Selected gene expression changes in the liver of mice exposed to different doses of TCE (0, 100, 500 and 1000 mg/kg b.w.) (n = 3).

<p>A) qPCR analysis of selected mRNA expression changes in mouse liver. B) Western analysis of Dnmt1 protein expression levels. Fold expression at each dose was calculated against the nonexposed samples (TCE dose level at 0 mg/kg). *, p<0.05; **, p<0.01. ***, p<0.001.</p

DNA methylation status of the promoter regions of Cdkn1a and Ihh in the liver of mice exposed to different doses of TCE (0, 100, 500 and 1000 mg/kg b.w.) (n = 3).

<p>A, D) Nucleotide sequences of Cdkn1a and Ihh promoter region fragments (upper strands) and the corresponding bisulphite-converted sequences (lower strands). CpG dinucleotides are numbered and marked in bold. The restriction enzyme cut sites are marked in italic. Primer sequences are underlined. B, E) Bisulfite sequencing of the Cdkn1a and Ihh promoter regions. Open and closed circles indicate unmethylated and methylated CpG sites respectively. Percent methylation is shown in parentheses. C) COBRA result of the promoter region of Cdkn1a at CpG4-5(CGCG) by <i>BstUI</i> 184 bp (84/100); L: Tiangen DNA ladder II; P, positive control by treating mouse genomic DNA with M.SssI. C, liver samples from mice exposed to corn oil; T, liver samples from mice exposed to TCE at 1000 mg/kg b.w. M, methylation; UM, unmethylation.</p

Global DNA methylation status of the liver of mice exposed to TCE.

<p>A–C) Bisulfite sequencing of the LINE-1, LAP-LTR and SINE B1 repetitive elements in the liver of mice treated with TCE at 0 or 1000 mg/kg b.w. Open and closed circles indicate unmethylated and methylated CpG sites respectively. Some sites are absent from the sequences in some clones due to mutations in the particular copies of the repetitive sequences. Percent methylation is shown in parentheses. D) The content of 5-mC detected by LC-MS/MS. (n = 5).</p

Trichloroethylene-Induced Gene Expression and DNA Methylation Changes in B6C3F1 Mouse Liver

<div><p>Trichloroethylene (TCE), widely used as an organic solvent in the industry, is a common contaminant in air, soil, and water. Chronic TCE exposure induced hepatocellular carcinoma in mice, and occupational exposure in humans was suggested to be associated with liver cancer. To understand the role of non-genotoxic mechanism(s) for TCE action, we examined the gene expression and DNA methylation changes in the liver of B6C3F1 mice orally administered with TCE (0, 100, 500 and 1000 mg/kg b.w. per day) for 5 days. After 5 days TCE treatment at a dose level of 1000 mg/kg b.w., a total of 431 differentially expressed genes were identified in mouse liver by microarray, of which 291 were up-regulated and 140 down-regulated. The expression changed genes were involved in key signal pathways including PPAR, proliferation, apoptosis and homologous recombination. Notably, the expression level of a number of vital genes involved in the regulation of DNA methylation, such as Utrf1, Tet2, DNMT1, DNMT3a and DNMT3b, were dysregulated. Although global DNA methylation change was not detected in the liver of mice exposed to TCE, the promoter regions of Cdkn1a and Ihh were found to be hypo- and hypermethylated respectively, which correlated negatively with their mRNA expression changes. Furthermore, the gene expression and DNA methylation changes induced by TCE were dose dependent. The overall data indicate that TCE exposure leads to aberrant DNA methylation changes, which might alter the expression of genes involved in the TCE-induced liver tumorgenesis.</p></div

Comparison of mRNA expression changes detected by microarray and qPCR in mouse liver exposed to TCE at a dose level of 1000 mg/kg b.w. (n = 3).

<p>Comparison of mRNA expression changes detected by microarray and qPCR in mouse liver exposed to TCE at a dose level of 1000 mg/kg b.w. (n = 3).</p

DNA methylation status of the promoter regions of Jun and Myc in the liver from mice exposed to TCE at 0 or 1000 mg/kg b.w. (n = 3).

<p>A, D) Nucleotide sequences of Jun and Myc promoter region fragments (upper strands) and the corresponding bisulphite-converted sequences (lower strands). CpG dinucleotides are numbered and marked in bold. The restriction enzyme cut sites are marked in italic. Primer sequences are underlined. (B, E) Bisulfite sequencing of the Jun and Myc promoter regions. Open and closed circles indicate unmethylated and methylated CpG sites respectively. C) COBRA result of the promoter region of Jun at CpG3,4 (CGCG) by <i>BstUI</i> 171 bp (49/122). F) COBRA result of the promoter region of Myc at CpG4 (TCGA) by <i>TaqI</i> 132 bp (88/43). L: Tiangen DNA ladder; P, positive control by treating mouse genomic DNA with M.SssI. C, control liver samples; T, liver samples treated with TCE at 1000 mg/kg b.w. M methylation; UM, unmethylation.</p

Correlation between % apoptosis and intracellular free Ca²⁺ levels in HL-60 cells.

<p>Correlation between % apoptosis and intracellular free Ca²⁺ levels in HL-60 cells.</p

Primary DNA damage, comet tail length and tail moment, in peripheral blood leukocytes of mice in different experimental groups.

<p>Number of animals in each group - 5. Data are Mean+/−Standard Deviation.</p><p>*No RF exposure. 3 Gy γ-radiation (GR) exposure is acute on days 1, 3, 5, 7 and 14 days.</p><p>**Expected values are the sum of two individual treatments (GR alone+RF alone) minus controls.</p

The viability, apoptosis, mitochondrial membrane potential (MMP), intracellular free Ca²⁺ and Ca²⁺-Mg²⁺-ATPase activity in HL-60 cells.

<p>Number of experiments: 2. Data are Mean +/− Standard Deviation.</p>*<p>FI: Fluorescence Intensity measured in flow cytometer.</p