Cigarette smoking during pregnancy: chromosome translocations and phenotypic susceptibility in mothers and newborns

Assessment of Chromosomal Damage in Umbilical Blood Lymphocytes of Newborns from Kragujevac in Central Serbia Born 18 Years after Environmental Contamination

The measurement of micronuclei (MN) in umbilical blood lymphocytes of newborns are increasingly used in cytogenetic epidemiology as one of the preferred methods for assessing chromosomal damage resulted from maternal exposure to mutagen. In the present study, we evaluated the effect of strong environmental contamination (EC) (which occured in the City of Kragujevac, Central Serbia in 1999) on the MN frequency in group of 22 newborns born in Kragujevac 18 years after EC, using cytokinesis-block micronucleus (CBMN) assay. The mean MN frequency in umbilical lymphocytes of these newborns was 5.14 ± 2.17/1,000 binucleated (BN) cells, which is significantly lower than mean MN frequency of newborns born 12 months after contamination (9.36 ± 5.60/1,000 BN cells). Sex of newborns, age of mothers, cigarette smoking, and number of pregnancies did not affect the MN frequency of newborns. Our results showed that in utero exposure to environmental pollution affected genome instability of the fetuses, but that by improving the quality of environmental conditions there was a decrease in mean MN frequency of newborns born 18 years after contamination. In general, genome of umbilical lymphocytes shows a realistic picture of all changes in body and the environment.

Nuclear abnormalities in umbilical cord blood lymphocytes of newborns from the Ahome and Guasave municipalities in Sinaloa, Mexico

AIM

We measured the frequency of nuclear abnormalities of 210 blood samples from the umbilical cord, since human fetuses are exposed to environmental mixtures of pesticides that induce DNA damage.

METHODS

The determinations were made through the micronucleus assay test in lymphocytes from the umbilical cord blood of newborns whose mothers live in Ahome (n = 105) and Guasave (n = 105), Sinaloa, Mexico.

RESULTS

The average frequency of anomalies in 1000 cells were, respectively: micronucleus 0.4 vs. 2.9, pyknotic cells 18.3 vs. 109.2, chromatin condensation 7.7 vs. 150.1, karyolitic cells 1.8 vs. 24.4, and binucleated cells 4.9 vs. 74.6. The calculated Pearson correlation factors of nuclear abnormality frequencies between both municipalities were low and negative, suggesting that they did not correlate between the Ahome and Guasave newborns and indicating a higher number of mothers exposed in Guasave.

CONCLUSION

Our data suggest that monitoring nuclear abnormalities in umbilical cord blood samples could be a useful tool to identify transplacental mutagens perfusion that is being discharged into the local environment.

Transplacental exposure to carcinogens and risks to children: evidence from biomarker studies and the utility of omic profiling

The factors underlying the increasing rates and the geographic variation of childhood cancers are largely unknown. Epidemiological studies provide limited evidence for a possible role in the etiology of certain types of childhood cancer of the exposure of pregnant women to environmental carcinogens (e.g., tobacco smoke and pesticides); however, such evidence is inadequate to allow definitive conclusions. Complementary evidence can be obtained from biomarker-based population studies. Such studies have demonstrated that, following exposure of pregnant mothers, most environmental carcinogens reach the fetus and, in many cases, induce therein genotoxic damage which in adults is known to be associated with increased cancer risk, implying that environmental carcinogens may contribute to the etiology of childhood cancer. During recent years, intermediate disease biomarkers, obtained via omic profiling, have provided additional insights into the impact of transplacental exposures on fetal tissues which, in some cases, are also compatible with a precarcinogenic role of certain in utero exposures. Here we review the epidemiological and biomarker evidence and discuss how further research, especially utilizing high-density profiling, may allow a better evaluation of the links between in utero environmental exposures and cancer in children.

DNA and chromosome damage induced by bleomycin in mammalian cells: An update

Bleomycin (BLM) is an antibiotic isolated from Streptomyces verticillus. It has radiomimetic actions on DNA thus it has been widely used in clinical chemotherapy for the treatment of different types of cancer, including head and neck tumors, lymphomas, squamous-cell carcinomas and germ-cell tumors. Because of this, the study of BLM genotoxicity is of practical interest. This antibiotic is an S-independent clastogen and an agent that generates free radicals and induces single- and double-strand breaks in DNA. In the present review, we will summarize our current knowledge concerning the DNA and chromosome damage induced by BLM in mammalian cells, with emphasis on new developments published since 1991.

Nuclear and mitochondrial DNA alterations in newborns with prenatal exposure to cigarette smoke

Newborns exposed to maternal cigarette smoke (CS) in utero have an increased risk of developing chronic diseases, cancer, and acquiring decreased cognitive function in adulthood. Although the literature reports many deleterious effects associated with maternal cigarette smoking on the fetus, the molecular alterations and mechanisms of action are not yet clear. Smoking may act directly on nuclear DNA by inducing mutations or epigenetic modifications. Recent studies also indicate that smoking may act on mitochondrial DNA by inducing a change in the number of copies to make up for the damage caused by smoking on the respiratory chain and lack of energy. In addition, individual genetic susceptibility plays a significant role in determining the effects of smoking during development. Furthermore, prior exposure of paternal and maternal gametes to cigarette smoke may affect the health of the developing individual, not only the in utero exposure. This review examines the genetic and epigenetic alterations in nuclear and mitochondrial DNA associated with smoke exposure during the most sensitive periods of development (prior to conception, prenatal and early postnatal) and assesses how such changes may have consequences for both fetal growth and development.

Nuclear abnormalities in cells from nasal epithelium: a promising assay to evaluate DNA damage related to air pollution in infants

OBJECTIVES

This study intends to provide a quick, easy, and inexpensive way to assess nuclear abnormalities such as micronuclei and bud frequencies; binucleated, karyorrhectic, karyolytic, pycnotic, and condensed chromatin cells in nasal scrapings of infants, which are particularly important for conducting genotoxic studies related to the inhaled atmosphere in pediatric populations.

METHODS

Nasal swab samples were collected from 40 infants under 12 months of age using a small cytobrush. 2,000 cells from each infant sample were analyzed and classified according to the frequency of nuclear abnormalities.

RESULTS

Rates of nuclear abnormalities found agree with values reported in other studies of neonates and children. This study found 0.13% of cells with micronuclei; 1.20% karyorrhexis; 0.03% pyknosis; 10.85% karyolysis; 1.11% condensed chromatin; 0.54 binucleated cells; and 0.02% nuclear bud. Differences were not observed between genders or environmental passive smoking, nor was any age correlation found.

CONCLUSION

The assay proposed here is suitable for assessing the frequency of nuclear abnormalities from nasal cells in infants.

Differences in cytogenetic sensitivity to ionizing radiation in newborns and adults

Radiation exposure causes DNA breaks leading to structural chromosome aberrations that can be carcinogenic. Lifetime cancer risks are elevated in irradiated children compared to similarly exposed adults. To determine the extent to which age influences the frequency and types of chromosome damage in response to ionizing radiation, peripheral blood samples were collected from 20 adults (aged 22-78 years) and from the umbilical cords of 10 newborns and acutely exposed to 0 (control), 1, 2, 3 or 4 Gy of cobalt-60 gamma rays. Cells were cultured in the presence of the mitogen phytohemagglutinin, harvested at 48 h and then evaluated for structural chromosome aberrations by fluorescence in situ hybridization whole chromosome painting. Regression analyses were used to evaluate radiation-induced translocated chromosomes, dicentrics, acentric fragments, color junctions and aberrant cells to determine whether the frequencies of these events was dependent upon age. Peripheral blood lymphocytes from newborns showed statistically significant increases in the induced frequencies of translocated chromosomes, dicentrics, acentric fragments, color junctions and abnormal cells at several radiation doses when compared to blood from adults. No significant changes in sensitivity with age were observed when adults were evaluated separately. We conclude that peripheral lymphocytes from newborns are significantly more prone to radiation-induced chromosome aberrations than peripheral lymphocytes from adults. The increased sensitivity of newborns in this study relative to adults was found to be 37(±9)%, 18(±4)%, 12(±2)% and 4(±5)% at doses of 1, 2, 3 and 4 Gy, respectively. These data may be relevant when making radiation exposure risk assessments.

Urinary naphthol metabolites and chromosomal aberrations in 5-year-old children

BACKGROUND

Exposure to naphthalene, an International Agency for Research on Cancer (IARC)-classified possible carcinogen and polycyclic aromatic hydrocarbon (PAH), is widespread, though resulting health effects are poorly understood. Metabolites of naphthalene, 1- and 2-naphthol, are measurable in urine and are biomarkers of personal exposure. Chromosomal aberrations, including translocations, are established markers of cancer risk and a biodosimeter of clastogenic exposures. Although prenatal (maternal) PAH exposure predicts chromosomal aberrations in cord blood, few studies have examined chromosomal aberrations in school-age children and none has examined their association with metabolites of specific PAHs.

METHODS

Using Whole Chromosome Paint Fluorescent in situ Hybridization, we documented chromosomal aberrations including translocations, in 113 five-year-old urban minority children and examined their association with concurrent concentrations of PAH metabolites measured in urine.

RESULTS

We report that in lymphocytes, the occurrence and frequency of chromosomal aberrations including translocations are associated with levels of urinary 1- and 2-naphthol. When doubling the levels of urinary naphthols, gender-adjusted OR for chromosomal aberrations are 1.63 [95% confidence interval (CI), 1.21-2.19] and 1.44 (95% CI, 1.02-2.04) for 1- and 2-naphthol, respectively; and for translocations OR = 1.55 (95% CI, 1.11-2.17) and 1.92 (95% CI, 1.20-3.08) for 1- and 2-naphthol, respectively.

CONCLUSION

Our results show that markers of exposure to naphthalene in children are associated with translocations in a dose-related manner, and that naphthalene may be a clastogen.

IMPACT

Indoor exposure to elevated levels of naphthalene is prevalent in large regions of the world. This study is the first to present an association between a marker of naphthalene exposure and a precarcinogenic effect in humans.

Cigarette smoke-induced transgenerational alterations in genome stability in cord blood of human F1 offspring

The relevance of preconceptional and prenatal toxicant exposures for genomic stability in offspring is difficult to analyze in human populations, because gestational exposures usually cannot be separated from preconceptional exposures. To analyze the roles of exposures during gestation and conception on genomic stability in the offspring, stability was assessed via the Comet assay and highly sensitive, semiautomated confocal laser scans of γH2AX foci in cord, maternal, and paternal blood as well as spermatozoa from 39 families in Crete, Greece, and the United Kingdom. With use of multivariate linear regression analysis with backward selection, preconceptional paternal smoking (% tail DNA: P>0.032; γH2AX foci: P>0.018) and gestational maternal (% tail DNA: P>0.033) smoking were found to statistically significantly predict DNA damage in the cord blood of F1 offspring. Maternal passive smoke exposure was not identified as a predictor of DNA damage in cord blood, indicating that the effect of paternal smoking may be transmitted via the spermatozoal genome. Taken together, these studies reveal a role for cigarette smoke in the induction of DNA alterations in human F1 offspring via exposures of the fetus in utero or the paternal germline. Moreover, the identification of transgenerational DNA alterations in the unexposed F1 offspring of smoking-exposed fathers supports the claim that cigarette smoke is a human germ cell mutagen.

Preterm newborns show slower repair of oxidative damage and paternal smoking associated DNA damage

Newborns have to cope with hypoxia during delivery and a sudden increase in oxygen at birth. Oxygen will partly be released as reactive oxygen species having the potential to cause damage to DNA and proteins. In utero, increase of most (non)-enzymatic antioxidants occurs during last weeks of gestation, making preterm neonates probably more sensitive to oxidative stress. Moreover, it has been hypothesized that oxidative stress might be the common etiological factor for certain neonatal diseases in preterm infants. The aim of this study was to assess background DNA damage; in vitro H(2)O(2) induced oxidative DNA damage and repair capacity (residual DNA damage) in peripheral blood mononucleated cells from 25 preterm newborns and their mothers. In addition, demographic data were taken into account and repair capacity of preterm was compared with full-term newborns. Multivariate linear regression analysis revealed that preterm infants from smoking fathers have higher background DNA damage levels than those from non-smoking fathers, emphasizing the risk of paternal smoking behaviour for the progeny. Significantly higher residual DNA damage found after 15-min repair in preterm children compared to their mothers and higher residual DNA damage after 2 h compared to full-term newborns suggest a slower DNA repair capacity in preterm children. In comparison with preterm infants born by caesarean delivery, preterm infants born by vaginal delivery do repair more slowly the in vitro induced oxidative DNA damage. Final impact of passive smoking and of the slower DNA repair activity of preterm infants need to be confirmed in a larger study population combining transgenerational genetic and/or epigenetic effects, antioxidant levels, genotypes, repair enzyme efficiency/levels and infant morbidity.

Chromosome translocations and assessing human exposure to adverse environmental agents

This article discusses the use of chromosome translocations for assessing adverse environmental exposure in humans. Translocations are a persistent biomarker of exposure and a biomarker of effect, making them the endpoint of choice for certain human exposure studies because they indicate a potential relationship between exposure and adverse health outcomes, particularly cancer and birth defects. Presented here are the different types of translocations, their origins and persistence, the strengths and limitations of using translocations for exposure assessments, the current state of the art for quantifying exposure including the importance of confounding effects, and the use of model organisms. This article concludes with an assessment of the future of translocation analyses.

Prenatal PAH exposure is associated with chromosome-specific aberrations in cord blood

Chromosomal aberrations are associated with increased cancer risk in adults. Previously, we demonstrated that stable aberrations involving chromosomes 1-6 in cord blood are associated with prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) measured in air and are disproportionate to genomic content. We now examine whether the association with air PAHs is chromosome-specific and extends to smaller chromosomes. Using whole chromosome paints for chromosomes 1-6, 11, 12, 14 and 19, and a 6q sub-telomere specific probe, we scored 48 cord bloods (1500 metaphases per sample) from newborns monitored prenatally for airborne PAH exposure in the Columbia Center for Children's Environmental Health cohort. Frequencies of stable aberrations were calculated as incident aberrations per 100 cell equivalents scored, and examined for association with airborne PAHs. Aberrations in chromosome 6 occurred more frequently than predicted by genomic content (p<0.008). Levels of both prenatal airborne PAHs and stable aberration frequency in chromosomes 1-6 decreased to half the levels reported previously in the same cohort (mean PAH decreased from 3.6 to 1.8ng/m(3); mean stable aberration frequency from 0.56 to 0.24, SD=0.19). The mean stable aberration frequency was 0.45 (SD=0.15) in chromosomes 11-19. After adjusting for gender, ethnicity, and household smokers, the mean stable aberration frequency increased with increasing PAH exposure: with a doubling of prenatal PAH exposure, the mean stable aberration frequency for the chromosome1-6 group increased by a factor of 1.49 (95% CI: 0.84, 2.66; p=0.17); for chromosomes 11-19 mean stable aberration frequency increased by 2.00 (95% CI: 1.11, 3.62; p=0.02); for chromosome 6 alone, it increased by 3.16 (95% CI: 0.93, 10.77; p=0.06); there was no increase for chromosomes 1-5 (p>0.8). Aberrations in chromosomes 11, 12, 14, 19 and 6 were associated with prenatal exposure to PAHs in air, even at lower levels of PAH in air. The observed chromosome-specific effects of prenatal airborne PAHs raise concern about potential cancer risk.