High Frequency Of Chromosomal Aberrations Research Articles

Assessing the Association of the Degree of DNA Methylation and the Frequency of Chromosomal Aberrations in Human Lymphocytes in a Single Irradiation of Blood <i>in vitro</i>

The most sensitive biomolecule under radiation exposure is DNA, whose damage manifests itself in the form of chromosomal aberrations (CA). The processes of DNA methylation, which are involved in the regulation of gene expression, replication, DNA repair, etc., are also affected by gamma radiation. The aim of the study was to evaluate the relationship between the degree of DNA methylation and the frequency of CA after acute in vitro irradiation of human blood lymphocytes with gamma radiation. The study involved 10 conditionally healthy workers of the Siberian Chemical Combine, in whose blood lymphocytes the degree of methylation of CpG-dinucleotides (wide-genome bisulfite sequencing, XmaI-Reduced representation bisulfite sequencing – XmaI-RRBS) and the frequency of CA (cytogenetic study) after acute in vitro blood irradiation with doses of 0 and 1.5 Gy were evaluated. After acute exposure to gamma radiation in lymphocytes, the frequency of aberrant cells, dicentric chromosomes, chromatid and chromosomal fragments increased. Correlation analysis of the status of CpG-dinucleotide methylation and the frequency of CA revealed changes in the degree of methylation of 97 genes, which strongly correlated positively (56 genes) or negatively (41 genes) with an increased frequency of CA. A primary genome-wide screening of genes whose methylation is correlates with a high frequency of CA was carried out. Many of the identified genes are promising as potential markers of radiation exposure and to study the mechanisms of formation of radiosensitivity of the body and radioresistance of tumors during radiation therapy.

Frequency and pattern of chromosomal abnormalities in acute myeloid leukemia from Western India: A retrospective study

Chromosomal abnormalities play an important role in diagnosis and prognosis of hematological diseases. The aim of the present study was to study the pattern and frequency of chromosomal aberrations in acute myeloid leukemia (AML) subgroups from western India. A retrospective study was conducted through evaluating laboratory proforma which were filled during 2005 to 2014 for diagnosis and treatment of AML subjects. We have studied chromosomal aberrations in 282 subjects with AML from western India. AML patients were sub-grouped according to FAB classification. Cytogenetic study using conventional cytogenetics (GTG-banding) and Fluorescence in situ hybridization (FISH) was carried out using FISH probes (AML1/ETO, PML/RARA, CBFB). Student's t test for continuous variables and Pearson's Chi-squared test for categorical variables were used to identify the relationship between variables. Cytomorphological study revealed AML- M3 as most frequent (32.3%) group followed by AML-M2 (25.2%) and AML-M4 (19.9%). Chromosomal abnormalities were identified in 145 (51.42%) of the total AML cases. A high frequency (38.6%) of chromosomal abnormalities was identified in AML-M3 subgroup as compared to AML-M2 (31%) and AML-M4 (20.6%). Cytogenetic study is important for the diagnosis and management of the AML patients. Our study identified chromosomal abnormalities in AML subgroups with varied frequencies. It is important in diagnosis and monitoring of the disease. As younger AML patients were more affected in our study, etiological factors such as environmental factors need to be studied. Combination of conventional cytogenetics and FISH has an advantage of identifying high frequency of chromosomal aberrations in AML patients.

O003 Radiation-related chromosomal aberrations observed in high volume endovascular operators performing X-ray guided surgery

Abstract Introduction The biological effects of chronic, low dose radiation, to which operators performing fluoroscopy-guided procedures are exposed, are unknown. We have previously demonstrated acute DNA damage/repair in lymphocytes from operators performing fluoroscopy-guided endovascular aneurysm repair (EVAR), but these markers normalised after 24 hours and did not inform on the residual accumulated effects of chronic radiation exposure. In the present study cytogenetic techniques were used to examine for chromosomal aberrations in endovascular operators. Methods Peripheral blood lymphocytes were isolated from high volume endovascular operators performing EVAR and age-matched radiation naïve general surgeons as controls. Giemsa staining was used to visualise the full complement of chromosomes and all dicentrics, where 2 centromeres are present in a single chromosome, were identified. The genome was analysed for abnormal exchanges of genetic material between chromosomes using multiplex fluorescence in situ hybridisation (mFISH). Results Lymphocytes from 18 operators (12 exposed, 6 controls) were analysed. A higher frequency of dicentric chromosomes were found in exposed operators compared with controls (0.0011 vs 0.0004, respectively, P=0.002) after examining 54,000 lymphocytes. Twice as many complex chromosome rearrangements were seen in endovascular operators compared with controls (0.48% vs 0.24%). Aneuploidy, the abnormal loss of chromosomes, was more frequent in endovascular operators with a median difference of 0.35 per chromosome (P=0.004). Conclusion We have found a higher frequency of chromosomal aberrations in endovascular operators compared with radiation naïve colleagues. This justifies further individual biological profiling for genomic instability and personalised radiation risk assessment. Take-home message Radiation-related DNA damage occurs in endovascular operators despite current radiation protection measures. Biological dosimetry could be a useful tool, allowing personalised risk assessment.

Cytogenetic Consequences of Food Industry Workers Occupationally Exposed to Cooking Oil Fumes (COFs).

Background:Cooking oil fumes (COFs) with smoking habits is a substantial risk that aggravates genetic modifications. The current study was to estimate the biological markers of genetic toxicity counting Micronucleus changes (MN), Chromosome Aberrations (CA) and DNA modifications among COFs exposures and control subjects inherent from South India. Materials and Methods:Present analysis comprised 212 COFs with tobacco users and equivalent number of control subjects. Results:High frequency of CA (Chromatid type: and chromosome type) were identified in group II experimental subjects also high amount of MN and DNA damage frequency were significantly (p < 0.05) in both subjects (experimental smokers and non-smokers). Present analysis was observed absence of consciousness among the COFs exposures about the destructive level of health effects of tobacco habits in working environment. Conclusion:COFs exposed workers with tobacco induce the significant alteration in chromosomal level. Furthermore, a high level of rate of genetic diseases (spontaneous abortion) were identified in the experimental subjects. This finding will be helpful for preventive measures of COFs exposed workers and supportive for further molecular analysis.

Heterogeneous photocatalysis of moxifloxacin at a pilot solar compound parabolic collector: Elimination of the genotoxicity

Photocatalysis has been applied for the elimination or reduction concentration of emerging pollutants in water. One of them, is the moxifloxacin (MOX), a fluoroquinolone that have a potential to develop resistant bacteria and have been present toxicity. The MOX achieves the environment due to inefficient wastewater treatment and incorrect disposal. Aiming to find a sustainable solution for photocatalytic process, compound parabolic concentrator (CPC) reactors have been proposed. In this sense, the present study investigates the application of CPC reactor for the degradation of MOX using sunlight and artificial light (UV-A lamp). In addition, the acute toxicity for L. sativa seeds and A. cepa bulbs, as well as the MOX cytotoxicity and genotoxicity for A. cepa root were investigated before and after treatment. The MOX degradation was around 65% using the sunlight and 44% with the artificial light. This difference was due to the kind of incident radiation (direct and diffuse), as well as the type of radiation (visible and/or ultraviolet) used in the processes. For L. sativa the acute toxicity was eliminated after MOX treatment using sunlight. A. cepa root length increased before the treatment and reduced significantly after it, what can indicate hormesis occurrence. MOX cytotoxicity was not observed. In contrast, genotoxicity assays showed high frequency of chromosomal aberrations for MOX solution, indicating elevated genotoxicity that was eliminated after solar treatment. The transformation products of MOX after CPC reactor solar treatment did not show cytotoxicity and genotoxicity in A. cepa and acute toxicity in L. Sativa. The results indicates that photocatalysis in a CPC solar reactor is efficient for MOX toxicity removal in the treated solutions.

Chromosomal Analysis of Myelodysplastic Syndromes Among Atomic Bomb Survivors in Nagasaki

[Background] Myelodysplastic syndromes (MDS) are clonal hematopoietic disorders that develop de novo and also secondary to chemotherapy and / or radiation therapy. We previously demonstrated that the risk of MDS is increased among atomic bomb survivors in Nagasaki, Japan with significant correlation to radiation dose (Iwanaga et al. JCO 2011). The latest our study showed that MDS among proximally radiated survivors to the hypocenter had higher frequency of chromosomal aberrations, especially those related to poor prognosis such as complex karyotypes, however, survival and leukemia transformation did not show statistical difference by the distance from hypocenter (Matsuo et al. Caner Sci 2016).[Aim] In this study, we investigated chromosomal abnormalities of MDS among survivors to address (1) whether specific chromosomal aberration exists, and (2) why karyotype did not have strong impact on the survival and leukemia transformation.[Methods] We collected clinical information of MDS patients diagnosed from 1985 to 2013 registered in the Nagasaki-City MDS database. This database includes information from five hospitals in Nagasaki city. Patients were diagnosed according to the French-American-British (FAB) classification criteria. Patient risk was evaluated using the International Prognostic Scoring System (IPSS), and the revised IPSS (IPSS-R).[Results and Discussion] There were 133 MDS patients among A-bomb survivors, and 269 were unexposed. Among survivors, the number of cases according to distance from the hypocenter was 29 in the <1.5km group (Group I), 35 in the 1.5-2.99 km group (Group II) and 69 in the ≥3 km group (Group III). Abnormal karyotype frequency was significantly higher with more very poor karyotypes, according to the revised International Prognostic Scoring System, among those exposed close to the hypocenter compared with unexposed cases. However, there was no difference in prognosis between exposed and unexposed cases. In the Group I, chromosomal translocations and inversions were more frequent, and the frequency of structural alterations in chromosomes 3, 8, and 11 was significantly increased compared with unexposed cases (P=0.007, 0.01, and 0.001, respectively). These results suggest that chromosomal alterations in MDS among survivors have different features compared with those in de novo or therapy-related MDS. Detailed molecular study is warranted. DisclosuresMiyazaki:Nippon Shinyaku: Honoraria. Haase:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Honoraria, Research Funding.

The Spectrum of Chromosomal Abnormalities and Endocrine Profile of Male Infertility with Nonobstructive Semen Abnormality: A Case-Control Study.

Background:Primary infertility is a common occurrence which affects approximately 15% of couples who desire to begin their family. Chromosomal abnormalities are well-established causes of pregnancy loss but may also have a role in explaining the cause of male infertility, especially with nonobstructive semen abnormalities. Hence, awareness regarding safety of artificial reproductive technology in these individuals due to underlying sperm aneuploidy is required.Aims:The aims of the study are to determine the prevalence of chromosomal abnormalities in primary infertile males with nonobstructive semen abnormalities and correlate with their endocrine profile.Study Design:A case–control study, in which 100 males with primary infertility and non-obstructive semen abnormalities were evaluated for chromosomal abnormality and hormonal profile; and were compared with 50 healthy males with normal semen analysis and at least one biological child.Materials and Methods:Blood T-lymphocytes were cultured using RPMI-1640 medium for obtaining metaphases and chromosomal analysis.Statistical Analysis:SPSS software and Student's t-test were used. A p < 0.05 was considered statistically significant.Results:Azoospermia (81%) was the most common nonobstructive semen abnormality. Overall prevalence of major chromosomal abnormalities and polymorphic variants was 16% and 7%, respectively. Klinefelter syndrome was the most common sex chromosomal numerical abnormality seen in 6.17% of cases with azoospermia. All healthy control males had 46, XY karyotype. Higher levels of follicle-stimulating hormone and luteinizing hormone and lower levels of testosterone along with testicular volumes were observed in infertile males with abnormal karyotype (p < 0.05).Conclusion:Primary infertile males with nonobstructive semen abnormality have high frequency of chromosomal aberrations, which justify the requirement of cytogenetic testing in these patients.

Composition of nanoclay supported silver nanoparticles in furtherance of mitigating cytotoxicity and genotoxicity.

Silver nanoparticle (Ag-NP) is well known for its high antibacterial efficacy. However, its toxicity toward mammalian cells is still a concern in clinical applications. The aim of our study was to evaluate the composition effects of Ag-NP supported by silicate nanoplatelet (NSP) with respect to the cytotoxicity and genotoxicity, and was in reference to the poly (styrene-co-maleic anhydride)-supported Ag-NP (Ag-NP/SMA). The NSP at the geometric dimension of averaged 80 x 80 x 1 nm3 was prepared from the exfoliation of natural clays and used to support different weight ratio of Ag-NP. The supporting limitation of NSP on Ag-NP was below the weight ratio of 15/85 (Ag-NP to NSP), and the detached Ag-NP from the Ag-NP/NSP (30/70) and Ag-NP/SMA hybrids were observed by TEM. Ames test was performed to assess the mutagenic potential of different compositions of Ag-NP/NSP, only Ag-NP/NSP (30/70) and Ag-NP/SMA hybrids exhibited mutagenicity when the concentration was 1.09 ppm or higher. In viewing of cytotoxicity using MTT tests toward HaCaT cells, the IC30 of Ag-NP/NSP (1/99, 7/93 and 15/85) were 1416.7, 243.6, and 148.9 ppm respectively, while Ag-NP/SMA was 64.8 ppm. The IC30 of Ag-NP/NSP (1/99, 7/93 and 15/85) were at least 833, 78 and 7 folds higher than their corresponding minimum inhibitory concentrations (MIC) respectively, and whereas Ag-NP/SMA was 6.4 folds. The Ag-NP/NSP and Ag-NP/SMA hybrids had been further investigated for genotoxicity by chromosomal aberrations and in vivo micronucleus assay within the concentration at IC10 and IC30, only Ag-NP/SMA showed a higher frequency of chromosomal aberrations. Our findings indicated that the viability of utilizing the NSP to maintain Ag-NP for antimicrobial activity, and the high-surface area of NSP served as an excellent support for associating Ag-NP and consequently rendering the mitigation of the inherent toxicity of Ag-NP in clinical uses.

Genetic behavior of induced translocation heterozygote in Artemisia annua L.

From the population raised from gamma irradiated seeds at different doses (100, 200 and 300 Gy), at 100 Gyphenotypically dissimilar plant (from the control plants) was isolated. The plant was shorter and morphologically weaker in contrast to control population. The cytological studies were carried out in a plant showed segmental exchanges between heterologous chromosomes. Chromosomal associations in rings and chains along with bivalents and univalents were observed in pollen mother cells (PMCs) during microsporogenesis. Various anaphasic anomalies were also taken into account including chromatid bridges, laggards and unequal separations etc. Subsequent stages of meiosis were also found to be highly intermittent. Owing to the high frequency of chromosomal aberrations, pollen fertility in control (96.32%) were efficaciously reduced to 38.26% at dose of 100Gy. The present study has been conducted to assess cytological behavior of the induced translocation heterozygote which is first time induced through gamma irradiation in the Artemisia annua L.

Assessment of mutagenic activity of toxic waste polygon (Kalush) soil’s chemical pollution by the level of cytogenetic disorders in Triticum aestivum L.

Aim. To study the frequency and spectrum of cytogenetic disorders in Triticum aestivum L. with prolonged action on soil xenobiotic seeds of toxic waste storage areas and to explore the level of their mutagenic activity in comparison with the action of NMS’s moderate and high concentrations. Methods. Cytogenetic disorders induced by soil’s chemical contamination of toxic waste landfill of Dombrovsky Quarry dump (Kalush city) and influence of NMS’s moderate and high concentrations were determined in the cells of the meristem root using the ana-thelophase method. Results. Soil’s chemical contamination of the studied objects exhibits high mutagenic activity, which exceeds the control level by 1.8–3.8 times and does not yield to the mutagenic activity of NMS’s moderate concentrations. The high frequency of chromosomal aberrations at the low concentration of hexachlorobenzene in the soil of the Dombrovsky Quarry dumps is a consequence of its complex interaction with natural mineral compounds of the mountain chemical raw materials. Conclusions. The increasing of the spectrum of cytogenetic disorders induced by chemical soil contamination the proportion of bridges and the chromosomal rings testify radiomimetic properties of the mutagenic factors. The increasing of the number of cells with multiple aberrations indicates a high genotoxicity of hexachlorobenzene and the risk of serious genetic consequences in the case of falling it’s into the environment.&#x0D; Keywords: Triticum aestivum L., toxic waste, mitosis disorders, chromosomal aberrations, mutagenic activity.

Taxonomic diversity of sputum microbiome in lung cancer patients and its relationship with chromosomal aberrations in blood lymphocytes

Here we report a pilot-sized study to compare the taxonomic composition of sputum microbiome in 17 newly-diagnosed lung cancer (LC) patients and 17 controls. Another object was to compare the representation of individual bacterial genera and species in sputum with the frequency of chromosomal aberrations in the blood lymphocytes of LC patients and in controls. Both groups were male; average age 56.1 ± 11.5 in patients and 55.7 ± 4.1 in controls. Differences in the species composition of bacterial communities in LC patients and controls were significant (pseudo-F = 1.94; p = 0.005). Increased prevalence in LC patients was detected for the genera Haemophilus and Bergeyella; whereas a decrease was observed for the genera Atopobium, Stomatobaculum, Treponema and Porphyromonas. Donors with high frequencies of chromosomal aberrations had a significant reduction in the microbiome of representatives of the genus Atopobium in the microbiome and a simultaneous increase in representatives of the species Alloprevotella compared to donors with a low level of chromosomal aberrations in lymphocytes. Thus, a comparison of the bacterial composition in the sputum of donors with cytogenetic damages in theirs lymphocytes, warrants further investigations on the potential role of microorganisms in the process of mutagenesis in somatic cells of the host body.

Biomonitoring of radioactive contamination of the Yenisei River using aquatic plants

The Yenisei River is contaminated by artificial radionuclides released by one of the Russian facilities producing weapons-grade plutonium (the Mining-and-Chemical Combine, MCC), which has been in operation for 60 years. The paper presents results of long-term monitoring of radionuclide concentrations in six aquatic plant species collected from the 1400 km Yenisei River stretch downstream of the city of Krasnoyarsk. Before the last MCC reactor was shut down (in 2010), up to 30 artificial radionuclides were detected in the plant biomass, and 2 and 5 years after the reactor shutdown, 11 and 3–5 radionuclides, respectively, were detected. The highest concentrations of radionuclides were recorded in Fontinalis antipyretica. The aquatic plant Elodea canadensis, which commonly occurs in the Yenisei River, was used in the cytogenetic study. High frequencies of chromosomal aberrations (up to 33%) were revealed in cells of Elodea canadensis roots from the Yenisei region affected by the MCC radioactive discharge, at dose rates of 45–72 μGy/d, while in the cells of the plant roots from the reference areas, the frequency of chromosomal aberrations was 5–7%, at dose rates below 2 μGy/d. The higher frequencies of chromosomal aberrations in Elodea canadensis collected from the parts of the River with increased concentrations of artificial radionuclides are associated with the radiation factor. The aquatic plant Elodea canadensis can be recommended as a bio-indicator for radioactively contaminated aquatic ecosystems.

Phytotoxicity and genotoxicity evaluation of 2,4,6-tribromophenol solution treated by UV-based oxidation processes

The environmental detriment due to the presence of emerging contaminants has encouraged the development of advanced oxidation processes. Such methods deal with non-selective chemical reactions. Therefore, toxic byproducts can be generated and distinct post treatment toxicity levels can be expected. The present study investigates the phytotoxicity of 2,4,6-tribromophenol (TBP) to L. sativa seeds and A. cepa bulbs, as well as the TBP phytotoxicity and genotoxicity to A. cepa root. L. sativa seeds and A. cepa bulbs were germinated by being exposed to solutions containing TBP before and after treatment by UV-based processes: direct photolysis (DP), heterogeneous photocatalysis (HP) and photoelectrolysis (PEC). Subsequent analysis of the root length, to determine phytotoxicity, as well as evaluation of chromosomal abnormalities, revealed that the samples treated by DP presented higher phytotoxicity than the untreated ones. On the other hand, samples treated by HP and PEC did not present phytotoxicity. In fact, for the A. cepa assays, phytotoxicity was not observed, including the initial sample. However, genotoxicity assays showed a high frequency of chromosomal aberrations in the initial sample, before the UV-based process treatment. After 140 min of treatment by HP, there was a reduction in genotoxicity, while PEC treatment resulted in a sample with no genotoxicity. In contrast, DP presented high levels of phytotoxicity and genotoxicity. Additionally, DP shows similar degradation and debromination values, when compared to the HP and PEC processes, but less mineralization. Therefore, considering that the DP process did not deals with the HO• radical, the oxidation pathway can generate byproducts with higher toxicity, which lead to higher levels of phytotoxicity and genotoxicity. These results show that different UV-based oxidation processes are associated to distinct byproducts and toxicity levels. In addition, a toxicity assessment with different organisms should be performed to ensure a safe outcome.

Incidence of genetic causes of idiopathic male infertility in Serbia: Ten years’ experience of single centre

The aim of the study was to estimate the type and the prevalence of chromosomal abnormalities and Y-chromosome microdeletions, analysed together for the first time in idiopathic infertile men in Serbia. During 10 years period among 823 couples with infertility problems, in 110 cases the cause of infertility was severe oligospermia or azoospermia in male partners. All of them underwent cytogenetic analysis, performed according to standard techniques. Testing for the presence of Y-chromosome microdeletions in AZF regions using multiplex PCR was done in all patients with normal karyotype (97) and in three cases with cytogenetically visible aberrations of Y chromosome, in order to specify the breakpoints. The overall prevalence of chromosomal abnormalities in the group of 110 infertile men was 11.82%. The most frequent aberration was Klinefelter syndrome (47, XXY), being found in 5.45%. Chromosomal aberrations were found in 13.89% in group of men with azoospermia, and in 7.89% in group of men with severe oligospermia. Among the infertile men with normal karyotype, the incidence of microdeletions of AZF regions was 7.22%. Two types of deletions were identified: AZFc and AZFbc, with frequencies of 6.19% and 1.03%, respectively. Y-chromosome microdeletions were found in 6.45% of azoospermic patients, and in 8.57% of severe oligospermia group of patients. Our findings demonstrate the presence of higher frequency of chromosome aberrations and Y-microdeletions in a group of infertile men with azoospermia/oligospermia in Serbia. Results confirmed importance of offering these tests as part of genetic counselling of infertile couples in our country.

The assessment of the genotoxicity of e-waste leachates from e-waste dumpsites in Metro Manila, Philippines

The extraordinary growth in the usage of electronic gadgets and their improper disposal has led to the massive problem of electronic waste management in the Philippines. The improper disposal of e-waste can lead to the exposure to the hazardous substances that can be harmful to the humans as well as to the environment. Genotoxicity of e-waste from three different e-waste landfills sites in and around Metro Manila was investigated using the Allium cepa bioassay. Morphological modifications of the Allium cepa roots, inhibition of root growth, mitotic index and the induction of high frequency of chromosomal aberrations were observed in the Allium cepa roots exposed to e-waste leachates prepared from the soil samples collected from all three sites tested as compared to the control. Since heavy metals are one of the hazardous components released during e-waste recycling, environmental contamination was further detected by Atomic Absorption Spectroscopy to detect the presence of heavy metals (Cd, Cu, Ni, Pb and Zn) in the soil samples of the e-waste recycling sites and in the hair of the informal recyclers. Our results are among the first few in the Philippines that establish the genotoxicity of e-waste as well as trace the route of the heavy metal component of e-waste into the human subjects through the exposure to the environmental contamination by e-waste. Hence, a proper e-waste management is an absolute priority to minimize the risk to the Filipino population and the environment.

Strong associations between chromosomal aberrations in blood lymphocytes and the risk of urothelial and squamous cell carcinoma of the bladder

Chromosomal aberrations (CAs) in blood lymphocytes have been shown to be associated with overall cancer risk and aging. However, their relationship to bladder cancer risk remains to be elucidated. In a case-control study of bladder cancer in Egypt, we examined the relationship between the increased frequency of CAs in blood lymphocytes and bladder cancer risk. High frequency of CAs was significantly associated with an increased risk of bladder cancer [adjusted odds ratios (OR) = 3.90, 95% confidence interval (CI) = 2.65–5.73]. The associations were somewhat stronger in squamous cell carcinomas (SCC, OR = 4.90) than in urothelial carcinomas (UC, OR = 3.62). We also identified chromosome specific CAs for chromosomes 3, 4, 5, 8, 9, 10, 11, 12, 17, 19 that were significantly associated with an increased risk of bladder cancer. We observed particularly strong associations between aberrations of chromosomes 12, 13, 17 and risk of SCC (OR = 7.06, 6.91 and 6.23, respectively). Conclusion: increased frequency of chromosomal aberrations in blood lymphocytes was significantly associated with bladder cancer risk. Overall and chromosome specific aberrations in blood lymphocytes may be a unique set of biomarkers for risk assessments of SCC and UC.

Identification of Small and Non-Small Cell Lung Cancer Markers in Peripheral Blood Using Cytokinesis-Blocked Micronucleus and Spectral Karyotyping Assays

Small cell lung cancer (SCLC) is a highly aggressive form of lung cancer. There is an urgent need to develop tools to identify individuals at high risk of developing SCLC. We have previously reported that the cytokinesis-blocked micronucleus (CBMN) assay is a strong predictor of non-small cell lung cancer (NSCLC). Here, we investigate the sensitivity of the CBMN endpoints as predictors of SCLC risk. We conducted the CBMN assay on SCLC patients (n = 216), NSCLC patients (n = 173), and healthy controls (n = 204). Per sample, 1,000 binucleated cells (BN) were scored, and 3 endpoints, micronuclei (BN-MN), nucleoplasmic bridges (BN-NPB), and nuclear buds(BN-BUD), were recorded. Spectral karyotyping was also conducted on SCLC patients (n = 116) and NSCLC patients (n = 137) to identify genomic regions unique to each disease. Significantly higher levels of CBMN endpoints were observed in both cancer groups compared to controls. BN-NPBs were significantly higher among SCLC patients compared to NSCLC patients (p < 0.001). Chromosomes 5 and 17 were associated with BN-MN, and chromosomes 5, 18, 20, and 22 were associated with BN-NPBs in SCLC patients. Given the high frequency of chromosome aberrations observed in SCLC, events such as reinsertion of the micronucleus and chromothripsis may be potential mechanisms for the genetic instability in these patients.

A Role for the Twins Protein Phosphatase (PP2A-B55) in the Maintenance of Drosophila Genome Integrity.

The protein phosphatase 2A (PP2A) is a conserved heterotrimeric enzyme that regulates several cellular processes including the DNA damage response and mitosis. Consistent with these functions, PP2A is mutated in many types of cancer and acts as a tumor suppressor. In mammalian cells, PP2A inhibition results in DNA double strand breaks (DSBs) and chromosome aberrations (CABs). However, the mechanisms through which PP2A prevents DNA damage are still unclear. Here, we focus on the role of the Drosophila twins (tws) gene in the maintenance of chromosome integrity; tws encodes the B regulatory subunit (B/B55) of PP2A. Mutations in tws cause high frequencies of CABs (0.5 CABs/cell) in Drosophila larval brain cells and lead to an abnormal persistence of γ-H2Av repair foci. However, mutations that disrupt the PP4 phosphatase activity impair foci dissolution but do not cause CABs, suggesting that a delayed foci regression is not clastogenic. We also show that Tws is required for activation of the G2/M DNA damage checkpoint while PP4 is required for checkpoint recovery, a result that points to a conserved function of these phosphatases from flies to humans. Mutations in the ATM-coding gene tefu are strictly epistatic to tws mutations for the CAB phenotype, suggesting that failure to dephosphorylate an ATM substrate(s) impairs DNA DSBs repair. In addition, mutations in the Ku70 gene, which do not cause CABs, completely suppress CAB formation in tws Ku70 double mutants. These results suggest the hypothesis that an improperly phosphorylated Ku70 protein can lead to DNA damage and CABs.

Biomarkers of exposure, effect, and susceptibility in workers exposed to chloronitrobenzenes

Biomonitoring methods were applied to workers exposed to high levels of chloronitrobenzenes. The external dose, internal dose, biologically effective dose, and biological effects were determined. Individual susceptibility was assessed by analyzing genetic polymorphisms of glutathione S-transferases M1, P1 and T1, and N-acetyltransferases 1 and 2. When the markers of exposure and susceptibility were compared with the frequency of chromosomal aberrations, clinical blood and urine parameters, and health effects typical of chloronitrobenzenes exposure, only a few of the comparisons were statistically significant. A statistically significantly higher frequency of chromosomal aberrations was detected in workers with a high level of hemoglobin-adducts.

The methylating agent streptozotocin induces persistent telomere dysfunction in mammalian cells

We analyzed chromosomal aberrations involving telomeres in the progeny of mammalian cells exposed to the methylating agent and antineoplastic/diabetogenic drug streptozotocin (STZ), to test whether it induces long-term telomere instability (by chromosome end loss and/or telomere dysfunction). Rat cells (ADIPO-P2 cell line, derived from Sprague-Dawley rat adipose cells) were treated with a single concentration of STZ (2mM). Chromosomal aberrations were analyzed 18h, 10 days, and 15 days after treatment, using PNA-FISH with a pan-telomeric probe [Cy3-(CCCTAA)3] to detect (TTAGGG)n repeats. Cytogenetic analysis revealed a higher frequency of chromosomal aberrations in STZ-exposed cultures vs. untreated cultures at each time point analyzed. The yield of induced aberrations was very similar at each time point. Induction of aberrations not involving telomere dysfunction was only observed 18h and 15 days after treatment, whereas induction of telomere dysfunction-related aberrations by STZ (mainly in the form of telomere FISH signal loss and duplications, most of them chromatid-type aberrations) was observed at each time point. Our results show that STZ induces persistent telomere instability in mammalian cells, cytogenetically manifested as telomere dysfunction-related chromosomal aberrations. Neither telomere length nor telomerase activity is related to the telomere dysfunction.