Clinical features of CpG island methylation in colon cancer and its prognostic significance in dMMR colon cancer / 国际外科学杂志

Objective:To investigate the clinical characteristics and prognosis of CpG island methylator phenotype (CIMP+ ) colon cancer, and the significance of CIMP status in the diagnosis and prognosis prediction in defective mismatch repair (dMMR) colon cancer.Methods:The keywords "colorectal cancer" "patient" and "CpG Island Methylator Phenotype" were used to search the Gene Expression Omnibus (GEO) database, and the GSE39582 was obtained, which included the clinical data of 585 patients with colorectal cancer and the sequencing data of the whole transcriptome of the tumor tissues. After excluding 72 cases with missing CIMP values, 513 cases were included for further analysis, including 278 males and 235 females, with a mean age of (67±13) years. According to the CIMP status, they were divided into CIMP+ group ( n=93) and CIMP-group ( n=420), then compare the differences in clinical characteristics, the Kaplan-Meier survival curves were plotted to compare the overall survival and disease-free survival; 71 dMMR cases were divided into CIMP+ group ( n=43) and CIMP-group ( n=28), and the K-M curves were plotted to analyze the differences in overall survival (OS) and disease free survival (DFS). Comparisons between groups were performed by t-test, χ2 test or Mann-Whitney U nonparametric test, and the difference in survival curves was tested by Long-rank test. Results:Patients in the CIMP+ group were significantly older than those in the CIMP-group [(70.84±12.60) years vs (66.21±13.08) years, t=3.18, P=0.002]. Right colon tumors originating from the CIMP+ molecular pathway were 9.3 times more likely to be CIMP+ than those of the left colon cancers ( OR=9.3, 95% CI: 5.2-17.9). BRAF mutant colon cancer originating from CIMP+ was 215.2 times more common than BRAF wild-type colon cancer originating with CIMP+ ( OR=215.2, 95% CI: 53.2-1906.7); and patients with dMMR colon cancer originated 12.8 times more common than patients with pMMR ( OR=12.8, 95% CI: 7.0-23.9). The difference between the CIMP+ and CIMP-groups was not statistically significant in terms of overall survival and disease-free survival ( P=0.590, 0.220). In the dMMR colon cancer subgroup, CIMP status did not correlate with patients′ overall survival and disease-free survival ( P>0.05). Conclusions:CIMP+ colon cancer patients were mostly of advanced age, with tumors originating from the right colon, mostly combined with BRAF gene mutations, and manifested as mismatch repair-deficient colon cancers. CIMP status had no correlation with TNM stage and survival of colon cancers patients. There was no significant difference in the survival between dMMR colon cancers caused by CIMP+ and those caused by MMR gene mutations.

Methylated CpG dinucleotides in the 5-α reductase 2 gene may explain finasteride resistance in benign prostatic enlargement patients / 亚洲男科学杂志(英文版)

The inhibition of 5-α reductase type 2 (SRD5A2) by finasteride is commonly used for the management of urinary obstruction resulting from benign prostatic enlargement (BPE). Certain BPE patients showing no SRD5A2 protein expression are resistant to finasteride therapy. Our previous work showed that methylated cytosine-phosphate-guanine (CpG) islands in the SRD5A2 gene might account for the absence or reduction of SRD5A2 protein expression. Here, we found that the expression of the SRD5A2 protein was variable and that weak expression of the SRD5A2 protein (scored 0-100) occurred in 10.0% (4/40) of benign adult prostates. We showed that the expression of SRD5A2 was negatively correlated with DNA methyltransferase 1 (DNMT1) expression. In vitro SRD5A2-negative BPH-1 cells were resistant to finasteride treatment, and SRD5A2 was re-expressed in BPH-1 cells when SRD5A2 was demethylated by 5-Aza-2'-deoxycytidine (5-Aza-CdR) or N-phthalyl-L-tryptophan (RG108). Furthermore, we determined the exact methylation ratios of CpG dinucleotides in a CpG island of SRD5A2 through MassArray quantitative methylation analysis. Ten methylated CpG dinucleotides, including four CpG dinucleotides in the promoter and six CpG dinucleotides in the first exon, were found in a CpG island located from -400 bp to +600 bp in SRD5A2, which might lead to the silencing of SRD5A2 and the absence or reduction of SRD5A2 protein expression. Finasteride cannot exert a therapeutic effect on patients lacking SRD5A2, which may partially account for the resistance to finasteride observed in certain BPE patients.

Association between DNA methylation in the CpG island of dopamine D2 receptor gene promoter region and persistent postural-perceptual dizziness / 中华神经医学杂志

Objective:To analyze the relation between DNA methylation in the CpG island of dopamine D2 receptor ( DRD2) gene promoter region and persistent postural-perceptual dizziness (PPPD), and explore the molecular mechanism of PPPD. Methods:The disease group consisted of 43 patients diagnosed as having PPPD in our hospital from January 2017 to June 2017, and blood samples were taken at admission. The control group included 45 with acute vestibular peripheral vertigo whose dizziness symptoms did not recrudesce after follow-up for more than 3 months and PPPD diagnosis was excluded in our hospital at the same period; these patients did not take selective serotonin reuptake inhibitors (SSRIs) or serotonin norepinephrine reuptake inhibitors (SNRIs); blood samples in the patients were collected during follow-up. DNA methylation in the CpG island of DRD2 promoter region was detected by disulfite sequencing and the differences between the two groups were compared. Results:The positive rate of DNA methylation in the CpG island of DRD2 promoter region in the disease group was 58.1%, which was significantly higher than that in the control group (15.6%, P<0.05); and the methylation rate of CpG island loci in the disease group (0.15±0.18) was significantly higher than that in the control group (0.04±0.10, P<0.05). Conclusion:The DNA methylation in the CpG island of DRD2 promoter region is associated with onset of PPPD.

A review of computational algorithms for CpG islands detection

Type II diabetes mellitus (T2DM) and obesity are two common pathophysiological conditions of metabolic syndrome(MetS), a collection of similar metabolic dysfunctions due to sedentary lifestyle and overnutrition. Obesity arises fromimproper adipogenesis which otherwise has a crucial role in maintaining proper metabolic functions. Downstream eventsarising from obesity have been linked to T2DM. The nuclear receptor peroxisome proliferator activator gamma (PPAR-c),responsible for maintaining lipid and glucose homeostasis, is down-regulated under obesity leading to a weakened insulinsensitivity of the human body. In course of our review we will outline details of the down-regulation mechanism, provide anoverview of the current clinical therapeutics and their shortcomings. Toxicity studies on the seminal drug troglitazone,belonging to the most effective glitazone anti-diabetic category, is also discussed. This will lead to an overview aboutstructural adaptations on the existing glitazones to alleviate their side effects and toxicity. Finally, we forward a concept ofnovel therapeutics mimicking the glitazone framework, based on some design concepts and preliminary in silico studies.These could be later developed into dual acting drugs towards alleviating the deleterious effects of obesity on normalglucose metabolism, and address obesity in itself.

Research progress of biomarkers in diagnosis and therapy of colorectal cancer / 国际生物医学工程杂志

Colorectal cancer (CRC) is one of the most common human malignant diseases, the cumulative result of genetic and epigenetic mutations, and its mortality rate is second only to that of lung cancer. Most patients with CRC have developed to middle to advanced stage when symptoms appear, and the treatment effects of surgery and chemotherapy are usually not satisfactory. With the emergence of targeted drugs in recent years, individualized treatment of colorectal cancer has gradually become a trend. With the development of colorectal cancer research, more and more molecular markers of colorectal cancer have been continuously discovered, and its impact on tumorigenesis, development and treatment has gradually received more attention. The application of molecular markers in the screening of colorectal cancer can help the early detection and diagnosis. Detection of molecular markers before individualized treatment can optimize the treatment plan and prompt the patient's prognosis. In this paper, the most recent findings of molecular markers with promising clinical application were summarized, in order to provide reference for the early diagnosis and treatment of colorectal cancer.

CpG Island Methylator Phenotype and Methylation of Wnt Pathway Genes Together Predict Survival in Patients with Colorectal Cancer

PURPOSE: Dysregulation of the Wnt pathway is a crucial step in the tumorigenesis of colorectal cancer (CRC). This study aimed to determine whether DNA methylation of Wnt pathway genes helps predict treatment response and survival in patients with metastatic or recurrent CRC. MATERIALS AND METHODS: We retrospectively collected primary tumor tissues from 194 patients with metastatic or recurrent CRC. Pyrosequencing was used to examine the methylation of 10 CpG island loci in DNA extracted from formalin-fixed paraffin-embedded specimens. To elucidate the predictive role of DNA methylation markers, Kaplan-Meier survival estimation and Cox regression were performed for progression-free survival and overall survival (OS). RESULTS: The methylation frequencies of the 10 genes analyzed (p16, p14, MINT1, MINT2, MINT31, hMLH1, DKK3, WNT5A, AXIN2, and TFAP2E) were 47.9%, 10.8%, 21.1%, 16.0%, 20.6%, 0.5%, 53.1%, 32.0%, 2.6%, and 2.1%, respectively. We divided patients into three groups based on the number of methylated genes (group 1, no methylation n=38; group 2, 1–2 methylations n=92; group 3, 3 or more methylations n=64). Among patients treated with palliative chemotherapy (n=167), median OSs of groups 1, 2, and 3 were 39.1, 39.7, and 29.1 months, respectively (log rank p=0.013). After adjustment, number of methylations was identified as an independent poor prognostic factor (0–2 methylated vs. ≥3 methylated: hazard ratio, 1.72; 95% confidence interval, 1.16–2.56, p=0.007). CONCLUSION: This study suggests that methylation of Wnt pathway genes, in addition to known CpG island methylator phenotype markers, may help predict treatment outcome and survival in patients with CRC.

Caracterización de pacientes con cáncer colorrectal esporádico basado en la nueva subclasificación molecular de consenso / Characterization of patients with sporadic colorectal cancer following the new Consensus Molecular Subtypes (CMS)

Background: Colorectal cancer (CRC) is an heterogeneous disease. Three carcinogenic pathways determine its molecular profile: microsatellite instability (MSI), chromosomal instability (CIN) and CpG island methylator phenotype (CIMP). Based on the new molecular classification, four consensus CRC molecular subtypes (CMS) are established, which are related to clinical, pathological and biological characteristics of the tumor. Aim: To classify Chilean patients with sporadic CRC according to the new consensus molecular subtypes of carcinogenic pathways. Material and Methods: Prospective analytical study of 53 patients with a mean age of 70 years (55% males) with CRC, operated at a private clinic, without neoadjuvant treatment. From normal and tumor tissue DNA of each patient, CIN, MSI and CIMP were analyzed. Combining these variables, tumors were classified as CMS1/MSI-immune, CMS2/canonical, CMS3/metabolic and CMS4/mesenchymal. Results: CMS1 tumors (19%) were located in the right colon, were in early stages, had MMR complex deficiencies and 67% had an activating mutation of the BRAF oncogene. CMS2 tumors (31%) were located in the left colon, had moderate differentiation, absence of vascular invasion, lymphatic and mucin. CMS3 tumors (29%) were also left-sided, with absence of vascular and lymphatic invasion, and 29% had an activating mutation of the KRAS oncogene. CMS4 tumors (21%) showed advanced stages and presence of metastases. Conclusions: This new molecular classification contributes to understanding the heterogeneity of tumors. It is possible to differentiate molecular subgroups of a single pathological diagnosis of adenocarcinoma, opening the door to personalized medicine.

Clinical value of peripheral blood Runx3 gene CpG island's methylation in the evaluation of colon cancer's disease condition and prognosis / 中国现代普通外科进展

Objective:To study the clinical value of peripheral blood Runx3 gene CpG island's methylation in the evaluation of colon cancer's disease condition and prognosis.Methods:Methy1ation specific PCR was used to detect the Runx3 gene CpG island's methylation by Peripheral blood in colon cancer patient (observation group) and healthy people (control group).The Runx3 gene CpG island's methylation rates in different clinicopathological factors were compared.The 3 year survival rate and total survival time between patient with Runx3 gene CpG island's methylation and unmethylation were Compared.Result:The Runx3 gene CpG island's methylation rate in observation group was significantly higher than in control group (P＜0.05).The Runx3 gene CpG island's methylation rates in degree of differentiation,maximum tumor diameter,lymph node metastasis,distant metastasis,TNM staging and surgical resection were significant different (P＜0.05).The 3 year survival rate and total survival time in patient with Runx3 gene CpG island's methylation were significantly higher than in patient with Runx3 gene CpG island's unmethylation.Conclusion:Runx3 gene CpG island is hypermethylated in colon cancer's peripheral blood,which has value in the evaluation of colon cancer's disease condition and prognosis.

Correlation between Hypermethylation of SFRP2 promoter CpG island and colorectal cancer / 中国现代普通外科进展

Objective:SFRP2 gene is a member of the SFRPs family.The gene is located on chromosome 4q31.3 with 3 exons and 2 introns and first exons have higher density near the island of CpG.Many studies showed that the methylation level of SFRP2 gene and colon cancer,esophageal cancer,gastric cancer and other tumor occurrence relating to,development and prog nosis.This study aims to study the clinical characteristics of CpG SFRP2 promoter island hypermethylation in colorectal cancer and whether there is a certain correlation.Methods:by matrix assisted laser desorption ionization time of flight mass spectrometry for detecting specific CpG island methylation.Methylation status of SFRP2 promoter by Sequenom EpiTYPER was detected in 20 cases of normal tissue of colorectal cancer and tumor tissues.Results:Our study using multiple linear regression analysis in tumor tissue of SFRP2 methylation at promoter Ⅰ and Ⅱ,found that SFRP2 promoter methylation and clinical features of.SFRP2_01_CpG_5 significantly correlated (P=0.018),SFRP2_02_CpG_5 (P=0.018) associated with the location of the tumor,SFRP2_02_CpG_6,7,8,9(P=0.039) and the number of lymph node metastasis of.SFRP2_01_CpG_1.2(P=0.043),SFRP2_02_CpG_16 (P=0.044) correlated with tumor size.Conclusion:we from epigenetic aspects of its promoter CpG methylation level and colorectal cancer clinical and pathological features,found a correlation between clinical and pathological features of colorectal cancer and CpG methylation in its promoter,suggesting that the SFRP2 promoter may be at this stage of colorectal cancer and future biological genetics the progress of the potential surface markers.

CpG Island Methylator Phenotype-High Colorectal Cancers and Their Prognostic Implications and Relationships with the Serrated Neoplasia Pathway

The concept of a CpG island methylator phenotype (CIMP) was first introduced by Toyota and Issa to describe a subset of colorectal cancers (CRCs) with concurrent hypermethylation of multiple CpG island loci. The concept of CIMP as a molecular carcinogenesis mechanism was consolidated by the identification of the serrated neoplasia pathway, in which CIMP participates in the initiation and progression of serrated adenomas. Distinct clinicopathological and molecular features of CIMP-high (CIMP-H) CRCs have been characterized, including proximal colon location, older age of onset, female preponderance, and frequent associations of high-level microsatellite instability and BRAF mutations. CIMP-H CRCs arise in sessile or traditional serrated adenomas and thus tend to display the morphological characteristics of serrated adenomas, including epithelial serration, vesicular nuclei, and abundant cytoplasm. Both the frequent association of CIMP and poor prognosis and different responses of CRCs to adjuvant therapy depending on CIMP status indicate clinical implications. In this review, we present an overview of the literature documenting the relevant findings of CIMP-H CRCs and their relationships with the serrated neoplasia pathway.

Bioinformatics analysis of the human MTERF1 gene promoter / 医学研究生学报

Objective The proteins encoded by mitochondrial transcription termination factor 1 ( MTERF1) plays important roles in regulating the mitochondrial gene expression and oxidative phosphorylation .This study was to investigate the characteristics and regulation mechanisms of the human MTERF1 gene with bioinformatics tools . Methods Using online bioinformatics software and phylogenetic foot-printing, we analyzed the promoter distribution , GpG island, transcription factors , and binding sites of the human MTERF1 gene. Results The human MTERF1 gene was located on 7q21.2, with a full length of 7845 bp, consisting of 4 exons and 3 introns.There were at least 2 promoters in the 5′region of the gene.The core promoter of the MTERF1 gene was located between 1878 and 2447 bp, which played a key role in its transcription .An 812 bp CpG island was observed in the gene promoter region .In addi-tion, 26 transcription factor binding sites were found in the conserved promoter region of human and mouse homologous MTERF1 genes. Conclusion Gene promoter-related online bioinformatics software can improve the efficiency of human MTERF1 gene promoter resear-ches and provide significant information for the prediction of gene pro-moter function.

variants: the impact on drug metabolism and therapeutic responses

The pregnane X receptor (PXR) plays an important and diverse role in mediating xenobiotic induction of drug-metabolizing enzymes and transporters. Several protein isoforms of PXR exist, and they have differential transcriptional activity upon target genes; transcript variants 3 (PXR3) and 4 (PXR4) do not induce target gene expression, whereas transcript variants 1 (PXR1) and 2 (PXR2) respond to agonist by activating target gene expression. PXR protein variants also display differences in protein-protein interactions; PXR1 interacts with p53, whereas PXR3 does not. Furthermore, the transcript variants of PXR that encode these protein isoforms are differentially regulated by methylation and deletions in the respective promoters of the variants, and their expression differs in various human cancers and also in cancerous tissue compared to adjacent normal tissues.andmRNA are downregulated by methylation in cancerous tissue and have divergent effects on cellular proliferation when ectopically overexpressed. Additional detailed and comparative mechanistic studies are required to predict the effect of PXR transcript variant expression on carcinogenesis, therapeutic response, and the development of toxicity.

Epigenetic regulatory effects of the methylation of CpG island shore on the expression of lag3 gene in various human T cell lines / 中华微生物学和免疫学杂志

Objective To investigate the effects of DNA methylation on the expression of lympho-cyte activation gene 3 (lag3) in different human T cell lines.Methods A quantitative PCR and a flow cy-tometry analysis were performed to measure the expression of lag3 gene in various T cell lines at mRNA and protein levels.The distribution of CpG sites within the promoter and body of lag3 gene was detected to locate the potential regulatory region(s) (CpG island and CpG island shore).The levels of DNA methylation in each cell line were analyzed.The T cell lines were demethylated with 5-Aza-2′-deoxycytidine (5-Aza-2′-dc) for further investigation on the changes of lag3 gene expression and DNA methylation.Results Jurkat E6-1 cells showed the highest expression level of lag3 gene as compared with J.CaM1.6 and CEM cells.Hyperm-ethylated CpG islands were detected in cells of each cell line.The methylation levels of CpG island shore in J.CaM1.6 and CEM cells were higher than that in Jurkat E6-1 cells.Treatment of J.CaM1.6 and CEM cells with 5-Aza-2′-dc significantly promoted the expression of lag3 gene at mRNA and protein levels as well as the demethylation of CpG island shore.No significant differences with the expression of lag3 gene and the methylation of CpG island were observed in Jurkat E6-1 cells with or without 5-Aza-2′-dc stimulation.Con-clusion Methylation and demethylation of CpG island shore played important roles in regulating the tran-scription of lag3 gene.

A Study on CpG Island Methylator Phenotype involving Tumor Suppressor Genes on Chromosome 3p in Gastric Cancer / 胃肠病学

Background:CpG island methylator phenotype(CIMP)involving tumor suppressor gene( TSG)on short arm of chromosome 3(chromosome 3p)has been found in various types of cancers. However,its correlation with gastric cancer has not been clarified. Aims:To study the clinical significance of CIMP involving TSG on chromosome 3p in gastric cancer. Methods:Methylation specific PCR(MSP)was used to examine methylation profiles for hOGG1,VHL,RAR-B, hMLH1,SEMA3B,RASSF1A,BLU and FHIT harbored in chromosome 3p in 100 gastric cancer and paired paracancerous tissues. High CIMP( CIMP-H)was referred for those samples having four or more synchronously methylated genes. Relationship between CIMP-H and clinicopathological characteristics in gastric cancer was analyzed. Results:Positive methylation rates of VHL(P = 0. 030),hMLH1(P 0. 05). Conclusions:CIMP on chromosome 3p may occur in early stage of oncogenesis of gastric cancer,and influencing tumor differentiation and lymph node metastasis.

The Role of the CpG Island Methylator Phenotype on Survival Outcome in Colon Cancer

BACKGROUND/AIMS: CpG island methylator phenotype (CIMP)- high colorectal cancers (CRCs) have distinct clinicopathological features from their CIMP-low/negative CRC counterparts. However, controversy exists regarding the prognosis of CRC according to the CIMP status. Therefore, this study examined the prognosis of Korean patients with colon cancer according to the CIMP status. METHODS: Among a previous cohort population with CRC, a total of 154 patients with colon cancer who had available tissue for DNA extraction were included in the study. CIMP-high was defined as 3/5 methylated markers using the five-marker panel (CACNA1G, IGF2, NEUROG1, RUNX3, and SOCS1). RESULTS: CIMP-high and CIMP-low/negative cancers were observed in 27 patients (17.5%) and 127 patients (82.5%), respectively. Multivariate analysis adjusting for age, gender, tumor location, tumor stage and CIMP and microsatellite instability (MSI) statuses indicated that CIMP-high colon cancers were associated with a significant increase in colon cancer-specific mortality (hazard ratio [HR], 3.23; 95% confidence interval [CI], 1.20 to 8.69; p=0.02). In microsatellite stable cancers, CIMP-high cancer had a poor survival outcome compared to CIMP-low/negative cancer (HR, 2.91; 95% CI, 1.02 to 8.27; p=0.04). CONCLUSIONS: Regardless of the MSI status, CIMP-high cancers had poor survival outcomes in Korean patients.

The Role of the CpG Island Methylator Phenotype on Survival Outcome in Colon Cancer

BACKGROUND/AIMS: CpG island methylator phenotype (CIMP)- high colorectal cancers (CRCs) have distinct clinicopathological features from their CIMP-low/negative CRC counterparts. However, controversy exists regarding the prognosis of CRC according to the CIMP status. Therefore, this study examined the prognosis of Korean patients with colon cancer according to the CIMP status. METHODS: Among a previous cohort population with CRC, a total of 154 patients with colon cancer who had available tissue for DNA extraction were included in the study. CIMP-high was defined as 3/5 methylated markers using the five-marker panel (CACNA1G, IGF2, NEUROG1, RUNX3, and SOCS1). RESULTS: CIMP-high and CIMP-low/negative cancers were observed in 27 patients (17.5%) and 127 patients (82.5%), respectively. Multivariate analysis adjusting for age, gender, tumor location, tumor stage and CIMP and microsatellite instability (MSI) statuses indicated that CIMP-high colon cancers were associated with a significant increase in colon cancer-specific mortality (hazard ratio [HR], 3.23; 95% confidence interval [CI], 1.20 to 8.69; p=0.02). In microsatellite stable cancers, CIMP-high cancer had a poor survival outcome compared to CIMP-low/negative cancer (HR, 2.91; 95% CI, 1.02 to 8.27; p=0.04). CONCLUSIONS: Regardless of the MSI status, CIMP-high cancers had poor survival outcomes in Korean patients.

Aberrant CpG Islands Hypermethylation Profiles in Malignant Gliomas

BACKGROUND: The authors analyzed whether the promoter hypermethylation of cancer-related genes was involved in the tumorigenesis of malignant gliomas. METHODS: A total of 29 patients received surgery and histologically confirmed to have malignant gliomas from January 2000 to December 2006. The promoter methylation status of several genes, which were reported to be frequently methylated in malignant gliomas, was investigated using methylation-specific polymerase chain reaction. RESULTS: All cases of malignant gliomas represented the promoter hypermethylation in at least 2 or more genes tested. Of 29 tumors, 28 (96.55%) showed concurrent hypermethylation of 3 or more genes. Ras association domain family member 1, epithelial cadherin, O-6 methyl guanine DNA methyltransferase, thrombospondin 1, p14 and adenomatous polyposis coli were frequently methylated in high grade gliomas including glioblastomas, anaplastic astrocytomas, and anaplastic oligodendrogliomas. CONCLUSION: Aberrant hypermethylation profile was closely related with malignant gliomas suggesting that epigenetic change may play a role in the development of malignant gliomas. Two or three target genes may provide useful clues to the development of the useful prognostic as well as diagnostic assays for malignant gliomas.

Methylation of the ERCC1 gene and its protein expression in gastric cancer / 中国肿瘤临床

Objective:This study aims to detect the CpG island methylation status of the ERCC1 gene promoter and the expres-sion of the ERCC1 protein in gastric cancer tissues, as well as to investigate the correlation and significance between ERCC1 gene pro-moter CpG island methylation and protein expression. Methods:Methylation-specific PCR was performed to detect the methylation sta-tus of the ERCC1 gene in tumor tissues and adjacent cancerous tissues from 30 gastric cancer patients. Ten cases of normal gastric tis-sues were used as control. Expression of the ERCC1 protein in gastric cancer tissues, adjacent cancerous tissues, and normal gastric tis-sues was examined by immunohistochemistry S-P method. Results:The methylation rate of the ERCC1 gene promoter CpG island in gastric cancer tissues was significantly higher than that in adjacent cancerous tissues (76.7%vs. 13.3%, P<0.05), and the difference was statistically significant. The incidence of promoter methylation was not found in 10 normal gastric tissues. The negative rate of ERCC1 protein expression in 30 cases of gastric carcinoma tissues was significantly higher than that in adjacent cancerous tissues (70.0% vs. 33.3%, P<0.05), whereas 10 normal gastric tissues all exhibited positive expression for the ERCC1 protein. The tumor tissues with ER-CC1 gene promoter CpG island methylation showed a lower expression of ERCC1 protein than the unmethylated tumor tissues in gas-tric cancer patients. Conclusion:Methylation of the ERCC1 gene promoter CpG island and protein expression are negatively correlat-ed, and methylation of the CpG island of the ERCC1 gene may be one of the main reasons for the down-regulation of protein expres-sion.

The relationship between methylation of ERCC1 gene in peripheral blood and in gastric cancer tissues / 中国癌症杂志

Background and purpose: At present, gastric cancer is considered to be both genetic and epigenetic disease, and epigenetic alterations play a significant role in the development of gastric cancer. DNA methylation is the most well studied and most in-depth epigenetic modiifcations in human-beings. The silencing of tumor-related genes by DNA methylation is reversible. ERCC1 is a kind of DNA repair gene. The present study was aimed to detect the CpG island methylation status of ERCC1 gene promoter in gastric cancer tissues and corresponding peripheral blood, and to explore the relationship between methylation of ERCC1 gene in peripheral blood and in gastric cancer tissues. Methods:Methylation speciifc PCR was performed to detect the methylation status of ERCC1 gene in the tumor tissues and the paired peripheral blood from 30 gastric cancer patients. Results:The positive rate of methylation of ERCC1 gene promoter CpG island was 76.7%(23/30) in the tumor tissues and 63.3%(19/30) in serum of gastric cancer patients, and the difference had no statistical signiifcance. Conclusion:Our studies suggest that ERCC1 gene promoter CpG island methylation can be detected in a high proportion of the serum consisting with that in tumor tissues of gastric cancer patients, and the detection of methylation status of ERCC1 gene in peripheral blood provides a more simple, fast and reliable way for the medical treatment of gastric cancer and also provides the possible theoretical basis for the CpG island methylation of ERCC1 gene promoter as a target for the treatment of gastric cancer.

Genes con islas CpG amplificados con la mezcla formamida, albúmina sérica bovina y dimetilsulfóxido / CG-rich genes amplified with the formamide, bovine seric albumin y dimethylsulfoxide mix / Genes com Ilhas CpG amplificados com a mistura formamida, albumina sérica bovina, e dimetilsulfóxido

Diversos aditivos químicos han sido utilizados para garantizar la polimerización de genes con islas CpG. El objetivo de este trabajo fue diseñar una mezcla potenciadora de PCR para amplificar genes con islas CpG. Con ese fin se analizaron fragmentos de los genes IRS2 y HNF1a con el programa EMBOSS CpG Report. Los iniciadores se diseñaron con el programa Primer 3 y se analizaron con el programa e-PCR. Se usaron tres aditivos químicos: Albúmina sérica bovina (0,1µg/µL), dimetilsulfóxido (5%) y formamida (5%) para 5 ensayos de PCR: dos usando un solo aditivo, dos combinando dos aditivos y uno combinando tres aditivos. Las amplificaciones con las mezclas se realizaron con las enzimas Taq Nativa, taq Recombinante y Taq Platinum. La calidad de los amplicones se probó por secuenciación. Fragmentos sin islas CpG (HNF-1a) amplificaron con las tres enzimas, sin el uso de los aditivos pero presentaron problemas de pureza en la secuenciación. Los fragmentos del gen IRS2 con islas CpG amplificaron sólo con la combinación de tres aditivos dimetilsulfóxido, albúmina sérica bovina y formamida, independientemente de la enzima usada, las secuencias fueron limpias. Se concluye que la mezcla de tres aditivos es una solución que permite obtener amplicones de alta calidad en genes con islas CpG, con cromatogramas limpios en la secuenciación.

Several chemical additives have been used to assure polymerization in CpG islands.The aim of the present work was to design a PCR enhancer mixture in order to amplify GC-rich genes. Fragments of IRS2 and HNF1a genes were analyzed using EMBOSS CpG Report Software. Primers were designed with the Primer3 Software and were tested with ePCR Software. Three additives were used: BSA (0.1µg/µL), DMSO (5%) and formamide (5%), in five PCR assays, two using one additive, two combining two additives and one with all additives. DNA sequences were amplified with the following enzymes: Native Taq, recombinant Taq and platinum Taq DNA polymerase. Amplicon quality was examined by sequencing. HNF1a gene was amplified without additives; however, the sequences were not amplified and showed purity problems in sequencing. The gene fragments IRS2 with CpG islands were amplified with additives DMSO, BSA and Formamida mixture, notwithstanding the enzyme used. These sequences were clean. DMSO-BSA-Formamide mixture can be a solution to obtain GC-rich DNA amplicons with such a high quality that it generates neat chromatograms during sequencing.

Diversos aditivos químicos têm sido utilizados para garantir a polimerização de genes com ilhas CpG. O objetivo do trabalho foi desenhar uma mistura que potencie PCR para amplificar genes com ilhas CpG. Para esta finalidade foram analisados fragmentos dos genes IRS2 e HNF1a com o programa EMBOSS CpG Report. Os iniciadores foram desenhados com o programa Primer 3 e se analisaram com o programa e-PCR. Foram utilizados três aditivos químicos: Albumina sérica bovina (0,1µg/µlL, Dimetilsulfóxido (5%) e formamida (5%) para 5 ensaios de PCR: dois usando um único aditivo, dois combinando dois aditivos e um combinando três aditivos. As amplificações com as misturas se realizaram com as enzimas, Taq Nativa, taq Recombinante e Taq Platinum. A qualidade das ampliações foi provada por sequenciação. Fragmentos sem ilhas CpG (HNF-1a) amplificaram com as três enzimas, sem o uso dos aditivos porém apresentaram problemas de pureza na sequenciação. Os fragmentos do gene IRS2 com ilhas CpG ampli­ficaram apenas com a combinação de três aditivos dimetilsulfóxido, albumina sérica bovina e formamida, independentemente da enzima usada, as sequências foram limpas. A conclusão que a mistura de três aditivos é uma solução que permite obter ampliações de alta qualidade em genes com ilhas CpG, com cromatogramas limpos na secuenciação.