5-Aza-dC及TSA对人胃癌细胞株SGC-7901 Runx3基因甲基化及表达水平的影响

目的:探讨5-Aza-dC及TSA对人胃癌细胞系SGC-7901中抑癌基因Runx3启动子区甲基化、mRNA及蛋白表达水平的影响.方法:单独或联合应用5-Aza-dC及TSA处理体外培养的SGC-7901细胞,提取各组细胞的DNA、RNA及蛋白质,应用甲基化特异性定量PCR法(QMSP)检测Runx3基因启动子区甲基化状态,逆转录PCR法(RT-PCR)检测Runx3mRNA的表达,免疫印迹法(Western blotting)法检测Runx3蛋白表达水平.结果:5-Aza-dC和TSA均能降低Runx3基因启动子区的甲基化水平(5-Aza-dC组及TSA组分别为对照组的0.70倍、0.63倍),提高mRNA表达水平(0.29±0.01、0.28±0.03vs0.14±0.03,P<0.05)及蛋白表达水平(0.35±0.02、0.37±0.02vs0.09±0.01,P<0.05);与单独使用5-Aza-dC和TSA相比,两药联合组Runx3基因启动子区甲基化水平(对照组的0.37倍)及mRNA表达水平(0.45±0.02)和蛋白表达水平(0.50±0.01)均较单药组效果更明显(P<0.05).结论:5-...     

Association of ADH and ALDH genes with alcohol dependence in the Irish Affected Sib Pair Study of alcohol dependence (IASPSAD) sample

Background:  The genes coding for ethanol metabolism enzymes [alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH)] have been widely studied for their influence on the risk to develop alcohol dependence (AD). However, the relation between polymorphisms of these metabolism genes and AD in Caucasian subjects has not been clearly established. The present study examined evidence for the association of alcohol metabolism genes with AD in the Irish Affected Sib Pair Study of alcohol dependence.
Methods:  We conducted a case–control association study with 575 independent subjects who met Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, AD diagnosis and 530 controls. A total of 77 single nucleotide polymorphisms (SNPs) in the seven ADH ( ADH1-7 ) and two ALDH genes ( ALDH1A1 and ALDH2 ) were genotyped using the Illumina GoldenGate protocols. Several statistical procedures were implemented to control for false discoveries.
Results:  All markers with minor allele frequency greater than 0.01 were in Hardy–Weinberg equilibrium. Numerous SNPs in ADH genes showed association with AD, including one marker in the coding region of ADH1C (rs1693482 in exon6, Ile271Gln). Haplotypic association was observed in the ADH5 and ADH1C genes, and in a long haplotype block formed by the ADH1A and ADH1B loci. We detected two significant interactions between pairs of markers in intron 6 of ADH6 and intron 12 of ALDH2 ( p  =   5 × 10⁻⁵), and 5' of both ADH4 and ADH1A ( p  =   2 × 10⁻⁴).
Conclusion:  We found evidence for the association of several ADH genes with AD in a sample of Western European origin. The significant interaction effects between markers in ADH and ALDH genes suggest possible epistatic roles between alcohol metabolic enzymes in the risk for AD.     

Effects of alcohol on histone deacetylase 2 (HDAC2) and the neuroprotective role of trichostatin A (TSA)

Background: Previous studies have implicated histone deacetylases (HDACs) and HDAC inhibitors (HDIs) such as trichostatin A (TSA) in the regulation of gene expression during drug addiction. Furthermore, an increase in HDAC activity has been linked to neurodegeneration. Alcohol has also been shown to promote abundant generation of reactive oxygen species (ROS) resulting in oxidative stress. TSA inhibits HDACs and has been shown to be neuroprotective in other neurodegenerative disease models. Although HDACs and HDIs have been associated with drug addiction, there is no evidence of the neurodegenerative role of HDAC2 and neuroprotective role of TSA in alcohol addiction. Therefore, we hypothesize that alcohol modulates HDAC2 through mechanisms involving oxidative stress. Methods: To test our hypothesis, the human neuronal cell line, SK‐N‐MC, was treated with different concentrations of ethanol (EtOH); HDAC2 gene and protein expression were assessed at different time points. Pharmacological inhibition of HDAC2 with TSA was evaluated at the gene level using qRT‐PCR and at the protein level using Western blot and flow cytometry. ROS production was measured with a fluorescence microplate reader and fluorescence microscopy. Results: Our results showed a dose‐dependent increase in HDAC2 expression with EtOH treatment. Additionally, alcohol significantly induced ROS, and pharmacological inhibition of HDAC2 with TSA was shown to be neuroprotective by significantly inhibiting HDAC2 and ROS. Conclusions: These results suggest that EtOH can upregulate HDAC2 through mechanisms involving oxidative stress and HDACs may play an important role in alcohol use disorders (AUDs). Moreover, the use of HDIs may be of therapeutic significance for the treatment of neurodegenerative disorders including AUDs.     

5-氮杂-2'-脱氧胞苷对人胃癌SGC-7901细胞株生长及EDNRB基因启动子异常甲基化的影响

目的:探讨去甲基化药物5-氮杂-2'-脱氧胞苷(5-Aza-CdR)对人胃癌细胞系SGC-7901细胞株的生长及EDNRB基因启动子异常甲基化的影响.方法:使用1、2、5、10μmol/L5-Aza-CdR干预胃癌SGC-7901细胞,甲基化特异性PCR(MSP)和逆转录聚合酶链反应(RT-PCR)分别检测药物干预前后EDNRB基因的甲基化状态和EDNRB mRNA的表达,MTT法检测细胞增殖活性,流式细胞术分析细胞周期及细胞凋亡的改变.结果:未经5-Aza-CdR处理的SGC-7901细胞中EDNRB基因启动子区域CpG岛高甲基化,且EDNRB mRNA不表达,经1、2、5、10μmol/L5-Aza-CdR处理4d后,EDNRB基因启动子区域高甲基化状态得到逆转,细胞中EDNRB mRNA表达恢复.4种浓度5-Aza-CdR处理的SGC-7901细胞后,细胞增殖受到抑制,且呈时间和剂量依赖性;并抑制SGC-7901细胞生长周期,其细胞周期阻滞于S期,5、10μmol/L5-Aza-CdR实验组细胞凋亡率显著高于对照组,且差异有统计学意义(7.13%±0.87%,13.34%±1.12% vs 3.69%±...     

Effects of Sirt1 on DNA methylation and expression of genes affected by dietary restriction

Changes in DNA methylation across the life course may contribute to the ageing process. We hypothesised that some effects of dietary restriction to extend lifespan and/or mitigate against features of ageing result from changes in DNA methylation, so we determined if genes that respond to dietary restriction also show age-related changes in DNA methylation. In support of our hypothesis, the intersection of lists of genes compiled from published sources that (1) were differentially expressed in response to dietary restriction and (2) showed altered methylation with increased age was greater than expected. We also hypothesised that some effects of Sirt1, which may play a pivotal role in beneficial effects of dietary restriction, are mediated through DNA methylation. We thus measured effects of Sirt1 overexpression and knockdown in a human cell line on DNA methylation and expression of a panel of eight genes that respond to dietary restriction and show altered methylation with age. Six genes were affected at the level of DNA methylation, and for six expressions were affected. In further support of our hypothesis, we observed by DNA microarray analysis that genes showing differential expression in response to Sirt1 knockdown were over-represented in the complied list of genes that respond to dietary restriction. The findings reveal that Sirt1 has effects on DNA methylation across the genome and affects, in particular, the expression of genes that respond to dietary restriction. Sirt1-mediated effects on DNA methylation and, consequently, gene expression may thus be one of the mechanisms underlying the response to dietary restriction.

Electronic supplementary material

The online version of this article (doi:10.1007/s11357-012-9485-8) contains supplementary material, which is available to authorized users.     

ALDH2 and ADH1B interactions in retrospective reports of low-dose reactions and initial sensitivity to alcohol in Asian American college students

Background: A mechanistic model has been proposed for how alcohol‐metabolizing gene variants protect individuals from the development of alcohol use disorders, with heightened sensitivity to alcohol being an early step (endophenotype) in this model. This study was designed to determine whether possession of 2 alcohol‐metabolizing genes variations, the aldehyde dehydrogenase ALDH2*2 allele and the alcohol dehydrogenase ADH1B*2 allele, was associated with self‐reported sensitivity to alcohol at low doses and at initial use. Methods: Asian–American college students (N = 784) of Chinese and Korean descent were genotyped at the ALDH2 and ADH1B loci and assessed for lifetime alcohol symptoms following 1 or 2 drinks and level of response to alcohol during the first 5 lifetime drinking episodes. Results: Participants who had an ALDH2*2 allele were more likely to report experiencing all 6 low‐dose symptoms and having heightened initial response to alcohol. An interaction was found between ALDH2*2 and ADH1B*2, with ADH1B*2 being associated with heightened self‐reported sensitivity to alcohol only in individuals who also possessed 1 ALDH2*2 allele. Conclusions: These findings suggest the effects of ADH1B*2 may be felt more strongly in Asians who already have some heightened sensitivity to alcohol from possessing 1 ALDH2*2 allele, but who are not too sensitized to alcohol from possessing 2 ALDH2*2 alleles. These results offer additional insight into the discrepant findings that have been reported in the literature for the role of ADH1B*2 in response to alcohol and the development of alcohol‐related problems.     

5-氮杂-2′-脱氧胞苷对肺癌SPC-A-1细胞p16、MGMT基因甲基化及其表达的影响

目的观察5-氮杂-2′-脱氧胞苷（5-Aza-CdR）对体外培养的肺癌SPC-A-1细胞p16、MGMT基因启动子区DNA甲基化状态及其表达的影响,探讨肺癌细胞p16、MGMT基因失活的机制及去甲基化制剂对p16、MGMT基因表达的调控。方法 5-Aza-CdR处理体外培养的肺癌SPC-A-1细胞,甲基化特异性PCR（MSP）法检测用药前后细胞p16、MGMT基因的甲基化状态,RT-PCR法检测用药前后细胞p16、MGMT mRNA。结果加入5-Aza-CdR前,SPC-A-1细胞p16、MGMTmRNA表达缺失,其启动子区域表现为DNA甲基化。加入5-Aza-CdR后,SPC-A-1细胞中p16、MGMT基因呈现DNA去甲基化,而且表达缺失的p16、MGMT mRNA重新表达。结论启动子区高甲基化是肺癌细胞p16、MGMT基因失活的主要原因之一,去甲基化制剂5-Aza-CdR能逆转p16、MGMT基因甲基化状态,从而调控p16、MGMT基因表达。     

Alcohol metabolism in human cells causes DNA damage and activates the Fanconi anemia-breast cancer susceptibility (FA-BRCA) DNA damage response network

Background: We recently reported that exposure of human cells in vitro to acetaldehyde resulted in the activation of the Fanconi anemia–breast cancer susceptibility (FA‐BRCA) DNA damage response network. Methods: To determine whether intracellular generation of acetaldehyde from ethanol metabolism can cause DNA damage and activate the FA‐BRCA network, we engineered HeLa cells to metabolize alcohol by expression of human alcohol dehydrogenase (ADH) 1B. Results: Incubation of HeLa‐ADH1B cells with ethanol (20 mM) resulted in acetaldehyde accumulation in the media, which was prevented by co‐incubation with 4‐methyl pyrazole (4‐MP), a specific inhibitor of ADH. Ethanol treatment of HeLa‐ADH1B cells produced a 4‐fold increase in the acetaldehyde–DNA adduct and N²‐ethylidene‐dGuo and also resulted in the activation of the FA‐BRCA DNA damage response network, as indicated by a monoubiquitination of FANCD2 and phosphorylation of BRCA1. Ser 1524 was identified as 1 site of BRCA1 phosphorylation. The increased levels of DNA adducts, FANCD2 monoubiquitination, and BRCA1 phosphorylation were all blocked by 4‐MP, indicating that acetaldehyde, rather than ethanol itself, was responsible for all 3 responses. Importantly, the ethanol concentration we used is within the range that can be attained in the human body during social drinking. Conclusions: Our results indicate that intracellular metabolism of ethanol to acetaldehyde results in DNA damage, which activates the FA‐BRCA DNA damage response network.     

Enzymic catalysis of the accumulation of acetaldehyde from ethanol in human prenatal cephalic tissues: evaluation of the relative contributions of CYP2E1, alcohol dehydrogenase, and catalase/peroxidases

BACKGROUND: The human prenatal brain is very sensitive to the toxic effects of ethanol, but very little information is available concerning the conversion of ethanol to the highly cytotoxic metabolite, acetaldehyde, in that organ. Thus, experiments were designed to investigate rates of accumulation of acetaldehyde from ethanol in the prenatal human brain. METHODS: Prenatal human cephalic tissue homogenates were used as enzyme sources and were compared with analogous preparations of adult rat livers. Generated acetaldehyde was derivatized with cyclohexane-1,3-dione to yield fluorescent decahydroacrizine-1,8-dione, which was readily separated, detected, and quantitated with HPLC. RESULTS: Detected rates of accumulation were unexpectedly high, even in the absence of added NADPH, NAD+, or H2O2, which are cofactors/cosubstrates for cytochrome P-450-, alcohol dehydrogenase- and catalase/peroxidase-catalyzed reactions, respectively. Without added cofactors/cosubstrates or other components and under linear reaction conditions, rates in human prenatal cephalic preparations were approximately 20% of those observed with analogous preparations of adult rat livers. Cofactor/cosubstrate-independent reactions were localized in the cytosolic (soluble) fraction and were strongly dependent on molecular oxygen (O2). They were not inhibited substantially by carbon monoxide (CO:O2 = 80:20 vs N2:O2 = 80:20) or by pyrazole in concentrations up to 10 mM and were only weakly inhibited by azide. Preincubations with excess catalase did not result in decreased activity. Reactions exhibited substrate saturation and heat inactivation indicating enzymic catalysis. CONCLUSIONS: Experiments indicated a relatively rapid accumulation of acetaldehyde from ethanol in human prenatal brain tissues and suggested that the observed cofactor/cosubstrate-independent reactions were largely independent of P-450 cytochromes, alcohol dehydrogenases, or catalase/peroxidases. Results were consistent with catalysis by an as yet unidentified cytosolic oxidase(s).     

Global DNA methylation and risk of subclinical atherosclerosis in young adults: the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study

Objective

The association between hepatic global DNA methylation measured using pyrosequencing technology and the risk of subclinical atherosclerosis was examined in the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study. PDAY is a bi-racial investigation of the natural history of atherosclerosis and its risk factors involving 3013 individuals aged 15–34 years who underwent autopsy after dying of unrelated causes in 1987–1994.

Methods

Raised atherosclerotic lesions were defined as the sum of the percentages of intimal surface area detected in the right coronary artery and left half of the abdominal and thoracic aorta harboring fibrous plaques, complicated lesions, and calcified lesions during a postmortem pathological examination. To conduct the case–control study, 300 cases selected with the highest raised lesion scores were paired with 300 controls without raised lesions after matching for age, race, and gender.

Results

Global DNA methylation was not associated with disease risk in the study population considered as a whole using conditional logistic regression models to analyze matched pairs. Since the estimation of the risk of atherosclerosis associated with inter-individual variation in DNA methylation was similar if unconditional logistic regression was used, subgroup analyses were carried out after adjusting for matching variables. A modest association with methylation levels below the median value was found in white but not in African-American study participants (odds ratio = 1.59, 95% confidence interval = 1.02–2.49, p = 0.04).

Conclusions

Hepatic global DNA methylation does not appear to be a definitive determinant of atherosclerosis burden in a postmortem sample of young adults.     

Genetic variation in alcohol dehydrogenase 1C and the beneficial effect of alcohol intake on coronary heart disease risk in the Second Northwick Park Heart Study

Alcohol dehydrogenase 1C (ADH1C or ADH3) genotype reportedly modifies the association between alcohol consumption and coronary heart disease (CHD) risk, as well as influencing plasma high-density lipoprotein (HDL) levels [Hines LM, Stampfer MJ, Ma J, et al. Genetic variation in alcohol dehydrogenase and the beneficial effect of moderate alcohol consumption on myocardial infarction. N Engl J Med 2001;344:549–55]. This relationship has been examined in a sample of middle-aged (50–61 years) men (total of 2773 with 220 CHD events), participating in the prospective Second Northwick Park Heart Study (NPHS II). Alcohol consumption was assessed by questionnaire as the number of units consumed in the previous week. Drinkers experienced lower CHD risk than abstainers [hazard ratio (HR) 0.73 (95% confidence intervals (CI) 0.53, 0.99; p = 0.04)] and had significantly higher HDL and apolipoprotein (apo)AI concentrations (both p < 0.0001) and a lower fibrinogen (p = 0.02). Overall, there was no effect of ADHC1 γ1 > γ2 genotype on plasma levels of HDL, apoAI or fibrinogen or on CHD risk. To consider whether the effect of alcohol consumption on risk was modulated by genotype, the men were divided into abstainers, modest drinkers (1–3 units/week) and those who consumed more than 3 units/week. Significant alcohol:genotype interaction on CHD risk was observed (p = 0.02), with γ2 homozygotes, who were modest drinkers, displaying 78% CHD risk reduction compared to γ1 homozygotes (HR = 0.22, 95% CI 0.05–0.94). There was, however, no association between genotype and apoAI, HDL or fibrinogen and this was not altered when alcohol intake was considered. These findings confirm that the cardiovascular benefit of modest alcohol consumption. ADH1C genotype modifies the relationship between alcohol consumption and CHD risk but at lower levels than previously reported.     

A polymorphism of the mu-opioid receptor gene (OPRM1) and sensitivity to the effects of alcohol in humans

BACKGROUND: Recent research has implicated the endogenous opioid system in the development of alcohol use disorders. The A118G polymorphism of the OPRM1 gene has been shown to confer functional differences to mu-opioid receptors, such that the G variant binds beta-endorphin three times more strongly than the A variant. The goal of this study was to test whether the A118G polymorphism is associated with sensitivity to the effects of alcohol. METHODS: Participants who were either homozygous for the A allele (n = 23) or heterozygous (n = 15) received intravenous doses of alcohol designed to reach three target levels of breath alcohol concentration: 0.02, 0.04, and 0.06. The testing procedure consisted of measures of subjective intoxication, stimulation, sedation, and mood states at baseline and at each of the three target breath alcohol concentrations. RESULTS: The results suggested that individuals with the G allele reported higher subjective feelings of intoxication, stimulation, sedation, and happiness across trials as compared with participants with the A allele. Furthermore, participants with the G allele were almost three times more likely to report a positive family history of alcohol use disorders than participants with the A allele. CONCLUSIONS: These findings may help to explain previous research suggesting that naltrexone is more effective among individuals with the G allele. A medication that reduces feelings of euphoria after alcohol consumption may be more successful among individuals with a genetic predisposition to greater feelings of euphoria after consuming alcohol.     

亚砷酸钠对HaCaT细胞MGMT基因启动子区甲基化CpG结合蛋白-2、DNA甲基转移酶1、组蛋白去乙酰化酶1结合的影响

目的 观察亚砷酸钠(NaAsO2)对人肤角质形成细胞株(HaCaT细胞)MGMT基因启动子区甲基化CpG结合蛋白-2(MeCP2)、DNA甲基转移酶1(DNMT1)及组蛋白去乙酰化酶1(HDAC1)结合情况的影响,为深化阐释砷毒作用机制提供依据.方法 分别以0.00(空白对照)、3.13、6.25、12.50、25.00 μmol/L NaAsO2重复间隔处理HaCaT细胞72 h(NaAsO2处理24h,隔天再次相同处理,重复3次),以人表皮鳞癌细胞株(A431)作为阳性对照,定量染色质免疫共沉淀技术(Q-ChIP)检测MGMT基因转录调控区ChIP1、ChIP2区域及MGMT基因编码区ChIP3区域MeCP2、DNMT1、HDAC1结合情况.结果 各组HaCaT细胞MGMT基因转录调控区ChIP1、ChIP2区域MeCP2、DNMT1、HDAC1蛋白结合水平比较,差异有统计学意义(F值分别为7.387、84.634、78.442和19.263、69.649、26.546,P均＜0.05);其中各NaAsO2处理组ChIP1、ChIP2区域MeCP2、DNMT1、HDAC1蛋白结合水平[3.13 μmol/L NaAsO2处理组:(136.00±16.97)％、(145.00±2.83)％、(88.50±19.09)％和(106.50±37.48)％、(112.34±8.73)％、(59.71±8.49)％;6.25 μmol/L NaAsO2处理组:(130.00±42.43)％、(154.50±4.95)％、(101.00±1.27)％和(88.50±3.54)％、(134.32±2.82)％、(102.75±19.91)％;12.50 μmol/LNaAsO2处理组:(141.50±23.33)％、(161.50±7.78)％、(125.00±11.31)％和(119.50±24.75)％、(171.59±3.54)％、(167.61±10.61)％;25.00 μmol/NaAsO处理组:(134.50±43.13)％、(472.50±50.20)％、(383.50±30.41)％和(180.09±12.73)％、(348.50±27.58)％、(158.45±12.02)％]均高于空白对照组[(51.50±9.19)％、(82.00±12.73)％、(25.03±2.91)％和(37.02±4.24)％、(91.56±26.16)％、(19.09±2.90)％,P均＜0.05].各组HaCaT细胞MGMT基因编码区ChIP3区域MeCP2蛋白结合水平比较,差异无统计学意义(F=1.670,P＞0.05),而DNMT1、HDAC1蛋白结合水平比较,差异有统计学意义(F值分别为4.404、9.863,P均＜0.05),其中25.00 μmol/L NaAsO2处理组DNMT1、HDAC1蛋白结合水平[(615.85±29.63)％、(306.09±59.40)％]与空白对照组[(99.70±12.02)％、(92.45±48.79)％]比较,差异有统计学意义(P均＜0.05).结论 MeCP2可结合于砷所致高甲基化MGMT基因转录调控区,通过招募DNMT1及HDAC1使组蛋白去乙酰化,同时DNMT1可结合于MGMT基因编码区,以非甲基化DNA结合蛋白(MBD)依赖的方式招募HDAC1,通过染色质重塑方式导致MGMT基因沉默,可能是砷毒性表现的早期分子事件.