The mRNA expression of mitogen-activated protein kinase signal pathway related genes in the blood of arseniasis patients caused by burning coal / 中华预防医学杂志

<p><b>OBJECTIVE</b>To detect the mRNA expression of ERK1, ERK2, JNK1 and P38 gene in mitogen-activated protein kinase(MAPK) path way in the arseniasis patients caused by burning coal.</p><p><b>METHODS</b>70 arseniasis patients caused by burning coal at Jiaole village XingRen county in December 2006 were selected as case group, and another 30 villagers with similar living habits, matched gender and age, healthy physical condition without history of burning high arsenic coal were selected as control group from 12 km nearby the same village.Silver diethyl dithiocarbamate method (Ag-DDC) was taken to detect the arsenic contents in the environmental media, food, and arsenic level in the urine and hair of arseniasis patients.On the principle of informed consent, the peripheral blood was collected from the patients. The total RNA was extracted with Trizol method and cDNA was reversed from it. The mRNA expression of ERK1, ERK2, JNK1 and P38 gene in MAPK path way were tested by real-time fluorescent quantitative PCR (QT-PCR).</p><p><b>RESULTS</b>A total of 70 cases of arseniasis patients (31 cases of mild, 25 cases of moderate and 14 cases of severe) and 30 cases of control were chosen. The median (quartile) of arsenic contents in the indoor air, outdoor air, coal, chili and corn were 0.079 (0.053-0.117) mg/m(3) ,0.007 (0.002-0.015) mg/m(3) , 93.010 (39.460-211.740) mg/kg, 3.460(0.550-16.760) mg/kg and 1.500(0.300-4.140) mg/kg respectively. They were above the national health standards. The median (quartile) of arsenic contents in the soil, rice and drinking water were separately 12.130(4.230-24.820) mg/kg, 0.650(0.300-0.980) mg/kg and 0.043(0.012-0.089)mg/kg, which were within the national health standards. Compared with the control group ((26.97 ± 9.71)µg/g Cr), arsenic level in the patients' urine ((71.48 ± 22.74)µg/g Cr) increased significantly, the differences were significant (F = 90.38, P < 0.01). Compared with the control group ((1.58 ± 1.07)µg/g), arsenic level in the patients' hair ((4.45 ± 2.78) µg/g) increased significantly, the differences were significant (F = 48.22, P < 0.01). The relative expression amount of the median(quartile) for ERK2, JNK1 mRNA were 0.0667 (0.0378-0.1371) and 0.0013 (0.0009-0.0025), respectively. Compared with the control group 0.1744 (0.1009-0.1985) and 0.0022 (0.0017-0.0030) , only the decreases of ERK2, JNK1 mRNA expression was significant (χ(2) = 15.10, 14.25, P < 0.01), and no significance in the other index. ERK2 mRNA relative expression for mild, medium and severe groups were separately 0.0818 (0.0408-0.1509) ,0.0582 (0.0154-0.1699) and 0.0588 (0.0399-0.1034) . Compared with the control group (0.1744 (0.1099-0.1985) ), there was significant difference (Z = -2.89, -3.19, -2.67, P < 0.01). JNK1 mRNA relative expression were 0.0012 (0.0007-0.001 57), 0.0019 (0.0011-0.0035), 0.0013 (0.0010-0.0026), respectively. Compared with the control group (0.0022 (0.0017-0.0030) ), significances were found in the mild groups (Z = -3.72, P < 0.01).</p><p><b>CONCLUSIONS</b>Arsenic could induce the changes of ERK2 and JNK1mRNA expression in the MAPK path way in arseniasis patients.It suggests that the MAPK signaling pathway take part in the occurrence and development process of arseniasis caused by burning coal.</p>

The effect of NaAsO2 on the binding of methyl CpG binding protein 2, DNA methyltransferase 1 and histone deacetylase 1 to the promoter of MGMT gene in HaCaT cells / 中国地方病学杂志

Objective To investigate the effect of NaAsO2 on the binding levels of methyl CpG binding protein 2(MeCP2),DNA methyltransferase 1 (DNMT1) and histone deacetylase 1(HDAC1) to the hypermethylation promoter region of MGMT gene in HaCaT cells,in order to provide a basis to deepen the interpretation of the role of arsenic poisoning mechanism.Methods HaCaT cells were treated repeatedly and interval with different concentrations of NaAsO2(3.13,6.25,12.50,25.00 μnol/L,respectively) for 72 h.Untreated HaCaT was used as blank control group and human epidermal squamous carcinoma cell line(A431 cells) as positive control group.The binding levels to the two transcription regulatory regions(ChIP1,ChIP2) and to the coding region(ChIP3) of MGMT 8ene were detected by chromatin immuno-precipitation combined with quantitative PCR.Results The differences of binding levels of MeCP2,DNMT1 and HDAC1 to ChIP1 and ChIP2 in each group were significant (F=7.387,84.634,78.442 and 19.263,69.649,26.546,all P ＜ 0.05).The binding levels of MeCP2,DNMT1 and HDAC1 to ChIP1 and ChIP2 in each NaAsO2 exposed group[3.13 μmol/L NaAsO2 exposed group:(136.00 ±16.97)％,(145.00 ± 2.83)％,(88.50 ± 19.09)％ and (106.50 ± 37.48)％,(112.34 ± 8.73)％,(59.71 ± 8.49)％;6.25 μmol/L NaAsO2 exposed group:(130.00 ± 42.43)％,(154.50 ± 4.95)％,(101.00 ± 1.27)％ and (88.50 ±3.54)％,(134.32 ± 2.82)％,(102.75 ± 19.91)％ ; 12.50 μmol/L NaAsO2 exposed group:(141.50 ± 23.33)％,(161.50 ± 7.78)％,(125.00 ± 11.31)％ and (119.50 ± 24.75)％,(171.59 ± 3.54)％,(167.61 ± 10.61)％; 25.00μmol/L NaAsO2 exposed group:(134.50 ± 43.13)％,(472.50+ 50.20)％,(383.50 ± 30.41)％ and (180.09 ±12.73)％,(348.50 ± 27.58)％,(158.45 ± 12.02)％] were higher than that in the blank control group[(51.50 ±9.19)％,(82.00 ± 12.73)％,(25.03 ± 2.91)％ and (37.02 ± 4.24)％,(91.56 ± 26.16)％,(19.09 ± 2.90)％,all P ＜ 0.05].The differences of binding levels of MeCP2 to ChIP3 in each group were not significant(F =1.670,P ＞0.05),but the differences of binding levels of DNMT1 and HDAC1 to ChIP3 were significant (F =4.404,9.863,all P ＜ 0.05),and only the binding levels in the 25.00 μmol/L NaAsO2 exposed group [(615.85 ± 29.63)％,(306.09 ± 59.40)％] were higher than that in the blank control group[(99.70 ± 12.02)％,(92.45 ± 48.79)％,all P ＜ 0.05].Conclusions MeCP2 can bind to the methylated MGMT gene transcriptional regulatory regions which are induced by arsenic and leads to histone deacetylation by the recruitment of DNMT1 and HDAC1 and,meanwhile,DNMT1 can bind to the coding region of MGMT gene to recruit HDAC1 in a methyl DNA binding protein(MBD) independence manner and media MGMT gene silencing through the chromatin remodeling way,which might be the early molecular events of arsenic poisoning.

Relationship between the methylation and mutation of p53 gene and endemic arsenism caused by coal-burning / 中华预防医学杂志

<p><b>OBJECTIVE</b>To explore the influence of arsenic pollution caused by coal-burning on methylation (promoter and exon 5) and mutation (exon 5) of human p53 gene, and to analyze the relationship between methylation, mutation and arsenism.</p><p><b>METHODS</b>According to the diagnostic criteria of endemic arsenism, 112 patients with arsenism (including 38 mild cases, 43 moderate cases and 31 severe cases) were selected in the areas with endemic arsenism from Xingren, Guizhou province. Among the subjects, 43 cases were diagnosed by dermatopathological methods, and they were divided into non-cancerous group (24 cases) and cancerous group (19 cases). 90 controls were selected from the non-arsenic polluted areas. Under the principle of informed consent, blood samples were collected from individuals. The methylation of p53 gene in promoter region and exon 5 were detected by extinction enzyme-PCR, the mutation of p53 gene (exon 5) was detected by PCR-SSCP, PCR products cloning and sequencing technology.</p><p><b>RESULTS</b>The positive rates of methylation of p53 gene in promoter region were 13.16% (5/38), 27.91% (12/43) and 45.16% (14/31) respectively among mild, moderate and severe arsenism group, which were obviously higher than the rates in the control group (1.11% (1/90), χ² values were 8.679, 23.690, 41.199, respectively, both P values < 0.017). The positive rates of methylation of p53 gene were 25.00% (6/24) and 63.16% (12/19) in non-cancerous and cancerous group respectively, which were obviously higher than those in the control group (1.11% (1/90), χ² values were 18.762, 57.497, respectively, both P values < 0.025). The positive rates of methylation of p53 gene (exon 5) were 55.26% (21/38), 51.16% (22/43) and 48.39% (15/31) respectively among mild, moderate and severe arsenism group, which were obviously lower than the rates in the control group (88.88% (80/90), χ² values were 18.151, 23.168, 22.420, respectively, both P values < 0.017). The positive rates of methylation of p53 gene (exon 5) were 54.17% (13/24) and 42.11% (8/19) in non-cancerous and cancerous group respectively, which were obviously lower than those in the control group (88.88% (80/90), χ² values were 15.201, 22.075, respectively, both P values < 0.025). The mutation rates of p53 gene (exon 5) were respectively 5.26% (2/38), 16.28% (7/43) and 25.81% (8/31) among mild, moderate and severe arsenism group; while the results in moderate and severe arsenism group were obviously higher than in the control group (0.00%, χ² values were 15.465, 24.870, respectively, both P values < 0.017). The positive rate of mutation of p53 gene (exon 5) were respectively 16.67% (4/24) and 31.58% (6/19) in non-cancerous and cancerous group, which were obviously higher than it in the control group (0.00%, χ² values were 15.545, 30.077, both P values < 0.025). The hypermethylation of p53 gene in promoter region was related with the mutation of p53 gene (exon 5) (coefficient of association was 0.294, P value < 0.05); and the hypomethylation of p53 gene (exon 5) was related with the its mutation (coefficient of association was 0.410, P value < 0.05).</p><p><b>CONCLUSION</b>Arsenic pollution caused by coal-burning can cause the hypermethylation of p53 gene in promoter region, hypomethylation and mutation of p53 gene (exon 5), and the changes of methylation of p53 gene are related with its mutation and might be one of the important etiological factors of arsenic pathogenicity or carcinogenesis.</p>

Effects of sodium arsenite on hypermethylation, transcription and expression of O6-methylguanine-DNA methyltransferase gene in HaCaT cells / 中国地方病学杂志

Objective To investigate the DNA methylation feature and DNA methylation regulation to its transcription and expression of O6-methylguanine-DNA methyltransferase gene (MGMT) in NaAsO2-treated HaCaT cells. Methods HaCaT cells were treated 72 hours at intervals and repeatedly by 3.13, 6.25,12.50, and 25.00 μmol/L NaAsO2, MGMT gene promoter region was amplified in the transcription initiation site - 329 - + 93 region by bisulfate-sequencing polymerase chain reaction (BSP), the mRNA transcription and the protein expression of MGMT was detected by real-time quantitative PCR and Western blotting. NaAsO2-untreated HaCaT cell was set as a blank control, and human epidermal squamous carcinoma cell strain A431 was set as a positive control. Results Among the groups of HaCaT cells treated with 3.13, 6.25, 12.50 and 25.00 μmol/L NaAsO2, the positive rates of the DNA methylation of promoter region in MGMT gene were 0.63%(l/160), 6.25% (10/160), 10.63%( 17/160) and 18.75% (30/160), respectively, and methylated CpG sites were mainly located in - 249--146 region relative to transcription start site. There was no DNA methylation in the blank control. There were significant differences between the blank control and the NaAsO2-treated cells (x2 = 76.687, P< 0.05). Average levels of MGMT mRNA were 1.518 31 ± 0.180 54, 1.425 22 ± 0.180 39, 1.014 54 ± 0.096 79 and 0.887 72 ± 0.020 00, respectively among the groups of HaCaT cells treated with 3.13, 6.25, 12.50 and 25.00 μmol/L NaAsO2, compared with the blank control cells(1.198 29 ± 0.159 97), there were significant differences(F = 37.359, P < 0.05). Average levels of MGMT protein were 1.174 47 ± 0.064 75, 0.848 83 ± 0.057 01, 0.471 63 ± 0.023 34 and 0.240 34 ± 0.014 43, respectively among the groups of HaCaT cells treated with 3.13, 6.25, 12.50 and 25.00 μmol/L NaAsO2, compared with the blank control cells (1.066 19 ± 0.061 24), there were significant differences(F = 20.687, P < 0.05). Conclusions Arsenic can cause CpC island hypermethylation in the promoter region of MGMT gene, which results in inhibited MGMT mRNA transcription and protein expression. It might be one of the important mechanisms of arsenic-induced skin lesion.

Expression of DNA methyltransferase 1 mRNA in patients of endemic arsenism and its clinical significances / 中国地方病学杂志

Objective To investigate the transcription and expression of DNA methyltransferase 1 (DNMT1) mRNA in endemic arsenism patients by burning coal usage,to probe its effects on the development and carcinogenesis of arsenism. Methods In 2008,68 arsenism patients(including 24 mild cases,28 moderate cases and 16 severe cases) were selected in the areas with endemic arsenism according to Standarding of Diagnosis for Endemic Arsenism from Xingren county,Guizhou province. Among the subjects,40 cases were diagnosed by pathological methods,and they were divided into general pathological changes(20),precancerous(14) and cancerous group(6). Tweleve kilometer away from the endemic arsenism area,23 controls were selected in Daguoduo village (non-arsenism exposure). Under the principle of informed consent,blood samples were collected from individuals. The mRNA expression of DNMTI was detected by real-time quantitative reverse transcription polymerase chain reaction(FQ-PCR). At the same time,skin tissue samples were collected from the voluntary surgical treatment patients with endemic arsenism (total 61 cases,including 34 general pathological changes cases,21 precancerous cases and 6 cancerous cases) and from the control(15 cases). DNMT1 protein was detected by immunohistochemical method.Results Average level of DNMT1 mRNA were 0.221 83±0.595 09,0.246 11±0.509 79 and 0.389 27±0.411 33 respectively among mild,moderate and severe arsenism group. DNMT1 mRNA level of mild and moderate group were obviously lower than the control group(0.695 95±0.463 98,all P < 0.01). The mRNA average level of DNMT1 were 0.320 64±0.547 46,0.313 09±0.529 13 and 0.159 07±0.342 56 individually among general pathological changes,precancerous and cancerous group,which were obviously lower than the control group(0.695 95±0.463 98,all P < 0.05). The expression rates of DNMT1 protein in skin were 88.24%(30/34),100%(21/21) and 100% (6/6) among general pathological changes,precancerous and cancerous group were higher than the control group [0(0/15),all P < 0.01],and the extent of expression gradually increased with the aggravation of skin damage(r,= 0.740,P < 0.01). Conclusions DNMT1 participated in the development of the arsenism. High expression of its protein was an early event during the process of the arsenism. DNMT1 may be the new target markers for early diagnosis and treatment of arsenism.