Association between Ras association domain family 1A promoter methylation and hepatocellular carcinoma: A meta-analysis

AIM:To assess diagnostic accuracy of Ras association domain family 1A(RASSF1A)promoter methylation in body fluids(serum,plasma and whole blood)for hepatocellular carcinoma(HCC).METHODS:Relative information about study characteristics and incidence of RASSF1A methylation was collected.Quality of all included studies was evaluated by Quality Assessment of Diagnostic Accuracy Studies-2.Sensitivity and specificity were pooled using a randomeffect model,and a summary receiver operating characteristic curve was used to demonstrate the overall diagnostic performance.Positive likelihood ratio(PLR),negative likelihood ratio(NLR),and diagnostic odds ratio(DOR)with 95%CI were also calculated.Meta-regression was applied to analyze observed heterogeneity,and Deeks’test was performed to detect publication bias.RESULTS:After a systematic literature review,seven studies with a total of 302 cases of HCC and 250 cases of chronic liver diseases were included in the analysis.The pooled sensitivity and specificity were 0.70(95%CI:0.49-0.85)and 0.72(95%CI:0.54-0.85),respectively.The PLR was 2.51(95%CI:1.64-3.86),NLR was 0.41(95%CI:0.25-0.68),and DOR was 6.13(95%CI:3.17-11.84).Theχ2values of sensitivity,specificity,PLR,NLR and DOR were 59.41(P<0.001),50.50(P<0.001),17.40(P=0.010),31.24(P<0.001)and80.51(P<0.001),respectively.The area under the curve was 0.77(95%CI:0.73-0.81).Three factors were analyzed by univariate meta-regression and none was significant to interpret the observed heterogeneity(P>0.05).No significant publication bias was detected by Deeks’test(P=0.346).CONCLUSION:We showed the potential diagnostic value of RASSF1A methylation in body fluids in HCC patients and it may improve diagnostic accuracy combined with theα-fetoprotein test.     

APC promoter methylation and protein expression in hepatocellular carcinoma

Purpose We investigated the impact of promoter methylation on APC protein expression in patients with hepatocellular carcinoma (HCC). Materials and methods 50 patients [HCC (n=19), liver metastasis (n=19), cholangiocellular cancer (n=7), and benign liver tumors (n=5)] were studied for methylation using Methylight analysis. APC mutation was investigated by protein truncation test and direct sequencing of genomic DNA. The protein expression was evaluated by immunohistochemistry and Western blot analysis. Results The APC promoter was hypermethylated in 81.8% of non-cancerous liver tissue samples. All HCC samples and ten patients with liver metastasis (52.6%) exhibited APC promoter methylation. The degree of methylation was significantly higher in samples from HCC compared to the non-cancerous liver tissue samples (63.1% vs. 24.98%; p=0.001). The level of APC protein expression was significantly reduced in HCC samples compared to that of the corresponding non-tumor liver tissue (p<0.05). Conclusions Promoter methylation of the APC gene seems to be of significance in hepatocarcinogenesis and results in reduced protein expression in HCC. Interestingly, APC promoter methylation is also present in the vast majority of non-cancerous liver tissue whose (patho)physiological function remains unresolved.     

KISS1 methylation and expression as predictors of disease progression in colorectal cancer patients

AIM:To examine the effect of aberrant methylation of the KISS1 promoter on the development of colorectal cancer(CRC)and to investigate reversing aberrant methylation of the KISS1 promoter as a potential therapeutic target.METHODS:KISS1 promoter methylation,mRNA expression and protein expression were detected by methylation-specific polymerase chain reaction(PCR),real-time quantitative PCR and Western blotting,respectively,in 126 CRC tissues and 142 normal colorectal tissues.Human CRC cells with KISS1 promoter hypermethylation and poor KISS1 expression were treated in vitro with 5-aza-2’-deoxycytidine(5-Aza-CdR).After treatment,KISS1 promoter methylation,KISS1 mRNA and protein expression and cell migration and invasion were evaluated.RESULTS:Hypermethylation of KISS1 occurred frequently in CRC samples(83.1%,105/126),but was infrequent in normal colorectal tissues(6.34%,9/142).Moreover,KISS1 methylation was associated with tumor differentiation,the depth of invasion,lymph node metastasis and distant metastasis(P<0.001).KISS1methylation was also associated with low KISS1 expression(P<0.001).Furthermore,we observed re-expression of the KISS1 gene and decreased cell migration after 5-Aza-CdR treatment in a CRC cell line.CONCLUSION:These data suggest that KISS1 is down-regulated in cancer tissues via promoter hypermethylation and therefore may represent a candidate target for treating metastatic CRC.     

肝细胞肝癌谷胱甘肽硫转移酶P1甲基化研究

目的本研究探讨谷胱甘肽硫转移酶（GST）PI启动子CpG岛甲基化与肝细胞肝癌（HCC）的关系。方法用甲基化特异性PCR技术检测53例HCC肿瘤组织及其癌旁非肿瘤组织中，GSTP1基因启动子CpG岛甲基化状况。结果GSTP1基因在HCC肿瘤组织中的甲基化率显著高于癌旁非肿瘤组织（X^2=19．08，P〈0．001），在Ⅲ-Ⅳ期肿瘤中的甲基化率显著高于Ⅰ-Ⅱ期肿瘤（X^2=4．84，P=0．028），在不同大小的肿瘤之间、单个结节与多个结节的肿瘤之间以及包膜完整的肿瘤与包膜不完整的肿瘤之间甲基化率的差异均无显著性。结论GSTP1启动子CDG岛甲基化可能参与肝细胞的痛性转变。     

DNA methylation,microRNAs,and their crosstalk as potential biomarkers in hepatocellular carcinoma

Epigenetic alterations have been identified as a major characteristic in human cancers.Advances in the field of epigenetics have contributed significantly in refining our knowledge of molecular mechanisms underlying malignant transformation.DNA methylation and microRNA expression are epigenetic mechanisms that are widely altered in human cancers including hepatocellular carcinoma(HCC),the third leading cause of cancer related mortality worldwide.Both DNA methylation and microRNA expression patterns are regulated in developmental stage specific-,cell type specific-and tissue-specific manner.The aberrations are inferred in the maintenance of cancer stem cells and in clonal cell evolution during carcinogenesis.The availability of genome-wide technologies for DNA methylation and microRNA profiling has revolutionized the field of epigenetics and led to the discovery of a number of epigenetically silenced microRNAs in cancerous cells and primary tissues.Dysregulation of these microRNAs affects several key signalling pathways in hepatocarcinogenesis suggesting that modulation of DNA methylation and/or microRNA expression can serve as new therapeutic targets for HCC.Accumulative evidence shows that aberrant DNA methylation of certain microRNA genes is an event specifically found in HCC which correlates with unfavorable outcomes.Therefore,it can potentially serve as a biomarker for detection as well as for prognosis,monitoring and predicting therapeutic responses in HCC.     

Connexin 32 and 43 promoter methylation in Helicobacter pylori-associated gastric tumorigenesis

AIM: To explore the mechanism of abnormal Connexin (Cx) 32 and Cx43 expression in the gastric mucosa after Helicobacter pylori (H. pylori) infection.METHODS: Biopsy specimens of gastric mucosa in different gastric carcinogenesis stages with H. pylori infection, that is, non-atrophic gastritis (NAG; n = 24), chronic atrophic gastritis (CAG; n = 25), intestinal metaplasia (IM; n = 28), dysplasia (DYS; n = 24), and gastric cancer (GC; n = 30), as well as specimens of normal gastric mucosa without H. pylori infection (NGM; n = 25), were confirmed by endoscopy and pathological examination. Cx32 and Cx43 mRNA expression was detected by real-time polymerase chain reaction (PCR). Cx32 and Cx43 promoter CpG island methylation status was determined by methylation-specific PCR (MSP), bisulfite PCR sequencing (BSP) and MassArray methods.RESULTS: The relative mRNA expression levels in the gastric mucosa of patients with NGM, NAG, CAG, IM, DYS and GC were 0.146 ± 0.011, 0.133 ± 0.026, 0.107 ± 0.035, 0.039 ± 0.032, 0.037 ± 0.01 and 0.03 ± 0.011 for Cx32; and 0.667 ± 0.057, 0.644 ± 0.051, 0.624 ± 0.049, 0.555 ± 0.067, 0.536 ± 0.058 and 0.245 ± 0.121 for Cx43, respectively, which were gradually decreasing and significantly different (GC vs NGM: P < 0.001 for Cx32, P < 0.001 for Cx43). The promoter methylation levels in the gastric mucosa from NGM to GC stages by MSP were 38.8% ± 9.0%, 43.1% ± 9.4%, 56.5% ± 3.1%, 64.4% ± 9.7%, 72.5% ± 4.2% and 79.6% ± 6.8% for Cx32; and 49.0% ± 3.9%, 58.1% ± 5.0%, 66.5% ± 7.9%, 74.0% ± 8.8%, 78.3% ± 3.6% and 88.7% ± 6.2% for Cx43, respectively, which were gradually increasing and significantly different (P = 0.039, P = 0.019). The promoter methylation levels by BSP and MassArray exhibited similar trends. Cx32 and Cx43 mRNA expression was negatively correlated with promoter methylation status and gastric carcinogenesis stages (P < 0.001, P = 0.016).CONCLUSION: Cx32 and Cx43 mRNA expression decreased gradually during H. pylori infection-associated gastric carcinogenesis, and it is associated with hypermethylation of these genes’ promoter.     

Clostridium perfringens infection after transarterial chemoembolization for large hepatocellular carcinoma

We report an unusual case of Clostridium perfringens liver abscess formation after transcatheter arterialchemoembolization(TACE) for large hepatocellular carcinoma. Severe deterioration in liver and renal function accompanied with hemocytolysis was found on the 2nd day after TACE. Blood culture found Clostridium perfringens and abdominal computed tomography revealed a gas-containing abscess in the liver. Following antibiotics administration and support care, the infection was controlled and the liver and renal function turned normal. The 2nd TACE procedure was performed 1.5 mo later and no recurrent Clostridium perfringens infection was found.     

肝细胞肝癌谷胱甘肽硫转移酶P1基因型和表型及其活性研究

目的 探讨谷胱甘肽硫转移酶（GST）P1活性及基因多态、启动子甲基化与肝细胞肝癌（HCC）的关系.方法 紫外分光光度法检测HCC肿瘤细胞和癌旁肝细胞胞质中GSTP1活性,用甲基化特异性PCR技术检测GSTP1甲基化,PCR-RFLP技术检测53例HCC患者和74例健康人外周血基因组GSTP1基因多态性.结果 GSTP1三种基因型频率在病例组与对照组间差异无统计学意义（χ^2=0.84,v=2,P=0.656）.GSTP1甲基化率在肿瘤组织与癌旁组织间差异有统计学意义（χ^2=19.08,P＜0.01）,在Ⅲ～Ⅳ期肿瘤中的频率显著高于Ⅰ～Ⅱ期肿瘤（χ^2=4.84,P=0.028）.HCC肿瘤细胞胞质中GSTP1活性显著低于癌旁肝细胞（t=2.49,P=0.014）,Ⅰ～Ⅱ期肿瘤胞质中GSTP1活性显著高于Ⅲ～Ⅳ期肿瘤（t=2.31,P=0.025）,GSTP1甲基化的肿瘤细胞胞质中GSTP1活性显著低于未甲基化的肿瘤细胞（t=3.50,P=0.001）.结论 由GSTP1基因甲基化引起的GSTP1活性下降可能与肝细胞的癌性转变有关.     

MGMT and MLH1 methylation in Helicobacter pylori-infected children and adults

AIM:To evaluate the association between Helicobacter pylori(H.pylori) infection and MLH1 and MGMT methylation and its relationship with microsatellite instability(MSI).METHODS:The methylation status of the MLH1 and MGMT promoter region was analysed by methylation specific methylation-polymerase chain reaction(MSPPCR) in gastric biopsy samples from uninfected or H.pylori-infected children(n = 50),from adults with chronic gastritis(n = 97) and from adults with gastric cancer(n = 92).MLH1 and MGMT mRNA expression were measured by real-time PCR and normalised to a constitutive gene(β actin).MSI analysis was performed by screening MSI markers at 4 loci(Bat-25,Bat-26,D17S250 and D2S123) with PCR;PCR products were analysed by single strand conformation polymorphism followed by silver staining.Statistical analyses were performed with either the χ 2 test with Yates continuity correction or Fisher’s exact test,and statistical significance for expression analysis was assessed using an unpaired Student’s t-test.RESULTS:Methylation was not detected in the promoter regions of MLH1 and MGMT in gastric biopsy samples from children,regardless of H.pylori infection status.The MGMT promoter was methylated in 51% of chronic gastritis adult patients and was associated with H.pylori infection(P < 0.05);this region was methylated in 66% of gastric cancer patients,and the difference in the percentage of methylated samples between these patients and those from H.pylori-infected chronic gastritis patients was statistically significant(P < 0.05).MLH1 methylation frequencies among H.pylori-infected and non-infected chronic gastritis adult patients were 13% and 7%,respectively.We observed methylation of the MLH1 promoter(39%) and increased MSI levels(68%) in samples from gastric cancer patients in comparison to samples from H.pylori-infected adult chronic gastritis patients(P < 0.001 and P < 0.01,respectively).The frequency of promoter methylation for both genes was higher in gastric cancer samples than in H.pylori-positiv     

肝细胞肝癌谷胱甘肽硫转移酶P1活性和甲基化研究

与环境中致癌物黄曲霉毒素B1（AFB1）密切接触可增加肝细胞肝癌（HCC）的危险性。进入体内的AFB1在肝内经细胞色素P4501A2活化为AFB1-8.9环氧化物（前致癌物），在肝细胞胞浆中与谷胱甘肽S-转移酶（GST）携带的活性极团谷胱苷肽结合后，水溶性增加，     

A polymorphism within ErbB4 is associated with risk for hepatocellular carcinoma in Chinese population

AIM: To investigate the association between hepatocellular carcinoma (HCC) susceptibility and a 12-bp insertion/deletion polymorphism (rs6147150) in the 3’UTR of ErbB4.METHODS: Using a case-control design, the rs6147150 genotypes in 270 patients with HCC and 270 healthy controls were determined by direct polymerase chain reaction and polyacrylamide gel electrophoresis. Logistic regression was used to analyze the association between the polymorphism and cancer risk.RESULTS: Computational modeling suggested that rs6147150 was located in the seed region of hsa-let-7c, a potential target sequence in ErbB4 3’UTR. Logistic regression analysis showed that, compared with individuals homozygous for wild-type, heterozygotes [adjusted odds ratio (OR) = 1.48, 95% confidence interval (CI) = 1.03-2.17, P = 0.034] and individuals homozygous for 12-bp del/del (OR = 2.50, 95% CI = 1.37-4.56, P = 0.001) were at significantly higher risk of HCC. Carriers of the “del” allele of rs6147150 had a 1.59-fold increased risk for HCC (95% CI = 1.22-2.07, P = 0.003).CONCLUSION: rs6147150 may be associated with HCC risk, in part through let-7c-mediated regulation, and may be involved in the pathogenesis of HCC in Chinese populations.     

肝癌组织中ZHX2基因启动子甲基化及其与临床病理特征的关系

目的 运用变性高效液相色谱(Denature High-Performance Liquid Chromatography,DHPLC)法检测原发性肝癌细胞中ZHX2基因启动子甲基化的情况,为进一步探讨其与原发性肝细胞癌(HCC)临床病理特征之间的关系奠定基础.方法 采用亚硫酸氢钠-DHPLC技术,以体外甲基化的DNA和人类胎盘DNA分别为甲基化和非甲基化对照,建立ZHX2基因启动子甲基化DHPLC分析方法.在55℃部分变性条件下,对ZHX2基因启动子重要区域甲基化水平进行检测,并对24例HCC癌组织及癌旁肝组织和6例正常肝组织标本进行检测.结果 建立了ZHX2基因启动子甲基化DHPLC分析方法,使用该方法检测结果显示正常肝组织未检测到甲基化,24例HCC癌组织中有11例存在甲基化(45.8％),而24例HCC癌旁组织中有3例(16.6％)存在甲基化.结论 本研究建立了ZHX2基因启动子甲基化DHPLC分析方法,并首次将其应用于肝癌组织标本的检测,为深入探讨ZHX2基因与HCC发生发展之间关系奠定了基础.     

Interactions of chemical carcinogens and genetic variation in hepatocellular carcinoma

In the etiology of hepatocellular carcinoma (HCC), in addition to hepatitis B virus and hepatitis C virus infections, chemical carcinogens also play important roles. For example, aflatoxin B(1) (AFB(1)) epoxide reacts with guanine in DNA and can lead to genetic changes. In HCC, the tumor suppressor gene p53 codon 249 mutation is associated with AFB(1) exposure and mutations in the K-ras oncogene are related to vinyl chloride exposure. Numerous genetic alterations accumulate during the process of hepatocarcinogenesis. Chemical carcinogen DNA-adduct formation is the basis for these genetic changes and also a molecular marker which reflects exposure level and biological effects. Metabolism of chemical carcinogens, including their activation and detoxification, also plays a key role in chemical hepatocarcinogenesis. Cytochrome p450 enzymes, N-acetyltransferases and glutathione S-transferases are involved in activating and detoxifying chemical carcinogens. These enzymes are polymorphic and genetic variation influences biological response to chemical carcinogens. This genetic variation has been postulated to influence the variability in risk for HCC observed both within and across populations. Ongoing studies seek to fully understand the mechanisms by which genetic variation in response to chemical carcinogens impacts on HCC risk.     

Study on the association of Helicobacter species with viral hepatitis-induced hepatocellular carcinoma

Helicobacter species are important pathogens and previous studies in mice suggested a link between colonization by Helicobacter hepaticus (H. hepaticus) and hepatocellular carcinoma (HCC). This study aimed at corroborating this potential link in human patients. We used a sensitive and specific Helicobacter ssp PCR assay to screen stool samples from a collective of patients with viral-induced HCC (hepatitis B or hepatitis C) and a control group for presence of Helicobacter ssp DNA. Although retrieving DNA of H. pylori and H. canadensis from stool samples of non-HCC patients, we found no evidence indicating the presence of H. hepaticus in HCC-patients with chronic hepatitis B or hepatitis C. Interestingly we found H. canadensis in a stool sample of a patient presenting with diarrhea. Taken together, our data argue against a pathogenic role of H. hepaticus in viral-induced HCC. Yet, our results do not exclude a role of H. hepaticus in those HCC cases caused by other carcinogens, such as aflatoxin. Moreover, we speculate that H. canadensis might be a novel gastrointestinal pathogen.     

RASSF1A基因启动子区甲基化在贲门腺癌、食管下段鳞癌组织中的变化及临床意义

目的:比较RASSF1A基因甲基化在贲门腺癌、食管下段鳞癌不同病理阶段组织中的共性和差异.方法:33例贲门腺癌和36例食管下段鳞癌手术切除标本纳入本研究,每例标本选取癌组织,癌旁不典型增生组织(距癌3-5 cm),癌旁正常组织(距癌>5 cm)组织各1块,采用甲基化特异性PCR检测RASSF1A基因启动子区的甲基化情况...     

Hypermethylation of TGF-β1 gene promoter in gastric cancer

AIM:To examine transforming growth factor-β1(TGF-β1)promoter methylation in gastric cancer and to determine if Helicobacter pylori(H.pylori)or interleukin(IL)-1β could induce TGF-β1 hypermethylation in vitro.METHODS:We examined the frequency and extent of TGF-β1 promoter methylation using methylationspecific PCR in the gastric tissues from 47 gastric cancer patients and 39 non-gastric cancer subjects.H.pylori infection was confirmed by a positive result from either a serological test,histological analysis or C13urea breath test.GES-1 and MKN-45 cells co-cultured with H.pylori or treated with IL-1β for 12,24 and 48 h in vitro tested the effects of H.pylori or IL-1β on TGF-1β.RESULTS:Twenty-four/forty-seven(51%)cases of gastric cancer(GC)tissues showed TGF-β1 promoter methylation,15/47(31.9%)cases of matched noncancerous gastric mucosa tissues from the GC patients,and 11/39(28%)case of the normal gastric mucosa tissues from non-GC subjects showed TGF-β1 promoter methylation(51%vs 28%,P<0.05).Significantly higher levels of methylation of TGF-β1 were found in the tumor tissues than in non-tumor tissues from GC patients(0.24±0.06 vs 0.17±0.04,P<0.05)and normal gastric tissues from non-GC subjects(0.24±0.06 vs 0.15±0.03,P<0.05).TGF-β1 methylation was found in 48.3% of H.pylori-positive gastric mucosal tissues whereas only 23.1% of H.pylori-negative gastric mucosal tissues showed TGF-β1 methylation(48.3%vs 23.1%,P<0.05).IL-1β appeared to induce a dose-dependent methylation of TGF-β1 and the strongest methylation was observed in GES-1 cells treated with 2.5 ng/mL of IL-1β for 48 h.Further studies showed that pre-treatment of GES-1 cells with 20ng/mL IL-1RA for 1 h could partially abolish the effect of IL-1β on TGF-β1 methylation.Infection of GES-1cells by H.pylori was not found to induce significant TGF-β1 promoter methylation.CONCLUSION:Our data revealed that TGF-1 promoter is methylated in GC patients.IL-1β may be an important mediator for H.pylori induced gene methylation during GC