Co-inhibition of NF-κB and JNK is synergistic in TNF-expressing human AML

Bone marrow inflammation in haematological malignancies

Tissue inflammation is a hallmark of tumour microenvironments. In the bone marrow, tumour-associated inflammation impacts normal niches for haematopoietic progenitor cells and mature immune cells and supports the outgrowth and survival of malignant cells residing in these niche compartments. This Review provides an overview of our current understanding of inflammatory changes in the bone marrow microenvironment of myeloid and lymphoid malignancies, using acute myeloid leukaemia and multiple myeloma as examples and highlights unique and shared features of inflammation in niches for progenitor cells and plasma cells. Importantly, inflammation exerts profoundly different effects on normal bone marrow niches in these malignancies, and we provide context for possible drivers of these divergent effects. We explore the role of tumour cells in inflammatory changes, as well as the role of cellular constituents of normal bone marrow niches, including myeloid cells and stromal cells. Integrating knowledge of disease-specific dynamics of malignancy-associated bone marrow inflammation will provide a necessary framework for future targeting of these processes to improve patient outcome.

Distinct roles of hematopoietic cytokines in the regulation of leukemia stem cells in murine MLL-AF9 leukemia

Lymphoid-primed multipotent progenitor (LMPP)-like and granulocyte-monocyte progenitor (GMP)-like leukemia stem cells (LSCs) co-exist in the blood of most patients with acute myeloid leukemia (AML). Complete elimination of both types of LSCs is required to cure AML. Using an MLL-AF9-induced murine AML model, we studied the role of hematopoietic cytokines in the survival of LMPP- and GMP-like LSCs. We found that SCF or FLT3L promotes the survival of LMPP-like LSCs by stimulating Stat5-mediated Mcl1 expression, whereas interleukin-3 (IL-3) or IL-6 induces the survival of GMP-like LSCs by stimulating Stat3/nuclear factor κB (NF-κB)-mediated Bcl2 expression. Functional study demonstrated that, compared to AML cells cultured in IL-3 and IL-6 medium, AML cells in SCF- or Flt3L-only culture are highly clonogenic in in vitro culture and are highly leukemogenic in vivo. Our study suggests that co-inhibition of both STAT5-MCL1 and STAT3/NF-κB-BCL2 signaling might represent an improved treatment strategy against AML, specifically AML cases with a monocytic phenotype and/or FLT3 mutations.

Complementary and countervailing actions of Jak2 and Ikk2 in hematopoiesis in mice

Hyperactivation of JAK2 kinase is a unifying feature of human Ph- myeloproliferative neoplasms (MPNs), most commonly due to the JAK2 V617F mutation. Mice harboring a homologous mutation in the Jak2 locus exhibit a phenotype resembling polycythemia vera. NFκB pathway hyperactivation is present in myeloid neoplasms, including MPNs, despite scarcity of mutations in NFκB pathway genes. To determine the impact of NFκB pathway hyperactivation in conjunction with Jak2 V617F, we utilized Ikk2 (Ikk2-CA) mice. Pan-hematopoietic Ikk2-CA alone produced depletion of hematopoietic stem cells and B cells. When combined with the Jak2 V617F mutation, Ikk2-CA rescued the polycythemia vera phenotype of Jak2 V617F. Likewise, Jak2 V617F ameliorated defects in hematopoiesis produced by Ikk2-CA. Single-cell RNA sequencing of hematopoietic stem and progenitor cells revealed multiple genes antagonistically regulated by Jak2 and Ikk2, including subsets whose expression was altered by Jak2 V617F and/or Ikk2-CA but partly or fully rectified in the double mutant. We hypothesize that Jak2 promotes hematopoietic stem cell population self-renewal, whereas Ikk2 promotes myeloid lineage differentiation, and biases cell fates at several branch points in hematopoiesis. Jak2 and Ikk2 both regulate multiple genes affecting myeloid maturation and cell death. Therefore, the presence of dual Jak2 and NFκB hyperactivation may present neomorphic therapeutic vulnerabilities in myeloid neoplasms.

Molecular characterization and expression analyses of five genes involved in the MyD88-dependent pathway of yellow catfish (Pelteobagrus fulvidraco) responding to challenge of Aeromonas hydrophila

MyD88-dependent pathway mediated by Toll-like receptor is one of the vital ways activating immune responses. In order to identify the role of MyD88-dependent signaling pathway in yellow catfish, the Pf_MyD88, Pf_IRAK4, Pf_IRAK1, Pf_TRAF6 and Pf_NFκB1 (p105) (Pf: abbreviation of Pelteobagrus fulvidraco) were cloned and characterized respectively. The Pf_MyD88, Pf_IRAK4, Pf_IRAK1 and Pf_TRAF6 were all highly conserved among species and showed the highest homology to that of Pangasianodon hypophthalmus. Pf_NFκB1 showed the highest homology to that of Ictalurus punetaus. All of the five genes showed similar expression patterns in various tissues, with the highest expression level in the liver. These genes also showed similar expression levels in different embryonic development stages, except Pf_IRAK4. The higher expression level was detected from fertilized eggs to 1 day post hatching (dph), lower expression from 3 dph to 30 dph. After stimulation of inactivated Aeromonas hydrophila, the mRNA expressions of Pf_MyD88, Pf_IRAK4, Pf_IRAK1, Pf_TRAF6 and Pf_NFκB1 were significantly increased at 24 h in the liver, spleen, head kidney and trunk kidney, suggesting that all the five genes were involved in the innate immune response of yellow catfish. These results showed that MyD88-dependent signaling pathway plays important roles for disease defensing in the innate immune response. Meanwhile, inactivated A. hydrophila can cause strong innate immune response, which provides theoretical bases for the application of inactivated vaccines in defense against bacterial diseases of teleost.

Influence of cytokines on early death and coagulopathy in newly diagnosed patients with acute promyelocytic leukemia

Introduction

Acute promyelocytic leukemia (APL) is a subtype of acute myeloid leukemia (AML) with a better prognosis. But early death (ED) rate remains high. APL patients are simultaneously accompanied by coagulopathy and hyperinflammation at the onset. It is not known what effects cytokines have on ED and coagulopathy in these patients. Therefore, the purposes of this study are to explore the clinical differences between APL and other types of AML, the link between cytokines and coagulopathy in newly diagnosed APL, and their roles in the ED for APL.

Methods

This study retrospectively collected the information of 496 adult patients with AML (age ≥14 years at admission) newly diagnosed in the First People's Hospital of Yunnan Province between January 2017 to February 2022, including 115 APL patients. The difference of clinical manifestations between two groups [APL and AML (non-APL)] was statistically analyzed. Then, the factors affecting ED in APL patients were screened, and the possible pathways of their influence on ED were further analyzed.

Results

The results indicate APL at the onset have a younger age and higher incidence of ED and DIC than other types of AML. Intracranial hemorrhage (ICH), age, and PLT count are found to be independent factors for ED in newly APL, among which ICH is the main cause of ED, accounting for 61.54% (8/13). The levels of cytokines in newly APL are generally higher than that in AML (non-APL), and those in the group of ED for APL were widely more than the control group. IL-17A and TNF-β are directly related to the ED in newly APL, especially IL-17A, which also affects ICH in these patients. Moreover, the increase of IL-17A and TNF-β cause the prolongation of PT in APL patients, which reflected the exogenous coagulation pathway. However, they have no effect on APTT prolongation and FIB reduction. Thus, it is speculated that IL-17A leads to early cerebral hemorrhage death in newly APL by inducing tissue factor (TF) overexpression to initiate exogenous coagulation and further leading to excessive depletion of clotting factors and prolongation of PT.

Conclusions

In conclusion, compared with other types of AML, APL patients have a younger age of onset and high inflammatory state, and are more likely to develop into DIC and die early. Age, and PLT count at diagnosis are independent factors for ED of APL, especially ICH. IL-17A is confirmed to be an independent risk factor for ED and ICH of newly APL. Hence, IL-17A may serve as a predictor of ED in newly diagnosed APL patients, and controlling its expression probably reduce ED in these patients.

Anti-inflammatory effects of extracellular vesicles from Morchella on LPS-stimulated RAW264.7 cells via the ROS-mediated p38 MAPK signaling pathway

Morchella is a kind of important edible and medicinal fungi, which is rich in polysaccharides, enzymes, fatty acids, amino acids and other active components. Extracellular vesicles (EVs) have a typical membrane structure, and the vesicles contain some specific lipids, miRNAs and proteins, and their can deliver the contents to different cells to change their functions. The present study investigated whether Morchella produce extracellular vesicles and its anti-inflammatory effect on lipopolysaccharide (LPS)-induced RAW246.7 macrophages. The experimental results showed that Morchella produced extracellular vesicles and significantly reduced the production of nitric oxide (NO) and reactive oxygen species (ROS) in a model of LPS-induced inflammation. In addition, the expression of inflammatory factor-related genes such as inducible nitric oxide synthase (iNOS), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and cyclooxygenase-2 (COX-2) showed dose-dependent inhibition. Morchella extracellular vesicles also can inhibit the inflammatory response induced by LPS by inhibiting the production of ROS and reducing the phosphorylation levels of the p38 MAPK signaling pathway. These results indicate that the Morchella extracellular vesicles can be used as a potential anti-inflammatory substance in the treatment of inflammatory diseases.

Real-Time Characterization of Clonal Fate Decisions in Complex Leukemia Samples by Fluorescent Genetic Barcoding

Clonal heterogeneity in acute myeloid leukemia (AML) forms the basis for treatment failure and relapse. Attempts to decipher clonal evolution and clonal competition primarily depend on deep sequencing approaches. However, this prevents the experimental confirmation of the identified disease-relevant traits on the same cell material. Here, we describe the development and application of a complex fluorescent genetic barcoding (cFGB) lentiviral vector system for the labeling and subsequent multiplex tracking of up to 48 viable AML clones by flow cytometry. This approach allowed the visualization of longitudinal changes in the in vitro growth behavior of multiplexed color-coded AML clones for up to 137 days. Functional studies of flow cytometry-enriched clones documented their stably inherited increase in competitiveness, despite the absence of growth-promoting mutations in exome sequencing data. Transplantation of aliquots of a color-coded AML cell mix into mice revealed the initial engraftment of similar clones and their subsequent differential distribution in the animals over time. Targeted RNA-sequencing of paired pre-malignant and de novo expanded clones linked gene sets associated with Myc-targets, embryonic stem cells, and RAS signaling to the foundation of clonal expansion. These results demonstrate the potency of cFGB-mediated clonal tracking for the deconvolution of verifiable driver-mechanisms underlying clonal selection in leukemia.

Predictive values of plasma TNFα and IL-8 for intracranial hemorrhage in patients with acute promyelocytic leukemia

In patients with acute promyelocytic leukemia (APL), intracranial hemorrhage (ICH), if not identified promptly, could be fatal. It is the leading cause of failure of induction and early death. Thus, biomarkers that could promptly predict severe complications are critical. Here, cytokine differences between patients with APL with and without ICH were investigated to develop predictive models for this complication. The initial cytokine profiling using plasma samples from 39 patients and 18 healthy donors found a series of cytokines that were remarkedly different between patients with APL and healthy controls. The APL patients were subsequently divided into high and low white blood cell count groups. Results showed that tumor necrosis factor a and interleukin 8 (IL-8) were vital in distinguishing patients with APL who did or did not develop ICH. In addition, verification in 81 patients with APL demonstrated that the two cytokines were positively correlated with the cumulative incidence of ICH. Finally, in-vitro and in-vivo experimental evidence were provided to show that IL-8 influenced the migration of APL-derived NB4 cells and impaired the blood-brain barrier in PML/RARα positive blast-transplanted FVB/NJ mice. These assessments may facilitate the early warning of ICH and reduce future mortality levels in APL.

NF-κB: A Druggable Target in Acute Myeloid Leukemia

Simple Summary

AML is a highly heterogeneous hematological disease and is the second most common form of leukemia. Around 40% of AML patients display elevated nuclear NF-κB activity, providing a compelling rationale for targeting the NF-κB pathway in AML. Here we summarize the main drivers of the NF-κB pathway in AML pathogenesis as well as the conventional and novel therapeutic strategies targeting NF-κB to improve the survival of AML patients.

Abstract

Acute Myeloid Leukemia (AML) is an aggressive hematological malignancy that relies on highly heterogeneous cytogenetic alterations. Although in the last few years new agents have been developed for AML treatment, the overall survival prospects for AML patients are still gloomy and new therapeutic options are still urgently needed. Constitutive NF-κB activation has been reported in around 40% of AML patients, where it sustains AML cell survival and chemoresistance. Given the central role of NF-κB in AML, targeting the NF-κB pathway represents an attractive strategy to treat AML. This review focuses on current knowledge of NF-κB’s roles in AML pathogenesis and summarizes the main therapeutic approaches used to treat NF-κB-driven AML.

Tumor Necrosis Factor Receptor 2 (TNFR2): An Emerging Target in Cancer Therapy

Despite the great success of TNF blockers in the treatment of autoimmune diseases and the identification of TNF as a factor that influences the development of tumors in many ways, the role of TNFR2 in tumor biology and its potential suitability as a therapeutic target in cancer therapy have long been underestimated. This has been fundamentally changed with the identification of TNFR2 as a regulatory T-cell (Treg)-stimulating factor and the general clinical breakthrough of immunotherapeutic approaches. However, considering TNFR2 as a sole immunosuppressive factor in the tumor microenvironment does not go far enough. TNFR2 can also co-stimulate CD8⁺ T-cells, sensitize some immune and tumor cells to the cytotoxic effects of TNFR1 and/or acts as an oncogene. In view of the wide range of cancer-associated TNFR2 activities, it is not surprising that both antagonists and agonists of TNFR2 are considered for tumor therapy and have indeed shown overwhelming anti-tumor activity in preclinical studies. Based on a brief summary of TNFR2 signaling and the immunoregulatory functions of TNFR2, we discuss here the main preclinical findings and insights gained with TNFR2 agonists and antagonists. In particular, we address the question of which TNFR2-associated molecular and cellular mechanisms underlie the observed anti-tumoral activities of TNFR2 agonists and antagonists.

Integrative genomic analysis of a novel small nucleolar RNAs prognostic signature in patients with acute myelocytic leukemia

This study mainly used The Cancer Genome Atlas (TCGA) RNA sequencing dataset to screen prognostic snoRNAs of acute myeloid leukemia (AML), and used for the construction of prognostic snoRNAs signature for AML. A total of 130 AML patients with RNA sequencing dataset were used for prognostic snoRNAs screenning. SnoRNAs co-expressed genes and differentially expressed genes (DEGs) were used for functional annotation, as well as gene set enrichment analysis (GSEA). Connectivity Map (CMap) also used for potential targeted drugs screening. Through genome-wide screening, we identified 30 snoRNAs that were significantly associated with the prognosis of AML. Then we used the step function to screen a prognostic signature composed of 14 snoRNAs (SNORD72, SNORD38, U3, SNORA73B, SNORD79, SNORA73, SNORD12B, SNORA74, SNORD116-12, SNORA65, SNORA14, snoU13, SNORA75, SNORA31), which can significantly divide AML patients into high- and low-risk groups. Through GSEA, snoRNAs co-expressed genes and DEGs functional enrichment analysis, we screened a large number of potential functional mechanisms of this prognostic signature in AML, such as phosphatidylinositol 3-kinase-Akt, Wnt, epithelial to mesenchymal transition, T cell receptors, NF-kappa B, mTOR and other classic cancer-related signaling pathways. In the subsequent targeted drug screening using CMap, we also identified six drugs that can be used for AML targeted therapy, they were alimemazine, MG-262, fluoxetine, quipazine, naltrexone and oxybenzone. In conclusion, our current study was constructed an AML prognostic signature based on the 14 prognostic snoRNAs, which may serve as a novel prognostic biomarker for AML.

Inflammatory Cytokines Shape an Altered Immune Response During Myeloid Malignancies

The immune microenvironment is a critical driver and regulator of leukemic progression and hematological disease. Recent investigations have demonstrated that multiple immune components play a central role in regulating hematopoiesis, and dysfunction at the immune cell level significantly contributes to neoplastic disease. Immune cells are acutely sensitive to remodeling by leukemic inflammatory cytokine exposure. Importantly, immune cells are the principal cytokine producers in the hematopoietic system, representing an untapped frontier for clinical interventions. Due to a proinflammatory cytokine environment, dysregulation of immune cell states is a hallmark of hematological disease and neoplasia. Malignant immune adaptations have profound effects on leukemic blast proliferation, disease propagation, and drug-resistance. Conversely, targeting the immune landscape to restore hematopoietic function and limit leukemic expansion may have significant therapeutic value. Despite the fundamental role of the immune microenvironment during the initiation, progression, and treatment response of hematological disease, a detailed examination of how leukemic cytokines alter immune cells to permit, promote, or inhibit leukemia growth is lacking. Here we outline an immune-based model of leukemic transformation and highlight how the profound effect of immune alterations on the trajectory of malignancy. The focus of this review is to summarize current knowledge about the impacts of pro- and anti-inflammatory cytokines on immune cells subsets, their modes of action, and immunotherapeutic approaches with the potential to improve clinical outcomes for patients suffering from hematological myeloid malignancies.

Relish plays a dynamic role in the niche to modulate Drosophila blood progenitor homeostasis in development and infection

Immune challenges demand the gearing up of basal hematopoiesis to combat infection. Little is known about how during development, this switch is achieved to take care of the insult. Here, we show that the hematopoietic niche of the larval lymph gland of Drosophila senses immune challenge and reacts to it quickly through the nuclear factor-κB (NF-κB), Relish, a component of the immune deficiency (Imd) pathway. During development, Relish is triggered by ecdysone signaling in the hematopoietic niche to maintain the blood progenitors. Loss of Relish causes an alteration in the cytoskeletal architecture of the niche cells in a Jun Kinase-dependent manner, resulting in the trapping of Hh implicated in progenitor maintenance. Notably, during infection, downregulation of Relish in the niche tilts the maintenance program toward precocious differentiation, thereby bolstering the cellular arm of the immune response.

Inflammatory Pathophysiology as a Contributor to Myeloproliferative Neoplasms

Myeloid neoplasms, including acute myeloid leukemia (AML), myeloproliferative neoplasms (MPNs), and myelodysplastic syndromes (MDS), feature clonal dominance and remodeling of the bone marrow niche in a manner that promotes malignant over non-malignant hematopoiesis. This take-over of hematopoiesis by the malignant clone is hypothesized to include hyperactivation of inflammatory signaling and overproduction of inflammatory cytokines. In the Ph-negative MPNs, inflammatory cytokines are considered to be responsible for a highly deleterious pathophysiologic process: the phenotypic transformation of polycythemia vera (PV) or essential thrombocythemia (ET) to secondary myelofibrosis (MF), and the equivalent emergence of primary myelofibrosis (PMF). Bone marrow fibrosis itself is thought to be mediated heavily by the cytokine TGF-β, and possibly other cytokines produced as a result of hyperactivated JAK2 kinase in the malignant clone. MF also features extramedullary hematopoiesis and progression to bone marrow failure, both of which may be mediated in part by responses to cytokines. In MF, elevated levels of individual cytokines in plasma are adverse prognostic indicators: elevated IL-8/CXCL8, in particular, predicts risk of transformation of MF to secondary AML (sAML). Tumor necrosis factor (TNF, also known as TNFα), may underlie malignant clonal dominance, based on results from mouse models. Human PV and ET, as well as MF, harbor overproduction of multiple cytokines, above what is observed in normal aging, which can lead to cellular signaling abnormalities separate from those directly mediated by hyperactivated JAK2 or MPL kinases. Evidence that NFκB pathway signaling is frequently hyperactivated in a pan-hematopoietic pattern in MPNs, including in cells outside the malignant clone, emphasizes that MPNs are pan-hematopoietic diseases, which remodel the bone marrow milieu to favor persistence of the malignancy. Clinical evidence that JAK2 inhibition by ruxolitinib in MF neither reliably reduces malignant clonal burden nor eliminates cytokine elevations, suggests targeting cytokine mediated signaling as a therapeutic strategy, which is being pursued in new clinical trials. Greater knowledge of inflammatory pathophysiology in MPNs can therefore contribute to the development of more effective therapy.

Pathogenic and therapeutic roles of cytokines in acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous disease with high mortality that accounts for the most common acute leukemia in adults. Despite all progress in the therapeutic strategies and increased rate of complete remission, many patients will eventually relapse and die from the disease. Cytokines as molecular messengers play a pivotal role in the immune system. The imbalance release of cytokine has been shown to exert a significant influence on the progression of hematopoietic malignancies including acute myeloid leukemia. This article aimed to summarize current knowledge about cytokines and their critical roles in the pathogenesis, treatment, and survival of AML patients.

Cell signaling pathways as molecular targets to eliminate AML stem cells

Acute myeloid leukemia (AML) remains the most lethal of leukemias and a small population of cells called leukemic stem cells (LSCs) has been associated with disease relapses. Some cell signaling pathways play an important role in AML survival, proliferation and self-renewal properties and are abnormally activated or suppressed in LSCs. This includes the NF-κB, Wnt/β-catenin, Hedgehog, Notch, EGFR, JAK/STAT, PI3K/AKT/mTOR, TGF/SMAD and PPAR pathways. This review aimed to discuss these pathways as molecular targets for eliminating AML LSCs. Herein, inhibitors/activators of these pathways were summarized as a potential new anti-AML therapy capable of eliminating LSCs to guide future researches. The clinical use of cell signaling pathways data can be useful to enhance the anti-AML therapy.

Clinical Implications of Inflammation in Acute Myeloid Leukemia

Recent advances in the description of the tumor microenvironment of acute myeloid leukemia, including the comprehensive analysis of the leukemic stem cell niche and clonal evolution, indicate that inflammation may play a major role in many aspects of acute myeloid leukemia (AML) such as disease progression, chemoresistance, and myelosuppression. Studies on the mechanisms of resistance to chemotherapy or tyrosine kinase inhibitors along with high-throughput drug screening have underpinned the potential role of glucocorticoids in this disease classically described as steroid-resistant in contrast to acute lymphoblastic leukemia. Moreover, some mutated oncogenes such as RUNX1, NPM1, or SRSF2 transcriptionally modulate cell state in a manner that primes leukemic cells for glucocorticoid sensitivity. In clinical practice, inflammatory markers such as serum ferritin or IL-6 have a strong prognostic impact and may directly affect disease progression, whereas interesting preliminary data suggested that dexamethasone may improve the outcome for AML patients with a high white blood cell count, which paves the way to develop prospective clinical trials that evaluate the role of glucocorticoids in AML.

Insights into the mechanism of Arnebia euchroma on leukemia via network pharmacology approach

BACKGROUND

Arnebia euchroma (A. euchroma) is a traditional Chinese medicine (TCM) used for the treatment of blood diseases including leukemia. In recent years, many studies have been conducted on the anti-tumor effect of shikonin and its derivatives, the major active components of A. euchroma. However, the underlying mechanism of action (MoA) for all the components of A. euchroma on leukemia has not been explored systematically.

METHODS

In this study, we analyzed the MoA of A. euchroma on leukemia via network pharmacology approach. Firstly, the chemical components and their concentrations in A. euchroma as well as leukemia-related targets were collected. Next, we predicted compound-target interactions (CTIs) with our balanced substructure-drug-target network-based inference (bSDTNBI) method. The known and predicted targets of A. euchroma and leukemia-related targets were merged together to construct A. euchroma-leukemia protein-protein interactions (PPIs) network. Then, weighted compound-target bipartite network was constructed according to combination of eight central attributes with concentration information through Cytoscape. Additionally, molecular docking simulation was performed to calculate whether the components and predicted targets have interactions or not.

RESULTS

A total of 65 components of A. euchroma were obtained and 27 of them with concentration information, which were involved in 157 targets and 779 compound-target interactions (CTIs). Following the calculation of eight central attributes of targets in A. euchroma-leukemia PPI network, 37 targets with all central attributes greater than the median values were selected to construct the weighted compound-target bipartite network and do the KEGG pathway analysis. We found that A. euchroma candidate targets were significantly associated with several apoptosis and inflammation-related biological pathways, such as MAPK signaling, PI3K-Akt signaling, IL-17 signaling, and T cell receptor signaling pathways. Moreover, molecular docking simulation demonstrated that there were eight pairs of predicted CTIs had the strong binding free energy.

CONCLUSIONS

This study deciphered that the efficacy of A. euchroma in the treatment of leukemia might be attributed to 10 targets and 14 components, which were associated with inhibiting leukemia cell survival and inducing apoptosis, relieving inflammatory environment and inhibiting angiogenesis.

Inhibition of NF-κB Signaling Alters Acute Myelogenous Leukemia Cell Transcriptomics

Acute myelogenous leukemia (AML) is an aggressive hematological malignancy. The pathophysiology of the disease depends on cytogenetic abnormalities, gene mutations, aberrant gene expressions, and altered epigenetic regulation. Although new pharmacological agents have emerged during the last years, the prognosis is still dismal and new therapeutic strategies are needed. The transcription factor nuclear factor-κB (NF-κB) is regarded a possible therapeutic target. In this study, we investigated the alterations in the global gene expression profile (GEP) in primary AML cells derived from 16 consecutive patients after exposure to the NF-κB inhibitor BMS-345541. We identified a profound and highly discriminative transcriptomic profile associated with NF-κB inhibition. Bioinformatical analyses identified cytokine/interleukin signaling, metabolic regulation, and nucleic acid binding/transcription among the major biological functions influenced by NF-κB inhibition. Furthermore, several key genes involved in leukemogenesis, among them RUNX1 and CEBPA, in addition to NFKB1 itself, were influenced by NF-κB inhibition. Finally, we identified a significant impact of NF-κB inhibition on the expression of genes included in a leukemic stem cell (LSC) signature, indicating possible targeting of LSCs. We conclude that NF-κB inhibition significantly altered the expression of genes central to the leukemic process.

Targeting Actomyosin Contractility Suppresses Malignant Phenotypes of Acute Myeloid Leukemia Cells

Actomyosin-mediated contractility is required for the majority of force-driven cellular events such as cell division, adhesion, and migration. Under pathological conditions, the role of actomyosin contractility in malignant phenotypes of various solid tumors has been extensively discussed, but the pathophysiological relevance in hematopoietic malignancies has yet to be elucidated. In this study, we found enhanced actomyosin contractility in diverse acute myeloid leukemia (AML) cell lines represented by highly expressed non-muscle myosin heavy chain A (NMIIA) and increased phosphorylation of the myosin regulatory light chain. Genetic and pharmacological inhibition of actomyosin contractility induced multivalent malignancy- suppressive effects in AML cells. In this context, perturbed actomyosin contractility enhances AML cell apoptosis through cytokinesis failure and aryl hydrocarbon receptor activation. Moreover, leukemic oncogenes were downregulated by the YAP/TAZ-mediated mechanotransduction pathway. Our results provide a theoretical background for targeting actomyosin contractility to suppress the malignancy of AML cells.

Endothelial E-selectin inhibition improves acute myeloid leukaemia therapy by disrupting vascular niche-mediated chemoresistance

The endothelial cell adhesion molecule E-selectin is a key component of the bone marrow hematopoietic stem cell (HSC) vascular niche regulating balance between HSC self-renewal and commitment. We now report in contrast, E-selectin directly triggers signaling pathways that promote malignant cell survival and regeneration. Using acute myeloid leukemia (AML) mouse models, we show AML blasts release inflammatory mediators that upregulate endothelial niche E-selectin expression. Alterations in cell-surface glycosylation associated with oncogenesis enhances AML blast binding to E-selectin and enable promotion of pro-survival signaling through AKT/NF-κB pathways. In vivo AML blasts with highest E-selectin binding potential are 12-fold more likely to survive chemotherapy and main contributors to disease relapse. Absence (in Sele^−/− hosts) or therapeutic blockade of E-selectin using small molecule mimetic GMI-1271/Uproleselan effectively inhibits this niche-mediated pro-survival signaling, dampens AML blast regeneration, and strongly synergizes with chemotherapy, doubling the duration of mouse survival over chemotherapy alone, whilst protecting endogenous HSC.

The cell adhesion molecule E-selectin regulates haematopoietic stem cell self-renewal in the bone marrow vascular niche. Here, the authors show E-selectin adhesion directly induces survival signaling in acute myeloid leukaemia and therapeutic inhibition improves chemotherapy outcomes in mice.

Coactivation of NF-κB and Notch signaling is sufficient to induce B-cell transformation and enables B-myeloid conversion

NF-κB and Notch signaling can be simultaneously activated in a variety of B-cell lymphomas. Patients with B-cell lymphoma occasionally develop clonally related myeloid tumors with poor prognosis. Whether concurrent activation of both pathways is sufficient to induce B-cell transformation and whether the signaling initiates B-myeloid conversion in a pathological context are largely unknown. Here, we provide genetic evidence that concurrent activation of NF-κB and Notch signaling in committed B cells is sufficient to induce B-cell lymphomatous transformation and primes common progenitor cells to convert to myeloid lineage through dedifferentiation, not transdifferentiation. Intriguingly, the converted myeloid cells can further transform, albeit at low frequency, into myeloid leukemia. Mechanistically, coactivation of NF-κB and Notch signaling endows committed B cells with the ability to self renew. Downregulation of BACH2, a lymphoma and myeloid gene suppressor, but not upregulation of CEBPα and/or downregulation of B-cell transcription factors, is an early event in both B-cell transformation and myeloid conversion. Interestingly, a DNA hypomethylating drug not only effectively eliminated the converted myeloid leukemia cells, but also restored the expression of green fluorescent protein, which had been lost in converted myeloid leukemia cells. Collectively, our results suggest that targeting NF-κB and Notch signaling will not only improve lymphoma treatment, but also prevent the lymphoma-to-myeloid tumor conversion. Importantly, DNA hypomethylating drugs might efficiently treat these converted myeloid neoplasms.

Cryptotanshinone from Salvia miltiorrhiza Bunge (Danshen) inhibited inflammatory responses via TLR4/MyD88 signaling pathway

Background

Cryptotanshinone (CPT), as a major component of Salvia miltiorrhiza Bunge (Danshen), displays many pharmacological activities including anti-inflammatory effects. However, the exact cellular and molecular mechanisms of the anti-inflammatory activities of CPT remain to be elucidated. The present study was aimed to clarify its mechanisms on lipopolysaccharide (LPS)-induced inflammatory responses in mouse macrophages, RAW264.7 cells.

Methods

In the current study, the anti-inflammatory properties of CPT were evaluated using LPS-stimulated RAW264.7 cell model. MTT assay was used to determine the viability of RAW264.7 cells. The anti-inflammatory effects of CPT were measured based on the detection of nitric oxide (NO) production (Griess and flow cytometry assay), and tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) release (ELISA). Cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) enzyme expressions were also determined by western blotting. Besides, by using flow cytometry, we also evaluated the effect of CPT on LPS-induced calcium influx. Finally, the underlying anti-inflammatory mechanisms of CPT were investigated using western blotting to assess the protein levels of toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), phosphatidylinositol 3-kinase (PI3K)/AKT, nuclear factor erythroid 2 related factor 2 (Nrf2), mitogen-activated protein kinase (MAPK), and nuclear factor-kappa B (NF-κB) pathways.

Results

Our data showed that CPT inhibited LPS-induced pro-inflammatory cytokine release like IL-6, and TNF-α, as well as NO production. It displayed a significant inhibitory effect on the protein expressions such as iNOS, COX-2, NF-κB pathway like inhibitor of kappa B kinase (IKK)α/β, inhibitor of kappa B (IκB)-α and NF-κB/p65, PI3K/AKT pathway like PI3K and AKT, and MAPK pathway like c-Jun N-terminal kinase (JNK)1/2, extracellular signal-regulated kinase (ERK)1/2, and p38, in LPS-stimulated RAW264.7 macrophages. Moreover, the immunofluorescence results indicated that CPT suppressed NF-κB/p65 translocation from the cytoplasm into the nucleus. Further investigations showed that CPT treatment increased NAD(P)H quinone oxidoreductase-1 (NQO1) and heme oxygenase-1 (HO-1) expressions together with its upstream mediator, Nrf2. In addition, CPT inhibited LPS-induced toll-like receptor 4 (TLR4) and MyD88 expressions in RAW264.7 macrophages.

Conclusions

Collectively, we suggested that CPT exerted significant anti-inflammatory effects via modulating TLR4-MyD88/PI3K/Nrf2 and TLR4-MyD88/NF-κB/MAPK pathways.

THBS1 Is a Novel Serum Prognostic Factors of Acute Myeloid Leukemia

Dysregulation of cytokines and growth factors is a general feature of tumor microenvironment, and unraveling the expression spectrum of cytokine and growth factor in niche is of utmost importance. Here, we evaluated cytokine profiling of bone marrow serum samples in AML patients and healthy controls. Protein expression profiling of serum from nine AML patients and five healthy controls was obtained using a biotinylated antibody chip. A total of 507 cytokines and growth factors were analyzed. Compared with healthy people, AML patients expressed 31 signature proteins, among which, 27 were significantly higher expressed and 4 proteins were lower. When patients were divided into favorable and poor prognosis, 12 signature proteins were significantly differentially expressed between these two groups. Furthermore, in order to identify the accuracy of cytokine expression profiles, we verified and analyzed the expression of THBS1 (Thrombospondin 1) in 116 patients and 9 healthy people. We found that THBS1 was lowly expressed in AML patients, which might be induced by promoter methylation, and patients with low THBS1 possessed shorter survivor time. Our data indicated that we successfully unveil differentially expressed proteins in AML patients using a biotinylated antibody chip; among them, THBS1 may be a potential therapeutic target for AML patients' treatment.

Anti-inflammatory effects of Aureusidin in LPS-stimulated RAW264.7 macrophages via suppressing NF-κB and activating ROS- and MAPKs-dependent Nrf2/HO-1 signaling pathways

Aureusidin, a naturally-occurring flavonoid, is found in various plants of Cyperaceae such as Heleocharis dulcis (Burm. f.) Trin., but its pharmacological effect and active mechanism are rarely reported. This study aimed to investigate the anti-inflammatory effect and action mechanism of Aureusidin in LPS-induced mouse macrophage RAW264.7 cells. The results suggested that lipopolysaccharide (LPS)-induced nitric oxide (NO), tumor necrosis factor-α (TNF-α) and prostaglandin E2 (PGE2) production were obviously inhibited by Aureusidin. Moreover, Aureusidin also significantly decreased the mRNA expression of various inflammatory factors in LPS-stimulated RAW264.7 cells. Furthermore, mechanistic studies showed that Aureusidin significantly inhibited nuclear transfer of nuclear factor-κB (NF-κB), while increasing the nuclear translocation of nuclear factor E2-related factor 2 (Nrf2) as well as expression of Nrf2 target genes such as heme oxygenase (HO-1) and NAD(P)H:quinone oxidoreductase 1 (NQO1), but the addition of the HO-1 inhibitor Sn-protoporphyrin (Snpp) significantly abolished the anti-inflammatory effect of Aureusidin in LPS-stimulated RAW264.7 cells, confirming the view that HO-1 was involved in the anti-inflammatory effect. In addition, Aureusidin increased the levels of reactive oxygen species (ROS) and mitogen-activated protein kinase (MAPK) phosphorylation in RAW264.7 cells. Antioxidant N-acetylcysteine (NAC) or three MAPK inhibitors blocked the nuclear translocation of Nrf2 and HO-1 expression induced by Aureusidin, indicating that Aureusidin activated the Nrf2/HO-1 signaling pathway through ROS and MAPKs pathways. At the same time, co-treatment with the NAC blocked the phosphorylation of MAPKs. Results from molecular docking indicated that Aureusidin inhibited the NF-κB pathway by covalently binding to NF-κB. Thus, Aureusidin exerted the anti-inflammatory activity through blocking the NF-κB signaling pathways and activating the MAPKs and Nrf2/HO-1 signaling pathways. Based on the above results, Aureusidin may be an attractive therapeutic candidate for the inflammation-related diseases.

Guidelines for the use of flow cytometry and cell sorting in immunological studies (second edition)

These guidelines are a consensus work of a considerable number of members of the immunology and flow cytometry community. They provide the theory and key practical aspects of flow cytometry enabling immunologists to avoid the common errors that often undermine immunological data. Notably, there are comprehensive sections of all major immune cell types with helpful Tables detailing phenotypes in murine and human cells. The latest flow cytometry techniques and applications are also described, featuring examples of the data that can be generated and, importantly, how the data can be analysed. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid, all written and peer-reviewed by leading experts in the field, making this an essential research companion.

Elevated SH3BP5 Correlates with Poor Outcome and Contributes to the Growth of Acute Myeloid Leukemia Cells

Current strategies are not especially successful in the treatment of acute myeloid leukemia (AML). The identification and characterization of oncogenes crucial to the survival and growth of leukemia cells will provide potential targets for the exploitation of novel therapies. Herein, we report that the elevated expression of SH3 domain-binding protein 5 (SH3BP5) significantly correlates with poor outcomes of AML patients. To test whether SH3BP5 contributes to the growth and survival of AML cells, we use the shRNA-encoding lentivirus system to achieve the knockdown of SH3BP5 expression in human AML cell lines U937, THP-1, Kasumi-1, and MV4-11. Functionally, the knockdown of SH3BP5 expression markedly inhibits the cell viability and induced apoptosis of these leukemia cells. Mechanistically, western blot analysis indicates that the knockdown of SH3BP5 expression decreases the phosphorylation of JNK and BAD. Moreover, the JNK agonist anisomycin rescues the growth inhibition phenotype of SH3BP5 deficiency in THP-1 cells. Moreover, the expression of SH3BP5 positively correlates with CD25 and CD123 levels. Finally, our study highlights the crucial role of SH3BP5 in promoting the survival of AML cells, and its suppression may be a potential therapeutic strategy for treating human AML.

Towards a Better Understanding of Cohesin Mutations in AML

Classical driver mutations in acute myeloid leukemia (AML) typically affect regulators of cell proliferation, differentiation, and survival. The selective advantage of increased proliferation, improved survival, and reduced differentiation on leukemia progression is immediately obvious. Recent large-scale sequencing efforts have uncovered numerous novel AML-associated mutations. Interestingly, a substantial fraction of the most frequently mutated genes encode general regulators of transcription and chromatin state. Understanding the selective advantage conferred by these mutations remains a major challenge. A striking example are mutations in genes of the cohesin complex, a major regulator of three-dimensional genome organization. Several landmark studies have shown that cohesin mutations perturb the balance between self-renewal and differentiation of hematopoietic stem and progenitor cells (HSPC). Emerging data now begin to uncover the molecular mechanisms that underpin this phenotype. Among these mechanisms is a role for cohesin in the control of inflammatory responses in HSPCs and myeloid cells. Inflammatory signals limit HSPC self-renewal and drive HSPC differentiation. Consistent with this, cohesin mutations promote resistance to inflammatory signals, and may provide a selective advantage for AML progression. In this review, we discuss recent progress in understanding cohesin mutations in AML, and speculate whether vulnerabilities associated with these mutations could be exploited therapeutically.

Oroxylin A, a natural compound, mitigates the negative effects of TNFα-treated acute myelogenous leukemia cells

Tumor necrosis factor alpha (TNFα) is a complicated cytokine which is involved in proliferation and differentiation of acute myelogenous leukemia (AML) cells through a poorly understood mechanism. Mechanistic studies indicate that TNFα induced binding of PI3K subunit p85α to N-terminal truncated nuclear receptor RXRα (tRXRα) proteins, and activated AKT. The activated PI3K/AKT pathway negatively regulated differentiation of AML cells through the upregulation of c-Myc. In addition, TNFα also induced activation of nuclear factor κB (NF-κB), a nuclear transcription factor which was shown to promote cell proliferation. The present study demonstrates that oroxylin A, a natural compound isolated from Scutellariae radix, sensitizes leukemia cells to TNFα and markedly enhances TNFα-induced growth inhibition and differentiation of AML cell including human leukemia cell lines and primary AML cells. Activation of PI3K/AKT pathway could be inhibited by oroxylin A through inhibiting expression of tRXRα in NB4 and HL-60-resistant cells. Furthermore, we found that oroxylin A inhibited the activation of NF-κB and the DNA binding activity by TNFα proved by EMSA in these two AML cell lines. Moreover, in vivo studies showed that treatment with oroxylin A in combination with TNFα decreased AML cell population and prolonged survival in NOD/SCID mice with xenografts of primary AML cells. Overall, our results indicate that oroxylin A is able to inhibit the negative effects of TNFα for AML therapy, suggesting that combination of oroxylin A and TNFα have the potential to delay growth or eliminate the abnormal leukemic cells, thus representing a promising strategy for AML treatment.

Tumor necrosis factor α knockout impaired tumorigenesis in chronic myeloid leukemia cells partly by metabolism modification and miRNA regulation

Purpose

Half of the chronic myeloid leukemia (CML) patients with sustained deep molecular response suffer from relapse after discontinuation mainly because tyrosine kinase inhibitors (TKIs) cannot eradicate leukemia stem cells (LSCs). In addition, tumor necrosis factor α (TNF-α) is highly detected in CML patients. Our aim was to explore whether TNF-α is a potential target for LSC elimination.

Materials and methods

We applied a CRISPR/Cas9 gene editing technique, colony-forming cell assay, subcutaneous tumor models, miRNA-seq and liquid chromatography-mass spectroscopy (LC-MS) on metabonomics to explore the feasibility and mechanism of TNF-α as a new therapeutic target for CML.

Results

We demonstrated that TNF-α knockout remarkably decreased the proliferative, colony-forming and in vivo tumorigenesis capacities of the CML K562 cell line. The apoptosis was increased when TNF-α knockout cells were cultured with imatinib. The mechanisms involved in the abovementioned phenomena were that TNF-α knockout inhibited the citrate cycle and increased starch, sucrose, amino sugar and nucleotide sugar metabolism. In addition, differentially expressed miRNAs between TNF-α knockout and control cells were involved in the cell cycle, CML, P13K-Akt and pathways in cancer.

Conclusion

We identified that TNF-α may serve as a new target therapy for CML and described the metabolic pathways associated with TNF-α in CML cells for the first time.

Role of alternative polyadenylation dynamics in acute myeloid leukaemia at single-cell resolution

Alternative polyadenylation (APA) has been discovered to play regulatory roles in the development of many cancer cells through preferential addition of a poly(A) tail at specific sites of pre-mRNA. A recent study found that APA was involved in the mediation of acute myeloid leukaemia (AML). However, unlike gene expression heterogeneity, little attention has been directed toward variations in single-cell APA for different cell types during AML development. Here, we used single-cell RNA-seq data of a massive population of 16,843 bone marrow mononuclear cells (BMMCs) from healthy and AML patient samples to investigate dynamic APA usage in different cell types. Abnormalities of APA dynamics in the BMMCs from AML patient samples were uncovered compared to the stable APA dynamics in samples from healthy individuals, as well as lower APA diversity between eight cell types in AML patients. Genes with APA dynamics specific to the AML samples were significantly enriched in cellular signal transduction pathways that contribute to AML development. Moreover, many leukaemic cell marker genes such as NF-κB, GATA2 and IAP-Family genes exhibited APA dynamics that specifically affected abnormal proliferation and differentiation of leukemic BMMCs. Additionally, mature erythroid cells displayed greater APA dynamics and global 3' UTR shortening compared with other cell types. Our results revealed extensive involvement of APA regulation in leukemia development and erythropoiesis at the single-cell level, providing a high-resolution atlas to navigate cellular mRNA processing landscapes of differentiated cells in AML.

Emerging Therapies for Acute Myelogenus Leukemia Patients Targeting Apoptosis and Mitochondrial Metabolism

Acute Myelogenous Leukemia (AML) is a malignant disease of the hematopoietic cells, characterized by impaired differentiation and uncontrolled clonal expansion of myeloid progenitors/precursors, resulting in bone marrow failure and impaired normal hematopoiesis. AML comprises a heterogeneous group of malignancies, characterized by a combination of different somatic genetic abnormalities, some of which act as events driving leukemic development. Studies carried out in the last years have shown that AML cells invariably have abnormalities in one or more apoptotic pathways and have identified some components of the apoptotic pathway that can be targeted by specific drugs. Clinical results deriving from studies using B-cell lymphoma 2 (BCL-2) inhibitors in combination with standard AML agents, such as azacytidine, decitabine, low-dose cytarabine, provided promising results and strongly support the use of these agents in the treatment of AML patients, particularly of elderly patients. TNF-related apoptosis-inducing ligand (TRAIL) and its receptors are frequently deregulated in AML patients and their targeting may represent a promising strategy for development of new treatments. Altered mitochondrial metabolism is a common feature of AML cells, as supported through the discovery of mutations in the isocitrate dehydrogenase gene and in mitochondrial electron transport chain and of numerous abnormalities of oxidative metabolism existing in AML subgroups. Overall, these observations strongly support the view that the targeting of mitochondrial apoptotic or metabolic machinery is an appealing new therapeutic perspective in AML.

Cytokine production in myelofibrosis exhibits differential responsiveness to JAK-STAT, MAP kinase, and NFκB signaling

The distinct clinical features of myelofibrosis (MF) have been attributed in part to dysregulated inflammatory cytokine production. Circulating cytokine levels are elevated in MF patients; a subset of which have been shown to be poor prognostic indicators. In this study, cytokine overproduction was examined in MF patient plasma and in MF blood cells ex vivo using mass cytometry. Plasma cytokines measured following treatment with ruxolitinib remained markedly abnormal, indicating that aberrant cytokine production persists despite therapeutic JAK2 inhibition. In MF patient samples, 14/15 cytokines measured by mass cytometry were found to be constitutively overproduced, with the principal cellular source for most cytokines being monocytes, implicating a non-cell-autonomous role for monocyte-derived cytokines impacting disease-propagating stem/progenitor cells in MF. The majority of cytokines elevated in MF exhibited ex vivo hypersensitivity to thrombopoietin (TPO), toll-like receptor (TLR) ligands, and/or tumor necrosis factor (TNF). A subset of this group (including TNF, IL-6, IL-8, IL-10) was minimally sensitive to ruxolitinib. All TPO/TLR/TNF-sensitive cytokines, however, were sensitive to pharmacologic inhibition of NFκB and/or MAP kinase signaling. These results indicate that NFκB and MAP kinase signaling maintain cytokine overproduction in MF, and that inhibition of these pathways may provide optimal control of inflammatory pathophysiology in MF.

The cytokine network in acute myeloid leukemia (AML): A focus on pro- and anti-inflammatory mediators

Cytokines exert profound effects on the progression of hematopoietic malignancies such as acute myeloid leukemia (AML). Critical roles of cytokines in the context of inflammation have gained special interest. While pro-inflammatory mediators such as IL-1β, TNF-α and IL-6 tend to increase AML aggressiveness, anti-inflammatory mediators such as TGF-β and IL-10 appear to impede AML progression. Dysregulation of the complex interactions between pro- and anti-inflammatory cytokines in AML may create a pro-tumorigenic microenvironment with effects on leukemic cell proliferation, survival and drug-resistance. This article summarizes current knowledge about the functions of pro- and anti-inflammatory cytokines in AML, their modes of action, and therapeutic interventions with potential to improve clinical outcomes for AML patients.

Identification of DNA methylation prognostic signature of acute myelocytic leukemia

BACKGROUND

The aim of this study is to find the potential survival related DNA methylation signature capable of predicting survival time for acute myelocytic leukemia (AML) patients.

METHODS

DNA methylation data were downloaded. DNA methylation signature was identified in the training group, and subsequently validated in an independent validation group. The overall survival of DNA methylation signature was performed. Functional analysis was used to explore the function of corresponding genes of DNA methylation signature. Differentially methylated sites and CpG islands were also identified in poor-risk group.

RESULTS

A DNA methylation signature involving 8 DNA methylation sites and 6 genes were identified. Functional analysis showed that protein binding and cytoplasm were the only two enriched Gene Ontology terms. A total of 70 differentially methylated sites and 6 differentially methylated CpG islands were identified in poor-risk group.

CONCLUSIONS

The identified survival related DNA methylation signature adds to the prognostic value of AML.

The impact of inflammation and cytokine expression of PM2.5 in AML

Environmental and health issues have become a major focus of research worldwide in recent years. Particulate matter with diameter ≤2.5 µm (PM2.5) is a common air pollutant that has been demonstrated to be associated with various diseases, including acute myeloid leukemia (AML). In the present study, the effects of PM2.5 on the proliferation and inflammation were assessed using three human acute myeloid cell lines (U937, HL-60 and KG-1a) in vitro. Additionally, the levels of several cytokines [interleukin (IL)-2, IL-10, IL-17A and tumor necrosis factor (TNF)α] in AML cells and Sprague Dawley rats were evaluated to investigate the effects of PM2.5 on cytokine expression in AML. The results revealed that PM2.5 was capable of enhancing inflammatory responses in AML cells, and increasing IL-2, IL-10, IL-17A and TNFα mRNA expression in AML cells to different degrees. Furthermore, PM2.5 increased IL-2 and IL-10 contents in rats following 12 weeks of exposure. These results suggested that PM2.5 may serve a role in promoting the occurrence and progression of leukemia by affecting cytokine expression, and that there may be various mechanisms active in different AML subtypes.

Dexamethasone in hyperleukocytic acute myeloid leukemia

Patients with acute myeloid leukemia and a high white blood cell count are at increased risk of early death and relapse. Because mediators of inflammation contribute to leukostasis and chemoresistance, dexamethasone added to chemotherapy could improve outcomes. This retrospective study evaluated the impact of adding or not adding dexamethasone to chemotherapy in a cohort of 160 patients with at least 50×10⁹ white blood cells. In silico studies, primary samples, leukemic cell lines, and xenograft mouse models were used to explore the antileukemic activity of dexamethasone. There was no difference with respect to induction death rate, response, and infections between the 60 patients in the dexamethasone group and the 100 patients in the no dexamethasone group. Multivariate analysis showed that dexamethasone was significantly associated with improved relapse incidence (adjusted sub-HR: 0.30; 95% CI: 0.14–0.62; P=0.001), disease-free survival (adjusted HR: 0.50; 95% CI: 0.29–0.84; P=0.010), event-free survival (adjusted HR: 0.35; 95% CI: 0.21–0.58; P<0.001), and overall survival (adjusted HR: 0.41; 95% CI: 0.22–0.79; P=0.007). In a co-culture system, dexamethasone reduced the frequency of leukemic long-term culture initiating cells by 38% and enhanced the cytotoxicity of doxorubicin and cytarabine. In a patient-derived xenograft model treated with cytarabine, chemoresistant cells were enriched in genes of the inflammatory response modulated by dexamethasone. Dexamethasone also demonstrated antileukemic activity in NPM1-mutated samples. Dexamethasone may improve the outcome of acute myeloid leukemia patients receiving intensive chemotherapy. This effect could be due to the modulation of inflammatory chemoresistance pathways and to a specific activity in acute myeloid leukemia with NPM1 mutation.

JNK1 as a signaling node in VDR-BRAF induction of cell death in AML

Numerous clinical studies of vitamin D, its derivatives or analogs, have failed to clearly demonstrate sustained benefits when used for the treatment of human malignant diseases. However, given the strong preclinical evidence of anti-neoplastic activity and the epidemiological associations suggesting that vitamin D compounds may have a place in cancer therapy, attempts are continuing to devise new approaches to their therapeutic use. This laboratory has developed a strategy to enhance the effectiveness of the currently standard therapy of Acute Myeloid Leukemia (AML) by the immediate addition of the vitamin D2 analog Doxercalciferol combined with the plant polyphenol-derived Carnosic acid to AML cells previously treated with Cytarabine (AraC). Enhancement of AML cell death was noted to be dependent on VDR and BRAF kinase. Here we document that the stress-related kinase JNK is an important additional component of cell death enhancement in this protocol. Either the Knock-down or the inhibition of JNK activity reduced the enhancement of AraC-induced cell death, and we show that JNK signaling to the apoptosis regulator BIM and Caspase executioners of cell death are downstream of VDR and BRAF. A clear understanding of the molecular basis for the increased efficacy of AraC in the therapy of AML is expected to bring this regimen to a clinical trial.

Sensitizing leukemia stem cells to NF-κB inhibitor treatment in vivo by inactivation of both TNF and IL-1 signaling

We previously reported that autocrine TNF-α (TNF) is responsible for JNK pathway activation in a subset of acute myeloid leukemia (AML) patient samples, providing a survival/proliferation signaling parallel to NF-κB in AML stem cells (LSCs). In this study, we report that most TNF-expressing AML cells (LCs) also express another pro-inflammatory cytokine, IL1β, which acts in a parallel manner. TNF was produced primarily by LSCs and leukemic progenitors (LPs), whereas IL1β was mainly produced by partially differentiated leukemic blasts (LBs). IL1β also stimulates an NF-κB-independent pro-survival and proliferation signal through activation of the JNK pathway. We determined that co-inhibition of signaling stimulated by both TNF and IL1β synergizes with NF-κB inhibition in eliminating LSCs both ex vivo and in vivo. Our studies show that such treatments are most effective in M4/5 subtypes of AML.

The bone marrow microenvironment in health and disease at a glance

The bone marrow microenvironment (BMM) is the 'domicile' of hematopoietic stem cells, as well as of malignant processes that can develop there. Multiple and complex interactions with the BMM influence hematopoietic stem cell (HSC) physiology, but also the pathophysiology of hematological malignancies. Reciprocally, hematological malignancies alter the BMM, in order to render it more hospitable for malignant progression. In this Cell Science at a Glance article and accompanying poster, we highlight concepts of the normal and malignant hematopoietic stem cell niches. We present the intricacies of the BMM in malignancy and provide approaches for targeting the interactions between malignant cells and their BMM. This is done in an effort to augment existing treatment strategies in the future.

A machine learning approach to integrate big data for precision medicine in acute myeloid leukemia

Cancers that appear pathologically similar often respond differently to the same drug regimens. Methods to better match patients to drugs are in high demand. We demonstrate a promising approach to identify robust molecular markers for targeted treatment of acute myeloid leukemia (AML) by introducing: data from 30 AML patients including genome-wide gene expression profiles and in vitro sensitivity to 160 chemotherapy drugs, a computational method to identify reliable gene expression markers for drug sensitivity by incorporating multi-omic prior information relevant to each gene’s potential to drive cancer. We show that our method outperforms several state-of-the-art approaches in identifying molecular markers replicated in validation data and predicting drug sensitivity accurately. Finally, we identify SMARCA4 as a marker and driver of sensitivity to topoisomerase II inhibitors, mitoxantrone, and etoposide, in AML by showing that cell lines transduced to have high SMARCA4 expression reveal dramatically increased sensitivity to these agents.

Identification of markers of drug response is essential for precision therapy. Here the authors introduce an algorithm that uses prior information about each gene’s importance in AML to identify the most predictive gene-drug associations from transcriptome and drug response data from 30 AML samples.

Inflammatory Signaling Pathways in Preleukemic and Leukemic Stem Cells

Hematopoietic stem cells (HSCs) are a rare subset of bone marrow cells that usually exist in a quiescent state, only entering the cell cycle to replenish the blood compartment, thereby limiting the potential for errors in replication. Inflammatory signals that are released in response to environmental stressors, such as infection, trigger active cycling of HSCs. These inflammatory signals can also directly induce HSCs to release cytokines into the bone marrow environment, promoting myeloid differentiation. After stress myelopoiesis is triggered, HSCs require intracellular signaling programs to deactivate this response and return to steady state. Prolonged or excessive exposure to inflammatory cytokines, such as in prolonged infection or in chronic rheumatologic conditions, can lead to continued HSC cycling and eventual HSC loss. This promotes bone marrow failure, and can precipitate preleukemic states or leukemia through the acquisition of genetic and epigenetic changes in HSCs. This can occur through the initiation of clonal hematopoiesis, followed by the emergence preleukemic stem cells (pre-LSCs). In this review, we describe the roles of multiple inflammatory signaling pathways in the generation of pre-LSCs and in progression to myelodysplastic syndrome (MDS), myeloproliferative neoplasms, and acute myeloid leukemia (AML). In AML, activation of some inflammatory signaling pathways can promote the cycling and differentiation of LSCs, and this can be exploited therapeutically. We also discuss the therapeutic potential of modulating inflammatory signaling for the treatment of myeloid malignancies.

Therapeutic targeting of necroptosis by Smac mimetic bypasses apoptosis resistance in acute myeloid leukemia cells

Resistance to apoptosis, for example due to overexpression of Inhibitor of Apoptosis (IAP) proteins, is associated with poor prognosis in acute myeloid leukemia (AML). Here, we identify that Smac mimetics such as BV6, which antagonizes IAP proteins, elicit necroptosis in AML cells, in which apoptosis is inhibited pharmacologically by caspase inhibitors or genetically by caspase-8 knockdown. Importantly, BV6 triggers necroptosis also in apoptosis-resistant patient-derived AML blasts, underlining the clinical relevance of our findings. Mechanistically, we show that BV6-induced cell death depends on key components of necroptosis signaling such as RIP1, RIP3 and MLKL, since pharmacological or genetic inhibition of these proteins significantly protects AML cells from BV6-mediated cell death, whereas PGAM5 is dispensable. Interestingly, we identify constitutive tumor necrosis factor-alpha (TNFα) secretion and an autocrine/paracrine TNFα loop as critical mediators of BV6-induced necroptosis in AML cell lines and patient-derived blasts, as the TNFα-blocking antibody Enbrel or tumor necrosis factor-alpha receptor 1 (TNFR1) knockdown significantly rescue cell death. Notably, AML cells exhibit high basal levels of TNFα compared to non-malignant CD34+ cells, which is further increased by BV6. In conclusion, this is the first report showing that Smac mimetics circumvent apoptosis resistance in AML cells by inducing necroptosis in a TNFα-dependent manner, which has important implications for the development of new strategies to overcome treatment resistance in AML.

Therapeutic Targeting of MLL Degradation Pathways in MLL-Rearranged Leukemia

Chromosomal translocations of the mixed-lineage leukemia (MLL) gene with various partner genes result in aggressive leukemia with dismal outcomes. Despite similar expression at the mRNA level from the wild-type and chimeric MLL alleles, the chimeric protein is more stable. We report that UBE2O functions in regulating the stability of wild-type MLL in response to interleukin-1 signaling. Targeting wild-type MLL degradation impedes MLL leukemia cell proliferation, and it downregulates a specific group of target genes of the MLL chimeras and their oncogenic cofactor, the super elongation complex. Pharmacologically inhibiting this pathway substantially delays progression, and it improves survival of murine leukemia through stabilizing wild-type MLL protein, which displaces the MLL chimera from some of its target genes and, therefore, relieves the cellular oncogenic addiction to MLL chimeras. Stabilization of MLL provides us with a paradigm in the development of therapies for aggressive MLL leukemia and perhaps for other cancers caused by translocations.

Mass cytometry analysis reveals hyperactive NF Kappa B signaling in myelofibrosis and secondary acute myeloid leukemia

Myeloproliferative neoplasms (MPNs) feature a malignant clone containing the JAK2 V617F mutation, or another mutation causing dysregulated JAK2 kinase activity. The multiple disease phenotypes of MPNs, and their tendency to transform phenotypically, suggest pathophysiologic heterogeneities beyond a common phenomenon of JAK2 hyperactivation. JAK2 has the potential to activate multiple other signaling molecules, either directly through downstream effectors, or indirectly through induction of target gene expression. We have interrogated myeloproliferative signaling in myelofibrosis (MF) and secondary acute myeloid leukemia (sAML) patient samples using mass cytometry, which allows the quantitative measurement of multiple signaling molecules simultaneously at the single cell level, in cell populations representing a nearly complete spectrum of hematopoiesis. MF and sAML malignant cells demonstrated a high prevalence of hyperactivation of the JAK-STAT, MAP kinase, PI3 kinase, and NFκB signaling pathways. Constitutive NFκB signaling was evident across MF and sAML patients. A supporting GSEA analysis of MF showed many NFκB target genes to be expressed above normal levels in MF patient CD34+ cells. NFκB inhibition suppressed colony formation from MF CD34+ cells. This study indicates that NFκB signaling contributes to human myeloproliferative disease and is abnormally activated in MF and sAML.

Tumor necrosis factor α in the onset and progression of leukemia

Tumor necrosis factor alpha (TNF-α), originally described as an anti-neoplastic cytokine, has been found, in apparent contradiction to its name, to play an important role in promoting the development and progression of malignant disease. Targeting TNF-α with TNF antagonists has elicited an objective response in certain solid tumors in phase I and II clinical trials. This review focuses on the relationship of TNF-α expressed by leukemia cells and adverse clinical features of leukemia. TNF-α is involved in all steps of leukemogenesis, including cellular transformation, proliferation, angiogenesis, and extramedullary infiltration. TNF-α is also an important factor in the tumor microenvironment and assists leukemia cells in immune evasion, survival, and resistance to chemotherapy. TNF-α may be a potent target for leukemia therapy.

Sensitizing acute myeloid leukemia cells to induced differentiation by inhibiting the RIP1/RIP3 pathway

Tumor necrosis factor-α (TNF-α)-induced RIP1/RIP3 (receptor-interacting protein kinase 1/receptor-interacting protein kinase 3)-mediated necroptosis has been proposed as an alternative strategy for treating apoptosis-resistant leukemia. However, we found that most acute myeloid leukemia (AML) cells, especially M4 and M5 subtypes, produce TNF and show basal level activation of RIP1/RIP3/MLKL signaling, yet do not undergo necroptosis. TNF, through RIP1/RIP3 signaling, prevents degradation of SOCS1, a key negative regulator of interferon-γ (IFN-γ) signaling. Using both pharmacologic and genetic assays, we show here that inactivation of RIP1/RIP3 resulted in reduction of SOCS1 protein levels and partial differentiation of AML cells. AML cells with inactivated RIP1/RIP3 signaling show increased sensitivity to IFN-γ-induced differentiation. RIP1/RIP3 inactivation combined with IFN-γ treatment significantly attenuated the clonogenic capacity of both primary AML cells and AML cell lines. This combination treatment also compromised the leukemogenic ability of murine AML cells in vivo. Our studies suggest that inhibition of RIP1/RIP3-mediated necroptotic signaling might be a novel strategy for the treatment of AML when combined with other differentiation inducers.