Zhang Ai-hua, Pan Xue-li, Xia Yu-jie, Xiao Qian, Huang Xiao-xin
Department of Toxicology, Guiyang Medical College, Guiyang 550004, China.
Zhonghua Yu Fang Yi Xue Za Zhi. 2011 May;45(5):393-8.
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.
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.
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).
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.
探讨燃煤型砷污染对人p53基因甲基化（启动子区及外显子5）及突变（外显子5）的影响，并分析甲基化、突变与砷中毒的关系。
按照地方性砷中毒诊断标准，在贵州省兴仁市地方性砷中毒病区选取112例砷中毒患者（其中轻度38例、中度43例、重度31例）。其中43例经皮肤病理诊断，分为非癌组（24例）和癌组（19例）。另选90例来自非砷污染地区的对照。在知情同意原则下，采集个体血样。采用甲基化特异性酶切PCR法检测p53基因启动子区及外显子5的甲基化，采用PCR-SSCP、PCR产物克隆及测序技术检测p53基因（外显子5）的突变。
轻度、中度、重度砷中毒组p53基因启动子区甲基化阳性率分别为13.16%（5/38）、27.91%（12/43）和45.16%（14/31），明显高于对照组（1.11%，1/90），χ²值分别为8.679、23.690、41.199，P值均<0.017。非癌组和癌组p53基因甲基化阳性率分别为25.00%（6/24）和63.16%（12/19），明显高于对照组（1.11%，1/90），χ²值分别为18.
