• Asian Pacific Journal of Cancer Prevention
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• v.14 no.6
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• pp.3719-3724
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• 2013

Background: RASSF1A has been reported to be a candidate tumor suppressor in non-small cell lung cancer (NSCLC). However, the association between RASSF1A promoter methylation and NSCLC remains unclear, particularly in regarding links to clinicopathologic features. Methods: Eligible studies were identified through searching PubMed, EMBASE, Cochrane Library and China National Knowledge Infrastructure (CNKI) databases. Studies were pooled and odds ratios (ORs) with corresponding confidence intervals (CIs) were calculated. Funnel plots were also performed to evaluate publication bias. Results: Nineteen studies involving 2,063 cases of NSCLC and 1,184 controls were included in this meta-analysis. A significant association was observed between RASSF1A methylation and NSCLC in the complete data set (OR = 19.42, 95% CI: 14.04-26.85, P < 0.001). Pooling the control tissue subgroups (heterogeneous/autologous) gave pooled ORs of 32.4 (95% CI, 12.4-84.5) and 17.7 (95% CI, 12.5-25.0) respectively. Racial subgroup (Caucasian/Asian) analysis gave pooled ORs of 26.6 (95% CI, 10.9-64.9) and 20.9 (95% CI, 14.4-30.4) respectively. The OR for RASSF1A methylation in poorly-differentiated vs. moderately/well-differentiated NSCLC tissues was 1.88 (95% CI, 1.32-2.68, P<0.001), whereas there were no significant differences in RASSF1A methylation in relation to gender, pathology, TNM stage and smoking behavior among NSCLC cases. Conclusion: This meta-analysis suggests a significant association between RASSF1A methylation and NSCLC, confirming the role of RASSF1A as a tumor suppressor gene. Large-scale and well-designed case-control studies are needed to validate the associations identified in the present meta-analysis.

• The Journal of the Korea Contents Association
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• v.13 no.8
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• pp.466-473
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• 2013

Gene expression is regulated by a wide range of mechanisms at the DNA sequence level. In addition, gene expression is also regulated by epigenetic mechanisms through DNA methylation, histone modification, and ncRNA. To understand the regulation of gene expression at the epigenetic level, we constructed aging related gene database and analyzed epigenetic properties that are focused on DNA methylation. The DNA methylation of promoter or upstream region of the genes induces to repress the gene expression. We compared and analyzed distribution between whole human genes and aging related genes in the epigenetic properties such as CGI distribution, methylation motif pattern, and TFBS (transcription factor binding site) distribution. In contrast to methylation motif pattern, CGI and TFBS distributions are positively correlated with epigenetic regulation of aging related gene expression. In this study, the epigenetic data about DNA methylation of the aging genes will provide us to understand phenomena of the aging and epigenetic mechanism for regulation of aging related genes.

• Proceedings of the KSAR Conference
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• 2001.03a
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• pp.49-49
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• 2001

To elucidate overall changes in DNA methylation that occurs by inappropriate epigenetic control during ageing, we compared fetal bovine fibroblasts and their aged neomycin-resistant versions using bisulfite-PCR technology. Reduction in DNA methylation was observed in euchromatic repeats (18S-rRNA/art2) and promoter regions of sing1e-copy genes (the cytokeratin/-lactoglobulin/interleukin-13 genes). Contrastingly, a stable maintenance of DNA methylation was revealed in various heterochromatic sequences (satellite I/IIalphoid and Bov-B). The differential inheritance modes of DNA methylation was confirmed through the analysis of individual neomycin-resistant clones. These global, multi-loci analyses provide evidence on the tendency of differential epigenetic modification between genomic DNA regions during ageing.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.15
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• pp.6397-6403
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• 2014

Background: Aberrant promoter hypermethylation has been recognized in human breast carcinogenesis as a frequent molecular alteration associated with the loss of expression of a number of key regulatory genes and may serve as a biomarker. The E-cadherin gene (CDH1), mapping at chromosome 16q22, is an intercellular adhesion molecule in epithelial cells, which plays an important role in establishing and maintaining intercellular connections. The aim of our study was to assess the methylation pattern of CDH1 and to correlate it with the expression of E-cadherin, clinicopathological parameters and hormone receptor status in breast cancer patients of Kashmir. Materials and Methods: Methylation specific PCR (MSP) was used to determine the methylation status of CDH1 in 128 invasive ductal carcinomas (IDCs) paired with the corresponding normal tissue samples. Immunohistochemistry was used to study the expression of E-cadherin, ER and PR. Results: CDH1 hypermethylation was detected in 57.8% of cases and 14.8% of normal adjacent controls. Reduced levels of E-cadherin protein were observed in 71.9% of our samples. Loss of E-cadherin expression was significantly associated with the CDH1 promoter region methylation (p<0.05, OR=3.48, CI: 1.55-7.79). Hypermethylation of CDH1 was significantly associated with age at diagnosis (p=0.030), tumor size (p=0.008), tumor grade (p=0.024) and rate of node positivity or metastasis (p=0.043). Conclusions: Our preliminary findings suggest that abnormal CDH1 methylation occurs in high frequencies in infiltrating breast cancers associated with a decrease in E-cadherin expression. We found significant differences in tumor-related CDH1 gene methylation patterns relevant to tumor grade, tumor size, nodal involvement and age at diagnosis of breast tumors, which could be extended in future to provide diagnostic and prognostic information.

• Reproductive and Developmental Biology
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• v.36 no.1
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• pp.7-12
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• 2012

DNA methyltransferase 1 (Dnmt1) gene contains three different isoform transcripts, Dnmt1s, Dnmt1o, and Dnmt1p, are produced by alternative usage of multiple first exons. Dnmt1o is specific to oocytes and preimplantation embryos, whereas Dnmt1s is expressed in somatic cells. Here we determined that porcine Dnmt1o gene had differentially methylated regions (DMRs) in 5'-flanking region, while those were not found in the Dnmt1s promoter region. The methylation patterns of the porcine Dnmt1o/Dnmt1s DMRs were investigated using bisulfite sequencing and pyrosequencing analysis through all preimplantation stages from one cell to blastocyst stage in in vivo or somatic cell nuclear transfer (SCNT). The Dnmt1o DMRs contained 8 CpG sites, which located in -640 bp to -30 bp upstream region from transcription start site of the Dnmt1o gene. The methylation status of 5 CpGs within the Dnmt1o DMRs were distinctively different at each stage from one-cell to blastocyst stage in the $in$ $vivo$ or SCNT, respectively. 55.62% methylation degree of the Dnmt1o DMRs in the $in$ $vivo$ was increased up to 84.38% in the SCNT embryo, moreover, $de$ $novo$ methylation and demethylation occurred during development of porcine embryos from the one-cell stage to the blastocyst stage. However, the DNA methylation states at CpG sites in the Dnmt1s promoter regions were hypomethylated, and dramatically not changed through one-cell to blastocyst stage in the $in$ $vivo$ or SCNT embryos. In the present study, we demonstrated that the DMRs in the promoter region of the porcine Dnmt1o was well conserved, contributing to establishment and maintenance of genome-wide patterns of DNA methylation in early embryonic development.

• Journal of Pharmacopuncture
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• v.25 no.2
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• pp.88-100
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• 2022

Gastric cancer (GC) is a significant cause of cancer mortality which has led to focused exploration of the pathology of GC. The advent of genome-wide analysis methods has made it possible to uncover genetic and epigenetic fluctuation such as abnormal DNA methylation in gene promoter regions that is expected to play a key role in GC. The study of gastric malignancies requires an etiological perspective, and Helicobacter pylori (H. pylori) was identified to play a role in GC. H. pylori infection causes chronic inflammation of the gastric epithelium causing abnormal polyclonal methylation, which might raise the risk of GC. In the last two decades, various pathogenic factors by which H. pylori infection causes GC have been discovered. Abnormal DNA methylation is triggered in several genes, rendering them inactive. In GC, methylation patterns are linked to certain subtypes including microsatellite instability. Multiple cancer-related processes are more usually changed by abnormal DNA methylation than through mutations, according to current general and combined investigations. Furthermore, the amount of acquired abnormal DNA methylation is heavily linked to the chances of developing GC. Therefore, we investigated abnormal DNA methylation in GC and the link between methylation and H. pylori infection.

• Oncology Reports
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• v.43 no.2
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• pp.655-661
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• 2020

Alterations in DNA methylation have a central role in the development and outcome of most human malignancies. Non-small cell lung cancer (NSCLC), the most common lung cancer, leads to the largest number of cancer-related deaths worldwide. FBJ murine osteosarcoma viral oncogene homolog B (FOSB) is a key component of the activator protein-1 transcription factor and regulates gene networks associated within oncogenic transformation. The role of FOSB in the development of NSCLC is still elusive. Therefore, the methylation status of the FOSB gene was investigated in NSCLC and its clinical significance in NSCLC progression was evaluated. The methylation status of the promoter and exon 4 regions of the FOSB gene were analyzed in 176 NSCLC specimens by bisulfite pyrosequencing and the association between FOSB methylation status and patient survival was investigated. Compared to adjacent non-malignant tissues, FOSB promoter exhibited exclusive unmethylation in all malignant tissues and the exon 4 region was found unmethylated in 18 (10.2% of the total) tumor samples. Exon 4 unmethylation was associated with downregulation of its mRNA and tended to occur in patients with lymph node metastasis. Univariate and multivariate analyses revealed that exon 4 unmethylation was significantly associated with unfavorable overall survival in patients with stage II-IIIA NSCLC (log-rank P=0.05, adjusted hazard ratio=2.43, 95% confidence interval=1.04-5.68, P=0.04). FOSB was identified as a novel gene with tumor-specific gene body unmethylation in NSCLC and a novel predictive biomarker for NSCLC prognosis. Moreover, the present results indicated that FOSB may have a tumor suppressor function in the progression of NSCLC.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.23
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• pp.10299-10306
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• 2015

The esophageal squamous cell carcinoma (ESCC) is thought to develop through a multi-stage process. Epigenetic gene silencing constitutes an alternative or complementary mechanism to mutational events in tumorigenesis. Posttranscriptional regulation of human leukocyte antigen class I (HLA-I) and antigen processing machinery (APM) proteins expression may be associated with novel epigenetic modifications in cancer development. In the present study, we determined the expression levels of HLA-I antigen and APM components by immunohistochemistry. Then by a bisulfite-sequencing PCR (BSP) approach, we identified target CpG islands methylated at the gene promoter region of APM family genes in a ESCC cell line (ECa109), and further quantitative analysis of CpG site specific methylation of these genes in cases of Kazakh primary ESCCs with corresponding non-cancerous esophageal tissues using the Sequenom MassARRAY platform. Here we showed that the development of ESCCs was accompanied by partial or total loss of protein expression of HLA-B, TAP2, LMP7, tapasin and ERp57. The results demonstrated that although no statistical significance was found of global target CpG fragment methylation level sof HLA-B, TAP2, tapasin and ERp57 genes between ESCC and corresponding non-cancerous esophageal tissues, there was significant differences in the methylation level of several single sites between the two groups. Of thesse only the global methylation level of LMP7 gene target fragments was statistically higher ($0.0517{\pm}0.0357$) in Kazakh esophageal cancer than in neighboring normal tissues ($0.0380{\pm}0.0214$, p<0.05). Our results suggest that multiple CpG sites, but not methylation of every site leads to down regulation or deletion of gene expression. Only some of them result in genetic transcription, and silencing of HLA-B, ERp57, and LMP7 expression through hypermethylation of the promoters or other mechanisms may contribute to mechanisms of tumor escape from immune surveillance in Kazakh esophageal carcinogenesis.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.1
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• pp.355-362
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• 2014

Objective: Altered regulation of many transcription factors has been shown to play important roles in the development of leukemia. hMSH2 can modulate the activity of some important transcription factors and is known to be a regulator of hematopoietic differentiation. Herein, we investigated epigenetic regulation of hMSH2 and its influence on cell growth and overall survival of acute lymphoblastic leukemia (ALL) patients. Methods: hMSH2 promoter methylation status was assessed by COBRA and pyrosequencing in 60 ALL patients and 30 healthy volunteers. mRNA and protein expression levels of hMSH2, PCNA, CyclinD1, Bcl-2 and Bax were determined by real time PCR and Western blotting, respectively. The influence of hMSH2 on cell proliferation and survival was assessed in transient and stable expression systems. Results: mRNA and protein expression of hMSH2 and Bcl-2 was decreased, and that of PCNA, CyclinD1 and Bax was increased in ALL patients as compared to healthy volunteers (P<0.05). hMSH2 was inactivated in ALL patients through promoter hypermethylation. Furthermore, hMSH2 hypermethylation was found in relapsed ALL patients (85.7% of all cases). The median survival of patients with hMSH2 methylation was shorter than that of patients without hMSH2 methylation (log-rank test, P=0.0035). Over-expression of hMSH2 in cell lines resulted in a significant reduction in growth and induction of apoptosis. Conclusions: This study suggests that aberrant DNA methylation and epigenetic inactivation of hMSH2 play an important role in the development of ALL through altering cell growth and survival.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.6
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• pp.2485-2489
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• 2014

In the present study, we studied the hypermethylation of the human riboflavin transporter 2 (hRFT2) gene and regulation of protein expression in biopsies from resected tissues from Uighur cervical squamous cell carcinoma (CSCC) patients and their neighboring normal tissues. hRFT2 gene promoter region methylation sequences were mapped in cervical cancer cell line SiHa by bisulfite-sequencing PCR and quantitative detection of methylated DNA from 30 pairs of Uighur's CSCCs and adjacent normal tissues by MassARRAY (Sequenom, San Diego, CA, USA) and hRFT2 protein expression was analyzed by immunohistochemistry. In SiHa, we identified 2 CG sites methylated from all of 12CpG sites of the hRFT2 gene. Analysis of the data from quantitative analysis of single CpG site methylation by Sequenom MassARRAY platform showed that the methylation level between two CpG sites (CpG 2 and CpG 3) from CpG 1~12 showed significant differences between CSCC and neighboring normal tissues. However, the methylation level of whole target CpG fragments demonstrated no significant variation between CSCC ($0.476{\pm}0.020$) and neighboring normal tissues ($0.401{\pm}0.019$, p>0.05). There was a tendency for translocation the hRFT2 proteins from cytoplasm/membrane to nucleus in CSCC with increase in methylation of CpG 2 and CpG 3 in hRFT2gene promoter regions, which may relate to the genesis of CSCC. Our results suggested that epigenetic modifications are responsible for aberrant expression of the hRFT2 gene, and may help to understand mechanisms of cervical carcinogenesis.