A microRNA-mediated regulatory loop modulates NOTCH and MYC oncogenic signals in B- and T-cell malignancies

Notch Inhibitors and BH3 Mimetics in T-Cell Acute Lymphoblastic Leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy with poor response to conventional therapy, derived from hematopoietic progenitors committed to T-cell lineage. Relapsed/Refractory patients account for nearly 20% of childhood and 45% of adult cases. Aberrant Notch signaling plays a critical role in T-ALL pathogenesis and therapy resistance. Notch inhibition is a promising therapeutic target for personalized medicine, and a variety of strategies to prevent Notch activation, including γ-secretase (GS) inhibitors (GSIs) and antibodies neutralizing Notch receptors or ligands, have been developed. Disruption of apoptosis is pivotal in cancer development and progression. Different reports evidenced the interplay between Notch and the anti-apoptotic Bcl-2 family proteins in T-ALL. Although based on early research data, this review discusses recent advances in directly targeting Notch receptors and the use of validated BH3 mimetics for the treatment of T-ALL and their combined action in light of current evidence of their use.

IRF8-mutant B cell lymphoma evades immunity through a CD74-dependent deregulation of antigen processing and presentation in MHCII complexes

The mechanism by which interferon regulatory factor 8 (IRF8) mutation contributes to lymphomagenesis is unknown. We modeled IRF8 variants in B cell lymphomas and found that they affected the expression of regulators of antigen presentation. Expression of IRF8 mutants in murine B cell lymphomas suppressed CD4, but not CD8, activation elicited by antigen presentation and downmodulated CD74 and human leukocyte antigen (HLA) DM, intracellular regulators of antigen peptide processing/loading in the major histocompatibility complex (MHC) II. Concordantly, mutant IRF8 bound less efficiently to the promoters of these genes. Mice harboring IRF8 mutant lymphomas displayed higher tumor burden and remodeling of the tumor microenvironment, typified by depletion of CD4, CD8, and natural killer cells, increase in regulatory T cells and T follicular helper cells. Deconvolution of bulk RNA sequencing data from IRF8-mutant human diffuse large B cell lymphoma (DLBCL) recapitulated part of the immune remodeling detected in mice. We concluded that IRF8 mutations contribute to DLBCL biology by facilitating immune escape.

NCAPD3 exerts tumor-promoting effects in prostatic cancer via dual impact on miR-30a-5p by STAT3-MALAT1 and MYC

Non-SMC condensin II complex subunit D3 (NCAPD3) is a subunit of the non-structural maintenance of chromosomes condensin II complex, which involves chromosome condensation and segregation during mitosis. NCAPD3 has recently been demonstrated as a crucial oncogenic factor. However, the underlying mechanism of NCAPD3 in prostate cancer (PCa) remains not completely clear. In this study, we confirmed that lncRNA MALAT1 was induced by NCAPD3-STAT3, and the expression of miR-30a-5p was controlled by NCAPD3 in PCa cells by miRNA-seq. Through quantitative real-time PCR, fluorescence in situ hybridization, western blotting, and immunohistochemistry assay, we demonstrated that miR-30a-5p was lowly expressed in PCa cells and tissues compared to the controls, which was contrary to NCAPD3 expression and markedly downregulated by NCAPD3. Then, MALAT1 was analyzed for the complementary sequence in the potential interaction with miR-30a-5p by using the predicted target module of public databases. Dual-luciferase reporter assay and RNA immunoprecipitation were carried out to verify that MALAT1 functioned as a sponge for miR-30a-5p to reduce miR-30a-5p expression. Meanwhile, MYC acted as a transcriptional repressor to directly bind the promoter of the miR-30a-5p located gene and repress the miR-30a-5p expression. Furthermore, the upregulation of NCAPD3 on cell viability and migration was significantly attenuated in PC-3 cells when miR-30a-5p was overexpressed. NCAPD3 overexpression also accelerated tumor growth in the xenograft mouse model and repressed miR-30-5p. In summary, this work elucidates NCAPD3 inhibits miR-30a-5p through two pathways: increasing STAT3-MALAT1 to sponge miR-30a-5p and increasing MYC to directly inhibit miR-30a-5p transcription, which could serve as potential therapeutic targets for prostate cancer.

IRF8-mutant B cell lymphoma evades immunity through a CD74-dependent deregulation of antigen processing and presentation in MHC CII complexes

In diffuse large B-cell lymphoma (DLBCL), the transcription factor IRF8 is the target of a series of potentially oncogenic events, including, chromosomal translocation, focal amplification, and super-enhancer perturbations. IRF8 is also frequently mutant in DLBCL, but how these variants contribute to lymphomagenesis is unknown. We modeled IRF8 mutations in DLBCL and found that they did not meaningfully impact cell fitness. Instead, IRF8 mutants, mapping either to the DNA-binding domain (DBD) or c-terminal tail, displayed diminished transcription activity towards CIITA, a direct IRF8 target. In primary DLBCL, IRF8 mutations were mutually exclusive with mutations in genes involved in antigen presentation. Concordantly, expression of IRF8 mutants in murine B cell lymphomas uniformly suppressed CD4, but not CD8, activation elicited by antigen presentation. Unexpectedly, IRF8 mutation did not modify MHC CII expression on the cell surface, rather it downmodulated CD74 and HLA- DM, intracellular regulators of antigen peptide processing/loading in the MHC CII complex. These changes were functionally relevant as, in comparison to IRF8 WT, mice harboring IRF8 mutant lymphomas displayed a significantly higher tumor burden, in association with a substantial remodeling of the tumor microenvironment (TME), typified by depletion of CD4, CD8, Th1 and NK cells, and increase in T-regs and Tfh cells. Importantly, the clinical and immune phenotypes of IRF8-mutant lymphomas were rescued in vivo by ectopic expression of CD74. Deconvolution of bulk RNAseq data from primary human DLBCL recapitulated part of the immune remodeling detected in mice and pointed to depletion of dendritic cells as another feature of IRF8 mutant TME. We concluded that IRF8 mutations contribute to DLBCL biology by facilitating immune escape.

Increased retinoic acid signaling decreases lung metastasis in salivary adenoid cystic carcinoma by inhibiting the noncanonical Notch1 pathway

MYB-NFIB fusion and NOTCH1 mutation are common hallmark genetic events in salivary gland adenoid cystic carcinoma (SACC). However, abnormal expression of MYB and NOTCH1 is also observed in patients without MYB-NFIB fusion and NOTCH1 mutation. Here, we explore in-depth the molecular mechanisms of lung metastasis through single-cell RNA sequencing (scRNA-seq) and exome target capture sequencing in two SACC patients without MYB-NFIB fusion and NOTCH1 mutation. Twenty-five types of cells in primary and metastatic tissues were identified via Seurat clustering and categorized into four main stages ranging from near-normal to cancer-based on the abundance of each cell cluster in normal tissue. In this context, we identified the Notch signaling pathway enrichment in almost all cancer cells; RNA velocity, trajectory, and sub-clustering analyses were performed to deeply investigate cancer progenitor-like cell clusters in primary tumor-associated lung metastases, and signature genes of progenitor-like cells were enriched in the "MYC_TARGETS_V2" gene set. In vitro, we detected the NICD1-MYB-MYC complex by co-immunoprecipitation (Co-IP) and incidentally identified retinoic acid (RA) as an endogenous antagonist of genes in the "MYC_TARGETS_V2" gene set. Following this, we confirmed that all-trans retinoic acid (ATRA) suppresses the lung metastasis of SACC by correcting erroneous cell differentiation mainly caused by aberrant NOTCH1 or MYB expression. Bioinformatic, RNA-seq, and immunohistochemical (IHC) analyses of primary tissues and metastatic lung tissues from patients with SACC suggested that RA system insufficiency partially promotes lung metastasis. These findings imply the value of the RA system in diagnosis and treatment.

Notch Partners in the Long Journey of T-ALL Pathogenesis

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological disease that arises from the oncogenic transformation of developing T cells during T-lymphopoiesis. Although T-ALL prognosis has improved markedly in recent years, relapsing and refractory patients with dismal outcomes still represent a major clinical issue. Consequently, understanding the pathological mechanisms that lead to the appearance of this malignancy and developing novel and more effective targeted therapies is an urgent need. Since the discovery in 2004 that a major proportion of T-ALL patients carry activating mutations that turn NOTCH1 into an oncogene, great efforts have been made to decipher the mechanisms underlying constitutive NOTCH1 activation, with the aim of understanding how NOTCH1 dysregulation converts the physiological NOTCH1-dependent T-cell developmental program into a pathological T-cell transformation process. Several molecular players have so far been shown to cooperate with NOTCH1 in this oncogenic process, and different therapeutic strategies have been developed to specifically target NOTCH1-dependent T-ALLs. Here, we comprehensively analyze the molecular bases of the cross-talk between NOTCH1 and cooperating partners critically involved in the generation and/or maintenance and progression of T-ALL and discuss novel opportunities and therapeutic approaches that current knowledge may open for future treatment of T-ALL patients.

The Promising Role of Non-Coding RNAs as Biomarkers and Therapeutic Targets for Leukemia

Early-stage leukemia identification is crucial for effective disease management and leads to an improvement in the survival of leukemia patients. Approaches based on cutting-edge biomarkers with excellent accuracy in body liquids provide patients with the possibility of early diagnosis with high sensitivity and specificity. Non-coding RNAs have recently received a great deal of interest as possible biomarkers in leukemia due to their participation in crucial oncogenic processes such as proliferation, differentiation, invasion, apoptosis, and their availability in body fluids. Recent studies have revealed a strong correlation between leukemia and the deregulated non-coding RNAs. On this basis, these RNAs are also great therapeutic targets. Based on these advantages, we tried to review the role of non-coding RNAs in leukemia. Here, the significance of several non-coding RNA types in leukemia is highlighted, and their potential roles as diagnostic, prognostic, and therapeutic targets are covered.

Guidelines on Designing MicroRNA Sponges: From Construction to Stable Cell Line

Single microRNA (miRNA) can be inhibited using antagomiR which efficiently knocks down a specific miRNA. However, the effect is transient and often results in subtle phenotype. Here we report a guideline on designing miRNA sponges inhibiting a miRNA family. As a model system, we targeted miR-30 family, known as tumor suppressor miRNAs in multiple tumors. To achieve an efficient knockdown, we generated perfect and bulged-matched miRNA binding sites (MBS) and introduced multiple copies of MBS. The protocol here demonstrates the miRNA sponge as a useful tool to examine the functional impact of inhibition miRNAs.

MicroRNAs and the Diagnosis of Childhood Acute Lymphoblastic Leukemia: Systematic Review, Meta-Analysis and Re-Analysis with Novel Small RNA-Seq Tools

Simple Summary

MicroRNAs (miRNAs) have been under the spotlight for the last three decades. These non-coding RNAs seem to be dynamic regulators of mRNA stability and translation, in addition to interfering with transcription. Circulating miRNAs play a critical role in cell-to-cell interplay; therefore, they can serve as disease biomarkers. Meta-analysis of published data revealed that the CC genotype of rs4938723 in pri-miR-34b/c and the TT genotype of rs543412 in miR-100 confer protection against acute lymphoblastic leukemia (ALL) in children. Reanalysis of small RNA-seq data with novel tools identified significantly overexpressed members of the miR-128, miR-181, miR-130 and miR-17 families and significantly lower expression of miR-30, miR-24-2 and miR143~145 clusters, miR-574 and miR-618 in pediatric T-ALL cases compared with controls. Inconsistencies in methodology and study designs in most published material preclude reproducibility, and further cohort studies need to be conducted in order to empower novel tools, such as ALLSorts and RNAseqCNV.

Abstract

MicroRNAs (miRNAs) have been implicated in childhood acute lymphoblastic leukemia (ALL) pathogenesis. We performed a systematic review and meta-analysis of miRNA single-nucleotide polymorphisms (SNPs) in childhood ALL compared with healthy children, which revealed (i) that the CC genotype of rs4938723 in pri-miR-34b/c and the TT genotype of rs543412 in miR-100 confer protection against ALL occurrence in children; (ii) no significant association between rs2910164 genotypes in miR-146a and childhood ALL; and (iii) SNPs in DROSHA, miR-449b, miR-938, miR-3117 and miR-3689d-2 genes seem to be associated with susceptibility to B-ALL in childhood. A review of published literature on differential expression of miRNAs in children with ALL compared with controls revealed a significant upregulation of the miR-128 family, miR-130b, miR-155, miR-181 family, miR-210, miR-222, miR-363 and miR-708, along with significant downregulation of miR-143 and miR-148a, seem to have a definite role in childhood ALL development. MicroRNA signatures among childhood ALL subtypes, along with differential miRNA expression patterns between B-ALL and T-ALL cases, were scrutinized. With respect to T-ALL pediatric cases, we reanalyzed RNA-seq datasets with a robust and sensitive pipeline and confirmed the significant differential expression of hsa-miR-16-5p, hsa-miR-19b-3p, hsa-miR-92a-2-5p, hsa-miR-128-3p (ranked first), hsa-miR-130b-3p and -5p, hsa-miR-181a-5p, -2-3p and -3p, hsa-miR-181b-5p and -3p, hsa-miR-145-5p and hsa-miR-574-3p, as described in the literature, along with novel identified miRNAs.

Molecular Characterization of the Response to Conventional Chemotherapeutics in Pro-B-ALL Cell Lines in Terms of Tumor Relapse

Little is known about optimally applying chemotherapeutic agents in a specific temporal sequence to rapidly reduce the tumor load and to improve therapeutic efficacy. The clinical optimization of drug efficacy while reducing side effects is still restricted due to an incomplete understanding of the mode of action and related tumor relapse mechanisms on the molecular level. The molecular characterization of transcriptomic drug signatures can help to identify the affected pathways, downstream regulated genes and regulatory interactions related to tumor relapse in response to drug application. We tried to outline the dynamic regulatory reprogramming leading to tumor relapse in relapsed MLL-rearranged pro-B-cell acute lymphoblastic leukemia (B-ALL) cells in response to two first-line treatments: dexamethasone (Dexa) and cytarabine (AraC). We performed an integrative molecular analysis of whole transcriptome profiles of each treatment, specifically considering public knowledge of miRNA regulation via a network-based approach to unravel key driver genes and miRNAs that may control the relapse mechanisms accompanying each treatment. Our results gave hints to the crucial regulatory roles of genes leading to Dexa-resistance and related miRNAs linked to chemosensitivity. These genes and miRNAs should be further investigated in preclinical models to obtain more hints about relapse processes.

Systems Drug Discovery for Diffuse Large B Cell Lymphoma Based on Pathogenic Molecular Mechanism via Big Data Mining and Deep Learning Method

Diffuse large B cell lymphoma (DLBCL) is an aggressive heterogeneous disease. The most common subtypes of DLBCL include germinal center b-cell (GCB) type and activated b-cell (ABC) type. To learn more about the pathogenesis of two DLBCL subtypes (i.e., DLBCL ABC and DLBCL GCB), we firstly construct a candidate genome-wide genetic and epigenetic network (GWGEN) by big database mining. With the help of two DLBCL subtypes’ genome-wide microarray data, we identify their real GWGENs via system identification and model order selection approaches. Afterword, the core GWGENs of two DLBCL subtypes could be extracted from real GWGENs by principal network projection (PNP) method. By comparing core signaling pathways and investigating pathogenic mechanisms, we are able to identify pathogenic biomarkers as drug targets for DLBCL ABC and DLBCL GCD, respectively. Furthermore, we do drug discovery considering drug-target interaction ability, drug regulation ability, and drug toxicity. Among them, a deep neural network (DNN)-based drug-target interaction (DTI) model is trained in advance to predict potential drug candidates holding higher probability to interact with identified biomarkers. Consequently, two drug combinations are proposed to alleviate DLBCL ABC and DLBCL GCB, respectively.

MYC, mitochondrial metabolism and O-GlcNAcylation converge to modulate the activity and subcellular localization of DNA and RNA demethylases

Mitochondria can function as signaling organelles, and part of this output leads to epigenetic remodeling. The full extent of this far-reaching interplay remains undefined. Here, we show that MYC transcriptionally activates IDH2 and increases alpha-ketoglutarate (αKG) levels. This regulatory step induces the activity of αKG-dependent DNA hydroxylases and RNA demethylases, thus reducing global DNA and RNA methylation. MYC, in a IDH2-dependent manner, also promotes the nuclear accumulation of TET1-TET2-TET3, FTO and ALKBH5. Notably, this subcellular movement correlated with the ability of MYC, in an IDH2-dependent manner, and, unexpectedly, of αKG to directly induce O-GlcNAcylation. Concordantly, modulation of the activity of OGT and OGA, enzymes that control the cycling of this non-canonical mono-glycosylation, largely recapitulated the effects of the MYC-IDH2-αKG axis on the subcellular movement of DNA and RNA demethylases. Together, we uncovered a hitherto unsuspected crosstalk between MYC, αKG and O-GlcNAcylation which could influence the epigenome and epitranscriptome homeostasis.

The role of miRNAs as a big master regulator of signaling pathways involved in lymphoblastic leukemia

MicroRNAs (miRNAs) belong to small noncoding RNAs, which have long attracted researchers' attention because of their potency in acting either as oncogenes or tumor-suppressors in cancers. acute lymphocytic leukemia (ALL) and chronic lymphocytic leukemia (CLL) are two known types of leukemia with high mortality rates in adults and children. On a molecular basis, various signaling pathways are active in both types, making researchers consider the potential role of miRNAs in activating or suppressing these pathways to further hinder cancer development. In this review, we summarized the potential miRNAs, especially circulating ones, involved in essential signaling pathways in the ALL and CLL patients which serve as biomarkers and valuable targets in the treatment fields.

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.

Targeting Notch to Maximize Chemotherapeutic Benefits: Rationale, Advanced Strategies, and Future Perspectives

Simple Summary

The Notch signaling pathway regulates cell proliferation, apoptosis, stem cell self-renewal, and differentiation in a context-dependent fashion both during embryonic development and in adult tissue homeostasis. Consistent with its pleiotropic physiological role, unproper activation of the signaling promotes or counteracts tumor pathogenesis and therapy response in distinct tissues. In the last twenty years, a wide number of studies have highlighted the anti-cancer potential of Notch-modulating agents as single treatment and in combination with the existent therapies. However, most of these strategies have failed in the clinical exploration due to dose-limiting toxicity and low efficacy, encouraging the development of novel agents and the design of more appropriate combinations between Notch signaling inhibitors and chemotherapeutic drugs with improved safety and effectiveness for distinct types of cancer.

Abstract

Notch signaling guides cell fate decisions by affecting proliferation, apoptosis, stem cell self-renewal, and differentiation depending on cell and tissue context. Given its multifaceted function during tissue development, both overactivation and loss of Notch signaling have been linked to tumorigenesis in ways that are either oncogenic or oncosuppressive, but always context-dependent. Notch signaling is critical for several mechanisms of chemoresistance including cancer stem cell maintenance, epithelial-mesenchymal transition, tumor-stroma interaction, and malignant neovascularization that makes its targeting an appealing strategy against tumor growth and recurrence. During the last decades, numerous Notch-interfering agents have been developed, and the abundant preclinical evidence has been transformed in orphan drug approval for few rare diseases. However, the majority of Notch-dependent malignancies remain untargeted, even if the application of Notch inhibitors alone or in combination with common chemotherapeutic drugs is being evaluated in clinical trials. The modest clinical success of current Notch-targeting strategies is mostly due to their limited efficacy and severe on-target toxicity in Notch-controlled healthy tissues. Here, we review the available preclinical and clinical evidence on combinatorial treatment between different Notch signaling inhibitors and existent chemotherapeutic drugs, providing a comprehensive picture of molecular mechanisms explaining the potential or lacking success of these combinations.

MYC in T-cell acute lymphoblastic leukemia: functional implications and targeted strategies

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological cancer that frequently occurs in children and adolescents, which results from the transformation of immature T-cell progenitors. Aberrant cell growth and proliferation of T-ALL lymphoblasts are sustained by activation of strong oncogenic drivers. Mounting evidence highlights the critical role of the NOTCH1-MYC highway toward the initiation and progression of T-ALL. MYC has been emphasized as a primary NOTCH1 transcriptional target impinging in leukemia-initiating cell activity particularly responsible for disease onset and relapse. These findings lay a foundation of T-ALL as an ideal disease model for studying MYC-mediated cancer. The biology of MYC deregulation in T-ALL supports innovative strategies for therapeutic targeting of MYC. To summarize the relevant literature and data in recent years, we here provide a comprehensive overview of the functional importance of MYC in T-ALL development, and the molecular mechanisms underlying MYC deregulation in T-ALL. Finally, we illustrate the innovative MYC-targeted approaches that have been evaluated in pre-clinical models and shown significant efficacy. Given the complexity of T-ALL molecular pathogenesis, we propose that a combination of anti-MYC strategies with conventional chemotherapies or other targeted/immunotherapies may provide the most durable response, especially for those patients with relapsed and refractory T-ALL.

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

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

Regulators at Every Step-How microRNAs Drive Tumor Cell Invasiveness and Metastasis

Tumor cell invasiveness and metastasis are the main causes of mortality in cancer. Tumor progression is composed of many steps, including primary tumor growth, local invasion, intravasation, survival in the circulation, pre-metastatic niche formation, and metastasis. All these steps are strictly controlled by microRNAs (miRNAs), small non-coding RNA that regulate gene expression at the post-transcriptional level. miRNAs can act as oncomiRs that promote tumor cell invasion and metastasis or as tumor suppressor miRNAs that inhibit tumor progression. These miRNAs regulate the actin cytoskeleton, the expression of extracellular matrix (ECM) receptors including integrins and ECM-remodeling enzymes comprising matrix metalloproteinases (MMPs), and regulate epithelial-mesenchymal transition (EMT), hence modulating cell migration and invasiveness. Moreover, miRNAs regulate angiogenesis, the formation of a pre-metastatic niche, and metastasis. Thus, miRNAs are biomarkers of metastases as well as promising targets of therapy. In this review, we comprehensively describe the role of various miRNAs in tumor cell migration, invasion, and metastasis.

Regulation of PD-L1 expression is a novel facet of cyclic-AMP-mediated immunosuppression

Cyclic-AMP (cAMP) exerts suppressive effects in the innate and adaptive immune system. The PD-1/PD-L1 immune checkpoint down-regulates T-cell activity. Here, we examined if these two immunosuppressive nodes intersect. Using normal and malignant lymphocytes from humans, and the phosphodiesterase 4b (Pde4b) knockout mouse, we found that cAMP induces PD-L1 transcription and protein expression. Mechanistically, we discovered that the cAMP effectors PKA and CREB induce the transcription/secretion of IL-10, IL-8 and IL-6, which initiate an autocrine loop that activates the JAK/STAT pathway and ultimately increase PD-L1 expression in the cell surface. This signaling axis is disarmed at two specific nodes in subsets of diffuse large B cell lymphoma, which may help explain the variable PD-L1 expression in these tumors. In vivo, we found that despite its immunosuppressive attributes, the PDE4 inhibitor roflumilast did not decrease the clinical activity of checkpoint inhibitors, an important clinical observation given the approved use of these agents in multiple diseases. In summary, we discovered that PD-L1 induction is a part of the repertoire of immunosuppressive actions mediated by cAMP, defined a cytokine-mediated autocrine loop that executes this action and, reassuringly, showed that PDE4 inhibition does not antagonize immune checkpoint blockade in an in vivo syngeneic lymphoma model.

PRL3 enhances T-cell acute lymphoblastic leukemia growth through suppressing T-cell signaling pathways and apoptosis

T cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy of thymocytes and is largely driven by the NOTCH/MYC pathway. Yet, additional oncogenic drivers are required for transformation. Here, we identify protein tyrosine phosphatase type 4 A3 (PRL3) as a collaborating oncogenic driver in T-ALL. PRL3 is expressed in a large fraction of primary human T-ALLs and is commonly co-amplified with MYC. PRL3 also synergized with MYC to initiate early-onset ALL in transgenic zebrafish and was required for human T-ALL growth and maintenance. Mass spectrometry phosphoproteomic analysis and mechanistic studies uncovered that PRL3 suppresses downstream T cell phosphorylation signaling pathways, including those modulated by VAV1, and subsequently suppresses apoptosis in leukemia cells. Taken together, our studies have identified new roles for PRL3 as a collaborating oncogenic driver in human T-ALL and suggest that therapeutic targeting of the PRL3 phosphatase will likely be a useful treatment strategy for T-ALL.

Targeting miR-27a/VE-cadherin interactions rescues cerebral cavernous malformations in mice

Cerebral cavernous malformations (CCMs) are vascular lesions predominantly developing in the central nervous system (CNS), with no effective treatments other than surgery. Loss-of-function mutation in CCM1/krev interaction trapped 1 (KRIT1), CCM2, or CCM3/programmed cell death 10 (PDCD10) causes lesions that are characterized by abnormal vascular integrity. Vascular endothelial cadherin (VE-cadherin), a major regulator of endothelial cell (EC) junctional integrity is strongly disorganized in ECs lining the CCM lesions. We report here that microRNA-27a (miR-27a), a negative regulator of VE-cadherin, is elevated in ECs isolated from mouse brains developing early CCM lesions and in cultured ECs with CCM1 or CCM2 depletion. Furthermore, we show miR-27a acts downstream of kruppel-like factor (KLF)2 and KLF4, two known key transcription factors involved in CCM lesion development. Using CD5-2 (a target site blocker [TSB]) to prevent the miR-27a/VE-cadherin mRNA interaction, we present a potential therapy to increase VE-cadherin expression and thus rescue the abnormal vascular integrity. In CCM1- or CCM2-depleted ECs, CD5-2 reduces monolayer permeability, and in Ccm1 heterozygous mice, it restores dermal vessel barrier function. In a neonatal mouse model of CCM disease, CD5-2 normalizes vasculature and reduces vascular leakage in the lesions, inhibits the development of large lesions, and significantly reduces the size of established lesions in the hindbrain. Furthermore, CD5-2 limits the accumulation of inflammatory cells in the lesion area. Our work has established that VE-cadherin is a potential therapeutic target for normalization of the vasculature and highlights that targeting miR-27a/VE-cadherin interaction by CD5-2 is a potential novel therapy for the devastating disease, CCM.

Cerebral cavernous malformation (CCM) is a disease for which, hitherto, surgery has been the only option. This study shows that a potential therapeutic, CD5-2, inhibits lesion development and vascular leak in the brains of CCM neonatal mice by targeting the endothelial cell–specific adhesion molecule VE-cadherin and restoring the vascular integrity of CCM lesions.

Enhancers and MYC interplay in hematopoiesis

Transcription requires the fine interplay between enhancers and transcription factors. Enhancers are able to activate transcription of genes involved in normal cell biology, whereas aberrant enhancer activity leads to oncogenesis. MYC is a well-established proto-oncogene involved in half of human cancers amplifying the output of its targets. The crosstalk between MYC and enhancers is known for many years since the discovery of IgH enhancer juxtaposition with MYC in high-grade lymphomas. Here, we focus mainly in the enhancers surrounding MYC in the 8q24 locus. That region comprises several enhancers that associate with other transcription factors, transmembrane receptors, and fusion genes composing complex regulatory networks aberrantly expressed in almost all types of hematological malignancies. Understanding the nature of these interactions in normal blood cells and in leukemias/lymphomas will expand MYC targeting options in the armamentarium against hematological cancers.

MYC Regulation of D2HGDH and L2HGDH Influences the Epigenome and Epitranscriptome

Mitochondrial D2HGDH and L2HGDH catalyze the oxidation of D-2-HG and L-2-HG, respectively, into αKG. This contributes to cellular homeostasis in part by modulating the activity of αKG-dependent dioxygenases. Signals that control the expression/activity of D2HGDH/L2HGDH are presumed to broadly influence physiology and pathology. Using cell and mouse models, we discovered that MYC directly induces D2HGDH and L2HGDH transcription. Furthermore, in a manner suggestive of D2HGDH, L2HGDH, and αKG dependency, MYC activates TET enzymes and RNA demethylases, and promotes their nuclear localization. Consistent with these observations, in primary B cell lymphomas MYC expression positively correlated with enhancer hypomethylation and overexpression of lymphomagenic genes. Together, these data provide additional evidence for the role of mitochondria metabolism in influencing the epigenome and epitranscriptome, and imply that in specific contexts wild-type TET enzymes could demethylate and activate oncogenic enhancers.

The Role of MicroRNAs upon Epithelial-to-Mesenchymal Transition in Inflammatory Bowel Disease

Increasing evidence suggest the significance of inflammation in the progression of cancer, for example the development of colorectal cancer in Inflammatory Bowel Disease (IBD) patients. Long-lasting inflammation in the gastrointestinal tract causes serious systemic complications and breaks the homeostasis of the intestine, where the altered expression of regulatory genes and miRNAs trigger malignant transformations. Several steps lead from acute inflammation to malignancies: epithelial-to-mesenchymal transition (EMT) and inhibitory microRNAs (miRNAs) are known factors during multistage carcinogenesis and IBD pathogenesis. In this review, we outline the interactions between EMT components and miRNAs that may affect cancer development during IBD.

MicroRNA-16 is involved in the pathogenesis of pre-eclampsia via regulation of Notch2

In recent years, the role of microRNAs (miRNAs) in pre-eclampsia (PE) has been demonstrated, while the relevant mechanisms of miR-16 in PE await to be unearthed. Thus, the aim of this study is to explore whether miR-16 exerts its function in PE, and we assumed that miR-16 may be implicated in the occurrence of PE by adjusting the biological functions of trophoblast cells via modulating Notch2. Placental tissues of pregnant women with normal pregnancy and PE were collected to detect the expression of miR-16, Notch2, and Notch3. The effects of miR-16 and Notch2 on the biological functions of BeWo and JEG-3 cells were further determined. Expression of miR-16 and Notch2 in trophoblast cells was detected by reverse transcription quantitative polymerase chain reaction and western blot assay. Downregulated Notch2 and upregulated miR-16 and Notch3 were found in placental tissues of PE. There was a negative correlation between Notch2 and miR-16 expression (r = -0.769), and a positive correlation between Notch3 and miR-16 expression (r = 0.676; p < .05). Overexpression of miR-16 inhibited proliferation, migration, and invasion, and facilitated the apoptosis of BeWo and JEG-3 cells, but overexpression of Notch2 reversed this trend. Overexpression of miR-16 inhibited Notch2 expression in BeWo and JEG-3 cells, and Notch2 was the target gene of miR-16. Our study highlights that overexpression of miR-16 is involved in PE by regulating the biological functions of trophoblast cells via inhibition of Notch2. This paper provides a new idea for further study of the pathogenesis of PE.

MicroRNAs and their involvement in T-ALL: A brief overview

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy in which the transformed clone is arrested during T-cell development. Several genetic and epigenetic events have been implicated in this transformation. MicroRNAs (miRNAs) are small, non-coding RNAs that primarily function as endogenous translational repressors of protein-coding genes. The involvement of miRNAs in the regulation of cancer progression is well-established, namely by down-regulating the expression of key oncogenes or tumor suppressors and thereby preventing or promoting tumorigenesis, respectively. Similar to other cancers, several miRNA genes have been identified and implicated in the context of T-ALL. In this review we focused on the most studied microRNAs associated with T-ALL pathogenesis.

The role of oncogenic Notch2 signaling in cancer: a novel therapeutic target

Deregulated Notch signaling is a key factor thought to facilitate the stem-like proliferation of cancer cells, thereby facilitating disease progression. Four subtypes of Notch receptor have been described to date, with each playing a distinct role in cancer development and progression, therefore warranting a careful and comprehensive examination of the targeting of each receptor subtype in the context of oncogenesis. Clinical efforts to translate the DAPT, which blocks Notch signaling, have been unsuccessful due to a combination of serious gastrointestinal side effects and a lack of complete blocking efficacy. There is therefore a clear need to identify better therapeutic strategies for targeting and manipulating Notch signaling. Notch2 is a Notch receptor that is commonly overexpressed in a range of cancers, and which is linked to a unique oncogenic mechanism. Successful efforts to block Notch2 signaling will depend upon doing so both efficiently and specifically in patients. As such, in the present review we will explore the role of Notch2 signaling in the development and progression of cancer, and we will assess agents and strategies with the potential to effectively disrupt Notch2 signaling and thereby yield novel cancer treatment regimens.

Comprehensive Investigation of miRNome Identifies Novel Candidate miRNA-mRNA Interactions Implicated in T-Cell Acute Lymphoblastic Leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy originating from T-cell precursors. The genetic landscape of T-ALL has been largely characterized by next-generation sequencing. Yet, the transcriptome of miRNAs (miRNome) of T-ALL has been less extensively studied. Using small RNA sequencing, we characterized the miRNome of 34 pediatric T-ALL samples, including the expression of isomiRs and the identification of candidate novel miRNAs (not previously annotated in miRBase). For the first time, we show that immunophenotypic subtypes of T-ALL present different miRNA expression profiles. To extend miRNome characteristics in T-ALL (to 82 T-ALL cases), we combined our small RNA-seq results with data available in Gene Expression Omnibus. We report on miRNAs most abundantly expressed in pediatric T-ALL and miRNAs differentially expressed in T-ALL versus normal mature T-lymphocytes and thymocytes, representing candidate oncogenic and tumor suppressor miRNAs. Using eight target prediction algorithms and pathway enrichment analysis, we identified differentially expressed miRNAs and their predicted targets implicated in processes (defined in Gene Ontology and Kyoto Encyclopedia of Genes and Genomes) of potential importance in pathogenesis of T-ALL, including interleukin-6-mediated signaling, mTOR signaling, and regulation of apoptosis. We finally focused on hsa-mir-106a-363 cluster and functionally validated direct interactions of hsa-miR-20b-5p and hsa-miR-363-3p with 3' untranslated regions of their predicted targets (PTEN, SOS1, LATS2), overrepresented in regulation of apoptosis. hsa-mir-106a-363 is a paralogue of prototypic oncogenic hsa-mir-17-92 cluster with yet unestablished role in the pathogenesis of T-ALL. Our study provides a firm basis and data resource for functional analyses on the role of miRNA-mRNA interactions in T-ALL.

A Two-Cohort RNA-seq Study Reveals Changes in Endometrial and Blood miRNome in Fertile and Infertile Women

The endometrium undergoes extensive changes to prepare for embryo implantation and microRNAs (miRNAs) have been described as playing a significant role in the regulation of endometrial receptivity. However, there is no consensus about the miRNAs involved in mid-secretory endometrial functions. We analysed the complete endometrial miRNome from early secretory (pre-receptive) and mid-secretory (receptive) phases from fertile women and from patients with recurrent implantation failure (RIF) to reveal differentially expressed (DE) miRNAs in the mid-secretory endometrium. Furthermore, we investigated whether the overall changes during early to mid-secretory phase transition and with RIF condition could be reflected in blood miRNA profiles. In total, 116 endometrial and 114 matched blood samples collected from two different population cohorts were subjected to small RNA sequencing. Among fertile women, 91 DE miRNAs were identified in the mid-secretory vs. early secretory endometrium, while no differences were found in the corresponding blood samples. The comparison of mid-secretory phase samples between fertile and infertile women revealed 21 DE miRNAs from the endometrium and one from blood samples. Among discovered novel miRNAs, chr2_4401 was validated and showed up-regulation in the mid-secretory endometrium. Besides novel findings, we confirmed the involvement of miR-30 and miR-200 family members in mid-secretory endometrial functions.

Identification of Endogenous Control miRNAs for RT-qPCR in T-Cell Acute Lymphoblastic Leukemia

Optimal endogenous controls enable reliable normalization of microRNA (miRNA) expression in reverse-transcription quantitative PCR (RT-qPCR). This is particularly important when miRNAs are considered as candidate diagnostic or prognostic biomarkers. Universal endogenous controls are lacking, thus candidate normalizers must be evaluated individually for each experiment. Here we present a strategy that we applied to the identification of optimal control miRNAs for RT-qPCR profiling of miRNA expression in T-cell acute lymphoblastic leukemia (T-ALL) and in normal cells of T-lineage. First, using NormFinder for an iterative analysis of miRNA stability in our miRNA-seq data, we established the number of control miRNAs to be used in RT-qPCR. Then, we identified optimal control miRNAs by a comprehensive analysis of miRNA stability in miRNA-seq data and in RT-qPCR by analysis of RT-qPCR amplification efficiency and expression across a variety of T-lineage samples and T-ALL cell line culture conditions. We then showed the utility of the combination of three miRNAs as endogenous normalizers (hsa-miR-16-5p, hsa-miR-25-3p, and hsa-let-7a-5p). These miRNAs might serve as first-line candidate endogenous controls for RT-qPCR analysis of miRNAs in different types of T-lineage samples: T-ALL patient samples, T-ALL cell lines, normal immature thymocytes, and mature T-lymphocytes. The strategy we present is universal and can be transferred to other RT-qPCR experiments.

Effect of Notch and PARP Pathways' Inhibition in Leukemic Cells

Differentiation of blood cells is one of the most complex processes in the body. It is regulated by the action of transcription factors in time and space which creates a specific signaling network. In the hematopoietic signaling system, Notch is one of the main regulators of lymphocyte development. The aim of this study was to get insight into the regulation of Notch signalization and the influence of poly(ADP-ribose)polymerase (PARP) activity on this process in three leukemia cell lines obtained from B and T cells. PARP1 is an enzyme involved in posttranslational protein modification and chromatin structure changes. B and T leukemia cells were treated with Notch and PARP inhibitors, alone or in combination, for a prolonged period. The cells did not show cell proliferation arrest or apoptosis. Analysis of gene and protein expression set involved in Notch and PARP pathways revealed increase in JAGGED1 expression after PARP1 inhibition in B cell lines and changes in Ikaros family members in both B and T cell lines after γ-secretase inhibition. These data indicate that Notch and PARP inhibition, although not inducing differentiation in leukemia cells, induce changes in signaling circuits and chromatin modelling factors.

Downregulated miR-17, miR-29c, miR-92a and miR-214 may be related to BCL11B overexpression in T cell acute lymphoblastic leukemia

AIM

BCL11B overexpression is a characteristic of most T cell acute lymphoblastic leukemia (T-ALL) cases, and downregulated BCL11B in leukemic T cells inhibits cell proliferation and induces apoptosis. The purpose of this study was to analyze the miRNA expression pattern that may be related to BCL11B regulation in T-ALL.

METHODS

Quantitative real-time PCR was used to detect the miRNAs miR-17-3p, miR-17-5p, miR-29c-3p, miR-92a-3p, miR-214-3p and miR-214-5p, the BCL11B expression level in peripheral blood mononuclear cells which was obtained from 17 de novo and untreated T-ALL patients, and 15 healthy individuals (HIs) served as control. Correlations between the relative miRNA expression levels and BCL11B were analyzed.

RESULTS

Based on the computational prediction that certain miRNAs bind the BCL11B 3'-UTR, miR-17-3p, miR-17-5p, miR-29c-3p, miR-92a-3p, miR-214-3p and miR-214-5p were found to be candidates for regulating BCL11B. The expression levels of the six miRNAs were decreased compared with HIs, and with the exception of miR-17-5p, statistically significant differences in expression levels were found in the T-ALL group. Moreover, while significantly higher BCL11B expression was found in the T-ALL group, a negative trend in the correlation level for all six miRNAs could be found in all groups; however, statistical significance was only found for miR-214-3p in the T-ALL group.

CONCLUSION

miRNA downregulation together with BCL11B upregulation suggests that miR-17, miR-29c, miR-92a and miR-214 might be involved in BCL11B regulation. The therapeutic promise of regulating the expression of these miRNAs for T-ALL therapy may be considered in the future.

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

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

T-cell acute lymphoblastic leukemia from miRNA perspective: Basic concepts, experimental approaches, and potential biomarkers

T-cell acute lymphoblastic leukemia (T-ALL) is a rare, aggressive and heterogeneous malignancy originating from T-cell precursors. The mechanisms of T-ALL pathogenesis related to non-protein coding part of the genome are currently intensively studied. miRNAs are short, non-coding molecules acting as negative regulators of gene expression which shape phenotype of cells in a complex and context-specific manner. miRNAs may act as oncogenes or tumor suppressors; several miRNAs have been related to drug resistance and treatment response in various malignancies. Here we present the review of the state-of-the-art knowledge on the role of miRNAs in T-ALL pathogenesis, with detailed overview of the studies reporting on miRNAs with oncogenic and tumor suppressor potential. We discuss whether miRNAs might be considered candidate biomarkers of prognosis in T-ALL and leukemia subtype-specific markers. We also describe experimental approaches and a typical workflow applied in research on the involvement of miRNAs in oncogenesis.

Notch signaling as a therapeutic target for acute lymphoblastic leukemia

INTRODUCTION

Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. Although the therapy of ALL has significantly improved, the heterogeneous genetic landscape of the disease often causes relapse, which is difficult to treat. Achieving a positive outcome for patients with relapsed or refractory ALL remains a challenging issue. The high prevalence of NOTCH-activating mutations in T-cell acute lymphoblastic leukemia (T-ALL) and the central role of NOTCH signaling in regulating cell survival and growth of ALL provide a rationale for the development of Notch signaling-targeted strategies in this disease. Therapeutic alternatives with effective anti-leukemic potential and low toxicity are needed. Areas covered: This review provides an overview of the currently available drugs directly or indirectly targeting Notch signaling in ALL. Besides considering the known Notch targeting approaches, such as γ-secretase inhibitors (GSIs) and Notch inhibiting antibodies (mAbs), currently in clinical trials, we focus on the recent insights into the molecular mechanisms underlying the Notch signaling regulation in ALL. Expert opinion: Novel drugs targeting specific steps of Notch signaling or intersecting pathways could improve the efficiency of the conventional hematological cancers therapies. Further studies are required to translate the new findings into future clinical applications.

Guidelines on Designing MicroRNA Sponges: From Construction to Stable Cell Line

Single microRNA (miRNA) can be inhibited using antagomiR which efficiently knockdown a specific miRNA. However, the effect is transient and often results in subtle phenotype. Here we report a guideline on designing miRNA sponge inhibiting a miRNA family. As a model system, we targeted miR-30 family, known as tumor suppressor miRNAs in multiple tumors. To achieve an efficient knockdown, we generated perfect and bulged-matched miRNA binding sites (MBS) and introduced multiple copies of MBS. The protocol here demonstrates the miRNA sponge as a useful tool to examine the functional impact of inhibition miRNAs.

MicroRNA expression and activity in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is a lymphoid malignancy caused by the oncogenic transformation of immature T-cell progenitors. Many biologically relevant genetic and epigenetic alterations have been identified as driving factors for this transformation. Recently, microRNAs (miRNAs) have been shown to influence various leukemias, including T-ALL. Aberrant expression of miRNAs can function as either oncogenes or tumor suppressors in T-ALL through the regulation of cell migration, invasion, proliferation, apoptosis, and chemoresistance. This occurs by targeting key signaling pathways or transcriptional factors that play a critical role in T-ALL pathology and progression. Different miRNA expression profiles have been linked to specific genetic subtypes of human T-ALL. Furthermore, miRNAs can also act as independent prognostic factors to predict clinical outcomes for T-ALL patients. In the current review, we will focus on the role of miRNAs in the development and progression of T-ALL.

CBX4 exhibits oncogenic activities in breast cancer via Notch1 signaling

Polycomb chromobox (CBX) proteins are involved in gene silencing to function as oncogenes or tumor suppressors through the polycomb repressive complex (PRC1). CBX4 has been implicated in the progression of human cancers, but its role and clinical significance in breast cancer remain unclear. Here, we show that CBX4 is up-regulated in breast cancer and exerts oncogenic activities via miR-137-mediated activation of Notch1 signaling pathway. CBX4 expression was increased in breast cancer, compared with the nontumorous tissues. High CBX4 expression was closely correlated with tumor metastasis, advanced clinical stage and poor overall survival in a cohort of 179 patients with breast cancer. In vitro studies demonstrated that CBX4 overexpression enhanced, whereas CBX4 knockdown inhibited cell growth and migration. Mechanistically, in a PRC1-dependent manner, CBX4 inhibited the promoter activity of miR-137 and suppressed its expression. miR-137 decreased the expression of Notch1, Jag1 and Hey2 via targeting their 3'-UTRs. The suppression of Notch1 by siRNA or overexpression of miR-137 markedly attenuated CBX4-promoted phenotypes. Collectively, these findings indicate that CBX4 promotes breast cancer via miR-137-mediated Notch1 signaling. Our data, therefore, suggest that CBX4 serve as a prognostic biomarker and that targeting CBX4/miR-137 axis may provide therapeutic potent in the treatment of breast cancer.

MiR-30a increases MDSC differentiation and immunosuppressive function by targeting SOCS3 in mice with B-cell lymphoma

Myeloid-derived suppressor cells (MDSCs), including granulocytic (G)-MDSCs and monocytic (M)-MDSCs, play a critical role in tumor-induced T cell tolerance. MDSC immunosuppressive function and differentiation are significantly promoted in patients and B-cell lymphoma model mice. However, the mechanisms regulating these processes remain largely unclear. In the present study, we observed increased microRNA (miR)-30a expression both in G-MDSCs and in M-MDSCs from B cell lymphoma model mice. After transfection with miR-30a mimics, the differentiation and suppressive capacities of MDSCs were significantly increased via up-regulation of arginase-1. Moreover, we showed that the 3'-UTR of suppressor of cytokine signaling 3 (SOCS3) mRNA is a direct target of miR-30a. Decreased SOCS3 expression and activated Janus kinase-signal transducer and activator of transcription 3 signaling promote MDSC differentiation and suppressive activities. These findings provide new insights into the molecular mechanisms underlying MDSC expansion and function during B cell lymphoma development.

The relevance of PTEN-AKT in relation to NOTCH1-directed treatment strategies in T-cell acute lymphoblastic leukemia

The tumor suppressor phosphatase and tensin homolog (PTEN) negatively regulates phosphatidylinositol 3-kinase (PI3K)-AKT signaling and is often inactivated by mutations (including deletions) in a variety of cancer types, including T-cell acute lymphoblastic leukemia. Here we review mutation-associated mechanisms that inactivate PTEN together with other molecular mechanisms that activate AKT and contribute to T-cell leukemogenesis. In addition, we discuss how Pten mutations in mouse models affect the efficacy of gamma-secretase inhibitors to block NOTCH1 signaling through activation of AKT. Based on these models and on observations in primary diagnostic samples from patients with T-cell acute lymphoblastic leukemia, we speculate that PTEN-deficient cells employ an intrinsic homeostatic mechanism in which PI3K-AKT signaling is dampened over time. As a result of this reduced PI3K-AKT signaling, the level of AKT activation may be insufficient to compensate for NOTCH1 inhibition, resulting in responsiveness to gamma-secretase inhibitors. On the other hand, de novo acquired PTEN-inactivating events in NOTCH1-dependent leukemia could result in temporary, strong activation of PI3K-AKT signaling, increased glycolysis and glutaminolysis, and consequently gamma-secretase inhibitor resistance. Due to the central role of PTEN-AKT signaling and in the resistance to NOTCH1 inhibition, AKT inhibitors may be a promising addition to current treatment protocols for T-cell acute lymphoblastic leukemia.

Specific Gene- and MicroRNA-Expression Pattern Contributes to the Epithelial to Mesenchymal Transition in a Rat Model of Experimental Colitis

The aim of this study was to determine the gene- and microRNA-expression profile contributing to epithelial to mesenchymal transition in a rat model of experimental colitis. For this, inflammation was induced by injecting 2,4,6-trinitrobenzene sulphonic acid to the colon of male Wistar rats. Samples were taken from both inflamed and uninflamed regions of the same colon, total RNA was isolated, and the mRNA and microRNA expressions were monitored. We have determined that the expression of genes responsible for inducing mesenchymal phenotype, such as Egr1, Fgf2, Fgf7, Jak2, Notch2, Hif1α, Zeb2, Mmp9, Lox, and Vim, was all significantly induced in the inflamed regions of the affected colons while the epithelial marker E-cadherin (Cdh1) was downregulated. In contrast, the expression of microRNAs miR-192, miR-143, miR-375, miR-30a, miR-107, and miR-200b responsible for the regulation of the above mentioned genes was significantly downregulated in inflamed colon. Importantly, we detected moderate induction in the expression of five out of six tested microRNAs in the uninflamed regions. In summary, we identified numerous interacting genes and microRNAs with mutually exclusive expression pattern in inflamed regions of colitis-induced rats. These findings suggest that—among others—an important step in the epithelial to mesenchymal transition in experimental colitis is the dysregulated microRNA expression.

Regulation of PI3K signaling in T-cell acute lymphoblastic leukemia: a novel PTEN/Ikaros/miR-26b mechanism reveals a critical targetable role for PIK3CD

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy, and T-ALL patients are prone to early disease relapse and suffer from poor outcomes. The PTEN, PI3K/AKT, and Notch pathways are frequently altered in T-ALL. PTEN is a tumor suppressor that inactivates the PI3K pathway. We profiled miRNAs in Pten-deficient mouse T-ALL and identified miR-26b as a potentially dysregulated gene. We validated decreased expression levels of miR-26b in mouse and human T-ALL cells. In addition, expression of exogenous miR-26b reduced proliferation and promoted apoptosis of T-ALL cells in vitro, and hindered progression of T-ALL in vivo. Furthermore, miR-26b inhibited the PI3K/AKT pathway by directly targeting PIK3CD, the gene encoding PI3Kδ, in human T-ALL cell lines. ShRNA for PIK3CD and CAL-101, a PIK3CD inhibitor, reduced the growth and increased apoptosis of T-ALL cells. Finally, we showed that PTEN induced miR-26b expression by regulating the differential expression of Ikaros isoforms that are transcriptional regulators of miR-26b. These results suggest that miR-26b functions as a tumor suppressor in the development of T-ALL. Further characterization of targets and regulators of miR-26b may be promising for the development of novel therapies.

T-ALL and thymocytes: a message of noncoding RNAs

In the last decade, the role for noncoding RNAs in disease was clearly established, starting with microRNAs and later expanded towards long noncoding RNAs. This was also the case for T cell acute lymphoblastic leukemia, which is a malignant blood disorder arising from oncogenic events during normal T cell development in the thymus. By studying the transcriptomic profile of protein-coding genes, several oncogenic events leading to T cell acute lymphoblastic leukemia (T-ALL) could be identified. In recent years, it became apparent that several of these oncogenes function via microRNAs and long noncoding RNAs. In this review, we give a detailed overview of the studies that describe the noncoding RNAome in T-ALL oncogenesis and normal T cell development.

Burrowing through the Heterogeneity: Review of Mouse Models of PTCL-NOS

Currently, there are 19 different peripheral T-cell lymphoma (PTCL) entities recognized by the World Health Organization; however, ~70% of PTCL diagnoses fall within one of three subtypes [i.e., peripheral T-cell lymphoma not otherwise specified (PTCL-NOS), anaplastic large-cell lymphoma, and angioimmunoblastic T-cell lymphoma]. PTCL-NOS is a grouping of extra-thymic neoplasms that represent a challenging and heterogeneous subset of non-Hodgkin’s lymphomas. Research into peripheral T-cell lymphomas has been cumbersome as the lack of defining cytogenetic, histological, and molecular features has stymied diagnosis and treatment of these diseases. Similarly, the lacks of genetically manipulated murine models that faithfully recapitulate disease characteristics were absent prior to the turn of the century. Herein, we review the literature concerning existing mouse models for PTLC-NOS, while paying particular attention to the etiology of this heterogeneous disease.

miR‑30a‑5p in the tumorigenesis of renal cell carcinoma: A tumor suppressive microRNA

Renal cell carcinoma (RCC) is the most common type of malignant tumor of the adult kidney and has a poor prognosis. MicroRNAs (miRs) are important in a wide range of biological and pathological processes, including cell differentiation, migration, growth, proliferation, apoptosis and metabolism. The present study aimed to determine the role exerted by miR‑30a‑5p in the tumorigenesis of RCC. The expression levels of miR‑30a‑5p in RCC tissues and RCC‑derived cells were demonstrated to be significantly downregulated by real‑time quantitative polymerase chain reaction (RT‑qPCR). Wound scratch assay, cell proliferation assay and flow cytometric analysis revealed that the abilities of migration and proliferation of the RCC‑derived cells were suppressed, whereas cell apoptosis was promoted, when miR‑30a‑5p was overexpressed in these cells. N‑acetylgalactosaminyltransferase 7 (GALNT7) was predicted to be one target gene of miR‑30a‑5p by bioinformatics analysis. Luciferase reporter assay, RT‑qPCR and western blotting were performed to confirm that GALNT7 is the direct conserved target of miR‑30a‑5p. These results suggested that miR‑30a‑5p has a tumor‑suppressive role in the tumorigenesis of RCC.

MicroRNA-30a as a prognostic factor in urothelial carcinoma of bladder inhibits cellular malignancy by antagonising Notch1

OBJECTIVE

To explore the relation between microRNA-30a (miR-30a) and Notch1, and to evaluate the potential prognostic role of miR-30a in invasive urothelial carcinoma of the bladder (UCB).

PATIENTS AND METHODS

In all, 50 invasive UCB tissue specimens, along with the adjacent bladder tissue specimens were obtained, and the clinical parameters of the 50 patients were analysed. Bioinformatics analysis was performed and miR-30a was selected as a potential miRNA targeting Notch1, with a luciferase assay performed to verify the binding site between miR-30a and Notch1. Quantitative real-time reverse transcriptase-polymerase chain reaction was used to assess the RNA expressions of miR-30a and Notch1, while Western Blotting and immunohistochemical staining were used to assess the protein expression of Notch1. Finally, cell proliferation, cell cycle, cell migration and invasion assays were used to evaluate the cellular effects of miR-30a and Notch1 on the UCB cell lines T24 and 5637.

RESULTS

MiR-30a was downregulated in tumour tissues when compared with adjacent bladder tissues (P < 0.001), negatively correlating with Notch1 messenger RNA (R(2) 0.106, P = 0.021) in invasive UCB, and miR-30a expression further decreased in patients with shorter overall survival and disease-free survival (P = 0.039 and P = 0.037, respectively). The luciferase assay showed that miR-30a inhibited the Notch1 3'-untranslated region reporter activities in the T24 and 5637 cell lines (both P < 0.001). Both miR-30a and small interfering RNA Notch1 negatively regulated cell proliferation (P = 0.002 and P = 0.035 in T24; P = 0.029 and P = 0.037 in 5637 cell lines), activated cell cycle arrest (both P < 0.001 in T24; both P < 0.001 in 5637 cell lines), and prevented cellular migration (both P < 0.001 in T24; P = 0.003 and P < 0.001 in 5637 cell lines) and invasion (P = 0.009 and P = 0.006 in T24; P = 0.006 and P = 0.002 in 5637 cell lines) abilities. Ectopic Notch1 without the 3'untranslated region partially rescued the above-mentioned cellular effects of over-expressed miR-30a on T24 and 5637 cells.

CONCLUSIONS

MiR-30a lessens cellular malignancy by antagonising oncogene Notch1 and plays an effective prognostic role in invasive UCB.

LncRNA NALT interaction with NOTCH1 promoted cell proliferation in pediatric T cell acute lymphoblastic leukemia

Long non-coding RNA (lncRNA) was referred to be participating in various malignant tumors. Location based analysis of the mechanism in lncRNA and genes have been highly focused. In this study, we reported that lncRNA named NALT which was located near NOTCH1 within 100 bp away. We confirmed that up-regulation of NALT associating with NOTCH1 in human samples. Increased expression of NALT dramatically promoted cell proliferation in cell lines via CCK8 assay and EDU stain. Further xenograft tumor also indicated the growth inducing affection of NALT while could be partial reversed by GSI. Besides, through sorting the side-population cells in T ALL cells treated with NALT shRNA could decrease percentage of SP cell which companied by the down-regulation of NOTCH1. Gal4-λN/BoxB reporter system revealed that the nuclear located NALT could function as a transcription activator which caused an activation of NOTCH signal pathway as confirmed by western blot. Taken together, we found a neighbor of NOTCH1, Lnc-RP11-611D20.2 (named NALT) which could regulate the NOTCH1 signal pathway through cis-regulation. This founding may trigger a comparable development of diagnosis or novel molecularly-directed therapies.