摘要目的 了解DNA甲基转移酶1(DNMT1)Mrna在燃煤污染型地方性砷中毒(简称地砷病)患者中的转录及表达情况,探讨其在地砷病发生、发展乃至癌变中的作用.方法 2008年,在贵州省兴仁县交乐乡燃煤污染型地砷病病区,按"地方性砷中毒诊断标准"选择68例地砷病患者(轻度24例、中度28例,重度16例),其中有40例经过皮肤病理学诊断,分为一般病变组(20例)、癌前病变组(14例)及癌变组(6例).在距病区约12 km的非砷暴露村大果朵村.选择23例居民作为对照组.在知情同意的原则下,采集上述被调查者的外周血,采用实时荧光定量PCR(FQ-PCR)检测血中DNMT1 Mrna的表达.另收集自愿接受手术治疗的61例地砷病患者皮肤组织标本(一般病变34例、痛前病变21例,癌变6例)和15例正常皮肤组织标本,采用免疫组织化学法检测地砷病患者皮肤及对照皮肤组织中DNMTl蛋白的表达.结果 轻、中、重度地砷病患者外周血DNMT1 Mrna表达分别为0.221 83±0.595 09、0.246 11±0.509 79和0.389 27±0.411 33,轻、中度患者的DNMT1 Mrna表达量明显低于对照组(0.695 95±0.463 98,P均<0.01);一般病变组、癌前病变组和癌变组患者外周血中DNMT1 Mrna表达分别为0.320 64±0.547 46、0.313 09±0.529 13和0.159 07±0.342 56,均低于对照组(0.695 95±0.463 98,P均<0.05).一般病变组、癌前病变组以及癌变组皮肤DNMT1蛋白阳性表达率分别为88.24%(30/34)、100.00%(21/21)和100.00%(6/6),与对照组[0(0/15)]比较表达增强(P均<0.01),并随患者皮肤损害程度加重而逐渐增强(r=0.740,P<0.01).结论 DNMT1参与了砷中毒的发生发展,其蛋白表达增强是砷中毒发生的早期事件,DNMT1有望成为砷中毒诊疗的新靶点.

abstractsObjective 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.