The Notch/Hes1 pathway sustains NF-κB activation through CYLD repression in T cell leukemia

Amicis Omnia Sunt Communia: NF-κB Inhibition as an Alternative to Overcome Osteosarcoma Heterogeneity

Tumor heterogeneity poses a significant challenge in osteosarcoma (OS) treatment. In this regard, the "omics" era has constantly expanded our understanding of biomarkers and altered signaling pathways (i.e., PI3K/AKT/mTOR, WNT/β-catenin, NOTCH, SHH/GLI, among others) involved in OS pathophysiology. Despite different players and complexities, many commonalities have been described, among which the nuclear factor kappa B (NF-κB) stands out. Its altered activation is pervasive in cancer, with pleiotropic action on many disease-relevant traits. Thus, in the scope of this article, we highlight the evidence of NF-κB dysregulation in OS and its integration with other cancer-related pathways while we summarize the repertoire of compounds that have been described to interfere with its action. In silico strategies were used to demonstrate that NF-κB is closely coordinated with other commonly dysregulated signaling pathways not only by functionally interacting with several of their members but also by actively participating in the regulation of their transcription. While existing inhibitors lack selectivity or act indirectly, the therapeutic potential of targeting NF-κB is indisputable, first for its multifunctionality on most cancer hallmarks, and secondly, because, as a common downstream effector of the many dysregulated pathways influencing OS aggressiveness, it turns complex regulatory networks into a simpler picture underneath molecular heterogeneity.

The emerging role of CARM1 in cancer

Coactivator-associated arginine methyltransferase 1 (CARM1), pivotal for catalyzing arginine methylation of histone and non-histone proteins, plays a crucial role in developing various cancers. CARM1 was initially recognized as a transcriptional coregulator by orchestrating chromatin remodeling, transcription regulation, mRNA splicing and stability. This diverse functionality contributes to the recruitment of transcription factors that foster malignancies. Going beyond its established involvement in transcriptional control, CARM1-mediated methylation influences a spectrum of biological processes, including the cell cycle, metabolism, autophagy, redox homeostasis, and inflammation. By manipulating these physiological functions, CARM1 becomes essential in critical processes such as tumorigenesis, metastasis, and therapeutic resistance. Consequently, it emerges as a viable target for therapeutic intervention and a possible biomarker for medication response in specific cancer types. This review provides a comprehensive exploration of the various physiological functions of CARM1 in the context of cancer. Furthermore, we discuss potential CARM1-targeting pharmaceutical interventions for cancer therapy.

NF-κB in biology and targeted therapy: new insights and translational implications

NF-κB signaling has been discovered for nearly 40 years. Initially, NF-κB signaling was identified as a pivotal pathway in mediating inflammatory responses. However, with extensive and in-depth investigations, researchers have discovered that its role can be expanded to a variety of signaling mechanisms, biological processes, human diseases, and treatment options. In this review, we first scrutinize the research process of NF-κB signaling, and summarize the composition, activation, and regulatory mechanism of NF-κB signaling. We investigate the interaction of NF-κB signaling with other important pathways, including PI3K/AKT, MAPK, JAK-STAT, TGF-β, Wnt, Notch, Hedgehog, and TLR signaling. The physiological and pathological states of NF-κB signaling, as well as its intricate involvement in inflammation, immune regulation, and tumor microenvironment, are also explicated. Additionally, we illustrate how NF-κB signaling is involved in a variety of human diseases, including cancers, inflammatory and autoimmune diseases, cardiovascular diseases, metabolic diseases, neurological diseases, and COVID-19. Further, we discuss the therapeutic approaches targeting NF-κB signaling, including IKK inhibitors, monoclonal antibodies, proteasome inhibitors, nuclear translocation inhibitors, DNA binding inhibitors, TKIs, non-coding RNAs, immunotherapy, and CAR-T. Finally, we provide an outlook for research in the field of NF-κB signaling. We hope to present a stereoscopic, comprehensive NF-κB signaling that will inform future research and clinical practice.

Comprehensive analysis of the proximity-dependent nuclear interactome for the oncoprotein NOTCH1 in live cells

Notch signaling plays a critical role in cell fate decisions in all cell types. Furthermore, gain-of-function mutations in NOTCH1 have been uncovered in many human cancers. Disruption of Notch signaling has recently emerged as an attractive disease treatment strategy. However, the nuclear interaction landscape of the oncoprotein NOTCH1 remains largely unexplored. We therefore employed here a proximity-dependent biotin identification approach to identify in vivo protein associations with the nuclear Notch1 intracellular domain in live cells. We identified a large set of previously reported and unreported proteins that associate with NOTCH1, including general transcription and elongation factors, DNA repair and replication factors, coactivators, corepressors, and components of the NuRD and SWI/SNF chromatin remodeling complexes. We also found that Notch1 intracellular domain associates with protein modifiers and components of other signaling pathways that may influence Notch signal transduction and protein stability such as USP7. We further validated the interaction of NOTCH1 with histone deacetylase 1 or GATAD2B using protein network analysis, proximity-based ligation, in vivo cross-linking and coimmunoprecipitation assays in several Notch-addicted cancer cell lines. Through data mining, we also revealed potential drug targets for the inhibition of Notch signaling. Collectively, these results provide a valuable resource to uncover the mechanisms that fine-tune Notch signaling in tumorigenesis and inform therapeutic targets for Notch-addicted tumors.

Sulindac sulfide as a non-immune suppressive γ-secretase modulator to target triple-negative breast cancer

Introduction

Triple-negative breast cancer (TNBC) comprises a heterogeneous group of clinically aggressive tumors with high risk of recurrence and metastasis. Current pharmacological treatment options remain largely limited to chemotherapy. Despite promising results, the efficacy of immunotherapy and chemo-immunotherapy in TNBC remains limited. There is strong evidence supporting the involvement of Notch signaling in TNBC progression. Expression of Notch1 and its ligand Jagged1 correlate with poor prognosis. Notch inhibitors, including g-secretase inhibitors (GSIs), are quite effective in preclinical models of TNBC. However, the success of GSIs in clinical trials has been limited by their intestinal toxicity and potential for adverse immunological effects, since Notch plays key roles in T-cell activation, including CD8 T-cells in tumors. Our overarching goal is to replace GSIs with agents that lack their systemic toxicity and ideally, do not affect tumor immunity. We identified sulindac sulfide (SS), the active metabolite of FDA-approved NSAID sulindac, as a potential candidate to replace GSIs.

Methods

We investigated the pharmacological and immunotherapeutic properties of SS in TNBC models in vitro, ex-vivo and in vivo.

Results

We confirmed that SS, a known γ-secretase modulator (GSM), inhibits Notch1 cleavage in TNBC cells. SS significantly inhibited mammosphere growth in all human and murine TNBC models tested. In a transplantable mouse TNBC tumor model (C0321), SS had remarkable single-agent anti-tumor activity and eliminated Notch1 protein expression in tumors. Importantly, SS did not inhibit Notch cleavage in T- cells, and the anti-tumor effects of SS were significantly enhanced when combined with a-PD1 immunotherapy in our TNBC organoids and in vivo.

Discussion

Our data support further investigation of SS for the treatment of TNBC, in conjunction with chemo- or -chemo-immunotherapy. Repurposing an FDA-approved, safe agent for the treatment of TNBC may be a cost-effective, rapidly deployable therapeutic option for a patient population in need of more effective therapies.

Uncovering NOTCH1 as a Promising Target in the Treatment of MLL-Rearranged Leukemia

MLL rearrangement (MLLr) is responsible for the development of acute leukemias with poor outcomes. Therefore, new therapeutic approaches are urgently needed. The NOTCH1 pathway plays a critical role in the pathogenesis of many cancers including acute leukemia. Using a CRISPR/Cas9 MLL-AF4/-AF9 translocation model, the newly developed NOTCH1 inhibitor CAD204520 with less toxic side effects allowed us to unravel the impact of NOTCH1 as a pathogenic driver and potential therapeutic target in MLLr leukemia. RNA sequencing (RNA-seq) and RT-qPCR of our MLLr model and MLLr cell lines showed the NOTCH1 pathway was overexpressed and activated. Strikingly, we confirmed this elevated expression level in leukemia patients. We also demonstrated that CAD204520 treatment of MLLr cells significantly reduces NOTCH1 and its target genes as well as NOTCH1 receptor expression. This was not observed with a comparable cytarabine treatment, indicating the specificity of the small molecule. Accordingly, treatment with CAD204520 resulted in dose-dependent reduced proliferation and viability, increased apoptosis, and the induction of cell cycle arrest via the downregulation of MLL and NOTCH1 target genes. In conclusion, our findings uncover the oncogenic relevance of the NOTCH1 pathway in MLLr leukemia. Its inhibition leads to specific anti-leukemic effects and paves the way for further evaluation in clinical settings.

CYLD stimulates macrophage phagocytosis of leukemic cells through STAT1 signalling in acute myeloid leukemia

Acute myeloid leukemia (AML) is the most aggressive hematopoietic malignancy characterized by uncontrolled proliferation of myeloid progenitor cells within the bone marrow. Tumor suppressor cylindromatosis (CYLD) is a deubiquitinating enzyme, which suppresses inflammatory response in macrophages. Macrophages have a central role in the defense against foreign substances and circulating cancer cells by their professional phagocytic capacity. Little is known about contributions of CYLD to changes in biological properties of human macrophages and its involvement in AML. The present study, therefore, explored whether macrophage functions in healthy individuals and AML patients are influenced by CYLD. To this end, ninety-two newly diagnosed AML patients and 80 healthy controls were recruited. The mRNA expression levels of inflammation-related genes were evaluated by real-time PCR, cell maturation, phagocytosis and apoptosis assays by flow cytometry and secretion of inflammatory cytokines by ELISA. As a result, AML patients with the low CYLD expression were significantly higher in M4/M5 than other subtypes according to the FAB type. The low CYLD expression was also closely associated with older patients and enhanced level of LDH in AML. Moreover, treatment of normal macrophages with CYLD siRNA enhanced activation of STAT-1, leading to increases in expressions of maturation markers and IL-6 production as well as suppression in cell apoptosis and phagocytosis, while macrophage phagocytosis from AML M4/M5b was higher than that from healthy controls upon CYLD siRNA transfection through STAT1 signalling. In conclusion, the inhibitory effects of CYLD on macrophage functions are expected to affect the immune response in AML.

SHIP1 Is Present but Strongly Downregulated in T-ALL, and after Restoration Suppresses Leukemia Growth in a T-ALL Xenotransplantation Mouse Model

Acute lymphoblastic leukemia (ALL) is the most common cause of cancer-related death in children. Despite significantly increased chances of cure, especially for high-risk ALL patients, it still represents a poor prognosis for a substantial fraction of patients. Misregulated proteins in central switching points of the cellular signaling pathways represent potentially important therapeutic targets. Recently, the inositol phosphatase SHIP1 (SH2-containing inositol 5-phosphatase) has been considered as a tumor suppressor in leukemia. SHIP1 serves as an important negative regulator of the PI3K/AKT signaling pathway, which is frequently constitutively activated in primary T-ALL. In contrast to other reports, we show for the first time that SHIP1 has not been lost in T-ALL cells, but is strongly downregulated. Reduced expression of SHIP1 leads to an increased activation of the PI3K/AKT signaling pathway. SHIP1-mRNA expression is frequently reduced in primary T-ALL samples, which is recapitulated by the decrease in SHIP1 expression at the protein level in seven out of eight available T-ALL patient samples. In addition, we investigated the change in the activity profile of tyrosine and serine/threonine kinases after the restoration of SHIP1 expression in Jurkat T-ALL cells. The tyrosine kinase receptor subfamilies of NTRK and PDGFR, which are upregulated in T-ALL subgroups with low SHIP1 expression, are significantly disabled after SHIP1 reconstitution. Lentiviral-mediated reconstitution of SHIP1 expression in Jurkat cells points to a decreased cellular proliferation upon transplantation into NSG mice in comparison to the control cohort. Together, our findings will help to elucidate the complex network of cell signaling proteins, further support a functional role for SHIP1 as tumor suppressor in T-ALL and, much more importantly, show that full-length SHIP1 is expressed in T-ALL samples.

The role of SF3B1 and NOTCH1 in the pathogenesis of leukemia

The discovery of new genes/pathways improves our knowledge of cancer pathogenesis and presents novel potential therapeutic options. For instance, splicing factor 3b subunit 1 (SF3B1) and NOTCH1 genetic alterations have been identified at a high frequency in hematological malignancies, such as leukemia, and may be related to the prognosis of involved patients because they change the nature of malignancies in different ways like mediating therapeutic resistance; therefore, studying these gene/pathways is essential. This review aims to discuss SF3B1 and NOTCH1 roles in the pathogenesis of various types of leukemia and the therapeutic potential of targeting these genes or their mutations to provide a foundation for leukemia treatment.

Notch Signaling in Acute Inflammation and Sepsis

Notch signaling, a highly conserved pathway in mammals, is crucial for differentiation and homeostasis of immune cells. Besides, this pathway is also directly involved in the transmission of immune signals. Notch signaling per se does not have a clear pro- or anti-inflammatory effect, but rather its impact is highly dependent on the immune cell type and the cellular environment, modulating several inflammatory conditions including sepsis, and therefore significantly impacts the course of disease. In this review, we will discuss the contribution of Notch signaling on the clinical picture of systemic inflammatory diseases, especially sepsis. Specifically, we will review its role during immune cell development and its contribution to the modulation of organ-specific immune responses. Finally, we will evaluate to what extent manipulation of the Notch signaling pathway could be a future therapeutic strategy.

The Orphan GPR50 Receptor Regulates the Aggressiveness of Breast Cancer Stem-like Cells via Targeting the NF-kB Signaling Pathway

The expression of GPR50 in CSLC and several breast cancer cell lines was assessed by RT-PCR and online platform (UALCAN, GEPIA, and R2 gene analysis). The role of GPR50 in driving CSLC, sphere formation, cell proliferation, and migration was performed using shGPR50 gene knockdown, and the role of GPR50-regulated signaling pathways was examined by Western blotting and Luciferase Assay. Herein, we confirmed that the expression of G protein-coupled receptor 50 (GPR50) in cancer stem-like cells (CSLC) is higher than that in other cancer cells. We examined that the knockdown of GPR50 in CSLC led to decreased cancer properties, such as sphere formation, cell proliferation, migration, and stemness. GPR50 silencing downregulates NF-kB signaling, which is involved in sphere formation and aggressiveness of CSLC. In addition, we demonstrated that GPR50 also regulates ADAM-17 activity by activating NOTCH signaling pathways through the AKT/SP1 axis in CSLC. Overall, we demonstrated a novel GPR50-mediated regulation of the NF-κB-Notch signaling pathway, which can provide insights into CSLC progression and prognosis, and NF-κB-NOTCH-based CSLC treatment strategies.

Transcriptional regulation of Notch1 by nuclear factor-κB during T cell activation

Notch1 plays important roles in T cell development and is highly expressed in activated CD4⁺ T cells. However, the underlying mechanism of Notch1 transcription in T cells has not been fully characterized. Therefore, we aimed to determine how Notch1 expression is regulated during the activation of CD4⁺ T cells. Both the surface expression and mRNA transcription of Notch1 were significantly higher in activated CD4⁺ T cells, but the inhibition of phosphatidylinositol 3-kinase (PI3K) by LY294002 or deletion of the Pdk1 gene impaired this upregulation of Notch1. Interrogation of the Notch1 promoter region using serially deleted Notch1 promoter reporters revealed that the - 300 to - 270 region is crucial for its transcription in activated T cells. In addition, we found that nuclear factor (NF)-κB subunits containing RelA bind directly to this promoter region, thereby upregulating transcription. In addition, inhibition of NF-κB by SN50 impaired upregulation of Notch1 surface protein and mRNA in activated CD4⁺ T cells. Thus, we provide evidence that Notch1 transcription in activated CD4⁺ T cells is upregulated via the PI3K-PDK1-NF-κB signaling pathway.

Oncogenic deubiquitination controls tyrosine kinase signaling and therapy response in acute lymphoblastic leukemia

Dysregulation of kinase signaling pathways favors tumor cell survival and therapy resistance in cancer. Here, we reveal a posttranslational regulation of kinase signaling and nuclear receptor activity via deubiquitination in T cell acute lymphoblastic leukemia (T-ALL). We observed that the ubiquitin-specific protease 11 (USP11) is highly expressed and associates with poor prognosis in T-ALL. USP11 ablation inhibits leukemia progression in vivo, sparing normal hematopoiesis. USP11 forms a complex with USP7 to deubiquitinate the oncogenic lymphocyte cell-specific protein-tyrosine kinase (LCK) and enhance its activity. Impairment of LCK activity leads to increased glucocorticoid receptor (GR) expression and glucocorticoids sensitivity. Genetic knockout of USP7 improved the antileukemic efficacy of glucocorticoids in vivo. The transcriptional activation of GR target genes is orchestrated by the deubiquitinase activity and mediated via an increase in enhancer-promoter interaction intensity. Our data unveil how dysregulated deubiquitination controls leukemia survival and drug resistance, suggesting previously unidentified therapeutic combinations toward targeting leukemia.

Roles of transducin-like enhancer of split (TLE) family proteins in tumorigenesis and immune regulation

Mammalian transducin-like enhancer of split family proteins (TLEs) are homologous to Drosophila Groucho (Gro) and are essential transcriptional repressors. Seven TLE family members, TLE1-7, have been identified to date. These proteins do not bind DNA directly; instead, they bind a set of transcription factors and thereby inhibit target gene expression. Loss of TLEs in mice usually leads to defective early development; however, TLE functions in developmentally mature cells are unclear. Recent studies have revealed that TLEs are dysregulated in certain human cancer types and may function as oncogenes or tumor suppressors in different contexts. TLE levels also affect the efficacy of cancer treatments and the development of drug resistance. In addition, TLEs play critical roles in the development and function of immune cells, including macrophages and lymphocytes. In this review, we provide updates on the expression, function, and mechanism of TLEs; discuss the roles played by TLEs in tumorigenesis and the inflammatory response; and elaborate on several TLE-associated signaling pathways, including the Notch, Wnt, and MAPK pathways. Finally, we discuss potential strategies for targeting TLEs in cancer therapy.

Dysregulation of FBW7 in malignant lymphoproliferative disorders

The ubiquitin-proteasome system (UPS) is involved in various aspects of cell processes, including cell proliferation, differentiation, and cell cycle progression. F-box and WD repeat domain-containing protein 7 (FBW7), as a key component of UPS proteins and a critical tumor suppressor in human cancers, controls proteasome-mediated degradation by ubiquitinating oncoproteins such as c-Myc, Mcl-1, cyclin E, and Notch. It also plays a role in the development of various cancers, including solid and hematological malignancies, such as T-cell acute lymphoblastic leukemia, diffuse large B-cell lymphoma, and multiple myeloma. This comprehensive review emphasizes the functions, substrates, and expression of FBW7 in malignant lymphoproliferative disorders.

Ischemic preconditioning/ischemic postconditioning alleviates anoxia/reoxygenation injury via the Notch1/Hes1/VDAC1 axis

Ischemic preconditioning (IPC), and ischemic postconditioning (IPost) have a significant protective effect on myocardial ischemia/reperfusion (MI/R) injury by alleviating oxidative stress and mitochondrial disturbances, although the underlying molecular mechanisms are unclear. The study was to demonstrate that cardioprotection against anoxia/reoxygenation (A/R) injury is transduced via the Notch1/Hes1/VDAC1 signaling pathway. Using mass spectrometry and tandem affinity purification (TAP), to screen for differentially expressed proteins associated with Hes1, followed by standard bioinformatics analysis. The co-immunoprecipitation (Co-IP) assay confirmed an interaction between Hes1 and VDAC1 proteins. H9c2 cells were transfected with Hes1 adenoviral N-terminal TAP vector (AD-NTAP/Hes1) and Hes1-short hairpin RNA adenoviral vector (AD-Hes1-shRNA) to establish A/R injury, IPC, and IPost models, respectively. The expression of Hes1 and VDAC1 proteins were measured by western blot analysis, while the levels of reactive oxygen species (ROS), mitochondrial membrane potential (ΔΨm), and apoptosis were evaluated by flow cytometry. AD-NTAP/Hes1 can activate the exogenous protein expression of Hes1, thus decreasing creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) activity and promoting cell viability. The study found that VDAC1 was a potential target protein for Hes1 and the overexpression of Hes1 protein expression downregulated protein expression levels of VDAC1, reduced ROS production, stabilized ΔΨm, and inhibited apoptosis in H9c2 cells. Additionally, downregulation of Hes1 protein expression also upregulated VDAC1 protein expression, increased ROS production, imbalanced ΔΨm, promoted cell apoptosis, and attenuated the cardioprotection afforded by IPC and IPost. The Notch1/Hes1 signaling pathway activated by IPC/IPost can directly downregulate the protein expression of VDAC1 and consequently relieve A/R injury.

EMD originates from hyaluronan-induced homophilic interactions of CD44 variant-expressing MM cells under shear stress

Extramedullary disease (EMD) is known to be associated with chemoresistance and poor prognosis in multiple myeloma (MM); however, the mechanisms of its development are not fully understood. Elucidating the mechanism of EMD development and its therapeutic targeting would greatly contribute to further improvement of treatment outcome in patients with MM. Here, we show that bone marrow stroma cell-derived hyaluronan (HA) elicits homophilic interactions of MM cells by binding to surface CD44, especially long-stretch variants, under physiological shear stress and generates cell clusters that might develop into EMD. We recapitulated the development of EMD via administration of HA in a syngeneic murine MM model in a CD44-dependent manner. HA-induced MM cell clusters exhibited the specific resistance to proteasome inhibitors (PIs) in vitro and in murine models via γ-secretase-mediated cleavage of the intracellular domains of CD44, which in turn transactivated PI resistance-inducible genes. Treatment of HA-injected mice with anti-CD44 antibody or γ-secretase inhibitors readily suppressed the development of EMD from transplanted MM cells and significantly prolonged the survival of recipients by overcoming PI resistance. The HA-CD44 axis represents a novel pathway to trigger EMD development and could be a target of the prediction, prevention, and treatment of EMD in patients with MM.

Therapeutic Targeting Notch2 Protects Bone Micro-Vasculatures from Methotrexate Chemotherapy-Induced Adverse Effects in Rats

Intensive cancer chemotherapy is well known to cause bone vasculature disfunction and damage, but the mechanism is poorly understood and there is a lack of treatment. Using a rat model of methotrexate (MTX) chemotherapy (five once-daily dosses at 0.75 mg/kg), this study investigated the roles of the Notch2 signalling pathway in MTX chemotherapy-induced bone micro-vasculature impairment. Gene expression, histological and micro-computed tomography (micro-CT) analyses revealed that MTX-induced micro-vasculature dilation and regression is associated with the induction of Notch2 activity in endothelial cells and increased production of inflammatory cytokine tumour necrosis factor alpha (TNFα) from osteoblasts (bone forming cells) and bone marrow cells. Blockade of Notch2 by a neutralising antibody ameliorated MTX adverse effects on bone micro-vasculature, both directly by supressing Notch2 signalling in endothelial cells and indirectly via reducing TNFα production. Furthermore, in vitro studies using rat bone marrow-derived endothelial cell revealed that MTX treatment induces Notch2/Hey1 pathway and negatively affects their ability in migration and tube formation, and Notch2 blockade can partially protect endothelial cell functions from MTX damage.

Multiple Mechanisms of NOTCH1 Activation in Chronic Lymphocytic Leukemia: NOTCH1 Mutations and Beyond

Simple Summary

Mutations of the NOTCH1 gene are a validated prognostic marker in chronic lymphocytic leukemia and a potential predictive marker for anti-CD20-based therapies. At present, the most frequent pathological alteration of the NOTCH1 gene is due to somatic genetic mutations, which have a multifaceted functional impact. However, beside NOTCH1 mutations, other factors may lead to activation of the NOTCH1 pathway, and these include mutations of FBXW7, MED12, SPEN, SF3B1 as well as other B-cell pathways. Understanding the preferential strategies though which CLL cells hijack NOTCH1 signaling may present important clues for designing targeted treatment strategies for the management of CLL.

Abstract

The Notch signaling pathway plays a fundamental role for the terminal differentiation of multiple cell types, including B and T lymphocytes. The Notch receptors are transmembrane proteins that, upon ligand engagement, undergo multiple processing steps that ultimately release their intracytoplasmic portion. The activated protein ultimately operates as a nuclear transcriptional co-factor, whose stability is finely regulated. The Notch pathway has gained growing attention in chronic lymphocytic leukemia (CLL) because of the high rate of somatic mutations of the NOTCH1 gene. In CLL, NOTCH1 mutations represent a validated prognostic marker and a potential predictive marker for anti-CD20-based therapies, as pathological alterations of the Notch pathway can provide significant growth and survival advantage to neoplastic clone. However, beside NOTCH1 mutation, other events have been demonstrated to perturb the Notch pathway, namely somatic mutations of upstream, or even apparently unrelated, proteins such as FBXW7, MED12, SPEN, SF3B1, as well as physiological signals from other pathways such as the B-cell receptor. Here we review these mechanisms of activation of the NOTCH1 pathway in the context of CLL; the resulting picture highlights how multiple different mechanisms, that might occur under specific genomic, phenotypic and microenvironmental contexts, ultimately result in the same search for proliferative and survival advantages (through activation of MYC), as well as immune escape and therapy evasion (from anti-CD20 biological therapies). Understanding the preferential strategies through which CLL cells hijack NOTCH1 signaling may present important clues for designing targeted treatment strategies for the management of CLL.

The role and therapeutic implication of endoplasmic reticulum stress in inflammatory cancer transformation

Endoplasmic reticulum (ER) stress occurs when proteins are affected by various factors, fail to fold properly into higher structures and accumulate in the lumen of the ER, which activates the unfolded protein response (UPR) to restore normal cellular function or induce apoptosis as a self-protective mechanism. However, a growing number of studies have shown that the three branches of ER stress and the UPR can mediate inflammation and cancer development by interacting with inflammatory transformation-related signaling pathways. Targeting the UPR, especially the use of small molecules that target the active sites of the enzymes IRE1α and PERK and BIP/GRP78 inhibitors are potential strategies for treating tumors and have shown promising results in some tumor models. Therefore, in this review, we summarize the progress of ER stress/UPR research and the signaling pathways associated with inflammatory cancer transformation, provide an in-depth description of the mechanisms of these pathways, and outline strategies in the field of UPR biology in tumor therapy to provide new ideas for the mechanisms of inflammatory cancer transformation and tumor-related treatment.

Novel antitumor activity of the combined treatment of galloylquinic acids from Copaifera lucens and doxorubicin in solid Ehrlich carcinoma-bearing mice via the modulation of the Notch signaling pathway

AIMS

This study aims to investigate the potential synergistic effect of the combined treatment of galloylquinic acids compounds from Copaifera lucens with doxorubicin via the modulation of the Notch pathway in Ehrlich carcinoma-bearing mice model.

MAIN METHODS

The solid tumor model was induced in mice by s.c. injection of Ehrlich cancerous cells in the right hind limb. Sixty mice were allocated into five different groups which included treated groups with galloylquinic acids compounds, doxorubicin and their combination. Normal and tumor control groups were also used. Different biological samples were collected to measure the levels of Notch1, Hes1, Jagged1, TNF-α, IL-6, and VEGF. Histopathological and immunohistochemical examinations of tumor tissues using specific anti-NF-kβ and anti-cyclin D1 antibodies were also performed.

KEY FINDINGS

Our results showed that the combined treatment of galloylquinic acids compounds with doxorubicin significantly inhibited Notch1, Hes1, Jagged1, TNF-α, IL-6, VEGF, NF-kβ, and cyclin D1 activities.

SIGNIFICANCE

Galloylquinic acids compounds exhibited promising synergistic chemotherapeutic and oncostatic effects and promoted the chemosensitivity of doxorubicin, mainly by inhibiting the Notch signaling pathway and its downstream effectors. These compounds may be considered in cancer therapy exhibiting improved efficacy and reduced side effects of chemotherapeutic agents.

Contribution of Epithelial and Gut Microbiome Inflammatory Biomarkers to the Improvement of Colorectal Cancer Patients’ Stratification

In order to ensure that primary endpoints of clinical studies are attained, the patients’ stratification is an important aspect. Selection criteria include age, gender, and also specific biomarkers, such as inflammation scores. These criteria are not sufficient to achieve a straightforward selection, however, in case of multifactorial diseases, with unknown or partially identified mechanisms, occasionally including host factors, and the microbiome. In these cases, the efficacy of interventions is difficult to predict, and as a result, the selection of subjects is often random. Colorectal cancer (CRC) is a highly heterogeneous disease, with variable clinical features, outcomes, and response to therapy; the CRC onset and progress involves multiple sequential steps with accumulation of genetic alterations, namely, mutations, gene amplification, and epigenetic changes. The gut microbes, either eubiotic or dysbiotic, could influence the CRC evolution through a complex and versatile crosstalk with the intestinal and immune cells, permanently changing the tumor microenvironment. There have been significant advances in the development of personalized approaches for CRC screening, treatment, and potential prevention. Advances in molecular techniques bring new criteria for patients’ stratification—mutational analysis at the time of diagnosis to guide treatment, for example. Gut microbiome has emerged as the main trigger of gut mucosal homeostasis. This may impact cancer susceptibility through maintenance of the epithelial/mucus barrier and production of protective metabolites, such as short-chain fatty acids (SCFAs) via interactions with the hosts’ diet and metabolism. Microbiome dysbiosis leads to the enrichment of cancer-promoting bacterial populations, loss of protective populations or maintaining an inflammatory chronic state, all of which contribute to the development and progression of CRC. Meanwhile, variations in patient responses to anti-cancer immuno- and chemotherapies were also linked to inter-individual differences in intestine microbiomes. The authors aim to highlight the contribution of epithelial and gut microbiome inflammatory biomarkers in the improvement of CRC patients’ stratification towards a personalized approach of early diagnosis and treatment.

Blockade of the Notch Signaling Pathway Promotes M2 Macrophage Polarization to Suppress Cardiac Fibrosis Remodeling in Mice With Myocardial Infarction

Myocardial infarction (MI) is regarded as a serious ischemic heart disease on a global level. The current study set out to explore the mechanism of the Notch signaling pathway in the regulation of fibrosis remodeling after the occurrence of MI. First, experimental mice were infected with recombination signal binding protein J (RBP-J) shRNA and empty adenovirus vector, followed by the establishment of MI mouse models and detection of cardiac function. After 4 weeks of MI, mice in the sh-RBP-J group were found to exhibit significantly improved cardiac function relative to the sh-NC group. Moreover, knockdown of RBP-J brought about decreased infarct area, promoted cardiac macrophages M2 polarization, reduced cardiac fibrosis, and further decreased transcription and protein expressions of inflammatory factors and fibrosis-related factors. Furthermore, downregulation of cylindromatosis (CYLD) using si-CYLD reversed the results that knockdown of RBP-J inhibited fibrogenesis and the release of inflammatory factors. Altogether, our findings indicated that the blockade of Notch signaling promotes M2 polarization of cardiac macrophages and improves cardiac function by inhibiting the imbalance of fibrotic remodeling after MI.

Recent advances in T-cell lymphoid neoplasms

T Cells comprise many subtypes of specified lymphocytes, and their differentiation and function take place in different tissues. This cellular diversity is also observed in the multiple ways T-cell transformation gives rise to a variety of T-cell neoplasms. This review covers the main types of T-cell malignancies and their specific characteristics, emphasizing recent advances at the cellular and molecular levels as well as differences and commonalities among them.

Essential role of ALKBH5-mediated RNA demethylation modification in bile acid-induced gastric intestinal metaplasia

Bile acid reflux and subsequent caudal-related homeobox 2 (CDX2) activation contribute to gastric intestinal metaplasia (IM), a precursor of gastric cancer; however, the mechanism underlying this phenomenon is unclear. Here, we demonstrate that alkylation repair homolog protein 5 (ALKBH5), a major RNA N⁶-adenosine demethylase, is required for bile acid-induced gastric IM. Mechanistically, we revealed the N⁶-methyladenosine (m⁶A) modification profile in gastric IM for the first time and identified ZNF333 as a novel m⁶A target of ALKBH5. ALKBH5 was shown to demethylate ZNF333 mRNA, leading to enhanced ZNF333 expression by abolishing m⁶A-YTHDF2-dependent mRNA degradation. In addition, ALKBH5 activated CDX2 and downstream intestinal markers by targeting the ZNF333/CYLD axis and activating NF-κB signaling. Reciprocally, p65, the key transcription factor of the canonical NF-κB pathway, enhanced the transcription activity of ALKBH5 in the nucleus, thus forming a positive feedforward circuit. Furthermore, ALKBH5 levels were positively correlated with ZNF333 and CDX2 levels in IM tissues, indicating significant clinical relevance. Collectively, our findings suggest that an m⁶A modification-associated positive feedforward loop between ALKBH5 and NF-κB signaling is involved in generating the IM phenotype of gastric epithelial cells. Targeting the ALKBH5/ZNF333/CYLD/CDX2 axis may be a useful therapeutic strategy for gastric IM in patients with bile regurgitation.

The IRE1/XBP1 signaling axis promotes skeletal muscle regeneration through a cell non-autonomous mechanism

Skeletal muscle regeneration is regulated by coordinated activation of multiple signaling pathways. The unfolded protein response (UPR) is a major mechanism that detects and alleviates protein-folding stresses in the endoplasmic reticulum. However, the role of individual arms of the UPR in skeletal muscle regeneration remain less understood. In the present study, we demonstrate that IRE1α (also known as ERN1) and its downstream target, XBP1, are activated in skeletal muscle of mice upon injury. Myofiber-specific ablation of IRE1α or XBP1 in mice diminishes skeletal muscle regeneration that is accompanied with reduced number of satellite cells. Ex vivo cultures of myofiber explants demonstrate that ablation of IRE1α reduces the proliferative capacity of myofiber-associated satellite cells. Myofiber-specific ablation of IRE1α dampens Notch signaling and canonical NF-κB pathway in skeletal muscle of adult mice. Finally, targeted ablation of IRE1α also reduces Notch signaling, abundance of satellite cells, and skeletal muscle regeneration in the mdx mice, a model of Duchenne muscular dystrophy. Collectively, our experiments suggest that the IRE1α-mediated signaling promotes muscle regeneration through augmenting the proliferation of satellite cells in a cell non-autonomous manner.

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.

LncRNA SRA mediates cell migration, invasion, and progression of ovarian cancer via NOTCH signaling and epithelial-mesenchymal transition

Long non-coding RNA (lncRNA) is a newly identified regulator of tumor formation and tumor progression. The function and expression of lncRNAs remain to be fully elucidated, but recent studies have begun to address their importance in human health and disease. The lncRNA, SRA, known as steroid receptor activator, acts as an important modulator of gynecological cancer, and its expression may affect biological functions including proliferation, apoptosis, steroid formation, and muscle development. However, it is still not well known whether SRA is involved in the regulation of ovarian cancer. The present study investigated the molecular function and association between SRA expression and clinicopathological factors. In ovarian cancer cell lines, SRA knockdown and overexpression regulated cell migration, proliferation, and invasion. Both in vivo and in vitro experiments using knockdown and overexpression showed that SRA potently regulated epithelial-mesenchymal transition (EMT) and NOTCH pathway components. Further, clinical data confirmed that SRA was a significant predictor of overall survival (OS) and progression-free survival and patients with ovarian cancer exhibiting high expression of SRA exhibited higher recurrence rates than patients with low SRA expression. In conclusion, the present study indicates that SRA has clinical significance as its expression can predict the prognosis of ovarian cancer patients. High expression of the lncRNA SRA is strongly correlated with recurrence-free survival of ovarian cancer patients.

Deubiquitinases in hematological malignancies

Deubiquitinases (DUBs) are enzymes that control the stability, interactions or localization of most cellular proteins by removing their ubiquitin modification. In recent years, some DUBs, such as USP7, USP9X and USP10, have been identified as promising therapeutic targets in hematological malignancies. Importantly, some potent inhibitors targeting the oncogenic DUBs have been developed, showing promising inhibitory efficacy in preclinical models, and some have even undergone clinical trials. Different DUBs perform distinct function in diverse hematological malignancies, such as oncogenic, tumor suppressor or context-dependent effects. Therefore, exploring the biological roles of DUBs and their downstream effectors will provide new insights and therapeutic targets for the occurrence and development of hematological malignancies. We summarize the DUBs involved in different categories of hematological malignancies including leukemia, multiple myeloma and lymphoma. We also present the recent development of DUB inhibitors and their applications in hematological malignancies. Together, we demonstrate DUBs as potential therapeutic drug targets in hematological malignancies.

CARMA1 is required for Notch1-induced NF-κB activation in SIL-TAL1-negative T cell acute lymphoblastic leukemia

The NF-κB signaling pathway is an important downstream pathway of oncogenic Notch1 in T cell acute lymphoblastic leukemia (T-ALL) cells. However, the molecular mechanisms underlying the cascade activation of Notch1 in T-ALL cells are poorly understood. Here, we evaluated the role of CARMA1 in Notch1-induced NF-κB activation in T-ALL cells. CARMA1 was highly and specifically expressed in T-ALL cells and correlated with the prognosis of T-ALL patients. Interestingly, CARMA1 knockdown only inhibited the growth and proliferation of SIL-TAL1 fusion gene-negative T-ALL cells. In addition, CARMA1 knockdown arrested T-ALL cells at the G1 phase. Furthermore, CARMA1 knockdown significantly inhibited the proliferation of T-ALL cells in vivo and prolonged the survival of mice. Mechanistically, CARMA1 deficiency abolished Notch1-induced NF-κB transcriptional activation and significantly reduced expression levels of the NF-κB target genes c-Myc, Bcl-2, and CCR7. Taken together, these results of our study identify CARMA1 as one of the crucial mediators of Notch1-induced transformation of T-All cells, suggesting that CARMA1 is a promising therapeutic target for T-ALL due to its specific expression in lymphocytes. KEY MESSAGES: CARMA1 contributes to cell survival only in SIL-TAL1 negative T-ALL cells. CARMA1 is a crucial mediator of Notch1-induced activation of NF-κB pathway. CARMA1 is a promising therapeutic target for T-ALL.

A lineage-specific requirement for YY1 Polycomb Group protein function in early T cell development

Yin Yang 1 (YY1) is a ubiquitous transcription factor and mammalian Polycomb Group protein (PcG) with important functions for regulating lymphocyte development and stem cell self-renewal. YY1 mediates stable PcG-dependent transcriptional repression via recruitment of PcG proteins that result in histone modifications. Many questions remain unanswered regarding how cell- and tissue-specificity is achieved by PcG proteins. Here, we demonstrate that a conditional knockout of Yy1 in the hematopoietic system results in an early T cell developmental blockage at the double negative (DN) 1 stage with reduced Notch1 signaling. There is a lineage-specific requirement for YY1 PcG function. YY1 PcG domain is required for T and B cell development but not necessary for myeloid cells. YY1 functions in early T cell development are multicomponent and involve both PcG-dependent and -independent regulations. Although YY1 promotes early T cell survival through its PcG function, its function to promote the DN1-to-DN2 transition and Notch1 expression and signaling is independent of its PcG function. Our results reveal how a ubiquitously expressed PcG protein mediates lineage-specific and context-specific functions to control early T cell development.

Treatment of collagen-induced arthritis rat model by using Notch signalling inhibitor

Background

The Notch signalling pathway has been reported to play a key role in rheumatoid arthritis (RA) development. Thus, inhibition of the activation of this signalling pathway may be a promising approach to the treatment of RA. In this study, the Notch signalling inhibitor LY411575, which can inhibit both Notch1 and Notch3, was used for the treatment of collagen-induced arthritis (CIA) rats.

Methods

Wistar rats were immunised with bovine type II collagen (CII) to establish rats CIA model. The inhibitory effects of LY411575 on Notch1 intracellular domain (N1ICD) and Notch3 intracellular domain (N3ICD) protein was verified by western blot (WB) in vitro. CIA rats were treated with different doses of LY411575 for 15 and 28 days, respectively. Methotrexate and sodium carboxymethyl cellulose (CMC-Na) were used as positive and negative (vehicle) control respectively. Destruction of the rat ankle joint and the bone loss on the periarticular side were evaluated by micro-computed tomography (Micro-CT). In addition, destruction of the ankle articular cartilage and the osteoclast numbers were determined by histology. Expression of N1ICD and N3ICD in the ankle joint was detected by immunohistochemistry.

Results

LY411575 could significantly inhibit the expression of N1ICD and N3ICD in vitro. Micro-CT test showed that the ankle joint destruction significantly improved after treatment with LY411575 (5 ​mg/kg and 10 ​mg/kg, respectively). The bone quality in the LY411575 (5 ​mg/kg and 10 ​mg/kg, respectively) groups were improved compared with the vehicle group. Histological analysis showed that LY411575 (5 ​mg/kg and 10 ​mg/kg, respectively) treatment reduced the severity of ankle joint inflammation in CIA rats (including ankle joint destruction, pannus formation, and cartilage damage) and reduced the expression of N1ICD and N3ICD in CIA rats ankle joints significantly.

Conclusion

The inhibitor of Notch signalling LY411575 is an effective treatment for CIA.

The translational potential of this article

Our study provides new evidence to support the potential clinical application of Notch signalling pathway inhibitor LY411575 as a drug candidate for the treatment of RA.

FANCD2 and HES1 suppress inflammation-induced PPARɣ to prevent haematopoietic stem cell exhaustion

The Fanconi anaemia protein FANCD2 suppresses PPARƔ to maintain haematopoietic stem cell's (HSC) function; however, the underlying mechanism is not known. Here we show that FANCD2 acts in concert with the Notch target HES1 to suppress inflammation-induced PPARƔ in HSC maintenance. Loss of HES1 exacerbates FANCD2-KO HSC defects. However, deletion of HES1 does not cause more severe inflammation-mediated HSC defects in FANCD2-KO mice, indicating that both FANCD2 and HES1 are required for limiting detrimental effects of inflammation on HSCs. Further analysis shows that both FANCD2 and HES1 are required for transcriptional repression of inflammation-activated PPARg promoter. Inflammation orchestrates an overlapping transcriptional programme in HSPCs deficient for FANCD2 and HES1, featuring upregulation of genes in fatty acid oxidation (FAO) and oxidative phosphorylation. Loss of FANCD2 or HES1 augments both basal and inflammation-primed FAO. Targeted inhibition of PPARƔ or the mitochondrial carnitine palmitoyltransferase-1 (CPT1) reduces FAO and ameliorates HSC defects in inflammation-primed HSPCs deleted for FANCD2 or HES1 or both. Finally, depletion of PPARg or CPT1 restores quiescence in these mutant HSCs under inflammatory stress. Our results suggest that this novel FANCD2/HES1/PPARƔ axis may constitute a key component of immunometabolic regulation, connecting inflammation, cellular metabolism and HSC function.

Downregulation of microRNA-9-5p promotes synaptic remodeling in the chronic phase after traumatic brain injury

The level of microRNA-9-5p (miRNA-9-5p) in brain tissues is significantly changed in the chronic phase after traumatic brain injury (TBI). However, the effect of miRNA-9-5p on brain function after TBI has not been elucidated. In this study, we used a controlled cortical impact (CCI) model to induce TBI in Sprague-Dawley rats. Brain microvascular endothelial cells (BMECs), astrocytes, and neurons were extracted from immature Sprague-Dawley rats and cocultured to reconstruct the neurovascular unit (NVU) in vitro. The results showed that downregulation of miRNA-9-5p in the chronic phase contributed to neurological function recovery by promoting astrocyte proliferation and increasing the release of astrocyte-derived neurotrophic factors around injured brain tissues after TBI. A dual-luciferase reporter assay validated that miRNA-9-5p was a post-transcriptional modulator of thrombospondin 2 (Thbs-2), and downregulation of miRNA-9-5p promoted Thbs-2 expression in astrocytes. Furthermore, we verified that Thbs-2 can promote Notch pathway activation by directly binding to Jagged and Notch. Through in vitro experiments, we found that the expression of synaptic proteins and the number of synaptic bodies were increased in neurons in the NVU, which was constructed using astrocytes pretreated with miRNA-9-5p inhibitor. Moreover, we also found that downregulation of miRNA-9-5p promoted Thbs-2 expression in astrocytes, which activated the Notch/cylindromatosis/transforming growth factor-β-activated kinase 1 pathway in neurons and promoted the expression of synaptic proteins, including post-synaptic density protein 95 and synaptotagmin. Based on these results, miRNA-9-5p may be a new promising prognostic marker and treatment target for TBI.

Functional Gene Expression Differentiation of the Notch Signaling Pathway in Female Reproductive Tract Tissues-A Comprehensive Review With Analysis

The Notch pathway involves evolutionarily conserved signaling regulating the development of the female tract organs such as breast, ovary, cervix, and uterine endometrium. A great number of studies revealed Notch aberrancies in association with their carcinogenesis and disease progression, the management of which is still challenging. The present study is a comprehensive review of the available literature on Notch signaling during the normal development and carcinogenesis of the female tract organs. The review has been enriched with our analyses of the TCGA data including breast, cervical, ovarian, and endometrial carcinomas concerning the effects of Notch signaling at two levels: the core components and downstream effectors, hence filling the lack of global overview of Notch-driven carcinogenesis and disease progression. Phenotype heterogeneity regarding Notch signaling was projected in two uniform manifold approximation and projection algorithm dimensions, preceded by the principal component analysis step reducing the data burden. Additionally, overall and disease-free survival analyses were performed with the optimal cutpoint determination by Evaluate Cutpoints software to establish the character of particular Notch components in tumorigenesis. In addition to the review, we demonstrated separate models of the examined cancers of the Notch pathway and its targets, although expression profiles of all normal tissues were much more similar to each other than to its cancerous compartments. Such Notch-driven cancerous differentiation resulted in a case of opposite association with DFS and OS. As a consequence, target genes also show very distinct profiles including genes associated with cell proliferation and differentiation, energy metabolism, or the EMT. In conclusion, the observed Notch associations with the female tract malignancies resulted from differential expression of target genes. This may influence a future analysis to search for new therapeutic targets based on specific Notch pathway profiles.

HES1 and HES4 have non-redundant roles downstream of Notch during early human T-cell development

In both mouse and human, Notch1 activation is the main initial driver to induce T-cell development in hematopoietic progenitor cells. The initiation of this developmental process coincides with Notch1-dependent repression of differentiation towards other hematopoietic lineages. Although well described in mice, the role of the individual Notch1 target genes during these hematopoietic developmental choices is still unclear in human, particularly for HES4 since no orthologous gene is present in the mouse. Here, we investigated the functional capacity of the Notch1 target genes HES1 and HES4 to modulate human Notch1-dependent hematopoietic lineage decisions and their requirement during early T-cell development. We show that both genes are upregulated in a Notch-dependent manner during early T-cell development and that HES1 acts as a repressor of differentiation by maintaining a quiescent stem cell signature in CD34+ hematopoietic progenitor cells. While HES4 can also inhibit natural killer and myeloid cell development like HES1, it acts differently on the T- versus B-cell lineage choice. Surprisingly, HES4 is not capable of repressing B-cell development, the most sensitive hematopoietic lineage with respect to Notch-mediated repression. In contrast to HES1, HES4 promotes initiation of early T-cell development, but ectopic expression of HES4, or HES1 and HES4 combined, is not sufficient to induce T-lineage differentiation. Importantly, knockdown of HES1 or HES4 significantly reduces human T-cell development. Overall, we show that the Notch1 target genes HES1 and HES4 have non-redundant roles during early human T-cell development which may relate to differences in mediating Notch-dependent human hematopoietic lineage decisions.

MicroRNA‑223‑induced inhibition of the FBXW7 gene affects the proliferation and apoptosis of colorectal cancer cells via the Notch and Akt/mTOR pathways

The tumour suppressor gene F-box and WD repeat domain-containing 7 (FBXW7) plays an important role in human cancer by regulating cell division, proliferation and differentiation. However, the exact regulatory mechanisms of microRNA (miR)-223 in colorectal cancer (CRC) cells are still unknown. The present study aimed to investigate the effect and mechanism of miR-223 inhibiting FBXW7 on the proliferation and apoptosis of CRC cells. HCT116 cells were transfected with miR-223 mimics or small interfering RNA (siRNA) targeting FBXW7 (siFBXW7), and the effects of these treatments on cell proliferation and apoptosis were examined. The downstream Notch and Akt/mTOR pathways were also assessed. Following miR-223 overexpression, the mRNA and protein expression levels of FBXW7 were downregulated. Transfection with miR-223 mimics or siFBXW7 promoted the proliferation of HCT116 cells and inhibited apoptosis by promoting the Notch and Akt/mTOR signalling pathways. Conversely, miR-223 mimics transfection with FBXW7 overexpression inhibited cell viability and restored apoptosis. Thus, the present study demonstrated that miR-223 could bind to the FBXW7 gene and inhibit its expression, ultimately increasing the proliferation and preventing the apoptosis of CRC cells through the Notch and Akt/mTOR signalling pathways.

Contribution of Autophagy-Notch1-Mediated NLRP3 Inflammasome Activation to Chronic Inflammation and Fibrosis in Keloid Fibroblasts

Keloid is a representative chronic fibroproliferative condition that occurs after tissue injury. Emerging evidence showed that activation of NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome is involved in the pro-inflammatory response in injured tissues. However, the role of NLRP3 inflammasome in keloid progression remains unclear. Notch signaling, which activates NLRP3 inflammasome, is known to contribute to scar formation in keloid, but the cause of enhanced Notch signaling in keloid is not clear. We sought to investigate whether autophagy regulates Notch1 signaling in keloid fibroblasts and determine whether Notch1 signaling might regulate NLRP3 inflammasomes and myofibroblast differentiation. An in vitro model of keloid was established by culturing primary keloid fibroblasts from patients. Expression levels of Notch1, NLRP3 inflammasome proteins, pro-inflammatory cytokines, and myofibroblast markers in keloid fibroblasts were examined and compared with those in normal fibroblasts. Autophagy known to mediate Notch1 degradation was also monitored in fibroblasts. Small interfering RNA (siRNA) targeting Notch1 was used to transfect keloid fibroblasts to further examine the role of Notch signaling in NLRP3 inflammasome activation. Expression levels of Notch1 and NLRP3 inflammasome in keloid fibroblasts increased compared to those in normal fibroblasts. Such increases were accompanied by increased LC3 levels and reduced autophagic flux. Notch1 silencing in keloid fibroblasts by siRNA transfection significantly suppressed increased levels of overall NLRP3 inflammasome complex proteins, NF-kB, and α-smooth muscle actin. Autophagy induction by rapamycin treatment in keloid fibroblasts effectively suppressed expression levels of Notch1 and NLRP3 inflammasome proteins. Decreased autophagy activity in keloid can result in Notch1-mediated myofibroblast activation and NLRP3 inflammasome signaling activation which is critical for chronic inflammation. Collectively, these results identify Notch1 as a novel activator of NLRP3 inflammasome signaling leading to chronic tissue damage and myofibroblast differentiation in keloid progression.

MALT1 Inhibition as a Therapeutic Strategy in T-Cell Acute Lymphoblastic Leukemia by Blocking Notch1-Induced NF-κB Activation

Current treatment of T-cell acute lymphoblastic leukemia (T-ALL) is primarily based on high-intensity combination chemotherapy, which has serious side effects. Therefore, developments of novel targeted therapeutics are urgently needed for treatment of T-ALL. In this study, we found that mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) is a novel promising therapeutic target for treatment of T-ALL. MALT1 inhibitor MI-2 significantly suppressed the cell growth, proliferation, and colony formation of T-ALL cells. Furthermore, MI-2 induced cell apoptosis of T-ALL via a mitochondrial-dependent pathway. In a T-ALL mouse model, MI-2 significantly reduced leukemic burden and prolonged the survival of leukemia-bearing mice. Mechanistically, MALT1 inhibition effectively blocked both baseline and Notch1-induced activation of nuclear factor κB pathway, which mediates T-ALL cell survival. In conclusion, our results highlight the potential role of MALT1 as an attractive target for treatment of T-ALL and support the potential of MI-2 or other MALT1 inhibitors to clinical trials in T-ALL.

Notch in Head and Neck Cancer

Head and neck cancer is a group of neoplastic diseases affecting the facial, oral, and neck region. It is one of the most common cancers worldwide with an aggressive, invasive evolution. Due to the heterogeneity of the tissues affected, it is particularly challenging to study the molecular mechanisms at the basis of these tumors, and to date we are still lacking accurate targets for prevention and therapy. The Notch signaling is involved in a variety of tumorigenic mechanisms, such as regulation of the tumor microenvironment, aberrant intercellular communication, and altered metabolism. Here, we provide an up-to-date review of the role of Notch in head and neck cancer and draw parallels with other types of solid tumors where the Notch pathway plays a crucial role in emergence, maintenance, and progression of the disease. We therefore give a perspective view on the importance of the pathway in neoplastic development in order to define future lines of research and novel therapeutic approaches.

Reduced expression of CYLD promotes cell survival and inflammation in gefitinib-treated NSCLC PC-9 cells: Targeting CYLD may be beneficial for acquired resistance to gefitinib therapy

The application of tyrosine kinase inhibitors (TKIs) to the epidermal growth factor receptor (EGFR) has been proven to be highly effective for non-small-cell lung cancer (NSCLC). However, patients often evolve into acquired resistance. The secondary mutations in EGFR account for nearly half of the acquired resistance. While the remaining 50% of patients exhibit tolerance to EGFR-TKIs with unclear mechanism(s). Cylindromatosis (CYLD), a deubiquitinase, functions as a tumor suppressor to regulate cell apoptosis, proliferation, and immune response, and so on. The role of CYLD in NSCLC EGFR-TKI resistance remains elusive. Here, we found CYLD was upregulated in PC-9 cells, whereas downregulated in PC-9 acquired gefitinib-resistant (PC-9/GR) cells in response to the treatment of gefitinib, which is consistent with the results in the Gene Expression Omnibus database. Overexpression of CYLD promoted a more apoptotic death ratio in PC-9/GR cells than that in PC-9 cells. In addition, silencing the expression of CYLD resulted in an increase of the expression level of interleukin-6, transforming growth factor-β and tumor necrosis factor-α, which may contribute to acquired resistance of PC-9 cells to gefitinib. Taken together, our data in vitro demonstrate that PC-9/GR cells downregulated CYLD expression, enhanced subsequent CYLD-dependent antiapoptotic capacity and inflammatory response, which may provide a possible target for acquired gefitinib-resistant treatment in NSCLC.

NF-κB1 Regulates Immune Environment and Outcome of Notch-Dependent T-Cell Acute Lymphoblastic Leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive pediatric malignancy that arises from the transformation of immature T-cell progenitors and has no definitive cure. Notch signaling governs many steps of T cell development and its dysregulation represents the most common causative event in the pathogenesis of T-ALL. The activation of canonical NF-κB pathway has been described as a critical downstream mediator of Notch oncogenic functions, through the sustaining of tumor cell survival and growth. The potential role of Notch/NF-κB partnership is also emerging in the generation and function of regulatory T cells (Tregs) in the context of cancer. However, little is known about the effects of combined mutations of Notch and NF-κB in regulating immune-environment and progression of T-ALL. To shed light on the topics above we generated double-mutant mice, harboring conventional knock-out mutation of NF-κB1/p50 on the genetic background of a transgenic model of Notch-dependent T-ALL. The immunophenotyping of double-mutant mice demonstrates that NF-κB1 deletion inhibits the progression of T-ALL and strongly modifies immune-environment of the disease. Double-mutant mice display indeed a dramatic reduction of pre-leukemic CD4⁺CD8⁺ (DP) T cells and regulatory T cells (Tregs) and, concurrently, the rising of an aggressive myeloproliferative trait with a massive expansion of CD11b⁺Gr-1⁺ cells in the periphery, and an accumulation of the granulocyte/monocyte progenitors in the bone-marrow. Interestingly, double-mutant T cells are able to improve the growth of CD11b⁺Gr-1⁺ cells in vitro, and, more importantly, the in vivo depletion of T cells in double-mutant mice significantly reduces the expansion of myeloid compartment. Our results strongly suggest that the myeloproliferative trait observed in double-mutant mice may depend on non-cell-autonomous mechanism/s driven by T cells. Moreover, we demonstrate that the reduction of CD4⁺CD8⁺ (DP) T cells and Tregs in double-mutant mice relies on a significant enhancement of their apoptotic rate. In conclusion, double-mutant mice may represent a useful model to deepen the knowledge of the consequences on T-ALL immune-environment of modulating Notch/NF-κB relationships in tumor cells. More importantly, information derived from these studies may help in the refinement of multitarget therapies for the disease.

The Role of Deubiquitinating Enzymes in Hematopoiesis and Hematological Malignancies

Hematopoietic stem cells (HSCs) are responsible for the production of blood cells throughout the human lifespan. Single HSCs can give rise to at least eight distinct blood-cell lineages. Together, hematopoiesis, erythropoiesis, and angiogenesis coordinate several biological processes, i.e., cellular interactions during development and proliferation, guided migration, lineage programming, and reprogramming by transcription factors. Any dysregulation of these processes can result in hematological disorders and/or malignancies. Several studies of the molecular mechanisms governing HSC maintenance have demonstrated that protein regulation by the ubiquitin proteasomal pathway is crucial for normal HSC function. Recent studies have shown that reversal of ubiquitination by deubiquitinating enzymes (DUBs) plays an equally important role in hematopoiesis; however, information regarding the biological function of DUBs is limited. In this review, we focus on recent discoveries about the physiological roles of DUBs in hematopoiesis, erythropoiesis, and angiogenesis and discuss the DUBs associated with common hematological disorders and malignancies, which are potential therapeutic drug targets.

Bladder neoplasms and NF-κB: an unfathomed association

Introduction: Bladder cancer is the second most common genitourinary tract cancer and is often recurrent and/or chemoresistant after tumor resection. Cigarette smoking, exposure to aromatic amines, and chronic infection/inflammation are bladder cancer risk factors. NF-κB is a transcription factor that plays a critical role in normal physiology and bladder cancer. Bladder cancer patients have constitutively active NF-κB triggered by pro-inflammatory cytokines, chemokines, and hypoxia, augmenting carcinogenesis and progression.Areas covered: NF-κB orchestrates protein interactions (PTEN, survivin, VEGF), regulation (CYLD, USP13) and gene expression (Trp 53) resulting in bladder cancer progression, recurrence and resistance to therapy. This review focuses on NF-κB in bladder inflammation, cancer and resistance to therapy.Expert opinion: NF-κB and bladder cancer necessitate further research to develop better diagnostic and treatment regimens that address progression, recurrence and resistance to therapy. NF-κB is a master regulator that can act with or on minimally one cancer hallmark gene or protein, leading to bladder cancer progression (Tp53, PTEN, VEGF, HMGB1, CYLD, USP13), recurrence (PCNA, BcL-2, JUN) and resistance to therapy (P-gp, twist, SETD6). Thus, an understanding of bladder cancer in relation to NF-κB will offer improved strategies and efficacious targeted therapies resulting in minimal progression, recurrence and resistance to therapy.

Three-dimensional chromatin landscapes in T cell acute lymphoblastic leukemia

Differences in three-dimensional (3D) chromatin architecture can influence the integrity of topologically associating domains (TADs) and rewire specific enhancer-promoter interactions, impacting gene expression and leading to human disease. Here we investigate the 3D chromatin architecture in T cell acute lymphoblastic leukemia (T-ALL) by using primary human leukemia specimens and examine the dynamic responses of this architecture to pharmacological agents. Systematic integration of matched in situ Hi-C, RNA-seq and CTCF ChIP-seq datasets revealed widespread differences in intra-TAD chromatin interactions and TAD boundary insulation in T-ALL. Our studies identify and focus on a TAD 'fusion' event associated with absence of CTCF-mediated insulation, enabling direct interactions between the MYC promoter and a distal super-enhancer. Moreover, our data also demonstrate that small-molecule inhibitors targeting either oncogenic signal transduction or epigenetic regulation can alter specific 3D interactions found in leukemia. Overall, our study highlights the impact, complexity and dynamic nature of 3D chromatin architecture in human acute leukemia.

Hes1 deficiency causes hematopoietic stem cell exhaustion

The transcriptional repressor Hairy Enhancer of Split 1 (HES1) plays an essential role in the development of many organs by promoting the maintenance of stem/progenitor cells, controlling the reversibility of cellular quiescence, and regulating both cell fate decisions. Deletion of Hes1 in mice results in severe defects in multiple organs and is lethal in late embryogenesis. Here we have investigated the role of HES1 in hematopoiesis using a hematopoietic lineage‐specific Hes1 knockout mouse model. We found that while Hes1 is dispensable for steady‐state hematopoiesis, Hes1‐deficient hematopoietic stem cells (HSCs) undergo exhaustion under replicative stress. Loss of Hes1 upregulates the expression of genes involved in PPARγ signaling and fatty acid metabolism pathways, and augments fatty acid oxidation (FAO) in Hes1^f/fVav1Cre HSCs and progenitors. Functionally, PPARγ targeting or FAO inhibition ameliorates the repopulating defects of Hes1^f/fVav1Cre HSCs through improving quiescence in HSCs. Lastly, transcriptome analysis reveals that disruption of Hes1 in hematopoietic lineage alters expression of genes critical to HSC function, PPARγ signaling, and fatty acid metabolism. Together, our findings identify a novel role of HES1 in regulating stress hematopoiesis and provide mechanistic insight into the function of HES1 in HSC maintenance.

The Genetics and Mechanisms of T-Cell Acute Lymphoblastic Leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy derived from early T-cell progenitors. The recognition of clinical, genetic, transcriptional, and biological heterogeneity in this disease has already translated into new prognostic biomarkers, improved leukemia animal models, and emerging targeted therapies. This work reviews our current understanding of the molecular mechanisms of T-ALL.

Reversal of CYLD phosphorylation as a novel therapeutic approach for adult T-cell leukemia/lymphoma (ATLL)

Adult T-cell leukemia/lymphoma (ATLL) is a malignancy of mature T cells associated with chronic infection by human T-cell lymphotropic virus type-1 (HTLV-1). ATLL patients with aggressive subtypes have dismal outcomes. We demonstrate that ATLL cells co-opt an early checkpoint within the tumor necrosis factor receptor 1 (TNFR1) pathway, resulting in survival advantage. This early checkpoint revolves around an interaction between the deubiquitinase CYLD and its target RIPK1. The status of RIPK1 K63-ubiquitination determines cell fate by creating either a prosurvival signal (ubiquitinated RIPK1) or a death signal (deubiquitinated RIPK1). In primary ATLL samples and in cell line models, an increased baseline level of CYLD phosphorylation was observed. We therefore tested the hypothesis that this modification of CYLD, which has been reported to inhibit its deubiquitinating function, leads to increased RIPK1 ubiquitination and thus provides a prosurvival signal to ATLL cells. CYLD phosphorylation can be pharmacologically reversed by IKK inhibitors, specifically by TBK1/IKKε and IKKβ inhibitors (MRT67307 and TPCA). Both of the IKK sub-families can phosphorylate CYLD, and the combination of MRT67307 and TPCA have a marked effect in reducing CYLD phosphorylation and triggering cell death. ATLL cells overexpressing a kinase-inactive TBK1 (TBK1-K38A) demonstrate lower CYLD phosphorylation and subsequently reduced proliferation. IKK blockade reactivates CYLD, as evidenced by the reduction in RIPK1 ubiquitination, which leads to the association of RIPK1 with the death-inducing signaling complex (DISC) to trigger cell death. In the absence of CYLD, RIPK1 ubiquitination remains elevated following IKK blockade and it does not associate with the DISC. SMAC mimetics can similarly disrupt CYLD phosphorylation and lead to ATLL cell death through reduction of RIPK1 ubiquitination, which is CYLD dependent. These results identify CYLD as a crucial regulator of ATLL survival and point to its role as a potential novel target for pharmacologic modification in this disease.