Dose- and time- effect responses of DNA methylation and histone H3K9 acetylation changes induced by traffic-related air pollution.

As an important risk factor of respiratory disorders, traffic-related air pollution (TRAP) has caused extensive concerns. Epigenetic change has been considered a link between TRAP and respiratory diseases. However, the exact effects of TRAP on epigenetic changes are still unclear. Here we investigated the dose- and time- effect responses of TRAP on DNA methylations and H3K9 acetylation (H3K9ac) in both blood and lung tissues of rats. The findings showed that every 1 µg/m3 increase of TRAP components were associated with changes in %5 mC (95% CI) in LINE-1, iNOS, p16CDKN2A, and APC ranging from -0.088% (-0.150, -0.026) to 0.102 (0.049, 0.154), as well as 0.276 (0.053, 0.498) to 0.475 (0.103, 0.848) ng/mg increase of H3K9ac. In addition, every 1 more day exposure at high level of TRAP (in tunnel) also significantly changed the levels of DNA methylation (ranging from -0.842% to 0.248%) and H3K9ac (16.033 and 15.718 ng/mg pro in PBMC and lung tissue, respectively) changes. Season and/or sex could interact with air pollutants in affecting DNA methylation and H3K9ac. The findings showed that TRAP exposure is dose- and time- dependently associated with the changes of DNA methylation and H3K9ac.

Cigarette Smoking, BPDE-DNA Adducts, and Aberrant Promoter Methylations of Tumor Suppressor Genes (TSGs) in NSCLC from Chinese Population.

Non-small cell lung cancer (NSCLC) is related to the genetic and epigenetic factors. The goal of this study was to determine association of cigarette smoking and BPDE-DNA adducts with promoter methylations of several genes in NSCLC. Methylation of the promoters of p16, RARß, DAPK, MGMT, and TIMP-3 genes of tumor tissues from 199 lung cancer patients was analyzed with methylation-specific PCR (MSP), and BPDE-DNA adduct level in lung cancer tissue was obtained by ELISA. Level of BPDE-DNA adduct increased significantly in males, aged people (over 60 years), and smokers; however, no significant difference was found while comparing the BPDE-DNA adduct levels among different tumor types, locations, and stages. Cigarette smoking was also associated with increased BPDE-DNA adducts level (OR = 2.43, p > .05) and increased methylation level in at least 1 gene (OR = 5.22, p < .01), both in dose-response manner. Similarly, cigarette smoking also significantly increase the risk of p16 or DAPK methylation (OR = 3.02, p < .05 for p16, and 3.66, p < .05 for DAPK). The highest risk of BPDE-DNA adducts was detected among individuals with cigarette smoking for more than 40 pack-years (OR = 4.21, p < .01). Furthermore, the present study did not show that BPDE-DNA adducts are significantly associated with abnormal TSGs methylations in NSCLC, including SCC and AdO, respectively. Conclusively, cigarette smoking is significantly associated with the increase of BPDE-DNA adduct level, promoter hypermethylation of p16 and DAPK genes, while BPDE-DNA adduct was not significantly related to abnormal promoter hypermethylation in TSGs, suggesting that BPDE-DNA adducts and TSGs methylations play independent roles in NSCLC.

H3K9 acetylation change patterns in rats after exposure to traffic-related air pollution.

Traffic-related air pollution (TRAP) has been acknowledged as a potential risk factor for numerous respiratory disorders including lung cancer; however, the exact mechanisms involved are still unclear. Here we investigated the effects of TRAP exposure on the H3K9 acetylation in rats. The exposure was performed in both spring and autumn with identical study procedures. In each season, 48 healthy Wistar rats were exposed to different levels of TRAP for 4 h, 7 d, 14 d, and 28 d, respectively. H3K9 acetylation levels in both the peripheral blood mononuclear cells (PBMCs) and lung tissues were quantified. Multiple linear regression was applied to assess the influence of air pollutants on H3K9 acetylation levels. The levels of PM2.5, PM10, and NO2 in the tunnel and crossroad groups were significantly higher than in the control group. The H3K9 acetylation levels were not significantly different between spring and autumn. When spring and autumn data were analyzed together, no significant association between the TRAP and H3K9 acetylation was found in 4h exposure window. However, in the 7 d exposure window, PM2.5 and PM10 exposures were associated with changes in H3K9 acetylation ranging from 0.276 (0.053, 0.498) to 0.475 (0.103, 0.848) per 1 µg/m(3) increase in the pollutant concentration. In addition, prolonged exposure of the rats in the tunnel showed that both PM2.5 and PM10 concentrations were positively associated with H3k9 acetylation in both PBMCs and lung tissues. The findings showed that 7-d and prolonged TRAP exposure could effectively increase the H3K9 acetylation level in both PBMCs and lung tissues of rats.

Characteristics of DNA methylation changes induced by traffic-related air pollution.

Traffic-related air pollution (TRAP) is a potential risk factor for numerous respiratory disorders, including lung cancer, while alteration of DNA methylation may be one of the underlying mechanisms. However, the effects of TRAP mixtures on DNA methylation have not been investigated. We have studied the effects of brief or prolonged TRAP exposures on DNA methylation in the rat. The exposures were performed in spring and autumn, with identical study procedures. In each season, healthy Wistar rats were exposed to TRAP at for 4 h, 7 d, 14 d, or 28 d. Global DNA methylation (LINE-1 and Alu) and specific gene methylation (p16(CDKN2A), APC, and iNOS) in the DNA from blood and lung tissues were quantified by pyrosequencing. Multiple linear regression was applied to assess the influence of air pollutants on DNA methylation levels. The levels of PM2.5, PM10, and NO2 in the high and moderate groups were significantly higher than in the control group. The DNA methylation levels were not significantly different between spring and autumn. When spring and autumn data were analyzed together, PM2.5, PM10, and NO2 exposures were associated with changes in%5mC (95% CI) in LINE-1, iNOS, p16(CDKN2A), and APC ranging from -0.088 (-0.150, -0.026) to 0.102 (0.049, 0.154) per 1 µg/m(3) increase in the pollutant concentration. Prolonged exposure to a high level of TRAP was negatively associated with LINE-1 and iNOS methylation, and positively associated with APC methylations in the DNA from lung tissues but not blood. These findings show that TRAP exposure is associated with decreased methylation of LINE-1 and iNOS, and increased methylation of p16(CDKN2A) and APC.

[Relationship between Line 1 methylation and clinical data of non-small cell lung cancer].

OBJECTIVE: To explore the impact of Line-1 methylation on clinical features of non-small cell lung cancer and its connection with smoking and other living habits. METHODS: Pyrosequencing was used to determine the extent of Line-1 methylation in cancer and adjacent tissues derived from 197 patients with primary non-small cell lung cancer. Non-conditional logistic regression analysis was performed to correlate the level of Line-1 methylation with clinical features and living habits of the patients. RESULTS: Line-1 methylation for cancer tissue and adjacent tissue has measured 68.20±11.63 and 78.90±2.09, respectively (P < 0.01), and has been associated with TNM staging, smoking history and histopathological types. CONCLUSION: Lung cancer tissue Line-1 methylation level is closely related with clinical features and smoking. There is also a correlation between histopathological types of lung cancer and relative hypomethylation of Line-1.

Aberrant promoter methylation of cell adhesion-related genes associated with clinicopathologic features in non-small cell lung cancer in China.

PURPOSE: The aim of this study was to investigate the methylation status of three cell adhesion-related genes including CDH1, TSLC1 and TIMP3 in non-small cell lung cancer and explore its association with clinicopathologic features and various environmental risk factors. METHODS: We detected the aberrant methylation presence of these genes by methylation-specific polymerase chain reaction and analyzed the potential correlations with multivariate logistic regression model as well as stepwise logistic regression. RESULTS: For CDH1, promoter methylation was less frequent in adenosquamous carcinomas than adenocarcinomas (OR=0.35, 95%CI=0.13-0.96); pickled food increased the methylation frequency (OR=2.23, 95%CI=1.09-4.54) while light smoking and fruit intake decreased that (OR=0.43, 95%CI=0.19-0.97; OR=0.37, 95%CI=0.15-0.95). For TSLC1, males and toxin exposure increased methylation frequency (OR=6.25, 95%CI=1.05-37.13; OR=2.42, 95%CI=1.01-5.77) while light smoking and radiation exposure decreased that (OR=0.14, 95%CI=0.03-0.60; OR=0.17, 95%CI=0.04-0.87). For TIMP3, males showed lower methylation frequency than females (OR=0.18, 95%CI=0.04-0.88) while central lung cancer, heavy smoking and radiation exposure presented higher aberrant DNA methylation status (OR=2.19, 95%CI=1.07-4.52; OR=6.99, 95%CI=1.32-37.14; OR=2.30, 95%CI=1.04-5.08). CONCLUSIONS: Aberrant promoter methylation of cell adhesion-related tumor suppressor genes in lung cancer displayed varieties of gene-specific correlations with clinicopathologic features and various environmental risk factors.