Up-Regulation of Plasma miR-23b is Associated with Poor Prognosis of Gastric Cancer

Liquid Biopsy: An Emerging Diagnostic, Prognostic, and Predictive Tool in Gastric Cancer

Liquid biopsy, a minimally invasive procedure that causes minimal pain and complication risks to patients, has been extensively studied for cancer diagnosis and treatment. Moreover, it facilitates comprehensive quantification and serial assessment of the whole-body tumor burden. Several biosources obtained through liquid biopsy have been studied as important biomarkers for establishing early diagnosis, monitoring minimal residual disease, and predicting the prognosis and response to treatment in patients with cancer. Although the clinical application of liquid biopsy in gastric cancer is not as robust as that in other cancers, biomarker studies using liquid biopsy are being actively conducted in patients with gastric cancer. Herein, we aimed to review the role of various biosources that can be obtained from patients with gastric cancer through liquid biopsies, such as blood, saliva, gastric juice, urine, stool, peritoneal lavage fluid, and ascites, by dividing them into cellular and acellular components. In addition, we reviewed previous studies on the diagnostic, prognostic, and predictive biomarkers for gastric cancer using liquid biopsy and discussed the limitations of liquid biopsy and the challenges to overcome these limitations in patients with gastric cancer.

Clinical application and detection techniques of liquid biopsy in gastric cancer

Gastric cancer (GC) is one of the most common tumors worldwide and the leading cause of tumor-related mortality. Endoscopy and serological tumor marker testing are currently the main methods of GC screening, and treatment relies on surgical resection or chemotherapy. However, traditional examination and treatment methods are more harmful to patients and less sensitive and accurate. A minimally invasive method to respond to GC early screening, prognosis monitoring, treatment efficacy, and drug resistance situations is urgently needed. As a result, liquid biopsy techniques have received much attention in the clinical application of GC. The non-invasive liquid biopsy technique requires fewer samples, is reproducible, and can guide individualized patient treatment by monitoring patients' molecular-level changes in real-time. In this review, we introduced the clinical applications of circulating tumor cells, circulating free DNA, circulating tumor DNA, non-coding RNAs, exosomes, and proteins, which are the primary markers in liquid biopsy technology in GC. We also discuss the current limitations and future trends of liquid biopsy technology as applied to early clinical biopsy technology.

PLK2 Single Nucleotide Variant in Gastric Cancer Patients Affects miR-23b-5p Binding

PURPOSE

Chromosomal instability is a hallmark of gastric cancer (GC). It can be driven by single nucleotide variants (SNVs) in cell cycle genes. We investigated the associations between SNVs in candidate genes, PLK2, PLK3, and ATM, and GC risk and clinicopathological features.

MATERIALS AND METHODS

The genotyping study included 542 patients with GC and healthy controls. Generalized linear models were used for the risk and clinicopathological association analyses. Survival analysis was performed using the Kaplan-Meier method. The binding of candidate miRs was analyzed using a luciferase reporter assay.

RESULTS

The PLK2 Crs15009-Crs963615 haplotype was under-represented in the GC group compared to that in the control group (Pcorr=0.050). Male patients with the PLK2 rs963615 CT genotype had a lower risk of GC, whereas female patients had a higher risk (P=0.023; P=0.026). The PLK2 rs963615 CT genotype was associated with the absence of vascular invasion (P=0.012). The PLK3 rs12404160 AA genotype was associated with a higher risk of GC in the male population (P=0.015). The ATM Trs228589-Ars189037-Grs4585 haplotype was associated with a higher risk of GC (P<0.001). The ATM rs228589, rs189037, and rs4585 genotypes TA+AA, AG+GG, and TG+GG were associated with the absence of perineural invasion (P=0.034). In vitro analysis showed that the cancer-associated miR-23b-5p mimic specifically bound to the PLK2 rs15009 G allele (P=0.0097). Moreover, low miR-23b expression predicted longer 10-year survival (P=0.0066) in patients with GC.

CONCLUSIONS

PLK2, PLK3, and ATM SNVs could potentially be helpful for the prediction of GC risk and clinicopathological features. PLK2 rs15009 affects the binding of miR-23b-5p. MiR-23b-5p expression status could serve as a prognostic marker for survival in patients with GC.

The Role of miR-23b in Cancer and Autoimmune Disease

Short-stranded miRNAs are single-stranded RNA molecules involved in the regulation of gene expression. miRNAs are involved in a variety of cellular physiological processes, including cell proliferation, differentiation, and apoptosis. miR-23b have been identified to act both as oncogenes and as tumor suppressors. In addition, miR-23b is related to inflammation resistance to various autoimmune diseases and restrained inflammatory cell migration. The characterization of the specific alterations in the patterns of miR-23b expression in cancer and autoimmune disease has great potential for identifying biomarkers for early disease diagnosis, as well as for potential therapeutic intervention in various diseases. In this review, we summarize the ever-expanding role of miR-23b and its target genes in different models and offer insight into how this multifunctional miRNA modulates tumor cell proliferation and apoptosis or inflammatory cell activation, differentiation, and migration.

Current and potential biomarkers in gastric cancer: a critical review of the literature

Gastric cancer is the fourth most common type of cancer worldwide and the second most lethal. Gastric cancer biomarkers can be used for diagnosis, prediction of sensitivity to treatment, and prognosis. The following search terms were applied to PubMed as of December 2020: 'gastric cancer classification', 'gastric cancer epidemiology', 'cancer metastasis' and 'gastric cancer biomarker'. Only experimental studies were reported in the 'biomarkers' section. Some biomarkers can serve as therapeutic targets for antitumoral drugs. The genes analyzed include E-cadherin, RPRM, XAF1, MINT25, TFF1, p16 and p53. The miRNAs analyzed include miR-18a, miR185-5p, miR-125b and miR-21. Some molecules were associated with metastasis of gastric cancer, specifically those involved with EMT process and tissue degradation.

Longitudinal Circulating Levels of miR-23b-3p, miR-126-3p and lncRNA GAS5 in HCC Patients Treated with Sorafenib

Human hepatocellular carcinoma (HCC) is the most frequent primary tumor of the liver and the third cause of cancer-related deaths. The multikinase inhibitor sorafenib is a systemic drug for unresectable HCC. The identification of molecular biomarkers for the early diagnosis of HCC and responsiveness to treatment are needed. In this work, we performed an exploratory study to investigate the longitudinal levels of cell-free long ncRNA GAS5 and microRNAs miR-126-3p and -23b-3p in a cohort of 7 patients during the period of treatment with sorafenib. We used qPCR to measure the amounts of GAS5 and miR-126-3p and droplet digital PCR (ddPCR) to measure the levels of miR-23b-3p. Patients treated with sorafenib displayed variable levels of GAS5, miR-126-3p and miR-23b-3p at different time-points of follow-up. miR-23b-3p was further measured by ddPCR in 37 healthy individuals and 25 untreated HCC patients. The amount of miR-23b-3p in the plasma of untreated HCC patients was significantly downregulated if compared to healthy individuals. The ROC curve analysis underlined its diagnostic relevance. In conclusion, our results highlight a potential clinical significance of circulating miR-23b-3p and an exploratory observation on the longitudinal plasmatic levels of GAS5, miR-126-3p and miR-23b-3p during sorafenib treatment.

MSC-AS1 induced cell growth and inflammatory mediators secretion through sponging miR-142-5p/DDX5 in gastric carcinoma

Emerging studies have noted that dysregulated lncRNAs are implicated in cancer progression and tumorigenesis. We first showed that MSC-AS1 was overexpressed in gastric cancer (GC) cells (HGC-27, MKN-45, SGC-7901 and MGC-803 cells) compared with GES cells. We observed that MSC-AS1 was upregulated in GC specimens compared with paired normal specimens. MSC-AS1 increased cell growth and cycle progression. Moreover, the overexpression of MSC-AS1 enhanced the secretion of the inflammatory mediators IL-1β, IL-6 and TNF-α. We found that the overexpression of MSC-AS1 inhibited the expression of miR-142-5p in HGC-27 cells. We noted that DDK5 was a target gene of miR-142-5p. The overexpression of miR-142-5p suppressed the luciferase activity of wild-type DDX5, but the luciferase activity of the mutant DDX5 was not changed. We showed that miR-142-5p was downregulated in GC specimens compared with paired normal specimens. MSC-AS1 expression was inversely correlated with miR-142-5p expression in GC specimens. MSC-AS1 induced cell growth, cell cycle progression and inflammatory mediator secretion by modulating DDX5. These results showed that MSC-AS1 functions as a key oncogene in the development of GC.

LINC00689 induces gastric cancer progression via modulating the miR-338-3p/HOXA3 axis

BACKGROUND

LINC00689 acts one critical regulatory role in several tumors. However, the functional, regulatory mechanism and expression of LINC00689 remains unknown in gastric cancer.

METHODS

LINC00689 and miR-338-3p levels were determined using a quantitative reverse transcriptase-polymerase chain reaction analysis and an enzyme-linked immunoassay and a cell-counting kit-8 assay were utilized to detect interleukin (IL)-8, IL-6 and IL-1β expression and cell proliferation, respectively.

RESULTS

We found that LINC00689 and HOXA3 are overexpressed and miR-338-3p is decreased in gastric cancer cells. Compared to control specimens, LINC00689 is overexpressed in gastric cancer specimens and the level of LINC00689 was up-regulated in 32 cases (32/40; 80.0%) compared to control samples. LINC00689 increased cell growth, epithelial-mesenchymal transition (EMT) development and secretion of inflammatory factors in gastric cancer. Compared to control specimens, miR-338-3p expression was decreased in gastric cancer specimens and a Pearson's correlation assay revealed that miR-338-3p was negatively correlated with LINC00689 expression in gastric cancer specimens. HOXA3 was identified as one target gene of miR-338-3p and Ectopic expression of LINC00689 suppressed miR-338-3p and enhanced HOXA3 expression in HGC-27 cells. LINC00689 enhanced cell growth, EMT development and secretion of inflammatory factors by promoting HOXA3.

CONCLUSIONS

LINC00689 may present a potential future target for gastric cancer treatment.

Machine Learning-Based Ensemble Recursive Feature Selection of Circulating miRNAs for Cancer Tumor Classification

Circulating microRNAs (miRNA) are small noncoding RNA molecules that can be detected in bodily fluids without the need for major invasive procedures on patients. miRNAs have shown great promise as biomarkers for tumors to both assess their presence and to predict their type and subtype. Recently, thanks to the availability of miRNAs datasets, machine learning techniques have been successfully applied to tumor classification. The results, however, are difficult to assess and interpret by medical experts because the algorithms exploit information from thousands of miRNAs. In this work, we propose a novel technique that aims at reducing the necessary information to the smallest possible set of circulating miRNAs. The dimensionality reduction achieved reflects a very important first step in a potential, clinically actionable, circulating miRNA-based precision medicine pipeline. While it is currently under discussion whether this first step can be taken, we demonstrate here that it is possible to perform classification tasks by exploiting a recursive feature elimination procedure that integrates a heterogeneous ensemble of high-quality, state-of-the-art classifiers on circulating miRNAs. Heterogeneous ensembles can compensate inherent biases of classifiers by using different classification algorithms. Selecting features then further eliminates biases emerging from using data from different studies or batches, yielding more robust and reliable outcomes. The proposed approach is first tested on a tumor classification problem in order to separate 10 different types of cancer, with samples collected over 10 different clinical trials, and later is assessed on a cancer subtype classification task, with the aim to distinguish triple negative breast cancer from other subtypes of breast cancer. Overall, the presented methodology proves to be effective and compares favorably to other state-of-the-art feature selection methods.

Association Between Liquid Biopsy and Prognosis of Gastric Cancer Patients: A Systematic Review and Meta-Analysis

Background: Reports regarding liquid biopsy and gastric cancer (GC) have emerged rapidly in recent decades, yet their prognostic value still remains controversial. This study was aimed to assess the impact of liquid biopsy, including circulating tumor cells (CTCs) and cell-free nucleic acids, on GC patients' prognosis.

Methods: PubMed, Medline, EMBASE, and ClinicalTrial.gov databases were searched for studies that report GC patient survival data stratified by CTC/circulating tumor DNA (ctDNA)/circulating miRNAs' status. The hazard ratios (HRs) and their 95% confidence intervals (CIs) for patients' overall survival (OS) and disease-free survival (DFS)/progression-free survival (PFS) were recorded or calculated depending on circulating target status.

Results: We initially identified 4,221 studies, from which 43 were eligible for further analysis, comprising 3,814 GC patients. Pooled analyses showed that detection of certain CTCs, ctDNA, and circulating miRNA was associated with poorer OS (CTCs: HR = 1.84, 95%CI 1.50–2.26, p < 0.001; ctDNA: HR = 1.78, 95%CI 1.36–2.34, p < 0.001; circulating miRNA: HR = 1.74, 95%CI 1.13–2.69, p < 0.001) and DFS/PFS (CTCs: HR = 3.39, 95%CI 2.21–5.20, p < 0.001; ctDNA: HR = 2.38, 95%CI 1.31–4.32, p = 0.004; circulating miRNA: HR = 3.30, 95%CI 2.39–4.55, p < 0.001) of GC patients, regardless of disease stage and time point at which sample is taken (at baseline or post-treatment).

Conclusions: The presence of CTCs and/or cellular components identifies a group of GC with poorer prognosis. Among circulating markers, CTCs demonstrated a stronger and more stable predictive value for late-stage disease and among Mongolian populations with GC. Less data are available for ctDNA and miRNA; however, their presence may also reflect aggressive biology and warrants further prospective study.

Secondary Structural Model of Human MALAT1 Reveals Multiple Structure-Function Relationships

Human metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is an abundant nuclear-localized long noncoding RNA (lncRNA) that has significant roles in cancer. While the interacting partners and evolutionary sequence conservation of MALAT1 have been examined, much of the structure of MALAT1 is unknown. Here, we propose a hypothetical secondary structural model for 8425 nucleotides of human MALAT1 using three experimental datasets that probed RNA structures in vitro and in various human cell lines. Our model indicates that approximately half of human MALAT1 is structured, forming 194 helices, 13 pseudoknots, five structured tetraloops, nine structured internal loops, and 13 intramolecular long-range interactions that give rise to several multiway junctions. Evolutionary conservation and covariation analyses support 153 of 194 helices in 51 mammalian MALAT1 homologs and 42 of 194 helices in 53 vertebrate MALAT1 homologs, thereby identifying an evolutionarily conserved core that likely has important functional roles in mammals and vertebrates. Data mining revealed that RNA modifications, somatic cancer-associated mutations, and single-nucleotide polymorphisms may induce structural rearrangements that sequester or expose binding sites for several cancer-associated microRNAs. Our findings reveal new mechanistic leads into the roles of MALAT1 by identifying several intriguing structure–function relationships in which the dynamic structure of MALAT1 underlies its biological functions.

LINC00994 promoted invasion and proliferation of gastric cancer cell via regulating miR-765-3p

Emerging studies indicated that lncRNA is one crucial regulator in development and tumorigenesis. We firstly showed that LINC00994 was overexpressed in GC cells compare with GES-1. Compared to adjacent samples, the LINC00994 expression was increased in GC tissues by qRT-PCR assay. Furthermore, Elevated expression of LINC00994 induced GC cell invasion, proliferation and cycle. Luciferase reporter analysis indicated that ectopic miR-765-3p expression suppressed wild type LINC00994 luciferase activity, but not mutant LINC00994 in GC cells. Elevated expression of LINC00994 inhibited the miR-765-3p expression in GC cells. Compared to adjacent samples, the miR-765-3p expression was decreased in GC tissues by qRT-PCR assay. LINC00994 induced GC cell invasion and growth via modulating miR-765-3p. Thus, our data suggested an oncogenic role of LINC00994 in development of GC.

The diagnostic value of circulating microRNAs as a biomarker for gastric cancer: A meta‑analysis

Recently, cancer research microRNA studies have drawn great attention. However, the results of these studies have been inconsistent and variable regarding the availability of circulating miRNAs in gastric cancer (GC) diagnosis. Thus, results should be interpreted cautiously. The purpose of the present study was to assess the diagnostic performance of circulating miRNAs in GC diagnosis. We conducted a systematic and comprehensive approach for the inclusion of studies. The sensitivity, specificity, and diagnostic odds ratio were pooled with random effects models, and a summary of receiver operator characteristic (SROC) curves were plotted. The potential heterogeneity was assessed with Q test and I2 statistics. Subgroup analyses and meta‑regressions further investigated the sources of heterogeneity. A total of 77 studies from 48 articles were eligible for the meta‑analysis. The results revealed a sensitivity of 0.76, a specificity of 0.81, and an AUC of 0.86 for gastric cancer diagnosis with circulating miRNAs. In addition, subgroup analyses indicated that multiple miRNAs assays, non‑microarray screening approaches, and serum‑based miRNA assays exhibited good diagnostic performance in contrast to a single miRNA assay, microarray expression profiling screening, and plasma‑based miRNA group analysis. The diagnostic ability of miRNAs in early stage I‑II groups and the high expression group were approximately similar to that in the stage I‑IV groups and the low expression group. For the circulating miRNAs, our meta‑analysis identified a combination of multiple miRNAs, non‑microarray chip screening, and serum‑based miRNA assays were associated with the most effective GC diagnostic performance. However, many unclear molecular mechanisms limited the accuracy of the diagnostic results, and should be interpreted with caution. Further large‑scale prospective studies are required for validating the diagnostic applicability of circulating miRNAs in gastric cancer patients.

Long noncoding RNA DGCR5 suppresses gastric cancer progression by acting as a competing endogenous RNA of PTEN and BTG1

Long noncoding RNA (lncRNA) DiGeorge syndrome critical region gene 5 (DGCR5) has been reported to correlate with a variety of cancers, with its expression pattern and potential mechanism not clarified in gastric cancer (GC). In this study, we demonstrated that DGCR5 was downregulated in cancerous tissues and plasma samples from patients with GC, and its downregulation was associated with advanced TNM stage and positive lymphatic metastasis. Plasma DGCR5 had an area under the receiver operating characteristic curve (AUC) of 0.722 for diagnosis of GC. Gain- and loss-of-function of DGCR5 revealed that DGCR5 functioned as a competing endogenous RNA for miR-23b to suppress GC cell proliferation, invasion and migration, and facilitate apoptosis by regulating PTEN and BTG1 in vitro. Furthermore, the overexpression of DGCR5 suppressed tumor growth, and inhibited the expression of miR-23b and proliferation antigen Ki-67, but increased the expression of PTEN and BTG1 in vivo. In conclusion, our results show that DGCR5 is a tumor-suppressive lncRNA that regulates PTEN and BTG1 expression through directly binding to miR-23b. This mechanism may contribute to a better understanding of GC pathogenesis and provide a potential therapeutic strategy for GC.

Long Noncoding RNA XR007793 Regulates Proliferation and Migration of Vascular Smooth Muscle Cell via Suppressing miR-23b

Background

Long noncoding RNAs (lncRNAs) were identified as potential regulatory factor in vascular disease. However, the role of XR007793 in the regulation of neointima formation after vascular injury remains largely unknown.

Material/Methods

LncRNA expression levels were detected using real-time polymerase chain reaction (RT-PCR). In vivo and in vitro assay were performed in Sprague-Dawley rats and VSMCs. Cell Counting Kit-8 (CCK-8) assay, Transwell assay, and scratch wound healing assay were performed to detect cell proliferation and migration. Western blotting was used to detect protein expression.

Results

The results of qRT-PCR indicated that XR007793 expression was significantly increased in the injured carotid artery of Sprague-Dawley rats and platelet-derived growth factor-BB induced rat aortic smooth muscle cells. Knockdown of XR007793 repressed the proliferation and migration of VSMC in vitro. The expression level of miR-23b was reduced in mouse carotid injured tissues and cell line. Bioinformatics analysis and luciferase reporter assay revealed that XR007793 directly bonds to miR-23b. Pearson correlation analysis showed that XR007793a and miR-23b were negatively correlated in carotid samples. Furthermore, bioinformatics analysis and luciferase assay indicated that miR-23b targeted the Forkhead box O 4 (FOXO4) 3′-UTR to inhibit FOXO4 expression. After transfecting miR-23b inhibitor, the expression both of XR007793 and FOXO4 was increased. The effects on expression were reversed after transfected with miR-23b mimics. Rescue experiments results indicated that miR-23b inhibitor reduced the expression of VSMC marker and promoted proliferation and migration of VSMC.

Conclusions

This study shows that XR007793 aggravates the loss of function of VSMCs by negatively regulating miR-23b. It does so by targeting FOXO4, which could serve as a novel therapeutic target in post-angioplasty restenosis.

MicroRNAs as non-invasive diagnostic biomarkers for gastric cancer: Current insights and future perspectives

Non-invasive diagnostic biomarkers may contribute to an early identification of gastric cancer (GC) and improve the clinical management. Unfortunately, no sensitive and specific screening biomarkers are available yet and the currently available approaches are limited by the nature of the disease. GC is a heterogenic disease with various distinct genetic and epigenetic events that occur during the multifactorial cascade of carcinogenesis. MicroRNAs (miRNAs) are commonly deregulated in gastric mucosa during the Helicobacter pylori infection and in stepwise manner from chronic gastritis, through preneoplastic conditions such as atrophic gastritis and intestinal metaplasia, to early dysplasia and invasive cancer. Identification of miRNAs in blood in 2008 led to a great interest on miRNA-based diagnostic, prognostic biomarkers in GC. In this review, we provide the most recent systematic review on the existing studies related to miRNAs as diagnostic biomarkers for GC. Here, we systematically evaluate 75 studies related to differential expression of circulating miRNAs in GC patients and provide novel view on various heterogenic aspects of the existing data and summarize the methodological differences. Finally, we highlight several important aspects crucial to improve the future translational and clinical research in the field.

MicroRNAs as potential biomarkers for diagnosis, therapy and prognosis of gastric cancer

Despite the widespread use of endoscopy and conventional tumor biomarkers, gastric cancer (GC) remains one of the most frequent causes of cancer-related deaths worldwide due to its late diagnosis and poor response to treatment. Valuable and practical biomarkers are urgently needed to screen patients with a high risk of GC that can complement endoscopic diagnosis. Such biomarkers will enable the efficient prediction of therapeutic response and prognosis of GC patients and favor the establishment of an effective treatment strategy for each and every patient. MicroRNAs (miRNAs) are a class of small non-coding RNA sequences that play important roles in modulating key biological processes by regulating the expression of target genes. Expectedly, miRNAs are abnormally expressed within the tumor tissue and in associated biological fluids of GC patients including their blood, gastric juice, and urine. Accumulating evidence indicates that miRNAs are potential biomarkers with multiple diagnostic functions for GC. Here, we review recent advances and challenges in using miRNAs, particularly biofluid miRNAs, as GC biomarkers with potential clinical applications including diagnosing, clinically staging, and predicting malignant behaviors, therapy response, recurrence after surgery and survival time.

Review of recent efforts to discover biomarkers for early detection, monitoring, prognosis, and prediction of treatment responses of patients with gastric cancer

Gastric cancer (GC) is the leading cause of cancer-related death worldwide. Despite recent advances in diagnosis and therapy, the prognosis of patients with GC is poor. Many patients have inoperable disease upon diagnosis or experience recurrent disease after curative gastrectomy. Unfortunately, tumor markers for GC, such as serum carcinoembryonic antigen and carbohydrate antigen 19-9, lack sufficient sensitivity and specificity. Therefore, effective biomarkers are required to detect early GC and to predict tumor recurrence and chemosensitivity. Areas covered: Here we aimed to review recent developments in techniques that improve the detection of aberrant expression of GC-associated molecules, including protein coding genes, microRNAs, long noncoding RNAs, and methylated promoter DNAs. Expert commentary: Detection of genetic and epigenetic alterations in gastric tissue or in the circulation will likely improve the diagnosis and management of GC to achieve significantly improved outcomes.

Correlation analysis on the expression levels of microRNA-23a and microRNA-23b and the incidence and prognosis of ovarian cancer

The present study aimed to investigate the expression levels of microRNA (miR)-23a and miR-23b in the tumor tissues of patients with ovarian cancer. The study also explored the correlation of miR-23a and miR-23b expression levels in the tumor tissues with the clinic-pathological parameters and prognosis of the patients. Specimens of frozen tumor tissues and normal tissues adjacent to the tumor were collected from 50 patients with ovarian cancer. Reverse transcription-quantitative polymerase chain reaction was adopted to detect the expression levels of miR-23a and miR-23b in tumor tissues. Furthermore, normal tissues adjacent to the tumor were utilized as the control for the experiments and Pearson method was used to analyze the correlation between miR-23a and miR-23b expression levels in tumor tissues. The correlation of miR-23a and miR-23 expression in tumor tissues and the prognosis of the patients with ovarian cancer was analyzed in combination with clinical data. The expression of miR-23a in the tissues of ovarian cancer was significantly higher in comparison with normal adjacent tissues. However, the expression of miR-23b in the tissues of ovarian cancer was significantly lower when compared with adjacent normal tissues. Notably, the expression of miR-23a was negatively correlated with that of miR-23b in tumor tissues of ovarian cancer. The high expression of miR-23a and the low expression of miR-23b in tumor tissues of the patients was correlated with the degree of tumor differentiation, metastasis of lymph nodes and clinical staging. The five-year overall survival rate of the patients was 36% (18/50). Univariate survival analysis indicated that miR-23a and miR-23b were the factors influencing the overall survival rate of ovarian cancer. The present findings suggest that high expression of miR-23a and the low expression of miR-23b are closely correlated with the occurrence and development of ovarian cancer. The abnormal expression of the miR-23a and miR-23b could be utilized as potential prognostic molecular markers of ovarian cancer.

Construction and Comprehensive Analysis for Dysregulated Long Non-Coding RNA (lncRNA)-Associated Competing Endogenous RNA (ceRNA) Network in Gastric Cancer

Long non-coding RNA (lncRNA) is a kind of non-coding RNA with transcripts more than 200 bp in length. LncRNA can interact with the miRNA as a competing endogenous RNA (ceRNA) to regulate the expression of target genes, which play a significant role in the initiation and progression of tumors. In this study, we explored the functional roles and regulatory mechanisms of lncRNAs as ceRNAs in gastric cancer, and their potential implications for prognosis. The lncRNAs, miRNAs, and mRNAs expression profiles of 375 gastric cancer tissues and 32 non-tumor gastric tissues were downloaded from The Cancer Genome Atlas (TCGA) database. Differential expression of RNAs was identified using the DESeq package. Survival analysis was estimated based on Kaplan-Meier curve analysis. KEGG pathway analysis was performed using KOBAS 3.0. The dysregulated lncRNA-associated ceRNA network was constructed in gastric cancer based on bioinformatics generated from miRcode and miRTarBase. A total of 237 differentially expressed lncRNAs and 198 miRNAs between gastric cancer and matched normal tissues were screened in our study with thresholds of |log2FC| >2 and adjusted P value <0.01. Eleven discriminatively expressed lncRNAs may be correlated with tumorigenesis of gastric cancer. Seven out of 11 dysregulated lncRNA were found to be significantly associated with overall survival in gastric cancer (P value <0.05). The newly identified ceRNA network includes 11 gastric cancer-specific lncRNAs, 9 miRNAs, and 41 mRNAs. Collectively, our study will contribute to improving the understanding of the lncRNA-associated ceRNA network regulatory mechanisms in the pathogenesis of gastric cancer and provide and identify novel lncRNAs as candidate prognostic biomarkers or potential therapeutic targets.

MicroRNA-454 inhibits tumor cell proliferation, migration and invasion by downregulating zinc finger E‑box‑binding homeobox 1 in gastric cancer

Gastric cancer is the fourth most common malignancy and the third leading cause of cancer‑associated mortality globally. Accumulating studies have identified the involvement of microRNAs in the initiation and progression of gastric cancer. This study was aimed to investigate the expression, functional roles of microRNA‑454 (miR‑454) and its direct target gene in gastric cancer. According to the results, the expression level of miR‑454 was demonstrated to be reduced in gastric cancer tissues and cell lines compared with corresponding distant non‑tumor gastric tissues and human immortalized gastric epithelial, respectively. miR‑454 mimic transfection led to inhibition of gastric cancer cells proliferation, migration and invasion in vitro. Bioinformatic analysis predicated that zinc finger E‑box‑binding homeobox 1 (ZEB1) is a potential target gene of miR‑454. Luciferase reporter assays revealed that miR‑454 directly targeted the 3'UTR of ZEB1. miR‑454 overexpression significantly decreased the ZEB1 mRNA and protein expression levels. ZEB1 knockdown could mimic the tumor suppressive roles induced by miR‑454 overexpression on gastric cancer cell proliferation, migration and invasion. In conclusion, the present study suggested that miR‑454 under expression may be involved in gastric cancer initiation and progression, by promoting proliferation, migration and invasion by directly targeting ZEB1. miR‑454/ZEB1‑based targeted therapy may be a potential strategy for the treatment of gastric cancer.

MiR-23b inhibits cell migration and invasion through targeting PDE7A in colon cancer cells

It has been found that the abnormal expression of miR-23b is related to the poor prognosis or the weak ability of metastasis in colorectal cancer. Furthermore, high expression of PDE7A in tumors is known to be related to poor prognosis. The aim of this study was to explain whether miR-23b was involved in the invasion and metastasis of colon cancer by regulating PDE7A gene. The expression levels of miR-23b and PDE7A in colon tissues and colon cancer cell lines (SW620 and SW480 cells) were measured by real time PCR. The PDE7A protein level was determined by Western blotting. The relationship between miR-23b and PDE7A was verified by cell transfection and luciferase reporter assay. The effect of miR-23b or PDE7A level on cell invasion and migration was determined by Transwell assay. miR-23b was down-regulated when PDE7A was up-regulated in colon cancer tissues and cells. The result of dual luciferase reporter assay showed that PDE7A was a direct target gene of miR-23b. Overexpression of miR-23b not only reduced the expression of PDE7A in SW620 cells or SW480 cells, but also weakened the migration and invasion abilities of SW620 cells or SW480 cells. When SW620 cells or SW480 cells were transfected with si-PDE7A, the level of PDE7A increased and the migration and invasion abilities of cells diminished. In conclusion, miR-23b is lowly expressed in colon cancer tissues and cells, and miR-23b may play an inhibitory role in the development of colon cancer through down-regulating the expression of PDE7A.

Prognostic value of microRNAs in gastric cancer: a meta-analysis

BACKGROUND

Previous articles have reported that expression levels of microRNAs (miRNAs) are associated with survival time of patients with gastric cancer (GC). A systematic review and meta-analysis was performed to study the outcome of it.

DESIGN

Meta-analysis.

METHODS

English studies estimating expression levels of miRNAs with any of survival curves in GC were identified up till March 19, 2017 through performing online searches in PubMed, EMBASE, Web of Science and Cochrane Database of Systematic Reviews by two authors independently. The pooled hazard ratios (HR) with 95% confidence intervals (CI) were used to estimate the correlation between miRNA expression and overall survival (OS).

RESULTS

Sixty-nine relevant articles about 26 miRNAs with 6148 patients were ultimately included. GC patients with high expression of miR-20b (HR=2.38, 95%CI=1.16-4.87), 21 (HR=1.77, 95%CI=1.01-3.08), 106b (HR=1.84, 95%CI=1.15-2.94), 196a (HR=2.66, 95%CI=1.94-3.63), 196b (HR=1.67, 95%CI=1.38-2.02), 214 (HR=1.84, 95%CI=1.27-2.67) or low expression of miR-125a (HR=2.06, 95%CI=1.26-3.37), 137 (HR=3.21, 95%CI=1.68-6.13), 141 (HR=2.47, 95%CI=1.34-4.56), 145 (HR=1.62, 95%CI=1.07-2.46), 146a (HR=2.60, 95%CI=1.63-4.13), 206 (HR=2.85, 95%CI=1.73-4.70), 218 (HR=2.61, 95%CI=1.74-3.92), 451 (HR=1.73, 95%CI=1.19-2.52), 486-5p (HR=2.45, 95%CI=1.65-3.65), 506 (HR=2.07, 95%CI=1.33-3.23) have significantly poor OS (P<0.05).

CONCLUSIONS

In summary, miR-20b, 21, 106b, 125a, 137, 141, 145, 146a, 196a, 196b, 206, 214, 218, 451, 486-5p and 506 demonstrate significantly prognostic value. Among them, miR-20b, 125a, 137, 141, 146a, 196a, 206, 218, 486-5p and 506 are strong biomarkers of prognosis in GC.

High expression of miR-16 and miR-451 predicating better prognosis in patients with gastric cancer

PURPOSE

To investigate the expression pattern of miR-16 and miR-451 and evaluate their prognostic value in 180 GC patients undergoing surgery.

METHODS

In our previous study, a panel of five circulating miRNAs (miR-16, miR-25, miR-92a, miR-451 and miR-486-5p) can be used as a potential biomarker for detecting of early-stage gastric carcinoma (GC). Tissue microarrays were constructed from 180 patients with GC after surgery. MiR-16 and miR-451 expression was detected by miRNA-locked nucleic acid in situ hybridization, and their relationship with clinicopathological parameters and overall survival was analyzed.

RESULTS

MiR-16 expression was decreased in 30.6 % (55/180) of GC, increased in 54.4 % (98/180) and unchanged in 15.0 % (27/180), compared with paracancerous normal tissue (P < 0.001). MiR-451 expression was decreased in 17.8 % (32/180), increased in 62.8 % (113/180) and unchanged in 19.4 % (35/180) of GC, compared with paracancerous normal tissue (P < 0.001).Univariate analysis indicated that low miR-16 and miR-451 expression, tumor stage, tumor status, node status and tumor size were significant negative prognostic predictors for overall survival in patients with GC (P < 0.001, P < 0.001, P = 0.002, P < 0.001 and P = 0.001, respectively). Multivariate regression analysis demonstrated that stage [hazard ratio (HR) 1.80; 95 % confidence interval (CI) 1.0-3.26; P = 0.05], low expression of miR-16 (HR 2.26; 95 % CI 1.51-3.40; P < 0.001) and miR-451 (HR 2.01; 95 % CI 1.36-2.96; P < 0.001) predicted shorter OS, while tumor status (HR 1.59; 95 % CI 0.73-3.48 P = 0.242), lymph node metastasis (HR 1.41; 95 % CI 0.71-2.82; P = 0.326) and tumor size (HR 1.53; 95 % CI 0.92-2.55; P = 0.099) were not. Moreover, patients with both miR-16 and miR-451 high expression have better OS than those with two miRNAs unchanged or low expression in GC tissues. Patients with both miR-16 and miR-451 high have better OS than patients with single miR-451 high expression.

CONCLUSIONS

High expression of miR-16 and miR-451 was associated with longer OS in GC patients. Especially patients with miR-16 and miR-451 double high expression will predict better OS. MiR-16 and miR-451 may be used as novel makers to evaluate prognosis and provide a new treatment target in GC.