Design and preparation of 2-benzamido-pyrimidines as inhibitors of IKK

The PARP inhibitor rucaparib blocks SARS-CoV-2 virus binding to cells and the immune reaction in models of COVID-19

BACKGROUND AND PURPOSE

To date, there are limited options for severe Coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2 virus. As ADP-ribosylation events are involved in regulating the life cycle of coronaviruses and the inflammatory reactions of the host; we have, here, assessed the repurposing of registered PARP inhibitors for the treatment of COVID-19.

EXPERIMENTAL APPROACH

The effects of PARP inhibitors on virus uptake were assessed in cell-based experiments using multiple variants of SARS-CoV-2. The binding of rucaparib to spike protein was tested by molecular modelling and microcalorimetry. The anti-inflammatory properties of rucaparib were demonstrated in cell-based models upon challenging with recombinant spike protein or SARS-CoV-2 RNA vaccine.

KEY RESULTS

We detected high levels of oxidative stress and strong PARylation in all cell types in the lungs of COVID-19 patients, both of which negatively correlated with lymphocytopaenia. Interestingly, rucaparib, unlike other tested PARP inhibitors, reduced the SARS-CoV-2 infection rate through binding to the conserved 493-498 amino acid region located in the spike-ACE2 interface in the spike protein and prevented viruses from binding to ACE2. In addition, the spike protein and viral RNA-induced overexpression of cytokines was down-regulated by the inhibition of PARP1 by rucaparib at pharmacologically relevant concentrations.

CONCLUSION AND IMPLICATIONS

These results point towards repurposing rucaparib for treating inflammatory responses in COVID-19.

Reduced SH3RF3 may protect against Alzheimer's disease by lowering microglial pro-inflammatory responses via modulation of JNK and NFkB signaling

Understanding how high-risk individuals are protected from Alzheimer's disease (AD) may illuminate potential therapeutic targets. A previously identified non-coding SNP in SH3RF3/POSH2 significantly delayed disease onset in a Caribbean Hispanic cohort carrying the PSEN1 G206A mutation sufficient to cause early-onset AD and microglial expression of SH3RF3 has been reported to be a key driver of late-onset AD. SH3RF3 acts as a JNK pathway scaffold and can activate NFκB signaling. While effects of SH3RF3 knockdown in human neurons were subtle, including decreased phospho-tau S422, knockdown in human microglia significantly reduced inflammatory cytokines in response to either a viral mimic or oligomeric Aβ42. This was associated with reduced activation of JNK and NFκB pathways in response to these stimuli. Pharmacological inhibition of JNK or NFκB signaling phenocopied SH3RF3 knockdown. We also found PSEN1 G206A microglia have reduced inflammatory responses to oAβ42. Thus, further reduction of microglial inflammatory responses in PSEN1 mutant carriers by protective SNPs in SH3RF3 might reduce the link between amyloid and neuroinflammation to subsequently delay the onset of AD.

The lipopeptide Pam3CSK4 inhibits Rift Valley fever virus infection and protects from encephalitis

Rift Valley fever virus (RVFV) is an encephalitic bunyavirus that can infect neurons in the brain. There are no approved therapeutics that can protect from RVFV encephalitis. Innate immunity, the first line of defense against infection, canonically antagonizes viruses through interferon signaling. We found that interferons did not efficiently protect primary cortical neurons from RVFV, unlike other cell types. To identify alternative neuronal antiviral pathways, we screened innate immune ligands and discovered that the TLR2 ligand Pam3CSK4 inhibited RVFV infection, and other bunyaviruses. Mechanistically, we found that Pam3CSK4 blocks viral fusion, independent of TLR2. In a mouse model of RVFV encephalitis, Pam3CSK4 treatment protected animals from infection and mortality. Overall, Pam3CSK4 is a bunyavirus fusion inhibitor active in primary neurons and the brain, representing a new approach toward the development of treatments for encephalitic bunyavirus infections.

JAK1/2 Regulates Synergy Between Interferon Gamma and Lipopolysaccharides in Microglia

Microglia, the resident immune cells of the brain, regulate neuroinflammation which can lead to secondary neuronal damage and cognitive impairment under pathological conditions. Two of the many molecules that can elicit an inflammatory response from microglia are lipopolysaccharide (LPS), a component of gram-negative bacteria, and interferon gamma (IFNγ), an endogenous pro-inflammatory cytokine. We thoroughly examined the concentration-dependent relationship between LPS from multiple bacterial species and IFNγ in cultured microglia and macrophages. We measured the effects that these immunostimulatory molecules have on pro-inflammatory activity of microglia and used a battery of signaling inhibitors to identify the pathways that contribute to the microglial response. We found that LPS and IFNγ interacted synergistically to induce a pro-inflammatory phenotype in microglia, and that inhibition of JAK1/2 completely blunted the response. We determined that this synergistic action of LPS and IFNγ was likely dependent on JNK and Akt signaling rather than typical pro-inflammatory mediators such as NF-κB. Finally, we demonstrated that LPS derived from Escherichia coli, Klebsiella pneumoniae, and Akkermansia muciniphila can elicit different inflammatory responses from microglia and macrophages, but these responses could be consistently prevented using ruxolitinib, a JAK1/2 inhibitor. Collectively, this work reveals a mechanism by which microglia may become hyperactivated in response to the combination of LPS and IFNγ. Given that elevations in circulating LPS and IFNγ occur in a wide variety of pathological conditions, it is critical to understand the pharmacological interactions between these molecules to develop safe and effective treatments to suppress this process.

A gain-of-function p53 mutant synergizes with oncogenic NRAS to promote acute myeloid leukemia in mice

We previously demonstrated that a subset of acute myeloid leukemia (AML) patients with concurrent RAS pathway and TP53 mutations have an extremely poor prognosis and that most of these TP53 mutations are missense mutations. Here, we report that, in contrast to the mixed AML and T cell malignancy that developed in NrasG12D/+ p53-/- (NP-/-) mice, NrasG12D/+ p53R172H/+ (NPmut) mice rapidly developed inflammation-associated AML. Under the inflammatory conditions, NPmut hematopoietic stem and progenitor cells (HSPCs) displayed imbalanced myelopoiesis and lymphopoiesis and mostly normal cell proliferation despite MEK/ERK hyperactivation. RNA-Seq analysis revealed that oncogenic NRAS signaling and mutant p53 synergized to establish an NPmut-AML transcriptome distinct from that of NP-/- cells. The NPmut-AML transcriptome showed GATA2 downregulation and elevated the expression of inflammatory genes, including those linked to NF-κB signaling. NF-κB was also upregulated in human NRAS TP53 AML. Exogenous expression of GATA2 in human NPmut KY821 AML cells downregulated inflammatory gene expression. Mouse and human NPmut AML cells were sensitive to MEK and NF-κB inhibition in vitro. The proteasome inhibitor bortezomib stabilized the NF-κB-inhibitory protein IκBα, reduced inflammatory gene expression, and potentiated the survival benefit of a MEK inhibitor in NPmut mice. Our study demonstrates that a p53 structural mutant synergized with oncogenic NRAS to promote AML through mechanisms distinct from p53 loss.

Ouabain's Influence on TRPV4 Channels of Epithelial Cells: An Exploration of TRPV4 Activity, Expression, and Signaling Pathways

Ouabain, a substance originally obtained from plants, is now classified as a hormone because it is produced endogenously in certain animals, including humans. However, its precise effects on the body remain largely unknown. Previous studies have shown that ouabain can influence the phenotype of epithelial cells by affecting the expression of cell-cell molecular components and voltage-gated potassium channels. In this study, we conducted whole-cell clamp assays to determine whether ouabain affects the activity and/or expression of TRPV4 channels. Our findings indicate that ouabain has a statistically significant effect on the density of TRPV4 currents (dITRPV4), with an EC50 of 1.89 nM. Regarding treatment duration, dITRPV4 reaches its peak at around 1 h, followed by a subsequent decline and then a resurgence after 6 h, suggesting a short-term modulatory effect related to on TRPV4 channel activity and a long-term effect related to the promotion of synthesis of new TRPV4 channel units. The enhancement of dITRPV4 induced by ouabain was significantly lower in cells seeded at low density than in cells in a confluent monolayer, indicating that the action of ouabain depends on intercellular contacts. Furthermore, the fact that U73122 and neomycin suppress the effect caused by ouabain in the short term suggests that the short-term induced enhancement of dITRPV4 is due to the depletion of PIP2 stores. In contrast, the fact that the long-term effect is inhibited by PP2, wortmannin, PD, FR18, and IKK16 suggests that cSrc, PI3K, Erk1/2, and NF-kB are among the components included in the signaling pathways.

Global REACH 2018: High Altitude-Related Circulating Extracellular Microvesicles Promote a Proinflammatory Endothelial Phenotype In Vitro

Brewster, L. Madden, Anthony R. Bain, Vinicius P. Garcia, Noah M. DeSouza, Michael M. Tymko, Jared J. Greiner, and Philip N. Ainslie. Global REACH 2018: high altitude-related circulating extracellular microvesicles promote a proinflammatory endothelial phenotype in vitro. High Alt Med Biol. 24:223-229, 2023. Introduction: Ascent to high altitude (HA) can induce vascular dysfunction by promoting a proinflammatory endothelial phenotype. Circulating microvesicles (MVs) can mediate the vascular endothelium and inflammation. It is unclear whether HA-related MVs are associated with endothelial inflammation. Objectives: We tested the hypothesis that MVs derived from ascent to HA induce a proinflammatory endothelial phenotype. Methods: Ten healthy adults (8 M/2 F; age: 28 ± 2 years) residing at sea level (SL) were studied before and 4-6 days after rapid ascent to HA (4,300 m). MVs were isolated and enumerated from plasma by centrifugation and flow cytometry. Human umbilical vein endothelial cells were treated with MVs collected from each subject at SL (MV-SL) and at HA (MV-HA). Results: Circulating MV number significantly increased at HA (26,637 ± 3,315 vs. 19,388 ± 1,699). Although intracellular expression of total nuclear factor kappa beta (NF-κB; 83.4 ± 6.7 arbitrary units [AU] vs. 90.2 ± 6.9 AU) was not affected, MV-HA resulted in ∼55% higher (p < 0.05) active NF-κB (129.6 ± 19.8 AU vs. 90.7 ± 10.5 AU) expression compared with MV-SL. In addition, MV-HA induced higher interleukin (IL)-6 (63.9 ± 3.9 pg/ml vs. 53.3 ± 3.6 pg/ml) and IL-8 (140.2 ± 3.6 pg/ml vs. 120.7 ± 3.8 pg/ml) release compared with MV-SL, which was blunted with NF-κB blockade. Conclusions: Circulating extracellular MVs increase at HA and induce endothelial inflammation, potentially contributing to altitude-related vascular dysfunction.

Mechanism of TNFα-induced downregulation of salt-inducible kinase 2 in adipocytes

Salt-inducible kinase 2 (SIK2) is highly expressed in white adipocytes, but downregulated in individuals with obesity and insulin resistance. These conditions are often associated with a low-grade inflammation in adipose tissue. We and others have previously shown that SIK2 is downregulated by tumor necrosis factor α (TNFα), however, involvement of other pro-inflammatory cytokines, or the mechanisms underlying TNFα-induced SIK2 downregulation, remain to be elucidated. In this study we have shown that TNFα downregulates SIK2 protein expression not only in 3T3L1- but also in human in vitro differentiated adipocytes. Furthermore, monocyte chemoattractant protein-1 and interleukin (IL)-1β, but not IL-6, might also contribute to SIK2 downregulation during inflammation. We observed that TNFα-induced SIK2 downregulation occurred also in the presence of pharmacological inhibitors against several kinases involved in inflammation, namely c-Jun N-terminal kinase, mitogen activated protein kinase kinase 1, p38 mitogen activated protein kinase or inhibitor of nuclear factor kappa-B kinase (IKK). However, IKK may be involved in SIK2 regulation as we detected an increase of SIK2 when inhibiting IKK in the absence of TNFα. Increased knowledge about inflammation-induced downregulation of SIK2 could ultimately be used to develop strategies for the reinstalment of SIK2 expression in insulin resistance.

BET Inhibition Sensitizes Immunologically Cold Rb-Deficient Prostate Cancer to Immune Checkpoint Blockade

Non-T-cell-inflamed immunologically "cold" tumor microenvironments (TME) are associated with poor responsiveness to immune checkpoint blockade (ICB) and can be sculpted by tumor cell genomics. Here, we evaluated how retinoblastoma (Rb) tumor-suppressor loss-of-function (LOF), one of the most frequent alterations in human cancer and associated with lineage plasticity, poor prognosis, and therapeutic outcomes, alters the TME, and whether therapeutic strategies targeting the molecular consequences of Rb loss enhance ICB efficacy. We performed bioinformatics analysis to elucidate the impact of endogenous Rb LOF on the immune TME in human primary and metastatic tumors. Next, we used isogenic murine models of Rb-deficient prostate cancer for in vitro and in vivo mechanistic studies to examine how Rb loss and bromodomain and extraterminal (BET) domain inhibition (BETi) reprograms the immune landscape, and evaluated in vivo therapeutic efficacy of BETi, singly and in combination with ICB and androgen deprivation therapy. Rb loss was enriched in non-T-cell-inflamed tumors, and Rb-deficient murine tumors demonstrated decreased immune infiltration in vivo. The BETi JQ1 increased immune infiltration into the TME through enhanced tumor cell STING/NF-κB activation and type I IFN signaling within tumor cells, resulting in differential macrophage and T-cell-mediated tumor growth inhibition and sensitization of Rb-deficient prostate cancer to ICB. BETi can reprogram the immunologically cold Rb-deficient TME via STING/NF-κB/IFN signaling to sensitize Rb-deficient prostate cancer to ICB. These data provide the mechanistic rationale to test combinations of BETi and ICB in clinical trials of Rb-deficient prostate cancer.

ATP Consumption Is Coupled with Endocytosis in Exudated Neutrophils

Neutrophil energy metabolism during phagocytosis has been previously reported, and adenosine triphosphate (ATP) plays a crucial role in endocytosis. Neutrophils are prepared by intraperitoneal injection of thioglycolate for 4 h. We previously reported a system established for measuring particulate matter endocytosis by neutrophils using flow cytometry. In this study, we utilized this system to investigate the relationship between endocytosis and energy consumption in neutrophils. A dynamin inhibitor suppressed ATP consumption triggered by neutrophil endocytosis. In the presence of exogenous ATP, neutrophils behave differently during endocytosis depending on ATP concentration. The inhibition of ATP synthase and nicotinamide adenine dinucleotide phosphate oxidase but not phosphatidylinositol-3 kinase suppresses neutrophil endocytosis. The nuclear factor kappa B was activated during endocytosis and inhibited by I kappa B kinase (IKK) inhibitors. Notably, IKK inhibitors restored endocytosis-triggered ATP consumption. Furthermore, data from the NLR family pyrin domain containing three knockout mice suggest that inflammasome activation is not involved in neutrophil endocytosis or concomitant ATP consumption. To summarize, these molecular events occur via endocytosis, which is closely related to ATP-centered energy metabolism.

Targeting the NF-κB pathway enhances responsiveness of mammary tumors to JAK inhibitors

Interactions between tumor cells and the tumor microenvironment are critical for tumor growth, progression, and response to therapy. Effective targeting of oncogenic signaling pathways in tumors requires an understanding of how these therapies impact both tumor cells and cells within the tumor microenvironment. One such pathway is the janus kinase (JAK)/signal transducer and activator or transcription (STAT) pathway, which is activated in both breast cancer cells and in tumor associated macrophages. This study demonstrates that exposure of macrophages to JAK inhibitors leads to activation of NF-κB signaling, which results in increased expression of genes known to be associated with therapeutic resistance. Furthermore, inhibition of the NF-κB pathway improves the ability of ruxolitinib to reduce mammary tumor growth in vivo. Thus, the impact of the tumor microenvironment is an important consideration in studying breast cancer and understanding such mechanisms of resistance is critical to development of effective targeted therapies.

Ectopic CH60 mediates HAPLN1-induced cell survival signaling in multiple myeloma

Multiple myeloma (MM), the second most common hematological malignancy, is generally considered incurable because of the development of drug resistance. We previously reported that hyaluronan and proteoglycan link protein 1 (HAPLN1) produced by stromal cells induces activation of NF-κB, a tumor-supportive transcription factor, and promotes drug resistance in MM cells. However, the identity of the cell surface receptor that detects HAPLN1 and thereby engenders pro-tumorigenic signaling in MM cells remains unknown. Here, we performed an unbiased cell surface biotinylation assay and identified chaperonin 60 (CH60) as the direct binding partner of HAPLN1 on MM cells. Cell surface CH60 specifically interacted with TLR4 to evoke HAPLN1-induced NF-κB signaling, transcription of anti-apoptotic genes, and drug resistance in MM cells. Collectively, our findings identify a cell surface CH60-TLR4 complex as a HAPLN1 receptor and a potential molecular target to overcome drug resistance in MM cells.

Human ZBP1 induces cell death-independent inflammatory signaling via RIPK3 and RIPK1

ZBP1 is an interferon-induced cytosolic nucleic acid sensor that facilitates antiviral responses via RIPK3. Although ZBP1-mediated programmed cell death is widely described, whether and how it promotes inflammatory signaling is unclear. Here, we report a ZBP1-induced inflammatory signaling pathway mediated by K63- and M1-linked ubiquitin chains, which depends on RIPK1 and RIPK3 as scaffolds independently of cell death. In human HT29 cells, ZBP1 associated with RIPK1 and RIPK3 as well as ubiquitin ligases cIAP1 and LUBAC. ZBP1-induced K63- and M1-linked ubiquitination of RIPK1 and ZBP1 to promote TAK1- and IKK-mediated inflammatory signaling and cytokine production. Inhibition of caspase activity suppressed ZBP1-induced cell death but enhanced cytokine production in a RIPK1- and RIPK3 kinase activity-dependent manner. Lastly, we provide evidence that ZBP1 signaling contributes to SARS-CoV-2-induced cytokine production. Taken together, we describe a ZBP1-RIPK3-RIPK1-mediated inflammatory signaling pathway relayed by the scaffolding role of RIPKs and regulated by caspases, which may induce inflammation when ZBP1 is activated below the threshold needed to trigger a cell death response.

Ouabain-Induced Changes in the Expression of Voltage-Gated Potassium Channels in Epithelial Cells Depend on Cell-Cell Contacts

Ouabain is a cardiac glycoside, initially isolated from plants, and currently thought to be a hormone since some mammals synthesize it endogenously. It has been shown that in epithelial cells, it induces changes in properties and components related to apical-basolateral polarity and cell-cell contacts. In this work, we used a whole-cell patch clamp to test whether ouabain affects the properties of the voltage-gated potassium currents (Ik) of epithelial cells (MDCK). We found that: (1) in cells arranged as mature monolayers, ouabain induced changes in the properties of Ik; (2) it also accelerated the recovery of Ik in cells previously trypsinized and re-seeded at confluence; (3) in cell-cell contact-lacking cells, ouabain did not produce a significant change; (4) Na+/K+ ATPase might be the receptor that mediates the effect of ouabain on Ik; (5) the ouabain-induced changes in Ik required the synthesis of new nucleotides and proteins, as well as Golgi processing and exocytosis, as evidenced by treatment with drugs inhibiting those processes; and (5) the signaling cascade included the participation of cSrC, PI3K, Erk1/2, NF-κB and β-catenin. These results reveal a new role for ouabain as a modulator of the expression of voltage-gated potassium channels, which require cells to be in contact with themselves.

Inhibition of IκB Kinase Is a Potential Therapeutic Strategy to Circumvent Resistance to Epidermal Growth Factor Receptor Inhibition in Triple-Negative Breast Cancer Cells

Triple-negative breast cancer (TNBC) remains as an intractable malignancy with limited therapeutic targets. High expression of epidermal growth factor receptor (EGFR) has been associated with a poor prognosis of TNBC; however, EGFR targeting has failed with unfavorable clinical outcomes. Here, we performed a combinatorial screening of fifty-five protein kinase inhibitors with the EGFR inhibitor gefitinib in the TNBC cell line MDA-MB-231 and identified the IκB kinase (IKK) inhibitor IKK16 as a sensitizer of gefitinib. Cell viability and clonogenic survival assays were performed to evaluate the antiproliferative effects of the gefitinib and IKK16 (Gefitinib + IKK16) combination in TNBC cell lines. Western blot analyses were also performed to reveal the potential mode of action of this combination. In addition, next-generation sequencing (NGS) analysis was performed in Gefitinib+IKK16-treated cells. The Gefitinib+IKK16 treatment synergistically reduced cell viability and colony formation of TNBC cell lines such as HS578T, MDA-MB-231, and MDA-MB-468. This combination downregulated p-STAT3, p-AKT, p-mTOR, p-GSK3β, and p-RPS6. In addition, p-NF-κB and the total NF-κB were also regulated by this combination. Furthermore, NGS analysis revealed that NF-κB/RELA targets including CCL2, CXCL8, EDN1, IL-1β, IL-6, and SERPINE1 were further reduced and several potential tumor suppressors, such as FABP3, FADS2, FDFT1, SEMA6A, and PCK2, were synergistically induced by the Gefitinib-+IKK16 treatment. Taken together, we identified the IKK/NF-κB pathway as a potential target in combination of EGFR inhibition for treating TNBC.

Identification of Novel 2,4,5-Trisubstituted Pyrimidines as Potent Dual Inhibitors of Plasmodial PfGSK3/PfPK6 with Activity against Blood Stage Parasites In Vitro

Essential plasmodial kinases PfGSK3 and PfPK6 are considered novel drug targets to combat rising resistance to traditional antimalarial therapy. Herein, we report the discovery of IKK16 as a dual PfGSK3/PfPK6 inhibitor active against blood stage Pf3D7 parasites. To establish structure–activity relationships for PfPK6 and PfGSK3, 52 analogues were synthesized and assessed for the inhibition of PfGSK3 and PfPK6, with potent inhibitors further assessed for activity against blood and liver stage parasites. This culminated in the discovery of dual PfGSK3/PfPK6 inhibitors 23d (PfGSK3/PfPK6 IC₅₀ = 172/11 nM) and 23e (PfGSK3/PfPK6 IC₅₀ = 97/8 nM) with antiplasmodial activity (23dPf3D7 EC₅₀ = 552 ± 37 nM and 23ePf3D7 EC₅₀ = 1400 ± 13 nM). However, both compounds exhibited significant promiscuity when tested in a panel of human kinase targets. Our results demonstrate that dual PfPK6/PfGSK3 inhibitors with antiplasmodial activity can be identified and can set the stage for further optimization efforts.

Structural Insights and Development of LRRK2 Inhibitors for Parkinson's Disease in the Last Decade

Parkinson's disease (PD) is the second most prevalent neurodegenerative disease, characterized by the specific loss of dopaminergic neurons in the midbrain. The pathophysiology of PD is likely caused by a variety of environmental and hereditary factors. Many single-gene mutations have been linked to this disease, but a significant number of studies indicate that mutations in the gene encoding leucine-rich repeat kinase 2 (LRRK2) are a potential therapeutic target for both sporadic and familial forms of PD. Consequently, the identification of potential LRRK2 inhibitors has been the focus of drug discovery. Various investigations have been conducted in academic and industrial organizations to investigate the mechanism of LRRK2 in PD and further develop its inhibitors. This review summarizes the role of LRRK2 in PD and its structural details, especially the kinase domain. Furthermore, we reviewed in vitro and in vivo findings of selected inhibitors reported to date against wild-type and mutant versions of the LRRK2 kinase domain as well as the current trends researchers are employing in the development of LRRK2 inhibitors.

Mutations Affecting Genes in the Proximal T-Cell Receptor Signaling Pathway in Peripheral T-Cell Lymphoma

Simple Summary

The advent of next-generation sequencing (NGS) has allowed rapid advances in genomic studies on the pathogenesis and biology of peripheral T-cell lymphoma (PTCL). Recurrent mutations and fusions in genes related to the proximal TCR signaling pathway have been identified and show an important pathogenic role in PTCL. In this review, we summarize the genomic alterations in TCR signaling identified in different subgroups of PTCL patients and the functional impact of these alterations on TCR signaling and downstream pathways. We also discuss novel agents that could target TCR-related mutations and may hold promise for improving the treatment of PTCL.

Abstract

Peripheral T-cell lymphoma (PTCL) comprises a heterogeneous group of mature T-cell malignancies. Recurrent activating mutations and fusions in genes related to the proximal TCR signaling pathway have been identified in preclinical and clinical studies. This review summarizes the genetic alterations affecting proximal TCR signaling identified from different subgroups of PTCL and the functional impact on TCR signaling and downstream pathways. These genetic abnormalities include mostly missense mutations, occasional indels, and gene fusions involving CD28, CARD11, the GTPase RHOA, the guanine nucleotide exchange factor VAV1, and kinases including FYN, ITK, PLCG1, PKCB, and PI3K subunits. Most of these aberrations are activating mutations that can potentially be targeted by inhibitors, some of which are being tested in clinical trials that are briefly outlined in this review. Finally, we focus on the molecular pathology of recently identified subgroups of PTCL-NOS and highlight the unique genetic profiles associated with PTCL-GATA3.

Deficiency of PPP6C protects TNF-induced necroptosis through activation of TAK1

Necroptotic cell death is mediated by a super-molecular complex called necrosome which consists of receptor-interacting protein kinase 1 and 3 (RIPK1, RIPK3) and mixed-lineage kinase domain-like protein (MLKL). The role of these kinases has been extensively investigated in the regulation of necroptosis. However, whether the protein phosphatase is involved in necroptosis is still largely unknown. Here, we identified protein phosphatase 6 catalytic subunit (PPP6C) promotes TNF-induced necroptosis by genome-wide CRISPR/Cas9 library screening. We found that PPP6C deficiency protects cells from TNF-induced necroptosis in a phosphatase-activity-dependent manner. Mechanistically, PPP6C acts as a TGF-β activated kinase 1 (TAK1) phosphatase to inactivate its kinase activity. Deletion of PPP6C leads to hyperactivation of TAK1 and reduced RIPK1 kinase activity upon TNF stimulation. We further showed that heterozygous deletion of Ppp6c in mouse gastrointestinal tract alleviates necroptosis-related tissue injury and inflammation. Thus, our study identifies PPP6C as an important regulator of necroptosis and highlights a central role of phosphatase in the regulation of necroptosis-related diseases.

A scalable organoid model of human autosomal dominant polycystic kidney disease for disease mechanism and drug discovery

Human pluripotent stem-cell-derived organoids are models for human development and disease. We report a modified human kidney organoid system that generates thousands of similar organoids, each consisting of 1-2 nephron-like structures. Single-cell transcriptomic profiling and immunofluorescence validation highlighted patterned nephron-like structures utilizing similar pathways, with distinct morphogenesis, to human nephrogenesis. To examine this platform for therapeutic screening, the polycystic kidney disease genes PKD1 and PKD2 were inactivated by gene editing. PKD1 and PKD2 mutant models exhibited efficient and reproducible cyst formation. Cystic outgrowths could be propagated for months to centimeter-sized cysts. To shed new light on cystogenesis, 247 protein kinase inhibitors (PKIs) were screened in a live imaging assay identifying compounds blocking cyst formation but not overall organoid growth. Scaling and further development of the organoid platform will enable a broader capability for kidney disease modeling and high-throughput drug screens.

Unlocking the Untapped Potential of Endothelial Kinase and Phosphatase Involvement in Sepsis for Drug Treatment Design

Sepsis is a devastating clinical condition that can lead to multiple organ failure and death. Despite advancements in our understanding of molecular mechanisms underlying sepsis and sepsis-associated multiple organ failure, no effective therapeutic treatment to directly counteract it has yet been established. The endothelium is considered to play an important role in sepsis. This review highlights a number of signal transduction pathways involved in endothelial inflammatory activation and dysregulated endothelial barrier function in response to sepsis conditions. Within these pathways – NF-κB, Rac1/RhoA GTPases, AP-1, APC/S1P, Angpt/Tie2, and VEGF/VEGFR2 – we focus on the role of kinases and phosphatases as potential druggable targets for therapeutic intervention. Animal studies and clinical trials that have been conducted for this purpose are discussed, highlighting reasons why they might not have resulted in the expected outcomes, and which lessons can be learned from this. Lastly, opportunities and challenges that sepsis and sepsis-associated multiple organ failure research are currently facing are presented, including recommendations on improved experimental design to increase the translational power of preclinical research to the clinic.

IL-3-Induced Immediate Expression of c-fos and c-jun Is Modulated by the IKK2-JNK Axis

Interleukin (IL)-3 is a pleiotropic cytokine that regulates the survival, proliferation, and differentiation of hematopoietic cells. The binding of IL-3 to its receptor activates intracellular signaling, inducing transcription of immediate early genes (IEGs) such as c-fos, c-jun, and c-myc; however, transcriptional regulation under IL-3 signaling is not fully understood. This study assessed the role of the inhibitor of nuclear factor-κB kinases (IKKs) in inducing IL-3-mediated expression of IEGs. We show that IKK1 and IKK2 are required for the IL-3-induced immediate expression of c-fos and c-jun in murine hematopoietic Ba/F3 cells. Although IKK2 is well-known for its pivotal role as a regulator of the canonical nuclear factor-κB (NF-κB) pathway, activation of IKKs did not induce the nuclear translocation of the NF-κB transcription factor. We further revealed the important role of IKK2 in the activation of c-Jun N-terminal kinase (JNK), which mediates the IL-3-induced expression of c-fos and c-jun. These findings indicate that the IKK2-JNK axis modulates the IL-3-induced expression of IEGs in a canonical NF-κB-independent manner.

Whole-genome sequencing reveals that variants in the Interleukin 18 Receptor Accessory Protein 3'UTR protect against ALS

The noncoding genome is substantially larger than the protein-coding genome but has been largely unexplored by genetic association studies. Here, we performed region-based rare variant association analysis of >25,000 variants in untranslated regions of 6,139 amyotrophic lateral sclerosis (ALS) whole genomes and the whole genomes of 70,403 non-ALS controls. We identified interleukin-18 receptor accessory protein (IL18RAP) 3' untranslated region (3'UTR) variants as significantly enriched in non-ALS genomes and associated with a fivefold reduced risk of developing ALS, and this was replicated in an independent cohort. These variants in the IL18RAP 3'UTR reduce mRNA stability and the binding of double-stranded RNA (dsRNA)-binding proteins. Finally, the variants of the IL18RAP 3'UTR confer a survival advantage for motor neurons because they dampen neurotoxicity of human induced pluripotent stem cell (iPSC)-derived microglia bearing an ALS-associated expansion in C9orf72, and this depends on NF-κB signaling. This study reveals genetic variants that protect against ALS by reducing neuroinflammation and emphasizes the importance of noncoding genetic association studies.

USP8 inhibition reshapes an inflamed tumor microenvironment that potentiates the immunotherapy

Anti-PD-1/PD-L1 immunotherapy has achieved impressive therapeutic outcomes in patients with multiple cancer types. However, the underlined molecular mechanism(s) for moderate response rate (15–25%) or resistance to PD-1/PD-L1 blockade remains not completely understood. Here, we report that inhibiting the deubiquitinase, USP8, significantly enhances the efficacy of anti-PD-1/PD-L1 immunotherapy through reshaping an inflamed tumor microenvironment (TME). Mechanistically, USP8 inhibition increases PD-L1 protein abundance through elevating the TRAF6-mediated K63-linked ubiquitination of PD-L1 to antagonize K48-linked ubiquitination and degradation of PD-L1. In addition, USP8 inhibition also triggers innate immune response and MHC-I expression largely through activating the NF-κB signaling. Based on these mechanisms, USP8 inhibitor combination with PD-1/PD-L1 blockade significantly activates the infiltrated CD8⁺ T cells to suppress tumor growth and improves the survival benefit in several murine tumor models. Thus, our study reveals a potential combined therapeutic strategy to utilize a USP8 inhibitor and PD-1/PD-L1 blockade for enhancing anti-tumor efficacy.

The regulatory mechanisms of PD-L1 posttranslational modifications are not completely understood. Here the authors show that USP8 negatively regulates PD-L1 protein abundance by removing the K63-linked ubiquitination of PD-L1; while USP8 inhibition increases MHC-I expression and triggers anti-tumour immune responses through activating NF-κB signalling.

Constitutive, Basal, and β-Alanine-Mediated Activation of the Human Mas-Related G Protein-Coupled Receptor D Induces Release of the Inflammatory Cytokine IL-6 and Is Dependent on NF-κB Signaling

G protein-coupled receptors (GPCRs) have emerged as key players in regulating (patho)physiological processes, including inflammation. Members of the Mas-related G protein coupled receptors (MRGPRs), a subfamily of GPCRs, are largely expressed by sensory neurons and known to modulate itch and pain. Several members of MRGPRs are also expressed in mast cells, macrophages, and in cardiovascular tissue, linking them to pseudo-allergic drug reactions and suggesting a pivotal role in the cardiovascular system. However, involvement of the human Mas-related G-protein coupled receptor D (MRGPRD) in the regulation of the inflammatory mediator interleukin 6 (IL-6) has not been demonstrated to date. By stimulating human MRGPRD-expressing HeLa cells with the agonist β-alanine, we observed a release of IL-6. β-alanine-induced signaling through MRGPRD was investigated further by probing downstream signaling effectors along the Gαq/Phospholipase C (PLC) pathway, which results in an IkB kinases (IKK)-mediated canonical activation of nuclear factor kappa-B (NF-κB) and stimulation of IL-6 release. This IL-6 release could be blocked by a Gαq inhibitor (YM-254890), an IKK complex inhibitor (IKK-16), and partly by a PLC inhibitor (U-73122). Additionally, we investigated the constitutive (ligand-independent) and basal activity of MRGPRD and concluded that the observed basal activity of MRGPRD is dependent on the presence of fetal bovine serum (FBS) in the culture medium. Consequently, the dynamic range for IL-6 detection as an assay for β-alanine-mediated activation of MRGPRD is substantially increased by culturing the cells in FBS free medium before treatment. Overall, the observation that MRGPRD mediates the release of IL-6 in an in vitro system, hints at a role as an inflammatory mediator and supports the notion that IL-6 can be used as a marker for MRGPRD activation in an in vitro drug screening assay.

Small Molecule Inhibitors Targeting Nuclear Factor κB Activation Markedly Reduce Expression of Interleukin-2, but Not Interferon-γ, Induced by Phorbol Esters and Calcium Ionophores

The T-box transcription factor Eomesodermin (Eomes) promotes the expression of interferon-γ (IFN-γ). We recently reported that the small molecule inhibitors, TPCA-1 and IKK-16, which target nuclear factor κB (NF-κB) activation, moderately reduced Eomes-dependent IFN-γ expression in mouse lymphoma BW5147 cells stimulated with phorbol 12-myristate 13-acetate (PMA) and ionomycin (IM). In the present study, we investigated the direct effects of NF-κB on IFN-γ expression in mouse lymphoma EL4 cells and primary effector T cells. Eomes strongly promoted IFN-γ expression and the binding of RelA and NFATc2 to the IFN-γ promoter when EL4 cells were stimulated with PMA and IM. Neither TPCA-1 nor IKK-16 reduced IFN-γ expression; however, they markedly decreased interleukin (IL)-2 expression in Eomes-transfected EL4 cells. Moreover, TPCA-1 markedly inhibited the binding of RelA, but not that of Eomes or NFATc2 to the IFN-γ promoter. In effector CD4⁺ and CD8⁺ T cells activated with anti-CD3 and anti-CD28 antibodies, IFN-γ expression induced by PMA and A23187 was not markedly decreased by TPCA-1 or IKK-16 under conditions where IL-2 expression was markedly reduced. Therefore, the present results revealed that NF-κB is dispensable for IFN-γ expression induced by PMA and calcium ionophores in EL4 cells expressing Eomes and primary effector T cells.

Human Herpesvirus 6A Tegument Protein U14 Induces NF-κB Signaling by Interacting with p65

Viral infection induces host cells to mount a variety of immune responses, which may either limit viral propagation or create conditions conducive to virus replication in some instances. In this regard, activation of the NF-κB transcription factor is known to modulate virus replication. Human herpesvirus 6A (HHV-6A), which belongs to the Betaherpesvirinae subfamily, is frequently found in patients with neuroinflammatory diseases, although its role in disease pathogenesis has not been elucidated. In this study, we found that the HHV-6A-encoded U14 protein activates NF-κB signaling following interaction with the NF-κB complex protein, p65. Through induction of nuclear translocation of p65, U14 increases the expression of interleukin-6 (IL-6), IL-8, and monocyte chemoattractant protein 1 transcripts. We also demonstrated that activation of NF-κB signaling is important for HHV-6A replication, since inhibition of this pathway reduced virus protein accumulation and viral genome copy number. Taken together, our results suggest that HHV-6A infection activates the NF-κB pathway and promotes viral gene expression via late gene products, including U14. IMPORTANCE Human herpesvirus 6A (HHV-6A) is frequently found in patients with neuro-inflammation, although its role in the pathogenesis of this disease has not been elucidated. Most viral infections activate the NF-κB pathway, which causes the transactivation of various genes, including those encoding proinflammatory cytokines. Our results indicate that HHV-6A U14 activates the NF-κB pathway, leading to upregulation of proinflammatory cytokines. We also found that activation of the NF-κB transcription factor is important for efficient viral replication. This study provides new insight into HHV-6A U14 function in host cell signaling and identifies potential cellular targets involved in HHV-6A pathogenesis and replication.

IL-1β induces changes in expression of core circadian clock components PER2 and BMAL1 in primary human chondrocytes through the NMDA receptor/CREB and NF-κB signalling pathways

The circadian clock is a specialised cell signalling circuit present in almost all cells. It controls the timing of key cell activities such as proliferation and differentiation. In osteoarthritis, expression of two components of the circadian clock, BMAL1 and PER2 is altered in chondrocytes and this change has been causally linked with the increase in proliferation and altered chondrocyte differentiation in disease. IL-1β, an inflammatory cytokine abundant in OA joints, has previously been shown to induce changes in BMAL1 and PER2 expression in chondrocytes. The purpose of this study is to identify the mechanism involved. We found IL-1β treatment of primary human chondrocytes led to activation of NMDA receptors as evidenced by an increase in phosphorylation of GluN1 and an increase in intracellular calcium which was blocked by the NMDAR antagonist MK801. Levels of phosphorylated CREB were also elevated in IL-1β treated cells and this effect was blocked by co-treatment of cells with IL-1β and the NMDAR antagonist MK-801. Knockdown of CREB or inhibition of CREB activity prevented the IL-1β induced increase in PER2 expression in chondrocytes but had no effect on BMAL1. Phosphorylated p65 levels were elevated in IL-1β treated chondrocytes indicating increased NF-κB activation. Inhibition of NF-κB activity prevented the IL-1β induced reduction in BMAL1 expression and partially mitigated the IL-1β induced increase in PER2 expression in chondrocytes. These data indicate that the NMDAR/CREB and NF-κB signalling pathways regulate the core circadian clock components PER2 and BMAL1 in chondrocytes. Given that changes in expression of these clock components have been observed in a wide range of diseases, these findings may be broadly relevant for understanding the mechanism leading to circadian clock changes in pathology.

Radioresistance and Transcriptional Reprograming of Invasive Glioblastoma Cells

PURPOSE

Infiltrative growth pattern is a hallmark of glioblastoma (GBM). Radiation therapy aims to eradicate microscopic residual GBM cells after surgical removal of the visible tumor bulk. However, in-field recurrences remain the major pattern of therapy failure. We hypothesized that the radiosensitivity of peripheral invasive tumor cells (peri) may differ from the predominantly investigated tumor bulk.

METHODS AND MATERIALS

Invasive GBM populations were generated via debulking of the visible tumor core and serial orthotopic transplantation of peri cells, and sustained proinvasive phenotype of peri cells was confirmed in vitro by scratch assay and time lapse imaging. In parallel, invasive GBM cells were selected by transwell assay and from peri cells of patient-derived 3-dimensional spheroid cultures. Transcriptome analysis deciphered a GBM invasion-associated gene signature, and functional involvement of key pathways was validated by pharmacologic inhibition.

RESULTS

Compared with the bulk cells, invasive GBM populations acquired a radioresistant phenotype characterized by increased cell survival, reduced cell apoptosis, and enhanced DNA double-strand break repair proficiency. Transcriptome analysis revealed a reprograming of invasive cells toward augmented activation of epidermal growth factor receptor- and nuclear factor-κB-related pathways, whereas metabolic processes were downregulated. An invasive GBM score derived from this transcriptional fingerprint correlated well with patient outcome. Inhibition of epidermal growth factor receptor and nuclear factor-κB signaling resensitized invasive cells to irradiation. Invasive cells were eradicated with similar efficacy by particle therapy with carbon ions.

CONCLUSIONS

Our data indicate that invasive tumor cells constitute a phenotypically distinct and highly radioresistant GBM subpopulation with prognostic impact that may be vulnerable to targeted therapy and carbon ions.

Recent Approaches to Targeting Canonical NFκB Signaling in the Early Inflammatory Response to Renal IRI

Ischemia reperfusion injury (IRI) is the most common cause of in-hospital AKI and is associated with increased morbidity and mortality. IRI is associated with an early phase of inflammation primarily regulated by the canonical NFκB signaling pathway. Despite recent advances in our understanding of the pathogenesis of IRI, few therapeutic strategies have emerged. The purpose of this manuscript is to review interventions targeting NFκB after IRI.

Structure of the Mycobacterium tuberculosis cPknF and conformational changes induced in forkhead-associated regulatory domains

Mycobacterium tuberculosis (Mtb) has 11 Serine-Threonine Protein Kinases (STPK) that control numerous physiological processes, including cell growth, cell division, metabolic flow, and transcription. PknF is one of the 11 Mtb STPKs that has, among other substrates, two FHA domains (FHA-1 and FHA-2) of the ATP-Binding Cassette (ABC) transporter Rv1747. Phosphorylation in T152 and T210 located in a non-structured linker that connects Rv1747 FHA domains is considerate to be the regulatory mechanism of the transporter. In this work, we resolved the three-dimensional structure of the PknF catalytic domain (cPknF) in complex with the human kinase inhibitor IKK16. cPknF is conserved when compared to other STPKs but shows specific residues in the binding site where the inhibitor is positioned. In addition, using Small Angle X-Ray Scattering analysis we monitored the behavior of the wild type and three FHA-phosphomimetic mutants in solution, and measured the cPknF affinity for these domains. The kinase showed higher affinity for the non-phosphorylated wild type domain and preference for phosphorylation of T152 inducing the rapprochement of the domains and significant structural changes. The results shed some light on the process of regulating the transporter's activity by phosphorylation and arises important questions about evolution and importance of this mechanism for the bacillus.

•

Rv1747 is an ABC transporter which activity is regulated by PknF.

•

cPknF is a typical Serine/Threonine Protein Kinase that can be explored as drug target.

•

The higher affinity of cPknF for FHA-2 is important for further conformational changes.

•

Rv1747 activation model reveals a concatenated activity essential for the system.

Stromal Cell-Contact Dependent PI3K and APRIL Induced NF-κB Signaling Prevent Mitochondrial- and ER Stress Induced Death of Memory Plasma Cells

The persistence of long-lived memory plasma cells in the bone marrow depends on survival factors available in the bone marrow, which are provided in niches organized by stromal cells. Using an ex vivo system in which we supply the known survival signals, direct cell contact to stromal cells, and the soluble cytokine a proliferation-inducing ligand (APRIL), we have elucidated the critical signaling pathways required for the survival of long-lived plasma cells. Integrin-mediated contact of bone marrow plasma cells with stromal cells activates the phosphatidylinositol 3-kinase (PI3K) signaling pathway, leading to critical inactivation of Forkhead-Box-Protein O1/3 (FoxO1/3) and preventing the activation of mitochondrial stress-associated effector caspases 3 and 7. Accordingly, inhibition of PI3K signaling in vivo ablates bone marrow plasma cells. APRIL signaling, by the nuclear factor κB (NF-κB) pathway, blocks activation of the endoplasmic-reticulum-stress-associated initiator caspase 12. Thus, stromal-cell-contact-induced PI3K and APRIL-induced NF-κB signaling provide the necessary and complementary signals to maintain bone marrow memory plasma cells.

IL-3 is essential for ICOS-L stabilization on mast cells, and sustains the IL-33-induced RORγt+ Treg generation via enhanced IL-6 induction

IL-33 is a member of the IL-1 family. By binding to its receptor ST2 (IL-33R) on mast cells, IL-33 induces the MyD88-dependent activation of the TAK1-IKK2 signalling module resulting in activation of the MAP kinases p38, JNK1/2 and ERK1/2, and of NFκB. Depending on the kinases activated in these pathways, the IL-33-induced signalling is essential for production of IL-6 or IL-2. This was shown to control the dichotomy between RORγt+ and Helios+ Tregs , respectively. SCF, the ligand of c-Kit (CD117), can enhance these effects. Here, we show that IL-3, another growth factor for mast cells, is essential for the expression of ICOS-L on BMMCs, and costimulation with IL-3 potentiated the IL-33-induced IL-6 production similar to SCF. In contrast to the enhanced IL-2 production by SCF-induced modulation of the IL-33 signalling, IL-3 blocked the production of IL-2. Consequently, IL-3 shifted the IL-33-induced Treg dichotomy towards RORγt+ Tregs at the expense of RORγt- Helios+ Tregs . However, ICOS-L expression was downregulated by IL-33. In line with that, ICOS-L did not play any important role in the Treg modulation by IL-3/IL-33-activated mast cells. These findings demonstrate that different from the mast cell growth factor SCF, IL-3 can alter the IL-33-induced and mast cell-dependent regulation of Treg subpopulations by modulating mast cell-derived cytokine profiles.

Effects of NF-kB Signaling Inhibitors on Bed Bug Resistance to Orally Provisioned Entomopathogenic Bacteria

Bed bugs are globally important pests and there is an ongoing need for the development and improvement of bed bug control tools. Though promising against other insect pests, the exploration of biological methods for bed bug control is limited. Previously, we identified several species of bacteria that have entomopathogenic effects against bed bugs when ingested. We also described the conservation of several antibacterial responses in bed bugs, including the expression of immune effector genes regulated by NF-kB transcription factors through the Toll and immune deficiency (IMD) signaling pathways. Accordingly, we predicted that chemical inhibition of NF-kB signaling could reduce bed bug resistance to orally provisioned entomopathogenic bacteria, potentially improving their effectiveness as biological control agents. In the present study, we administered four small molecule inhibitors of NF-kB signaling (BMS345541, IKK16, IMD0354, Takinib) to bed bugs by feeding them in a blood meal. We then quantified basal mortality and mortality in response to oral infection with two different entomopathogenic bacteria (Pseudomonas entomophila and Bacillus thuringiensis israelensis). None of the NF-kB signaling inhibitors tested increased mortality above control levels when administered alone, suggesting a lack of direct toxicity. However, one inhibitor (IKK16) significantly enhanced the rate of mortality from oral infection with P. entomophila. Enhanced mortality was independent of direct effects of IKK16 on P. entomophila growth in vitro but was associated with higher bacterial loads in vivo (i.e., reduced resistance). Together, these results provide new insight into the regulation of the bed bug immune system and suggest that administration of entomopathogens in combination with inhibition of immune signaling pathways to reduce infection resistance may be effective for biological control of bed bugs.

Global REACH 2018: dysfunctional extracellular microvesicles in Andean highlander males with excessive erythrocytosis

High altitude-related excessive erythrocytosis (EE) is associated with increased cardiovascular risk. The experimental aim of this study was to determine the effects of microvesicles isolated from Andean highlanders with EE on endothelial cell inflammation, oxidative stress, apoptosis, and nitric oxide (NO) production. Twenty-six male residents of Cerro de Pasco, Peru (4,340 m), were studied: 12 highlanders without EE (age: 40 ± 4 yr; BMI: 26.4 ± 1.7; Hb: 17.4 ± 0.5 g/dL, Spo₂: 86.9 ± 1.0%) and 14 highlanders with EE (43 ± 4 yr; 26.2 ± 0.9; 24.4 ± 0.4 g/dL; 79.7 ± 1.6%). Microvesicles were isolated, enumerated, and collected from plasma by flow cytometry. Human umbilical vein endothelial cells were cultured and treated with microvesicles from highlanders without and with EE. Microvesicles from highlanders with EE induced significantly higher release of interleukin (IL)-6 (89.8 ± 2.7 vs. 77.1 ± 1.9 pg/mL) and IL-8 (62.0 ± 2.7 vs. 53.3 ± 2.2 pg/mL) compared with microvesicles from healthy highlanders. Although intracellular expression of total NF-κB p65 (65.3 ± 6.0 vs. 74.9 ± 7.8.9 AU) was not significantly affected in cells treated with microvesicles from highlanders without versus with EE, microvesicles from highlanders with EE resulted in an ∼25% higher (P < 0.05) expression of p-NF-κB p65 (173.6 ± 14.3 vs. 132.8 ± 12.2 AU). Cell reactive oxygen species production was significantly higher (76.4.7 ± 5.4 vs. 56.7 ± 1.7% of control) and endothelial nitric oxide synthase (p-eNOS) activation (231.3 ± 15.5 vs. 286.6 ± 23.0 AU) and NO production (8.3 ± 0.6 vs. 10.7 ± 0.7 μM/L) were significantly lower in cells treated with microvesicles from highlanders with versus without EE. Cell apoptotic susceptibility was not significantly affected by EE-related microvesicles. Circulating microvesicles from Andean highlanders with EE increased endothelial cell inflammation and oxidative stress and reduced NO production.NEW & NOTEWORTHY In this study, we determined the effects of microvesicles isolated from Andean highlanders with excessive erythrocytosis (EE) on endothelial cell inflammation, oxidative stress, apoptosis, and NO production. Microvesicles from highlanders with EE induced a dysfunctional response from endothelial cells characterized by increased cytokine release and expression of active nuclear factor-κB and reduced nitric oxide production. Andean highlanders with EE exhibit dysfunctional circulating extracellular microvesicles that induce a proinflammatory, proatherogenic endothelial phenotype.

Dual Inhibition of AKT and MEK Pathways Potentiates the Anti-Cancer Effect of Gefitinib in Triple-Negative Breast Cancer Cells

There is an unmet medical need for the development of new targeted therapeutic strategies for triple-negative breast cancer (TNBC). With drug combination screenings, we found that the triple combination of the protein kinase inhibitors (PKIs) of the epidermal growth factor receptor (EGFR), v-akt murine thymoma viral oncogene homolog (AKT), and MAPK/ERK kinase (MEK) is effective in inducing apoptosis in TNBC cells. A set of PKIs were first screened in combination with gefitinib in the TNBC cell line, MDA-MB-231. The AKT inhibitor, AT7867, was identified and further analyzed in two mesenchymal stem-like (MSL) subtype TNBC cells, MDA-MB-231 and HS578T. A combination of gefitinib and AT7867 reduced the proliferation and long-term survival of MSL TNBC cells. However, gefitinib and AT7867 induced the activation of the rat sarcoma (RAS)/ v-raf-1 murine leukemia viral oncogene homolog (RAF)/MEK/ extracellular signal-regulated kinase (ERK) pathway. To inhibit this pathway, MEK/ERK inhibitors were further screened in MDA-MB-231 cells in the presence of gefitinib and AT7867. As a result, we identified that the MEK inhibitor, PD-0325901, further enhanced the anti-proliferative and anti-clonogenic effects of gefitinib and AT7867 by inducing apoptosis. Our results suggest that the dual inhibition of the AKT and MEK pathways is a novel potential therapeutic strategy for targeting EGFR in TNBC cells.

C11orf95-RELA fusion drives aberrant gene expression through the unique epigenetic regulation for ependymoma formation

Recurrent C11orf95-RELA fusions (RELA^FUS) are the hallmark of supratentorial ependymomas. The presence of RELA as the fusion partner indicates a close association of aberrant NF-κB activity with tumorigenesis. However, the oncogenic role of the C11orf95 has not been determined. Here, we performed ChIP-seq analyses to explore genomic regions bound by RELA^FUS and H3K27ac proteins in human 293T and mouse ependymoma cells. We then utilized published RNA-Seq data from human and mouse RELA^FUS tumors and identified target genes that were directly regulated by RELA^FUS in these tumors. Subsequent transcription factor motif analyses of RELA^FUS target genes detected a unique GC-rich motif recognized by the C11orf95 moiety, that is present in approximately half of RELA^FUS target genes. Luciferase assays confirmed that a promoter carrying this motif is sufficient to drive RELA^FUS-dependent gene expression. Further, the RELA^FUS target genes were found to be overlapped with Rela target genes primarily via non-canonical NF-κB binding sites. Using a series of truncation and substitution mutants of RELA^FUS, we also show that the activation domain in the RELA^FUS moiety is necessary for the regulation of gene expression of these RELA^FUS target genes. Lastly, we performed an anti-cancer drug screening with mouse ependymoma cells and identified potential anti-ependymoma drugs that are related to the oncogenic mechanism of RELA^FUS. These findings suggested that RELA^FUS might induce ependymoma formation through oncogenic pathways orchestrated by both C11orf95 and RELA target genes. Thus, our study unveils a complex gene function of RELA^FUS as an oncogenic transcription factor in RELA^FUS positive ependymomas.

FYN-TRAF3IP2 induces NF-κB signaling-driven peripheral T cell lymphoma

Angioimmunoblastic T cell lymphoma (AITL) and peripheral T cell lymphoma not-otherwise-specified (PTCL, NOS) have poor prognosis and lack driver actionable targets for directed therapies in most cases. Here we identify FYN-TRAF3IP2 as a recurrent oncogenic gene fusion in AITL and PTCL, NOS tumors. Mechanistically, we show that FYN-TRAF3IP2 leads to aberrant NF-κB signaling downstream of T cell receptor activation. Consistent with a driver oncogenic role, FYN-TRAF3IP2 expression in hematopoietic progenitors induces NF-κB-driven T cell transformation in mice and cooperates with loss of the Tet2 tumor suppressor in PTCL development. Moreover, abrogation of NF-κB signaling in FYN-TRAF3IP2-induced tumors with IκB kinase inhibitors delivers strong anti-lymphoma effects in vitro and in vivo. These results demonstrate an oncogenic and pharmacologically targetable role for FYN-TRAF3IP2 in PTCLs and call for the clinical testing of anti-NF-κB targeted therapies in these diseases.

Leveraging Uncertainty in Machine Learning Accelerates Biological Discovery and Design

Machine learning that generates biological hypotheses has transformative potential, but most learning algorithms are susceptible to pathological failure when exploring regimes beyond the training data distribution. A solution to address this issue is to quantify prediction uncertainty so that algorithms can gracefully handle novel phenomena that confound standard methods. Here, we demonstrate the broad utility of robust uncertainty prediction in biological discovery. By leveraging Gaussian process-based uncertainty prediction on modern pre-trained features, we train a model on just 72 compounds to make predictions over a 10,833-compound library, identifying and experimentally validating compounds with nanomolar affinity for diverse kinases and whole-cell growth inhibition of Mycobacterium tuberculosis. Uncertainty facilitates a tight iterative loop between computation and experimentation and generalizes across biological domains as diverse as protein engineering and single-cell transcriptomics. More broadly, our work demonstrates that uncertainty should play a key role in the increasing adoption of machine learning algorithms into the experimental lifecycle.

Targeting AGTR1/NF-κB/CXCR4 axis by miR-155 attenuates oncogenesis in glioblastoma

Glioblastoma (GBM) represents the most aggressive malignancy of the central nervous system. Increased expression of Angiotensin II Receptor Type 1 (AGTR1) has been associated with proliferative and infiltrative properties of glioma cells. However, the underlying mechanism of AGTR1 upregulation in GBM is still unexplored. To understand the post-transcriptional regulation of AGTR1 in GBM, we screened 3'untranslated region (3'UTR) of AGTR1 for putative miRNA binding by using prediction algorithms. Interestingly, miR-155 showed conserved binding on the 3'UTR of AGTR1, subsequently confirmed by luciferase reporter assay. Furthermore, miR-155 overexpressing GBM cells show decrease in AGTR1 expression accompanied with reduced cell proliferation, invasion, foci formation and anchorage-independent growth. Strikingly, immunodeficient mice implanted with stable miR-155 overexpressing SNB19 cells show negligible tumor growth. Notably, miR-155 attenuates NF-κB signaling downstream of AGTR1 leading to reduced CXCR4 as well as AGTR1 levels. Mechanistically, miR-155 mitigates AGTR1-mediated angiogenesis, epithelial-to-mesenchymal transition, stemness, and MAPK signaling. Similar effects were observed by using pharmacological inhibitor of IκB Kinase (IKK) complex in multiple cell-based assays. Taken together, we established that miRNA-155 post-transcriptionally regulates AGTR1 expression, abrogates AGTR1/NF-κB/CXCR4 signaling axis and elicits pleiotropic anticancer effects in GBM. This study opens new avenues for using IKK inhibitors and miRNA-155 replacement therapies for the treatment of AGTR1-positive malignancies.

PIM Kinase Inhibitors Block the Growth of Primary T-cell Acute Lymphoblastic Leukemia: Resistance Pathways Identified by Network Modeling Analysis

Despite significant progress in understanding the genetic landscape of T-cell acute lymphoblastic leukemia (T-ALL), the discovery of novel therapeutic targets has been difficult. Our results demonstrate that the levels of PIM1 protein kinase is elevated in early T-cell precursor ALL (ETP-ALL) but not in mature T-ALL primary samples. Small-molecule PIM inhibitor (PIMi) treatment decreases leukemia burden in ETP-ALL. However, treatment of animals carrying ETP-ALL with PIMi was not curative. To model other pathways that could be targeted to complement PIMi activity, HSB-2 cells, previously characterized as a PIMi-sensitive T-ALL cell line, were grown in increasing doses of PIMi. Gene set enrichment analysis of RNA sequencing data and functional enrichment of network modules demonstrated that the HOXA9, mTOR, MYC, NFκB, and PI3K-AKT pathways were activated in HSB-2 cells after long-term PIM inhibition. Reverse phase protein array-based pathway activation mapping demonstrated alterations in the mTOR, PI3K-AKT, and NFκB pathways, as well. PIMi-tolerant HSB-2 cells contained phosphorylated RelA-S536 consistent with activation of the NFκB pathway. The combination of NFκB and PIMis markedly reduced the proliferation in PIMi-resistant leukemic cells showing that this pathway plays an important role in driving the growth of T-ALL. Together these results demonstrate key pathways that are activated when HSB-2 cell line develop resistance to PIMi and suggest pathways that can be rationally targeted in combination with PIM kinases to inhibit T-ALL growth.

The NF-κB Pathway Promotes Tamoxifen Tolerance and Disease Recurrence in Estrogen Receptor-Positive Breast Cancers

The purpose of this study was to identify critical pathways promoting survival of tamoxifen-tolerant, estrogen receptor α positive (ER+) breast cancer cells, which contribute to therapy resistance and disease recurrence. Gene expression profiling and pathway analysis were performed in ER+ breast tumors of patients before and after neoadjuvant tamoxifen treatment and demonstrated activation of the NF-κB pathway and an enrichment of epithelial-to mesenchymal transition (EMT)/stemness features. Exposure of ER+ breast cancer cell lines to tamoxifen, in vitro and in vivo, gives rise to a tamoxifen-tolerant population with similar NF-κB activity and EMT/stemness characteristics. Small-molecule inhibitors and CRISPR/Cas9 knockout were used to assess the role of the NF-κB pathway and demonstrated that survival of tamoxifen-tolerant cells requires NF-κB activity. Moreover, this pathway was essential for tumor recurrence following tamoxifen withdrawal. These findings establish that elevated NF-κB activity is observed in breast cancer cell lines under selective pressure with tamoxifen in vitro and in vivo, as well as in patient tumors treated with neoadjuvant tamoxifen therapy. This pathway is essential for survival and regrowth of tamoxifen-tolerant cells, and, as such, NF-κB inhibition offers a promising approach to prevent recurrence of ER+ tumors following tamoxifen exposure. IMPLICATIONS: Understanding initial changes that enable survival of tamoxifen-tolerant cells, as mediated by NF-κB pathway, may translate into therapeutic interventions to prevent resistance and relapse, which remain major causes of breast cancer lethality.

Therapeutic effects of IkB kinase inhibitor during systemic inflammation

Animal models of inflammatory diseases support the idea that nuclear factor κB (NF-κB) activation plays a pathophysiological role and is widely implicated in multiple organ dysfunction (MOD). Indeed, the inhibition of the IκB kinase (IKK) complex, involved in the NF-κB pathway, can represent a promising approach to prevent MOD. The present work employed a rat model of systemic inflammation to investigate the preventive effects of Inhibitor of IKK complex (IKK16). In male Wistar rats, systemic inflammation was induced by a tail vein injection of lipopolysaccharides (LPS challenge; 12 mg/kg). Treatment with IKK16 (1 mg/kg body weight) was administered, by tail vein, 15 min post-LPS. Age- and sex-matched healthy rats and LPS rats without treatment were used as controls. At 24 h post-IKK16 treatment, serum enzyme levels indicative of liver, kidney, pancreas and muscle function were evaluated by biochemical analysis, and RT-PCR technique was used to analyze gene expression of pro-inflammatory cytokines. Hemodynamic parameters were also considered to assess the LPS-induced inflammation. IKK16 treatment yielded a strong therapeutic effect in preventing LPS-induced elevation of serological enzyme levels, attenuating hepatic, renal, pancreatic and muscular dysfunction after LPS challenge. Moreover, as expected, LPS promoted a significantly overexpression of TNF-α, IL-6 and IL-1β in the heart, kidney, and liver; which was diminished by IKK16 treatment. The present study provides convincing evidence that selective inhibition of the IκB kinase complex through the action of IKK16, plays a protective role against LPS-induced multiple organ dysfunction by reducing the acute inflammatory response induced by endotoxin exposure.

PTPIP51 crosslinks the NFκB signaling and the MAPK pathway in SKBR3 cells

Aim:

PTPIP51 interacts with NFκB signaling at the RelA and IκB level. NFκB signaling is linked to the initiation, progression and metastasis of breast cancer. Her2-amplified breast cancer cells frequently display activation of the NFκB signaling. We aimed to clarify the effects of NFκB inhibition on the NFκB- and MAPK-related interactome of PTPIP51 and cell viability in HaCat cells and SKBR3 cells.

Results:

IKK-16 selectively reduced cell viability in SKBR3 cells. PDTC induced a formation of the Raf1/14-3-3/PTPIP51 complex in SKBR3 cells, indicating a shift of PTPIP51 into MAPK signaling.

Conclusion:

IKK-16 selectively inhibits cell viability of SKBR3 cells. In addition, PTPIP51 might serve as the mediator between NFκB signaling and the MAPK pathway in SKBR3.

Breast cancer is the most common cancerous disease among women. Prognosis and therapy of breast cancer depends on the expression of hormone and surface receptors such as Her2, which promote tumor growth and invasion via activation of downstream signaling pathways. NFκB signaling represents a downstream signaling pathway that can be activated by Her2. In this study, we demonstrated that inhibition of NFκB signaling with IKK-16 reduces cell viability in breast cancer cells with amplified Her2. Furthermore, we identified PTPIP51 as a potential mediator of crosstalks between the MAPK pathway and NFκB signaling. This signaling pathway could therefore be a target for future drug development.

In vitro benchmarking of NF-κB inhibitors

Dysregulated activity of the transcription factors of the nuclear factor κb (NF-κB) family has been implicated in numerous cancer types, inflammatory diseases, autoimmune disease, and other disorders. As such, selective NF-κB pathway inhibition is an attractive target to researchers for preclinical and clinical drug development. A plethora of commercially and clinically available inhibitors claim to be NF-κB specific; however, such claims of specificity are rarely quantitative or benchmarked, making the biomedical literature difficult to contextualize. This imprecision is worsened because some NF-κB reporter systems have low signal-to-noise ratios. Herein, we use a robust, defined, commercially available reporter system to benchmark NF-κB agonists and antagonists for the field. We also functionally characterize a RELA fusion-positive ependymoma cell culture with validated NF-κB inhibitor compounds.

Mechanistic and therapeutic study of novel anti-tumor function of natural compound imperialine for treating non-small cell lung cancer

ETHNOPHARMACOLOGICAL RELEVANCE

Bulbus Fritillaria cirrhosa D. Don (BFC) is a Chinese traditional herbal medicine that has long been used as an indispensable component in herbal prescriptions for bronchopulmonary diseases due to its well-established strong anti-inflammation and pulmonary harmonizing effects. Interestingly, there are few case reports in traditional Chinese medicine available where they found it to contribute in anti-tumor therapies. Imperialine is one of the most favored active substances extracted from BFC and has been widely recognized as an anti-inflammatory agent.

AIM OF THE STUDY

The aim of the current work is to provide first-hand evidences both in vitro and in vivo showing that imperialine exerts anti-cancer effects against non-small cell lung cancer (NSCLC), and to explore the molecular mechanism of this anti-tumor activity. It is also necessary to examine its systemic toxicity, and to investigate how to develop strategies for feasible clinical translation of imperialine.

MATERIALS AND METHODS

To investigate anti-NSCLC efficacy of imperialine using both in vitro and in vivo methods where A549 cell line were chosen as in vitro model NSCLC cells and A549 tumor-bearing mouse model was constructed for in vivo study. The detailed underlying anti-cancer mechanism has been systematically explored for the first time through a comprehensive set of molecular biology methods mainly including immunohistochemistry, western blot and enzyme-linked immunosorbent assays. The toxicity profile of imperialine treatments were evaluated using healthy nude mice by examining hemogram and histopathology. An imperialine-loaded liposomal drug delivery system was developed using thin film hydration method to evaluate target specific delivery.

RESULTS

The results showed that imperialine could suppress both NSCLC tumor and associated inflammation through an inflammation-cancer feedback loop in which NF-κB activity was dramatically inhibited by imperialine. The NSCLC-targeting liposomal system was successfully developed for targeted drug delivery. The developed platform could favorably enhance imperialine cellular uptake and in vivo accumulation at tumor sites, thus improving overall anti-tumor effect. The toxicity assays revealed imperialine treatments did not significantly disturb blood cell counts in mice or exert any significant damage to the main organs.

CONCLUSIONS

Imperialine exerts anti-cancer effects against NSCLC both in vitro and in vivo, and this previously unknown function is related to NF-κB centered inflammation-cancer feedback loop. Imperialine mediated anti-cancer activity is not through cytotoxicity and exhibit robust systemic safety. Furthermore, the liposome-based system we commenced would dramatically enhance therapeutic effects of imperialine while exhibiting extremely low side effects both on cellular and in NSCLC model. This work has identified imperialine as a promising novel anti-cancer compound and offered an efficient target-delivery solution that greatly facilitate practical use of imperialine.

Proteasome Composition in Cytokine-Treated Neurons and Astrocytes is Determined Mainly by Subunit Displacement

In this study, we investigated if subunit displacement and/or alterations in proteasome biosynthesis are responsible for the changes in the levels of constitutive proteasomes (c-20S), immunoproteasomes (i-20S) and the activators PA28 and PA700 in neurons and astrocytes cultured with a cytokine mixture (IFN-γ/TNF-α/IL-1β). Exposure of both cell types to cytokines for 24 h increases mRNA and protein expression of the i-20S-specific subunit β5i and PA28α/β, and leads to a decline in the amount of the c-20S-specific subunit β5. Since β5 mRNA levels are unchanged by the cytokine treatment, it is fair to conclude that displacement of constitutive β-subunits with inducible β5i subunits is likely the mechanism underlying the decrease in c-20S. As expected, the increase in the amount of the IFN-γ-inducible subunits coincides with elevated expression of phospho-STAT-1 and interferon regulatory factor-1 (IRF-1). However, inhibition of NF-κB signaling in cytokine-treated astrocytes reduces IRF-1 expression without affecting that of i-20S, c-20S and PA28. This suggests that STAT-1 is capable of increasing the transcription of i20S-specific subunits and PA28α/β by itself. The lack of a decrease in proteasome β5 mRNA expression is consistent with the fact that Nrf1 (Nfe2l1) and Nrf2 (Nfe2l2) levels are not reduced by pro-inflammatory cytokines. In contrast, we previously found that there is a significant Nrf1 dysregulation and reduced β5 mRNA expression in the spinal cords of mice with experimental autoimmune encephalomyelitis (EAE). Thus, there are stressors in EAE, other than a pro-inflammatory environment, that are not present in cytokine-treated cells.

A homogeneous bioluminescent immunoassay to probe cellular signaling pathway regulation

Monitoring cellular signaling events can help better understand cell behavior in health and disease. Traditional immunoassays to study proteins involved in signaling can be tedious, require multiple steps, and are not easily adaptable to high throughput screening (HTS). Here, we describe a new immunoassay approach based on bioluminescent enzyme complementation. This immunoassay takes less than two hours to complete in a homogeneous "Add and Read" format and was successfully used to monitor multiple signaling pathways' activation through specific nodes of phosphorylation (e.g pIκBα, pAKT, and pSTAT3). We also tested deactivation of these pathways with small and large molecule inhibitors and obtained the expected pharmacology. This approach does not require cell engineering. Therefore, the phosphorylation of an endogenous substrate is detected in any cell type. Our results demonstrate that this technology can be broadly adapted to streamline the analysis of signaling pathways of interest or the identification of pathway specific inhibitors.

Dimethyl fumarate potentiates oncolytic virotherapy through NF-κB inhibition

Resistance to oncolytic virotherapy is frequently associated with failure of tumor cells to get infected by the virus. Dimethyl fumarate (DMF), a common treatment for psoriasis and multiple sclerosis, also has anticancer properties. We show that DMF and various fumaric and maleic acid esters (FMAEs) enhance viral infection of cancer cell lines as well as human tumor biopsies with several oncolytic viruses (OVs), improving therapeutic outcomes in resistant syngeneic and xenograft tumor models. This results in durable responses, even in models otherwise refractory to OV and drug monotherapies. The ability of DMF to enhance viral spread results from its ability to inhibit type I interferon (IFN) production and response, which is associated with its blockade of nuclear translocation of the transcription factor nuclear factor κB (NF-κB). This study demonstrates that unconventional application of U.S. Food and Drug Administration-approved drugs and biological agents can result in improved anticancer therapeutic outcomes.