Perspectives of micronuclear test in human lymphocytes cultivated in cytogenetic block conditions. Part 1: Cell proliferation

Cytogenetic status of blood lymphocytes in schoolchildren living middle and high latitudes

Intensive industrial development of the northern regions of the Russian Federation is primarily associated with the extraction and processing of natural resources, which leads to environmental pollution and makes the tasks of sanitary and hygienic monitoring urgent. Rapid methods are convenient for the rapid diagnosis of the genetic well-being of the environment, one of which is the micronucleus test in combination with the cytokinetic block cytochalasin B. mitosis. At the moment, there are scanty data on the inter-latitudinal comparison of the results of cytogenetic studies on cells of various human tissues, which greatly complicates the comparison of the results obtained in the Arctic zone of the Russian Federation with data from more southern regions. The purpose of this study is to identify and compare division abnormalities in cells of peripheral blood lymphocytes in two groups of older schoolchildren living in middle and high latitudes. The study was carried out in the city of Serpukhov, Moscow region (54 ° 54 '56 "N, 37 ° 24' 40" E) and the city of Apatity, Murmansk region (67 ° 34'03 "N, 33 ° 23'36 ″ E). A total of 40 children aged 16-18 were examined - 20 children each from the city of Serpukhov and from the city of Apatity. The micronucleus test was carried out in accordance with the international protocol. Cytogenetic analysis of schoolchildren's peripheral blood lymphocytes using the micronucleus test showed that the spontaneous number of cells with micronuclei is comparable in middle and high latitudes, and approaches the upper limit of the mean population norm. Therefore, when comparing the data of the micronucleus test on the cells of peripheral blood lymphocytes of the studied groups, it is permissible not to take into account the latitude of residence.

Genetic damage in lymphocytes of lung cancer patients is correlated to the composition of the respiratory tract microbiome

Recent findings indicate that the microbiome may have significant impact on the development of lung cancer by its effects on inflammation, dysbiosis or genome damage. The aim of this study was to compare the sputum microbiome of lung cancer (LC) patients with the chromosomal aberration (CA) and micronuclei (MN) frequency in peripheral blood lymphocytes. In the study, the taxonomic composition of the sputum microbiome of 66 men with untreated LC were compared with 62 control subjects with respect to CA and MN frequency and centromere fluorescence in situ hybridisation analysis. Results showed a significant increase in CA (4.11 ± 2.48% versus 2.08 ± 1.18%) and MN (1.53 ± 0.67% versus 0.87 ± 0.49%) frequencies, respectively, in LC patients as compared to control subjects. The higher frequency of centromeric positive MN of LC patients was mainly due to aneuploidy. A significant increase in Streptococcus, Bacillus, Gemella and Haemophilus in LC patients was detected, in comparison to the control subjects while 18 bacterial genera were significantly reduced, which indicates a decrease in the beta diversity in the microbiome of LC patients. Although, the CA frequency in LC patients is significantly associated with an increased presence of the genera Bacteroides, Lachnoanaerobaculum, Porphyromonas, Mycoplasma and Fusobacterium in their sputum, and a decrease for the genus Granulicatella after application of false discovery rate correction, significance was not any more present. The decrease of MN frequency of LC patients is significantly associated with an increase in Megasphaera genera and Selenomonas bovis. In conclusion, a significant difference in beta diversity of microbiome between LC and control subjects and association between the sputum microbiome composition and genome damage of LC patients was detected, thus supporting previous studies suggesting an etiological connection between the airway microbiome and LC.

Association of DNA repair gene polymorphisms with genotoxic stress in underground coal miners

In underground coal mining, numerous harmful substances and ionising radiation pose a major threat to the occupational safety and health of workers. Because cell DNA repair machinery eliminates genotoxic stress conferred by these agents, we examined whether single nucleotide polymorphisms in hOGG1 (rs1052133), XRCC1 (rs25487), ADPRT (rs1136410), XRCC4 (rs6869366) and LIG4 (rs1805388) genes modulate the genotoxic damage assessed by the cytokinesis-block micronucleus assay in lymphocytes from 143 underground coal miners and 127 healthy non-exposed males. We also analyzed models of gene-gene interactions associated with increased cytogenetic damage in coal miners and determined 'protective' and 'risk' combinations of alleles. We showed that miners with the G/G genotype of the hOGG1 (rs1052133) gene had a significantly increased frequency of binucleated lymphocytes with micronuclei (13.17‰, 95% CI = 10.78-15.56) compared to the C/C genotype carriers (10.35‰, 95% CI = 9.59-11.18). In addition, in the exposed group this indicator was significantly increased in carriers of the T/T genotype of the LIG4 (rs1805388) gene compared to miners harbouring the C/T genotype (13.00‰, 95% CI = 10.96-15.04 and 9.69‰, 95% CI = 8.32-11.06, respectively). Using the multifactor dimensionality reduction method, we found the three-locus model of gene-gene interactions hOGG1 (rs1052133) × ADPRT (rs1136410) × XRCC4 (rs6869366) associated with high genotoxic risk in coal miners. These results indicate that the studied polymorphisms and their combinations are associated with cytogenetic status in miners and may be used as molecular predictors of occupational risks in underground coal mines.