Vesicle-related microRNAs in plasma of nonsmall cell lung cancer patients and correlation with survival

Deregulation of serum microRNA expression is associated with cigarette smoking and lung cancer

Lung cancer is the leading cause of cancer-related death and cigarette smoking is the main risk factor for lung cancer. Circulating microRNAs (miRNAs) are considered potential biomarkers of various cancers, including lung cancer. However, it is unclear whether changes in circulating miRNAs are associated with smoking and smoking-related lung cancer. In this study, we determined the serum miRNA profiles of 10 nonsmokers, 10 smokers, and 10 lung-cancer patients with miRCURY LNA microRNA arrays. The differentially expressed miRNAs were then confirmed in a larger sample. We found that let-7i-3p and miR-154-5p were significantly downregulated in the sera of smokers and lung-cancer patients, so the serum levels of let-7i-3p and miR-154-5p are associated with smoking and smoking-related lung cancer. The areas under receiver operating characteristic curves for let-7i-3p and miR-154-5p were approximately 0.892 and 0.957, respectively. In conclusion, our results indicate that changes in serum miRNAs are associated with cigarette smoking and lung cancer and that let-7i-3p and miR-154-5p are potential biomarkers of smoking-related lung cancer.

MicroRNAs as lung cancer biomarkers

Lung cancer is the leading cause of cancer mortality worldwide. Its high mortality is due to the poor prognosis of the disease caused by a late disease presentation, tumor heterogeneities within histological subtypes, and the relatively limited understanding of tumor biology. Importantly, lung cancer histological subgroups respond differently to some chemotherapeutic substances and side effects of some therapies appear to vary between subgroups. Biomarkers able to stratify for the subtype of lung cancer, prognosticate the course of disease, or predict the response to treatment are in high demand. In the last decade, microRNAs (miRNAs), measured in resected tumor samples or in fine needle aspirate samples have emerged as biomarkers for tumor diagnosis, prognosis and prediction of response to treatment, due to the ease of their detection and in their extreme specificity. Moreover, miRNAs present in sputum, in plasma, in serum or in whole blood have increasingly been explored in the last five years as less invasive biomarkers for the early detection of cancers. In this review we cover the increasing amounts of data that have accumulated in the last ten years on the use of miRNAs as lung cancer biomarkers.

The impact of extracellular vesicle-encapsulated circulating microRNAs in lung cancer research

Lung cancer is the leading cause of cancer-related deaths. Biomarkers for lung cancer have raised great expectations in their clinical applications for early diagnosis, survival, and therapeutic responses. MicroRNAs (miRNAs), a family of short endogenous noncoding RNAs, play critical roles in cell growth, differentiation, and the development of various types of cancers. Current studies have shown that miRNAs are present in the extracellular spaces, packaged into various membrane-bound vesicles. Tumor-specific circulating miRNAs have been developed as early diagnostic biomarkers for lung cancer. Remarkably, some studies have succeeded in discovering circulating miRNAs with prognostic or predictive significance. Extracellular vesicles (EVs), such as exosomes and microvesicles, are recognized as novel tools for cell-cell communication and as biomarkers for various diseases. Their vesicle composition and miRNA content have the ability to transfer biological information to recipient cells and play an important role in cancer metastasis and prognosis. This review provides an in-depth summary of current findings on circulating miRNAs in lung cancer patients used as diagnostic biomarkers. We also discuss the role of EV miRNAs in cell-cell communication and explore the effectiveness of these contents as predictive biomarkers for cancer malignancy.

Forensic miRNA: potential biomarker for body fluids?

In forensic investigation, body fluids represent an important support to professionals when detected, collected and correctly identified. Through many years, various approaches were used, namely serology-based methodologies however, their lack of sensitivity and specificity became difficult to set aside. In order to sidetrack the problem, miRNA profiling surged with a real potential to be used to identify evidences like urine, blood, menstrual blood, saliva, semen and vaginal secretions. MiRNAs are small RNA structures with 20-25 nt whose proprieties makes them less prone to degradation processes when compared to mRNA which is extremely important once, in a crime scene, biological evidences might be exposed to several unfavorable environmental factors. Recently, published studies were able to identify some specific miRNAs, however their results were not always reproducible by others which can possibly be the reflection of different workflow strategies for their profiling studies. Given the current blast of interest in miRNAs, it is important to acknowledge potential limitations of miRNA profiling, yet, the lack of such studies are evident. This review pretends to gather all the information to date and assessed a multitude of factors that have a potential aptitude to discrediting miRNA profiling, such as: methodological approaches, environmental factors, physiological conditions, gender, pathologies and samples storage. It can be asserted that much has yet to be made, but we pretend to highlight a potential answer for the ultimate question: Can miRNA profiling be used as the forensic biomarker for body fluids identification?

Plasma microRNAs are promising novel biomarkers for the early detection of Toxoplasma gondii infection

Background

MicroRNAs (miRNAs) have been shown to be present in plasma, which are remarkably stable, and have been suggested as disease biomarkers. Toxoplasma gondii (T. gondii) is a protozoan parasite that is infective to a wide range of animals and human beings. Previous studies have found that the parasite generated a large number of miRNAs during proliferation and it is known that the spectrum of miRNA expression in the infected hosts is pathogen-specific. To date, there are no reports regarding the application of microRNAs as biomarkers for the early detection of T. gondii infection.

Methods

In this study, we investigated the expression patterns of 414 murine miRNAs and tested their expression levels in the plasma after T. gondii infection by real-time PCR, with an ultimate purpose of identifying infection-related miRNAs. Three miRNAs in particular, exhibiting prominently elevated expressions, were further validated in a large number of infected mice. The Toxoplasma infection-specific miRNAs were confirmed by comparing their expression levels with those of mice infected with Plasmodium berghei, P. yoelii, P. chabaudi, Cryptosporidium parvum, Mouse hepatitis virus, and Staphylococcus aureus.

Results

Among the 414 miRNA candidates identified by a real-time PCR array, 71 were found to be up-regulated in the plasma of T. gondii infected mice. Three of those miRNAs (mmu-miR-712-3p, mmu-miR-511-5p and mmu-miR-217-5p) were prominently expressed in mice infected by both the RH and ME49 strains of T. gondii. Additionally, the elevated expression of these miRNAs was Toxoplasma-specific.

Conclusions

The levels of the three miRNAs, mmu-miR-712-3p, mmu-miR-511-5p and mmu-miR-217-5p miRNAs, were found specifically up-regulated in plasma of mice after T. gondii infection.

MicroRNA-30e* suppresses dengue virus replication by promoting NF-κB-dependent IFN production

MicroRNAs have been shown to contribute to a repertoire of host-pathogen interactions during viral infection. Our previous study demonstrated that microRNA-30e* (miR-30e*) directly targeted the IκBα 3'-UTR and disrupted the NF-κB/IκBα negative feedback loop, leading to hyperactivation of NF-κB. This current study investigated the possible role of miR-30e* in the regulation of innate immunity associated with dengue virus (DENV) infection. We found that DENV infection could induce miR-30e* expression in DENV-permissive cells, and such an overexpression of miR-30e* upregulated IFN-β and the downstream IFN-stimulated genes (ISGs) such as OAS1, MxA and IFITM1, and suppressed DENV replication. Furthermore, suppression of IκBα mediates the enhancing effect of miR-30e* on IFN-β-induced antiviral response. Collectively, our findings suggest a modulatory role of miR-30e* in DENV induced IFN-β signaling via the NF-κB-dependent pathway. Further investigation is needed to evaluate whether miR-30e* has an anti-DENV effect in vivo.

Design and Analysis for Studying microRNAs in Human Disease: A Primer on -Omic Technologies

microRNAs (miRNAs) are fundamental to cellular biology. Although only approximately 22 bases long, miRNAs regulate complex processes in health and disease, including human cancer. Because miRNAs are highly stable in circulation when compared with several other classes of nucleic acids, they have generated intense interest as clinical biomarkers in diverse epidemiologic studies. As with other molecular biomarker fields, however, miRNA research has become beleaguered by pitfalls related to terminology and classification; procedural, assay, and study cohort heterogeneity; and methodological inconsistencies. Together, these issues have led to both false-positive and potentially false-negative miRNA associations. In this review, we summarize the biological rationale for studying miRNAs in human disease with a specific focus on circulating miRNAs, which highlight some of the most challenging topics in the field to date. Examples from lung cancer are used to illustrate the potential utility and some of the pitfalls in contemporary miRNA research. Although the field is in its infancy, several important lessons have been learned relating to cohort development, sample preparation, and statistical analysis that should be considered for future studies. The goal of this primer is to equip epidemiologists and clinical researchers with sound principles of study design and analysis when using miRNAs.

Underexpression of miR-126 and miR-20b in hereditary and nonhereditary colorectal tumors

OBJECTIVES

The aim of the study was to determine the significance of miR-126 and miR-20b in colorectal carcinogenesis.

METHODS

We analyzed the expressions of miR-126 and miR-20b in 136 colorectal tumors from 39 microsatellite stable (MSS) tumors, 23 high microsatellite instability (MSI-H) tumors, 16 Lynch syndrome, and 58 familial adenomatous polyposis (FAP) tumors including adenoma, intramucosal carcinoma, and invasive carcinoma.

RESULTS

All four kinds of tumors showed underexpression of both miR-126 and miR-20b. The frequency of miR-126 downregulation was 100.0% in FAP adenomas, 85.7% in FAP intramucosal carcinomas, 78.9% in invasive carcinomas, 81.3% in Lynch syndrome tumors, 68.4% in MSS tumors, and 65.4% in MSI-H tumors. The frequency of miR-20b downregulation was 64.0% in FAP adenomas, 50.0% in FAP intramucosal carcinomas, 73.3% in invasive carcinomas, 62.5% in Lynch syndrome tumors, 79.5% in MSS tumors, and 91.3% in MSI-H tumors. The current study demonstrated underexpression of miR-126 and miR-20b in various types of colorectal cancer. These findings support the hypothesis that angiogenesis results from underexpressions of miR-126 and miR-20b and occurs as an early event in colorectal carcinogenesis.

CONCLUSIONS

Underexpression of miR-126 and miR-20b was observed in various types of colorectal cancer, and occurs as an early event of colorectal carcinogenesis in FAP tumors.

miRNAs as non-invasive biomarkers for lung cancer diagnosis

Lung cancer is a leading cause of cancer death and late diagnosis is one of the most important reasons for the high mortality rate. Circulating microRNAs (miRNAs) represent stable and reproducible markers for numerous solid tumors, including lung cancer, and have been hypothesized as non-invasive diagnostic markers. Serum, plasma or whole peripheral blood can be used as starting material, and several methodological approaches have been proposed to evaluate miRNA expression. The present review provides an in depth summary of current knowledge on circulating miRNAs in different types of biological samples used as diagnostic markers of lung cancer. We also evaluate the diagnostic accuracy of each miRNA or group of miRNAs in relation to the different housekeeping miRNAs used. Finally, the limitations and potential of miRNA analysis are discussed.

The new concepts on overcoming drug resistance in lung cancer

Lung cancer is one of the most deadly diseases worldwide. The current first-line therapies include chemotherapy using epidermal growth factor receptor tyrosine kinase inhibitors and radiotherapies. With the current progress in identifying new molecular targets, acquired drug resistance stands as an obstacle for good prognosis. About half the patients receiving epidermal growth factor receptor-tyrosine kinase inhibitor treatments develop resistance. Although extensive studies have been applied to elucidate the underlying mechanisms, evidence is far from enough to establish a well-defined picture to correct resistance. In the review, we will discuss four different currently developed strategies that have the potential to overcome drug resistance in lung cancer therapies and facilitate prolonged anticancer effects of the first-line therapies.

The validity of circulating microRNAs in oncology: five years of challenges and contradictions

MicroRNAs (miRNAs) in circulation have received an increasing amount of interest as potential minimal invasive diagnostic tools in oncology. Several diagnostic, prognostic and predictive signatures have been proposed for a variety of cancers at different stages of disease, but these have not been subjected to a critical review regarding their validity: reproducible identification in comparable studies and/or with different platforms of miRNA detection. In this review, we will critically address the results of circulating miRNA research in oncology that have been published between January 2008 and June 2013 (5.5 years), and discuss pre-analytical challenges, technological pitfalls and limitations that may contribute to the non-reproducibility of circulating miRNA research.

Different exosome cargo from plasma/bronchoalveolar lavage in non-small-cell lung cancer

Tumor-derived exosomes mediate tumorigenesis by facilitating tumor growth, metastasis, development of drug resistance, and immunosuppression. However, little is known about the exosomes isolated from bronchoalveolar lavage (BAL) in patients with lung neoplasm. Exosomes isolated in plasma and BAL from 30 and 75 patients with tumor and nontumor pathology were quantified by acetylcholinesterase activity and characterized by Western Blot, Electron Microscopy, and Nanoparticle Tracking Analysis. Differences in exosome cargo were analyzed by miRNA quantitative PCR in pooled samples and validated in a second series of patients. More exosomes were detected in plasma than in BAL in both groups (P < 0.001). The most miRNAs evaluated by PCR array were detected in tumor plasma, tumor BAL, and nontumor BAL pools, but only 56% were detected in the nontumor plasma pool. Comparing the top miRNAs with the highest levels detected in each pool, we found close homology only between the BAL samples of the two pathologies. In tumor plasma, we found a higher percentage of miRNAs with increased levels than in tumor BAL or in nontumor plasma. The data reveal differences between BAL and plasma exosome amount and miRNA content.

Oncogenic micro-RNAs and Renal Cell Carcinoma

Tumor formation is a complex process that occurs in different steps and involves many cell types, including tumor cells, endothelial cells, and inflammatory cells, which interact to promote growth of the tumor mass and metastasization. Epigenetic alterations occurring in transformed cells result in de-regulation of miRNA expression (a class of small non-coding RNA that regulates multiple functions), which contributes to tumorigenesis. The specific miRNAs, which have an aberrant expression in tumors, are defined as oncomiRNAs, and may be either over- or under-expressed, but down-regulation is most commonly observed. Renal cell carcinoma (RCC) is a frequent form of urologic tumor, associated with an alteration of multiple signaling pathways. Many molecules involved in the progression of RCCs, such as HIF, VEGF, or mammalian target of rapamycin, are possible targets of de-regulated miRNAs. Within tumor mass, the cancer stem cell (CSC) population is a fundamental component that promotes tumor growth. The CSC hypothesis postulates that CSCs have the unique ability to self-renew and to maintain tumor growth and metastasis. CSCs present in RCC were shown to express the mesenchymal stem cell marker CD105 and to exhibit self-renewal and clonogenic properties, as well as the ability to generate serially transplantable tumors. The phenotype of CSC has been related to the potential to undergo the epithelial–mesenchymal transition, which has been linked to the expression pattern of tumorigenic miRNAs or down-regulation of anti-tumor miRNAs. In addition, the pattern of circulating miRNAs may allow discrimination between healthy and tumor patients. Therefore, a miRNA signature may be used as a tumor biomarker for cancer diagnosis, as well as to classify the risk of relapse and metastasis, and for a guide for therapy.

Assessment of circulating microRNAs in plasma of lung cancer patients

Lung cancer is the most common cause of cancer deaths worldwide and numerous ongoing research efforts are directed to identify new strategies for its early detection. The development of non-invasive blood-based biomarkers for cancer detection in its preclinical phases is crucial to improve the outcome of this deadly disease. MicroRNAs (miRNAs) are a new promising class of circulating biomarkers for cancer detection and prognosis definition, but lack of consensus on data normalization methods for circulating miRNAs and the critical issue of haemolysis, has affected the identification of circulating miRNAs with diagnostic potential. We describe here an interesting approach for profiling circulating miRNAs in plasma samples based on the evaluation of reciprocal miRNA levels measured by quantitative Real-Time PCR. By monitoring changes of plasma miRNA-ratios, it is possible to assess the deregulation of tumor-related miRNAs and identify signatures with diagnostic and prognostic value. In addition, to avoid bias due to the release of miRNAs from blood cells, a miRNA-ratios signature distinguishing haemolyzed samples was identified. The method described was validated in plasma samples of lung cancer patients, but given its reproducibility and reliability, could be potentially applied for the identification of diagnostic circulating miRNAs in other diseases.

Emerging technologies in extracellular vesicle-based molecular diagnostics

Extracellular vesicles (EVs), including exosomes and microvesicles, have been shown to carry a variety of biomacromolecules including mRNA, microRNA and other non-coding RNAs. Within the past 5 years, EVs have emerged as a promising minimally invasive novel source of material for molecular diagnostics. Although EVs can be easily identified and collected from biological fluids, further research and proper validation is needed in order for them to be useful in the clinical setting. In addition, innovative and more efficient means of nucleic acid profiling are needed to facilitate investigations into the cellular and molecular mechanisms of EV function and to establish their potential as useful clinical biomarkers and therapeutic tools. In this article, we provide an overview of recent technological improvements in both upstream EV isolation and downstream analytical technologies, including digital PCR and next generation sequencing, highlighting future prospects for EV-based molecular diagnostics.

Methodological challenges in utilizing miRNAs as circulating biomarkers

MicroRNAs (miRNAs) have emerged as important regulators in the post-transcriptional control of gene expression. The discovery of their presence not only in tissues but also in extratissular fluids, including blood, urine and cerebro-spinal fluid, together with their changes in expression in various pathological conditions, has implicated these extracellular miRNAs as informative biomarkers of disease. However, exploiting miRNAs in this capacity requires methodological rigour. Here, we report several key procedural aspects of miRNA isolation from plasma and serum, as exemplified by research in cardiovascular and pulmonary diseases. We also highlight the advantages and disadvantages of various profiling methods to determine the expression levels of plasma- and serum-derived miRNAs. Attention to such methodological details is critical, as circulating miRNAs become diagnostic tools for various human diseases.

Tumor-associated circulating microRNAs as biomarkers of cancer

MicroRNAs (miRNAs), the 17- to 25-nucleotide long noncoding RNAs that modulate the expression of mRNAs and proteins, have emerged as critical players in cancer initiation and progression processes. Deregulation of tissue miRNA expression levels associated with specific genetic alterations has been demonstrated in cancer, where miRNAs function either as oncogenes or as tumor-suppressor genes and are shed from cancer cells into circulation. The present review summarizes and evaluates recent advances in our understanding of the characteristics of tumor tissue miRNAs, circulating miRNAs, and the stability of miRNAs in tissues and their varying expression profiles in circulating tumor cells, and body fluids including blood plasma. These advances in knowledge have led to intense efforts towards discovery and validation of differentially expressing tumor-associated miRNAs as biomarkers and therapeutic targets of cancer. The development of tumor-specific miRNA signatures as cancer biomarkers detectable in malignant cells and body fluids should help with early detection and more effective therapeutic intervention for individual patients.

Clinical relevance of circulating cell-free microRNAs in cancer

Efficient patient management relies on early diagnosis of disease and monitoring of treatment. In this regard, much effort has been made to find informative, blood-based biomarkers for patients with cancer. Owing to their attributes-which are specifically modulated by the tumour-circulating cell-free microRNAs found in the peripheral blood of patients with cancer may provide insights into the biology of the tumour and the effects of therapeutic interventions. Moreover, the role of microRNAs in the regulation of different cellular processes points to their clinical utility as blood-based biomarkers and future therapeutic targets. MicroRNAs are optimal biomarkers owing to high stability under storage and handling conditions and their presence in blood, urine and other body fluids. In particular, detection of levels of microRNAs in blood plasma and serum has the potential for an earlier cancer diagnosis and to predict prognosis and response to therapy. This Review article considers the latest developments in the use of circulating microRNAs as prognostic and predictive biomarkers and discusses their utility in personalized medicine.

MicroRNAs as potential biomarkers in diseases and toxicology

MiRNAs (microRNAs) are single-stranded non-coding RNAs of approximately 21-23 nucleotides in length whose main function is to inhibit gene expression by interfering with mRNA processes. MicroRNAs suppress gene expression by affecting mRNA (messenger RNAs) stability, targeting the mRNA for degradation, or both. In this review, we have examined how microRNA expression could be altered following exposure to chemicals and how they could represent appropriate tissue and more interestingly circulating biomarkers. Among the key questions before using the microRNA for evaluation of risk toxicity, it remains still to clarify how they could be causally involved in the adverse effects and how stable their changes are.

Circulating microRNAs in relation to EGFR status and survival of lung adenocarcinoma in female non-smokers

Objectives

Lung adenocarcinoma is considered a unique disease for Asian female non-smokers. We investigated whether plasma microRNA (miRNA) expression profiles are different by the EGFR status and are associated with survival outcomes of the patients.

Methods

Using real-time RT-PCR, we analyzed the expression of 20 miRNAs in the plasma of 105 female patients with lung adenocarcinoma. Kaplan-Meier survival analysis and Cox proportional hazards regression were performed to determine the association between miRNA expression and overall survival. Time dependent receiver operating characteristic (ROC) analysis was also performed.

Results

In the 20 miRNAs, miR-122 were found differently expressed between wild and mutant EGFR carriers (P=0.018). Advanced disease stage and tumor metastasis were independently associated with poor prognosis of patients with lung adenocarcinoma (P=0.010 and 1.0×10^-4). Plasma levels of miR-195 and miR-122 expression were also associated with overall survival in the patients, especially in those with advanced stage (HR=0.23, 95%CI:0.07-0.84; and HR=0.22, 95%CI:0.06-0.77) and EGFR mutation (HR=0.27, 95%CI:0.08-0.96; and HR=0.23, 95%CI=0.06-0.81). Moreover, a model including miR-195, miR-122 may predict survival outcomes of female patients with lung adenocarcinoma (AUC=0.707).

Conclusions

Circulating miR-195 and miR-122 may have prognostic values in predicting the overall survival as well as predicting EGFR mutation status in non-smoking female patients with lung adenocarcinoma. Measuring plasma levels of miR-195 and miR-122 may especially be useful in EGFR mutant patients with lung adenocarcinoma.

Plasma miRNAs as diagnostic and prognostic biomarkers for ovarian cancer

Background

Most (70%) epithelial ovarian cancers (EOCs) are diagnosed late. Non-invasive biomarkers that facilitate disease detection and predict outcome are needed. The microRNAs (miRNAs) represent a new class of biomarkers. This study was to identify and validate plasma miRNAs as biomarkers in EOC.

Methodology/Principal Findings

We evaluated plasma samples of 360 EOC patients and 200 healthy controls from two institutions. All samples were grouped into screening, training and validation sets. We scanned the circulating plasma miRNAs by TaqMan low-density array in the screening set and identified/validated miRNA markers by real-time polymerase chain reaction assay in the training set. Receiver operating characteristic and logistic regression analyses established the diagnostic miRNA panel, which were confirmed in the validation sets. We found higher plasma miR-205 and lower let-7f expression in cases than in controls. MiR-205 and let-7f together provided high diagnostic accuracy for EOC, especially in patients with stage I disease. The combination of these two miRNAs and carbohydrate antigen-125 (CA-125) further improved the accuracy of detection. MiR-483-5p expression was elevated in stages III and IV compared with in stages I and II, which was consistent with its expression pattern in tumor tissues. Furthermore, lower levels of let-7f were predictive of poor prognosis in EOC patients.

Conclusions/Significance

Our findings indicate that plasma miR-205 and let-7f are biomarkers for ovarian cancer detection that complement CA-125; let-7f may be predictive of ovarian cancer prognosis.

Global analysis of serum microRNAs as potential biomarkers for lung adenocarcinoma

Early diagnosis and the ability to predict the most relevant treatment option for individuals is essential to improve clinical outcomes for non-small cell lung cancer (NSCLC) patients. Adenocarcinoma (ADC), a subtype of NSCLC, is the single biggest cancer killer and therefore an urgent need to identify minimally invasive biomarkers to enable early diagnosis. Recent studies, by ourselves and others, indicate that circulating miRNAs have potential as biomarkers. Here we applied global profiling approaches in serum from patients with ADC of the lung to explore if miRNAs have potential as diagnostic biomarkers. This study involved RNA isolation from 80 sera specimens including those from ADC patients (equal numbers of stages 1, 2, 3, and 4) and age- and gender-matched controls (n = 40 each). Six hundred and sixty-seven miRNAs were co-analyzed in these specimens using TaqMan low density arrays and qPCR validation using individual miRNAs. Overall, approximately 390 and 370 miRNAs were detected in ADC and control sera, respectively. A group of 6 miRNAs, miR-30c-1* (AUC = 0.74; P<0.002), miR-616* (AUC = 0.71; P = 0.001), miR-146b-3p (AUC = 0.82; P<0.0001), miR-566 (AUC = 0.80; P<0.0001), miR-550 (AUC = 0.72; P = 0.0006), and miR-939 (AUC = 0.82; P<0.0001) was found to be present at substantially higher levels in ADC compared with control sera. Conversely, miR-339-5p and miR-656 were detected at substantially lower levels in ADC sera (co-analysis resulting in AUC = 0.6; P = 0.02). Differences in miRNA profile identified support circulating miRNAs having potential as diagnostic biomarkers for ADC. More extensive studies of ADC and control serum specimens are warranted to independently validate the potential clinical relevance of these miRNAs as minimally invasive biomarkers for ADC.

Pathway-based serum microRNA profiling and survival in patients with advanced stage non-small cell lung cancer

This study was designed to identify TGF-β signaling pathway-related serum microRNAs (miRNA) as predictors of survival in advanced non-small cell lung cancer (NSCLC). Serum samples from 391 patients with advanced NSCLC were collected before treatment. Global miRNA microarray expression profiling based on sera from four patients with good survival (>24 months) and four patients with poor survival (<6 months) was used to identify 140 highly expressed serum miRNAs, among which 35 miRNAs had binding sites within the 3'-untranslated regions of a panel of 11 genes in the TGF-β signaling pathway and were assayed by quantitative RT-PCR for their associations with survival in a training (n = 192) and testing set (n = 191). Out of the 35 miRNAs, survival analysis using Cox regression model identified 17 miRNAs significantly associated with 2-year patient survival. MiR-16 exhibited the most statistically significant association: high expression of miR-16 was associated with a significantly better survival [adjusted hazard ratio (HR) = 0.4, 95% confidence interval (CI): 0.3-0.5]. A combined 17-miRNA risk score was created that was able to identify patients at the highest risk of death. Those with a high-risk score had a 2.5-fold increased risk of death compared with those with a low risk score (95% CI: 1.8-3.4; P = 1.1 × 10(-7)). This increase in risk of death was corresponding to a 7.8-month decrease in median survival time (P = 9.5 × 10(-14)). Our results suggest that serum miRNAs could serve as predictors of survival for advanced NSCLC.

MicroRNA as a new factor in lung and esophageal cancer

Lung cancer is the most lethal cancer due to late detection in advanced stages; early diagnosis of lung cancer allows surgical treatment and improves the outcome. The prevalence of gastroesophageal reflux-related adenocarcinomas of the esophagus is increasing; repetitive surveillance endoscopies are necessary to detect development of cancer. A blood-based biomarker would simplify the diagnosis and treatment of both diseases. MicroRNAs (miRNAs) are short RNA strands that interfere with protein production. miRNAs play pivotal roles in cell homeostasis, and dysregulation of miRNAs can lead to the development of cancer. miRNAs can be found in all body fluids and have been proposed to serve as messengers between closely localized cells but also distant organs. Cancer cells actively secrete miRNAs, and these miRNA profiles can be found in blood. We outline, here, how these miRNAs may aid in diagnosis and treatment of lung and esophageal cancers, as well as their apparent limitations.

Distinct microRNAs expression profile in primary biliary cirrhosis and evaluation of miR 505-3p and miR197-3p as novel biomarkers

BACKGROUND AND AIMS

MicroRNAs are small endogenous RNA molecules with specific expression patterns that can serve as biomarkers for numerous diseases. However, little is known about the expression profile of serum miRNAs in PBC.

METHODS

First, we employed Illumina deep sequencing for the initial screening to indicate the read numbers of miRNA expression in 10 PBC, 5 CH-C, 5 CH-B patients and 5 healthy controls. Comparing the differentially expressed miRNAs in the 4 groups, analysis of variance was performed on the number of sequence reads to evaluate the statistical significance. Hierarchical clustering was performed using an R platform and we have found candidates for specific miRNAs in the PBC patients. Second, a quantitative reverse transcription PCR validation study was conducted in 10 samples in each group. The expression levels of the selected miRNAs were presented as fold-changes (2(-ΔΔCt)). Finally, computer analysis was conducted to predict target genes and biological functions with MiRror 2.0 and DAVID v6.7.

RESULTS

We obtained about 12 million 32-mer short RNA reads on average per sample and the mapping rates to miRBase were 16.60% and 81.66% to hg19. In the statistical significance testing, the expression levels of 81 miRNAs were found to be differentially expressed in the 4 groups. The heat map and hierarchical clustering demonstrated that the miRNA profiles from PBC clustered with those of CH-B, CH-C and healthy controls. Additionally, the circulating levels of hsa-miR-505-3p, 197-3p, and 500a-3p were significantly decreased in PBC compared with healthy controls and the expression levels of hsa-miR-505-3p, 139-5p and 197-3p were significantly reduced compared with the viral hepatitis group.

CONCLUSIONS

Our results indicate that sera from patients with PBC have a unique miRNA expression profile and that the down-regulated expression of hsa-miR-505-3p and miR-197-3p can serve as clinical biomarkers of PBC.

Clinical evaluation of microRNA expression profiling in non small cell lung cancer

Deregulation of miRNAs expression levels has been detected in many human tumor types, and recent studies have demonstrated the critical roles of miRNAs in cancer pathogenesis. Numerous recent studies have shown that miRNAs are rapidly released from tissues into the circulation in many pathological conditions. The high relative stability of miRNAs in biofluids such as plasma and serum, and the ability of miRNA expression profiles to accurately classify discrete tissue types and disease states have positioned miRNAs as promising non-invasive new tumor biomarkers. In this study, we used liquid bead array technology (Luminex) to profile the expression of 320 mature miRNAs in a pilot testing group of 19 matched fresh frozen cancerous and non-cancerous tissues from NSCLC patients. We further validated our results by RT-qPCR for differentially expressed miRNAs in an independent group of 40 matched fresh frozen tissues, 37 plasma samples from NSCLC patients and 28 healthy donors. We found that eight miRNAs (miR-21, miR-30d, miR-451, miR-10a, miR-30e-5p and miR-126*, miR-126, miR-145) were differentially expressed by three different statistical analysis approaches. Two of them (miR-10a and miR-30e-5p) are reported here for the first time. Bead-array results were further verified in an independent group of 40 matched fresh frozen tissues by RT-qPCR. According to RT-qPCR miR-21 was significantly up-regulated (P = 0.010), miR-126* (P = 0.002), miR-30d (P = 0.012), miR-30e-5p (P < 0.001) and miR-451 (P < 0.001) were down-regulated, while miR-10a was not differentiated (P = 0.732) in NSCLC tissues. However, in NSCLC plasma samples, only three of these miRNAs (miR-21, miR-10a, and miR-30e-5p) displayed differential expression when compared to plasma of healthy donors. High expression of miR-21 was associated with DFI and OS both in NSCLC tissues (P = 0.022 and P = 0.037) and plasma (P = 0.045 and P = 0.065), respectively. Moreover, we report for the first time that low expression of miR-10a in NSCLC plasma samples was associated with worse DFI (P = 0.050) and high expression of miR-30e-5p was found to be associated with shorter OS (P = 0.048). In conclusion, circulating miR-21, miR-10a and miR-30e-5p in plasma should be further evaluated as potential non-invasive biomarkers in NSCLC.

Fludarabine treatment favors the retention of miR-485-3p by prostate cancer cells: implications for survival

Background

Circulating microRNAs (miRNAs) have been found in many body fluids and represent reliable markers of several physio-pathological disorders, including cancer. In some cases, circulating miRNAs have been evaluated as markers of the efficacy of anticancer treatment but it is not yet clear if miRNAs are actively released by tumor cells or derive from dead tumor cells.

Results

We showed that a set of prostate cancer secretory miRNAs (PCS-miRNAs) were spontaneously released in the growth medium by DU-145 prostate cancer cells and that the release was greater after treatment with the cytotoxic drug fludarabine. We also found that the miRNAs were associated with exosomes, implying an active mechanism of miRNA release. It should be noted that in fludarabine treated cells the release of miR-485-3p, as well as its association with exosomes, was reduced suggesting that miR-485-3p was retained by surviving cells. Monitoring the intracellular level of miR-485-3p in these cells, we found that miR-485-3p was stably up regulated for several days after treatment. As a possible mechanism we suggest that fludarabine selected cells that harbor high levels of miR-485-3p, which in turn regulates the transcriptional repressor nuclear factor-Y triggering the transcription of topoisomerase IIα, multidrug resistance gene 1 and cyclin B2 pro-survival genes.

Conclusions

Cytotoxic treatment of DU-145 cells enhanced the release of PCS-miRNAs with the exception of miR-485-3p which was retained by surviving cells. We speculate that the retention of miR-485-3p was a side effect of fludarabine treatment in that the high intracellular level of miR-485-3p plays a role in the sensitivity to fludarabine.

Cigarette smoking substantially alters plasma microRNA profiles in healthy subjects

Circulating microRNAs (miRNAs) are receiving attention as potential biomarkers of various diseases, including cancers, chronic obstructive pulmonary disease, and cardiovascular disease. However, it is unknown whether the levels of circulating miRNAs in a healthy subject might vary with external factors in daily life. In this study, we investigated whether cigarette smoking, a habit that has spread throughout the world and is a risk factor for various diseases, affects plasma miRNA profiles. We determined the profiles of 11 smokers and 7 non-smokers by TaqMan MicroRNA array analysis. A larger number of miRNAs were detected in smokers than in non-smokers, and the plasma levels of two-thirds of the detected miRNAs (43 miRNAs) were significantly higher in smokers than in non-smokers. A principal component analysis of the plasma miRNA profiles clearly separated smokers and non-smokers. Twenty-four of the miRNAs were previously reported to be potential biomarkers of disease, suggesting the possibility that smoking status might interfere with the diagnosis of disease. Interestingly, we found that quitting smoking altered the plasma miRNA profiles to resemble those of non-smokers. These results suggested that the differences in the plasma miRNA profiles between smokers and non-smokers could be attributed to cigarette smoking. In addition, we found that an acute exposure of ex-smokers to cigarette smoke (smoking one cigarette) did not cause a dramatic change in the plasma miRNA profile. In conclusion, we found that repeated cigarette smoking substantially alters the plasma miRNA profile, interfering with the diagnosis of disease or signaling potential smoking-related diseases.

Non-Coding RNAs: Functional Aspects and Diagnostic Utility in Oncology

Noncoding RNAs (ncRNAs) have been found to have roles in a large variety of biological processes. Recent studies indicate that ncRNAs are far more abundant and important than initially imagined, holding great promise for use in diagnostic, prognostic, and therapeutic applications. Within ncRNAs, microRNAs (miRNAs) are the most widely studied and characterized. They have been implicated in initiation and progression of a variety of human malignancies, including major pathologies such as cancers, arthritis, neurodegenerative disorders, and cardiovascular diseases. Their surprising stability in serum and other bodily fluids led to their rapid ascent as a novel class of biomarkers. For example, several properties of stable miRNAs, and perhaps other classes of ncRNAs, make them good candidate biomarkers for early cancer detection and for determining which preneoplastic lesions are likely to progress to cancer. Of particular interest is the identification of biomarker signatures, which may include traditional protein-based biomarkers, to improve risk assessment, detection, and prognosis. Here, we offer a comprehensive review of the ncRNA biomarker literature and discuss state-of-the-art technologies for their detection. Furthermore, we address the challenges present in miRNA detection and quantification, and outline future perspectives for development of next-generation biodetection assays employing multicolor alternating-laser excitation (ALEX) fluorescence spectroscopy.

MicroRNAs as Biomarkers in Cancer

MicroRNAs (miRNAs) are small non-coding RNA molecules, which in recent years have emerged to have enormous potential as biomarkers. Recently, there have been significant developments in understanding miRNA biogenesis, their regulatory mechanisms and role in disease process, and their potential as effective therapies. The identification of miRNAs as biomarkers provides possibilities for development of less or non-invasive and more specific methods for monitoring tumor growth and progression. This review summarizes the recent developments in methods to detect and quantitate miRNAs in body fluids and their applications as biomarkers in cancers. The prospect of miRNAs as potential diagnostic and prognostic biomarkers with clinical applications is significant as more evidence points to their central role in cancer pathobiology.

Cell-free microRNAs as diagnostic, prognostic, and predictive biomarkers for lung cancer

Lung cancer is the most common cancer worldwide, accounting for over 1.37 million deaths annually. The clinical outcome and management of lung cancer patients could be substantially improved by the implementation of non-invasive biomarker assays for the early detection, prognosis as well as prediction and monitoring of treatment response. MicroRNAs (miRNAs) have been implicated in the regulation of virtually all signaling circuits within a cell and their dysregulation has been shown to play an essential role in the development and progression of cancer. Recently, miRNAs were found to be released into the circulation and to exist there in a remarkably stable form. Furthermore, various cancers were shown to leave specific miRNA fingerprints in the blood of patients suggesting that cell-free miRNAs could serve as non-invasive biomarkers for the detection or monitoring of cancer and putative therapeutic targets. Since that, a considerable effort has been devoted to decode the information carried by circulating miRNAs. In the current review, we give an insight into the mechanisms of miRNA release into the bloodstream, their putative functional significance and systematically review the studies focused on the identification of cell-free miRNAs with the diagnostic, prognostic, and predictive significance in lung cancer and discuss their potential clinical utility.

Role of microRNAs in lung cancer: microRNA signatures in cancer prognosis

Lung cancer-related mortality is the most common cause of cancer death worldwide. Detecting lung cancer at an earlier stage and, ideally, predicting who will develop the disease and particularly the most aggressive forms of cancer are the biggest challenge. MicroRNAs (miRNAs) are short, noncoding RNA molecules with regulatory function on protein-coding genes. Because of their fundamental role in development and differentiation, their involvement in the biological mechanisms underlying tumorigenesis, as well as their low complexity, stability, and easy detection, they represent a promising class of tissue- and blood-based biomarkers of cancer. We summarize the current literature on the use of microRNAs as diagnostic and prognostic tools in lung cancer and discuss the relevant clinical implications of these findings.

MicroRNA profiling predicts survival in anti-EGFR treated chemorefractory metastatic colorectal cancer patients with wild-type KRAS and BRAF

Anti-EGFR monoclonal antibodies (anti-EGFRmAb) serve in the treatment of metastatic colorectal cancer (mCRC), but patients with a mutation in KRAS/BRAF and nearly one-half of those without the mutation fail to respond. We performed microRNA (miRNA) analysis to find miRNAs predicting anti-EGFRmAb efficacy. Of the 99 mCRC patients, we studied differential miRNA expression by microarrays from primary tumors of 33 patients who had wild-type KRAS/BRAF and third- to sixth-line anti-EGFRmAb treatment, with/without irinotecan. We tested the association of each miRNA with overall survival (OS) by the Cox proportional hazards regression model. Significant miR-31* up-regulation and miR-592 down-regulation appeared in progressive disease versus disease control. miR-31* expression and down-regulation of its target genes SLC26A3 and ATN1 were verified by quantitative reverse transcriptase polymerase chain reaction. Clustering of patients based on miRNA expression revealed a significant difference in OS between patient clusters. Members of the let-7 family showed significant up-regulation in the patient cluster with poor OS. Additionally, miR-140-5p up-regulation and miR-1224-5p down-regulation were significantly associated with poor OS in both cluster analysis and the Cox proportional hazards regression model. In mCRC patients with wild-type KRAS/BRAF, miRNA profiling can efficiently predict the benefits of anti-EGFRmAb treatment. Larger series of patients are necessary for application of these miRNAs as predictive/prognostic markers.

High expression of miR-21 and miR-155 predicts recurrence and unfavourable survival in non-small cell lung cancer

We synthesised the evidence of microRNAs as prognostic biomarkers in lung cancer. Studies were identified by searching PubMed, Embase and Web of Science until March 2012. Descriptive characteristics for studies were described and an additional meta-analysis for two specific microRNAs (miR-21 and miR-155) which were studied extensively was performed. Pooled hazard ratios (HRs) and their corresponding 95% confidence intervals (CIs) were calculated. The median study size was 88 patients (interquartile range [IQR]=53-193) and the median HR in the studies that reported statistically significant results was 2.855 (IQR=2.01-5.035). For the studies evaluating miR-21's association with clinical outcomes, the pooled HR suggested that high expression of miR-21 has a negative impact on overall survival (OS) in non-small cell lung cancer (NSCLC) (HR=2.32[1.17-4.62], P<0.05) and recurrence-free survival (RFS)/cancer-specific survival (CSS) in lung adenocarcinoma (HR=2.43[1.67-3.54], P<0.001). As for miR-155, the pooled HR for OS was 2.09 (95%CI: 0.68-6.41, P>0.05) which was not statistically significant, but for RFS/CSS was 1.42 (95% CI: 1.10-1.83, P=0.007). These results indicate that microRNAs show promising associations with prognosis in lung cancer; moreover, specific microRNAs such as miR-21 and miR-155 can predict recurrence and poor survival in NSCLC.

miRandola: extracellular circulating microRNAs database

MicroRNAs are small noncoding RNAs that play an important role in the regulation of various biological processes through their interaction with cellular messenger RNAs. They are frequently dysregulated in cancer and have shown great potential as tissue-based markers for cancer classification and prognostication. microRNAs are also present in extracellular human body fluids such as serum, plasma, saliva, and urine. Most of circulating microRNAs are present in human plasma and serum cofractionate with the Argonaute2 (Ago2) protein. However, circulating microRNAs have been also found in membrane-bound vesicles such as exosomes. Since microRNAs circulate in the bloodstream in a highly stable, extracellular form, they may be used as blood-based biomarkers for cancer and other diseases. A knowledge base of extracellular circulating miRNAs is a fundamental tool for biomedical research. In this work, we present miRandola, a comprehensive manually curated classification of extracellular circulating miRNAs. miRandola is connected to miRò, the miRNA knowledge base, allowing users to infer the potential biological functions of circulating miRNAs and their connections with phenotypes. The miRandola database contains 2132 entries, with 581 unique mature miRNAs and 21 types of samples. miRNAs are classified into four categories, based on their extracellular form: miRNA-Ago2 (173 entries), miRNA-exosome (856 entries), miRNA-HDL (20 entries) and miRNA-circulating (1083 entries). miRandola is available online at: http://atlas.dmi.unict.it/mirandola/index.html.

Cell-free Circulating miRNA Biomarkers in Cancer

Considerable attention and an enormous amount of resources have been dedicated to cancer biomarker discovery and validation. However, there are still a limited number of useful biomarkers available for clinical use. An ideal biomarker should be easily assayed with minimally invasive medical procedures but possess high sensitivity and specificity. Commonly used circulating biomarkers are proteins in serum, most of which require labor-intensive analysis hindered by low sensitivity in early tumor detection. Since the deregulation of microRNA (miRNA) is associated with cancer development and progression, profiling of circulating miRNAs has been used in a number of studies to identify novel minimally invasive miRNA biomarkers. In this review, we discuss the origin of the circulating cell-free miRNAs and their carriers in blood. We summarize the clinical use and function of potentially promising miRNA biomarkers in a variety of different cancers, along with their downstream target genes in tumor initiation and development. Additionally, we analyze some technical challenges in applying miRNA biomarkers to clinical practice.

Circulating miR-17, miR-20a, miR-29c, and miR-223 combined as non-invasive biomarkers in nasopharyngeal carcinoma

Background

MicroRNAs have been considered as a kind of potential novel biomarker for cancer detection due to their remarkable stability in the blood and the characteristics of their expression profile in many diseases.

Methods

We performed microarray-based serum miRNA profiling on the serum of twenty nasopharyngeal carcinoma patients at diagnosis along with 20 non-cancerous individuals as controls. This was followed by a real-time quantitative Polymerase Chain Reaction (RT-qPCR) in a separate cohort of thirty patients with nasopharyngeal carcinoma and thirty age- matched non-cancerous volunteers. A model for diagnosis was established by a conversion of mathematical calculation formula which has been validated by analyzing 74 cases of patients with nasopharyngeal carcinoma and 57 cases of non-cancerous volunteers.

Results

The profiles showed that 39 and 17 miRNAs are exclusively expressed in the serum of non-cancerous volunteers and of patients with nasopharyngeal carcinoma respectively. 4 miRNAs including miR-17, miR-20a, miR-29c, and miR-223 were found to be expressed differentially in the serum of NPC compared with that of non-cancerous control. Based on this, a diagnosis equation with Ct difference method has been established to distinguish NPC cases and non-cancerous controls and validated with high sensitivity and specificity.

Conclusions

We demonstrate that the serum miRNA-based biomarker model become a novel tool for NPC detection. The circulating 4-miRNA-based method may provide a novel strategy for NPC diagnosis.

Circulating microRNA is a biomarker of biliary atresia

OBJECTIVE

The lack of reliable noninvasive diagnostic biomarkers of biliary atresia (BA) results in delayed diagnosis and worsened patient outcome. Circulating microRNAs (miRNAs) are a new class of noninvasive biomarkers with encouraging diagnostic utility.

METHODS

We examined the ability of serum miRNAs to distinguish BA from other forms of neonatal hyperbilirubinemia. BA-specific serum miRNAs were identified using a microfluidic array platform and validated in a larger, independent sample set.

RESULTS

The miR-200b/429 cluster was significantly increased in the sera of patients with BA relative to infants with non-BA cholestatic disorders.

CONCLUSIONS

Circulating levels of the miR-200b/429 cluster are elevated in infants with BA and have promising diagnostic clinical performance.

[Extracellular miRNA: a novel molecular biomarker for lung cancer]

Though continuous development and progress have been made in the early diagnosis and treatment of cancer, it is still difficult to find a sensitive, accurate and minimally invasive biomarker for cancer diagnosis and treatment. MicroRNA (miRNA) is a class of non-coding small endogenous RNAs of 21-24 nucleotides in length. As a novel molecular biomarker, extracellular miRNA (ec-miRNA) has the potential to be a minimally invasive, highly sensitive and highly specific marker in cancer diagnosis. Many research achievements of ec-miRNA have been accumulated in recent years. In this paper, the origin, function and detection of ec-miRNA, its role in lung cancer diagnosis as a novel molecular biomarker, and some issues are reviewed.

Genetic variation in hippocampal microRNA expression differences in C57BL/6 J X DBA/2 J (BXD) recombinant inbred mouse strains

BACKGROUND

miRNAs are short single-stranded non-coding RNAs involved in post-transcriptional gene regulation that play a major role in normal biological functions and diseases. Little is currently known about how expression of miRNAs is regulated. We surveyed variation in miRNA abundance in the hippocampus of mouse inbred strains, allowing us to take a genetic approach to the study of miRNA regulation, which is novel for miRNAs. The BXD recombinant inbred panel is a very well characterized genetic reference panel which allows quantitative trait locus (QTL) analysis of miRNA abundance and detection of correlates in a large store of brain and behavioural phenotypes.

RESULTS

We found five suggestive trans QTLs for the regulation of miRNAs investigated. Further analysis of these QTLs revealed two genes, Tnik and Phf17, under the miR-212 regulatory QTLs, whose expression levels were significantly correlated with miR-212 expression. We found that miR-212 expression is correlated with cocaine-related behaviour, consistent with a reported role for this miRNA in the control of cocaine consumption. miR-31 is correlated with anxiety and alcohol related behaviours. KEGG pathway analysis of each miRNA's expression correlates revealed enrichment of pathways including MAP kinase, cancer, long-term potentiation, axonal guidance and WNT signalling.

CONCLUSIONS

The BXD reference panel allowed us to establish genetic regulation and characterize biological function of specific miRNAs. QTL analysis enabled detection of genetic loci that regulate the expression of these miRNAs. eQTLs that regulate miRNA abundance are a new mechanism by which genetic variation influences brain and behaviour. Analysis of one of these QTLs revealed a gene, Tnik, which may regulate the expression of a miRNA, a molecular pathway and a behavioural phenotype. Evidence of genetic covariation of miR-212 abundance and cocaine related behaviours is strongly supported by previous functional studies, demonstrating the value of this approach for discovery of new functional roles and downstream processes regulated by miRNA.

MicroRNA expression in ovarian carcinoma and its correlation with clinicopathological features

Background

MicroRNA (miRNA) expression is known to be deregulated in ovarian carcinomas. However, limited data is available about the miRNA expression pattern for the benign or borderline ovarian tumors as well as differential miRNA expression pattern associated with histological types, grades or clinical stages in ovarian carcinomas. We defined patterns of microRNA expression in tissues from normal, benign, borderline, and malignant ovarian tumors and explored the relationship between frequently deregulated miRNAs and clinicopathologic findings, response to therapy, survival, and association with Her-2/neu status in ovarian carcinomas.

Methods

We measured the expression of nine miRNAs (miR-181d, miR-30a-3p, miR-30c, miR-30d, miR-30e-3p, miR-368, miR-370, miR-493-5p, miR-532-5p) in 171 formalin-fixed, paraffin-embedded ovarian tissue blocks as well as six normal human ovarian surface epithelial (HOSE) cell lines using Taqman-based real-time PCR assays. Her-2/neu overexpression was assessed in ovarian carcinomas (n = 109 cases) by immunohistochemistry analysis.

Results

Expression of four miRNAs (miR-30c, miR-30d, miR-30e-3p, miR-370) was significantly different between carcinomas and benign ovarian tissues as well as between carcinoma and borderline tissues. An additional three miRNAs (miR-181d, miR-30a-3p, miR-532-5p) were significantly different between borderline and carcinoma tissues. Expression of miR-532-5p was significantly lower in borderline than in benign tissues. Among ovarian carcinomas, expression of four miRNAs (miR-30a-3p, miR-30c, miR-30d, miR-30e-3p) was lowest in mucinous and highest in clear cell samples. Expression of miR-30a-3p was higher in well-differentiated compared to poorly differentiated tumors (P = 0.02), and expression of miR-370 was higher in stage I/II compared to stage III/IV samples (P = 0.03). In multivariate analyses, higher expression of miR-181d, miR-30c, miR-30d, and miR-30e-3p was associated with significantly better disease-free or overall survival. Finally, lower expression of miR-30c, miR-30d, miR-30e-3p and miR-532-5p was significantly associated with overexpression of Her-2/neu.

Conclusions

Aberrant expression of miRNAs is common in ovarian tumor suggesting involvement of miRNA in ovarian tumorigenesis. They are associated with histology, clinical stage, survival and oncogene expression in ovarian carcinoma.

Treatment-independent miRNA signature in blood of Wilms tumor patients

Background

Blood-born miRNA signatures have recently been reported for various tumor diseases. Here, we compared the miRNA signature in Wilms tumor patients prior and after preoperative chemotherapy according to SIOP protocol 2001.

Results

We did not find a significant difference between miRNA signature of both groups. However both, Wilms tumor patients prior and after chemotherapy showed a miRNA signature different from healthy controls. The signature of Wilms tumor patients prior to chemotherapy showed an accuracy of 97.5% and of patients after chemotherapy an accuracy of 97.0%, each as compared to healthy controls.

Conclusion

Our results provide evidence for a blood-born Wilms tumor miRNA signature largely independent of four weeks preoperative chemotherapy treatment.

Peripheral blood microRNAs: A novel tool for diagnosing disease?

Peripheral blood microRNAs (miRNAs) are endogenous, noncoding small RNAs present in blood. Because of their size, abundance, tissue specificity, and relative stability in peripheral circulation, they offer great promise of becoming a novel noninvasive biomarker. However, the mechanism by which they are secreted, their biological function, and the reason for the existence of extracellular miRNAs are largely unclear. This article describes advances in the study of the mechanism of origin and biological function of extracellular miRNAs along with approaches adopted by research and questions that remain. This work also discusses the potential for peripheral blood miRNAs to serve as a diagnostic tool.

microRNA regulation of cell viability and drug sensitivity in lung cancer

INTRODUCTION

microRNAs (miRNAs) are 19 - 23 nucleotide long RNAs found in multiple organisms that regulate gene expression and have been shown to play important roles in tumorigenesis. In the context of lung cancer, numerous studies have shown that tumor suppressor genes and oncogenes that play crucial roles in lung tumor development and progression are targets of miRNA regulation. Manipulation of miRNA levels that modulate lung cancer cell survival and drug sensitivity can therefore provide novel therapeutic targets and agents.

AREAS COVERED

Here, the authors review the published in vitro, in vivo and preclinical studies on the functional role of miRNAs in modulating lung cancer cell viability and drug response, and discuss the limitations and promise of translating current findings into miRNA-based therapeutic and diagnostic strategies.

EXPERT OPINION

Although many miRNAs have been identified as potent regulators of cell viability and drug sensitivity in lung cancer, most of them have not been characterized for potential clinical application. Further study is warranted to evaluate translation of the current findings to the clinic to improve the diagnosis and treatment of lung cancer. In addition, most studies have focused on non-small cell lung cancer (NSCLC). It is therefore important to raise interest in investigating miRNAs in small cell lung cancer (SCLC) as well as in comparative studies of miRNA expression and function in different histological subtypes of lung cancer.

Prognostic impact of circulating miR-21 and miR-375 in plasma of patients with esophageal squamous cell carcinoma

BACKGROUND

miR-21 and miR-375 are reported to be highly and poorly expressed in esophageal squamous cell carcinoma (ESCC) tissues, respectively. Recently, we demonstrated that circulating miR-21 and miR-375 were stably detectable in plasma and reflected tumor dynamics as a tumor marker for ESCC. We hypothesized that these plasma miRNA concentrations contributed to prognostic markers in patients with ESCC.

METHODS

Between 2008 and 2010, 50 preoperative plasma samples were collected from consecutive patients with ESCC, who underwent curative esophagectomy in our hospital. We examined the association between plasma miRNA concentrations and prognosis retrospectively.

RESULTS

i) The postoperative cause-specific survival rate of patients with high plasma miR-21 concentration tended to be poorer than low group (3-yr survival rate: 53.4 and 81.5%, p = 0.1038), while that of high plasma miR-375 group was better than low group (3-yr survival rate: 100 and 65.2%). ii) Patients with high miR-21 and low miR-375 concentrations in plasma had significantly poorer prognosis than other patients (3-yr survival rate: 48.4 and 83.1%, p = 0.039). Multivariate analysis revealed that the presence of high miR-21 and low miR-375 concentrations in plasma was an independent prognostic factor (p = 0.029, hazard ratio 3.8 (1.14-12.5)).

CONCLUSION

Circulating miR-21 and miR-375 could be reliable prognostic markers for ESCC. These plasma markers might facilitate clinical decision-making to select prospective candidates, which need meticulous follow-up for early detection of recurrences and additional treatments such as neo-adjuvant chemotherapy and postoperative chemotherapy in ESCC.

Exosomal RNA as biomarkers and the therapeutic potential of exosome vectors

INTRODUCTION

Exosomes are nano-sized (40 - 100 nm), extracellular vesicles, of endosomal origin. They are released by cells and found in many body fluids, including plasma. Exosomes contain proteins, microRNAs (miRNAs), and messenger RNAs (mRNAs) that can be transferred between cells. The discovery that exosomes contain RNA, and that this encapsulated RNA could potentially be transferred over distances in vivo, reinforced the importance of exosomes in cell-to-cell communication.

AREAS COVERED

The existence of exosomes, as a naturally occurring delivery system of RNA, enables their use as both biomarkers and vectors in gene therapy. This review provides an overview of studies reporting that exosomal miRNA and mRNA in plasma can serve as a diagnostic marker in various types of cancers. In addition, the recent finding that exosomes can be used as vectors for delivery of small interfering RNA (siRNA) in mice, with therapeutic effects, is also reviewed.

EXPERT OPINION

The data reviewed here suggest that exosomal RNA has the potential to play an important role in the diagnosis, prognosis, and treatment of diseases in the future.