scholarly journals ROCK Inhibition Drives Resolution of Acute Inflammation by Enhancing Neutrophil Apoptosis

Cells ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 964 ◽  
Author(s):  
Izabela Galvão ◽  
Rayssa M. Athayde ◽  
Denise A. Perez ◽  
Alesandra C. Reis ◽  
Luisa Rezende ◽  
...  
Keyword(s):  
Intracellular Signaling ◽  
Pleural Cavity ◽  
Inflammatory Diseases ◽  
Human Neutrophils ◽  
Neutrophil Accumulation ◽  
Resolution Of Inflammation ◽  
Induced Apoptosis ◽  
Rock Inhibition ◽  
Rock Activity

Uncontrolled inflammation leads to tissue damage and it is central for the development of chronic inflammatory diseases and autoimmunity. An acute inflammatory response is finely regulated by the action of anti-inflammatory and pro-resolutive mediators, culminating in the resolution of inflammation and restoration of homeostasis. There are few studies investigating intracellular signaling pathways associated with the resolution of inflammation. Here, we investigate the role of Rho-associated kinase (ROCK), a serine/threonine kinase, in a model of self-resolving neutrophilic inflammatory. We show that ROCK activity, evaluated by P-MYPT-1 kinetics, was higher during the peak of lipopolysaccharide-induced neutrophil influx in the pleural cavity of mice. ROCK inhibition by treatment with Y-27632 decreased the accumulation of neutrophils in the pleural cavity and was associated with an increase in apoptotic events and efferocytosis, as evaluated by an in vivo assay. In a model of gout, treatment with Y-27632 reduced neutrophil accumulation, IL-1β levels and hypernociception in the joint. These were associated with reduced MYPT and IκBα phosphorylation levels and increased apoptosis. Finally, inhibition of ROCK activity also induced apoptosis in human neutrophils and destabilized cytoskeleton, extending the observed effects to human cells. Taken together, these data show that inhibition of the ROCK pathway might represent a potential therapeutic target for neutrophilic inflammatory diseases.

scholarly journals Switching Off Key Signaling Survival Molecules to Switch On the Resolution of Inflammation

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Denise Alves Perez ◽  
Juliana Priscila Vago ◽  
Rayssa Maciel Athayde ◽  
Alesandra Corte Reis ◽  
Mauro Martins Teixeira ◽  
...  
Keyword(s):  
Intracellular Signaling ◽  
Physiological Response ◽  
Cytokine Production ◽  
Inflammatory Diseases ◽  
Signaling Molecules ◽  
Active Process ◽  
Resolution Of Inflammation ◽  
Chronic Inflammatory Diseases ◽  
Intracellular Signaling Molecules

Inflammation is a physiological response of the immune system to injury or infection but may become chronic. In general, inflammation is self-limiting and resolves by activating a termination program named resolution of inflammation. It has been argued that unresolved inflammation may be the basis of a variety of chronic inflammatory diseases. Resolution of inflammation is an active process that is fine-tuned by the production of proresolving mediators and the shutdown of intracellular signaling molecules associated with cytokine production and leukocyte survival. Apoptosis of leukocytes (especially granulocytes) is a key element in the resolution of inflammation and several signaling molecules are thought to be involved in this process. Here, we explore key signaling molecules and some mediators that are crucial regulators of leukocyte survivalin vivoand that may be targeted for therapeutic purposes in the context of chronic inflammatory diseases.

scholarly journals Prospects for use of peptides and their derivatives, structurally corresponding to the G protein-coupled receptors, in medicine

2015 ◽  
Vol 61 (1) ◽  
pp. 19-29 ◽  
Author(s):  
A.O. Shpakov ◽  
E.A. Shpakova
Keyword(s):  
G Protein ◽  
Intracellular Signaling ◽  
High Efficiency ◽  
Clinical Medicine ◽  
Inflammatory Diseases ◽  
G Protein Coupled Receptors ◽  
Signaling Cascades ◽  
G Protein Coupled

The regulation of signaling pathways involved in the control of many physiological functions is carried out via the heterotrimeric G protein-coupled receptors (GPCR). The search of effective and selective regulators of GPCR and intracellular signaling cascades coupled with them is one of the important problems of modern fundamental and clinical medicine. Recently data suggest that synthetic peptides and their derivatives, structurally corresponding to the intracellular and transmembrane regions of GPCR, can interact with high efficiency and selectivity with homologous receptors and influence, thus, the functional activity of intracellular signaling cascades and fundamental cellular processes controlled by them. GPCR-peptides are active in both in vitro and in vivo. They regulate hematopoiesis, angiogenesis and cell proliferation, inhibit tumor growth and metastasis, and prevent the inflammatory diseases and septic shock. These data show greatest prospects in the development of the new generations of drugs based on GPCR-derived peptides, capable of regulating the important functions of the organism.

Rapamycin sensitizes multiple myeloma cells to apoptosis induced by dexamethasone

Blood ◽  
2004 ◽  
Vol 103 (8) ◽  
pp. 3138-3147 ◽  
Author(s):  
Thomas Strömberg ◽  
Anna Dimberg ◽  
Anna Hammarberg ◽  
Kristina Carlson ◽  
Anders Österborg ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Lines ◽  
Intracellular Signaling ◽  
Kinase Inhibitor ◽  
Mammalian Target Of Rapamycin ◽  
G1 Arrest ◽  
Cyclin Dependent Kinase Inhibitor ◽  
Induced Apoptosis ◽  
Molecular Mode

Abstract Circumvention of chemoresistance in the B-cell neoplasm multiple myeloma (MM) might be achieved by targeting certain intracellular signaling pathways crucial for survival of the malignant clone. The use of the macrolide rapamycin, selectively inhibiting the phosphoprotein mammalian target of rapamycin (mTOR) downstream of, for example, insulin-like growth factor-I receptor (IGF-IR), possibly represents such a molecular mode of therapy. By using a panel of MM cell lines we showed that rapamycin induced G0/G1 arrest, an effect being associated with an increase of the cyclin-dependent kinase inhibitor p27 and a decrease of cyclins D2 and D3. Interestingly, in primary, mainly noncycling MM cells, rapamycin, at clinically achievable concentrations, induced apoptosis. More important, rapamycin sensitized both MM cell lines and primary MM cells to dexamethasone-induced apoptosis. This effect was associated with a decreased expression of cyclin D2 and survivin. The phosphorylation of the serine/threonine kinase p70S6K at Thr389 and Thr421/Ser424 was down-regulated by rapamycin and/or dexamethasone. Strikingly, the combinatorial treatment with rapamycin and dexamethasone suppressed the antiapoptotic effects of exogenously added IGF-I and interleukin 6 (IL-6) as well as their stimulation of p70S6K phosphorylation. The induction of apoptosis by rapamycin and dexamethasone despite the presence of survival factors was also demonstrated in primary MM cells, thus suggesting this drug combination to be active also in vivo. (Blood. 2004;103:3138-3147)

Interleukin-8 induces neutrophil accumulation but not protease secretion in the canine trachea

1992 ◽  
Vol 263 (6) ◽  
pp. L708-L713 ◽  
Author(s):  
P. G. Jorens ◽  
J. B. Richman-Eisenstat ◽  
B. P. Housset ◽  
P. D. Graf ◽  
I. F. Ueki ◽  
...  
Keyword(s):  
Interleukin 8 ◽  
Cathepsin G ◽  
Human Neutrophils ◽  
Secretory Cells ◽  
Neutrophil Accumulation ◽  
High Concentrations ◽  
Granule Secretion ◽  
Protease Secretion

The neutrophil enzyme elastase is a potent secretagogue of airway secretory cells, and elastase is present in high concentrations in sputum of patients with hypersecretion (e.g., cystic fibrosis, bronchiectasis). Interleukin-8 (IL-8), a recently discovered cytokine with potent neutrophil chemotactic properties in vitro, is also found in the sputum of these patients. We used an isolated tracheal segment in dogs in vivo to study the effect of IL-8 in causing neutrophil accumulation, elastase release, and secretion (by measuring lysozyme concentrations) in the luminal superfusate. IL-8 caused a potent time-dependent neutrophil accumulation at between 3 and 6 h. The effect was significant at 10(-9) and maximum at 10(-8) M. No increase in free elastase, cathepsin G, or lysozyme was detected in the superfusate. Thus, in contrast to previous studies showing that ragweed antigen causes the accumulation of neutrophil elastase which in turn causes lysozyme secretion, IL-8 causes neutrophil accumulation without granule secretion (or subsequent secretagogue activity). The findings were confirmed with dog and human neutrophils in vitro.

scholarly journals G-CSF maintains controlled neutrophil mobilization during acute inflammation by negatively regulating CXCR2 signaling

2016 ◽  
Vol 213 (10) ◽  
pp. 1999-2018 ◽  
Author(s):  
Besnik Bajrami ◽  
Haiyan Zhu ◽  
Hyun-Jeong Kwak ◽  
Subhanjan Mondal ◽  
Qingming Hou ◽  
...  
Keyword(s):  
Intracellular Signaling ◽  
Acute Inflammation ◽  
Early Stage ◽  
Pulmonary Inflammation ◽  
Lung Damage ◽  
Critical Event ◽  
Neutrophil Accumulation ◽  
Peripheral Blood Neutrophil ◽  
Lung Injury Model

Cytokine-induced neutrophil mobilization from the bone marrow to circulation is a critical event in acute inflammation, but how it is accurately controlled remains poorly understood. In this study, we report that CXCR2 ligands are responsible for rapid neutrophil mobilization during early-stage acute inflammation. Nevertheless, although serum CXCR2 ligand concentrations increased during inflammation, neutrophil mobilization slowed after an initial acute fast phase, suggesting a suppression of neutrophil response to CXCR2 ligands after the acute phase. We demonstrate that granulocyte colony-stimulating factor (G-CSF), usually considered a prototypical neutrophil-mobilizing cytokine, was expressed later in the acute inflammatory response and unexpectedly impeded CXCR2-induced neutrophil mobilization by negatively regulating CXCR2-mediated intracellular signaling. Blocking G-CSF in vivo paradoxically elevated peripheral blood neutrophil counts in mice injected intraperitoneally with Escherichia coli and sequestered large numbers of neutrophils in the lungs, leading to sterile pulmonary inflammation. In a lipopolysaccharide-induced acute lung injury model, the homeostatic imbalance caused by G-CSF blockade enhanced neutrophil accumulation, edema, and inflammation in the lungs and ultimately led to significant lung damage. Thus, physiologically produced G-CSF not only acts as a neutrophil mobilizer at the relatively late stage of acute inflammation, but also prevents exaggerated neutrophil mobilization and the associated inflammation-induced tissue damage during early-phase infection and inflammation.

scholarly journals POS0376 MONOMERIC C REACTIVE PROTEIN (mCRP) REGULATES INFLAMMATORY RESPONSES IN HUMAN AND MOUSE CHONDROCYTES

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 418.2-418
Author(s):  
C. Ruiz-Fernández ◽  
M. González-Rodríguez ◽  
V. Francisco ◽  
I. M. Rajab ◽  
R. Gómez Bahamonde ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Intracellular Signaling ◽  
Inflammatory Responses ◽  
Proteolytic Enzymes ◽  
Inflammatory Diseases ◽  
Osteoclast Differentiation ◽  
Human Neutrophils ◽  
C Reactive Protein ◽  
Reactive Protein

Background:C-reactive protein (CRP) is an acute-phase protein that is used as an established biomarker to follow disease severity and progression in a plethora of inflammatory diseases. However, its pathophysiologic mechanisms of action are still poorly defined and remain elusive. CRP, in its pentameric form, exhibits weak anti-inflammatory activity. On the contrary, the monomeric isoform (mCRP) exhibits potent pro-inflammatory properties in endothelial cells, leukocytes, and platelets. So far, no data exists regarding mCRP effects in human or mouse chondrocytesObjectives:This work aimed to verify the pathophysiological relevance of mCRP in the etiology and/or progression of osteoarthritis (OA)Methods:We investigated the effects of mCRP in cultured human primary chondrocytes and in the chondrogenic ATDC5 mouse cell line. We determined mRNA and protein levels of relevant factors involved in inflammatory responses and the modulation of nitric oxide synthase type II (NOS2), an early inflammatory molecular target.Results:We demonstrate, for the first time, that monomeric C reactive protein increases NOS2, COX2, MMP13, VCAM1, IL-6, IL-8, and LCN2 expression in human and murine chondrocytes. We also demonstrated that NF-kB is a key factor in the intracellular signaling of mCRP-driven induction of pro-inflammatory and catabolic mediators in chondrocytes.Conclusion:mCRP exerts a sustained catabolic effect on human and murine chondrocytes, increasing the expression of inflammatory mediators and proteolytic enzymes, which can promote extracellular matrix (ECM) breakdown in healthy and OA cartilage. In addition, our results implicate the NF-kB signaling pathway in catabolic effects mediated by mCRP.References:[1]Sproston NR, Ashworth JJ. Role of C-reactive protein at sites of inflammation and infection. Front Immunol. 2018;9(APR). doi:10.3389/fimmu.2018.00754[2]Francisco V, Pérez T, Pino J, et al. Biomechanics, obesity, and osteoarthritis. The role of adipokines: When the levee breaks. J Orthop Res. 2018;36(2):594-604. doi:10.1002/jor.23788[3]Kozijn AE, Tartjiono MT, Ravipati S, et al. Human C-reactive protein aggravates osteoarthritis development in mice on a high-fat diet. Osteoarthr Cartil. 2019;27(1):118-128. doi:10.1016/j.joca.2018.09.007[4]Rajab IM, Majerczyk D, Olson ME, et al. C-reactive protein in gallbladder diseases: diagnostic and therapeutic insights. Biophys Reports. 2020;6(2-3):49-67. doi:10.1007/s41048-020-00108-9[5]Wu Y, Potempa LA, El Kebir D, Filep JG. C-reactive protein and inflammation: conformational changes affect function. Biol Chem. 2015;396(11):1181-1197. doi:10.1515/hsz-2015-0149[6]Thiele JR, Zeller J, Bannasch H, Stark GB, Peter K, Eisenhardt SU. Targeting C-Reactive Protein in Inflammatory Disease by Preventing Conformational Changes. Mediators Inflamm. 2015;2015(372432):9. doi:10.1155/2015/372432[7]Khreiss T, József L, Hossain S, Chan JSD, Potempa LA, Filep JG. Loss of pentameric symmetry of C-reactive protein is associated with delayed apoptosis of human neutrophils. J Biol Chem. 2002;277(43):40775-40781. doi:10.1074/jbc.M205378200[8]Jia ZK, Li HY, Liang YL, Potempa LA, Ji SR, Wu Y. Monomeric C-reactive protein binds and neutralizes receptor activator of NF-κB ligand-induced osteoclast differentiation. Front Immunol. 2018;9(FEB). doi:10.3389/fimmu.2018.00234[9]Francisco V, Ruiz-Fernández C, Pino J, et al. Adipokines: Linking metabolic syndrome, the immune system, and arthritic diseases. Biochem Pharmacol. 2019;165:196-206. doi:10.1016/j.bcp.2019.03.030[10]Ullah N, Ma FR, Han J, et al. Monomeric C-reactive protein regulates fibronectin mediated monocyte adhesion. Mol Immunol. 2020;117:122-130. doi:10.1016/j.molimm.2019.10.013[11]Boras E, Slevin M, Alexander MY, et al. Monomeric C-reactive protein and Notch-3 co-operatively increase angiogenesis through PI3K signalling pathway. Cytokine. 2014;69(2):165-179. doi:10.1016/j.cyto.2014.05.027Disclosure of Interests:None declared

scholarly journals Resolvin T-series Reduce Neutrophil Extracellular Traps

Blood ◽  
2021 ◽  
Author(s):  
Nan Chiang ◽  
Miyuki Sakuma ◽  
Ana R Rodriguez ◽  
Bernd W. Spur ◽  
Daniel Irimia ◽  
...  
Keyword(s):  
Intracellular Signaling ◽  
Neutrophil Infiltration ◽  
Neutrophil Extracellular Traps ◽  
Human Neutrophils ◽  
Signaling Mechanism ◽  
Human Macrophages ◽  
Extracellular Traps ◽  
Mouse Macrophages ◽  
Net Uptake

The newly identified thirteen-series Resolvins (RvTs) regulate phagocyte functions and accelerate resolution of infectious inflammation. Since SARS-CoV-2 elicits uncontrolled inflammation involving neutrophil extracellular traps (NETs), we tested whether stereochemically defined RvTs regulate NET formation. Using microfluidic devices capturing NETs in PMA-stimulated human whole blood, the RvTs, RvT1-RvT4, 2.5 nM each, potently reduced NETs. With IL-1b-stimulated human neutrophils, each RvT dose- and time-dependently decreased NETosis giving ~50% potencies at 10 nM, compared to the known NETosis inhibitors [10 mM]. In mouse Staphylococcus aureus infection, RvTs [50 ng each] limited neutrophil infiltration, bacterial titers and NETs. Additionally, each RvT enhanced NET uptake by human macrophages; RvT2 was the most potent of the four RvTs, giving >50% increase in NET-phagocytosis. As part of the intracellular signaling mechanism, RvT2 increased cAMP and phospho-AMPK within human macrophages, and RvT2-stimulated NET uptake was abolished by PKA and AMPK inhibition. RvT2 also stimulated NET clearance by mouse macrophages in vivo. Together, these results provide evidence for novel pro-resolving functions of RvTs, namely reducing NETosis and enhancing macrophage NET clearance via a cAMP-PKA-AMPK axis. Thus, RvTs open opportunities for regulating NET-mediated collateral tissue damage during infection as well as monitoring NETs.

scholarly journals Mesenchymal Stem Cell-Conditioned Medium Induces Neutrophil Apoptosis Associated with Inhibition of the NF-κB Pathway in Endotoxin-Induced Acute Lung Injury

2019 ◽  
Vol 20 (9) ◽  
pp. 2208 ◽  
Author(s):  
Vincent Yi-Fong Su ◽  
Chi-Shiuan Lin ◽  
Shih-Chieh Hung ◽  
Kuang-Yao Yang
Keyword(s):  
Acute Lung Injury ◽  
Lung Injury ◽  
Conditioned Medium ◽  
Mouse Lung ◽  
Human Neutrophils ◽  
Neutrophil Apoptosis ◽  
Neutrophil Accumulation ◽  
Mobility Shift

The immunomodulatory effects of mesenchymal stem cells (MSCs) are established. However, the effects of MSCs on neutrophil survival in acute lung injury (ALI) remain unclear. The goal of this study was to investigate the effect of an MSC-conditioned medium (MSC-CM) on neutrophil apoptosis in endotoxin-induced ALI. In this study, an MSC-CM was delivered via tail vein injection to wild-type male C57BL/6 mice 4 h after an intratracheal injection of lipopolysaccharide (LPS). Twenty-four hours later, bronchoalveolar lavage fluid (BALF) and lung tissue were collected to perform histology, immunohistochemistry, apoptosis assay of neutrophil, enzyme-linked immunosorbent assays, and an electrophoretic mobility shift assay. Human neutrophils were also collected from patients with sepsis-induced acute respiratory distress syndrome (ARDS). Human neutrophils were treated in vitro with LPS, with or without subsequent MSC-CM co-treatment, and were then analyzed. Administration of the MSC-CM resulted in a significant attenuation of histopathological changes, the levels of interleukin-6 and macrophage inflammatory protein 2, and neutrophil accumulation in mouse lung tissues of LPS-induced ALI. Additionally, MSC-CM therapy enhanced the apoptosis of BALF neutrophils and reduced the expression of the anti-apoptotic molecules, Bcl-xL and Mcl-1, both in vivo and in vitro experiments. Furthermore, phosphorylated and total levels of nuclear factor (NF)-κB p65 were reduced in lung tissues from LPS + MSC-CM mice. Human MSC-CM also reduced the activity levels of NF-κB and matrix metalloproteinase-9 in the human neutrophils from ARDS patients. Thus, the results of this study suggest that the MSC-CM attenuated LPS-induced ALI by inducing neutrophil apoptosis, associated with inhibition of the NF-κB pathway.

scholarly journals Neutrophils preferentially phagocytose elongated particles—An opportunity for selective targeting in acute inflammatory diseases

2020 ◽  
Vol 6 (24) ◽  
pp. eaba1474 ◽  
Author(s):  
Hanieh Safari ◽  
William J. Kelley ◽  
Eiji Saito ◽  
Nicholas Kaczorowski ◽  
Lauren Carethers ◽  
...  
Keyword(s):  
Particle Shape ◽  
Ex Vivo ◽  
Inflammatory Diseases ◽  
Specific Interaction ◽  
Mononuclear Phagocytes ◽  
Human Neutrophils ◽  
Inflammatory Conditions ◽  
Polymeric Particles ◽  
Physical Particle

Polymeric particles have recently been used to modulate the behavior of immune cells in the treatment of various inflammatory conditions. However, there is little understanding of how physical particle parameters affect their specific interaction with different leukocyte subtypes. While particle shape is known to be a crucial factor in their phagocytosis by macrophages, where elongated particles are reported to experience reduced uptake, it remains unclear how shape influences phagocytosis by circulating phagocytes, including neutrophils that are the most abundant leukocyte in human blood. In this study, we investigated the phagocytosis of rod-shaped polymeric particles by human neutrophils relative to other leukocytes. In contrast to macrophages and other mononuclear phagocytes, neutrophils were found to exhibit increased internalization of rods in ex vivo and in vivo experimentation. This result suggests that alteration of particle shape can be used to selectively target neutrophils in inflammatory pathologies where these cells play a substantial role.

First-in-Class ROR1 Small Molecule Inhibitor (KAN0439834) Downregulated Wnt-Canonical and Non-Canonical Signaling Pathways and Induced Apoptosis of CLL Cells

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2912-2912 ◽  
Author(s):  
Mohammad Hojjat-Farsangi ◽  
Ali Moshfegh ◽  
Amir Hossein Daneshmanesh ◽  
Jan Vågberg ◽  
Byström Styrbjörn ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Signaling Pathways ◽  
Small Molecule ◽  
Intracellular Signaling ◽  
Leukemic Cells ◽  
Drug Candidate ◽  
Dependent Manner ◽  
Induced Apoptosis ◽  
Dose Dependent

Abstract Background: The receptor tyrosine kinase (RTK) ROR1 is detected during embryogenesis but downregulated in adult normal tissues. However, it is expressed in several solid tumors and hematological malignancies. Targeting ROR1 with specific siRNAs in chronic lymphocytic leukemia (CLL) induced apoptosis of the leukemic cells. Moreover, ROR1 specific monoclonal antibodies (mAbs) dephosphorylated ROR1 followed by apoptosis of the CLL cells. Furthermore, ROR1 tyrosine kinase inhibitors (ROR1-TKI) (small molecule inhibitors) have been shown to dephosphorylate ROR1, downregulate the activated PI3K/AKT/mTOR signaling pathway and induce specific apoptosis of CLL cells. Aim: In the present report we analysed the effects of a ROR1-TKI drug candidate (KAN0439834) on other intracellular signaling pathways involved in cell survival, differentiation and migration in addition to the PI3K/AKT/mTOR pathway in CLL cells. Methods: KAN0439834 ROR1-TKI was derived from a high-throughput screening (HTS) and a chemical synthesis program, including cellular assays for CLL specific cytotoxicity. The compound was also tested for ADME and in vivo pharmacokinetics characteristics. Peripheral blood mononuclear cells (PBMC) were derived from patients with CLL and normal healthy donors. Intracellular signaling molecules were analysed by Western blot (WB) after 30 min incubation of the cells with the ROR1-TKI (50-1000 nM). Apoptosis/necrosis was determined by the MTT cytotoxicity assay and Annexin V/PI staining in flowcytometry after 24 h of incubation. Results: CLL cells expressed ROR1 as determined by WB and flowcytometry. ROR1 was shown to be phosphorylated using a polyclonal anti-phospho-ROR1 (pROR1) antibody (WB). After 30 min of incubation with 50-1000 nM of KAN0439834, ROR1 was dephosphorylated in a dose-dependent manner. KAN0439834 also dephosphorylated LRP6, GSK3β, JNK, MAPK/ERK/p42,44, PKC, Src, and c-Jun and decreased the β-catenin concentration as well as deactivated BCL-2 and Bax proteins. KAN0439834 had no effect on Bruton tyrosine kinase (Btk) phosphorylation involved in B-cell receptor (BCR) signaling. Incubation of CLL cells with KAN0439834 (50-1000 nM) showed a dose dependent induction of apoptosis/necrosis of leukemic cells with more than 80% specific killing of CLL cells after 24 h and an IC50 value of 250 nM. Conclusions: Our data show that KAN0439834 downregulated the activity of various signaling pathways in CLL cells suggested to be connected with ROR1 signaling, including the Wnt-canonical associated molecule as LRP6, GSK3β and β-catenin as well as several Wnt non-canonical associated proteins as Src, MAPK/ERK p42,44, JNK, and PKC and inactivation of c-Jun that was followed by apoptosis of the CLL cells in a dose dependent manner. Further studies are ongoing to study the effects of the ROR1 specific TKIs on ROR1 downstream signaling as well as in preclinical in vivo animal models using human fresh tumors and cell lines to evaluate the anti-tumor effects. Available data suggest a specific ROR1-mediated cytotoxic effect of KAN0439834 on CLL cells, which represents a first-in-class of a novel CLL drug candidate targeting ROR1. Disclosures Moshfegh: Kancera AB: Employment. Vågberg:Kancera AB: Employment. Styrbjörn:Kancera AB: Employment. Schultz:Kancera AB: Employment. Olsson:Kancera AB: Employment. Löfberg:Kancera AB: Employment. Norström:Kancera AB: Employment. Norin:Kancera AB: Employment. Olin:Kancera AB: Employment, Equity Ownership. Österborg:Janssen Cilag: Research Funding.

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