Protein kinase C beta controls nuclear factor kappaB activation in B cells through selective regulation of the IkappaB kinase alpha

Mitochondrial-targeted antioxidant attenuates preeclampsia-like phenotypes induced by syncytiotrophoblast-specific Gαq signaling

Syncytiotrophoblast stress is theorized to drive development of preeclampsia, but its molecular causes and consequences remain largely undefined. Multiple hormones implicated in preeclampsia signal via the Gαq cascade, leading to the hypothesis that excess Gαq signaling within the syncytiotrophoblast may contribute. First, we present data supporting increased Gαq signaling and antioxidant responses within villous and syncytiotrophoblast samples of human preeclamptic placenta. Second, Gαq was activated in mouse placenta using Cre-lox and DREADD methodologies. Syncytiotrophoblast-restricted Gαq activation caused hypertension, kidney damage, proteinuria, elevated circulating proinflammatory factors, decreased placental vascularization, diminished spiral artery diameter, and augmented responses to mitochondrial-derived superoxide. Administration of the mitochondrial-targeted antioxidant Mitoquinone attenuated maternal proteinuria, lowered circulating inflammatory and anti-angiogenic mediators, and maintained placental vascularization. These data demonstrate a causal relationship between syncytiotrophoblast stress and the development of preeclampsia and identify elevated Gαq signaling and mitochondrial reactive oxygen species as a cause of this stress.

Ellagic Acid and Cancer Hallmarks: Insights from Experimental Evidence

Cancer is a complex and multifaceted disease with a high global incidence and mortality rate. Although cancer therapy has evolved significantly over the years, numerous challenges persist on the path to effectively combating this multifaceted disease. Natural compounds derived from plants, fungi, or marine organisms have garnered considerable attention as potential therapeutic agents in the field of cancer research. Ellagic acid (EA), a natural polyphenolic compound found in various fruits and nuts, has emerged as a potential cancer prevention and treatment agent. This review summarizes the experimental evidence supporting the role of EA in targeting key hallmarks of cancer, including proliferation, angiogenesis, apoptosis evasion, immune evasion, inflammation, genomic instability, and more. We discuss the molecular mechanisms by which EA modulates signaling pathways and molecular targets involved in these cancer hallmarks, based on in vitro and in vivo studies. The multifaceted actions of EA make it a promising candidate for cancer prevention and therapy. Understanding its impact on cancer biology can pave the way for developing novel strategies to combat this complex disease.

Protein Kinase C at the Crossroad of Mutations, Cancer, Targeted Therapy and Immune Response

The frequent PKC dysregulations observed in many tumors have made these enzymes natural targets for anticancer applications. Nevertheless, this considerable interest in the development of PKC modulators has not led to the expected therapeutic benefits, likely due to the complex biological activities regulated by PKC isoenzymes, often playing ambiguous and protective functions, further driven by the occurrence of mutations. The structure, regulation and functions of PKCs have been extensively covered in other publications. Herein, we focused on PKC alterations mostly associated with complete functional loss. We also addressed the modest yet encouraging results obtained targeting PKC in selected malignancies and the more frequent negative clinical outcomes. The reported observations advocate the need for more selective molecules and a better understanding of the involved pathways. Furthermore, we underlined the most relevant immune mechanisms controlled by PKC isoforms potentially impacting the immune checkpoint inhibitor blockade-mediated immune recovery. We believe that a comprehensive examination of the molecular features of the tumor microenvironment might improve clinical outcomes by tailoring PKC modulation. This approach can be further supported by the identification of potential response biomarkers, which may indicate patients who may benefit from the manipulation of distinctive PKC isoforms.

The store-operated Ca2+ channel Orai1α is required for agonist-evoked NF-κB activation by a mechanism dependent on PKCβ2

Store-operated Ca²⁺ entry is a ubiquitous mechanism for Ca²⁺ influx in mammalian cells that regulates a variety of physiological processes. The identification of two forms of Orai1, the predominant store-operated channel, Orai1α and Orai1β, raises the question whether they differentially regulate cell function. Orai1α is the full-length Orai1, containing 301 amino acids, whereas Orai1β lacks the N-terminal 63 amino acids. Here, using a combination of biochemistry and imaging combined with the use of human embryonic kidney 293 KO cells, missing the native Orai1, transfected with plasmids encoding for either Orai1α or Orai1β, we show that Orai1α plays a relevant role in agonist-induced NF-κB transcriptional activity. In contrast, functional Orai1β is not required for the activation of these transcription factors. The role of Orai1α in the activation of NF-κB is entirely dependent on Ca²⁺ influx and involves PKCβ activation. Our results indicate that Orai1α interacts with PKCβ2 by a mechanism involving the Orai1α exclusive AKAP79 association region, which strongly suggests a role for AKAP79 in this process. These findings provide evidence of the role of Orai1α in agonist-induced NF-κB transcriptional activity and reveal functional differences between Orai1 variants.

Protein arginine deiminase 2 (PAD2) modulates the polarization of THP-1 macrophages to the anti-inflammatory M2 phenotype

Background

Macrophages are effector cells of the innate immune system that undergo phenotypical changes in response to organ injury and repair. These cells are most often classified as proinflammatory M1 and anti-inflammatory M2 macrophages. Protein arginine deiminase (PAD), which catalyses the irreversible conversion of protein-bound arginine into citrulline, is expressed in macrophages. However, the substrates of PAD and its role in immune cells remain unclear. This study aimed to investigate the role of PAD in THP-1 macrophage polarization to the M1 and M2 phenotypes and identify the citrullinated proteins and modified arginines that are associated with this biological switch using mass spectrometry.

Results

Our study showed that PAD2 and, to a lesser extent, PAD1 and PAD4 were predominantly expressed in M1 macrophages. We showed that inhibiting PAD expression with BB-Cl-amidine decreased macrophage polarization to the M1 phenotype (TNF-α, IL-6) and increased macrophage polarization to the M2 phenotype (MRC1, ALOX15). This process was mediated by the downregulation of proteins involved in the NF-κβ pathway. Silencing PAD2 confirmed the activation of M2 macrophages by increasing the antiviral innate immune response and interferon signalling. A total of 192 novel citrullination sites associated with inflammation, cell death and DNA/RNA processing pathways were identified in M1 and M2 macrophages.

Conclusions

We showed that inhibiting PAD activity using a pharmacological inhibitor or silencing PAD2 with PAD2 siRNA shifted the activation of macrophages towards the M2 phenotype, which can be crucial for designing novel macrophage-mediated therapeutic strategies. We revealed a major citrullinated proteome and its rearrangement following macrophage polarization, which after further validation could lead to significant clinical benefits for the treatment of inflammation and autoimmune diseases.

Signaling networks in B cell development and related therapeutic strategies

B cells are essential for Ab production during humoral immune responses. From decades of B cell research, there is now a detailed understanding of B cell subsets, development, functions, and most importantly, signaling pathways. The complicated pathways in B cells and their interactions with each other are stage-dependent, varying with surface marker expression during B cell development. With the increasing understanding of B cell development and signaling pathways, the mechanisms underlying B cell related diseases are being unraveled as well, making it possible to provide more precise and effective treatments. In this review, we describe several essential and recently discovered signaling pathways in B cell development and take a look at newly developed therapeutic strategies targeted at B cell signaling.

Epigenetic gene regulation in plasma cells

Humoral immunity provides protection from pathogenic infection and is mediated by antibodies following the differentiation of naive B cells (nBs) to antibody-secreting cells (ASCs). This process requires substantial epigenetic and transcriptional rewiring to ultimately repress the nB program and replace it with one conducive to ASC physiology and function. Notably, these reprogramming events occur within the framework of cell division. Efforts to understand the relationship of cell division with reprogramming and ASC differentiation in vivo have uncovered the timing and scope of reprogramming, as well as key factors that influence these events. Herein, we discuss the unique physiology of ASC and how nBs undergo epigenetic and genome architectural reorganization to acquire the necessary functions to support antibody production. We also discuss the stage-wise manner in which reprogramming occurs across cell divisions and how key molecular determinants can influence B cell fate outcomes.

Bruton's tyrosine kinase inhibition induces rewiring of proximal and distal B-cell receptor signaling in mice

Bruton′s tyrosine kinase (Btk) is a crucial signaling molecule in BCR signaling and a key regulator of B‐ cell differentiation and function. Btk inhibition has shown impressive clinical efficacy in various B‐cell malignancies. However, it remains unknown whether inhibition additionally induces changes in BCR signaling due to feedback mechanisms, a phenomenon referred to as BCR rewiring. In this report, we studied the impact of Btk activity on major components of the BCR signaling pathway in mice. As expected, NF‐κB and Akt/S6 signaling was decreased in Btk‐deficient B cells. Unexpectedly, phosphorylation of several proximal signaling molecules, including CD79a, Syk, and PI3K, as well as the key Btk‐effector PLCγ2 and the more downstream kinase Erk, were significantly increased. This pattern of BCR rewiring was essentially opposite in B cells from transgenic mice overexpressing Btk. Importantly, prolonged Btk inhibitor treatment of WT mice or mice engrafted with leukemic B cells also resulted in increased phosho‐CD79a and phospho‐PLCγ2 in B cells. Our findings show that Btk enzymatic function determines phosphorylation of proximal and distal BCR signaling molecules in B cells. We conclude that Btk inhibitor treatment results in rewiring of BCR signaling, which may affect both malignant and healthy B cells.

Activation of Protein Tyrosine Phosphatase Receptor Type γ Suppresses Mechanisms of Adhesion and Survival in Chronic Lymphocytic Leukemia Cells

The regulatory role of protein tyrosine kinases in β₁- and β₂-integrin activation and in the survival of chronic lymphocytic leukemia (CLL) cells is well established. In contrast, the involvement of protein tyrosine phosphatases in CLL biology was less investigated. We show that selective activation of the protein tyrosine phosphatase receptor type γ (PTPRG) strongly suppresses integrin activation and survival in leukemic B cells isolated from patients with CLL. Activation of PTPRG specifically inhibits CXCR4- as well as BCR-induced triggering of LFA-1 and VLA-4 integrins and mediated rapid adhesion. Triggering of LFA-1 affinity is also prevented by PTPRG activity. Analysis of signaling mechanisms shows that activation of PTPRG blocks chemokine-induced triggering of JAK2 and Bruton's tyrosine kinase protein tyrosine kinases and of the small GTP-binding protein RhoA. Furthermore, activated PTPRG triggers rapid and robust caspase-3/7-mediated apoptosis in CLL cells in a manner quantitatively comparable to the Bruton's tyrosine kinase inhibitor ibrutinib. However, in contrast to ibrutinib, PTPRG-triggered apoptosis is insensitive to prosurvival signals generated by CXCR4 and BCR signaling. Importantly, PTPRG activation does not trigger apoptosis in healthy B lymphocytes. The data show that activated PTPRG inhibits, at once, the signaling pathways controlling adhesion and survival of CLL cells, thus emerging as a negative regulator of CLL pathogenesis. These findings suggest that pharmacological potentiation of PTPRG tyrosine-phosphatase enzymatic activity could represent a novel approach to CLL treatment.

The Nuclear Factor Kappa B (NF-kB) signaling in cancer development and immune diseases

The nuclear factor kappa B (NF-kB) family of transcription factors plays an essential role as stressors in the cellular environment, and controls the expression of important regulatory genes such as immunity, inflammation, death, and cell proliferation. NF-kB protein is located in the cytoplasm, and can be activated by various cellular stimuli. There are two pathways for NF-kB activation, as the canonical and non-canonical pathways, which require complex molecular interactions with adapter proteins and phosphorylation and ubiquitinase enzymes. Accordingly, this increases NF-kB translocation in the nucleus and regulates gene expression. In this study, the concepts that emerge in different cellular systems allow the design of NF-kB function in humans. This would not only allow the development for rare diseases associated with NF-kB, but would also be used as a source of useful information to eliminate widespread consequences such as cancer or inflammatory/immune diseases.

Case Report: Resetting the Humoral Immune Response by Targeting Plasma Cells With Daratumumab in Anti-Phospholipid Syndrome

Introduction

Monoclonal antibodies (mAb) targeting plasma cells are malignant gammopathy designed and approved therapies. In recent years, these antibodies have also been increasingly introduced for non-malignant conditions such as autoimmune-mediated diseases. The Anti-Phospholipid Syndrome (APS) is an immune-mediated disorder in which autoantibodies against phospholipid associated proteins could elicit the activation of the coagulation cascade in specific situations. Therefore, the mainstream treatment for APS patients is the use of anticoagulant therapy. However, there are refractory patients who would benefit from targeting the antibodies rather than their effects. Rituximab, a B-cell depleting mAb, and intravenous immunoglobulins (IVIG) have been used in APS patients without showing a clear beneficial effect or a significant drop in anti-phospholipid antibody (aPL) levels.

Clinical case

We present our first APS case treated with daratumumab, an anti-CD38 mAb, in a 21-year-old patient with APS who presented with recurrent venous thromboembolic events despite adequate anticoagulant therapy. She tested positive for lupus anticoagulant, anti-cardiolipin IgG, anti-beta-2-glycoprotein-I IgG and anti-phosphatidylserine/prothrombin IgG and IgM. She was administered one dose weekly of daratumumab for 4 weeks. The treatment showed an adequate safety profile and was well tolerated. The patient was discharged after undergoing a clinically significant improvement. After the therapy, her levels of positive aPL declined significantly and most continued to decrease during the next three months. The patient experienced a new thrombotic episode two years after the therapy associated with poor adherence to antithrombotic therapy.

Conclusions

The treatment with daratumumab showed an adequate safety profile, was well tolerated and led to a significant clinical improvement. Levels of aPL lowered on therapy and the next three months and then rose again during follow-up. Further investigation is needed to better elucidate the role and optimal timing and doses of daratumumab in treatment of refractory APS.

NLRC5 regulates expression of MHC-I and provides a target for anti-tumor immunity in transmissible cancers

Purpose

Downregulation of MHC class I (MHC-I) is a common immune evasion strategy of many cancers. Similarly, two allogeneic clonal transmissible cancers have killed thousands of wild Tasmanian devils (Sarcophilus harrisii) and also modulate MHC-I expression to evade anti-cancer and allograft responses. IFNG treatment restores MHC-I expression on devil facial tumor (DFT) cells but is insufficient to control tumor growth. Transcriptional co-activator NLRC5 is a master regulator of MHC-I in humans and mice but its role in transmissible cancers remains unknown. In this study, we explored the regulation and role of MHC-I in these unique genetically mis-matched tumors.

Methods

We used transcriptome and flow cytometric analyses to determine how MHC-I shapes allogeneic and anti-tumor responses. Cell lines that overexpress NLRC5 to drive antigen presentation, and B2M-knockout cell lines incapable of presenting antigen on MHC-I were used to probe the role of MHC-I in rare cases of tumor regressions.

Results

Transcriptomic results suggest that NLRC5 plays a major role in MHC-I regulation in devils. NLRC5 was shown to drive the expression of many components of the antigen presentation pathway but did not upregulate PDL1. Serum from devils with tumor regressions showed strong binding to IFNG-treated and NLRC5 cell lines; antibody binding to IFNG-treated and NRLC5 transgenic tumor cells was diminished or absent following B2M knockout.

Conclusion

MHC-I could be identified as a target for anti-tumor and allogeneic immunity. Consequently, NLRC5 could be a promising target for immunotherapy and vaccines to protect devils from transmissible cancers and inform development of transplant and cancer therapies for humans.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00432-021-03601-x.

Intravital quantification reveals dynamic calcium concentration changes across B cell differentiation stages

Calcium is a universal second messenger present in all eukaryotic cells. The mobilization and storage of Ca²⁺ ions drives a number of signaling-related processes, stress-responses, or metabolic changes, all of which are relevant for the development of immune cells and their adaption to pathogens. Here, we introduce the Förster resonance energy transfer (FRET)-reporter mouse YellowCaB expressing the genetically encoded calcium indicator TN-XXL in B lymphocytes. Calcium-induced conformation change of TN-XXL results in FRET-donor quenching measurable by two-photon fluorescence lifetime imaging. For the first time, using our novel numerical analysis, we extract absolute cytoplasmic calcium concentrations in activated B cells during affinity maturation in vivo. We show that calcium in activated B cells is highly dynamic and that activation introduces a persistent calcium heterogeneity to the lineage. A characterization of absolute calcium concentrations present at any time within the cytosol is therefore of great value for the understanding of long-lived beneficial immune responses and detrimental autoimmunity.

Systemic Lupus Erythematosus in Children and Young People

PURPOSE OF REVIEW

Juvenile-onset systemic lupus erythematosus ((j)SLE) is an autoimmune/inflammatory disease that results in significant damage and disability. When compared to patients with disease onset in adulthood, jSLE patients exhibit increased disease activity, damage and require more aggressive treatments. This manuscript summarises age-specific pathogenic mechanisms and underscores the need for age group-specific research, classification and treatment.

RECENT FINDINGS

Genetic factors play a significant role in the pathophysiology of jSLE, as > 7% of patients develop disease as a result of single gene mutations. Remaining patients carry genetic variants that are necessary for disease development, but require additional factors. Increased 'genetic impact' likely contributes to earlier disease onset and more severe phenotypes. Epigenetic events have only recently started to be addressed in jSLE, and add to the list of pathogenic mechanisms that may serve as biomarkers and/or treatment targets. To allow meaningful and patient-oriented paediatric research, age-specific classification criteria and treatment targets require to be defined as currently available tools established for adult-onset SLE have limitations in the paediatric cohort. Significant progress has been made in understanding the pathophysiology of jSLE. Meaningful laboratory and clinical research can only be performed using age group-specific tools, classification criteria and treatment targets.

Signal Transduction in Immune Cells and Protein Kinases

Immune response relies upon several intracellular signaling events. Among the protein kinases involved in these pathways, members of the protein kinase C (PKC) family are prominent molecules because they have the capacity to acutely and reversibly modulate effector protein functions, controlling both spatial distribution and dynamic properties of the signals. Different PKC isoforms are involved in distinct signaling pathways, with selective functions in a cell-specific manner.In innate system, Toll-like receptor signaling is the main molecular event triggering effector functions. Various isoforms of PKC can be common to different TLRs, while some of them are specific for a certain type of TLR. Protein kinases involvement in innate immune cells are presented within the chapter emphasizing their coordination in many aspects of immune cell function and, as important players in immune regulation.In adaptive immunity T-cell receptor and B-cell receptor signaling are the main intracellular pathways involved in seminal immune specific cellular events. Activation through TCR and BCR can have common intracellular pathways while others can be specific for the type of receptor involved or for the specific function triggered. Various PKC isoforms involvement in TCR and BCR Intracellular signaling will be presented as positive and negative regulators of the immune response events triggered in adaptive immunity.

Biomarkers and novel therapeutic approaches for diffuse large B-cell lymphoma in the era of precision medicine

Despite the great efforts for better treatment options for diffuse large B-cell lymphoma (DLBCL) (most common form of non-Hodgkin lymphoma, NHL) to treat and prevent relapse, it continues to be a challenge. Here, we present an overview of DLBCL and address the diagnostic assays and molecular techniques used in its diagnosis, role of biomarkers in detection, treatment of early and advanced stage DLBCL, and novel drug regimens. We discuss the significant biomarkers that have emerged as essential tools for stratifying patients according to risk factors and for providing insights into the use of more targeted and individualized therapeutics. We discuss techniques such as gene expression studies, including next-generation sequencing, which have enabled a more understanding of the complex pathogenesis of DLBCL and have helped determine molecular targets for novel therapeutic agents. We examine current treatment approaches, outline the findings of completed clinical trials, and provide updates for ongoing clinical trials. We highlight clinical trials relevant to the significant fraction of DLBCL patients who present with complex cases marked by high relapse rates. Supported by an increased understanding of targetable pathways in DLBCL, clinical trials involving specialized combination therapies are bringing us within reach the promise of an effective cure to DLBCL using precision medicine. Optimization of therapy remains a crucial objective, with the end goal being a balance between high survival rates through targeted and personalized treatment while reducing adverse effects in DLBCL patients of all subsets.

The Future of Anticancer Drugs: A Cytotoxicity Assessment Study of CdSe/ZnS Quantum Dots

Quantum dots (QDs), including CdSe/ZnS, are nanoparticles emitting various wavelengths of fluorescent light depending on their size. Fluorescence allows them to be exploited for in vivo sensing/imaging of cancer cells. Nevertheless, thorough assessments of the effects of these commonly used QDs on cell stability are essentially required prior to their full applications. To investigate the effects of Cd QDs on the growth of human cervical cancer cells (HeLa), we utilized a growth assay, a reactive oxygen species (ROS) assay, an apoptosis assay, and RNA-seq. The growth assay results showed significant proliferation inhibition of HeLa cells by CdSe/ZnS. We revealed that smaller green CdSe/ZnS exerts more toxic effects than slightly larger yellow CdSe/ZnS. There were no significant increases of ROSs under the treatment of Cd QDs, which is consistent with the notion that low concentration of Cd QDs does not cause significant production of ROSs. In addition, we found that Cd QDs induced late apoptosis. RNA-Seq-based transcriptome analysis revealed that the exposure to green Cd QDs significantly upregulated antiapoptotic, antiproliferative, and antitumorigenic functions. The transcriptome profile also noted the downregulation of pro-proliferation, mitochondrial respiratory chain, detoxification, and receptor-mediated endocytosis. Taken together, our findings provide evidence that green CdSe/ZnS can be an alternative anticancer drug. In addition, our transcriptome analysis provides new insights into alteration of physiological state induced by CdSe/ZnS QDs in HeLa cancer cells.

Stromal cell protein kinase C-β inhibition enhances chemosensitivity in B cell malignancies and overcomes drug resistance

Overcoming drug resistance remains a key challenge to cure patients with acute and chronic B cell malignancies. Here, we describe a stromal cell-autonomous signaling pathway, which contributes to drug resistance of malignant B cells. We show that protein kinase C (PKC)-β-dependent signals from bone marrow-derived stromal cells markedly decrease the efficacy of cytotoxic therapies. Conversely, small-molecule PKC-β inhibitors antagonize prosurvival signals from stromal cells and sensitize tumor cells to targeted and nontargeted chemotherapy, resulting in enhanced cytotoxicity and prolonged survival in vivo. Mechanistically, stromal PKC-β controls the expression of adhesion and matrix proteins, required for activation of phosphoinositide 3-kinases (PI3Ks) and the extracellular signal-regulated kinase (ERK)-mediated stabilization of B cell lymphoma-extra large (BCL-XL) in tumor cells. Central to the stroma-mediated drug resistance is the PKC-β-dependent activation of transcription factor EB, regulating lysosome biogenesis and plasma membrane integrity. Stroma-directed therapies, enabled by direct inhibition of PKC-β, enhance the effectiveness of many antileukemic therapies.

Variegatic acid from the edible mushroom Tylopilus ballouii inhibits TNF-α production and PKCβ1 activity in leukemia cells

Variegatic acid, isolated from Tylopilus ballouii dry fruiting bodies, is an inhibitor of β-hexosaminidase release and tumor necrosis factor (TNF)-α secretion from rat basophilic leukemia (RBL-2H3) cells, with IC₅₀ values of 10.4 μM and 16.8 μM, respectively. On the other hand, it inhibits PKCβ1 activity with an IC₅₀ value of 36.2 μM.

Quantitative Subcellular Proteomics of the Orbitofrontal Cortex of Schizophrenia Patients

Schizophrenia is a chronic disease characterized by the impairment of mental functions with a marked social dysfunction. A quantitative proteomic approach using iTRAQ labeling and SRM, applied to the characterization of mitochondria (MIT), crude nuclear fraction (NUC), and cytoplasm (CYT), can allow the observation of dynamic changes in cell compartments providing valuable insights concerning schizophrenia physiopathology. Mass spectrometry analyses of the orbitofrontal cortex from 12 schizophrenia patients and 8 healthy controls identified 655 protein groups in the MIT fraction, 1500 in NUC, and 1591 in CYT. We found 166 groups of proteins dysregulated among all enriched cellular fractions. Through the quantitative proteomic analysis, we detect as the main biological pathways those related to calcium and glutamate imbalance, cell signaling disruption of CREB activation, axon guidance, and proteins involved in the activation of NF-kB signaling along with the increase of complement protein C3. Based on our data analysis, we suggest the activation of NF-kB as a possible pathway that links the deregulation of glutamate, calcium, apoptosis, and the activation of the immune system in schizophrenia patients. All MS data are available in the ProteomeXchange Repository under the identifier PXD015356 and PXD014350.

Iguratimod represses B cell terminal differentiation linked with the inhibition of PKC/EGR1 axis

Background

This study aimed to explore the molecular mechanism and clinical relevance of iguratimod in the regulation of human B cell terminal differentiation.

Methods

An in vitro human antibody-secreting cell (ASC) differentiation system was established to test the effect of iguratimod. B cell phenotype and key transcription factors (TFs) relevant to ASC differentiation were analyzed through flow cytometry and qPCR. The COX-2 activity was measured by enzyme immunoassay (EIA). RNA sequencing was used to identify potential targets of iguratimod. We enrolled six treatment-naive rheumatoid arthritis (RA) patients whose blood samples were collected for phenotypic and molecular studies along with 12-week iguratimod monotherapy.

Results

Iguratimod inhibited human ASC generation without affecting B cell activation and proliferation. Iguratimod showed only weak COX-2 activity. Gene set enrichment analysis (GSEA) identified that protein kinase C (PKC) pathway was targeted by iguratimod which was confirmed by PKC activity detection. Furthermore, early growth response 1 (EGR1), a target of PKC and a non-redundant TF for ASC differentiation, was found to be the most downregulated gene in iguratimod-treated B cells. Lastly, iguratimod monotherapy decreased peripheral ASCs and was associated with improved disease activity. The expression of major ASC-related TFs, including EGR1, was similarly downregulated in patient blood samples.

Conclusions

Iguratimod inhibits ASC differentiation both in vitro and in RA patients. Our study suggests that PKC/EGR1 axis, rather than COX-2, is critically involved in the inhibitory effect by iguratimod on human ASC differentiation. Iguratimod could have a broader application to treat B cell-related autoimmune diseases in clinics.

Electronic supplementary material

The online version of this article (10.1186/s13075-019-1874-2) contains supplementary material, which is available to authorized users.

Class II MHC cytoplasmic domain-mediated signaling in B cells: A tail of two signals

In addition to their role in antigen presentation, class II MHC molecules also transmit signals to B lymphocytes. Class II MHC-mediated signals initiate a range of events in B cells, including induction of cell surface proteins, initiation of cell-cycle progression/proliferation, activation of or protection from apoptosis, and antigen-dependent plasma cell differentiation. Although various transmembrane signaling proteins associate with class II MHC molecules, the class II MHC cytoplasmic domains are essential for signals leading to increased intracellular cAMP and activation of protein kinase C (PKC). Although truncation and mutagenesis studies have provided considerable information about the cytoplasmic domain sequences required, how class II MHC molecules elicit cAMP and PKC activation is not known. Further, appropriate T-dependent B cell responses require intact cAMP and PKC signaling, but the extent to which class II MHC signals are involved is also unknown. This review details our current knowledge of class II MHC cytoplasmic domain signaling in B cells with an emphasis on the likely importance of class II MHC signals for T-dependent antibody responses.

Protein Kinase C-β Dictates B Cell Fate by Regulating Mitochondrial Remodeling, Metabolic Reprogramming, and Heme Biosynthesis

PKCβ-null (Prkcb-/-) mice are severely immunodeficient. Here we show that mice whose B cells lack PKCβ failed to form germinal centers and plasma cells, which undermined affinity maturation and antibody production in response to immunization. Moreover, these mice failed to develop plasma cells in response to viral infection. At the cellular level, we have shown that Prkcb-/- B cells exhibited defective antigen polarization and mTORC1 signaling. While altered antigen polarization impaired antigen presentation and likely restricted the potential of GC development, defective mTORC1 signaling impaired metabolic reprogramming, mitochondrial remodeling, and heme biosynthesis in these cells, which altogether overwhelmingly opposed plasma cell differentiation. Taken together, our study reveals mechanistic insights into the function of PKCβ as a key regulator of B cell polarity and metabolic reprogramming that instructs B cell fate.

Juvenile-onset systemic lupus erythematosus (jSLE) - Pathophysiological concepts and treatment options

The systemic autoimmune/inflammatory condition systemic lupus erythematosus (SLE) manifests before the age of 16 years in 10-20% of all cases. Clinical courses are more severe, and organ complications are more common in patients with juvenile SLE. Varying gender distribution in different age groups and increasing severity with younger age and the presence of monogenic disease in early childhood indicate distinct differences in the pathophysiology of juvenile versus adult-onset SLE. Regardless of these differences, classification criteria and treatment options are identical. In this article, we discuss age-specific pathomechanisms of juvenile-onset SLE, which are currently available and as future treatment options, and propose reclassification of different forms of SLE along the inflammatory spectrum from autoinflammation to autoimmunity.

The role of HSP27 in RACK1-mediated PKC activation in THP-1 cells

Receptor for Activated C Kinase 1 (RACK1) pseudosubstrate is a commercially available peptide that directly activates protein kinase C-β (PKCβ). We have recently shown that RACK1 pseudosubstrate, alone or in combination with classical immune activators, results in increased cytokine production and CD86 upregulation in primary leukocytes. Furthermore, we demonstrated a role of PKCβ and RACK1 in chemical allergen-induced CD86 expression and IL-8 production in both THP-1 cells and primary human dendritic cells. Aim of this study was to shed light on the mechanisms underlying RACK1 pseudosubstrate-induced immune activation and to compare it to lipopolysaccharide (LPS). The human promyelocytic cell line THP-1 was used throughout the study. RACK1 pseudosubstrate induced rapid (5 min) and dose-related PKCβ activation as assessed by its membrane translocation. Among the proteins phosphorylated, we identified Hsp27. Both RACK1 pseudosubstrate and LPS induce its phosphorylation and release in culture medium. The release of Hsp27 induced by RACK1 pseudosubstrate was also confirmed in peripheral blood mononuclear cells. To evaluate the role of Hsp27 in RACK1 pseudosubstrate or LPS-induced cell activation, we conducted Hsp27 silencing and neutralization experiments. Both strategies confirmed the central role of Hsp27 in RACK1 pseudosubstrate or LPS-induced cell activation, as assessed by IL-8 production and upregulation of CD86.

PKK deficiency in B cells prevents lupus development in Sle lupus mice

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the production of autoantibodies that can result in damage to multiple organs. It is well documented that B cells play a critical role in the development of the disease. We previously showed that protein kinase C associated kinase (PKK) is required for B1 cell development as well as for the survival of recirculating mature B cells and B-lymphoma cells. Here, we investigated the role of PKK in lupus development in a lupus mouse model. We demonstrate that the conditional deletion of PKK in B cells prevents lupus development in Sle1Sle3 mice. The loss of PKK in Sle mice resulted in the amelioration of multiple classical lupus-associated phenotypes and histologic features of lupus nephritis, including marked reduction in the levels of serum autoantibodies, proteinuria, spleen size, peritoneal B-1 cell population and the number of activated CD4 T cells. In addition, the abundance of autoreactive plasma cells normally seen in Sle lupus mice was also significantly decreased in the PKK-deficient Sle mice. Sle B cells deficient in PKK display defective proliferation responses to BCR and LPS stimulation. Consistently, B cell receptor-mediated NF-κB activation, which is required for the survival of activated B cells, was impaired in the PKK-deficient B cells. Taken together, our work uncovers a critical role of PKK in lupus development and suggests that targeting the PKK-mediated pathway may represent a promising therapeutic strategy for lupus treatment.

Transcriptional mechanism of vascular endothelial growth factor-induced expression of protein kinase CβII in chronic lymphocytic leukaemia cells

A key feature of chronic lymphocytic leukaemia (CLL) cells is overexpressed protein kinase CβII (PKCβII), an S/T kinase important in the pathogenesis of this and other B cell malignancies. The mechanisms contributing to enhanced transcription of the gene coding for PKCβII, PRKCB, in CLL cells remain poorly described, but could be important because of potential insight into how the phenotype of these cells is regulated. Here, we show that SP1 is the major driver of PKCβII expression in CLL cells where enhanced association of this transcription factor with the PRKCB promoter is likely because of the presence of histone marks permissive of gene activation. We also show how vascular endothelial growth factor (VEGF) regulates PRKCB promoter function in CLL cells, stimulating PKCβ gene transcription via increased association of SP1 and decreased association of STAT3. Taken together, these results are the first to demonstrate a clear role for SP1 in the up regulation of PKCβII expression in CLL cells, and the first to link SP1 with the pathogenesis of this and potentially other B cell malignancies where PKCβII is overexpressed.

Prognosis biomarkers evaluation in chronic lymphocytic leukemia

OBJECTIVE/BACKGROUND

From clinical and biological points of view, chronic lymphocytic leukemia (CLL) is a heterogeneous disease characterized by a progressive accumulation of lymphocytes in the peripheral blood, bone marrow, and lymphoid organs. New prognostic markers in CLL may be useful to clinicians for predicting outcome and in clinical decision-making. The aim of this study was to evaluate the potential prognostic value of the apoptotic/survival-controlling proteins and protein tyrosine kinase ZAP-70 gene expression in CLL patients and control individuals, correlating such findings with patients' clinical data.

METHODS

Fifty-three patients diagnosed with CLL attending the hematology service of a clinical hospital, and 24 healthy individuals with no history of leukemia (Control group) were enrolled in this study. Analyses of apoptotic/survival-controlling proteins were performed by western blot and ZAP-70 gene expression was evaluated by real-time polymerase chain reaction.

RESULTS

Significant differences were observed for the p-p38, Mcl-1 long, and Mcl-1 short proteins when patients were compared with CLL and controls. A positive correlation between the results for Mcl-1 short and Mcl-1 long and lymphocyte count was observed, corroborating the hypothesis of an imbalance between proteins of cell survival pathways/apoptosis in CLL.

CONCLUSION

ZAP-70 gene expression was not detected as a discriminant biomarker in these CLL patients. An imbalance between apoptosis-related proteins was observed in the present study, corroborating the hypothesis of increased survival of lymphocytes in CLL patients.

NF-κB signaling pathway and its potential as a target for therapy in lymphoid neoplasms

The NF-κB pathway, a critical regulator of apoptosis, plays a key role in many normal cellular functions. Genetic alterations and other mechanisms leading to constitutive activation of the NF-κB pathway contribute to cancer development, progression and therapy resistance by activation of downstream anti-apoptotic pathways, unfavorable microenvironment interactions, and gene dysregulation. Not surprisingly, given its importance to normal and cancer cell function, the NF-κB pathway has emerged as a target for therapy. In the review, we present the physiologic role of the NF-κB pathway and recent advances in better understanding of the pathologic roles of the NF-κB pathway in major types of lymphoid neoplasms. We also provide an update of clinical trials that use NF-κB pathway inhibitors. These trials are exploring the clinical efficiency of combining NF-κB pathway inhibitors with various agents that target diverse mechanisms of action with the goal being to optimize novel therapeutic opportunities for targeting oncogenic pathways to eradicate cancer cells.

Protein Kinase Cζ Regulation of Hypertrophic and Apoptotic Events Occurring during Rat Neonatal Heart Development and Growth

The development and growth of the rat heart implies hyperplasia, which stops at birth, and hypertrophy, allowing cardiac mass to grow in response to programmed genetic events along with to haemodynamic overload. Moreover, hypertrophy is accomplished to apoptosis which controls the final number of myocardial cells, deletes vestigial structures, and takes part in remodelling the organ. Since at the basis of all these processes, which lead to the complete development of the heart, the activation of specific signalling pathways underlies, attention has been addressed to the role played in vivo by Protein Kinase Cζ (PKCζ) in regulating NF-kB signalling system and “intrinsic” mitochondrial apoptotic route at days 1, 4, 10 and 22 of rat life. In fact, a role has been assigned to PKCζ in indirectly phosphorylating IKBα, which peaks between 10 and 22 days, through a IKK determining, in turn, NF-kB activation, concomitantly to cytochrome c/Apaf 1 co-localization in the cytoplasm and caspase-9/caspase-3 activation, which leads to the occurrence of apoptosis. Thus a key role for PKCζ in regulating the hypertrophic and apoptotic events leading to establishment of complete function in rat neonatal heart is here suggested.

A critical role for the protein kinase PKK in the maintenance of recirculating mature B cells and the development of B1 cells

Protein kinase C associated kinase (PKK) regulates NF-κB activation and is required for the survival of certain lymphoma cells. Mice lacking PKK die soon after birth, and previous studies suggest that the role of PKK in B cell development might be context dependent. We have generated a mouse strain harboring conditional null alleles for PKK and a Cre-recombinase transgene under the control of the endogenous CD19 promoter. In the present study, we show that knockout of PKK in B cells results in the reduction of long-lived recirculating mature B cell population in lymph nodes and bone marrow as well as a decrease in peritoneal B1 cells, while PKK deficiency has no apparent effect on early B cell development in bone marrow or the development of follicular and marginal zone B cells in the spleen. In addition, we demonstrate that PKK-deficient B cells display defective proliferation and survival responses to stimulation of B cell receptor (BCR), which may underlie the reduction of recirculating mature B cells in PKK mutant mice. Consistently, BCR-mediated NF-κB activation, known to be required for the survival of activated but not resting B cells, is attenuated in PKK-deficient B cells. Thus, our results reveal a critical role of PKK in the maintenance of recirculating mature B cells as well as the development of B1 cells in mice.

Similarities and differences between alpha-tocopherol and gamma-tocopherol in amelioration of inflammation, oxidative stress and pre-fibrosis in hyperglycemia induced acute kidney inflammation

BACKGROUND/OBJECTIVES

Diabetes mellitus (DM) is a major chronic disease which increases global health problems. Diabetes-induced renal damage is associated with inflammation and fibrosis. Alpha (AT) and gamma-tocopherols (GT) have shown antioxidant and anti-inflammatory effects in inflammation-mediated injuries. The primary aim of this study was to investigate effects of AT and GT supplementations on hyperglycemia induced acute kidney inflammation in alloxan induced diabetic mice with different levels of fasting blood glucose (FBG).

MATERIALS/METHODS

Diabetes was induced by injection of alloxan monohydrate (150 mg/kg, i.p) in ICR mice (5.5-week-old, male) and mice were subdivided according to their FBG levels and treated with different diets for 2 weeks; CON: non-diabetic mice, m-DMC: diabetic control mice with mild FBG levels (250 mg/dl ≤ FBG ≤ 450 mg/dl), m-AT: m-DM mice fed AT supplementation (35 mg/kg diet), m-GT: m-DM mice with GT supplementation (35 mg/kg diet), s-DMC: diabetic control mice with severe FBG levels (450 mg/dl < FBG), s-AT: s-DM mice with AT supplementation, s-GT: s-DM mice with GT supplementation.

RESULTS

Both AT and GT supplementations showed similar beneficial effects on NFκB associated inflammatory response (phosphorylated inhibitory kappa B-α, interleukin-1β, C-reactive protein, monocyte chemotactic protein-1) and pre-fibrosis (tumor growth factor β-1 and protein kinase C-II) as well as an antioxidant emzyme, heme oxygenase-1 (HO-1) in diabetic mice. On the other hands, AT and GT showed different beneficial effects on kidney weight, FBG, and oxidative stress associated makers (malondialdehyde, glutathione peroxidase, and catalase) except HO-1. In particular, GT significantly preserved kidney weight in m-DM and improved FBG levels in s-DM and malondialdehyde and catalase in m- and s-DM, while AT significantly attenuated FBG levels in m-DM and improved glutathione peroxidase in m- and s-DM.

CONCLUSIONS

The results suggest that AT and GT with similarities and differences would be considered as beneficial nutrients to modulate hyperglycemia induced acute renal inflammation. Further research with careful approach is needed to confirm beneficial effects of tocopherols in diabetes with different FBG levels for clinical applications.

Protein kinase C in the immune system: from signalling to chromatin regulation

Protein kinase C (PKC) form a key family of enzymes involved in signalling pathways that specifically phosphorylates substrates at serine/threonine residues. Phosphorylation by PKC is important in regulating a variety of cellular events such as cell proliferation and the regulation of gene expression. In the immune system, PKCs are involved in regulating signal transduction pathways important for both innate and adaptive immunity, ultimately resulting in the expression of key immune genes. PKCs act as mediators during immune cell signalling through the immunological synapse. PKCs are traditionally known to be cytoplasmic signal transducers and are well embedded in the signalling pathways of cells to mediate the cells' response to a stimulus from the plasma membrane to the nucleus. PKCs are also found to transduce signals within the nucleus, a process that is distinct from the cytoplasmic signalling pathway. There is now growing evidence suggesting that PKC can directly regulate gene expression programmes through a non-traditional role as nuclear kinases. In this review, we will focus on the role of PKCs as key cytoplasmic signal transducers in immune cell signalling, as well as its role in nuclear signal transduction. We will also highlight recent evidence for its newly discovered regulatory role in the nucleus as a chromatin-associated kinase.

FcμR interacts and cooperates with the B cell receptor To promote B cell survival

The IgM FcR (FcμR) promotes B cell survival, but the molecular mechanism remains largely unknown. We show using FcμR(-/-) and wild-type mice that FcμR specifically enhanced B cell survival induced by BCR cross-linking with F(ab')2-anti-IgM Abs while having no effect on survival when the B cells were activated by CD40 ligation or LPS stimulation. FcμR expression was markedly upregulated by anti-IgM stimulation, which may promote enhanced FcμR signaling in these cells. Immunofluorescence and confocal microscopy analyses demonstrated that FcμR colocalized with the BCR on the plasma membrane of primary B cells. Coimmunoprecipitation analysis further revealed that FcμR physically interacted with the BCR complex. Because NF-κB plays a prominent role in B cell survival, we analyzed whether FcμR was involved in BCR-triggered NF-κB activation. FcμR did not affect BCR-triggered IκBα phosphorylation characteristic of the canonical NF-κB activation pathway but promoted the production of the noncanonical NF-κB pathway component p52. Consistent with the elevated p52 levels, FcμR enhanced BCR-triggered expression of the antiapoptotic protein BCL-xL. Importantly, FcμR stimulation alone in the absence of BCR signaling had no effect on either IκBα phosphorylation or the expression of p52 and BCL-xL. Therefore, FcμR relied on the BCR signal to activate the noncanonical NF-κB pathway and enhance B cell survival. These results reveal a cross-talk downstream of FcμR and BCR signaling and provide mechanistic insight into FcμR-mediated enhancement of B cell survival after BCR stimulation.

MAP Kinase Cascades in Antigen Receptor Signaling and Physiology

Mitogen-activated protein kinases (MAPKs) play roles in a cell type and context-dependent manner to convert extracellular stimuli to a variety of cellular responses, thereby directing cells to proliferation, differentiation, survival, apoptosis, and migration. Studies of genetically engineered mice or chemical inhibitors specific to each MAPK signaling pathway revealed that MAPKs have various, but non-redundant physiologically important roles among different families. MAPK cascades are obviously integrated in the B cell receptor signaling pathways as critical components to drive B cell-mediated immunity.

Protein kinase C-associated kinase regulates NF-κB activation through inducing IKK activation

Activation of the transcription factor NF-κB induced by extracellular stimuli requires IKKα and IKKβ kinase activity. How IKKα and IKKβ are activated by various upstream signaling molecules is not fully understood. We previously showed that protein kinase C-associated kinase (PKK, also known as DIK/RIP4), which belongs to the receptor-interacting protein (RIP) kinase family, mediates the B cell activating factor of the TNF family (BAFF)-induced NF-κB activation in diffuse large B cell lymphoma (DLBCL) cell lines. Here we have investigated the mechanism underlying NF-κB activation regulated by PKK. Our results suggest that PKK can activate both the classical and the alternative NF-κB activation pathways. PKK associates with IKKα and IKKβ in mammalian cells and induces activation of both IKKα and IKKβ via phosphorylation of their serine residues 176/180 and 177/181, respectively. Unlike other members of the RIP family that activate NF-κB through a kinase-independent pathway, PKK appears to activate IKK and NF-κB mainly in a kinase-dependent manner. Suppression of PKK expression by RNA interference inhibits phosphorylation of IKKα and IKKβ as well as activation of NF-κB in human cancer cell lines. Thus, PKK regulates NF-κB activation by modulating activation of IKKα and IKKβ in mammalian cells. We propose that PKK may provide a critical link between IKK activation and various upstream signaling cascades, and may represent a potential target for inhibiting abnormal NF-κB activation in human cancers.

Bruton's tyrosine kinase and protein kinase C µ are required for TLR7/9-induced IKKα and IRF-1 activation and interferon-β production in conventional dendritic cells

Stimulation of TLR7/9 by their respective ligands leads to the activation of IκB kinase α (IKKα) and Interferon Regulatory Factor 1 (IRF-1) and results in interferon (IFN)-β production in conventional dendritic cells (cDC). However, which other signaling molecules are involved in IKKα and IRF-1 activation during TLR7/9 signaling pathway are not known. We and others have shown that Bruton's Tyrosine Kinase (BTK) played a part in TLR9-mediated cytokine production in B cells and macrophages. However, it is unclear if BTK participates in TLR7/9-induced IFN-β production in cDC. In this study, we show that BTK is required for IFN-β synthesis in cDC upon TLR7/9 stimulation and that stimulated BTK-deficient cDC are defective in the induction of IKKα/β phosphorylation and IRF-1 activation. In addition, we demonstrate that Protein Kinase C µ (PKCµ) is also required for TLR7/9-induced IRF-1 activation and IFN-β upregulation in cDC and acts downstream of BTK. Taken together, we have uncovered two new molecules, BTK and PKCµ, that are involved in TLR7/9-triggered IFN-β production in cDC.

PKC-β as a therapeutic target in CLL: PKC inhibitor AEB071 demonstrates preclinical activity in CLL

Targeting B-cell receptor (BCR) signaling in chronic lymphocytic leukemia (CLL) has been successful with durable remissions observed with several targeted therapeutics. Protein kinase C-β (PKC-β) is immediately downstream of BCR and has been shown to be essential to CLL cell survival and proliferation in vivo. We therefore evaluated sotrastaurin (AEB071), an orally administered potent PKC inhibitor, on CLL cell survival both in vitro and in vivo. AEB071 shows selective cytotoxicity against B-CLL cells in a dose-dependent manner. Additionally, AEB071 attenuates BCR-mediated survival pathways, inhibits CpG-induced survival and proliferation of CLL cells in vitro, and effectively blocks microenvironment-mediated survival signaling pathways in primary CLL cells. Furthermore, AEB071 alters β-catenin expression, resulting in decreased downstream transcriptional genes as c-Myc, Cyclin D1, and CD44. Lastly, our preliminary in vivo studies indicate beneficial antitumor properties of AEB071 in CLL. Taken together, our results indicate that targeting PKC-β has the potential to disrupt signaling from the microenvironment contributing to CLL cell survival and potentially drug resistance. Future efforts targeting PKC with the PKC inhibitor AEB071 as monotherapy in clinical trials of relapsed and refractory CLL patients are warranted.

The B-cell receptor pathway: a critical component of healthy and malignant immune biology

The pathogenesis and progression of normal B-cell development to malignant transformation of chronic lymphocytic leukemia (CLL) is still poorly understood and has hampered attempts to develop targeted therapeutics for this disease. The dependence of CLL cells on B-cell receptor signaling has fostered a new area of basic and therapeutic research interest. In particular, identification of the dependence of CLL cells on both phosphatidylinositol 3-kinase delta and Bruton's tyrosine kinase signaling for survival and proliferation has come forth through well-performed preclinical studies and subsequent trials demonstrating dramatic efficacy. This review outlines essential components of B-cell receptor signaling and briefly addresses therapeutics that are emerging to target these in patients with CLL and related lymphoid malignancies.

Protein kinase C Beta in the tumor microenvironment promotes mammary tumorigenesis

Protein kinase C beta (PKCβ) expression in breast cancer is associated with a more aggressive tumor phenotype, yet the mechanism for how PKCβ is pro-tumorigenic in this disease is still unclear. Interestingly, while it is known that PKCβ mediates angiogenesis, immunity, fibroblast function and adipogenesis, all components of the mammary tumor microenvironment (TME), no study to date has investigated whether stromal PKCβ is functionally relevant in breast cancer. Herein, we evaluate mouse mammary tumor virus–polyoma middle T-antigen (MMTV–PyMT) induced mammary tumorigenesis in the presence and absence of PKCβ. We utilize two model systems: one where PKCβ is deleted in both the epithelial and stromal compartments to test the global requirement for PKCβ on tumor formation, and second, where PKCβ is deleted only in the stromal compartment to test its role in the TME. MMTV–PyMT mice globally lacking PKCβ live longer and develop smaller tumors with decreased proliferation and decreased macrophage infiltration. Similarly, when PKCβ is null exclusively in the stroma, PyMT-driven B6 cells form smaller tumors with diminished collagen deposition. These experiments reveal for the first time a tumor promoting role for stromal PKCβ in MMTV–PyMT tumorigenesis. In corroboration with these results, PKCβ mRNA (Prkcb) is increased in fibroblasts isolated from MMTV–PyMT tumors. These data were confirmed in a breast cancer patient cohort. Combined these data suggest the continued investigation of PKCβ in the mammary TME is necessary to elucidate how to effectively target this signaling pathway in breast cancer.

Different sensitivity of germinal center B cell-like diffuse large B cell lymphoma cells towards ibrutinib treatment

Background

Although rituximab in the combination of CHOP chemotherapy has been widely used as the standard treatment for several kinds of B-cell non-Hodgkin lymphoma (B-NHL), a great number of B-NHL patients treated with this immunotherapy still develop primary and secondary resistance. Recently Bruton’s tyrosine kinase (Btk) inhibitor ibrutinib showed promising therapeutic effect in relapsed/refractory CLL and B-cell NHL, which provided essential alternatives for these patients.

Methods

The proliferation and apoptosis induction of tumor cells were measured by cell viability assay and Annexin-V staining. Western Blotting analysis and real-time PCR were used to detect the expression level of target proteins and chemokines production.

Results

We demonstrated that ibrutinib inhibited the proliferation and induced apoptosis of GCB-DLBCL cell lines through suppression of BCR signaling pathway and activation of caspase-3. Furthermore, the chemokines CCL3 and CCL4 production from tumor cells were also found to be attenuated by ibrutinib treatment. But different cell lines exhibited distinct sensitivity after ibrutinib treatment. Interestingly, the decreasing level of p-ERK after ibrutinib treatment, but not the basal expression level of Btk, correlated with different drug sensitivity.

Conclusions

Ibrutinib could be a potentially useful therapy for GCB-DLBCL and the decreasing level of p-ERK could become a useful biomarker to predict related therapeutic response.

Ellagic acid inhibits PKC signaling by improving antioxidant defense system in murine T cell lymphoma

Antioxidants protect the cells from the damaging effects of reactive oxygen species (ROS). Production of ROS during cellular metabolism is balanced by their removal by antioxidants. Any condition leading to increased levels of ROS results in oxidative stress, which participates in multistage carcinogenesis by causing oxidative DNA damage, mutations in the proto-oncogenes and tumor suppressor genes. Antioxidant defense system is required to overcome the process of carcinogenesis generated by ROS. Antioxidant enzymes are major contributors to endogenous antioxidant defense system. Protein kinase C (PKC) is generally involved in cell proliferation and its over expression leads to abnormal tumor growth. Out of three classes of PKC, classical PKC is mainly involved in cell proliferation and tumor growth. Classical PKC initiates signaling pathway and leads to activation of a number of downstream protein via activation of NF-κB. Therefore any agent which can promotes the endogenous antioxidant defense system should be able to down regulate PKC and NF-κB activation and thus may be useful in reducing cancer progression. To investigate this hypothesis we have tested the effect of antioxidant ellagic acid on antioxidant enzymes and PKC signaling in Dalton's lymphoma bearing (DL) mice. DL mice were treated with three different doses of ellagic acid. The treatment significantly increases the activity and expression of antioxidant enzymes and down regulates the expression of classical isozymes of PKC as well as the activation of NF-κB, indicating that ellagic acid improves antioxidant defense system and PKC signaling via NF-κB which may contribute to its cancer preventive role.

Tumor-induced STAT3 signaling in myeloid cells impairs dendritic cell generation by decreasing PKCβII abundance

A major mechanism by which cancers escape control by the immune system is by blocking the differentiation of myeloid cells into dendritic cells (DCs), immunostimulatory cells that activate antitumor T cells. Tumor-dependent activation of signal transducer and activator of transcription 3 (STAT3) signaling in myeloid progenitor cells is thought to cause this block in their differentiation. In addition, a signaling pathway through protein kinase C βII (PKCβII) is essential for the differentiation of myeloid cells into DCs. We found in humans and mice that breast cancer cells substantially decreased the abundance of PKCβII in myeloid progenitor cells through a mechanism involving the enhanced activation of STAT3 signaling by soluble, tumor-derived factors (TDFs). STAT3 bound to previously undescribed negative regulatory elements within the promoter of PRKCB, which encodes PKCβII. We also found a previously undescribed counter-regulatory mechanism through which the activity of PKCβII inhibited tumor-dependent STAT3 signaling by decreasing the abundance of cell surface receptors, such as cytokine and growth factor receptors, that are activated by TDFs. Together, these data suggest that a previously unrecognized cross-talk mechanism between the STAT3 and PKCβII signaling pathways provides the molecular basis for the tumor-induced blockade in the differentiation of myeloid cells, and suggest that enhancing PKCβII activity may be a therapeutic strategy to alleviate cancer-mediated suppression of the immune system.

Midkine as a regulator of B cell survival in health and disease

In healthy individuals, the pool of peripheral lymphocytes is constant in size. The control of lymphoid homeostasis is the result of a very fine balance between lymphocyte production, survival and proliferation. Survival factors have been shown to play a critical role in maintaining the correct size of lymphocyte populations. Midkine, a heparin-binding cytokine was recently shown to be involved in cell proliferation, differentiation and apoptosis in various cell types including normal and malignant B cells. This review focuses on the role of midkine in the regulation of peripheral B cell survival in health and disease.

LINKED ARTICLES

This article is part of a themed section on Midkine. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-4.

Diffuse large B-cell lymphoma-treatment approaches in the molecular era

Diffuse large B-cell lymphoma (DLBCL) is an aggressive B-cell non-Hodgkin lymphoma that affects patients of all ages with a wide range of clinical presentations. Although DLBCL is curable even in advanced stages, up to one-third of patients will not achieve cure with initial therapy. In the modern era of rituximab-based therapy as the first-line treatment, the prognoses of patients who require salvage therapy are poor and most will eventually succumb to their disease. Insight into the complex molecular circuitry of DLBCL reveals a diverse range of somatic mutations and aberrant intracellular signalling pathways that characterize distinct molecular subsets of the disease. The next major breakthrough in DLBCL therapy during this 'molecular era' of disease definition will be the identification of combinations of novel agents that target the oncogenic drivers of these subsets. Well-conducted clinical trials, with translational molecular investigations, will be essential to achieve the goal of precision medicine and expand the number of patients with DLBCL who achieve a cure.