A five-microRNA panel in plasma was identified as potential biomarker for early detection of gastric cancer

microRNA: Diagnostic Perspective

Biomarkers are biological measures of a biological state. An ideal marker should be safe and easy to measure, cost efficient, modifiable with treatment, and consistent across gender and ethnic groups. To date, none of the available biomarkers satisfy all of these criteria. In addition, the major limitations of these markers are low specificity, sensitivity, and false positive results. Recently identified, microRNAs (miRNAs) are endogenous, evolutionarily conserved small non-coding RNA (about 22–25 nt long), also known as micro-coordinators of gene expression, which have been shown to be an effective tools to study the biology of diseases and to have great potential as novel diagnostic and prognostic biomarkers with high specificity and sensitivity. In fact, it has been demonstrated that miRNAs play a pivotal role in the regulation of a wide range of developmental and physiological processes and their deficiencies have been related to a number of disease. In addition, miRNAs are stable and can be easily isolated and measured from tissues and body fluids. In this review, we provide a perspective on emerging concepts and potential usefulness of miRNAs as diagnostic markers, emphasizing the involvement of specific miRNAs in particular tumor types, subtypes, cardiovascular diseases, diabetes, infectious diseases, and forensic test.

miRNA-regulated gene expression differs in celiac disease patients according to the age of presentation

Celiac disease is an intestinal disease which shows different symptoms and clinical manifestations among pediatric and adult patients. These variations could be imputable to age-related changes in gut architecture and intestinal immune system, which could be characterized by gene expression differences possibly regulated by miRNAs. We analyzed a panel of miRNAs and their target genes in duodenal biopsies of Marsh 3AB and 3C pediatric celiac patients, compared to controls. Moreover, to assess variation of expression in plasma samples, we evaluated circulating miRNA levels in controls and patients at diagnosis or on gluten-free diet. We detected a decreased miR-192-5p expression in celiac patients, but no variations in NOD2 and CXCL2, targets previously identified in adults. Conversely, we detected a significant increase in mRNA and protein levels of another target, MAD2L1, protein related to cell cycle control. miR-31-5p and miR-338-3p were down-regulated and their respective targets, FOXP3 and RUNX1, involved in Treg function, resulted up-regulated in celiac patients. Finally, we detected, in celiac patients, an increased expression of miR-21-5p, possibly caused by a regulatory loop with its putative target STAT3, which showed an increased activation in Marsh 3C patients. The analysis of plasma revealed a trend similar to that observed in biopsies, but in presence of gluten-free diet we could not detect circulating miRNAs values comparable to controls. miRNAs and their gene targets showed an altered expression in duodenal mucosa and plasma of celiac disease pediatric patients, and these alterations could be different from adult ones.

Combination of miRNA and RNA functions as potential biomarkers for gastric cancer

Gastric cancer (GC) is the second leading cause of cancer-related death in the world. The optimal treatment regimens for GC depend on tumor stage, histopathological subtype, and other factors. The detection of tumor biomarkers is a quick way to get information of the tumor state. In this study, new biomarkers are detected for GC diagnostic and prognostic purposes. A total of 305 cases of diagnosed gastric adenocarcinoma were enrolled, microRNAs (miRNAs) and their transcriptome sequencing data were obtained from the "The Cancer Genome Atlas." Blood samples were collected from GC patients before surgery and therapy. The miRNA levels and the expression of RNA were detected by real-time RT-PCR. Receiver operating characteristic analysis was used to evaluate the sensitivity and specificity of biomarkers. The combining predictors were established with the logistic regression analysis. Hundreds of miRNA were with higher area under curve (AUC) than 0.5; among them, nine miRNAs were with the highest AUC more than 0.90 and displayed strong diagnostic value. Moreover, the mir-17 level was correlated with tumor stage (p = 0.029), while mir-133b, mir-133a-2, and mir-1-2 levels were significantly correlated with race, tumor pathologic, and tumor stage (p < 0.05). The combination biomarker (mir-181a-1/KAT2B with a sensitivity of 95.83 % and specificity of 94.12 %) could be used as an independent diagnostic indicator for GC patients. For GC patients, mir-17, mir-133b, mir-133a-2, and mir-1-2 appear to be a potential novel predictor of tumor stage and preoperative and intraoperative diagnosis. The combination of miRNA and mRNA such as mir-181a-1/KAT2B (with a sensitivity of 95.83 % and specificity of 94.12 %) showed significant improvement in the diagnostic accuracy.

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.

Biomarkers for Helicobacter pylori infection and gastroduodenal diseases

Helicobacter pylori infection is a major cause of gastric cancer. Although identifying H. pylori infected subjects is the first approach for delineating the high-risk population for gastric cancer, the presence of H. pylori antibodies is not sufficient for gastric cancer screening. Among H. pylori infected subjects, only a minority of infected individuals develop gastric cancer. Serologic markers of H. pylori infection can serve as potential predictors for the development of gastric cancer. Serum or urinary H. pylori antibodies, cytotoxin-associated gene A antibodies, pepsinogen and microRNAs were reported to be associated with precancerous lesions or gastric cancer. In this review, we summarized the utilities and limitations of each strategy.

Diagnostic value of a plasma microRNA signature in gastric cancer: a microRNA expression analysis

The differential expression of microRNAs (miRNAs) in plasma of gastric cancer (GC) patients may serve as a diagnostic biomarker. A total of 33 miRNAs were identified through the initial screening phase (3 GC pools vs. 1 normal control (NC) pool) using quantitative reverse transcription polymerase chain reaction (qRT-PCR) based Exiqon panel (miRCURY-Ready-to-Use-PCR-Human-panel-I + II-V1.M). By qRT-PCR, these miRNAs were further assessed in training (30 GC VS. 30 NCs) and testing stages (71 GC VS. 61 NCs). We discovered a plasma miRNA signature including five up-regulated miRNAs (miR-185, miR-20a, miR-210, miR-25 and miR-92b), and this signature was evaluated to be a potential diagnostic marker of GC. The areas under the receiver operating characteristic curve of the signature were 0.86, 0.74 and 0.87 for the training, testing and the external validation stages (32 GC VS. 18 NCs), respectively. The five miRNAs were consistently dysregulated in GC tissues (n = 30). Moreover, miR-185 was decreased while miR-20a, miR-210 and miR-92b were increased in arterial plasma (n = 38). However, none of the miRNAs in the exosomes showed different expression between 10 GC patients and 10 NCs. In conclusion, we identified a five-miRNA signature in the peripheral plasma which could serve as a non-invasive biomarker in detection of GC.

Altered levels of circulating miRNAs are associated Schistosoma japonicum infection in mice

Background

Dioecious flatworms of the genus Schistosoma causes schistosomiasis, which is a major public health problem in developing countries. Acquiring detailed knowledge of schistosome-host interactions may aid in the development of novel strategies for schistosomiasis control. MicroRNAs (miRNAs) are involved in processes such as development, cell proliferation, metabolism, and signal transduction. Circulating miRNAs not only serve as a novel class of biomarkers of many diseases but also regulate target gene expression in recipient cells, which are similar to hormones.

Methods

In the present study, we used miRNA microarrays to determine the profile of circulating miRNAs associated with S. japonicum infection of mice. The biological functions of the altered levels of miRNAs and their target genes were predicted using bioinformatics. Expression levels of selected miRNAs and their target genes were further analyzed by quantitative RT-PCR.

Results

Our study identified 294 and 189 miRNAs in infected mice that were expressed in two independent experiments at levels ≥ 2-fold higher or ≤ 0.5-fold lower, respectively, compared with uninfected mice. Thirty-six of the same miRNAs were detected in these analyses. Moreover, pathway analyses indicated that most of these miRNAs are putatively involved in signaling pathways associated with pathogenesis, such as Wnt and MAPK signaling. Further, we show an inverse correlation between the circulating levels of these miRNAs and their target genes, suggesting that changes in miRNA expression may cause aberrant expression of genes such as Creb1 and Caspase-3 in mice infected with S. japonicum.

Conclusions

Our study shows significant differences in the levels of circulating miRNAs between S. japonicum infected mice and uninfected mice. In particular, the altered levels of miR-706 and miR-134-5p were associated with altered levels of expression of the Caspase-3 and Creb1 genes, respectively, suggesting that circulating miRNAs may serve as important mediators of the pathology of hepatic schistosomiasis. Additionally, our results are expected to provide new insights for further understanding the mechanisms of schistosome-host interaction that may facilitate in the development of novel interventions for alleviating the symptom of S. japonicum infection as well as for preventing and treating schistosomiasis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-015-0806-5) contains supplementary material, which is available to authorized users.

miR-107 and miR-25 simultaneously target LATS2 and regulate proliferation and invasion of gastric adenocarcinoma (GAC) cells

Although a series of oncogenes and tumor suppressors were identified in the pathological development of gastric adenocarcinoma (GAC), the underlying molecule mechanism were still not fully understood. The current study explored the expression profile of miR-107 and miR-25 in GAC patients and their downstream regulative network. qRT-PCR analysis was performed to quantify the expression of these two miRNAs in serum samples from both patients and healthy controls. Dual luciferase assay was conducted to verify their putative bindings with LATS2. MTT assay, cell cycle assay and transwell assay were performed to explore how miR-107 and miR-25 regulate proliferation and invasion of gastric cancer cells. Findings of this study demonstrated that total miR-107 or miR-25 expression might be overexpressed in gastric cancer patients and they can simultaneously and synchronically regulate LATS2 expression, thereby affecting gastric cancer cell growth and invasion. Therefore, the miR-25/miR-107-LATS2 axis might play an important role in proliferation and invasion of the gastric cancer cells.

Expression and prognostic value of miR-486-5p in patients with gastric adenocarcinoma

MicroRNA (miR)-486-5p expression is often reduced in human cancers. However, its expression in gastric carcinoma and its relation to clinicopathological features and prognosis are unclear. Tissue microarrays were constructed from 84 patients with gastric adenocarcinoma (GC) who were undergoing radical resection. miR-486-5p expression was detected by miRNA-locked nucleic acid in situ hybridization, and its correlations with clinicopathological features and overall survival were analyzed. Bioinformatic studies predict that fibroblast growth factor 9 (FGF9) is a potential target gene of miR-486-5p. miR-486-5p was mainly located in the cytoplasm of GC cells and neighboring normal tissues. Compared with paracancerous normal tissue, miR-486-5p expression was decreased in 63.1% (53/84) of the GC samples, increased in 32.1% (27/84) and unchanged in 4.8% (4/84). FGF9 expression was decreased in 69.0% (58/84) of GC samples and increased in 31.0% (26/84) compared with normal paracancerous tissues using immunohistochemical analysis. Low or unchanged miR-486-5p expression (P = 0.002), tumor stage (P = 0.001), tumor status (P = 0.001), node status (P = 0.001), tumor size (P = 0.004), and depth of tumor invasion (P = 0.013) were significant negative prognostic predictors for overall survival in patients with GC. After stratification according to American Joint Committee on Cancer (AJCC) stage, low/unchanged miR-486-5p expression remained a significant predictor of poor survival in stage II (P = 0.024) and stage III (P = 0.003). Cox regression analysis identified the following predictors of poor prognosis: tumor status (hazard ratio [HR], 7.19; 95% confidence interval [CI], 1.75–29.6; P = 0.006), stage (HR, 2.62; 95%CI, 1.50–4.59; P = 0.001), lymph node metastasis (HR, 2.52; 95% CI, 1.27–4.99; P = 0.008), low/unchanged miR-486-5p (HR, 2.47; 95% CI, 1.35–4.52; P = 0.003), high level of FGF9 (HR, 2.41; 95% CI, 1.42–4.09; P = 0.001) and tumor size (HR, 2.50; 95% CI, 1.30–4.82; P = 0.006). Low or unchanged expression of miR-486-5p compared with neighboring normal tissues was associated with a poor prognosis, while high expression was associated with a good prognosis in GC. miR-486-5p may thus be useful for evaluating prognosis and may provide a novel target treatment in patients with GC.

Identification of miR-93 as a suitable miR for normalizing miRNA in plasma of tuberculosis patients

Tuberculosis (TB) remains a major public health issue. New tests to aid diagnoses and monitor the response to therapy are urgently required. There is growing interest in the use of microRNA (miRNA) profiles as diagnostic, prognostic or predictive markers in a range of clinical and infectious diseases, including Mycobacterium tuberculosis infection, however, challenges exist to accurately normalise miRNA levels in cohorts. This study examined the appropriateness of 12 miRs and RNU6B to normalise circulating plasma miRNA levels in individuals with active TB from 2 different geographical and ethnic regions. Twelve miRs (let-7, miR-16, miR-22, miR-26, miR-93, miR-103, miR-191, miR-192, miR-221, miR-423, miR-425 and miR-451) and RNU6B were selected based on their reported production by lung cells, expression in blood and previous use as a reference miRNA. Expression levels were analysed in the plasma of newly diagnosed TB patients from Australia and China compared with individuals with latent TB infection and healthy volunteers. Analysis with both geNorm and NormFinder software identified miR-93 as the most suitable reference miR in both cohorts, either when analysed separately or collectively. Interestingly, there were large variations in the expression levels of some miRs, in particular miR-192 and let-7, between the two cohorts, independent of disease status. These data identify miR-93 is a suitable reference miR for normalizing miRNA levels in TB patients, and highlight how environmental, and possibly ethnic, factors influence miRNA expression levels, demonstrating the necessity of assessing the suitability of reference miRs within the study population.

MiR-16 family as potential diagnostic biomarkers for cancer: a systematic review and meta-analysis

BACKGROUND

Cancer is a main public health problem all over the world with its high morbidity and mortality. MicroRNA-16 (miRNA-16, miR-16) family members have been considered as potential biomarkers in cancer diagnosis in several previous studies, but their results were inconsistent.

OBJECTIVE

The present meta-analysis was conducted to assess the diagnostic efficacy of miR-16 family for cancer systematically.

METHODS

Multiple search strategies and random-effects model were used. Pooled sensitivity, specificity and other parameters were calculated. Totally, 1,259 cancer patients and 855 controls from 16 articles were enrolled in this meta-analysis.

RESULTS

The pooled results for sensitivity, specificity, positive likelihood ratios (PLR), negative likelihood ratios (NLR), diagnostic odds ratio (DOR) and the area under the curve (AUC) were 0.80 (95% CI: 0.73-0.85), 0.77 (95% CI: 0.70-0.84), 3.5 (95% CI: 2.5-5.0), 0.26 (95% CI: 0.19-0.36), 14 (95% CI: 8-25) and 0.86 (95% CI: 0.82-0.88), respectively. Our subgroup analyses indicated miR-16 family assay was more appropriate in Asian populations.

CONCLUSIONS

Our findings demonstrated that miR-16 family members have a relatively high value as promising biomarkers in diagnosing cancers. Nevertheless, the clinical application of miR-16 family profiling for cancers diagnosis still needs further large-scale studies and additional improvements of substantiation.

Serum miR-125a-5p, miR-145 and miR-146a as diagnostic biomarkers in non-small cell lung cancer

BACKGROUND

Lung cancer is becoming the leading cause of cancer-related deaths with high mortality worldwide and in China as well. Non-small-cell lung cancer (NSCLC) is the most common type of lung cancer accounting for approximately 85% of all cases. Over 70% of cases are at loco-regionally advanced stages or have distant metastasis at the time of presentation with subsequently poor prognosis. MiRNAs are stable molecules in blood and used as biomarkers for the early diagnosis of various malignancy. The purpose of this study was to evaluate whether circulating miR-125a-5p, miR-145 and miR-146a could be used as biomarkers for the diagnosis of NSCLC through measuring their expression and assess their relationship with clinical pathological factors.

METHODS

Expression levels of serum miR-125a-5p, miR-145 and miR-146a were detected in 70 pairs of NSCLC patients and healthy controls using quantitative real-time PCR analysis.

RESULTS

Serum miR-125a-5p, miR-145 and miR-146a were overexpressed in NSCLC patients compared with healthy controls. Their values of the area under the receiver -operating characteristic curve (AUC-ROC) were 0.71, 0.84 and 0.78. Optimal sensitivity and specificity were 73.53% and 55.71%, 92.75% and 61.43%, 84.06% and 58.57%, respectively in differentiating NSCLC patients from healthy controls.

CONCLUSIONS

These preliminary data suggest that serum miR-125a-5p, miR-145 and miR-146a may be useful noninvasive biomarkers for the clinical diagnosis of NSCLC.

Circulating miRNAs: roles in cancer diagnosis, prognosis and therapy

MicroRNAs (miRNAs) belong to a class of small non-coding RNAs that regulate numerous biological processes by targeting a broad set of messenger RNAs. Recently, miRNAs have been detected in remarkably stable forms in many types of body fluids. A comparison between cancer patients and healthy individuals has clearly shown that certain types of circulating miRNAs are associated with cancer initiation and progression. Research on miRNA-based biomarkers has witnessed phenomenal growth, owing to the non-invasive nature of miRNA-based screening assays and their sensitivity and specificity in detecting cancers. Consequently, a considerable effort has been devoted to identify suitable miRNAs for cancer diagnosis and also decode the information carried by circulating miRNAs. This review highlights the current studies that focus on the identification of circulating miRNA-based diagnostic and prognostic markers, for the most prevalent types of cancer. Additionally, the review also provides an insight into the putative functions of miRNAs, and attempts to delineate the mechanisms through which they are released into the bloodstream. Moreover, methodologies and strategies for identification of circulating miRNAs in cancers are summarized. Finally, potential strategies for circulating miRNA-based cancer therapies are proposed.

MicroRNA-451 plays a role in murine embryo implantation through targeting Ankrd46, as implicated by a microarray-based analysis

OBJECTIVE

To determine the potential microRNA (miRNA) regulators of embryo implantation, as a continuation of genomic and proteomic research.

DESIGN

Laboratory animal research.

SETTING

University hospital laboratory.

ANIMAL(S)

Adult healthy female C57BL6/J mice (age 6-8 weeks, nonfertile, weighing 18-20 g each).

INTERVENTION(S)

Female mice were mated naturally with fertile males to produce pregnancy. Luminal epithelium was collected by laser-capture microdissection during the implantation period. Mouse models of pseudopregnancy, delayed implantation, and artificial decidualization were established.

MAIN OUTCOME MEASURE(S)

The miRNA profile in luminal epithelium was clarified by microarray analysis and validated by real-time reverse transcription polymerase chain reaction (qRT-PCR) in a series of models. Target genes were predicted and confirmed by luciferase activity assay. The role of miRNA in implantation was examined by loss-of-function and gain-of-function of miRNA in vitro and in vivo.

RESULT(S)

A total of 29 and 15 miRNAs were up- and down-regulated, respectively, during the implantation period; 11 of these miRNAs were validated by qRT-PCR. The profile of miR-451 was clarified in a series of models. A dual-luciferase activity assay showed that Ankrd46 was a target gene of miR-451. Loss-of-function by LV-miR-451 sponge or miR-451 inhibitor led to a reduced number of embryo implantations, but had little effect on fertilization.

CONCLUSION(S)

miR-451 was specifically up-regulated during the implantation period, and it may play a major role in embryo implantation by targeting Ankrd46.

Circulating microRNA-21 as a biomarker for the detection of various carcinomas: an updated meta-analysis based on 36 studies

Cancer is a class of diseases with high mortality rate, characterized by unregulated cell growth. Early diagnosis of cancer is currently the most effective method to prevent cancer development and improve the survival rate of patients. Traditional diagnostic methods such as biopsy usually provoke discomfort and unpleasant experience. Recently, microRNAs (miRNAs) were widely reported to be potential biomarkers to detect cancers without invasiveness. MicroRNA-21 (miRNA-21, miR-21) is one of the most prevalent miRNAs. This meta-analysis aims to make a comprehensive analysis of the potential role of circulating miR-21 as a biomarker in human carcinoma diagnosis. A total of 36 articles involving 2920 cancer patients and 1986 healthy controls with regard to the diagnostic value of the circulating miR-21 for cancer detection were selected from online bibliographic databases. For pooled analysis, the sensitivity, specificity, and other basic characteristics were extracted from the 36 included articles. Then, bivariate random-effects model was selected to gain pooled results. Furthermore, to explore the sources of heterogeneity, we conducted stratified and meta-regression analyses based on different race/sample groups. The pooled characteristics of all included articles were as follows: sensitivity, 0.78 (95% confidence intervals (CI), 0.73-0.82); specificity, 0.82 (95% CI, 0.79-0.86); positive likelihood ratio (PLR), 4.4 (95% CI, 3.6-5.4); negative likelihood ratio (NLR), 0.26 (95% CI, 0.21-0.33); diagnostic odds ratio (DOR), 17 (95% CI, 12-24); and area under the curve (AUC), 0.87 (95% CI, 0.84-0.90). The subgroup analyses results based on different ethnic populations revealed that the diagnostic accuracy of miR-21 tends to be higher in Asian populations than in Caucasian populations. Furthermore, another subgroup analysis performed on sample types suggested that the serum-based specimen used in cancer diagnosis appeared to be more accurate than the plasma-based specimen. Our meta-analysis shows that the circulating miR-21 may be a potential biomarker as diagnostic tool for early-stage cancer diagnosis.

Serum MicroRNAs as Diagnostic Biomarkers for Macrosomia

BACKGROUND

Macrosomia is defined as an infant's birth weight of more than 4000 g. Although microRNAs (miRNAs) have been implicated in the pathogenesis of various diseases, the associations between serum miRNAs and macrosomia have been rarely reported.

METHODOLOGY

We used the Taqman Low Density Array followed by quantitative reverse transcriptase polymerase chain reaction assays to screen for miRNAs associated with macrosomia using serum samples collected 1 week before delivery.

RESULTS

Profiling results showed that 1 miRNA was significantly upregulated and 10 miRNAs were significantly downregulated in serum samples of macrosomia (ΔΔCt > 3-fold). The expression levels of miR-21 were significantly decreased in macrosomia as compared to the controls in the third trimester. Receiver operating characteristic (ROC) curve analyses showed that the area under the ROC curve for miR-21 was 67.7% (sensitivity = 66.7% and specificity = 70.0%).

CONCLUSIONS

miR-21 in maternal serum is differentially expressed between macrosomia and controls, and miR-21 could be used as a candidate biomarker to predict macrosomia.

Circulating miRNAs in cancer: from detection to therapy

Since the discovery of circulating microRNAs (miRNAs) in body fluids, an increasing number of studies have focused on their potential as non-invasive biomarkers and as therapeutic targets or tools for many diseases, particularly for cancers. Because of their stability, miRNAs are easily detectable in body fluids. Extracellular miRNAs have potential as biomarkers for the prediction and prognosis of cancer. Moreover, they also enable communication between cells within the tumor microenvironment, thereby influencing tumorigenesis. In this review, we summarize the progresses made over the past decade regarding circulating miRNAs, from the development of detection methods to their clinical application as biomarkers and therapeutic tools for cancer. We also discuss the advantages and limitations of different detection methods and the pathways of circulating miRNAs in cell-cell communication, in addition to their clinical pharmacokinetics and toxicity in human organs. Finally, we highlight the potential of circulating miRNAs in clinical applications for cancer.

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

OBJECTIVE

MicroRNAs (miRNAs) have become the focus of most recent efforts in cancer research. However, there have been inconsistencies in the literature regarding the suitability of circulating miRNAs for early detection of gastrointestinal cancers. This study aims to assess the diagnostic performance of circulating miRNAs in detection of gastrointestinal cancer through a meta-analysis.

METHODS

Eligible studies were selected by conducting a systematic literature search of public databases. The sensitivity and specificity were used to plot the summary receiver operator characteristic (SROC) curve and calculate the area under the SROC curve (AUC). The between-study heterogeneity was evaluated by Q test and I2 statistics. Subgroup analyses and meta-regression were further performed to explore the potential sources of heterogeneity. All analyses were performed using the STATA 12.0 software.

RESULTS

A total of 107 studies from 42 articles were included for the meta-analysis according to the inclusion criteria. The overall analysis of all gastrointestinal cancers showed that circulating miRNAs have a relatively good diagnostic performance in gastrointestinal cancers, with a sensitivity of 0.75, a specificity of 0.81 and an AUC of 0.85. In addition, subgroup analyses based on different type of miRNA assay suggested that single-miRNA assay displayed a relatively low diagnostic performance with the AUC values of 0.84 for gastric cancer (GC) and 0.79 for colorectal cancer (CRC), while multiple-miRNAs assay significantly improved the diagnosing accuracy with AUC rising to 0.92 for GC and 0.89 for CRC. Another interesting finding was that plasma-based miRNA assay reach a higher accuracy compared with serum-based one for GC, while opposite conclusion was drawn for CRC.

CONCLUSIONS

In conclusion, circulating miRNAs, particularly the combination of multiple miRNAs, may present as promising biomarkers for the diagnosis of gastrointestinal cancers. Further large-scale prospective studies are necessary to validate their potential applicability in human cancer diagnosis.

Early second-trimester serum microRNAs as potential biomarker for nondiabetic macrosomia

Background. Macrosomia has become a worldwide problem with the rapid economic growth in the past few years. However, the detailed mechanism of how the macrosomia happened remains unknown. Growing evidence indicates that miRNAs are involved in maintaining metabolic homeostasis. We hypothesized that serum miRNAs are potential biomarkers for macrosomia. Methods. We performed miRNAs profiling using TLDA chips in the discovery phase in two pooled samples from 30 cases and 30 controls, respectively. Individual qRT-PCR was conducted for the discovery phase samples. To confirm the results, we detected the miRNAs which were differentially expressed in the microarray assays and individual qRT-PCR in external validation phase with another 30 cases and 30 controls. Results. In the discovery stage, miR-194 and miR-376a expression levels were significantly different between macrosomia group and controls (P = 0.048 for miR-194 and P = 0.018 for miR-376a, resp.). Further evaluation of the two miRNAs on a total of 120 serum samples showed that the miR-376a remains significantly lower in macrosomia (P = 0.032). Receiver operating characteristic curve analyses showed that the area under curve for miR-376a was 67.8% (sensitivity = 96.7% and specificity = 40.0%). Conclusions. Serum miR-376a may serve as a potential noninvasive biomarker in detecting macrosomia.

Catalpol suppresses proliferation and facilitates apoptosis of OVCAR-3 ovarian cancer cells through upregulating microRNA-200 and downregulating MMP-2 expression

Catalpol is expected to possess diverse pharmacological actions including anti-cancer, anti-inflammatory and hypoglycemic properties. Matrix metalloproteinase-2 (MMP-2) is closely related to the pathogenesis of ovarian cancer. In addition, microRNA-200 (miR-200) can modulate phenotype, proliferation, infiltration and transfer of various tumors. Here, OVCAR-3 cells were employed to investigate whether the effect of catalpol (25, 50 and 100 μg/mL) promoted apoptosis of ovarian cancer cells and to explore the potential mechanisms. Our results demonstrate that catalpol could remarkably reduce the proliferation and accelerate the apoptosis of OVCAR-3 cells. Interestingly, our findings show that catalpol treatment significantly decreased the MMP-2 protein level and increased the miR-200 expression level in OVCAR-3 cells. Further, microRNA-200 was shown to regulate the protein expression of MMP-2 in OVCAR-3 cells. It is concluded that catalpol suppressed cellular proliferation and accelerated apoptosis in OVCAR-3 ovarian cancer cells via promoting microRNA-200 expression levels and restraining MMP-2 signaling.

Circulating microRNA-182 in plasma and its potential diagnostic and prognostic value for pancreatic cancer

MicroRNA-182 (miR-182) is overexpressed in several tumors and is found to be associated with adverse clinical characteristics. However, less information on the circulating miR-182 in pancreatic cancer (PCa) is available. The aim of this study was to detect the circulating miR-182 in plasma and to explore its potential diagnostic and prognostic value in PCa. Real-time quantitative PCR was employed to detect circulating miR-182 from 109 PCa and 38 chronic pancreatitis (CP) as well as 50 healthy controls. Our findings revealed that the level of circulating miR-182 in PCa patients was higher than that in CP patients and healthy controls (both at P < 0.05), which was significantly associated with clinical stages (P < 0.001) and lymph node metastasis (P = 0.018). The area under the receiver operating characteristic curve was 0.775, and the optimal cutoff value was 1.63, thus providing a sensitivity of 64.1 % and a specificity of 82.6 %. The diagnosis capability of circulating miR-182 was significantly higher than that of CA19-9, and the combination of two molecules had higher diagnosis capacity (sensitivity of 84.68 % and specificity of 86.77 %). Kaplan-Meier analysis demonstrated that the elevated circulating miR-182 was closely correlated with both shorten overall survival (OS) (P < 0.001) and disease-free survival (DFS) (P < 0.001). Cox analysis indicated that it was an independent prognostic factor for OS and DFS. Our data suggest that circulating miR-182 may be a potential and useful noninvasive tumor marker for diagnosis and prognosis of pancreatic cancer.

Clinical significance of abnormal expression of miR-92a in serum of gastric cancer patients

AIM: To investigate the abnormal expression of miR-92a in serum of gastric cancer patients and to assess its clinical significance.

METHODS: The expression of miR-92a in serum of 100 gastric cancer patients and 100 normal controls was detected by real-time quantitative PCR. The correlation between miR-92a expression and clinicopathological features of gastric cancer was analyzed.

RESULTS: The expression level of miR-92a in serum of gastric cancer patients was significantly higher than that in normal controls (4.58 ± 0.53 vs 4.14 ± 0.41, P = 0.002). For detecting gastric cancer, the area under the receiver operating characteristic (ROC) curve of miR-92a was 0.737, with a sensitivity of 64.0% and a specificity of 82.0%. Serum miR-92a expression was significantly associated with lymph node metastasis, distant metastasis, clinical stage and survival duration (P = 0.000, 0.010, 0.008, 0.024), but not with sex, age or tumor differentiation (P = 0.221, 0.656, 0.051).

CONCLUSION: Serum miR-92a testing may be helpful in the diagnosis and evaluation of prognosis of gastric cancer.

The fusion of two worlds: non-coding RNAs and extracellular vesicles--diagnostic and therapeutic implications (Review)

The role of the extracellular non-coding RNAs, particularly microRNAs present in tumor-derived extravesicles, has been intensively exploited in human cancer as a promising tool for diagnostic and prognostic purposes. Current knowledge on exosomes shows an important role not only as vehicles in the intercellular communication, but the transfer of their content can specifically modulate the surrounding microenvironment, leading to tumor development and progression and affecting therapy response. Based on this, much effort has focused on understanding the mechanisms behind the biology of exosomes and their closely interaction with non-coding RNAs as an efficient tool in tumor diagnostic and therapy. Here we summarize the current knowledge on extracellular and exosomes-enclosed non-coding RNAs, and their importance as potential biomarkers and mediators of intercellular communication in tumor biology.

The p53/microRNA connection in gastrointestinal cancer

The protein encoded by the TP53 gene is one of the most important suppressors of tumor formation, which is also frequently inactivated in gastrointestinal cancer. MicroRNAs (miRNAs) are small noncoding RNAs that inhibit translation and/or promote degradation of their target messenger RNAs. In recent years, several miRNAs have been identified as mediators and regulators of p53’s tumor suppressing functions. p53 induces expression and/or maturation of several miRNAs, which leads to the repression of critical effector proteins. Furthermore, certain miRNAs regulate the expression and activity of p53 through direct repression of p53 or its regulators. Experimental findings indicate that miRNAs are important components of the p53 network. In addition, the frequent genetic and epigenetic alterations of p53-regulated miRNAs in tumors indicate that they play an important role in cancer initiation and/or progression. Therefore, p53-regulated miRNAs may represent attractive diagnostic and/or prognostic biomarkers. Moreover, restoration of p53-induced miRNAs results in suppression of tumor growth and metastasis in mouse models of cancer. Thus, miRNA-based therapeutics may represent a feasible strategy for future cancer treatment. Here we summarize the current published state-of-the-art on the role of the p53-miRNA connection in gastrointestinal cancer.

MicroRNAome genome: a treasure for cancer diagnosis and therapy

The interplay between abnormalities in genes coding for proteins and noncoding microRNAs (miRNAs) has been among the most exciting yet unexpected discoveries in oncology over the last decade. The complexity of this network has redefined cancer research as miRNAs, produced from what was once considered "genomic trash," have shown to be crucial for cancer initiation, progression, and dissemination. Naturally occurring miRNAs are very short transcripts that never produce a protein or amino acid chain, but act by regulating protein expression during cellular processes such as growth, development, and differentiation at the transcriptional, posttranscriptional, and/or translational level. In this review article, miRNAs are presented as ubiquitous players involved in all cancer hallmarks. The authors also describe the most used methods to detect their expression, which have revealed the identity of hundreds of miRNAs dysregulated in cancer cells or tumor microenvironment cells. Furthermore, the role of miRNAs as hormones and as reliable cancer biomarkers and predictors of treatment response is discussed. Along with this, the authors explore current strategies in designing miRNA-targeting therapeutics, as well as the associated challenges that research envisions to overcome. Finally, a new wave in molecular oncology translational research is introduced: the study of long noncoding RNAs.

MicroRNA and signaling pathways in gastric cancer

MicroRNAs (miRNAs) function as either oncogenes or tumor suppressors by inhibiting the expression of target genes, some of which are either directly or indirectly involved with canonical signaling pathways. The relationship between miRNAs and signaling pathways in gastric cancer is extremely complicated. In this paper, we determined the pathogenic mechanism of gastric cancer related to miRNA expression based on recent high-quality studies and then clarified the regulation network of miRNA expression and the correlated functions of these miRNAs during the progression of gastric cancer. We try to illustrate the correlation between the expression of miRNAs and outcomes of patients with gastric cancer. Understanding this will allow us to take a big step forward in the treatment of gastric cancer.

MicroRNA-148b expression is decreased in hepatocellular carcinoma and associated with prognosis

MicroRNAs are small non-coding RNA molecules that have been shown to regulate the expression of genes linked to cancer. MicroRNA-148a (miR-148a) has recently been found to be involved in many critical processes in human malignancies. The present study is to clarify the expression pattern and prognostic role of miR-148b in human hepatocellular carcinoma (HCC). The expression of miR-148b was detected in 156 cases of HCC and 36 cases of normal control specimens by real-time PCR. Results showed that miR-148b expression was significantly decreased in HCC compared with that in normal control. It was also demonstrated that aberrant miR-148b expression was associated with vein invasion and TNM stage of HCC. Kaplan-Meier analysis showed that decreased miR-148b expression was associated with poor overall survival of patients. A multivariate survival analysis also indicated that miR-148b could be an independent prognostic marker. These results proved that miR-148b expression was decreased in HCC and associated with tumor invasion and progression. The present study also provides the first evidence that miR-148b could be an independent prognostic factor for patients with HCC, indicating the potential role of miR-148b as a prognostic marker in clinical practice, and the inhibition of miR-148b may even become a new therapeutic method for the treatment of HCC.

Comparative analysis of microRNA profiles between adult Ascaris lumbricoides and Ascaris suum

Background

The parasitic nematodes Ascaris lumbricoides and A. suum are of great public health and economic significance, and the two taxa were proposed to represent a single species. miRNAs are known with functions of gene regulations at post-transcriptional level.

Results

We herein compared the miRNA profiles of A. lumbricoides and A. suum female adults by Solexa deep sequencing combined with bioinformatics analysis and stem-loop real-time PCR. Using the A. suum genome as the reference genome, we obtained 171 and 494 miRNA candidates from A. lumbricoides and A. suum, respectively. Among which, 74 miRNAs were shared between the two taxa, 97 and 420 miRNAs were A. lumbricoides and A. suum specific. Target and function prediction revealed a significant set of targets which are related to ovarian message protein, vitellogenin and chondroitin proteoglycan of the two nematodes. Enrichment analysis revealed that the percentages of most predicted functions of the miRNA targets were similar, with some taxon specific or taxon enhanced functions, such as different target numbers, specific functions (NADH dehydrogenase and electron carrier functions), etc.

Conclusions

This study characterized comparatively the miRNAs of adult A. lumbricoides and A. suum, and the findings provide additional evidence that A. lumbricoides and A. suum represent a single species. Due to the fast evolution nature of miRNAs and the different parasitic living conditions of humans and pigs, the phenomenon above might indicate a fast evolution of miRNAs of Ascaris in humans and pigs.