MicroRNAs and other non-coding RNAs as targets for anticancer drug development

ZFP36L2 promotes cancer cell aggressiveness and is regulated by antitumor microRNA-375 in pancreatic ductal adenocarcinoma

Due to its aggressive nature, pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal and hard-to-treat malignancies. Recently developed targeted molecular strategies have contributed to remarkable improvements in the treatment of several cancers. However, such therapies have not been applied to PDAC. Therefore, new treatment options are needed for PDAC based on current genomic approaches. Expression of microRNA-375 (miR-375) was significantly reduced in miRNA expression signatures of several types of cancers, including PDAC. The aim of the present study was to investigate the functional roles of miR-375 in PDAC cells and to identify miR-375-regulated molecular networks involved in PDAC aggressiveness. The expression levels of miR-375 were markedly downregulated in PDAC clinical specimens and cell lines (PANC-1 and SW1990). Ectopic expression of miR-375 significantly suppressed cancer cell proliferation, migration and invasion. Our in silico and gene expression analyses and luciferase reporter assay showed that zinc finger protein 36 ring finger protein-like 2 (ZFP36L2) was a direct target of miR-375 in PDAC cells. Silencing ZFP36L2 inhibited cancer cell aggressiveness in PDAC cell lines, and overexpression of ZFP36L2 was confirmed in PDAC clinical specimens. Interestingly, Kaplan-Meier survival curves showed that high expression of ZFP36L2 predicted shorter survival in patients with PDAC. Moreover, we investigated the downstream molecular networks of the miR-375/ZFP36L2 axis in PDAC cells. Elucidation of tumor-suppressive miR-375-mediated PDAC molecular networks may provide new insights into the potential mechanisms of PDAC pathogenesis.

MicroRNAs in Oncogenesis and Tumor Suppression

MicroRNAs (MiRNAs) have emerged in the last 15 years as central players in the biology of cancer. Increasing lines of evidence have supported their regulatory role in the expression of both oncogenes and tumor-suppressor genes, progressively clarifying which genes are modulated by specific MiRNAs dysregulated in cancer. Intriguingly, a "target-specific" understanding of MiRNA function in oncology has been replaced by a more "pathway-specific" vision of their involvement in cancer biology. This work provides a state-of-the-art knowledge of the role of MiRNAs in the most frequently altered signaling pathways in cancer cells and provides an updated overview on some of the most relevant findings trying to decode the complex molecular mechanisms of cancer.

Minicircle-oriP-miR-31 as a Novel EBNA1-Specific miRNA Therapy Approach for Nasopharyngeal Carcinoma

MicroRNAs (miRNAs) are important post-transcriptional regulators that control cancer development and progression. However, the application of miRNA therapy in cancer has been hampered by a lack of an efficient and targeted delivery system. In our previous studies, an oriP promoter-based minicircle system successfully mediated targeted foreign gene expression in EBNA1-positive nasopharyngeal carcinoma (NPC). However, it remains to be evaluated whether this system can be applied for tumor miRNA therapy. miR-31-5p, a tumor suppressive miRNA involved in the tumorigenesis of EBV-positive NPC, was selected as the therapeutic miRNA to be transferred. In this work, we constructed a novel EBNA1-specific miRNA expression system, minicircle-oriP-miR-31. The results indicated that mc-oriP-miR-31 mediated selective miR-31-5p expression in EBNA1-positive NPC cells. Both the proliferation and migration of EBNA1-positive NPC cell lines were inhibited by mc-oriP-miR-31 treatment in vitro. Furthermore, mc-oriP-miR-31 treatment inhibited xenograft growth and lung metastasis in vivo. We also identified WDR5 as a novel miR-31-5p target. Knockdown of WDR5 inhibited NPC cell proliferation and migration and was associated with downregulation of Notch1. Reintroduction of WDR5 partially abrogated the suppressive effects induced by miR-31-5p. In conclusion, we demonstrate for the first time that targeted expression of miR-31-5p using a nonviral minicircle vector can serve as a novel approach for tumor miRNA therapy. Moreover, WDR5 may be a promising therapeutic target for NPC treatment.

MiRNA-29a as a tumor suppressor mediates PRIMA-1Met-induced anti-myeloma activity by targeting c-Myc

The proto-oncogene c-Myc plays substantial role in multiple myeloma (MM) pathogenesis and is considered a potential drug target. Here we provide evidence of a novel mechanism for PRIMA-1Met, a small molecule with anti-tumor activity in phase I/II clinical trial, showing that PRIMA-1Met induces apoptosis in MM cells by suppressing c-Myc and upregulating miRNA-29a. Our study further demonstrates that miRNA-29a functions as a tumor suppressor which targets c-Myc. The baseline expression of miR-29a was significantly lower in MM cell lines and MM patient samples compared to normal hematopoietic cells. In addition, ectopic expression of miRNA-29a or exposure to PRIMA-1Met reduced cell proliferation and induced apoptosis in MM cells. On the other hand, overexpression of c-Myc at least partially reverted the inhibitory effects of PRIMA-1Met or miRNA-29a overexpression suggesting the miRNA-29a/c-Myc axis mediates anti-myeloma effects of PRIMA-1Met. Importantly, intratumor delivery of miRNA-29a mimics induced regression of tumors in mouse xenograft model of MM and this effect synergized with PRIMA-1Met. Our study indicates that miRNA-29a is a tumor suppressor that plays an important role during PRIMA-1Met-induced apoptotic signaling by targeting c-Myc and provides the basis for novel therapeutic strategies using miRNA-29a mimics combined with PRIMA-1Met in MM.

MicroRNA-708-5p acts as a therapeutic agent against metastatic lung cancer

MicroRNAs (miRNAs) have recently been recognized as targets for anti-metastatic therapy against cancer malignancy. Development of effective miRNA mediated therapies remains a challenge to both basic research and clinical practice. Here we presented the evidence for a miR-708-5p mediated replacement therapy against metastatic lung cancer. Expression of miR-708-5p was substantially reduced in metastatic lung cancer samples and cancer cell lines when compared to non-metastatic counterparts. Expression of the miRNA suppressed cell survival and metastasis in vitro through its direct target p21, and inhibited the PI3K/AKT pathway and stem cell-like characteristics of lung cancer cells. Systemic administration of this miRNA in a mouse model of NSCLC using polyethylenimine (PEI)-mediated delivery of unmodified miRNA mimics induced tumor specific apoptosis. It also effectively protected the tested animals from developing metastatic malignancy without causing any observed toxicity. The findings strongly support miR-708-5p as a novel and effective therapeutic agent against metastatic malignancy of non-small cell lung cancer.

Therapeutic Resistance in Acute Myeloid Leukemia: The Role of Non-Coding RNAs

Acute myeloid leukemia (AML) is caused by malignant transformation of hematopoietic stem or progenitor cells and displays the most frequent acute leukemia in adults. Although some patients can be cured with high dose chemotherapy and allogeneic hematopoietic stem cell transplantation, the majority still succumbs to chemoresistant disease. Micro-RNAs (miRNAs) and long non-coding RNAs (lncRNAs) are non-coding RNA fragments and act as key players in the regulation of both physiologic and pathologic gene expression profiles. Aberrant expression of various non-coding RNAs proved to be of seminal importance in the pathogenesis of AML, as well in the development of resistance to chemotherapy. In this review, we discuss the role of miRNAs and lncRNAs with respect to sensitivity and resistance to treatment regimens currently used in AML and provide an outlook on potential therapeutic targets emerging thereof.

Expression of Long Non-Coding RNA (lncRNA) Small Nucleolar RNA Host Gene 1 (SNHG1) Exacerbates Hepatocellular Carcinoma Through Suppressing miR-195

Background

Aberrant expression of lncRNA has been suggested to have an association with tumorigenesis. Our study was designed to reveal the underlying connection between lncRNA SNHG1 and hepatocellular carcinoma (HCC) pathogenesis.

Material/Methods

A total of 122 pairs of HCC tissues (case group) and matched adjacent non-tumor liver tissues (control group) were collected for this study. RT-PCR and in situ hybridization were conducted to investigate differences in lncRNA SNHG1 expression between the case and control group. The expression levels of lncRNA SNHG1 and miR-195 in HepG2 cells transfected with SNHG1-mimic and SNHG1-inhibitor were measured by RT-PCR. The proliferation, invasion, and migration status of HepG2 cells after transfection were assessed through MTT assay, wound healing assay, and Transwell assay, respectively. Whether miR-195 is a direct downstream target of lncRNA SNHG1 was verified by both bioinformatics target gene prediction and dual-luciferase report assay.

Results

The expression level of lncRNA SNHG1 was remarkably upregulated in HCC tissues and cell lines compared with normal tissues and cell lines. High expression of lncRNA SNHG1 contributed to the downregulation of miR-195 in HepG2 cells. Also, lncRNA SNHG1 exacerbated HCC cell proliferation, invasion, and migration in vitro through the inhibition of miR-195. This suggests that miR-195 is a direct downstream target of lncRNA SNHG1.

Conclusions

lncRNA SNHG1 may contribute to the aggravation of HCC through the inhibition of miR-195.

Tools for Sequence-Based miRNA Target Prediction: What to Choose?

MicroRNAs (miRNAs) are defined as small non-coding RNAs ~22 nt in length. They regulate gene expression at a post-transcriptional level through complementary base pairing with the target mRNA, leading to mRNA degradation and therefore blocking translation. In the last decade, the dysfunction of miRNAs has been related to the development and progression of many diseases. Currently, researchers need a method to identify precisely the miRNA targets, prior to applying experimental approaches that allow a better functional characterization of miRNAs in biological processes and can thus predict their effects. Computational prediction tools provide a rapid method to identify putative miRNA targets. However, since a large number of tools for the prediction of miRNA:mRNA interactions have been developed, all with different algorithms, the biological researcher sometimes does not know which is the best choice for his study and many times does not understand the bioinformatic basis of these tools. This review describes the biological fundamentals of these prediction tools, characterizes the main sequence-based algorithms, and offers some insights into their uses by biologists.

Exosomal microRNA miR-1246 induces cell motility and invasion through the regulation of DENND2D in oral squamous cell carcinoma

Metastasis is associated with poor prognosis in cancers. Exosomes, which are packed with RNA and proteins and are released in all biological fluids, are emerging as an important mediator of intercellular communication. However, the function of exosomes remains poorly understood in cancer metastasis. Here, we demonstrate that exosomes isolated by size-exclusion chromatography from a highly metastatic human oral cancer cell line, HOC313-LM, induced cell growth through the activation of ERK and AKT as well as promoted cell motility of the poorly metastatic cancer cell line HOC313-P. MicroRNA (miRNA) array analysis identified two oncogenic miRNAs, miR-342–3p and miR-1246, that were highly expressed in exosomes. These miRNAs were transferred to poorly metastatic cells by exosomes, which resulted in increased cell motility and invasive ability. Moreover, miR-1246 increased cell motility by directly targeting DENN/MADD Domain Containing 2D (DENND2D). Taken together, our findings support the metastatic role of exosomes and exosomal miRNAs, which highlights their potential for applications in miRNA-based therapeutics.

New Insights into Regulatory T Cells: Exosome- and Non-Coding RNA-Mediated Regulation of Homeostasis and Resident Treg Cells

Regulatory T (Treg) cells are a group of cells that are heterogeneous in origin and in functional activity. Treg cells comprise a necessary balance to adaptive immune responses. As key regulators of self-tolerance, Treg cells have been involved in a series of pathologic processes and considered as therapeutic targets. Here, we summarize recent research regarding Treg cell origins and their functional classification, highlight the role of exosomes and non-coding RNA in modulating Treg cell homeostasis, and discuss the current understanding of resident Treg cells.

A Review of Computational Methods for Finding Non-Coding RNA Genes

Finding non-coding RNA (ncRNA) genes has emerged over the past few years as a cutting-edge trend in bioinformatics. There are numerous computational intelligence (CI) challenges in the annotation and interpretation of ncRNAs because it requires a domain-related expert knowledge in CI techniques. Moreover, there are many classes predicted yet not experimentally verified by researchers. Recently, researchers have applied many CI methods to predict the classes of ncRNAs. However, the diverse CI approaches lack a definitive classification framework to take advantage of past studies. A few review papers have attempted to summarize CI approaches, but focused on the particular methodological viewpoints. Accordingly, in this article, we summarize in greater detail than previously available, the CI techniques for finding ncRNAs genes. We differentiate from the existing bodies of research and discuss concisely the technical merits of various techniques. Lastly, we review the limitations of ncRNA gene-finding CI methods with a point-of-view towards the development of new computational tools.

TP53/MicroRNA Interplay in Hepatocellular Carcinoma

The role of microRNAs as oncogenes and tumor suppressor genes has emerged in several cancers, including hepatocellular carcinoma (HCC). The pivotal tumor suppressive role of p53-axis is indicated by the presence of inactivating mutations in TP53 gene in nearly all cancers. A close interaction between these two players, as well as the establishment of complex p53/miRNAs loops demonstrated the strong contribution of p53-effector miRNAs in enhancing the p53-mediated tumor suppression program. On the other hand, the direct and indirect targeting of p53, as well as the regulation of its stability and activity by specific microRNAs, underlie the importance of the fine-tuning of p53 pathway, affecting the cell fate of damaged/transformed cells. The promising results of miRNAs-based therapeutic approaches in preclinical studies and their entrance in clinical trials demonstrate the feasibility of this strategy in several diseases, including cancer. Molecularly targeted drugs approved so far for HCC treatment show intrinsic or acquired resistances with disease progression in many cases, therefore the identification of effective and non-toxic agents for the treatment of HCC is actually an unmet clinical need. The knowledge of p53/miRNA inter-relations in HCC may provide useful elements for the identification of novel combined approaches in the context of the “personalized-medicine” era.

miR-155 expression and correlation with clinical outcome in pediatric AML: A report from Children's Oncology Group

BACKGROUND

Aberrant expression of microRNA-155 (miR-155) has been implicated in acute myeloid leukemia (AML) and associated with clinical outcome.

PROCEDURE

We evaluated miR-155 expression in 198 children with normal karyotype AML (NK-AML) enrolled in Children's Oncology Group (COG) AML trial AAML0531 and correlated miR-155 expression levels with disease characteristics and clinical outcome. Patients were divided into quartiles (Q1-Q4) based on miR-155 expression level, and disease characteristics were then evaluated and correlated with miR-155 expression.

RESULTS

MiR-155 expression varied over 4-log10-fold range relative to its expression in normal marrow with a median expression level of 0.825 (range 0.043-25.630) for the entire study cohort. Increasing miR-155 expression was highly associated with the presence of FLT3/ITD mutations (P < 0.001) and high-risk disease (P < 0.001) and inversely associated with standard-risk (P = 0.008) and low-risk disease (P = 0.041). Patients with highest miR-155 expression had a complete remission (CR) rate of 46% compared with 82% in low expressers (P < 0.001) with a correspondingly lower event-free (EFS) and overall survival (OS) (P < 0.001 and P = 0.002, respectively). In a multivariate model that included molecular risk factors, high miR-155 expression remained a significant independent predictor of OS (P = 0.022) and EFS (0.019).

CONCLUSIONS

High miR-155 expression is an adverse prognostic factor in pediatric NK-AML patients. Specifically, high miR-155 expression not only correlates with FLT3/ITD mutation status and high-risk disease but it is also an independent predictor of worse EFS and OS.

Combining Anti-Mir-155 with Chemotherapy for the Treatment of Lung Cancers

Purpose: The oncogenic miR-155 is upregulated in many human cancers, and its expression is increased in more aggressive and therapy-resistant tumors, but the molecular mechanisms underlying miR-155-induced therapy resistance are not fully understood. The main objectives of this study were to determine the role of miR-155 in resistance to chemotherapy and to evaluate anti-miR-155 treatment to chemosensitize tumors.Experimental Design: We performed in vitro studies on cell lines to investigate the role of miR-155 in therapy resistance. To assess the effects of miR-155 inhibition on chemoresistance, we used an in vivo orthotopic lung cancer model of athymic nude mice, which we treated with anti-miR-155 alone or in combination with chemotherapy. To analyze the association of miR-155 expression and the combination of miR-155 and TP53 expression with cancer survival, we studied 956 patients with lung cancer, chronic lymphocytic leukemia, and acute lymphoblastic leukemia.Results: We demonstrate that miR-155 induces resistance to multiple chemotherapeutic agents in vitro, and that downregulation of miR-155 successfully resensitizes tumors to chemotherapy in vivo We show that anti-miR-155-DOPC can be considered non-toxic in vivo We further demonstrate that miR-155 and TP53 are linked in a negative feedback mechanism and that a combination of high expression of miR-155 and low expression of TP53 is significantly associated with shorter survival in lung cancer.Conclusions: Our findings support the existence of an miR-155/TP53 feedback loop, which is involved in resistance to chemotherapy and which can be specifically targeted to overcome drug resistance, an important cause of cancer-related death. Clin Cancer Res; 23(11); 2891-904. ©2016 AACR.

Efficient and Stable Red Emissive Carbon Nanoparticles with a Hollow Sphere Structure for White Light-Emitting Diodes

Red-emissive solid-state carbon nanoparticles (CNPs) with a hollow sphere structure for white light-emitting diodes (WLEDs) were designed and synthesized by molecular self-assembly and microwave pyrolysis. Highly ordered graphite-like structures for CNPs were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and ultraviolet-visible (UV-vis) spectroscopy. The emission mechanism of the red-emissive solid-state CNPs was investigated in detail by steady-state and time-resolved photoluminescence (PL) spectroscopy. The as-prepared CNPs showed a red emission band centered at 620 nm with excitation wavelength independence, indicating uniform size of sp² carbon domains in the CNPs. The CNPs also had a PL quantum yield (QY) of 17% under 380 nm excitation. Significantly, the PL QY of the organosilane-functionalized CNPs was 47%, which is the highest value recorded for red-emissive solid-state carbon-based materials under UV-light excitation. More importantly, the red-emissive CNPs exhibited a PL QY of 25% after storage in air for 12 months, indicating their excellent stability. The red-emissive CNP powders were used as environmentally friendly and low-cost phosphors on a commercial 460 nm blue GaN-based chip, and a pure white light with CIE coordinates of (0.35, 0.36) was achieved. The experimental results indicated that the red-emissive CNP phosphors have potential applications in WLEDs.

Deregulated MicroRNAs in Biliary Tract Cancer: Functional Targets and Potential Biomarkers

Biliary tract cancer (BTC) is still a fatal disease with very poor prognosis. The lack of reliable biomarkers for early diagnosis and of effective therapeutic targets is a major demanding problem in diagnosis and management of BTC. Due to the clinically silent and asymptomatic characteristics of the tumor, most patients are diagnosed at an already advanced stage allowing only for a palliative therapeutic approach. MicroRNAs are small noncoding RNAs well known to regulate various cellular functions and pathologic events including the formation and progression of cancer. Over the last years, several studies have shed light on the role of microRNAs in BTC, making them potentially attractive therapeutic targets and candidates as biomarkers. In this review, we will focus on the role of oncogenic and tumor suppressor microRNAs and their direct targets in BTC. Furthermore, we summarize and discuss data that evaluate the diagnostic power of deregulated microRNAs as possible future biomarkers for BTC.

Epigenetics in liver disease: from biology to therapeutics

Knowledge of the fundamental epigenetic mechanisms governing gene expression and cellular phenotype are sufficiently advanced that novel insights into the epigenetic control of chronic liver disease are now emerging. Hepatologists are in the process of shedding light on the roles played by DNA methylation, histone/chromatin modifications and non-coding RNAs in specific liver pathologies. Alongside these discoveries are advances in the technologies for the detection and quantification of epigenetic biomarkers, either directly from patient tissue or from body fluids. The premise for this review is to survey the recent advances in the field of liver epigenetics and to explore their potential for translation by industry and clinical hepatologists for the design of novel therapeutics and diagnostic/prognostic biomarkers. In particular, we present findings in the context of hepatocellular carcinoma, fibrosis and non-alcoholic fatty liver disease, where there is urgent unmet need for new clinical interventions and biomarkers.

Mammalian microRNA: an important modulator of host-pathogen interactions in human viral infections

MicroRNAs (miRNAs), which are small non-coding RNAs expressed by almost all metazoans, have key roles in the regulation of cell differentiation, organism development and gene expression. Thousands of miRNAs regulating approximately 60 % of the total human genome have been identified. They regulate genetic expression either by direct cleavage or by translational repression of the target mRNAs recognized through partial complementary base pairing. The active and functional unit of miRNA is its complex with Argonaute proteins known as the microRNA-induced silencing complex (miRISC). De-regulated miRNA expression in the human cell may contribute to a diverse group of disorders including cancer, cardiovascular dysfunctions, liver damage, immunological dysfunction, metabolic syndromes and pathogenic infections. Current day studies have revealed that miRNAs are indeed a pivotal component of host-pathogen interactions and host immune responses toward microorganisms. miRNA is emerging as a tool for genetic study, therapeutic development and diagnosis for human pathogenic infections caused by viruses, bacteria, parasites and fungi. Many pathogens can exploit the host miRNA system for their own benefit such as surviving inside the host cell, replication, pathogenesis and bypassing some host immune barriers, while some express pathogen-encoded miRNA inside the host contributing to their replication, survival and/or latency. In this review, we discuss the role and significance of miRNA in relation to some pathogenic viruses.

BzDANP, a Small-Molecule Modulator of Pre-miR-29a Maturation by Dicer

We here report the synthesis of novel molecule BzDANP having a three-ring benzo[c][1,8]naphthyridine system, the evaluation of its binding properties to a single nucleotide bulge in RNA duplexes, and BzDANP-induced suppression of pre-miR-29a processing by Dicer. BzDANP showed much increased affinity to the bulged RNAs as compared with the parent molecule DANP, which possesses the same hydrogen-bonding surface as BzDANP but in a two-ring [1,8]naphthyridine system. Melting temperature analysis of bulged RNAs showed that BzDANP most effectively stabilized the C-bulged RNA. Dicer-mediated processing of pre-miR-29a was suppressed by BzDANP in a concentration dependent manner. The presence of the C-bulge at the Dicer cleavage site was effective for the suppression of pre-miR-29a processing by BzDANP. These results demonstrated that the small molecule binding to the bulged site in the vicinity of the Dicer cleavage site could be a potential modulator for the maturation of pre-miRNA.

In Vivo Detection of miRNA Expression in Tumors Using an Activatable Nanosensor

PURPOSE

The development of tools for the analysis of microRNA (miRNA) function in tumors can advance our diagnostic and prognostic capabilities. Here, we describe the development of technology for the profiling of miRNA expression in the tumors of live animals.

PROCEDURES

The approach is based on miRNA nanosensors consisting of sensor oligonucleotides conjugated to magnetic nanoparticles for systemic delivery. Feasibility was demonstrated for the detection of miR-10b, implicated in epithelial to mesenchymal transition and the development of metastasis. The miR-10b nanosensor was tested in vivo in two mouse models of cancer. In the first model, mice were implanted subcutaneously with MDA-MB-231-luc-D3H2LN tumors, in which miR-10b was inhibited. In the second model, mice were implanted bilaterally with metastatic MDA-MB-231 and nonmetastatic MCF-7 cells. The nanosensors were injected intravenously, and fluorescence intensity in the tumors was monitored over time.

RESULTS

We showed that the described nanosensors are capable of discriminating between tumors based on their expression of miR-10b. Radiant efficiency was higher in the miR-10b-active tumors than in the miR-10b-inhibited tumors and in the MDA-MB-231 tumors relative to the MCF-7 tumors.

CONCLUSIONS

The described technology provides an important tool that could be used to answer questions about microRNA function in cancer.

Downregulation of Foxo3 and TRIM31 by miR-551b in side population promotes cell proliferation, invasion, and drug resistance of ovarian cancer

Ovarian cancer (OVCa) stem cells are associated with tumor growth, metastasis, and recurrence, which are driving forces behind a majority of the OVCa-related mortality. This subpopulation of cancer cells are characterized by uncontrolled proliferation, high invasiveness, and resistance against the current platinum-based therapy. Thus, targeting OVCa cancer stem cells has been focused in recent therapeutic development. Isolation and purification of cancer stem cells are, however, challenging for the lack of sensitive and specific markers. In this study, we demonstrated that miR-551b was upregulated in OVCa stem cells, by using a quantitative PCR array, correlating with the pathological grades of this malignancy. In vitro experiments indicated that miR-551b promoted the proliferation, invasion, and chemoresistance of OVCa cells and cancer stem cells. Further analysis suggested that miR-551b functioned through the suppression of Foxo3 and TRIM31, two important tumor suppressors. In support of this, our in vivo experiments using mouse xenograft models showed that inhibiting miR-551b significantly increased the susceptibility of OVCa cells to cisplatin and prolonged the survival of the host mice. In conclusion, our study suggested miR-551b as a potential biomarker for OVCa stem cells and explored its functional mechanism, providing a potential therapeutic target for future drug development.

Non-coding RNA/microRNA-modulatory dietary factors and natural products for improved cancer therapy and prevention: Alkaloids, organosulfur compounds, aliphatic carboxylic acids and water-soluble vitamins

Non-coding small RNA molecules, the microRNAs (miRNAs), contribute decisively to the epigenetic regulation processes in cancer cells. Problematic pathogenic properties of cancer cells and the response of cancers towards anticancer drugs are highly influenced by miRNAs. Both increased drug activity and formation of tumor resistance are regulated by miRNAs. Further to this, the survival and proliferation of cancer cells and the formation of metastases is based on the modulated expression of certain miRNAs. In particular, drug-resistant cancer stem-like cells (CSCs) depend on the presence and absence of specific miRNAs. Fortunately, several small molecule natural compounds were discovered that target miRNAs involved in the modulation of tumor aggressiveness and drug resistance. This review gives an overview of the effects of a selection of naturally occurring small molecules (alkaloids, organosulfur compounds, aliphatic carboxylic acids and water-soluble vitamins) on miRNAs that are closely tangled with cancer diseases.

Label-Free Isothermal Amplification Assay for Specific and Highly Sensitive Colorimetric miRNA Detection

We describe a new method for the detection of miRNA in biological samples. This technology is based on the isothermal nicking enzyme amplification reaction and subsequent hybridization of the amplification product with gold nanoparticles and magnetic microparticles (barcode system) to achieve naked-eye colorimetric detection. This platform was used to detect a specific miRNA (miRNA-10b) associated with breast cancer, and attomolar sensitivity was demonstrated. The assay was validated in cell culture lysates from breast cancer cells and in serum from a mouse model of breast cancer.

Long noncoding RNA (lincRNA), a new paradigm in gene expression control

Long intergenic non-coding RNAs (lincRNAs) are defined as RNA transcripts that are longer than 200 nucleotides. By definition, these RNAs must not have open reading frames that encode proteins. Many of these transcripts are encoded by RNA polymerase II, are spliced, and are poly-adenylated. This final fact indicates that there is a trove of information about lincRNAs in databases such as the Gene Expression Omnibus (GEO), which is a repository for RNAseq and microarray data. Recent experiments indicate that there are upwards of 15,000 lincRNAs encoded by the human genome. The term "intergenic" refers to the identification of these transcripts from regions of the genome that do not contain protein-encoding genes. These regions coincide with what was once labeled as the "junk DNA" portions of our genomes, which, upon careful examination by whole genome RNA sequencing experiments, clearly encode RNA transcripts. LincRNAs also contain promoter- or enhancer-associated RNAs that are gene proximal and can be either in the sense or antisense orientation, relative to the protein-coding gene with which they are associated. In this review, we describe the functions of lincRNAs playing roles in biological processes such as gene expression control, scaffold formation, and epigenetic control.

From cell biology to immunology: Controlling metastatic progression of cancer via microRNA regulatory networks

Recently, the study of microRNAs has expanded our knowledge of the fundamental processes of cancer biology and the underlying mechanisms behind tumor metastasis. Extensive research in the fields of microRNA and its novel mechanisms of actions against various cancers has more recently led to the trial of a first cancer-targeted microRNA drug, MRX34. Yet, these microRNAs are mostly being studied and clinically trialed solely based on the understanding of their cell biologic effects, thus, neglecting the important immunologic effects that are sometimes opposite of the cell biologic effects. Here, we summarize both the cell biologic and immunologic effects of various microRNAs and discuss the importance of considering both effects before using them in clinical settings. We stress the importance of understanding the miRNA's effect on cancer metastasis from a "systems" perspective before developing a miRNA-targeted therapeutic in treating cancer metastasis.

miR-579-3p controls melanoma progression and resistance to target therapy

Therapy of melanoma patients harboring activating mutations in the BRAF (V-raf murine sarcoma viral oncogene homolog B1) oncogene with a combination of BRAF and MEK inhibitors is plagued by the development of drug resistance. Mutational events, as well as adaptive mechanisms, contribute to the development of drug resistance. In this context we uncover here the role of a miRNA, miR-579-3p. We first show that low expression of miR-579-3p is a negative prognostic factor correlating with poor survival. Expression levels of miR-579-3p decrease from nevi to stage III/IV melanoma samples and even further in cell lines resistant to BRAF/MEK inhibitors. Mechanistically, we demonstrate that miR-579-3p acts as an oncosuppressor by targeting the 3'UTR of two oncoproteins: BRAF and an E3 ubiquitin protein ligase, MDM2. Moreover miR-579-3p ectopic expression impairs the establishment of drug resistance in human melanoma cells. Finally, miR-579-3p is strongly down-regulated in matched tumor samples from patients before and after the development of resistance to targeted therapies.

Long non-coding RNA H19 regulates glioma angiogenesis and the biological behavior of glioma-associated endothelial cells by inhibiting microRNA-29a

Long non-coding RNAs (lncRNAs) play crucial roles in the development and progression of glioma. Previous studies indicated that lncRNA H19 regulated tumor carcinogenesis, angiogenesis and metastasis. This study aimed to investigate its functional role in glioma-induced endothelial cell proliferation, migration and tube formation as well as its possible molecular mechanisms. H19 was up-regulated in microvessels from glioma tissues and glioma-associated endothelial cells (GEC) cultured in glioma conditioned medium. Knockdown of H19 suppressed glioma-induced endothelial cell proliferation, migration and tube formation in vitro and meanwhile up-regulated the expression of miR-29a. Bioinformatics analysis and luciferase reporter assay defined that H19 mediated the above effects via directly binding to miR-29a. In addition, miR-29a targeted 3'-UTR region of vasohibin 2 (VASH2) and decreased its expression. VASH2 has been identified as an angiogenic factor. Knockdown of H19 also decreased the VASH2 expression by up-regulating miR-29a. In conclusion, the results indicated that knockdown of H19 suppressed glioma induced angiogenesis by inhibiting microRNA-29a, which may modulate the onset of glioma by regulating biological behaviors of glioma vascular endothelial cells.

MiR-625-3p promotes cell migration and invasion via inhibition of SCAI in colorectal carcinoma cells

MicroRNAs (miRNAs) play a critical role in controlling tumor invasion and metastasis via regulating the expression of a variety of targets, which act as oncogenes or tumor suppressor genes. Abnormally expressed miR-625-3p has been observed in several types of human cancers. However, the molecular mechanisms of miR-625-3p-mediated tumorigenesis are largely elusive. Therefore, the aim of this study was to evaluate the biological function and molecular insight on miR-625-3p-induced oncogenesis in colorectal carcinoma (CRC). The effects of miR-625-3p in cell migration and invasion were analyzed by wound healing assay and transwell assay, respectively. In addition, the expression of miR-625-3p and its targets was detected in five human CRC cell lines. In the present study, we found that overexpression of miR-625-3p promoted migration and invasion in SW480 cells, whereas downregulation of miR-625-3p inhibited cell motility in SW620 cells. More importantly, we observed potential binding sites for miR-625-3p in the 3′-untranslated region of suppressor of cancer cell invasion (SCAI). Notably, we identified that overexpression of miR-625-3p inhibited the expression of SCAI, while depletion of miR-625-3p increased SCAI level, suggesting that SCAI could be a target of miR-625-3p. Additionally, we revealed that miR-625-3p exerts its oncogenic functions through regulation of SCAI/E-cadherin/MMP-9 pathways. Our findings indicate the pivotal role of miR-625-3p in invasion that warrants further exploration whether targeting miR-625-3p could be a promising approach for the treatment of CRC.

Long non-coding RNA AOC4P suppresses hepatocellular carcinoma metastasis by enhancing vimentin degradation and inhibiting epithelial-mesenchymal transition

Increasing evidence indicates that long non-coding RNAs (lncRNAs) regulate diverse cellular processes, including cell growth, differentiation, apoptosis, and cancer progression. However, the function of lncRNAs in the progression of hepatocellular carcinoma (HCC) remains largely unknown. We performed a comprehensive microarray analysis of lncRNA expression in human HCC samples. After validation in 108 HCC specimens, we identified a differentially expressed novel tumor suppressive lncRNA termed amine oxidase, copper containing 4, pseudogene (AOC4P). The level of AOC4P expression was significantly downregulated in 68% of HCC samples and negatively correlated with advanced clinical stage, capsule invasion and vessel invasion. Low AOC4P expression correlated with poor prognostic outcomes, serving as an independent prognostic factor for HCC. In vitro functional assays indicated that AOC4P overexpression significantly reduced cell proliferation, migration and invasion by inhibiting the epithelial-mesenchymal transition (EMT). RNA immunoprecipitation assays demonstrated that AOC4P binds to vimentin and promotes its degradation. Animal model experiments confirmed the ability of AOC4P to suppress tumor growth and metastasis. Taken together, our findings suggest that AOC4P lncRNA acts as an HCC tumor suppressor by enhancing vimentin degradation and suppressing the EMT. By clarifying the mechanisms underlying HCC progression, these findings promote the development of novel therapeutic strategies for HCC.

Pre-administration of PepFect6-microRNA-146a nanocomplexes inhibits inflammatory responses in keratinocytes and in a mouse model of irritant contact dermatitis

The skin is a difficult to access tissue for efficient delivery of large and/or charged macromolecules, including therapeutic DNA and RNA oligonucleotides. Cell-penetrating peptide PepFect6 (PF6) has been shown to be suitable transport vehicle for siRNAs in cell culture and systemically in vivo in mice. MiR-146a is known as anti-inflammatory miRNA that inhibits multiple factors from the nuclear factor (NF)-κB pathway in various cell types, including keratinocytes. In this study, PF6 was shown to form unimodal nanocomplexes with miR-146a mimic that entered into human primary keratinocytes, where miR-146a inhibited the expression of its direct targets from the NF-κB pathway and the genes known to be activated by NF-κB, C-C motif ligand (CCL)5 and interleukin (IL)-8. The transfection of miR-146a mimic with PF6 was more efficient in sub-confluent keratinocyte cultures, affected keratinocyte proliferation less and had similar effect on cell viability when compared with a lipid based agent. Subcutaneous pre-administration of PF6-miR-146a nanocomplexes attenuated ear-swelling and reduced the expression of pro-inflammatory cytokines and chemokines IL-6, CCL11, CCL24 and C-X-C motif ligand 1 (CXCL1) in a mouse model of irritant contact dermatitis. Our data demonstrates that PF6-miR-146a nanoparticles might have potential in the development of therapeutics to target inflammatory skin diseases.

MicroRNA and Metastasis

Noncoding RNAs are important regulatory molecules of cellular processes. MicroRNAs (miRNAs) are small noncoding RNAs that bind to complementary sequences in the 3' untranslated region of target mRNAs, leading to degradation of the target mRNAs and/or inhibition of their translation. Some miRNAs are essential for normal animal development; however, many other miRNAs are dispensable for development but play a critical role in pathological conditions, including tumorigenesis and metastasis. miRNA genes often reside at fragile chromosome sites and are deregulated in cancer. Some miRNAs function as oncogenes or tumor suppressors, collectively termed "oncomirs." Specific metastasis-regulating miRNAs, collectively termed "metastamirs," govern molecular processes and pathways in malignant progression in either a tumor cell-autonomous or a cell-nonautonomous manner. Recently, exosome-transferred miRNAs have emerged as mediators of the tumor-stroma cross talk. In this chapter, we focus on the functions, mechanisms of action, and therapeutic potential of miRNAs, particularly oncomirs and metastamirs.

Immunomodulation of hematological malignancies using oligonucleotides based-nanomedicines

Hematological malignancies are a group of diseases characterized by clonal proliferation of blood-forming cells. Malignant blood cells are classified as myeloid or lymphoid cells depending on their stem cell origin. Lymphoid malignancies are characterized by lymphocyte accumulation in the blood stream, in the bone marrow, or in lymphatic nodes and organs. Several of these diseases are associated with chromosomal translocations, which cause gene fusion and amplification of expression, while others are characterized with aberrant expression of oncogenes. Overall, these genes play a major role in development and maintenance of malignant clones. The discovery of antisense oligonucleotides and RNA interference (RNAi) mechanisms offer new tools to specifically manipulate gene expression. Systemic delivery of inhibitory oligonucleotides molecules for manipulation of gene expression in lymphocytes holds a great potential for facilitating the development of an oligonucleotides -based therapy platform for lymphoid blood cancer. However, lymphocytes are among the most difficult targets for oligonucleotides delivery, as they are resistant to conventional transfection reagents and are dispersed throughout the body, making it difficult to successfully localize or deliver oligonucleotides payloads via systemic administration. In this review, we will survey the latest progress in the field of oligonucleotides based nanomedicine in the heterogeneous group of hematological malignancies with special emphasis on RNA based strategies. We will describe the most advanced non-viral nanocarriers for RNA delivery to malignant blood cells. We will also discuss targeted strategies for cell specific delivery of RNA molecules using nanoparticles and the therapeutic benefit of manipulating gene function in hematological malignancies. Finally, we will focus on the ex vivo, in vivo, and clinical trial strategies, that are currently under development in hematological malignancies - strategies that might increase the arsenal of drugs available to hematologists in the upcoming years.

microRNAs with AAGUGC seed motif constitute an integral part of an oncogenic signaling network

microRNA (miRNA) dysregulation is a common feature of cancer cells, but the complex roles of miRNAs in cancer are not fully elucidated. Here, we used functional genomics to identify oncogenic miRNAs in non-small cell lung cancer and evaluate their impact on response to epidermal growth factor (EGFR)-targeting therapy. Our data demonstrate that miRNAs with an AAGUGC motif in their seed sequence increase both cancer cell proliferation and sensitivity to EGFR inhibitors. Global transcriptomics, proteomics and target prediction resulted in the identification of several tumor suppressors involved in the G1/S transition as AAGUGC-miRNA targets. The clinical implications of our findings were evaluated by analysis of AAGUGC-miRNA expression in multiple cancer types, supporting the link between this miRNA seed family, their tumor suppressor targets and cancer cell proliferation. In conclusion, we propose the AAGUGC seed motif as an oncomotif and that oncomotif-miRNAs promote cancer cell proliferation. These findings have potential therapeutic implications, especially in selecting patients for EGFR-targeting therapy.

Evidence for the role of microRNA 374b in acquired cisplatin resistance in pancreatic cancer cells

Recent evidence has implicated microRNAs (miRNAs) as potentially significant players in the acquisition of cancer-drug resistance in pancreatic and other cancers. To evaluate the potential contribution of miRNAs in acquired resistance to cisplatin in pancreatic cancer, we compared levels of more than 2000 human miRNAs in a cisplatin-resistant cell line (BxPC3-R) derived from parental (BxPC3) cells by step-wise exposure to increasing concentrations of the drug over more than 20 passages. The acquired drug resistance was accompanied by significant changes in the expression of 57 miRNAs, of which 23 were downregulated and 34 were upregulated. Employing a hidden Markov model (HMM) algorithm, we identified downregulation of miR-374b as likely being directly involved in acquisition of the drug-resistant phenotype. Consistent with this prediction, ectopic overexpression of miR-374b in the resistant BxPC3-R cells restored cisplatin sensitivity to levels approaching those displayed by the BxPC3 parental cells. The results are consistent with a growing body of evidence implicating miRNAs in acquired cancer-drug resistance and with the potential therapeutic value of these small regulatory RNAs in blocking and/or reversing the process.

Current state of phenolic and terpenoidal dietary factors and natural products as non-coding RNA/microRNA modulators for improved cancer therapy and prevention

The epigenetic regulation of cancer cells by small non-coding RNA molecules, the microRNAs (miRNAs), has raised particular interest in the field of oncology. These miRNAs play crucial roles concerning pathogenic properties of cancer cells and the sensitivity of cancer cells towards anticancer drugs. Certain miRNAs are responsible for an enhanced activity of drugs, while others lead to the formation of tumor resistance. In addition, miRNAs regulate survival and proliferation of cancer cells, in particular of cancer stem-like cells (CSCs), that are especially drug-resistant and, thus, cause tumor relapse in many cases. Various small molecule compounds were discovered that target miRNAs that are known to modulate tumor aggressiveness and drug resistance. This review comprises the effects of naturally occurring small molecules (phenolic compounds and terpenoids) on miRNAs involved in cancer diseases.

Long Noncoding RNAs in Lung Cancer

Despite great progress in research and treatment options, lung cancer remains the leading cause of cancer-related deaths worldwide. Oncogenic driver mutations in protein-encoding genes were defined and allow for personalized therapies based on genetic diagnoses. Nonetheless, diagnosis of lung cancer mostly occurs at late stages, and chronic treatment is followed by a fast onset of chemoresistance. Hence, there is an urgent need for reliable biomarkers and alternative treatment options. With the era of whole genome and transcriptome sequencing technologies, long noncoding RNAs emerged as a novel class of versatile, functional RNA molecules. Although for most of them the mechanism of action remains to be defined, accumulating evidence confirms their involvement in various aspects of lung tumorigenesis. They are functional on the epigenetic, transcriptional, and posttranscriptional level and are regulators of pathophysiological key pathways including cell growth, apoptosis, and metastasis. Long noncoding RNAs are gaining increasing attention as potential biomarkers and a novel class of druggable molecules. It has become clear that we are only beginning to understand the complexity of tumorigenic processes. The clinical integration of long noncoding RNAs in terms of prognostic and predictive biomarker signatures and additional cancer targets could provide a chance to increase the therapeutic benefit. Here, we review the current knowledge about the expression, regulation, biological function, and clinical relevance of long noncoding RNAs in lung cancer.

Pancreatic Cancer Cell Exosome-Mediated Macrophage Reprogramming and the Role of MicroRNAs 155 and 125b2 Transfection using Nanoparticle Delivery Systems

Exosomes are nano-sized endosome-derived small intraluminal vesicles, which are important facilitators of intercellular communication by transporting contents, such as protein, mRNA, and microRNAs, between neighboring cells, such as in the tumor microenvironment. The purpose of this study was to understand the mechanisms of exosomes-mediated cellular communication between human pancreatic cancer (Panc-1) cells and macrophages (J771.A1) using a Transwell co-culture system. Following characterization of exosome-mediated cellular communication and pro-tumoral baseline M2 macrophage polarization, the Panc-1 cells were transfected with microRNA-155 (miR-155) and microRNA-125b-2 (miR-125b2) expressing plasmid DNA using hyaluronic acid-poly(ethylene imine)/hyaluronic acid-poly(ethylene glycol) (HA-PEI/HA-PEG) self-assembling nanoparticle-based non-viral vectors. Our results show that upon successful transfection of Panc-1 cells, the exosome content was altered leading to differential communication and reprogramming of the J774.A1 cells to an M1 phenotype. Based on these results, genetic therapies targeted towards selective manipulation of tumor cell-derived exosome content may be very promising for cancer therapy.

MicroRNAs and psychiatric disorders: From aetiology to treatment

The emergence of psychiatric disorders relies on the interaction between genetic vulnerability and environmental adversities. Several studies have demonstrated a crucial role for epigenetics (e.g. DNA methylation, post-translational histone modifications and microRNA-mediated post-transcriptional regulation) in the translation of environmental cues into adult behavioural outcome, which can prove to be harmful thus increasing the risk to develop psychopathology. Within this frame, non-coding RNAs, especially microRNAs, came to light as pivotal regulators of many biological processes occurring in the Central Nervous System, both during the neuronal development as well as in the regulation of adult function, including learning, memory and neuronal plasticity. On these basis, in recent years it has been hypothesised a central role for microRNA modulation and expression regulation in many brain disorders, including neurodegenerative disorders and mental illnesses. Indeed, the aim of the present review is to present the most recent state of the art regarding microRNA involvement in psychiatric disorders. We will first describe the mechanisms that regulate microRNA biogenesis and we will report evidences of microRNA dysregulation in peripheral body fluids, in postmortem brain tissues from patients suffering from psychopathology as well as in animal models. Last, we will discuss the potential to consider microRNAs as putative target for pharmacological intervention, using common psychotropic drugs or more specific tools, with the aim to normalize functions that are disrupted in different psychiatric conditions.

microRNA-7 regulates cell growth, migration and invasion via direct targeting of PAK1 in thyroid cancer

The expression and function of microRNA-7 (miR-7) has been studied in a variety of different cancer types. However, to date, no studies have investigated the expression of miR‑7 in human thyroid cancer. In the present study, the expression levels and biological function of miR‑7 were investigated in human thyroid cancer, with the aim of evaluating whether it may serve as a therapeutic biomarker. The expression levels of miR‑7 in human thyroid cancer tissues, matched, adjacent normal tissues, normal thyroid tissues and human thyroid cancer cell lines were determined using RT‑qPCR and western blot analysis. To explore the functional role of miR‑7 in human thyroid cancer cell lines, MTT assays, cell migration and invasion assays were employed. TargetScan software identified p21 activated kinase‑1 (PAK1) as a putative interacting partner of miR‑7. Therefore, functional assays were performed to explore the effects of endogenous PAK1 in thyroid cancer. In the present study, miR‑7 was significantly downregulated in thyroid cancer tissues and cells compared with normal thyroid tissue samples. A correlation between miR‑7 expression and thyroid tumor stage was also observed. Ectopic expression of miR‑7 was found to suppress the proliferation, migra-tion and invasion of thyroid cancer cells in vitro. Dual-luciferase reporter assays demonstrated that PAK1 was a direct target of miR-7 in vitro. RT-qPCR and western blot analysis demonstrated that miR‑7 negatively regulates PAK1 protein expression but has no effect on PAK1 mRNA expression. Knockdown of PAK1 expression markedly suppressed thyroid cancer cell proliferation, migration and invasion. These results suggest that miR‑7 functions as a tumor suppressor by targeting PAK1 directly and may therefore present a novel therapeutic target for the treatment of thyroid cancer.

Direct Comparison of Metastasis-Related miRNAs Expression Levels in Circulating Tumor Cells, Corresponding Plasma, and Primary Tumors of Breast Cancer Patients

BACKGROUND

Circulating tumor cells (CTCs) and microRNAs (miRNAs) are important in liquid biopsies in which peripheral blood is used to characterize the evolution of solid tumors. We evaluated the expression levels of miR-21, miR-146a, miR-200c, and miR-210 in CTCs of breast cancer patients with verified metastasis and compared their expression levels in corresponding plasma and primary tumors.

METHODS

Expression levels of the miRNAs were quantified by quantitative reverse transcription PCR (RT-qPCR) in (a) 89 primary breast tumors and 30 noncancerous breast tissues and (b) CTCs and corresponding plasma of 55 patients with metastatic breast cancer and 20 healthy donors. For 30 of these patients, CTCs, corresponding plasma, and primary tumor tissues were available.

RESULTS

In formalin-fixed, paraffin-embedded tissues, these miRNAs were differentially expressed between primary breast tumors and noncancerous breast tissues. miR-21 (P &lt; 0.001) and miR-146a (P = 0.001) were overexpressed, whereas miR-200c (P = 0.004) and miR-210 (P = 0.002) were underexpressed. In multivariate analysis, miR-146a overexpression was significantly [hazard ratio 2.969 (1.231–7.157), P = 0.015] associated with progression-free survival. In peripheral blood, all miRNAs studied were overexpressed in both CTC and corresponding plasma. There was a significant association between miR-21 expression levels in CTCs and plasma for 36 of 55 samples (P = 0.008). In plasma, ROC curve analysis revealed that miR-21, miR-146a, and miR-210 could discriminate patients from healthy individuals.

CONCLUSIONS

Metastasis-related miRNAs are overexpressed in CTCs and corresponding plasma; miR-21 expression levels highly correlate in CTCs and plasma; and miR-21, miR-146a, and miR-210 are valuable plasma biomarkers for discriminating patients from healthy individuals.

miRNA-205 targets VEGFA and FGF2 and regulates resistance to chemotherapeutics in breast cancer

MicroRNAs (miRNAs) have critical roles in regulating cancer cell survival, proliferation and sensitivity to chemotherapy. The potential application of using miRNAs to predict chemotherapeutic response to cancer treatment is highly promising. However, the underlying mechanisms of chemotherapy response control by miRNAs remain to be fully identified and their prognostic value has not been fully evaluated. Here we show a strong correlation between miR-205 expression and chemosensitivtiy to TAC (docetaxol, doxorubicin plus cyclophosphamide), a widely-used neoadjuvant chemotherapy (NAC) regimen, for breast cancer patients. High level of miR-205 predicted better response to TAC regimen NAC in breast cancer patients. We found miR-205 downregulated in both MCF-7/A02 and CALDOX cells, two drug-resistant derivatives of MCF-7 and Cal51 cells, and its ectopic expression led to an increase in apoptosis resensitization of both drug-resistant cell lines to doxorubicin and taxol. We further show that miR-205 directly binds VEGFA and FGF2 mRNA 3′-UTRs and confirm that miR-205 levels are negatively correlated with VEGFA and FGF2 mRNA expression in breast cancer patients. Adding VEGFA and FGF2 exogenously to chemosensitive breast cancer cells and chemoresistant cells with miR-205 overexpression led to drug resistance. Consistently, low VEGFA and FGF2 expression correlated with better response to NAC in breast cancer patients. In addition, inhibition of tumor growth and resensitization to doxorubicin were also observed in mouse tumor xenografts from cells overexpressing miR-205. Taken together, our data suggest that miR-205 enhances chemosensitivity of breast cancer cells to TAC chemotherapy by suppressing both VEGFA and FGF2, leading to evasion of apoptosis. MiR-205 may serve as a predictive biomarker and a potential therapeutic target in breast cancer treatment.

Identifying circulating microRNAs as biomarkers of cardiovascular disease: a systematic review

The aim of the present study is to identify microRNAs (miRs) with high potential to be used as biomarkers in plasma and/or serum to clinically diagnose, or provide accurate prognosis for survival in, patients with atherosclerosis, coronary artery disease, and acute coronary syndrome (ACS). A systematic search of published original research yielded a total of 72 studies. After review of the risk of bias of the published studies, according to Cochrane Collaboration and the QUADUAS Group standards, 19 studies were selected. Overall 52 different miRs were reported. In particular, miR-133a/b (5 studies), miR-208a/b (6 studies), and miR-499 (7 studies) were well studied and found to be significant diagnostic and/or prognostic markers across different cardiovascular disease progression stages. miR-1 and miR-145b are potential biomarkers of ACS; miR-1 with higher sensitivity for all acute myocardial infarction (AMI), and miR-145 for STEMI and worse outcome of AMI. But when miRs were studied across different ACS study populations, patients had varying degrees of coronary stenosis, which was identified as an important confounder that limited the ability to quantitatively pool the study results. The identified miRs were found to regulate endothelial function and angiogenesis (miR-1, miR-133), vascular smooth muscle cell differentiation (miR-133, miR-145), communication between vascular smooth muscle and endothelial cell to stabilize plaques (miR-145), apoptosis (miR-1, miR-133, miR-499), cardiac myocyte differentiation (miR-1, miR-133, miR-145, miR-208, miR-499), and to repress cardiac hypertrophy (miR-133). Their role in these processes may be explained by regulation of shared RNA targets such as cyclin-dependent kinase inhibitor 1A (or p21), ETS proto-oncogene 1, fascin actin-bundling protein 1, hyperpolarization-activated cyclic nucleotide-gated potassium channel 4, insulin-like growth factor 1 receptor LIM and SH3 protein 1, purine nucleoside phosphorylase, and transgelin 2. These mechanistic data further support the clinical relevance of the identified miRs. miR-1, miR-133a/b, miR-145, miR-208a/b, and miR-499(a) in plasma and/or serum show some potential for diagnosis of cardiovascular disease. However, biased selection of miRs in most studies and unexplained contrasting results are major limitations of current miR research. Inconsistencies need to be addressed in order to definitively identify clinically useful miRs. Therefore, this paper presents important aspects to improve future miR research, including unbiased selection of miRs, standardization/normalization of reference miRs, adjustment for patient comorbidities and medication, and robust protocols of data-sharing plans that could prevent selective publication and selective reporting of miR research outcomes.

miR-93 regulates Msk2-mediated chromatin remodelling in diabetic nephropathy

How the kidney responds to the metabolic cues from the environment remains a central question in kidney research. This question is particularly relevant to the pathogenesis of diabetic nephropathy (DN) in which evidence suggests that metabolic events in podocytes regulate chromatin structure. Here, we show that miR-93 is a critical metabolic/epigenetic switch in the diabetic milieu linking the metabolic state to chromatin remodelling. Mice with inducible overexpression of a miR-93 transgene exclusively in podocytes exhibit significant improvements in key features of DN. We identify miR-93 as a regulator of nucleosomal dynamics in podocytes. miR-93 has a critical role in chromatin reorganization and progression of DN by modulating its target Msk2, a histone kinase, and its substrate H3S10. These findings implicate a central role for miR-93 in high glucose-induced chromatin remodelling in the kidney, and provide evidence for a previously unrecognized role for Msk2 as a target for DN therapy.

Podocyte injury is central to kidney dysfunction in diabetic nephropathy. Here the authors show that Msk2 is a target of miR-93 and this interaction mediates pathogenic chromatin remodelling in diabetic nephropathy.

DDX3 Represses Stemness by Epigenetically Modulating Tumor-suppressive miRNAs in Hepatocellular Carcinoma

Studies indicate that the presence of cancer stem cells (CSCs) is responsible for poor prognosis of hepatocellular carcinoma (HCC) patients. In this study, the functional role of DDX3 in regulation of hepatic CSCs was investigated. Our results demonstrated that reduced DDX3 expression was not only inversely associated with tumor grade, but also predicted poor prognosis of HCC patients. Knockdown of DDX3 in HCC cell line HepG2 induced stemness gene signature followed by occurrence of self-renewal, chemoreisistance, EMT, migration as well as CSC expansion, and most importantly, DDX3 knockdown promotes tumorigenesis. Moreover, we found positive correlations between DDX3 level and expressions of tumor-suppressive miR-200b, miR-200c, miR-122 and miR-145, but not miR-10b and miR-519a, implying their involvement in DDX3 knockdown-induced CSC phenotypes. In addition, DDX3 reduction promoted up-regulation of DNA methyltransferase 3A (DNMT3A), while neither DNMT3B nor DNMT1 expression was affected. Enriched DNMT3A binding along with hypermethylation on promoters of these tumor-suppressive miRNAs reflected their transcriptional repressions in DDX3-knockdown cells. Furthermore, individual restoration of these tumor-suppressive miRNAs represses DDX3 knockdown-induced CSC phenotypes. In conclusion, our study suggested that DDX3 prevents generation of CSCs through epigenetically regulating a subset of tumor-suppressive miRNAs expressions, which strengthens tumor suppressor role of DDX3 in HCC.

MicroRNA‑335 inhibits bladder cancer cell growth and migration by targeting mitogen‑activated protein kinase 1

The abnormal expression of microRNAs (miRs) as oncogenes or tumor‑suppressor genes has been widely investigated in various tumor types. However, the roles of miR‑335 in bladder cancer cells have remained elusive. The aim of the present study was to assess the expression of miR‑335 in bladder cancer as well as the effects of miR‑335 on bladder cancer cell proliferation, metastasis and apoptosis. PCR and western blot analyses revealed that miR‑335 was significantly downregulated in bladder cancer tissues, and low levels of miR‑335 were associated with more aggressive phenotypes of bladder cancer. Overexpression of miR‑335 in T24 cells inhibited cell proliferation and induced apoptosis as indicated by an MTT assay and flow cytometric analysis, respectively. Furthermore, overexpression of miR‑335 significantly suppressed cell migration, as indicated by a Transwell assay. The expression of mitogen‑activated protein kinase (MAPK)1 was decreased after overexpression of miR‑335, indicating that MAPK1 may be a target gene of miR‑335. In addition, silencing of MAPK1 inhibited the proliferation and migration of bladder cancer cells. In conclusion, the results of the present study demonstrated that miR‑335 was significantly downregulated in bladder cancer, and may act as a tumor suppressor through repression of MAPK1.