MicroRNAs: potential biomarkers for cancer diagnosis, prognosis and targets for therapy

Let-7a suppresses glioma cell proliferation and invasion through TGF-β/Smad3 signaling pathway by targeting HMGA2

It has been shown that let-7a was associated with the tumorigenesis of glioma. Our study was designed to infer how let-7a targets high-mobility AT-hook 2 (HMGA2) and suppresses glioma cell proliferation, invasion, and migration. Glioma tissues from 60 glioma patients and 10 normal brain tissues were collected in this study. Real-time quantitative reverse transcription-PCR (qRT-PCR) and in situ hybridization were used to detect the expression levels of let-7a in tissues and cells. The HMGA2 and the proteins related to transforming growth factor-beta (TGF-β)/Smad3 signaling pathway were measured by immunohistochemistry and western blot. Glioma U87 cells were transfected with either let-7a mimics, HMGA2 small interfering RNA (siRNA), let-7a mimics + HMGA2, HMGA2, or scramble. A cell counting kit-8 (CCK-8) assay was used to detect and compare the difference among various transfection groups. Glioma tumor xenograft models on mice were built to evaluate the effects of let-7a and HMGA2 siRNA on glioma tumors in vivo. The expression level of let-7a significantly downregulated in glioma tissues, while the HMGA2 positive expression rate notably increased compared with those in normal brain tissues (all P < 0.05). Moreover, the expression levels of let-7a and HMGA2 were correlated with glioma grades (all P < 0.05). The proliferation of U87 cells transfected with let-7a mimics or HMGA2 siRNA was significantly inhibited in comparison to the blank control group and the apoptosis rates of U87 cells transfected with let-7a mimics or HMGA2 siRNA were significantly higher than those in the blank control group (all P < 0.05). Let-7a or HMGA2 siRNA could remarkably attenuate the invasion and migration ability of glioma cells (all P < 0.05). Apart from that, over-expressed exogenous HMGA2 could reverse the inhibition of glioma cell metastasis and proliferation induced by let-7a. As suggested by immunohistochemistry and western blot, the expression levels of TGF-β1 and p-Smad3 significantly decreased compared with the blank or scramble group (all P < 0.05). Thus, let-7a and HMGA2 siRNA could effectively suppress the growth of tumors in glioma xenograft models. Let-7a may suppress the proliferation and invasion of glioma cells through mediating TGF-β/Smad3 signaling pathway by targeting HMGA2.

The Roles of MicroRNA-122 Overexpression in Inhibiting Proliferation and Invasion and Stimulating Apoptosis of Human Cholangiocarcinoma Cells

Our study investigated whether microRNA-122 (miR-122) played important roles in the proliferation, invasion and apoptosis of human cholangiocarcinoma (CC) cells. QBC939 and RBE cells lines were chosen and divided into five groups: miR-122 mimic group, anti-miR-122 group, negative control (NC) group, mock group and blank group. MiR-122 expression was measured by qRT-PCR. Roles of miR-122 in cell proliferation, apoptosis and invasion were investigated using MTT assay, flow cytometer and Transwell invasion assay, respectively. MiR-122 expression was lower in CC tissues and QBC939 cell than that in normal bile duct tissues, HCCC-9810 and RBE cells. In both QBC939 and RBE cells lines, miR-122 expression was higher in miR-122 mimic group than that in NC group, mock group and blank group; opposite results were found in anti-miR-122 group. Cell proliferation and invasion were remarkably inhibited in miR-122 mimic group after 48 h/72 h transfection, while apoptotic cells numbers were much greater in miR-122 mimic group; the opposite results were obtained from anti-miR-122 group (all P < 0.05). MiR-122 expression was significantly weaker in CC tissues, and miR-122 overexpression might play pivotal roles in inhibiting proliferation, stimulating apoptosis and suppressing invasion of CC cells, suggesting a new target for CC diagnosis and treatment.

Downregulation of microRNA-132 by DNA hypermethylation is associated with cell invasion in colorectal cancer

microRNAs (miRNAs) are small, noncoding RNAs that are involved in many biological processes, and aberrant regulation of miRNAs is always associated with cancer progression and development. Abnormal expression of miRNA-132 (miR-132) has been found in some types of cancer, but the effects and potential mechanisms of miR-132 in colorectal cancer (CRC) have not been explored to date. In this study, quantitative real-time polymerase chain reaction was used to investigate the level of miR-132 in CRC tissues and their paired adjacent normal tissues. Bioinformatics analysis indicated that the mechanism underlying the tumor suppressor role of miR-132 in CRC cells may play a role in tumor suppression by targeting paxillin. Furthermore, methylation-specific polymerase chain reaction was performed to evaluate the methylation status of the miR-132 regulatory region. A DNA methyltransferase inhibitor, 5-aza-2'-deoxycytidine, was used to activate the expression of miR-132 in CRC cells in vitro. Downregulation of miR-132 may occur as a result of hypermethylation and implies a poor prognosis in CRC; therefore, triggering miR-132 reexpression by using DNA methyltransferase inhibitors may be a potential molecular therapeutic target for CRC.

Biomarkers for Bone Tumors: Discovery from Genomics and Proteomics Studies and Their Challenges

Diagnosis of bone tumor currently relies on imaging and biopsy, and hence, the need to find less invasive ways for its accurate detection. More recently, numerous promising deoxyribonucleic acid (DNA) and protein biomarkers with significant prognostic, diagnostic and/or predictive abilities for various types of bone tumors have been identified from genomics and proteomics studies. This article reviewed the putative biomarkers for the more common types of bone tumors (that is, osteosarcoma, Ewing sarcoma, chondrosarcoma [malignant] and giant cell tumor [benign]) that were unveiled from the studies. The benefits and drawbacks of these biomarkers, as well as the technology platforms involved in the research, were also discussed. Challenges faced in the biomarker discovery studies and the problems in their translation from the bench to the clinical settings were also addressed.

MicroRNA-519a promotes proliferation and inhibits apoptosis of hepatocellular carcinoma cells by targeting FOXF2

Recent studies report that microRNA-519a (miR-519a) is a novel oncomir, which facilitates the onset and progression of human cancers. However, the clinical significance of miR-519a and its functional role and underlying mechanisms in hepatocellular carcinoma (HCC) are poorly investigated. In the present study, elevated expression of miR-519a was observed in HCC tissues compared with adjacent non-tumor tissues. The increased level of miR-519a expression was significantly correlated with adverse clinical features of HCC including hepatitis B virus (HBV) infection, large tumor size, cirrhosis and advanced tumor-node-metastasis tumor stage. Furthermore, high expression of miR-519a was prominently associated with a poorer 5-year overall survival and recurrence-free survival of HCC patients. Gain- and loss-of function experiments showed that miR-519a overexpression enhanced proliferation and reduced apoptosis of Huh7 cells. By contrast, miR-519a knockdown inhibited SMMC-7721 cell proliferation and induced apoptosis. Importantly, up-regulation of miR-519a reduced the expression of FOXF2 mRNA and protein in Huh7 cells, while down-regulation of miR-519a resulted in increased expression of FOXF2 in SMMC-7721 cells. An inverse correlation between mRNA levels of miR-519a and FOXF2 was observed in HCC tissues. Thus, Forkhead box F2 (FOXF2) was identified as a downstream target of miR-519a in HCC. Mechanistically, the effects of miR-519a knockdown on SMMC-7721 cells were abrogated by FOXF2 repression. In conclusion, miR-519a is a novel prognostic predictor for HCC patients and it may potentiate proliferation and inhibits apoptosis of HCC cells by targeting FOXF2.

MicroRNA-608 acts as a prognostic marker and inhibits the cell proliferation in hepatocellular carcinoma by macrophage migration inhibitory factor

Human hepatocellular carcinoma (HCC) is one of the most prevalent malignancies in the world. Research on HCC has recently focused on microRNAs (miRNAs) that play crucial roles in cancer development and progression of HCC. In this study, we aimed to analyze the expression and function of a metastasis-associated microRNA-608 (miR-608) in HCC. Samples of human HCC and matched adjacent normal tissues were surgically removed, and miR-608 expression and the pathological characteristics of HCC were investigated. In this study, we found that miR-608 expression was significantly reduced in HCC and its expression levels were highly associated with tumor size, differentiation, clinical stage, and overall and disease-free survival of HCC. Overexpression of miR-608 in HCC cell lines HepG2 and SK-Hep-1 inhibited cell proliferation by G1 arrest. Macrophage migration inhibitory factor (MIF), a potential target gene of miR-608, was inversely correlated with miR-608 expression in HCC tissues and cell lines. Furthermore, we demonstrated that MIF was directly regulated by miR-608 and the restoration of MIF expression reversed the inhibitory effects of miR-608 on HCC cell proliferation. Taken together, these findings collectively demonstrate that miR-608 exerts its anti-cancer function by directly targeting MIF in HCC, indicating a potential novel prognostic biomarker and therapeutic target for HCC.

Deregulation of miR-93 and miR-143 in human esophageal cancer

Esophageal squamous cell carcinoma (ESCC) is the second and third most common malignancy in Iranian males and females, respectively. Treatment of ESCC is largely ineffective due to lack of detection at early stages of the disease. In recent years, miRNA, a small RNA molecule, has drawn much attention to researchers as a potential biomarker for esophageal cancer. miR-93 and miR-143 are two miRNA molecules reported to be frequently deregulated in various cancers, including prostate, stomach, cervix, and etc. The purpose of this study was to investigate the expression levels of these miRNAs and evaluate their diagnostic and therapeutic potential in esophageal squamous cell carcinoma. In this study, total RNA was extracted from 30 tumor tissues and 30 nontumor tissues of esophageal tumor margins, using RNX-plus solution. After validating the quality and quantity of total RNA, cDNAs of interest were synthesized using microRNA-specific cDNA Synthesis Kit. The expression level of miR-93 and miR-143 was evaluated using quantitative real-time PCR with miRNA-specific primers. Finally, the obtained data was analyzed by SPSS ver.20 software and paired t test was performed to observe the significance of difference between groups. The expression level of miR-93 was significantly increased and of miR-143 was significantly decreased in most of the examined tumor tissues, compared to nontumor tissues. Also, our findings did not detect correlation between mir-93 and mir-143 expressions in regard to stage and grade of the samples. These findings suggest that the deregulation of these miRNAs may play an important role in esophageal squamous cell carcinoma. Both miR-93 and miR-143 might be used as potential biomarkers in esophageal squamous cell carcinoma. However, more studies with large population of samples are necessary.

microRNA-10b Is Overexpressed and Critical for Cell Survival and Proliferation in Medulloblastoma

This study demonstrates the effects of miRNA-10b on medulloblastoma proliferation through transcriptional induction of the anti-apoptotic protein BCL2. Using a cancer specific miRNA-array, high expression of miRNA-10b in medulloblastoma cell lines compared to a normal cerebellar control was shown, and this was confirmed with real time PCR (RT-PCR). Two medulloblastoma cell lines (DAOY and UW228) were transiently transfected with control miRNA, miRNA-10b inhibitor or miRNA-10b mimic and subjected to RT-PCR, MTT, apoptosis, clonogenic assay and western blot analysis. Transfection of miRNA-10b inhibitor induced a significant down-regulation of miRNA-10b expression, inhibited proliferation, and induced apoptosis, while miRNA-10b mimic exerted an opposite effect. Inhibition of miRNA-10b abrogated the colony-forming capability of medulloblastoma cells, and markedly down-regulated the expression of BCL2. Down-regulation of BCL2 by antisense oligonucleotides or siRNA also significantly down-regulated miRNA-10b, suggesting that BCL2 is a major mediator of the effects of miRNA-10b. ABT-737 and ABT-199, potent inhibitors of BCL2, downregulated the expression of miRNA-10b and increased apoptosis. Analysis of miRNA-10b levels in 13 primary medulloblastoma samples revealed that the 2 patients with the highest levels of miRNA-10b had multiple recurrences (4.5) and died within 8 years of diagnosis, compared with the 11 patients with low levels of miRNA-10b who had a mean of 1.2 recurrences and nearly 40% long-term survival. The data presented here indicate that miRNA-10b may act as an oncomir in medulloblastoma tumorigenesis, and reveal a previously unreported mechanism with Bcl-2 as a mediator of the effects of miRNA-10b upon medulloblastoma cell survival.

Competing endogenous RNA: A novel posttranscriptional regulatory dimension associated with the progression of cancer

The existence of artificial sponges and antisense oligonucleotides designed to decrease the availability of microRNAs (miRNAs), a family of small non-coding RNAs that target RNA transcripts through miRNA response elements (MREs) involved in gene expression, suggests that miRNAs may also be regulated. The wide range of RNA transcripts harboring MREs, termed competing endogenous RNAs (ceRNAs), includes protein-coding messenger RNAs (mRNAs) and non-coding RNAs, for example long non-coding RNAs, pseudogenes and circular RNAs, which compete for a common pool of miRNAs as natural decoys. These ceRNAs are co-regulated and produce large, complex posttranscriptional regulatory networks, which have been implicated in numerous biological processes. The present review discusses recent discoveries that implicate natural microRNA decoys in the development of cancer.

RBMMMDA: predicting multiple types of disease-microRNA associations

Accumulating evidences have shown that plenty of miRNAs play fundamental and important roles in various biological processes and the deregulations of miRNAs are associated with a broad range of human diseases. However, the mechanisms underlying the dysregulations of miRNAs still have not been fully understood yet. All the previous computational approaches can only predict binary associations between diseases and miRNAs. Predicting multiple types of disease-miRNA associations can further broaden our understanding about the molecular basis of diseases in the level of miRNAs. In this study, the model of Restricted Boltzmann machine for multiple types of miRNA-disease association prediction (RBMMMDA) was developed to predict four different types of miRNA-disease associations. Based on this model, we could obtain not only new miRNA-disease associations, but also corresponding association types. To our knowledge, RBMMMDA is the first model which could computationally infer association types of miRNA-disease pairs. Leave-one-out cross validation was implemented for RBMMMDA and the AUC of 0.8606 demonstrated the reliable and effective performance of RBMMMDA. In the case studies about lung cancer, breast cancer, and global prediction for all the diseases simultaneously, 50, 42, and 45 out of top 100 predicted miRNA-disease association types were confirmed by recent biological experimental literatures, respectively.

MicroRNAs and Growth Factors: An Alliance Propelling Tumor Progression

Tumor progression requires cancer cell proliferation, migration, invasion, and attraction of blood and lymph vessels. These processes are tightly regulated by growth factors and their intracellular signaling pathways, which culminate in transcriptional programs. Hence, oncogenic mutations often capture growth factor signaling, and drugs able to intercept the underlying biochemical routes might retard cancer spread. Along with messenger RNAs, microRNAs play regulatory roles in growth factor signaling and in tumor progression. Because growth factors regulate abundance of certain microRNAs and the latter modulate the abundance of proteins necessary for growth factor signaling, the two classes of molecules form a dense web of interactions, which are dominated by a few recurring modules. We review specific examples of the alliance formed by growth factors and microRNAs and refer primarily to the epidermal growth factor (EGF) pathway. Clinical applications of the crosstalk between microRNAs and growth factors are described, including relevance to cancer therapy and to emergence of resistance to specific drugs.

MicroRNA-638 inhibits cell proliferation by targeting phospholipase D1 in human gastric carcinoma

MicroRNAs (miRNAs) are a type of small non-coding RNAs that are often play important roles in carcinogenesis, but the carcinogenic mechanism of miRNAs is still unclear. This study will investigate the function and the mechanism of miR-638 in carcinoma (GC). The expression of miR-638 in GC and the DNA copy number of miR-638 were detected by real-time PCR. The effect of miR-638 on cell proliferation was measured by counting kit-8 assay. Different assays, including bioinformatics algorithms (TargetScan and miRanda), luciferase report assay and Western blotting, were used to identify the target gene of miR-638 in GC. The expression of miR-638 target gene in clinical CRC tissues was also validated by immunohistochemical assay. From this research, we found that miR-638 was downregulated in GC tissues compared with corresponding noncancerous tissues (NCTs), and the DNA copy number of miR-638 was lower in GC than NCTs, which may induce the corresponding downregulation of miR-638 in GC. Ectopic expression of miR-638 inhibited GC cell growth in vitro. Subsequently, we identified that PLD1 is the target gene of miR-638 in GC, and silencing PLD1 expression phenocopied the inhibitory effect of miR-638 on GC cell proliferation. Furthermore, we observed that PLD1 was overexpressed in GC tissues, and high expression of PLD1 in GC predicted poor overall survival. In summary, we revealed that miR-638 functions as a tumor suppressor in GC through inhibiting PLD1.

MiR-17-92 cluster promotes hepatocarcinogenesis

MiR-17-92 cluster is an oncogenic miRNA cluster that is implicated in several cancers, although its role in hepatocarcinogenesis has not been clearly defined. In this study, we show that the miR-17-92 cluster is highly expressed in human hepatocellular carcinoma (HCC) tissues compared to the non-tumorous liver tissues by RT-PCR and in situ hybridization analyses. Increased miR-17-92 cluster expression in HCC tissues was further confirmed by analysis of the RNA-sequencing data of 319 patients available from the Cancer Genome Atlas (TCGA) Data Portal (https://tcga-data.nci.nih.gov/tcga/). To create an animal model that resembles enhanced miR-17-92 in the liver, we developed liver-specific miR-17-92 transgenic mice and the animals were treated with the hepatic carcinogen, diethylnitrosamine (DEN). We observed that the liver-specific miR-17-92 transgenic mice showed significantly increased hepatocellular cancer development compared to the matched wild-type control mice. Forced overexpression of the miR-17-92 cluster in cultured human hepatocellular cancer cells enhanced tumor cell proliferation, colony formation and invasiveness in vitro, whereas inhibition of the miR-17-92 cluster reduced tumor cell growth. By analyzing the miRNA and mRNA sequencing data from the 312 hepatocellular cancer patients available from the TCGA database, we observed that the expression levels of the miR-17-92 cluster members and host gene in the tumor tissues are negatively correlated with several target genes, including CREBL2, PRRG1, NTN4. Our findings demonstrate an important role of the miR-17-92 cluster in hepatocarcinogenesis and suggest the possibility of targeting this pivotal miRNA cluster for potential therapy.

Emerging Roles of MicroRNAs in EGFR-Targeted Therapies for Lung Cancer

Lung cancer is a leading cause of cancer mortality worldwide. Several molecular pathways underlying mechanisms of this disease have been partly elucidated, among which the epidermal growth factor receptor (EGFR) pathway is one of the well-known signaling cascades that plays a critical role in tumorigenesis. Dysregulation of the EGFR signaling is frequently found in lung cancer. The strategies to effectively inhibit EGFR signaling pathway have been mounted for developing anticancer therapeutic agents. However, most anti-EGFR-targeted agents fail to repress cancer progression because of developing drug-resistance. Therefore, studies of the mechanisms underpinning the resistance toward anti-EGFR agents may provide important findings for lung cancer treatment using anti-EGFR therapies. Recently, increasing numbers of miRNAs are correlated with the drug resistance of lung cancer cells to anti-EGFR agents, indicating that miRNAs may serve as novel targets and/or promising predictive biomarkers for anti-EGFR therapy. In this paper, we summarize the emerging role of miRNAs as regulators to modulate the EGFR signaling and the resistance of lung cancer cells to anti-EGFR therapy. We also highlight the evidence supporting the use of miRNAs as biomarkers for response to anti-EGFR agents and as novel therapeutic targets to circumvent the resistance of lung cancer cells to EGFR inhibitors.

Association of miR-193b down-regulation and miR-196a up-regulation with clinicopathological features and prognosis in gastric cancer

Dysregulated expression of microRNAs (miRNAs) has been shown to be closely associated with tumor development, progression, and carcinogenesis. However, their clinical implications for gastric cancer remain elusive. To investigate the hypothesis that genome-wide alternations of miRNAs differentiate gastric cancer tissues from those matched adjacent non-tumor tissues (ANTTs), miRNA arrays were employed to examine miRNA expression profiles for the 5-pair discovery stage, and the quantitative real-time polymerase chain reaction (qRT- PCR) was applied to validate candidate miRNAs for 48-pair validation stage. Furthermore, the relationship between altered miRNA and clinicopathological features and prognosis of gastric cancer was explored. Among a total of 1,146 miRNAs analyzed, 16 miRNAs were found to be significantly different expressed in tissues from gastric cancer compared to ANTTs (p<0.05). qRT-PCR further confirmed the variation in expression of miR-193b and miR-196a in the validation stage. Down-expression of miR-193b was significantly correlated with Lauren type, differentiation, UICC stage, invasion, and metastasis of gastric cancer (p<0.05), while over-expression of miR-196a was significantly associated with poor differentiation (p=0.022). Moreover, binary logistic regression analysis demonstrated that the UICC stage was a significant risk factor for down-expression of miR-193b (adjusted OR=8.69; 95%CI=1.06-56.91; p=0.043). Additionally, Kaplan-Meier survival curves indicated that patients with a high fold-change of down-regulated miR-193b had a significantly shorter survival time (n=19; median survival=29 months) compared to patients with a low fold-change of down-regulated miR-193b (n=29; median survival=54 months) (p=0.001). Overall survival time of patients with a low fold-change of up-regulated miR- 196a (n=27; median survival=52 months) was significantly longer than that of patients with a high fold-change of up-regulated miR-196a (n=21; median survival=46 months) (p=0.003). Hence, miR-193b and miR-196a may be applied as novel and promising prognostic markers in gastric cancer.

miR-122 negatively correlates with liver fibrosis as detected by histology and FibroScan

AIM: To investigate whether expression of selected miRNAs obtained from fibrotic liver biopsies correlate with fibrosis stage.

METHODS: Altogether, 52 patients were enrolled in the study representing various etiologic backgrounds of fibrosis: 24 cases with chronic hepatitis infections (types B, C), 19 with autoimmune liver diseases (autoimmune hepatitis, primary biliary cirrhosis, primary sclerosing cholangitis, overlapping syndrome cases), and 9 of mixed etiology (alcoholic and nonalcoholic steatosis, cryptogenic cases). Severity of fibrosis was determined by both histologic staging using the METAVIR scoring system and noninvasive transient elastography. Following RNA isolation, expression levels of miR-21, miR-122, miR-214, miR-221, miR-222, and miR-224 were determined using TaqMan MicroRNA Assays applying miR-140 as the reference. Selection of miRNAs was based on their characteristic up- or downregulation observed in hepatocellular carcinoma. Relative expression of miRNAs was correlated with fibrosis stage and liver stiffness (LS) value measured by transient elastography, as well as with serum alanine aminotransferase (ALT) level.

RESULTS: The expression of individual miRNAs showed deregulated patterns in stages F1-F4 as compared with stage F0, but only the reduced level of miR-122 in stage F4 was statistically significant (P < 0.04). When analyzing miRNA expression in relation to fibrosis, levels of miR-122 and miR-221 showed negative correlations with fibrosis stage, and miR-122 was found to correlate negatively and miR-224 positively with LS values (all P < 0.05). ALT levels displayed a positive correlation with miR-21 (P < 0.04). Negative correlations were observed in the fibrosis samples of mixed etiology between miR-122 and fibrosis stage and LS values (P < 0.05), and in the samples of chronic viral hepatitis, between miR-221 and fibrosis stage (P < 0.01), whereas miR-21 showed positive correlation with ALT values in the samples of autoimmune liver diseases (P < 0.03). The results also revealed a strong correlation between fibrosis stage and LS values (P < 0.01) when etiology of fibrosis was not taken into account.

CONCLUSION: Reduced expression of miR-122 in advanced fibrosis and its correlation with fibrosis stage and LS values seem to be characteristic of hepatic fibrosis of various etiologies.

Targeting microRNAs to withstand cancer metastasis

MicroRNAs are endogenous, regulatory, noncoding small RNAs shown to play a key role in controlling gene expression, mainly at the posttranscriptional level. Several lines of evidence highlighted the importance of selected microRNAs as essential actors of cancer initiation events, tumor progression towards malignancy, and ultimately metastasis. By acting as either prometastatic or antimetastatic factors, microRNAs may represent novel targets or tools to withstand cancer progression. This chapter summarizes the available strategies to manipulate the expression of metastasis-related microRNAs, either by mimicking or inhibiting them, in cell systems and in vivo models. In addition, we provide a broad overview of conceptual and technological issues that need to be addressed before microRNAs might be exploited in the clinical setting for the prevention and treatment of the metastatic disease.

Impact of Nutrition on Non-Coding RNA Epigenetics in Breast and Gynecological Cancer

Cancer is the second leading cause of death in females. According to the American Cancer Society, there are 327,660 new cases in breast and gynecological cancers estimated in 2014, placing emphasis on the need for cancer prevention and new cancer treatment strategies. One important approach to cancer prevention involves phytochemicals, biologically active compounds derived from plants. A variety of studies on the impact of dietary compounds found in cruciferous vegetables, green tea, and spices like curry and black pepper have revealed epigenetic changes in female cancers. Thus, an important emerging topic comprises epigenetic changes due to the modulation of non-coding RNA levels. Since it has been shown that non-coding RNAs such as microRNAs and long non-coding RNAs are aberrantly expressed in cancer, and furthermore are linked to distinct cancer phenotypes, understanding the effects of dietary compounds and supplements on the epigenetic modulator non-coding RNA is of great interest. This article reviews the current findings on nutrition-induced changes in breast and gynecological cancers at the non-coding RNA level.

MicroRNA and pediatric tumors: Future perspectives

A better understanding of pediatric tumor biology is needed to allow the development of less toxic and more efficient therapies, as well as to provide novel reliable biomarkers for diagnosis and risk stratification. The emerging role of microRNAs in controlling key pathways implicated in tumorigenesis makes their use in diagnostics a powerful novel tool for the early detection, risk assessment and prognosis, as well as for the development of innovative anticancer therapies. This perspective would be more urgent for the clinical management of pediatric cancer. In this review, we focus on the involvement of microRNAs in the biology of the main childhood tumors, describe their clinical significance and discuss their potential use as novel therapeutic tools and targets.

MicroRNA-93 promotes cell growth and invasion in nasopharyngeal carcinoma by targeting disabled homolog-2

Dysregulation of microRNAs (miRNAs) has been demonstrated to contribute to malignant progression in nasopharyngeal carcinoma (NPC). We previously reported that miR-93 was significantly upregulated in NPC based on a microarray analysis. However, the potential role and mechanism of action of miR-93 in the initiation and progression of NPC remain largely unknown. Quantitative RT-PCR demonstrated that miR-93 was significantly upregulated in NPC cell lines and clinical specimens. The MTT assay, colony formation assay, anchorage-independent growth, and Transwell migration and invasion assays showed that depletion of miR-93 inhibited NPC cell growth, invasion and migration in vitro and suppressed tumor growth in vivo. Disabled homolog-2 (Dab2) was verified as a miR-93 target gene using Luciferase reporter assays, quantitative RT-PCR and Western blotting and was involved in miR-93-regulated NPC cell growth, invasion and migration. These results indicated that miR-93 plays an important role in the initiation and progression of NPC by targeting Dab2 and the miR-93/Dab2 pathway may contribute to the development of novel therapeutic strategies for NPC in the future.

MiR-506 is down-regulated in clear cell renal cell carcinoma and inhibits cell growth and metastasis via targeting FLOT1

Background

Some microRNAs (miRNAs) are abnormally expressed in cancer and contribute to tumorigenesis. In the present study, we investigated the role of miR-506 in clear cell renal cell carcinoma (ccRCC).

Methods

miR-506 expression was detected in renal cancer cell lines 786-O, ACHN, Caki-1, and Caki-2 and ccRCC specimens by quantitative real-time-PCR. We assessed the association of miR-506 expression with pathology and prognosis in ccRCC patients. We over-expressed and knocked-down miR-506 expression in two renal cancer cell lines, 786-O and ACHN, and assessed the impact on cell proliferation, migration and invasion. A luciferase reporter assay was conducted to confirm the target gene of miR-506 in renal cancer cell lines.

Results

miR-506 was significantly down-regulated in renal cancer cell lines and ccRCC specimens. Low miR-506 expression in ccRCC specimens was associated with an advanced clinical stage and poor prognosis. miR-506 expression was an independent prognostic marker of overall ccRCC patient survival in a multivariate analysis. Over-expression of miR-506 in renal cancer cells decreased cell growth and metastasis, In contrast, down-regulation of miR-506 expression promoted renal cancer cell growth and metastasis. FLOT1, a potential target gene of miR-506, was inversely correlated with miR-506 expression in ccRCC tissues. Consistent with the effect of miR-506, knockdown of FLOT1 by siRNA inhibited cell malignant behaviors. Rescue of FLOT1 expression partially restored the effects of miR-506.

Conclusions

miR-506 exerts its anti-cancer function by directly targeting FLOT1 in renal cancer, indicating a potential novel therapeutic role in renal cancer treatment.

A functional variant at miR-520a binding site in PIK3CA alters susceptibility to colorectal cancer in a Chinese Han population

An increasing body of evidence has indicated that polymorphisms in the miRNA binding site of target gene can alter the ability of miRNAs to bind their target genes and modulate the risk of cancer. We aimed to investigate the association between a miR-520a binding site polymorphism rs141178472 in the PIK3CA 3′-UTR and the risk of colorectal cancer (CRC) in a Chinese Han population. The polymorphism rs141178472 was analyzed in a case-control study, including 386 CRC patients and 394 age- and sex-matched controls; the relationship between the polymorphism and the risk of colorectal cancer was examined. Individuals carrying the rs141178472 CC genotype or C allele had an increased risk of developing CRC (CC versus TT, OR (95% CI): 1.716 (1.084–2.716), P = 0.022; C versus T, OR (95% CI): 1.258 (1.021–1.551), P = 0.033). Furthermore, the expression of PIK3CA was detected in the peripheral blood mononucleated cell of CRC patients, suggesting that mRNA levels of PIK3CA might be associated with SNP rs141178472. These findings provide evidence that a miR-520a binding site polymorphism rs141178472 in the PIK3CA 3′-UTR may play a role in the etiology of CRC.

Prognostic significance of miR-34a and its target proteins of FOXP1, p53, and BCL2 in gastric MALT lymphoma and DLBCL

BACKGROUND

Mucosa-associated lymphoid tissue (MALT) lymphoma and diffuse large B-cell lymphoma (DLBCL), which are the two most common types of gastric lymphomas, have different clinicopathological features and molecular characteristics with distinct clinical outcomes. Tumor suppressor miR-34a connects the p53 network with forkhead box protein 1 (FOXP1) and BCL2. Here, we investigated the prognostic value of these molecules in gastric MALT lymphoma and DLBCL for use in routine clinical practice.

METHODS

Relative miR-34a expression was detected by quantitative reverse transcriptase-polymerase chain reaction in 20 cases of MALT lymphomas and 20 cases of DLBCLs. Tissue microarray, in situ hybridization, and immunohistochemistry analysis were used to examine the expression of miR-34a and its regulated genes, FOXP1, p53, and BCL2 proteins, in 64 patients with gastric MALT lymphoma and in 58 patients with DLBCL. Helicobacter pylori infection, overall survival (OS), and progression-free survival (PFS) were documented.

RESULTS

The expression level of miR-34a was markedly decreased in MALT lymphomas and DLBCLs compared to normal gastric tissues and peripheral blood mononuclear cells. miR-34a was present in the cytoplasm and nucleus of lymphocytes. Its expression was significantly downregulated in MALT and DLBCL lymphoma tissues, as compared with normal lymphocytes. The expression level of miR-34a in DLBCL was lower than in MALT lymphoma. FOXP1 was found to be positive in 48%, p53 in 20%, and BCL2 in 68% of MALT lymphoma cases. The corresponding positive rates of these markers in DLBCL were 64, 57, and 52%, respectively. High expression of FOXP1, p53, and BCL2 was seen in stage III and IV of both types of lymphomas. FOXP1, p53, and BCL2 positivity was associated with poor OS with both lymphoma types but OS with DLBCL was significantly lower than with MALT lymphoma.

CONCLUSIONS

Decreased miR-34a expression and increased FOXP1, p53, and BCL2 coexpression to predict a poor OS for MALT lymphoma and DLBCL patients could become very important prognostic markers in daily clinical work. Further investigation of these changes may be of prognostic significance in clinical practice.

Novel candidate key drivers in the integrative network of genes, microRNAs, methylations, and copy number variations in squamous cell lung carcinoma

The mechanisms of lung cancer are highly complex. Not only mRNA gene expression but also microRNAs, DNA methylation, and copy number variation (CNV) play roles in tumorigenesis. It is difficult to incorporate so much information into a single model that can comprehensively reflect all these lung cancer mechanisms. In this study, we analyzed the 129 TCGA (The Cancer Genome Atlas) squamous cell lung carcinoma samples with gene expression, microRNA expression, DNA methylation, and CNV data. First, we used variance inflation factor (VIF) regression to build the whole genome integrative network. Then, we isolated the lung cancer subnetwork by identifying the known lung cancer genes and their direct regulators. This subnetwork was refined by the Bayesian method, and the directed regulations among mRNA genes, microRNAs, methylations, and CNVs were obtained. The novel candidate key drivers in this refined subnetwork, such as the methylation of ARHGDIB and HOXD3, microRNA let-7a and miR-31, and the CNV of AGAP2, were identified and analyzed. On three large public available lung cancer datasets, the key drivers ARHGDIB and HOXD3 demonstrated significant associations with the overall survival of lung cancer patients. Our results provide new insights into lung cancer mechanisms.

Screening for characteristic microRNAs between pre-invasive and invasive stages of cervical cancer

The aim of the present study was to investigate the characteristic microRNAs (miRNAs) expressed during the pre-invasive and invasive stages of cervical cancer. A gene expression profile (GSE7803) containing 21 invasive squamous cell cervical carcinoma samples, 10 normal squamous cervical epithelium samples and seven high-grade squamous intraepithelial cervical lesion samples, was obtained from the Gene Expression Omnibus. Differentially expressed genes (DEGs) were identified using significance analysis of microarray software, and a Gene Ontology (GO) enrichment analysis was conducted using the Database for Annotation, Visualization and Integrated Discovery. The miRNAs that interacted with the identified DEGs were selected, based on the TarBase v5.0 database. Regulatory networks were constructed from these selected miRNAs along with their corresponding target genes among the DEGs. The regulatory networks were visualized using Cytoscape. A total of 1,160 and 756 DEGs were identified in the pre-invasive and invasive stages of cervical cancer, respectively. The results of the GO enrichment demonstrated that the DEGs were predominantly involved in the immune response and the cell cycle, in the pre-invasive and invasive stages, respectively. Furthermore, a total of 18 and 26 characteristic miRNAs were screened in the pre-invasive and invasive stages, respectively. These miRNAs may be potential biomarkers and targets for the diagnosis and treatment of the different stages of cervical cancer.

miR-20a promotes prostate cancer invasion and migration through targeting ABL2

The aberrant expression of microRNAs (miRNAs) has been found in various types of cancer. The present study found miR-20a was significantly up-regulated in prostate cancer compared with normal prostate tissues. Patients with a higher miR-20a expression had a Gleason score of 7-10 and shorter survival time. The transwell and wound healing assays revealed that blocking expression of miR-20a by miR-20a ASO suppresses the invasion and migration of PC-3 and DU145 cells in vitro and also inhibits tumor growth in vivo. Furthermore, we identified miR-20a directly targets the ABL family non-receptor tyrosine kinases ABL2 and negatively regulates the phosphorylation of its downstream gene p190RhoGAP. Knockdown of ABL2 promoted cell invasion and migration and we identified miR-20a-induced cell invasion and migration can be rescued by ABL2. In conclusion, our findings show that miR-20a significantly contributes to the progression of prostate cancer by targeting ABL2.

A highly specific and sensitive electroanalytical strategy for microRNAs based on amplified silver deposition by the synergic TiO2 photocatalysis and guanine photoreduction using charge-neutral probes

TiO₂ photocatalysis and guanine photoreduction were synergically combined for amplifying silver deposition toward sensitive electroanalysis of microRNAs using charge-neutral probes.

MicroRNA-576-3p inhibits proliferation in bladder cancer cells by targeting cyclin D1

MicroRNAs (miRNAs) are small, endogenous RNAs that play important gene-regulatory roles by binding to the imperfectly complementary sequences at the 3'-UTR of mRNAs and directing their gene expression. Here, we first discovered that miR-576-3p was down-regulated in human bladder cancer cell lines compared with the non-malignant cell line. To better characterize the role of miR-576-3p in bladder cancer cells, we over-expressed or down-regulated miR-576-3p in bladder cancer cells by transfecting with chemically synthesized mimic or inhibitor. The overexpression of miR-576-3p remarkably inhibited cell proliferation via G1-phase arrest, and decreased both mRNA and protein levels of cyclin D1 which played a key role in G1/S phase transition. The knock-down of miR-576-3p significantly promoted the proliferation of bladder cancer cells by accelerating the progression of cell cycle and increased the expression of cyclin D1. Moreover, the dual-luciferase reporter assays indicated that miR-576-3p could directly target cyclin D1 through binding its 3'-UTR. All the results demonstrated that miR-576-3p might be a novel suppressor of bladder cancer cell proliferation through targeting cyclin D1.

Circulating biomarkers in renal cell carcinoma: the link between microRNAs and extracellular vesicles, where are we now?

Renal cell carcinoma (RCC) is a lethal urological cancer, with incidence and mortality rates increasing by 2-3% per decade. The lack of standard screening tests contributes to the fact that one-third of patients are diagnosed with locally invasive or metastatic disease. Moreover, 20-40% of RCC patients submitted to surgical nephrectomy will develop metastasis. MicroRNAs (miRNAs) are small non-coding RNAs responsible for gene regulation at a post-transcriptional level. It is accepted that they are deregulated in cancer and can influence tumor development. Thus, miRNAs are promising RCC biomarkers, since they can be detected using non-invasive methods. They are highly stable and easier to quantify in circulating biofluids. The elevated miRNA stability in circulating samples may be the consequence of their capacity to circulate inside of extracellular microvesicles (EMVs), for example, the exosomes. The EMVs are bilayered membrane vesicles secreted by all cell types. They can be released in the interstitial space or into circulating biofluids, which allows the travelling, binding and entrance of these vesicles in receptor cells. This type of cell communication can shuttle bioactive molecules between cells, allowing the horizontal transference of genetic material. In this review, we focus on circulating miRNAs (miR-210, miR-1233, miR-221, miR-15a, miR-451, miR-508, miR-378) in the biofluids of RCC patients and attempt to establish the diagnostic and prognostic accuracy, their synergic effects, and the pathways involved in RCC biology.

Comprehensive expression analysis of miRNA in breast cancer at the miRNA and isomiR levels

Breast cancer (BC) is the main factor that leads cause of cancer death in women worldwide. A class of small non-coding RNAs, microRNAs (miRNAs), has been widely studied in human cancers as crucial regulatory molecule. Recent studies indicate that a series of isomiRs can be yielded from a miRNA locus, and these physiological miRNA isoforms have versatile roles in miRNA biogenesis. Herein, we performed a comprehensive analysis of miRNAs at the miRNA and isomiR levels in BC using next-generation sequencing data from The Cancer Genome Atlas (TCGA). Abnormally expressed miRNA (miR-21, miR-221, miR-155, miR-30e and miR-25) and isomiR profiles could be obtained at the miRNA and isomiR levels, and similar biological roles could be detected. IsomiR expression profiles should be further concerned, and especially isomiRs are actual regulatory molecules in the miRNA-mRNA regulatory networks. The study provides a comprehensive expression analysis at the miRNA and isomiR levels in BC, which indicates biological roles of isomiRs.

Adenoid cystic carcinoma of breast: Recent advances

Adenoid cystic carcinoma (ACC) of the breast is a rare special subtype of breast cancer characterized by the presence of a dual cell population of luminal and basaloid cells arranged in specific growth patterns. Most breast cancers with triple-negative, basal-like breast features (i.e., tumors that are devoid of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 expression, and express basal cell markers) are generally high-grade tumors with an aggressive clinical course. Conversely, while ACCs also display a triple-negative, basal-like phenotype, they are usually low-grade and exhibit an indolent clinical behavior. Many discoveries regarding the molecular and genetic features of the ACC, including a specific chromosomal translocation t(6;9) that results in a MYB-NFIB fusion gene, have been made in recent years. This comprehensive review provides our experience with the ACC of the breast, as well as an overview of clinical, histopathological, and molecular genetic features.

miR-218 expression in osteosarcoma tissues and its effect on cell growth in osteosarcoma cells

OBJECTIVE

To investigate the expression of miR-218 and its clinical significance in osteosarcoma tissues and explore its effect on proliferation and apoptosis in osteosarcoma cells.

METHODS

miR-218 expression was detected in 76 samples of surgically resected osteosarcoma and matched normal tumor-adjacent tissues using quantitative reverse transcription polymerase chain reaction (qRT-PCR). MiR-218 was over-expressed by exogenous miR-218 plasmids in Saos-2 cells, and then BrdU cell proliferation assay and flow cytometry were used to determine cell proliferation and apoptosis.

RESULTS

The expression of miR-218 in osteosarcoma tissues was significantly lower than those in normal tumor-adjacent tissues (t=8.735, P<0.001). MiR-218 expression in tumor tissues was significantly correlated with tumor size (χ(2)=5.380, P=0.020), clinical stage (χ(2)=6.692, P=0.010) and distant metastasis (χ(2)=4.180, P=0.041). MiR-218 was obviously over-expressed by exogenous miR-218 plasmids (t=19.42, P<0.001), and miR-218 overexpression significantly reduced cell proliferation (t=9.045, P<0.001) and induced apoptosis (t=12.38, P<0.001) in Saos-2 cells.

CONCLUSIONS

The low-expression of miR-218 is correlated with the poor clinicopathological features in osteosarcoma. Moreover, miR-218 overexpression reduces cancer cell proliferation and induces apoptosis in Saos-2 cells, suggesting that miR-218 may play a key role in the progression of human osteosarcoma.

Polymorphisms of microRNA-binding sites in integrin genes are associated with oral squamous cell carcinoma susceptibility and progression

Integrins, which act as an important role in the connection between cells and extra-cellular environments, are important cell surface receptors. Integrins have been demonstrated to play critical roles in many aspects of the progression of oral squamous cell carcinoma (OSCC). The aim of this study was to investigate the association between single nucleotide polymorphisms (SNPs) in microRNA-binding sites of integrin genes and the susceptibility and progression of OSCC in Chinese Han Population. We recruited 167 OSCC patients and 200 cancer-free controls from three independent medical centers. Genotyping was completed successfully for the five selected integrin SNPs: rs1062484 (integrin α3), rs11902171 (integrin αv), rs17468 (integrin β1), rs3809865 (integrin β3), and rs2675 (integrin β5). The results demonstrated that the A allele of rs3809865 T/A (a T-to-A nucleotide change), a functional polymorphism in the 3'UTR of integrin β3 gene, was associated with OSCC risk (p < 0.05). In addition, the association analysis between this SNP and integrin β3 mRNA expression level in the patients' peripheral blood mononuclear cells indicated that OSCC patients carrying the A allele would have a lower integrin β3 expression level (p = 0.047). Meanwhile, survival analysis showed that the C allele of rs2675 A/C (nucleotide change from A to C), another 3'UTR polymorphism in integrin β5 gene, was related with progression of OSCC. Overall, our results suggest that rs3809865 and rs2675 may contribute to OSCC risk and progression in Chinese Han Population. These two SNPs may be used as potential diagnostic and prognostic biomarkers for OSCC in future.

miR-1228 promotes the proliferation and metastasis of hepatoma cells through a p53 forward feedback loop

Background:

The effective mechanisms of microRNAs (miRNAs) functions as oncogenes or tumour suppressors in human hepatocellular carcinoma (HCC) are still obscure. Here, we investigated the function and expression of miR-1228 in HCC.

Methods:

The role of miR-1228 in HCC was determined by colony formation, transwell, and nude mice xenograft experiments. miR-1228 target gene were identified by EGFP reporter assays, real-time PCR, and western blot analysis. Dual-luciferase reporter assay and real-time PCR analysis are used to examine the regulation of p53.

Results:

miR-1228 promoted proliferation and metastasis, and facilitated the transition of cell cycle in hepatoma cells. miR-1228 downregulated p53 expression by binding to its 3′UTR. The ectopic expression of p53 abrogated the phenotypes induced by miR-1228. An inverse correlation existed between miR-1228 and p53 expression in hepatoma tissues compared with the adjacent tissues and three hepatoma cell lines. Moreover, we found that p53 suppressed the expression and promoter activity of miR-1228.

Conclusions:

miR-1228 functions as an oncogene by promoting cell cycle progression and cell mobility and negatively regulates the expression of p53. p53 downregulation in turn leads to an increase in miR-1228 expression, thereby forming a positive feedback loop that contributes to cancerogenesis in HCC.

Neural network cascade optimizes microRNA biomarker selection for nasopharyngeal cancer prognosis

MicroRNAs (miRNAs) have been shown to be promising biomarkers in predicting cancer prognosis. However, inappropriate or poorly optimized processing and modeling of miRNA expression data can negatively affect prediction performance. Here, we propose a holistic solution for miRNA biomarker selection and prediction model building. This work introduces the use of a neural network cascade, a cascaded constitution of small artificial neural network units, for evaluating miRNA expression and patient outcome. A miRNA microarray dataset of nasopharyngeal carcinoma was retrieved from Gene Expression Omnibus to illustrate the methodology. Results indicated a nonlinear relationship between miRNA expression and patient death risk, implying that direct comparison of expression values is inappropriate. However, this method performs transformation of miRNA expression values into a miRNA score, which linearly measures death risk. Spearman correlation was calculated between miRNA scores and survival status for each miRNA. Finally, a nine-miRNA signature was optimized to predict death risk after nasopharyngeal carcinoma by establishing a neural network cascade consisting of 13 artificial neural network units. Area under the ROC was 0.951 for the internal validation set and had a prediction accuracy of 83% for the external validation set. In particular, the established neural network cascade was found to have strong immunity against noise interference that disturbs miRNA expression values. This study provides an efficient and easy-to-use method that aims to maximize clinical application of miRNAs in prognostic risk assessment of patients with cancer.

miR-143 and miR-145 synergistically regulate ERBB3 to suppress cell proliferation and invasion in breast cancer

Introduction

ERBB3, one of the four members of the ErbB family of receptor tyrosine kinases, plays an important role in breast cancer etiology and progression. In the present study, we aimed to identify novel miRNAs that can potentially target ERBB3 and their biological functions.

Method

The expression levels of miR-143/145 and target mRNA were examined by relative quantification RT-PCR, and the expression levels of target protein were detected by Western blot. We used bioinformatic analyses to search for miRNAs that can potentially target ERBB3. Luciferase reporter plasmids were constructed to confirm direct targeting. Furthermore, the biological consequences of the targeting of ERBB3 by miR-143/145 were examined by cell proliferation and invasion assays in vitro and by the mouse xenograft tumor model in vivo.

Results

We identified an inverse correlation between miR-143/145 levels and ERBB3 protein levels, but not between miR-143/145 levels and ERBB3 mRNA levels, in breast cancer tissue samples. We identified specific targeting sites for miR-143 and miR-145 (miR-143/145) in the 3’-untranslated region (3’-UTR) of the ERBB3 gene and regulate ERBB3 expression. We demonstrated that the repression of ERBB3 by miR-143/145 suppressed the proliferation and invasion of breast cancer cells, and that miR-143/145 showed an anti-tumor effect by negatively regulating ERBB3 in the xenograft mouse model. Interestingly, miR-143 and miR-145 showed a cooperative repression of ERBB3 expression and cell proliferation and invasion in breast cancer cells, such that the effects of the two miRNAs were greater than with either miR-143 or miR-145 alone.

Conclusion

Taken together, our findings provide the first clues regarding the role of the miR-143/145 cluster as a tumor suppressor in breast cancer through the inhibition of ERBB3 translation. These results also support the idea that different miRNAs in a cluster can synergistically repress a given target mRNA.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-4598-13-220) contains supplementary material, which is available to authorized users.

The characteristics of the porcine (Sus scrofa) liver miRNAome with the use of next generation sequencing

MicroRNAs (miRNAs) are a class of small, noncoding RNAs, which play a vital role in the regulation of gene expression by binding to the 3' untranslated region (3'UTR) of a target mRNA. Despite a significant improvement in the identification of miRNAs in a variety of species, the coverage of the porcine miRNAome is still scarce. To identify porcine miRNAs potentially regulating processes taking place in the liver, we applied next generation sequencing. As a result, we detected 206 distinct miRNAs, of which 68 represented potential novel miRNAs. Among these new miRNAs, there were miRNAs deriving from the opposite arm of a hairpin precursor of already known miRNAs. Moreover, we observed 3' and 5' length and sequence variants, probably constituting so called isomiRs, as well as differentially mapped precursor loci, alternative precursor sequences and clustering of miRNA encoding genes. On the basis of expression levels, reflected by the number of sequence reads, we identified the most abundant miRNAs followed by gene target prediction and pathway analysis. The enriched pathways were connected with cellular and metabolic processes, growth factors as well as enzymatic activity. The obtained results are the first ones to concern the porcine liver miRNAome. Consequently, they will increase the number of known porcine miRNAs and facilitate further research on gene regulation mechanisms as well as biological processes associated with the liver functioning in pigs.

Prognostic role of microRNA-21 in gastric cancer: a meta-analysis

Background

Mounting evidence shows that microRNAs may be useful as prognostic biomarkers of gastric cancer. The aim of this meta-analysis was to summarize the predictive role of miR-21 for survival in patients with gastric cancer and to verify the association between expression of miR-21 and clinical characteristics.

Material/Methods

All the eligible studies were searched by PubMed and EMBASE and clinical characteristics and survival results were extracted. Then a meta-analysis was carried out to clarify the prognostic role of the miR-21 expression in different subgroups.

Results

We included 8 studies dealing with gastric cancer in this meta-analysis. For overall survival, the pooled hazard ratio of higher miR-21 expression in tumor tissue was 2.00 (95% CI: 1.39–2.88, P<0.01), which could significantly predict poorer survival in gastric cancer patients. Importantly, subgroup analysis suggested that higher expression of miR-21 correlated with tumor differentiation 0.42 (95% CI: 0.25–0.70 p<0.01), lymph node metastasis 6.39(95% CI: 3.11–13.14, P<0.01), and TNM stage 0.38 (95% CI: 0.21–0.67, P<0.01).

Conclusions

This meta-analysis indicates that miR-21 detection has a prognostic value in patients with gastric cancer. In addition, overexpression of miR-21 is associated with worse tumor differentiation, lymph node metastasis, and TNM stage.

microRNA levels in paraffin-embedded indolent B-cell non-Hodgkin lymphoma tissues from patients chronically infected with hepatitis B or C virus

Background

Epidemiological evidence links Hepatitis B Virus (HBV) and Hepatitis C Virus (HCV) to B-cell non-Hodgkin lymphoma (B-NHL). These B-NHLs, particularly those associated with HCV, may represent a distinct sub-group with peculiar molecular features, including peculiar expression of microRNAs (miRs).

The aim of the present study was to search for miRs whose level in indolent B-NHL tissues could be associated with HBV or HCV infection.

Methods

Fourteen formalin fixed paraffin embedded (FFPE) tissues from HBV+, HCV+ and HBV-/HCV- indolent B-NHL patients were analyzed for levels of 34 selected miRs by quantitative Real-Time PCR. Reactive lymph nodes (RLNs) from HBV-/HCV- patients were included as non-tumor control. Statistical analysis of output data included Pearson and Spearman correlation and Mann-Whitney test and were carried out by the STATA software.

Results

MiR-92a was decreased exclusively in HBV-/HCV- B-NHLs, while miR-30b was increased in HBV+ and HCV+ samples, though only the HCV+ achieved full statistical significance. Analysis of a small subset of B-NHLs belonging to the same histological subtype (Nodal Marginal Zone Lymphoma) highlighted three miRs associated with HCV infection (miR-223, miR-29a and miR-29b) and confirmed decreased level of miR-92a in HBV-/HCV- samples also when considering this restricted B-NHL group.

Conclusions

Although caution is needed due to the limited number of analyzed samples, overall the results suggest that differences at the miR expression level exist between indolent B-NHLs developed in patients with or without HBV or HCV infection. The identification of three further miRs associated with HCV by analyzing histologically homogeneous samples suggests that variations of miR levels possibly associated with HBV or HCV may be obscured by the tissue-specific variability of miR level associated with the different histological subtypes of B-NHL. Thus, the identification of further miRs will require, in addition to an increased sample size, the comparison of B-NHL tissues with the same histological classification.

The potential of microRNAs in personalized medicine against cancers

MicroRNAs orchestrate the expression of the genome and impact many, if not all, cellular processes. Their deregulation is thus often causative of human malignancies, including cancers. Numerous studies have implicated microRNAs in the different steps of tumorigenesis including initiation, progression, metastasis, and resistance to chemo/radiotherapies. Thus, microRNAs constitute appealing targets for novel anticancer therapeutic strategies aimed at restoring their expression or function. As microRNAs are present in a variety of human cancer types, microRNA profiles can be used as tumor-specific signatures to detect various cancers (diagnosis), to predict their outcome (prognosis), and to monitor their treatment (theranosis). In this review, we present the different aspects of microRNA biology that make them remarkable molecules in the emerging field of personalized medicine against cancers and provide several examples of their industrial exploitation.

Enterococcus faecalis Infection and Reactive Oxygen Species Down-Regulates the miR-17-92 Cluster in Gastric Adenocarcinoma Cell Culture

Chronic inflammation due to bacterial overgrowth of the stomach predisposes to the development of gastric cancer and is also associated with high levels of reactive oxygen species (ROS). In recent years increasing attention has been drawn to microRNAs (miRNAs) due to their role in the pathogenesis of many human diseases including gastric cancer. Here we studied the impact of infection by the gram-positive bacteria Enterococcus faecalis (E. faecalis) on global miRNA expression as well as the effect of ROS on selected miRNAs. Human gastric adenocarcinoma cell line MKN74 was infected with living E. faecalis for 24 h or for 5 days or with E. faecalis lysate for 5 days. The miRNA expression was examined by microarray analysis using Affymetrix GeneChip miRNA Arrays. To test the effect of ROS, MKN74 cells were treated with 100 mM tert-Butyl hydroperoxide (TBHP). Following 5 days of E. faecalis infection we found 91 differentially expressed miRNAs in response to living bacteria and 2 miRNAs responded to E. faecalis lysate. We verified the down-regulation of the miR-17-92 and miR-106-363 clusters and of other miRNAs involved in the oxidative stress-response by qRT-PCR. We conclude that only infection by living E. faecalis bacteria caused a significant global response in miRNA expression in the MKN74 cell culture. E. faecalis infection as well as ROS stimulation down-regulated the expression of the miR-17-92 cluster. We believe that these changes could reflect a general response of gastric epithelial cells to bacterial infections.