miR-17~92 cooperates with RB pathway mutations to promote retinoblastoma

Etiology including epigenetic defects of retinoblastoma

Retinoblastoma (RB), originating from the developing retina, is an aggressive intraocular malignant neoplasm in childhood. Biallelic loss of RB1 is conventionally considered a prerequisite for initiating RB development in most RB cases. Additional genetic mutations arising from genome instability following RB1 mutations are proposed to be required to promote RB development. Recent advancements in high throughput sequencing technologies allow a deeper and more comprehensive understanding of the etiology of RB that additional genetic alterations following RB1 biallelic loss are rare, yet epigenetic changes driven by RB1 loss emerge as a critical contributor promoting RB tumorigenesis. Multiple epigenetic regulators have been found to be dysregulated and to contribute to RB development, including noncoding RNAs, DNA methylations, RNA modifications, chromatin conformations, and histone modifications. A full understanding of the roles of genetic and epigenetic alterations in RB formation is crucial in facilitating the translation of these findings into effective treatment strategies for RB. In this review, we summarize current knowledge concerning genetic defects and epigenetic dysregulations in RB, aiming to help understand their links and roles in RB tumorigenesis.

Insights into the molecular roles of FOXR2 in the pathology of primary pediatric brain tumors

Forkhead box gene R2 (FOXR2) belongs to the family of FOX genes which codes for highly conserved transcription factors (TFs) with critical roles in biological processes ranging from development to organogenesis to metabolic and immune regulation to cellular homeostasis. A number of FOX genes are associated with cancer development and progression and poor prognosis. A growing body of evidence suggests that FOXR2 is an oncogene. Studies suggested important roles for FOXR2 in cancer cell growth, metastasis, and drug resistance. Recent studies showed that FOXR2 is overexpressed by a subset of newly identified entities of embryonal tumors. This review discusses the role(s) FOXR2 plays in the pathology of pediatric brain cancers and its potential as a therapeutic target.

Histopathology and molecular pathology of pediatric pineal parenchymal tumors

Pineal parenchymal tumors in children are rare. They consist of two main types, pineoblastoma (PB) and pineal parenchymal tumor of intermediate differentiation (PPTID), which are World Health Organization (WHO) grade 4 and grade 2-3 respectively. PBs are divided into four distinct molecular groups: PB-miRNA1, PB-miRNA2, PB-RB1, and PB-MYC/FOXR2. PB-RB1 and PB-MYC/FOXR2 affect young children and are associated with a dismal prognosis. PB-miRNA1 and PB-miRNA2 groups affect older children and follow a more favorable course. They are characterized by mutually exclusive alterations in genes involved in miRNA biogenesis, including DICER1, DROSHA, and DGCR8. They may be sporadic or may represent one manifestation of DICER1 syndrome. PB-RB1 tumors show alterations in the RB1 gene and may develop in the setting of congenital retinoblastoma, a condition known as "trilateral retinoblastoma." In the pediatric population, PPTIDs typically affect adolescents. They are characterized by small in-frame insertions in the KBTBD4 gene which is involved in ubiquitination.

Epigenetic Alterations in Canine Malignant Lymphoma: Future and Clinical Outcomes

Canine malignant lymphoma is a common neoplasia in dogs, and some studies have used dogs as a research model for molecular mechanisms of lymphomas in humans. In two species, chemotherapy is the treatment of choice, but the resistance to conventional anticancer drugs is frequent. The knowledge of molecular mechanisms of development and progression of neoplasia has expanded in recent years, and the underlying epigenetic mechanisms are increasingly well known. These studies open up new ways of discovering therapeutic biomarkers. Histone deacetylases and demethylase inhibitors could be a future treatment for canine lymphoma, and the use of microRNAs as diagnosis and prognosis biomarkers is getting closer. This review summarises the epigenetic mechanisms underlying canine lymphoma and their possible application as treatment and biomarkers, both prognostic and diagnostic.

Association of RB1 rs9568036 and CDKN1A rs1801270 Polymorphisms with Retinoblastoma Susceptibility

Purpose

To investigate the association of polymorphisms (rs9568036 and rs1801270) in the RB1 and P21 genes with susceptibility to retinoblastoma (RB).

Methods

This case-control study was designed with 50 patients with RB and 50 controls. Polymerase chain reaction was performed to amplify the intron 17 of RB1 rs9568036 and exon 2 of P21 rs1801270. Then, all the amplified fragments were subjected to directional sequencing, and finally, the association between genotypes and the development of RB risk and invasion was studied.

Results

A statistically significant difference in genotypic or allele frequencies of single-nucleotide polymorphisms (SNPs) (rs1801270 and rs9568036) was found between Iranian RB patients and the controls (P > 0.05). However, the frequency of genotype RB1 rs9568036 observed a statically significant difference in the RB patients compared to the control group, and the nonwild-type allele A increased the chance of susceptibility to developing RB by 2.92 times.

Conclusion

The rs9568036 SNP in the RB1 gene may increase susceptibility to the development of RB in the affected patients. In spite of that, this polymorphism does not influence RB patient's invasion. Further investigation with a large enough sample size is recommended to validate this hypothesis.

Retinoblastoma: Review and new insights

Retinoblastoma (Rb), the most frequent malignant intraocular tumor in childhood, is caused by mutations in the retinoblastoma gene (RB1) situated on chromosome 13q14.2. The incidence of retinoblastoma is approximately 1 in 17,000 live births with approximately 8,000 new cases diagnosed each year worldwide. Rb is the prototypical hereditary cancer in humans. Autosomal dominant inheritance is seen in 30-40% of cases whereas the non-inherited sporadic type accounts for the remaining 60-70%. Rb arises due to inactivation of both alleles of the Rb tumor suppressor gene, which results in a defective Rb protein (pRB) with subsequent cell cycle impairment and uncontrolled cell proliferation. Patients with Rb have survival rates higher than 95-98% in industrialized countries but mortality remains high in developing countries. For example, the mortality rate in Africa is 70%. In all cases of intraocular and extraocular retinoblastoma, there is a need for new therapies that are more effective and carry less risk of toxicity. The Bruckner test is a practical and easy test for the detection of Rb, this test consists of assessing the fundus reflex through the pupil (red reflex) in both eyes simultaneously with a bright coaxial light produced with the direct ophthalmoscope. Rb can be detected by the Bruckner test showing a pupil that shines white or “Leukocoria”. Although the diagnosis of Rb remains essentially clinical, the newly identified biomarkers could contribute to early molecular detection, timely detection of micrometastases and establish new therapeutic options for Rb.

The miR-17-92 cluster: Yin and Yang in human cancers

MicroRNAs (miRNAs) are non-coding RNAs which modulate gene expression via multiple post-transcriptional mechanisms. They are involved in a variety of biological processes, including cell proliferation, metastasis, metabolism, tumorigenesis, and apoptosis. Dysregulation of miRNA expression has been implicated in human cancers, and they may also serve as biomarkers of disease progression and prognosis. The miR-17-92 cluster is one of the most widely studied miRNA clusters, which was initially reported as an oncogene, but was later reported to exhibit tumour suppressive effects in some human cancers. This review summarizes the recent progress and context-dependant role of this cluster in various cancers. We summarize the known mechanisms which regulate miR-17-92 expression and molecular pathways that are in turn controlled by it. We discuss examples where it acts as an oncogene or a tumour suppressor along with key targets affecting hallmarks of cancer. We discuss how cellular contexts regulate the biological effects of miR-17-92. The plausible mechanisms of its paradoxical roles are explained, and mechanisms are described that may contribute to cell fate regulation by miR-17-92. Further, we discuss recently developed strategies to target miR-17-92 cluster in human cancers. MiR-17-92 may serve as a potential biomarker for prognosis and response to therapy as well as a target for cancer prevention and therapeutics.

Comprehensive Analysis of Serum Small Extracellular Vesicles-Derived Coding and Non-Coding RNAs from Retinoblastoma Patients for Identifying Regulatory Interactions

The present study employed nanoparticle tracking analysis, transmission electron microscopy, immunoblotting, RNA sequencing, and quantitative real-time PCR validation to characterize serum-derived small extracellular vesicles (sEVs) from RB patients and age-matched controls. Bioinformatics methods were used to analyze functions, and regulatory interactions between coding and non-coding (nc) sEVs RNAs. The results revealed that the isolated sEVs are round-shaped with a size < 150 nm, 5.3 × 1011 ± 8.1 particles/mL, and zeta potential of 11.1 to −15.8 mV, and expressed exosome markers CD9, CD81, and TSG101. A total of 6514 differentially expressed (DE) mRNAs, 123 DE miRNAs, and 3634 DE lncRNAs were detected. Both miRNA-mRNA and lncRNA-miRNA-mRNA network analysis revealed that the cell cycle-specific genes including CDKNI1A, CCND1, c-MYC, and HIF1A are regulated by hub ncRNAs MALAT1, AFAP1-AS1, miR145, 101, and 16-5p. Protein-protein interaction network analysis showed that eye-related DE mRNAs are involved in rod cell differentiation, cone cell development, and retinol metabolism. In conclusion, our study provides a comprehensive overview of the RB sEV RNAs and regulatory interactions between them.

Overexpression of the miR-17-92 cluster in colorectal adenoma organoids causes a carcinoma-like gene expression signature

Gain of chromosome arm 13q is one of the most prevalent DNA copy number alterations associated with colorectal adenoma-to-carcinoma progression. The oncogenic miR-17-92 cluster, located at 13q, was found to be overexpressed in colorectal cancer and in adenomas harboring 13q gain. However, to what extent overexpression of this group of microRNAs actually drives progression to cancer remains to be resolved. Therefore, we aimed to clarify the role of miR-17-92 cluster in the progression from colorectal adenoma to carcinoma.

The miR-17-92 cluster was overexpressed in human colorectal adenoma organoids without 13q gain and downstream effects on mRNA expression were investigated, along with functional consequences in vitro and in vivo.

Comparison of mRNA sequencing results of organoids overexpressing miR-17-92 and cultures transduced with control vector revealed a miR-17-92 expression signature. This signature appeared to be enriched in an independent series of colorectal cancers and adenomas with 13q gain, confirming that miR-17-92 expression is associated with malignant progression. However, tumor-associated characteristics, such as increased proliferation rate, were not observed in miR-17-92 overexpressing adenoma organoids in vitro. In addition, subcutaneous injection of these organoids in immunodeficient mice was insufficient to cause tumor outgrowth.

In conclusion, this study showed that miR-17-92 expression contributes to 13q gain-associated adenoma-to-carcinoma progression, however, this is insufficient to cause malignancy.

Overexpression of miR-17 predicts adverse prognosis and disease recurrence for acute myeloid leukemia

Background

The clinical significance of miR-17 in patients with acute myeloid leukemia (AML) remains unknown.

Methods

Real-time quantitative reverse transcription-polymerase chain reaction (qPCR) was performed to detect the miR-17 expression in 115 de novo AML patients, 31 patients at complete remission (CR) time, 8 patients at relapse time and 30 normal controls.

Results

MiR-17 was upregulated in de novo AML compared with normal controls. Patients with high expression of miR-17 had less CEBPA double mutation, less favorable ELN-risk and lower CR rate. The level of miR-17 was significantly decreased at CR phase and was returned to primary level even higher when in relapse phase. In addition, Cox regression analysis revealed that miR-17 expression retained independent prognostic significance for overall survival (OS). Moreover, the gene-expression profile analysis of miR-17 in AML obtained from TCGA database was involved in multiple biological functions and signal pathways. Among the differential expressed genes (DEGs), we identified FGL2, PLAUR, SLC2A3, GPR65, CTSS, TLR7, S1PR3, OGFRL1, LILRB1, IL17RA, SIGLEC10, SLAMF7, PLXDC2, HPSE, TCF7 and MYCL as potential direct targets of miR-17 according to in silico analysis.

Conclusions

High expression of miR-17 in de novo AML patients pointed to dismal clinical outcome and disease recurrence, which could serve as novel prognostic biomarker for AML patients.

Regulation of epigenetic homeostasis in uveal melanoma and retinoblastoma

Uveal melanoma (UM) and retinoblastoma (RB), which cause blindness and even death, are the most frequently observed primary intraocular malignancies in adults and children, respectively. Epigenetic studies have shown that changes in the epigenome contribute to the rapid progression of both UM and RB following classic genetic changes. The loss of epigenetic homeostasis plays an important role in oncogenesis by disrupting the normal patterns of gene expression. The targetable nature of epigenetic modifications provides a unique opportunity to optimize treatment paradigms and establish new therapeutic options for both UM and RB with these aberrant epigenetic modifications. We aimed to review the research findings regarding relevant epigenetic changes in UM and RB. Herein, we 1) summarize the literature, with an emphasis on epigenetic alterations, including DNA methylation, histone modifications, RNA modifications, noncoding RNAs and an abnormal chromosomal architecture; 2) elaborate on the regulatory role of epigenetic modifications in biological processes during tumorigenesis; and 3) propose promising therapeutic candidates for epigenetic targets and update the list of epigenetic drugs for the treatment of UM and RB. In summary, we endeavour to depict the epigenetic landscape of primary intraocular malignancy tumorigenesis and provide potential epigenetic targets in the treatment of these tumours.

microRNA-based diagnostic and therapeutic applications in cancer medicine

It has been almost two decades since the first link between microRNAs and cancer was established. In the ensuing years, this abundant class of short noncoding regulatory RNAs has been studied in virtually all cancer types. This tremendously large body of research has generated innovative technological advances for detection of microRNAs in tissue and bodily fluids, identified the diagnostic, prognostic, and/or predictive value of individual microRNAs or microRNA signatures as potential biomarkers for patient management, shed light on regulatory mechanisms of RNA-RNA interactions that modulate gene expression, uncovered cell-autonomous and cell-to-cell communication roles of specific microRNAs, and developed a battery of viral and nonviral delivery approaches for therapeutic intervention. Despite these intense and prolific research efforts in preclinical and clinical settings, there are a limited number of microRNA-based applications that have been incorporated into clinical practice. We review recent literature and ongoing clinical trials that highlight most promising approaches and standing challenges to translate these findings into viable microRNA-based clinical tools for cancer medicine. This article is categorized under: RNA in Disease and Development > RNA in Disease.

Systematically Studying the Effect of Small Molecules Interacting with RNA in Cellular and Preclinical Models

The interrogation and manipulation of biological systems by small molecules is a powerful approach in chemical biology. Ideal compounds selectively engage a target and mediate a downstream phenotypic response. Although historically small molecule drug discovery has focused on proteins and enzymes, targeting RNA is an attractive therapeutic alternative, as many disease-causing or -associated RNAs have been identified through genome-wide association studies. As the field of RNA chemical biology emerges, the systematic evaluation of target validation and modulation of target-associated pathways is of paramount importance. In this Review, through an examination of case studies, we outline the experimental characterization, including methods and tools, to evaluate comprehensively the impact of small molecules that target RNA on cellular phenotype.

MIR17HG genetic variations affect the susceptibility of IgA nephropathy in Chinese Han people

BACKGROUND

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerular disease worldwide. It accounts for approximately 30 ~ 40% of glomerular diseases in China. However, the exact pathogenesis of IgAN is not well established. This study aimed to explore the association between MIR17HG polymorphisms and IgAN susceptibility.

METHODS

Six single nucleotide polymorphisms (SNPs) of MIR17HG were genotyped in 417 patients with IgAN and 424 healthy controls. The association analysis was conducted by logistic regression adjusted for age and gender in multiple genetic models and different subgroups.

RESULTS

Our results revealed that rs72640334 and rs1428 increased the susceptibility to IgAN in total populations (p < 0.05). The stratification analysis by age indicated that rs72640334 enhanced the risk of IgAN people older than 35 years, while rs7318578 played a protective role in the development of IgAN patients aged >35 years (p < 0.05). In addition, MIR17HG-rs72640334 could facilitate the occurrence of IgAN in females (p < 0.05). In Lee's grade III-Vsubgroup, rs72640334 and rs7336610 have an increasing effect on IgAN risk, while rs7318578 has a decreasing effect on IgAN susceptibility (p < 0.05).

CONCLUSIONS

Our findings suggested that MIR17HG genetic polymorphisms were correlated with IgAN susceptibility. It provided new evidence for the potential molecular mechanism of IgAN and may serve as a new biomarker for the treatment and early diagnosis of IgAN.

Retinoblastoma cell-derived exosomes promote angiogenesis of human vesicle endothelial cells through microRNA-92a-3p

Exosomes derived from tumor cells play a key role in tumor development. In the present study, we identified the bioactivity of exosomes released from WERI-Rb1 retinoblastoma cells in tumor angiogenesis, as well as the underlying mechanism, through biochemical methods and animal experiments. Our in vitro data showed that exosomes could be engulfed by human vesicle endothelial cells (HUVECs), significantly promote cell viability and induce an inflammatory response in HUVECs by increasing the expression of a series of related genes, such as IL-1, IL-6, IL-8, MCP-1, VCAM1, and ICAM1. Significant increases in migration and tube formation were also observed in the HUVECs incubated with exosomes. Moreover, experiments with a nude mouse xenotransplantation model showed that exosomes injected near tumors could be strongly absorbed by tumor cells. The numbers of endothelial cells and blood vessels were significantly increased in tumor tissues treated with exosomes compared to control tissues. Furthermore, to reveal the mechanism underlying exosome-mediated angiogenesis in retinoblastoma, we analyzed the levels of 12 microRNAs in the exosomes. Specifically, our data showed that miR-92a-3p was enriched in RB exosomes. Accordingly, miR-92a-3p was increased in the HUVECs incubated with these exosomes. After treatment with a miR-92a-3p inhibitor, the promoting effect of exosomes on the migration and tube formation of HUVECs was significantly abrogated. The expression of the angiogenesis-related genes mentioned above was markedly decreased in HUVECs. Similarly, treatment with a microRNA mimic also demonstrated that miR-92a-3p was involved in the angiogenesis of HUVECs. More importantly, bioinformatics analysis predicted that Krüppel-like factor 2 (KLF2), a member of the KLF family of zinc-finger transcription factors, might be an active target of miR-92a-3p. Notably, this prediction was confirmed both in vitro and in vivo. Thus, our work suggests that exosomal miR-92a-3p is involved in tumor angiogenesis and might be a promising therapeutic candidate for retinoblastoma.

Retinoblastoma tumor cell proliferation is negatively associated with an immune gene expression signature and increased immune cells

This study focuses on gene expression differences between early retinal states that ultimately lead to normal development, late onset retinoblastoma, or rapid bilateral retinoblastoma tumors. The late-onset and early-onset retinoblastoma tumor cells are remarkably similar to normally proliferating retinal progenitor cells, but they fail to properly express differentiation markers associated with normal development. Further, early-onset retinoblastoma tumor cells express a robust immune gene expression signature followed by accumulation of dendritic, monocyte, macrophage, and T-lymphocyte cells in the retinoblastoma tumors. This characteristic was not shared by either normal retinae or late-onset retinoblastomas. Comparison of our data with other human and mouse retinoblastoma tumor gene expression significantly confirmed, that the immune signature is present in tumors from each species. Strikingly, we observed that the immune signature in both mouse and human tumors was most highly evident in those with the lowest proliferative capacity. We directly assessed this relationship in human retinoblastoma tumors by co-analyzing proliferation and immune cell recruitment by immunohistochemistry, uncovering a significant inverse relationship between increased immune-cell infiltration in tumors and reduced tumor cell proliferation. Directly inhibiting proliferation with a PI3K/mTOR inhibitor significantly increased the number of CD45+ immune cells in the retina. This work establishes an in vivo model for the rapid recruitment of immune cells to tumorigenic neural tissue.

Role of MicroRNAs in Human Osteosarcoma: Future Perspectives

Osteosarcoma (OS) is a rare form of cancer with high death rate but is one of the most frequent forms of bone cancer in children and adolescents. MiRNAs are small endogenous RNAs that regulate gene expression post-transcriptionally. The discovery of miRNAs could allow us to obtain an earlier diagnosis, predict prognosis and chemoresistance, and lead to the discovery of new treatments in different types of tumors, including OS. Despite the fact that there is currently only one clinical trial being carried out on a single miRNA for solid tumors, it is very probable that the number of clinical trials including miRNAs as prognostic and diagnostic biomarkers, as well as potential therapeutic targets, will increase in the near future. This review summarizes the different miRNAs related to OS and their possible therapeutic application.

microRNAs as Novel Therapeutics in Cancer

Simple Summary

Over the last few years, we have witnessed incredible advancements in anti-tumor drug development. microRNAs, a class of small non-coding RNAs dysregulated in all cancers, have been recently elected as candidate therapeutics for treating a variety of diseases, including cancer. The scope of this review is to give some insight into the role of the most relevant microRNAs in cancer. We will focus on examining their biological role in tumor development while also providing a broad overview of microRNAs as therapeutics. There is a dedicated focus on the different methods available for microRNA delivery in addition to the efforts being made to increase the specificity of these delivery methods. Finally, we discuss the ongoing clinical trials that are using microRNAs for cancer treatment.

Abstract

In the last 20 years, the functional roles for miRNAs in gene regulation have been well established. MiRNAs act as regulators in virtually all biological pathways and thus have been implicated in numerous diseases, including cancer. They are particularly relevant in regulating the basic hallmarks of cancer, including apoptosis, proliferation, migration, and invasion. Despite the substantial progress made in identifying the molecular mechanisms driving the deregulation of miRNAs in cancer, the clinical translation of these important molecules to therapy remains in its infancy. The paucity of vehicles available for the safe and efficient delivery of miRNAs and ongoing concerns for toxicity remain major obstacles to clinical application. Novel formulations and the development of new vectors have significantly improved the stability of oligonucleotides, increasing the effectiveness of therapy. Furthermore, the use of specific moieties for delivery in target tissues or cells has increased the specificity of treatment. The use of new technologies has allowed small but important steps toward more specific therapeutic delivery in tumor tissues and cells. Although a long road remains, the path ahead holds great potential. Currently, a few miRNA drugs are under investigation in human clinical trials with promising results ahead.

Small molecule recognition of disease-relevant RNA structures

Targeting RNAs with small molecules represents a new frontier in drug discovery and development. The rich structural diversity of folded RNAs offers a nearly unlimited reservoir of targets for small molecules to bind, similar to small molecule occupancy of protein binding pockets, thus creating the potential to modulate human biology. Although the bacterial ribosome has historically been the most well exploited RNA target, advances in RNA sequencing technologies and a growing understanding of RNA structure have led to an explosion of interest in the direct targeting of human pathological RNAs. This review highlights recent advances in this area, with a focus on the design of small molecule probes that selectively engage structures within disease-causing RNAs, with micromolar to nanomolar affinity. Additionally, we explore emerging RNA-target strategies, such as bleomycin A5 conjugates and ribonuclease targeting chimeras (RIBOTACs), that allow for the targeted degradation of RNAs with impressive potency and selectivity. The compounds discussed in this review have proven efficacious in human cell lines, patient-derived cells, and pre-clinical animal models, with one compound currently undergoing a Phase II clinical trial and another that recently garnerd FDA-approval, indicating a bright future for targeted small molecule therapeutics that affect RNA function.

Retinoblastoma Tumor Suppressor Protein Roles in Epigenetic Regulation

Simple Summary

Loss of function of the retinoblastoma gene (RB1) is the rate-limiting step in the initiation of both the hereditary and sporadic forms of retinoblastoma tumor. Furthermore, loss of function of the retinoblastoma tumor suppressor protein (pRB) is frequently found in most human cancers. In retinoblastoma, tumor progression is driven by epigenetic changes following pRB loss. This review focuses on the diverse functions of pRB in epigenetic regulation.

Abstract

Mutations that result in the loss of function of pRB were first identified in retinoblastoma and since then have been associated with the propagation of various forms of cancer. pRB is best known for its key role as a transcriptional regulator during cell cycle exit. Beyond the ability of pRB to regulate transcription of cell cycle progression genes, pRB can remodel chromatin to exert several of its other biological roles. In this review, we discuss the diverse functions of pRB in epigenetic regulation including nucleosome mobilization, histone modifications, DNA methylation and non-coding RNAs.

Prenatal particulate air pollution exposure and expression of the miR-17/92 cluster in cord blood: Findings from the ENVIRONAGE birth cohort

BACKGROUND

Air pollution exposure during pregnancy is an important environmental health issue. Epigenetics mediate the effects of prenatal exposure and could increase disease predisposition in later life. The oncogenic miR-17/92 cluster is involved in normal development and disease.

OBJECTIVES

Here, for the first time the potential prenatal effects of particulate matter with a diameter<2.5 μm (PM_2.5) exposure on expression of the miR-17/92 cluster in cord blood are explored.

METHODS

In 370 mother-newborn pairs from the ENVIRONAGE birth cohort, expression of three members of the miR-17/92 cluster was measured in cord blood by qRT-PCR. Expression of C-MYC and CDKN1A, a cluster activator and a target gene, respectively, was also analyzed. Multivariable linear regression models were used to associate the relative m(i)RNA expression with prenatal PM_2.5 exposure.

RESULTS

PM_2.5 exposure averaged (10^th-90^th percentile) 11.7 (9.0-14.4) µg/m³ over the entire pregnancy. In cord blood, miR-17 and miR-20a showed a -45.0% (95%CI: -55.9 to -31.4, p < 0.0001) and a -33.7% (95%CI: -46.9 to -17.2, p = 0.0003), decrease in expression in association with first trimester PM_2.5 exposure, and a -32.5% (95%CI: -45.6 to -16.3, p = 0.0004) and -23.3% (95%CI: -38.1 to -4.8, p = 0.02), respectively, decrease in expression in association with PM_2.5 exposure during the entire pregnancy. In association with third trimester PM_2.5 exposure, a reduction of -25.8% (95%CI: -40.2 to -8.0, p = 0.007) and -14.2% (95%CI: -27.7 to 1.9, p = 0.08), for miR-20a and miR-92a expression, respectively, was identified. Only miR-92a expression (-15.7%, 95%CI: -27.3 to -2.4, p = 0.02) was associated with PM_2.5 exposure during the last month of pregnancy. C-MYC expression was downregulated in cord blood in association with prenatal PM_2.5 exposure during the first trimester and the entire pregnancy, in the adjusted model.

DISCUSSION

Lower expression levels of the miR-17/92 cluster in cord blood in association with increased prenatal PM_2.5 exposure were observed. Whether this oncogenic microRNA cluster plays a role in trans-placental carcinogenesis remains to be elucidated.

MicroRNA-19a-PTEN Axis Is Involved in the Developmental Decline of Axon Regenerative Capacity in Retinal Ganglion Cells

Irreversible blindness from glaucoma and optic neuropathies is attributed to retinal ganglion cells (RGCs) losing the ability to regenerate axons. While several transcription factors and proteins have demonstrated enhancement of axon regeneration after optic nerve injury, mechanisms contributing to the age-related decline in axon regenerative capacity remain elusive. In this study, we show that microRNAs are differentially expressed during RGC development and identify microRNA-19a (miR-19a) as a heterochronic marker; developmental decline of miR-19a relieves suppression of phosphatase and tensin homolog (PTEN), a key regulator of axon regeneration, and serves as a temporal indicator of decreasing axon regenerative capacity. Intravitreal injection of miR-19a promotes axon regeneration after optic nerve crush in adult mice, and it increases axon extension in RGCs isolated from aged human donors. This study uncovers a previously unrecognized involvement of the miR-19a-PTEN axis in RGC axon regeneration, and it demonstrates therapeutic potential of microRNA-mediated restoration of axon regenerative capacity in optic neuropathies.

Identification of microRNA-mRNA regulatory networks and pathways related to retinoblastoma across human and mouse

AIM

To explore the mRNA and pathways related to retinoblastoma (RB) genesis and development.

METHODS

Microarray datasets GSE29683 (human) and GSE29685 (mouse) were downloaded from NCBI GEO database. Homologous genes between the two species were identified using WGCNA, followed by protein-protein interaction (PPI) network construction and gene enrichment analysis. Disease-related miRNAs and pathways were retrieved from miR2Disease database and Comparative Toxicogenomics Database (CTD), respectively.

RESULTS

A total of 352 homologous genes were identified. Two pathways including "cell cycle" and "pathway in cancer" in CTD and enrichment analysis were identified and seven miRNAs (including hsa-miR-373, hsa-miR-34a, hsa-miR-129, hsa-miR-494, hsa-miR-503, hsa-let-7 and hsa-miR-518c) were associated with RB. miRNAs modulate "cell cycle" and "pathway in cancer" pathways via regulating 13 genes (including CCND1, CDC25C, E2F2, CDKN2D and TGFB2).

CONCLUSION

These results suggest that these miRNAs play crucial roles in RB genesis through "cell cycle" and "pathway in cancer" pathways by regulating their targets including CCND1, CDC25C, E2F2 and CDKN2D.

Targeted Degradation of the Oncogenic MicroRNA 17-92 Cluster by Structure-Targeting Ligands

Many RNAs are processed into biologically active transcripts, the aberrant expression of which can contribute to disease phenotypes. For example, the primary microRNA-17-92 (pri-miR-17-92) cluster contains six microRNAs (miRNAs) that collectively act in several disease settings. Herein, we used sequence-based design of structure-specific ligands to target a common structure in the Dicer processing sites of three miRNAs in the cluster, miR-17, miR-18a, and miR-20a, thereby inhibiting their biogenesis. The compound was optimized to afford a dimeric molecule that binds the Dicer processing site and an adjacent bulge, affording a 100-fold increase in potency. The dimer's mode of action was then extended from simple binding to direct cleavage by conjugation to bleomycin A5 in a manner that imparts RNA-selective cleavage or to indirect cleavage by recruiting an endogenous nuclease, or a ribonuclease targeting chimera (RIBOTAC). Interestingly, the dimer-bleomycin conjugate cleaves the entire pri-miR-17-92 cluster and hence functionally inhibits all six miRNAs emanating from it. The compound selectively reduced levels of the cluster in three disease models: polycystic kidney disease, prostate cancer, and breast cancer, rescuing disease-associated phenotypes in the latter two. Further, the bleomycin conjugate exerted selective effects on the miRNome and proteome in prostate cancer cells. In contrast, the RIBOTAC only depleted levels of pre- and mature miR-17, -18a, and 20a, with no effect on the primary transcript, in accordance with the cocellular localization of RNase L, the pre-miRNA targets, and the compound. These studies demonstrate a strategy to tune RNA structure-targeting compounds to the cellular localization of the target.

Biomarkers in retinoblastoma

Retinoblastoma (RB) is the most common intraocular malignancy of childhood caused by inactivation of the Rb genes. The prognosis of RB is better with an earlier diagnosis. Many diagnostic approaches and appropriate clinical treatments have been developed to improve clinical outcomes. However, limitations exist when utilizing current methods. Recently, many studies have identified identify new RB biomarkers which can be used in diagnosis, as prognostic indicators and may contribute to understanding the pathogenesis of RB and help determine specific treatment strategies. This review focuses on recent advances in the discovery of RB biomarkers and discusses their clinical utility and challenges from areas such as epigenetics, proteomics and radiogenomics.

Pineoblastoma segregates into molecular sub-groups with distinct clinico-pathologic features: a Rare Brain Tumor Consortium registry study

Pineoblastomas (PBs) are rare, aggressive pediatric brain tumors of the pineal gland with modest overall survival despite intensive therapy. We sought to define the clinical and molecular spectra of PB to inform new treatment approaches for this orphan cancer. Tumor, blood, and clinical data from 91 patients with PB or supratentorial primitive neuroectodermal tumor (sPNETs/CNS-PNETs), and 2 pineal parenchymal tumors of intermediate differentiation (PPTIDs) were collected from 29 centres in the Rare Brain Tumor Consortium. We used global DNA methylation profiling to define a core group of PB from 72/93 cases, which were delineated into five molecular sub-groups. Copy number, whole exome and targeted sequencing, and miRNA expression analyses were used to evaluate the clinico-pathologic significance of each sub-group. Tumors designated as group 1 and 2 almost exclusively exhibited deleterious homozygous loss-of-function alterations in miRNA biogenesis genes (DICER1, DROSHA, and DGCR8) in 62 and 100% of group 1 and 2 tumors, respectively. Recurrent alterations of the oncogenic MYC-miR-17/92-RB1 pathway were observed in the RB and MYC sub-group, respectively, characterized by RB1 loss with gain of miR-17/92, and recurrent gain or amplification of MYC. PB sub-groups exhibited distinct clinical features: group 1-3 arose in older children (median ages 5.2-14.0 years) and had intermediate to excellent survival (5-year OS of 68.0-100%), while Group RB and MYC PB patients were much younger (median age 1.3-1.4 years) with dismal survival (5-year OS 37.5% and 28.6%, respectively). We identified age < 3 years at diagnosis, metastatic disease, omission of upfront radiation, and chr 16q loss as significant negative prognostic factors across all PBs. Our findings demonstrate that PB exhibits substantial molecular heterogeneity with sub-group-associated clinical phenotypes and survival. In addition to revealing novel biology and therapeutics, molecular sub-grouping of PB can be exploited to reduce treatment intensity for patients with favorable biology tumors.

Targeting Transient Receptor Potential Channels by MicroRNAs Drives Tumor Development and Progression

Transient receptor potential (TRP) cation channel superfamily plays important roles in a variety of cellular processes such polymodal cellular sensing, adhesion, polarity, proliferation, differentiation and apoptosis. The expression of TRP channels is strictly regulated and their de-regulation can stimulate cancer development and progression.In human cancers, specific miRNAs are expressed in different tissues, and changes in the regulation of gene expression mediated by specific miRNAs have been associated with carcinogenesis. Several miRNAs/TRP channel pairs have been reported to play an important role in tumor biology. Thus, the TRPM1 gene regulates melanocyte/melanoma behaviour via TRPM1 and microRNA-211 transcripts. Both miR-211 and TRPM1 proteins are regulated through microphthalmia-associated transcription factor (MIFT) and the expression of miR-211 is decreased during melanoma progression. Melanocyte phenotype and melanoma behaviour strictly depend on dual TRPM1 activity, with loss of TRPM1 protein promoting melanoma aggressiveness and miR-211 expression supporting tumour suppressor. TRPM3 plays a major role in the development and progression of human clear cell renal cell carcinoma (ccRCC) with von Hippel-Lindau (VHL) loss. TRPM3, a direct target of miR-204, is enhanced in ccRCC with inactivated or deleted VHL. Loss of VHL inhibits miR-204 expression that lead to increased oncogenic autophagy. Therefore, the understanding of specific TRP channels/miRNAs molecular pathways in distinct tumors could provide a clinical rationale for target therapy in cancer.

Non-Coding RNAs in Pediatric Solid Tumors

Pediatric solid tumors are a diverse group of extracranial solid tumors representing approximately 40% of childhood cancers. Pediatric solid tumors are believed to arise as a result of disruptions in the developmental process of precursor cells which lead them to accumulate cancerous phenotypes. In contrast to many adult tumors, pediatric tumors typically feature a low number of genetic mutations in protein-coding genes which could explain the emergence of these phenotypes. It is likely that oncogenesis occurs after a failure at many different levels of regulation. Non-coding RNAs (ncRNAs) comprise a group of functional RNA molecules that lack protein coding potential but are essential in the regulation and maintenance of many epigenetic and post-translational mechanisms. Indeed, research has accumulated a large body of evidence implicating many ncRNAs in the regulation of well-established oncogenic networks. In this review we cover a range of extracranial solid tumors which represent some of the rarer and enigmatic childhood cancers known. We focus on two major classes of ncRNAs, microRNAs and long non-coding RNAs, which are likely to play a key role in the development of these cancers and emphasize their functional contributions and molecular interactions during tumor formation.

MiR-25-3p promotes malignant phenotypes of retinoblastoma by regulating PTEN/Akt pathway

Aberrant expression of microRNAs plays an important role in the pathogenesis and progression of retinoblastoma. MiR-25, a member of the miR-106b˜25 cluster, has been reported to be abnormally expressed in retinoblastoma, but the exact role of it remains unclear. In our study, we found that miR-25-3p was upregulated in retinoblastoma tissues and cell lines. Enforced expression of miR-25-3p in retinoblastoma cell line WERI-RB-1 increased cell growth, colony formation, anchorage-independent growth, cell migration and invasion in vitro and tumor xenograft growth in vivo. In contrast, inhibited miR-25-3p expression in retinoblastoma cell line Y79 suppressed cell growth, colony formation, anchorage-independent growth, cell migration and invasion. Through luciferase reporter assay, we found that phosphatase and tensin homolog (PTEN) was a direct target of miR-25-3p. This was verified by western blot that miR-25-3p overexpression suppressed PTEN and activated Akt signaling. In addition, miR-25-3p was found to promote epithelial-mesenchymal transition (EMT) of WERI-RB-1 cells through PTEN/Akt pathway. Western blot analysis revealed that miR-25-3p overexpression increased Vimentin and Snail expression, and suppressed E-cadherin expression, but this could be reversed by restoring PTEN. Moreover, LY294002 treatment or restoring PTEN expression abolished the effects of miR-25-3p on cell invasion, colony formation and anchorage-independent growth in vitro and tumor xenograft growth in vivo. Taken together, our results suggested that miR-25-3p promotes malignant transformation of retinoblastoma cells by suppressing PTEN.

MiR-17 and miR-19 cooperatively promote skeletal muscle cell differentiation

Skeletal myogenesis is a highly coordinated process that involves cell proliferation, differentiation and fusion controlled by a complex gene regulatory network. The microRNA gene cluster miR-17–92 has been shown to be related to this process; however, the exact role of each cluster member remains unclear. Here, we show that miR-17 and miR-20a could effectively promote the differentiation of both C2C12 myoblasts and primary bovine satellite cells. In contrast, miR-18a might play a negative role in C2C12 cell differentiation, while miR-19 and miR-92a had little influence. Transcriptome and target analyses revealed that miR-17 could act on Ccnd2, Jak1 and Rhoc genes that are critical for cell proliferation and/or fusion. Notably, the addition of miR-19 could reverse the lethal effect of miR-17 and could thus facilitate the maturation of myotubes. Furthermore, by co-injecting the lentiviral shRNAs of miR-17 and miR-19 into mouse tibialis anterior muscles, we demonstrated the wound healing abilities of the two miRNAs. Our findings indicate that in combination with miR-19, miR-17 is a potent inducer of skeletal muscle differentiation.

Overexpression of microRNA-186 inhibits angiogenesis in retinoblastoma via the Hedgehog signaling pathway by targeting ATAD2

Retinoblastoma (RB) represents an aggressive malignancy in the eye during the period of infancy and childhood. We delineated the ability of microRNA-186 (miR-186) to influence viability, invasion, migration, angiogenesis, and apoptosis of RB via the Hedgehog signaling pathway by targeting AAA domain-containing protein 2 (ATAD2). The microarray-based analysis was adopted to identify differentially expressed genes (DEGs) related to RB. Subsequently, RB cells were treated with miR-186 mimic, miR-186 inhibitor, or si-ATAD2. The expression of miR-186, ATAD2, Hedgehog signaling pathway-related genes were evaluated, and the target relationship between miR-186 and ATAD2 was verified. Finally, cell proliferation, invasion, migration, apoptosis, and angiogenesis were assessed. ATAD2 was identified as a DEG and modulated by miR-186. Moreover, we revealed that ATAD2 was highly expressed, whereas miR-186 was lowly expressed, and the Hedgehog signaling pathway was activated in RB. Then, ATAD2 as a putative target of miR-186 was validated using a luciferase assay. miR-186 mimic or siRNA-ATAD2 in RB cells reduced cell viability, invasion, and migration coordinating with elevated apoptosis via impairing the Hedgehog signaling pathway, where repressed angiogenesis was observed. Overexpression of miR-186 attenuates RB via the inactivation of the Hedgehog signaling pathway by downregulating ATAD2.

miR-20a inhibits hypoxia-induced autophagy by targeting ATG5/FIP200 in colorectal cancer

Autophagy is a highly conserved lysosome-mediated protective cellular process in which cytosolic components, including damaged organelles and long-lived proteins, are cleared. Many studies have shown that autophagy was upregulated in hypoxic regions. However, the precise molecular mechanism of hypoxia-induced autophagy in colorectal cancer (CRC) is still elusive. In this study, we found that miR-20a was significantly downregulated under hypoxia in colon cancer cells, and overexpression of miR-20a alleviated hypoxia-induced autophagy. Moreover, miR-20a inhibits the hypoxia-induced autophagic flux by targeting multiple key regulators of autophagy, including ATG5 and FIP200. Furthermore, by dual-luciferase assay we demonstrated that miR-20a directly targeted the 3'-untranslated region of ATG5 and FIP200, regulating their messenger RNA and protein levels. In addition, reintroduction of exogenous ATG5 or FIP200 partially reversed miR-20a-mediated autophagy inhibition under hypoxia. A negative correlation between miR-20a and its target genes is observed in the hypoxic region of colon cancer tissues. Taken together, our findings suggest that hypoxia-mediated autophagy was regulated by miR-20a/ATG5/FI200 signaling pathway in CRC. miR-20a-mediated autophagy defect that might play an important role in hypoxia-induced autophagy during colorectal tumorigenesis.

Expression Profiling Analysis Reveals Key MicroRNA-mRNA Interactions in Early Retinal Degeneration in Retinitis Pigmentosa

Purpose

The aim of this study was to identify differentially expressed microRNAs (miRNAs) that might play an important role in the etiology of retinal degeneration in a genetic mouse model of retinitis pigmentosa (rd10 mice) at initial stages of the disease.

Methods

miRNAs–mRNA interaction networks were generated for analysis of biological pathways involved in retinal degeneration.

Results

Of more than 1900 miRNAs analyzed, we selected 19 miRNAs on the basis of (1) a significant differential expression in rd10 retinas compared with control samples and (2) an inverse expression relationship with predicted mRNA targets involved in biological pathways relevant to retinal biology and/or degeneration. Seven of the selected miRNAs have been associated with retinal dystrophies, whereas, to our knowledge, nine have not been previously linked to any disease.

Conclusions

This study contributes to our understanding of the etiology and progression of retinal degeneration.

Retinoblastoma, the visible CNS tumor: A review

The pediatric ocular cancer retinoblastoma is the only central nervous system (CNS) tumor readily observed without specialized equipment: it can be seen by, and in, the naked eye. This accessibility enables unique imaging modalities. Here, we review this cancer for a neuroscience audience, highlighting these clinical and research imaging options, including fundus imaging, optical coherence tomography, ultrasound, and magnetic resonance imaging. We also discuss the subtype of retinoblastoma driven by the MYCN oncogene more commonly associated with neuroblastoma, and consider trilateral retinoblastoma, in which an intracranial tumor arises along with ocular tumors in patients with germline RB1 gene mutations. Retinoblastoma research and clinical care can offer insights applicable to CNS malignancies, and also benefit from approaches developed elsewhere in the CNS.

LncRNA XIST promotes the epithelial to mesenchymal transition of retinoblastoma via sponging miR-101

Accumulating evidence demonstrated that abnormal expression of long non-coding RNAs (lncRNAs) was closely associated with cancer development including retinoblastoma (RB). LncRNA X inactive specific transcript (XIST) has been found to function as an oncogene or a tumor suppressor in several cancers. However, the role and underlying mechanism of XIST in RB have not been clarified. The expression of XIST, microRNA (miR)- 101, zinc finger E-box binding homeobox (ZEB) 1, and ZEB2 was detected in human RB tissues and cell lines. The effects of XIST on the proliferation, migration, invasion, epithelial to mesenchymal transition (EMT), and apoptosis of RB cells were evaluated after downregulation of XIST. Furthermore, the mechanism of XIST was mainly focused on miR-101/ZEB1 or ZEB2 signaling. We found the expression of XIST, ZEB1 and ZEB2 was increased, whereas miR-101 was reduced in RB tissues and cells. Knockdown of XIST significantly suppressed the proliferation, migration, invasion and EMT, but promoted the apoptosis and caspase-3 activity. Moreover, we found that XIST functioned as a competing endogenous RNA (ceRNA) for miR-101 to regulate the de-repression of its endogenous targets ZEB1 and ZEB2. In conclusion, these findings suggest that XIST may facilitate the progression of RB through acting as a ceRNA for miR-101 to mediate the expression of ZEB1 and ZEB2. This may provide novel therapeutic options for RB.

Expression profiles and prognostic value of miRNAs in retinoblastoma

Current cure rates for retinoblastoma (RB) are very high in developed countries. Nonetheless, in less privileged places worldwide, delayed diagnosis and refusal to adhere to treatment still endure an obstacle to improve overall patient survival. Thus, the access to consistent biomarkers for diagnosis at an earlier stage may facilitate treatment and improve outcomes. Over recent years, much attention has been focused on miRNAs, key post-transcriptional regulators that when altered, largely contribute to carcinogenesis and tumor progression. Many of the ~ 2500 microRNAs described in humans have shown differential expression profiles in tumors. In this review, we summarize current data about the roles of miRNAs in RB along with their value as diagnostic/prognostic factors using electronic databases such as PubMed. We reviewed the importance of miRNA in RB biology and discussed their implications in clinic intervention. Several miRNAs have pointed out reliable diagnostic and prognostic molecular biomarkers. The emergence of targeted therapies has significantly improved cancer treatment. In the near future, the modulation of miRNAs will represent a good treatment strategy.

Noncoding RNAs in disease

Noncoding RNAs are emerging as potent and multifunctional regulators in all biological processes. In parallel, a rapidly growing number of studies has unravelled associations between aberrant noncoding RNA expression and human diseases. These associations have been extensively reviewed, often with the focus on a particular microRNA (miRNA) (family) or a selected disease/pathology. In this Mini‐Review, we highlight a selection of studies in order to demonstrate the wide‐scale involvement of miRNAs and long noncoding RNAs in the pathophysiology of three types of diseases: cancer, cardiovascular and neurological disorders. This research is opening new avenues to novel therapeutic approaches.

Clustered miRNAs and their role in biological functions and diseases

MicroRNAs (miRNAs) are endogenous, small non-coding RNAs known to regulate expression of protein-coding genes. A large proportion of miRNAs are highly conserved, localized as clusters in the genome, transcribed together from physically adjacent miRNAs and show similar expression profiles. Since a single miRNA can target multiple genes and miRNA clusters contain multiple miRNAs, it is important to understand their regulation, effects and various biological functions. Like protein-coding genes, miRNA clusters are also regulated by genetic and epigenetic events. These clusters can potentially regulate every aspect of cellular function including growth, proliferation, differentiation, development, metabolism, infection, immunity, cell death, organellar biogenesis, messenger signalling, DNA repair and self-renewal, among others. Dysregulation of miRNA clusters leading to altered biological functions is key to the pathogenesis of many diseases including carcinogenesis. Here, we review recent advances in miRNA cluster research and discuss their regulation and biological functions in pathological conditions.

Retinoblastoma cells activate the AKT pathway and are vulnerable to the PI3K/mTOR inhibitor NVP-BEZ235

Retinoblastoma is a pediatric cancer of the retina most often caused by inactivation of the retinoblastoma (RB1) tumor suppressor gene. We previously showed that Rb1 loss cooperates with either co-activating the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, or co-deleting Pten, to initiate retinoblastoma tumors in mice. The objectives of this study were to determine if the AKT pathway is activated in human retinoblastomas and the extent that anti-PI3K therapy induces apoptosis in retinoblastoma cells, alone or in combination with the DNA damaging drugs carboplatin and topotecan. Serial sections from human retinoblastoma tissue microarrays containing 27 tumors were stained with antibodies specific to p-AKT, Ki-67, forkhead box O1 (p-FOXO1), and ribosomal protein S6 (p-S6) using immunohistochemistry and each tumor sample scored for intensity. Human retinoblastoma tumors displayed significant correlation between p-AKT intensity with highly proliferative tumors (p = 0.008) that were also highly positive for p-FOXO1 (p = 0.002). Treatment with BEZ235, a dual PI3K/mTOR inhibitor, reduced phosphorylation levels of the AKT targets p-FOXO and p-S6 and effectively induced apoptosis the Y79 and Weri-1 human retinoblastoma cell lines and in vivo in our retinoblastoma mouse model. Long-term treatment with BEZ235 in vivo using our retinoblastoma-bearing mice induced apoptosis but did not significantly extend the lifespan of the mice. We then co-administered BEZ235 with topotecan and carboplatin chemotherapeutics in vivo, which more effectively induced apoptosis of retinoblastoma, but not normal retinal cells than either treatment alone. Our study has increased the variety of potentially effective targeted treatments that can be considered for human retinoblastoma.

MicroRNAs of the mir-17~92 cluster regulate multiple aspects of pancreatic tumor development and progression

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy characterized by resistance to currently employed chemotherapeutic approaches. Members of the mir-17~92 cluster of microRNAs (miRNAs) are upregulated in PDAC, but the precise roles of these miRNAs in PDAC are unknown. Using genetically engineered mouse models, we show that loss of mir-17~92 reduces ERK pathway activation downstream of mutant KRAS and promotes the regression of KRAS^G12D-driven precursor pancreatic intraepithelial neoplasias (PanINs) and their replacement by normal exocrine tissue. In a PDAC model driven by concomitant KRAS^G12D expression and Trp53 heterozygosity, mir-17~92 deficiency extended the survival of mice that lacked distant metastasis. Moreover, mir-17~92-deficient PDAC cell lines display reduced invasion activity in transwell assays, form fewer invadopodia rosettes than mir-17~92-competent cell lines and are less able to degrade extracellular matrix. Specific inhibition of miR-19 family miRNAs with antagomirs recapitulates these phenotypes, suggesting that miR-19 family miRNAs are important mediators of PDAC cell invasion. Together these data demonstrate an oncogenic role for mir-17~92 at multiple stages of pancreatic tumorigenesis and progression; specifically, they link this miRNA cluster to ERK pathway activation and precursor lesion maintenance in vivo and identify a novel role for miR-19 family miRNAs in promoting cancer cell invasion.

Regulatory landscape and clinical implication of MBD3 in human malignant glioma

In this article we inspect the roles and functions of the methyl-CpG-binding domain protein 3 (MBD3) in human malignant glioma, to assess its potential as an epigenetic biomarker for prognosis. The regulatory effects of MBD3 on glioma transcriptome were first profiled by high-throughput microarray. Our results indicate that MBD3 is involved in both transcriptional activation and repression. Furthermore, MBD3 fine-controls a spectrum of proteins critical for cellular metabolism and proliferation, thereby contributing to an exquisite anti-glioma network. Specifically, the expression of MHC class II molecules was found to positively correlate with MBD3, which provides new insight into the immune escape of gliomagenesis. In addition, MBD3 participates in constraining a number of oncogenic non-coding RNAs whose over-activation could drive cells into excessive growth and higher malignancy. Having followed up a pilot cohort, we noted that the survival of malignant glioma patients was proportional to the content of MBD3 and 5-hydroxymethylcytosine (5hmC) in their tumor cells. The progression-free survival (PFS) and overall survival (OS) were relatively poor for patients with lower amount of MBD3 and 5hmC in the tissue biopsies. Taken together, this work enriches our understanding of the mechanistic involvement of MBD3 in malignant glioma.

Alteration in microRNA-17-92 dynamics accounts for differential nature of cellular proliferation

MicroRNAs associated with the mir-17-92 cluster are crucial regulators of the mammalian cell cycle, as they inhibit transcription factors related to the E2F family that tightly control decision-making events for a cell to commit for active cellular proliferation. Intriguingly, in many solid cancers, these mir-17-92 cluster members are overexpressed, whereas in some hematopoietic cancers they are down-regulated. Our proposed model of the Myc/E2F/mir-17-92 network demonstrates that the differential expression pattern of mir-17-92 in different cell types can be conceived due to having a contrasting E2F dynamics induced by mir-17-92. The model predicts that by explicitly altering the mir-17-92-related part of the network, experimentally it is possible to control cellular proliferation in a cell type-dependent manner for therapeutic intervention.

Long non-coding RNA H19 suppresses retinoblastoma progression via counteracting miR-17-92 cluster

Long non-coding RNAs (lncRNAs) are frequently dysregulated and play important roles in many cancers. lncRNA H19 is one of the earliest discovered lncRNAs which has diverse roles in different cancers. However, the expression, roles, and action mechanisms of H19 in retinoblastoma are still largely unknown. In this study, we found that H19 is downregulated in retinoblastoma tissues and cell lines. Gain-of-function and loss-of-function assays showed that H19 inhibits retinoblastoma cell proliferation, induces retinoblastoma cell cycle arrest and cell apoptosis. Mechanistically, we identified seven miR-17-92 cluster binding sites on H19, and found that H19 directly bound to miR-17-92 cluster via these seven binding sites. Through binding to miR-17-92 cluster, H19 relieves the suppressing roles of miR-17-92 cluster on p21. Furthermore, H19 represses STAT3 activation induced by miR-17-92 cluster. Hence, our results revealed that H19 upregulates p21 expression, inhibits STAT3 phosphorylation, and downregulates the expression of STAT3 target genes BCL2, BCL2L1, and BIRC5. In addition, functional assays demonstrated that the mutation of miR-17-92 cluster binding sites on H19 abolished the proliferation inhibiting, cell cycle arrest and cell apoptosis inducing roles of H19 in retinoblastoma. In conclusion, our data suggested that H19 inhibits retinoblastoma progression via counteracting the roles of miR-17-92 cluster, and implied that enhancing the action of H19 may be a promising therapeutic strategy for retinoblastoma.

miR-19 promotes osteosarcoma progression by targeting SOCS6

microRNAs (miRNAs) play critical roles in cancer development and progression. This study investigated the effects of miR-19 in human osteosarcoma (OS) development. Here, we showed that miR-19 was frequently upregulated in OS tissues and cell lines. Moreover the expression of miR-19 was associated with TNM stage, metastasis, size and poor overall survival. Mechanistically, miR-19 dramatically suppressed OS growth in vitro and in vivo. Bioinformatics analyses predicted that SOCS6 is a potential target gene of miR-19 in OS, which was confirmed by luciferase-reporter assay. We also found that SOCS6 expression was downregulated and negatively correlated with miR-19 expression in OS tissues clinically. Moreover, ectopic SOCS6 could reverse miR-19 induced OS growth. Finally, JAK2/STAT3 signaling pathway involves miR-19/SOCS6-mediated OS progression. Together, our data provide important evidence for miR-19 mediated SOCS6 in OS growth and revealed miR-19/SOCS6/JAK2/STAT3 pathway as a potential therapeutic strategy for OS patients.

DNA Methylomes Reveal Biological Networks Involved in Human Eye Development, Functions and Associated Disorders

This work provides a comprehensive CpG methylation landscape of the different layers of the human eye that unveils the gene networks associated with their biological functions and how these are disrupted in common visual disorders. Herein, we firstly determined the role of CpG methylation in the regulation of ocular tissue-specification and described hypermethylation of retinal transcription factors (i.e., PAX6, RAX, SIX6) in a tissue-dependent manner. Second, we have characterized the DNA methylome of visual disorders linked to internal and external environmental factors. Main conclusions allow certifying that crucial pathways related to Wnt-MAPK signaling pathways or neuroinflammation are epigenetically controlled in the fibrotic disorders involved in retinal detachment, but results also reinforced the contribution of neurovascularization (ETS1, HES5, PRDM16) in diabetic retinopathy. Finally, we had studied the methylome in the most frequent intraocular tumors in adults and children (uveal melanoma and retinoblastoma, respectively). We observed that hypermethylation of tumor suppressor genes is a frequent event in ocular tumors, but also unmethylation is associated with tumorogenesis. Interestingly, unmethylation of the proto-oncogen RAB31 was a predictor of metastasis risk in uveal melanoma. Loss of methylation of the oncogenic mir-17-92 cluster was detected in primary tissues but also in blood from patients.

miR106b regulates retinoblastoma Y79 cells through Runx3

MicroRNAs are increasingly recognized as important regulators of cancer. The aim of the present study was to investigate the role of miR-106b in the regulation of Y79 retinoblastoma. Y79 cells were transfected with antisense oligonucleotides (ASO) against miR-106b (ASO-miR-106b) or ASO-control. After transfection, the levels of miR-106b were monitored with real-time PCR (RT-PCR). The effects of ASO-miR-106b transfection on cell viability was evaluated by Cell Counting Kit-8 (CCK-8) analysis at 24, 48 and 72 h after transfection. Subsequently, the cells were stained with Annexin V-FITC and propidium iodide (PI) and subjected to flow cytometry to assess cell apoptosis. Transwell assay was used to analyze cell migration. Changes in Runt-related transcription factor 3 (Runx3) mRNA and proteins levels were also evaluated. miR-106b was downregulated by ASO-miR-106b at 48 and 72 h after transfection, accompanied by a decrease in cell viability and proliferation, as well as an increase in cell apoptosis. Transwell analysis indicated that cells treated with ASO-miR-106b exhibited significantly lower cell migratory abilities. The mRNA and protein level of Runx3 were upregulated after transfection. These results demonstrated that suppression of miR-106b inhibited Y79 cell proliferation and migration. The upregulation of Runx3 after miR-106b suppression ascertained that Runx3 is a tumor-suppressor in retinoblastoma and is a target of miR-106b.

STAT3 is required for MiR-17-5p-mediated sensitization to chemotherapy-induced apoptosis in breast cancer cells

Signal transducer and activator of transcription 3 (STAT3) controls cell survival, growth, migration, and invasion. Here, we observed that STAT3 exerted anti-apoptotic effects in breast cancer cells. On the other hand, miR-17-5p induced apoptosis in breast cancer cells, and overexpression of miR-17-5p sensitized MCF-7 cells to paclitaxel-induced apoptosis via STAT3. Overexpression of STAT3 in MCF-7 cells decreased paclitaxel-induced apoptosis, but STAT3 knockout abolished the miR-17-5p-induced increases in apoptosis. Finally, miR-17-5p promoted apoptosis by increasing p53 expression, which was inhibited by STAT3. These results demonstrate a novel pathway via which miR-17-5p inhibits STAT3 and increases p53 expression to promote apoptosis in breast cancer cells.