.

Fluorescence in situ hybridization (FISH) was used to evaluate spontaneous and aneuploidogen-induced micronucleus frequencies and non-disjunction of chromosomes X and 8 in cultured binucleated lymphocytes of women of two age groups. Demecolcine and vincristine were used as model aneuploidogens to induce micronuclei and chromosome malsegregation. Four of the women were aged 22-26 (mean 24.3) years and four 47-50 (mean 49.0) years. Pancentromeric FISH was applied to micronuclei to identify chromosomes and double-color centromeric FISH, performed in binucleates of two young and two older women, was used to assess the involvement of chromosomes X and 8 in micronuclei and non-disjunction. It was confirmed that age increases micronucleus frequency. Micronuclei containing whole chromosomes predominated in older females. Age also enhanced micronuclei containing acentric chromosome fragments. The inclusion of chromosomes X and 8 in micronuclei was enhanced by age and chromosome X was generally overrepresented. Non-disjunction of chromosomes X and 8 also increased with age, chromosome X being the more sensitive. Treatment of lymphocytes with vincristine and demecolcine increased micronucleus frequency and malsegregation of chromosomes X and 8 in both age groups. Comparison of the estimated frequencies of micronucleation and non-disjunction for all human chromosomes showed that non-disjunction is the main type of chromosome malsegregation.

Epidemiologic studies indicate that prolonged exposure to high pollution levels is associated with increased risk of cancer, especially lung cancer. However, under conditions of moderate or low air pollution, epidemiologic evidence does not permit reliable conclusions. Biomarker-based population studies may serve as complementary tools providing a better understanding of the relative contribution of ambient atmospheric pollution to the overall genotoxic burden suffered by city dwellers. However, past efforts to apply biomarkers to studies of low levels exposure to urban air pollution have given inconclusive results, partly because of the absence of adequate data on personal exposure, covering a time-window which is appropriate for the biomarkers being examined, as well as a battery of biomarkers reflecting different stages of the carcinogenic process. In the present paper, the potential of biomarker-based population studies to aid the assessment of the genotoxic and carcinogenic effects of urban air pollution is reviewed by reference to the achievements and limitations of earlier reported studies. The design and methodology adopted in a recently completed large-scale population study, carried out in the context of the European Union Environment and Climate Programme, known by the short name of AULIS project, is discussed and descriptive statistics of the main findings of the project are presented. These findings indicate that for cohorts suffering moderate-to-low exposures to airborne particulate-bound polycyclic aromatic hydrocarbons (PAHs), no simple correlation with biomarkers of genotoxicity existed and suggest that additional factors made a significant contribution to the overall genotoxic burden.

3beta - Hydroxy - 13alpha - amino - 13, 17 - seco - 5alpha - androstan - 17 -oic-13,17-lactam-p-bis(2-chloroethyl)amino phenylacetate (ASE) is a homo-aza-steroidal ester of p-bis(2-chloroethyl) amino phenyl acetic acid and has been shown to display antineoplastic, mutagenic and genotoxic activity. In the present study an effort has been made to evaluate the ability of ASE to induce micronuclei (MN) in human lymphocytes treated in vitro using the cytokinesis-block assay. Lympocytes were treated with different concentrations of ASE (0.1, 0.25, 0.5, 1, 2.5, 5, 10 and 20 microg/ml) at two different cell culture times, 21 and 41 h after culture initiation. ASE treatment lasted until cell harvest, for 51 and 31 h, respectively. Two types of cultures were used, whole blood and isolated lymphocyte cultures. The content of induced MN was identified by FISH analysis, using an alpha-satellite DNA probe, in binucleate cells. Our results suggest that ASE is capable of increasing MN frequencies in human lymphocytes under both culture conditions. This increase is related to the concentration in a linear dose-dependent manner and is also dependent on the duration of treatment. FISH analysis has shown that the induced MN resulted mainly from breakage events. Additionally, a weak aneugenic effect was found at the higher concentrations in whole blood cultures as well as in isolated lymphocyte cultures. Cytotoxic effects of ASE were observed under both cell culture conditions with a linear dose-dependent relationship according to CBPI evaluation and were more pronounced in isolated lymphocyte cultures.

The association of occupational exposure to 1,3-butadiene (BD) and induction of cytogenetic damage in peripheral lymphocytes was studied in 19 male workers from a monomer production unit and 19 control subjects from a heat production unit. The exposure to BD was measured by passive personal monitors. The following biomarkers were used: chromosomal aberrations (CA), sister chromatid exchanges (SCE), cells with a high frequency of SCE (HFC), micronuclei, comet assay parameters like tail length (TL) and percentage of DNA in tail [T (%)] and polymorphisms of GSTM1 and GSTT1 genotypes. BD exposure with a median value of 0.53 mg/m3 (range: 0.024-23.0) significantly increased (a) the percentage of cells with chromosomal aberrations in exposed vs. control groups (3.11% vs. 2.03%, P<0.01), (b) the frequency of SCE per cell (6.96 vs. 4.87, P<0.001), and (c) the percentage of HFC (19.9% vs. 4.1%, P<0.001). BD exposure had no significant effects on formation of micronuclei and on comet assay parameters. Effect of smoking was observed only for HFC in BD-exposed group. GSTM1 genotype affected chromosomal aberrations in exposed group, while GSTT1 genotype affected chromosomal aberrations in controls. No effect of GSTM1 or GSTT1 genotypes was observed on any other biomarkers used., (Copyright 1998 Elsevier Science B.V.)

The ability of cetirizine dihydrochloride, an antihistaminic agent, to induce chromosome aberrations as well as sister chromatid exchanges (SCEs) was evaluated in human lymphocyte cultures treated in vitro. The following concentrations were tested: 25, 50, 75, 100 and 200 micrograms/ml. The results of our study revealed that cetirizine dihydrochloride is capable of inducing chromosome aberrations, at least at the higher concentrations studied, 100 and 200 micrograms/ml. The majority of aberrations was of chromatid type. Cetirizine is also a weak inducer of SCEs. Further studies are now warranted in order to define the in vivo cytogenetic activity of cetirizine in humans.

The effect of different 1,3-butadiene (BD) inhalation doses, 130, 250, and 500 ppm, on somatic cells of mice was studied. Two different cell populations with diverse replicative and differentiative activities, namely splenocytes and peripheral blood reticulocytes, were examined and micronucleus (MN) frequencies were estimated. In splenocytes, different postinhalation time intervals were studied with regard to MN induction and characterisation. BD was found to be clastogenic by inducing increased micronucleus frequencies in both cell compartments and also to induce cytotoxicity at the highest level of exposure. In mouse splenocytes, BD has also shown a weak aneugenic effect at a short time interval after the exposure. Postinhalation time influences the induction of chromosome damage in stimulated splenocytes treated in vivo, since MN frequency decreases with time; in addition, BD has shown its aneugenic and cytotoxic potential only at 2 days after exposure.

A summary of the results of the studies conducted in the EU Project "Multi-endpoint analysis of genetic damage induced by 1,3-butadiene and its major metabolites in somatic and germ cells of mice, rats and man" is presented. Results of the project are summarized on the detection of DNA and hemoglobin adducts, on the cytotoxic and clastogenic effects in somatic and germinal cells of mice and rats, on the induction of somatic mutations at the hprt locus of experimental rodents and occupationally exposed workers, on the induction of dominant lethal mutations in mice and rats, and on heritable translocations induced in mice, after exposure to butadiene (BD) or its major metabolites, butadiene monoepoxide (BMO), diepoxybutane (DEB) and butadiene diolepoxide (BDE). The primary goal of this project was to collect experimental data on the genetic effects of BD in order to estimate the germ cell genetic risk to humans of exposure to BD. To achieve this, the butadiene exposure are based on data for heritable translocations and bone marrow micronuclei induced in mice and chromosome aberrations observed in lymphocytes of exposed workers. A doubling dose for heritable translocations in human germ cells of 4900 ppm/h is estimated, which, assuming cumulative BD exposure over the sensitive period of spermatogenesis, corresponds to 5-6 weeks of continuous exposure at the workplace to 20-25 ppm. Alternatively, the rate of heritable translocation induction per ppm/h of BD exposure is estimated to be approximately 0.8 per million live born, compared to a spontaneous incidence of balanced translocations in humans of approximately 800 per million live born. These estimates have large confidence intervals and are only intended to indicate orders of magnitude of human genetic risk. These risk estimates are based on data from germ cells of BD-exposed male mice. The demonstration that clastogenic damage was induced by DEB in preovulatory oocytes at doses which were not ovotoxic implies that additional studies on the response of mammalian female germ cells to BD and its metabolites are needed. The basic assumption of the above genetic risk estimates is that experimental mouse data obtained after BD exposure can be extrapolated to humans. Several points exist in the present report and in the literature which contradict this assumption: (1) the level of BMO-hemoglobin adducts was significantly elevated in BD-exposed workers; however, it was considerably lower than would have been predicted from comparable rat and mouse exposures; (2) the concentrations of the metabolites DEB and BMO were significantly higher in mouse than in rat blood after BD exposure. Thus, while metabolism of BD is qualitatively similar in the two species, it is quantitatively different; (3) no increase of HPRT mutations was shown in 19 workers exposed on average to 1.8 ppm of BD, while in a different population of workers from a US plant exposed on average to 3.5 ppm of BD, a significant increase of HPRT variants was detected; and (4) data from cancer bioassays and cancer epidemiology suggest that rat is a more appropriate model than mouse for human cancer risk from BD exposure. However, the dominant lethal study in rats gave a negative result. At present, we do not know which BD metabolite(s) may be responsible for the genetic effects even though the bifunctional alkylating agent DEB is the most likely candidate for the induction of clastogenic events. Unfortunately, methods to measure DEB adducts in hemoglobin or DNA are only presently being developed. Despite these several uncertainties the use of the mouse genetic data is regarded as a justifiable and conservative approach to human genetic risk estimation given the considerable heterogeneity observed in the biotransformation of BD in humans.

3,4-Epoxy-1-butene (EB) is one of the main metabolites of 1,3 butadiene, a widely used industrial chemical. The mutagenic potential of 1,3 butadiene and its metabolites have been studied in different test systems. In this work the genotoxic effects of EB were studied by estimating micronuclei (MN) and sister chromatid exchange (SCE) frequencies in stimulated mouse splenocytes. Mice were treated in vivo with various doses of EB (24.4, 48.8 and 73.2 mg/kg). The antikinetochore antibody technique (CREST) was also applied to MN in cytokinesis blocked cells to investigate any possible aneugenic effect. Both MN and SCE frequencies increased after EB treatment. The induced MN resulted mainly from acentric fragments but a weak aneugenic effect was found as well. Cytotoxic effects of EB were observed at the highest dose. The above results, in combination with others on the effect of 1,3 butadiene and its metabolites in somatic and germ cells of mouse and rat as well as in somatic human cells, form a part of the information needed for application of the parallelogram approach and extrapolation to human risk.

The role of the glutathione S-transferase T1 gene (GSTT1) in determining genotoxic response to 1,2:3,4-diepoxybutane (DEB), an epoxide metabolite of 1,3-butadiene, was studied by analysis of micronuclei (MN) in cultured human lymphocytes using the cytokinesis block method. Fluorescence in situ hybridization (FISH) with an alphoid satellite DNA probe specific for the centromeres of all human chromosomes was applied to identify MN harboring whole chromosomes. Whole-blood lymphocyte cultures of 11 GSTM1 (glutathione S-transferase M1)-positive individuals (i.e. having at least one GSTM1 allele), of whom six were GSTT1-positive (with at least one GSTT1 allele) and five GSTT1-null (GSTT1 homozygously deleted), were treated for 48 h (starting 24 h after culture initiation) with two different concentrations (2 and 5 muM) [corrected] of DEB. The GSTT1-null individuals were excessively sensitive to DEB, showing, on average, approximately 2.5 times higher induced MN frequency (control frequency subtracted) than the GSTT1-positive donors, both at 2 muM [corrected] (mean/1000 binucleate cells 29.8 versus 11.8, P < 0.05) and 5 muM [corrected] (87.6 versus 34.0, P < 0.001) DEB. In accordance with the known strong clastogenicity of DEB, MN without centromeric FISH signals were particularly increased, the difference between the two GSTT1 genotypes being statistically significant at both concentrations of DEB (mean induced MN/1000 binucleate cells 23.1 versus 9.9, P < 0.05, at 2 muM [corrected]; 69.7 versus 24.2, P < 0.001, at 5 muM) [corrected]. In addition, centromere-positive (C+) MN were induced, suggesting that DEB also has some aneuploidogenic activity. The GSTT1-null genotype showed a significantly (P < 0.05) higher mean frequency of induced C+ MN than the GSTT1-positive genotype, at both 2 (6.7 versus 1.9) and 5 muM [corrected] (17.9 versus 9.8) DEB. At the higher dose mean nuclear division index was lower in the GSTT1-null group (1.80) than in the GSTT1-positive group (2.05, P < 0.01). These findings support earlier results from the analysis of sister chromatid exchange showing that individual sensitivity to the genotoxic and cytotoxic effects of DEB is largely explained by lack of the GSTT1 gene.

The alkylating agent m-N,N-bis(2-chloroethyl)aminocinnamic acid (m-ACA) and four new homo-aza-steroidal esters were studied for their ability to induce chromosomal abnormalities and to affect protein synthesis in human lymphocytes in vitro. A mitotic index reduction and an increase in the total number of aberrations were observed. Analysis of chromosomal abnormalities has shown that these are mainly chromatid breaks. A decrease in protein synthesis was also observed that seems to fit with the order of activity of the above compounds reflected in the induction of chromosomal aberrations. The observation that protein synthesis and the induction of chromosomal aberrations are affected by these chemicals may reflect interactions between these molecules and DNA that result in structural chromosome changes and decreased protein synthesis.

N-Nitroso-compounds are a large group of chemicals present in a number of environmental sources and many of them are mutagens as well as carcinogens in experimental animals. Among the known N-nitroso-compounds, N-nitroso-N-methylurea (MNU) is a strong mutagen. In this study an effort has been made to compare the ability of MNU to methylate the O6-guanosine site in DNA and to induce micronuclei and sister chromatid exchanges in human lymphocyte cultures in vitro. To quantitate O6-methyldeoxyguanosine (O6-mdG) a highly sensitive immunoassay, immuno-slot-blot (ISB), has been used. For the evaluation of micro nuclei (MN) the cytokinesis block micronucleus method has been used. Different concentrations (75, 100, 125 micrograms/ml) were tested. At the highest concentration tested for the MN induction, 125 micrograms/ml, the occurrence of binucleates and micro nuclei is higher than twice in relation to control and a reduction in NDI is also observed. The same concentrations were used for the estimation of sister chromatid exchanges (SCEs) induction. The mean number of SCEs at 125 micrograms/ml is almost three times that of the control level. The concentrations tested for the quantitation of O6-mdG were 200, 300 and 400 micrograms/ml and this was done because for the test system we used and for the given experimental conditions the first indication of O6-mdG formation was at 200 micrograms/ml. Our results show that methylation of O6-guanosine increases with concentration and at 400 micrograms/ml the concentration of O6-mdG is 5.83 fmol/microgram DNA, while at the control level it is 2.40 fmol/microgram DNA. Since O6-mdG formation is observed in higher concentrations than those of MN and SCE induction it would be interpreted that O6-mdG levels are not correlated with the studied cytogenetic effects although one has to take into consideration the total promutagenic lesions in DNA, induced by MNU, as well as AGT repair activity.

Blood samples were collected twice (in 1993 and 1994) from 19 workers exposed to 1,3-butadiene and 19 matched controls. Three exposed and three control subjects were the same in 1993 and 1994. Personal passive dosimetry was performed in 1993 and twice in 1994 on the day preceding blood sampling. Mean exposure level in 1994 was 1.76 +/- 4.20 ppm (S.D.) and individual exposure levels ranged between 0.012 ppm (detection limit) and 19.77 ppm. Using the clonal assay, geometric mean of hprt mutant frequencies adjusted for cloning efficiency, age and smoking were, respectively, 7.85 (+/- 7.09) x 10(-6) and 10.14 (+/- 9.16) x 10(-6) in pooled (1993 plus 1994) exposed and control subjects. The difference was not statistically significant indicating that 1,3-butadiene did not induce a detectable increase in mutations at the hprt locus. A similar result was obtained for the 1994 subjects alone. There was no difference between adjusted geometric mean mutant frequencies of exposed and unexposed non-smokers or between exposed and unexposed smokers. Analysis of chromosomal aberrations in lymphocytes from 1994 subjects indicated that the percentage of aberrant cells was significantly enhanced in exposed subjects. In 1993 (data not shown), it was impossible to demonstrate a significant increase of aberrant cells in subjects exposed to 1,3-butadiene. Frequencies of micronuclei in cytochalasin-B blocked binucleate lymphocytes in exposed and unexposed 1994 subjects were not significantly different. This was also the case for earlier samples analyzed in the same plant. Using the comet assay for 1994 subjects, no statistically significant difference was found between the whole group of exposed and unexposed subjects. This was true for both the comet tail length and the percentage of DNA in the tail. In exposed smokers, however, the comet tail length was significantly longer than in unexposed smokers. Unexpectedly, in unexposed smokers the tail length was significantly shorter than in unexposed non-smokers. It was also unexpected that the percentage of DNA in the comet tail was significantly lower in exposed non-smokers than in unexposed non-smokers.

Many of the cytostatic drugs commonly used in cancer chemotherapy treatments have been shown to be genotoxic in vivo and in vitro. We present a cytogenetic collaborative study on 13 cancer patients treated with different antitumor agents. For comparison we also carried out a cytogenetic analysis on 14 healthy untreated controls. The frequency of sister chromatid exchanges and structural chromosome aberrations in peripheral blood lymphocytes of the cancer patients was determined prior to the treatment, just after it and 3-7 weeks later. The results obtained show clear differences between the basal levels of cytogenetic alterations in cancer patients, even though the mean value is higher in this group than the basal levels of the group of healthy individuals. Treatment with cytostatics increases the frequency of both cytogenetic biomarkers analyzed, which declined to values similar to those initially observed several weeks after the treatment. Our data are in qualitative and quantitative agreement with other results previously found by other authors.

1,3-Butadiene (BD) is an important industrial chemical and environmental contaminant, e.g. in urban air, traffic exhausts and tobacco smoke. It has been shown to be genotoxic in vitro and in vivo and carcinogenic in rodents, mice being more sensitive than rats. The present study confirmed this species difference. Using micronuclei in erythrocytes or bone marrow as a marker, mice responded at an effective level of 50 p.p.m., while the highest ineffective level in rats was 500 p.p.m. (inhalation of BD for 5 days). A dose-dependent increase in N-terminal valine haemoglobin adducts was seen in both rats and mice, but the adduct levels in the latter species were on average five times higher. For the first time, specific N6-alkyldeoxyadenosine adducts were identified in lung and liver DNA of rats exposed to BD by inhalation. No significant difference in DNA adduct level was seen in lung tissue of rats and mice at similar exposure levels. Occupational exposure levels to BD in the European Process industry are variable, but generally < 1 p.p.m. Haemoglobin adduct levels were seen to be increased among the worker groups with higher potential exposure to BD (process work, bomb voiding and repair duties) as compared with adduct levels in less exposed workers in maintenance and the laboratory or control personnel. However, the N-terminal valine haemoglobin adducts measured in the workers were one to two orders of magnitude lower than extrapolated for the same exposure dose in mice. In the same workers no exposure-related effects were seen in the cytogenetic parametres studied, i.e. chromosomal aberrations, sister chromatid exchanges or micronuclei in peripheral blood lymphocytes, or in the Ras oncoprotein levels of plasma samples. The studies so far conducted suggest that human exposure at the levels seen in the present day process industry can be documented at the biological dose level using haemoglobin adduct measurement, but not at the biological effect level using cytogenetic biomarkers. In order to quantitate the human genotoxic risk of BD exposure more work needs to be done on the role of other active BD metabolites than 1,2-epoxy-3-butene and on the genetic polymorphisms controlling the variability of individual responses.

The association of occupational exposure to 1,3-butadiene and chromosomal damage in peripheral blood lymphocytes was studied in 40 workers from two production facilities. Control persons, 30 in all, were chosen from other departments of the same plants, and they were roughly matched for age and smoking habits. The exposure levels to ambient butadiene were measured both by personal sampling using diffuse monitors and by stationary sampling at production and handling sites. Chromosome aberrations (CA), micronuclei (MN) and sister-chromatid exchanges (SCE) in peripheral lymphocytes were analyzed as markers of exposure. Smoking had a slight effect on the frequency of MN, and the mean frequency of SCEs was also higher in smokers than in non-smokers. No effect of smoking, however, was seen in relation to chromosomal aberrations. No exposure related effects were seen in any of the three cytogenetic endpoints in either of the butadiene production plants, representing typical low (below 3 ppm) exposure levels of the butadiene manufacturing industry.

The clastogenic activity of the antineoplastic alkylating agent 3 beta-hydroxy-13 alpha-amino-13,17-seco-5 alpha-androstan-17-oic-13,17-lactam- p-bis (2-chloroethyl) aminophenoxy acetic acid (NSC 294859) and its congeners was studied in human lymphocyte cultures in vitro. Cells were exposed to several concentrations of the drugs for 24 h. It was found that NSC 294859 reduces the mitotic index and causes chromosome- as well as chromatid-type aberrations in a dose-dependent way. From its congeners, the alkylating agent (p-bis(2-chloroethyl)aminophenoxy acetic acid) induces the same phenomena but to a lesser extent, while the modified steroid (3 beta-hydroxy-13 alpha-amino-13,17-seco-5 alpha-androstan-17-oic-13,17-lactam) causes cytogenetic damages at the control level. These results favour the assumption that the antitumour activity of NSC 294859 is mainly based on its cytogenetic effects.

Four new chemicals, the homo-aza-steroidal esters of m-N,N-bis(2-chloroethyl)aminocinnamic acid, originaly synthesized to be used as antineoplastic agents, were tested for their mutagenic activity in the Ames test. 3 beta-Hydroxy-13 alpha-amino-13,17-seco-5-androsten-17-oic-13,17- lactam ester (ACALE3) and 3 alpha-hydroxy-13 alpha-amino-13,17-seco-5 alpha-androstan-17-oic-13,17-lactam ester of m-N,N-bis(2-chloroethyl)aminocinnamic acid (ACALE4) were found to induce base-pair substitutions, causing dose-dependent increases in his+ revertants in strains TA100 and TA1535, while no dose-dependent relations were established when 3 beta-hydroxy-13 alpha-amino-13,17-seco-5 alpha-androstan-17-oic-13,17-lactam ester (ACALE1) and 17 beta-hydroxy-3-aza-A-homo-4 alpha-androsten-4-one ester of m-N,N-bis(2-chloroethyl)aminocinnamic acid (ACALE2) were tested. The presence of metabolic activation enzymes in the test system had no effect in his+ revertants in strains TA100 and TA1535. The chemicals tested although having the same alkylating moiety and a similar chemical structure exhibited different mutagenic activities.

The mutagenic activity of the new antitumour agent 3 beta-hydroxy-13 alpha-amino-13,17-seco-5 alpha-androstan-17-oic-13,17-lactam- p-N,N-bis(2-chloroethyl)aminophenoxyacetate (NSC 294859) was studied in the Salmonella/microsome assay. It was found to induce base pair substitutions, causing dose-dependent increases in his+ revertants in strains TA100 and TA1535. The alkylating moiety, p-N,N-bis(2-chloroethyl)-aminophenoxyacetic acid, was shown to be less effective than the parent compound, while the modified steroid moiety, 3 beta-hydroxy-13 alpha-amino-13,17-seco-5 alpha-androstan-17-oic-13,17-lactam, showed no mutagenic effect in all strains used. The presence of metabolic activation enzymes in the test system induced a further increase in his+ revertants in strains TA100 and TA1535, in both the parent compound and the alkylating moiety of the parent compound, while it had no effect in the case of the steroidal lactam.

The ortho, meta and para isomers of N,N-bis(2-chloroethyl)aminocinnamic acid were tested for their ability to mutate Salmonella typhimurium strains in the Salmonella/microsome mutagenicity test. The aim of the work was to establish a structure-activity relationship between these three isomers. The drugs were found to induce base-pair substitutions, causing dose-dependent increases in his+ revertants, in strains TA100 and TA1535. The study showed that the position of the substituent groups influenced the mutagenic activity of the compounds. The ortho isomer exhibited a poorer mutagenic effect than meta and this was found to be a weaker mutagen than para. The presence of metabolic activation enzymes in the test system induced a further increase in his+ revertants, in strains TA100 and TA1535, which is consistent with the findings for melphalan, a cancer chemotherapeutic agent with a chemical structure similar to that of the isomers tested.

The genotoxic activity of the new antineoplastic alkylating agent 3 beta-hydroxy-13 alpha-amino-13,17-seco-5 alpha-androstan-17-oic-13,17- lactam-p-bis-(2-chloroethyl) aminophenoxyacetate (NSC 294859) was studied in the somatic mutation and recombination test (SMART) in Drosophila melanogaster. The drug was administered to larvae which were transheterozygous for two recessive wing cell markers mwh and flr3. Several concentrations were tested and two of them showed a clear induction of mosaic spots, expressing the mutant phenotypes. Multiple wing hair (mwh) spots were the main type observed but twin spots and flares (flr3) spots were also detected. We conclude that the compound induces both mutations and somatic recombination in the SMART test.

1. The effect of two homo-aza-steroidal esters with antineoplastic activity, namely 3 beta-hydroxy-13 alpha-amino-13,17-seco-5 alpha-androstan-17-oic-13,17-lactam-p-bis(2-chloroethyl)aminoph enoxyacetate (NSC 294859) and 3 beta-hydroxy-13 alpha-amino-13,17-seco-5 alpha-androstan-17-oic-13,17-lactam-p-bis(2-chloroethyl)aminoph enylacetate (ASE) on protein synthesis rate was studied in ovaries of Drosophila melanogaster females. 2. Two different concentrations for each compound were examined. 3. Both esters containing the same alkylating agent have been shown to decrease protein synthesis in relation to control.

Neocarzinostatin (NCS), a chemotherapeutic antibiotic, was investigated for the ability to induce chromosomal aberrations and sister-chromatid exchanges (SCEs) in human lymphocyte cultures. It was observed that the antibiotic causes a cell-cycle delay and reduces the mitotic index. Analysis of the induced chromosomal abnormalities showed that they are mainly chromosome and chromatid breaks; while the frequency of SCEs was increased, the magnitude indicates that NCS cannot be considered a potent inducer of SCEs.

The cytogenetic effects of homo-aza-steroidal ester (ASE) on Chinese hamster ovary (CHO) cells in vitro are reported. It was found that treatment of cells with a dose as low as 0.025 micrograms/ml of ASE causes a significant number of abnormal metaphases containing mostly chromatid-type aberrations. Similarly, significant frequencies of SCE were induced with only 0.075 micrograms/ml of ASE.

3 beta-Hydroxy-13 alpha-amino-13,17-seco-5 alpha-androstan-17-oic-13,17-lactam-p-bis(2-chloroethyl) aminophenoxyacetate (NSC 294859) is a new modified steroidal alkylating agent. This compound was given by i.p. administration to mice bearing different types of tumour. It was found to exhibit good activity in L1210 and P388 leukaemias with maintenance of activity against advanced tumours. The treatment of colon 26 tumour and B16 melanoma resulted in positive antineoplastic activity. The drug was not shown to be active in a melphalan-resistant P388 line. In this study, NSC 294859 was found to be effective in causing statistically significant increases in sister-chromatid exchange (SCE) rates and cell division delays. The alkylating agent component, p-bis-(2-chloroethyl)aminophenoxy acetic acid, was shown to be less effective than the parent compound, while the modified steroid component, 3 beta-hydroxy-13 alpha-amino-13,17-seco-5 alpha-androstan-17-oic-13,17-lactam, showed no effect. There were no statistically significant differences among donors regarding the induction of SCEs and replication indices (RIs) for the compounds tested.

Tallysomycin is an antibiotic compound structurally related to bleomycin, and like bleomycins and phleomycins also shows antitumour activity. We have investigated the genetic activity of tallysomycin in the ascomycete Aspergillus nidulans for malsegregation of chromosomes at mitosis and for point mutations. We found that the antibiotic at very low concentrations from 0.025 to 0.2 micrograms/ml had an inhibitory effect on colonial growth of up to 50% and it increased the number of mitotic malsegregants from 311% to 607% over the control value. Tallysomycin at concentrations between 2 and 16 micrograms/ml (which inhibited the germination of conidia from 30 to 90%) also increased the number of methionine suppressor revertants from 59 to 368 per 10(6) conidia. With regard to the mechanism for induced mitotic segregation it was shown that this may involve non-disjunction of chromosomes which through the intermediate formation of unstable aneuploids resulted in formation of stable haploid and diploid segregants.

Bleomycin (BLM) is well known as an antibiotic as well as for its antineoplastic activity. A clinical preparation of BLM was tested for its recombinogenicity in a higher eukaryotic organism, Drosophila melanogaster. Feeding of the F1 larvae on a medium with BLM increased somatic crossing-over spots on female tergites and induced recombination in male germ cells. However, nonlinear dose-response curves were obtained. Malformed tergites were also observed in females treated with BLM.

The combined action of hyperthermia and Bleomycin on Aspergillus nidulans was studied at three different levels: mycelial protein synthesis, spore viability and induction of mutations. It was found that Bleomycin treatment of preincubated mycelia during the heat shock enhances the incorporation of 35S-methionine into heat shock bands. Furthermore, simultaneous treatment with hyperthermia (43 degrees C) and Bleomycin results in greater cytotoxic activity in spores and in a higher induction rate of point mutations.

Heat shock was found to induce characteristic changes in the pattern of protein synthesis in Aspergillus nidulans as analysed by SDS-polyacrylamide gel electrophoresis. Six to seven new bands were found to show increased incorporation to 35S-methionine at 43 degrees C compared to 37 degrees C, the standard temperature for this organism. The heat shock response of five different strains of A. nidulans was examined. This comparative study showed that these strains (haploids and diploids) show exactly the same set of heat shock proteins.

Bleomycin, an antibiotic and antineoplastic drug that inhibits DNA synthesis and causes several types of chromosomal aberration, was found to increase mitotic recombination in Aspergillus nidulans. Heterozygous prototrophic diploid strains grown on media containing bleomycin produced significant increases of yellow and white sectors compared with controls. Further, the increased colour segregants were due to mitotic crossing-over, whereas the non-dis junctional segregants remained at the control level. Bleomycin also induced point mutations in the methionine-suppressor system of the methGl biAl strain of Aspergillus nidulans. Conidia treated in suspension with various concentrations of bleomycin increased the methionine-independent mutants 30-fold and more.