MicroRNAs as a potential prognostic factor in gastric cancer

The Emerging Roles and Mechanisms of PAQR3 in Human Cancer: Pathophysiology and Therapeutic Implications

Cancer was one of the common causes of death in the world, and it was increasing year by year. At present, Progestin and AdipoQ receptor family member 3 (PAQR3) was widely studied in cancer. It has been found that PAQR3 was down regulated in various cancers, such as the gastric cancer, osteosarcoma, glioma, hepatocellular carcinoma, acute lymphoblastic leukemia, laryngeal squamous cell carcinoma, esophageal cancer, breast cancer, non-small cell lung cancer, and colorectal cancer. The decreased expression of PAQR3 was associated with short overall survival and disease-free survival in patients with gastric cancer, hepatocellular carcinoma, laryngeal squamous cell carcinoma, esophageal cancer, breast cancer, and non-small cell lung cancer. PAQR3 could inhibit cancer progression by using the Ras/Raf/MEK/ERK, PI3/AKT, EMT and other mechanisms, and was negatively regulated by the miR-543, miR-15b-5p and miR-15b. The roles and signaling mechanisms of PAQR3, and the relationship between the expression of PAQR3 and prognosis in cancer progression are reviewed in this article, and provides new tumor marker and idea to guide cancer treatment.

miR-199a-3p promotes gastric cancer progression by promoting its stemness potential via DDR2 mediation

BACKGROUND

Peritoneal metastasis (PM) is an independent prognostic factor in gastric cancer (GC), however, the underlying mechanisms of PM occurrence remain unclear.

METHOD

The roles of DDR2 were investigated in GC and its potential relationship to PM, and orthotopic implants into nude mice were performed to assess the biological effects of DDR2 on PM.

RESULTS

Herein, DDR2 level is more significantly observed to elevate in PM lesion than the primary lesion. GC with DDR2-high expression evokes a worse overall survival (OS) in TCGA, similar results of the gloomy OS with high DDR2 levels are clarified via the stratifying stage of TNM. The conspicuously increased expression of DDR2 was found in GC cell lines, luciferase reporter assays verified that miR-199a-3p directly targeted DDR2 gene, which was correlated to tumor progression. We ulteriorly observed DDR2 participated in GC stemness maintenance via mediating pluripotency factor SOX2 expression and implicated in autophagy and DNA damage of cancer stem cells (CSCs). In particular, DDR2 dominated EMT programming through recruiting NFATc1-SOX2 complex to Snai1 in governing cell progression, controlling by DDR2-mTOR-SOX2 axis in SGC-7901 CSCs. Furthermore, DDR2 promoted the tumor peritoneal dissemination in gastric xenograft mouse model.

CONCLUSION

Phenotype screens and disseminated verifications incriminating in GC exposit the miR-199a-3p-DDR2-mTOR-SOX2 axis as a clinically actionable target for tumor PM progression. The herein-reported DDR2-based underlying axis in GC represents novel and potent tools for studying the mechanisms of PM.

Downregulation of miR-451 in cholangiocarcinoma help the diagnsosi and promotes tumor progression

Background

Cholangiocarcinoma is a kind of invasive malignant tumor followed by hepatocellular carcinoma. miR-451 was suggested to function as regulator in various human tumors, but its role in mediating tumor progression and predicting the prognosis of cholangiocarcinoma remains unknown. The clinical significance and biological function of miR-451 in cholangiocarcinoma were assessed in this study.

Results

The tissue and serum expression of miR-451 was decreased in cholangiocarcinoma compared with corresponding normal samples. The downregulation of miR-451 was associated with the progressive TNM stage and positive lymph node metastasis of patients. miR-451 was identified to be an indicator of the diagnosis and prognosis of cholangiocarcinoma distinguishing cholangiocarcinoma patients from healthy volunteers and predicting the poor outcome of patients. miR-451 also served as a tumor suppressor negatively regulating the cellular processes of cholangiocarcinoma.

Conclusions

miR-451 played a vital role in the early detection and risk prediction of cholangiocarcinoma. miR-451 also suppressed the progression of cholangiocarcinoma, which provides a potential therapeutical target for cholangiocarcinoma treatment.

miR-144-3p/miR-451a promotes lymphovascular invasion through repression of PTEN/p19 in rectal neuroendocrine tumors

BACKGROUND AND AIM

Although rectal neuroendocrine tumor (NET-G1) have potential metastatic capability, even among small tumors, no predictive biomarker for invasion and metastasis has been reported. We analyzed microRNA (miRNA) expression profiles in rectal NET-G1 tissues with and without lymphovascular invasion (LVI). Moreover, we then investigated their target genes to clarify the mechanism of invasion/metastasis in NET-G1.

METHODS

miRNA array analysis was performed using seven rectal NET-G1 tissues with LVI and seven without LVI. miRNA expression was confirmed by quantitative real-time PCR. A NET cell line H727 was transfected with miRNA mimic or target gene small interfering RNA, and migration and invasion assays were performed.

RESULTS

The expression levels of miR-144-3p and miR-451a were significantly higher in NET-G1 with LVI versus without LVI, as determined by miRNA array analysis and RT-qPCR. A significant correlation was observed between miR-144-3p and miR-451a expression levels, strongly suggesting miR144/451 cluster overexpression in NET-G1 with LVI. Bioinformatic analysis of target genes revealed that miR-144-3p and miR-451a directly interact with PTEN and p19 mRNA, respectively. Immunohistochemistry revealed significantly lower expression of PTEN and p19 in NET-G1 tissues with LVI than in those without LVI. The miR-144-3p and miR-451a mimic significantly increased cell migration/invasion capability, respectively. Knockdown of PTEN and p19 induced significant augmentation of cell invasion and migration capability, respectively.

CONCLUSIONS

Our data suggest that overexpression of miR-144/miR-451 cluster promotes LVI via repression of PTEN and p19 in rectal NET-G1 cells. miR-144/451 cluster may be a novel biomarker for predicting invasion/metastasis in rectal NET-G1.

Novel biomarkers of microRNAs in gastric cancer; an overview from diagnosis to treatment

The fourth frequent disease in the world and the second cause of cancer-related death is gastric cancer (GC). In this way, over 80% of diagnoses are made in the middle to advanced degrees of the disease, underscoring the requirement for innovative biomarkers that can be identified quickly. Meaningly, biomarkers that can complement endoscopic diagnosis and be used to detect patients with a high risk of GC are desperately needed. These biomarkers will allow for the accurate prediction of therapy response and prognosis in GC patients, as well as the development of an optimal treatment strategy for each individual. Conspicoiusly, microRNAs (miRNAs) and small noncoding RNA regulates the expression of target mRNA and thereby modifies critical biological mechanisms. According to the data, abnormally miRNAs expression in GC is linked to tumor growth, carcinogenesis, aggression and distant metastasis. Importantly, miRNA expression patterns and next-generation sequencing (NGS) can also be applied to analyze kinds of tissues and cancers. Given the high death rates and poor prognosis of GC, and the absence of a clinical diagnostic factor that is adequately sensitive to GC, research into novel sensitive and specific markers for GC diagnosis is critical. In this review,we evaluate the latest research findings that suggest the feasibility and clinical utility of miRNAs in GC.

MiRNA-4537 functions as a tumor suppressor in gastric cancer and increases the radiosensitivity of gastric cancer cells

Radiotherapy is a common method to treat gastric cancer (GC). However, the clinical outcomes of GC radiotherapy face challenges, and the mechanisms of GC radioresistance remain unclear. Our study aimed to investigate the role and mechanism of miR-4537 in the radiation sensitivity of GC cells. Cell viability was determined by Cell Counting Kit-8. The proliferation of HGC27 and KATO III cells was measured using a colony formation assay. Flow cytometry was performed to examine the changes in cell apoptosis. Western blotting was conducted to detect the expression of zinc finger protein 587 (ZNF587) protein in HGC27 and KATO III cells. To confirm the relationship between miR-4537 and ZNF587, a luciferase reporter assay was performed. MiR-4537 was downregulated in GC tumors and cells and suppressed cell proliferation, while promoting cell apoptosis in GC. Importantly, we found that miR-4537 reduced the radioresistance of GC cells. In addition, we also confirmed that miR-4537 expression is negatively correlated with ZNF587 expression in GC tissues. MiR-4537 bound to ZNF587 and suppressed the expression level of ZNF587. Overexpression of ZNF587 partially counteracted the effects of miR-4537 on cell proliferation and apoptosis. In conclusion, in GC cells, miR-4537 inhibited the ability of cell proliferation, but on the contrary, it promoted the ability of cell apoptosis and improved radiosensitivity of the cells.

Prognostic value of microRNA-125a/b family in patients with gastric cancer: a meta-analysis

AIM

This meta-analysis was designed to reassess the prognostic and clinicopathologic values of the microRNA-125 family in GC patients.

BACKGROUND

The miR-125 family (including miR-125a, miR-125b) has been reported as being pivotal prognostic biomarkers of gastric cancer (GC). However, there is controversy about the role of the miR-125 family in predicting the progression of GC.

METHODS

The miR-125 family (including miR-125a, miR-125b) has been reported as being pivotal prognostic biomarkers of gastric cancer (GC). However, there is controversy about the role of the miR-125 family in predicting the progression of GC.

RESULTS

The electronic databases of PubMed, ISI Web of Science, Scopus, and Cochrane Library were systematically searched for relevant studies. Overall survival (OS) rate as the primary outcome from each study was extracted. The overall hazard ratio (HR or survival rate in patients with GC) and odds ratio (OR) with 95% confidence interval (CI) was calculated to evaluate the association between miR-125 family expression and prognosis and susceptibility to gastric cancer. The quality of evidence was evaluated using the Newcastle-Ottava Scale (NOS). The extracted data was combined based on the random-effects model.

CONCLUSION

The low expression of miR-125 family predicts poor OS in GC patients. Thus, the miR-125 family may be helpful as a potential biomarker for the prognosis of gastric cancer.

Upregulation of miR-1307-3p and its function in the clinical prognosis and progression of gastric cancer

Gastric cancer is one of the major causes of cancer-associated mortality worldwide. miR-1307-3p has been demonstrated to serve multiple roles in the development of various types of cancer. The present study aimed to evaluate the expression and functional role of miR-1307-3p in the progression of gastric cancer. The expression of miR-1307-3p in gastric cancer tissues and cell lines was detected by reverse transcription quantitative PCR. Furthermore, the correlation between miR-1307-3p expression and the clinicopathological characteristics and prognosis of patients was evaluated. Cell Counting Kit-8 and Transwell assays were performed to analyze the effects of miR-1307-3p on the proliferation and the migratory and invasive abilities of gastric cancer cells, respectively. Dual-luciferase reporter assay was conducted to reveal the potential underlying mechanism of miR-1307-3p. In gastric cancer tissues and cells, miR-1307-3p expression was significantly upregulated compared with the normal tissues and cell lines. In addition, the expression of miR-1307-3p was associated with the Tumor-Node Metastasis stage of patients. The results from Cox regression analysis demonstrated that miR-1307-3p may serve as an independent predictor for the prognosis of patients with gastric cancer. Furthermore, the upregulation of miR-1307-3p in gastric cancer cell lines significantly promoted the cell proliferation and migratory and invasive abilities by targeting DAB2 interacting protein. In conclusion, the findings from the present study suggested that miR-1307-3p may serve as a tumor promoter of gastric cancer and that miR-1307-3p expression in tumor tissues may be used as a prognostic indicator for patients with gastric cancer.

MicroRNA-195 controls MICU1 expression and tumor growth in ovarian cancer

MICU1 is a mitochondrial inner membrane protein that inhibits mitochondrial calcium entry; elevated MICU1 expression is characteristic of many cancers, including ovarian cancer. MICU1 induces both glycolysis and chemoresistance and is associated with poor clinical outcomes. However, there are currently no available interventions to normalize aberrant MICU1 expression. Here, we demonstrate that microRNA-195-5p (miR-195) directly targets the 3' UTR of the MICU1 mRNA and represses MICU1 expression. Additionally, miR-195 is under-expressed in ovarian cancer cell lines, and restoring miR-195 expression reestablishes native MICU1 levels and the associated phenotypes. Stable expression of miR-195 in a human xenograft model of ovarian cancer significantly reduces tumor growth, increases tumor doubling times, and enhances overall survival. In conclusion, miR-195 controls MICU1 levels in ovarian cancer and could be exploited to normalize aberrant MICU1 expression, thus reversing both glycolysis and chemoresistance and consequently improving patient outcomes.

miR-451: A Novel Biomarker and Potential Therapeutic Target for Cancer

MicroRNAs (miRNAs) are endogenous, non-coding, single-stranded small RNAs involved in a variety of cellular processes, including ontogeny, cell proliferation, differentiation, and apoptosis. They can also function as oncogenes or tumor suppressor genes. Recent studies have revealed that miRNA-451 (miR-451) is involved in the regulation of various human physiological and pathological processes. Furthermore, it has been shown that miR-451 not only directly affects the biological functions of tumor cells but also indirectly affects tumor cell invasion and metastasis upon secretion into the tumor microenvironment via exosomes. Thus, miR-451 also influences the progression of tumorigenesis and drug resistance. This review summarizes the expression of miR-451 in various cancer types and the relationship between miR-451 and the diagnosis, treatment, and drug resistance of solid tumors. In addition, we address possible mechanisms of action of miR-451 and its potential application as a biomarker in the diagnosis and treatment of human cancers.

miR-625 reverses multidrug resistance in gastric cancer cells by directly targeting ALDH1A1

Background: microRNAs (miRNAs) are emerging as critical regulators of multidrug resistance (MDR) in gastric cancer, a major cause of chemotherapy failure. miR-625 is downregulated in gastric cancer and negatively associated with metastasis. In the current study, we aimed to investigate whether miR-625 regulates MDR in gastric cancer.

Methods: The level of miR-625 in gastric cancer cells with or without MDR was quantified by quantitative reverse transcription PCR (qRT-PCR) analysis. The sensitivity of gastric cancer cells to chemotherapeutic agents was assessed by MTT assay. The protein expression was determined by Western blot analysis, and the luciferase reporter assay was applied to confirm miR-625 regulation of the potential target.

Results: miR-625 is downregulated in MDR gastric cancer cells compared with chemosensitive counterparts. In addition, miR-625 increases the sensitivity and promotes apoptosis of gastric cancer cells when treated with different chemotherapeutic agents. Moreover, miR-625 directly targets the aldehyde dehydrogenase 1A1 (ALDH1A1), and importantly, the restoration of ALDH1A1 expression rescues miR-625 effects on MDR in gastric cancer cells.

Conclusion: miR-625 reverses MDR in gastric cancer cells by targeting ALDH1A1. Hence, our study identifies miR-625 as a novel regulator of MDR in gastric cancer cells, and implicates its potential application for overcoming MDR in gastric cancer chemotherapy.

Upregulated miR-154 promotes ECM degradation in intervertebral disc degeneration

Intervertebral disc degeneration (IDD), a common global health issue, is a major cause for low back pain (LBP). Given the complex etiology of IDD, micro RNA (miRNA) recently has been demonstrated to play essential roles in the progression of IDD. Therefore, this study aims to investigate functions of the miR-154, which is well-documented in a series of cell activities, IDD, and other relevant mechanisms. Lumbar nucleus pulposus (NP) samples were collected from patients with IDD and the control group. After solexa sequencing and bioinformatical analysis, the results showed that miR-154 was increased in NP cells of patients with IDD. Inhibition of miR-154 increased type II collagen and aggrecan and decreased mRNA expressions of collagenase-3 (MMP13) and aggrecanase-1 (ADAMTS4), whereas overexpression of miR-154 reversed such effects in NP cells. In addition, the luciferase reporter assay revealed that fibroblast growth factor 14 (FGF14) is a direct target of miR-154 and that the overexpression of FGF14 leads to similar effects as inhibition of miR-154 did. In conclusion, the results suggested that miR-154 participates in the development of IDD and its effects are mediated via targeting FGF14. Thus, miR-154 may be thought as a potential etiological factor for IDD and may provide insights into a therapeutic target to treat IDD.

MicroRNA-1224 Inhibits Tumor Metastasis in Intestinal-Type Gastric Cancer by Directly Targeting FAK

Intestinal-type gastric cancer (GC) of the Lauren classification system has specific epidemiological characteristics and carcinogenesis patterns. MicroRNAs (miRNAs) have prognostic significance, and some can be used as prognostic biomarkers in GC. In this study, we identified miR-1224 as a potential survival-related miRNA in intestinal-type GC patients by The Cancer Genome Atlas (TCGA) analysis. Using quantitative real-time PCR (qRT-PCR), we showed that the relative expression of miR-1224 was significantly decreased in intestinal-type GC tissues compared to matched adjacent normal mucosa tissues (p < 0.01). We found that high miR-1224 expression was associated with no lymph-node metastasis (p < 0.05) and good prognosis (p = 0.028) in 90 intestinal-type GC tissues. Transfection of intestinal-type GC cells with miR-1224 mimics showed that miR-1224 suppressed cell migration in vitro (wound healing assay and Transwell migration assay), whereas the transfection of cells with miR-1224 inhibitor promoted cell migration in vitro. miR-1224 also suppressed intestinal-type GC cell metastasis in a xenograft mouse model. Furthermore, bioinformatics, luciferase reporter, Western blotting, and immunohistochemistry (IHC) studies demonstrated that miR-1224 directly bound to the focal adhesion kinase (FAK) gene, and downregulated its expression, which decreased STAT3 and NF-κB signaling and subsequent the epithelial-to-mesenchymal transition (EMT). Repression of FAK is required for the miR-1224-mediated inhibition of cell migration in intestinal-type GC. The present study demonstrated that miR-1224 is downregulated in intestinal-type GC. miR-1224 inhibits the metastasis of intestinal-type GC by suppressing FAK-mediated activation of the STAT3 and NF-κB pathways, and subsequent EMT. miR-1224 could represent an important prognostic factor in intestinal-type GC.

Integrated MicroRNA-mRNA Analysis Reveals miR-204 Inhibits Cell Proliferation in Gastric Cancer by Targeting CKS1B, CXCL1 and GPRC5A

Gastric cancer (GC) is the second most frequent cause of cancer-related deaths worldwide. MicroRNAs are single-stranded RNA molecules of 21–23 nucleotides that regulate target gene expression through specific base-pairing interactions between miRNA and untranslated regions of targeted mRNAs. In this study, we generated a multistep approach for the integrated analysis of miRNA and mRNA expression. First, both miRNA and mRNA expression profiling datasets in gastric cancer from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) identified 79 and 1042 differentially expressed miRNAs and mRNAs, respectively, in gastric cancer. Second, inverse correlations between miRNA and mRNA expression levels identified 3206 miRNA–mRNA pairs combined with 79 dysregulated miRNAs and their 774 target mRNAs predicted by three prediction tools, miRanda, PITA, and RNAhybrid. Additionally, miR-204, which was found to be down-regulated in gastric cancer, was ectopically over-expressed in the AGS gastric cancer cell line and all down-regulated targets were identified by RNA sequencing (RNA-seq) analysis. Over-expression of miR-204 reduced the gastric cancer cell proliferation and suppressed the expression of three targets which were validated by qRT-PCR and luciferase assays. For the first time, we identified that CKS1B, CXCL1, and GPRC5A are putative targets of miR-204 and elucidated that miR-204 acted as potential tumor suppressor and, therefore, are useful as a promising therapeutic target for gastric cancer.

Increased T-helper 17 cell differentiation mediated by exosome-mediated microRNA-451 redistribution in gastric cancer infiltrated T cells

MicroRNA (miR)‐451 is a cell metabolism‐related miRNA that can mediate cell energy‐consuming models by several targets. As miR‐451 can promote mechanistic target of rapamycin (mTOR) activity, and increased mTOR activity is related to increased differentiation of T‐helper 17 (Th17) cells, we sought to investigate whether miR‐451 can redistribute from cancer cells to infiltrated T cells and enhance the distribution of Th17 cells through mTOR. Real‐time PCR was used for detecting expression of miR‐451 in gastric cancer, tumor infiltrated T cells and exosomes, and distribution of Th17 was evaluated by both flow cytometry and immunohistochemistry (IHC). Immunofluorescence staining was used in monitoring the exosome‐enveloped miR‐451 from cancer cells to T cells with different treatments, and signaling pathway change was analyzed by western blot. miR‐451 decreased significantly in gastric cancer (GC) tissues but increased in infiltrated T cells and exosomes; tumor miR‐451 was negatively related to infiltrated T cells and exosome miR‐451. Exosome miR‐451 can not only serve as an indicator for poor prognosis of post‐operation GC patients but is also related to increased Th17 distribution in gastric cancer. miR‐451 can redistribute from cancer cells to T cells with low glucose treatment. Decreased 5′ AMP‐activated protein kinase (AMPK) and increased mTOR activity was investigated in miR‐451 redistributed T cells and the Th17 polarized differentiation of these T cells were also increased. Exosome miR‐451 derived from tumor tissues can serve as an indicator for poor prognosis and redistribution of miR‐451 from cancer cells to infiltrated T cells in low glucose treatment can enhance Th17 differentiation by enhancing mTOR activity.

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.

Identification of circulating microRNA signatures as potential noninvasive biomarkers for prediction and prognosis of lymph node metastasis in gastric cancer

Circulating microRNAs (miRNAs) are emerging as novel noninvasive biomarkers for prediction of lymph node metastasis (LNM) in cancer. The aim of this study was to identify serum miRNA signatures for prediction and prognosis of LNM in gastric cancer (GC). MiSeq sequencing was performed for an initial screening of serum miRNAs in 10 GC patients with LNM, 10 patients without LNM and 10 healthy controls. Reverse transcription quantitative real-time PCR was applied to confirm concentration of candidate miRNAs using a training cohort (n = 279) and a validation cohort (n = 180). We identified a four-miRNA panel (miR-501-3p, miR-143-3p, miR-451a, miR-146a) by multivariate logistic regression model that provided high predictive accuracy for LNM with an area under the receiver operating characteristic curve (AUC) of 0.891 (95% CI, 0.840 to 0.930) in training set. Prospective evaluation of this panel revealed an AUC of 0.822 (95% CI, 0.758 to 0.875, specificity = 87.78%, sensitivity = 63.33%) in validation set. Moreover, Kaplan-Meier analysis showed that LNM patients with low miR-451a and miR-146a levels had worse overall survival (OS) (p < 0.05). In Cox regression analysis, miR-451a was independently associated with OS of LNM (p = 0.028). Our results suggested that use of serum miRNAs seems promising in estimating the probability GC patients harbor LNM and providing prognostic information for LNM.

MiR-129-5p suppresses gastric cancer cell invasion and proliferation by inhibiting COL1A1

Gastric cancer (GC) is one of the most lethal cancers worldwide. In this study, we aimed to explore the role of miR-129-5p, a newly identified miR-129 member, in GC cells as well as the potential mechanism of action. The results of reverse transcription - qualitative polymerase chain reaction (RT-qPCR) and Western Blot showed that miR-129 was downregulated in GC cells compared with normal ones. Using MTT, colony formation, wound healing assay, and a Transwell assay, we evaluated the proliferation, migration, and invasion abilities of transfected cells, and confirmed miR-129-5p as a tumor suppressor in GC. After a microarray analysis comparing different gene expressions in miR-129-5p transfected SGC-7901 cells, COL1A1 was selected for biggest fold-change and potential target of miR-129-5p predicted by TargetScan. Measured by RT-qPCR and Western blot, COL1A1 turned out to be upregulated in GC tissues and cells. We further confirmed the targeting relationship between miR-129-5p and COL1A1 by dual luciferase assay. By manipulating the expression of COL1A1 in SGC-7901 cells, cell proliferation, migration, and invasion were examined and the tumor-promoting function of COL1A1 was validated. Moreover, co-transfection of miR-129-5p mimics and COL1A1 attenuated the tumor-promoting effects induced by a single-transfection of COL1A1, and miR-129-5p inhibitor counteracted the tumor-suppressing effects of COL1A1 siRNA. Collectively, the data demonstrate the important functions of the miR-129-5p-COL1A1 axis in GC: miR-129-5p suppresses GC cell proliferation, migration, and invasion, by selectively inhibiting COL1A1. This study provides new therapeutic targets for the clinical treatment of GC.

Epigenetic modulation associated with carcinogenesis and prognosis of human gastric cancer

Gastric cancer (GC) is a leading cause of cancer-related death, particularly in Asia. Epidemiological and other clinical studies have identified an association between a number of risk factors, including Helicobacter pylori, and GC. A number of studies have also examined genetic changes associated with the development and progression of GC. When considering the clinical significance of the expression of a specific gene, its epigenetic modulation should be considered. Epigenetic modulation appears to be a primary driver of changes in gastric tissue that promotes carcinogenesis and progression of GC and other neoplasms. The role of epigenetic modulation in GC carcinogenesis and progression has been widely studied in recent years. In the present review, recent results of epigenetic modulation associated with GC and their effects on clinical outcome are examined, with particular respect to DNA methylation, histone modulation and non-coding RNA. A number of studies indicate that epigenetic changes in the expression of specific genes critically affect their clinical significance and further study may reveal epigenetic changes as the basis for targeted molecular therapy or novel biomarkers that predict GC prognosis or extension of this often fatal disease.

Six Serum-Based miRNAs as Potential Diagnostic Biomarkers for Gastric Cancer

BACKGROUND

Circulating miRNAs in serum may serve as promising diagnostic biomarkers for patients with gastric cancer.

METHODS

Using qRT-PCR-based Exiqon panel, we identified 58 differentially expressed miRNAs from three gastric cancer pool samples and one normal control (NC) pool in the initial screening phase. Identified miRNAs were further validated in the training (49 gastric cancer vs. 47 NCs) and validation phases (154 gastric cancer vs. 120 NCs) using qRT-PCR. The expression levels of the miRNAs were also determined in tissues, arterial serum, and exosomes.

RESULTS

Consequently, six serum miRNAs (miR10b-5p, miR132-3p, miR185-5p, miR195-5p, miR-20a3p, and miR296-5p) were significantly overexpressed in gastric cancer compared with NCs. The areas under the receiver operating characteristic curve of the six-miRNA panel were 0.764 and 0.702 for the training and validation phases, respectively. miR10b-5p and miR296-5p were significantly upregulated in gastric cancer tissues (n = 188). In addition, patients who did not receive adjuvant chemotherapy with high expression of miR10b-5p or miR296-5p in tissues tended to suffer worse overall survival. Furthermore, the expression levels of miR10b-5p, miR195-5p, miR20a-3p, and miR296-5p were significantly elevated in exosomes from gastric cancer serum samples (n = 30).

CONCLUSIONS

We identified a six-miRNA panel in serum for the detection of gastric cancer.

IMPACT

Our findings provide a novel serum miRNA signature for gastric cancer diagnosis, and will serve as the basis of the application of circulating miRNAs in clinical for the detection of gastric cancer in the future. Cancer Epidemiol Biomarkers Prev; 26(2); 188-96. ©2016 AACR.

Expression pattern of miR-451 and its target MIF (macrophage migration inhibitory factor) in colorectal cancer

AIMS

To investigate the expression pattern of microRNA-451 (miR-451) in patients with colorectal carcinoma and correlate with the expression of its target gene MIF (macrophage migration inhibitory factor).

METHODS

Matched cancer and non-cancer fresh frozen tissues were prospectively collected from 70 patients (35 men and 35 women) who underwent resection of colorectal adenocarcinoma. These tissues collected were extracted for miR and complementary DNA conversion. Then, miR-451 expressions in these tissues were measured by quantitative real-time PCR. The expression was correlated with clinical and pathological parameters of these patients. In addition, paraffin blocks of 10 colorectal carcinomas with lowest expression of miR-451 were used for the study of MIF protein expression by immunohistochemistry.

RESULTS

miR-451 was downregulated in majority of the colorectal cancer tissues when compared with their matched normal tissues (84.3%, n=59/70). Downregulation of miR-451 correlates significantly with presence of coexisting adenoma (91.4%, p=0.025). In addition, persistence of cancer or cancer recurrence after surgery showed significant correlation with downregulation of miR-451 (80% vs 0%; p=0.028). There is no significant correlation between miR-451 expression and age, gender of the patients as well as size, grades, pathological stages, presence of lymphovascular permeation, perineural invasion and microsatellite instability status of the colorectal carcinoma (p>0.05). Majority of the cases (80%) with low expression of miR-451 showed high levels of MIF protein expression confirming the inverse relationship between miR-451 and MIF expressions.

CONCLUSIONS

The results showed that miR-451 could play a role in development and progression of colorectal cancer and likely by targeting MIF.

Identification of microRNA-regulated pathways using an integration of microRNA-mRNA microarray and bioinformatics analysis in CD34+ cells of myelodysplastic syndromes

The effect of microRNA (miRNA) and targeted mRNA on signal transduction is not fully understood in myelodysplastic syndromes (MDS). Here, we tried to identify the miRNAs-regulated pathways through a combination of miRNA and mRNA microarray in CD34+ cells from MDS patients. We identified 34 differentially expressed miRNAs and 1783 mRNAs in MDS. 25 dysregulated miRNAs and 394 targeted mRNAs were screened by a combination of Pearson’s correlation analysis and software prediction. Pathway analysis showed that several pathways such as Notch, PI3K/Akt might be regulated by those miRNA-mRNAs pairs. Through a combination of Pathway and miRNA-Gene or GO-Network analysis, miRNAs-regulated pathways, such as miR-195-5p/DLL1/Notch signaling pathway, were identified. Further qRT-PCR showed that miR-195-5p was up-regulated while DLL1 was down-regulated in patients with low-grade MDS compared with normal controls. Luciferase assay showed that DLL1 was a direct target of miR-195-5p. Overexpression of miR-195-5p led to increased cell apoptosis and reduced cell growth through inhibition of Notch signaling pathway. In conclusion, alteration expression of miRNAs and targeted mRNAs might have an important impact on cancer-related cellular pathways in MDS. Inhibition of Notch signaling pathway by miR-195-5p-DLL1 axis contributes to the excess apoptosis in low-grade MDS.

miR‑483‑5p promotes growth, invasion and self‑renewal of gastric cancer stem cells by Wnt/β‑catenin signaling

Gastric carcinoma (GC) ranks as the second most common cause of cancer‑associated mortality worldwide. Emerging evidence has suggested a potential novel therapeutic strategy based on the ability of cancer stem cells (CSCs) to trigger tumorigenesis. MicroRNAs (miRNAs) have previously been implicated in CSC formation and regulation of their functional characteristics. In the current study, a significant upregulation of miR‑483‑5p levels was demonstrated in spheroid body‑forming cells (P<0.01) by reverse transcription‑quantitative polymerase chain reaction, which were isolated from the MKN‑45 gastric cancer cell line and possessed gastric CSC (GCSC) properties. An MTT assay demonstrated that overexpression of miR‑483‑5p by transfection with miR‑483‑5p mimics significantly increased cell proliferation and Annexin V‑propidium iodide staining indicated the suppression of cell apoptosis, suggesting that miR‑483‑5p has an important function in GCSC growth. Notably, Transwell and sphere formation assays demonstrated that miR‑483‑5p elevation promoted GCSC invasion and cell self‑renewal ability, respectively. Further western blotting assays demonstrated that miR‑483‑5p upregulation induced an increase in the protein expression levels of β‑catenin and its downstream target molecules, including cyclin D1, Bcl‑2 and matrix metalloproteinase 2, indicating that miR‑483‑5p activates Wnt/β‑catenin signaling. Inhibition of this pathway by β‑catenin small interfering RNA transfection attenuated the miR‑483‑5p‑induced effects on cell growth, invasion and self‑renewal. These results demonstrate that miR‑483‑5p may act as an oncogene to promote the development of GC by regulating GCSC growth, invasion and self‑renewal via the Wnt/β‑catenin signaling pathway. Thus, the present study suggests that miR‑483‑5p may be a promising therapeutic target against GC.

microRNA-199a-3p functions as tumor suppressor by regulating glucose metabolism in testicular germ cell tumors

microRNA (miR)-199a-3p serves critical roles in cancer development and progression. In order to improve knowledge of the functional mechanism of miR‑199a‑3p in testicular tumors, the present study characterized the regulation of aerobic glycolysis by miR‑199a‑3p and its impact on metabolism. Using 3‑4,5‑dimethylthiazol‑2‑yl‑2,5 diphenyl tetrazolium bromide, wound healing and flow cytometry assays, it was determined that overexpression of miR‑199a‑3p in Ntera‑2 cells caused suppression of cell growth and migration. Further biochemical methods and high‑throughput quantitative polymerase chain reaction array of metabolic genes showed that inhibition of miR‑199a‑3p markedly elevated lactate production and 12 differentially expressed genes, including 2 upregulated and 10 downregulated genes, were identified following treatment with miR‑199a‑3p in Ntera‑2 cells. In clinical samples, four selected genes, lactate dehydrogenase A, monocarboxylate transporter 1, phosphoglycerate kinase 1 and TP53‑inducible glycolysis and apoptosis regulator, were significantly overexpressed in malignant testicular germ cell tumor, and their expression inversely correlated with the expression of miR‑199a‑3p, suggesting that these four genes may be affected by miR‑199a‑3p. Using bioinformatics analysis, the transcription factor Sp1 binding site was identified in the promoter region of the four selected genes. In addition, miR‑199a‑3p was predicted to bind to conservative target sequences in the 3'‑untranslated region of Sp1 mRNA, suggesting that miR-199a-3p may downregulate these four metabolic genes through Sp1. It was demonstrated the dysregulated expression and activation of miR‑199a‑3p may serve important roles in aerobic glycolysis and tumorigenesis in patients with testicular cancer. Therefore, miR-199a-3p may be a potential biomarker in the prognosis and treatment of testicular tumors.

Potential Diagnostic, Prognostic and Therapeutic Targets of MicroRNAs in Human Gastric Cancer

Human gastric cancer (GC) is characterized by a high incidence and mortality rate, largely because it is normally not identified until a relatively advanced stage owing to a lack of early diagnostic biomarkers. Gastroscopy with biopsy is the routine method for screening, and gastrectomy is the major therapeutic strategy for GC. However, in more than 30% of GC surgical patients, cancer has progressed too far for effective medical resection. Thus, useful biomarkers for early screening or detection of GC are essential for improving patients’ survival rate. MicroRNAs (miRNAs) play an important role in tumorigenesis. They contribute to gastric carcinogenesis by altering the expression of oncogenes and tumor suppressors. Because of their stability in tissues, serum/plasma and other body fluids, miRNAs have been suggested as novel tumor biomarkers with suitable clinical potential. Recently, aberrantly expressed miRNAs have been identified and tested for clinical application in the management of GC. Aberrant miRNA expression profiles determined with miRNA microarrays, quantitative reverse transcription-polymerase chain reaction and next-generation sequencing approaches could be used to establish sample specificity and to identify tumor type. Here, we provide an up-to-date summary of tissue-based GC-associated miRNAs, describing their involvement and that of their downstream targets in tumorigenic and biological processes. We examine correlations among significant clinical parameters and prognostic indicators, and discuss recurrence monitoring and therapeutic options in GC. We also review plasma/serum-based, GC-associated, circulating miRNAs and their clinical applications, focusing especially on early diagnosis. By providing insights into the mechanisms of miRNA-related tumor progression, this review will hopefully aid in the identification of novel potential therapeutic targets.

By downregulating TIAM1 expression, microRNA-329 suppresses gastric cancer invasion and growth

Gastric cancer (GC) is one of the most common malignant tumors worldwide. Emerging evidence has shown that abnormal microRNAs (miRNAs) expression is involved in tumorigenesis. MiR-329 was previously reported to act as a tumor suppressor or oncogene in some types of cancer. However, its function in gastric cancer (GC) is unclear. Here, we found that miR-329 was down-regulated in GC compared with adjacent controls. Enforced expression of miR-329 inhibited proliferation, migration and invasion of gastric cancer cells in vitro. We identified T lymphoma invasion and metastasis 1 (TIAM1) gene as potential target of miR-329. MiR-329 levels inversely correlated with TIAM1 expression in GC. Importantly, TIAM1 rescued the miR-329-mediated inhibition of cell invasion and proliferation. Finally, reintroduction of miR-329 significantly inhibited tumor formation of GC in the xenograft mice. Our findings suggest that miR-329 is a tumor suppressor and potential therapeutic target of GC

The Pleiotropic Effects of miRNAs on Tumor Angiogenesis

Angiogenesis, the process of new blood vessel formation and growth from already existing venules is critical in vascular development and homeostasis controlled by the balance of pro- and anti-angiogenic factors. Emerging evidence indicates the development, progression, and metastasis of various human cancers are strongly relied on angiogenesis. However, molecular mechanisms that underlie the complex regulation of angiogenic processes are still not fully elucidated. Recent studies revealed that microRNAs (miRNAs) were important regulators of tumor angiogenesis and the entire research in this area has entered into a so-called "miRNAs era." Thus, miRNAs might be important therapeutic targets or biomarkers for cancer. Due to the complexity of miRNA regulating mechanisms, how specific miRNAs intersect with and modulate tumor angiogenesis is still unclear. The conflicting results of the same miRNAs from different groups indicated that miRNAs might possess potent activity in a cell type or cell context specific manner. Here, we present a summary of latest advances in understanding the roles of angiogenic miRNAs as potential tools or targets in cancer therapy.

The conglomeration of diagnostic, prognostic and therapeutic potential of serum miR-199a and its association with clinicopathological features in epithelial ovarian cancer

Epithelial ovarian cancer (EOC) is the most lethal cause of morbidity and mortality worldwide. miRNA deregulation evinces a remarkable role in ovarian cancer tumorigenesis. miRNA-199a (miR-199a) is known to be involved in cancer development and progression. Although miR-199a has been studied in various cell types, its correlation with clinicopathological features in EOC has not been documented. In this study, we identified the clinicopathological hallmarks which might be perturbed due to the downregulation of serum miR-199a in EOC. Seventy serum samples from histopathologically confirmed EOC patients and 70 controls were collected. Total RNA from serum was isolated by Trizol method, polyadenylated and reverse transcribed into cDNA. Expression level of miR-199a was detected by using miRNA qRT-PCR. Relative expression was determined with matched controls using U6 snRNA as reference. Level of miR-199a expression was compared with distinct clinicopathological features. Expression of miR-199a was found to be significantly downregulated in comparison with matched normal controls. The expression level of miR-199a was found to be significantly associated with tumor stage, lymph node metastasis, and distal metastasis. Receiver operating characteristic (ROC) curve for diagnostic potential yielded significant area under the curve (AUC) with a considerable sensitivity and specificity. ROC curves for prognosis yielded significant AUCs for histological grade, distal metastasis, lymph node status, and survival. Our findings suggest that miR-199a downregulation might be a potential indicator for disease progression promoting the aggressive tumor progression and be identified as a diagnostic marker to predict the prognosis and survival in EOC patients.

The hypoxia-related microRNA miR-199a-3p displays tumor suppressor functions in ovarian carcinoma

During the dissemination of ovarian cancer cells, the cells float in the peritoneal cavity without access to a vascular supply and so are exposed to hypoxic conditions, which may cause the ovarian cancer cells to acquire a more aggressive and malignant phenotype. In this study, we screened microRNAs (miRNAs) to identify those that displayed altered expression patterns under hypoxic conditions and then analyzed their functional roles in ovarian cancer progression. miRNA PCR arrays performed on cells from 2 ovarian cancer cell lines (CaOV3 and RMUG-S) revealed miR-199a-3p as one of the miRNAs that are downregulated under hypoxia. In silico analyses indicated that MET is one of the target genes for miR-199a-3p; subsequently, miR-199a-3p expression was found to be inversely correlated with c-Met expression in ovarian cancer. Transfection of precursor miR-199a-3p into ovarian cancer cells reduced c-Met expression and inhibited the phosphorylation of c-Met, extracellular signal-regulated kinase, and AKT; in addition, proliferation, adhesion, and invasiveness were inhibited. Moreover, overexpression of miR-199a-3p in cancer cells significantly suppressed peritoneal dissemination in a xenograft model. In summary, the hypoxia-related microRNA miR-199a-3p drastically inhibits ovarian cancer progression through the downregulation of c-Met expression. Therefore, miR-199a-3p is a potential target for treating ovarian cancer dissemination.

Effects of Aloe-emodin and Emodin on Proliferation of the MKN45 Human Gastric Cancer Cell Line

Aloe-emodin (1, 8-dihydroxy-3-hydroxyl-methylanthraquinone; AE) and emodin (1,3,8-trihydroxy-6- methylanthraquinone; EM) are anthraquinone derivatives that have been detected in some medical plants and share similar anthraquinone structures. AE and EM have been shown to exhibit anticancer activities in various cancer cell lines; however, the inhibitory effects of these derivatives on the growth of cancer cells were previously reported to be different. Gastric cancer is the second most common cause of cancer cell death worldwide. In the present study, we examined the inhibitory effects of 0.05 mM AE and 0.05 mM EM on the proliferation of the MKN45 human gastric cancer cell line. The proliferation of MKN45 cells was significantly inhibited in AE- and EM-treated groups 24 h and 48 h after treatment. Furthermore, the inhibitory effects of EM were stronger than those of AE. The cell cycle of MKN45 cells were arrested in G0/G1 phase or G0/G1 and G2/M phases by AE and EM, respectively. However, an analysis of intracellular polyamine levels and DNA fragmentation revealed that the mechanisms underlying cell death following cell arrest induced by AE and EM differed.

MiR-195 suppresses non-small cell lung cancer by targeting CHEK1

MiR-195 suppresses tumor growth and is associated with better survival outcomes in several malignancies including non-small cell lung cancer (NSCLC). Our previous study showed high miR-195 plasma levels associated with favorable overall survival of non-smoking women with lung adenocarcinoma. To further elucidate role of miR-195 in NSCLC, we conducted in vitro experiment as well as clinical studies in a cohort of 299 NSCLC samples. We demonstrated that miR-195 expression was lower in tumor tissues and was associated with poor survival outcome. Overexpression of miR-195 suppressed tumor cell growth, migration and invasion. We discovered that CHEK1 was a direct target of miR-195, which decreased CHEK1 expression in lung cancer cells. High expression of CHEK1 in lung tumors was associated with poor overall survival. Our results suggest that miR-195 suppresses NSCLC and predicts lung cancer prognosis.

Comparison of Prognostic MicroRNA Biomarkers in Blood and Tissues for Gastric Cancer

Gastric cancer (GC) still keeps up high mortality worldwide with poor prognosis. Efficient and non-invasive prognostic biomarkers are urgently needed. MicroRNAs are non-coding RNAs playing roles in post-transcriptional gene regulation, which contribute to various biological processes such as development, differentiation and carcinogenesis. MicroRNA expression profiles have been associated with the prognosis and outcome in GC. MicroRNA prognostic biomarkers have been identified from blood or tissues samples, but with different prognostic features. Understanding the various roles of microRNAs in different sample sources of GC will provide deep insights into GC progression. In this review, we highlight the distinct prognostic roles of microRNAs biomarkers in blood and tissue according to their relationships with prognostic parameters, survival rates and target pathways. This will be useful for non-invasive biomarker development and selection in prognosis of GC.

miR-935 suppresses gastric signet ring cell carcinoma tumorigenesis by targeting Notch1 expression

Gastric signet ring cell carcinoma (GSRCC) is a unique pathological type of gastric carcinoma that is extremely invasive and has a poor prognosis. Expression of microRNAs (miRNAs) has been closely linked to the carcinogenesis of gastric cancer and has been considered as a powerful prognostic marker. The function of miR-935 has never been reported in cancer before. We found, using microRNA array, that expression of miR-935 in GSRCC cell lines is lower than in non-GSRCC cell lines, and enhanced expression of miR-935 in GSRCC cell-lines inhibit cell proliferation, migration and invasion. We also identified Notch1 as a direct target of miR-935. Knockdown of Notch1 reduced proliferation, migration/invasion of GSRCC cells, and overexpression Notch1's activated form (Notch intracellular domain) could rescue miR-935's tumor suppressive effect on GSRCC. Expression of miR-935 was lower in gastric carcinoma tissue than in paired normal tissue samples, and lower in GSRCC than in non-GSRCC. Our results demonstrate the inverse correlation between the expression of miR-935 and Notch1 in gastric tissues. We conclude that miR-935 inhibits gastric carcinoma cell proliferation, migration and invasion by targeting Notch1, suggesting potential applications of the miR-935-Notch1 pathway in gastric cancer clinical diagnosis and therapeutics, especially in gastric signet ring cell carcinoma.

miR-195 is a key regulator of Raf1 in thyroid cancer

Proto-oncogene Raf1 serves as a part of the mitogen-activated protein kinases/extracellular signal-regulated kinase signal transduction pathway and regulates cell migration, apoptosis, and differentiation. Although a large number of studies have shown that Raf1 is overexpressed in various kinds of cancer, little is known about the association between Raf1 and miRNAs in thyroid carcinoma. This study proves that Raf1 is overexpressed in thyroid cancer, which has been confirmed by many other studies. Besides, we identify that Raf1 is a direct target of miR-15a/b, miR-16, and miR-195 by dual luciferase reporter assay. We also find that the expression of miR-195 is downregulated in 50 pairs of thyroid tumor tissues compared to the adjacent nontumor tissues, while there is no difference in the expression of miR-15a/b and miR-16 between the groups. Furthermore, exogenous overexpression of miR-195 significantly inhibits the protein expression of Raf1 and blocks the thyroid cancer cell proliferation. Our findings delineate a novel mechanism for the regulation of Raf1 in thyroid cancer, which may help to provide a new direction for the treatment of thyroid cancer.

miR-101-2, miR-125b-2 and miR-451a act as potential tumor suppressors in gastric cancer through regulation of the PI3K/AKT/mTOR pathway

BACKGROUND

Gastric cancer (GC) is a deadly malignancy worldwide. In the past, it has been shown that cellular signaling pathway alterations play a crucial role in the development of GC. In particular, deregulation of the PI3K/AKT/mTOR pathway seems to affect multiple GC functions including growth, proliferation, metabolism, motility and angiogenesis. Targeting alterations in this pathway by microRNAs (miRNAs) represents a potential therapeutic strategy, especially in inhibitor-resistant tumors. The objective of this study was to evaluate the expression of 3 pre-selected miRNAs, miR-101-2, miR-125b-2 and miR-451a, in a series of primary GC tissues and matched non-GC tissues and in several GC-derived cell lines, and to subsequently evaluate the functional role of these miRNAs.

METHODS

Twenty-five primary GC samples, 25 matched non-GC samples and 3 GC-derived cell lines, i.e., AGS, MKN28 and MKN45, were included in this study. miRNA and target gene expression levels were assessed by quantitative RT-PCR and western blotting, respectively. Subsequently, cell viability, clone formation, cell death, migration and invasion assays were performed on AGS cells.

RESULTS

miR-101-2, miR-125b-2 and miR-451a were found to be down-regulated in the primary GC tissues and the GC-derived cell lines tested. MiRNA mimic transfections significantly reduced cell viability and colony formation, increased cell death and reduced cell migration and invasion in AGS cells. We also found that exogenous expression of miR-101-2, miR-125b-2 and miR-451a decreased the expression of their putative targets MTOR, PIK3CB and TSC1, respectively.

CONCLUSIONS

Our expression analyses and in vitro functional assays suggest that miR-101-2, miR-125b-2 and miR-451a act as potential tumor suppressors in primary GCs as well as in GC-derived AGS cells.

c-Myc Represses Tumor-Suppressive microRNAs, let-7a, miR-16 and miR-29b, and Induces Cyclin D2-Mediated Cell Proliferation in Ewing's Sarcoma Cell Line

Myc oncogenic transcription factor is known to inhibit tumor suppressive microRNAs (miRNAs), resulting in greater expression of their target protein related to cell cycle, invasion or anti-apoptotic factors in human cancer cells. To explore possible oncogenic factors in Ewing’s sarcoma (ES), we conducted microarray-based approach to profile the changes in the expression of miRNAs and its downstream mRNAs in five ES cell lines and human mesenchymal stem cells (hMSCs). Three miRNAs, let-7a, miR-16 and miR-29b were significantly down-regulated, whereas c-Myc and cyclin D2 (CCND2) were significantly up-regulated in all tested ES cells compared with hMSCs. To verify that let-7a, miR-16 and miR-29b were the targets of c-Myc in ES cell lines, we transfected siRNA against c-Myc and confirmed the coordinate up-regulation of let-7a, miR-16 and miR-29b through the repression of c-Myc. The ES cells transfected with c-Myc-siRNA and let-7a, miR-16 and miR-29b exhibited the inhibition of the cell cycle progression. The increased expression of let-7a, miR-16 and miR-29b resulted in the reduction of CCND2 protein expression. We also demonstrated that c-Myc-siRNA treatment of ES cells was associated with the decreased expression of CCND2 as a down-stream of three miRNAs. Furthermore, the introduction of let-7a, miR-16 and miR-29b in ES cells could inhibit the c-Myc-mediated up-regulation of CCND2 resulted in the prevention of cell cycle progression. In addition, the transfection of let-7a, miR-16 and miR-29b in ES cells suppressed tumor growth ex vivo treatment. These findings suggests that the up-regulation of c-Myc inhibited the expression of let-7a, miR-16 and miR-29b subsequently induced CCND2 expression in ES cells. The present study might identify a novel oncogenic axis that c-Myc regulates the expression of CCND2 via let-7a, miR-16 and miR-29b, leading to the development new therapeutic targets for ES.

Molecular classification and prediction in gastric cancer

Gastric cancer, a highly heterogeneous disease, is the second leading cause of cancer death and the fourth most common cancer globally, with East Asia accounting for more than half of cases annually. Alongside TNM staging, gastric cancer clinic has two well-recognized classification systems, the Lauren classification that subdivides gastric adenocarcinoma into intestinal and diffuse types and the alternative World Health Organization system that divides gastric cancer into papillary, tubular, mucinous (colloid), and poorly cohesive carcinomas. Both classification systems enable a better understanding of the histogenesis and the biology of gastric cancer yet have a limited clinical utility in guiding patient therapy due to the molecular heterogeneity of gastric cancer. Unprecedented whole-genome-scale data have been catalyzing and advancing the molecular subtyping approach. Here we cataloged and compared those published gene expression profiling signatures in gastric cancer. We summarized recent integrated genomic characterization of gastric cancer based on additional data of somatic mutation, chromosomal instability, EBV virus infection, and DNA methylation. We identified the consensus patterns across these signatures and identified the underlying molecular pathways and biological functions. The identification of molecular subtyping of gastric adenocarcinoma and the development of integrated genomics approaches for clinical applications such as prediction of clinical intervening emerge as an essential phase toward personalized medicine in treating gastric cancer.

MiR-451, a potential prognostic biomarker and tumor suppressor for gastric cancer

BACKGROUND

The expression of microRNA-451 (miR-451) and its association with clinical pathological factors in GC remain still unclear. The purpose of this study was to investigate if miR-451 is a potential prognostic biomarker and tumor suppressor for gastric cancer.

METHODS

Real-time quantitative RT-PCR (qRT-PCR) was applied to detect miR-451 expression in GC cell lines and primary tumor and paired non-cancerous tissues. The association of miR-451 expression with clinicopathological factors and prognosis was statistically analyzed.

RESULTS

We found that miR-451 showed decreased expression in GC tissues and cell lines, and its down-regulation tended to be positively correlated with lymphatic metastasis, clinical staging and shorter overall survival of patients. In addition, forced expression of miR-451 in BGC-823 and MKN-45 cells did not impact on cell proliferation, but did reduce migration and invasion rates in BGC-823 cells.

CONCLUSION

Our findings indicated that miR-451 may act as a novel prognostic marker and potential therapeutic target in human GC.

Circulating miR-25-3p and miR-451a May Be Potential Biomarkers for the Diagnosis of Papillary Thyroid Carcinoma

OBJECTIVE

There is no effective and reliable biomarker to distinguish benign thyroid nodules from papillary thyroid carcinomas (PTC). This study aimed at examining the levels of plasma miRNAs in patients with PTC or benign nodules to explore the potential miRNA biomarkers for PTC.

PATIENTS AND METHODS

Genome-wide plasma miRNA expression profiles were determined by the miRNA Microarray and the significantly higher levels of miRNAs were validated in plasma and tissues by quantitative RT-PCR. The levels of two miRNAs were further tested in seven patients before and after tumor excision and the potential values for the diagnosis of PTC were evaluated by receiver operating characteristic curve (ROC).

RESULTS

In comparison with that in the patients with benign nodules, eight significantly higher and three lower levels of plasma miRNAs were detected in the PTC patients. Further validation indicated that the levels of plasma miR-25-3p, miR-451a, miR-140-3p and let-7i were significantly higher in the PTC cases than in those with benign nodules or the healthy controls. Significantly higher levels of miR-25-3p and miR-451a were detected in the thyroid tissues from the PTC patients. The levels of plasma miR-25-3p and miR-451a in seven patients significantly decreased after tumor excision. ROC analyses revealed that the levels of plasma miR-25-3p at cut-off 1.41 and miR-451a at 1.38 had sensitivity of 92.8% and 88.9%, and specificity of 68.8% and 66.7% for distinguishing PTC from benign nodules, respectively.

CONCLUSION

Our findings suggest that the levels of plasma miR-25-3p and miR-451a may be valuable for the diagnosis of PTC.

A miRNA-Based Signature Detected in Primary Melanoma Tissue Predicts Development of Brain Metastasis

PURPOSE

Brain metastasis is the major cause of mortality among patients with melanoma. A molecular prognostic test that can reliably stratify patients at initial melanoma diagnosis by risk of developing brain metastasis may inform the clinical management of these patients.

EXPERIMENTAL DESIGN

We performed a retrospective, cohort-based study analyzing genome-wide and targeted microRNA expression profiling of primary melanoma tumors of three patient cohorts (n = 92, 119, and 45) with extensive clinical follow-up. We used Cox regression analysis to establish a microRNA-based signature that improves the ability of the current clinicopathologic staging system to predict the development of brain metastasis.

RESULTS

Our analyses identified a 4-microRNA (miR-150-5p, miR-15b-5p, miR-16-5p, and miR-374b-3p) prognostic signature that, in combination with stage, distinguished primary melanomas that metastasized to the brain from nonrecurrent and non-brain metastatic primary tumors (training cohort: C-index = 81.4%, validation cohort: C-index = 67.4%, independent cohort: C-index = 76.9%). Corresponding Kaplan-Meier curves of high- versus low-risk patients displayed a clear separation in brain metastasis-free and overall survival (training: P < 0.001; P < 0.001, validation: P = 0.033; P = 0.007, independent: P = 0.021; P = 0.022, respectively). Finally, of the microRNA in the prognostic model, we found that the expression of a key lymphocyte miRNA, miR-150-5p, which is less abundant in primary melanomas metastatic to brain, correlated with presence of CD45(+) tumor-infiltrating lymphocytes.

CONCLUSIONS

A prognostic assay based on the described miRNA expression signature combined with the currently used staging criteria may improve accuracy of primary melanoma patient prognoses and aid clinical management of patients, including selection for adjuvant treatment or clinical trials of adjuvant therapies.

Screening of differential microRNA expression in gastric signet ring cell carcinoma and gastric adenocarcinoma and target gene prediction

Gastric signet ring cell carcinoma (GSRCC) is a unique pathological type of gastric carcinoma that is extremely invasive and has a poor prognosis after diagnosis. The expression of microRNAs has been closely linked to the carcinogenesis of gastric cancer and has been considered as a powerful prognostic marker. Distinctive expression of miRNAs in GSRCC was investigated in the present study. Samples of GSRCC were compared to that of intestinal gastric adenocarcinoma using Agilent microarray technique, and two differentially expressed miRNAs were identified, hsa-miR-665 and hsa-miR‑95. qRT-PCR verification showed downregulation of both miRNAs in signet ring cell carcinoma and upregulation in gastric adenocarcinoma, which was not consistent with the results obtained by the microarray. Target gene prediction using online databases conferred two strong candidate genes, GLI2 and PLCG1. GO/KO analysis of these two genes showed close correlations with carcinogenesis and chemoresistance. It was concluded that hsa-miR-665 and hsa-miR-95 were downregulated in GSRCC but upregulated in intestinal gastric adenocarcinoma, and the relatively differential expression of the miRNAs negatively controlling their target genes could be closely related to the high invasive metastasis and chemoresistance of GSRCC.

MicroRNA in intervertebral disc degeneration

Aetiology of intervertebral disc degeneration (IDD) is complex, with genetic, developmental, biochemical and biomechanical factors contributing to the disease process. It is becoming obvious that epigenetic processes influence evolution of IDD as strongly as the genetic background. Deregulated phenotypes of nucleus pulposus cells, including differentiation, migration, proliferation and apoptosis, are involved in all stages of progression of human IDD. Non-coding RNAs, including microRNAs, have recently been recognized as important regulators of gene expression. Research into roles of microRNAs in IDD has been very active over the past 5 years. Our review summarizes current research enlightenment towards understanding roles of microRNAs in regulating nucleus pulposus cell functions in IDD. These exciting findings support the notion that specific modulation of microRNAs may represent an attractive approach for management of IDD.

Analysis of miRNA expression profiles in breast cancer using biclustering

Background

MicroRNAs (miRNAs) are important key regulators in multiple cellular functions, due to their a crucial role in different physiological processes. MiRNAs are differentially expressed in specific tissues, during specific cell status, or in different diseases as tumours. RNA sequencing (RNA-seq) is a Next Generation Sequencing (NGS) method for the analysis of differential gene expression. Using machine learning algorithms, it is possible to improve the functional significance interpretation of miRNA in the analysis and interpretation of data from RNA-seq. Furthermore, we tried to identify some patterns of deregulated miRNA in human breast cancer (BC), in order to give a contribution in the understanding of this type of cancer at the molecular level.

Results

We adopted a biclustering approach, using the Iterative Signature Algorithm (ISA) algorithm, in order to evaluate miRNA deregulation in the context of miRNA abundance and tissue heterogeneity. These are important elements to identify miRNAs that would be useful as prognostic and diagnostic markers. Considering a real word breast cancer dataset, the evaluation of miRNA differential expressions in tumours versus healthy tissues evidenced 12 different miRNA clusters, associated to specific groups of patients. The identified miRNAs were deregulated in breast tumours compared to healthy controls. Our approach has shown the association between specific sub-class of tumour samples having the same immuno-histo-chemical and/or histological features. Biclusters have been validated by means of two online repositories, MetaMirClust database and UCSC Genome Browser, and using another biclustering algorithm.

Conclusions

The obtained results with biclustering algorithm aimed first of all to give a contribute in the differential expression analysis in a cohort of BC patients and secondly to support the potential role that these non-coding RNA molecules could play in the clinical practice, in terms of prognosis, evolution of tumour and treatment response.

Inhibition of microRNA-25 by tumor necrosis factor α is critical in the modulation of vascular smooth muscle cell proliferation

Atherosclerosis and coronary heart disease are characterized by a hyperplastic neointima and inflammation involving cytokines, such as tumor necrosis factor‑α (TNF‑α). TNF‑α is pleiotropic and mediates inflammation and proliferation in various cell types, such as vascular smooth muscle cells (VSMCs). The molecular mechanism for the pleiotropic effects of TNF‑α has not previously been fully elucidated. The current study identified that the expression of microRNA‑25 (miR‑25), a small noncoding RNA, was reduced in response to TNF‑α signaling in VSMCs. Restored miR‑25 expression inhibited cell proliferation and Ki‑67 expression. The present study indicated that cyclin‑dependent kinase 6 (CDK6) was the direct target gene of miR‑25 using mRNA and protein expression analysis, and luciferase assays. It was also observed that restored CDK6 expression in the miR‑25 mimic‑treated VSMCs partly reduced miR‑25‑mediated VSMC proliferation. In conclusion, miR‑25 is suggested to be important in TNF‑α‑induced abnormal proliferation of VSMCs.

MiR-199a-3p promotes gastric cancer progression by targeting ZHX1

Accumulating evidence has indicated that microRNAs (miRNAs) act as critical epigenetic regulators in tumor carcinogenesis. Here, we report that miR-199a-3p was significantly upregulated in gastric cancer (GC) cell lines and tissues. Functional studies demonstrated that miR-199a-3p dramatically increased cell proliferation and suppressed cell apoptosis both in vitro and in vivo. Furthermore, the transcriptional regulator zinc fingers and homeoboxes 1 (ZHX1) was identified as one of the direct downstream targets of miR-199a-3p, miR-199a-3p bound to the ZHX1 3′ untranslated region (3′UTR) to regulate ZHX1 protein expression. In addition, the expression of miR-199a-3p was inversely associated with that of ZHX1 in GC cell lines. Overexpression of miR-199a-3p in SGC-7901 cells inhibited ZHX1 expression, while reduction in miR-199a-3p by inhibitors in NCI-N87 cells enhanced ZHX1 expression. Moreover, restoring ZHX1 expression in SGC-7901/miR-199a-3p cells inhibited the cell proliferation induced by miR-199a-3p. Taken together, these findings suggest that miR-199a-3p may function as a novel tumor promoter in GC and its oncogenic activity may involve the direct targeting and inhibition of ZHX1.

Epigenetics of gastric cancer

Epigenetic changes frequently occur in human gastric cancer. Gene promoter region hypermethylation, genomic global hypomethylation, histone modifications, and alterations of noncoding RNAs are major epigenetic changes in gastric cancer. As a key risk factor of gastric cancer, H. pylori infection is an independent predictive indicator of gene methylation. A growing number of epigenetic studies in gastric cancer have provided lots of potential diagnostic and prognostic markers and therapeutic targets.