The Novel Cancer Drug Seliciclib Engages the Mitochondrial Apoptosis Pathway Via the Mcl-1/Noxa Axis in CLL.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2983-2983
Author(s):  
Delfine Hallaert ◽  
Rene Spijker ◽  
Ingrid A.M. Derks ◽  
Margot Jak ◽  
Bart de Goeij ◽  
...  
Keyword(s):  
B Cell ◽  
Rna Polymerase Ii ◽  
Kinase Inhibitor ◽  
Lymphocytic Leukemia ◽  
Gene Profiling ◽  
Cancer Drug ◽  
Caspase 9 ◽  
Apoptotic Pathway ◽  
Apoptosis Pathway

Abstract Seliciclib (cyc202, R-roscovitine) is a novel cyclin dependent kinase inhibitor currently in pre-clinical testing. It indirectly inhibits RNA polymerase II and has been shown to be effective against B-cell malignancies by inducing apoptosis and Mcl-1 degradation. The aim of this study was to dissect the underlying apoptotic pathway(s) of seliciclib in chronic lymphocytic leukemia (B-CLL). Treatment of CLL cells with >10 μM seliciclib in vitro induced apoptosis within 24 hours, irrespective of IgVH mutation status (n=20). Gene profiling by means of RT-MLPA, did not reveal involvement of p53 as indicated by the absence of Puma upregulation. None of the >30 other apoptosis genes tested were induced; instead signals for certain labile mRNAs (Mcl-1, A1/Bfl-1, PI-9) were clearly decreased upon seliciclib. Detailed investigation of B cell lines overexpressing various anti-apoptotic proteins (Bcl-2, caspase-9-DN, Flip, FADD-DN), indicated that seliciclib activated the mitochondrial but not the death receptor pathway. Neither mitochondrial activation nor the rapid degradation of Mcl-1 protein could be prevented by caspase inhibition (zVAD) or overexpression of inactive caspase-9 (DN). This indicated that Mcl-1 decline is an upstream, caspase-independent event. Immuno-precipitation demonstrated that pro-survival Mcl-1 is engaged by pro-apoptotic Noxa and Bim. The specific contribution of Noxa was confirmed by RNAi, resulting in inhibition of apoptosis after seliciclib, but not after staurosporin, CD95- or BCR triggering. These findings demonstrate that seliciclib induces rapid, p53-independent apoptosis via Mcl-1 degradation and mitochondrial activation. The involvement of Noxa, which is highly expressed in CLL, suggests this BH3-only protein may be a novel therapeutic target.

Prognostic Significance of the Cell Cycle Inhibitor p27Kip1 in Chronic B-Cell Lymphocytic Leukemia

Blood ◽  
1998 ◽  
Vol 91 (12) ◽  
pp. 4694-4700 ◽  
Author(s):  
Radovan Vrhovac ◽  
Alain Delmer ◽  
Ruoping Tang ◽  
Jean-Pierre Marie ◽  
Robert Zittoun ◽  
...  
Keyword(s):  
Cell Cycle ◽  
B Cell ◽  
Doubling Time ◽  
Kinase Inhibitor ◽  
Prognostic Significance ◽  
Absolute Number ◽  
Lymphocytic Leukemia ◽  
Interleukin 4 ◽  
Resting Lymphocytes

Abstract B-cell chronic lymphocytic leukemia (B-CLL) is characterized by the accumulation of resting lymphocytes. The identification of p27kip1, a cyclin-dependent kinase inhibitor that contributes to cell cycle arrest and represents a link between extracellular signals and cell cycle, prompted us to study p27 protein in the lymphocytes from 88 patients with B-CLL and 32 patients with other chronic B-lymphoproliferative disorders. The expression of p27 protein was higher in B-CLL samples with variations among them. In B-CLL, p27 levels were independent of absolute number of circulating lymphocytes, but strongly correlated with both lymphocyte and total tumor mass (TTM) doubling time. High p27 expression was associated with a poorer overall prognosis. In vitro, there was an increased spontaneous survival of B-CLL cells expressing high p27 levels. Interleukin-4 (IL-4) upregulated p27 levels in B-CLL cells, while fludarabine decreased p27 levels. Thus, our results indicate that p27 may be a valuable kinetic marker in B-CLL by providing instantaneous estimation of the disease doubling time. In addition, these results suggest that there is a link between p27 expression and the ability of CLL cells to undergo apoptosis.

scholarly journals Emerging role of kinase-targeted strategies in chronic lymphocytic leukemia

Hematology ◽  
2012 ◽  
Vol 2012 (1) ◽  
pp. 88-96 ◽  
Author(s):  
Adrian Wiestner
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Absolute Lymphocyte Count ◽  
Cell Receptor ◽  
Lymphocytic Leukemia ◽  
Cell Trafficking

Abstract Chronic lymphocytic leukemia (CLL) is a malignancy of mature B cells that depend on host factors in the tissue microenvironment for survival and proliferation. In vitro, CLL cells rapidly undergo apoptosis unless microenvironmental factors are provided that support their survival. Signaling pathways activated in the microenvironment in vivo include the B-cell receptor (BCR) and NF-κB pathways. Thus, CLL is a disease “addicted to the host” and is dependent on pathways that promote normal B-cell development, expansion, and survival; this is particularly true in the case of the BCR signaling cascade. Small-molecule inhibitors of kinases that are essential for BCR signal transduction abrogate the stimulating effects of the microenvironment on CLL cells. The orally administered tyrosine kinase inhibitors fostamatinib and ibrutinib and the phosphatidylinositol 3-kinase inhibitor GS-1101 have induced impressive responses in relapsed and refractory CLL patients, mostly with moderate side effects. Reductions in lymphadenopathy and splenomegaly are seen within weeks and are frequently accompanied by a transient rise in absolute lymphocyte count that is asymptomatic and probably the result of changes in CLL cell trafficking. This review discusses the biologic basis for kinase inhibitors as targeted therapy of CLL and summarizes the exciting early clinical experience with these agents.

Prognostic Significance of the Cell Cycle Inhibitor p27Kip1 in Chronic B-Cell Lymphocytic Leukemia

Blood ◽  
1998 ◽  
Vol 91 (12) ◽  
pp. 4694-4700 ◽  
Author(s):  
Radovan Vrhovac ◽  
Alain Delmer ◽  
Ruoping Tang ◽  
Jean-Pierre Marie ◽  
Robert Zittoun ◽  
...  
Keyword(s):  
Cell Cycle ◽  
B Cell ◽  
Doubling Time ◽  
Kinase Inhibitor ◽  
Prognostic Significance ◽  
Absolute Number ◽  
Lymphocytic Leukemia ◽  
Interleukin 4 ◽  
Resting Lymphocytes

B-cell chronic lymphocytic leukemia (B-CLL) is characterized by the accumulation of resting lymphocytes. The identification of p27kip1, a cyclin-dependent kinase inhibitor that contributes to cell cycle arrest and represents a link between extracellular signals and cell cycle, prompted us to study p27 protein in the lymphocytes from 88 patients with B-CLL and 32 patients with other chronic B-lymphoproliferative disorders. The expression of p27 protein was higher in B-CLL samples with variations among them. In B-CLL, p27 levels were independent of absolute number of circulating lymphocytes, but strongly correlated with both lymphocyte and total tumor mass (TTM) doubling time. High p27 expression was associated with a poorer overall prognosis. In vitro, there was an increased spontaneous survival of B-CLL cells expressing high p27 levels. Interleukin-4 (IL-4) upregulated p27 levels in B-CLL cells, while fludarabine decreased p27 levels. Thus, our results indicate that p27 may be a valuable kinetic marker in B-CLL by providing instantaneous estimation of the disease doubling time. In addition, these results suggest that there is a link between p27 expression and the ability of CLL cells to undergo apoptosis.

scholarly journals Emerging role of kinase-targeted strategies in chronic lymphocytic leukemia

Blood ◽  
2012 ◽  
Vol 120 (24) ◽  
pp. 4684-4691 ◽  
Author(s):  
Adrian Wiestner
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Absolute Lymphocyte Count ◽  
Cell Receptor ◽  
Lymphocytic Leukemia ◽  
Cell Trafficking

AbstractChronic lymphocytic leukemia (CLL) is a malignancy of mature B cells that depend on host factors in the tissue microenvironment for survival and proliferation. In vitro, CLL cells rapidly undergo apoptosis unless microenvironmental factors are provided that support their survival. Signaling pathways activated in the microenvironment in vivo include the B-cell receptor (BCR) and NF-κB pathways. Thus, CLL is a disease “addicted to the host” and is dependent on pathways that promote normal B-cell development, expansion, and survival; this is particularly true in the case of the BCR signaling cascade. Small-molecule inhibitors of kinases that are essential for BCR signal transduction abrogate the stimulating effects of the microenvironment on CLL cells. The orally administered tyrosine kinase inhibitors fostamatinib and ibrutinib and the phosphatidylinositol 3-kinase inhibitor GS-1101 have induced impressive responses in relapsed and refractory CLL patients, mostly with moderate side effects. Reductions in lymphadenopathy and splenomegaly are seen within weeks and are frequently accompanied by a transient rise in absolute lymphocyte count that is asymptomatic and probably the result of changes in CLL cell trafficking. This review discusses the biologic basis for kinase inhibitors as targeted therapy of CLL and summarizes the exciting early clinical experience with these agents.

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

2021 ◽  
Vol 11 (3) ◽  
Author(s):  
Rong Chen ◽  
Jennifer Tsai ◽  
Philip A. Thompson ◽  
Yuling Chen ◽  
Ping Xiong ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Rna Polymerase Ii ◽  
Kinase Inhibitor ◽  
Leukemia Cell ◽  
Cell Receptor ◽  
B Cell Receptor ◽  
Lymphocytic Leukemia ◽  
Rapid Induction ◽  
Bcr Signaling

AbstractThe 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.

scholarly journals LUBAC Suppresses IL-21-Induced Apoptosis in CD40-Activated Murine B Cells and Promotes Germinal Center B Cell Survival and the T-Dependent Antibody Response

2021 ◽  
Vol 12 ◽  
Author(s):  
Jingwei Wang ◽  
Tianbao Li ◽  
Hong Zan ◽  
Carlos E. Rivera ◽  
Hui Yan ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Survival ◽  
Cell Activation ◽  
Caspase 8 ◽  
B Cell Activation ◽  
Caspase 9 ◽  
Apoptosis Pathway ◽  
B Cell Survival

B cell activation by Tfh cells, i.e., through CD154 engagement of CD40 and IL-21, and survival within GCs are crucial for the T-dependent Ab response. LUBAC, composed of HOIP, SHARPIN, and HOIL-1, catalyzes linear ubiquitination (Linear M1-Ub) to mediate NF-κB activation and cell survival induced by TNF receptor superfamily members, which include CD40. As shown in this study, B cells expressing the Sharpin null mutation cpdm (Sharpincpdm) could undergo proliferation, CSR, and SHM in response to immunization by a T-dependent Ag, but were defective in survival within GCs, enrichment of a mutation enhancing the BCR affinity, and production of specific Abs. Sharpincpdm B cells stimulated in vitro with CD154 displayed normal proliferation and differentiation, marginally impaired NF-κB activation and survival, but markedly exacerbated death triggered by IL-21. While activating the mitochondria-dependent apoptosis pathway in both Sharpin+/+ and Sharpincpdm B cells, IL-21 induced Sharpincpdm B cells to undergo sustained activation of caspase 9 and caspase 8 of the mitochondria-dependent and independent pathway, respectively, and ultimately caspase 3 in effecting apoptosis. These were associated with loss of the caspase 8 inhibitor cFLIP and reduction in cFLIP Linear M1-Ub, which interferes with cFLIP poly-ubiquitination at Lys48 and degradation. Finally, the viability of Sharpincpdm B cells was rescued by caspase inhibitors but virtually abrogated – together with Linear M1-Ub and cFLIP levels – by a small molecule HOIP inhibitor. Thus, LUBAC controls the cFLIP expression and inhibits the effects of caspase 8 and IL-21-activated caspase 9, thereby suppressing apoptosis of CD40 and IL-21-activated B cells and promoting GC B cell survival.

scholarly journals Acalabrutinib: A Selective Bruton Tyrosine Kinase Inhibitor for the Treatment of B-Cell Malignancies

2021 ◽  
Vol 11 ◽  
Author(s):  
Hussein A. Abbas ◽  
William G. Wierda
Keyword(s):  
Adverse Events ◽  
Tyrosine Kinase ◽  
B Cell ◽  
Kinase Inhibitor ◽  
Progression Free Survival ◽  
Lymphocytic Leukemia ◽  
B Cell Malignancies ◽  
Bruton Tyrosine Kinase ◽  
Btk Inhibitor

Bruton tyrosine kinase (BTK) is a validated target for treatment of B-cell malignancies, and oral inhibitors of BTK have emerged as a standard of care for these diseases. Acalabrutinib is a second generation, highly selective, potent, covalent BTK inhibitor that exhibits minimal off-target activity in in vitro assays, providing the potential to improve tolerability over the first-in-class BTK inhibitor, ibrutinib. Acalabrutinib was approved for the treatment of relapsed/refractory mantle cell lymphoma (MCL) and chronic lymphocytic leukemia (CLL) in the US in 2017 and 2019, respectively. Acalabrutinib is also undergoing trials for other B-cell malignancies, both as monotherapy and in combinations. In this review, we discuss results from clinical trials evaluating the efficacy and safety of acalabrutinib in patients with CLL, MCL, and Waldenstrom’s macroglobulinemia. Recent phase 3 data showed that acalabrutinib improved progression-free survival (PFS) compared with rituximab plus idelalisib or rituximab plus bendamustine in patients with relapsed/refractory CLL, and acalabrutinib with or without obinutuzumab improved PFS compared with chlorambucil plus obinutuzumab in patients with treatment-naïve CLL. Overall, acalabrutinib had a tolerable safety profile, with most adverse events being grade 1/2 severity (most commonly headache and diarrhea) and a low rate of discontinuation due to adverse events.

109. TROPHOBLAST DEPORTATION IS DEPENDENT UPON CASPASES 3, 8 AND ROCK

2009 ◽  
Vol 21 (9) ◽  
pp. 28
Author(s):  
K. J. Askelund ◽  
P. Stone ◽  
L. W. Chamley
Keyword(s):  
Caspase 3 ◽  
First Trimester ◽  
Normal Pregnancy ◽  
Maternal Blood ◽  
Caspase 8 ◽  
Caspase 9 ◽  
Apoptotic Pathway ◽  
Apoptosis Pathway ◽  
Villous Trophoblast

Background: Trophoblast deportation is the process whereby multinucleated fragments of the syncytiotrophoblast are shed from the placenta into the maternal blood. It is estimated that 150,000 are shed from the placenta and deported daily in normal pregnancy and that more are shed during preeclampsia1. In normal pregnancy deported trophoblasts are thought to die by apoptosis, which is also increased in villous trophoblast in preeclampsia2. However, experimental confirmation that apoptosis leads to trophoblast shedding is required and it is not clear which components of the apoptotic pathway are involved in trophoblast shedding. Objectives: To determine the effect of inhibiting caspase 3 (executioner), caspases 8 and 9 (initiators), and Rho-associated kinase (ROCK; bleb formation) on the number of trophoblasts shed from first trimester human placentae. Methods : Using an in vitro placental explant model of trophoblast deportation, first trimester placentae were cultured for 72 hours in media containing specific inhibitors of ROCK, caspases 3, 8 or 9. Trophoblasts shed from quintuple explants/inhibitor from five placentae were depleted of contaminating leucocytes and erythrocytes, labelled with trypan blue and the sizes and numbers of shed trophoblasts quantified using a Nexcelom automated counter. Results: The number of trophoblasts that were shed from the explants was significantly increased (p=0.04) when caspase 3 (2.4 fold) and caspase 8 (2.7 fold) were inhibited. There was no significant change following caspase 9 inhibition. The number of shed trophoblasts was significantly decreased when ROCK was inhibited. None of the inhibitors significantly altered the size of the shed trophoblasts. Conclusion: Our data suggest that the apoptosis pathway is involved in trophoblast shedding in vitro from first trimester placentae. That caspase 8 but not caspase 9 affected shedding suggests trophoblasts from normal placentae are induced to die via the extrinsic apoptosis pathway. Aberrant regulation of the apoptosis pathway may contribute to pregnancy pathology.

scholarly journals Deoxynivalenol Induces Caspase-8-Mediated Apoptosis through the Mitochondrial Pathway in Hippocampal Nerve Cells of Piglet

Toxins ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 73
Author(s):  
Li Cao ◽  
Yunjing Jiang ◽  
Lei Zhu ◽  
Wei Xu ◽  
Xiaoyan Chu ◽  
...  
Keyword(s):  
B Cell ◽  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
Nerve Cells ◽  
Caspase 8 ◽  
Trichothecene Mycotoxin ◽  
Apoptotic Pathway ◽  
Apoptosis Pathway ◽  
Mitochondrial Apoptosis Pathway

Deoxynivalenol (DON) is a common trichothecene mycotoxin found worldwide. DON has broad toxicity towards animals and humans. However, the mechanism of DON-induced neurotoxicity in vitro has not been fully understood. This study investigated the hypothesis that DON toxicity in neurons occurs via the mitochondrial apoptotic pathway. Using piglet hippocampal nerve cells (PHNCs), we evaluated the effects of different concentrations of DON on typical indicators of apoptosis. The obtained results demonstrated that DON treatment inhibited PHNC proliferation and led to morphological, biochemical, and transcriptional changes consistent with apoptosis, including decreased mitochondrial membrane potential, mitochondrial release of cytochrome C (CYCS) and apoptosis inducing factor (AIF), and increased abundance of active cleaved-caspase-9 and cleaved-caspase-3. Increasing concentrations of DON led to decreased B-cell lymphoma-2 (Bcl-2) expression and increased expression of BCL2-associated X (Bax) and B-cell lymphoma-2 homology 3 interacting domain death agonist (Bid), which in turn increased transcriptional activity of the transcription factors AIF and P53 (a tumor suppressor gene, promotes apoptosis). The addition of a caspase-8 inhibitor abrogated these effects. These results reveal that DON induces apoptosis in PHNCs via the mitochondrial apoptosis pathway, and caspase-8 is shown to play an important role during apoptosis regulation.

Aberrant Regulation of pVHL Levels by Microrna May Explain Autocrine Secretion of VEGF in CLL B Cells.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1064-1064
Author(s):  
Asish K Ghosh ◽  
Tait Shanafelt ◽  
George A Calin ◽  
Carlo M. Croce ◽  
Linda Wellik ◽  
...  
Keyword(s):  
B Cells ◽  
Western Blot ◽  
B Cell ◽  
Rna Polymerase Ii ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Lymphocytic Leukemia ◽  
Apoptosis Resistance ◽  
Downstream Target

Abstract Background: B-Chronic Lymphocytic Leukemia (CLL) is predominantly characterized as a clonal B-cell disorder where a minor fraction of CLL B cells proliferate, but the majority of these cells are non-cycling. Importantly, CLL B cells also exhibit apoptosis resistance that results from a complex set of redundant mechanisms. This latter feature presents a significant problem in relation to disease progression and developing effective therapies in CLL. Previously, we and others have reported that leukemic CLL cells spontaneously secrete pro-angiogenic vascular endothelial growth factor (VEGF) that can significantly enhance CLL leukemic B cell apoptosis resistance via unknown mechanisms. In addition, the molecular mechanism of the constitutive upregulation of VEGF in CLL B cells is unknown. Methods and Results: Here, we report that CLL B cells express a high level of HIF-1α protein under normoxic conditions as compared to that of normal B cells in Western blot analysis using a specific antibody. Accumulation of HIF-1α in CLL B cells resulted in upregulation of its downstream target VEGF. To comprehend this abnormal overexpression of HIF-1α, we have examined the status of the von Hippel-Lindau gene product (pVHL) that is responsible for HIF-1α degradation by Western blot analysis and found it to be either absent or notably low level in CLL B cells as compared to that of normal B cells. Furthermore, we have shown by in vitro reporter gene assays that miR-92a, a microRNA known to be overexpressed in CLL B cells, can target the VHL 3′-untranslated region (UTR) and is likely a reason for the depressed levels of pVHL in CLL B cells. To validate our hypothesis, we transiently transfected the human embryonic kidney cell line (293T) with miR-92a and observed a dose-dependent repression of pVHL level. Post-transcriptional regulation of the VHL gene was further confirmed when we observed a subtle but definite increase of the pVHL levels monitored by immunoblot following nucleofection of the antisense oligo targeted to miR-92a into primary CLL B cells. To examine whether HIF-1α is functionally active in CLL B cells, we performed co-immunoprecipitation experiments and found that HIF-1α forms an active complex by physical association with the transcriptional co-activator p300 and phospho-STAT3 in CLL B cells. The latter molecule is known to be constitutively expressed in CLL B cells but its function has been unknown. Subsequently, we have found via chromatin immunoprecipitation analyses in CLL B cells that HIF-1α and STAT3 are bound to the VEGF promoter and also recruit RNA polymerase II, further substantiating that this complex likely functions in the activation of VEGF transcription. Summary: Overall, our data show that CLL B cells express constitutively elevated HIF-1α levels in normoxia due, at least in part, to miR-92a regulated diminished pVHL expression. This is a unique previously undescribed mechanism for enhanced HIF-1α levels in human malignancy. We believe that Increased VEGF expression is associated with the combined effects of HIF-1α, p300 and constitutively active STAT3 as a functional complex and is an explanation for the VEGF-based autocrine pathway found in CLL B cells. These findings now provide additional strategy points for interrupting the VEGF autocrine pathway in CLL B cells.

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