Mutations in microRNA processing genes in Wilms tumors derepress the IGF2 regulator PLAG1

DROSHA Regulates Mesenchymal Gene Expression in Wilms Tumor

Wilms tumor, the most common pediatric kidney cancer, resembles embryonic renal progenitors. Currently, there are no ways to therapeutically target Wilms tumor driver mutations, such as in the microRNA processing gene DROSHA. In this study, we used a "multiomics" approach to define the effects of DROSHA mutation in Wilms tumor. We categorized Wilms tumor mutations into four mutational subclasses with unique transcriptional effects: microRNA processing, MYCN activation, chromatin remodeling, and kidney developmental factors. In particular, we find that DROSHA mutations are correlated with de-repressing microRNA target genes that regulate differentiation and proliferation and a self-renewing, mesenchymal state. We model these findings by inhibiting DROSHA expression in a Wilms tumor cell line, which led to upregulation of the cell cycle regulator cyclin D2 (CCND2). Furthermore, we observed that DROSHA mutations in Wilms tumor and DROSHA silencing in vitro were associated with a mesenchymal state with aberrations in redox metabolism. Accordingly, we demonstrate that Wilms tumor cells lacking microRNAs are sensitized to ferroptotic cell death through inhibition of glutathione peroxidase 4, the enzyme that detoxifies lipid peroxides. Implications: This study reveals genotype-transcriptome relationships in Wilms tumor and points to ferroptosis as a potentially therapeutic vulnerability in one subset of Wilms tumor.

The Role of PLAG1 in Mouse Brain Development and Neurogenesis

The pleomorphic adenoma gene 1 (Plag1) is a transcription factor involved in the regulation of growth and cellular proliferation. Here, we report the spatial distribution and functional implications of PLAG1 expression in the adult mouse brain. We identified Plag1 promoter-dependent β-galactosidase expression in various brain structures, including the hippocampus, cortex, choroid plexus, subcommisural organ, ependymal cells lining the third ventricle, medial and lateral habenulae and amygdala. We noted striking spatial-restriction of PLAG1 within the cornu ammonis (CA1) region of the hippocampus and layer-specific cortical expression, with abundant expression noted in all layers except layer 5. Furthermore, our study delved into the role of PLAG1 in neurodevelopment, focusing on its impact on neural stem/progenitor cell proliferation. Loss of Plag1 resulted in reduced proliferation and decreased production of neocortical progenitors in vivo, although ex vivo neurosphere experiments revealed no cell-intrinsic defects in the proliferative or neurogenic capacity of Plag1-deficient neural progenitors. Lastly, we explored potential target genes of PLAG1 in the cortex, identifying that Neurogenin 2 (Ngn2) was significantly downregulated in Plag1-deficient mice. In summary, our study provides novel insights into the spatial distribution of PLAG1 expression in the adult mouse brain and its potential role in neurodevelopment. These findings expand our understanding of the functional significance of PLAG1 within the brain, with potential implications for neurodevelopmental disorders and therapeutic interventions.

Pediatric fibromyxoid brachial plexus tumor with YWHAZ::PLAG1 gene fusion: a case report

Pediatric fibromyxoid soft tissue tumors may be associated with gene fusions such as YHWAZ::PLAG1, with only three reported cases in the literature. We present the fourth case, a 13-year-old male with a pediatric fibromyxoid brachial plexus tumor with YWHAZ::PLAG1 gene fusion. This is also the first case to be reported in an adolescent, in the brachial plexus, and in the Philippines. The patient presented with a 10-year history of a slowly growing left supraclavicular mass and a 1-year history of intermittent dysesthesia in the left upper extremity. Neurologic examination was unremarkable. Imaging revealed a large left supraclavicular lesion with intrathoracic extension. Surgical excision was performed, and histopathology revealed a fibromyxoid tumor with YWHAZ::PLAG1 gene fusion. Although previous examples of this gene fusion pointed toward lipoblastoma as their primary pathology, our tumor does not completely fulfill the current diagnostic criteria for a lipoblastoma and may represent an intermediate form of the disease. Our case is unique not only because it is the first reported adolescent patient harboring such a lesion but also because of the relatively lengthy natural history exhibited by the tumor prior to its resection. This provided us with valuable information about its behavior, which suggests a more indolent growth pattern. This case also highlights the clinical importance of molecular testing of tumors, where recognition of disease entities can assist clinicians in deciding and advocating for the proper management.

An imbalance between proliferation and differentiation underlies the development of microRNA-defective pineoblastoma

Mutations in the microRNA processing genes DICER1 and DROSHA drive several cancers that resemble embryonic progenitors. To understand how microRNAs regulate tumorigenesis, we ablated Drosha or Dicer1 in the developing pineal gland to emulate the pathogenesis of pineoblastoma, a brain tumor that resembles undifferentiated precursors of the pineal gland. Accordingly, these mice develop pineal tumors marked by loss of microRNAs, including the let-7/miR-98-5p family, and de-repression of microRNA target genes. Pineal tumors driven by loss of Drosha or Dicer1 mimic tumors driven by Rb1 loss, as they exhibit upregulation of S-phase genes and homeobox transcription factors that regulate pineal development. Blocking proliferation of these tumors facilitates expression of pinealocyte maturation markers, with a concomitant reduction in embryonic markers. Select embryonic markers remain elevated, however, as the microRNAs that normally repress these target genes remain absent. One such microRNA target gene is the oncofetal transcription factor Plagl2, which regulates expression of pro-growth genes, and inhibiting their signaling impairs tumor growth. Thus, we demonstrate that tumors driven by loss of microRNA processing may be therapeutically targeted by inhibiting downstream drivers of proliferation.

Ectopic PLAG1 induces muscular dystrophy in the mouse

Even though various genetic mutations have been identified in muscular dystrophies (MD), there is still a need to understand the biology of MD in the absence of known mutations. Here we reported a new mouse model of MD driven by ectopic expression of PLAG1. This gene encodes a developmentally regulated transcription factor known to be expressed in developing skeletal muscle, and implicated as an oncogene in certain cancers including rhabdomyosarcoma (RMS), an aggressive soft tissue sarcoma composed of myoblast-like cells. By breeding loxP-STOP-loxP-PLAG1 (LSL-PLAG1) mice into the MCK-Cre line, we achieved ectopic PLAG1 expression in cardiac and skeletal muscle. The Cre/PLAG1 mice died before 6 weeks of age with evidence of cardiomyopathy significantly limiting left ventricle fractional shortening. Histology of skeletal muscle revealed dystrophic features, including myofiber necrosis, fiber size variation, frequent centralized nuclei, fatty infiltration, and fibrosis, all of which mimic human MD pathology. QRT-PCR and Western blot revealed modestly decreased Dmd mRNA and dystrophin protein in the dystrophic muscle, and immunofluorescence staining showed decreased dystrophin along the cell membrane. Repression of Dmd by ectopic PLAG1 was confirmed in dystrophic skeletal muscle and various cell culture models. In vitro studies showed that excess IGF2 expression, a transcriptional target of PLAG1, phenocopied PLAG1-mediated down-regulation of dystrophin. In summary, we developed a new mouse model of a lethal MD due to ectopic expression of PLAG1 in heart and skeletal muscle. Our data support the potential contribution of excess IGF2 in this model. Further studying these mice may provide new insights into the pathogenesis of MD and perhaps lead to new treatment strategies.

Human IGF2 Gene Epigenetic and Transcriptional Regulation: At the Core of Developmental Growth and Tumorigenic Behavior

Regulation of the human IGF2 gene displays multiple layers of control, which secures a genetically and epigenetically predetermined gene expression pattern throughout embryonal growth and postnatal life. These predominantly nuclear regulatory mechanisms converge on the function of the IGF2-H19 gene cluster on Chromosome 11 and ultimately affect IGF2 gene expression. Deregulation of such control checkpoints leads to the enhancement of IGF2 gene transcription and/or transcript stabilization, ultimately leading to IGF-II peptide overproduction. This type of anomaly is responsible for the effects observed in terms of both abnormal fetal growth and increased cell proliferation, typically observed in pediatric overgrowth syndromes and cancer. We performed a review of relevant experimental work on the mechanisms affecting the human IGF2 gene at the epigenetic, transcriptional and transcript regulatory levels. The result of our work, indeed, provides a wider and diversified scenario for IGF2 gene activation than previously envisioned by shedding new light on its extended regulation. Overall, we focused on the functional integration between the epigenetic and genetic machinery driving its overexpression in overgrowth syndromes and malignancy, independently of the underlying presence of loss of imprinting (LOI). The molecular landscape provided at last strengthens the role of IGF2 in cancer initiation, progression and malignant phenotype maintenance. Finally, this review suggests potential actionable targets for IGF2 gene- and regulatory protein target-degradation therapies.

WILMS TUMOR MUTATIONAL SUBCLASSES CONVERGE TO DRIVE CCND2 OVEREXPRESSION

Wilms tumor, the most common kidney cancer in pediatrics, arises from embryonic renal progenitors. Although many patients are cured with multimodal therapy, outcomes remain poor for those with high-risk features. Recent sequencing efforts have provided few biological or clinically actionable insights. Here, we performed DNA and RNA sequencing on 94 Wilms tumors to understand how Wilms tumor mutations transform the transcriptome to arrest differentiation and drive proliferation. We show that most Wilms tumor mutations fall into four classes, each with unique transcriptional signatures: microRNA processing, MYCN activation, chromatin remodeling, and kidney development. In particular, the microRNA processing enzyme DROSHA is one of the most commonly mutated genes in Wilms tumor. We show that DROSHA mutations impair pri-microRNA cleavage, de-repress microRNA target genes, halt differentiation, and overexpress cyclin D2 (CCND2). Several mutational classes converge to drive CCND2 overexpression, which could render them susceptible to cell-cycle inhibitors.

Lipoblastoma in one adult and 35 pediatric patients: Retrospective analysis of 36 cases

Lipoblastoma is a rare benign mesenchymal neoplasm that typically occurs at various sites in infants and children but may also occur in adults. Thus, differential diagnoses are often performed. To understand this tumor type, the present study described clinicopathological features, diagnosis and differential diagnosis of different morphological lipoblastomas. A single-institution retrospective review of 36 lipoblastoma cases diagnosed between 2015 and 2021 was performed. Formalin-fixed paraffin-embedded tissue was used for S-100, CD34, P16 and desmin immunohistochemistry analysis, along with rapid fluorescence in situ hybridization (FISH) detection with pleiomorphic adenoma gene 1 (PLAG1). The 36 cases included 14 females and 22 males [age range, 7 days to 33 years (median, 16.5 years); 28 patients were aged ≤3 years] and the tumors were located in the trunk (n=16), limbs (n=12), head and neck (n=6), and perineum (n=2). Histologically, lipoblastomas were divided into classic (n=15), lipoma-like (n=13) and myxoid (n=8) subtypes. They comprised lobules of mature adipose tissue of varying size and a fine capillary network surrounded by mucinous stroma. Single- or multivesicular lipoblasts positive for S-100 (29/36, 81%) were observed, with occasional mature adipocytes. Peripheral vessels and cytoplasm of primitive mesenchymal cells were diffusely positive for CD34 (36/36, 100%), whereas primitive mesenchymal cells and striated muscle tissue were positive for desmin (26/36, 72%). Most tumor cells were negative while only few were positive for P16 (8/36, 22%). FISH revealed PLAG1 breakage and rearrangement in 24/32 (75%) patients. In total, 28 patients were followed up post-operatively (range, 2-84 months; median, 41 months; 3 patients relapsed and 8 were lost to follow-up). In conclusion, diagnosis of a typical lipoblastoma is not difficult and PLAG1 breakage detection is key for the diagnosis.

Non-coding RNAs: The link between maternal malnutrition and offspring metabolism

Early life nutrition is associated with the development and metabolism in later life, which is known as the Developmental Origin of Health and Diseases (DOHaD). Epigenetics have been proposed as an important explanation for this link between early life malnutrition and long-term diseases. Non-coding RNAs (ncRNAs) may play a role in this epigenetic programming. The expression of ncRNAs (such as long non-coding RNA H19, microRNA-122, and circular RNA-SETD2) was significantly altered in specific tissues of offspring exposed to maternal malnutrition. Changes in these downstream targets of ncRNAs lead to abnormal development and metabolism. This review aims to summarize the existing knowledge on ncRNAs linking the maternal nutrition condition and offspring metabolic diseases, such as obesity, type 2 diabetes (T2D) and non-alcoholic fatty liver disease (NAFLD).

Pediatric fibromyxoid tumor with PLAG1 fusion: An emerging entity with a novel intracranial location

Translocations involving PLAG1 occur in several tumors, most commonly pleomorphic adenoma and lipoblastoma. Recently, a distinctive soft tissue tumor with a PLAG1 fusion has been reported in the pediatric age group. These are low grade tumors with a fibroblastic or mixed fibroblastic and myxoid morphology but no other lines of differentiation. They are typically immunopositive for desmin and CD34. The partner genes for these tumors have included YWHAZ, EEF1A1, ZFHX4l, CHCHD7, and PCMTD1. We report another case of this fibromyxoid tumor with a PLAG1 fusion, this time with COL3A1 as the partner gene. The fusion placed expression of a full-length PLAG1 protein under the control of the constitutively active COL3A1 promoter. Overexpression of PLAG1 was confirmed by diffusely positive immunostaining for PLAG1. The most novel aspect of this tumor is the intracranial location. Opinion has been divided over whether these tumors are a specific entity, or related to lipoblastoma, since that tumor also typically occurs in soft tissue in the pediatric age group and shows many of the same gene fusions. However, lipoblastoma has never been reported in an intracranial location and, thus, our case provides compelling evidence that this fibromyxoid tumor is indeed a distinct entity.

MicroRNAs in kidney development and disease

MicroRNAs (miRNAs) belong to a class of endogenous small noncoding RNAs that regulate gene expression at the posttranscriptional level, through both translational repression and mRNA destabilization. They are key regulators of kidney morphogenesis, modulating diverse biological processes in different renal cell lineages. Dysregulation of miRNA expression disrupts early kidney development and has been implicated in the pathogenesis of developmental kidney diseases. In this Review, we summarize current knowledge of miRNA biogenesis and function and discuss in detail the role of miRNAs in kidney morphogenesis and developmental kidney diseases, including congenital anomalies of the kidney and urinary tract and Wilms tumor. We conclude by discussing the utility of miRNAs as potentially novel biomarkers and therapeutic agents.

Research advances in the targeted therapy and immunotherapy of Wilms tumor: a narrative review

Wilms tumor is the most common pediatric abdominal solid tumor, and its treatment has been a focus of research. For now, the 5-year survival rate of children with Wilms tumor is about 90%. It is difficult to make further progress simply by the improvement of the existing treatments (multi-modal therapy). Therefore, targeted therapy and immunotherapy which have high accuracy and few side effects began to be considered for the treatment of Wilms tumor. At present, though targeted therapy and immunotherapy are rarely used in the treatment of Wilms tumor except in clinical trials, there are dozens of clinical trials research them around the world. The sites in targeted therapy research are mainly focused on insulin-like growth factor 2 (IGF2) pathway, anti-angiogenesis, phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway, and some miRNAs, etc. And there are three types of study in Wilms tumor immunotherapy, which are inhibition of the COX-2 pathway, chimeric antigen receptor (CAR)-T cell therapy, and multi-tumor associated antigen (TAA)-specific cytotoxic T lymphocytes (CTL) therapy. Among them, the phase I clinical trial of multi-TAA-specific CTL (MTAA-CTL) therapy has been completed, and the results are very satisfactory. In this narrative review, we review the basic research and relevant clinical research on targeted therapy and immunotherapy for Wilms tumor.

Sequencing of Argonaute-bound microRNA/mRNA hybrids reveals regulation of the unfolded protein response by microRNA-320a

MicroRNAs (miRNA) are short non-coding RNAs widely implicated in gene regulation. Most metazoan miRNAs utilize the RNase III enzymes Drosha and Dicer for biogenesis. One notable exception is the RNA polymerase II transcription start sites (TSS) miRNAs whose biogenesis does not require Drosha. The functional importance of the TSS-miRNA biogenesis is uncertain. To better understand the function of TSS-miRNAs, we applied a modified Crosslinking, Ligation, and Sequencing of Hybrids on Argonaute (AGO-qCLASH) to identify the targets for TSS-miRNAs in HCT116 colorectal cancer cells with or without DROSHA knockout. We observed that miR-320a hybrids dominate in TSS-miRNA hybrids identified by AGO-qCLASH. Targets for miR-320a are enriched for the eIF2 signaling pathway, a downstream component of the unfolded protein response. Consistently, in miR-320a mimic- and antagomir- transfected cells, differentially expressed gene products are associated with eIF2 signaling. Within the AGO-qCLASH data, we identified the endoplasmic reticulum (ER) chaperone calnexin as a direct miR-320a down-regulated target, thus connecting miR-320a to the unfolded protein response. During ER stress, but not amino acid deprivation, miR-320a up-regulates ATF4, a critical transcription factor for resolving ER stress. In summary, our study investigates the targetome of the TSS-miRNAs in colorectal cancer cells and establishes miR-320a as a regulator of unfolded protein response.

Recent advances in Wilms' tumor predisposition

Wilms' tumor (WT), the most common childhood kidney cancer, develops in association with an underlying germline predisposition in up to 15% of cases. Germline alterations affecting the WT1 gene and epigenetic alterations affecting the 11p15 locus are associated with a selective increase in WT risk. Nevertheless, WT also occurs in the context of more pleiotropic cancer predispositions, such as DICER1, Li-Fraumeni and Bloom syndrome, as well as Fanconi anemia. Recent germline genomic investigations have increased our understanding of the host genetic factors that influence WT risk, with sequencing of rare familial cases and large WT cohorts revealing an expanding array of predisposition genes and associated genetic conditions. Here, we describe evidence implicating WT1, the 11p15 locus, and the recently identified genes CTR9, REST and TRIM28 in WT predisposition. We discuss the clinical features, mode of inheritance and biological aspects of tumorigenesis, when known. Despite these described associations, many cases of familial WT remain unexplained. Continued investigations are needed to fully elucidate the landscape of germline genetic alterations in children with WT. Establishing a genetic diagnosis is imperative for WT families so that individuals harboring a predisposing germline variant can undergo surveillance, which should enable the early detection of tumors and use of less intensive treatments, thereby leading to improved overall outcomes.

Postnatal prolongation of mammalian nephrogenesis by excess fetal GDNF

Nephron endowment, defined during the fetal period, dictates renal and related cardiovascular health throughout life. We show here that, despite its negative effects on kidney growth, genetic increase of GDNF prolongs the nephrogenic program beyond its normal cessation. Multi-stage mechanistic analysis revealed that excess GDNF maintains nephron progenitors and nephrogenesis through increased expression of its secreted targets and augmented WNT signaling, leading to a two-part effect on nephron progenitor maintenance. Abnormally high GDNF in embryonic kidneys upregulates its known targets but also Wnt9b and Axin2, with concomitant deceleration of nephron progenitor proliferation. Decline of GDNF levels in postnatal kidneys normalizes the ureteric bud and creates a permissive environment for continuation of the nephrogenic program, as demonstrated by morphologically and molecularly normal postnatal nephron progenitor self-renewal and differentiation. These results establish that excess GDNF has a bi-phasic effect on nephron progenitors in mice, which can faithfully respond to GDNF dosage manipulation during the fetal and postnatal period. Our results suggest that sensing the signaling activity level is an important mechanism through which GDNF and other molecules contribute to nephron progenitor lifespan specification.

Summary: Dosage of neurotropic factor GDNF regulates nephron progenitors and in utero growth factor augmentation can extend postnatal lifespan and differentiation of nephron progenitors.

Pediatric fibromyxoid soft tissue tumor with PLAG1 fusion: A novel entity?

The classification of undifferentiated soft tissue tumors continues to evolve with the expanded application of molecular analysis in clinical practice. We report three cases of a unique soft tissue tumor in young children (5 months to 2 years old) displaying a purely fibromyxoid histology, with positive staining for desmin and CD34. In two cases, RNA sequencing detected a YWHAZ-PLAG1 gene fusion, while in the third case, a previously unreported EEF1A1-PLAG1 fusion was identified. PLAG1 fusions have been reported in several pathologic entities including pleomorphic adenoma, myoepithelial tumors of skin and soft tissue, and lipoblastoma, the latter occurring preferentially in young children. In these tumors, expression of a full length PLAG1 protein comes under the control of the constitutively active promoter of the partner gene in the fusion, and the current cases conform to that model. Overexpression of PLAG1 was confirmed by diffusely positive immunostaining for PLAG1 in all three cases. Our findings raise the possibility of a novel fibromyxoid neoplasm in childhood associated with these rare PLAG1 fusion variants. The only other report of a PLAG1-YWHAZ fusion occurred in a pediatric tumor diagnosed as a "fibroblastic lipoblastoma." This finding raises the possibility of a relationship with our three cases, even though our cases lacked any fat component. Further studies with regard to a shared pathogenesis are required.

Embryonic Kidney Development, Stem Cells and the Origin of Wilms Tumor

The adult mammalian kidney is a poorly regenerating organ that lacks the stem cells that could replenish functional homeostasis similarly to, e.g., skin or the hematopoietic system. Unlike a mature kidney, the embryonic kidney hosts at least three types of lineage-specific stem cells that give rise to (a) a ureter and collecting duct system, (b) nephrons, and (c) mesangial cells together with connective tissue of the stroma. Extensive interest has been raised towards these embryonic progenitor cells, which are normally lost before birth in humans but remain part of the undifferentiated nephrogenic rests in the pediatric renal cancer Wilms tumor. Here, we discuss the current understanding of kidney-specific embryonic progenitor regulation in the innate environment of the developing kidney and the types of disruptions in their balanced regulation that lead to the formation of Wilms tumor.

[MicroRNA-200c-3p inhibits proliferation of nephroblastoma cells by targeting CCNE2]

OBJECTIVE

To predict and verify the target gene of miR-200c-3p and evaluate the inhibitory effect of miR-200c-3p on the proliferation of nephroblastoma cells.

METHODS

The putative target genes of miR-200c-3p were predicted by bioinformatics approach. Nephroblastoma cell models with miR-200c-3p overexpression or knockdown were established in SK-NEP-1 and G401 cells with corresponding control groups. The expressions of CCNE2 in SK-NEP-1 and G401 cells in different groups were detected by RT-PCR and Western blotting. A luciferase reporter assay was used to determine the targeting relationship between miR-200c-3p and CCNE2. The effects of miR-200c-3p overexpression or knockdown on cell proliferation was detected by cell counting kit-8 (CCK-8) assay and soft agarose assay.

RESULTS

CCNE2 was one of the target genes of miR-200c-3p as predicted by bioinformatics methods. Transfection of the two nephroblastoma cell lines with miR-200c-3p mimic resulted in significantly lowered CCNE2 mRNA and protein expressions (P < 0.05). The results of dual-luciferase assay confirmed that miR-200c-3p bound to the 3'UTR of CCNE2. CCK-8 assay and soft agarose assay demonstrated that overexpression of miR-200c-3p significantly inhibited the proliferation of the nephroblastoma cells (P < 0.01), and knocking down miR-200c-3p in the cells produced the opposite effects.

CONCLUSIONS

miR-200c-3p overexpression inhibits the proliferation of nephroblastoma cells by down-regulating its target gene CCNE2.

The biological and diagnostic roles of MicroRNAs in meningiomas

MicroRNAs (miRNAs) refer to a class of small endogenous non-coding RNAs that regulate gene expression at the post-transcriptional level. Emerging studies have shown that miRNAs play critical roles in tumorigenesis and cancer progression. However, roles and mechanisms of miRNA dysregulation in the pathogenesis of meningioma are not fully understood. Here, we first reviewed existing research of aberrantly expressed miRNAs identified by high throughput microarray profiling in meningioma. We also explored the potential of miRNA as biomarkers and therapeutic targets for novel treatment paradigms of meningiomas. In addition, we summarized recent researches that focused on the possible mechanisms involved in miRNA-mediate meningioma occurrence and progression. This review provides an overview of miRNA deregulation in meningioma and indicates the potential of miRNAs to be used as biomarkers or novel therapeutic targets.

Uncovering the cellular capacity for intensive and specific feedback self-control of the argonautes and MicroRNA targeting activity

The miRNA pathway has three segments—biogenesis, targeting and downstream regulatory effectors. We aimed to better understand their cellular control by exploring the miRNA-mRNA-targeting relationships. We first used human evolutionarily conserved sites. Strikingly, AGOs 1–3 are all among the top 14 mRNAs with the highest miRNA site counts, along with ANKRD52, the phosphatase regulatory subunit of the recently identified AGO phosphorylation cycle; and the AGO phosphorylation cycle mRNAs share much more than expected miRNA sites. The mRNAs for TNRC6, which acts with AGOs to channel miRNA-mediated regulatory actions onto specific mRNAs, are also heavily miRNA-targeted. In contrast, upstream miRNA biogenesis mRNAs are not, and neither are downstream regulatory effectors. In short, binding site enrichment in miRNA targeting machinery mRNAs, but neither upstream biogenesis nor downstream effector mRNAs, was observed, endowing a cellular capacity for intensive and specific feedback control of the targeting activity. The pattern was confirmed with experimentally determined miRNA-mRNA target relationships. Moreover, genetic experiments demonstrated cellular utilization of this capacity. Thus, we uncovered a capacity for intensive, and specific, feedback-regulation of miRNA targeting activity directly by miRNAs themselves, i.e. segment-specific feedback auto-regulation of miRNA pathway, complementing miRNAs pairing with transcription factors to form hybrid feedback-loop.

MiR-155-5p exerts tumor-suppressing functions in Wilms tumor by targeting IGF2 via the PI3K signaling pathway

BACKGROUND

MicroRNA-155-5p (miR-155-5p) has been reported to play an oncogenic role in different human malignancies; however, its role in Wilms tumor (WT) remains unclear.

METHODS

Differentially expressed miRNAs (DE-miRNAs) and mRNAs (DEGs) in WT blood and tissues were identified by using miRNA microarray and RNA-sequencing. Bioinformatics prediction and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were used to predict the potential functions of DE-miRNAs. DE-miRNAs and DEGs in WT obtained from Gene Expression Omnibus (GEO) and Therapeutically Applicable Research to Generate Effective Treatments (TARGET) were identified by using the "edgeR" package. RT-qPCR was used to explore miR-155-5p and IGF2 expression and their clinical significance in WT specimens. A rhabdoid cell line (G401) and Ewing sarcoma cell line (SK-NEP-1) were used. Immunohistochemical staining, western blotting and dual-luciferase reporter assays were performed to study the mechanisms involved. The CCK-8, flow cytometry, wound healing and transwell assays were performed to identify the effects of miR-155-5p and IGF2 knockdown on cell proliferation, apoptosis, migration and invasion, respectively.

RESULTS

MiR-155-5p was downregulated in both blood and tissues from WT patients who did not receive chemotherapy before surgery but was upregulated in tissues from WT patients who had received chemotherapy before surgery. IGF2, PI3K, AKT and mTOR were found to be upregulated in WT tissues. Additionally, miR-155-5p and IGF2 were significantly correlated with TNM stage and lymphatic metastasis in WT patients. Molecular mechanism exploration indicated that IGF2 was downregulated by miR-155-5p via direct binding to its 3' untranslated region in cell lines. Furthermore, IGF2, PI3K, AKT and mTOR expression was inversely correlated with miR-155-5p expression, and PI3K, AKT and mTOR expression was positively correlated with IGF2 expression in cell culture. Functional studies demonstrated that miR-155-5p upregulation and IGF2 knockdown suppressed cell proliferation, migration and invasion and induced cell apoptosis. Moreover, the tumor-suppressing effects of miR-155-5p in cells were abrogated by miR-155-5p inhibitor treatment.

CONCLUSIONS

Taken together, these findings suggest that miR-155-5p functions as a tumor suppressor in WT through inactivating the PI3K/AKT/mTOR signaling pathway by directly targeting IGF2. Thus, miR-155-5p might be a novel therapeutic target for WT.

The association of RAN and RANBP2 gene polymerphisms with Wilms tumor risk in Chinese children

Wilms tumor is considered to be the most common renal malignancy among children. RAN, a member of RAS superfamily, and its binding partner RANBP2 are related to the progression of multiple tumors. Nevertheless, the effects of the RAN and RANBP2 gene polymorphisms on the tumorigenesis of Wilms tumor remain unclarified. In this study, three potentially functional polymorphisms (rs56109543 C>T, rs7132224 A>G, and rs14035 C>T) in the RAN and one (rs2462788 C>T) in the RANBP2 were chosen to investigate their association with Wilms tumor susceptibility. Odds ratios (ORs) and 95% confidence intervals (CIs) were applied to assess the association of the selected polymorphisms with Wilms tumor susceptibility. Results shown that RAN rs7132224 AG/GG genotypes significantly increased Wilms tumor risk when compared to AA genotype (adjusted OR=1.40, 95% CI=1.01-1.95, P=0.047). Carriers of 1-3 risk genotypes have a significantly higher Wilms tumor risk than those without risk genotype (adjusted OR=1.49, 95% CI=1.07-2.07, P=0.020). Moreover, stratified analysis indicated that RAN rs56109543 CT/TT genotypes, RAN rs7132224 AG/GG genotypes and RANBP2 rs2462788 CT/TT genotypes remarkably increased Wilms tumor susceptibility among the subgroups. Our results indicated that RAN and RANBP2 polymorphisms were associated with Wilms tumor susceptibility in Chinese children. The role of RAN/RANBP2 in cancers deserves more attention.

Mouse Models of Congenital Kidney Anomalies

Congenital anomalies of the kidney and urinary tract (CAKUT) are common birth defects, which cause the majority of chronic kidney diseases in children. CAKUT covers a wide range of malformations that derive from deficiencies in embryonic kidney and lower urinary tract development, including renal aplasia, hypodysplasia, hypoplasia, ectopia, and different forms of ureter abnormalities. The majority of the genetic causes of CAKUT remain unknown. Research on mutant mice has identified multiple genes that critically regulate renal differentiation. The data generated from this research have served as an excellent resource to identify the genetic bases of human kidney defects and have led to significantly improved diagnostics. Furthermore, genetic data from human CAKUT studies have also revealed novel genes regulating kidney differentiation.

[Expression of miR-155-5p in Wilms tumor and its regulatory role in proliferation, migration and apoptosis of Wilms tumor cells in vitro]

OBJECTIVE

explore the expression of miR-155-5p in Wilms tumor and its effect in regulating the proliferation, migration and apoptosis of Wilms tumor cells.

METHODS

Specimens of tumor tissues and paired adjacent tissues were obtained from 40 patients with Wilms tumor for detection of the expression levels of miR-155-5p using RT-qPCR. Wilms tumor cell line G401 was transfected with miR-155-5p mimics and miR-155-5p inhibitor to induce miR-155-5p over-expression and its inhibition, respectively, and the changes in the cell proliferation, migration and apoptosis were assessed using cell counting kit-8 (CCK-8), wound healing assay and fl ow cytometry.

RESULTS

RT-qPCR showed that the expression of miR-155-5p decreased significantly in Wilms tumor tissues as compared with normal kidney tissues and was significantly associated with TNM stage (P < 0.05). In G401 cells, over-expression of miR-155-5p significantly inhibited the cell proliferation and migration and promoted cell apoptosis (P < 0.05), and down-regulation of miR-155-5p obviously enhanced the proliferation and migration and suppressed apoptosis of the cells (P < 0.05).

CONCLUSIONS

miR-155-5p is down-regulated in Wilms tumor and its expression level is correlated with TNM stage. miR-155-5p participates in the progression of Wilms tumor by inhibiting the proliferation and migration and promoting apoptosis of the tumor cells, and may serve as a novel biomarker for diagnosis, therapy and prognostic evaluation of Wilms tumor.

Construction of miRNA-target networks using microRNA profiles of CVB3-infected HeLa cells

MicroRNAs (miRNAs) play an important role in regulating gene expression in multiple biological processes and diseases. Thus, to understand changes in miRNA during CVB3 infection, specific miRNA expression profiles were investigated at 3 h, 6 h, and 9 h postinfection in HeLa cells by small-RNA high-throughput sequencing. Biological implications of 68 differentially expressed miRNAs were analyzed through GO and KEGG pathways. Interaction networks between 34 known highly differentially expressed miRNAs and targets were constructed by mirDIP and Navigator. The predicted targets showed that FAM135A, IKZF2, PLAG1, ZNF148, PHC3, LCOR and DYRK1A, which are associated with cellular differentiation and transcriptional regulation, were recognized by 8 miRNAs or 9 miRNAs through interactional regulatory networks. Seven target genes were confirmed by RT-qPCR. The results showed that the expression of DYRK1A, FAM135A, PLAG1, ZNF148, and PHC3 were obviously inhibited at 3 h, 6 h, and 9 h postinfection. The expression of LCOR did not show a significant change, and the expression of IKZF2 increased gradually with prolonged infection time. Our findings improve the understanding of the pathogenic mechanism of CVB3 infection on cellular differentiation and development through miRNA regulation, which has implications for interventional approaches to CVB3-infection therapy. Our results also provide a new method for screening target genes of microRNA regulation in virus-infected cells.

Bayesian Modeling Identifies PLAG1 as a Key Regulator of Proliferation and Survival in Rhabdomyosarcoma Cells

We recently developed a novel computational algorithm that incorporates Bayesian methodology to identify rhabdomyosarcoma disease genes whose expression level correlates with copy-number variations, and we identified PLAG1 as a candidate oncogenic driver. Although PLAG1 has been shown to contribute to other type of cancers, its role in rhabdomyosarcoma has not been elucidated. We observed that PLAG1 mRNA is highly expressed in rhabdomyosarcoma and is associated with PLAG1 gene copy-number gain. Knockdown of PLAG1 dramatically decreased cell accumulation and induced apoptosis in rhabdomyosarcoma cells, whereas its ectopic expression increased cell accumulation in vitro and as a xenograft and promoted G₁ to S-phase cell-cycle progression. We found that PLAG1 regulates IGF2 expression and influences AKT and MAPK pathways in rhabdomyosarcoma, and IGF2 partially rescues cell death triggered by PLAG1 knockdown. The expression level of PLAG1 correlated with the IC₅₀ of rhabdomyosarcoma cells to BMS754807, an IGF receptor inhibitor. IMPLICATIONS: Our data demonstrate that PLAG1 contributes to proliferation and survival of rhabdomyosarcoma cells at least partially by inducing IGF2, and this new understanding may have the potential for clinical translation.

Associations between miR-146a rs2910164 polymorphisms and risk of ischemic cardio-cerebrovascular diseases

BACKGROUND

Many studies investigated the association between miR-146a rs2910164 polymorphisms and risk of ischemic cardio-cerebrovascular diseases. However, the results were inconsistent.

METHODS

We searched the PubMed, EMBASE, Cochrane library, Web of Science, Chinese National Knowledge Infrastructure, VIP, and Wanfang databases for appropriate studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to evaluate the associations. Heterogeneity, sensitivity, and publication bias were conducted to measure the robustness of our findings.All analyses were based on previous published studies, thus, no ethical approval and patient consent are required.

RESULTS

We conducted a meta-analysis to evaluate the relationship between miR-146a rs2910164 polymorphisms and risk of ischemic cardio-cerebrovascular diseases. A total of 26 related studies involving 11,602 cases and 14,016 controls were identified and included in our meta-analysis. After considering the heterogeneity of the global analysis, we inferred that rs2910164 polymorphisms were associated with a lower risk of coronary heart disease (CHD) significantly in all genetic models. In addition, it was also found that the miR-146a rs2910164 polymorphisms were associated with the low risk of ischemic cardio-cerebrovascular diseases in large sample size subgroup analysis.

CONCLUSION

These results indicate that miR-146a rs2910164 polymorphisms were significantly associated with a lower risk of ischemic cardio-cerebrovascular. The miR-146a rs29101164 might be recommended as a predictor for susceptibility of ischemic cardio-cerebrovascular diseases.

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.

Overgrowth syndromes and pediatric cancers: how many roads lead to IGF2?

In this Perspective, Bharathavikru and Hastie discuss recent studies published by Hunter et al., investigating the molecular mechanisms by which mutations in the gene encoding the RNA degradation component DIS3L2 lead to Perlman syndrome, and Chen et al., who show that microRNA processing gene mutations in Wilms tumor leads to an increase in the levels of transcription factor PLAG1 that in turn activates IGF2 expression.

Overgrowth syndromes such as Perlman syndrome and associated pediatric cancers, including Wilms tumor, arise through genetic and, in certain instances, also epigenetic changes. In the case of the Beckwith-Wiedemann overgrowth syndrome and in Wilms tumor, increased levels of IGF2 have been shown to be causally related to the disease manifestation. In the previous issue of Genes & Development, Hunter and colleagues (pp. 903–908) investigated the molecular mechanisms by which mutations in the gene encoding the RNA degradation component DIS3L2 lead to Perlman syndrome. By analyzing nephron progenitor cells derived from their newly created Dis3l2 mutant mouse lines, the investigators showed that DIS3L2 loss of function leads to up-regulation of IGF2 independently of the let7 microRNA pathway. In a second study in this issue of Genes & Development, Chen and colleagues (pp. 996–1007) show that microRNA processing gene mutations in Wilms tumor lead to an increase in the levels of transcription factor pleomorphic adenoma gene 1 (PLAG1) that in turn activates IGF2 expression. Thus, augmented IGF2 expression seems to be a common downstream factor in both tissue overgrowth and Wilms tumor through several alternative mechanisms.

HnRNPL promotes Wilms tumor progression by regulating the p53 and Bcl2 pathways

Background: Wilms tumor (WT) is the most common renal tumor in children with diffusely anaplastic or unfavorable histology, indicative of a poor prognosis. Heterogeneous nuclear ribonucleoprotein L (hnRNPL) is an RNA-binding protein (RBP) and a regulator of alternative RNA splicing that plays an important role in the occurrence and development of several cancers. Methods: Next generation sequencing technologies was used to discovery differentially expressed genes between WT and adjacent nontumors. The gene ontology (GO) analysis was performed to uncover the biological functions of differentially expressed genes, and the kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis was applied to find out the related signal pathways. Expression levelsof hnRNPL with WT tissues and cells were determined by RT-qPCR.After silencing hnRNPL, the expression of hnRNPL, p53 and Bcl-2 were detected by RT-qPCR and Western blot in WT cell line. The regulatory effects of hnRNPLon proliferative and apoptotic potentials of WT cells were evaluated by MTT and flow cytometry, respectively. RNA-binding protein immuno-precipitation was used to confirm the direct interaction of hnRNPL with p53 mRNA. Mouse xenograft models ofhnRNPL knockdown were established to test the functions in the growth of WT in vivo. Results: High levels of hnRNPL were expressed in WT tissues and cells. Functional analysis revealed that hnRNPL silencing suppressed cell proliferation and promoted cell apoptosis in WT. Molecular mechanism exploration indicated that hnRNPL directly targeted p53. Moreover, knockdown of hnRNPL inhibited the expression of p53 and Bcl2 in WT. Additionally, hnRNPL silencing inhibited the growth of xenograft tumors in vivo. Conclusion: HnRNPL act as p53 mRNA-binding protein, which plays an important role in the proliferation and apoptosis of WT through p53 and Bcl2 pathways and these findings provide new insights into the mechanism of WT pathogenesis.

MAPK/ERK Signaling in Regulation of Renal Differentiation

Congenital anomalies of the kidney and urinary tract (CAKUT) are common birth defects derived from abnormalities in renal differentiation during embryogenesis. CAKUT is the major cause of end-stage renal disease and chronic kidney diseases in children, but its genetic causes remain largely unresolved. Here we discuss advances in the understanding of how mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) activity contributes to the regulation of ureteric bud branching morphogenesis, which dictates the final size, shape, and nephron number of the kidney. Recent studies also demonstrate that the MAPK/ERK pathway is directly involved in nephrogenesis, regulating both the maintenance and differentiation of the nephrogenic mesenchyme. Interestingly, aberrant MAPK/ERK signaling is linked to many cancers, and recent studies suggest it also plays a role in the most common pediatric renal cancer, Wilms' tumor.