DNA methylation biomarkers for blood-based colorectal cancer screening

Circulating Tumor DNA as Biomarkers for Cancer Detection

Detection of circulating tumor DNAs (ctDNAs) in cancer patients is an important component of cancer precision medicine ctDNAs. Compared to the traditional physical and biochemical methods, blood-based ctDNA detection offers a non-invasive and easily accessible way for cancer diagnosis, prognostic determination, and guidance for treatment. While studies on this topic are currently underway, clinical translation of ctDNA detection in various types of cancers has been attracting much attention, due to the great potential of ctDNA as blood-based biomarkers for early diagnosis and treatment of cancers. ctDNAs are detected and tracked primarily based on tumor-related genetic and epigenetic alterations. In this article, we reviewed the available studies on ctDNA detection and described the representative methods. We also discussed the current understanding of ctDNAs in cancer patients and their availability as potential biomarkers for clinical purposes. Considering the progress made and challenges involved in accurate detection of specific cell-free nucleic acids, ctDNAs hold promise to serve as biomarkers for cancer patients, and further validation is needed prior to their broad clinical use.

Circulating tumor cells and circulating tumor DNA: What surgical oncologists need to know?

As a result of recent progress in detection techniques, circulating tumor DNA (ctDNA) and circulating tumor cells (CTC) can now be accurately detected in the blood of most cancer patients. While these new biomarkers can provide a better understanding of key biological mechanisms underlying cancer growth and dissemination, they also open up a wide range of possible clinical applications in medical oncology, radiation oncology and surgical oncology. In this review, we summarize the results obtained with ctDNA and CTC together with their potential future clinical applications in the field of surgical oncology, with particular focus on the perioperative setting of various types of cancer. These applications include, but are not limited to, cancer screening, early diagnosis, prognostic assessment, evaluation and management of preoperative systemic or local therapies, post-surgical detection of minimal residual disease and early detection of cancer relapse.

Sensitive and Noninvasive Detection of Aberrant SFRP2 and MGMT-B Methylation in Iranian Patients with Colon Polyps

BACKGROUND

The pathogenesis of sporadic colorectal cancer (CRC) is influenced by the patient genetic background and environmental factors. Based on prior understanding, these are classified in two major pathways of genetic instability. Microsatellite instability (MSI) and CPG island methylator phenotype (CIMP) are categorized as features of the hypermethylated prototype, and chromosomal instability (CIN) is known to be indicative of the non-hypermethylated category. Secreted frizzled related protein 2 (SFRP2), APC1A in WNT signaling pathway and the DNA repair gene, O6-methylguanine-DNA methyltransferase (MGMT), are frequently hypermethylated in colorectal cancer. Detection of methylated DNA as a biomarker by easy and inexpensive methods might improve the quality of life of patients with CRC via early detection of cancer or a precancerous condition.

AIM

To evaluate the rate of SFRP2 and MGMT hypermethylation in both polyp tissue and serum of patients in south Iran as compared with matched control normal population corresponding samples.

MATERIALS AND METHODS

Methylation-specific PCR was used to detect hypermethylation in DNA extracted from 48 polypoid tissue samples and 25 healthy individuals.

RESULTS

Of total polyp samples, 89.5% had at least one promoter gene hypermethylation. The most frequent methylated locus was SFRP2 followed by MGMT-B (81.2 and 66.6 percent respectively). Serologic detection of hypermethylation was 95% sensitive as compared with polyp tissue. No hypermethylation was detected in normal tissue and serum and its detection in patients with polyps, especially of serrated type, was specific.

CONCLUSIONS

Serologic investigation for detection of MGMT-B, SFRP2 hypermethylation could facilitate prioritization of high risk patients for colonoscopic polyp detection and excision.

Diagnostic Accuracy of Methylated SEPT9 for Blood-based Colorectal Cancer Detection: A Systematic Review and Meta-Analysis

Objectives:

More convenient and effective blood-based methods are believed to increase colorectal cancer (CRC) detection adoption. The effectiveness of methylated SPET9 for CRC detection has been reviewed in the newly published recommendation statement by US Preventive Services Task Force (USPSTF), while detailed instructions were not provided, which may be a result of insufficient evidence. Therefore, more evidence is needed to assist practitioners to thoroughly understand the utilization of this special maker.

Methods:

Based on the standard method, a systematic review and meta-analysis was performed. Quadas-2 was used to assess the methodological quality of studies. Relevant studies were searched and screened from PubMed, Embase and other literature databases up to June 1, 2016. Pooled sensitivity, specificity and diagnostic odds ratio were summarized by bivariate mixed effect model and area under the curve (AUC) was estimated by hierarchical summary receiver operator characteristic curve.

Results:

25 studies were included for analysis. The pooled sensitivity, specificity and AUC were 0.71, 0.92 and 0.88, respectively. Among the various methods and assays, Epipro Colon 2.0 with 2/3 algorithm was the most effective in colorectal cancer detection. Positive ratio of mSEPT9 was higher in advanced CRC (45% in I, 70% in II, 76% in III, 79% in IV) and lower differentiation (31% in high, 73% in moderate, 90% in low) tissue. However, this marker has poor ability of identifying precancerous lesions according to current evidence.

Conclusions:

mSEPT9 is a reliable blood-based marker in CRC detection, particularly advanced CRC. Epipro Colon 2.0 with 2/3 algorithm is currently the optimal method and assay to detect CRC.

The Relationship between the Methylated Septin-9 DNA Blood Test and Stool Occult Blood Test for Diagnosing Colorectal Cancer in Taiwanese People

BACKGROUND

Colorectal cancer (CRC) is a common and lethal disease in the world. There is an increasing number of cases in Taiwan and a higher rate at advanced stages. The immune fecal occult blood test (iFOBT) has been used as a screening method in Taiwan for years. A new novel diagnostic tool, the Methylated Septin-9 (MS-9) DNA blood test, had been reported to have high sensitivity and specificity for CRC detection. There are no available data in Taiwan, so we conducted this prospective randomized trial to investigate the relationship among the MS-9 DNA blood test, iFOBT, and a combination of the two tests for diagnosing CRC in Taiwanese people.

METHODS

From July 1, 2012 to December 31, 2013, we prospectively selected 60 plasma samples from patients who were diagnosed with CRC and otherwise, the healthy group by colonoscopy in our hospital. Patients were divided into the CRC group and healthy group. CRC stages 0, I, II and stages III and IV were separately analyzed. We calculated the sensitivity and specificity of each group to determine the relationship among the MS-9 DNA blood test, iFOBT, and a combination of the two tests for diagnosing CRC in Taiwanese people.

RESULTS

The results of the MS-9 DNA blood test for the 60 samples were divided into three groups, and the sensitivity as well as the specificity of the MS-9 DNA blood test to detect CRC were 47% and 89%, respectively. The results of iFOBT were also divided into three groups, and had higher sensitivity (84%) but lower specificity (55%) using iFOBT to detect CRC. Higher rates could be predicted to detect CRC if both the tests were positive.

CONCLUSIONS

A combined MS-9 DNA blood test and iFOBT may help in a higher detection rate of CRC. It could be offered to individuals who are unwilling or unable to undergo colonoscopy. Further large prospective, randomized studies are needed in the future.

Promoter hypermethylation of SHOX2 and SEPT9 is a potential biomarker for minimally invasive diagnosis in adenocarcinomas of the biliary tract

BACKGROUND

Biliary tract carcinoma (BTC) is a fatal malignancy which aggressiveness contrasts sharply with its relatively mild and late clinical presentation. Novel molecular markers for early diagnosis and precise treatment are urgently needed. The purpose of this study was to evaluate the diagnostic and prognostic value of promoter hypermethylation of the SHOX2 and SEPT9 gene loci in BTC.

METHODS

Relative DNA methylation of SHOX2 and SEPT9 was quantified in tumor specimens and matched normal adjacent tissue (NAT) from 71 BTC patients, as well as in plasma samples from an independent prospective cohort of 20 cholangiocarcinoma patients and 100 control patients. Receiver operating characteristic (ROC) curve analyses were performed to probe the diagnostic ability of both methylation markers. DNA methylation was correlated to clinicopathological data and to overall survival.

RESULTS

SHOX2 methylation was significantly higher in tumor tissue than in NAT irrespective of tumor localization (p < 0.001) and correctly identified 71% of BTC specimens with 100% specificity (AUC = 0.918; 95% CI 0.865-0.971). SEPT9 hypermethylation was significantly more frequent in gallbladder carcinomas compared to cholangiocarcinomas (p = 0.01) and was associated with large primary tumors (p = 0.01) as well as age (p = 0.03). Cox proportional hazard analysis confirmed microscopic residual tumor at the surgical margin (R1-resection) as an independent prognostic factor, while SHOX2 and SEPT9 methylation showed no correlation with overall survival. Elevated DNA methylation levels were also found in plasma derived from cholangiocarcinoma patients. SHOX2 and SEPT9 methylation as a marker panel achieved a sensitivity of 45% and a specificity of 99% in differentiating between samples from patients with and without cholangiocarcinoma (AUC = 0.752; 95% CI 0.631-0.873).

CONCLUSIONS

SHOX2 and SEPT9 are frequently methylated in biliary tract cancers. Promoter hypermethylation of SHOX2 and SEPT9 may therefore serve as a minimally invasive biomarker supporting diagnosis finding and therapy monitoring in clinical specimens.

Methylation of Septin9 mediated by DNMT3a enhances hepatic stellate cells activation and liver fibrogenesis

Liver fibrosis, resulting from chronic and persistent injury to the liver, is a worldwide health problem. Advanced liver fibrosis results in cirrhosis, liver failure and even hepatocellular cancer (HCC), often eventually requiring liver transplantation, poses a huge health burden on the global community. However, the specific pathogenesis of liver fibrosis remains not fully understood. Numerous basic and clinical studies have provided evidence that epigenetic modifications, especially DNA methylation, might contribute to the activation of hepatic stellate cells (HSCs), the pivotal cell type responsible for the fibrous scar in liver. Here, reduced representation bisulfite sequencing (RRBS) and bisulfite pyrosequencing PCR (BSP) analysis identified hypermethylation status of Septin9 (Sept9) gene in liver fibrogenesis. Sept9 protein was dramatically decreased in livers of CCl4-treated mice and immortalized HSC-T6 cells exposed to TGF-β1. Nevertheless, the suppression of Sept9 could be blocked by DNMT3a-siRNA and DNA methyltransferase inhibitor, 5-aza-2'-deoxycytidine (5-azadC). Overexpressed Sept9 attenuated TGF-β1-induced expression of myofibroblast markers α-SMA and Col1a1, accompanied by up-regulation of cell apoptosis-related proteins. Conversely, RNAi-mediated silencing of Sept9 enhanced accumulation of extracellular matrix. These observations suggested that Sept9 contributed to alleviate liver fibrosis might partially through promoting activated HSCs apoptosis and this anti-fibrogenesis effect might be blocked by DNMT-3a mediated methylation of Sept9. Therefore, pharmacological agents that inhibit Sept9 methylation and increase its expression could be considered as valuable treatments for liver fibrosis.

Integrating Epigenomics into the Understanding of Biomedical Insight

Epigenetics is one of the most rapidly expanding fields in biomedical research, and the popularity of the high-throughput next-generation sequencing (NGS) highlights the accelerating speed of epigenomics discovery over the past decade. Epigenetics studies the heritable phenotypes resulting from chromatin changes but without alteration on DNA sequence. Epigenetic factors and their interactive network regulate almost all of the fundamental biological procedures, and incorrect epigenetic information may lead to complex diseases. A comprehensive understanding of epigenetic mechanisms, their interactions, and alterations in health and diseases genome widely has become a priority in biological research. Bioinformatics is expected to make a remarkable contribution for this purpose, especially in processing and interpreting the large-scale NGS datasets. In this review, we introduce the epigenetics pioneering achievements in health status and complex diseases; next, we give a systematic review of the epigenomics data generation, summarize public resources and integrative analysis approaches, and finally outline the challenges and future directions in computational epigenomics.

Algorithm Optimization in Methylation Detection with Multiple RT-qPCR

Epigenetic markers based on differential methylation of DNA sequences are used in cancer screening and diagnostics. Detection of abnormal methylation at specific loci by real-time quantitative polymerase chain reaction (RT-qPCR) has been developed to enable high-throughput cancer screening. For tests that combine the results of multiple PCR replicates into a single reportable result, both individual PCR cutoff and weighting of the individual PCR result are essential to test outcome. In this opportunistic screening study, we tested samples from 1133 patients using the triplicate Epi proColon assay with various algorithms and compared it with the newly developed single replicate SensiColon assay that measures methylation status of the same SEPT9 gene sequence. The Epi proColon test approved by the US FDA (1/3 algorithm) showed the highest sensitivity (82.4%) at a lower specificity (82.0%) compared with the Epi proColon 2.0 CE version with 2/3 algorithm (75.1% sensitivity, 97.1% specificity) or 1/1 algorithm (71.3% sensitivity, 92.7% specificity). No significant difference in performance was found between the Epi proColon 2.0 CE and the SensiColon assays. The choice of algorithm must depend on specific test usage, including screening and early detection. These considerations allow one to choose the optimal algorithm to maximize the test performance. We hope this study can help to optimize the methylation detection in cancer screening and early detection.

Current noninvasive tests for colorectal cancer screening: An overview of colorectal cancer screening tests

Colorectal cancer (CRC) has become the third most common cancer in the world. Screening has been shown to be an effective way to identify early CRC and precancerous lesions, and to reduce its morbidity and mortality. Several types of noninvasive tests have been developed for CRC screening, including the fecal occult blood test (FOBT), the fecal immunochemical test (FIT), the fecal-based DNA test and the blood-based DNA test (the SEPT9 assay). FIT has replaced FOBT and become the major screening test due to high sensitivity, specificity and low costs. The fecal DNA test exhibited higher sensitivity than FIT but its current cost is high for a screening assay. The SEPT9 assay showed good compliance while its performance in screening needs further improvements. These tests exhibited distinct sensitivity and specificity in screening for CRC and adenoma. This article will focus on the performance of the current noninvasive in vitro diagnostic tests that have been used for CRC screening. The merits and drawbacks for these screening methods will also be compared regarding the techniques, usage and costs. We hope this review can provide suggestions for both the public and clinicians in choosing the appropriate method for CRC screening.

Use of NCCN Guidelines, Other Guidelines, and Biomarkers for Colorectal Cancer Screening

Colorectal cancer (CRC) remains a common cancer and significant public health burden. CRC-related mortality is declining, partly due to the early detection of CRC through robust screening. NCCN has established the NCCN Guidelines for CRC Screening to help healthcare providers make appropriate screening recommendations according to the patient's risk of developing CRC. This review describes the evolution of CRC screening guidelines for average-risk individuals, discusses the role of NCCN Guidelines for CRC Screening in cancer prevention, and comments on the current and emerging use of biomarkers for CRC screening.

Diagnostic Value of Methylated Septin9 for Colorectal Cancer Screening: A Meta-Analysis

Background

Septin9 is a member of GTP-binding protein family, and is used as a predictive diagnostic index. However, it has not been widely adopted due to inconsistent results reported in the literature. The present study was performed to determine the diagnostic accuracy of methylated Septin9 (mSEPT9) for colorectal cancer (CRC) and to evaluate its utility in CRC screening.

Material/Methods

After reviewing relevant studies, accuracy measures (pooled sensitivity and specificity, positive/negative likelihood ratio [PLR/NLR], and diagnostic odds ratio [DOR]) were calculated for mSEPT9 in the diagnosis of CRC. Overall test performance was summarized using summary receiver operating characteristic curve analysis. Potential between-study heterogeneity was explored by use of a meta-regression model. We divided included studies into Epi proColon test and non-Epi proColon test subgroups. We compared the effects of mSEPT9 and fecal occult blood test (FOBT) for CRC screening.

Results

A total of 9870 subjects in 14 studies were recruited. Pooled sensitivity and specificity, PLR, NLR, DOR, and corresponding 95% confidence intervals (CI) of mSEPT9 for CRC diagnosis were 0.66 (95% CI: 0.64–0.69), 0.91 (95% CI: 0.90–0.91), 5.59 (95% CI: 4.03–7.74), 0.37 (95% CI: 0.29–0.48), and 16.79 (95% CI: 10.54–26.76), respectively. The area under the summary ROC curve (AUC) was 0.8563. The AUCs in the Epi proColon test and non-Epi proColon test for CRC diagnosis were 0.8709 and 0.7968, respectively. In head-to-head comparison, AUC of mSEPT9 and FOBT for CRC diagnosis were 0.7857 and 0.6571, respectively.

Conclusions

The present study demonstrates that mSEPT9 can be a good diagnostic biomarker complementary to FOBT as a screening tool for CRC.

SEPT9 and SHOX2 DNA methylation status and its utility in the diagnosis of colonic adenomas and colorectal adenocarcinomas

Background

Colorectal cancer (CRC) appear to arise from precursor lesions in a well-characterized adenoma-carcinoma sequence. Significant efforts have been invested to develop biomarkers that identify early adenocarcinomas and adenomas with high-grade dysplasia, since these are believed to harbor a particularly high risk for malignant transition and thus require resection. Promoter methylation of SEPT9 and SHOX2 has been suggested as a biomarker for various solid malignant tumors. Hence, the present study aimed to test their biomarker potential in CRC and precursor lesions.

Results

Assessment of promoter methylation of SEPT9 distinguished adenomas and CRC from controls as well as advanced from non-advanced adenomas (all p < 0.001). Correspondingly, SHOX2 methylation levels in adenomas and colorectal carcinomas were significantly higher compared to those in normal control tissues (p < 0.001). Histologic transition from adenomas to CRC was paralleled by amplification of the SEPT9 gene locus.

Conclusions

SEPT9/SHOX2 methylation assays may help to distinguish colorectal cancer and adenomas from normal and inflammatory colonic tissue, as well as advanced from non-advanced adenomas. Further studies need to validate these findings before introduction in clinical routine.

[Liquid biopsy analysis using cell-free DNA (cfDNA): Opportunities and limitations]

Molecular biological analysis of nucleic acids in blood or other bodily fluids (i.e. liquid biopsy analyses) may supplement the pathologists' diagnostic armamentarium in a reasonable way-particularly in cancer precision medicine. Within the field of oncology, liquid biopsy can potentially be used to monitor tumor burden in the blood and to early detect emerging resistance in the course of targeted cancer therapies. An already approved application of liquid biopsy is the detection of epidermal growth factor receptor (EGFR) driver mutations in blood samples of lung cancer patients in those cases where no tissue biopsy is available. However, there is still currently considerable insecurity associated with blood-based DNA analytic methods that must be solved before liquid biopsy can be implemented for broader routine application in the diagnosis of cancer. In this article, the current state of development of liquid biopsy in molecular diagnostics from a pathology point of view is presented.

Molecular Detection of Gastrointestinal Neoplasia: Innovations in Early Detection and Screening

Emerging molecular tools promise to extend the diagnostic reach of the endoscopist and open doors to population screening for gastrointestinal (GI) cancers. This review briefly addresses biological considerations in marker detection and types of markers, highlights examples of tools under development at each organ site, and appraises the possibility of universal GI cancer screening. The outlook is positive, but further technical refinement and rigorous clinical validation are needed before most of these new approaches are ready for clinical application.

Methylation of the SEPT9_v2 promoter as a novel marker for the detection of circulating tumor DNA in breast cancer patients

The aim of the present study was to evaluate the promoter methylation status of SEPT9_v2 in breast cancer and to detect this methylated gene in circulating tumor DNA (ctDNA) in plasma. Bisulfite sequencing was performed with a next generation sequencer. Methylation of the SEPT9_v2 promoter was found in 67% (8/12) of breast cancer cell lines and 53% (10/19) of breast tumor tissue, but not in normal breast tissue (0/19). A clear inverse correlation was observed between the expression of SEPT9_v2 mRNA and the methylation index (MI) both in cell lines and breast cancer tissues. The MI of SEPT9_v2 was significantly higher in non-basal subtype of breast cancer (13.0%, n=84) than in basal subtype (3.0%, n=23) (P<0.0001). Methylated SEPT9_v2 ctDNA in plasma was detected in 11% (9/82) of primary breast cancer patients and 52% (26/50) of metastatic breast cancer patients, but not in the healthy controls (0/51). These results indicate that SEPT9_v2 promoter hypermethylation, which silences the expression of SEPT9_v2 mRNA, is observed in a significant proportion of breast tumors, and that methylated SEPT9_v2 may serve as a novel tumor marker for breast cancer.

Emerging stool-based and blood-based non-invasive DNA tests for colorectal cancer screening: the importance of cancer prevention in addition to cancer detection

Colorectal cancer (CRC) screening can be undertaken utilizing a variety of distinct approaches, which provides both opportunities and confusion. Traditionally, there has often been a trade-off between the degree of invasiveness of a screening test and its ability to prevent cancer, with fecal occult blood testing (FOBT) and optical colonoscopy (OC) at each end of the spectrum. CT colonography (CTC), although currently underutilized for CRC screening, represents an exception since it is only minimally invasive, yet provides accurate evaluation for advanced adenomas. More recently, the FDA approved a multi-target stool DNA test (Cologuard) and a blood-based test (Epi proColon) for average-risk CRC screening. This commentary will provide an overview of these two new non-invasive tests, including the clinical indications, mechanism of action, and diagnostic performance. Relevance to radiology practice, including a comparison with CTC, will also be discussed.

Extraction and Purification of DNA from Complex Biological Sample Matrices Using Solid-Phase Microextraction Coupled with Real-Time PCR

The determination of extremely small quantities of DNA from complex biological sample matrices represents a significant bottleneck in nucleic acid analysis. In this study, polymeric ionic liquid (PIL)-based solid-phase microextraction (SPME) was applied for the extraction and purification of DNA from crude bacterial cell lysate with subsequent quantification by real-time PCR (qPCR) analysis. Using an on-fiber ultraviolet initiated polymerization technique, eight different PIL sorbent coatings were generated and their DNA extraction performance evaluated using qPCR. The PIL sorbent coating featuring halide anions and carboxylic acid groups in the cationic portion exhibited superior DNA extraction capabilities when compared to the other studied PILs and a commercial polyacrylate SPME fiber. Electrostatic interactions as well as an ion-exchange mechanism were identified as the driving forces in DNA extraction by the PIL sorbents. The selectivity of the PIL sorbent coating for DNA was demonstrated in the presence of PCR inhibitors at high concentration, where a quantifiable amount of template DNA was extracted from aqueous samples containing CaCl2 and FeCl3. Furthermore, the PIL-based SPME method was successfully applied for the extraction of DNA from crude bacterial cell lysate spiked with 1 pg mL(-1) template DNA without requiring the use of organic solvents or centrifugation steps. Following PIL-based SPME of DNA from a dilute cell lysate, the qPCR amplification efficiency was determined to be 100.3%, demonstrating the feasibility of the developed method to extract high purity DNA from complex sample matrices.

Hypermethylated tumor suppressor genes as potential biomarkers in colorectal cancer

Colorectal cancer is a common malignant tumor and the fourth cause of cancer related death in the world. Colorectal cancer is a consequence of the accumulation of multiple genetic and epigenetic changes that transform colon epithelial cells into invasive malignant adenoma. Epigenetic changes, especially CpG island methylation in the promoter region, occur more frequently than genetic mutations in colorectal cancer. Hypermethylation contributes to carcinogenesis by inducing transcriptional silencing or downregulation of tumor suppressor genes. Up to now, more than 600 hypermethylated gene candidates have been identified. The use of methylated tumor suppressor genes as minimally invasive biomarkers has broad prospects, and great progress has been made in this area. These biomarkers, either stool-based or blood-based, are now commercially available for diagnostics. However, hypermethylated tumor suppressor genes as prognostic and predictive markers are still at the primary stage of development.

Hypermethylated DNA as a biomarker for colorectal cancer: a systematic review

AIM

Improved methods for early detection of colorectal cancer (CRC) are essential for increasing survival. Hypermethylated DNA in blood or stool has been proposed as a biomarker for CRC. Biochemical methods have improved in recent years, and several hypermethylated genes that are sensitive and specific for CRC have been proposed. Articles describing the use of hypermethylated promoter regions in blood or stool as biomarkers for CRC were systematically reviewed.

METHOD

A systematic literature search was performed using the Medline, Web of Science and Embase databases. Studies were included if they analysed hypermethylated genes from stool or blood samples in correlation with CRC. Studies in languages other than English and those based on animal models or cell lines were excluded.

RESULTS

The literature search yielded 74 articles, including 43 addressing blood samples and 31 addressing stool samples. In blood samples, hypermethylated ALX4, FBN2, HLTF, P16, TMEFF1 and VIM were associated with poor prognosis, hypermethylated APC, NEUROG1, RASSF1A, RASSF2A, SDC2, SEPT9, TAC1 and THBD were detected in early stage CRC and hypermethylated P16 and TFPI2 were associated with CRC recurrence. In stool samples, hypermethylated BMP3, PHACTR3, SFRP2, SPG20, TFPI2 and TMEFF2 were associated with early stage CRC.

CONCLUSION

Hypermethylation of the promoters of specific genes measured in blood or stool samples could be used as a CRC biomarker and provide prognostic information. The majority of studies, however, include only a few patients with poorly defined control groups. Further studies are therefore needed before hypermethylated DNA can be widely applied as a clinical biomarker for CRC detection and prognosis.

Diagnostic Performance of DNA Hypermethylation Markers in Peripheral Blood for the Detection of Colorectal Cancer: A Meta-Analysis and Systematic Review

DNA hypermethylation in blood is becoming an attractive candidate marker for colorectal cancer (CRC) detection. To assess the diagnostic accuracy of blood hypermethylation markers for CRC in different clinical settings, we conducted a meta-analysis of published reports. Of 485 publications obtained in the initial literature search, 39 studies were included in the meta-analysis. Hypermethylation markers in peripheral blood showed a high degree of accuracy for the detection of CRC. The summary sensitivity was 0.62 [95% confidence interval (CI), 0.56-0.67] and specificity was 0.91 (95% CI, 0.89-0.93). Subgroup analysis showed significantly greater sensitivity for the methylated Septin 9 gene (SEPT9) subgroup (0.75; 95% CI, 0.67-0.81) than for the non-methylated SEPT9 subgroup (0.58; 95% CI, 0.52-0.64). Sensitivity and specificity were not affected significantly by target gene number, CRC staging, study region, or methylation analysis method. These findings show that hypermethylation markers in blood are highly sensitive and specific for CRC detection, with methylated SEPT9 being particularly robust. The diagnostic performance of hypermethylation markers, which have varied across different studies, can be improved by marker optimization. Future research should examine variation in diagnostic accuracy according to non-neoplastic factors.

Detection of Colorectal Cancer Using a Simplified SEPT9 Gene Methylation Assay Is a Reliable Method for Opportunistic Screening

SEPT9 gene methylation was validated as a biomarker for colorectal cancer (CRC) for >10 years and available as the Epi proColon test as an aid in CRC detection for >6 years. It was proven to be an accurate, reliable, fast, and convenient molecular test. In this opportunistic screening study, we validated a further simplified SEPT9 gene methylation assay in 1031 subjects in Chinese hospitals. The sensitivity for CRC detection was 76.6% at a specificity of 95.9%, and the results showed a satisfactory detection rate for each CRC stage, including early stages. The new SEPT9 assay, with enhanced technical simplicity, convenience, and lower cost, did not differ in performance compared with Epi proColon 2.0, the commercialized SEPT9 assay. The CRC detection sensitivity was further enhanced when the assay was combined with carcinoembryonic antigen (sensitivity, 86.4%) or fecal immunochemical test (sensitivity, 94.4%), suggesting that the combined tests may be an effective option for future opportunistic screening. In brief, our study has validated a new SEPT9 assay and combined testing as an aid in cancer detection, providing a new approach for opportunistic CRC screening.

Establishing the clinical utility of epigenetic markers in cancer: many challenges ahead

The use of epigenetic biomarkers in cancer management relies on the availability of robust assays and evidence that these markers are able to segregate clinically significant groups of patients. While many cancers are characterized by genetic and epigenetic modifications, it is far simpler to develop molecular tests that detect genetic rather than epigenetic changes. In this special report, we will describe the challenges associated with developing epigenetic assays and the practical issues that must be overcome before they can be used in the clinic.

DNA methylation patterns as noninvasive biomarkers and targets of epigenetic therapies in colorectal cancer

Aberrant DNA methylation is frequently detected in gastrointestinal tumors, and can therefore potentially be used to screen, diagnose, prognosticate, and predict colorectal cancers (CRCs). Although colonoscopic screening remains the gold standard for CRC screening, this procedure is invasive, expensive, and suffers from poor patient compliance. Methylated DNA is an attractive choice for a biomarker substrate because CRCs harbor hundreds of aberrantly methylated genes. Furthermore, abundance in extracellular environments and resistance to degradation and enrichment in serum, stool, and other noninvasive bodily fluids, allows quantitative measurements of methylated DNA biomarkers. This article describes the most important studies that investigated the efficacy of serum- or stool-derived methylated DNA as population-based screening biomarkers in CRC, details several mechanisms and factors that control DNA methylation, describes a better use of prevailing technologies that discover novel DNA methylation biomarkers, and illustrates the diversity of demethylating agents and their applicability toward clinical impact.

The concerted impact of domestication and transposon insertions on methylation patterns between dogs and grey wolves

The process of domestication can exert intense trait-targeted selection on genes and regulatory regions. Specifically, rapid shifts in the structure and sequence of genomic regulatory elements could provide an explanation for the extensive, and sometimes extreme, variation in phenotypic traits observed in domesticated species. Here, we explored methylation differences from >24 000 cytosines distributed across the genomes of the domesticated dog (Canis familiaris) and the grey wolf (Canis lupus). PCA and model-based cluster analyses identified two primary groups, domestic vs. wild canids. A scan for significantly differentially methylated sites (DMSs) revealed species-specific patterns at 68 sites after correcting for cell heterogeneity, with weak yet significant hypermethylation typical of purebred dogs when compared to wolves (59% and 58%, P < 0.05, respectively). Additionally, methylation patterns at eight genes significantly deviated from neutrality, with similar trends of hypermethylation in purebred dogs. The majority (>66%) of differentially methylated regions contained or were associated with repetitive elements, indicative of a genotype-mediated trend. However, DMSs were also often linked to functionally relevant genes (e.g. neurotransmitters). Finally, we utilized known genealogical relationships among Yellowstone wolves to survey transmission stability of methylation marks, from which we found a substantial fraction that demonstrated high heritability (both H(2) and h(2 ) > 0.99). These analyses provide a unique epigenetic insight into the molecular consequences of recent selection and radiation of our most ancient domesticated companion, the dog. These findings suggest selection has acted on methylation patterns, providing a new genomic perspective on phenotypic diversification in domesticated species.

A 2015 survey of established or potential epigenetic biomarkers for the accurate detection of human cancers

Context The silencing or activation of cancer-associated genes by epigenetic mechanisms can ultimately lead to the clonal expansion of cancer cells. Objective The aim of this review is to summarize all relevant epigenetic biomarkers that have been proposed to date for the diagnosis of some prevalent human cancers. Methods A Medline search for the terms epigenetic biomarkers, human cancers, DNA methylation, histone modifications and microRNAs was performed. Results One hundred fifty-seven relevant publications were found and reviewed. Conclusion To date, a significant number of potential epigenetic cancer biomarkers of human cancer have been investigated, and some have advanced to clinical implementation.

Diagnostic and prognostic value of SHOX2 and SEPT9 DNA methylation and cytology in benign, paramalignant, and malignant ascites

BACKGROUND

Cytology remains the gold standard for the detection of malignant cells in ascites. However, its sensitivity is limited. The aim of this study was to evaluate DNA methylation biomarkers for the differential diagnosis of benign (ascites in patients without malignancy), malignant (ascites in cancer patients directly caused by malignancy), and paramalignant (ascites in cancer patients caused by comorbidities but not by malignancy) ascites.

METHODS

A cohort of 283 patients (134 cancer patients, 149 patients with benign diseases) presenting with ascites was prospectively enrolled. Ascites was evaluated by means of cytopathological investigation and DNA methylation of SHOX2 and SEPT9 in the cell-free and cellular fraction. DNA methylation in bisulfite-converted DNA was determined using quantitative methylation specific real-time PCR. Cytopathological and DNA methylation results were evaluated with regard to diagnosis and overall survival (OS).

RESULTS

Patients with positive DNA methylation had a poor overall survival compared to methylation-negative patients (hazard ratio: HR = 1.97, p = 0.001). In multivariate survival analysis, DNA methylation was an independent prognostic parameter (p = 0.003) together with age (HR = 1.03, p < 0.001) and the presence of malignant disease (HR = 1.87, p < 0.001). The combination of methylation with cytopathological analyses led to a 42 % increase in the detection rate of malignant ascites, resulting in 37 % positively diagnosed cancer patients and a specificity of 97 %. Among cancer patients, patients with DNA methylation-positive ascites showed an adverse clinical course (HR = 1.63, p = 0.039).

CONCLUSIONS

DNA methylation testing adds diagnostic and prognostic information and might constitute an effective ancillary method for the differential diagnosis of malignant, paramalignant, and benign ascites.

Circulating cell-free nucleic acids as biomarkers in colorectal cancer screening and diagnosis

Screening methods for the most frequent diagnosed malignant tumor, colorectal cancer (CRC), have limitations. Circulating cell-free DNA (cfDNA) analysis came into focus as a potential screening test for CRC. Detection of epigenetic and genetic alterations of cfDNA as DNA methylation or DNA mutations and related ribonucleic acids may improve cancer detection based on unique, CRC-specific patterns. In this review the authors summarize the CRC-specific nucleic acid biomarkers measured in peripheral blood and their potential as screening markers. Detection of DNA mutation has inadequate sensitivity; however, methylated DNA can be established with higher sensitivity from CRC plasma samples. The ribonucleic acid based miRNA studies represented higher sensitivity for CRC as compared with mRNA studies. Recently, isolation of cfDNA has become automated, highly reproducible and a high throughput method. With automated possible diagnostic tools, a new approach may be available for CRC screening as liquid biopsy.

Aberrant DNA methylation profiles of inherited and sporadic colorectal cancer

Background

Aberrant DNA methylation has been widely investigated in sporadic colorectal carcinomas (CRCs), and extensive work has been performed to characterize different methylation profiles of CRC. Less information is available about the role of epigenetics in hereditary CRC and about the possible clinical use of epigenetic biomarkers in CRC, regardless of the etiopathogenesis. Long interspersed nucleotide element 1 (LINE-1) hypomethylation and gene-specific hypermethylation of 38 promoters were analyzed in multicenter series of 220 CRCs including 71 Lynch (Lynch colorectal cancer with microsatellite instability (LS-MSI)), 23 CRCs of patients under 40 years in which the main inherited CRC syndromes had been excluded (early-onset colorectal cancer with microsatellite stability (EO-MSS)), and 126 sporadic CRCs, comprising 28 cases with microsatellite instability (S-MSI) and 98 that were microsatellite stable (S-MSS). All tumor methylation patterns were integrated with clinico-pathological and genetic characteristics, namely chromosomal instability (CIN), TP53 loss, BRAF, and KRAS mutations.

Results

LS-MSI mainly showed absence of extensive DNA hypo- and hypermethylation. LINE-1 hypomethylation was observed in a subset of LS-MSI that were associated with the worse prognosis. Genetically, they commonly displayed G:A transition in the KRAS gene and absence of a CIN phenotype and of TP53 loss. S-MSI exhibited a specific epigenetic profile showing low rates of LINE-1 hypomethylation and extensive gene hypermethylation. S-MSI were mainly characterized by MLH1 methylation, BRAF mutation, and absence of a CIN phenotype and of TP53 loss. By contrast, S-MSS showed a high frequency of LINE-1 hypomethylation and of CIN, and they were associated with a worse prognosis. EO-MSS were a genetically and epigenetically heterogeneous group of CRCs. Like LS-MSI, some EO-MSS displayed low rates of DNA hypo- or hypermethylation and frequent G:A transitions in the KRAS gene, suggesting that a genetic syndrome might still be unrevealed in these patients. By contrast, some EO-MSS showed similar features to those observed in S-MSS, such as LINE-1 hypomethylation, CIN, and TP53 deletion. In all four classes, hypermethylation of ESR1, GATA5, and WT1 was very common.

Conclusions

Aberrant DNA methylation analysis allows the identification of different subsets of CRCs. This study confirms the potential utility of methylation tests for early detection of CRC and suggests that LINE-1 hypomethylation may be a useful prognostic marker in both sporadic and inherited CRCs.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-015-0165-2) contains supplementary material, which is available to authorized users.

Simultaneous Analysis of SEPT9 Promoter Methylation Status, Micronuclei Frequency, and Folate-Related Gene Polymorphisms: The Potential for a Novel Blood-Based Colorectal Cancer Biomarker

One challenge in colorectal cancer (CRC) is identifying novel biomarkers to be introduced in screening programs. The present study investigated the promoter methylation status of the SEPT9 gene in peripheral blood samples of subjects' positive fecal occult blood test (FOBT). In order to add new insights, we investigated the association between SEPT9 promoter methylation and micronuclei frequency, and polymorphisms in the folate-related pathway genes. SEPT9 promoter methylation, micronuclei frequency, and genotypes were evaluated on 74 individuals' FOBT positive. Individuals were subjected to a colonoscopy that provided written informed consent for study participation. SEPT9 promoter methylation status was significantly lower in the CRC group than controls (p = 0.0006). In contrast, the CaCo2 cell-line, analyzed as a tissue specific model of colon adenocarcinoma, showed a significantly higher percentage of SEPT9 promoter methylation compared to the CRC group (p < 0.0001). Linear regression analysis showed an inverse correlation between micronuclei frequency and the decrease in the methylation levels of SEPT9 promoter region among CRC patients (β = -0.926, p = 0.0001). With regard to genotype analysis, we showed the involvement of the DHFR polymorphism (rs70991108) in SEPT9 promoter methylation level in CRC patients only. In particular, the presence of at least one 19 bp del allele significantly correlates with decreased SEPT9 promoter methylation, compared to the 19 bp ins/ins genotype (p = 0.007). While remaining aware of the strengths and limitations of the study, this represents the first evidence of a novel approach for the early detection of CRC, using SEPT9 promoter methylation, micronuclei frequency and genotypes, with the potential to improve CRC risk assessment.

Noninvasive DNA methylation biomarkers in colorectal cancer: A systematic review

OBJECTIVE

To summarize the current evidence on the biomarkers associated with DNA methylation in the screening and diagnosis of colorectal cancer (CRC).

METHODS

A literature search was conducted on the databases of PubMed and Web of Science to identify articles published from 1 January 2000 to 6 June 2015 with language striction. Stuides focusing on the association between noninvasive biomarkers indicating DNA methylation and CRC were included.

RESULTS

Altogether 74 studies were finally included in the study. Varied genetic markers in the feces and blood samples were hypermethylated in patients with CRC than in the healthy controls. Some of them could even be detected at the early stage of the tumors. The sensitivity of the genetic markers was superior to that of fecal occult blood test and carcinoembryonic antigen. Multitarget DNA assays using a combination of different methylated genes could improve the diagnostic sensitivity.

CONCLUSIONS

Genetic markers might be minimally invasive, economical and accurate for the screening and surveillance of CRC. Large multicenter studies evaluating these biomarkers systematically and prospectively not only in CRC but also in other types of cancers are needed in the future.

Detecting hepatocellular carcinoma in blood

Liquid biopsy is ideal for early diagnosis of cancer and for prognosis upon treatment. Wen et al. describe a methylated CpG tandems amplification and sequencing method to profile hypermethylated CpG islands genome-widely in cell-free DNA, and further identify high performance markers in blood for potential detection of early stage hepatocellular carcinoma.

Notes for developing a molecular test for the full characterization of circulating tumor cells

The proved association between the circulating tumor cell (CTC) levels and the patients' survival parameters has been growing interest to investigate the molecular profile of these neoplastic cells among which hide out precursors capable of initiating a new distant metastatic lesion. The full characterization of the tumor cells in peripheral blood of cancer patients is expected to be of help for understanding and (prospectively) for counteracting the metastatic process. The major hitch that is hampering the successful gaining of this result is the lack of a consensus onto standard operating procedures (SOPs) for performing what we generally define as the "liquid biopsy". Here we review the more recent acquisitions in the analysis of CTCs and tumor related nucleic acids, looking to the main open questions that are hampering their definitive employ in the routine clinical practice.

Genome-scale detection of hypermethylated CpG islands in circulating cell-free DNA of hepatocellular carcinoma patients

Despite advances in DNA methylome analyses of cells and tissues, current techniques for genome-scale profiling of DNA methylation in circulating cell-free DNA (ccfDNA) remain limited. Here we describe a methylated CpG tandems amplification and sequencing (MCTA-Seq) method that can detect thousands of hypermethylated CpG islands simultaneously in ccfDNA. This highly sensitive technique can work with genomic DNA as little as 7.5 pg, which is equivalent to 2.5 copies of the haploid genome. We have analyzed a cohort of tissue and plasma samples (n = 151) of hepatocellular carcinoma (HCC) patients and control subjects, identifying dozens of high-performance markers in blood for detecting small HCC (≤ 3 cm). Among these markers, 4 (RGS10, ST8SIA6, RUNX2 and VIM) are mostly specific for cancer detection, while the other 15, classified as a novel set, are already hypermethylated in the normal liver tissues. Two corresponding classifiers have been established, combination of which achieves a sensitivity of 94% with a specificity of 89% for the plasma samples from HCC patients (n = 36) and control subjects including cirrhosis patients (n = 17) and normal individuals (n = 38). Notably, all 15 alpha-fetoprotein-negative HCC patients were successfully identified. Comparison between matched plasma and tissue samples indicates that both the cancer and noncancerous tissues contribute to elevation of the methylation markers in plasma. MCTA-Seq will facilitate the development of ccfDNA methylation biomarkers and contribute to the improvement of cancer detection in a clinical setting.

Performance of the colorectal cancer screening marker Sept9 is influenced by age, diabetes and arthritis: a nested case-control study

Background

Annually, colorectal cancer (CRC) is diagnosed in >1.4 million subjects worldwide and incidence is increasing. Much effort has therefore been focused on screening, which has proven to reduce cancer-related mortality. The Sept9 DNA-methylation assay is among the most well studied blood-based screening markers. However, earlier reported performances may be misleading: the Sept9 test was recently examined in two screening based cohorts and yielded performances lower than expected. We hypothesize that comorbidities and/or demographic characteristics affect the results of the Sept9 test.

Methods

Using a retrospective nested case–control study design, we studied plasma from 150 cancer and 150 controls selected from a well-characterized cohort of 4698 subjects referred for diagnostic colonoscopy due to CRC-related symptoms. The cases and controls were matched on age and gender, and moreover cases were stratified on tumor-site and tumor-stage. The selected cohort included a wide range of comorbidities. Plasma Sept9 levels were assessed using a commercially available PCR based assay (Epi-proColon).

Results

Clinical sensitivity for CRC stages I-IV was 37 %, 91 %, 77 %, and 89 %, and the overall sensitivity 73 % (95 % CI, 64–80 %) and specificity 82 % (95 % CI, 75–88 %), respectively. Age >65 was associated with both increased false positive and false negative results (p < 0.05). Arthritis was associated with a higher false negative rate (p = 0.005) whereas Arteriosclerosis was associated with a higher false positive rate (p = 0.007). Diabetes was associated with Sept9 positivity with an OR of 5.2 (95 % CI 1.4–19.1). When the performance of Sept9 was adjusted for these parameters in a final multivariate regression model, the OR for a positive Sept9 test to be associated with CRC increased from 8.25 (95 % CI 4.83–14.09) to 29.46 (95 % CI 12.58–69.02).

Conclusions

The results indicate that the performance of the Sept9 assay is negatively affected by several factors commonly associated with CRC screening populations: early-stage disease, age > 65 years, diabetes, arthritis, and arteriosclerosis. This should be taken into account if the Sept9 assay is used as a single marker for CRC screening, but may also have a wider impact, as it is likely that such factors may affect other blood based DNA markers as well.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1832-6) contains supplementary material, which is available to authorized users.

Value of DNA methylation markers in colorectal cancer screening

Colorectal cancer (CRC) is one of the most common malignant tumors in the world. Recognizing CRC at an early stage by population-based screening is crucial in the prevention and treatment of CRC. Numerous candidate genes, which play important roles in the development and progression of CRC, have been found to be hyper-methylated in the promoter regions in recent studies. The promoter fragments of those hyper-methylated genes in tumor tissues have also been detected in the blood and fecal specimens, with higher sensitivity and specificity than traditional markers in the screening of CRC, including carcino-embryonic antigen (CEA) and fecal occult blood test. Here, we will discuss what we have already known about the DNA methylation markers for CRC screening and the potential research direction in the future.

Evaluation of an assay for methylated BCAT1 and IKZF1 in plasma for detection of colorectal neoplasia

BACKGROUND

Specific genes, such as BCAT1 and IKZF1, are methylated with high frequency in colorectal cancer (CRC) tissue compared to normal colon tissue specimens. Such DNA may leak into blood and be present as cell-free circulating DNA. We have evaluated the accuracy of a novel blood test for these two markers across the spectrum of benign and neoplastic conditions encountered in the colon and rectum.

METHODS

Circulating DNA was extracted from plasma obtained from volunteers scheduled for colonoscopy for any reason, or for colonic surgery, at Australian and Dutch hospitals. The extracted DNA was bisulphite converted and analysed by methylation specific real-time quantitative PCR (qPCR). A specimen was deemed positive if one or more qPCR replicates were positive for either methylated BCAT1 or IKZF1 DNA. Sensitivity and specificity for CRC were estimated as the primary outcome measures.

RESULTS

Plasma samples were collected from 2105 enrolled volunteers (mean age 62 years, 54 % male), including 26 additional samples taken after surgical removal of cancers. The two-marker blood test was run successfully on 2127 samples. The test identified 85 of 129 CRC cases (sensitivity of 66 %, 95 % CI: 57-74). For CRC stages I-IV, respective positivity rates were 38 % (95 % CI: 21-58), 69 % (95 % CI: 53-82), 73 % (95 % CI: 56-85) and 94 % (95 % CI: 70-100). A positive trend was observed between positivity rate and degree of invasiveness. The colonic location of cancer did not influence assay positivity rates. Gender, age, smoking and family history were not significant predictors of marker positivity. Twelve methylation-positive cancer cases with paired pre- and post-surgery plasma showed reduction in methylation signal after surgery, with complete disappearance of signal in 10 subjects. Sensitivity for advanced adenoma (n = 338) was 6 % (95 % CI: 4-9). Specificity was 94 % (95 % CI: 92-95) in all 838 non-neoplastic pathology cases and 95 % (95 % CI: 92-97) in those with no colonic pathology detected (n = 450).

CONCLUSIONS

The sensitivity for cancer of this two-marker blood test justifies prospective evaluation in a true screening population relative to a proven screening test. Given the high rate of marker disappearance after cancer resection, this blood test might also be useful to monitor tumour recurrence.

TRIAL REGISTRATION

ACTRN12611000318987 .

Epigenetic Alterations in Colorectal Cancer: Emerging Biomarkers

Colorectal cancer (CRC) is a leading cause of cancer deaths worldwide. One of the fundamental processes driving the initiation and progression of CRC is the accumulation of a variety of genetic and epigenetic changes in colonic epithelial cells. Over the past decade, major advances have been made in our understanding of cancer epigenetics, particularly regarding aberrant DNA methylation, microRNA (miRNA) and noncoding RNA deregulation, and alterations in histone modification states. Assessment of the colon cancer "epigenome" has revealed that virtually all CRCs have aberrantly methylated genes and altered miRNA expression. The average CRC methylome has hundreds to thousands of abnormally methylated genes and dozens of altered miRNAs. As with gene mutations in the cancer genome, a subset of these epigenetic alterations, called driver events, are presumed to have a functional role in CRC. In addition, the advances in our understanding of epigenetic alterations in CRC have led to these alterations being developed as clinical biomarkers for diagnostic, prognostic, and therapeutic applications. Progress in this field suggests that these epigenetic alterations will be commonly used in the near future to direct the prevention and treatment of CRC.

Towards an understanding of the role of DNA methylation in rheumatoid arthritis: therapeutic and diagnostic implications

The term 'epigenetics' loosely describes DNA-templated processes leading to heritable changes in gene activity and expression, which are independent of the underlying DNA sequence. Epigenetic mechanisms comprise of post-translational modifications of chromatin, methylation of DNA, nucleosome positioning as well as expression of noncoding RNAs. Major advances in understanding the role of DNA methylation in regulating chromatin functions have been made over the past decade, and point to a role of this epigenetic mechanism in human disease. Rheumatoid arthritis (RA) is an autoimmune disorder where altered DNA methylation patterns have been identified in a number of different disease-relevant cell types. However, the contribution of DNA methylation changes to RA disease pathogenesis is at present poorly understood and in need of further investigation. Here we review the current knowledge regarding the role of DNA methylation in rheumatoid arthritis and indicate its potential therapeutic implications.

Alterations in DNA methylation corresponding with lung inflammation and as a biomarker for disease development after MWCNT exposure

Use of multi-walled carbon nanotubes (MWCNT) is growing which increases occupational exposures to these materials. Their toxic potential makes it important to have an in-depth understanding of the inflammation and disease that develops due to exposure. Epigenetics is one area of interest that has been quickly developing to assess disease processes due to its ability to change gene expression and thus the lung environment after exposure. In this study, promoter methylation of inflammatory genes (IFN-γ and TNF-α) was measured after MWCNT exposure using the pyrosequencing assay and found to correlate with initial cytokine production. In addition, methylation of a gene involved in tissue fibrosis (Thy-1) was also altered in a way that matched collagen deposition. In addition to using epigenetics to better understand disease processes, it has also been used as a biomarker of exposure and disease. In this study, global methylation was determined in the lung to ascertain whether MWCNT alter global methylation at the site of exposure and if those alterations coincide with disease development. Then, global methylation levels were determined in the blood to ascertain whether global methylation could be used as a biomarker of exposure in a more easily accessible tissue. Using the LuUminometric Methylation Assay (LUMA) and 5-Methylcytosine (5-mC) Quantification assay, we found that MWCNT lead to DNA hypomethylation in the lung and blood, which coincided with disease development. This study provides initial data showing that alterations in gene-specific methylation correspond with an inflammatory response to MWCNT exposure. In addition, global DNA methylation in the lung and blood coincides with MWCNT-induced disease development, suggesting its potential as a biomarker of both exposure and disease development.

Gene-gene interaction analysis identifies a new genetic risk factor for colorectal cancer

BACKGROUND

Adiponectin levels have been shown to be associated with colorectal cancer (CRC). Furthermore, a newly identified adiponectin receptor, T-cadherin, has been associated with plasma adiponectin levels. Therefore, we investigated the potential for a genetic association between T-cadherin and CRC risk.

RESULT

We conducted a case-control study using the Korean Cancer Prevention study-II cohort, which is composed of 325 CRC patients and 977 normal individuals. Study results revealed that rs3865188 in the 5' flanking region of the T-cadherin gene (CDH13) was significantly associated with CRC (p = 0.0474). The odds ratio (OR) for the TT genotype as compared to the TA + AA genotype was 1.577 (p = 0.0144). In addition, the interaction between CDH13 and the adiponectin gene (APN) for CRC risk was investigated using a logistic regression analysis. Among six APN single nucleotide polymorphisms (rs182052, rs17366568, rs2241767, rs3821799, rs3774261, and rs6773957), an interaction with the rs3865188 was found for four (rs2241767, rs3821799, rs3774261, and rs6773957). The group with combined genotypes of TT for rs3865188 and GG for rs377426 displayed the highest risk for CRC development as compared to those with the other genotype combinations. The OR for the TT/GG genotype as compared to the AA/AA genotype was 4.108 (p = 0.004). Furthermore, the plasma adiponectin level showed a correlation with the gene-gene interaction, and the group with the highest risk for CRC had the lowest adiponectin level (median, 4.8 μg/mL for the TT/GG genotype vs.7.835 μg/mL for the AA/AA genotype, p = 0.0017).

CONCLUSIONS

The present study identified a new genetic factor for CRC risk and an interaction between CDH13 and APN in CRC risk. These genetic factors may be useful for predicting CRC risk.

SEPT9: A Specific Circulating Biomarker for Colorectal Cancer

SEPT9 gene methylation has been implicated as a biomarker for colorectal cancer (CRC) for more than 10 years and has been used clinically for more than 6 years. Studies have proven it to be an accurate, reliable, fast, and convenient method for CRC. In this chapter, we will first provide the background on the role of septin9 protein and the theoretical basis of the SEPT9 gene methylation assay. We will then focus on the performance of SEPT9 gene methylation assay for CRC early detection and screening by analyzing the data obtained in clinical trials and comparing its performance with other methods or markers. Finally, we will discuss the future applications of the assay in monitoring cancer recurrence, evaluating surgery, chemotherapy, and predicting long-term survival. We hope this chapter can provide a full overview of the theoretical basis, development, validation, and clinical applications of the SEPT9 assay for both basic science researchers and clinical practitioners.

Strategies for validation and testing of DNA methylation biomarkers

DNA methylation is a stable covalent epigenetic modification of primarily CpG dinucleotides that has recently gained considerable attention for its use as a biomarker in different clinical settings, including disease diagnosis, prognosis and therapeutic response prediction. Although the advent of genome-wide DNA methylation profiling in primary disease tissue has provided a manifold resource for biomarker development, only a tiny fraction of DNA methylation-based assays have reached clinical testing. Here, we provide a critical overview of different analytical methods that are suitable for biomarker validation, including general study design considerations, which might help to streamline epigenetic marker development. Furthermore, we highlight some of the recent marker validation studies and established markers that are currently commercially available for assisting in clinical management of different cancers.

Detection of colorectal cancer by DNA methylation biomarker SEPT9: past, present and future

Colorectal cancer has become the third most common cancer in the world. Early diagnosis and treatment can significantly reduce colorectal cancer mortality. The current routinely used fecal-based screening methods do not provide satisfactory sensitivity. Although colonoscopy provides macroscopic diagnosis, the compliance is low due to its inconvenience and complications. Hence, the development of new screening methods is needed urgently. Peripheral blood SEPT9 gene methylation assay has become a potential option with promising future for early detection and screening of colorectal cancer. It is shown to be convenient, reliable with good compliance by several clinical trials. This article will review the theoretical foundation and development of the assay, focusing on its clinical trials, comparing it with other screening methods and discussing its future applications.

Improved amplification efficiency on stool samples by addition of spermidine and its use for non-invasive detection of colorectal cancer

Background

Using quantitative methylation-specific PCR (QM-MSP) is a promising method for colorectal cancer (CRC) diagnosis from stool samples. Difficulty in eliminating PCR inhibitors of this body fluid has been extensively reported. Here, spermidine is presented as PCR facilitator for the detection of stool DNA methylation biomarkers using QM-MSP. We examined its effectiveness with NPY, PENK and WIF1, three biomarkers which we have previously shown to be of relevance to CRC.

Results

We determined an optimal window for the amplification of the albumin (Alb) gene (100 ng of bisulfite-treated stool DNA added of 1 mM spermidine) at which we report that spermidine acts as a PCR facilitator (AE = 1680%) for SG RT-PCR. We show that the amplification of methylated PENK, NPY and WIF1 is considerably facilitated by QM-MSP as measured by an increase of CMI (Cumulative Methylation Index, i.e. the sum of the three methylation values) by a factor of 1.5 to 23 fold in individual samples, and of 10 fold in a pool of five samples.

Conclusions

We contend that spermidine greatly reduces the problems of PCR inhibition in stool samples. This observed feature, after validation on a larger sampling, could be used in the development of stool-based CRC diagnosis tests.

Electronic supplementary material

The online version of this article (doi:10.1186/s12896-015-0148-6) contains supplementary material, which is available to authorized users.

Colorectal Cancer Biomarkers: Where Are We Now?

Colorectal cancer is one of the major causes of cancer-related death in the Western world. Patient survival is highly dependent on the tumor stage at the time of diagnosis. Reduced sensitivity to chemotherapy is still a major obstacle in effective treatment of advanced disease. Due to the fact that colorectal cancer is mostly asymptomatic until it progresses to advanced stages, the implementation of screening programs aimed at early detection is essential to reduce incidence and mortality rates. Current screening and diagnostic methods range from semi-invasive procedures such as colonoscopy to noninvasive stool-based tests. The combination of the absence of symptoms, the semi-invasive nature of currently used methods, and the suboptimal accuracy of fecal blood tests results in colorectal cancer diagnosis at advanced stages in a significant number of individuals. Alterations in gene expression leading to colorectal carcinogenesis are reflected in dysregulated levels of nucleic acids and proteins, which can be used for the development of novel, minimally invasive molecular biomarkers. The purpose of this review is to discuss the commercially available colorectal cancer molecular diagnostic methods as well as to highlight some of the new candidate predictive and prognostic molecular markers for tumor, stool, and blood samples.