Dataset Information

Diesel exhaust influences carcinogenic PAH-induced genotoxicity and gene expression in human breast epithelial cells in culture.

ABSTRACT: The carcinogenic polycyclic aromatic hydrocarbon (PAHs) benzo[a]pyrene (B[a]P) and dibenzo[a,l]pyrene (DB[a,l]P) are widespread environmental pollutants, however their toxicological effects within a mixture is not established. We investigated the influence of diesel exhaust (DE) on B[a]P and DB[a,l]P-induced PAH-DNA adduct formation, metabolic activation, gene expression and 8-oxo-dG adduct levels in human breast epithelial cells (MCF-10A) in culture. Following 24 and 48h, cells co-exposed to DE plus B[a]P exhibited a significant decrease in PAH-DNA adduct levels, compared with B[a]P alone, as determined by (33)P-postlabeling combined with reversed-phase high performance liquid chromatography (HPLC). Cytochrome P450 (CYP) enzyme activity, as measured by the ethoxyresorufin O-deethylase (EROD) assay and CYP1B1 expression, significantly increased with co-exposure of DE plus DB[a,l]P, compared with DB[a,l]P alone. Aldo keto-reductase (AKR)1C1, AKR1C2, and AKR1C3 expression also significantly increased in cells exposed to DE plus PAH, compared with PAH exposure alone. Cell populations exhibiting 8-oxo-dG adducts significantly increased in response to exposure to B[a]P or DE plus B[a]P for 24h, compared with vehicle control, as quantified by flow cytometry. These results suggest that complex mixtures may modify the carcinogenic potency of PAH by shifting the metabolic activation pathway from the production of PAH diol-epoxides to AKR pathway-derived metabolites.

SUBMITTER: Courter LA

PROVIDER: S-EPMC2815343 | biostudies-literature | 2007 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Diesel exhaust influences carcinogenic PAH-induced genotoxicity and gene expression in human breast epithelial cells in culture.

Courter Lauren A LA Pereira Cliff C Baird William M WM

Mutation research 20070521 1-2

The carcinogenic polycyclic aromatic hydrocarbon (PAHs) benzo[a]pyrene (B[a]P) and dibenzo[a,l]pyrene (DB[a,l]P) are widespread environmental pollutants, however their toxicological effects within a mixture is not established. We investigated the influence of diesel exhaust (DE) on B[a]P and DB[a,l]P-induced PAH-DNA adduct formation, metabolic activation, gene expression and 8-oxo-dG adduct levels in human breast epithelial cells (MCF-10A) in culture. Following 24 and 48h, cells co-exposed to DE ...[more]

PMID: 17612574

Similar Datasets

Project description:BackgroundWhile exposure to diesel exhaust particles has been linked to aberrant immune responses in allergic diseases such as asthma, little attention has been paid to their effects on the airway epithelial barrier. In this study, we sought to determine the effect of diesel exhaust exposure on airway epithelial barrier function and composition using in vitro and in vivo model systems.Methods16HBE14o- human bronchial epithelial cells were grown on collagen coated Transwell inserts and exposed to 5 to 50 μg/cm2 SRM 2975 diesel particulate matter (DEP) suspended in cell culture medium or vehicle controls. Changes in barrier function were assessed by measuring transepithelial electrical resistance (TEER) and permeability to 4 kDa FITC Dextran. Neonatal BALB/c mice were exposed to aerosolized DEP (255 ± 89 μg/m3; 2 h per day for 5 days) and changes in the tight junction protein Tricellulin were assessed 2 weeks post exposure.ResultsA six-hour incubation of epithelial cells with diesel exhaust particles caused a significant concentration-dependent reduction in epithelial barrier integrity as measured by decreased TEER and increased permeability to 4 kDa FITC-Dextran. This reduction in epithelial barrier integrity corresponded to a significant reduction in expression of the tight junction protein Tricellulin. siRNA mediated knockdown of Tricellulin recapitulated changes in barrier function caused by DEP exposure. Neonatal exposure to aerosolized DEP caused a significant reduction in lung Tricellulin 2 weeks post exposure at both the protein and mRNA level.ConclusionShort term exposure to DEP causes a significant reduction in epithelial barrier integrity through a reduction in the tight junction protein Tricellulin. Neonatal exposure to aerosolized DEP caused a significant and sustained reduction in Tricellulin protein and mRNA in the lung, suggesting that early life exposure to inhaled DEP may cause lasting changes in airway epithelial barrier function.

Project description:BackgroundMost studies of the association between diesel exhaust exposure and lung cancer suggest a modest, but consistent, increased risk. However, to our knowledge, no study to date has had quantitative data on historical diesel exposure coupled with adequate sample size to evaluate the exposure-response relationship between diesel exhaust and lung cancer. Our purpose was to evaluate the relationship between quantitative estimates of exposure to diesel exhaust and lung cancer mortality after adjustment for smoking and other potential confounders.MethodsWe conducted a nested case-control study in a cohort of 12 315 workers in eight non-metal mining facilities, which included 198 lung cancer deaths and 562 incidence density-sampled control subjects. For each case subject, we selected up to four control subjects, individually matched on mining facility, sex, race/ethnicity, and birth year (within 5 years), from all workers who were alive before the day the case subject died. We estimated diesel exhaust exposure, represented by respirable elemental carbon (REC), by job and year, for each subject, based on an extensive retrospective exposure assessment at each mining facility. We conducted both categorical and continuous regression analyses adjusted for cigarette smoking and other potential confounding variables (eg, history of employment in high-risk occupations for lung cancer and a history of respiratory disease) to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Analyses were both unlagged and lagged to exclude recent exposure such as that occurring in the 15 years directly before the date of death (case subjects)/reference date (control subjects). All statistical tests were two-sided.ResultsWe observed statistically significant increasing trends in lung cancer risk with increasing cumulative REC and average REC intensity. Cumulative REC, lagged 15 years, yielded a statistically significant positive gradient in lung cancer risk overall (P (trend) = .001); among heavily exposed workers (ie, above the median of the top quartile [REC ≥ 1005 μg/m(3)-y]), risk was approximately three times greater (OR = 3.20, 95% CI = 1.33 to 7.69) than that among workers in the lowest quartile of exposure. Among never smokers, odd ratios were 1.0, 1.47 (95% CI = 0.29 to 7.50), and 7.30 (95% CI = 1.46 to 36.57) for workers with 15-year lagged cumulative REC tertiles of less than 8, 8 to less than 304, and 304 μg/m(3)-y or more, respectively. We also observed an interaction between smoking and 15-year lagged cumulative REC (P (interaction) = .086) such that the effect of each of these exposures was attenuated in the presence of high levels of the other.ConclusionOur findings provide further evidence that diesel exhaust exposure may cause lung cancer in humans and may represent a potential public health burden.

Project description:The potential effects of combinations of dilute whole diesel exhaust (DE) and ozone (O?), each a common component of ambient airborne pollutant mixtures, on lung function were examined. Healthy young human volunteers were exposed for 2 hr to pollutants while exercising (~50 L/min) intermittently on two consecutive days. Day 1 exposures were either to filtered air, DE (300 ?g/m³), O? (0.300 ppm), or the combination of both pollutants. On Day 2 all exposures were to O? (0.300 ppm), and Day 3 served as a followup observation day. Lung function was assessed by spirometry just prior to, immediately after, and up to 4 hr post-exposure on each exposure day. Functional pulmonary responses to the pollutants were also characterized based on stratification by glutathione S-transferase mu 1 (GSTM1) genotype. On Day 1, exposure to air or DE did not change FEV1 or FVC in the subject population (n?=?15). The co-exposure to O? and DE decreased FEV1 (17.6%) to a greater extent than O? alone (9.9%). To test for synergistic exposure effects, i.e., in a greater than additive fashion, FEV1 changes post individual O? and DE exposures were summed together and compared to the combined DE and O? exposure; the p value was 0.057. On Day 2, subjects who received DE exposure on Day 1 had a larger FEV1 decrement (14.7%) immediately after the O? exposure than the individuals' matched response following a Day 1 air exposure (10.9%). GSTM1 genotype did not affect the magnitude of lung function changes in a significant fashion. These data suggest that altered respiratory responses to the combination of O? and DE exposure can be observed showing a greater than additive manner. In addition, O?-induced lung function decrements are greater with a prior exposure to DE compared to a prior exposure to filtered air. Based on the joint occurrence of these pollutants in the ambient environment, the potential exists for interactions in more than an additive fashion affecting lung physiological processes.

Dataset Information

Diesel exhaust influences carcinogenic PAH-induced genotoxicity and gene expression in human breast epithelial cells in culture.

Publications

Diesel exhaust influences carcinogenic PAH-induced genotoxicity and gene expression in human breast epithelial cells in culture.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets