Arsenic exposure causes human 8-hydroxyguanine DNA glycosidase 1 gene methylation and DNA oxidative damage

摘要

OBJECTIVE To investigate DNA hypermethylation of human 8-hydroxyguanine glycosy-lase(hOGG1 )gene and and the level of oxidative stress and DNA oxidative damage relations with arse-nic poisoning.METHODS In ende mic coal-pollution-borne arsenism area,Xinren county,Guizhou Province,according to the diagnostic criteria of ende mic arsenism(WS /T21 1 -2001 ),207 people with ende mic arsenism were selected and divided into four groups(The arsenic exposure group:46 cases, mild arsenism group:46 cases,moderate arsenism group:60 cases and severe arsenism group:55 cases).64 residents were selected as controls in a village about 12 km away fro m the ende mic arsenism area.With the informed consent principle,peripheral blood of all respondents was collected in order to analyze DNA methylation.Methylation-specific poly merase chain reaction were respectively performed to analyze hOGG1 Hypermethylation in arsenism respondents.Che mical methods were performed on the activity of super oxide dis mutase (SOD)and glutathione peroxidase (GSH-Px),while the contents of malondialdehyde (MDA)in the blood of patients were measured,and the contents of 8-hydroxy-2′-deox-yguanine(8-OHdG)urine of patients were measured and analysed.On the basis of methylation status are divided into hOGG1 gene methylation group (34 cases)and hOGG1 gene no methylation group (237cases).Analysis was performd on hOGG1 gene DNA methylation and the relationship between oxi-dative stress and arsenic poisoning.RESULTS The positive rates of hypermethylation of hOGG1 were associated with the degree of arsenic poisonin (co mpared with control group,χ2 =23.916,P <0.05, Co mpared with the Ende mic area normal group,χ2 =12.039,P <0.05 ).Co mparing with negative group,SOD〔(85 ±25)kU·L -1 〕,GSH-Px〔(70 ±26)kU·L -1 〕activity and 8-OHdG 〔(22.5 ±6.8)μg·L -1 〕contents were lower〔(1 18 ±41 )kU·L -1 ,(171 ±56)kU·L -1 ,(28.4 ±6.5)μg·L -1 ,P <0.05)〕in positive group.There was no significant difference between the MDA content(P> 0.05).CONCLUSION Coal arsenic exposure can cause hOGG1 gene high methylation and oxidation and anti-oxidation system imbalance,causing DNA oxidative damage,it is one of the reasons to pro mote the develop ment of arsenic poisoning occurred.

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