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

Inflammation and Related Signaling Pathways in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is an aggressive hematologic malignancy, and inflammatory signaling is involved in its pathogenesis. Cytokines exert a robust effect on the progression of AML and affect survival outcomes. The dysregulation in the cytokine network may foster a pro-tumorigenic microenvironment, increasing leukemic cell proliferation, decreasing survival and driving drug resistance. The dominance of pro-inflammatory mediators such as IL-11β, TNF-α and IL-6 over anti-inflammatory mediators such as TGF-β and IL-10 has been implicated in tumor progression. Additionally, inflammatory cytokines have favored certain populations of hematopoietic stem and progenitor cells with mutated clonal hematopoiesis genes. This article summarizes current knowledge about inflammatory cytokines and signaling pathways in AML, their modes of action and the implications for immune tolerance and clonal hematopoiesis, with the aim of finding potential therapeutic interventions to improve clinical outcomes in AML patients.

Transforming the Niche: The Emerging Role of Extracellular Vesicles in Acute Myeloid Leukaemia Progression

Acute myeloid leukaemia (AML) management remains a significant challenge in oncology due to its low survival rates and high post-treatment relapse rates, mainly attributed to treatment-resistant leukaemic stem cells (LSCs) residing in bone marrow (BM) niches. This review offers an in-depth analysis of AML progression, highlighting the pivotal role of extracellular vesicles (EVs) in the dynamic remodelling of BM niche intercellular communication. We explore recent advancements elucidating the mechanisms through which EVs facilitate complex crosstalk, effectively promoting AML hallmarks and drug resistance. Adopting a temporal view, we chart the evolving landscape of EV-mediated interactions within the AML niche, underscoring the transformative potential of these insights for therapeutic intervention. Furthermore, the review discusses the emerging understanding of endothelial cell subsets' impact across BM niches in shaping AML disease progression, adding another layer of complexity to the disease progression and treatment resistance. We highlight the potential of cutting-edge methodologies, such as organ-on-chip (OoC) and single-EV analysis technologies, to provide unprecedented insights into AML-niche interactions in a human setting. Leveraging accumulated insights into AML EV signalling to reconfigure BM niches and pioneer novel approaches to decipher the EV signalling networks that fuel AML within the human context could revolutionise the development of niche-targeted therapy for leukaemia eradication.

Signaling pathways governing the behaviors of leukemia stem cells

Leukemia is a malignancy in the blood that develops from the lymphatic system and bone marrow. Although various treatment options have been used for different types of leukemia, understanding the molecular pathways involved in the development and progression of leukemia is necessary. Recent studies showed that leukemia stem cells (LSCs) play essential roles in the pathogenesis of leukemia by targeting several signaling pathways, including Notch, Wnt, Hedgehog, and STAT3. LSCs are highly proliferative cells that stimulate tumor initiation, migration, EMT, and drug resistance. This review summarizes cellular pathways that stimulate and prevent LSCs' self-renewal, metastasis, and tumorigenesis.

Micheliolide exerts effects in myeloproliferative neoplasms through inhibiting STAT3/5 phosphorylation via covalent binding to STAT3/5 proteins

Ruxolitinib is a cornerstone of management for some subsets of myeloproliferative neoplasms (MPNs); however, a considerable number of patients respond suboptimally. Here, we evaluated the efficacy of micheliolide (MCL), a natural guaianolide sesquiterpene lactone, alone or in combination with ruxolitinib in samples from patients with MPNs, JAK2V617F-mutated MPN cell lines, and a Jak2V617F knock-in mouse model. MCL effectively suppressed colony formation of hematopoietic progenitors in samples from patients with MPNs and inhibited cell growth and survival of MPN cell lines in vitro. Co-treatment with MCL and ruxolitinib resulted in greater inhibitory effects compared with treatment with ruxolitinib alone. Moreover, dimethylaminomicheliolide (DMAMCL), an orally available derivative of MCL, significantly increased the efficacy of ruxolitinib in reducing splenomegaly and cytokine production in Jak2V617F knock-in mice without evident effects on normal hematopoiesis. Importantly, MCL could target the Jak2V617F clone and reduce mutant allele burden in vivo. Mechanistically, MCL can form a stable covalent bond with cysteine residues of STAT3/5 to suppress their phosphorylation, thus inhibiting JAK/STAT signaling. Overall, these findings suggest that MCL is a promising drug in combination with ruxolitinib in the setting of suboptimal response to ruxolitinib.

NF-κB: A Druggable Target in Acute Myeloid Leukemia

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.

IRAK1 and IRAK4 as emerging therapeutic targets in hematologic malignancies

PURPOSE OF REVIEW

Cell intrinsic and extrinsic perturbations to inflammatory signaling pathways are a hallmark of development and progression of hematologic malignancies. The interleukin 1 receptor-associated kinases (IRAKs) are a family of related signaling intermediates (IRAK1, IRAK2, IRAK3, IRAK4) that operate at the nexus of multiple inflammatory pathways implicated in the hematologic malignancies. In this review, we explicate the oncogenic role of these kinases and review recent therapeutic advances in the dawning era of IRAK-targeted therapy.

RECENT FINDINGS

Emerging evidence places IRAK signaling at the confluence of adaptive resistance and oncogenesis in the hematologic malignancies and solid tissue tumors. Preclinical investigations nominate the IRAK kinases as targetable molecular dependencies in diverse cancers.

SUMMARY

IRAK-targeted therapies that have matriculated to early phase trials are yielding promising preliminary results. However, studies of IRAK kinase signaling continue to defy conventional signaling models and raise questions as to the design of optimal treatment strategies. Efforts to refine IRAK signaling mechanisms in the malignant context will inspire deliberate IRAK-targeted drug development and informed combination therapy.

Quercetin attenuates lipopolysaccharide-mediated inflammatory injury in human nasal epithelial cells via regulating miR-21/DMBT1/NF-κB axis

BACKGROUND

Quercetin (Qu) belongs to a flavonoid polyphenolic compound present in fruits and vegetables which has been confirmed to exert anti-inflammatory properties. Our study aimed to explore the impacts of quercetin on lipopolysaccharide (LPS)-induced inflammatory injury and signal transduction of miR-21/DMBT1/NF-κB axis in human nasal epithelial cells (HNEpC).

METHODS

HNEpCs were cultured and treated with 1 μg/mL of LPS and a gradient concentration (10, 100, and 200 μM) of quercetin for 24 h. Cell viability, apoptosis, and cytokines were detected to assess the inflammatory injury in LPS-exposed HNEpCs. The expressions of miR-21, DMBT1, and NF-κB mRNA were detected by quantitative real-time polymerase chain reaction (qRT-PCR). The levels of DMBT1 and NF-κB protein were measured by western blotting.

RESULTS

LPS treatment reduced cell viability, promoted cell apoptosis and inflammatory response, down-regulated miR-21 expression and up-regulated DMBT1, and NF-κB in HNEpC cells. Quercetin exerted the opposite effects to attenuate LPS-induced inflammatory injury in HNEpC cells at a concentration-dependent way. Additionally, miR-21 directly targeted DMBT1 to reduce its expression and further inducing cell viability via inhibiting cell apoptosis and inflammatory response. MiR-21 inhibition or DMBT1 over-expression weakened the protective effects of quercetin against LPS-induced inflammatory injury in HNEpC cells.

CONCLUSIONS

Quercetin could protect HNEpC cells against LPS-induced inflammatory injury via inducing miR-21/DMBT1/NF-κB axis. Therefore, quercetin could be utilized as a potential compound to treat for allergic rhinitis.

Ferritin H deficiency deteriorates cellular iron handling and worsens Salmonella typhimurium infection by triggering hyperinflammation

Iron is an essential nutrient for mammals as well as for pathogens. Inflammation-driven changes in systemic and cellular iron homeostasis are central for host-mediated antimicrobial strategies. Here, we studied the role of the iron storage protein ferritin H (FTH) for the control of infections with the intracellular pathogen Salmonella enterica serovar Typhimurium by macrophages. Mice lacking FTH in the myeloid lineage (LysM-Cre+/+Fthfl/fl mice) displayed impaired iron storage capacities in the tissue leukocyte compartment, increased levels of labile iron in macrophages, and an accelerated macrophage-mediated iron turnover. While under steady-state conditions, LysM-Cre+/+Fth+/+ and LysM-Cre+/+Fthfl/fl animals showed comparable susceptibility to Salmonella infection, i.v. iron supplementation drastically shortened survival of LysM-Cre+/+Fthfl/fl mice. Mechanistically, these animals displayed increased bacterial burden, which contributed to uncontrolled triggering of NF-κB and inflammasome signaling and development of cytokine storm and death. Importantly, pharmacologic inhibition of the inflammasome and IL-1β pathways reduced cytokine levels and mortality and partly restored infection control in iron-treated ferritin-deficient mice. These findings uncover incompletely characterized roles of ferritin and cellular iron turnover in myeloid cells in controlling bacterial spread and for modulating NF-κB and inflammasome-mediated cytokine activation, which may be of vital importance in iron-overloaded individuals suffering from severe infections and sepsis.

Aberrantly low STAT3 and STAT5 responses are associated with poor outcome and an inflammatory gene expression signature in pediatric acute myeloid leukemia

The relapse rate for children with acute myeloid leukemia is nearly 40% despite aggressive chemotherapy and often stem cell transplant. We sought to understand how environment-induced signaling responses are associated with clinical response to treatment. We previously reported that patients whose AML cells showed low G-CSF-induced STAT3 activation had inferior event-free survival compared to patients with stronger STAT3 responses. Here, we expanded the paradigm to evaluate multiple signaling parameters induced by a more physiological stimulus. We measured STAT3, STAT5 and ERK1/2 responses to G-CSF and to stromal cell-conditioned medium for 113 patients enrolled on COG trials AAML03P1 and AAML0531. Low inducible STAT3 activity was independently associated with inferior event-free survival in multivariate analyses. For inducible STAT5 activity, those with the lowest and highest responses had inferior event-free survival, compared to patients with intermediate STAT5 responses. Using existing RNA-sequencing data, we compared gene expression profiles for patients with low inducible STAT3/5 activation with those for patients with higher inducible STAT3/5 signaling. Genes encoding hematopoietic factors and mitochondrial respiratory chain subunits were overexpressed in the low STAT3/5 response groups, implicating inflammatory and metabolic pathways as potential mechanisms of chemotherapy resistance. We validated the prognostic relevance of individual genes from the low STAT3/5 response signature in a large independent cohort of pediatric AML patients. These findings provide novel insights into interactions between AML cells and the microenvironment that are associated with treatment failure and could be targeted for therapeutic interventions.

Whole transcriptome sequencing and integrated network analysis elucidates the effects of 3,8-Di-O-methylellagic acid 2-O-glucoside derived from Sanguisorba offcinalis L., a novel differentiation inducer on erythroleukemia cells

Acute erythroid leukemia (AEL) is a rare and aggressive hematologic malignancy with no specific treatment. Sanguisorba officinalis L. (S. officinalis), a well-known traditional Chinese medicine, possesses potent anticancer activity. However, the active components of S. officinalis against AEL and the associated molecular mechanisms remain unknown. In this study, we predicted the anti-AML effect of S. officinalis based on network pharmacology. Through the identification of active components of S. officinalis, we found that 3,8-Di-O-methylellagic acid 2-O-glucoside (DMAG) not only significantly inhibited the proliferation of erythroleukemic cell line HEL, but also induced their differentiation to megakaryocytes. Furthermore, we demonstrated that DMAG could prolong the survival of AEL mice model. Whole-transcriptome sequencing was performed to elucidate the underlying molecular mechanisms associated with anti-AEL effect of DMAG. The results showed that the total of 68 miRNAs, 595 lncRNAs, 4030 mRNAs and 35 circRNAs were significantly differentially expressed during DMAG induced proliferation inhibition and differentiation of HEL cells. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses revealed that the differentially expressed miRNAs, lncRNAs, mRNAs and circRNAs were mainly involved in metabolic, HIF-1, MAPK, Notch pathway and apoptosis. The co-expression networks showed that miR-23a-5p, miR-92a-1-5p, miR-146b and miR-760 regulatory networks were crucial for megakaryocyte differentiation induced by DMAG. In conclusion, our results suggest that DMAG, derived from S. officinalis might be a potent differentiation inducer of AEL cells and provide important information on the underlying mechanisms associated with its anti-AEL activity.

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.

Oxidative Stress and ROS-Mediated Signaling in Leukemia: Novel Promising Perspectives to Eradicate Chemoresistant Cells in Myeloid Leukemia

Myeloid leukemic cells are intrinsically under oxidative stress due to impaired reactive oxygen species (ROS) homeostasis, a common signature of several hematological malignancies. The present review focuses on the molecular mechanisms of aberrant ROS production in myeloid leukemia cells as well as on the redox-dependent signaling pathways involved in the leukemogenic process. Finally, the relevance of new chemotherapy options that specifically exert their pharmacological activity by altering the cellular redox imbalance will be discussed as an effective strategy to eradicate chemoresistant cells.

Atrial fibrillation influences automatic oscillometric ankle-brachial index measurement

INTRODUCTION

Repeated measurements of ankle-brachial index (ABI) using Doppler method were shown to be accurate during atrial fibrillation. Oscillometric devices are effective in ABI measurement, but their accuracy during atrial fibrillation is unknown. The purpose of the study was to investigate whether atrial fibrillation influences ABI obtained with the automatic oscillometric method.

MATERIAL AND METHODS

Ninety-nine patients with atrial fibrillation (mean age: 66.6 +(SD = 11) years, M/F - 63/36) who underwent electrical cardioversion were investigated (198 lower extremities). The ABI measurements using oscillometric and Doppler methods were performed on both lower extremities before and after procedure.

RESULTS

The ABI measured using the oscillometric method on both lower limbs did not change after cardioversion (1.21 (IQR: 1.13-1.27) vs. 1.22 (IQR: 1.14-1.26), p = 0.664, respectively). The ABI measured before and after cardioversion using Doppler and oscillometric methods showed a significant difference (1.14 (IQR: 1.07-1.22) vs. 1.21 (IQR: 1.13-1.27), p < 0.001 and 1.18 (IQR: 1.09-1.13) vs. 1.22 (IQR: 1.14-1.26), p < 0.001 respectively). Both methods showed a weak correlation before (r = 0.35, p < 0.001) and no correlation after cardioversion (r = 0.12, p = 0.07). The Bland-Altman plot showed poor agreement between measurements performed with the Doppler and oscillometric methods in sinus rhythm and during atrial fibrillation.

CONCLUSIONS

The automated oscillometric method of ABI measurements should not replace the reference Doppler method in patients with atrial fibrillation. More research related to the oscillometric measurements is needed in subjects with peripheral artery disease and atrial fibrillation.

Modulation of cytokine production by monocytes and developing-dendritic cells under the influence of leukemia and lymphoma cell products

Cytokines and other soluble factors released by tumor cells play an important role in modulating immune cells to favor tumor development. Monocyte differentiation into macrophages or dendritic cells (DCs) with specific phenotypes is deeply affected by tumor signals and understanding this context is paramount to prevent and propose new therapeutic possibilities. Hence, we developed a study to better describe the modulatory effects of leukemia and lymphoma cell products on human monocytes and monocyte-derived DCs secretion of cytokines such as interleukin (IL)-1β, tumor necrosis factor-α (TNF-α), IL-6, and IL-12. Except with the promyelocytic leukemia cell supernatants (HL-60), the other two tumor supernatants (chronic myeloid leukemia, K562 and Burkitt lymphoma, DAUDI) increased both TNF-α and IL-1β production by monocytes and monocytes undergoing differentiation. This effect was neither explained by alterations of cell number in culture nor by the high amount of vascular endothelial growth factor (VEGF) present in the tumor supernatants. Moreover, all supernatants used were able to induce drastic reduction of IL-12 secretion by cells induced to activation, suggesting a negative interference with Th1 antitumoral responses that should be a huge advantage for tumor progression.

Combinatorial Inhibition of Focal Adhesion Kinase and BCL-2 Enhances Antileukemia Activity of Venetoclax in Acute Myeloid Leukemia

Focal adhesion kinase (FAK) promotes cancer cell growth and metastasis. We previously reported that FAK inhibition by the selective inhibitor VS-4718 exerted antileukemia activities in acute myeloid leukemia (AML). The mechanisms involved, and whether VS-4718 potentiates efficacy of other therapeutic agents, have not been investigated. Resistance to apoptosis inducted by the BCL-2 inhibitor ABT-199 (venetoclax) in AML is mediated by preexisting and ABT-199-induced overexpression of MCL-1 and BCL-XL. We observed that VS-4718 or silencing FAK with siRNA decreased MCL-1 and BCL-XL levels. Importantly, VS-4718 antagonized ABT-199-induced MCL-1 and BCL-XL. VS-4718 markedly synergized with ABT-199 to induce apoptosis in AML cells, including primary AML CD34+ cells and AML cells overexpressing MCL-1 or BCL-XL. In a patient-derived xenograft (PDX) model derived from a patient sample with NPM1/FLT3-ITD/TET2/DNMT3A/WT1 mutations and complex karyotype, VS-4718 statistically significantly reduced leukemia tissue infiltration and extended survival (72 vs. control 36 days, P = 0.0002), and only its combination with ABT-199 effectively decreased systemic leukemia tissue infiltration and circulating blasts, and prolonged survival (65.5 vs. control 36 days, P = 0.0119). Furthermore, the combination decreased NFκB signaling and induced the expression of IFN genes in vivo The combination also markedly extended survival of a second PDX model developed from an aggressive, TP53-mutated complex karyotype AML sample. The data suggest that the combined inhibition of FAK and BCL-2 enhances antileukemia activity in AML at least in part by suppressing MCL-1 and BCL-XL and that this combination may be effective in AML with TP53 and other mutations, and thus benefit patients with high-risk AML.

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.

HMGA Proteins in Hematological Malignancies

The high mobility group AT-Hook (HMGA) proteins are a family of nonhistone chromatin remodeling proteins known as "architectural transcriptional factors". By binding the minor groove of AT-rich DNA sequences, they interact with the transcription apparatus, altering the chromatin modeling and regulating gene expression by either enhancing or suppressing the binding of the more usual transcriptional activators and repressors, although they do not themselves have any transcriptional activity. Their involvement in both benign and malignant neoplasias is well-known and supported by a large volume of studies. In this review, we focus on the role of the HMGA proteins in hematological malignancies, exploring the mechanisms through which they enhance neoplastic transformation and how this knowledge could be exploited to devise tailored therapeutic strategies.

HMGA2 regulates acute myeloid leukemia progression and sensitivity to daunorubicin via Wnt/β-catenin signaling

Acute myeloid leukemia (AML) is a malignant disease with an increasing prevalence in adults and children. However, valuable molecular diagnostic research is rare. In the present study, plasmids silencing and overexpressing high‑mobility group AT‑hook 2 (HMGA2) were respectively transfected in HL60 and NB4 cells. The effects of HMGA2 on AML cell viability, apoptosis, migration and invasion were determined by preforming MTT, flow cytometry, wound scratch and Transwell assays, respectively. Genes associated with apoptosis and Wnt signaling were evaluated by reverse transcription‑quantitative (RT‑q)‑PCR and western blotting. AML cell sensitivity to daunorubicin (DNR) and the regulatory effects of the Wnt signaling pathway via HMGA2 following treatment with the agonist LiCl or antagonist XAV939 were detected by MTT, RT‑qPCR and western blot analysis. The results revealed that the expression of HMGA2 was elevated more so in HL60, KG1, U937, Kasumi‑1, THP‑1 and K562 cells than in NB4 cells. Silencing HMGA2 suppressed cell viability, migration and invasion, enhanced cell apoptosis and sensitivity to DNR, and almost restored the DNR inhibitory function that was promoted by LiCl treatment. In addition, low expression of HMGA2 attenuated X‑linked inhibitor of apoptosis and Bcl‑2 mRNA and protein levels, and upregulated the expression of Bax and cleaved‑caspase‑3. Furthermore, silencing HMGA2 not only decreased Wnt and non‑phospho‑β‑catenin expressions, but also partially reversed the increased expressions of these proteins induced by LiCl treatment. On the other hand, overexpression of HMGA2 exhibited the opposite results after transfection in NB4 cells. The results of the present study demonstrated that HMGA2 played important roles in driving AML progression and chemosensitivity in HL60 and NB4 cells, potentially by activating the Wnt/β‑catenin signaling pathway. Therefore, it was suggested that HMGA2 may be a promising molecular marker for AML diagnosis.

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.

Loss of the selective autophagy receptor p62 impairs murine myeloid leukemia progression and mitophagy

Autophagy maintains hematopoietic stem cell integrity and prevents malignant transformation. In addition to bulk degradation, selective autophagy serves as an intracellular quality control mechanism and requires autophagy receptors, such as p62 (SQSTM1), to specifically bridge the ubiquitinated cargos into autophagosomes. Here, we investigated the function of p62 in acute myeloid leukemia (AML) in vitro and in murine in vivo models of AML. Loss of p62 impaired expansion and colony-forming ability of leukemia cells and prolonged latency of leukemia development in mice. High p62 expression was associated with poor prognosis in human AML. Using quantitative mass spectrometry, we identified enrichment of mitochondrial proteins upon immunoprecipitation of p62. Loss of p62 significantly delayed removal of dysfunctional mitochondria, increased mitochondrial superoxide levels, and impaired mitochondrial respiration. Moreover, we demonstrated that the autophagy-dependent function of p62 is essential for cell growth and effective mitochondrial degradation by mitophagy. Our results highlight the prominent role of selective autophagy in leukemia progression, and specifically, the importance of mitophagy to maintain mitochondrial integrity.

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.

Disordered Immune Regulation and its Therapeutic Targeting in Myelodysplastic Syndromes

PURPOSE OF REVIEW

Immune dysregulation is a defining feature of myelodysplastic syndromes (MDS). Recently, several studies have further defined the complex role of immune alterations within MDS. Herein, we will summarize some of these findings and discuss the therapeutic strategies currently in development.

RECENT FINDINGS

Immune alterations in MDS are complex, heterogeneous, and intertwined with clonal hematopoiesis and stromal cell dysfunction. Inflammation in MDS proceeds as a vicious cycle, mediated in large part by secreted factors, which induce cell death and activate innate immune signaling. Therapeutic targeting of this variable immune dysregulation has led to modest responses thus far, but incorporation of the growing repertoire of immunotherapy brings new potential for improved outcomes. The immune milieu is variable across the spectrum of MDS subtypes, with a changing balance of inflammatory and suppressive cellular forces from low- to high-risk disease.

A New Venue of TNF Targeting

The first Food and Drug Administration-(FDA)-approved drugs were small, chemically-manufactured and highly active molecules with possible off-target effects, followed by protein-based medicines such as antibodies. Conventional antibodies bind a specific protein and are becoming increasingly important in the therapeutic landscape. A very prominent class of biologicals are the anti-tumor necrosis factor (TNF) drugs that are applied in several inflammatory diseases that are characterized by dysregulated TNF levels. Marketing of TNF inhibitors revolutionized the treatment of diseases such as Crohn’s disease. However, these inhibitors also have undesired effects, some of them directly associated with the inherent nature of this drug class, whereas others are linked with their mechanism of action, being pan-TNF inhibition. The effects of TNF can diverge at the level of TNF format or receptor, and we discuss the consequences of this in sepsis, autoimmunity and neurodegeneration. Recently, researchers tried to design drugs with reduced side effects. These include molecules with more specificity targeting one specific TNF format or receptor, or that neutralize TNF in specific cells. Alternatively, TNF-directed biologicals without the typical antibody structure are manufactured. Here, we review the complications related to the use of conventional TNF inhibitors, together with the anti-TNF alternatives and the benefits of selective approaches in different diseases.

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.

Chlorpheniramine attenuates histamine-mediated aquaporin 5 downregulation in human nasal epithelial cells via suppression of NF-κB activation

Background: Aquaporin 5 (AQP5) is most likely the primary water channel in the human nasal mucosa and acts as a key tight junction protein. The signaling cascades responsible for AQP5 regulation are still works in progress. Objective: This study sought to determine the effects of histamine and chlorpheniramine on AQP5 expression in human nasal epithelial cells (HNEpC) and to detect the signaling cascades responsible for these effects. Methods: HNEpC were cultured with four concentrations of histamine or chlorpheniramine in vitro. The sub-cellular distribution of AQP5 was explored using immunocytochemistry. The pharmacologic effects of histamine and chlorpheniramine on the expression of the phosphorylation of cyclic adenosine monophosphate-responsive element binding protein (p-CREB), the AQP5 and the NF-κB protein were examined using Western blotting. Results: AQP5 was found to be located in cell membrane and cytoplasm and present in every group without significant difference. Histamine inhibits the expression of AQP5 and p-CREB in HNEpC, while chlorpheniramine dose-dependently increases these protein levels with statistical significance. HNEpC treated with histamine and chlorpheniramine in turn showed the same trends as those intervened separately with these two drugs. Moreover, chlorpheniramine had the ability to reverse the inhibitory effect of histamine. Western blotting analysis revealed that after incubation with 10-4 M histamine, NF-κB protein was significantly heightened by 165% compared with the untreated control group. Again, such increase can be significantly reversed after chlorpheniramine treatment. Conclusions: The current study demonstrated that histamine inhibits CREB phosphorylation in HNEpC, which results in decreased AQP5 expression via activation of NF-κB pathway. Chlorpheniramine attenuates the inhibitory effect of histamine in p-CREB/AQP5 expression via suppression of NF-κB signal cascades. This observation could provide additional insight into the anti-inflammatory effects of H1-antihistamines that contribute to maintain airway surface liquid and mucosal defense.

Ghrelin protects against nucleus pulposus degeneration through inhibition of NF-κB signaling pathway and activation of Akt signaling pathway

The objective of the present study was to examine the potential role of ghrelin in degeneration of nucleus pulposus (NP). Lower expression levels of ghrelin were found in human NP cells stimulated with interleukin-1β (IL-1β). Moreover, exogenous ghrelin suppressed IL-1β induced degeneration and inflammation associated biomarkers in human NP cells, including matrix metalloproteinase-13, a disintegrin and metalloproteinase with thrombospondin motifs-5, tumor necrosis factor-α and iNOS, which was possibly mediated by antagonization of NF-κB signaling. Moreover, ghrelin enhanced production of critical extracellular matrix of NP cells, including collagen 2, aggrecan, and Sox-9 in NP cells. Ghrelin also promoted NP tissue regeneration in a rabbit IVD degeneration model, which seems to be associated with growth hormone secretagogue receptor. Additionally, the protective role of ghrelin in anabolism potentially relies on activation of Akt signaling pathway. Taken together, ghrelin may represent a molecular target for prevention and treatment of intervertebral disc degeneration.