Concerted microRNA control of Hedgehog signalling in cerebellar neuronal progenitor and tumour cells

MiR-326: Role and significance in brain cancers

MicroRNAs (miRNAs) are small non-coding RNAs that act as critical regulators of gene expression by repressing mRNA translation. The role of miRNAs in cell physiology spans from cell cycle control to cell proliferation and differentiation, both during development and in adult tissues. Accordingly, dysregulated expression of miRNAs has been reported in several diseases, including cancer, where miRNAs can act as oncogenes or oncosuppressors. Of note, miRNA signatures are also under investigation for classification, diagnosis, and prognosis of cancer patients. Brain tumours are primarily associated with poor prognosis and high mortality, highlighting an urgent need for novel diagnostic, prognostic, and therapeutic tools. Among miRNAs investigated in brain tumours, miR-326 has been shown to act as a tumour suppressor in adult and paediatric brain cancers. In this review, we describe the role of miR-326 in malignant as well as benign cancers originating from brain tissue. In addition, since miR-326 expression can be regulated by other non-coding RNA species, adding a further layer of regulation in the cancer-promoting axis, we discuss this miRNA's role in targeted therapy for brain cancers.

MicroRNA dysregulation in glutamate and dopamine pathways of schizophrenia: From molecular pathways to diagnostic and therapeutic approaches

Schizophrenia is a complex psychiatric disorder, and genetic and environmental factors have been implicated in its development. Dysregulated glutamatergic and dopaminergic transmission pathways are involved in schizophrenia development. Besides genetic mutations, epigenetic dysregulation has a considerable role in dysregulating molecular pathways involved in schizophrenia. MicroRNAs (miRNAs) are small, non-coding RNAs that target specific mRNAs and inhibit their translation into proteins. As epigenetic factors, miRNAs regulate many genes involved in glutamate and dopamine signaling pathways; thereby, their dysregulation can contribute to the development of schizophrenia. Secretion of specific miRNAs from damaged cells into body fluids can make them one of the ideal non-invasive biomarkers in the early diagnosis of schizophrenia. Also, understanding the molecular mechanisms of miRNAs in schizophrenia pathogenesis can pave the way for developing novel treatments for patients with schizophrenia. In this study, we reviewed the glutamatergic and dopaminergic pathophysiology and highlighted the role of miRNA dysregulation in schizophrenia development. Besides, we shed light on the significance of circulating miRNAs for schizophrenia diagnosis and the recent findings on the miRNA-based treatment for schizophrenia.

microRNA-324 mediates bone homeostasis and the regulation of osteoblast and osteoclast differentiation and activity

MicroRNAs (miRNAs) modulate the expression of other RNA molecules. One miRNA can target many transcripts, allowing each miRNA to play key roles in many biological pathways. Defects in bone homeostasis result in common age-related diseases including osteoporosis. Serum levels of miR-324-3p positively correlate with several features of bone maintenance. In contrast here, using in vivo micro-computed tomography and histology, global miR-324-null mice demonstrated increased bone mineral density and both trabecular and cortical thickness, with effect magnitudes increasing with age. The bone marrow of miR-324-null mice had reduced lipid content while TRAP staining revealed a decrease in osteoclasts, with histomorphometry demonstrating an increased rate of bone formation. Ex vivo assays showed that the high bone mass phenotype of miR-324-null mice resulted from both increased osteoblast activity and decreased osteoclastogenesis. RNA-seq analysis of osteoblasts, osteoclasts and bone marrow macrophages and target validation assays identified that the osteoclast fusion regulator Pin1 and the master osteogenic regulator Runx2 were targets of miR-324-5p in osteoclast lineage cells and osteoblasts, respectively. Indeed, in vitro Runx2 overexpression recapitulated the increased osteogenesis and decreased adipogenesis phenotype observed in vivo by the loss of miR-324. Overall, these data demonstrate the importance of miR-324 in bone homeostasis by regulating aspects of both bone formation and remodelling. Elucidation of pathways regulated by miR-324 offer promise for the treatment of bone diseases such as osteoporosis.

Widespread biochemical reaction networks enable Turing patterns without imposed feedback

Understanding self-organized pattern formation is fundamental to biology. In 1952, Alan Turing proposed a pattern-enabling mechanism in reaction-diffusion systems containing chemical species later conceptualized as activators and inhibitors that are involved in feedback loops. However, identifying pattern-enabling regulatory systems with the concept of feedback loops has been a long-standing challenge. To date, very few pattern-enabling circuits have been discovered experimentally. This is in stark contrast to ubiquitous periodic patterns and symmetry in biology. In this work, we systematically study Turing patterns in 23 elementary biochemical networks without assigning any activator or inhibitor. These mass action models describe post-synthesis interactions applicable to most proteins and RNAs in multicellular organisms. Strikingly, we find ten simple reaction networks capable of generating Turing patterns. While these network models are consistent with Turing's theory mathematically, there is no apparent connection between them and commonly used activator-feedback intuition. Instead, we identify a unifying network motif that enables Turing patterns via regulated degradation pathways with flexible diffusion rate constants of individual molecules. Our work reveals widespread biochemical systems for pattern formation, and it provides an alternative approach to tackle the challenge of identifying pattern-enabling biological systems.

Non-Coding RNAs in Myasthenia Gravis: From Immune Regulation to Personalized Medicine

Myasthenia gravis (MG) is an antibody-mediated autoimmune disorder characterized by altered neuromuscular transmission, which causes weakness and fatigability in the skeletal muscles. The etiology of MG is complex, being associated with multiple genetic and environmental factors. Over recent years, progress has been made in understanding the immunological alterations implicated in the disease, but the exact pathogenesis still needs to be elucidated. A pathogenic interplay between innate immunity and autoimmunity contributes to the intra-thymic MG development. Epigenetic changes are critically involved in both innate and adaptive immune response regulation. They can act as (i) pathological factors besides genetic predisposition and (ii) co-factors contributing to disease phenotypes or patient-specific disease course/outcomes. This article reviews the role of non-coding RNAs (ncRNAs) as epigenetic factors implicated in MG. Particular attention is dedicated to microRNAs (miRNAs), whose expression is altered in MG patients' thymuses and circulating blood. The long ncRNA (lncRNA) contribution to MG, although not fully characterized yet, is also discussed. By summarizing the most recent and fast-growing findings on ncRNAs in MG, we highlight the therapeutic potential of these molecules for achieving immune regulation and their value as biomarkers for the development of personalized medicine approaches to improve disease care.

Non-coding RNAs as therapeutic targets in cancer and its clinical application

Cancer genomics has led to the discovery of numerous oncogenes and tumor suppressor genes that play critical roles in cancer development and progression. Oncogenes promote cell growth and proliferation, whereas tumor suppressor genes inhibit cell growth and division. The dysregulation of these genes can lead to the development of cancer. Recent studies have focused on non-coding RNAs (ncRNAs), including circular RNA (circRNA), long non-coding RNA (lncRNA), and microRNA (miRNA), as therapeutic targets for cancer. In this article, we discuss the oncogenes and tumor suppressor genes of ncRNAs associated with different types of cancer and their potential as therapeutic targets. Here, we highlight the mechanisms of action of these genes and their clinical applications in cancer treatment. Understanding the molecular mechanisms underlying cancer development and identifying specific therapeutic targets are essential steps towards the development of effective cancer treatments.

Differential Signaling Pathways in Medulloblastoma: Nano-biomedicine Targeting Non-coding Epigenetics to Improve Current and Future Therapeutics

BACKGROUND

Medulloblastomas (MDB) are malignant, aggressive brain tumors that primarily affect children. The survival rate for children under 14 is approximately 72%, while for ages 15 to 39, it is around 78%. A growing body of evidence suggests that dysregulation of signaling mechanisms and noncoding RNA epigenetics play a pivotal role in this disease.

METHODOLOGY

This study conducted an electronic search of articles on websites like PubMed and Google. The current review also used an in silico databases search and bioinformatics analysis and an extensive comprehensive literature search for original research articles and review articles as well as retrieval of current and future medications in clinical trials.

RESULTS

This study indicates that several signaling pathways, such as sonic hedgehog, WNT/β-catenin, unfolded protein response mediated ER stress, notch, neurotrophins and TGF-β and ERK, MAPK, and ERK play a crucial role in the pathogenesis of MDB. Gene and ncRNA/protein are also involved as an axis long ncRNA to sponge micro-RNAs that affect downstream signal proteins expression and translation affection disease pathophysiology, prognosis and present potential target hit for drug repurposing. Current treatment options include surgery, radiation, and chemotherapy; unfortunately, the disease often relapses, and the survival rate is less than 5%. Therefore, there is a need to develop more effective treatments to combat recurrence and improve survival rates.

CONCLUSION

This review describes various MDB disease hallmarks, including the signaling mechanisms involved in pathophysiology, related-causal genes, epigenetics, downstream genes/epigenes, and possibly the causal disease genes/non-protein coding (nc)RNA/protein axis. Additionally, the challenges associated with MDB treatment are discussed, along with how they are being addressed using nano-technology and nano-biomedicine, with a listing of possible treatment options and future potential treatment modalities.

MiR-324-5p inhibition after intrahippocampal kainic acid-induced status epilepticus does not prevent epileptogenesis in mice

Background

Acquired epilepsies are caused by an initial brain insult that is followed by epileptogenesis and finally the development of spontaneous recurrent seizures. The mechanisms underlying epileptogenesis are not fully understood. MicroRNAs regulate mRNA translation and stability and are frequently implicated in epilepsy. For example, antagonism of a specific microRNA, miR-324-5p, before brain insult and in a model of chronic epilepsy decreases seizure susceptibility and frequency, respectively. Here, we tested whether antagonism of miR-324-5p during epileptogenesis inhibits the development of epilepsy.

Methods

We used the intrahippocampal kainic acid (IHpKa) model to initiate epileptogenesis in male wild type C57BL/6 J mice aged 6-8 weeks. Twenty-four hours after IHpKa, we administered a miR-324-5p or scrambled control antagomir intracerebroventricularly and implanted cortical surface electrodes for EEG monitoring. EEG data was collected for 28 days and analyzed for seizure frequency and duration, interictal spike activity, and EEG power. Brains were collected for histological analysis.

Results

Histological analysis of brain tissue showed that IHpKa caused characteristic hippocampal damage in most mice regardless of treatment. Antagomir treatment did not affect latency to, frequency, or duration of spontaneous recurrent seizures or interictal spike activity but did alter the temporal development of frequency band-specific EEG power.

Conclusion

These results suggest that miR-324-5p inhibition during epileptogenesis induced by status epilepticus does not convey anti-epileptogenic effects despite having subtle effects on EEG frequency bands. Our results highlight the importance of timing of intervention across epilepsy development and suggest that miR-324-5p may act primarily as a proconvulsant rather than a pro-epileptogenic regulator.

Possible role of miRNAs in pheochromocytoma pathology - Signaling pathways interaction

Pheochromocytoma (PCC) is a type of neuroendocrine tumor that originates from adrenal medulla or extra-adrenal chromaffin cells and results in the production of catecholamine. Paroxysmal hypertension and cardiovascular crises were among the clinical signs experienced by people with PCC. Five-year survival of advanced-stage PCC is just around 40% despite the identification of various molecular-level fundamentals implicated in these pathogenic pathways. MicroRNAs (miRNAs, miRs) are a type of short, non-coding RNA (ncRNA) that attach to the 3'-UTR of a target mRNA, causing translational inhibition or mRNA degradation. Evidence is mounting that miRNA dysregulation plays a role in the development, progression, and treatment of cancers like PCC. Hence, this study employs a comprehensive and expedited survey to elucidate the potential role of miRNAs in the development of PCC, surpassing their association with survival rates and treatment options in this particular malignancy.

Advances in molecular mechanism of HPV16 E5 oncoprotein carcinogenesis

For a considerable duration, cervical cancer has posed a significant risk to the well-being and survival of women. The emergence and progression of cervical cancer have garnered extensive attention, with prolonged chronic infection of HPV serving as a crucial etiological factor. Consequently, investigating the molecular mechanism underlying HPV-induced cervical cancer has become a prominent research area. The HPV molecule is composed of a long control region (LCR), an early coding region and a late coding region.The early coding region encompasses E1, E2, E4, E5, E6, E7, while the late coding region comprises L1 and L2 ORF.The investigation into the molecular structure and function of HPV has garnered significant attention, with the aim of elucidating the carcinogenic mechanism of HPV and identifying potential targets for the treatment of cervical cancer. Research has demonstrated that the HPV gene and its encoded protein play a crucial role in the invasion and malignant transformation of host cells. Consequently, understanding the function of HPV oncoprotein is of paramount importance in comprehending the pathogenesis of cervical cancer. E6 and E7, the primary HPV oncogenic proteins, have been the subject of extensive study. Moreover, a number of contemporary investigations have demonstrated the significant involvement of HPV16 E5 oncoprotein in the malignant conversion of healthy cells through its regulation of cell proliferation, differentiation, and apoptosis via diverse pathways, albeit the precise molecular mechanism remains unclear. This manuscript aims to provide a comprehensive account of the molecular structure and life cycle of HPV.The HPV E5 oncoprotein mechanism modulates cellular processes such as proliferation, differentiation, apoptosis, and energy metabolism through its interaction with cell growth factor receptors and other cellular proteins. This mechanism is crucial for the survival, adhesion, migration, and invasion of tumor cells in the early stages of carcinogenesis. Recent studies have identified the HPV E5 oncoprotein as a promising therapeutic target for early-stage cervical cancer, thus offering a novel approach for treatment.

Hedgehog signaling in tissue homeostasis, cancers, and targeted therapies

The past decade has seen significant advances in our understanding of Hedgehog (HH) signaling pathway in various biological events. HH signaling pathway exerts its biological effects through a complex signaling cascade involved with primary cilium. HH signaling pathway has important functions in embryonic development and tissue homeostasis. It plays a central role in the regulation of the proliferation and differentiation of adult stem cells. Importantly, it has become increasingly clear that HH signaling pathway is associated with increased cancer prevalence, malignant progression, poor prognosis and even increased mortality. Understanding the integrative nature of HH signaling pathway has opened up the potential for new therapeutic targets for cancer. A variety of drugs have been developed, including small molecule inhibitors, natural compounds, and long non-coding RNA (LncRNA), some of which are approved for clinical use. This review outlines recent discoveries of HH signaling in tissue homeostasis and cancer and discusses how these advances are paving the way for the development of new biologically based therapies for cancer. Furthermore, we address status quo and limitations of targeted therapies of HH signaling pathway. Insights from this review will help readers understand the function of HH signaling in homeostasis and cancer, as well as opportunities and challenges of therapeutic targets for cancer.

Epigenetic control of cell signalling in cancer stem cells

The self-renewing cancer stem cells (CSCs) represent one of the distinct cell populations occurring in a tumour that can differentiate into multiple lineages. This group of sparsely abundant cells play a vital role in tumour survival and resistance to different treatments during cancer. The lack of exclusive markers associated with CSCs makes diagnosis and prognosis in cancer patients extremely difficult. This calls for the identification of unique regulators and markers for CSCs. Various signalling pathways like the Wnt/β-catenin pathway, Hedgehog pathway, Notch pathway, and TGFβ/BMP play a major role in the regulation and maintenance of CSCs. Epigenetic regulatory mechanisms add another layer of complexity to control these signalling pathways. In this chapter, we discuss about the role of epigenetic mechanisms in regulating the cellular signalling pathways in CSCs. The epigenetic regulatory mechanisms such as DNA methylation, histone modification and microRNAs can modulate the diverse effectors of signalling pathways and consequently the growth, differentiation and tumorigenicity of CSCs. In the end, we briefly discuss the therapeutic potential of targeting these epigenetic regulators and their target genes in CSCs.

Regulation of miRNA expression by α4β1 integrin-dependent multiple myeloma cell adhesion

The α4β1 integrin regulates the trafficking of multiple myeloma (MM) cells and contributes to MM disease progression. MicroRNAs (miRNAs) can have both tumor suppressor and oncogenic roles and thus are key controllers of tumor evolution, and have been associated with different phases of MM pathogenesis. Using small RNAseq analysis, we show here that α4β1-dependent MM cell adhesion regulates the expression of forty different miRNAs, therefore expanding our current view of the α4β1 involvement in MM cell biology. Specific upregulation of miR-324-5p and miR-331-3p in cells attached to α4β1 ligands was confirmed upon silencing the α4 integrin subunit, and their increased levels found to be dependent on Erk1/2- and PI3K-Akt-, but not Src-dependent signaling. Enhanced miR-324-5p expression upon α4β1-mediated MM cell adhesion aimed the hedgehog (Hh) component SMO, revealing that the miR-324-5p-SMO module represents a α4β1-regulated pathway that could control Hh-dependent cellular responses in myeloma. Our results open new therapy research avenues around the α4β1 contribution to MM progression that deserve to be investigated.

Comparison of Oncogenes, Tumor Suppressors, and MicroRNAs Between Schizophrenia and Glioma: The Balance of Power

The risk of cancer in schizophrenia has been controversial. Confounders of the issue are cigarette smoking in schizophrenia, and antiproliferative effects of antipsychotic medications. The author has previously suggested comparison of a specific cancer like glioma to schizophrenia might help determine a more accurate relationship between cancer and schizophrenia. To accomplish this goal, the author performed three comparisons of data; the first a comparison of conventional tumor suppressors and oncogenes between schizophrenia and cancer including glioma. This comparison determined schizophrenia has both tumor-suppressive and tumor-promoting characteristics. A second, larger comparison between brain-expressed microRNAs in schizophrenia with their expression in glioma was then performed. This identified a core carcinogenic group of miRNAs in schizophrenia offset by a larger group of tumor-suppressive miRNAs. This proposed "balance of power" between oncogenes and tumor suppressors could cause neuroinflammation. This was assessed by a third comparison between schizophrenia, glioma and inflammation in asbestos-related lung cancer and mesothelioma (ALRCM). This revealed that schizophrenia shares more oncogenic similarity to ALRCM than glioma.

Mir125b-2 imprinted in human but not mouse brain regulates hippocampal function and circuit in mice

Genomic imprinting predominantly occurs in the placenta and brain. Few imprinted microRNAs have been identified in the brain, and their functional roles in the brain are not clear. Here we show paternal, but not maternal, expression of MIR125B2 in human but not mouse brain. Moreover, Mir125b-2^m-/p- mice showed impaired learning and memory, and anxiety, whose functions were hippocampus-dependent. Hippocampal granule cells from Mir125b-2^m-/p- mice displayed increased neuronal excitability, increased excitatory synaptic transmission, and decreased inhibitory synaptic transmission. Glutamate ionotropic receptor NMDA type subunit 2A (Grin2a), a key regulator of synaptic plasticity, was physically bound by miR-125b-2 and upregulated in the hippocampus of Mir125b-2^m-/p- mice. Taken together, our findings demonstrate MIR125B2 imprinted in human but not mouse brain, mediated learning, memory, and anxiety, regulated excitability and synaptic transmission in hippocampal granule cells, and affected hippocampal expression of Grin2a. Our work provides functional mechanisms of a species-specific imprinted microRNA in the brain.

Nanoparticles for Drug and Gene Delivery in Pediatric Brain Tumors' Cancer Stem Cells: Current Knowledge and Future Perspectives

Primary malignant brain tumors are the most common solid neoplasm in childhood. Despite recent advances, many children affected by aggressive or metastatic brain tumors still present poor prognosis, therefore the development of more effective therapies is urgent. Cancer stem cells (CSCs) have been discovered and isolated in both pediatric and adult patients with brain tumors (e.g., medulloblastoma, gliomas and ependymoma). CSCs are a small clonal population of cancer cells responsible for brain tumor initiation, maintenance and progression, displaying resistance to conventional anticancer therapies. CSCs are characterized by a specific repertoire of surface markers and intracellular specific pathways. These unique features of CSCs biology offer the opportunity to build therapeutic approaches to specifically target these cells in the complex tumor bulk. Treatment of pediatric brain tumors with classical chemotherapeutic regimen poses challenges both for tumor location and for the presence of the blood-brain barrier (BBB). Lastly, the application of chemotherapy to a developing brain is followed by long-term sequelae, especially on cognitive abilities. Novel avenues are emerging in the therapeutic panorama taking advantage of nanomedicine. In this review we will summarize nanoparticle-based approaches and the efficacy that NPs have intrinsically demonstrated and how they are also decorated by biomolecules. Furthermore, we propose novel cargoes together with recent advances in nanoparticle design/synthesis with the final aim to specifically target the insidious CSCs population in the tumor bulk.

β-arrestin1-E2F1-ac axis regulates physiological apoptosis and cell cycle exit in cellular models of early postnatal cerebellum

Development of the cerebellum is characterized by rapid proliferation of cerebellar granule cell precursors (GCPs) induced by paracrine stimulation of Sonic hedgehog (Shh) signaling from Purkinje cells, in the external granular layer (EGL). Then, granule cell precursors differentiate and migrate into the inner granular layer (IGL) of the cerebellum to form a terminally differentiated cell compartment. Aberrant activation of Sonic hedgehog signaling leads to granule cell precursors hyperproliferation and the onset of Sonic hedgehog medulloblastoma (MB), the most common embryonal brain tumor. β-arrestin1 (ARRB1) protein plays an important role downstream of Smoothened, a component of the Sonic hedgehog pathway. In the medulloblastoma context, β-arrestin1 is involved in a regulatory axis in association with the acetyltransferase P300, leading to the acetylated form of the transcription factor E2F1 (E2F1-ac) and redirecting its activity toward pro-apoptotic gene targets. This axis in the granule cell precursors physiological context has not been investigated yet. In this study, we demonstrate that β-arrestin1 has antiproliferative and pro-apoptotic functions in cerebellar development. β-arrestin1 silencing increases proliferation of Sonic hedgehog treated-cerebellar precursor cells while decreases the transcription of E2F1-ac pro-apoptotic targets genes, thus impairing apoptosis. Indeed, chromatin immunoprecipitation experiments show a direct interaction between β-arrestin1 and the promoter regions of the pro-apoptotic E2F1 target gene and P27, indicating the double role of β-arrestin1 in controlling apoptosis and cell cycle exit in a physiological context. Our data elucidate the role of β-arrestin1 in the early postnatal stages of cerebellar development, in those cell compartments that give rise to medulloblastoma. This series of experiments suggests that the physiological function of β-arrestin1 in neuronal progenitors is to directly control, cooperating with E2F1 acetylated form, transcription of pro-apoptotic genes.

The role of Hedgehog and Notch signaling pathway in cancer

Notch and Hedgehog signaling are involved in cancer biology and pathology, including the maintenance of tumor cell proliferation, cancer stem-like cells, and the tumor microenvironment. Given the complexity of Notch signaling in tumors, its role as both a tumor promoter and suppressor, and the crosstalk between pathways, the goal of developing clinically safe, effective, tumor-specific Notch-targeted drugs has remained intractable. Drugs developed against the Hedgehog signaling pathway have affirmed definitive therapeutic effects in basal cell carcinoma; however, in some contexts, the challenges of tumor resistance and recurrence leap to the forefront. The efficacy is very limited for other tumor types. In recent years, we have witnessed an exponential increase in the investigation and recognition of the critical roles of the Notch and Hedgehog signaling pathways in cancers, and the crosstalk between these pathways has vast space and value to explore. A series of clinical trials targeting signaling have been launched continually. In this review, we introduce current advances in the understanding of Notch and Hedgehog signaling and the crosstalk between pathways in specific tumor cell populations and microenvironments. Moreover, we also discuss the potential of targeting Notch and Hedgehog for cancer therapy, intending to promote the leap from bench to bedside.

Micromanaging pattern formation: miRNA regulation of signaling systems in vertebrate development

Early embryogenesis requires the establishment of fields of progenitor cells with distinct molecular signatures. A balance of intrinsic and extrinsic cues determines the boundaries of embryonic territories and pushes progenitor cells toward different fates. This process involves multiple layers of regulation, including signaling systems, transcriptional networks, and post-transcriptional control. In recent years, microRNAs (miRNAs) have emerged as undisputed regulators of developmental processes. Here, we discuss how miRNAs regulate pattern formation during vertebrate embryogenesis. We survey how miRNAs modulate the activity of signaling pathways to optimize transcriptional responses in embryonic cells. We also examine how localized RNA interference can generate spatial complexity during early development. Unraveling the complex crosstalk between miRNAs, signaling systems and cell fate decisions will be crucial for our understanding of developmental outcomes and disease.

The emerging role of noncoding RNAs in the Hedgehog signaling pathway in cancer

Hedgehog (HH), a conserved signaling pathway, is involved in embryo development, organogenesis, and other biological functions. Dysregulation and abnormal activation of HH are involved in tumorigenesis and tumor progression. With the emergence of interest in noncoding RNAs, studies on their involvement in abnormal regulation of biological processes in tumors have been published one after another. In this review, we focus on the crosstalk between noncoding RNAs and the HH pathway in tumors and elaborate the mechanisms by which long noncoding RNAs and microRNAs regulate or are regulated by HH signaling in cancer. We also discuss the interaction between noncoding RNAs and the HH pathway from the perspective of cancer hallmarks, presenting this complex network as concisely as possible and organizing ideas for cancer diagnosis and treatment.

Dissection of the microRNA Network Regulating Hedgehog Signaling in Drosophila

The evolutionarily conserved Hedgehog (Hh) signaling plays a critical role in embryogenesis and adult tissue homeostasis. Aberrant Hh signaling often leads to various forms of developmental anomalies and cancer. Since altered microRNA (miRNA) expression is associated with developmental defects and tumorigenesis, it is not surprising that several miRNAs have been found to regulate Hh signaling. However, these miRNAs are mainly identified through small-scale in vivo screening or in vitro assays. As miRNAs preferentially reduce target gene expression via the 3' untranslated region, we analyzed the effect of reduced expression of core components of the Hh signaling cascade on downstream signaling activity, and generated a transgenic Drosophila toolbox of in vivo miRNA sensors for core components of Hh signaling, including hh, patched (ptc), smoothened (smo), costal 2 (cos2), fused (fu), Suppressor of fused (Su(fu)), and cubitus interruptus (ci). With these tools in hand, we performed a genome-wide in vivo miRNA overexpression screen in the developing Drosophila wing imaginal disc. Of the twelve miRNAs identified, seven were not previously reported in the in vivo Hh regulatory network. Moreover, these miRNAs may act as general regulators of Hh signaling, as their overexpression disrupts Hh signaling-mediated cyst stem cell maintenance during spermatogenesis. To identify direct targets of these newly discovered miRNAs, we used the miRNA sensor toolbox to show that miR-10 and miR-958 directly target fu and smo, respectively, while the other five miRNAs act through yet-to-be-identified targets other than the seven core components of Hh signaling described above. Importantly, through loss-of-function analysis, we found that endogenous miR-10 and miR-958 target fu and smo, respectively, whereas deletion of the other five miRNAs leads to altered expression of Hh signaling components, suggesting that these seven newly discovered miRNAs regulate Hh signaling in vivo. Given the powerful effects of these miRNAs on Hh signaling, we believe that identifying their bona fide targets of the other five miRNAs will help reveal important new players in the Hh regulatory network.

ITGA9: Potential Biomarkers and Therapeutic Targets in Different Tumors

Abstract:

Integrins are a class of a cell surface adhesion molecule which composed of α subunit (ITGA) and β subunit (ITGB). They belong to heterodimer transmembrane glycoproteins. Its main function in organisms is as the receptor of cell adhesion molecules (CAMs) and extracellular matrix (ECM). According to the current research integration analysis, integrin α9 (ITGA9) is one of the integrin subunits, and there are few studies on ITGA9 among integrins. ITGA9 can improve cell migration and regulate various cellular biological functions, such as tumor cell proliferation, adhesion, invasion, and angiogenesis. But its abnormal expression mechanism in cancer and its specific role in tumor growth and metastasis are still unknown to a great extent. This review reveals the role of ITGA9 in the complex pathogenesis of many tumors and cancers, providing a new direction for the treatment of tumors and cancers. Relevant studies were retrieved and collected through the PubMed system. After determining ITGA9 as the research object, we found the close relationship between ITGA9 and tumorigenesis through the analysis of the research articles on ITGA9 in the PubMed system in the last 15 years, and further determined the references mainly based on the influencing factors of the articles. Thus, the role of ITGA9 in tumor and cancer genesis, proliferation, and metastasis was reviewed and analyzed. ITGA9 is an integrin subunit, which has been proved to be abnormally expressed in many tumors. After sorting and analyzing the research data, it was found that the abnormal expression of ITGA9 in a variety of tumors, including glioblastoma, rhabdomyosarcoma, melanoma, hepatocellular carcinoma, nasopharyngeal carcinoma, multiple myeloma, non-small cell lung cancer, and prostate cancer, was closely related to the proliferation, metastasis, adhesion, and angiogenesis of tumor cells. These results suggest that ITGA9 plays an important role in the occurrence and development of tumors. The integrin subunit ITGA9 may serve as a biomarker for the diagnosis of tumors and a potential therapeutic target for anti-tumor therapies.

Epigenetic mechanisms in paediatric brain tumours: regulators lose control

Epigenetic mechanisms are essential to regulate gene expression during normal development. However, they are often disrupted in pathological conditions including tumours, where they contribute to their formation and maintenance through altered gene expression. In recent years, next generation genomic techniques has allowed a remarkable advancement of our knowledge of the genetic and molecular landscape of paediatric brain tumours and have highlighted epigenetic deregulation as a common hallmark in their pathogenesis. This review describes the main epigenetic dysregulations found in paediatric brain tumours, including at DNA methylation and histone modifications level, in the activity of chromatin-modifying enzymes and in the expression of non-coding RNAs. How these altered processes influence tumour biology and how they can be leveraged to dissect the molecular heterogeneity of these tumours and contribute to their classification is also addressed. Finally, the availability and value of preclinical models as well as the current clinical trials exploring targeting key epigenetic mediators in paediatric brain tumours are discussed.

Subgroup-Specific Diagnostic, Prognostic, and Predictive Markers Influencing Pediatric Medulloblastoma Treatment

Medulloblastoma (MB) is the most common malignant central nervous system tumor in pediatric patients. Mainstay of therapy remains surgical resection followed by craniospinal radiation and chemotherapy, although limitations to this therapy are applied in the youngest patients. Clinically, tumors are divided into average and high-risk status on the basis of age, metastasis at diagnosis, and extent of surgical resection. However, technological advances in high-throughput screening have facilitated the analysis of large transcriptomic datasets that have been used to generate the current classification system, dividing patients into four primary subgroups, i.e., WNT (wingless), SHH (sonic hedgehog), and the non-SHH/WNT subgroups 3 and 4. Each subgroup can further be subdivided on the basis of a combination of cytogenetic and epigenetic events, some in distinct signaling pathways, that activate specific phenotypes impacting patient prognosis. Here, we delve deeper into the genetic basis for each subgroup by reviewing the extent of cytogenetic events in key genes that trigger neoplastic transformation or that exhibit oncogenic properties. Each of these discussions is further centered on how these genetic aberrations can be exploited to generate novel targeted therapeutics for each subgroup along with a discussion on challenges that are currently faced in generating said therapies. Our future hope is that through better understanding of subgroup-specific cytogenetic events, the field may improve diagnosis, prognosis, and treatment to improve overall quality of life for these patients.

Role of MicroRNAs in the Development and Progression of the Four Medulloblastoma Subgroups

Medulloblastoma is the most frequent malignant brain tumour in children. Medulloblastoma originate during the embryonic stage. They are located in the cerebellum, which is the area of the central nervous system (CNS) responsible for controlling equilibrium and coordination of movements. In 2012, medulloblastoma were divided into four subgroups based on a genome-wide analysis of RNA expression. These subgroups are named Wingless, Sonic Hedgehog, Group 3 and Group 4. Each subgroup has a different cell of origin, prognosis, and response to therapies. Wingless and Sonic Hedgehog medulloblastoma are so named based on the main mutation originating these tumours. Group 3 and Group 4 have generic names because we do not know the key mutation driving these tumours. Gene expression at the post-transcriptional level is regulated by a group of small single-stranded non-coding RNAs. These microRNA (miRNAs or miRs) play a central role in several cellular functions such as cell differentiation and, therefore, any malfunction in this regulatory system leads to a variety of disorders such as cancer. The role of miRNAs in medulloblastoma is still a topic of intense clinical research; previous studies have mostly concentrated on the clinical entity of the single disease rather than in the four molecular subgroups. In this review, we summarize the latest discoveries on miRNAs in the four medulloblastoma subgroups.

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.

Noncoding RNAs in pediatric brain tumors: Molecular functions and pathological implications

Brain tumors are common solid pediatric malignancies and the main reason for cancer-related death in the pediatric setting. Recently, evidence has revealed that noncoding RNAs (ncRNAs), including microRNAs (miRNAs), long ncRNAs (lncRNAs), and circular RNAs (circRNAs), play a critical role in brain tumor development and progression. Therefore, in this review article, we describe the functions and molecular mechanisms of ncRNAs in multiple types of cancer, including medulloblastoma, pilocytic astrocytoma, ependymoma, atypical teratoid/rhabdoid tumor, glioblastoma, diffuse intrinsic pontine glioma, and craniopharyngioma. We also mention the limitations of using ncRNAs as therapeutic targets because of the nonspecificity of ncRNA targets and the delivery methods of ncRNAs. Due to the critical role of ncRNAs in brain oncogenesis, targeting aberrantly expressed ncRNAs might be an effective strategy to improve the outcomes of pediatric patients with brain tumors.

Identification of colorectal cancer associated biomarkers: an integrated analysis of miRNA expression

Colorectal cancer is one of the leading causes of cancer-related deaths worldwide. This complex disease still holds severe problems concerning diagnosis due to the high invasiveness nature of colonoscopy and the low accuracy of the alternative diagnostic methods. Additionally, patient heterogeneity even within the same stage is not properly reflected in the current stratification system. This scenario highlights the need for new biomarkers to improve non-invasive screenings and clinical management of patients. MicroRNAs (miRNAs) have emerged as good candidate biomarkers in cancer as they are stable molecules, easily measurable and detected in body fluids thus allowing for non-invasive diagnosis and/or prognosis. In this study, we performed an integrated analysis first using 4 different datasets (discovery cohorts) to identify miRNAs associated with colorectal cancer development, unveil their role in this disease by identifying putative targets and regulatory networks and investigate their ability to serve as biomarkers. We have identified 26 differentially expressed miRNAs which interact with frequently deregulated genes known to participate in commonly altered pathways in colorectal cancer. Most of these miRNAs have high diagnostic power, and their prognostic potential is evidenced by panels of 5 miRNAs able to predict the outcome of stage II and III colorectal cancer patients. Notably, 8 miRNAs were validated in three additional independent cohorts (validation cohorts) including a plasma cohort thus reinforcing the value of miRNAs as non-invasive biomarkers.

Identification of Molecules Responsible for Therapeutic Effects of Extracellular Vesicles Produced from iPSC-Derived MSCs on Sjo¨gren's Syndrome

Recent research indicated that extracellular vesicles (EVs) derived from mesenchymal stem/stromal cells (MSCs) are a promising alternative to MSCs for immunomodulatory therapy. However, the contents of MSC-EVs would change as their parent MSCs change, hence the therapeutic efficacy of MSC-derived EVs (MSC-EVs) would largely depend on donors, tissue sources and culture conditions of MSCs. To overcome limitations of tissue-derived MSCs, we previously used MSCs derived from human induced pluripotent stem cells (iMSCs) to produce EVs and demonstrated their therapeutic potential in a mouse model of secondary Sjo¨gren's Syndrome. Here, we further found that EVs from early-passage iMSCs had better immunomodulatory potency than EVs from late-passage iMSCs in TLR4-stimulated splenocytes and in a mouse model of primary Sjögren's syndrome. Comparative molecular profiling using proteomics and microRNA sequencing revealed distinctive molecular profiles of iMSC-EVs with or without immunomodulation capacity. Amongst them, manipulation of TGF-β1, miR-21 and miR-125b levels in iMSC-EVs significantly affected their immunosuppressive effects. These findings would help improve our understanding of the molecular mechanism underlying iMSC-EV-mediated immunomodulation and further provide strategies to improve regulatory function of EVs for the treatment of immune-mediated diseases.

Epigenetic modulators for brain cancer stem cells: Implications for anticancer treatment

Primary malignant brain tumors are a major cause of morbidity and mortality in both adults and children, with a dismal prognosis despite multimodal therapeutic approaches. In the last years, a specific subpopulation of cells within the tumor bulk, named cancer stem cells (CSCs) or tumor-initiating cells, have been identified in brain tumors as responsible for cancer growth and disease progression. Stemness features of tumor cells strongly affect treatment response, leading to the escape from conventional therapeutic approaches and subsequently causing tumor relapse. Recent research efforts have focused at identifying new therapeutic strategies capable of specifically targeting CSCs in cancers by taking into consideration their complex nature. Aberrant epigenetic machinery plays a key role in the genesis and progression of brain tumors as well as inducing CSC reprogramming and preserving CSC characteristics. Thus, reverting the cancer epigenome can be considered a promising therapeutic strategy. Three main epigenetic mechanisms have been described: DNA methylation, histone modifications, and non-coding RNA, particularly microRNAs. Each of these mechanisms has been proven to be targetable by chemical compounds, known as epigenetic-based drugs or epidrugs, that specifically target epigenetic marks. We review here recent advances in the study of epigenetic modulators promoting and sustaining brain tumor stem-like cells. We focus on their potential role in cancer therapy.

Epigenetically Mediated Ciliogenesis and Cell Cycle Regulation, and Their Translational Potential

Primary cilia biogenesis has been closely associated with cell cycle progression. Cilia assemble when cells exit the cell cycle and enter a quiescent stage at the post-mitosis phase, and disassemble before cells re-enter a new cell cycle. Studies have focused on how the cell cycle coordinates with the cilia assembly/disassembly process, and whether and how cilia biogenesis affects the cell cycle. Appropriate regulation of the functions and/or expressions of ciliary and cell-cycle-associated proteins is pivotal to maintaining bodily homeostasis. Epigenetic mechanisms, including DNA methylation and histone/chromatin modifications, are involved in the regulation of cell cycle progression and cilia biogenesis. In this review, first, we discuss how epigenetic mechanisms regulate cell cycle progression and cilia biogenesis through the regulation of DNA methylation and chromatin structures, to either promote or repress the transcription of genes associated with those processes and the modification of cytoskeleton network, including microtubule and actin. Next, we discuss the crosstalk between the cell cycle and ciliogenesis, and the involvement of epigenetic regulators in this process. In addition, we discuss cilia-dependent signaling pathways in cell cycle regulation. Understanding the mechanisms of how epigenetic regulators contribute to abnormal cell cycle regulation and ciliogenesis defects would lead to developing therapeutic strategies for the treatment of a wide variety of diseases, such as cancers, polycystic kidney disease (PKD), and other ciliopathy-associated disorders.

Identification of Circulating hsa-miR-324-3p and hsa-miR-331-3p Exchanges in The Serum of Alzheimer's Patients and Insights into The Pathophysiological Pathways

Objective

Alzheimer's disease (AD) is a type of dementia. Currently, there are not any existing and reliable methods for the prognosis or diagnosis of AD. Hence, finding a diagnostic/prognostic biomarker for AD helps physicians to prescribe the treatments and methods preventing disease progression. Circulating microRNAs (miRNAs) are the most promising biomarkers due to their non-invasive and easily accessible for diagnosis and prognosis of AD. The aim of current study is to evaluate expression levels of two unwell-known circulating miRNAs including hsa-miR-324-3p and hsa-miR-331-3p in serums of AD patients and to understand their roles in AD physiopathogenesis by in silico analysis.

Materials and Methods

In this case and control study, to get the gene targets related to these two miRNAs, TargetScan, miRTargetLink Human and mirDIP web servers were applied. In addition, gene networks and gene ontology enrichment analysis were performed by STRING 10.5, KEGG and ShinyGO v0.41. Experimentally, expression levels of these two miRNAs in the serum of 21 patients with AD and 23 healthy individuals were compared using the quantitative reverse transcription polymerase chain reaction (qRT-PCR) method.

Results

The pathophysiological pathways associated with these two miRNAs were nucleotide metabolism and cellular response to stress pathway. Furthermore, the upregulated expression levels of hsa-miR-324-3p and hsa-miR-331-3p in comparison with the healthy control serums were not statistically significant (P>0.05).

Conclusion

Non-significant results were obtained from the expression levels of AD patients and two significant pathways were obtained by networks and gene enrichment analysis.

MiRNAs in early brain development and pediatric cancer: At the intersection between healthy and diseased embryonic development

The size and organization of the brain are determined by the activity of progenitor cells early in development. Key mechanisms regulating progenitor cell biology involve miRNAs. These small noncoding RNA molecules bind mRNAs with high specificity, controlling their abundance and expression. The role of miRNAs in brain development has been studied extensively, but their involvement at early stages remained unknown until recently. Here, recent findings showing the important role of miRNAs in the earliest phases of brain development are reviewed, and it is discussed how loss of specific miRNAs leads to pathological conditions, particularly adult and pediatric brain tumors. Let-7 miRNA downregulation and the initiation of embryonal tumors with multilayered rosettes (ETMR), a novel link recently discovered by the laboratory, are focused upon. Finally, it is discussed how miRNAs may be used for the diagnosis and therapeutic treatment of pediatric brain tumors, with the hope of improving the prognosis of these devastating diseases.

Downregulation of miR-326 and its host gene β-arrestin1 induces pro-survival activity of E2F1 and promotes medulloblastoma growth

Persistent mortality rates of medulloblastoma (MB) and severe side effects of the current therapies require the definition of the molecular mechanisms that contribute to tumor progression. Using cultured MB cancer stem cells and xenograft tumors generated in mice, we show that low expression of miR-326 and its host gene β-arrestin1 (ARRB1) promotes tumor growth enhancing the E2F1 pro-survival function. Our models revealed that miR-326 and ARRB1 are controlled by a bivalent domain, since the H3K27me3 repressive mark is found at their regulatory region together with the activation-associated H3K4me3 mark. High levels of EZH2, a feature of MB, are responsible for the presence of H3K27me3. Ectopic expression of miR-326 and ARRB1 provides hints into how their low levels regulate E2F1 activity. MiR-326 targets E2F1 mRNA, thereby reducing its protein levels; ARRB1, triggering E2F1 acetylation, reverses its function into pro-apoptotic activity. Similar to miR-326 and ARRB1 overexpression, we also show that EZH2 inhibition restores miR-326/ARRB1 expression, limiting E2F1 pro-proliferative activity. Our results reveal a new regulatory molecular axis critical for MB progression.

Deconstructing Sonic Hedgehog Medulloblastoma: Molecular Subtypes, Drivers, and Beyond

Medulloblastoma (MB) is a highly malignant cerebellar tumor predominantly diagnosed during childhood. Driven by pathogenic activation of sonic hedgehog (SHH) signaling, SHH subgroup MB (SHH-MB) accounts for nearly one-third of diagnoses. Extensive molecular analyses have identified biologically and clinically relevant intertumoral heterogeneity among SHH-MB tumors, prompting the recognition of novel subtypes. Beyond germline and somatic mutations promoting constitutive SHH signaling, driver alterations affect a multitude of pathways and molecular processes, including TP53 signaling, chromatin modulation, and post-transcriptional gene regulation. Here, we review recent advances in the underpinnings of SHH-MB in the context of molecular subtypes, clarify novel somatic and germline drivers, highlight cellular origins and developmental hierarchies, and describe the composition of the tumor microenvironment and its putative role in tumorigenesis.

SUFU mediates EMT and Wnt/β-catenin signaling pathway activation promoted by miRNA-324-5p in human gastric cancer

The poor prognosis of late gastric carcinomas (GC) underscores the necessity to identify novel biomarkers for earlier diagnosis and effective therapeutic targets. MiRNA-324-5p has been shown to be over-expressed in GC, however the biological function of miRNA-324-5p implicated in gastric cancer and its downstream targets were not well understood. Wnt/β-catenin signaling pathway is aberrantly regulated in GC. We sought to explore if miRNA-324-5p promotes oncogenesis through modulating Wnt signaling and EMT. MiRNA-324-5p is highly expressed in GC based on qRT-PCR and TCGA data. In addition, in vitro cell proliferation, cell migration assays and in vivo animal exenograft were executed to show that miRNA-324-5p is an oncogenic miRNA in GC. MiRNA-324-5p activates Wnt signaling and induces EMT in GC. Further, SUFU was identified as a target of miRNA-324-5p confirmed by western blotting and luciferase assays. Spearson analysis and TCGA data indicate that the expression of SUFU is negatively associated with the expression of miRNA-324-5p. Rescue experiments were performed to determine if SUFU mediates the Wnt activation, EMT and oncogenic function of miRNA-324-5p. MiRNA-324-5p inhibitors plus SUFU siRNAs rescue partially the inhibitory effect on Wnt signaling and EMT caused by miRNA-324-5p inhibitors. Finally, the suppression of cell proliferation, migration, and colony formation ability induced by miRNA-324-5p inhibitors is alleviated by addition of SUFU siRNAs. In summary, miRNA-324-5p is overexpressed in vivo and exerts cell growth and migration-promoting effects through activating Wnt signaling and EMT by targeting SUFU in GC. It represents a potential miRNA with an oncogenic role in human gastric cancer.

Noncoding RNAs and Midbrain DA Neurons: Novel Molecular Mechanisms and Therapeutic Targets in Health and Disease

Midbrain dopamine neurons have crucial functions in motor and emotional control and their degeneration leads to several neurological dysfunctions such as Parkinson's disease, addiction, depression, schizophrenia, and others. Despite advances in the understanding of specific altered proteins and coding genes, little is known about cumulative changes in the transcriptional landscape of noncoding genes in midbrain dopamine neurons. Noncoding RNAs-specifically microRNAs and long noncoding RNAs-are emerging as crucial post-transcriptional regulators of gene expression in the brain. The identification of noncoding RNA networks underlying all stages of dopamine neuron development and plasticity is an essential step to deeply understand their physiological role and also their involvement in the etiology of dopaminergic diseases. Here, we provide an update about noncoding RNAs involved in dopaminergic development and metabolism, and the related evidence of these biomolecules for applications in potential treatments for dopaminergic neurodegeneration.

The Effects of Combination of Mimic miR-155-5p and Antagonist miR-324-5p Encapsulated Chitosan in Ovarian Cancer SKOV3

Objective:

Ovarian cancer is a malignant tumor that attacks reproductive organs of women. MicroRNA is known to have an involvement in the prognosis of ovarian cancer. One of them is miR-155-5p which is down regulated and miR-324-5p which is up regulated. Chitosan is used as microRNA delivery system. The aims of this study is to find out the effects of combination microRNA encapsulated chitosan in cell line SKOV3.

Methods:

Cell line SKOV3 obtained from Stem Cell and Cancer Institute (Kalbe). Mimic miR-155-5p and Antagonist miR-324-5p formulated with chitosan. Total RNA was extracted from nine samples (three as control and six as treatment), and prepared for cDNA synthesis. Expression of RNA and mRNA target was measured using q-PCR Biorad CFX96 C.100 and Gen Ex 7 software. Statistics analysis was measured using SPSS 16.0.

Results:

The administration of combination microRNA encapsulated with chitosan affect the expression of miR-155-5p and miR-324-5p endogen (P<0.05). The expression of mRNA target HIF1α and GLI1 was down regulated after treatment. The correlation between expression of microRNA and mRNA target was strongly (P<0.05).

Conclusion:

This study successfully presented effects of combination of mimic miR-155-5p and antagonist miR-324-5p encapsulated chitosan which be considered as a potential therapy targets for ovarium cancer.

Medulloblastoma epigenetics and the path to clinical innovation

INTRODUCTION

In the last decade, a number of genomic and pharmacological studies have demonstrated the importance of epigenetic dysregulation in medulloblastoma initiation and progression. High throughput approaches including gene expression array, next-generation sequencing (NGS), and methylation profiling have now clearly identified at least four molecular subgroups within medulloblastoma, each with distinct clinical and prognostic characteristics. These studies have clearly shown that despite the overall paucity of mutations, clinically relevant events do occur within the cellular epigenetic machinery. Thus, this review aims to provide an overview of our current understanding of the spectrum of epi-oncogenetic perturbations in medulloblastoma.

METHODS

Comprehensive review of epigenetic profiles of different subgroups of medulloblastoma in the context of molecular features. Epigenetic regulation is mediated mainly by DNA methylation, histone modifications and microRNAs (miRNA). Importantly, epigenetic mis-events are reversible and have immense therapeutic potential.

CONCLUSION

The widespread epigenetic alterations present in these tumors has generated intense interest in their use as therapeutic targets. We provide an assessment of the progress that has been made towards the development of molecular subtypes-targeted therapies and the current status of clinical trials that have leveraged these recent advances.

Histone Deacetylase Inhibitors in Pediatric Brain Cancers: Biological Activities and Therapeutic Potential

Brain cancers are the leading cause of cancer-related deaths in children. Biological changes in these tumors likely include epigenetic deregulation during embryonal development of the nervous system. Histone acetylation is one of the most widely investigated epigenetic processes, and histone deacetylase inhibitors (HDACis) are increasingly important candidate treatments in many cancer types. Here, we review advances in our understanding of how HDACis display antitumor effects in experimental models of specific pediatric brain tumor types, i.e., medulloblastoma (MB), ependymoma (EPN), pediatric high-grade gliomas (HGGs), and rhabdoid and atypical teratoid/rhabdoid tumors (ATRTs). We also discuss clinical perspectives for the use of HDACis in the treatment of pediatric brain tumors.

The Non-coding Side of Medulloblastoma

Medulloblastoma (MB) is the most common pediatric brain tumor and a primary cause of cancer-related death in children. Until a few years ago, only clinical and histological features were exploited for MB pathological classification and outcome prognosis. In the past decade, the advancement of high-throughput molecular analyses that integrate genetic, epigenetic, and expression data, together with the availability of increasing wealth of patient samples, revealed the existence of four molecularly distinct MB subgroups. Their further classification into 12 subtypes not only reduced the well-characterized intertumoral heterogeneity, but also provided new opportunities for the design of targets for precision oncology. Moreover, the identification of tumorigenic and self-renewing subpopulations of cancer stem cells in MB has increased our knowledge of its biology. Despite these advancements, the origin of MB is still debated, and its molecular bases are poorly characterized. A major goal in the field is to identify the key genes that drive tumor growth and the mechanisms through which they are able to promote tumorigenesis. So far, only protein-coding genes acting as oncogenic drivers have been characterized in each MB subgroup. The contribution of the non-coding side of the genome, which produces a plethora of transcripts that control fundamental biological processes, as the cell choice between proliferation and differentiation, is still unappreciated. This review wants to fill this major gap by summarizing the recent findings on the impact of non-coding RNAs in MB initiation and progression. Furthermore, their potential role as specific MB biomarkers and novel therapeutic targets is also highlighted.

A Mechanism for microRNA Arm Switching Regulated by Uridylation

Strand selection is a critical step in microRNA (miRNA) biogenesis. Although the dominant strand may change depending on cellular contexts, the molecular mechanism and physiological significance of such alternative strand selection (or "arm switching") remain elusive. Here we find miR-324 to be one of the strongly regulated miRNAs by arm switching and identify the terminal uridylyl transferases TUT4 and TUT7 to be the key regulators. Uridylation of pre-miR-324 by TUT4/7 re-positions DICER on the pre-miRNA and shifts the cleavage site. This alternative processing produces a duplex with a different terminus from which the 3' strand (3p) is selected instead of the 5' strand (5p). In glioblastoma, the TUT4/7 and 3p levels are upregulated, whereas the 5p level is reduced. Manipulation of the strand ratio is sufficient to impair glioblastoma cell proliferation. This study uncovers a role of uridylation as a molecular switch in alternative strand selection and implicates its therapeutic potential.

Recent Trends of microRNA Significance in Pediatric Population Glioblastoma and Current Knowledge of Micro RNA Function in Glioblastoma Multiforme

Central nervous system tumors are a significant problem for modern medicine because of their location. The explanation of the importance of microRNA (miRNA) in the development of cancerous changes plays an important role in this respect. The first papers describing the presence of miRNA were published in the 1990s. The role of miRNA has been pointed out in many medical conditions such as kidney disease, diabetes, neurodegenerative disorder, arthritis and cancer. There are several miRNAs responsible for invasiveness, apoptosis, resistance to treatment, angiogenesis, proliferation and immunology, and many others. The research conducted in recent years analyzing this group of tumors has shown the important role of miRNA in the course of gliomagenesis. These particles seem to participate in many stages of the development of cancer processes, such as proliferation, angiogenesis, regulation of apoptosis or cell resistance to cytostatics.

Implication of the p53-Related miR-34c, -125b, and -203 in the Osteoblastic Differentiation and the Malignant Transformation of Bone Sarcomas

The formation of the skeleton occurs throughout the lives of vertebrates and is achieved through the balanced activities of two kinds of specialized bone cells: the bone-forming osteoblasts and the bone-resorbing osteoclasts. Impairment in the remodeling processes dramatically hampers the proper healing of fractures and can also result in malignant bone diseases such as osteosarcoma. MicroRNAs (miRNAs) are a class of small non-coding single-strand RNAs implicated in the control of various cellular activities such as proliferation, differentiation, and apoptosis. Their post-transcriptional regulatory role confers on them inhibitory functions toward specific target mRNAs. As miRNAs are involved in the differentiation program of precursor cells, it is now well established that this class of molecules also influences bone formation by affecting osteoblastic differentiation and the fate of osteoblasts. In response to various cell signals, the tumor-suppressor protein p53 activates a huge range of genes, whose miRNAs promote genomic-integrity maintenance, cell-cycle arrest, cell senescence, and apoptosis. Here, we review the role of three p53-related miRNAs, miR-34c, -125b, and -203, in the bone-remodeling context and, in particular, in osteoblastic differentiation. The second aim of this study is to deal with the potential implication of these miRNAs in osteosarcoma development and progression.

miRNA-7 and miRNA-324-5p regulate alpha9-Integrin expression and exert anti-oncogenic effects in rhabdomyosarcoma

The prognosis of patients with metastatic rhabdomyosarcoma (RMS), the most common type of soft tissue sarcoma in children, is poor and no strategies have been identified to improve their dismal prognosis. Alpha-9 integrin (ITGA9) plays a particularly crucial role in cancer progression and invasiveness. Despite the consensus on the remarkable pro-oncogenic potential of this protein, the miRNA-mediated regulation of ITGA9 has barely been studied to date. In the present study, miR-7 and miR-324-5p were selected as the best candidates after a screening to find ITGA9 regulators, and their effects on cell proliferation and invasion in RMS are described and characterized for the first time. Interestingly, the overexpression of both miRNA produced a clear impairment of cell proliferation, while miR-7 also induced a remarkable drop in cell invasion. Furthermore, the stable overexpression of both miRNA was found to reduce tumor growth in orthotopic RMS models and miR-7 was able to impair metastatic lung colonization. Consequently, we conclude that miR-7 and miR-324-5p show anti-oncogenic and anti-metastatic potential, thereby opening up the possibility of being used as novel therapeutic tools to avoid RMS progression.

Aberrantly expressed microRNAs and their implications in childhood central nervous system tumors

Even though the treatment of childhood cancer has evolved significantly in recent decades, aggressive central nervous system (CNS) tumors are still a leading cause of morbidity and mortality in this population. Consequently, the identification of molecular targets that can be incorporated into diagnostic practice, effectively predict prognosis, follow treatment response, and materialize into potential targeted therapeutic approaches are still warranted. Since the first evidence of the participation of miRNAs in cancer development and progression 20 years ago, notable progress has been made in the basic understanding of the contribution of their dysregulation as epigenetic driver of tumorigenesis. Nevertheless, among the plethora of articles in the literature, microRNA profiling of pediatric tumors are scarce. This article gives an overview of the recent advances in the diagnostic/prognostic potential of miRNAs in a selection of pediatric CNS tumors: medulloblastoma, ependymoma, pilocytic astrocytoma, glioblastoma, diffuse intrinsic pontine glioma, atypical teratoid/rhabdoid tumors, and choroid plexus tumors.

Medulloblastomics revisited: biological and clinical insights from thousands of patients

Medulloblastoma, a malignant brain tumour primarily diagnosed during childhood, has recently been the focus of intensive molecular profiling efforts, profoundly advancing our understanding of biologically and clinically heterogeneous disease subgroups. Genomic, epigenomic, transcriptomic and proteomic landscapes have now been mapped for an unprecedented number of bulk samples from patients with medulloblastoma and, more recently, for single medulloblastoma cells. These efforts have provided pivotal new insights into the diverse molecular mechanisms presumed to drive tumour initiation, maintenance and recurrence across individual subgroups and subtypes. Translational opportunities stemming from this knowledge are continuing to evolve, providing a framework for improved diagnostic and therapeutic interventions. In this Review, we summarize recent advances derived from this continued molecular characterization of medulloblastoma and contextualize this progress towards the deployment of more effective, molecularly informed treatments for affected patients.