LCK is an important mediator of B-cell receptor signaling in chronic lymphocytic leukemia cells

Transcriptomic and proteomic differences in BTK-WT and BTK-mutated CLL and their changes during therapy with pirtobrutinib

ABSTRACT

Covalent Bruton tyrosine kinase inhibitors (cBTKis), which bind to the BTK C481 residue, are now primary therapeutics for chronic lymphocytic leukemia (CLL). Alterations at C481, primarily C481S, prevent cBTKi binding and lead to the emergence of resistant clones. Pirtobrutinib is a noncovalent BTKi that binds to both wild-type (WT) and C481S-mutated BTK and has shown efficacy in BTK-WT and -mutated CLL patient groups. To compare baseline clinical, transcriptomic, and proteomic characteristics and their changes during treatment in these 2 groups, we used 67 longitudinal peripheral blood samples obtained during the first 3 cycles of treatment with pirtobrutinib from 18 patients with CLL (11 BTK-mutated, 7 BTK-WT) enrolled in the BRUIN (pirtobrutinib in relapsed or refractory B-cell malignancies) trial. Eastern Cooperative Oncology Group performance status, age, and Rai stage were similar in both groups. At baseline, lymph nodes were larger in the BTK-mutated cohort. All patients achieved partial remission within 4 cycles of pirtobrutinib. Lactate dehydrogenase and β2-microglobulin levels decreased in both cohorts after 1 treatment cycle. Expression analysis demonstrated upregulation of 35 genes and downregulation of 6 in the BTK-mutated group. Gene set enrichment analysis revealed that the primary pathways enriched in BTK-mutated cells were involved in cell proliferation, metabolism, and stress response. Pathways associated with metabolism and proliferation were downregulated in both groups during pirtobrutinib treatment. Proteomic data corroborated transcriptomic findings. Our data identified inherent differences between BTK-mutated and -WT CLL and demonstrated molecular normalization of plasma and omics parameters with pirtobrutinib treatment in both groups.

Aberrant spliceosome activity via elevated intron retention and upregulation and phosphorylation of SF3B1 in chronic lymphocytic leukemia

Splicing factor 3b subunit 1 (SF3B1) is the largest subunit and core component of the spliceosome. Inhibition of SF3B1 was associated with an increase in broad intron retention (IR) on most transcripts, suggesting that IR can be used as a marker of spliceosome inhibition in chronic lymphocytic leukemia (CLL) cells. Furthermore, we separately analyzed exonic and intronic mapped reads on annotated RNA-sequencing transcripts obtained from B cells (n = 98 CLL patients) and healthy volunteers (n = 9). We measured intron/exon ratio to use that as a surrogate for alternative RNA splicing (ARS) and found that 66% of CLL-B cell transcripts had significant IR elevation compared with normal B cells (NBCs) and that correlated with mRNA downregulation and low expression levels. Transcripts with the highest IR levels belonged to biological pathways associated with gene expression and RNA splicing. A >2-fold increase of active pSF3B1 was observed in CLL-B cells compared with NBCs. Additionally, when the CLL-B cells were treated with macrolides (pladienolide-B), a significant decrease in pSF3B1, but not total SF3B1 protein, was observed. These findings suggest that IR/ARS is increased in CLL, which is associated with SF3B1 phosphorylation and susceptibility to SF3B1 inhibitors. These data provide additional support to the relevance of ARS in carcinogenesis and evidence of pSF3B1 participation in this process.

All-photonic kinase inhibitors: light-controlled release-and-report inhibition

Light-responsive molecular tools targeting kinases affords one the opportunity to study the underlying cellular function of selected kinases. In efforts to externally control lymphocyte-specific protein tyrosine kinase (LCK) activity, the development of release-and-report LCK inhibitors is described, in which (i) the release of the active kinase inhibitor can be controlled externally with light; and (ii) fluorescence is employed to report both the release and binding of the active kinase inhibitor. This introduces an unprecedented all-photonic method for users to both control and monitor real-time inhibitory activity. A functional cellular assay demonstrated light-mediated LCK inhibition in natural killer cells. The use of coumarin-derived caging groups resulted in rapid cellular uptake and non-specific intracellular localisation, while a BODIPY-derived caging group predominately localised in the cellular membrane. This concept of release-and-report inhibitors has the potential to be extended to other biorelevant targets where both spatiotemporal control in a cellular setting and a reporting mechanism would be beneficial.

Lymphocyte-Specific Protein Tyrosine Kinase Contributes to Spontaneous Regression of Liver Fibrosis may by Interacting with Suppressor of Cytokine Signaling 1

Quiescent hepatic stellate cells (qHSCs), converted to myofibroblasts, produce fibrous scars, which is an essential event during liver fibrogenesis. Clinical and experimental fibrosis undergo remarkable regression when the underlying etiological agent is removed. Some myofibroblasts revert to an inactive phenotype (iHSCs) during the regression of fibrosis. However, the mechanisms underlying HSC activation and reversal remain unclear. The present study demonstrated that the expression of lymphocyte-specific protein tyrosine kinase (LCK) was increased in fibrotic livers but decreased after spontaneous recovery in vivo and in vitro, which was correlated with the expression of α-smooth muscle actin (α-SMA) and type I collagen (COL-1). Further investigation indicated that specific knockdown of LCK by a recombination adeno-associated virus 9 (rAAV9) in C57BL/6 mice ameliorated liver fibrosis. Co-incubation of TGF-β1-induced HSC-T6 cells with LCK-siRNA inhibited cell proliferation and activation. Overexpression of LCK inhibited activated HSCs going to inactivated phenotype. Interestingly, we found that LCK may interact with suppressor of cytokine signaling 1 (SOCS1) and may influence the expression of p-JAK1 and p-STAT1/3. These data suggest that LCK may play a regulatory role in liver fibrosis by inhibiting SOCS1, indicating that LCK is a potential therapeutic target for liver fibrosis treatment.

Integrated signaling and transcriptome analysis reveals Src family kinase individualities and novel pathways controlled by their constitutive activity

The Src family kinases (SFKs) Lck and Lyn are crucial for lymphocyte development and function. Albeit tissue-restricted expression patterns the two kinases share common functions; the most pronounced one being the phosphorylation of ITAM motifs in the cytoplasmic tails of antigenic receptors. Lck is predominantly expressed in T lymphocytes; however, it can be ectopically found in B-1 cell subsets and numerous pathologies including acute and chronic B-cell leukemias. The exact impact of Lck on the B-cell signaling apparatus remains enigmatic and is followed by the long-lasting question of mechanisms granting selectivity among SFK members. In this work we sought to investigate the mechanistic basis of ectopic Lck function in B-cells and compare it to events elicited by the predominant B-cell SFK, Lyn. Our results reveal substrate promiscuity displayed by the two SFKs, which however, is buffered by their differential susceptibility toward regulatory mechanisms, revealing a so far unappreciated aspect of SFK member-specific fine-tuning. Furthermore, we show that Lck- and Lyn-generated signals suffice to induce transcriptome alterations, reminiscent of B-cell activation, in the absence of receptor/co-receptor engagement. Finally, our analyses revealed a yet unrecognized role of SFKs in tipping the balance of cellular stress responses, by promoting the onset of ER-phagy, an as yet completely uncharacterized process in B lymphocytes.

A Non-Canonical Role for the Glycosyltransferase Enzyme UGT2B17 as a Novel Constituent of the B Cell Receptor Signalosome

In chronic lymphocytic leukemia (CLL), an elevated glycosyltransferase UGT2B17 expression (UGT2B17HI) identifies a subgroup of patients with shorter survival and poor drug response. We uncovered a mechanism, possibly independent of its enzymatic function, characterized by an enhanced expression and signaling of the proximal effectors of the pro-survival B cell receptor (BCR) pathway and elevated Bruton tyrosine kinase (BTK) phosphorylation in B-CLL cells from UGT2B17HI patients. A prominent feature of B-CLL cells is the strong correlation of UGT2B17 expression with the adverse marker ZAP70 encoding a tyrosine kinase that promotes B-CLL cell survival. Their combined high expression levels in the treatment of naïve patients further defined a prognostic group with the highest risk of poor survival. In leukemic cells, UGT2B17 knockout and repression of ZAP70 reduced proliferation, suggesting that the function of UGT2B17 might involve ZAP70. Mechanistically, UGT2B17 interacted with several kinases of the BCR pathway, including ZAP70, SYK, and BTK, revealing a potential therapeutic vulnerability. The dual SYK and JAK/STAT6 inhibitor cerdulatinib most effectively compromised the proliferative advantage conferred by UGT2B17 compared to the selective BTK inhibitor ibrutinib. Findings point to an oncogenic role for UGT2B17 as a novel constituent of BCR signalosome also connected with microenvironmental signaling.

A novel peptide that disrupts the Lck-IP3R protein-protein interaction induces widespread cell death in leukemia and lymphoma

There is increasing evidence that the T-cell protein, Lck, is involved in the pathogenesis of chronic lymphocytic leukemia (CLL) as well as other leukemias and lymphomas. We previously discovered that Lck binds to domain 5 of inositol 1,4,5-trisphosphate receptors (IP3R) to regulate Ca2+ homeostasis. Using bioinformatics, we targeted a region within domain 5 of IP3R-1 predicted to facilitate protein-protein interactions (PPIs). We generated a synthetic 21 amino acid peptide, KKRMDLVLELKNNASKLLLAI, which constitutes a domain 5 sub-domain (D5SD) of IP3R-1 that specifically binds Lck via its SH2 domain. With the addition of an HIV-TAT sequence to enable cell permeability of D5SD peptide, we observed wide-spread, Ca2+-dependent, cell killing of hematological cancer cells when the Lck-IP3R PPI was disrupted by TAT-D5SD. All cell lines and primary cells were sensitive to D5SD peptide, but malignant T-cells were less sensitive compared with B-cell or myeloid malignancies. Mining of RNA-seq data showed that LCK was expressed in primary diffuse large B-cell lymphoma (DLBCL) as well as acute myeloid leukemia (AML). In fact, LCK shows a similar pattern of expression as many well-characterized AML oncogenes and is part of a protein interactome that includes FLT3-ITD, Notch-1, and Kit. Consistent with these findings, our data suggest that the Lck-IP3R PPI may protect malignant hematopoietic cells from death. Importantly, TAT-D5SD showed no cytotoxicity in three different non-hematopoietic cell lines; thus its ability to induce cell death appears specific to hematopoietic cells. Together, these data show that a peptide designed to disrupt the Lck-IP3R PPI has a wide range of pre-clinical activity in leukemia and lymphoma.

ArtinM Cytotoxicity in B Cells Derived from Non-Hodgkin's Lymphoma Depends on Syk and Src Family Kinases

Receptors on the immune cell surface have a variety of glycans that may account for the immunomodulation induced by lectins, which have a carbohydrate recognition domain (CRD) that binds to monosaccharides or oligosaccharides in a specific manner. ArtinM, a D-mannose-binding lectin obtained from Artocarpus heterophyllus, has affinity for the N-glycans core. Immunomodulation by ArtinM toward the Th1 phenotype occurs via its interaction with TLR2/CD14 N-glycans on antigen-presenting cells, as well as recognition of CD3γ N-glycans on murine CD4+ and CD8+ T cells. ArtinM exerts a cytotoxic effect on Jurkat human leukemic T-cell line and human myeloid leukemia cell line (NB4). The current study evaluated the effects of ArtinM on murine and human B cells derived from non-Hodgkin’s lymphoma. We found that murine B cells are recognized by ArtinM via the CRD, and the ArtinM stimulus did not augment the proliferation rate or production of IL-2. However, murine B cell incubation with ArtinM augmented the rate of apoptosis, and this cytotoxic effect of ArtinM was also seen in human B cell-lines sourced from non-Hodgkin’s lymphoma Raji cell line. This cytotoxic effect was inhibited by the phosphatase activity of CD45 on Lck, and the protein kinases of the Src family contribute to cell death triggered by ArtinM.

New insights into the Lck-NF-κB signaling pathway

Lck is essential for the development, activity, and proliferation of T cells, which may contribute to pathological progression and development of human diseases, such as autoimmune disorders and cancers when functioning aberrantly. Nuclear factor-κB (NF-κB) was initially discovered as a factor bound to the κ light-chain immunoglobulin enhancer in the nuclei of activated B lymphocytes. Activation of the nuclear factor-κB pathway controls expression of several genes that are related to cell survival, apoptosis, and inflammation. Abnormal expression of Lck and nuclear factor-κB has been found in autoimmune diseases and malignancies, including rheumatoid arthritis, systemic lupus erythematosus, acute T cell lymphocytic leukemia, and human chronic lymphocytic leukemia, etc. Nuclear factor-κB inhibition is effective against autoimmune diseases and malignancies through blocking inflammatory responses, although it may lead to serious adverse reactions that are unexpected and unwanted. Further investigation of the biochemical and functional interactions between nuclear factor-κB and other signaling pathways may be helpful to prevent side-effects. This review aims to clarify the Lck-nuclear factor-κB signaling pathway, and provide a basis for identification of new targets and therapeutic approaches against autoimmune diseases and malignancies.

CD160 receptor in CLL: Current state and future avenues

CD160 is a glycosylphosphatidylinositol (GPI)-anchored cell surface glycoprotein expressed on cytotoxic natural killer (NK) cells and T-cell subsets. It plays a crucial role in the activation of NK-cell cytotoxicity and cytokine production. It also modulates the immune system and is involved in some pathologies, such as cancer. CD160 is abnormally expressed in B-cell chronic lymphocytic leukemia (CLL) but not expressed in normal B lymphocytes. Its expression in CLL enhances tumor cell proliferation and resistance to apoptosis. CD160 is also a potential prognostic marker for the detection of minimal residual disease (MRD) in CLL, which is important for the clinical management of CLL, the prevention of disease relapse, and the achievement of complete remission. In this review, we present an overview of CD160 and its involvement in the pathophysiology of CLL. We also discuss its use as a prognostic marker for the assessment of MRD in CLL.

The lymphocyte-specific protein tyrosine kinase-specific inhibitor A-770041 attenuates lung fibrosis via the suppression of TGF-β production in regulatory T-cells

Background

Lymphocyte-specific protein tyrosine kinase (Lck) is a member of the Src family of tyrosine kinases. The significance of Lck inhibition in lung fibrosis has not yet been fully elucidated, even though lung fibrosis is commonly preceded by inflammation caused by infiltration of T-cells expressing Lck. In this study, we examined the effect of Lck inhibition in an experimental mouse model of lung fibrosis. We also evaluated the effect of Lck inhibition on the expression of TGF-β1, an inhibitory cytokine regulating the immune function, in regulatory T-cells (Tregs).

Methods

Lung fibrosis was induced in mice by intratracheal administration of bleomycin. A-770041, a Lck-specific inhibitor, was administrated daily by gavage. Tregs were isolated from the lung using a CD4⁺CD25⁺ Regulatory T-cell Isolation Kit. The expression of Tgfb on Tregs was examined by flow cytometry and quantitative polymerase chain reaction. The concentration of TGF-β in bronchoalveolar lavage fluid (BALF) and cell culture supernatant from Tregs was quantified by an enzyme-linked immunosorbent assay.

Results

A-770041 inhibited the phosphorylation of Lck in murine lymphocytes to the same degree as nintedanib. A-770041 attenuated lung fibrosis in bleomycin-treated mice and reduced the concentration of TGF-β in BALF. A flow-cytometry analysis showed that A-770041 reduced the number of Tregs producing TGF-β1 in the lung. In isolated Tregs, Lck inhibition by A-770041 decreased the Tgfb mRNA level as well as the concentration of TGF-β in the supernatant.

Conclusions

These results suggest that Lck inhibition attenuated lung fibrosis by suppressing TGF-β production in Tregs and support the role of Tregs in the pathogenesis of lung fibrosis.

Molecular profiling of core immune-escape genes highlights LCK as an immune-related prognostic biomarker in melanoma

The tumor microenvironment is complicated and continuously evolving. This study was devoted to the identification of potential prognostic biomarkers based on the tumor microenvironment associated with immunotherapy for melanoma. This study integrates a couple of melanoma single cell and transcriptome sequencing datasets and performs a series of silico analyses as nicely as validation of molecular biology techniques. A core set of immune escape related genes was identified through Lawson et al. and the ImmPort portal. The differential proteins were identified through the cBioPortal database. Regression analysis was used to profile independent prognostic factors. Correlation with the level of immune cell infiltration was evaluated by multiple algorithms. The capacity of LCK to predict response was assessed in two independent immunotherapy cohorts. High LCK expression is associated with better prognosis, high levels of TILs and better clinical staging. Pathway analysis showed that high expression of LCK was significantly associated with activation of multiple tumor pathways as well as immune-related pathways. LCK expression tends to be higher in immunotherapy-responsive patients and those with lower IC50s treated with chemotherapeutic agents. RT-qPCR detected that LCK expression was significantly upregulated in melanoma cell lines. Single-cell transcriptome analysis showed that LCK was specifically highly expressed on T cells. CellChat analysis confirmed that LCK in C2 subpopulations and T cell subpopulations exerted immune promotion between cells by binding to CD8 receptors. In conclusion, LCK is a reliable biomarker for melanoma and will contribute to its immunotherapy.

PAX5 fusion genes are frequent in poor risk childhood acute lymphoblastic leukaemia and can be targeted with BIBF1120

Background

Methods

Findings

Interpretation

Funding

Trimethylamine-N-oxide (TMAO) mediates the crosstalk between the gut microbiota and hepatic vascular niche to alleviate liver fibrosis in nonalcoholic steatohepatitis

Liver fibrosis is one main histological characteristic of nonalcoholic steatohepatitis (NASH), a disease paralleling a worldwide surge in metabolic syndromes with no approved therapies. The role of the gut microbiota in NASH pathogenesis has not been thoroughly illustrated, especially how the gut microbiota derives metabolites to influence the distal liver in NASH. Here, we performed 16S rDNA amplicon sequencing analysis of feces from a mouse NASH model induced by a Western diet and CCl4 injury and found genera under Streptococcaceae, Alcaligenaceae, Oscillibacter, and Pseudochrobactrum, which are related metabolites of TMAO. Injection of the gut microbial metabolite TMAO reduced the progression of liver fibrosis in the mouse NASH model. Further analysis revealed that the anti-fibrotic TMAO normalized gut microbiota diversity and preserved liver sinusoidal endothelial cell integrity by inhibiting endothelial beta 1-subunit of Na (+), K (+)-ATPase (ATP1B1) expression. Collectively, our findings suggest TMAO-mediated crosstalk between microbiota metabolites and hepatic vasculature, and perturbation of this crosstalk disrupts sinusoidal vasculature to promote liver fibrosis in NASH.

Enhanced Anti-Cancer Effects of Conditioned Medium from Hypoxic Human Adult Dermal Fibroblasts on Cervical Cancer Cells

Hypoxia regulates fibroblast function by changing intracellular signaling and secretion factors, that influence the states of nearby cells. In this work, we investigated how medium (CM) from human adult dermal fibroblasts (HDFs) cultured in normoxic and hypoxic conditions affected cervical cancer (HeLa) cells. The HeLa cells showed decreased cell viability, increased apoptosis, and cell cycle arrest in response to CM from hypoxic-cultured HDFs (H-CM) compared with CM from normoxic-cultured HDFs (N-CM). Among the proteins up-regulated (>2-fold) in H-CM compared with N-CM, lymphotoxin-beta receptor (LTBR) decreased the viability of HeLa cells. Among the intracellular proteins down-regulated (>2-fold) in HeLa cells treated with H-CM compared with N-CM, the most enriched biological process GO term and KEGG pathway were protein deubiquitination and hsa05166:HTLV-I infection, respectively. In the protein−protein interaction network of intracellular proteins with altered expression (>2-fold), 1 up-regulated (TNF) and 8 down-regulated (ESR1, MCL1, TBP, CD19, LCK, PCNA, CHEK1, and POLA1) hub proteins were defined. Among the down-regulated hub proteins, the most enriched biological process GO term and KEGG pathway were leading strand elongation and hsa05166:HTLV-I infection, respectively. This study reveals that H-CM had stronger anti-cancer effects on cervical cancer cells than N-CM and induced intracellular signaling patterns related to those enhanced anti-cancer effects.

Role of Programmed Cell Death Protein-1 and Lymphocyte Specific Protein Tyrosine Kinase in the Aryl Hydrocarbon Receptor- Mediated Impairment of the IgM Response in Human CD5+ Innate-Like B Cells

Innate-like B cells (ILBs) are a heterogeneous population B cells which participate in innate and adaptive immune responses. This diverse subset of B cells is characterized by the expression of CD5 and has been shown to secrete high levels of immunoglobulin M (IgM) in the absence of infection or vaccination. Further, CD5+ ILBs have been shown to express high basal levels of lymphocyte specific protein tyrosine kinase (LCK) and programmed cell death protein-1 (PD-1), which are particularly sensitive to stimulation by interferon gamma (IFNγ). Previous studies have demonstrated that activation of the aryl hydrocarbon receptor (AHR), a cytosolic ligand-activated transcription factor, results in suppressed IgM responses and is dependent on LCK. A recent study showed that CD5+ ILBs are particularly sensitive to AHR activation as evidenced by a significant suppression of the IgM response compared to CD5- B cells, which were refractory. Therefore, the objective of this study was to further investigate the role of LCK and PD-1 signaling in AHR-mediated suppression of CD5+ ILBs. In addition, studies were conducted to establish whether IFNγ alters the levels of LCK and PD-1 in CD5+ ILBs. We found that AHR activation led to a significant upregulation of total LCK and PD-1 proteins in CD5+ ILBs, which correlated with suppression of IgM. Interestingly, treatment with recombinant IFNγ reduced LCK protein levels and reversed AHR-mediated IgM suppression in CD5+ ILBs in a similar manner as LCK inhibitors. Collectively, these results support a critical role for LCK and PD-1 in AHR-mediated suppression of the IgM response in human CD5+ ILBs.

Identification of novel immunomodulators in lung squamous cell carcinoma based on transcriptomic data

Cells in the tumor microenvironment are well known for their role in cancer development and prognosis. The processes of genetic changes and possible remodeling in the tumor microenvironment of lung squamous cell carcinoma, on the other hand, are mainly unclear. In this investigation, 1164 immunological differentially expressed genes (DEGs) were shown to have predictive significance. A prognostic model with high prediction accuracy was constructed using these genes and survival data. There were 1020 upregulated genes and 144 downregulated genes found, with 57 genes found to be important in the development of LUSC. We used least absolute shrinkage and selection operator (LASSO) regression analysis to determine the risk profiles of 9 genes based on the expression values of 57 prognosis-related genes. The AUCs of the developed prognostic model for predicting patient survival at 1, 3, and 5 years were 0.66, 0.61, and 0.63, respectively, based on the training data. For immune-correlation analysis in this survival model, we chose IGLC7, which was seen to predict patient survival with high accuracy. The effects on immune cells and synergistic effects with other immunomodulators were then investigated. We discovered that IGLC7 is involved in immune response and inflammatory activity using gene ontology analysis and genomic sequence variance analysis (GSVA), with a potential effect, especially on B cells and T cells. In conclusion, IGLC7 expression levels are related to the malignancy of LUSC based on the constructed prognostic model and can thus be a therapeutic target for patients with LUSC. Furthermore, IGLC7 may work in concert with other immune checkpoint members to regulate the immune microenvironment of LUSC. These discoveries might lead to a fresh understanding of the complicated interactions between cancer cells and the tumor microenvironment, particularly the population of immune cells, and a novel approach to future immunotherapeutic treatments for patients with LUSC.

Role of antifibrotics in the management of idiopathic inflammatory myopathy associated interstitial lung disease

The antifibrotic therapies nintedanib and pirfenidone were first approved by the United States for the treatment of idiopathic pulmonary fibrosis in 2014. In 2020, nintedanib received U.S. Food and Drug Administration (FDA) approval for the treatment of all progressive fibrosing interstitial lung disease (ILD). Given that a major cause of mortality and morbidity in the idiopathic inflammatory myopathies (IIM) is progressive interstitial lung disease and respiratory failure, antifibrotic therapies may be useful as adjuvant to traditional immunosuppression. However, randomized controlled trials of antifibrotic therapies in IIM are lacking. The purpose of this review is to (1) summarize the mechanism of action of nintedanib and pirfenidone in ILD with possible role in IIM-ILD, (2) review the clinical data supporting their use in interstitial lung disease in general, and more specifically in connective tissue disease associated ILD, and (3) discuss the evidence and remaining challenges for using antifibrotic therapies in IIM-ILD.

BCL-2 Inhibitor ABT-737 Effectively Targets Leukemia-Initiating Cells with Differential Regulation of Relevant Genes Leading to Extended Survival in a NRAS/BCL-2 Mouse Model of High Risk-Myelodysplastic Syndrome

During transformation, myelodysplastic syndromes (MDS) are characterized by reducing apoptosis of bone marrow (BM) precursors. Mouse models of high risk (HR)-MDS and acute myelogenous leukemia (AML) post-MDS using mutant NRAS and overexpression of human BCL-2, known to be poor prognostic indicators of the human diseases, were created. We have reported the efficacy of the BCL-2 inhibitor, ABT-737, on the AML post-MDS model; here, we report that this BCL-2 inhibitor also significantly extended survival of the HR-MDS mouse model, with reductions of BM blasts and lineage negative/Sca1+/KIT+ (LSK) cells. Secondary transplants showed increased survival in treated compared to untreated mice. Unlike the AML model, BCL-2 expression and RAS activity decreased following treatment and the RAS:BCL-2 complex remained in the plasma membrane. Exon-specific gene expression profiling (GEP) of HR-MDS mice showed 1952 differentially regulated genes upon treatment, including genes important for the regulation of stem cells, differentiation, proliferation, oxidative phosphorylation, mitochondrial function, and apoptosis; relevant in human disease. Spliceosome genes, found to be abnormal in MDS patients and downregulated in our HR-MDS model, such as Rsrc1 and Wbp4, were upregulated by the treatment, as were genes involved in epigenetic regulation, such as DNMT3A and B, upregulated upon disease progression and downregulated upon treatment.

New horizons in drug discovery of lymphocyte-specific protein tyrosine kinase (Lck) inhibitors: a decade review (2011-2021) focussing on structure-activity relationship (SAR) and docking insights

Lymphocyte-specific protein tyrosine kinase (Lck), a non-receptor Src family kinase, has a vital role in various cellular processes such as cell cycle control, cell adhesion, motility, proliferation, and differentiation. Lck is reported as a key factor regulating the functions of T-cell including the initiation of TCR signalling, T-cell development, in addition to T-cell homeostasis. Alteration in expression and activity of Lck results in numerous disorders such as cancer, asthma, diabetes, rheumatoid arthritis, atherosclerosis, and neuronal diseases. Accordingly, Lck has emerged as a novel target against different diseases. Herein, we amass the research efforts in literature and pharmaceutical patents during the last decade to develop new Lck inhibitors. Additionally, structure-activity relationship studies (SAR) and docking models of these new inhibitors within the active site of Lck were demonstrated offering deep insights into their different binding modes in a step towards the identification of more potent, selective, and safe Lck inhibitors.

Dermatan Sulfate Is a Potential Regulator of IgH via Interactions With Pre-BCR, GTF2I, and BiP ER Complex in Pre-B Lymphoblasts

Dermatan sulfate (DS) and autoantigen (autoAg) complexes are capable of stimulating autoreactive CD5+ B1 cells. We examined the activity of DS on CD5+ pre-B lymphoblast NFS-25 cells. CD19, CD5, CD72, PI3K, and Fas possess varying degrees of DS affinity. The three pre-BCR components, Ig heavy chain mu (IgH), VpreB, and lambda 5, display differential DS affinities, with IgH having the strongest affinity. DS attaches to NFS-25 cells, gradually accumulates in the ER, and eventually localizes to the nucleus. DS and IgH co-localize on the cell surface and in the ER. DS associates strongly with 17 ER proteins (e.g., BiP/Grp78, Grp94, Hsp90ab1, Ganab, Vcp, Canx, Kpnb1, Prkcsh, Pdia3), which points to an IgH-associated multiprotein complex in the ER. In addition, DS interacts with nuclear proteins (Ncl, Xrcc6, Prmt5, Eftud2, Supt16h) and Lck. We also discovered that DS binds GTF2I, a required gene transcription factor at the IgH locus. These findings support DS as a potential regulator of IgH in pre-B cells at protein and gene levels. We propose a (DS•autoAg)-autoBCR dual signal model in which an autoBCR is engaged by both autoAg and DS, and, once internalized, DS recruits a cascade of molecules that may help avert apoptosis and steer autoreactive B cell fate. Through its affinity with autoAgs and its control of IgH, DS emerges as a potential key player in the development of autoreactive B cells and autoimmunity.

Integrative Transcriptomic, Proteomic and Functional Analysis Reveals ATP1B3 as a Diagnostic and Potential Therapeutic Target in Hepatocellular Carcinoma

The Na+/K+-ATPase (NKA), has been proposed as a signal transducer involving various pathobiological processes, including tumorigenesis. However, the clinical relevance of NKA in hepatocellular carcinoma (HCC) has not been well studied. This study revealed the upregulation of mRNA of ATP1A1, ATP1B1, and ATP1B3 in HCC using TCGA, ICGC, and GEO database. Subsequently, ATP1B3 was demonstrated as an independent prognostic factor of overall survival (OS) of HCC. To investigate the potential mechanisms of ATP1B3 in HCC, we analyzed the co-expression network using LinkedOmics and found that ATP1B3 co-expressed genes were associated with immune-related biological processes. Furthermore, we found that ATP1B3 was correlated immune cell infiltration and immune-related cytokines expression in HCC. The protein level of ATP1B3 was also validated as a prognostic significance and was correlated with immune infiltration in HCC using two proteomics datasets. Finally, functional analysis revealed that ATP1B3 was increased in HCC cells and tissues, silenced ATP1B3 repressed HCC cell proliferation, migration, and promoted HCC cell apoptosis and epithelial to mesenchymal transition (EMT). In conclusion, these findings proved that ATP1B3 could be an oncogene and it was demonstrated as an independent prognostic factor and correlated with immune infiltration in HCC, revealing new insights into the prognostic role and potential immune regulation of ATP1B3 in HCC progression and provide a novel possible therapeutic strategy for HCC.

The multi-kinase inhibitor TG02 induces apoptosis and blocks B-cell receptor signaling in chronic lymphocytic leukemia through dual mechanisms of action

The constitutive activation of B-cell receptor (BCR) signaling, together with the overexpression of the Bcl-2 family anti-apoptotic proteins, represents two hallmarks of chronic lymphocytic leukemia (CLL) that drive leukemia cell proliferation and sustain their survival. TG02 is a small molecule multi-kinase inhibitor that simultaneously targets both of these facets of CLL pathogenesis. First, its inhibition of cyclin-dependent kinase 9 blocked the activation of RNA polymerase II and transcription. This led to the depletion of Mcl-1 and rapid induction of apoptosis in the primary CLL cells. This mechanism of apoptosis was independent of CLL prognostic factors or prior treatment history, but dependent on the expression of BAX and BAK. Second, TG02, which inhibits the members of the BCR signaling pathway such as Lck and Fyn, blocked BCR-crosslinking-induced activation of NF-κB and Akt, indicating abrogation of BCR signaling. Finally, the combination of TG02 and ibrutinib demonstrated moderate synergy, suggesting a future combination of TG02 with ibrutinib, or use in patients that are refractory to the BCR antagonists. Thus, the dual inhibitory activity on both the CLL survival pathway and BCR signaling identifies TG02 as a unique compound for clinical development in CLL and possibly other B cell malignancies.

Genetic Loss of LCK Kinase Leads to Acceleration of Chronic Lymphocytic Leukemia

Most patients with chronic lymphocytic leukemia (CLL) exhibit an indolent disease course and unresponsive B cell receptors (BCRs) exemplified by an anergic phenotype of their leukemic cells. In up to 5% of patients, CLL transforms from an indolent subtype to an aggressive form of B cell lymphoma (Richter's syndrome), which is associated with worse disease outcome and severe downregulation of NFAT2. Here we show that ablation of the tyrosine kinase LCK, which has previously been characterized as a main NFAT2 target gene in CLL, leads to loss of the anergic phenotype, thereby restoring BCR signaling, which results in an acceleration of CLL. Our study identifies LCK as a main player in mediating BCR unresponsiveness and its role as a crucial regulator of anergy in CLL.

LCK expression is a potential biomarker for distinguishing primary central nervous system lymphoma from glioblastoma multiforme

Glioblastoma multiforme (GBM) and primary central nervous system lymphoma (PCNSL) are both malignant cerebral tumors; however, their treatments are vastly different. Early and precise diagnosis is vital for subsequent adequate treatment to improve prognosis. Reliable biomarkers that can easily distinguish GBM and PCNSL are urgently needed. We evaluated the diagnostic potential of lymphocyte‐specific protein tyrosine kinase (LCK) as a biomarker in differentiating PCNSL from GBM using established computational approaches (Gene Expression Profiling Interactive Analysis, The Cancer Proteome Atlas, Tumor Immune Estimation Resource, GEO, Oncomine) and immunohistochemistry. The results showed that LCK was expressed at a high level in PCNSL patients but at a low level in GBM patients. Moreover, LCK expression positively correlated with the levels of infiltrating B cells in diffuse large B‐cell lymphoma (DLBCL) and GBM. Overall, bioinformatics analysis and immunohistochemistry revealed that LCK expression is a potential biomarker for distinguishing PCNSL from GBM.

Integrated systems analysis of salivary gland transcriptomics reveals key molecular networks in Sjögren's syndrome

Background

Treatment of patients with Sjögren’s syndrome (SjS) is a clinical challenge with high unmet needs. Gene expression profiling and integrative network-based approaches to complex disease can offer an insight on molecular characteristics in the context of clinical setting.

Methods

An integrated dataset was created from salivary gland samples of 30 SjS patients. Pathway-driven enrichment profiles made by gene set enrichment analysis were categorized using hierarchical clustering. Differentially expressed genes (DEGs) were subjected to functional network analysis, where the elements of the core subnetwork were used for key driver analysis.

Results

We identified 310 upregulated DEGs, including nine known genetic risk factors and two potential biomarkers. The core subnetwork was enriched with the processes associated with B cell hyperactivity. Pathway-based subgrouping revealed two clusters with distinct molecular signatures for the relevant pathways and cell subsets. Cluster 2, with low-grade inflammation, showed a better response to rituximab therapy than cluster 1, with high-grade inflammation. Fourteen key driver genes appeared to be essential signaling mediators downstream of the B cell receptor (BCR) signaling pathway and to have a positive relationship with histopathology scores.

Conclusion

Integrative network-based approaches provide deep insights into the modules and pathways causally related to SjS and allow identification of key targets for disease. Intervention adjusted to the molecular traits of the disease would allow the achievement of better outcomes, and the BCR signaling pathway and its leading players are promising therapeutic targets.

Beyond TCR Signaling: Emerging Functions of Lck in Cancer and Immunotherapy

In recent years, the lymphocyte-specific protein tyrosine kinase (Lck) has emerged as one of the key molecules regulating T-cell functions. Studies using Lck knock-out mice or Lck-deficient T-cell lines have shown that Lck regulates the initiation of TCR signaling, T-cell development, and T-cell homeostasis. Because of the crucial role of Lck in T-cell responses, strategies have been employed to redirect Lck activity to improve the efficacy of chimeric antigen receptors (CARs) and to potentiate T-cell responses in cancer immunotherapy. In addition to the well-studied role of Lck in T cells, evidence has been accumulated suggesting that Lck is also expressed in the brain and in tumor cells, where it actively takes part in signaling processes regulating cellular functions like proliferation, survival and memory. Therefore, Lck has emerged as a novel druggable target molecule for the treatment of cancer and neuronal diseases. In this review, we will focus on these new functions of Lck.

Ectopic Lck expression in CLL demarcates intratumoral subpopulations with aberrant B-cell receptor signaling

Ectopic Lck expression signifies interpatient and intratumoral heterogeneity in CLL. Lck expression identifies CLL subpopulations with aberrant BCR signaling.

Exploration of the therapeutic aspects of Lck: A kinase target in inflammatory mediated pathological conditions

Lck, a non-receptor src family kinase, plays a vital role in various cellular processes such as cell cycle control, cell adhesion, motility, proliferation and differentiation. As a 56 KDa protein, Lck phosphorylates tyrosine residues of various proteins such as ZAP-70, ITK and protein kinase C. The structure of Lck is comprised of three domains, one SH3 in tandem with a SH2 domain at the amino terminal and the kinase domain at the carboxy terminal. Physiologically, Lck is involved in the development, function and differentiation of T-cells. Additionally, Lck regulates neurite outgrowth and maintains long-term synaptic plasticity in neurons. Given a major role of Lck in cytokine production and T cell signaling, alteration in expression and activity of Lck may result in various diseased conditions like cancer, asthma, diabetes, rheumatoid arthritis, psoriasis, inflammatory bowel diseases such as Crohn's disease and ulcerative colitis, atherosclerosis etc. This article provides evidence and information establishing Lck as one of the therapeutic targets in various inflammation mediated pathophysiological conditions.

Lymphocyte-Specific Protein Tyrosine Kinase (LCK) is Involved in the Aryl Hydrocarbon Receptor-Mediated Impairment of Immunoglobulin Secretion in Human Primary B Cells

The aryl hydrocarbon receptor (AHR) is a cytosolic ligand-activated transcription factor involved in xenobiotic sensing, cell cycle regulation, and cell development. In humans, the activation of AHR by 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), a high affinity AHR-ligand, impairs the secretion of immunoglobulin M (IgM) to suppress humoral immunity. However, the mechanisms bridging the activation of AHR and the impairment of IgM secretion by human primary B cells remain poorly understood. Recent transcriptomic analysis revealed upregulation of lymphocyte-specific protein tyrosine kinase (LCK) in AHR-activated human primary B cells. LCK is a well-characterized tyrosine kinase that phosphorylates critical signaling proteins involved in activation and cytokine production in T cells. Conversely, the role of LCK in human primary B cells is not well understood. In the current studies, we have verified the transcriptomic finding by detecting AHR-mediated upregulation of LCK protein in human primary B cells. We also confirmed the role of AHR in the upregulation of LCK by using a specific AHR antagonist, which abolished the AHR-mediated increase of LCK. Furthermore, we have confirmed the role of LCK in the AHR-mediated suppression of IgM by using LCK specific inhibitors, which restored the IgM secretion by human B cells in the presence of TCDD. Collectively, the current studies demonstrate a novel role of LCK in IgM response and provide new insights into the mechanism for AHR-mediated impairment of immunoglobulin secretion by human primary B cells.

Prevalence of cytogenetic abnormalities in chronic lymphocytic leukemia in the southern part of Turkey

BACKGROUND

Chronic lymphocytic leukemia (CLL) is the most common type of leukemia among adults in Western populations. CLL has a wide range of clinical presentations and varied outcomes. For CLL, cytogenetic assessment is essential for estimating prognoses and determining the treatment of choice. The fluorescence in situ hybridization (FISH) technique is widely used for genetic assessment due to its high sensitivity.

AIM

This study aimed to evaluate the frequencies of deletions of 13q14.3, 17p13.1, 11q22.3, and 13q34 and of trisomy 12 and to observe their effects on survival in 226 Turkish CLL patients using FISH analysis.

RESULT AND CONCLUSION

The frequencies of abnormalities were 65.4% for del 13q14.3, 39.8% for del 17p13.1, 19% for del 11q22.3 (del ATM), and 15.9% for trisomy 12. No patients had a 13q34.3 aberration. Our results are partially consistent with literature findings. However, certain conflicts with prior results were observed, particularly with respect to the high prevalence of 17p13.1 deletions and the enhanced survival of patients with such deletions. These inconsistencies may represent population-based differences in the genetic epidemiology of CLL.

Bioinformatic identification of key genes and pathways that may be involved in the pathogenesis of HBV-associated acute liver failure

In order to explore the molecular mechanisms behind the pathogenesis of acute liver failure (ALF) associated with hepatitis B virus (HBV) infection, the present study aimed to identify potential key genes and pathways involved using samples from patients with HBV-associated ALF. The GSE38941 array dataset was downloaded from the Gene Expression Omnibus database, and differentially expressed genes (DEGs) between 10 liver samples from 10 healthy donors and 17 liver specimens from 4 patients with HBV-associated ALF were analyzed using the Linear Models for Microarray Data package. Gene Ontology and KEGG pathway enrichment analyses of the DEGs were performed, followed by functional annotation of the genes and construction of a protein–protein interaction (PPI) network. Subnetwork modules were subsequently identified and analyzed. In total, 3142 DEGs were identified, of which 1755 were upregulated and 1387 were downregulated. The extracellular exosome, immune response, and inflammatory response pathways may potentially be used as biomarkers of ALF pathogenesis. In total, 17 genes (including CCR5, CXCR4, ALB, C3, VGEFA, and IGF1) were identified as hub genes in the PPI network and may therefore be potential marker genes for HBV-associated ALF.

A combination of an anti-SLAMF6 antibody and ibrutinib efficiently abrogates expansion of chronic lymphocytic leukemia cells

The signaling lymphocyte activation molecule family [SLAMF] of cell surface receptors partakes in both the development of several immunocyte lineages and innate and adaptive immune responses in humans and mice. For instance, the homophilic molecule SLAMF6 (CD352) is in part involved in natural killer T cell development, but also modulates T follicular helper cell and germinal B cell interactions. Here we report that upon transplantation of a well-defined aggressive murine B220⁺CD5⁺ Chronic Lymphocytic Leukemia (CLL) cell clone, TCL1-192, into SCID mice one injection of a monoclonal antibody directed against SLAMF6 (αSlamf6) abrogates tumor progression in the spleen, bone marrow and blood. Similarly, progression of a murine B cell lymphoma, LMP2A/λMyc, was also eliminated by αSlamf6. But, surprisingly, αSLAMF6 neither eliminated TCL1-192 nor LMP2A/λMyc cells, which resided in the peritoneal cavity or omentum. This appeared to be dependent upon the tumor environment, which affected the frequency of sub-populations of the TCL1-192 clone or the inability of peritoneal macrophages to induce Antibody Dependent Cellular Cytotoxicity (ADCC). However, co-administering αSlamf6 with the Bruton tyrosine kinase (Btk) inhibitor, ibrutinib, synergized to efficiently eliminate the tumor cells in the spleen, bone marrow, liver and the peritoneal cavity. Because an anti-human SLAMF6 mAb efficiently killed human CLL cells in vitro and in vivo, we propose that a combination of αSlamf6 with ibrutinib should be considered as a novel therapeutic approach for CLL and other B cell tumors.

Lck is a relevant target in chronic lymphocytic leukaemia cells whose expression variance is unrelated to disease outcome

Pathogenesis of chronic lymphocytic leukaemia (CLL) is contingent upon antigen receptor (BCR) expressed by malignant cells of this disease. Studies on somatic hypermutation of the antigen binding region, receptor expression levels and signal capacity have all linked BCR on CLL cells to disease prognosis. Our previous work showed that the src-family kinase Lck is a targetable mediator of BCR signalling in CLL cells, and that variance in Lck expression associated with ability of BCR to induce signal upon engagement. This latter finding makes Lck similar to ZAP70, another T-cell kinase whose aberrant expression in CLL cells also associates with BCR signalling capacity, but also different because ZAP70 is not easily pharmacologically targetable. Here we describe a robust method of measuring Lck expression in CLL cells using flow cytometry. However, unlike ZAP70 whose expression in CLL cells predicts prognosis, we find Lck expression and disease outcome in CLL are unrelated despite observations that its inhibition produces effects that biologically resemble the egress phenotype taken on by CLL cells treated with idelalisib. Taken together, our findings provide insight into the pathobiology of CLL to suggest a more complex relationship between expression of molecules within the BCR signalling pathway and disease outcome.

Encoding optical control in LCK kinase to quantitatively investigate its activity in live cells

LCK is a tyrosine kinase essential for initiating T-cell antigen receptor (TCR) signaling. A complete understanding of LCK function is constrained by a paucity of methods to quantitatively study its function within live cells. To address this limitation, we generated LCK*, in which a key active site lysine is replaced by a photo-caged equivalent, using genetic code expansion. This enabled fine temporal and spatial control over kinase activity, allowing us to quantify phosphorylation kinetics in situ using biochemical and imaging approaches. We find that auto-phosphorylation of the LCK active site loop is indispensable for its catalytic activity and that LCK can stimulate its own activation by adopting a more open conformation, which can be modulated by point mutations. We then show that CD4 and CD8, the T cell coreceptors, can enhance LCK activity, helping to explain their effect in physiological TCR signaling. Our approach also provides general insights into SRC-family kinase dynamics.

NFAT2 is a critical regulator of the anergic phenotype in chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is a clonal disorder of mature B cells. Most patients are characterised by an indolent disease course and an anergic phenotype of their leukaemia cells, which refers to a state of unresponsiveness to B cell receptor stimulation. Up to 10% of CLL patients transform from an indolent subtype to an aggressive form of B cell lymphoma over time (Richter´s syndrome) and show a significantly worse treatment outcome. Here we show that B cell-specific ablation of Nfat2 leads to the loss of the anergic phenotype culminating in a significantly compromised life expectancy and transformation to aggressive disease. We further define a gene expression signature of anergic CLL cells consisting of several NFAT2-dependent genes including Cbl-b, Grail, Egr2 and Lck. In summary, this study identifies NFAT2 as a crucial regulator of the anergic phenotype in CLL.NFAT2 is a transcription factor that has been linked with chronic lymphocytic leukaemia (CLL), but its functions in CLL manifestation are still unclear. Here the authors show, by analysing mouse CLL models and characterising biopsies from CLL patients, that NFAT2 is an important regulator for the anergic phenotype of CLL.

A novel BLK-induced tumor model

B-lymphoid tyrosine kinase (BLK) is a non-receptor tyrosine kinase belonging to the SRC family kinases. BLK is known to be functionally involved in B-cell receptor signaling and B-cell development. New evidence suggests that B-lymphoid tyrosine kinase is ectopically expressed and is a putative oncogene in cutaneous T-cell lymphoma and other T-cell malignancies. However, little is known about the role of BLK in lymphomagenesis, and the oncogenic function seems to depend on the cellular context. Importantly, BLK is also ectopically expressed in other hematological and multiple non-hematological malignancies including breast, kidney, and lung cancers, suggesting that BLK could be a new potential target for therapy. Here, we studied the oncogenic potential of human BLK. We found that engrafted Ba/F3 cells stably expressing constitutive active human BLK formed tumors in mice, whereas neither Ba/F3 cells expressing wild type BLK nor non-transfected Ba/F3 cells did. Inhibition of BLK with the clinical grade and broadly reacting SRC family kinase inhibitor dasatinib inhibited growth of BLK-induced tumors. In conclusion, our study provides evidence that human BLK is a true proto-oncogene capable of inducing tumors, and we demonstrate a novel BLK activity-dependent tumor model suitable for studies of BLK-driven lymphomagenesis and screening of novel BLK inhibitors in vivo.

Modulation of B-cell receptor and microenvironment signaling by a guanine exchange factor in B-cell malignancies

OBJECTIVE

Chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL) cells over-express a guanine exchange factor (GEF), Rasgrf-1. This GEF increases active Ras as it catalyzes the removal of GDP from Ras so that GTP can bind and activate Ras. This study aims to study the mechanism of action of Rasgrf-1 in B-cell malignancies.

METHODS

N-terminus truncated Rasgrf-1 variants have a higher GEF activity as compared to the full-length transcript therefore a MCL cell line with stable over-expression of truncated Rasgrf-1 was established. The B-cell receptor (BCR) and chemokine signaling pathways were compared in the Rasgrf-1 over-expressing and a control transfected cell line.

RESULTS

Cells over-expressing truncated form of Rasgrf-1 have a higher proliferative rate as compared to control transfected cells. BCR was activated by lower concentrations of anti-IgM antibody in Rasgrf-1 over-expressing cells as compared to control cells indicating that these cells are more sensitive to BCR signaling. BCR signaling also phosphorylates Rasgrf-1 that further increases its GEF function and amplifies BCR signaling. This activation of Rasgrf-1 in over-expressing cells resulted in a higher expression of phospho-ERK, AKT, BTK and PKC-alpha as compared to control cells. Besides BCR, Rasgrf-1 over-expressing cells were also more sensitive to microenvironment stimuli as determined by resistance to apoptosis, chemotaxis and ERK pathway activation.

CONCLUSIONS

This GEF protein sensitizes B-cells to BCR and chemokine mediated signaling and also upregulates a number of other signaling pathways which promotes growth and survival of these cells.

SLP76 integrates into the B-cell receptor signaling cascade in chronic lymphocytic leukemia cells and is associated with an aggressive disease course

I In the last decade, the B-cell receptor has emerged as a pivotal stimulus in the pathogenesis of chronic lymphocytic leukemia, and a very feasible therapeutic target in this disease. B-cell receptor responsiveness in chronic lymphocytic leukemia cells is heterogeneous among patients and correlates with aggressiveness of the disease. Here we show, for the first time, that SLP76, a key scaffold protein in T-cell receptor signaling, is ectopically expressed in chronic lymphocytic leukemia cells, with variable levels among patients, and correlates positively with unmutated immunoglobulin heavy chain variable gene status and ZAP-70 expression. We found that SLP76 was functionally active in chronic lymphocytic leukemia cells. A SYK-dependent basal level of phosphorylated SLP76 exists in the cells, and upon B-cell receptor engagement, SLP76 tyrosine phosphorylation is significantly enhanced concomitantly with increased physical association with BTK. B-cell receptor-induced SLP76 phosphorylation is mediated by upstream signaling events involving LCK and SYK. Knockdown of SLP76 in the cells resulted in decreased induction of BTK, PLCγ2 and IκB phosphorylation, as well as cell viability after B-cell receptor activation with anti-IgM. Consistent with our biochemical findings, high total SLP76 expression in chronic lymphocytic leukemia cells correlated with a more aggressive disease course.

IN CONCLUSION

SLP76 is ectopically expressed in chronic lymphocytic leukemia cells where it plays a role in B-cell receptor signaling.

Lenalidomide Induces Interleukin-21 Production by T Cells and Enhances IL21-Mediated Cytotoxicity in Chronic Lymphocytic Leukemia B Cells

The immunomodulatory drug lenalidomide has demonstrated efficacy in patients with chronic lymphocytic leukemia (CLL), despite a lack of direct cytotoxic effects in vitro The mechanism of lenalidomide efficacy in vivo is thought to occur via a combination of enhanced immune activity and an alteration of tumor cell-microenvironment interactions. We demonstrate in whole blood from patients with CLL that lenalidomide significantly depletes malignant B cells. Lenalidomide also induced production of interleukin-21 (IL21) and its mRNA in T cells from patients with CLL. In addition, lenalidomide enhanced upregulation of functional IL21 receptor (IL21R) on the cell surface and increased receptor mRNA in vitro The in vitro combination of IL21 and lenalidomide enhanced IL21-mediated cytotoxicity toward CLL cells through a variety of mechanisms. We show association of cell death with upregulation of Bid by IL21, enhanced upregulation of Bid by the combination therapy, and diminished Lck and downstream BCR signaling activation of Syk and PLCG2. Collectively, we demonstrated an immune cell-tumor cell interaction through lenalidomide-mediated induction of IL21 and IL21R, with enhanced IL21-mediated cytotoxicity, which provides justification for this combination in clinical trials for patients with CLL. Cancer Immunol Res; 4(8); 698-707. ©2016 AACR.

Targeting B-cell receptor signaling in leukemia and lymphoma: how and why?

B-lymphocytes are dependent on B-cell receptor (BCR) signaling for the constant maintenance of their physiological function, and in many B-cell malignancies this signaling pathway is prone to aberrant activation. This understanding has led to an ever-increasing interest in the signaling networks activated following ligation of the BCR in both normal and malignant cells, and has been critical in establishing an array of small molecule inhibitors targeting BCR-induced signaling. By dissecting how different malignancies signal through BCR, researchers are contributing to the design of more customized therapeutics which have greater efficacy and lower toxicity than previous therapies. This allows clinicians access to an array of approaches to best treat patients whose malignancies have BCR signaling as a driver of pathogenesis.

RPPA-based protein profiling reveals eIF4G overexpression and 4E-BP1 serine 65 phosphorylation as molecular events that correspond with a pro-survival phenotype in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL), the most common adult leukemia, remains incurable despite advancements in treatment regimens over the past decade. Several expression profile studies have been pursued to better understand CLL pathogenesis. However, these large-scale studies only provide information at the transcriptional level. To better comprehend the differential protein changes that take place in CLL, we performed a reverse-phase protein array (RPPA) analysis using 167 different antibodies on B-cell lysates from 18 CLL patients and 6 normal donors. From our analysis, we discovered an enrichment of protein alterations involved with mRNA translation, specifically upregulation of the translation initiator eIF4G and phosphorylation of the cap-dependent translation inhibitor 4E-BP1 at serine 65. Interestingly, 4E-BP1 phosphorylation occurred independently of AKT phosphorylation, suggesting a disconnect between PI3K/AKT pathway activation and 4E-BP1 phosphorylation. Based on these results, we treated primary CLL samples with NVP-BEZ235, a PI3K/mTOR dual inhibitor, and compared its apoptotic-inducing potential against the BTK inhibitor Ibrutinib and the PI3Kδ inhibitor Idelalisib. We demonstrated that treatment with NVP-BEZ235 caused greater apoptosis, greater apoptotic cleavage of eIF4G, and greater dephosphorylation of 4E-BP1 in primary CLL cells. Taken together, these results highlight the potential dependence of eIF4G overexpression and 4E-BP1 phosphorylation in CLL survival.

Gene expression and splicing alterations analyzed by high throughput RNA sequencing of chronic lymphocytic leukemia specimens

Background

To determine differentially expressed and spliced RNA transcripts in chronic lymphocytic leukemia specimens a high throughput RNA-sequencing (HTS RNA-seq) analysis was performed.

Methods

Ten CLL specimens and five normal peripheral blood CD19+ B cells were analyzed by HTS RNA-seq. The library preparation was performed with Illumina TrueSeq RNA kit and analyzed by Illumina HiSeq 2000 sequencing system.

Results

An average of 48.5 million reads for B cells, and 50.6 million reads for CLL specimens were obtained with 10396 and 10448 assembled transcripts for normal B cells and primary CLL specimens respectively. With the Cuffdiff analysis, 2091 differentially expressed genes (DEG) between B cells and CLL specimens based on FPKM (fragments per kilobase of transcript per million reads and false discovery rate, FDR q < 0.05, fold change >2) were identified. Expression of selected DEGs (n = 32) with up regulated and down regulated expression in CLL from RNA-seq data were also analyzed by qRT-PCR in a test cohort of CLL specimens. Even though there was a variation in fold expression of DEG genes between RNA-seq and qRT-PCR; more than 90 % of analyzed genes were validated by qRT-PCR analysis. Analysis of RNA-seq data for splicing alterations in CLL and B cells was performed by Multivariate Analysis of Transcript Splicing (MATS analysis). Skipped exon was the most frequent splicing alteration in CLL specimens with 128 significant events (P-value <0.05, minimum inclusion level difference >0.1).

Conclusion

The RNA-seq analysis of CLL specimens identifies novel DEG and alternatively spliced genes that are potential prognostic markers and therapeutic targets. High level of validation by qRT-PCR for a number of DEG genes supports the accuracy of this analysis. Global comparison of transcriptomes of B cells, IGVH non-mutated CLL (U-CLL) and mutated CLL specimens (M-CLL) with multidimensional scaling analysis was able to segregate CLL and B cell transcriptomes but the M-CLL and U-CLL transcriptomes were indistinguishable. The analysis of HTS RNA-seq data to identify alternative splicing events and other genetic abnormalities specific to CLL is an added advantage of RNA-seq that is not feasible with other genome wide analysis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1708-9) contains supplementary material, which is available to authorized users.

Machine Learning-based Classification of Diffuse Large B-cell Lymphoma Patients by Their Protein Expression Profiles

Characterization of tumors at the molecular level has improved our knowledge of cancer causation and progression. Proteomic analysis of their signaling pathways promises to enhance our understanding of cancer aberrations at the functional level, but this requires accurate and robust tools. Here, we develop a state of the art quantitative mass spectrometric pipeline to characterize formalin-fixed paraffin-embedded tissues of patients with closely related subtypes of diffuse large B-cell lymphoma. We combined a super-SILAC approach with label-free quantification (hybrid LFQ) to address situations where the protein is absent in the super-SILAC standard but present in the patient samples. Shotgun proteomic analysis on a quadrupole Orbitrap quantified almost 9,000 tumor proteins in 20 patients. The quantitative accuracy of our approach allowed the segregation of diffuse large B-cell lymphoma patients according to their cell of origin using both their global protein expression patterns and the 55-protein signature obtained previously from patient-derived cell lines (Deeb, S. J., D'Souza, R. C., Cox, J., Schmidt-Supprian, M., and Mann, M. (2012) Mol. Cell. Proteomics 11, 77–89). Expression levels of individual segregation-driving proteins as well as categories such as extracellular matrix proteins behaved consistently with known trends between the subtypes. We used machine learning (support vector machines) to extract candidate proteins with the highest segregating power. A panel of four proteins (PALD1, MME, TNFAIP8, and TBC1D4) is predicted to classify patients with low error rates. Highly ranked proteins from the support vector analysis revealed differential expression of core signaling molecules between the subtypes, elucidating aspects of their pathobiology.

B-cell receptor signaling in the pathogenesis of lymphoid malignancies

B-cell receptor (BCR) signaling pathway plays a central role in B-lymphocyte development and initiation of humoral immunity. Recently, BCR signaling pathway has been shown as a major driver in the pathogenesis of B-cell malignancies. As a result, a vast array of BCR-associated kinases has emerged as rational therapeutic targets changing treatment paradigms in B cell malignancies. Based on high efficacy in early-stage clinical trials, there is rapid clinical development of inhibitors targeting BCR signaling pathway. Here, we describe the essential components of BCR signaling, their function in normal and pathogenic signaling and molecular effects of their inhibition in vitro and in vivo.

LCK over-expression drives STAT5 oncogenic signaling in PAX5 translocated BCP-ALL patients

The PAX5 gene is altered in 30% of BCP-ALL patients and PAX5 chromosomal translocations account for 2-3% of cases. Although PAX5 fusion genes significantly affect the transcription of PAX5 target genes, their role in sustaining leukemia cell survival is poorly understood. In an in vitro model of PAX5/ETV6 leukemia, we demonstrated that Lck hyper-activation, and down-regulation of its negative regulator Csk, lead to STAT5 hyper-activation and consequently to the up-regulation of the downstream effectors, cMyc and Ccnd2. More important, cells from PAX5 translocated patients show LCK up-regulation and over-activation, as well as STAT5 hyper-phosphorylation, compared to PAX5 wt and PAX5 deleted cases. As in BCR/ABL1 positive ALL, the hyper-activation of STAT5 pathway can represent a survival signal in PAX5 translocated cells, alternative to the pre-BCR, which is down-regulated. The LCK inhibitor BIBF1120 selectively reverts this phenomenon both in the murine model and in leukemic primary cells. LCK inhibitor could therefore represent a suitable candidate drug to target this subgroup of ALL patients.

Src family kinases and their role in hematological malignancies

The Src family protein tyrosine kinases (SFKs) are non-receptor intracellular kinases that have important roles in both hematopoiesis and leukemogenesis. The derangement of their expression or activation has been demonstrated to contribute to hematological malignancies. This review first examines the mechanisms of SFK overexpression and hyperactivation, emphasizing the dysregulation of the upstream modulators. Subsequently, the role of SFK up-regulation in the initiation, progression and therapy resistance of many hematological malignancies is also analyzed. The presented evidence endeavors to highlight the influence of SFK up-regulation on an extensive number of hematological malignancies and the need to consider them as candidates in targeted anticancer therapy.

Molecular basis of chronic lymphocytic leukemia diagnosis and prognosis

BACKGROUNDS

Chronic lymphocytic leukemia (CLL) is the most common type of leukemia in adults and is characterized by a clonal accumulation of mature apoptosis-resistant neoplastic cells. It is also a heterogeneous disease with a variable clinical outcome. Here, we present a review of currently known (epi)genetic alterations that are related to the etiology, progression and chemo-refractoriness of CLL. Relevant literature was identified through a PubMed search (1994-2014) of English-language papers using the terms CLL, signaling pathway, cytogenetic abnormality, somatic mutation, epigenetic alteration and micro-RNA.

RESULTS

CLL is characterized by the presence of gross chromosomal abnormalities, epigenetic alterations, micro-RNA expression alterations, immunoglobulin heavy chain gene mutations and other genetic lesions. The expression of unmutated immunoglobulin heavy chain variable region (IGHV) genes, ZAP-70 and CD38 proteins, the occurrence of chromosomal abnormalities such as 17p and 11q deletions and mutations of the NOTCH1, SF3B1 and BIRC3 genes have been associated with a poor prognosis. In addition, mutations in tumor suppressor genes, such as TP53 and ATM, have been associated with refractoriness to conventional chemotherapeutic agents. Micro-RNA expression alterations and aberrant methylation patterns in genes that are specifically deregulated in CLL, including the BCL-2, TCL1 and ZAP-70 genes, have also been encountered and linked to distinct clinical parameters.

CONCLUSIONS

Specific chromosomal abnormalities and gene mutations may serve as diagnostic and prognostic indicators for disease progression and survival. The identification of these anomalies by state-of-the-art molecular (cyto)genetic techniques such as fluorescence in situ hybridization (FISH), comparative genomic hybridization (CGH), single nucleotide polymorphism (SNP) microarray-based genomic profiling and next-generation sequencing (NGS) can be of paramount help for the clinical management of these patients, including optimal treatment design. The efficacy of novel therapeutics should to be tested according to the presence of these molecular lesions in CLL patients.