A systematic review and quantitative assessment of methylation biomarkers in fecal DNA and colorectal cancer and its precursor, colorectal adenoma

Significance of SDC2 and NDRG4 methylation in stool for colorectal cancer diagnosis

BACKGROUND

Recent studies have identified methylated SDC2 and NDRG4 in colorectal cancer (CRC), however, the diagnostic value of the combined two genes remains undefined. This study aims to investigate the methylation of SDC2 and NDRG4 in stool samples and their application in diagnosis of CRC.

METHODS

Five groups were enrolled in our study which consisted of CRC (n = 138), advanced adenomas (n = 27), polyp (n = 35), intestinal disease control (n = 150), and healthy individuals (n = 28). Methylation status of SDC2 and NDRG4 in fecal samples were tested with appropriate commercial kits. Primary data were collected and statistical analyses were performed.

RESULTS

The positive rates of both SDC2 and NDRG4 methylation in stool samples of CRC group were significantly higher (P < 0.001) than those of either group of advanced adenomas, or polyp, or intestinal disease or the healthy control. It was suggested that both methylated SDC2,NDRG4, SDC2/NDRG4 and age were independent risk factors for CRC. The sensitivity of SDC2 and NDRG4 for CRC diagnosis were 73.9 % and 63.0 %, respectively, while SDC2 combined with NDRG4 had a higher sensitivity of 85.5 %. The specificity of SDC2, NDRG4 and SDC2 combined with NDRG4 achieved 91.6 %, 88.3 % and 84.6 %, respectively. The AUC for methylated SDC2 and NDRG4 were 0.828 (95 % CI: 0.780-0.876) and 0.757 (95 % CI: 0.703-0.811), respectively. In contrast, SDC2 combined with NDRG4 improved the AUC to 0.850 (95 % CI: 0.807-0.893).

CONCLUSIONS

This research confirmed the significance of detection of SDC2 and NDRG4 methylation by using noninvasive samples of stool. More importantly, attributing to their high level and frequency of methylation in stool, SDC2 and NDRG4 could be promising biomarkers for stool-based method for screening and early diagnosis of CRC, especially when combined.

Tumor circulating biomarkers in colorectal cancer

CRC is a major global health concern and is responsible for a significant number of cancer-related deaths each year. The successful treatment of CRC becomes more difficult when it goes undetected until it has advanced to a later stage. Diagnostic biomarkers can play a critical role in the early detection of CRC, which leads to improved patient outcomes and increased survival rates. It is important to develop reliable biomarkers for the early detection of CRC to enable timely diagnosis and treatment. To date, CRC detection methods such as endoscopy, blood, and stool tests are imperfect and often only identify cases in the later stages of the disease. To overcome these limitations, researchers are turning to molecular biomarkers as a promising avenue for improving CRC detection. Diagnostic information can be provided more reliably through a noninvasive approach using biomarkers such as mRNA, circulating cell-free DNA, micro-RNA, long non-coding RNA, and proteins. These biomarkers can be found in blood, tissue, feces, and volatile organic compounds. The identification of molecular biomarkers with high sensitivity and specificity for early detection of CRC that are safe, cost-effective, and easily measurable remains a significant challenge for researchers. In this article, we will explore the latest advancements in blood-based diagnostic biomarkers for CRC and their potential impact on improving patient survival rates.

Current advances in detecting genetic and epigenetic biomarkers of colorectal cancer

Colorectal carcinoma (CRC) is the third most common cancer in terms of diagnosis and the second in terms of mortality. Recent studies have shown that various proteins, extracellular vesicles (i.e., exosomes), specific genetic variants, gene transcripts, cell-free DNA (cfDNA), circulating tumor DNA (ctDNA), microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and altered epigenetic patterns, can be used to detect, and assess the prognosis of CRC. Over the last decade, a plethora of conventional methodologies (e.g., polymerase chain reaction [PCR], direct sequencing, enzyme-linked immunosorbent assay [ELISA], microarray, in situ hybridization) as well as advanced analytical methodologies (e.g., microfluidics, electrochemical biosensors, surface-enhanced Raman spectroscopy [SERS]) have been developed for analyzing genetic and epigenetic biomarkers using both optical and non-optical tools. Despite these methodologies, no gold standard detection method has yet been implemented that can analyze CRC with high specificity and sensitivity in an inexpensive, simple, and time-efficient manner. Moreover, until now, no study has critically reviewed the advantages and limitations of these methodologies. Here, an overview of the most used genetic and epigenetic biomarkers for CRC and their detection methods are discussed. Furthermore, a summary of the major biological, technical, and clinical challenges and advantages/limitations of existing techniques is also presented.

Artificial intelligence for the prevention and prediction of colorectal neoplasms

BACKGROUND

Colonoscopy is a useful as a cancer screening test. However, in countries with limited medical resources, there are restrictions on the widespread use of endoscopy. Non-invasive screening methods to determine whether a patient requires a colonoscopy are thus desired. Here, we investigated whether artificial intelligence (AI) can predict colorectal neoplasia.

METHODS

We used data from physical exams and blood analyses to determine the incidence of colorectal polyp. However, these features exhibit highly overlapping classes. The use of a kernel density estimator (KDE)-based transformation improved the separability of both classes.

RESULTS

Along with an adequate polyp size threshold, the optimal machine learning (ML) models' performance provided 0.37 and 0.39 Matthews correlation coefficient (MCC) for the datasets of men and women, respectively. The models exhibit a higher discrimination than fecal occult blood test with 0.047 and 0.074 MCC for men and women, respectively.

CONCLUSION

The ML model can be chosen according to the desired polyp size discrimination threshold, may suggest further colorectal screening, and possible adenoma size. The KDE feature transformation could serve to score each biomarker and background factors (health lifestyles) to suggest measures to be taken against colorectal adenoma growth. All the information that the AI model provides can lower the workload for healthcare providers and be implemented in health care systems with scarce resources. Furthermore, risk stratification may help us to optimize the efficiency of resources for screening colonoscopy.

Colon cancer transcriptome

Over the last four decades, methodological innovations have continuously changed transcriptome profiling. It is now feasible to sequence and quantify the transcriptional outputs of individual cells or thousands of samples using RNA sequencing (RNA-seq). These transcriptomes serve as a connection between cellular behaviors and their underlying molecular mechanisms, such as mutations. This relationship, in the context of cancer, provides a chance to unravel tumor complexity and heterogeneity and uncover novel biomarkers or treatment options. Since colon cancer is one of the most frequent malignancies, its prognosis and diagnosis seem to be critical. The transcriptome technology is developing for an earlier and more accurate diagnosis of cancer which can provide better protectivity and prognostic utility to medical teams and patients. A transcriptome is a whole set of expressed coding and non-coding RNAs in an individual or cell population. The cancer transcriptome includes RNA-based changes. The combined genome and transcriptome of a patient may provide a comprehensive picture of their cancer, and this information is beginning to affect treatment decision-making in real-time. A full assessment of the transcriptome of colon (colorectal) cancer has been assessed in this review paper based on risk factors such as age, obesity, gender, alcohol use, race, and also different stages of cancer, as well as non-coding RNAs like circRNAs, miRNAs, lncRNAs, and siRNAs. Similarly, they have been examined independently in the transcriptome study of colon cancer.

Locus-Specific Bisulfate NGS Sequencing of GSTP1, RNF219, and KIAA1539 Genes in the Total Pool of Cell-Free and Cell-Surface-Bound DNA in Prostate Cancer: A Novel Approach for Prostate Cancer Diagnostics

The locus-specific methylation of three genes (GSTP1, RNF219, and KIAA1539, also known as FAM214B) in the total pool of blood cell-free DNA, including cell-free DNA from plasma and cell-surface-bound DNA, of patients with prostate cancer and healthy donors was studied on the MiSeq platform. Our study found a higher methylation index of loci for total cell-free DNA compared with cell-free DNA. For total cell-free DNA, the methylation of GSTP1 in each of the 11 positions provided a complete separation of cancer patients from healthy donors, whereas for cell-free DNA, there were no positions in the three genes allowing for such separation. Among the prostate cancer patients, the minimum proportion of GSTP1 genes methylated in any of the 17 positions was 12.1% of the total circulated DNA fragments, and the minimum proportion of GSTP1 genes methylated in any of the 11 diagnostically specific positions was 8.4%. Total cell-free DNA was shown to be more convenient and informative as a source of methylated DNA molecules circulating in the blood than cell-free DNA.

Methylation Heterogeneity and Gene Expression of SPG20 in Solid Tumors

Introduction. The downregulation of the Spastic Paraplegia-20 (SPG20) gene is correlated with a rare autosomal recessive disorder called Troyer Syndrome. Only in recent years has SPG20 been studied and partially characterized in cancer. SPG20 has been shown to be hypermethylated in colorectal cancer, gastric cancer, non-Hodgkin’s lymphoma and hepatocellular carcinoma. In this study, we analyze the methylation status and the gene expression of SPG20 in different tumors of various histological origins. Methods. We analyzed the data generated through Infinium Human Methylation 450 BeadChip arrays and RNA-seq approaches extrapolated from The Cancer Genome Atlas (TCGA) database. The statistics were performed with R 4.0.4. Results. We aimed to assess whether the hypermethylation of this target gene was a common characteristic among different tumors and if there was a correlation between the m-values and the gene expression in paired tumor versus solid tissue normal. Overall, our analysis highlighted that SPG20 open sea upstream the TSS is altogether hypermethylated, and the tumor tissues display a higher methylation heterogeneity compared to the solid tissue normal. The gene expression evidences a reproducible, higher gene expression in normal tissues. Conclusion. Our research, based on data mining from TCGA, evidences that colon and liver tumors display a consistent methylation heterogeneity compared to their normal counterparts. This parallels a downregulation of SPG20 gene expression in tumor samples and suggests a role for this multifunctional protein in the control of tumor progression.

Novel Diagnostic Biomarkers in Colorectal Cancer

Colorectal cancer (CRC) is still a leading cause of cancer death worldwide. Less than half of cases are diagnosed when the cancer is locally advanced. CRC is a heterogenous disease associated with a number of genetic or somatic mutations. Diagnostic markers are used for risk stratification and early detection, which might prolong overall survival. Nowadays, the widespread use of semi-invasive endoscopic methods and feacal blood tests characterised by suboptimal accuracy of diagnostic results has led to the detection of cases at later stages. New molecular noninvasive tests based on the detection of CRC alterations seem to be more sensitive and specific then the current methods. Therefore, research aiming at identifying molecular markers, such as DNA, RNA and proteins, would improve survival rates and contribute to the development of personalized medicine. The identification of “ideal” diagnostic biomarkers, having high sensitivity and specificity, being safe, cheap and easy to measure, remains a challenge. The purpose of this review is to discuss recent advances in novel diagnostic biomarkers for tumor tissue, blood and stool samples in CRC patients.

Locus-Specific Methylation of GSTP1, RNF219, and KIAA1539 Genes with Single Molecule Resolution in Cell-Free DNA from Healthy Donors and Prostate Tumor Patients: Application in Diagnostics

Simple Summary

Prostate cancer (PCa) is the second most commonly diagnosed cancer in men, which is constantly accompanied by benign prostate hyperplasia (BPH). To reach a 100% 5-year survival rate in PCa, which is characteristic for PCa if it is diagnosed in early stages, efficient PCa diagnostics against the background of BPH are demanded. The article describes a liquid biopsy approach to differential PCa diagnostics based on the data on locus-specific methylation of the three genes (GSTP1, RNF219, and KIAA1539) obtained with NGS of cell-free DNA from blood plasma of PCa, BPH, and healthy individuals. We offered a diagnostic approach including the analysis of simultaneous methylation status of two CpGs in one cell-free DNA molecule, allowing the discrimination of all patients with absolute sensitivity and specificity.

Abstract

The locus-specific methylation of three genes (GSTP1, RNF219, and KIAA1539 (also known as FAM214B)) in the blood plasma cell-free DNA (cfDNA) of 20 patients with prostate cancer (PCa), 18 healthy donors (HDs), and 17 patients with benign prostatic hyperplasia (BPH) was studied via the MiSeq platform. The methylation status of two CpGs within the same loci were used as the diagnostic feature for discriminating the patient groups. Many variables had good diagnostic characteristics, e.g., each of the variables GSTP1.C3.C9, GSTP1.C9, and GSTP1.C9.T17 demonstrated an 80% sensitivity at a 100% specificity for PCa patients vs. the others comparison. The analysis of RNF219 gene loci methylation allowed discriminating BPH patients with absolute sensitivity and specificity. The data on the methylation of the genes GSTP1 and RNF219 allowed discriminating PCa patients, as well as HDs, with absolute sensitivity and specificity. Thus, the data on the locus-specific methylation of cfDNA (with single-molecule resolution) combined with a diagnostic approach considering the simultaneous methylation of several CpGs in one locus enabled the discrimination of HD, BPH, and PCa patients.

Detection of Microsatellite Instability in Colorectal Cancer Patients With a Plasma-Based Real-Time PCR Analysis

A microsatellite instability (MSI) test is crucial for screening for HNPCC (Hereditary nonpolyposis colorectal cancer; Lynch syndrome) and optimization of colorectal cancer (CRC) treatment. Mismatch repair (MMR) deficiency is a predictor for good response of immune checkpoint inhibitors in various malignancies. In this study, we evaluated the results of a newly developed plasma-based real-time PCR kit for the detection of MSI in CRC patients. We assessed a peptide nucleotide acid (PNA) probe-mediated real-time PCR test (U-TOP MSI Detection Kit Plus) that determines MSI status by using amplicon melting analysis of five markers (NR21, NR24, NR27, BAT25, and BAT26) from plasma. Eighty-four CRC patients (46 dMMR and 38 pMMR) with colorectal cancer were analyzed. The concordance rate of MSI status assessment between the plasma kit and IHC was 63.0% in dMMR patients (29/46), but in the pMMR evaluation, a 100% (38/38) concordance rate was observed. In the evaluation of the performance of a custom tissue U-TOP MSI Detection Kit and plasma kit in 28 patients, sensitivity, specificity, PPV (positive predictive value) and NPV (negative predictive value) of plasma kit were 68.4, 100, 100, and 44.4%, respectively, with the tissue U-TOP MSI Detection Kit. Our results demonstrate the feasibility of a non-invasive and rapid plasma-based real-time PCR kit (U-TOP MSI Detection Kit Plus) for the detection of MSI in colorectal cancer.

Novel Methylation Biomarkers for Colorectal Cancer Prognosis

Colorectal cancer (CRC) comprises the third most common cancer worldwide and the second regarding number of deaths. In order to make a correct and early diagnosis to predict metastasis formation, biomarkers are an important tool. Although there are multiple signaling pathways associated with cancer progression, the most recognized are the MAPK pathway, p53 pathway, and TGF-β pathway. These pathways regulate many important functions in the cell, such as cell cycle regulation, proliferation, differentiation, and metastasis formation, among others. Changes in expression in genes belonging to these pathways are drivers of carcinogenesis. Often these expression changes are caused by mutations; however, epigenetic changes, such as DNA methylation, are increasingly acknowledged to play a role in the deregulation of oncogenic genes. This makes DNA methylation changes an interesting biomarkers in cancer. Among the newly identified biomarkers for CRC metastasis INHBB, SMOC2, BDNF, and TBRG4 are included, all of which are highly deregulated by methylation and closely associated with metastasis. The identification of such biomarkers in metastasis of CRC may allow a better treatment and early identification of cancer formation in order to perform better diagnostics and improve the life expectancy.

Liquid Biopsy-Based Colorectal Cancer Screening via Surface Markers of Circulating Tumor Cells

Colorectal cancer (CRC) is ranked second for cancer-related deaths worldwide with approximately half of the patients being diagnosed at the late stages. The untimely detection of CRC results in advancement to the metastatic stage and nearly 90% of cancer-related deaths. The early detection of CRC is crucial to decrease its overall incidence and mortality rates. The recent introduction of circulating tumor cells (CTCs) has enabled a less invasive sampling method from liquid biopsies, besides revealing key information toward CRC metastasis. The current gold standard for CTC identification is the CellSearch® system (Veridex). This first-generation instrumentation relies on a single cell surface marker (CSM) to capture and count CTCs. Detection of CTCs allows the identification of patients at risk for metastasis, whereas CTC enumeration could improve risk assessment, monitoring of systemic therapy, and detection of therapy resistance in advanced metastatic CRC. In this review, we compared the pros and cons between single CSM-based CTC enrichment techniques and multi-marker-based systems. We also highlighted the challenges faced in the routine implementation of CSM-dependent CTC detection methods in CRC screening, prediction, prognosis, disease monitoring, and therapy selection toward precision medicine, as well as the dwelling on post-CTC analysis and characterization methods.

Multiple Biomarker-Combined Screening for Colorectal Cancer Based on Bisulfate Conversion-Free Detection of Fecal DNA Methylation

To evaluate the applicability of bisulfate conversion-free methylation assay based on enzyme digestion in fecal screening for colorectal cancer (CRC). Stool samples were collected from a total of 1142 participants with intestinal abnormalities, including 180 positive cases, 60 advanced adenomas, and 902 negative cases. DNA from reference cell lines and clinical samples was extracted and digested with an enzyme to detect the methylation of CRC markers SEPT9, SDC2, NDRG4, SFRP2, and BMP3 genes. Statistical analysis was then used to determine the ability of the markers, both individually and in combination, to detect CRC and adenoma. Our results showed that the enzyme digestion method could suitably detect DNA marker methylation in as low as 1% of the cell lines. BMP3 had a considerably low detection rate in all clinical samples, with only 6 positive cases detected out of 180 cancer samples. Our findings showed that the combination of SEPT9, SDC2, and SFRP2 had an area under the receiver operation curve of 0.937, sensitivity of 94.11%, and specificity of 89.21% for detecting CRC. Moreover, the detection sensitivity of adenoma can also reach 38.33%. After innovatively utilizing bisulfate conversion-free methylation assay for CRC screening, this study verified the potential clinical applicability of combining multiple biomarkers for CRC screening in a large number of samples.

Using Comorbidity Pattern Analysis to Detect Reliable Methylated Genes in Colorectal Cancer Verified by Stool DNA Test

Colorectal cancer (CRC) is the third most commonly diagnosed cancer worldwide in 2020. Colonoscopy and the fecal immunochemical test (FIT) are commonly used as CRC screening tests, but both types of tests possess different limitations. Recently, liquid biopsy-based DNA methylation test has become a powerful tool for cancer screening, and the detection of abnormal DNA methylation in stool specimens is considered as an effective approach for CRC screening. The aim of this study was to develop a novel approach in biomarker selection based on integrating primary biomarkers from genome-wide methylation profiles and secondary biomarkers from CRC comorbidity analytics. A total of 125 differential methylated probes (DMPs) were identified as primary biomarkers from 352 genome-wide methylation profiles. Among them, 51 biomarkers, including 48 hypermethylated DMPs and 3 hypomethylated DMPs, were considered as suitable DMP candidates for CRC screening tests. After comparing with commercial kits, three genes (ADHFE1, SDC2, and PPP2R5C) were selected as candidate epigenetic biomarkers for CRC screening tests. Methylation levels of these three biomarkers were significantly higher for patients with CRC than normal subjects. The sensitivity and specificity of integrating methylated ADHFE1, SDC2, and PPP2R5C for CRC detection achieved 84.6% and 92.3%, respectively. Through an integrated approach using genome-wide DNA methylation profiles and electronic medical records, we could design a biomarker panel that allows for early and accurate noninvasive detection of CRC using stool samples.

Progressive alteration of DNA methylation of Alu, MGMT, MINT2, and TFPI2 genes in colonic mucosa during colorectal cancer development

BACKGROUND

Colorectal cancer (CRC) is one of the leading causes of mortality and morbidity in the world. It is characterized by different pathways of carcinogenesis and is a heterogeneous disease with diverse molecular landscapes that reflect histopathological and clinical information. Changes in the DNA methylation status of colon epithelial cells have been identified as critical components in CRC development and appear to be emerging biomarkers for the early detection and prognosis of CRC.

OBJECTIVE

To explore the underlying disease mechanisms and identify more effective biomarkers of CRC.

METHODS

We compared the levels and frequencies of DNA methylation in 11 genes (Alu, APC, DAPK, MGMT, MLH1, MINT1, MINT2, MINT3, p16, RGS6, and TFPI2) in colorectal cancer and its precursor adenomatous polyp with normal tissue of healthy subjects using pyrosequencing and then evaluated the clinical value of these genes.

RESULTS

Aberrant methylation of Alu, MGMT, MINT2, and TFPI2 genes was progressively accumulated during the normal-adenoma-carcinoma progression. Additionally, CGI methylation occurred either as an adenoma-associated event for APC, MLH1, MINT1, MINT31, p16, and RGS6 or a tumor-associated event for DAPK. Moreover, relatively high levels and frequencies of DAPK, MGMT, and TFPI2 methylation were detected in the peritumoral nonmalignant mucosa of cancer patients in a field-cancerization manner, as compared to normal mucosa from healthy subjects.

CONCLUSION

This study identified several biomarkers associated with the initiation and progression of CRC. As novel findings, they may have important clinical implications for CRC diagnostic and prognostic applications. Further large-scale studies are needed to confirm these findings.

Performance evaluation of stool DNA methylation tests in colorectal cancer screening: a systematic review and meta-analysis

AIM

There is not sufficient evidence about whether stool DNA methylation tests allow prioritizing patients to colonoscopy. Due to the COVID-19 pandemic, there will be a wait-list for rescheduling colonoscopies once the mitigation is lifted. The aim of this meta-analysis was to evaluate the accuracy of stool DNA methylation tests in detecting colorectal cancer.

METHODS

The PubMed, Cochrane Library and MEDLINE via Ovid were searched. Studies reporting the accuracy (Sackett phase 2 or 3) of stool DNA methylation tests to detect sporadic colorectal cancer were included. The DerSimonian-Laird method with random-effects model was utilized for meta-analysis.

RESULTS

Forty-six studies totaling 16 149 patients were included in the meta-analysis. The pooled sensitivity and specificity of all single genes and combinations was 62.7% (57.7%, 67.4%) and 91% (89.5%, 92.2%), respectively. Combinations of genes provided higher sensitivity compared to single genes (80.8% [75.1%, 85.4%] vs. 57.8% [52.3%, 63.1%]) with no significant decrease in specificity (87.8% [84.1%, 90.7%] vs. 92.1% [90.4%, 93.5%]). The most accurate single gene was found to be SDC2 with a sensitivity of 83.1% (72.6%, 90.2%) and a specificity of 91.2% (88.6%, 93.2%).

CONCLUSIONS

Stool DNA methylation tests have high specificity (92%) with relatively lower sensitivity (81%). Combining genes increases sensitivity compared to single gene tests. The single most accurate gene is SDC2, which should be considered for further research.

SDC2 and TFPI2 Methylation in Stool Samples as an Integrated Biomarker for Early Detection of Colorectal Cancer

Background

Detection of aberrant methylated DNA in the stool is an effective early screening method for colorectal cancer (CRC). Previously, reporters identified that syndecan-2 (SDC2) and tissue factor pathway inhibitor 2 (TFPI2) were aberrantly methylated in most CRC tissues. However, the combined diagnostic role of them remains undefined. Our research aimed at probing the role and efficiency of the methylation status of SDC2 and TFPI2 in CRC early screening by using bioinformatics analysis and clinical stool sample validation.

Methods

The promoter and CpG site methylation levels of SDC2 and TFPI2 and their correlation with clinicopathological characteristics of CRC were analyzed using UALCAN, Methsurv, and Wanderer. UCSC Xena was used to perform survival analyses. LinkedOmics was used to do functional network analysis. DNA was isolated and purified from stool, and quantitative methylation-specific PCR (qMSP) was applied to detect methylatedSDC2 and TFPI2.

Results

The results showed that promoter and most CpG site methylation levels of SDC2 and TFPI2 were significantly higher in CRC than in normal tissues. Moreover, SDC2 and TFPI2 methylation showed a positive correlation. Functional network analysis suggested that both methylated SDC2 and TFPI2 were involved in tumor cells’ metabolic programs. Besides, there was a higher positive integrated detection rate in CRC (n=61) with a sensitivity of 93.4% and in adenoma (Ade) (n=16) with a sensitivity of 81.3% than normal with a specificity of 94.3% in stool samples. What is more, integration of methylated SDC2 and TFPI2 showed a higher sensitivity and Youden index than a single gene in detecting Adeor CRC.

Conclusion

Our data indicate that SDC2 and TFPI2 were hypermethylated in CRC, and integrated detection of methylated SDC2 and TFPI2 in stool has the potential to be an effective and noninvasive tool of CRC early screening.

Microsatellite Instability in Colorectal Cancer Liquid Biopsy-Current Updates on Its Potential in Non-Invasive Detection, Prognosis and as a Predictive Marker

Colorectal cancer (CRC) is the third most commonly-diagnosed cancer in the world and ranked second for cancer-related mortality in humans. Microsatellite instability (MSI) is an indicator for Lynch syndrome (LS), an inherited cancer predisposition, and a prognostic marker which predicts the response to immunotherapy. A recent trend in immunotherapy has transformed cancer treatment to provide medical alternatives that have not existed before. It is believed that MSI-high (MSI-H) CRC patients would benefit from immunotherapy due to their increased immune infiltration and higher neo-antigenic loads. MSI testing such as immunohistochemistry (IHC) and PCR MSI assay has historically been a tissue-based procedure that involves the testing of adequate tissue with a high concentration of cancer cells, in addition to the requirement for paired normal tissues. The invasive nature and specific prerequisite of such tests might hinder its application when surgery is not an option or when the tissues are insufficient. The application of next-generation sequencing, which is highly sensitive, in combination with liquid biopsy, therefore, presents an interesting possibility worth exploring. This review aimed to discuss the current body of evidence supporting the potential of liquid biopsy as a tool for MSI testing in CRC.

The Value of Multi-targeted Fecal DNA Methylation Detection for Colorectal Cancer Screening in a Chinese Population

Objective: To design a multi-targeted fecal DNA methylation kit and explore its value for clinical application among Chinese people. Methods: Based on previous research, a multi-targeted fecal DNA methylation detection kit, using four genes, was designed and clinically validated. Results: The methylation PCR from 279 patients met the requirements for the detection criteria. When all four molecular markers were negative, the negative predictive value (NPV) for colorectal cancer was 100% and the NPV for colorectal polyps was 84.21%. When one molecular marker was positive, the sensitivity (Se) for colorectal cancer was 76.4%-90.3%, the specificity (Sp) was 68.3-93.4%, and the positive predictive value (PPV) for colorectal cancer was 54.5-85.5%, and the NPV was 87.0-95.0%. For colorectal polyps, the Se was 41.0-52.5%, Sp 69.5-91.5%, and the PPV for colorectal polyps was 41.0-70.3%, the NPV was 75.2-79.3%. When two molecular markers were positive, the Se for colorectal cancer was 52.6-73.7%, the Sp was 93.2-98.3%, the PPV for colorectal cancer was 84.6-96.2%, the NPV was 76.0-85.3%. For colorectal polyps, the Se was 25.9-40.7%, Sp was 93.2-98.3%, PPV for screening of colorectal polyps was 63.6-90.0%, and the NPV was 73.3-78.1%. When three molecular markers were positive, the Se for colorectal cancer was 31.6-52.6%, the Sp was 98.3-100.0%, the PPV for colorectal cancer was 94.4-100.0%, the NPV was 73.4-76.6%. For colorectal polyps, the Se was 14.8-25.9%, and Sp was 98.3-100.0%, the PPV for colorectal polyps was 85.7-100.0%, the NPV was 72.0-74.7%. When four molecular markers were positive, the Se for colorectal cancer was 31.6%, the Sp was 100.0%, and the colorectal cancer PPV was 100.0% and the NPV was 69.4%. For polyps, the Se was 14.8%, Sp was 100.0%, and PPV was 100.0% and the NPV was 72.0%. Conclusion: The multi-targeted fecal DNA methylation detection kit for colorectal cancer and polyps had the sensitivity and specificity to meet the requirements for screening of colorectal tumors, which is easy to operate, has stable results and important clinical value. Among the four molecular markers studied, when one marker was positive for DNA methylation, colonoscopy was required; as the number of positive methylation markers increased, the specificity for the diagnosis gradually increased as well.

A New Method for the Detection of Colorectal Cancer and the Precancerous Lesions: Occult Blood Testing Combination with Promoter Methylation in the Fecal Sample

Background: Noninvasive stool-based DNA methylation testing emerges as a new approach for detecting colorectal cancer (CRC). However, its feasibility for early detection of CRC and precancerous lesions in the Chinese population remains inconclusive.

Methods: In this study, we establish a possibilities screening method (sDNA-FOBT) for detecting CRC and precancerous lesions (hyperplastic polyps [HP] and adenomas [AD]) and evaluate its detection performance in the Chinese population. This method combined a molecular assay of DNA methylation markers (BMP3, NDRG4, and SDC2) with the human hemoglobin test (FOBT) in stool samples.

Results: The sensitivity of sDNA-FOBT was 85.42% for CRC, 85.71% for AD, and 28.21% for HP, respectively, at the specificity of 92%. The diagnostic efficacy of sDNA-FOBT for detecting CRC and precancerous lesions was significantly higher than FOBT alone (sensitivity: 61.70% vs. 51.06%, P<0.01; AUC: 0.78 vs. 0.72, P<0.001), especially for CRC (AUC: 0.91 vs. 0.86, P<0.001) and AD (AUC: 0.91 vs. 0.75, P<0.05). No significant difference was observed between the detection sensitivity of sDNA-FOBT and the clinical variables. Notably, compared with FOBT, sDNA-FOBT was more effective in the detection of CRC and precancerous lesions in the patients aged >50 y (62.34% vs 54.55%, P<0.05).

Conclusion: Our results demonstrate that sDNA-FOBT is a promising method for screening CRC and precancerous lesions in the Chinese population. Further studies are required to validate the results in a larger sample capacity.

Colorectal Cancer Screening Methods and Molecular Markers for Early Detection

Colorectal cancer (CRC) is one of the most common malignant tumors in the digestive tract in humans. The development of colorectal cancer is composed of multiple stages, starting with benign adenomatous polyps in the inner wall of the large intestine and rectum, and then gradually developing. Then it developed into advanced adenomas carcinoma in situ and invasive carcinoma. Represents the distant metastasis of the most advanced development. The purpose of this review is to novel routine screening and diagnostic methods (e.g., Endoscopy and CT colonoscopy, SEPT9 methylation assay, Fecal test) and find reliable molecular markers for early diagnosis of CRC.

C8orf48 inhibits the tumorigenesis of colorectal cancer by regulating the MAPK signaling pathway

AIMS

Colorectal cancer (CRC) is a leading cause of cancer-related death globally. Thus, in this study, we aimed to investigate chromosome 8 open reading frame 48 (C8orf48) as a biomarker for early detection of CRC.

MAIN METHODS

RNA expression and methylation profiles were downloaded from The Cancer Genome Atlas (TCGA) database. Cell proliferation, migration and invasion assays were performed to confirm the function of C8orf48 in CRC cells. Dual-luciferase reporter assay was used to identify that C8orf48 was the direct target of miR-556. Genomics of Drug Sensitivity in Cancer (GDSC) database, gene set enrichment analysis (GSEA) and western blot analysis were performed to explore the mechanism of C8orf48.

KEY FINDINGS

we found that C8orf48 is down-regulated in clinical samples of CRC tissues. Enrichment analysis showed that C8orf48 is associated with methylation biomarkers in CRC, and TCGA database confirmed that the methylation of C8orf48 is up-regulated in the early stage of CRC. We further revealed that the overexpression of C8orf48 decreased CRC cell proliferation, migration and invasion. Luciferase reporter indicated that C8orf48 was the direct target of the oncogene miR-556. Additionally, we used GDSC database, GSEA database and western blot analysis to demonstrate that C8orf48 plays a suppressor role in CRC by inhibiting MAPK signaling pathway.

SIGNIFICANCE

C8orf48 was identified as a biomarker for early detection of CRC for the first time, and might provide novel information for CRC prediction and therapy.

Hypomethylation of GDNF family receptor alpha 1 promotes epithelial-mesenchymal transition and predicts metastasis of colorectal cancer

Tumor metastasis is the major cause of poor prognosis and mortality in colorectal cancer (CRC). However, early diagnosis of highly metastatic CRC is currently difficult. In the present study, we screened for a novel biomarker, GDNF family receptor alpha 1 (GFRA1) based on the expression and methylation data in CRC patients from The Cancer Genome Altlas (TCGA), followed by further analysis of the correlation between the GFRA1 expression, methylation, and prognosis of patients. Our results show DNA hypomethylation-mediated upregulation of GFRA1 in invasive CRC, and it was found to be correlated with poor prognosis of CRC patients. Furthermore, GFRA1 methylation-modified sequences were found to have potential as methylation diagnostic markers of highly metastatic CRC. The targeted demethylation of GFRA1 by dCas9-TET1CD and gRNA promoted CRC metastasis in vivo and in vitro. Mechanistically, demethylation of GFRA1 induces epithelial-mesenchymal transition (EMT) by promoting AKT phosphorylation and increasing c-Jun expression in CRC cells. Collectively, our findings indicate that GFRA1 hypomethylation can promote CRC invasion via inducing EMT, and thus, GFRA1 methylation can be used as a biomarker for the early diagnosis of highly metastasis CRC.

Abnormal DNA methylation, one of important characteristics in tumor cells, is exploited as biomarkers for cancer diagnosis and prognosis prediction. Early diagnosis of highly metastatic CRC will be helpful for the clinical management, thus prolongs patient survival. However, it is currently difficult to make early diagnosis of highly metastatic CRC in clinical practice. Currently, we screened a novel biomarker gene, GFRA1, which associated with the invasion and poor prognosis of CRC. The targeted demethylation of GFRA1 exerted a significant promoting effect on CRC metastasis, and GFRA1 methylation-modified sequences are valuable diagnostic biomarker for CRC metastasis risk assessment. Mechanically, demethylation of GFRA1 induced epithelial-mesenchymal transition (EMT) by upregulating AKT phosphorylation and c-Jun expression in CRC cells. Our results demonstrate the promoting effect of GFRA1 demethylation on CRC invasion and GFRA1 methylation may be a potential prognostic marker for predicting metastasis of CRC.

EZH2 regulates sFRP4 expression without affecting the methylation of sFRP4 promoter DNA in colorectal cancer cell lines

Abnormal activation of the Wnt signaling pathway is found in 90% of colorectal cancers (CRCs). Secreted frizzled-related protein 4 (sFRP4) serves as an antagonist of the canonical Wnt signaling pathway. Epigenetic alterations, including changes in DNA methylation and histone methylation, may influence the expression of sFRP4. Polycomb group (PcG) proteins are epigenetic transcriptional repressors that selectively repress gene expression by forming polycomb repressive complexes (PRCs). Enhancer of zeste homolog 2 (EZH2), the core component of PRC2, is a histone-lysine N-methyltransferase that interacts with DNA methyltransferases. In the present study, the promoter DNA methylation status of sFRP4 in CRC cell lines was analyzed and the underlying mechanisms of action governing this modification was investigated. Firstly, the DNA methylation status of the sFRP4 promoter in CRC cell lines was assessed using methylation-specific PCR. Subsequently, the mRNA and protein levels of sFRP4 were measured using real-time qPCR and western blot analysis, respectively, to determine whether the DNA methylation status of the sFRP4 promoter is correlated with its transcriptional levels. To screen for important epigenetic modifiers that may regulate the promoter DNA methylation status of sFRP4, the expression levels of PcG proteins were examined by gene array analysis. ChIP-qPCR was performed to test whether the selected PcG proteins directly bind the promoter region of sFRP4. Finally, the downregulated PcG proteins EZH2, chromobox 7 (CBX7) and jumonji and AT-rich interaction domain containing 2 (JARID2) were identified and their association with sFRP4 expression levels and Wnt/β-catenin signaling pathway activity were investigated. The present study revealed that sFRP4 was hypermethylated in the promoter region and downregulated during the progression of the CRC cell lines from Dukes A to Dukes C. Expression levels of PcG proteins EZH2, CBX7 and JARID2 were upregulated and positively associated with the aberrantly activated Wnt signaling pathway in the CRC cell lines. EZH2, CBX7 and JARID2 were all enriched in the sFRP4 promoter region in CRC cells. EZH2 downregulation did not affect the promoter DNA methylation status of sFRP4 but increased its expression levels and decreased CRC cell proliferation. DNA methylation controls the expression of sFRP4. EZH2 regulates sFRP4 expression without affecting the DNA hypermethylation of the sFRP4 promoter and influences CRC cell proliferation and Wnt/β-catenin signaling pathway activities.

A Distinctive microRNA (miRNA) Signature in the Blood of Colorectal Cancer (CRC) Patients at Surgery

Background: Liquid biopsy (LB) provides an examination of the peripheral blood of cancer patients for circulating tumor cells, cell-free nucleic acids and microRNAs (miRNAs) and is an established tool of precision medicine. Unlike most previous LB studies that focused on advanced metastatic colorectal cancer (CRC), we assessed miRNA dysregulation in blood samples obtained on the day of surgery from patients with primary CRC lesions but no clinical evidence of extra-colonic diffusion. In this study, plasma preparation included miRNAs associated to exosomes, but excluded large macrovesicles from the preparation. Methods: The miRNA profile in plasma isolated from a cohort of 35 CRC patients at the day of surgery was analyzed by Next Generation Sequencing (NGS) and further confirmed by droplet digital RT-PCR (dd-RT-PCR). Results: A miR-141-3p/miR-221-3p/miR-222-3p upregulation signature previously described in advanced CRC did not discriminate the analyzed early-CRC cohort from six tumor-free donors (Tf-D). In contrast, NGS-based miRNome analysis of a training cohort of five CRC and three tumor-free donors identified a novel, distinct nine miRNA signature comprising five up-regulated and four down-regulated miRNAs, six of which could be confirmed in the full CRC and tumor-free donor validation dataset by dd-RT-PCR. Additionally, a KRAS (Kirsten Rat Sarcoma Viral Oncogene Homolog) mutant status was correlated with the plasma content of three identified miRNAs. Conclusions: When the data obtained were comparatively evaluated, at least one of the miRNAs belonging to the signature list was found to be dysregulated in 34/35 (97.1%) of our early-CRC plasma samples. The miRNA list provides diagnostic markers as well as possible molecular targets for protocols focusing on “microRNA therapeutics”.

Tissue and Cell-Free DNA-Based Epigenomic Approaches for Cancer Detection

BACKGROUND

Over 9 million people die of cancer each year worldwide, reflecting the unmet need for effective biomarkers for both cancer diagnosis and prognosis. Cancer diagnosis is complex because the majority of malignant tumors present with long periods of latency and lack of clinical presentation at early stages. During carcinogenesis, premalignant cells experience changes in their epigenetic landscapes, such as differential DNA methylation, histone modifications, nucleosome positioning, and higher orders of chromatin changes that confer growth advantage and contribute to determining the biologic phenotype of human cancers.

CONTENT

Recent progress in microarray platforms and next-generation sequencing approaches has allowed the characterization of abnormal epigenetic patterns genome wide in a large number of cancer cases. The sizable amount of processed data also comes with challenges regarding data management and assessment for effective biomarker exploration to be further applied in prospective clinical trials. Epigenetics-based single or panel tests of genes are being explored for clinical management to fulfill unmet needs in oncology. The advance of these tests to the clinical routine will depend on rigorous, extensive, and independent validation in well-annotated cohort of patients and commercial development of clinical routine-friendly and adequate procedures.

SUMMARY

In this review we discuss the analytic validation of tissue and cell-free DNA-based epigenomic approaches for early cancer detection, diagnosis, and treatment monitoring and the clinical utility of candidate epigenetic alterations applied to colorectal, glioblastoma, breast, prostate, bladder, and lung cancer management.

Biomarkers for detecting colorectal cancer non-invasively: DNA, RNA or proteins?

Colorectal cancer (CRC) is a global problem affecting millions of people worldwide. This disease is unique because of its slow progress that makes it preventable and often curable. CRC symptoms usually emerge only at advanced stages of the disease, consequently its early detection can be achieved only through active population screening, which markedly reduces mortality due to this cancer. CRC screening tests that employ non-invasively detectable biomarkers are currently being actively developed and, in most cases, samples of either stool or blood are used. However, alternative biological substances that can be collected non-invasively (colorectal mucus, urine, saliva, exhaled air) have now emerged as new sources of diagnostic biomarkers. The main categories of currently explored CRC biomarkers are: (1) Proteins (comprising widely used haemoglobin); (2) DNA (including mutations and methylation markers); (3) RNA (in particular microRNAs); (4) Low molecular weight metabolites (comprising volatile organic compounds) detectable by metabolomic techniques; and (5) Shifts in gut microbiome composition. Numerous tests for early CRC detection employing such non-invasive biomarkers have been proposed and clinically studied. While some of these studies generated promising early results, very few of the proposed tests have been transformed into clinically validated diagnostic/screening techniques. Such DNA-based tests as Food and Drug Administration-approved multitarget stool test (marketed as Cologuard®) or blood test for methylated septin 9 (marketed as Epi proColon® 2.0 CE) show good diagnostic performance but remain too expensive and technically complex to become effective CRC screening tools. It can be concluded that, despite its deficiencies, the protein (haemoglobin) detection-based faecal immunochemical test (FIT) today presents the most cost-effective option for non-invasive CRC screening. The combination of non-invasive FIT and confirmatory invasive colonoscopy is the current strategy of choice for CRC screening. However, continuing intense research in the area promises the emergence of new superior non-invasive CRC screening tests that will allow the development of improved disease prevention strategies.

Hypermethylation of Corticotropin Releasing Hormone Receptor-2 Gene in Ulcerative Colitis Associated Colorectal Cancer

BACKGROUND/AIM

The difficulty of early diagnosis of colitis associated colorectal cancer (CACRC) due to colonic mucosal changes in long-standing ulcerative colitis (UC) patients is often experienced in daily clinical practice. Noninvasive objective monitoring for cancer development is advantageous for optimizing treatment strategies in UC patients. We aimed to examine the epigenetic alterations occurring in CACRC, focusing on DNA hypermethylation of CpG islands.

MATERIALS AND METHODS

The level of DNA methylation in CpG cites was compared between CACRC and the counterpart non-tumorous mucosa using Infinium HumanMethylation 450K BeadChip.

RESULTS

Our subjects included 3 males and 3 females (median age, 49.5 years). The 450K CpG site DNA methylation microarray revealed that the difference in β value (level of hypermethylation) was the highest for corcicotropin releasing hormone receptor 2 (CRHR2) between CACRC and counterpart non-tumorous mucosa.

CONCLUSION

Detection of hypermethylation of CRHR2 may be promising for cancer screening in UC patients.