Genotoxicity of tobacco smoke and tobacco smoke condensate: a review

Paternal Smoking Before Conception and During Pregnancy Is Associated With an Increased Risk of Childhood Acute Lymphoblastic Leukemia: A Systematic Review and Meta-Analysis of 17 Case-Control Studies

OBJECTIVE

Current evidence regarding the association between paternal smoking before conception or during pregnancy and the risk of childhood acute lymphoblastic leukemia (ALL) are inconsistent. We aimed to systematically summarize the current evidence regarding this potential association.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and the Meta-analysis of Observational Studies in Epidemiology (MOOSE), we systematically retrieved PubMed, Embase, Web of Science, and Scopus, screened relevant literature, and assessed the methodologic quality of the included studies. We calculated the pooled estimates using random-effects models. We assessed statistical heterogeneity by I values and χ tests for the Cochrane Q statistic. We further investigate the dose-response relation using 2-stage nonlinear models.

RESULTS

A total of 17 case-control studies were identified, and the synthesized risk ratios (RRs) for smoking before conception (RR=1.15, 95% confidence interval: 1.04-1.27) and during pregnancy (RR=1.20, 95% confidence interval: 1.12-1.28) were both statistically significant. Moreover, the dose-response analysis showed a positive association as well.

CONCLUSION

Current evidence from observational studies suggests the association between paternal smoking before conception or during pregnancy and the increased risk of childhood ALL, which needs to be confirmed in prospective studies.

Environmental exposures, stem cells, and cancer

An estimated 70-90% of all cancers are linked to exposure to environmental risk factors. In parallel, the number of stem cells in a tissue has been shown to be a strong predictor of risk of developing cancer in that tissue. Tumors themselves are characterized by an acquisition of "stem cell" characteristics, and a growing body of evidence points to tumors themselves being sustained and propagated by a stem cell-like population. Here, we review our understanding of the interplay between environmental exposures, stem cell biology, and cancer. We provide an overview of the role of stem cells in development, tissue homeostasis, and wound repair. We discuss the pathways and mechanisms governing stem cell plasticity and regulation of the stem cell state, and describe experimental methods for assessment of stem cells. We then review the current understanding of how environmental exposures impact stem cell function relevant to carcinogenesis and cancer prevention, with a focus on environmental and occupational exposures to chemical, physical, and biological hazards. We also highlight key areas for future research in this area, including defining whether the biological basis for cancer disparities is related to effects of complex exposure mixtures on stem cell biology.

Genotoxic effects of tobacco use in residents of hilly areas and foot hills of Western Ghats, Southern India

Smoking and smokeless tobacco consumption is a significant risk factor that provokes genetic alterations. The present investigation was to evaluate the biomarkers of genotoxicity including micronucleus (MN), chromosome aberrations (CA) and DNA strand breaks among tobacco consumers and control individuals residing in hilly areas of Western Ghats, Tamilnadu, South India. This study included 268 tobacco consumers with equal number of controls. The tobacco consumers were divided into Group I (<10 years of tobacco consumption with an age range from 15 to 35 years) and group II (>10 years consumption above 35 years of age). Chromosome aberration (CA) and comet assay were performed using blood and micronucleus assay from exfoliated buccal epithelial cells obtained from tobacco consumers and controls. Elevated levels of CA were found in group II (Chromatid type: 2.39 ± 1.13 and chromosome type: 1.44 ± 1.24) exposed subjects, high micronucleus and DNA damage (TL:4.48 ± 1.24 and TM:3.40 ± 1.58) levels were significantly (p < 0.05) observed in both smoking and smokeless tobacco consumers when comparison with group I and controls. This study also observed a lack of awareness among the tobacco consumers about the harmful health effects of tobacco. Tobacco consumption contributes to the significant alteration in genetic materials. In addition, a high rate of spontaneous abortion was also seen in the studied population.

Smoking and microbiome in oral, airway, gut and some systemic diseases

The human microbiome harbors a diverse array of microbes which establishes a mutually beneficial relation with the host in healthy conditions, however, the dynamic homeostasis is influenced by both host and environmental factors. Smoking contributes to modifications of the oral, lung and gut microbiome, leading to various diseases, such as periodontitis, asthma, chronic obstructive pulmonary disease, Crohn’s disease, ulcerative colitis and cancers. However, the exact causal relationship between smoking and microbiome alteration remains to be further explored.

Tobacco smoke exposure and the risk of childhood acute lymphoblastic leukemia and acute myeloid leukemia: A meta-analysis

OBJECTIVE

Tobacco smoke contains carcinogens known to damage somatic and germ cells. In this study, we investigated the effect of tobacco smoking on the risk of childhood acute lymphoblastic leukemia (ALL) and myeloid leukemia (AML).

METHODS

Information about tobacco smoking exposures of the mother before, during, and after pregnancy was collected via PubMed, Embase, and Web of Science databases through November 5, 2018. We performed to evaluate the association between smoking exposure and the risk of childhood ALL and AML. Study selection, data abstraction, and quality assessment were performed by 2 independent reviewers. Random effects models were used to obtain summary odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Nineteen case-control studies of childhood leukemia (age < 15 years) conducted in 9 countries from 1974 to 2018. Maternal smoking exposures did not a significant association with childhood ALL (OR = 1.004, 95% CI 0.953-1.058, P = .881) and AML (OR = 0.92, 95% CI 0.815-1.038, P = .177) during exposure time windows. However, there was an association with paternal smoking and ALL (OR = 1.15, 95% CI 1.038-1.275, P = .007). Paternal smoking in AML showed there was no association with smoking exposures and childhood AML (OR = 1.133, 95% CI 0.943-1.362, P = .181). Next, maternal daily cigarettes consumption showed no associations with ALL (OR = 1.08, 95% CI 1.000-1.168, P = .051) during pregnancy. No association with maternal daily smoking and AML (OR = 0.909, 95% CI 0.682-1.211, P = .514). Paternal daily cigarettes consumption was associated with increased risks of childhood ALL (OR = 1.200, 95% CI 1.112-1.302, P = .000). The higher consumption of paternal smoking (more than 10 per day) was significantly related to childhood ALL. Paternal daily smoking consumption also was related to AML (OR = 1.242, 95% CI 1.031-1.496, P = .022).

CONCLUSION

Maternal smoking before, during, or after pregnancy was not associated with childhood ALL or AML. However, paternal smoking was related to a significantly elevated risk of childhood ALL during pregnancy, but not for AML. Maternal daily smoking consumption was not associated with ALL or AML during pregnancy. The higher consumption of paternal smoking were, the higher the risk of childhood ALL or AML.

Bioactivation of the tobacco carcinogens 4-aminobiphenyl (4-ABP) and 2-amino-9H-pyrido[2,3-b]indole (AαC) in human bladder RT4 cells

Occupational and tobacco exposure to aromatic amines (AAs) including 4-aminobiphenyl (4-ABP) and 2-naphthylamine (2-NA) are associated with bladder cancer (BC) risk. Several epidemiological studies have also reported a possible role for structurally related heterocyclic aromatic amines (HAAs) formed in tobacco smoke or cooked meats with BC risk. We had screened for DNA adducts of 4-ABP, 2-NA, and several prominent HAAs formed in tobacco smoke or grilled meats including 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-3,8-dimethylmidazo[4,5-f]quinoxaline (MeIQx), and 2-amino-9H-pyrido[2,3-b]indole (AαC) in the bladder DNA of BC patients, using liquid chromatography/mass spectrometry. We detected DNA adducts of 4-ABP, but not adducts of the other carcinogens. In this study, we have examined the capacity of RT4 cells, an epithelial human bladder cell line, to bioactivate AAs and HAAs to DNA damaging agents, which may contribute to BC. 4-ABP and AαC formed DNA adducts, but DNA adducts of 2-NA, PhIP, and MeIQx were not detected. 4-ABP DNA adducts were formed at tenfold higher levels than AαC adducts. Pretreatment of RT4 cells with α-naphthoflavone (1-10 µM), a specific cytochrome P450 1 (CYP1) inhibitor, decreased AαC adduct formation by 50% but did not affect the level of 4-ABP adducts. However, cell pretreatment with 8-methoxypsoralen (0.1-1 µM), a potent inhibitor of CYP2A, resulted in a 90% decrease of 4-ABP DNA adducts levels. These data signify that CYP2A and CYP1A isoforms expressed in the target urothelium bioactivate 4-ABP and AαC, respectively, and may be a critical feature of aromatic amine-induced urinary bladder carcinogenesis. The bioactivation of other tobacco and environmental AAs by bladder CYPs and their ensuing bladder DNA damage warrants further study.

Antioxidant and anti-apoptotic effects of royal jelly against nicotine-induced testicular injury in mice

This study describes the effects of royal jelly (RJ) on testicular injury induced by nicotine (NIC) in mice. Thirty-six male BALB/c mice were randomly divided into six groups (n = 6). Group 1 received normal saline, group 2 received 100 mg/kgBW/day RJ, groups 3 and 4 received NIC at doses of 0.50 and 1.00 mg/kgBW/day, respectively, and groups 5 and 6 received NIC at doses of 0.50 and 1.00 mg/kg BW/day, respectively, plus RJ. Following 35 days, the serum level of testosterone, histopathological changes, germ cell apoptosis, proliferating cell nuclear antigen (PCNA), malondialdehyde (MDA) content, and antioxidant indexes including total antioxidant capacity (TAC) and catalase (CAT) activity were determined. In addition, the mitochondria-dependent apoptosis was investigated by assessing the Bcl-2, p53, and Caspase-3 mRNA levels expression by reverse transcription-PCR (RT-PCR). Compared to NIC receiving groups, the concomitant administration of RJ could protect the testosterone reduction and histological damages. After RJ treatment, the level of tissue MDA content decreased, while tissue TAC and CAT levels were remarkably increased compared to NIC-exposed groups. Remarkable higher TUNEL-positive germ cells and low PCNA index were observed in NIC receiving groups. Besides, the expression level of Bcl-2 was significantly higher and the p53 and Caspase-3 levels were significantly lower in the RJ co-administration groups than NIC-only receiving groups. Our results confirmed that RJ effectively protects the testis against NIC evoked damages by antioxidant and anti-apoptotic effects involving the up regulation of the antioxidant status, mitochondria-dependent apoptosis pathway prevention, and the proliferating activity improvement.

DNA methylation at an enhancer of the three prime repair exonuclease 2 gene (TREX2) is linked to gene expression and survival in laryngeal cancer

Background

Genetic aberrations in DNA repair genes are linked to cancer, but less is reported about epigenetic regulation of DNA repair and functional consequences. We investigated the intragenic methylation loss at the three prime repair exonuclease 2 (TREX2) locus in laryngeal (n = 256) and colorectal cancer cases (n = 95) and in pan-cancer data from The Cancer Genome Atlas (TCGA).

Results

Significant methylation loss at an intragenic site of TREX2 was a frequent trait in both patient cohorts (p = 0.016 and < 0.001, respectively) and in 15 out of 22 TCGA studies. Methylation loss correlated with immunohistochemically staining for TREX2 (p < 0.0001) in laryngeal tumors and improved overall survival of laryngeal cancer patients (p = 0.045). Chromatin immunoprecipitation, demethylation experiments, and reporter gene assays revealed that the region of methylation loss can function as a CCAAT/enhancer binding protein alpha (CEBPA)-responsive enhancer element regulating TREX2 expression.

Conclusions

The data highlight a regulatory role of TREX2 DNA methylation for gene expression which might affect incidence and survival of laryngeal cancer. Altered TREX2 protein levels in tumors may affect drug-induced DNA damage repair and provide new tailored therapies.

Electronic supplementary material

The online version of this article (10.1186/s13148-019-0666-5) contains supplementary material, which is available to authorized users.

Significant Strain Variation in the Mutation Spectra of Inbred Laboratory Mice

Mutation provides the ultimate source of all new alleles in populations, including variants that cause disease and fuel adaptation. Recent whole genome sequencing studies have uncovered variation in the mutation rate among individuals and differences in the relative frequency of specific nucleotide changes (the mutation spectrum) between populations. Although parental age is a major driver of differences in overall mutation rate among individuals, the causes of variation in the mutation spectrum remain less well understood. Here, I use high-quality whole genome sequences from 29 inbred laboratory mouse strains to explore the root causes of strain variation in the mutation spectrum. My analysis leverages the unique, mosaic patterns of genetic relatedness among inbred mouse strains to identify strain private variants residing on haplotypes shared between multiple strains due to their recent descent from a common ancestor. I show that these strain-private alleles are strongly enriched for recent de novo mutations and lack signals of widespread purifying selection, suggesting their faithful recapitulation of the spontaneous mutation landscape in single strains. The spectrum of strain-private variants varies significantly among inbred mouse strains reared under standardized laboratory conditions. This variation is not solely explained by strain differences in age at reproduction, raising the possibility that segregating genetic differences affect the constellation of new mutations that arise in a given strain. Collectively, these findings imply the action of remarkably precise nucleotide-specific genetic mechanisms for tuning the de novo mutation landscape in mammals and underscore the genetic complexity of mutation rate control.

Impact of Tobacco Smoke in HIV Progression: a Major Risk Factor for the Development of NeuroAIDS and Associated of CNS Disorders

Aim

With the advent of highly active and combination antiretroviral therapy have substantially increased the life expectancy of patients infected with human immunodeficiency virus (HIV). However, this has brought into sharp contrast the incidence of several 'Non-acquired immunodeficiency syndrome (AIDS) diseases such as NeuroAIDS which identifies a group of neurological disorders caused primarily by HIV-mediated damage to the central and peripheral nervous systems. Given the patients depleted immune condition, the use and abuse of drug and addictive substances such as tobacco smoking can further deteriorates their overall health and accelerate the progression and severity of the disease. In this review we detail the pathogenesis, progression and characteristics of HIV and the impact of tobacco smoking as a risk factor for the progression of the disease to NeuroAIDS. This is a poorly understood aspect of HIV-related complications that needs to be addressed.

Subjects and methods

Review of theoretical approaches and knowledge synthesis.

Results

Tobacco smoking is highly prevalent in HIV patients when compared to the general population. The oxidative damage and inflammatory stress caused by chronic smoking on the cerebrovascular system have been well established. Considering that HIV patients have an impaired immune system and smokers per se are more susceptible to viral and bacterial inflammatory neuropathologies than non-smokers, it is conceivable that tobacco smoking as a risk factor for the progression of HIV into NeuroAIDS and related neurological impairments.

Conclusion

Tobacco smoke (TS) may bring about a synergistic effect in the context of persistent inflammatory state and cerebrovascular damage which facilitate HIV infection and progression to NeuroAIDS when compared to non-smokers.

Targeted and Untargeted Detection of DNA Adducts of Aromatic Amine Carcinogens in Human Bladder by Ultra-Performance Liquid Chromatography-High-Resolution Mass Spectrometry

Epidemiological studies have linked aromatic amines (AAs) from tobacco smoke and some occupational exposures with bladder cancer risk. Several epidemiological studies have also reported a plausible role for structurally related heterocyclic aromatic amines present in tobacco smoke or formed in cooked meats with bladder cancer risk. DNA adduct formation is an initial biochemical event in bladder carcinogenesis. We examined paired fresh-frozen (FR) and formalin-fixed paraffin-embedded (FFPE) nontumor bladder tissues from 41 bladder cancer patients for DNA adducts of 4-aminobiphenyl (4-ABP), a bladder carcinogen present in tobacco smoke, and 2-amino-9 H-pyrido[2,3- b]indole, 2-amino-1-methyl-6-phenylimidazo[4,5- b]pyridine and 2-amino-3,8-dimethylimidazo[4,5- f]quinoxaline, possible human carcinogens, which occur in tobacco smoke and cooked meats. These chemicals are present in urine of tobacco smokers or omnivores. Targeted DNA adduct measurements were done by ultra-performance liquid chromatography-electrospray ionization multistage hybrid Orbitrap MS. N-(2'-Deoxyguanosin-8-yl)-4-ABP ( N-(dG-C8)-4-ABP) was the sole adduct detected in FR and FFPE bladder tissues. Twelve subjects (29%) had N-(dG-C8)-4-ABP levels above the limit of quantification, ranging from 1.4 to 33.8 adducts per 109 nucleotides (nt). DNA adducts of other human AA bladder carcinogens, including 2-naphthylamine (2-NA), 2-methylaniline (2-MA), 2,6-dimethylaniline (2,6-DMA), and lipid peroxidation (LPO) adducts, were screened for in bladder tissue, by our untargeted data-independent adductomics method, termed wide-selected ion monitoring (wide-SIM)/MS2. Wide-SIM/MS2 successfully detected N-(dG-C8)-4-ABP, N-(2'-deoxyadenosin-8-yl)-4-ABP and the presumed hydrazo linked adduct, N-(2'-deoxyguanosin- N2-yl)-4-ABP, and several LPO adducts in bladder DNA. Wide-SIM/MS2 detected multiple DNA adducts of 2-NA, 2-MA, and, 2,6-DMA, when calf thymus DNA was modified with reactive intermediates of these carcinogens. However, these AA-adducts were below the limit of detection in unspiked human bladder DNA (<1 adduct per 108 nt). Wide-SIM/MS2 can screen for many types of DNA adducts formed with exogenous and endogenous electrophiles and will be employed to identify DNA adducts of other chemicals that may contribute to the etiology of bladder cancer.

In vitro toxicological activity of particulate matter generated by coal combustion

Herein, the toxicity of particles generated from the complete combustion of 1 g coal at 500, 700, and 900 °C were compared, and combustion at 700 °C generated the most toxins. Chemical analyses revealed that all components except catechol, resorcinol, and aromatic amines were most abundant at 700 °C. Toxicity results confirmed that the relative mutagenicity, cytotoxicity, redox cycling, and production of reactive oxygen species was highest for particles generated at 700 °C. Particles generated during combustion at 700 °C exhibited higher toxicity toward biological systems due to a higher content of toxic compounds.

Association between polycyclic aromatic hydrocarbons and osteoporosis: data from NHANES, 2005-2014

The association between osteoporosis and polycyclic aromatic hydrocarbons was not clear. However, recent studies showed that both osteoporosis and polycyclic aromatic hydrocarbons were associated with reactive oxygen species. So we presumed that polycyclic aromatic hydrocarbons were associated with increased odds of osteoporosis. We found 3-hydroxyfluorene was associated with decreased odds of osteoporosis, while 2-hydroxyfluorene was associated with increased odds of osteoporosis.

PURPOSE

Previous studies showed that polycyclic aromatic hydrocarbons were involved in the production of reactive oxygen species that played an important role in illness. Other studies demonstrated that the reactive oxygen species might play a role in occurrence of osteoporosis. However, the association between polycyclic aromatic hydrocarbons and osteoporosis was not clear. Therefore, we conducted a study to investigate the relationship between polycyclic aromatic hydrocarbons and osteoporosis.

METHODS

A total of 3053 individuals aged 50 years or older were drawn from National Health and Nutritional Examination Survey, 2005-2014. Eight polycyclic aromatic hydrocarbons metabolites (1-hydroxynaphthalene, 2-hydroxynaphthalene, 2-hydroxyfluorene, 3-hydroxyfluorene, 1-hydroxyphenanthrene, 2-hydroxyphenanthrene, and 3-hydroxyphenanthrene and 1-hydroxypyrene) were examined to represent exposure of polycyclic aromatic hydrocarbons in the body. Weighted percentage and weighted mean were used to describe classified variable and continuous variable, respectively. We used weighted logistic regression to estimate the association of polycyclic aromatic hydrocarbons and osteoporosis.

RESULTS

Five hundred seventy-seven (18.9%) osteoporosis patients were included. Among the eight polycyclic aromatic hydrocarbons metabolites, 3-hydroxyfluorene was associated with decreased odds of osteoporosis after controlling socio-demographic status, body mass index, alcohol, previous fracture, parental fracture, glucocorticoid use, dietary calcium intake, smoking, and other polycyclic aromatic hydrocarbons metabolites (OR = 0.63, 95%CI 0.41-0.98). 2-hydroxyfluorene (OR = 1.87, 95%CI 1.07-3.29) was associated with increased odds of osteoporosis. In the nonsmoking group, we found the association of osteoporosis with 2-hydroxyfluorene (OR = 2.56, 95%CI 1.10-5.96) and 3-hydroxyfluorene (OR = 0.41, 95%CI 0.22-0.77) still exists.

CONCLUSION

Our study found that 3-hydroxyfluorene was associated with decreased odd of osteoporosis, while 2-hydroxyfluorene was associated with increased odds of osteoporosis. Our study was a cross-sectional study, therefore cohort studies or experimental studies about association of PAH and osteoporosis is needed.

Anti-cancer effects of 3,5-dimethylaminophenol in A549 lung cancer cells

Exposure to 3,5-dimethylaminophenol (3,5-DMAP), the metabolite of the 3-5-dimethylaniline, was shown to cause high levels of oxidative stress in different cells. The aim of the present work was to observe whether this metabolite can lead to cytotoxicity, oxidative stress, DNA damage and cell cycle changes in non-small cell lung cancer A549 cells. 3,5-DMAP caused a dose-dependent increase in cytotoxicity, generation of superoxide (O₂^-.), inductions in the enzyme activities orchestrating cellular antioxidant balance, increases in lipid peroxidation as well as DNA damage. However, 3,5-DMAP showed significantly lower cytotoxicity towards human lung fibroblast (HLF) cells. 3,5-DMAP also led to molecular events, like inducing apoptotic markers (ie. p53, Bad, Bax and cytochrome c); decreasing anti-apoptotic proteins (Bcl-2) and alterations in cell cycle. Our findings indicate that the cytotoxicity caused by this particular alkylaniline metabolite led to initiation of caspase 3-mediated apoptosis. Furthermore, 3,5-DMAP attenuated carcinogenic properties like migration capacity of A549 cells and eventually inhibited growth of A549 cells in an in vivo mouse model. Tumor sections showed that 3,5-DMAP down-regulated c-Myc expression but up-regulated p53 and cytochrome c, all of which might result in tumor growth arrest. Co-treatment with N-acetylcysteine provided reductions in cytotoxicity and positively modulated genetic events induced by 3,5-DMAP in A549 cells. In conclusion, our findings demonstrate 3,5-DMAP may be a potential anti-cancer drug in cancer, due to its self redox cycling properties.

Paternal lifestyle factors in relation to semen quality and in vitro reproductive outcomes

This prospective-cohort study aimed at investigating the influence of paternal lifestyle factors on semen parameters and intracytoplasmic sperm injection (ICSI) outcomes. The influence of paternal lifestyle factors on seminal quality and ICSI outcomes was investigated in male patients undergoing conventional semen analysis. Cigarette smoking negatively influenced semen volume (B: -0.417, slope: 1.570, p = 0.047), sperm count/ml (B: -7.363, slope: 52.298, p = 0.014), total sperm count (B: -4.43, slope: 178.165, p = 0.023), total motile sperm count (B: -1.38, slope: 100.276, p = 0.045) and SDF (B: 0.014, slope: 9.767, p = 0.033). Alcohol consumption negatively influenced sperm count/ml (B: -12.527, slope: 42.255, p = 0.040) and sperm DNA fragmentation (B: 5.833, slope: 9.680, p = 0.002). There were no significant influences of other paternal lifestyle factors. Cigarette smoking negatively influenced the fertilisation rate (B: -1.349, slope: 21.950, p = 0.039) and the blastocyst formation rate (B: -14.244, slope: 28.851, p = 0.025). Alcohol consumption negatively influenced fertilisation rate (B: -3.617, slope: 20.138, p = 0.041) and blastocyst formation rate (B: -34.801, slope: 30.044, p = 0.042). Cigarette smoking and alcohol consumption appear to reduce semen quality, fertilisation and blastocyst formation rates; thus, it would be wise to recommend that male partners reconsider their lifestyle during in vitro reproduction treatment.

Paternal smoking and spontaneous abortion: a population-based retrospective cohort study among non-smoking women aged 20-49 years in rural China

BACKGROUND

To comprehensively evaluate the association of paternal smoking and spontaneous abortion.

METHODS

We conducted a population-based retrospective cohort study among 5 770 691 non-smoking rural Chinese women, along with their husbands, participating in the National Free Pre-Pregnancy Checkups Project, regarding outcome events that occurred in 2010-2016. The main outcome was spontaneous abortion (SA). Multivariable logistic regression was used to estimate OR and 95% CI, and restricted cubic spline was used to estimate the non-linear relationship.

RESULTS

The multivariable-adjusted OR of exposure to paternal smoking for SA was 1.17 (95% CI 1.16 to 1.19), compared with women without exposure to paternal smoking; and corresponding OR of exposure to preconception paternal smoking for SA was 1.11 (95% CI 1.08 to 1.14), compared with women without exposure to preconception paternal smoking. The ORs of preconception paternal smoking also increased with increases in paternal smoking (p_nonlinear<0.05, almost linearly shaped) and preconception paternal smoking (p_nonlinear>0.05). In addition, periconception paternal smoking cessation was associated with an 18% (15%-22%) lower risk of SA.

CONCLUSION

Paternal smoking was associated with SA. The importance of tobacco control, specifically pertaining to paternal smoking, should be emphasised during preconception and pregnancy counselling.

Indoor PM2.5 in an urban zone with heavy wood smoke pollution: The case of Temuco, Chile

Temuco is a mid-size city representative of severe wood smoke pollution in southern Chile; however, little is known about the indoor air quality in this region. A field measurement campaign at 63 households in the Temuco urban area was conducted in winter 2014 and is reported here. In this study, indoor and outdoor (24-hr) PM_2.5 and its elemental composition were measured and compared. Infiltration parameters and outdoor/indoor contributions to indoor PM_2.5 were also determined. A statistical evaluation of how various air quality interventions and household features influence indoor PM_2.5 was also performed. This study determined median indoor and outdoor PM_2.5 concentrations of 44.4 and 41.8 μg/m³, respectively. An average infiltration factor (0.62 ± 0.06) was estimated using sulfur as a tracer species. Using a simple mass balance approach, median indoor and outdoor contributions to indoor PM_2.5 concentrations were then estimated as 12.5 and 26.5 μg/m³, respectively; therefore, 68% of indoor PM_2.5 comes from outdoor infiltration. This high percentage is due to high outdoor pollution and relatively high household air exchange rates (median: 1.06 h^-1). This study found that S, Br and Rb were dominated by outdoor contributions, while Si, Ca, Ti, Fe and As originated from indoor sources. Using continuous indoor and outdoor PM_2.5 measurements, a median indoor source strength of 75 μg PM_2.5/min was estimated for the diurnal period, similar to literature results. For the evening period, the median estimate rose to 135 μg PM_2.5/min, reflecting a more intense wood burning associated to cooking and space heating at night. Statistical test results (at the 90% confidence level) support the ongoing woodstove replacement program (reducing emissions) and household weatherization subsidies (reducing heating demand) for improving indoor air quality in southern Chile, and suggest that a cookstove improvement program might be helpful as well.

Father's environment before conception and asthma risk in his children: a multi-generation analysis of the Respiratory Health In Northern Europe study

Background

Whereas it is generally accepted that maternal environment plays a key role in child health, emerging evidence suggests that paternal environment before conception also impacts child health. We aimed to investigate the association between children's asthma risk and parental smoking and welding exposures prior to conception.

Methods

In a longitudinal, multi-country study, parents of 24 168 offspring aged 2-51 years provided information on their life-course smoking habits, occupational exposure to welding and metal fumes, and offspring's asthma before/after age 10 years and hay fever. Logistic regressions investigated the relevant associations controlled for age, study centre, parental characteristics (age, asthma, education) and clustering by family.

Results

Non-allergic early-onset asthma (asthma without hay fever, present in 5.8%) was more common in the offspring with fathers who smoked before conception {odds ratio [OR] = 1.68 [95% confidence interval (CI) = 1.18-2.41]}, whereas mothers' smoking before conception did not predict offspring asthma. The risk was highest if father started smoking before age 15 years [3.24 (1.67-6.27)], even if he stopped more than 5 years before conception [2.68 (1.17-6.13)]. Fathers' pre-conception welding was independently associated with non-allergic asthma in his offspring [1.80 (1.29-2.50)]. There was no effect if the father started welding or smoking after birth. The associations were consistent across countries.

Conclusions

Environmental exposures in young men appear to influence the respiratory health of their offspring born many years later. Influences during susceptible stages of spermatocyte development might be important and needs further investigation in humans. We hypothesize that protecting young men from harmful exposures may lead to improved respiratory health in future generations.

Comparison of Mutagenic Activities of Various Ultra-Fine Particles

Air pollution is increasing, along with consumption of fossil fuels such as coal and diesel gas. Air pollutants are known to be a major cause of respiratory-related illness and death, however, there are few reports on the genotoxic characterization of diverse air pollutants in Korea. In this study, we investigated the mutagenic activity of various particles such as diesel exhaust particles (DEP), combustion of rice straw (RSC), pine stem (PSC), and coal (CC), tunnel dust (TD), and road side dust (RD). Ultra-fine particles (UFPs) were collected by the glass fiber filter pad. Then, we performed a chemical analysis to see each of the component features of each particulate matter. The mutagenicity of various UFPs was determined by the Ames test with four Salmonella typhimurium strains with or without metabolic activation. The optimal concentrations of UFPs were selected based on result of a concentration decision test. Moreover, in order to compare relative mutagenicity among UFPs, we selected and tested DEP as mutation reference. DEP, RSC, and PSC induced concentration-dependent increases in revertant colony numbers with TA98, TA100, and TA1537 strains in the absence and presence of metabolic activation. DEP showed the highest specific activity among the particulate matters. In this study, we conclude that DEP, RSC, PSC, and TD displayed varying degrees of mutagenicity, and these results suggest that the mutagenicity of these air pollutants is associated with the presence of polycyclic aromatic hydrocarbons (PAHs) in these particulate matters.

Smoking under hypoxic conditions: a potent environmental risk factor for inflammatory and autoimmune diseases

Autoimmune disease management presents a significant challenge to medical science. Environmental factors potentially increase the risk of developing inflammatory and autoimmune diseases, such as multiple sclerosis, rheumatoid arthritis, and lupus. Among various environmental stresses, cigarette smoke and hypoxia have both been reported to lead to an enhanced risk of inflammatory and autoimmune diseases.In this review, we shed light on all reported mechanisms whereby cigarette smoke and a hypoxic environment can induce inflammatory and autoimmune diseases and discuss how hypoxic conditions influence the cigarette smoke-induced threat of inflammatory and autoimmune disease development.Cigarette smoke and hypoxia both lead to increased oxidative stress and production of reactive oxygen species and other free radicals, which have various effects including the generation of autoreactive pro-inflammatory T cells and autoantibodies, reductions in T regulatory (Treg) cell activity, and enhanced expression of pro-inflammatory mediators [e.g., interleukin-6 (IL-6), interleukin-4 (IL-4) and interleukin-8 (IL-8)]. Accordingly, smoking and hypoxic environments may synergistically act as potent environmental risk factors for inflammatory and autoimmune diseases. To our knowledge, no studies have reported the direct association of cigarette smoke and hypoxic environments with the risk of developing inflammatory and autoimmune diseases.Future studies exploring the risk of autoimmune disease development in smokers at high altitudes, particularly military personnel and mountaineers who are not acclimatized to high-altitude regions, are required to obtain a better understanding of disease risk as well as its management.

Cigarette Smoking Impairs Adipose Stromal Cell Vasculogenic Activity and Abrogates Potency to Ameliorate Ischemia

Cigarette smoking (CS) adversely affects the physiologic function of endothelial progenitor, hematopoietic stem and progenitor cells. However, the effect of CS on the ability of adipose stem/stromal cells (ASC) to promote vasculogenesis and rescue perfusion in the context of ischemia is unknown. To evaluate this, ASC from nonsmokers (nCS-ASC) and smokers (CS-ASC), and their activity to promote perfusion in hindlimb ischemia models, as well as endothelial cell (EC) survival and vascular morphogenesis in vitro were assessed. While nCS-ASC improved perfusion in ischemic limbs, CS-ASC completely lost this therapeutic effect. In vitro vasculogenesis assays revealed that human CS-ASC and ASC from CS-exposed mice showed compromised support of EC morphogenesis into vascular tubes, and the CS-ASC secretome was less potent in supporting EC survival/proliferation. Comparative secretome analysis revealed that CS-ASC produced lower amounts of hepatocyte growth factor (HGF) and stromal cell-derived growth factor 1 (SDF-1). Conversely, CS-ASC secreted the angiostatic/pro-inflammatory factor Activin A, which was not detected in nCS-ASC conditioned media (CM). Furthermore, higher Activin A levels were measured in EC/CS-ASC cocultures than in EC/nCS-ASC cocultures. CS-ASC also responded to inflammatory cytokines with 5.2-fold increase in Activin A secretion, whereas nCS-ASC showed minimal Activin A induction. Supplementation of EC/CS-ASC cocultures with nCS-ASC CM or with recombinant vascular endothelial growth factor, HGF, or SDF-1 did not rescue vasculogenesis, whereas inhibition of Activin A expression or activity improved network formation up to the level found in EC/nCS-ASC cocultures. In conclusion, ASC of CS individuals manifest compromised in vitro vasculogenic activity as well as in vivo therapeutic activity. Stem Cells 2018;36:856-867.

Chronic exposure to cigarette smoke leads to activation of p21 (RAC1)-activated kinase 6 (PAK6) in non-small cell lung cancer cells

Epidemiological data clearly establishes cigarette smoking as one of the major cause for lung cancer worldwide. Recently, targeted therapy has become one of the most preferred modes of treatment for cancer. Though certain targeted therapies such as anti-EGFR are in clinical practice, they have shown limited success in lung cancer patients who are smokers. This demands discovery of alternative drug targets through systematic investigation of cigarette smoke-induced signaling mechanisms. To study the signaling events activated in response to cigarette smoke, we carried out SILAC-based phosphoproteomic analysis of H358 lung cancer cells chronically exposed to cigarette smoke. We identified 1,812 phosphosites, of which 278 phosphosites were hyperphosphorylated (≥ 3-fold) in H358 cells chronically exposed to cigarette smoke. Our data revealed hyperphosphorylation of S560 within the conserved kinase domain of PAK6. Activation of PAK6 is associated with various processes in cancer including metastasis. Mechanistic studies revealed that inhibition of PAK6 led to reduction in cell proliferation, migration and invasion of the cigarette smoke treated cells. Further, siRNA mediated silencing of PAK6 resulted in decreased invasive abilities in a panel of non-small cell lung cancer (NSCLC) cells. Consistently, mice bearing tumor xenograft showed reduced tumor growth upon treatment with PF-3758309 (group II PAK inhibitor). Immunohistochemical analysis revealed overexpression of PAK6 in 66.6% (52/78) of NSCLC cases in tissue microarrays. Taken together, our study indicates that PAK6 is a promising novel therapeutic target for NSCLC, especially in smokers.

Smoking habit from the paternal line and grand-child's overweight or obesity status in early childhood: prospective findings from the lifeways cross-generation cohort study

BACKGROUND/OBJECTIVES

The role of smoking from the paternal line during the pre-conception period on grand-child's overweight/obesity and associated underlying pathways are uncertain. We examined whether the smoking status from the paternal line was associated with the grand-child's higher weight at birth, and overweight or obesity at 5 and 9 years of age. The grandparental smoking effect from the maternal line was also explored.

SUBJECTS/METHODS

Participants were fathers and grandparents and grand-children from the Lifeways Cross Generational Cohort (N = 1021 for the analysis at birth; N = 562 and N = 284 for the analysis at 5 and 9 years, respectively). Paternal and grandparental smoking was defined as smoking versus non-smoking. Children's weight categories compared were high versus normal weight at birth, and overweight/obesity versus normal weight (based on BMI and waist circumference) at age of five and nine years. Logistic regression models were used to estimate the crude and adjusted associations.

RESULTS

After adjustment for several child and parental factors, at age five there was an association between paternal smoking and offspring's overweight/obesity based on BMI (Adjusted Odds Ratio (AOR), and 95%CI: 1.76, 1.14-2.71, p-value: 0.010), most marked for boys (AOR: 2.05, 1.06-3.96, p-value: 0.032). These associations remained when confined to the children sample with biological fathers only (overall sample, AOR: 1.92, 1.22-3.02, p-value: 0.005; son, AOR: 2.09, 1.06-4.11, p-value: 0.033). At age 9, the paternal grandmothers' smoking was positively associated with their grandchild's overweight/obesity status based on waist circumference (AOR: 3.29, 1.29-8.37), and especially with that of her granddaughter (AOR: 3.44, 1.11-10.69). These associations remained when analysing only the children sample with biological fathers (overall sample, AOR: 3.22,1.25-8.29, p-value: 0.016; granddaughter, AOR: 3.55, 1.13-11.15, p-value: 0.030).

CONCLUSION

The smoking habit from the paternal line is associated with grand-children's adiposity measures during their early childhood, which might be epigenetically transmitted through male-germline cells.

Avoiding the ingestion of cytotoxic concentrations of ethanol may reduce the risk of cancer associated with alcohol consumption

Alcohol consumption is a known risk factor for cancer. Almost 6% of all cancers worldwide are attributable to alcohol use. Approximately half of them occur in tissues highly exposed to ethanol, such as the oral cavity, pharynx, upper larynx and esophagus. However, since ethanol is not mutagenic and the mutagenic metabolite of ethanol (acetaldehyde) is mainly produced in the liver, it is unclear why alcohol consumption preferentially exerts a local carcinogenic effect. Recent findings indicate that the risk of cancer in a tissue is strongly correlated with the number of stem cell divisions accumulated by the tissue; the accumulation of stem cell divisions leads to the accumulation of cancer-promoting errors such as mutations occurring during DNA replication. Since cell death activates the division of stem cells, we recently proposed that the possible cytotoxicity of ethanol on the cells lining the tissues in direct contact with alcoholic beverages could explain the local carcinogenic effect of alcohol. Here we report that short-term exposures (2-3 s) to ethanol concentrations between 10% and 15% start to cause a marked cytotoxic effect on human epithelial keratinocytes in a concentration-dependent manner. We propose that choosing alcoholic beverages containing non-cytotoxic concentrations of ethanol, or diluting ethanol to non-cytotoxic concentrations, may be a simple and effective way to reduce the risk of cancers of the oral cavity, pharynx, larynx and esophagus in alcohol users. This preventive strategy may also reduce the known synergistic effect of alcohol drinking and tobacco smoking on the risk of these cancers.

Cigarette sidestream smoke delays nucleotide excision repair: inhibited accumulation of repair proteins at DNA lesions

Cigarette sidestream smoke (CSS) contains many carcinogens that induce DNA damage. DNA damage plays an important role in the initiation of cancer and several diseases, and repair is the major defense mechanism; however, the relationship between CSS and the repair of DNA damage remains unclear. We herein investigated whether CSS influences nucleotide excision repair (NER) in vivo and in vitro. HR-1 hairless mouse skin treated with CSS was exposed to UVB, as a result of which pyrimidine dimers (cyclobutane pyrimidine dimers (CPDs) and pyrimidine(6-4)pyrimidone photoproducts (6-4PPs)) were formed and repaired via the NER pathway. The immunohistochemical staining of CPDs revealed that their repair was delayed by the CSS treatment. This delay in NER and the underlying mechanisms were examined in the human skin cell lines, HaCaT and HSC-1. Dot-blot assays, enzyme-linked immunosorbent assay and local ultraviolet irradiation assays demonstrated that CSS delayed the repair of CPDs and 6-4PPs. The recruitment of the repair molecules, TFIIH, XPA and XPG to pyrimidine dimers was markedly inhibited by CSS. Semicarbazide, which reacts with aldehydes, recovered the CSS-induced inhibition of NER, and formaldehyde exerted similar inhibitory effects to those of CSS. These results suggest that aldehydes in CSS interfere with the recruitment of NER molecules to damaged sites, leading to a delay in the repair of pyrimidine dimers.

Evaluation of Pb-210 in urine and frequency of micronuclei in exfoliated cells as indicators of exposure to cigarettes

This study aimed at analyzing the frequency of micronuclei (MN) in exfoliated cells as well as the levels of Pb-210 in urine samples to evaluate the association between the smoking habit and toxic stress of transitional epithelial cells. The frequency of MN was scored from Giemsa-stained slides while exchange resin and beta counting techniques were employed to measure the concentrations of this radioisotope. Urine samples of smokers had levels of Pb-210 up to 158.65 mBq L^-1. For nonsmokers, the median was below the detection limit (45 mBq L^-1). The analyses of mononucleated cells showed a significant increase of the frequency of MN in smokers when compared to nonsmokers. Statistical tests showed a tight relation between the cigarette consumption and the increase of the frequency of MN, rather than with the levels of Pb-210 present in smoke particles. The results indicate the usefulness of the methodology for the evaluation of human health risks related to chronic contamination with Pb-210.

Caryophyllane sesquiterpenes inhibit DNA-damage by tobacco smoke in bacterial and mammalian cells

In the present study, the ability of the natural sesquiterpene β-caryophyllene (CRY) and its metabolite β-caryophyllene oxide (CRYO) to inhibit the genotoxicity of a condensate of cigarette smoke (CSC) was evaluated both in bacterial and mammalian cells. Also, the inhibition of the CSC-mediated STAT3 phosphorylation and intracellular oxidative stress was evaluated as potential chemopreventive mechanism. Under our experimental conditions, both the sesquiterpenes exhibited antimutagenic properties, being CRY the most potent compound. The antimutagenicity was highlighted in all experimental protocols, being particularly strong in the co- and post-treatments. The test substances also reduced the micronuclei frequency induced by CSC, with a major effectiveness of CRY. CRY was also able to reduce the CSC-mediated increase of the Y705- pSTAT3 levels, in spite of a lacking effect of CRYO. Furthermore, the sesquiterpenes CRY and CRYO displayed a moderate antioxidant activity, with a 25 % and 40 % inhibition of the ROS-levels increased by CSC, respectively. On the basis of these results, CRY seems to be a multi-target chemopreventive agent, although the genoprotective and antioxidant effects of CRYO suggest that both compounds deserve to be deeply investigated for a possible application in the prevention and treatment of different smoke-related ailments.

The tobacco carcinogen NNK disturbs mitotic chromosome alignment by interrupting p53 targeting to the centrosome

The tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is the most potent risk factor among tobacco-related carcinogens in lung cancer progression and outcomes. Although genetic mutations and chromosome instability have been detected in NNK-induced lung tumors, the oncogenic mechanisms of NNK are not fully understood. Here, we show that NNK increases chromosomal instability by disrupting spindle microtubule (MT) attachment to the kinetochore (KT) and spindle dynamics. Mechanistically, NNK blocks the targeting of p53 to the centrosome during mitosis, leading to chromosome alignment defects in metaphase. Therefore, lung cancer cells with wild-type p53, such as A594 and H226B, are more resistant to the NNK treatment than p53-mutant lung cancer cells, such as A1299 and H226Br. Although NNK does not affect the levels or transcriptional activity of p53, the reduction of the p53 level at the centrosome exacerbates the NNK-induced chromosome alignment defect in A549 and H226B cells. Therefore, p53 protects against NNK-induced chromosome instability by modulating the function of centrosome-localized p53 and not by modulating transcriptional activity. We conclude that NNK may increase the risk of lung cancer progression and poorer outcomes in patients with p53 mutations by perturbing proper mitotic progression and chromosome integrity.

5-Aza-2'-deoxycytidine protects against emphysema in mice via suppressing p16Ink4a expression in lung tissue

Background

There is a growing realization that COPD, or at least emphysema, involves several processes presenting in aging and cellular senescence. Endothelial progenitor cells (EPCs) contribute to neovascularization and play an important role in the development of COPD. The gene for p16^Ink4a is a major dominant senescence one. The aim of the present study was to observe changes in lung function, histomorphology of lung tissue, and expression of p16^Ink4a in lung tissue and bone marrow-derived EPCs in emphysematous mice induced by cigarette-smoke extract (CSE), and further to search for a potential candidate agent protecting against emphysema induced by CSE.

Materials and methods

An animal emphysema model was induced by intraperitoneal injection of CSE. 5-Aza-2′-deoxycytidine (5-Aza-CdR) was administered to the emphysematous mice. Lung function and histomorphology of lung tissue were measured. The p16^Ink4a protein and mRNA in EPCs and lung tissues were detected using Western blotting and quantitative reverse-transcription polymerase chain reaction, respectively.

Results

CSE induced emphysema with increased p16^Ink4a expression in lung tissue and bone marrow-derived EPCs. 5-Aza-CdR partly protected against emphysema, especially in the lung-morphology profile, and partly protest against the overexpression of p16^Ink4a in EPCs and lung tissue induced by CSE.

Conclusion

5-Aza-CdR partly protected against emphysema in mice via suppressing p16^Ink4a expression in EPCs and lung tissue.

ADAMTS5 Deficiency Protects Mice From Chronic Tobacco Smoking-induced Intervertebral Disc Degeneration

STUDY DESIGN

ADAMTS5-deficient and wild type (WT) mice were chronically exposed to tobacco smoke to investigate effects on intervertebral disc degeneration (IDD).

OBJECTIVE

The aim of this study was to demonstrate a role for ADAMTS5 in mediating tobacco smoking-induced IDD.

SUMMARY OF BACKGROUND DATA

We previously demonstrated that chronic tobacco smoking causes IDD in mice because, in part, of proteolytic destruction of disc aggrecan. However, it was unknown which matrix proteinase(s) drive these detrimental effects.

METHODS

Three-month-old WT (C57BL/6) and ADAMTS5 mice were chronically exposed to tobacco smoke (four cigarettes/day, 5 day/week for 6 months). ADAMTS-mediated cleavage of disc aggrecan was analyzed by Western blot. Disc total glycosaminoglycan (GAG) content was assessed by dimethyl methylene blue assay and safranin O/fast green histology. Vertebral osteoporosity was measured by microcomputed tomography. Human nucleus pulposus (hNP) cell cultures were also exposed directly to tobacco smoke extract (TSE), a condensate containing the water-soluble compounds inhaled by smokers, to measure ADAMTS5 expression and ADAMTS-mediated cleavage of aggrecan. Activation of nuclear factor (NF)-κB, a family of transcription factors essential for modulating the cellular response to stress, was measured by immunofluorescence assay.

RESULTS

Genetic depletion of ADAMTS5 prevented vertebral bone loss, substantially reduced loss of disc GAG content, and completely obviated ADAMTS-mediated proteolysis of disc aggrecan within its interglobular domain (IGD) in mice following exposure to tobacco smoke. hNP cell cultures exposed to TSE also resulted in upregulation of ADAMTS5 protein expression and a concomitant increase in ADAMTS-mediated cleavage within aggrecan IGD. Activation of NF-κB, known to be required for ADAMTS5 gene expression, was observed in both TSE-treated hNP cell cultures and disc tissue of tobacco smoke-exposed mice.

CONCLUSION

The findings demonstrate that ADAMTS5 is the primary aggrecanase mediating smoking-induced disc aggrecanolysis and IDD. Mouse models of chronic tobacco smoking are important and useful for probing the mechanisms of disc aggrecan catabolism and IDD.

LEVEL OF EVIDENCE

N/A.

A study of DNA damage in buccal cells of consumers of well- and/or tap-water using the comet assay: Assessment of occupational exposure to genotoxicants

Because of concerns that natural aquifers in the region of Todos Santos (Baja California Sur, Mexico) might be contaminated by organochlorine pesticides and heavy metals, a case-control study was conducted among consumers and non-consumers of well- and/or tap-water to determine risks to human health. This study was based on a genotoxic evaluation of buccal cells using the Comet assay technique. Levels of DNA damage in the consumers group were significantly higher than those of the control group. However, occupational exposure to genotoxicants showed to be the critical factor rather than water consumption. Taking into account the professions of well- and/or tap-water consumers, agricultural workers exposed directly (those who fumigated) or indirectly (those not involved in fumigating) to agrochemicals showed greater genetic damage than controls. This difference persisted even when age, and whether the person smoked or consumed alcoholic drinks were considered. These factors were not associated with the level of genetic damage observed. Chemical analyses of organochlorine pesticides and heavy metals were carried out to evaluate the water quality of wells, faucets, and surface water of canals consumed by the population and/or used for irrigation. High concentrations of α and β endosulfan were detected in water of surface canals. Although our inventory of agrochemicals employed in the region showed the use of products considered carcinogenic and/or mutagenic, they were not detected by the analytical techniques used. Heavy metals (arsenic, mercury, and lead) were detected in water of some wells used for irrigation and human consumption. Environ. Mol. Mutagen. 58:619-627, 2017. © 2017 Wiley Periodicals, Inc.

Abnormal white matter microstructure among early adulthood smokers: a tract-based spatial statistics study

Objectives Cigarette smoking is an important risk factor of central nervous system diseases. However, the white matter (WM) integrity of early adulthood chronic smokers has not been attached enough importance to as it deserves, and the relationship between the chronic smoking effect and the WM is still unclear. The purpose of this study was to investigate whole - brain WM microstructure of early adulthood smokers and explore the structural correlates of behaviorally relevant features of the disorder. Methods We compared multiple DTI-derived indices, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD), between early adulthood smokers (n = 19) and age-, education- and gender-matched controls (n = 23) using a whole-brain tract-based spatial statistics approach. We also explored the correlations of the mean DTI index values with pack-years and Fagerström Test for Nicotine Dependence. Results The smokers showed increased FA in left superior longitudinal fasciculus (SLF), left anterior corona radiate, left superior corona radiate, left posterior corona radiate, left external capsule (EC), left inferior fronto-occipital fasciculus and sagittal stratum (SS), and decreased RD in left SLF. There were significant negative correlations among the average FA in the left external capsule and pack-years in smokers. In addition, significant positive correlation was found between RD values in the left SLF and pack-years. Discussion These findings indicate that smokers show microstructural changes in several white-matter regions. The correlation between the cumulative effect and microstructural WM alternations suggests that WM properties may become the new biomarkers in practice.

A Study of the Feasibility of FDG-PET/CT to Systematically Detect and Quantify Differential Metabolic Effects of Chronic Tobacco Use in Organs of the Whole Body-A Prospective Pilot Study

RATIONALE AND OBJECTIVES

The aim of this study was to assess the feasibility of ¹⁸F-fluorodeoxyglucose (FDG)-positron emission tomography/computed tomography (PET/CT) to systematically detect and quantify differential effects of chronic tobacco use in organs of the whole body.

MATERIALS AND METHODS

Twenty healthy male subjects (10 nonsmokers and 10 chronic heavy smokers) were enrolled. Subjects underwent whole-body FDG-PET/CT, diagnostic unenhanced chest CT, mini-mental state examination, urine testing for oxidative stress, and serum testing. The organs of interest (thyroid, skin, skeletal muscle, aorta, heart, lung, adipose tissue, liver, spleen, brain, lumbar spinal bone marrow, and testis) were analyzed on FDG-PET/CT images to determine their metabolic activities using standardized uptake value (SUV) or metabolic volumetric product (MVP). Measurements were compared between subject groups using two-sample t tests or Wilcoxon rank-sum tests as determined by tests for normality. Correlational analyses were also performed.

RESULTS

FDG-PET/CT revealed significantly decreased metabolic activity of lumbar spinal bone marrow (MVPmean: 29.8 ± 9.7 cc vs 40.8 ± 11.6 cc, P = 0.03) and liver (SUVmean: 1.8 ± 0.2 vs 2.0 ± 0.2, P = 0.049) and increased metabolic activity of visceral adipose tissue (SUVmean: 0.35 ± 0.10 vs 0.26 ± 0.06, P = 0.02) in chronic smokers compared to nonsmokers. Normalized visceral adipose tissue volume was also significantly decreased (P = 0.04) in chronic smokers. There were no statistically significant differences in the metabolic activity of other assessed organs.

CONCLUSIONS

Subclinical organ effects of chronic tobacco use are detectable and quantifiable on FDG-PET/CT. FDG-PET/CT may, therefore, play a major role in the study of systemic toxic effects of tobacco use in organs of the whole body for clinical or research purposes.

Assessment of genotoxicity amongst smokers, alcoholics, and tobacco chewers of North India using micronucleus assay and urinary 8-hydroxyl-2'-deoxyguanosine, as biomarkers

The main objective of the present study was to screen the genotoxicity caused by individual and combined habits of smoking, tobacco chewing, and alcohol consumption in human population of North India. Study recruited 67 male subjects aged 25 to 65 years. Buccal mucosal cells were subjected to micronucleus (MN) assay, and 8-hydroxyl-2-deoxyguanosine (8-OHdG) was estimated in their urine samples. Number and shape of the MN cells varied in the buccal epithelium of different groups. Maximum number of MN (0.47%) were found in tobacco chewers followed by smokers (0.45%) and alcoholics (0.44%) (P < 0.05). These results reciprocated the concentration of urinary 8-OHdG. Maximum value for 8-OHdG was also recorded in tobacco chewers (21.07 ± 5.51 mg/mg creatinine) followed by smokers (20.25 ± 3.96 mg/mg creatinine) and alcoholics (19.06 ± 3.41 mg/mg creatinine) (P < 0.05). Combined effects of these agents were found to be statistically different from individual effects. Carcinogenic compounds present in cigarette smoke, nitrosamines found in solid tobacco, and acetaldehyde, a metabolic product of alcohol, induce oxidative stress that manifests into genotoxicity. In conclusion, demographical differences occur in the genotoxicity caused by these three habits. MN assay and urinary 8-OHdG are simple, noninvasive, and reliable biomarkers of genotoxicity.

Combinations of genotoxic tests for the evaluation of group 1 IARC carcinogens

Many of the known human carcinogens are potent genotoxins that are efficiently detected as carcinogens in human populations but certain types of compounds such as immunosuppressants, sex hormones, etc. act via non-genotoxic mechanism. The absence of genotoxicity and the diversity of modes of action of non-genotoxic carcinogens make predicting their carcinogenic potential extremely challenging. There is evidence that combinations of different short-term tests provide a better and efficient prediction of human genotoxic and non-genotoxic carcinogens. The purpose of this study is to summarize the in vivo and in vitro comet assay (CMT) results of group 1 carcinogens selected from the International Agency for Research on Cancer and to discuss the utility of the comet assay along with other genotoxic assays such as Ames, in vivo micronucleus (MN), and in vivo chromosomal aberration (CA) test. Of the 62 agents for which valid genotoxic data were available, 38 of 61 (62.3%) were Ames test positive, 42 of 60 (70%) were in vivo MN test positive and 36 of 45 (80%) were positive for the in vivo CA test. Higher sensitivity was seen in in vivo CMT (90%) and in vitro CMT (86.9%) assay. Combination of two tests has greater sensitivity than individual tests: in vivo MN + in vivo CA (88.6%); in vivo MN + in vivo CMT (92.5%); and in vivo MN + in vitro CMT (95.6%). Combinations of in vivo or in vitro CMT with other tests provided better sensitivity. In vivo CMT in combination with in vivo CA provided the highest sensitivity (96.7%).

Cigarette Smoke Extract Changes Expression of Endothelial Nitric Oxide Synthase (eNOS) and p16(INK4a) and is Related to Endothelial Progenitor Cell Dysfunction

BACKGROUND Endothelial dysfunction is an important pathophysiologic feature in many smoke-related diseases. Endothelial progenitor cells (EPCs) are the precursors of endothelial cells and play a fundamental role in the maintenance of endothelial integrity and function. Endothelial nitric oxide synthase (eNOS) is the dominant NOS isoform in the vasculature and plays a central role in the maintenance of endothelial homeostasis. p16(INK4a) is a cyclin-dependent kinase inhibitor and could be regarded as a major dominant senescence gene. The present study aimed to determine whether the expression of eNOS and p16(INK4a) in EPCs is related to EPCs function and the possible epigenetic mechanism, if any. MATERIAL AND METHODS We investigated EPCs capacity for proliferation, adhesion, and secretion, and the expression of eNOS and p16(INK4a) in EPCs which were altered by cigarette smoke extract (CSE) in vitro. Furthermore, Decitabine (Dec), an agent of demethylation, was used to examine whether it could alter the changes induced by CSE. RESULTS The present study demonstrated that EPCs altered by CSE in vitro displayed decreased capacities of proliferation, adhesion, and secretion, which was accompanied by decreased eNOS expression and increased p16(INK4a) expression in EPCs. Furthermore, Dec could alleviate the changes in the expression of eNOS and p16(INK4a), and protect against the EPCs dysfunction caused by CSE. CONCLUSIONS The decreased eNOS expression and increased p16(INK4a) expression was associated with dysfunction of EPCs caused by CSE. The mechanism of methylation, one of the most common epigenetic mechanism, may be involved in the EPCs dysfunction caused by CSE.

From sperm to offspring: Assessing the heritable genetic consequences of paternal smoking and potential public health impacts

Individuals who smoke generally do so with the knowledge of potential consequences to their own health. What is rarely considered are the effects of smoking on their future children. The objective of this work was to review the scientific literature on the effects of paternal smoking on sperm and assess the consequences to offspring. A literature search identified over 200 studies with relevant data in humans and animal models. The available data were reviewed to assess the weight of evidence that tobacco smoke is a human germ cell mutagen and estimate effect sizes. These results were used to model the potential increase in genetic disease burden in offspring caused by paternal smoking, with specific focus on aneuploid syndromes and intellectual disability, and the socioeconomic impacts of such an effect. The review revealed strong evidence that tobacco smoking is associated with impaired male fertility, and increases in DNA damage, aneuploidies, and mutations in sperm. Studies support that these effects are heritable and adversely impact the offspring. Our model estimates that, with even a modest 25% increase in sperm mutation frequency caused by smoke-exposure, for each generation across the global population there will be millions of smoking-induced de novo mutations transmitted from fathers to offspring. Furthermore, paternal smoking is estimated to contribute to 1.3 million extra cases of aneuploid pregnancies per generation. Thus, the available evidence makes a compelling case that tobacco smoke is a human germ cell mutagen with serious public health and socio-economic implications. Increased public education should be encouraged to promote abstinence from smoking, well in advance of reproduction, to minimize the transmission of harmful mutations to the next-generation.

Evaluation of baseline frequency of sister chromatid exchanges in an Italian population according to age, sex, smoking habits, and gene polymorphisms

OBJECTIVES

Increased SCEs frequencies in human lymphocytes are an indicator of spontaneous chromosome instability and could be influenced by different exogenous and endogenous factors. In this study, we evaluated the influence of age, sex, smoking habits, and genetic polymorphisms on the background levels of SCEs in peripheral blood lymphocytes.

METHODS

Two hundred-thirty healthy Italian subjects were recruited. Data about age, sex and smoking habits were recorded. Subjects were also genotyped for GSTT1, GSTM1, GSTP1 A/G, CYP1A1 Ile/Val, CYP2C19 G/A, ERCC2/XPD Lys751Gln, XRCC1 Arg194ATrp, XRCC1 Arg399Gln, and XRCC1Arg208His gene polymorphisms.

RESULTS

The frequency of SCEs/cell was 5.15 ± 1.87, with females showing a significantly higher SCEs value with respect to males (5.36 ± 2.10 and 4.82 ± 1.39, respectively). Smokers showed significantly increased levels of SCEs with respect to nonsmokers (5.93 ± 1.75 and 4.70 ± 1.79, respectively) whereas no differences were observed between heavy and light smokers. Age correlated with the RI value (P = .01) but not with the SCEs frequency (P = 07), although the 31-40 age group showed a significantly lower SCEs frequency with respect to the other age groups. A significant association was also found between GSTP2C19-AA, GSTT1-null, GSTM1-null, ERCC2/XPD Gln751Gln, and XRCC1 His208His genotypes, and higher frequencies of SCEs.

CONCLUSION

We describe the association between some phase I, phase II, and DNA-repair gene polymorphisms with increased SCEs frequencies, reinforcing the importance of genetic analysis in biomonitoring studies. Sex and age were found to be important endogenous factors that affect the level of genomic damage and the replicative capacity of cells, respectively.

Rotating night work, lifestyle factors, obesity and promoter methylation in BRCA1 and BRCA2 genes among nurses and midwives

Some recent evidence suggests that environmental and lifestyle factors may modify DNA methylation. We hypothesized that rotating night work and several modifiable factors may be associated with the methylation of the promoter regions within two tumor suppressor and DNA repair genes: BRCA1 and BRCA2. The methylation status of BRCA1 and BRCA2 was determined via qMSP reactions using DNA samples derived from blood leucocytes of 347 nurses and midwives working rotating nights and 363 working during the days. The subjects were classified into unmethylated vs methylated BRCA1 and BRCA2 when the methylation index was 0% or >0%, respectively. The adjusted odds ratios with 95% confidence intervals were calculated for night work status, smoking, obesity, physical activity and alcohol drinking. Current night shift work or night work history was not associated with methylation status of the promoter sites within BRCA1 and BRCA2 genes. We observed weak associations between smoking and the methylation status of BRCA1 with OR = 1.50 (95%CI: 0.98–2.29) for current smoking, OR = 1.83, 95CI: 1.08–3.13 for smoking longer than 31 years, and 0.1>p>0.05 for trends for the number of cigarettes per day, smoking duration and packyears. In conclusion, no links between night shift work and methylation of the promoter region within the BRCA1, and BRCA2 genes were observed in this exploratory analysis. The findings of our study weakly support the hypothesis that smoking may contribute to epigenetic events.

AKR1C1 as a Biomarker for Differentiating the Biological Effects of Combustible from Non-Combustible Tobacco Products

Smoking has been established as a major risk factor for developing oral squamous cell carcinoma (OSCC), but less attention has been paid to the effects of smokeless tobacco products. Our objective is to identify potential biomarkers to distinguish the biological effects of combustible tobacco products from those of non-combustible ones using oral cell lines. Normal human gingival epithelial cells (HGEC), non-metastatic (101A) and metastatic (101B) OSCC cell lines were exposed to different tobacco product preparations (TPPs) including cigarette smoke total particulate matter (TPM), whole-smoke conditioned media (WS-CM), smokeless tobacco extract in complete artificial saliva (STE), or nicotine (NIC) alone. We performed microarray-based gene expression profiling and found 3456 probe sets from 101A, 1432 probe sets from 101B, and 2717 probe sets from HGEC to be differentially expressed. Gene Set Enrichment Analysis (GSEA) revealed xenobiotic metabolism and steroid biosynthesis were the top two pathways that were upregulated by combustible but not by non-combustible TPPs. Notably, aldo-keto reductase genes, AKR1C1 and AKR1C2, were the core genes in the top enriched pathways and were statistically upregulated more than eight-fold by combustible TPPs. Quantitative real time polymerase chain reaction (qRT-PCR) results statistically support AKR1C1 as a potential biomarker for differentiating the biological effects of combustible from non-combustible tobacco products.

Identification of an atypical etiological head and neck squamous carcinoma subtype featuring the CpG island methylator phenotype

Head and neck squamous cell carcinoma (HNSCC) is broadly classified into HNSCC associated with human papilloma virus (HPV) infection, and HPV negative HNSCC, which is typically smoking-related. A subset of HPV negative HNSCCs occur in patients without smoking history, however, and these etiologically 'atypical' HNSCCs disproportionately occur in the oral cavity, and in female patients, suggesting a distinct etiology. To investigate the determinants of clinical and molecular heterogeneity, we performed unsupervised clustering to classify 528 HNSCC patients from The Cancer Genome Atlas (TCGA) into putative intrinsic subtypes based on their profiles of epigenetically (DNA methylation) deregulated genes. HNSCCs clustered into five subtypes, including one HPV positive subtype, two smoking-related subtypes, and two atypical subtypes. One atypical subtype was particularly genomically stable, but featured widespread gene silencing associated with the 'CpG island methylator phenotype' (CIMP). Further distinguishing features of this 'CIMP-Atypical' subtype include an antiviral gene expression profile associated with pro-inflammatory M1 macrophages and CD8+ T cell infiltration, CASP8 mutations, and a well-differentiated state corresponding to normal SOX2 copy number and SOX2OT hypermethylation. We developed a gene expression classifier for the CIMP-Atypical subtype that could classify atypical disease features in two independent patient cohorts, demonstrating the reproducibility of this subtype. Taken together, these findings provide unprecedented evidence that atypical HNSCC is molecularly distinct, and postulates the CIMP-Atypical subtype as a distinct clinical entity that may be caused by chronic inflammation.

Biomarkers of the health outcomes associated with ambient particulate matter exposure

Epidemiologic evidence supports the positive association of cardiopulmonary morbidity and mortality, and lung cancer risk with exposure to airborne particulate matter (PM). Oxidative stress and inflammation have been proposed to be the major causal factors involved in mediating PM effects on both cardiovascular and pulmonary health outcomes. However, the mechanism whereby PM causes the health effects is not fully elucidated. To evaluate and investigate human exposure to PM, it is essential to have a specific, sensitive and robust characterization of individual exposure to PM. Biomarkers may mark important intermediate steps leading to overt health effects after PM exposure. Thus biomarkers are promising indicators, which could serve as representative measures of the exposure to PM for assessing the health impacts and understanding the mechanism. Indeed, a number of biomarkers are already in use in the field of epidemiological studies and toxicological research. However, we are facing now the challenges to select robust, specific and sensitive biomarkers, which can be employed in large-scale of population to assess the health risk and to monitor the effectiveness of interventions. In this review, we describe a range of biomarkers that are associated with air pollution exposure, particularly markers of oxidative stress, inflammatory factors, and microRNAs, as well as markers of pollutants metabolites. Understanding the nature of the association of these biomarkers with PM exposure may shed some light on the process of selecting biomarkers for large-scale population studies, developing novel preventative and therapeutic strategies.

Tobacco nitrosamine NNK increases ALDH-positive cells via ROS-Wnt signaling pathway in A549 human lung cancer cells

Epidemiological studies suggest that lung cancer, which is a major cause of cancer death, has a critical association with cigarette smoking. Tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in cigarette smoke is a major risk factor for carcinogenesis. However, the mechanisms by which NNK promotes cancer development have not been fully elucidated. Growing evidence suggests that lung cancer originates from cancer stem cells (CSCs), which are a minor population of lung cancer cells. In the present study, we investigated the effects of NNK on the CSCs in A549 human lung cancer cells using flow cytometry with aldehyde dehydrogenase (ALDH), a functional marker of CSCs. We found that NNK increased the proportion of ALDH-positive cells in a dose-dependent manner. A Wnt inhibitor PNU74654 reduced NNK-induced expression levels of Wnt target gene Dkk1 and increase in ALDH-positive cells. We next examined the signaling pathway that mediates the NNK-induced increase in ALDH-positive cells via Wnt signaling. DCF assay revealed that NNK induced reactive oxygen species (ROS) production. The ROS scavenger N-acetylcysteine (NAC) inhibited the NNK-induced Wnt activation and increase in ALDH-positive cells. These data suggest that NNK-induced ROS activate the Wnt signaling pathway in A549 cells. These findings would provide new insights into the role of NNK in the lung CSCs.

Modulation by Ethanol of Cigarette Smoke Clastogenicity in Cells of Adult Mice and of Transplacentally Exposed Fetuses

Cigarette smoke (CS) and ethanol (EtOH) are known to synergize in the causation of cancers of the upper aerodigestive tract and of the liver. Little is known about possible interactions between these agents in other organs. These premises prompted us to evaluate the clastogenic effects resulting from the inhalation for 3 weeks of mainstream CS and oral administration of EtOH, which were tested either individually or in combination in cells of adult BDF1 mice and their fetuses. CS exerted clastogenic effects in haematopoietic cells of adult male mice by increasing the frequency of micronucleated erythroid cells both in bone marrow and in peripheral blood as well as the frequency of micronucleated and polynucleated pulmonary alveolar macrophages. Likewise, exposure to CS of pregnant mice resulted in a clastogenic damage in maternal bone marrow cells and in the liver and peripheral blood of their fetuses. Under all experimental conditions, EtOH was consistently devoid of clastogenic effects when given alone. In adult mice, EtOH exhibited a mild stimulating effect on the clastogenicity of CS in haematopoietic cells, while an opposite effect was observed in the respiratory tract, where EtOH attenuated the cytogenetic alterations induced by CS in pulmonary alveolar macrophages. At variance with the mild synergism observed in haematopoietic cells of adult mice, EtOH inhibited the clastogenicity of CS in the liver and peripheral blood cells of transplacentally exposed fetuses. Therefore, the effects of EtOH in CS-exposed mice show different trends depending both on the life stage and on the cells analyzed.