Huihui Ji

Elevation of peripheral BDNF promoter methylation links to the risk of Alzheimer's disease.

Brain derived neurotrophic factor (BDNF) has been known to play an important role in various mental disorders or diseases such as Alzheimers disease (AD). The aim of our study was to assess whether BDNF promoter methylation in peripheral blood was able to predict the risk of AD. A total of 44 AD patients and 62 age- and gender-matched controls were recruited in the current case-control study. Using the bisulphite pyrosequencing technology, we evaluated four CpG sites in the promoter of the BDNF. Our results showed that BDNF methylation was significantly higher in AD cases than in the controls (CpG1: p = 10.021; CpG2: p = 0.002; CpG3: p = 0.007; CpG4: p = 0.005; average methylation: p = 0.004). In addition, BDNF promoter methylation was shown to be significantly correlated with the levels of alkaline phosphatase (ALP), glucose, Lp(a), ApoE and ApoA in males (ALP: r = −0.308, p = 0.042; glucose: r = −0.383, p = 0.010; Lp(a): r = 0.333, p = 0.027; ApoE: r = −0.345, p = 0.032;), ApoA levels in females (r = 0.362, p = 0.033), and C Reactive Protein (CRP) levels in both genders (males: r = −0.373, p = 0.016; females: r = −0.399, p = 0.021). Our work suggested that peripheral BDNF promoter methylation might be a diagnostic marker of AD risk, although its underlying function remains to be elaborated in the future.

A significant association between BDNF promoter methylation and the risk of drug addiction.

As a member of the neurotrophic factor family, brain derived neurotrophic factor (BDNF) plays an important role in the survival and differentiation of neurons. The aim of our work was to evaluate the role of BDNF promoter methylation in drug addiction. A total of 60 drug abusers (30 heroin and 30 methylamphetamine addicts) and 52 healthy age- and gender-matched controls were recruited for the current case control study. Bisulfite pyrosequencing technology was used to determine the methylation levels of five CpGs (CpG1-5) on the BDNF promoter. Among the five CpGs, CpG5 methylation was significantly lower in drug abusers than controls. Moreover, significant associations were found between CpG5 methylation and addictive phenotypes including tension-anxiety, anger-hostility, fatigue-inertia, and depression-dejection. In addition, luciferase assay showed that the DNA fragment of BDNF promoter played a key role in the regulation of gene expression. Our results suggest that BDNF promoter methylation is associated with drug addiction, although further studies are needed to understand the mechanisms by which BDNF promoter methylation contributes to the pathophysiology of drug addiction.

OPRK1 promoter hypermethylation increases the risk of Alzheimer’s disease

As a member of the opioid family, κ-opioid receptors play important role in cognitive and learning functions. The purpose of this study was to evaluate the association of OPRK1 promoter methylation with Alzheimers disease (AD). OPRK1 DNA methylation levels of 48 cases and 58 well matched controls were measured using the bisulphite pyrosequencing technology. Our results showed that there was a significant correlation between three CpG sites on the OPRK1 promoter region (r>=0.715, p<0.001). Thus, the mean methylation value of the three CpG sites was used for the case-control comparison. And our results showed there was a significantly higher OPRK1 promoter methylation in AD cases than in controls (p=0.006, adjusted p=0.012). Subsequent luciferase reporter assay showed the CpGs containing fragment of OPRK1 promoter significantly increased the expression of reporter gene (Fold=2.248, p=0.0235). In summary, our results suggested that OPRK1 promoter hypermethylation might increase the risk of AD through its regulation on the gene expression of OPRK1.

Association between RASSF1A Promoter Hypermethylation and Oncogenic HPV Infection Status in Invasive Cervical Cancer: a Meta-analysis

Cervical carcinoma is the main cause of cancer-related mortality in women and is correlated with more than 15 risk cofactors, including infection of cervical cells with high-risk types of HPV (hrHPV). Indeed, both aberrant methylation of the RASSF1A promoter and hrHPV infection are often observed in cervical carcinomas. The purpose of our meta-analysis was to evaluate the role of RASSF1A promoter methylation and hrHPV infection in cervical cancer. Our meta-analysis involved 895 cervical cancer patients and 454 control patients from 15 studies. Our results suggested that RASSF1A promoter hypermethylation increased the risk of cervical cancer (OR=9.77, 95%CI=[3.06, 31.26], P=0.0001, I2=78%). By grouping cases according to cancer subtypes, we found that HPV infection was higher in cervical squamous cell carcinomas (SCCs) than in cervical adenocarcinomas/ adenosquamous cancers (ACs/ASCs) (OR=4.00, 95%CI=[1.41, 11.30], P=0.009, I2=55%). Interestingly, HPV infection tended to occur in cervical cancers with relatively low levels of RASSF1A promoter methylation (OR=0.59, 95%CI=[0.36, 0.99], P=0.05, I2=0%). Our study provides evidence of a possible interaction between HPV infection and RASSF1A promoter methylation in the development of cervical cancers.

Population Difference in the Associations of KLOTH Promoter Methylation with Mild Cognitive Impairment in Xinjiang Uygur and Han Populations

Background Mild cognitive impairment (MCI) is the intermediate stage of the cognitive changes between normal aging and dementia. KLOTH is an age-related gene that may contribute to the risk of MCI. The aim of our study was to explore the association between KLOTHO promoter methylation and MCI in Xinjiang Uygur and Han populations. Methods DNA methylation assay was performed using the bisulphite pyrosequencing technology among 96 Uygur (48 MCI and 48 controls) and 96 Han (48 MCI and 48 controls) Chinese individuals from Xinjiang province of China. Results We found significant association between KLOTHO promoter methylation and MCI in the Han Chinese (CpG1: p = 3.77E-06; CpG2: p = 1.91E-07; CpG3: p = 5.83E-07; CpG4: p = 2.23E-05; CpG5: p = 3.03E-06) but not in the Uygur Chinese. Higher KLOTHO promoter methylation levels were found in Han MCI patients than Uygur MCI patients for all the five CpGs (adjusted p values by age < 0.02). Conclusion Our results showed that KLOTHO promoter hypermethylation contributed to the MCI risk in Xinjiang Han Chinese but not in Xinjiang Uygur Chinese. The population difference of KLOTHO methylation in the risk of MCI required further investigation in the future.

Association of seven thrombotic pathway gene CpG-SNPs with coronary heart disease.

OBJECTIVES Coronary heart disease (CHD) has been considered a thromboembolic arterial diseases. The aim of this case-control study was to explore whether the CpG-SNPs of the thrombotic pathway genes contributed to the risk of CHD. METHODS AND MATERIALS A total of 784 CHD patients and 738 healthy controls were recruited in the current association study, which evaluated 7 CpG-SNPs of the thrombotic pathway genes. The CpG-SNPs included THBS4 rs17878919, CYP2C19 rs12773342, P2RY12 rs1491974, ITGA2 rs26680, FGB rs2227389, F7 rs510317 and F5 rs2269648. SNP genotyping was performed with a Sequenom Mass Spectrometry Genetic Analyzer. RESULTS Our results demonstrated that CYP2C19 rs12773342 polymorphism was significantly associated with CHD in the recessive model (χ(2)=5.41, df=1, P=0.020, OR=1.455, 95% CI=1.060-1.996). A breakdown analysis by age showed that the association of CYP2C19 rs12773342 with CHD was mainly found in individuals aged 55-65 (genotype: χ(2)=7.93, df=2, P=0.019; allele: χ(2)=4.45, df=1, P=0.035). In addition, we also observed a significant association between F7 rs510317 polymorphism and CHD in males (genotype: χ(2)=7.24, df=2, P=0.027). There was no significant association with CHD for the remaining CpG-SNPs. CONCLUSION Our results supported that the CYP2C19 rs12773342 and F7 rs510317 polymorphisms were associated with CHD in the Han Chinese population.

Elevated OPRD1 promoter methylation in Alzheimer’s disease patients

Aberrant DNA methylation has been observed in the patients with Alzheimer’s disease (AD), a common neurodegenerative disorder in the elderly. OPRD1 encodes the delta opioid receptor, a member of the opioid family of G-protein-coupled receptors. In the current study, we compare the DNA methylation levels of OPRD1 promoter CpG sites (CpG1, CpG2, and CpG3) between 51 AD cases and 63 controls using the bisulfite pyrosequencing technology. Our results show that significantly higher CpG3 methylation is found in AD cases than controls. Significant associations are found between several biochemical parameters (including HDL-C and ALP) and CpG3 methylation. Subsequent luciferase reporter gene assay shows that DNA fragment containing the three OPRD1 promoter CpGs is able to regulate gene expression. In summary, our results suggest that OPRD1 promoter hypermethylation is associated with the risk of AD.

Population difference in the association of BDNF promoter methylation with mild cognitive impairment in the Xinjiang Uygur and Han populations

BACKGROUND Mild cognitive impairment (MCI) is a clinical transitional stage between normal aging and Alzheimer disease, which leads to memory loss and a reduction in cognitive function. Brain derived neurotrophic factor (BDNF) plays an important role in neuronal development and plasticity. The aim of this study was to explore the association between BDNF promoter methylation and MCI in the Xinjiang Uygur and Han populations. METHODS A DNA methylation assay using bisulfite pyrosequencing technology was performed on 96 Uygur and 96 Han Chinese individuals from Xinjiang province, China. RESULTS We found a significantly higher BDNF methylation level in Han MCI cases than in Uygur MCI cases in males from Xinjiang province (p=0.022). In addition, the methylation level was significantly higher in Xinjiang Han healthy Chinese individuals (Northwestern China) than in Ningbo Han healthy Chinese individuals (Southeastern China) (Female and Male: p=1.17E-05; Female: p=0.020; Male: p=1.37E-04). But our results showed no significant association of BDNF methylation with MCI in either the Uygur or Han Chinese populations (p>0.05). Further gender-based subgroup analyses did not find any significant results (p>0.05). CONCLUSION Our results indicate that different levels of BDNF methylation may be present in different populations and environments. This study also provides further information regarding the relationship between BDNF methylation levels and MCI in Xinjiang Uygur and Han ethnic groups.

Diagnostic value of WIF1 methylation for colorectal cancer: a meta-analysis

As a common antagonist of Wnt/β-catenin signaling, Wnt inhibitory factor 1 (WIF1) plays an important role in the tumor progression. The aim of our meta-analysis was to summarize the diagnostic value of WIF1 methylation in colorectal cancer (CRC). Eligible studies were retrieved by a systemic search among PubMed, Embase, CNKI, and Wanfang literature databases. The diagnostic value of WIF1 methylation for CRC was assessed by the summary receiver operating characteristics (SROC) test. Our meta-analysis of 12 studies between 1420 CRC samples and 946 control samples showed that WIF1 hypermethylation was significantly associated with CRC (P < 0.001, OR = 30.10, 95% CI = 19.48-46.50). WIF1 hypermethylation, as a diagnostic biomarker for CRC, has a pooled sensitivity of 0.40 (95% CI: 0.37-0.42), a pooled specificity of 0.95 (95% CI: 0.93-0.96), a pooled positive-likelihood ratio (PLR) of 8.65 (95% CI, 4.47-16.73), and a pooled negative-likelihood ratio (NLR) of 0.41 (95% CI, 0.30-0.55), a diagnostic odds ratio (DOR) of 26.86 (95% CI: 15.73-45.89), and an area under the curve (AUC) of 0.9115. In conclusion, our study established that WIF1 hypermethylation might be a promising diagnostic biomarker for CRC.

Dopamine receptor D4 promoter hypermethylation increases the risk of drug addiction

Heroin and methylamphetamine (METH) are two addictive drugs that cause serious problems for society. Dopamine receptor D4 (DRD4), a key receptor in the dopaminergic system, may facilitate the development of drug addiction. The aim of the present study was to investigate the association between the promoter methylation level of DRD4 gene and drug addiction. Bisulfite pyrosequencing technology was used to measure the methylation levels of DRD4 promoter in 60 drug addicts and 52 matched controls. Significantly higher levels of DRD4 CpG1 and CpG4 methylation were detected in METH and heroin drug addicts compared with controls (P<0.05). Male METH addicts exhibited significantly higher DRD4 CpG1, CpG2 and CpG4 methylation levels compared with sex-matched controls (P<0.05). In heroin addicts, a positive correlation was observed between depression-dejection and DRD4 CpG5 methylation (r=0.537, P=0.039) whereas there was a negative correlation between drug usage frequency and CpG1 methylation (r=-0.632, P=0.011). In METH addicts, methylation levels were not significantly associated with depression-dejection and drug usage frequency. In addition, luciferase assays demonstrated that the target sequence of the DRD4 promoter upregulates gene expression. The results of the present study suggest that DNA methylation of DRD4 may be responsible for the pathophysiology of drug addiction.