Circulating microRNAs as a novel class of diagnostic biomarkers in gastrointestinal tumors detection: a meta-analysis based on 42 articles

Liquid biopsy approaches and immunotherapy in colorectal cancer for precision medicine: Are we there yet?

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths globally, with nearly half of patients detected in the advanced stages. This is due to the fact that symptoms associated with CRC often do not appear until the cancer has reached an advanced stage. This suggests that CRC is a cancer with a slow progression, making it curable and preventive if detected in its early stage. Therefore, there is an urgent clinical need to improve CRC early detection and personalize therapy for patients with this cancer. Recently, liquid biopsy as a non-invasive or nominally invasive approach has attracted considerable interest for its real-time disease monitoring capability through repeated sample analysis. Several studies in CRC have revealed the potential for liquid biopsy application in a real clinical setting using circulating RNA/miRNA, circulating tumor cells (CTCs), exosomes, etc. However, Liquid biopsy still remains a challenge since there are currently no promising results with high specificity and specificity that might be employed as optimal circulatory biomarkers. Therefore, in this review, we conferred the plausible role of less explored liquid biopsy components like mitochondrial DNA (mtDNA), organoid model of CTCs, and circulating cancer-associated fibroblasts (cCAFs); which may allow researchers to develop improved strategies to unravel unfulfilled clinical requirements in CRC patients. Moreover, we have also discussed immunotherapy approaches to improve the prognosis of MSI (Microsatellite Instability) CRC patients using neoantigens and immune cells in the tumor microenvironment (TME) as a liquid biopsy approach in detail.

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.

Advances of Tumorigenesis, Diagnosis at Early Stage, and Cellular Immunotherapy in Gastrointestinal Malignancies

Globally, in 2018, 4.8 million new patients have a diagnosis of gastrointestinal (GI) cancers, while 3.4 million people died of such disorders. GI malignancies are tightly relevant to 26% of the world-wide cancer incidence and occupies 35% of all cancer-associated deaths. In this article, we principally investigated molecular and cellular mechanisms of tumorigenesis in five major GI cancers occurring at esophagus, stomach, liver, pancreas, and colorectal region that illustrate high morbidity in Eastern and Western countries. Moreover, through this investigation, we not only emphasize importance of the tumor microenvironment in development and treatment of malignant tumors but also identify significance of M2PK, miRNAs, ctDNAs, circRNAs, and CTCs in early detection of GI cancers, as well as systematically evaluate contribution of personalized precision medicine including cellular immunotherapy, new antigen and vaccine therapy, and oncolytic virotherapy in treatment of GI cancers.

Diagnostic value of oncofetal miRNAs in cancers: A comprehensive analysis of circulating miRNAs in pan-cancers and UCB

BACKGROUND

Circulating miRNAs are promising biomarkers for detection of various cancers. As a "developmental" disorder, cancer showed great similarities with embryos.

OBJECTIVE

A comprehensive analysis of circulating miRNAs in umbilical cord blood (UCB) and pan-cancers was conducted to identify circulating miRNAs with potential for cancer detection.

METHODS

A total of 3831 cancer samples (2050 serum samples from 15 types of cancers and 1781 plasma samples from 13 types of cancers) and 248 UCB samples (120 serum and 128 plasma samples) with corresponding NCs from Chinese populations were analyzed via consistent experiment workflow with Exiqon panel followed by multiple-stage validation with qRT-PCR.

RESULTS

Thirty-four serum and 32 plasma miRNAs were dysregulated in at least one type of cancer. Eighteen serum and 16 plasma miRNAs were related with embryos. Among them, 9 serum and 8 plasma miRNAs with consistent expression patterns between pan-cancers and UCB were identified as circulating oncofetal miRNAs. Retrospective analysis confirmed the diagnostic ability of circulating oncofetal miRNAs for specific cancers. And the oncofetal miRNAs were mainly up-regulated in tissues of pan-cancers.

CONCLUSIONS

Our study might serve as bases for the potential application of the non-invasive biomarkers in the future clinical.

Liquid Biopsy for Cancer Cachexia: Focus on Muscle-Derived microRNAs

Cancer cachexia displays a complex nature in which systemic inflammation, impaired energy metabolism, loss of muscle and adipose tissues result in unintentional body weight loss. Cachectic patients have a poor prognosis and the presence of cachexia reduces the tolerability of chemo/radio-therapy treatments and it is frequently the primary cause of death in advanced cancer patients. Early detection of this condition could make treatments more effective. However, early diagnostic biomarkers of cachexia are currently lacking. In recent years, although solid biopsy still remains the "gold standard" for diagnosis of cancer, liquid biopsy is gaining increasing interest as a source of easily accessible potential biomarkers. Moreover, the growing interest in circulating microRNAs (miRNAs), has made these molecules attractive for the diagnosis of several diseases, including cancer. Some muscle-derived circulating miRNA might play a pivotal role in the onset/progression of cancer cachexia. This topic is of great interest since circulating miRNAs might be easily detectable by means of liquid biopsies and might allow an early diagnosis of this syndrome. We here summarize the current knowledge on circulating muscular miRNAs involved in muscle atrophy, since they might represent easily accessible and promising biomarkers of cachexia.

Long noncoding RNAs as diagnostic biomarkers for the early detection of digestive tract cancers: a systematic review and meta-analysis

BACKGROUND

long noncoding RNAs (lncRNAs) have attracted attention recently. However, many inconsistencies frequently appeared for the early diagnosis of digestive tract cancers (DTCs). We performed this meta-analysis to describe the diagnostic performance of lncRNAs in the discrimination of DTCs.

METHODS

data were extracted from PubMed, Web of Science, Embase, and Cochrane Library. Their quality was evaluated using the revised Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2). Such parameters as sensitivity and specificity were included for pooled analyses. The STATA 12.0 and Meta-Disc 1.4 software packages were used to perform the statistical analysis.

RESULTS

sixty-nine papers were included in this meta-analysis. The pooled analysis of DTCs showed that lncRNAs had a sensitivity of 0.78 and a specificity of 0.80. The area under the summary ROC curve (AUC) was 0.86. For gastric cancer (GC), the pooled sensitivity and specificity were 0.77 (95 % CI: 0.72-0.81) and 0.75 (95 % CI: 0.71-0.79), respectively, and the AUC was 0.83. For colorectal cancer (CRC), these three parameters were 0.82 (95 % CI: 0.76-0.86), 0.84 (95 % CI: 0.79-0.88), and 0.90, respectively. For esophageal cancer (EC) sensitivity was 0.74 (95 % CI: 0.67-0.80) and specificity reached 0.86 (95 % CI: 0.72-0.93), with an AUC of 0.82.

CONCLUSIONS

LncRNAs show potential diagnostic value for discrimination between DTCs.

Novel Biomarkers in the Diagnosis of Benign and Malignant Gastrointestinal Diseases

BACKGROUND

Various noninvasive biomarkers have been used in the diagnosis, prognosis, and treatment of different gastrointestinal (GI) diseases for years. Novel technological developments and profound perception of molecular processes related to GI diseases over the last decade have allowed researchers to evaluate genetic, epigenetic, and many other potential molecular biomarkers in different diseases and clinical settings. Here, we present a review of recent and most relevant articles in order to summarize major findings on novel biomarkers in the diagnosis of benign and malignant GI diseases.

SUMMARY

Genetic variations, noncoding RNAs (ncRNAs), cell-free DNA (cfDNA), and microbiome-based biomarkers have been extensively analyzed as potential biomarkers in benign and malignant GI diseases. Multiple single-nucleotide polymorphisms have been linked with a number of GI diseases, and these observations are further being used to build up disease-specific genetic risk scores. Micro-RNAs and long ncRNAs have a large potential as noninvasive biomarkers in the management of inflammatory bowel diseases and GI tumors. Altered microbiome profiles were observed in multiple GI diseases, but most of the findings still lack translational clinical application. As of today, cfDNA appears to be the most potent biomarker for early detection and screening of GI cancers. Key Messages: Novel noninvasive molecular biomarkers show huge potential as useful tools in the diagnostics and management of different GI diseases. However, the use of these biomarkers in real-life clinical practice still remains limited, and further large studies are needed to elucidate the ultimate role of these potential noninvasive clinical tools.

Circulating molecular biomarkers for screening or early diagnosis of colorectal cancer: which is ready for prime time?

According to recent statistics, colorectal cancer (CRC) is a frequent disease, the second most frequent malignancy in women and the third most common malignant disease in men, respectively. Although reinforced emphasis on CRC screening by means of immunochemical fecal occult blood test, colonoscopy or sigmoidoscopy has contributed to decrease cancer-related deaths, alternative diagnostic tests would be needed for establishing earlier and more potentially effective treatments. Innovative diagnostic techniques have recently emerged, some of which hold promises for screening and/or early CRC detection. Recent evidence suggests that the so-called "liquid biopsy", conventionally defined as detection and quantification of circulating tumor cells (CTCs) and cancer-related nucleic acids in peripheral blood, may allow earlier diagnosis of CRC combined with lower invasiveness and less patient inconvenience, higher throughput, faster turnaround time, inferior usage of healthcare resources and relatively low cost. Encouraging data have emerged from trials based on CTCs detection, though the sensitivity of the current diagnostic techniques is still perhaps insufficient for enabling early CRC diagnosis. Among the various biomarkers that can be detected with liquid biopsy, SEPT9 methylation displays good diagnostic performance and relatively high cancer detection rate (between 57-64% in patients with CRC stages 0-I), which would make this test a promising tool for population screening, alone or in combination with other conventional diagnostic investigations. Encouraging evidence has also been recently published for BCAT1/IKZF1 methylation. Regarding microRNA (miRNAs), the available evidence highlights that the combination of some of these biomarkers rather than the assessment of a single miRNA alone would enable efficient identification of early CRCs, though widespread clinical application is still challenged by a number of preanalytical, analytical and clinical issues.

Plasma miRNAs in diagnosis and prognosis of pancreatic cancer: A miRNA expression analysis

The differential expression of microRNAs (miRNAs) in plasma of pancreatic cancer (PC) patients may act as a diagnostic biomarker. A four-stage study was performed to identify plasma miRNAs with potential in detecting PC. Exiqon panels (20 PC vs. 10 normal controls (NCs)) were applied in the screening phase to obtain miRNA profiling. The identified miRNAs were further assessed in the training (40 PC vs. 40 NCs) and testing stages (112 PC vs. 116 NCs) with qRT-PCR assays. A six-miRNA signature including up-regulated miR-122-5p, miR-125b-5p, miR-192-5p, miR-193b-3p, miR-221-3p and miR-27b-3p was identified. The signature could accurately discriminate PC patients from NCs with areas under the receiver operating characteristic curve of 0.848, 0.833 and 0.937 for the training, testing and the external validation stage (41 PC vs. 50 NCs), respectively. The multivariate Cox regression analyses showed that down-regulated plasma miR-125b-5p could predict worse OS independent from late tumor stage and high CA19-9. All the six miRNAs except miR-122-5p showed high expression levels in PC tissues than those in matched normal tissues. MiR-122-5p and miR-193b-3p were up-regulated, while miR-221-3p was down-regulated in plasma exosomes from PC patients. Bioinformatics analysis demonstrated that the miRNAs might involve in several molecular pathways closely related with PC such as p53 signaling pathway, pancreatic cancer, TGF-beta signaling pathway and so on. In conclusion, we identified a six-miRNA signature in plasma which could act as a non-invasive biomarker in diagnosis and prognosis of PC. Plasma miR-125b-5p might act as an independent biomarker in predicting OS of PC patients.

Serum microRNA signatures and metabolomics have high diagnostic value in gastric cancer

BACKGROUND

Many novel diagnostic biomarkers have been developed for gastric cancer (GC) recently. We chose two methods with high diagnostic value, the detection of serum microRNAs and metabolomics based on gas chromatography/mass spectrometry (GC/MS), and aimed to establish appropriate models.

METHODS

We reviewed the diagnostic accuracies of all microRNAs identified by previous diagnostic tests. Then appropriate microRNAs and their combinations were validated the diagnostic value. We included 80 patients with GC and 82 healthy controls (HCs) and detected the expression of the microRNAs. GC/MS analysis was conducted, and we used three multivariate statistical analyses to establish diagnostic models. The concentrations of carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) were detected for comparison with the novel models.

RESULTS

Sixty-seven published studies and 70 microRNAs were finally included in the systematic review. MiR-18a, miR-19a, miR-21, miR-92a, miR-199a and miR-421 were chosen to further validate their diagnostic efficiencies. Five of those microRNAs in GC patients had significantly different expression. The combination of miR-19a and miR-92a had the highest area under the curve (AUC) at 0.850 with a sensitivity of 91.3% and a specificity of 61.0%. The GC/MS analysis performed an excellent diagnostic value and the AUC reached 1.0.

CONCLUSION

There is a good potential for microRNAs and GC/MS analysis as new diagnostic methods in view of their high diagnostic value compared with traditional biomarkers.

Identification of circulating microRNAs as diagnostic biomarkers for ovarian cancer:A pooled analysis of individual studies

BACKGROUND

Circulating microRNAs (miRNAs) are proposed as promising non-invasive diagnostic biomarkers for many cancers. However, the diagnostic value of circulating miRNAs in ovarian cancer is inconsistent in different studies. Thus we performed this meta-analysis to systematically evaluate the diagnostic value of circulating miRNAs in ovarian cancer.

METHODS

Eligible studies that were published prior to 30 June 2017 were searched from the PubMed, EMBASE, Cochrane Library, and Chinese National Knowledge Infrastructure. All analyses were performed using STATA 12.0 software. A bivariate regression was used to calculate pooled diagnostic accuracy estimates.

RESULTS

A total of 36 studies from 16 publications were included in this meta-analysis. The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio of circulating miRNAs for ovarian cancer diagnosis were 0.76 (95% confidence intervals (CI): 0.69, 0.81), 0.81 (95% CI 0.74, 0.87), 4.00 (95% CI 2.70, 5.30), 0.30(95% CI 0.24, 0.37) and 13.00 (95% CI 9.00, 19.00), respectively. The area under the summary receiver operating characteristic curve was 0.85 (95% CI 0.82, 0.88). Subgroup analyses showed that multiple miRNA assays yielded better diagnostic characteristics than a single miRNA assay, and plasma miRNAs were better than serum miRNAs for ovarian cancer detection.

CONCLUSION

Circulating miRNAs, especially the combination of multiple circulating miRNAs, are promising biomarkers for the diagnosis of ovarian cancer. However, further large-scale prospective studies are necessary to validate the applicability of the miRNAs in the early detection of ovarian cancer.

MicroRNAs in type 2 immunity

Type 2 immunity drives the pathology of allergic diseases and is necessary for expulsion of parasitic worms as well as having important implications in tumor progression. Over the last decade, a new research field has emerged describing a significant link between type 2 immunity and cancer development, called AllergoOncology. Thus, type 2 immune responses must be carefully regulated to mediate effective protection against damaging environmental factors, yet avoid excessive activation and immunopathology. Regulation of gene expression by microRNAs is required for normal behavior of most mammalian cells and has been studied extensively in the context of cancer. Although microRNA regulation of the immune system in cancer is well established and includes type 2 immune reactions in the tumor microenvironment, the involvement of microRNAs in these responses initiated by allergens, parasites or other environmental factors is just emerging. In this review, we focus on recent advances which increase the understanding of microRNA-mediated regulation of key mechanisms of type 2 immunity.

Circulating microRNA124-3p, microRNA9-3p and microRNA196b-5p may be potential signatures for differential diagnosis of thyroid nodules

It is important to develop an effective auxiliary approach to distinguish papillary thyroid carcinoma (PTC) from benign nodules because a considerable proportion cannot be identified by fine-needle aspiration cytology at present, resulting in unnecessary thyroidectomy. Circulating miRNAs are potential biomarkers for differential diagnosis of tumors. We aimed to investigate the dysregulation of circulating miRNAs in PTC and evaluate the diagnostic value for differentiation of PTC from benign nodules. We first assessed the expression of miRNAs in patients with PTC, patients with benign nodules and healthy controls using a miRCURY LNA Array (n = 3 for each group). Expression of circulating miR-124-3p, miR-9-3p and miR-5691 was significantly up-regulated, while miR-4701 and miR-196b-5p were down-regulated in PTC patients. The dysregulation of miR-124-3p, miR-9-3p, miR-4701 and miR-196b-5p was further validated by qRT-PCR in fifty participants from each group. The expression of circulating miR-124-3p and miR-9-3p was significantly up-regulated in PTC patients. Both miR-124-3p and miR-9-3p could distinguish PTC from benign nodules with high sensitivity and specificity. There were no significant differences in the expression of circulating miR-4701 and miR-196b-5p between PTC patients and healthy controls. Nevertheless, patients with benign nodules showed a higher level of miR-196b-5p compared with that of PTC patients and healthy controls. ROC analysis indicated that miR-196b-5p had a good diagnostic value for differentiation of benign nodules from PTC. Our study suggested that miR-124-3p, miR-9-3p and miR-196b-5p may be potential signatures for differential diagnosis of thyroid nodules in eastern coastal areas of China.

Serum microRNA signatures and metabolomics have high diagnostic value in colorectal cancer using two novel methods

Recently, many new diagnostic biomarkers have been developed for colorectal cancer. We chose 2 methods with high diagnostic efficiency, the detection of serum microRNA and metabolomics based on gas chromatography/mass spectrometry (GC/MS), and aimed to establish appropriate models. We reviewed the diagnostic value of all microRNA identified by previous diagnostic tests. We selected appropriate microRNA to validate their diagnostic efficiency, and determined the optimal combination. We included 85 patients with colorectal cancer (CRC) and 78 healthy controls (HC) and detected the expression of the microRNA. GC/MS analysis was conducted, and we used 3 multivariate statistical methods to establish diagnostic models. The concentrations of carcinoembryonic antigen (CEA) and carbohydrate antigen 19‐9 (CA19‐9) were detected for comparison with the novel models. Ultimately, 62 published studies and 63 microRNA were included in this review. MiR‐21, miR‐29a, miR‐92a, miR‐125b and miR‐223 were selected to further validate their diagnostic value. The serum levels of the 5 microRNA in CRC patients were significantly higher than those in the HC. The combination of miR‐21, miR‐29a, miR‐92a and miR‐125b had the highest area under the curve (AUC) at 0.952, with a sensitivity of 84.7% and a specificity of 98.7%. The GC/MS analysis exhibited an excellent diagnostic value and the AUC reached 1.0. With regard to traditional biomarkers, the AUC of CEA and CA19‐9 were 0.808 and 0.705, respectively. The application prospects are good for microRNA and metabolomics as new diagnostic methods because of their high diagnostic value compared with traditional biomarkers.

Meta-analysis of microRNAs as potential biomarkers for detecting esophageal carcinoma in Asian populations

BACKGROUND:

An Increasing number of studies in the literature have shown that microRNAs (miRNAs) can be used as early diagnostic markers for esophageal carcinoma (EC), but their conclusions remain controversial. Hence, we performed this meta-analysis to evaluate the diagnostic accuracy of using miRNAs in EC and to provide an experimental basis for early diagnosis of the disease.

METHODS:

This meta-analysis included 39 Asian studies from 18 articles, which covered 3,708 EC patients and 2,689 healthy controls. We used a bivariate random-effects model, the chi-square test and the I² test to assess sensitivity and heterogeneity.

RESULTS:

Pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and diagnostic odds ratio of miRNAs for diagnosis of EC in Asians reached 0.798, 0.785, 3.705, 0.257 and 14.391, respectively. Additionally, the area under the summary receiver operating characteristic curve was 0.86. Subgroup analysis based on research country (China vs. Japan), sample types (plasma vs. serum) and miRNAs (single vs. multiple; singly reported miRNAs vs. repeatedly reported miRNAs) showed no significant difference in accuracy of diagnosis for each subgroup.

CONCLUSIONS:

MiRNAs can distinguish EC patients from healthy controls. Blood-based miRNAs have better diagnostic value in detecting EC than saliva-based miRNAs, whereas both serum and plasma are recommended for clinical specimens for miRNA detection.

Systematic literature review and clinical validation of circulating microRNAs as diagnostic biomarkers for colorectal cancer

Because patients with colorectal cancer (CRC) are usually diagnosed at an advanced stage and current serum tumor markers have limited diagnostic efficacy, there is an urgent need to identify reliable diagnostic biomarkers. To better define the diagnostic potential of microRNAs (miRNAs) for CRC, we performed a comprehensive evaluation of reported circulating CRC miRNA markers. After a systematic literature review, we selected 30 candidate miRNAs and used quantitative real-time polymerase chain reaction to examine their expression in a training cohort of 120 plasma samples (CRC vs healthy controls (HC) = 60:60). Expression data was confirmed in a validation cohort of 160 plasma samples (CRC vs HC = 80:80). We ultimately identified 5 dysregulated circulating miRNAs (miR-15b, miR-17, miR-21, miR-26b, and miR-145), of which miR-21 and miR-26b proved to have the best diagnostic performance in the training and validation cohorts, respectively. Based on these results, we propose a novel blood-based diagnostic model, integrating 5 CRC-related miRNAs and serum carcinoembryonic antigen (CEA), which provides better diagnostic performance than the combined 5 miRNAs, CEA alone, or any single miRNA. We propose that the novel CRC diagnostic model presented here will be useful for overcoming the limitations faced by current non-invasive diagnostic strategies.

Circulating miRNAs as novel diagnostic biomarkers in hepatocellular carcinoma detection: a meta-analysis based on 24 articles

The diagnostic value and suitability of circulating miRNAs for the detection of hepatocellular carcinoma have been inconsistent in the literature. A meta-analysis is used to systematically evaluate the diagnostic value of circulating miRNAs. Eligible studies were selected and the heterogeneity was assessed by subgroup analysis, meta-regression, and publication bias. After strictly and comprehensive screening, the source methods, internal reference and the cut-off values of the included miRNAs were first listed. Circulating miRNAs demonstrated a relatively good diagnostic value in hepatocellular carcinoma, In the subgroup analysis, diagnosis odds ratio showed a higher accuracy with multiple miRNAs than with a single miRNA as well as with serum types than plasma types. In addition, although miRNAs have many expression patterns, the high frequency expression miRNAs (miR-21, miR-199 and miR-122) might be more specific for the diagnosis of hepatocellular carcinoma.The sources of heterogeneity might be related to the number of miRNAs and the specimen types in meta-regression. Furthermore, it’s surprised that the pooled studies were first demonstrated publication bias (P < 0.05). In conclusion, multiple miRNAs in serum have a better diagnostic value, and the publication bias was stable. To validate the potential applicability of miRNAs in the diagnosis of hepatocellular carcinoma, more rigorous studies are needed to confirm these conclusions.

A proposed method for the relative quantification of levels of circulating microRNAs in the plasma of gastric cancer patients

Gastric cancer (GC) is the fifth most common type of malignancy and the third leading cause of cancer-associated mortality worldwide. It is necessary to identify novel methods aimed at improving the early diagnosis and treatment of GC. MicroRNA expression profiles in the plasma of patients with GC have demonstrated a potential use in the opportune diagnosis of this neoplasm. However, there are currently no standardized targets for use in the normalization of microRNA Cq values for different neoplasms. The present study tested two normalization approaches while analyzing plasma derived from patients with GC and non-atrophic gastritis. The first method utilized a panel of small nucleolar RNAs (snoRNAs) and a small nuclear RNA (snRNA) provided by a commercial array. The second normalization approach involved the use of hsa-miR-18a-5p and hsa-miR-29a-3p, which were identified by a stability analysis of the samples being tested. The results revealed that the snoRNAs and snRNA were not expressed in all samples tested. Only the stable microRNAs allowed a narrow distribution of the data and enabled the identification of specific downregulation of hsa-miR-200c-3p and hsa-miR-26b-5p in patients with GC. hsa-miR-200c-3p and hsa-miR-26b-5p have been previously linked to cancer, and a Kyoto Encyclopedia of Genes and Genomes analysis demonstrated that these microRNAs were associated with cell adhesion, cell cycle and cancer pathways.

Circulating miRNAs as novel potential biomarkers for esophageal squamous cell carcinoma diagnosis: a meta-analysis update

Early detection of esophageal squamous cell carcinoma (ESCC) is urgently needed to reduce the high morbidity and mortality of disease. Circulating microRNAs (miRNAs) are promising molecular biomarkers for ESCC prediction. We performed a comprehensive meta-analysis to systematically evaluate the diagnostic accuracy of circulating miRNAs in diagnosis of ESCC patients. Eligible studies were identified and assessed for quality employing multiple search strategies. Summary estimates for sensitivity, specificity, and other measures of accuracy of miRNAs in the diagnosis of ESCC were pooled using the bivariate random effects model. A total of 27 studies from 11 published articles were included in the meta-analysis. The overall sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio of circulating miRNAs for the diagnosis of ESCC were 79.9% (95% confidence intervals [CI]: 76.2%-83.1%), 81.3% (95% CI: 75.7-85.9), 4.27 (95%CI: 3.27-5.58), 0.25 (95% CI: 0.21-0.29), and 17.29 (95% CI: 12.01-24.86), respectively. The area under the summary receiver operating characteristic curve was 0.87 (95% CI: 0.84-0.90). The subgroup analyses based on research country (China vs. Japan), specimen type (plasma vs. serum), miRNAs profiling (single vs. multiple), and test method (screening vs. candidate; Taqman vs. SYBR) indicated no significant difference in the diagnostic accuracy of each subgroup. Collectively, our findings indicate that circulating miRNAs have significant potential to be used as noninvasive biomarkers for early detection of ESCC. Moreover, the subgroup analyses demonstrated the feasibility of using blood miRNAs as an ESCC diagnostic biomarker in Japanese and Chinese populations. Further, both plasma and serum are recommended as clinical specimens for miRNA detection. Further studies will be needed to validate these findings using larger numbers of patients.

Monitoring the HER2 copy number status in circulating tumor DNA by droplet digital PCR in patients with gastric cancer

BACKGROUND

We previously demonstrated the potential of circulating tumor DNA (ctDNA) for the amplification of detecting HER2 in patients with gastric cancer (GC). In the present study, we focused on the clinical courses of patients who developed recurrence with GC, and investigated the potential clinical utility of the ddPCR-based HER2 copy number (CN) as a marker for the temporal and/or spatial heterogeneities of GC during treatment progress.

METHOD

We enrolled 30 healthy volunteers and 60 patients with GC who underwent surgery, including 17 patients who developed recurrence. Using ribonuclease P RNA component H1 (RPPH1) as a reference gene, plasma HER2 to RPPH1 ratios (the HER2 ratio) were determined using ddPCR.

RESULTS

The preoperative plasma HER2 ratio correlated with the tumor HER2 status (p < 0.001), and sensitivity and specificity were 0.733 and 0.933, respectively. Analyses of plasma samples during the postoperative follow-up periods revealed that high plasma HER2 ratios were detected at the time of recurrence in 7 of 13 cases, which were diagnosed as being HER2 negative at the time of surgery. These results were supported by continuously increasing HER2 ratios thereafter with the progression of recurrent cancer.

CONCLUSION

The plasma HER2 ratio determined by ddPCR is a repeatable and noninvasive approach for real-time evaluations of the HER2 status to monitor the effects of treatments for patients with HER2-positive GC and enable treatment options for patients with HER2-negative GC but positive conversion of the HER2 status after recurrence.

Decreased miR-503 expression in gastric cancer is inversely correlated with serum carcinoembryonic antigen and acts as a potential prognostic and diagnostic biomarker

Background

Altered expression of miR-503 has been linked to human carcinogenesis. In this present study, we aimed to detect the potential for miR-503 as a novel biomarker for gastric cancer (GC) patients.

Materials and methods

The relative mRNA level of miR-503 in serum and tissue of 68 GC patients and serum of 32 healthy volunteers was determined by real-time reverse transcription quantitative polymerase chain reaction.

Results

The miR-503 level was significantly lower in the tissue and serum of GC than their counterparts (all P<0.01). Downregulation of miR-503 was found to be corrected with more aggressive tumor. Patients in the high-miR-503 group showed significantly better overall survival compared to the low-miR-503 group (P=0.021). The serum miR-503 level in GC was inversely correlated with carcinoembryonic antigen (CEA) (r=−0.624, P<0.001). Furthermore, the area under the receiver operating characteristic curve for miR-503 discriminating GC patients from healthy individuals was 0.889 (P=0.006), with a sensitivity of 96.8% and a specificity of 79.4%, higher than that of CEA (area under the receiver operating characteristic curve =0.681, P=0.048).

Conclusion

The present study suggests that the expression level of miR-503 may serve as prognostic and diagnostic biomarker for GC.

Plasma lncRNA-GACAT2 is a valuable marker for the screening of gastric cancer

Long non-coding RNAs (lncRNAs) are crucial in contributing to gastric tumorigenesis and development. However, the diagnostic value of the majority of lncRNAs in gastric cancer (GC) are not clear. The present study investigated the diagnostic value of gastric cancer associated transcript 2 (GACAT2), a lncRNA that is aberrantly expressed in GC tissues. A total of 343 plasma samples from 80 healthy individuals, 29 patients with gastric dysplasia (GD) and 117 paired preoperative and postoperative patients with GC were collected. Plasma GACAT2 levels were subsequently measured by reverse transcription-quantitative polymerase chain reaction. Finally, the associations between plasma GACAT2 levels and various clinicopathological features of patients with GC were assessed. The results demonstrated that plasma GACAT2 levels in preoperative patients with GC were significantly higher than those in the postoperative group (P=0.031). Compared with healthy individuals, plasma GACAT2 levels were significantly increased in patients with GD (P<0.001) and preoperative patients with GC (P=0.040). Moreover, the individual relative changes of plasma GACAT2 expression following surgery were significantly associated with lymphatic metastasis (P=0.034), distal metastasis (P=0.035) and perineural invasion (P=0.039). Therefore, the results of the current study suggest that plasma-based GACAT2 may be developed as a tumor marker to screen and predict the prognosis of GC patients.

Role of miRNAs and their potential to be useful as diagnostic and prognostic biomarkers in gastric cancer

Alterations in epigenetic control of gene expression play an important role in many diseases, including gastric cancer. Many studies have identified a large number of upregulated oncogenic miRNAs and downregulated tumour-suppressor miRNAs in this type of cancer. In this review, we provide an overview of the role of miRNAs, pointing to their potential to be useful as diagnostic and/or prognostic biomarkers in gastric cancer. Moreover, we discuss the influence of polymorphisms and epigenetic modifications on miRNA activity.

Extracellular MicroRNA in liquid biopsy: applicability in cancer diagnosis and prevention

One of the goals of contemporary cancer research is the development of new markers that facilitate earlier and non-invasive diagnosis. MicroRNAs are non-coding RNA molecules that regulate gene expression; studies have shown that their expression levels are altered in cancer. Recently, extra-cellular microRNAs have been detected in biological fluids and studied as possible cancer markers that can be detected by noninvasive procedures. In this review, we analyze the current understanding of extracellular miRNAs based on clinical studies to establish their possible use for the prevention of the most common tumors. Despite discrepancies among different studies of the same cancers, panels of specific extracellular microRNAs are emerging as a new tool for the secondary (selection of high-risk individuals to undergo screening) and tertiary (relapse) prevention of cancer.

Integrated Analysis of Dysregulated ncRNA and mRNA Expression Profiles in Humans Exposed to Carbon Nanotubes

BACKGROUND

As the application of carbon nanotubes (CNT) in consumer products continues to rise, studies have expanded to determine the associated risks of exposure on human and environmental health. In particular, several lines of evidence indicate that exposure to multi-walled carbon nanotubes (MWCNT) could pose a carcinogenic risk similar to asbestos fibers. However, to date the potential markers of MWCNT exposure are not yet explored in humans.

METHODS

In the present study, global mRNA and ncRNA expression profiles in the blood of exposed workers, having direct contact with MWCNT aerosol for at least 6 months (n = 8), were compared with expression profiles of non-exposed (n = 7) workers (e.g., professional and/or technical staff) from the same manufacturing facility.

RESULTS

Significant changes in the ncRNA and mRNA expression profiles were observed between exposed and non-exposed worker groups. An integrative analysis of ncRNA-mRNA correlations was performed to identify target genes, functional relationships, and regulatory networks in MWCNT-exposed workers. The coordinated changes in ncRNA and mRNA expression profiles revealed a set of miRNAs and their target genes with roles in cell cycle regulation/progression/control, apoptosis and proliferation. Further, the identified pathways and signaling networks also revealed MWCNT potential to trigger pulmonary and cardiovascular effects as well as carcinogenic outcomes in humans, similar to those previously described in rodents exposed to MWCNTs.

CONCLUSION

This study is the first to investigate aberrant changes in mRNA and ncRNA expression profiles in the blood of humans exposed to MWCNT. The significant changes in several miRNAs and mRNAs expression as well as their regulatory networks are important for getting molecular insights into the MWCNT-induced toxicity and pathogenesis in humans. Further large-scale prospective studies are necessary to validate the potential applicability of such changes in mRNAs and miRNAs as prognostic markers of MWCNT exposures in humans.

Emerging blood-based biomarkers for detection of gastric cancer

Early detection and efficient monitoring of tumor dynamics are prerequisites for reducing disease burden and mortality, and for improving the management of patients with gastric cancer (GC). Blood-based biomarker assays for the detection of early-stage GC could be of great relevance both for population-wide or risk group-based screening programs, while circulating biomarkers that reflect the genetic make-up and dynamics of the tumor would allow monitoring of treatment efficacy, predict recurrences and assess the genetic heterogeneity of the tumor. Recent research to identify blood-based biomarkers of GC has resulted in the identification of a wide variety of cancer-associated molecules, including various proteins, autoantibodies against tumor associated antigens, cell-free DNA fragments, mRNAs and various non-coding RNAs, circulating tumor cells and cancer-derived extracellular vesicles. Each type of these biomarkers provides different information on the disease status, has different advantages and disadvantages, and distinct clinical usefulness. In the current review, we summarize the recent developments in blood-based GC biomarker discovery, discuss the origin of various types of biomarkers and their clinical usefulness and the technological challenges in the development of biomarker assays for clinical use.

May Circulating microRNAs be Gastric Cancer Diagnostic Biomarkers?

Gastric cancer (GC) is the third leading cause of cancer-related deaths. More than 80% of the diagnosis was made at the advanced stages of the disease, highlighting the urgent demand for novel biomarkers that can be used for early detection. Recently, a number of studies suggest that circulating microRNAs (miRNAs) could be potential biomarkers for GC diagnosis. Cancer-related circulating miRNAs, as well as tissue miRNAs, provide a hopeful prospect of detecting GC at early stages, and the prospective participation of miRNAs in biomarker development will enhance the sensitivity and specificity of diagnostic tests for GC. As miRNAs in blood are stable, their potential value as diagnostic biomarkers in GC has been explored over the past few years. However, due to the inconsistent or sometimes conflicting reports, large-scale prospective studies are needed to validate their potential applicability in GC diagnosis. This review summarizes the current development about potential miRNA biomarkers for GC diagnosis and the obstacles hindering their clinical usage.

Gastric Cancer Risk in Patients with Helicobacter pylori Infection and Following Its Eradication

As Helicobacter pylori is a first-class carcinogen, eradication of the infection would be expected to be a beneficial measure for the (primary) prevention of gastric cancer. Given the natural history of gastric cancer, it is plausible that eradication before gastric atrophy sets in offers the best chance for cancer risk reduction. The beneficial effects of eradication may, nevertheless, still be achievable in more advanced disease. The reversibility of inflammatory lesions has been supported by undeniable evidence; the regression of mucosal atrophy/metaplasia has also been confirmed by several recent histologic studies.

Analysis of Deregulated microRNAs and Their Target Genes in Gastric Cancer

BACKGROUND

MicroRNAs (miRNAs) are widely studied non-coding RNAs that modulate gene expression. MiRNAs are deregulated in different tumors including gastric cancer (GC) and have potential diagnostic and prognostic implications. The aim of our study was to determine miRNA profile in GC tissues, followed by evaluation of deregulated miRNAs in plasma of GC patients. Using available databases and bioinformatics methods we also aimed to evaluate potential target genes of confirmed differentially expressed miRNA and validate these findings in GC tissues.

METHODS

The study included 51 GC patients and 51 controls. Initially, we screened miRNA expression profile in 13 tissue samples of GC and 12 normal gastric tissues with TaqMan low density array (TLDA). In the second stage, differentially expressed miRNAs were validated in a replication cohort using qRT-PCR in tissue and plasma samples. Subsequently, we analyzed potential target genes of deregulated miRNAs using bioinformatics approach, determined their expression in GC tissues and performed correlation analysis with targeting miRNAs.

RESULTS

Profiling with TLDA revealed 15 deregulated miRNAs in GC tissues compared to normal gastric mucosa. Replication analysis confirmed that miR-148a-3p, miR-204-5p, miR-223-3p and miR-375 were consistently deregulated in GC tissues. Analysis of GC patients' plasma samples showed significant down-regulation of miR-148a-3p, miR-375 and up-regulation of miR-223-3p compared to healthy subjects. Further, using bioinformatic tools we identified targets of replicated miRNAs and performed disease-associated gene enrichment analysis. Ultimately, we evaluated potential target gene BCL2 and DNMT3B expression by qRT-PCR in GC tissue, which correlated with targeting miRNA expression.

CONCLUSIONS

Our study revealed miRNA profile in GC tissues and showed that miR-148a-3p, miR-223-3p and miR-375 are deregulated in GC plasma samples, but these circulating miRNAs showed relatively weak diagnostic performance as sole biomarkers. Target gene analysis demonstrated that BCL2 and DNMT3B expression in GC tissue correlated with their targeting miRNA expression.