Spleen Tyrosine Kinase Expression Research Articles

Abstract 1185: Novel association of an autoimmune-related axis and anti-CTLA-4-based toxicities in adjuvant immunotherapy-treated melanoma patients

Abstract Intro: Immune checkpoint inhibition (ICI) for metastatic unresectable melanoma has markedly improved survival, and has shown benefit as adjuvant (AT) and neoadjuvant (NAT) therapy. Although ICI treatments confer survival benefit, they frequently induce immune-related adverse events (irAEs), which are a substantial clinical problem, particularly in AT/NAT, where ICI is used in less advanced disease to prevent recurrence. As such, the biomarkers predicting irAE risk, in particular in AT/NAT, are urgently needed to improve patient outcomes. Methods: We assessed RNA from pre-treatment peripheral CD4+ and CD8+ T cells from adjuvant clinical trial patients (CheckMate-915; n=212 patients) treated with Nivolumab (n=130) or Ipilimumab/Nivolumab (Combo) (n=82). We performed RNA-seq differential expression analysis to identify baseline differences in the immune profiles of patients with no/mild toxicity (grade 0-2) versus severe toxicity (grade 3-5). Results: Gene ontology analysis of the differentially expressed genes (DEGs) among those with severe toxicity reveals significant enrichment of immune-related pathways (IL-2, IFN-gamma, T-cell receptors, Toll-like receptors). These are shared among cell types (CD4+/CD8+) and between treatments (Nivo/Combo). From predicted DEG protein-protein interactions, we identified a treatment- and cell-type-specific expression signature associated with irAE development in CD4+ cells from Combo-treated patients. This signature, involving genes in the spleen tyrosine kinase (SYK) pathway, correctly predicts severe irAE patients with 73% accuracy (chi-squared p-value=0.001). The signature also identifies patients with mild to moderate irAEs in organ systems previously found in autoimmune traits to be associated with SYK upregulation (including skin, GI, liver, and pancreas), with 96% of all predicted patients experiencing at least one of these SYK-related toxicities, and 79% experiencing two or more. Importantly, the signature is not associated with disease recurrence (p=0.79). Conclusions: We have identified baseline expression differences in key immune pathways in peripheral T cells from ICI-treated patients with severe irAEs, and defined an SYK-related gene signature correctly identifying over half of severe irAE patients in the Combo-treated cohort. This finding aligns with our previous work linking anti-CTLA-4 irAEs with a germline variant associated with high SYK expression. This gene signature may not only serve as a baseline biomarker of severe irAEs, but it may also help guide treatment decisions, reducing toxicity while retaining efficacy, which will be particularly important in the adjuvant setting. Citation Format: Kelsey R. Monson, Robert Ferguson, Joanna Handzlik, Jiahan Xiong, Sasha Dagayev, Leah Morales, Vylyny Chat, Anabelle Bunis, Chaitra Sreenivasaiah, Sonia Dolfi, Daniel Tenney, Iman Osman, Jeffrey Weber, Tomas Kirchhoff. Novel association of an autoimmune-related axis and anti-CTLA-4-based toxicities in adjuvant immunotherapy-treated melanoma patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1185.

Apolipoprotein C3 (ApoC3) facilitates NLRP3 mediated pyroptosis of macrophages through mitochondrial damage by accelerating of the interaction between SCIMP and SYK pathway in acute lung injury

Respiratory failure caused by severe acute lung injury (ALI) is the main cause of mortality in patients with COVID-19.This study aimed to investigate the effects and underlying biological mechanism of Apolipoprotein C3 (ApoC3) in ALI.To establish an in vivo model, C57BL/6 mice were exposed by lipopolysaccharide (LPS). For the in vitro model, murine bone marrow-derived macrophages (BMDMs) or RAW264.7 cells were stimulated with LPS + adenosine triphosphate (ATP).Serum levels of ApoC3 were found to be upregulated in patients with COVID-19 or pneumonia-induced ALI. Inhibition of ApoC3 reduced lung injury in an ALI model, while overexpression of ApoC3 promoted lung injury. ApoC3 induced mitochondrial damage-mediated pyroptosis in ALI through the activation of the NOD-like receptorprotein 3 (NLRP3) inflammasome. ApoC3 recombinant protein significantly increased SCIMP expression in the lung tissue of mice models with ALI. ApoC3 also facilitated the interaction between the SLP adapter and CSK-interacting membrane protein (SCIMP) protein and Spleen tyrosine kinase (SYK) protein in the ALI model. Moreover, ApoC3 accelerated calcium-dependent reactive oxygen species (ROS) production in the ALI model. The effects of ApoC3 on pyroptosis were mitigated by the use of a pyroptosis inhibitor or an ROS inhibitor in the ALI model. Furthermore, ApoC3 activated the expression of SYK, which in turn induced NLRP3 inflammasome-regulated pyroptosis in the ALI model. METTL3 was found to mediate the m6A mRNA expression of ApoC3.Overall, our study highlights the crucial role of ApoC3 in promoting macrophage pyroptosis in ALI through calcium-dependent ROS production and NLRP3 inflammasome activation via the SCIMP-SYK pathway, providing a potential therapeutic strategy for ALI and other inflammatory diseases.

Spleen tyrosine kinase facilitates the progression of papillary thyroid cancer regulated by the hsa_circ_0006417/miR-377-3p axis.

Papillary thyroid cancer (PTC) is a prevalent malignancy worldwide. Spleen tyrosine kinase (SYK) is a crucial enzyme that participates in various biological processes, including cancer progression. This study aims to uncover the biological function of SYK in PTC. SYK expression patterns in PTC were evaluated using quantitative real time polymerase chain reaction (qRT-PCR), immunohistochemistry (IHC), and western blot. Cell function assays were performed to assess the effects of SYK on PTC. Bioinformatics analysis was conducted to identify intriguing microRNA (miRNA) and circular RNA (circRNA). Dual-Luciferase Reporter or RNA immunoprecipitation assays were used to investigate the correlation among SYK, miR-377-3p, and hsa_circ_0006417. SYK was upregulated in PTC. Overexpression of SYK exhibited a positive correlation with tumor size, lymph node metastasis, and unfavorable disease-free survival. Functional assays revealed that SYK exerted tumorigenic effect on PTC cells through mTOR/4E-BP1 pathway. Mechanistically, hsa_circ_0006417 and miR-377-3p regulated SYK expression, offering modulating its tumor-promoting effects. Collectively, SYK acts as an oncogene in PTC through mTOR/4E-BP1 pathway, which is regulated by the hsa_circ_0006417/miR-377-3p axis, thereby providing a potential alternative for PTC treatment.

Prognostic biomarker SYK and its correlation with immune infiltrates in glioma.

The tumor microenvironment (TME) provides excellent conditions for the development of glioma. The present study sought to identify the prognostic factors of glioma that could be used to improve the prognosis of patients with this disease. In the present study, Cell-type Identification by Estimating Relative Subsets of RNA Transcripts (CIBERSORT) and Estimation of Stromal and Immune cells in Malignant Tumor tissues using Expression data calculations were employed to estimate the ratio of tumor-infiltrating immune cells and the quantity of immune and stromal components in 698 glioma cases from the Cancer Genome Atlas database. In addition, certain differentially expressed genes were studied by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses and single genes associated with prognosis were identified by protein-protein interaction (PPI) network and Cox combined analysis. The immune and stromal scores of the TME were significantly associated with glioma patient survival. By using the PPI network and Cox regression analyses, spleen tyrosine kinase (SYK) was eventually identified as the best prognostic factor for patients with glioma. In addition, Gene Set Enrichment Analysis and CIBERSORT analyses were employed. The former indicated that the high-expression SYK group genes were mainly enriched in immune-related activities. The latter revealed that SYK expression was positively associated with T cell cluster of differentiation 4 memory resting and monocytes. The aforementioned experimental analyses provided the theoretical basis for the biological prediction of SYK. The data indicated that SYK contributed to immune predictors in patients with glioma by facilitating the shift of the TME from immune dominance to metabolic activity. Finally, reverse transcription-quantitative PCR and western blotting were used to verify the single gene expression in glioma cells. This may provide prognostic value for the treatment of glioma.

In vivo activity of the dual SYK/FLT3 inhibitor TAK-659 against pediatric acute lymphoblastic leukemia xenografts.

While children with acute lymphoblastic leukemia (ALL) experience close to a 90% likelihood of cure, the outcome for certain high-risk pediatric ALL subtypes remains dismal. Spleen tyrosine kinase (SYK) is a prominent cytosolic nonreceptor tyrosine kinase in pediatric B-lineage ALL (B-ALL). Activating mutations or overexpression of Fms-related receptor tyrosine kinase 3 (FLT3) are associated with poor outcome in hematological malignancies. TAK-659 (mivavotinib) is a dual SYK/FLT3 reversible inhibitor, which has been clinically evaluated in several other hematological malignancies. Here, we investigate the in vivo efficacy of TAK-659 against pediatric ALL patient-derived xenografts (PDXs). SYK and FLT3mRNA expression was quantified by RNA-seq. PDX engraftment and drug responses in NSG mice were evaluated by enumerating the proportion of human CD45+ cells (%huCD45+ ) in the peripheral blood. TAK-659 was administered per oral at 60mg/kg daily for 21 days. Events were defined as %huCD45+ ≥ 25%. In addition, mice were humanely killed to assess leukemia infiltration in the spleen and bone marrow (BM). Drug efficacy was assessed by event-free survival and stringent objective response measures. FLT3 and SYK mRNA expression was significantly higher in B-lineage compared with T-lineage PDXs. TAK-659 was well tolerated and significantly prolonged the time to event in six out of eight PDXs tested. However, only one PDX achieved an objective response. The minimum mean %huCD45+ was significantly reduced in five out of eight PDXs in TAK-659-treated mice compared with vehicle controls. TAK-659 exhibited low to moderate single-agent in vivo activity against pediatric ALL PDXs representative of diverse subtypes.

A Phase I Trial of SYK Inhibition with Fostamatinib in the Prevention and Treatment of Chronic Graft-Versus-Host Disease

Despite the exciting advancement of novel therapies, chronic graft-versus-host disease (cGVHD) remains the most common cause of non-relapse mortality after allogeneic hematopoietic stem cell transplantation (HCT). Frontline treatment of cGVHD involves systemic steroids, which are associated with significant morbidities. We previously found that inhibition of spleen tyrosine kinase (SYK) with fostamatinib preferentially eradicated aberrantly activated B cells in both ex vivo studies of cGVHD patient B cells, as well as in vivo mouse studies. These and other preclinical studies implicated hyper-reactive B-cell receptor signaling and increased SYK expression in the pathogenesis of cGVHD and compelled this first in-human allogeneic HCT clinical trial. We investigated the safety and efficacy of the oral SYK inhibitor, fostamatinib, for both the prevention and treatment of cGVHD. The primary objective was to evaluate the safety of fostamatinib and determine its maximum tolerated dose in the post-HCT setting. Secondary objectives included assessing the efficacy of fostamatinib in preventing and treating cGVHD, as well as examining alterations in B-cell compartments with treatment. This was a single-institution phase I clinical trial that evaluated the use of fostamatinib in allogeneic HCT patients before the development of cGVHD or at the time of steroid-refractory cGVHD (SR-cGVHD). Patients received fostamatinib at one of three dose levels using a continual reassessment algorithm to determine the maximum tolerated dose. Multiparameter flow cytometry was used to evaluate changes in B cell subpopulations over the first year of treatment with fostamatinib. Nineteen patients were enrolled in this phase I trial, with 5 in the prophylaxis arm and 14 in the therapeutic arm. One patient (5%) required discontinuation of therapy for a dose-limiting toxicity. At a median follow-up of over 3 years, no patients had cancer relapse while on fostamatinib treatment, and recurrent malignancy was observed in 1 patient 2 years after the end of therapy. In the prophylaxis arm, 1 of 5 patients (20%) developed cGVHD while on fostamatinib. In the therapeutic arm, the overall response rate was 77%, with a complete response rate of 31%. The median duration of response was 19.3 months and the 12-month failure-free survival was 69% (95% confidence interval, 48-100). Patients were able to reduce their steroid dose by a median of 80%, with 73% remaining on a lower dose at 1 year compared to baseline. There was an early reduction in the proportion of IgD−CD38hi plasmablast-like cells with fostamatinib treatment, particularly in those SR-cGVHD patients who had an eventual response. B-cell reconstitution was not significantly impacted by fostamatinib therapy after allogeneic HCT. Fostamatinib featured a favorable safety profile in the post-HCT setting. Our data suggests an early efficacy signal that was associated with effects on expected cell targets in both the prophylaxis and treatment of cGVHD, providing rationale for a phase II investigation.

Hox transcript antisense RNA knockdown inhibits osteosarcoma progression by regulating the phosphoinositide 3-kinase/AKT pathway through the microRNA miR-6888-3p/spleen tyrosine kinase axis

ABSTRACT Long non-coding RNA HOX transcript antisense RNA (lncRNA HOTAIR) is thought to be a key regulator of the occurrence and development of osteosarcoma (OS). The expression of HOTAIR, microRNA miR-6888-3p, spleen tyrosine kinase (SYK), and phosphoinositide 3-kinase/AKT (PI3K/AKT) pathway-related proteins in OS was detected by quantitative reverse transcription-PCR (qRT-PCR) and western blotting. Changes in the proliferation and migration of OS cells were detected by Cell Counting Kit-8 (CCK-8) and transwell assays after the knockdown of HOTAIR, miR-6888-3p, or SYK. Luciferase assays, RNA immunoprecipitation (RIP), and RNA pull-down assays were used to detect the relationship between miR-6888-3p and HOTAIR or SYK. We found that HOTAIR and SYK were highly expressed in OS, whereas miR-6888-3p expression was low. In addition, downregulation of HOTAIR or SYK significantly inhibited the growth and migration of OS cells and the PI3K/AKT pathway, both in vitro and in vivo. Additionally, downregulation of miR-6888-3p promoted the proliferation and migration of OS cells and activated the PI3K/AKT pathway. Mechanistically, these results suggest that the HOTAIR sponge, miR-6888-3p, regulates SYK expression. To summarize, HOTAIR regulates SYK by acting on miR-6888-3p, thereby promoting the proliferation and migration of OS cells.

Histone methyltransferase DOT1L mediates the TGF-β1/Smad3 signaling pathway through epigenetic modification of SYK in myocardial infarction.

Myocardial infarction (MI) represents the most critical condition in coronary artery disease, and the fibrotic process, detrimental to optimal recovery, often sustains. In the present work, we assessed whether suppression of disruptor of telomeric silencing 1-like (DOT1L) could alleviate fibrosis in vivo and cardiac fibroblast (CFS) proliferation in vitro, and elucidated the possible mechanism involved in these events. After left coronary artery ligation, we found that the MI mice exhibited a decrease in cardiac function, along with evident MI and myocardial fibrosis. In addition, AngII increased CFS viability and migration, and enhanced the expression of fibrotic proteins. Inhibition of DOT1L ameliorated proliferation and fibrosis in CFS. Furthermore, DOT1L promoted the expression of spleen tyrosine kinase (SYK) by increasing the H3K79me2 modification of the SYK promoter. SYK upregulation reversed the inhibitory effect of DOT1L knockdown on CFS proliferation and fibrosis by activating the TGF-β1/Smad3 signaling. SYK also mitigated the ameliorative effect of DOT1L knockdown on myocardial injury and fibrosis caused by MI in vivo. In conclusion, these data indicated that DOT1L depletion might be a promising therapeutic target for fibrosis in MI.

SYK-3BP2 Pathway Activity in Parenchymal and Myeloid Cells Is a Key Pathogenic Factor in Metabolic Steatohepatitis.

Background & AimsSpleen tyrosine kinase (SYK) signaling pathway regulates critical processes in innate immunity, but its role in parenchymal cells remains elusive in chronic liver diseases. We investigate the relative contribution of SYK and its substrate c-Abl Src homology 3 domain-binding protein-2 (3BP2) in both myeloid cells and hepatocytes in the onset of metabolic steatohepatitis.MethodsHepatic SYK-3BP2 pathway was evaluated in mouse models of metabolic-associated fatty liver diseases (MAFLD) and in obese patients with biopsy-proven MAFLD (n = 33). Its role in liver complications was evaluated in Sh3bp2 KO and myeloid-specific Syk KO mice challenged with methionine and choline deficient diet and in homozygous Sh3bp2KI/KI mice with and without SYK expression in myeloid cells.ResultsHere we report that hepatic expression of 3BP2 and SYK correlated with metabolic steatohepatitis severity in mice. 3BP2 deficiency and SYK deletion in myeloid cells mediated the same protective effects on liver inflammation, injury, and fibrosis priming upon diet-induced steatohepatitis. In primary hepatocytes, the targeting of 3BP2 or SYK strongly decreased the lipopolysaccharide-mediated inflammatory mediator expression and 3BP2-regulated SYK expression. In homozygous Sh3bp2KI/KI mice, the chronic inflammation mediated by the proteasome-resistant 3BP2 mutant promoted severe hepatitis and liver fibrosis with augmented liver SYK expression. In these mice, the deletion of SYK in myeloid cells was sufficient to prevent these liver lesions. The hepatic expression of SYK is also up-regulated with metabolic steatohepatitis and correlates with liver macrophages in biopsy-proven MAFLD patients.ConclusionsCollectively, these data suggest an important role for the SYK-3BP2 pathway in the pathogenesis of chronic liver inflammatory diseases and highlight its targeting in hepatocytes and myeloid cells as a potential strategy to treat metabolic steatohepatitis.

Abstract 3039: Pediatric preclinical testing consortium evaluation of the dual SYK/FLT3 inhibitor TAK-659 in xenograft models of pediatric acute lymphoblastic leukemia

Abstract Introduction: While children with acute lymphoblastic leukemia (ALL) experience close to a 90% likelihood of cure, the outcome for certain high-risk pediatric ALL subtypes remains poor. Spleen Tyrosine Kinase (SYK), a cytosolic nonreceptor tyrosine kinase, is primarily expressed in the hematopoietic lineage and is essential for B-cell receptor signaling. It is associated with malignant transformation, cancer cell proliferation, and is a prominent tyrosine-phosphorylated protein in B-lineage pediatric ALL (Dolai et al, Cancer Res 76:2766-77, 2016). Fms Related Receptor Tyrosine Kinase 3 (FLT3) is a Class III receptor tyrosine kinase that regulates hematopoiesis. While uncommon in ALL, activating FLT3 mutations and internal tandem duplications are associated with poor outcome. TAK-659 is a dual SYK/FLT3 reversible inhibitor currently undergoing clinical trials against B-cell lymphoma, acute myeloid leukemia and solid tumors. Therefore, it was of interest for the Pediatric Preclinical Testing Consortium to test TAK-659 in vivo against its patient-derived xenograft (PDX) models of pediatric ALL. Methods: SYK and FLT3 mRNA expression in ALL PDXs was quantified by RNAseq (https://pedcbioportal.org) and 8 B-lineage pediatric ALL PDXs (3 B-cell precursor, BCP; 4 mixed-lineage leukemia-rearranged, MLLr; one Philadelphia Chromosome-like, Ph-like) were selected for testing. Engraftment was evaluated by enumerating the proportion of human CD45+ cells (%huCD45+) in the peripheral (PB) blood at weekly intervals. TAK-659 was tested at 60 mg/kg by oral gavage daily for 21 days. Events were defined as %huCD45+ ≥ 25%. At Day 28 post-treatment initiation or event (whichever occurred first), 4 mice/group were humanely killed to assess leukemia infiltration in the spleen and bone marrow (BM). Drug efficacy was assessed by event-free survival (EFS) of treated (T) and control (C) groups by T-C, T/C and stringent objective response measures (Houghton et al, Pediatr Blood Cancer 49:928-40, 2007). Results: The in vivo efficacy of TAK-659 was evaluated against B-lineage PDXs as FLT3 and SYK mRNA expression was higher in the PDXs from this lineage compared with PDXs from T-ALL. TAK-659 was well tolerated and significantly prolonged the time to event in 6/8 PDXs (T-C 0-25.5 days, T/C 1.0-2.2). Only one MLLr-ALL obtained an objective response (partial response) with all other models exhibiting progressive disease. The minimum mean %huCD45+ was significantly reduced in 5/8 PDXs in TAK-659 treated mice compared to control. Despite significant reductions in %huCD45+ in the PB for 5/8 PDXs, TAK-659 did not significantly reduce the spleen or BM infiltration of any PDXs. Conclusion: TAK-659 exhibited low to moderate single-agent in vivo activity against pediatric B-ALL PDXs representative of diverse disease subtypes. (Supported by NCI Grants CA199000 and CA199922) Citation Format: Richard B. Lock, Kathryn Evans, Narimanne El-Zein, Eric J. Earley, Stephen W. Erickson, Beverly A. Teicher, Malcolm A. Smith. Pediatric preclinical testing consortium evaluation of the dual SYK/FLT3 inhibitor TAK-659 in xenograft models of pediatric acute lymphoblastic leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3039.

How Aconiti Radix Cocta can Treat Gouty Arthritis Based on Systematic Pharmacology and UPLC-QTOF-MS/MS.

Background: Gouty arthritis (GA) is a common metabolic disease caused by a long-term disorder of purine metabolism and increased serum levels of uric acid. The processed product of dried root of Aconitum carmichaeli Debeaux (Aconiti Radix cocta, ARC) is used often in traditional Chinese medicine (TCM) to treat GA, but its specific active components and mechanism of action are not clear. Methods: First, we used ultra-performance liquid chromatography-quadrupole/time-of-flight tandem mass spectrometry to identify the chemical spectrum of ARC. Based on this result, we explored the active components of ARC in GA treatment and their potential targets and pathways. Simultaneously, we used computer simulations, in vitro cell experiments and animal experiments to verify the prediction results of systems pharmacology. In vitro, we used aurantiamide acetate (AA) to treat monosodium urate (MSU)-stimulated THP-1 cells and demonstrated the reliability of the prediction by western blotting and real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR). ELISAs kit were used to measure changes in levels of proinflammatory factors in rats with GA induced by MSU to demonstrate the efficacy of ARC in GA treatment. Results: Forty-three chemical constituents in ARC were identified. ARC could regulate 65 targets through 29 active components, and then treat GA, which involved 1427 Gene Ontology (GO) terms and 146 signaling pathways. Signaling pathways such as proteoglycans in cancer, C-type lectin receptor signaling pathway, and TNF signaling pathway may have an important role in GA treatment with ARC. In silico results showed that the active components songoramine and ignavine had high binding to mitogen-activated protein kinase p38 alpha (MAPK14) and matrix metallopeptidase (MMP)9, indicating that ARC treatment of GA was through multiple components and multiple targets. In vitro experiments showed that AA in ARC could effectively reduce expression of MAPK14, MMP9, and cyclooxygenase2 (PTGS2) in THP-1 cells stimulated by MSU, whereas it could significantly inhibit the mRNA expression of Caspase-1, spleen tyrosine kinase (SYK), and PTGS2. Animal experiments showed that a ARC aqueous extract could significantly reduce expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and intereleukin (IL)-18 in the serum of GA rats stimulated by MSU. Hence, ARC may inhibit inflammation by regulating the proteoglycans in cancer-associated signaling pathways. Conclusion: ARC treatment of GA may have the following mechanisms, ARC can reduce MSU crystal-induced joint swelling, reduce synovial tissue damage, and reduce the expression of inflammatory factors in serum. AA in ARC may inhibit inflammation by regulating the protein expression of MAPK14, MMP9, and PTGS2 and the mRNA expression of caspase-1, SYK, and PTGS2.

Brusatol Derivative-34 Attenuates Allergic Airway Inflammation Via Inhibition of the Spleen Tyrosine Kinase Pathway.

Brusatol derivative-34 (Bru-34), a derivative of brusatol, has been shown significantly anti-inflammatory activity in mice in our previously work. However, to our knowledge, there were very limited studies on how Bru-34 affected airway inflammation. Thus, in this present study, the effects and potential mechanisms of Bru-34 on allergic airway inflammation were examined both in vivo and in vitro. The results showed that Bru-34 attenuated the allergic airway inflammation in mice, with significant decreasing of the inflammatory cells and mediators in bronchoalveolar lavage fluids and attenuation of the histopathological alterations in the lung tissues. In addition, Bru-34 significantly inhibited the release of inflammatory cytokines in antigen induced rat basophilic leukemia -2H3 (RBL-2H3) cells. What’s more, Bru-34 significantly decreased the expression of spleen tyrosine kinase (Syk), p-Syk, cytoplasmic phospholipase A2 (cPLA2), p-cPLA2, nuclear factor-κB (NF-κB) and p-NF-κB both in allergic mice lung tissue and antigen induced RBL-2H3 cells. Furthermore, the collaborative effects of Bru-34 with inhibitors against Syk, cPLA2, and NF-κB, showed that Syk was an important target of Bru-34, and cPLA2 and NF-κB played important roles in the coordinated inflammatory response. In conclusion, Bru-34 could significantly modulate the allergic airway inflammation, and its potential mechanism was revealed at least partially via down-regulating of Syk-cPLA2 -NF-κB signaling.

Response of peripheral blood basophils in subjects with chronic spontaneous urticaria during treatment with omalizumab

Treatment of patients with asthma or food allergy with omalizumab results in several consistent changes in circulating basophils. The multiple basophil phenotypes observed in patients with chronic spontaneous urticaria (CSU) present some unique attributes that may not respond in a similar fashion to patients with asthma or food allergy. As part of a clinical study on the therapeutic outcomes of omalizumab treatment in CSU, the basophil compartment was examined for changes in characteristics predicted by prior studies. This study sought to examine the changes in basophil function and its relationship to auto-antibodies in serum during treatment with omalizumab. At multiple time points before and during omalizumab treatment of patients with CSU, basophil surface IgE and FcεRI expression, cellular spleen tyrosine kinase (SYK) expression, IgE-mediated histamine release (HR), and the presence of auto-antibodies in serum were determined. Three basophil phenotypes were enumerated in the clinical study and used to group results in this basophil study: subjects with (1) basopenia, (2) normal basophil numbers with normal IgE-mediated HR, and (3) normal basophil numbers with poor HR. Basopenia was highly associated with the presence of auto-antibodies to unoccupied FcεRI and basophil numbers did not change during treatment. Likewise, subjects who are basopenic showed no changes in SYK expression or HR during treatment. In basophils of subjects who are nonbasopenic, increases in SYK expression and HR showed the expected inverse relationship to starting SYK and HR levels. Treatment with omalizumab resulted in similar kinetics for decreases in surface FcεRI and IgE in all 3 groups. A unifying interpretation of the results revolves around the presence of auto-antibodies to FcεRI in CSU. If present, basopenia and an absence of changes in basophils during omalizumab treatment are observed. If auto-antibodies are absent, the changes in the basophil compartment are consistent with prior studies of asthma and food allergy. These group differences also are related to efficacy of the treatment for clinical outcomes, as found in the parent clinical study.

Precursor B-ALL Cell Lines Differentially Respond to SYK Inhibition by Entospletinib.

Background: Impaired B-cell receptor (BCR) function has been associated with the progress of several B-cell malignancies. The spleen tyrosine kinase (SYK) represents a potential therapeutic target in a subset of B-cell neoplasias. In precursor B-acute lymphoblastic leukemia (B-ALL), the pathogenic role and therapeutic potential of SYK is still controversially discussed. We evaluate the application of the SYK inhibitor entospletinib (Ento) in pre- and pro-B-ALL cell lines, characterizing the biologic and molecular effects. Methods: SYK expression was characterized in pre-B-ALL (NALM-6) and pro-B-ALL cell lines (SEM and RS4;11). The cell lines were exposed to different Ento concentrations and the cell biological response analyzed by proliferation, metabolic activity, apoptosis induction, cell-cycle distribution and morphology. BCR pathway gene expression and protein modulations were further characterized. Results: Ento significantly induced anti-proliferative and pro-apoptotic effects in NALM-6 and SEM, while barely affecting RS4;11. Targeted RNAseq revealed pronounced gene expression modulation only in NALM-6, while Western Blot analyses demonstrated that vital downstream effector proteins, such as pAKT, pERK, pGSK3β, p53 and BCL-6, were affected by Ento exposure in the inhibitor-sensitive cell lines. Conclusion: Different acting modes of Ento, independent of pre-BCR dependency, were characterized, unexpected in SEM. Accordingly, SYK classifies as a potential target structure in a subset of pro-B-ALLs.

RNA-Seq profiling of microdissected glomeruli identifies potential biomarkers for human IgA nephropathy.

Few studies have examined gene expression changes occurring in the glomeruli of IgA nephropathy (IgAN) using a sensitive transcriptomic profiling method such as RNA sequencing (RNA-Seq). We collected glomeruli from biopsy specimens from patients with IgAN with relatively preserved kidney function (estimated glomerular filtration rate ≥ 60 mL·min-1·1.73 m-2 and urine protein-to-creatinine ratio < 3 g/g) and from normal kidney cortexes by hand microdissection and performed RNA-Seq. Differentially expressed genes were identified, and gene ontology term annotation and pathway analysis were performed. Immunohistochemical labeling and primary mesangial cell cultures were performed to confirm the findings of RNA-Seq analysis. Fourteen patients with IgAN and ten controls were included in this study. Glomerulus-specific genes were highly abundant. Principal component analysis showed clear separation between the IgAN and control groups. There were 2,497 differentially expressed genes, of which 1,380 were upregulated and 1,117 were downregulated (false discovery rate < 0.01). The enriched gene ontology terms included motility/migration, protein/vesicle transport, and immune system, and kinase binding was the molecular function overrepresented in IgAN. B cell signaling, chemokine signal transduction, and Fcγ receptor-mediated phagocytosis were the canonical pathways overrepresented. In vitro experiments confirmed that spleen tyrosine kinase (SYK), reported as upregulated in the IgAN transcriptome, was also upregulated in glomeruli from an independent set of patients with IgAN and that treatment with patient-derived IgA1 increased the expression of SYK in mesangial cells. In conclusion, transcriptomic profiling of the IgAN glomerulus provides insights in the intraglomerular pathophysiology of IgAN before it reaches profound kidney dysfunction. SYK may have a pathogenetic role in IgAN.

Spleen tyrosine kinase expression and its correlation with necrosis and high-risk histopathologic features in retinoblastoma.

Spleen tyrosine kinase expression and its correlation with necrosis and high-risk histopathologic features in retinoblastoma.

Role of spleen tyrosine kinase in liver diseases.

Spleen tyrosine kinase (SYK) is a non-receptor tyrosine kinase expressed in most hematopoietic cells and non-hematopoietic cells and play a crucial role in both immune and non-immune biological responses. SYK mediate diverse cellular responses via an immune-receptor tyrosine-based activation motifs (ITAMs)-dependent signalling pathways, ITAMs-independent and ITAMs-semi-dependent signalling pathways. In liver, SYK expression has been observed in parenchymal (hepatocytes) and non-parenchymal cells (hepatic stellate cells and Kupffer cells), and found to be positively correlated with the disease severity. The implication of SYK pathway has been reported in different liver diseases including liver fibrosis, viral hepatitis, alcoholic liver disease, non-alcoholic steatohepatitis and hepatocellular carcinoma. Antagonism of SYK pathway using kinase inhibitors have shown to attenuate the progression of liver diseases thereby suggesting SYK as a highly promising therapeutic target. This review summarizes the current understanding of SYK and its therapeutic implication in liver diseases.

Preclinical efficacy for a novel tyrosine kinase inhibitor, ArQule 531 against acute myeloid leukemia

BackgroundAcute myeloid leukemia (AML) is the most common type of adult leukemia. Several studies have demonstrated that oncogenesis in AML is enhanced by kinase signaling pathways such as Src family kinases (SFK) including Src and Lyn, spleen tyrosine kinase (SYK), and bruton’s tyrosine kinase (BTK). Recently, the multi-kinase inhibitor ArQule 531 (ARQ 531) has demonstrated potent inhibition of SFK and BTK that translated to improved pre-clinical in vivo activity as compared with the irreversible BTK inhibitor ibrutinib in chronic lymphocytic leukemia (CLL) models. Given the superior activity of ARQ 531 in CLL, and recognition that this molecule has a broad kinase inhibition profile, we pursued its application in pre-clinical models of AML.MethodsThe potency of ARQ 531 was examined in vitro using FLT3 wild type and mutated (ITD) AML cell lines and primary samples. The modulation of pro-survival kinases following ARQ 531 treatment was determined using AML cell lines. The effect of SYK expression on ARQ 531 potency was evaluated using a SYK overexpressing cell line (Ba/F3 murine cells) constitutively expressing FLT3-ITD. Finally, the in vivo activity of ARQ 531 was evaluated using MOLM-13 disseminated xenograft model.ResultsOur data demonstrate that ARQ 531 treatment has anti-proliferative activity in vitro and impairs colony formation in AML cell lines and primary AML cells independent of the presence of a FLT3 ITD mutation. We demonstrate decreased phosphorylation of oncogenic kinases targeted by ARQ 531, including SFK (Tyr416), BTK, and fms-related tyrosine kinase 3 (FLT3), ultimately leading to changes in down-stream targets including SYK, STAT5a, and ERK1/2. Based upon in vitro drug synergy data, we examined ARQ 531 in the MOLM-13 AML xenograft model alone and in combination with venetoclax. Despite ARQ 531 having a less favorable pharmacokinetics profile in rodents, we demonstrate modest single agent in vivo activity and synergy with venetoclax.ConclusionsOur data support consideration of the application of ARQ 531 in combination trials for AML targeting higher drug concentrations in vivo.

Spleen tyrosine kinase inhibition is an effective treatment for established vasculitis in a pre-clinical model

The anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitides (AAV) are a group of life-threatening multi-system diseases characterized by necrotising inflammation of small blood vessels and crescentic glomerulonephritis. ANCA are thought to play a direct pathogenic role. Previous studies have shown that spleen tyrosine kinase (SYK) is phosphorylated during ANCA-induced neutrophil activation in vitro. However, the role of SYK in vivo is unknown. Here, we studied its role in the pathogenesis of experimental autoimmune vasculitis, a pre-clinical model of myeloperoxidase-ANCA-induced pauci-immune systemic vasculitis in the Wistar Kyoto rat. Up-regulation of SYK expression in inflamed renal and pulmonary tissue during early autoimmune vasculitis was confirmed by immunohistochemical and transcript analysis. R406, the active metabolite of fostamatinib, a small molecule kinase inhibitor with high selectivity for SYK, inhibited ANCA-induced pro-inflammatory responses in rat leucocytes in vitro. In an in vivo study, treatment with fostamatinib for 14 days after disease onset resulted in rapid resolution of urinary abnormalities, significantly improved renal and pulmonary pathology, and preserved renal function. Short-term exposure to fostamatinib did not significantly affect circulating myeloperoxidase-ANCA levels, suggesting inhibition of ANCA-induced inflammatory mechanisms in vivo. Finally, SYK expression was demonstrated within inflammatory glomerular lesions in ANCA-associated glomerulonephritis in patients, particularly within CD68+ve monocytes/macrophages. Thus, our data indicate that SYK inhibition warrants clinical investigation in the treatment of AAV.

Systematic Analysis of Spleen Tyrosine Kinase Expression and its Clinical Outcomes in Various Cancers.

Background:Spleen tyrosine kinase (SYK) is an important enzyme in the proliferation and differentiation of all hematopoietic tissues. Its role as a cancer driver is well documented in liquid tumors; however, cumulative evidence has suggested an opposite role in other tumor types.Objectives:To systematically assess the expression of SYK, its prognostic value and epigenetic status in different cancers using bioinformatics tools.Methods:In this bioinformatics study, Oncomine database and cBioPortal were used to study the SYK gene expression, Kaplan–Meier plotter to study its prognostic value and MethHC to assess the SYK gene methylation in various cancers.Results:From 542 unique analyses of the SYK gene, it was found to be overexpressed in bladder, breast and colon cancers but downregulated in leukemia, lymphoma and myeloma. Compared with normal tissues, breast and brain tumors showed an overexpression of the SYK gene, whereas lymphoma and leukemia had lower expression. The Kaplan–Meier survival analysis revealed that SYK expression in pancreatic, gastric, liver and lung patients were correlated with better overall survival. Using cBioPortal, prostate cancer was found to have the highest SYK gene mutation frequency, and the mean expression was highest in diffuse large B-cell lymphoma, acute myeloid leukemia and thymoma. Using the MethHC database, SYK promoter hypermethylation was found to be significantly higher in breast, renal, liver, lung, pancreatic, prostatic, skin and stomach cancers compared with the normal tissue (P < 0.005).Conclusion:The results of this study indicate the potential use of SYK as a diagnostic and therapeutic target for different type of cancers. However, further experimental data are required to validate these results before use of SYK in clinical settings.