SFRP2 methylation in fecal DNA—a marker for colorectal polyps

Introduction DNA methylation of secreted frizzled-related proteins (SFRPs) can be detected in colorectal cancer (CRC) tissue, in tissue of adenomas, and in aberrant crypt foci, whereas in normal colorectal mucosa tissue, SFRP genes are unmethylated. Recently, our study group was able to demonstrate SFRP2 methylation as the most sensitive single DNA-based marker in stool for identification of CRC. The purpose of this study was to clarify whether SFRP2 methylation in fecal DNA can be found in stool of individuals with hyperplastic and adenomatous colorectal polyps. Materials and methods Patients who were diagnosed with colorectal polyps or showed negative colonoscopy were included in this study. DNA from stool samples was isolated. SFRP2 methylation was assessed by means of MethyLight. Results Stool samples from 68 individuals were checked for DNA content; 23% of the samples (6 of 26) from healthy controls, 46% of the samples (6 of 13) from patients with hyperplastic polyps, and 45% of the samples (13 of 29) from patients with adenomas were positive for human DNA. SFRP2 methylation in stool samples was found in none of the healthy controls, in 33% (2 of 6) patients with hyperplastic polyps, and in 46% (6 of 13) patients with adenomas. Statistical analysis revealed that the frequency of SFRP2 methylation increased significantly (P = 0.028) from healthy controls to patients with hyperplastic polyps and to patients with adenomas. Conclusions In the current study, we report for the first time that SFRP2 methylation in fecal DNA increases significantly from healthy controls to patients with hyperplastic polyps and to patients with adenomas. SFRP2 methylation may serve as a marker for molecular stool-based adenoma and CRC screening.     

Detection of aberrant methylation in fecal DNA as a molecular screening tool for colorectal cancer and precancerous lesions

AIM: To investigate the feasibility of detecting methylated fecal DNA as a screening tool for colorectal carcinoma (CRC) and precancerous lesions. METHODS: Methylated secreted frizzled-related protein gene 2 (SFRP2 ), hyperplastic polyposis protein gene (HPP1 ) and O6-methylguanine-DNA methyltransferase gene (MGMT) in stools from 52 patients with CRC, 35 patients with benign colorectal diseases and 24 normal individuals were analyzed using methylation-specific PCR. RESULTS: Methylated SFRP2, HPP1 and MGMT were detected in 94.2%, 71.2%, 48.1% of CRC patients and 52.4%, 57.1%, 28.6% of adenoma patients, respectively. The overall prevalence of fecal DNA with at least one methylated gene was 96.2% and 81.8% in patients with CRC and precancerous lesions, respectively. In contrast, only one of the 24 normal individuals revealed methylated DNA. These results indicated a 93.7% sensitivity and a 77.1% specificity of the assay for detecting CRC and precancerous lesions. CONCLUSION: Methylation testing of fecal DNA using a panel of epigenetic markers may be a simple and promising non-invasive screening method for CRC and precancerous lesions.     

人粪便SFRP2基因甲基化分析对结直肠癌的诊断价值

目的探讨人粪便中分泌型卷曲相关蛋白2(SFRP2)基因甲基化分析用于结直肠癌(CRC)早期诊断的可行性。方法从87例结直肠癌或良性病变的患者及24例正常对照者的粪便中分别提取DNA,采用甲基化特异性PCR(MSP)技术分析其SFRP2基因甲基化状态。结果CRC、腺瘤、增生性息肉和溃疡性结肠炎患者的SFRP2基因甲基化阳性率分别为94.2%(49/52)、52.4%(11/21)、37.5%(3/8)和16.7%(1/6)。1例正常对照SFRP2基因甲基化检测阳性。检测SFRP2基因甲基化诊断CRC及癌前病变的敏感性和特异性分别为90.5%和85.4%。结论SFRP2基因甲基化是CRC进展过程中的早期事件。粪便SFRP2基因甲基化分析可望成为CRC早期无创诊断或CRC高风险人群筛查的新途径。     

Hypermethylated SFRP2 gene in fecal DNA is a high potential biomarker for colorectal cancer noninvasive screening

AIM： To investigate the feasibility of detecting hypermethylated secreted frizzled-related protein 2 （SFRP2） gene in fecal DNA as a non-invasive screening tool for colorectal cancer （CRC）. METHODS： Fluorescence-based real-time PCR assay （MethyLight） was performed to analyze SFRP2 gene promoter methylation status in a blinded fashion in tumor tissues and in stool samples taken from 69 CRC patients preoperatively and at the 9th postoperative day, 34 patients with adenoma ≥1 cm, 26 with hyperplastic polyp, and 30 endoscopically normal subjects. Simultaneously the relationship between hypermethylation of SFRP2 gene and clinicopathological features was analyzed. RESULTS： SFRP2 gene was hypermethylated in 91.3% （63/69） CRC, 79.4% （27/34） and 53.8% （14/26） adenoma and hyperplastic polyp tissues, and in 87.0% （60/69）, 61.8% （21/34） and 42.3% （11/26） of corresponding fecal samples, respectively. In contrast, no methylated SFRP2 gene was detected in mucosal tissues of normal controls, while two cases of matched fecal samples from normal controls were detected with hypermethylated SFRP2. A significant decrease （P 〈 0.001） in the rate of hypermethylated SFRP2 gene was detected in the postoperative （8.7%, 6/69） fecal samples as compared with the preoperative fecal samples （87%, 60/69） of CRC patients. Moreover, no significant associations were observed between SFRP2 hypermethylation and clinicopathological features including sex, age, tumor stage, site, lymph node status and histological grade, etc.CONCLUSION： Hypermethylation of SFRP2 gene in fecal DNA is a novel molecular biomarker of CRC and carries a high potential for the remote detection of CRC and premalignant lesions as noninvasive screening method.     

Accuracy of early detection of colorectal tumours by stool methylation markers: A meta-analysis

AIM: To evaluate the accuracy of methylation of genes in stool samples for diagnosing colorectal tumours.METHODS: Electronic databases including PubMed, Web of Science, Chinese Journals Full-Text Database and Wanfang Journals Full-Text Database were searched to find relevant original articles about methylated genes to be used in diagnosing colorectal tumours. A quality assessment of diagnostic accuracy studies tool (QADAS) was used to evaluate the quality of the included articles, and the Meta-disc 1.4 and SPSS 13.0 software programs were used for data analysis.RESULTS: Thirty-seven articles met the inclusion criteria, and 4484 patients were included. The sensitivity and specificity for the detection of colorectal cancer (CRC) were 73% (95%CI: 71%-75%) and 92% (95%CI: 90%-93%), respectively. For adenoma, the sensitivity and specificity were 51% (95%CI: 47%-54%) and 92% (95%CI: 90%-93%), respectively. Pooled diagnostic performance of SFRP2 methylation for CRC provided the following results: the sensitivity was 79% (95%CI: 75%-82%), the specificity was 93% (95%CI: 90%-96%), the diagnostic OR was 47.57 (95%CI: 20.08-112.72), the area under the curve was 0.9565. Additionally, the results of accuracy of SFRP2 methylation for detecting colorectal adenomas were as follows: sensitivity was 43% (95%CI: 38%-49%), specificity was 94% (95%CI: 91%-97%), the diagnostic OR was 11.06 (95%CI: 5.77-21.18), and the area under the curve was 0.9563.CONCLUSION: Stool-based DNA testing may be useful for noninvasively diagnosing colorectal tumours and SFRP2 methylation is a promising marker that has great potential in early CRC diagnosis.     

Combined detection of plasma GATA5 and SFRP2 methylation is a valid noninvasive biomarker for colorectal cancer and adenomas

AIM:To investigate GATA5,SFRP2,and ITGA4 methylation in plasma DNA as noninvasive biomarkers for colorectal cancer(CRC) or adenomas.METHODS:There were 57 CRC patients,30 adenomas patients,and 47 control patients enrolled in this study.Methylation-specific polymerase chain reaction was used to determine the promoter methylation status of GATA5,SFRP2,and ITGA4 genes in plasma DNA,and their association with clinical outcome in CRC.The predictive ability of GATA5,SFRP2,and ITGA4 methylation,individually or in combination,to detect CRC or adenomas was further analyzed.RESULTS:Hypermethylated GATA5 was detected in plasma in 61.4%(35/57) of CRC cases,43.33%(13/30) of adenoma cases,and 21.28%(10/47) of control cases.The hypermethylation of SFRP2 was detected in 54.39%(31/57),40.00%(12/30),and 27.66%(13/47) in plasma samples from CRC,adenomas,and controls,respectively.ITGA4 methylation was detected in 36.84%(21/57) of plasma samples of CRC patients and in 30.00%(9/30) of plasma samples from patients with colorectal adenomas,and the specificity of this individual biomarker was 80.85%(9/47).Moreover,GATA5 methylation in the plasma was significantly correlated with larger tumor size(P =0.019),differentiation status(P =0.038),TNM stage(P =0.008),and lymph node metastasis(P =0.008).SFRP2 and ITGA4 methylation in plasma significantly correlated with differentiation status(SFRP2,P =0.012; ITGA4,P =0.007),TNM stage(SFRP2,P =0.034; ITGA4,P =0.021),and lymph node metastasis(SFRP2,P =0.034; ITGA4,P =0.021).From the perspective of predictive power and cost-performance,using GATA5 and SFRP2 together as methylation markers seemed the most favorable predictor for CRC(OR =8.06;95%CI:2.54-25.5; P < 0.01) and adenomas(OR =3.35; 95%CI:1.29-8.71; P =0.012).CONCLUSION:A combination of GATA5 and SFRP2 methylation could be promising as a marker for the detection and diagnosis of CRC and adenomas.     

粪便基因甲基化分析对大肠癌的早期诊断价值

目的探讨人粪便中分泌型卷曲相关蛋白(SFRP2)及增生性息肉蛋白(HPP1)基因甲基化分析对患者大肠癌诊断的价值。方法从30例结直肠癌患者、30例结直肠腺瘤患者及30例正常对照者的粪便中分别提取DNA,采用甲基化特异性PCR(MSP)技术分析其SFRP2及HPP1基因甲基化状态。结果大肠癌、腺瘤和正常对照组的SFRP2基因甲基化阳性率分别为66.6%(20/30)、50.0%(15/30)和3.3%(1/30)。大肠癌、腺瘤和正常对照组的HPP1基因甲基化阳性率分别63.3%(19/30)、43.3%(13/30)和6.6%(2/30)。结论 SFRP2和HPP1基因甲基化是大肠癌进展过程中的早期事件。粪便SFRP2和HPP1基因甲基化分析可望成为大肠癌早期无创诊断的新途径。     

粪便DNA中MGMT、XAF1基因启动子甲基化联合检测在结直肠癌筛查中的应用研究

目的使用甲基化特异性PCR(MSP)方法检测粪便DNA中O6-甲基鸟嘌呤-DNA甲基转移酶(MGMT)、X染色体连锁凋亡抑制蛋白相关因子1(XAF1)基因启动子甲基化情况,并探讨其在结直肠肿瘤诊断中的意义。方法收集40例结直肠腺癌、40例腺瘤性息肉、52例正常对照住院患者粪便标本,使用试剂盒提取其粪便中肠道脱离细胞DNA,通过MSP方法检测其MGMT、XAF1基因启动子甲基化情况。结果 MGMT、XAF1基因启动子甲基化在结直肠腺癌中的阳性率分别为50.0%、55.9%;在腺瘤性息肉中的阳性率分别为42.1%、52.6%;二者联合检测在结直肠腺癌及腺瘤性息肉中的阳性率分别为73.5%、68.4%;特异性为52.0%。结直肠腺癌患者粪便中粪便潜血阳性率为35.3%,CEA阳性率为35.3%。结论通过试剂盒提取粪便DNA具有较高成功率;粪便DNA中MGMT、XAF1基因启动子甲基化状态用于检测结直肠腺癌及腺瘤性息肉具有较高的敏感性。检测粪便基因甲基化有望成为CRC高风险人群筛查的一个重要途径。     

Field Cancerization in Sporadic Colon Cancer

Background/AimsAberrant DNA methylation has a specific role in field cancerization. Certain molecular markers, including secreted frizzled-related protein 2 (SFRP2), tissue factor pathway inhibitor 2 (TFPI2), N-Myc downstream-regulated gene 4 (NDRG4) and bone morphogenic protein 3 (BMP3), have previously been shown to be hypermethylated in colorectal cancer (CRC). We aim to examine field cancerization in CRC based on the presence of aberrant DNA methylation in normal-appearing tissue from CRC patients.MethodsWe investigated promoter methylation in 34 CRC patients and five individuals with normal colonoscopy results. CRC patients were divided into three tissue groups: tumor tissue, adjacent and nonadjacent normal-appearing tissue. The methylation status (positive: methylation level >20%) of SFRP2, TFPI2, NDRG4, and BMP3 promoters was investigated using methylation-specific PCR.ResultsThe methylation frequencies of the SFRP2, TFPI2, NDRG4 and BMP3 promoters in tumor/adjacent/nonadjacent normal-appearing tissue were 79.4%/63.0%/70.4%, 82.4%/53.6%/60.7%, 76.5%/61.5%/69.2%, 41.2%/35.7%/50.0%, respectively. The methylation levels of the SFRP,TFPI2, NDRG4 and BMP3 promoters in tumor tissues were significantly higher than those in normal-appearing tissue (SFRP2, p=0.013; TFPI2, p<0.001; NDRG4, p=0.003; BMP3, p=0.001). No significant correlation was observed between the methylation levels of the promoters and the clinicopathological variables.ConclusionsThe field effect is present in CRC and affects both the adjacent and nonadjacent normal-appearing mucosa.     

Analysis of promoter methylation in stool: a novel method for the detection of colorectal cancer.

BACKGROUND & AIMS: Detection of tumor-derived DNA alterations in stool is an intriguing new approach with high potential for the noninvasive detection of colorectal cancer (CRC). Because of heterogeneity of tumors, usually multiple markers distributed throughout the human genome need to be analyzed. This is labor intensive and does not allow for high through-put screening. Therefore, markers with high sensitivity and good specificity are needed. We explored the potential of a single epigenetic marker in comparison with fecal occult blood testing (FOBT) for the discrimination of patients with CRCs and adenomas from those without. METHODS: Methylation-specific polymerase chain reaction (PCR) was performed to analyze hypermethylated in cancer 1 (HIC1) promoter methylation status in a blinded fashion in stool samples from 26 patients with CRC, 13 with adenoma > or =1 cm, 9 with hyperplastic polyps, 9 with chronic inflammatory bowel disease, and 32 with endoscopically normal colon. RESULTS: Ninety-seven percent of the stool samples contained amplifiable DNA. Forty-two percent of the samples from patients with CRC and 31% of the samples from patients with colorectal adenoma > or =1 cm were positive for HIC1 promoter methylation. No methylated HIC1 promoter DNA was detected in the fecal DNA from patients with endoscopically normal colon or hyperplastic polyps. CONCLUSIONS: The epigenetic marker HIC1 promoter methylation carries high potential for the remote detection of CRCs. We postulate that a panel of merely a few genetic and epigenetic markers will be required for the highly sensitive and specific detection of CRCs and adenomas in fecal samples from affected patients.     

Aberrant methylation of <Emphasis Type="Italic">SOCS-1</Emphasis> was observed in younger colorectal cancer patients

Background Recently, it was demonstrated that suppressor of cytokine signaling-1 (SOCS-1) was frequently silenced by methylation of its CpG island in human hepatocellular carcinoma (HCC). To define the role of SOCS-1 in the tumorigenic pathway of the colorectum, we examined the methylation of SOCS-1 in tumors of colorectal cancer patients.Methods We examined 74 colorectal cancer patients, using a methylation-specific polymerase chain reaction (PCR; MSP) for SOCS-1 CpG island in primary tumors.Results Aberrant methylation of the SOCS-1 CpG island was detected in 6 of the 74 (8%) colorectal cancer specimens. No corresponding normal colorectal tissues showed SOCS-1 methylation. We then analyzed the correlation between the clinicopathological features and SOCS-1 aberrant methylation and found that younger age was significantly related to SOCS-1 methylation (P = 0.048).Conclusions These findings suggested that SOCS-1 may act as a tumor suppressor in at least some colorectal cancers and that SOCS-1 methylation may be a particular phenomenon related to an early onset of colorectal cancer.     

Impact of MTHFR gene C677T polymorphism on Bcl-2 gene methylation and protein expression in colorectal cancer

Abstract

Objective. To investigate the impact of MTHFR C677T polymorphism on Bcl-2 gene promoter CpG island (CGI) methylation and Bcl-2 protein expression. Material and methods. MTHFR polymorphisms of 86 sporadic colorectal cancer (CRC) patients and 100 healthy volunteers were analyzed by PCR-based restriction fragment length polymorphism, and Bcl-2 promoter CGI methylation in 86 CRC tissues and 86 paired nonneoplastic adjacent tissues was determined by methylation-specific PCR. Bcl-2 oncoprotein expression in 70 CRC tissues and paired nonneoplastic adjacent tissues was detected by immunohistochemistry. Results. The frequency of MTHFR 677 T allele and combined variant genotypes (677CT + TT) in CRC patients was significantly higher than that in healthy controls (p = 0.023 and p = 0.035, respectively), and there is a significant association between 677TT or 677(CT + TT) genotypes and CRC (OR = 2.534, p = 0.045 and OR = 1.888, p = 0.035, respectively). The frequency of methylated Bcl-2 promoter CGI in tumor tissues was significantly lower than that in nonneoplastic adjacent tissues (p = 0.014). The frequency of methylated Bcl-2 promoter CGI in CRC tissues of the individuals with CC genotype was significantly higher than that of those with CT/TT genotypes (p = 0.018), there was significant distribution difference of C and T alleles between individuals with methylated and unmethylated Bcl-2 promoter CGI in colorectal cancer tissues (p = 0.023). Bcl-2 promoter hypomethylation was significantly correlated with Bcl-2 oncoprotein expression in colorectal cancer tissues (r = 0.558, p < 0.001). Conclusion. Bcl-2 promoter is hypomethylated in colorectal cancer tissue, and there is a significant correlation between MTHFR 677 TT or CT/TT genotypes and CRC or Bcl-2 promoter CGI methylation/oncoprotein expression in CRC.     

Multi-target stool DNA test in the surveillance of inflammatory bowel disease: a cross-sectional cohort study

Background and aim: Colonoscopic surveillance is recommended in patients with longstanding inflammatory bowel disease (IBD) as they are at increased risk of colorectal cancer (CRC). Non-invasive surveillance may improve compliance and access. Multi-target stool DNA (MT-sDNA) has been validated for screening of sporadic CRC but has not been assessed in IBD. Our aim was to assess the performance of a MT-sDNA test in a real-life surveillance setting of patients with longstanding IBD.

Material and methods: A total of 192 IBD patients enrolled from two prospective cohorts submitted an EDTA buffered stool sample and underwent chromo- or white light colonoscopy. Stools were assayed for methylated BMP3 &; NDRG4, mutant KRAS and β-actin by a laboratory blinded to clinical data.

Results: The multitarget-sDNA panel was positive in 2/2 CRC and 5/15 low-grade dysplasia (LGD)?Conclusion: The MT-sDNA panel detected CRC in IBD. Sensitivity for sub-centimeter colorectal neoplasms in IBD patients appears similar to that observed in the general population. The test may be a valuable tool for detection of malignancy during structured surveillance of long-term IBD in a first line hospital setting.     

Detection of promoter hypermethylation of Wnt antagonist genes in fecal samples for diagnosis of early colorectal cancer

AIM: To investigate the feasibility of detecting aberrantly hypermethylated Wnt-antagonist gene promoters (SFRP2 and WIF-1) in fecal DNA as non-invasive biomarkers for early colorectal cancer (CRC).METHODS: The methylation-specific polymerase chain reaction assay was performed to blindly analyze the methylation status of SFRP2 and WIF-1 gene promoters in fecal samples from 48 subjects with CRC, 35 with adenomas, 32 with hyperplastic polyps and 30 endoscopically normal subjects. Additionally, we compared the diagnostic efficiency of measuring the hypermethylated SFRP2 and WIF-1 genes in the feces to the fecal occult blood test (FOBT) for the early detection of CRC.RESULTS: Hypermethylated SFRP2 was detected in the feces of 56.3% (27/48) of CRC cases, 51.4% (18/35) of adenoma cases and 12.5% (4/32) of patients with hyperplastic polyps. The hypermethylation of WIF-1 was detected in 60.4% (29/48), 45.7% (16/35) and 18.7% (6/32) of fecal samples from CRC, adenoma and hyperplastic polyp patients, respectively. At least one hypermethylated gene was detected in 81.3% (39/48) of CRC and 65.7% (23/35) of adenoma samples. In contrast, only a hypermethylated WIF-1 gene was detected in one case of normal fecal samples. Moreover, no significant associations were observed between SFPR2 and WIF-1 hypermethylation and clinicopathological features. Additionally, 81.8% of CRC cases diagnosed as Dukes A stage or advanced adenomas had at least one hypermethylated gene detected, while the detection rate with the FOBT was only 31.8% (P < 0.001).CONCLUSION: Hypermethylated SFRP2 and WIF-1 genes in fecal DNA are novel and promising molecular biomarkers that have great diagnostic potential for early CRC.     

Quantitative profiling of CpG island methylation in human stool for colorectal cancer detection

Purpose

The aims of this study were to investigate the use of quantitative CGI methylation data from stool DNA to classify colon cancer patients and to relate stool CGI methylation levels to those found in corresponding tissue samples.

Methods

We applied a quantitative methylation-specific PCR assay to determine CGI methylation levels of six genes, previously shown to be aberrantly methylated during colorectal carcinogenesis. Assays were performed on DNA from biopsies of “normal” mucosa and stool samples from 57 patients classified as disease-free, adenoma, or cancer by endoscopy, and in tumour tissue from cancer patients. Additionally, CGI methylation was analysed in stool DNA from an asymptomatic population of individuals covering a broad age range (mean?=?47?±?24 years)

Results

CGI methylation levels in stool DNA were significantly higher than in DNA from macroscopically normal mucosa, and a significant correlation between stool and mucosa was observed for ESR1 only. Multivariate statistical analyses using the methylation levels of each CGI in stool DNA as a continuous variable revealed a highly significant (p?=?0.003) classification of cancer vs. non-cancer (adenoma + disease-free) patients (sensitivity?=?65 %, specificity?=?81 %).

Conclusion

CGI methylation profiling of stool DNA successfully identified patients with cancer despite the methylation status of CGIs in stool DNA not generally reflecting those in DNA from the colonic mucosa.     

Stool-based DNA testing, a new noninvasive method for colorectal cancer screening, the first report from Iran

AIM:To detect tumor-associated DNA changes in stool samples among Iranian patients with colorectal cancer(CRC)compared to healthy individuals using BAT-26,p16 hypermethylation and long DNA markers.METHODS:Stool DNA was isolated from 45 subjects including 25 CRC patients and 20 healthy individuals using a new,fast and easy extraction method.Long DNA associated with tumor was detected using polymerase chain reaction method.Microsatellite studies were performed utilizing denaturating polyacrylamide gel to determine the instability of BAT-26.Methylation status of p16 promoter was analyzed using methylation-specific PCR(MSP).RESULTS:The results showed a significant difference in existence of long DNA(16 in patients vs 1 in controls,P < 0.001)and p16(5 in patients vs none in controls,P = 0.043)in the stool samples of two groups.Long DNA was detected in 64% of CRC patients;whereas just one of the healthy individuals was positive for Long DNA.p16 methylation was found in 20% of patients and in none of healthy individuals.Instability of BAT-26 was not detected in any of stool samples.CONCLUSION:We could detect colorectal cancer related genetic alterations by analyzing stool DNA witha sensitivity of 64% and 20% and a specificity of 95% and 100% for Long DNA and p16 respectively.A non-invasive molecular stool-based DNA testing can provide a screening strategy in high-risk individuals.However,additional testing on more samples is necessary from Iranian subjects to determine the exact specificity and sensitivity of these markers.     

Aberrant Methylation of HLTF, SOCS-1, and CDH13 Genes Is Shown in Colorectal Cancers Without Lymph Node Metastasis

PURPOSE and METHODS In this study, we examined the combined methylation status of HLTF, SOCS-1, and CDH13 in 61 resected primary colorectal cancers using methylation-specific polymerase chain reaction and correlated the number of methylated genes with the clinicopathologic features of affected patients.RESULTS We found a significant difference in lymph node metastasis (P = 0.020) when we compared the number of methylated genes in colorectal cancers with lymph node metastasis to those without it.CONCLUSIONS Colorectal cancers without lymph node metastasis frequently exhibited the aberrant methylation of HLTF , SOCS-1 , and CDH13 genes.     

Novel <Emphasis Type="Italic">hMSH</Emphasis>2, <Emphasis Type="Italic">hMSH</Emphasis>6 and <Emphasis Type="Italic">hMLH</Emphasis>1 gene mutations and microsatellite instability in sporadic colorectal cancer

Purpose To detect the hMSH2, hMSH6 and hMLH1 DNA mismatch repair gene mutations and microsatellite instability in somatic colorectal cancer.Patients and methods The mutations of hMSH2, hMSH6, and hMLH1 genes, including microsatellite instability of BAT-26, BAT-40, D2S123, D5S346 and D17S250 were analyzed in 31 patients with colorectal.Results The results revealed that eight cases (25.8%) harbored mutations in DNA mismatch repair genes. Of these, five novel mutations including I237V in exon 4 of hMSH2, ins T at codon 1196 in exon 7 of hMSH6, and ins G at codon 154 in exon 6, N158H in exon 6, and del A at codon 257 in exon 9 of hMLH1 were identified. Moreover, several intronic polymorphisms, including c–g transversion at IVS-1 nt211 + 9 of hMSH2, del T in poly T track at IVS-6 nt3559-5, ATCT duplicate in IVS-7 nt 3642 + 35 and t–g transversion at IVS-10 nt4080 + 185 of hMSH6 were demonstrated in these patients. In addition, seven cases (22.5%) exhibited microsatellite instability (MSI).Conclusion These results suggested that the inactivation of DNA mismatch repair genes and microsatellite instability may play a minor role in somatic colorectal cancer development.     

Detection of hypermethylated DNA or cyclooxygenase-2 messenger RNA in fecal samples of patients with colorectal cancer or polyps

BACKGROUND: Detection of fecal DNA is a promising approach to colorectal cancer screening. However, the sensitivity of current fecal DNA tests for colorectal polyps is low. We evaluated the feasibility of detecting aberrantly methylated DNA or cyclooxygenase-2 (COX-2) mRNA in feces of patients with colorectal cancer or polyps. METHODS: Fecal samples were collected prior to colonoscopy from 20 patients with colorectal cancer, 30 patients with colorectal polyps, and 30 subjects with normal colonic examination. Presence of hypermethylated DNA in 7 tumor-related genes (APC, ATM, hMLH1, sFRP2, HLTF, MGMT, and GSTP1) in stool was analyzed by methylation-specific PCR. COX-2 mRNA in fecal samples was detected by RT-PCR. RESULTS: With the use of this panel of methylation markers, the sensitivity of detecting colorectal cancer and adenoma was 75% (95% CI 50.9-91.3%) and 68% (95% CI 46.5-85.1%), respectively. Three normal subjects also had methylated DNA detected in stool, which gives a specificity of 90% (95% CI 73.5-97.9%). The mean number of genes methylated in DNA from the stool of patients with colorectal cancer and adenoma was 1.4 and 0.9, respectively. In contrast, COX-2 mRNA was detected in the stool samples of 10 (50%) cancer patients and one (4%) patient with advanced adenoma only. Two (6.7%) stool samples from normal subjects also had COX-2 mRNA detected. CONCLUSION: Detection of aberrantly methylated DNA in fecal samples is more sensitive than COX-2 mRNA for detection of colorectal cancer and adenoma.     

DNA Stool Test for Colorectal Cancer: Hypermethylation of the Secreted Frizzled-Related Protein-1 Gene

Purpose To investigate a potential mode of noninvasive screening for colorectal cancer, we evaluated the hypermethylation of the secreted frizzled-related protein-1 gene promoter in human stool DNA. Methods In stool samples from 36 patients with colorectal neoplasia (7 adenoma, 29 colorectal cancer) and 17 healthy control subjects, isolated DNA was treated with sodium bisulfite and analyzed by methylation-specific polymerase chain reaction with primers specific for methylated or unmethylated promoter sequences of the secreted frizzled-related protein-1 gene. Results Hypermethylation of the secreted frizzled-related protein-1 promoter was present in the stool DNA of patients with adenoma and colorectal cancer. A sensitivity of 89 percent and specificity of 86 percent were achieved in the detection of colorectal neoplasia. The difference in hypermethylation status of the secreted frizzled-related protein-1 promoter between the patients with colorectal neoplasia and the control group was statistically highly significant (P < 0.001). Adenoma and early tumor Stage I (International Union Against Cancer) displayed both unmethylated and methylated secreted frizzled-related protein-1 promoter sequences, whereas advanced tumor stages showed only methylated secreted frizzled-related protein-1 (P = 0.05). Conclusions The results indicate that this DNA stool test of hypermethylation of the secreted frizzled-related protein-1 promoter is a sensitive and specific method. It has the potential of a clinically useful test for the early detection of colorectal cancer. Supported by grants of the Funds for Research and Teaching (Elan-Fonds to W. Zhang) and by the Interdisciplinary Centre of Clinical Research (IZKF, Project A1 to M. Stürzl) of the University of Erlangen-Nuremberg, Germany. Presented at the Research Forum of The American Society of Colon and Rectal Surgeons, Seattle, Washington, June 3 to 7, 2006.