Targeting Notch signalling by the conserved miR-8/200 microRNA family in development and cancer cells

Polycomb-mediated silencing of miR-8 is required for maintenance of intestinal stemness in Drosophila melanogaster

Balancing maintenance of self-renewal and differentiation is a key property of adult stem cells. The epigenetic mechanisms controlling this balance remain largely unknown. Herein, we report that the Polycomb Repressive Complex 2 (PRC2) is required for maintenance of the intestinal stem cell (ISC) pool in the adult female Drosophila melanogaster. We show that loss of PRC2 activity in ISCs by RNAi-mediated knockdown or genetic ablation of the enzymatic subunit Enhancer of zeste, E(z), results in loss of stemness and precocious differentiation of enteroblasts to enterocytes. Mechanistically, we have identified the microRNA miR-8 as a critical target of E(z)/PRC2-mediated tri-methylation of histone H3 at Lys27 (H3K27me3) and uncovered a dynamic relationship between E(z), miR-8 and Notch signaling in controlling stemness versus differentiation of ISCs. Collectively, these findings uncover a hitherto unrecognized epigenetic layer in the regulation of stem cell specification that safeguards intestinal homeostasis.

Identifications of three novel alleles of Serrate in Drosophila

The Notch signaling pathway, an evolutionarily highly conserved pathway, participates in various essential physiological processes in organisms. Activation of Notch signaling in the canonical manner requires the combination of ligand and receptor. There are two ligands of Notch in Drosophila: Delta (Dl) and Serrate (Ser). A mutation mf157 is identified for causing nicks of fly wings in genetic analysis from a mutant library (unpublished) that was established previously. Immunofluorescent staining illustrates that mf157 represses the expression of Cut and Wingless (Wg), the targets of Notch signaling. MARCM cloning analysis reveals that mf157 functions at the same level or the upstream of ligands of Notch in signaling sending cells. Sequencing demonstrates that mf157 is a novel allele of the Ser gene. Subsequently, mf553 and mf167 are also identified as new alleles of Ser from our library. Furthermore, the complementary assays and the examination of transcripts confirm the sequencing results. Besides, the repressed phenotypes of Notch signaling were reverted by transposon excision experiments of mf157. In conclusion, we identify three fresh alleles of Ser. Our works supply additional genetic resources for further study of functions of Ser and Notch signaling regulation.

Representation of non-coding RNA-mediated regulation of gene expression using the Gene Ontology

Regulatory non-coding RNAs (ncRNAs) are increasingly recognized as integral to the control of biological processes. This is often through the targeted regulation of mRNA expression, but this is by no means the only mechanism through which regulatory ncRNAs act. The Gene Ontology (GO) has long been used for the systematic annotation of protein-coding and ncRNA gene function, but rapid progress in the understanding of ncRNAs meant that the ontology needed to be revised to accurately reflect current knowledge. Here, a targeted effort to revise GO terms used for the annotation of regulatory ncRNAs is described, focusing on microRNAs (miRNAs), long non-coding RNAs (lncRNAs), small interfering RNAs (siRNAs) and PIWI-interacting RNAs (piRNAs). This paper provides guidance to biocurators annotating ncRNA-mediated processes using the GO and serves as background for researchers wishing to make use of the GO in their studies of ncRNAs and the biological processes they regulate.

MicroRNA miR-252-5p regulates the Notch signaling pathway by targeting Rab6 in Drosophila wing development

The Notch signaling pathway plays a central role in the development of various organisms. However, dysregulation of microRNAs (miRNAs), which are crucial regulators of gene expression, can disrupt signaling pathways at all stages of development. Although Notch signaling is involved in wing development in Drosophila, the mechanism underlying miRNA-based regulation of the Notch signaling pathway is unclear. Here, we report that loss of Drosophila miR-252 increases the size of adult wings, whereas the overexpression of miR-252 in specific compartments of larval wing discs leads to patterning defects in the adult wings. The miR-252 overexpression-induced wing phenotypes were caused by aberrant Notch signaling with intracellular accumulation of the full-length Notch receptor during development, which could be due to defects in intracellular Notch trafficking associated with its recycling to the plasma membrane and autophagy-mediated degradation. Moreover, we identified Rab6 as a direct target of miR-252-5p; Rab6 encodes a small Ras-like GTPase that regulates endosomal trafficking pathways. Consistent with this finding, RNAi-mediated downregulation of Rab6 led to similar defects in both wing patterning and Notch signaling. Notably, co-overexpression of Rab6 completely rescued the wing phenotype associated with miR-252 overexpression, further supporting that Rab6 is a biologically relevant target of miR-252-5p in the context of wing development. Thus, our data indicate that the miR-252-5p-Rab6 regulatory axis is involved in Drosophila wing development by controlling the Notch signaling pathway.

Identification and Characterization of Development-Related microRNAs in the Red Flour Beetle, Tribolium castaneum

MicroRNAs (miRNAs) play important roles in insect growth and development, but they were poorly studied in insects. In this study, a total of 883 miRNAs were detected from the early embryo (EE), late larva (LL), early pupa (EP), late pupa (LP), and early adult (EA) of Tribolium castaneum by microarray assay. Further analysis identified 179 differentially expressed unique miRNAs (DEmiRNAs) during these developmental stages. Of the DEmiRNAs, 102 DEmiRNAs exhibited stage-specific expression patterns during development, including 53 specifically highly expressed miRNAs and 20 lowly expressed miRNAs in EE, 19 highly expressed miRNAs in LL, 5 weakly expressed miRNAs in EP, and 5 abundantly expressed miRNAs in EA. These miRNAs were predicted to target 747, 265, 472, 234, and 121 genes, respectively. GO enrichment analysis indicates that the targets were enriched by protein phosphorylation, calcium ion binding, sequence-specific DNA binding transcription factor activity, and cytoplasm. An RNA interference-mediated knockdown of the DEmiRNAs tca-miR-6-3p, tca-miR-9a-3p, tca-miR-9d-3p, tca-miR-11-3p, and tca-miR-13a-3p led to defects in metamorphosis and wing development of T. castaneum. This study has completed the identification and characterization of development-related miRNAs in T. castaneum, and will enable us to investigate their roles in the growth and development of insect.

Plasmid encoding miRNA-200c delivered by CaCO3-based nanoparticles enhances rat alveolar bone formation

Aim: miRNAs have been shown to improve the restoration of craniofacial bone defects. This work aimed to enhance transfection efficiency and miR-200c-induced bone formation in alveolar bone defects via plasmid DNA encoding miR-200c delivery from CaCO₃ nanoparticles. Materials & methods: The CaCO₃/miR-200c delivery system was evaluated in vitro (microscopy, transfection efficiency, biocompatibility) and miR-200c-induced in vivo alveolar bone formation was assessed via micro-computed tomography and histology. Results: CaCO₃ nanoparticles significantly enhanced the transfection of plasmid DNA encoding miR-200c without inflammatory effects and sustained miR-200c expression. CaCO₃/miR-200c treatment in vivo significantly increased bone formation in rat alveolar bone defects. Conclusion: CaCO₃ nanoparticles enhance miR-200c delivery to accelerate alveolar bone formation, thereby demonstrating the application of CaCO₃/miR-200c to craniofacial bone defects.

Regulation of stem cell identity by miR-200a during spinal cord regeneration

Axolotls are an important model organism for multiple types of regeneration, including functional spinal cord regeneration. Remarkably, axolotls can repair their spinal cord after a small lesion injury and can also regenerate their entire tail following amputation. Several classical signaling pathways that are used during development are reactivated during regeneration, but how this is regulated remains a mystery. We have previously identified miR-200a as a key factor that promotes successful spinal cord regeneration. Here, using RNA-seq analysis, we discovered that the inhibition of miR-200a results in an upregulation of the classical mesodermal marker brachyury in spinal cord cells after injury. However, these cells still express the neural stem cell marker sox2. In vivo cell tracking allowed us to determine that these cells can give rise to cells of both the neural and mesoderm lineage. Additionally, we found that miR-200a can directly regulate brachyury via a seed sequence in the 3′UTR of the gene. Our data indicate that miR-200a represses mesodermal cell fate after a small lesion injury in the spinal cord when only glial cells and neurons need to be replaced.

Summary: Axolotl spinal cord cells have the potential to form cells of the ectoderm and mesoderm depending on the extent of the injury they are responding to.

Nanoparticle-Based RNAi Therapeutics Targeting Cancer Stem Cells: Update and Prospective

Cancer stem cells (CSCs) are characterized by intrinsic self-renewal and tumorigenic properties, and play important roles in tumor initiation, progression, and resistance to diverse forms of anticancer therapy. Accordingly, targeting signaling pathways that are critical for CSC maintenance and biofunctions, including the Wnt, Notch, Hippo, and Hedgehog signaling cascades, remains a promising therapeutic strategy in multiple cancer types. Furthermore, advances in various cancer omics approaches have largely increased our knowledge of the molecular basis of CSCs, and provided numerous novel targets for anticancer therapy. However, the majority of recently identified targets remain ‘undruggable’ through small-molecule agents, whereas the implications of exogenous RNA interference (RNAi, including siRNA and miRNA) may make it possible to translate our knowledge into therapeutics in a timely manner. With the recent advances of nanomedicine, in vivo delivery of RNAi using elaborate nanoparticles can potently overcome the intrinsic limitations of RNAi alone, as it is rapidly degraded and has unpredictable off-target side effects. Herein, we present an update on the development of RNAi-delivering nanoplatforms in CSC-targeted anticancer therapy and discuss their potential implications in clinical trials.

Rat Calvarial Bone Regeneration by 3D-Printed β-Tricalcium Phosphate Incorporating MicroRNA-200c

Advanced fabrication methods for bone grafts designed to match defect sites that combine biodegradable, osteoconductive materials with potent, osteoinductive biologics would significantly impact the clinical treatment of large bone defects. In this study, we engineered synthetic bone grafts using a hybrid approach that combined three-dimensional (3D-)printed biodegradable, osteoconductive β-tricalcium phosphate (β-TCP) with osteoinductive microRNA(miR)-200c. 3D-printed β-TCP scaffolds were fabricated utilizing a suspension-enclosing projection-stereolithography (SEPS) process to produce constructs with reproducible microarchitectures that enhanced the osteoconductive properties of β-TCP. Collagen coating on 3D-printed β-TCP scaffolds slowed the release of plasmid DNA encoding miR-200c compared to noncoated constructs. 3D-printed β-TCP scaffolds coated with miR-200c-incorporated collagen increased the transfection efficiency of miR-200c of both rat and human BMSCs and additionally increased osteogenic differentiation of hBMSCs in vitro. Furthermore, miR-200c-incorporated scaffolds significantly enhanced bone regeneration in critical-sized rat calvarial defects. These results strongly indicate that bone grafts combining SEPS 3D-printed osteoconductive biomaterial-based scaffolds with osteoinductive miR-200c can be used as superior bone substitutes for the clinical treatment of large bone defects.

MicroRNA miR-8 promotes cell growth of corpus allatum and juvenile hormone biosynthesis independent of insulin/IGF signaling in Drosophila melanogaster

The Drosophila melanogaster corpus allatum (CA) produces and releases three types of sesquiterpenoid hormones, including juvenile hormone III bisepoxide (JHB3), juvenile hormone III (JH III), and methyl farnesoate (MF). JH biosynthesis involves multiple discrete enzymatic reactions and is subjected to a comprehensive regulatory network including microRNAs (miRNAs). Using a high throughput sequencing approach, we have identified abundant miRNAs in the D. melanogaster ring gland, which consists of the CA, prothoracic gland, and corpus cardiaca. Genetic and qPCR screens were then performed in an attempt to uncover the full repertoire of CA miRNAs that are involved in regulating metamorphosis. miR-8 was identified as a potential candidate and further studied for its role in the CA. Overexpression of miR-8 in the CA increased cell size of the gland and expression of Jhamt (a gene coding for a key regulatory enzyme in JH biosynthesis), resulting in pupal lethality. By contrast, sponge-mediated reduction of miR-8 in the CA decreased cell size and Jhamt expression, but did not cause lethality. Further investigation revealed that miR-8 promotes cell growth independent of insulin/IGF signaling. Taken together, these experiments show that miR-8 is highly expressed in the CA and exerts its positive effects on cell growth and JH biosynthesis. The miRNAs data in the ring gland also provide a useful resource to study how miRNAs collaboratively regulate hormone synthesis in D. melanogaster.

miR-8b is involved in brain and eye regeneration of Dugesia japonica in head regeneration

MicroRNAs (miRNAs) are a class of evolutionarily conserved small non-coding RNAs that regulate gene expression at the translation level in cell growth, proliferation and differentiation. In addition, some types of miRNAs have been proven to be key modulators of both CNS development and plasticity, such as let-7, miR-9 and miR-124. In this research, we found miR-8b acts as an important regulator involved in brain and eyespot regeneration in Dugesia japonica. miR-8b was highly conserved among species and was abundantly expressed in central nervous system. Here, we detected the expression dynamics of miR-8b by qPCR during the head regeneration of D. japonica. Knockdown miR-8b by anti-MIRs method caused severe defects of eyes and CNS. Our study revealed the evolutionary conserved role of miR-8b in the planarian regeneration process, and further provided more research ideas and available information for planarian miRNAs.

Summary: Most miRNAs in planarians are homologous to humans and other mammals, and may also play a similar regulatory role. Knockdown miR-8b planarian miR-8b induces brain and eyespot defects during head regeneration.

TSCCA: A tensor sparse CCA method for detecting microRNA-gene patterns from multiple cancers

Existing studies have demonstrated that dysregulation of microRNAs (miRNAs or miRs) is involved in the initiation and progression of cancer. Many efforts have been devoted to identify microRNAs as potential biomarkers for cancer diagnosis, prognosis and therapeutic targets. With the rapid development of miRNA sequencing technology, a vast amount of miRNA expression data for multiple cancers has been collected. These invaluable data repositories provide new paradigms to explore the relationship between miRNAs and cancer. Thus, there is an urgent need to explore the complex cancer-related miRNA-gene patterns by integrating multi-omics data in a pan-cancer paradigm. In this study, we present a tensor sparse canonical correlation analysis (TSCCA) method for identifying cancer-related miRNA-gene modules across multiple cancers. TSCCA is able to overcome the drawbacks of existing solutions and capture both the cancer-shared and specific miRNA-gene co-expressed modules with better biological interpretations. We comprehensively evaluate the performance of TSCCA using a set of simulated data and matched miRNA/gene expression data across 33 cancer types from the TCGA database. We uncover several dysfunctional miRNA-gene modules with important biological functions and statistical significance. These modules can advance our understanding of miRNA regulatory mechanisms of cancer and provide insights into miRNA-based treatments for cancer.

MicroRNAs (miRNAs) are a class of small non-coding RNAs. Previous studies have revealed that miRNA-gene regulatory modules play key roles in the occurrence and development of cancer. However, little has been done to discover miRNA-gene regulatory modules from a pan-cancer view. Thus, it is urgently needed to develop new methods to explore the complex cancer-related miRNA-gene patterns by integrating multi-omics data of multi-cancers. To build the connections between miRNA-gene regulatory modules across different cancer types, we propose a tensor sparse canonical correlation analysis (TSCCA) method. Our specific contributions are two-fold: (1) We propose a sparse statistical learning model TSCCA and an efficient block-coordinate descent algorithm to solve it. (2) We apply TSCCA to a multi-omics data set of 33 cancer types from TCGA and identify some cancer-related miRNA-gene modules with important biological functions and statistical significance.

Drosophila primary microRNA-8 encodes a microRNA-encoded peptide acting in parallel of miR-8

BACKGROUND

Recent genome-wide studies of many species reveal the existence of a myriad of RNAs differing in size, coding potential and function. Among these are the long non-coding RNAs, some of them producing functional small peptides via the translation of short ORFs. It now appears that any kind of RNA presumably has a potential to encode small peptides. Accordingly, our team recently discovered that plant primary transcripts of microRNAs (pri-miRs) produce small regulatory peptides (miPEPs) involved in auto-regulatory feedback loops enhancing their cognate microRNA expression which in turn controls plant development. Here we investigate whether this regulatory feedback loop is present in Drosophila melanogaster.

RESULTS

We perform a survey of ribosome profiling data and reveal that many pri-miRNAs exhibit ribosome translation marks. Focusing on miR-8, we show that pri-miR-8 can produce a miPEP-8. Functional assays performed in Drosophila reveal that miPEP-8 affects development when overexpressed or knocked down. Combining genetic and molecular approaches as well as genome-wide transcriptomic analyses, we show that miR-8 expression is independent of miPEP-8 activity and that miPEP-8 acts in parallel to miR-8 to regulate the expression of hundreds of genes.

CONCLUSION

Taken together, these results reveal that several Drosophila pri-miRs exhibit translation potential. Contrasting with the mechanism described in plants, these data shed light on the function of yet undescribed primary-microRNA-encoded peptides in Drosophila and their regulatory potential on genome expression.

The interaction between miRNAs/lncRNAs and Notch pathway in human disorders

Notch pathway is a signaling cascade with important impacts on cell proliferation, differentiation, developmental processes and tissue homeostasis. This pathway also regulates stem cell properties, thus being involved in both normal developmental processes and metastatic capacity of cancer cells. Lots of lncRNAs and miRNAs have been recognized that control Notch pathway at some levels or their expression is regulated by this pathway. FOXD2-AS1, MEG3, ANRIL, linc-OIP5, lincRNA-p21, CBR3-AS1, HOTAIR, PVT1 and GAS5 are among lncRNAs that interact with Notch signaling. miR-19, miR-21, miR-33a, miR-8/200, miR-34a, miR-146a, miR-37, miR-100, miR-107 and several other miRNAs have functional interplay with this signaling cascade. In the present review article, we have illuminated the interplay between lncRNAs/miRNAs and Notch pathway in two distinct contexts i.e. cancers and non-neoplastic conditions.

Inhibition of miR-200b Promotes Angiogenesis in Endothelial Cells by Activating The Notch Pathway

Objective

Patients with diabetes mellitus frequently have chronic wounds or diabetic ulcers as a result of impaired wound healing, which may lead to limb amputation. Human umbilical vein endothelial cell (HUVEC) dysfunction also delays wound healing. Here, we investigated the mechanism of miR-200b in HUVECs under high glucose conditions and the potential of miR-200b as a therapeutic target.

Materials and Methods

In this experimental study, HUVECs were cultured with 5 or 30 mM glucose for 48 hours. Cell proliferation was evaluated by CCK-8 assays. Cell mobility was tested by wound healing and Transwell assays. Angiogenesis was analyzed in vitro Matrigel tube formation assays. Luciferase reporter assays were used to test the binding of miR-200b with Notch1.

Results

miR-200b expression was induced by high glucose treatment of HUVECs (P<0.01), and it significantly repressed cell proliferation, migration, and tube formation (P<0.05). Notch1 was directly targeted and repressed by miR-200b at both the mRNA and protein levels. Inhibition of miR-200b restored Notch1 expression (P<0.05) and reactivated the Notch pathway. The effects of miR-200b inhibition in HUVECs could be reversed by treatment with a Notch pathway inhibitor (P<0.05), indicating that the miR-200b/Notch axis modulates the proliferation, migration, and tube formation ability of HUVECs.

Conclusion

Inhibition of miR-200b activated the angiogenic ability of endothelial cells and promoted wound healing through reactivation of the Notch pathway in vitro. miR-200b could be a promising therapeutic target for treating HUVEC dysfunction.

MicroRNAs in treatment-induced neuroendocrine differentiation in prostate cancer

Prostate cancer is a condition commonly associated with men worldwide. Androgen deprivation therapy remains one of the targeted therapies. However, after some years, there is biochemical recurrence and metastatic progression into castration-resistant prostate cancer (CRPC). CRPC cases are treated with second-line androgen deprivation therapy, after which, these CRPCs transdifferentiate to form neuroendocrine prostate cancer (NEPC), a highly aggressive variant of CRPC. NEPC arises via a reversible transdifferentiation process, known as neuroendocrine differentiation (NED), which is associated with altered expression of lineage markers such as decreased expression of androgen receptor and increased expression of neuroendocrine lineage markers including enolase 2, chromogranin A and synaptophysin. The etiological factors and molecular basis for NED are poorly understood, contributing to a lack of adequate molecular biomarkers for its diagnosis and therapy. Therefore, there is a need to fully understand the underlying molecular basis for this cancer. Recent studies have shown that microRNAs (miRNAs) play a key epigenetic role in driving therapy-induced NED in prostate cancer. In this review, we briefly describe the role of miRNAs in prostate cancer and CRPCs, discuss some key players in NEPCs and elaborate on miRNA dysregulation as a key epigenetic process that accompanies therapy-induced NED in metastatic CRPC. This understanding will contribute to better clinical management of the disease.

Dual Effects of Non-Coding RNAs (ncRNAs) in Cancer Stem Cell Biology

The identification of cancer stem cells (CSCs) as initiators of carcinogenesis has revolutionized the era of cancer research and our perception for the disease treatment options. Additional CSC features, including self-renewal and migratory and invasive capabilities, have further justified these cells as putative diagnostic, prognostic, and therapeutic targets. Given the CSC plasticity, the identification of CSC-related biomarkers has been a serious burden in CSC characterization and therapeutic targeting. Over the past decades, a compelling amount of evidence has demonstrated critical regulatory functions of non-coding RNAs (ncRNAs) on the exclusive features of CSCs. We now know that ncRNAs may interfere with signaling pathways, vital for CSC phenotype maintenance, such as Notch, Wnt, and Hedgehog. Here, we discuss the multifaceted contribution of microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), as representative ncRNA classes, in sustaining the CSC-like traits, as well as the underlying molecular mechanisms of their action in various CSC types. We further discuss the use of CSC-related ncRNAs as putative biomarkers of high diagnostic, prognostic, and therapeutic value.

Multiplex profiling identifies clinically relevant signalling proteins in an isogenic prostate cancer model of radioresistance

The exact biological mechanism governing the radioresistant phenotype of prostate tumours at a high risk of recurrence despite the delivery of advanced radiotherapy protocols remains unclear. This study analysed the protein expression profiles of a previously generated isogenic 22Rv1 prostate cancer model of radioresistance using DigiWest multiplex protein profiling for a selection of 90 signalling proteins. Comparative analysis of the profiles identified a substantial change in the expression of 43 proteins. Differential PARP-1, AR, p53, Notch-3 and YB-1 protein levels were independently validated using Western Blotting. Pharmacological targeting of these proteins was associated with a mild but significant radiosensitisation effect at 4Gy. This study supports the clinical relevance of isogenic in vitro models of radioresistance and clarifies the molecular radiation response of prostate cancer cells.

miR-200c suppresses stemness and increases cellular sensitivity to trastuzumab in HER2+ breast cancer

Resistance to trastuzumab remains a major obstacle in HER2‐overexpressing breast cancer treatment. miR‐200c is important for many functions in cancer stem cells (CSCs), including tumour recurrence, metastasis and resistance. We hypothesized that miR‐200c contributes to trastuzumab resistance and stemness maintenance in HER2‐overexpressing breast cancer. In this study, we used HER2‐positive SKBR3, HER2‐negative MCF‐7, and their CD44⁺CD24⁻ phenotype mammospheres SKBR3‐S and MCF‐7‐S to verify. Our results demonstrated that miR‐200c was weakly expressed in breast cancer cell lines and cell line stem cells. Overexpression of miR‐200c resulted in a significant reduction in the number of tumour spheres formed and the population of CD44⁺CD24⁻ phenotype mammospheres in SKBR3‐S. Combining miR‐200c with trastuzumab can significantly reduce proliferation and increase apoptosis of SKBR3 and SKBR3‐S. Overexpression of miR‐200c also eliminated its downstream target genes. These genes were highly expressed and positively related in breast cancer patients. Overexpression of miR‐200c also improved the malignant progression of SKBR3‐S and SKBR3 in vivo. miR‐200c plays an important role in the maintenance of the CSC‐like phenotype and increases drug sensitivity to trastuzumab in HER2+ cells and stem cells.

MicroRNAs in Drosophila Cancer Models

MiRNAs are post-transcriptional regulators of gene expression which have been implicated in virtually all biological processes. MiRNAs are frequently dysregulated in human cancers. However, the functional consequences of aberrant miRNA levels are not well understood. Drosophila is emerging as an important in vivo tumor model, especially in the identification of novel cancer genes. Here, we review Drosophila studies which functionally dissect the roles of miRNAs in tumorigenesis. Ultimately, these advances help to understand the implications of miRNA dysregulation in human cancers.

Oncometabolites in cancer aggressiveness and tumour repopulation

Tumour repopulation is recognized as a crucial event in tumour relapse where therapy-sensitive dying cancer cells influence the tumour microenvironment to sustain therapy-resistant cancer cell growth. Recent studies highlight the role of the oncometabolites succinate, fumarate, and 2-hydroxyglutarate in the aggressiveness of cancer cells and in the worsening of the patient's clinical outcome. These oncometabolites can be produced and secreted by cancer and/or surrounding cells, modifying the tumour microenvironment and sustaining an invasive neoplastic phenotype. In this review, we report recent findings concerning the role in cancer development of succinate, fumarate, and 2-hydroxyglutarate and the regulation of their related enzymes succinate dehydrogenase, fumarate hydratase, and isocitrate dehydrogenase. We propose that oncometabolites are crucially involved in tumour repopulation. The study of the mechanisms underlying the relationship between oncometabolites and tumour repopulation is fundamental for identifying efficient anti-cancer therapeutic strategies and novel serum biomarkers in order to overcome cancer relapse.

Multiple functions of miR-8-3p in the development and metamorphosis of the red flour beetle, Tribolium castaneum

The microRNA miR-8-3p is conserved among insects and closely involved in development and immunity, but its functions in vivo are unexplored in the red flour beetle, Tribolium castaneum. Here, we show that miR-8-3p was highly expressed in late larva and early adult stages, as determined by quantitative real-time PCR. It was enriched in the fat body and cuticle in late larval tissues and abundant in the head and cuticle in early adult tissues, indicating this microRNA plays important roles during T. castaneum development. Specific inhibition of miR-8-3p in late larvae led to metamorphosis defects in the development of wings, eyes, legs and embryo. Moreover, a series of genes related to organism development were identified as miR-8-3p targets by computational prediction and microRNA-messenger RNA interaction validation, including Wingless, Eyg, Fpps and Sema-1a. These genes were critical for the regulation of the larva-to-adult transition. Eyg, as a functional target of miR-8-3p, participates in eye development, which was further confirmed by luciferase assay and loss-of-function analyses. In brief, miR-8-3p is broadly involved in the development of wings, eyes and legs through its target genes and has extensive regulatory roles during T. castaneum development.

Epigenetic Mechanisms Influencing Epithelial to Mesenchymal Transition in Bladder Cancer

Bladder cancer is one of the most incident neoplasms worldwide, and its treatment remains a significant challenge, since the mechanisms underlying disease progression are still poorly understood. The epithelial to mesenchymal transition (EMT) has been proven to play an important role in the tumorigenic process, particularly in cancer cell invasiveness and metastatic potential. Several studies have reported the importance of epigenetic mechanisms and enzymes, which orchestrate them in several features of cancer cells and, specifically, in EMT. In this paper, we discuss the epigenetic enzymes, protein-coding and non-coding genes, and mechanisms altered in the EMT process occurring in bladder cancer cells, as well as its implications, which allows for improved understanding of bladder cancer biology and for the development of novel targeted therapies.

Regulation of cytoplasmic RNA stability: Lessons from Drosophila

The process of RNA degradation is a critical level of regulation contributing to the control of gene expression. In the last two decades a number of studies have shown the specific and targeted nature of RNA decay and its importance in maintaining homeostasis. The key players within the pathways of RNA decay are well conserved with their mutation or disruption resulting in distinct phenotypes as well as human disease. Model organisms including Drosophila melanogaster have played a substantial role in elucidating the mechanisms conferring control over RNA stability. A particular advantage of this model organism is that the functions of ribonucleases can be assessed in the context of natural cells within tissues in addition to individual immortalized cells in culture. Drosophila RNA stability research has demonstrated how the cytoplasmic decay machines, such as the exosome, Dis3L2 and Xrn1, are responsible for regulating specific processes including apoptosis, proliferation, wound healing and fertility. The work discussed here has begun to identify specific mRNA transcripts that appear sensitive to specific decay pathways representing mechanisms through which the ribonucleases control mRNA stability. Drosophila research has also contributed to our knowledge of how specific RNAs are targeted to the ribonucleases including AU rich elements, miRNA targeting and 3' tailing. Increased understanding of these mechanisms is critical to elucidating the control elicited by the cytoplasmic ribonucleases which is relevant to human disease. This article is categorized under: RNA in Disease and Development > RNA in Development RNA Turnover and Surveillance > Regulation of RNA Stability RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms.

miR-200b/c targets the expression of RhoE and inhibits the proliferation and invasion of non-small cell lung cancer cells

Lung cancer is a major cause of mortality worldwide and non‑small cell lung cancer (NSCLC) accounts for ~80% of all cases of lung cancer. Increasing evidence indicates that Rho family GTPase 3 (RhoE) is important in the carcinogenesis and progression of NSCLC. In addition, several studies have indicated that microRNA (miR)‑200b/c is downregulated in NSCLC cells. However, the exact mechanism remains to be elucidated. In the present study, immunohistochemistry (IHC) assays were used to analyze the RhoE and epithelial‑mesenchymal transition (EMT)‑related proteins in NSCLC tissues. Putative target sequences of the RhoE 3' untranslated region (3'UTR) for miR‑200b/c were detected using bioinformatics analysis. The mRNA expression levels of RhoE and miR‑200b/c were determined by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) analysis, and western blot analysis was used to detect the protein levels of RhoE in cells. The luciferase‑reporter activity of the RhoE 3'UTR was detected using a dual‑luciferase assay. A cell counting kit‑8 assay, flow cytometry and Transwell assay were used to detect cell proliferation, cell cycle, and invasion and migration ability, respectively. The IHC assays indicated that RhoE was overexpressed in NSCLC tissues. The bioinformatics analysis revealed that the RhoE 3'UTR contained a putative target site for miR‑200b/c, which was conserved across species. The results of RT‑qPCR analysis showed that the mRNA expression of RhoE was overexpressed and miR‑200b/200c was decreased in lung cancer tissues. The enhanced expression of miR‑200b or miR‑200c significantly downregulated the expression of RhoE at the mRNA and protein levels in A549 and NCI‑H1299 NSCLC cells. Furthermore, luciferase assays showed that miR‑200b and miR‑200c directly targeted the 3'UTR of RhoE. The forced expression of miR‑200b or miR‑200c markedly inhibited A549 cell and NCI‑H1299 cell proliferation, G0/G1 progression and cell invasion, which was consistent with the effects of RNA interference‑mediated RhoE knockdown in these cells. The suppression of RhoE regulated the expression of EMT‑related markers, which was consistent with the effect of miR‑200b/c in NSCLC cells, and the expression of EMT‑related proteins and RhoE were also correlated in the lung cancer tissues. Therefore, miR‑200b and miR‑200c targeted the expression of RhoE and inhibited the malignancy of NSCLC cells, and the downregulation of miR‑200b and miR‑200c may contribute to the high expression of RhoE in NSCLC.

Cross-regulation between Notch signaling pathway and miRNA machinery in cancer

Despite their simple structure, the Notch family of receptors regulates a wide-spectrum of key cellular processes including development, tissue patterning, cell-fate determination, proliferation, differentiation and, cell death. On the other hand, accumulating date pinpointed the role of non-coding microRNAs, namely miRNAs in cancer initiation/progression via regulating the expression of multiple oncogenes and tumor suppressor genes, as such the Notch signaling. It is now documented that these two partners are in one or in the opposite directions and rule together the cancer fate. Here, we review the current knowledge relevant to this tricky interplay between different miRNAs and components of Notch signaling pathway. Further, we discuss the implication of this crosstalk in cancer progression/regression in the context of cancer stem cells, tumor angiogenesis, metastasis and emergence of multi-drug resistance. Understanding the molecular cues and mechanisms that occur at the interface of miRNA and Notch signaling would open new avenues for development of novel and effective strategies for cancer therapy.

A population of adult satellite-like cells in Drosophila is maintained through a switch in RNA-isoforms

Adult stem cells are important for tissue maintenance and repair. One key question is how such cells are specified and then protected from differentiation for a prolonged period. Investigating the maintenance of Drosophila muscle progenitors (MPs) we demonstrate that it involves a switch in zfh1/ZEB1 RNA-isoforms. Differentiation into functional muscles is accompanied by expression of miR-8/miR-200, which targets the major zfh1-long RNA isoform and decreases Zfh1 protein. Through activity of the Notch pathway, a subset of MPs produce an alternate zfh1-short isoform, which lacks the miR-8 seed site. Zfh1 protein is thus maintained in these cells, enabling them to escape differentiation and persist as MPs in the adult. There, like mammalian satellite cells, they contribute to muscle homeostasis. Such preferential regulation of a specific RNA isoform, with differential sensitivity to miRs, is a powerful mechanism for maintaining a population of poised progenitors and may be of widespread significance.

LncRNA XIST/miR-200c regulates the stemness properties and tumourigenicity of human bladder cancer stem cell-like cells

Background

The abnormal expression of non-coding RNAs (ncRNAs), such as microRNAs and long ncRNAs, often contribute to the development of cancers. miR-200c functions as a tumour suppressor that impacts the growth of bladder cancer cells and the epithelial-to-mesenchymal transition (EMT). LncRNA X inactive specific transcript (XIST) is highly expressed in tumour tissues, promotes cancer progression and might act as an miRNA molecular sponge. This study aimed to examine the relationship between lncRNA XIST and miR-200c and to assess their functions in the regulation of the stemness properties and tumourigenicity of human bladder cancer stem cell (BCSC)-like cells.

Methods

Biological effects including cell clone formation, sphere formation, self-renewal properties and mouse tumourigenesis were examined in BCSC-like cells with miR-200c overexpression or XIST knockdown. Real-time PCR and western blotting were used to detect the expression changing of related factors in BCSC-like cells gene models. Dual luciferase reporter assay was used to examine the changes of XIST and miR-200c expression levels.

Results

The results indicated that miR-200c overexpression and XIST knockdown could inhibit cell clone formation, self-renewal ability and EMT in BCSC-like cells. miR-200c knockdown could restore the tumour growth inhibition caused by XIST knockdown.

Conclusion

LncRNA XIST may act as an inhibitor of miR-200c to regulate the stemness properties and tumourigenicity of bladder cancer cells, and our findings might reveal a potential strategy of targeting XIST for bladder cancer therapy.

Modelling Cooperative Tumorigenesis in Drosophila

The development of human metastatic cancer is a multistep process, involving the acquisition of several genetic mutations, tumour heterogeneity, and interactions with the surrounding microenvironment. Due to the complexity of cancer development in mammals, simpler model organisms, such as the vinegar fly, Drosophila melanogaster, are being utilized to provide novel insights into the molecular mechanisms involved. In this review, we highlight recent advances in modelling tumorigenesis using the Drosophila model, focusing on the cooperation of oncogenes or tumour suppressors, and the interaction of mutant cells with the surrounding tissue in epithelial tumour initiation and progression.

microRNA involvement in the onset and progression of Barrett's esophagus: a systematic review

Esophageal adenocarcinoma (EAC) is a highly aggressive malignancy that develops from Barrett's esophagus (BE), an intestinal metaplasia of the distal esophagus. microRNAs (miRNAs), short non-coding regulatory RNAs, are frequently dysregulated in BE and are thought to play key roles in the onset of BE and its progression to EAC. miRNAs thus have potential diagnostic and prognostic value and are increasingly being used as cancer biomarkers. This review summarizes the current literature related to miRNAs that are dysregulated in BE within the context of Hedgehog, Notch, MAPK, NF kappa-B, Wnt and epithelial-mesenchymal transition (EMT) signaling which are thought to drive BE onset and progression. This comprehensive analysis of miRNAs and their associated signaling in the regulation of BE provides an overview of vital discoveries in this field and highlights gaps in our understanding of BE pathophysiology that warrant further investigation.

Integration of Drosophila and Human Genetics to Understand Notch Signaling Related Diseases

Notch signaling research dates back to more than one hundred years, beginning with the identification of the Notch mutant in the fruit fly Drosophila melanogaster. Since then, research on Notch and related genes in flies has laid the foundation of what we now know as the Notch signaling pathway. In the 1990s, basic biological and biochemical studies of Notch signaling components in mammalian systems, as well as identification of rare mutations in Notch signaling pathway genes in human patients with rare Mendelian diseases or cancer, increased the significance of this pathway in human biology and medicine. In the 21st century, Drosophila and other genetic model organisms continue to play a leading role in understanding basic Notch biology. Furthermore, these model organisms can be used in a translational manner to study underlying mechanisms of Notch-related human diseases and to investigate the function of novel disease associated genes and variants. In this chapter, we first briefly review the major contributions of Drosophila to Notch signaling research, discussing the similarities and differences between the fly and human pathways. Next, we introduce several biological contexts in Drosophila in which Notch signaling has been extensively characterized. Finally, we discuss a number of genetic diseases caused by mutations in genes in the Notch signaling pathway in humans and we expand on how Drosophila can be used to study rare genetic variants associated with these and novel disorders. By combining modern genomics and state-of-the art technologies, Drosophila research is continuing to reveal exciting biology that sheds light onto mechanisms of disease.

Oncogenic cooperation between Yorkie and the conserved microRNA miR-8 in the wing disc of Drosophila

Tissue growth has to be carefully controlled to generate well-functioning organs. microRNAs are small noncoding RNAs that modulate the activity of target genes and play a pivotal role in animal development. Understanding the functions of microRNAs in development requires the identification of their target genes. Here, we find that the conserved microRNA miR-8/miR-200 controls tissue growth and homeostasis in the Drosophila wing imaginal disc. Upregulation of miR-8 causes the repression of Yorkie, the effector of the Hippo pathway in Drosophila, and reduces tissue size. Remarkably, coexpression of Yorkie and miR-8 causes the formation of neoplastic tumors. We show that upregulation of miR-8 represses the growth inhibitor brinker, and depletion of brinker cooperates with Yorkie in the formation of neoplastic tumors. Hence, miR-8 modulates a positive growth regulator, Yorkie, and a negative growth regulator, brinker. Deregulation of this network can result in the loss of tissue homeostasis and the formation of tumors.

Interplay between Notch1 and Notch3 promotes EMT and tumor initiation in squamous cell carcinoma

Notch1 transactivates Notch3 to drive terminal differentiation in stratified squamous epithelia. Notch1 and other Notch receptor paralogs cooperate to act as a tumor suppressor in squamous cell carcinomas (SCCs). However, Notch1 can be stochastically activated to promote carcinogenesis in murine models of SCC. Activated form of Notch1 promotes xenograft tumor growth when expressed ectopically. Here, we demonstrate that Notch1 activation and epithelial–mesenchymal transition (EMT) are coupled to promote SCC tumor initiation in concert with transforming growth factor (TGF)-β present in the tumor microenvironment. We find that TGFβ activates the transcription factor ZEB1 to repress Notch3, thereby limiting terminal differentiation. Concurrently, TGFβ drives Notch1-mediated EMT to generate tumor initiating cells characterized by high CD44 expression. Moreover, Notch1 is activated in a small subset of SCC cells at the invasive tumor front and predicts for poor prognosis of esophageal SCC, shedding light upon the tumor promoting oncogenic aspect of Notch1 in SCC.

Notch receptors can exert different roles in cancer. In this manuscript, the authors reveal that Notch1 activation and EMT promote tumor initiation and cancer cell heterogeneity in squamous cell carcinoma, while the repression of Notch3 by ZEB1 limits Notch1-induced differentiation, permitting Notch1-mediated EMT.

Systematic analysis reveals tumor-enhancing and -suppressing microRNAs in Drosophila epithelial tumors

Despite their emergence as an important class of noncoding RNAs involved in cancer cell transformation, invasion, and migration, the precise role of microRNAs (miRNAs) in tumorigenesis remains elusive. To gain insights into how miRNAs contribute to primary tumor formation, we conducted an RNA sequencing (RNA-Seq) analysis of Drosophila wing disc epithelial tumors induced by knockdown of a neoplastic tumor-suppressor gene (nTSG) lethal giant larvae (lgl), combined with overexpression of an active form of oncogene Ras (Ras^V12 ), and identified 51 mature miRNAs that changed significantly in tumorous discs. Followed by in vivo tumor enhancer and suppressor screens in sensitized genetic backgrounds, we identified 10 tumor-enhancing (TE) miRNAs and 11 tumor-suppressing (TS) miRNAs that contributed to the nTSG defect-induced tumorigenesis. Among these, four TE and three TS miRNAs have human homologs. From this study, we also identified 29 miRNAs that individually had no obvious role in enhancing or alleviating tumorigenesis despite their changed expression levels in nTSG tumors. This systematic analysis, which includes both RNA-Seq and in vivo functional studies, helps to categorize miRNAs into different groups based on their expression profile and functional relevance in epithelial tumorigenesis, whereas the evolutionarily conserved TE and TS miRNAs provide potential therapeutic targets for epithelial tumor treatment.

MicroRNA-driven deregulation of cytokine expression helps development of drug resistance in metastatic melanoma

microRNAs are major components of the eukaryotic post-transcriptional machinery and are frequently deregulated during cancer development. Increasing evidence points to them also as key players in the establishment of drug resistance. In this review, we provide an updated overview of the role of miRNAs in melanoma development and drug resistance and postulate that they are able to drive these processes in concert with deregulation of inflammatory and angiogenic cytokine expression. Notably, we have identified by querying the Cancer Genome Atlas database, a defined set of miRNAs which mostly have an impact on the development of melanoma and have recognized the main downstream pathways controlled by them. Most importantly, these miRNAs, which are down-regulated in metastatic melanomas as compared to primary tumors, are also able to predict prognosis of BRAF-mutated melanoma patients. Finally, we discuss the possibility that a common miRNA signature characterizes not only acquired resistance to MAPKi but also innate resistance to anti-PD-1 immunotherapy, since these conditions are both associated with alterations of the same pro-angiogenetic and pro-inflammatory pathways.

MicroRNA-200c increases radiosensitivity of human cancer cells with activated EGFR-associated signaling

MicroRNA-200c (miR-200c) recently was found to have tumor-suppressive properties by inhibiting the epithelial-mesenchymal transition (EMT) in several cancers. miR-200c also interacts with various cellular signaling molecules and regulates many important signaling pathways. In this study, we investigated the radiosensitizing effect of miR-200c and its mechanism in a panel of human cancer cell lines. Malignant glioma (U251, T98G), breast cancer (MDA-MB-468), and lung carcinoma (A549) cells were transfected with control pre-microRNA, pre-miR-200c, or anti-miR-200c. Then, RT-PCR, clonogenic assays, immunoblotting, and immunocytochemisty were performed. To predict the potential targets of miR-200c, microRNA databases were used for bioinformatics analysis. Ectopic overexpression of miR-200c downregulated p-EGFR and p-AKT and increased the radiosensitivity of U251, T98G, A549, and MDA-MB-468 cells. In contrast, miR-200c inhibition upregulated p-EGFR and p-AKT, and decreased radiation-induced cell killing. miR-200c led to persistent γH2AX focus formation and downregulated pDNA-PKc expression. Autophagy and apoptosis were major modes of cell death. Bioinformatics analysis predicted that miR-200c may be associated with EGFR, AKT2, MAPK1, VEGFA, and HIF1AN. We also confirmed that miR-200c downregulated the expression of VEGF, HIF-1α, and MMP2 in U251 and A549 cells. In these cells, overexpressing miR-200c inhibited invasion, migration, and vascular tube formation. These phenotypic changes were associated with E-cadherin and EphA2 downregulation and N-cadherin upregulation. miR-200c showed no observable cytotoxic effect on normal human fibroblasts and astrocytes. Taken together, our data suggest that miR-200c is an attractive target for improving the efficacy of radiotherapy via a unique modulation of the complex regulatory network controlling cancer pro-survival signaling and EMT.

Metformin Inhibits Tumorigenesis and Tumor Growth of Breast Cancer Cells by Upregulating miR-200c but Downregulating AKT2 Expression

Background: Metformin has been reported to inhibit the growth of various types of cancers, including breast cancer. Yet the mechanisms underlying the anticancer effects of metformin are not fully understood. Growing evidence suggests that metformin's anticancer effects are mediated at least in part by modulating microRNAs, including miR-200c, which has a tumor suppressive role in breast cancer. We hypothesized that miR-200c has a role in the antitumorigenic effects of metformin on breast cancer cells.

Methods: To delineate the role of miR-200c in the effects of metformin on breast cancer, plasmids containing pre-miR-200c or miR-200c inhibitor were transfected into breast cancer cell lines. The MDA-MB-231, BT549, MCF-7, and T-47-D cells' proliferation, apoptosis, migration, and invasion were assessed. The antitumor role of metformin in vivo was investigated in a MDA-MB-231 xenograft tumor model in SCID mice.

Results: Metformin significantly inhibited the growth, migration, and invasion of breast cancer cells, and induced their apoptosis; these effects were dependent on both dose and time. Metformin also suppressed MDA-MB-231 tumor growth in SCID mice in vivo. Metformin treatment was associated with increased miR-200c expression and decreased c-Myc and AKT2 protein expression in both breast cancer cells and tumor tissues. Overexpression of miR-200c exhibited effects on breast cancer cells similar to those of metformin treatment. In contrast, inhibiting the expression of miR-200c increased the growth, migration, and invasion of MCF-7 and MDA-MB-231 cells.

Conclusion: Metformin inhibits the growth and invasiveness of breast cancer cells by upregulation of miR-200c expression by targeting AKT2. These findings provide novel insight into the molecular functions of metformin that suggest its potential as an anticancer agent.

MicroRNA‑141 inhibits the self‑renewal of glioblastoma stem cells via Jagged1

Glioblastoma multiforme is one of the most lethal types of brain cancer. With limited success from conventional therapies, the cancer stem cell theory was developed, and investigation into microRNAs (miRs) has facilitated understanding of this theory. The present study demonstrated that miR-141 is suppressed in sorted cluster of differentiation (CD) 133(+) glioblastoma stem cells (GSCs) compared with CD133(−) non-glioblastoma stem cells (NSCs) from patient samples. In addition, miR-141 overexpression inhibited the sphere formation ability of GSCs in vitro and in vivo. Furthermore, Jagged1 may reverse the effect of miR-141; miR-141 was revealed to target the 3′-untranslated region of Jagged1, thereby inhibiting the stemness of GSCs. Thus, miR-141 may serve as a potent antioncomir targeting cancer stem cells, and may facilitate the development of therapeutic targets to prolong the overall survival of patients with glioblastoma.

miR-285-Yki/Mask double-negative feedback loop mediates blood-brain barrier integrity in Drosophila

The Hippo signaling pathway is highly conserved from Drosophila to mammals and plays a central role in maintaining organ size and tissue homeostasis. The blood-brain barrier (BBB) physiologically isolates the brain from circulating blood or the hemolymph system, and its integrity is strictly maintained to perform sophisticated neuronal functions. Until now, the underlying mechanisms of subperineurial glia (SPG) growth and BBB maintenance during development are not clear. Here, we report an miR-285-Yorkie (Yki)/Multiple Ankyrin repeats Single KH domain (Mask) double-negative feedback loop that regulates SPG growth and BBB integrity. Flies with a loss of miR-285 have a defective BBB with increased SPG ploidy and disruptive septate junctions. Mechanistically, miR-285 directly targets the Yki cofactor Mask to suppress Yki activity and down-regulates the expression of its downstream target cyclin E, a key regulator of cell cycle. Disturbance of cyclin E expression in SPG causes abnormal endoreplication, which leads to aberrant DNA ploidy and defective septate junctions. Moreover, the expression of miR-285 is increased by knockdown of yki or mask and is decreased with yki overexpression, thus forming a double-negative feedback loop. This regulatory loop is crucial for sustaining an appropriate Yki/Mask activity and cyclin E level to maintain SPG ploidy and BBB integrity. Perturbation of this signaling loop, either by dysregulated miR-285 expression or Yki activity, causes irregular SPG ploidy and BBB disruption. Furthermore, ectopic expression of miR-285 promotes canonical Hippo pathway-mediated apoptosis independent of the p53 or JNK pathway. Collectively, these results reveal an exquisite regulatory mechanism for BBB maintenance through an miR-285-Yki/Mask regulatory circuit.

Function of the SIRT3 mitochondrial deacetylase in cellular physiology, cancer, and neurodegenerative disease

In mammals, seven members of the sirtuin protein family known as class III histone deacetylase have been identified for their characteristic features. These distinguished characteristics include the tissues where they are distributed or located, enzymatic activities, molecular functions, and involvement in diseases. Among the sirtuin members, SIRT3 has received much attention for its role in cancer genetics, aging, neurodegenerative disease, and stress resistance. SIRT3 controls energy demand during stress conditions such as fasting and exercise as well as metabolism through the deacetylation and acetylation of mitochondrial enzymes. SIRT3 is well known for its ability to eliminate reactive oxygen species and to prevent the development of cancerous cells or apoptosis. This review article provides a comprehensive review on numerous (noteworthy) molecular functions of SIRT3 and its effect on cancer cells and various diseases including Huntington's disease, amyotrophic lateral sclerosis, and Alzheimer's disease.

MicroRNA-141 suppresses prostate cancer stem cells and metastasis by targeting a cohort of pro-metastasis genes

MicroRNAs play important roles in regulating tumour development, progression and metastasis. Here we show that one of the miR-200 family members, miR-141, is under-expressed in several prostate cancer (PCa) stem/progenitor cell populations in both xenograft and primary patient tumours. Enforced expression of miR-141 in CD44⁺ and bulk PCa cells inhibits cancer stem cell properties including holoclone and sphere formation, as well as invasion, and suppresses tumour regeneration and metastasis. Moreover, miR-141 expression enforces a strong epithelial phenotype with a partial loss of mesenchymal phenotype. Whole-genome RNA sequencing uncovers novel miR-141-regulated molecular targets in PCa cells including the Rho GTPase family members (for example, CDC42, CDC42EP3, RAC1 and ARPC5) and stem cell molecules CD44 and EZH2, all of which are validated as direct and functionally relevant targets of miR-141. Our results suggest that miR-141 employs multiple mechanisms to obstruct tumour growth and metastasis.

MicroRNAs have important roles in regulating tumor development, progression and metastasis. Here, the authors demonstrate the tumor-suppressive functions of miRNA141 in prostate cancer stem cells mediated by directly targeting CD44, Rho GTPase protein family members, and EZH2.

Epithelial to mesenchymal transition-related proteins ZEB1, β-catenin, and β-tubulin-III in idiopathic pulmonary fibrosis

Epithelial to mesenchymal transition has been suggested as a relevant contributor to pulmonary fibrosis, but how and where this complex process is triggered in idiopathic pulmonary fibrosis is not fully understood. Beta-tubulin-III (Tubβ3), ZEB1, and β-catenin are partially under the negative control of miR-200, a family of micro-RNAs playing a major role in epithelial to mesenchymal transition, that are reduced in experimental lung fibrosis and idiopathic pulmonary fibrosis. We wonder whether in situ expression of these proteins is increased in idiopathic pulmonary fibrosis, to better understand the significance of miR-200 feedback loop and epithelial to mesenchymal transition. We investigated the immunohistochemical and immunofluorescent expression and precise location of ZEB1, Tubβ3, and β-catenin in tissue samples from 34 idiopathic pulmonary fibrosis cases and 21 controls (5 normal lungs and 16 other interstitial lung diseases). In 100% idiopathic pulmonary fibrosis samples, the three proteins were concurrently expressed in fibroblastic foci, as well in damaged epithelial cells overlying these lesions and in pericytes within neo-angiogenesis areas. These results were also confirmed by immunofluorescence assay. In controls the abnormal expression of the three proteins was absent or limited. This is the first study that relates concurrent expression of Tubβ3, ZEB1, and β-catenin to abnormal epithelial and myofibroblast differentiation in idiopathic pulmonary fibrosis, providing indirect but robust evidence of miR-200 deregulation and epithelial to mesenchymal transition activation in idiopathic pulmonary fibrosis. The abnormal expression and localization of these proteins in bronchiolar fibro-proliferative lesions are unique for idiopathic pulmonary fibrosis, and might represent a disease-specific marker in challenging lung biopsies.

Identification and characterization of microRNAs expressed in the African malaria vector Anopheles funestus life stages using high throughput sequencing

BACKGROUND

Over the past several years, thousands of microRNAs (miRNAs) have been identified in the genomes of various insects through cloning and sequencing or even by computational prediction. However, the number of miRNAs identified in anopheline species is low and little is known about their role. The mosquito Anopheles funestus is one of the dominant malaria vectors in Africa, which infects and kills millions of people every year. Therefore, small RNA molecules isolated from the four life stages (eggs, larvae, pupae and unfed adult females) of An. funestus were sequenced using next generation sequencing technology.

RESULTS

High throughput sequencing of four replicates in combination with computational analysis identified 107 mature miRNA sequences expressed in the An. funestus mosquito. These include 20 novel miRNAs without sequence identity in any organism and eight miRNAs not previously reported in the Anopheles genus but are known in non-anopheles mosquitoes. Finally, the changes in the expression of miRNAs during the mosquito development were determined and the analysis showed that many miRNAs have stage-specific expression, and are co-transcribed and co-regulated during development.

CONCLUSIONS

This study presents the first direct experimental evidence of miRNAs in An. funestus and the first profiling study of miRNA associated with the maturation in this mosquito. Overall, the results indicate that miRNAs play important roles during the growth and development. Silencing such molecules in a specific life stage could decrease the vector population and therefore interrupt malaria transmission.

miR-489 Suppresses Proliferation and Invasion of Human Bladder Cancer Cells

MicroRNAs (miRNAs) have been shown to be involved in bladder cancer progression. miR-489 (also known as miR-489-3p) was recently reported to be a tumor suppressor in several cancers. However, its exact role and mechanism in the progression of bladder cancer are largely unknown. In this study, we explore the role of miR-489 in the proliferation and invasion of human bladder cancer cells. The miR-489 expression levels were detected in bladder cancer and normal adjacent tissues, as well as in human normal bladder epithelial cells and bladder cancer cell lines. The results showed that miR-489 was sharply reduced in bladder cancer tissues and cell lines. Then the miR-489 mimic or oligo anta-miR-489 was transfected into T24 and UMUC3 bladder cancer cell lines. The results showed that the miR-489 mimic greatly increased the miR-489 level and significantly decreased the proliferation and invasion of T24 and UMUC3 cells. In contrast, the anta-miR-489 had a completely opposite effect on miR-489 expression, cell proliferation, and cell invasion. Moreover, bioinformatics and luciferase reporter gene assays confirmed that miR-489 targeted the mRNA 3'-untranslated region (3'-UTR) region of Jagged1 (JAG1), a Notch ligand. In conclusion, miR-489 suppressed proliferation and invasion of human bladder cancer cells.

Large-Scale microRNA Expression Profiling Identifies Putative Retinal miRNA-mRNA Signaling Pathways Underlying Form-Deprivation Myopia in Mice

Development of myopia is associated with large-scale changes in ocular tissue gene expression. Although differential expression of coding genes underlying development of myopia has been a subject of intense investigation, the role of non-coding genes such as microRNAs in the development of myopia is largely unknown. In this study, we explored myopia-associated miRNA expression profiles in the retina and sclera of C57Bl/6J mice with experimentally induced myopia using microarray technology. We found a total of 53 differentially expressed miRNAs in the retina and no differences in miRNA expression in the sclera of C57BL/6J mice after 10 days of visual form deprivation, which induced -6.93 ± 2.44 D (p < 0.000001, n = 12) of myopia. We also identified their putative mRNA targets among mRNAs found to be differentially expressed in myopic retina and potential signaling pathways involved in the development of form-deprivation myopia using miRNA-mRNA interaction network analysis. Analysis of myopia-associated signaling pathways revealed that myopic response to visual form deprivation in the retina is regulated by a small number of highly integrated signaling pathways. Our findings highlighted that changes in microRNA expression are involved in the regulation of refractive eye development and predicted how they may be involved in the development of myopia by regulating retinal gene expression.

Effects of mutations in Wnt/β-catenin, hedgehog, Notch and PI3K pathways on GSK-3 activity-Diverse effects on cell growth, metabolism and cancer

Glycogen synthase kinase-3 (GSK-3) is a serine/threonine kinase that participates in an array of critical cellular processes. GSK-3 was first characterized as an enzyme that phosphorylated and inactivated glycogen synthase. However, subsequent studies have revealed that this moon-lighting protein is involved in numerous signaling pathways that regulate not only metabolism but also have roles in: apoptosis, cell cycle progression, cell renewal, differentiation, embryogenesis, migration, regulation of gene transcription, stem cell biology and survival. In this review, we will discuss the roles that GSK-3 plays in various diseases as well as how this pivotal kinase interacts with multiple signaling pathways such as: PI3K/PTEN/Akt/mTOR, Ras/Raf/MEK/ERK, Wnt/beta-catenin, hedgehog, Notch and TP53. Mutations that occur in these and other pathways can alter the effects that natural GSK-3 activity has on regulating these signaling circuits that can lead to cancer as well as other diseases. The novel roles that microRNAs play in regulation of the effects of GSK-3 will also be evaluated. Targeting GSK-3 and these other pathways may improve therapy and overcome therapeutic resistance.

Notch signalling in context

The highly conserved Notch signalling pathway functions in many different developmental and homeostatic processes, which raises the question of how this pathway can achieve such diverse outcomes. With a direct route from the membrane to the nucleus, the Notch pathway has fewer opportunities for regulation than do many other signalling pathways, yet it generates exquisitely patterned structures, including sensory hair cells and branched arterial networks. More confusingly, its activity promotes tissue growth and cancers in some circumstances but cell death and tumour suppression in others. Many different regulatory mechanisms help to shape the activity of the Notch pathway, generating functional outputs that are appropriate for each context. These mechanisms include the receptor-ligand landscape, the tissue topology, the nuclear environment and the connectivity of the regulatory networks.

A genetic cell context-dependent role for ZEB1 in lung cancer

The Zinc-finger E-box-binding Homeobox-1 (ZEB1) is a transcription factor that promotes epithelial–mesenchymal transition (EMT) and acts as an oncogene in KRAS-mutated lung cancer models. Here we report that ZEB1 exerts the opposite effect in EGFR-mutated lung cancer cells, where it suppresses growth by increasing microRNA-200 targets to antagonize ERBB3, a driver of mutant EGFR-dependent cell growth. Among these targets, NOTCH1 represses ERBB3 promoter activity and the expression of ERBB3. Furthermore, we find that EGFR inhibitor treatment, which inhibits the growth of EGFR-mutated cells, induces ZEB1. Despite its growth-inhibiting effect, EGFR inhibitor-induced ZEB1 strongly promotes EMT-dependent resistance to EGFR inhibitors partially through NOTCH1, suggesting a multifunctional role for NOTCH1 in EGFR-mutated cells. These results support a previously unrecognized genetic cell context-dependent role for ZEB1 and suggest that NOTCH1 may be a useful target for treating resistance to EGFR inhibitors, especially EMT-driven resistance.

ZEB1 is a driver of epithelial-to-mesenchymal transition that usually promotes lung cancer in the context of KRAS mutation. Here, the authors uncover a growth suppressive role for ZEB1 in EGFR mutant lung adenocarcinoma, thus elucidating the context dependent function of this protein.