Changes in DNA Methylation Patterns in Subjects Exposed to Low-Dose Benzene

Abstract

Aberrant DNA methylation patterns, including global hypomethylation, gene-specific hypermethylation/hypomethylation, and loss of imprinting (LOI), are common in acute myelogenous leukemia (AML) and other cancer tissues. We investigated for the first time whether such epigenetic changes are induced in healthy subjects by low-level exposure to benzene, a widespread pollutant associated with AML risk. Blood DNA samples and exposure data were obtained from subjects with different levels of benzene exposure, including 78 gas station attendants, 77 traffic police officers, and 58 unexposed referents in Milan, Italy (personal airborne benzene range, <6-478 Mg/m 3 ). Bisulfite-PCR pyrosequencing was used to quantitate DNA methylation in long interspersed nuclear element-1 (LINE-1) and AluI repetitive elements as a surrogate of genome-wide methylation and examine genespecific methylation of MAGE-1 and p15. Allele-specific pyrosequencing of the H19 gene was used to detect LOI in 96 subjects heterozygous for the H19 imprinting center G/A single-nucleotide polymorphism. Airborne benzene was associated with a significant reduction in LINE-1 (À2.33% for a 10-fold increase in airborne benzene levels; P = 0.009) and AluI (À1.00%; P = 0.027) methylation. Hypermethylation in p15 (+0.35%; P = 0.018) and hypomethylation in MAGE-1 (À0.49%; P = 0.049) were associated with increasing airborne benzene levels. LOI was found only in exposed subjects (4 of 73, 5.5%) and not in referents (0 of 23, 0.0%). However, LOI was not significantly associated with airborne benzene (P > 0.20). This is the first human study to link altered DNA methylation, reproducing the aberrant epigenetic patterns found in malignant cells, to low-level carcinogen exposure. [Cancer Res 2007;67(3):876-80]

BDNF rs6265 methylation and genotype interact on risk for schizophrenia

“…DNA was extracted from PBMCs using QIAamp DNA Blood Midi Kit (Qiagen, Valencia, CA, US) and bisulfite treated as described previously. 60 Methylation analysis was performed with pyrosequencing, using primer sequences previously reported 36 and focused on CpG methylation sites in the region of the BDNF gene containing rs6265. A consensus LINE-1 sequence was also analyzed to estimate global DNA methylation, 60 in order to exclude any global effect (see Supplementary Results for LINE-1 methylation results).…”

“…60 Methylation analysis was performed with pyrosequencing, using primer sequences previously reported 36 and focused on CpG methylation sites in the region of the BDNF gene containing rs6265. A consensus LINE-1 sequence was also analyzed to estimate global DNA methylation, 60 in order to exclude any global effect (see Supplementary Results for LINE-1 methylation results). Methylation was expressed as percentage of methylated cytosines divided by the sum of methylated and unmethylated cytosines (%5mC).…”

Exercise Effects on Methylation ofASCGene

“…Bisulfite-modified DNA was resuspended in a total volume of 50 μl elution buffer and 0.3 μl, and 6 sites in p15 cited by Bollati et al [1] were selected for pyrosequencing analysis. The primers and PRC conditions used are shown in Table 2.…”

“…Another representative gene whose expression is epigenetically changed by methylation is the tumor suppressor gene p15 [1]. Since the relationship between exercise and cancer has also been reported [27], P15 was added to the present analysis.…”

LINE-1 gene hypomethylation and p16 gene hypermethylation in HepG2 cells induced by low-dose and long-term triclosan exposure: The role of hydroxyl group

“…Methylated DNA level of LINE-1 gene was performed using a Pyrosequencing method according to a method proposed by Bollati et al (2007). In brief, bisulfited DNA of cells was used as the template, and was amplified using TAQ enzyme kit (KAPA Biosystems, USA) according to the instructions.…”