scholarly journals Chronic lymphocytic leukemia cells receive RAF-dependent survival signals in response to CXCL12 that are sensitive to inhibition by sorafenib

Blood ◽  
2011 ◽  
Vol 117 (3) ◽  
pp. 882-889 ◽  
Author(s):  
Davorka Messmer ◽  
Jessie-F. Fecteau ◽  
Morgan O'Hayre ◽  
Ila S. Bharati ◽  
Tracy M. Handel ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Molecular Mechanisms ◽  
Lymphocytic Leukemia ◽  
Mitogen Activated Protein Kinase ◽  
Clinical Activity ◽  
Mitogen Activated Protein ◽  
Chemokine Cxcl12 ◽  
New Treatments

Abstract The chemokine CXCL12, via its receptor CXCR4, promotes increased survival of chronic lymphocytic leukemia (CLL) B cells that express high levels of ζ-chain–associated protein (ZAP-70), a receptor tyrosine kinase associated with aggressive disease. In this study, we investigated the underlying molecular mechanisms governing this effect. Although significant differences in the expression or turnover of CXCR4 were not observed between ZAP-70+ and ZAP-70− cell samples, CXCL12 induced greater intracellular Ca2+ flux and stronger and more prolonged phosphorylation of extracellular signal-regulated kinase (ERK) and mitogen-activated protein kinase/ERK kinase (MEK) in the ZAP-70+ CLL cells. The CXCL12-induced phosphorylation of ERK and MEK in ZAP-70+ CLL cells was blocked by sorafenib, a small molecule inhibitor of RAF. Furthermore, ZAP-70+ CLL cells were more sensitive than ZAP-70− CLL cells to the cytotoxic effects of sorafenib in vitro at concentrations that can readily be achieved in vivo. The data suggest that ZAP-70+ CLL cells may be more responsive to survival factors, like CXCL12, that are elaborated by the leukemia microenvironment, and this sensitivity could be exploited for the development of new treatments for patients with this disease. Moreover, sorafenib may have clinical activity for patients with CLL, particularly those with ZAP-70+ CLL.

scholarly journals Functional and clinical relevance of VLA-4 (CD49d/CD29) in ibrutinib-treated chronic lymphocytic leukemia

2018 ◽  
Vol 215 (2) ◽  
pp. 681-697 ◽  
Author(s):  
Erika Tissino ◽  
Dania Benedetti ◽  
Sarah E.M. Herman ◽  
Elisa ten Hacken ◽  
Inhye E. Ahn ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Progression Free Survival ◽  
Cell Receptor ◽  
Lymphocytic Leukemia ◽  
Clinical Activity ◽  
Independent Manner ◽  
Btk Inhibitor

The Bruton’s tyrosine kinase (BTK) inhibitor ibrutinib, which antagonizes B cell receptor (BCR) signals, demonstrates remarkable clinical activity in chronic lymphocytic leukemia (CLL). The lymphocytosis experienced by most patients under ibrutinib has previously been attributed to inhibition of BTK-dependent integrin and chemokine cues operating to retain the tumor cells in nodal compartments. Here, we show that the VLA-4 integrin, as expressed by CD49d-positive CLL, can be inside-out activated upon BCR triggering, thus reinforcing the adhesive capacities of CLL cells. In vitro and in vivo ibrutinib treatment, although reducing the constitutive VLA-4 activation and cell adhesion, can be overcome by exogenous BCR triggering in a BTK-independent manner involving PI3K. Clinically, in three independent ibrutinib-treated CLL cohorts, CD49d expression identifies cases with reduced lymphocytosis and inferior nodal response and behaves as independent predictor of shorter progression-free survival, suggesting the retention of CD49d-expressing CLL cells in tissue sites via activated VLA-4. Evaluation of CD49d expression should be incorporated in the characterization of CLL undergoing therapy with BCR inhibitors.

Lenalidomide Reduces Survival of Chronic Lymphocytic Leukemia Cells in Primary Co-Cultures by Altering the Myeloid Microenvironment

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3894-3894
Author(s):  
Angela Schulz ◽  
Claudia Dürr ◽  
Thorsten Zenz ◽  
Stephan Stilgenbauer ◽  
Peter Lichter ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Conflicts Of Interest ◽  
Drug Effects ◽  
Surface Expression ◽  
Lymphocytic Leukemia ◽  
Cell Surface Expression ◽  
Clinical Activity ◽  
Altered Expression

Abstract Abstract 3894 Chronic lymphocytic leukemia (CLL) cells are highly dependent on their microenvironment. External stimuli provided by bone marrow stromal cells or non-malignant leukocytes are required for their survival and proliferation. Interestingly, peripheral blood-derived monocytes differentiate in the presence of CLL cells to so-called Nurse-like cells (NLCs), which are round or fibroblast-shaped adherent cells that were shown to promote survival of CLL cells in vitro and to exist in lymph nodes of CLL patients. In search of new therapeutic options for patients with CLL, the immunomodulatory drug lenalidomide turned out to have significant clinical activity in CLL. Lenalidomide does not induce apoptosis in CLL cells directly, but is rather believed to act via the microenvironment. Several studies described that it alters cytokine levels and the activation status of the cells. Further, a CLL-specific T-cell defect was shown to be repaired by lenalidomide, which might represent a major activity of this drug in CLL. However, its mechanism of action seems to be complex and is not well understood. As monocytes as well as NLCs are very effective in maintaining survival of CLL cells, we aimed to investigate whether lenalidomide interferes with these supportive cell-cell interactions. To do this, we established primary co-cultures of monocytes and CLL cells in the presence or absence of lenalidomide and observed a significantly decreased viability of CLL cells after 14 days of treatment, suggesting an impact of this drug on the survival support of NLCs. Therefore, we analyzed the immunophenotype of NLCs by flow cytometry, as well as the secretion of cytokines in the co-cultures by ELISA and antibody-coupled bead arrays. Among the effects induced by lenalidomide, we observed reduced cell surface expression of the MHC II protein HLA-DR on NLCs as well as lower levels of the chemokine CCL2, but higher levels of IL-10 in the culture supernatant, indicating an altered inflammatory milieu in the co-cultures. The enhanced IL-10 levels resulted in an increase in STAT1 phosphorylation in CLL cells as measured by Western blot analysis. As a consequence, enhanced expression of the adhesion molecule ICAM-1 (CD54) and an altered expression of cytoskeletal genes (e.g. RHOC and CORO1B) were observed in CLL cells after lenalidomide treatment. Chemotaxis assays using transwell culture dishes and SDF1-α as chemoattractant revealed an impaired migratory potential of lenalidomide-treated CLL cells, which was not due to reduced expression of the SDF1-α receptor CXCR4. In summary, our data show that lenalidomide reduces the survival support of NLCs for CLL cells in vitro, suggesting that this drug effects the myeloid microenvironment in CLL in vivo. Furthermore, lenalidomide impairs the migratory potential of CLL cells which may affect circulation and homing of CLL cells in vivo. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Characterization of the TCL-1 transgenic mouse as a preclinical drug development tool for human chronic lymphocytic leukemia

Blood ◽  
2006 ◽  
Vol 108 (4) ◽  
pp. 1334-1338 ◽  
Author(s):  
Amy J. Johnson ◽  
David M. Lucas ◽  
Natarajan Muthusamy ◽  
Lisa L. Smith ◽  
Ryan B. Edwards ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Drug Development ◽  
Transgenic Mouse ◽  
Subsequent Development ◽  
Lymphocytic Leukemia ◽  
New Drugs ◽  
Clinical Activity ◽  
Suitable Animal Model

Abstract Drug development in human chronic lymphocytic leukemia (CLL) has been limited by lack of a suitable animal model to adequately assess pharmacologic properties relevant to clinical application. A recently described TCL-1 transgenic mouse develops a chronic B-cell CD5+ leukemia that might be useful for such studies. Following confirmation of the natural history of this leukemia in the transgenic mice, we demonstrated that the transformed murine lymphocytes express relevant therapeutic targets (Bcl-2, Mcl-1, AKT, PDK1, and DNMT1), wild-type p53 status, and in vitro sensitivity to therapeutic agents relevant to the treatment of human CLL. We then demonstrated the in vivo clinical activity of low-dose fludarabine in transgenic TCL-1 mice with active leukemia. These studies demonstrated both early reduction in blood-lymphocyte count and spleen size and prolongation of survival (P = .046) compared with control mice. Similar to human CLL, an emergence of resistance was noted with fludarabine treatment in vivo. Overall, these studies suggest that the TCL-1 transgenic leukemia mouse model has similar clinical and therapeutic response properties to human CLL and may therefore serve as a useful in vivo tool to screen new drugs for subsequent development in CLL.

scholarly journals Luteolin-3′-O-Phosphate Inhibits Lipopolysaccharide-Induced Inflammatory Responses by Regulating NF-κB/MAPK Cascade Signaling in RAW 264.7 Cells

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7393
Author(s):  
Jung-Hwan Kim ◽  
Tae-Jin Park ◽  
Jin-Soo Park ◽  
Min-Seon Kim ◽  
Won-Jae Chi ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Inflammatory Responses ◽  
Mitogen Activated Protein Kinase ◽  
Inflammatory Activity ◽  
Raw 264.7 Cells ◽  
Raw 264.7 ◽  
Mitogen Activated Protein ◽  
Anti Inflammatory

Luteolin (LT), present in most plants, has potent anti-inflammatory properties both in vitro and in vivo. Furthermore, some of its derivatives, such as luteolin-7-O-glucoside, also exhibit anti-inflammatory activity. However, the molecular mechanisms underlying luteolin-3′-O-phosphate (LTP)-mediated immune regulation are not fully understood. In this paper, we compared the anti-inflammatory properties of LT and LTP and analyzed their molecular mechanisms of action; we obtained LTP via the biorenovation of LT. We investigated the anti-inflammatory activities of LT and LTP in macrophage RAW 264.7 cells. We confirmed from previously reported literature that LT inhibits the production of nitric oxide and prostaglandin E2, as well as the expression of inducible NO synthetase and cyclooxygenase-2. In addition, expressions of inflammatory genes and mediators, such as tumor necrosis factor-α, interleukin-6, and interleukin-1β, were suppressed. LTP showed anti-inflammatory activity similar to LT, but better anti-inflammatory activity in all the experiments, while also inhibiting mitogen-activated protein kinase and nuclear factor-kappa B more effectively than LT. At a concentration of 10 μM, LTP showed differences of 2.1 to 44.5% in the activity compared to LT; it also showed higher anti-inflammatory activity. Our findings suggest that LTP has stronger anti-inflammatory activity than LT.

scholarly journals Role for the Ran Binding Protein, Mog1p, in Saccharomyces cerevisiae SLN1-SKN7 Signal Transduction

2004 ◽  
Vol 3 (6) ◽  
pp. 1544-1556 ◽  
Author(s):  
Jade Mei-Yeh Lu ◽  
Robert J. Deschenes ◽  
Jan S. Fassler
Keyword(s):  
Signal Transduction ◽  
Transcription Factor ◽  
Osmotic Stress ◽  
Kinase Activity ◽  
Mitogen Activated Protein Kinase ◽  
Osmotic Response ◽  
Mitogen Activated Protein ◽  
Kinase Pathway

ABSTRACT Yeast Sln1p is an osmotic stress sensor with histidine kinase activity. Modulation of Sln1 kinase activity in response to changes in the osmotic environment regulates the activity of the osmotic response mitogen-activated protein kinase pathway and the activity of the Skn7p transcription factor, both important for adaptation to changing osmotic stress conditions. Many aspects of Sln1 function, such as how kinase activity is regulated to allow a rapid response to the continually changing osmotic environment, are not understood. To gain insight into Sln1p function, we conducted a two-hybrid screen to identify interactors. Mog1p, a protein that interacts with the yeast Ran1 homolog, Gsp1p, was identified in this screen. The interaction with Mog1p was characterized in vitro, and its importance was assessed in vivo. mog1 mutants exhibit defects in SLN1-SKN7 signal transduction and mislocalization of the Skn7p transcription factor. The requirement for Mog1p in normal localization of Skn7p to the nucleus does not fully account for the mog1-related defects in SLN1-SKN7 signal transduction, raising the possibility that Mog1p may play a role in Skn7 binding and activation of osmotic response genes.

Evaluation of vecabrutinib as a model for non-covalent BTK/ITK inhibition for treatment of chronic lymphocytic leukemia

Blood ◽  
2021 ◽  
Author(s):  
Billy Michael Chelliah Jebaraj ◽  
Annika Müller ◽  
Rashmi Priyadharshini Dheenadayalan ◽  
Sascha Endres ◽  
Philipp M. Roessner ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Chronic Lymphocytic Leukemia ◽  
Inhibitory Effect ◽  
Lymphocytic Leukemia ◽  
Transfer Model ◽  
Treatment Benefit ◽  
Btk Inhibitors

Covalent Bruton tyrosine kinase (BTK) inhibitors such as ibrutinib have proven to be highly beneficial in the treatment of chronic lymphocytic leukemia (CLL). Interestingly, the off-target inhibition of IL-2-inducible T-cell kinase (ITK) by ibrutinib may also play a role in modulating the tumor microenvironment, potentially enhancing the treatment benefit. However, resistance to covalently binding BTK inhibitors can develop by a mutation in cysteine 481 of BTK (C481S), which prevents the irreversible binding of the drugs. In the present study we performed pre-clinical characterization of vecabrutinib, a next generation non-covalent BTK inhibitor, with ITK inhibitory properties similar to those of ibrutinib. Unlike ibrutinib and other covalent BTK inhibitors, vecabrutinib showed retention of the inhibitory effect on C481S BTK mutants in vitro, similar to that of wildtype BTK. In the murine Eµ-TCL1 adoptive transfer model, vecabrutinib reduced tumor burden and significantly improved survival. Vecabrutinib treatment led to a decrease in CD8+ effector and memory T-cell populations, while the naïve populations were increased. Of importance, vecabrutinib treatment significantly reduced frequency of regulatory CD4+ T-cells (Tregs) in vivo. Unlike ibrutinib, vecabrutinib treatment showed minimal adverse impact on activation and proliferation of isolated T-cells. Lastly, combination treatment of vecabrutinib with venetoclax was found to augment treatment efficacy, significantly improve survival and lead to favourable reprogramming of the microenvironment in the murine Eµ-TCL1 model. Thus, non-covalent BTK/ITK inhibitors such as vecabrutinib may be efficacious in C481S BTK mutant CLL, while preserving the T-cell immunomodulatory function of ibrutinib.

Chronic lymphocytic leukemia: revelations from the B-cell receptor

Blood ◽  
2004 ◽  
Vol 103 (12) ◽  
pp. 4389-4395 ◽  
Author(s):  
Freda K. Stevenson ◽  
Federico Caligaris-Cappio
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Cell Receptor ◽  
B Cell Receptor ◽  
Lymphocytic Leukemia ◽  
Cell Of Origin ◽  
Regulatory B Cell ◽  
V Genes

Abstract The finding that chronic lymphocytic leukemia (CLL) consists of 2 clinical subsets, distinguished by the incidence of somatic mutations in the immunoglobulin (Ig) variable region (V) genes, has clearly linked prognosis to biology. Antigen encounter by the cell of origin is indicated in both subsets by selective but distinct expression of V genes, with evidence for continuing stimulation after transformation. The key to distinctive tumor behavior likely relates to the differential ability of the B-cell receptor (BCR) to respond. Both subsets may be undergoing low-level signaling in vivo, although analysis of blood cells limits knowledge of critical events in the tissue microenvironment. Analysis of signal competence in vitro reveals that unmutated CLL generally continues to respond, whereas mutated CLL is anergized. Differential responsiveness may reflect the increased ability of post-germinal center B cells to be triggered by antigen, leading to long-term anergy. This could minimize cell division in mutated CLL and account for prognostic differences. Unifying features of CLL include low responsiveness, expression of CD25, and production of immunosuppressive cytokines. These properties are reminiscent of regulatory T cells and suggest that the cell of origin of CLL might be a regulatory B cell. Continuing regulatory activity, mediated via autoantigen, could suppress Ig production and lead to disease-associated hypogammaglobulinemia. (Blood. 2004;103:4389-4395)

scholarly journals Extracellular Signal-Regulated Kinases Phosphorylate Mitogen-Activated Protein Kinase Phosphatase 3/DUSP6 at Serines 159 and 197, Two Sites Critical for Its Proteasomal Degradation

2005 ◽  
Vol 25 (2) ◽  
pp. 854-864 ◽  
Author(s):  
Sandrine Marchetti ◽  
Clotilde Gimond ◽  
Jean-Claude Chambard ◽  
Thomas Touboul ◽  
Danièle Roux ◽  
...  
Keyword(s):  
Map Kinases ◽  
Fluorescent Protein ◽  
Proteasomal Degradation ◽  
Mitogen Activated Protein Kinase ◽  
Dependent Manner ◽  
Double Mutation ◽  
Extracellular Signal ◽  
Mitogen Activated Protein

ABSTRACT Mitogen-activated protein (MAP) kinase phosphatases (MKPs) are dual-specificity phosphatases that dephosphorylate phosphothreonine and phosphotyrosine residues within MAP kinases. Here, we describe a novel posttranslational mechanism for regulating MKP-3/Pyst1/DUSP6, a member of the MKP family that is highly specific for extracellular signal-regulated kinase 1 and 2 (ERK1/2) inactivation. Using a fibroblast model in which the expression of either MKP-3 or a more stable MKP-3-green fluorescent protein (GFP) chimera was induced by tetracycline, we found that serum induces the phosphorylation of MKP-3 and its subsequent degradation by the proteasome in a MEK1 and MEK2 (MEK1/2)-ERK1/2-dependent manner. In vitro phosphorylation assays using glutathione S-transferase (GST)-MKP-3 fusion proteins indicated that ERK2 could phosphorylate MKP-3 on serines 159 and 197. Tetracycline-inducible cell clones expressing either single or double serine mutants of MKP-3 or MKP-3-GFP confirmed that these two sites are targeted by the MEK1/2-ERK1/2 module in vivo. Double serine mutants of MKP-3 or MKP-3-GFP were more efficiently protected from degradation than single mutants or wild-type MKP-3, indicating that phosphorylation of either serine by ERK1/2 enhances proteasomal degradation of MKP-3. Hence, double mutation caused a threefold increase in the half-life of MKP-3. Finally, we show that the phosphorylation of MKP-3 has no effect on its catalytic activity. Thus, ERK1/2 exert a positive feedback loop on their own activity by promoting the degradation of MKP-3, one of their major inactivators in the cytosol, a situation opposite to that described for the nuclear phosphatase MKP-1.

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