The goal of the present study was to explore the effects of traffic-related air pollution exposure on DNA methylation. Into five groups of 6, 30 healthy Wistar rats were randomly divided. Three groups of rats were then exposed to traffic-related air pollution at high (tunnel), moderate (crossroad), and low (control) pollution levels for 7 d, whereas the two other groups were exposed in the tunnel for 14 d/28 d. The levels of PM10 and NO2 were measured during the exposure. The study was performed in spring and autumn, and lung tissue and blood were collected after the exposure. Promoter methylation levels of p 53 , MGMT, and MAGE-A 4 were quantified via pyrosequencing. The levels of PM10 and NO2 in the crossroad and tunnel groups were significantly higher than those in the control group. After 7 d exposure in autumn, promoter methylation levels of p 53 and MGMT in lung tissue significantly decreased, and the methylation status continued to decrease with increasing exposure time; MAGE-A 4 was highly methylated and showed no difference among the three groups. DNA methylation in lung tissue was more likely to be changed compared with that in blood during 7 d exposure. As the exposure time increased, DNA methylation changes between blood and lung tissue started to coincide. In lung tissue, PM10 exposure was significantly associated with decreased p 53 promoter methylation (r=-0.347, P=0.038) and NO2 exposure was significantly associated with decreased promoter methylation of p 53, MGMT, and MAGE-A 4 (r=-0.482, -0.444, and -0.346, respectively; P< 0.05). In blood, PM10 and NO2 were significantly and positively associated with MAGE-A 4 promoter methylation (r=0.395 and 0.431, respectively; P< 0.05). Traffic-related air pollution exposure may induce promoter hypomethylation of p 53 and MGMT.
Keywords: DNA methylation; MGMT; exposure; p 53; traffic-related air pollution.