scholarly journals TNFR2 is required for RIP1-dependent cell death in human leukemia

2020 ◽  
Vol 4 (19) ◽  
pp. 4823-4833
Author(s):  
Júlia Aguadé-Gorgorió ◽  
Scott McComb ◽  
Cornelia Eckert ◽  
Anna Guinot ◽  
Blerim Marovca ◽  
...  
Keyword(s):  
Cell Death ◽  
Messenger Rna ◽  
Molecular Mechanisms ◽  
Apoptotic Cell ◽  
Lymphoblastic Leukemia ◽  
Tumor Necrosis Factor Receptor ◽  
Therapeutic Interventions ◽  
Human Leukemia ◽  
Dismal Prognosis ◽  
Dependent Cell

Abstract Despite major advances in the treatment of patients with acute lymphoblastic leukemia in the last decades, refractory and/or relapsed disease remains a clinical challenge, and relapsed leukemia patients have an exceedingly dismal prognosis. Dysregulation of apoptotic cell death pathways is a leading cause of drug resistance; thus, alternative cell death mechanisms, such as necroptosis, represent an appealing target for the treatment of high-risk malignancies. We and other investigators have shown that activation of receptor interacting protein kinase 1 (RIP1)–dependent apoptosis and necroptosis by second mitochondria derived activator of caspase mimetics (SMs) is an attractive antileukemic strategy not currently exploited by standard chemotherapy. However, the underlying molecular mechanisms that determine sensitivity to SMs have remained elusive. We show that tumor necrosis factor receptor 2 (TNFR2) messenger RNA expression correlates with sensitivity to SMs in primary human leukemia. Functional genetic experiments using clustered regularly interspaced short palindromic repeats/Cas9 demonstrate that TNFR2 and TNFR1, but not the ligand TNF-α, are essential for the response to SMs, revealing a ligand-independent interplay between TNFR1 and TNFR2 in the induction of RIP1-dependent cell death. Further potential TNFR ligands, such as lymphotoxins, were not required for SM sensitivity. Instead, TNFR2 promotes the formation of a RIP1/TNFR1-containing death signaling complex that induces RIP1 phosphorylation and RIP1-dependent apoptosis and necroptosis. Our data reveal an alternative paradigm for TNFR2 function in cell death signaling and provide a rationale to develop strategies for the identification of leukemias with vulnerability to RIP1-dependent cell death for tailored therapeutic interventions.

scholarly journals Combined Inhibition of CXCR4 Signaling and System xc- Transporter Activity Induces Synthetic Lethality in T-ALL Cells By Suppressing Gsh and Inducing Ferroptosis

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 37-37
Author(s):  
Jun Xia ◽  
Stephanie Sun ◽  
Matthew RM Jotte ◽  
Geoffrey L Uy ◽  
Ella Sorani ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Death ◽  
Oxidative Phosphorylation ◽  
Molecular Mechanisms ◽  
Synthetic Lethality ◽  
Reduced Glutathione ◽  
Apoptotic Cell ◽  
Lymphoblastic Leukemia ◽  
Cxcr4 Signaling ◽  
The Media

T cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy that accounts for 10-15% of pediatric and 25% of adult ALL cases. Prior studies have established that most cases pf T-ALL are addicted to CXCR4 signaling. Indeed, strong preclinical data demonstrating therapeutic activity of BL-8040, a potent CXCR4 antagonist, have led to a clinical trial of BL-8040 in combination with nelarabine for patients with relapsed/refractory T-ALL (NCT02763384). However, the molecular mechanisms by which CXCR4 blockade induces T-ALL cell death are unknown. Using a human T-ALL xenotransplantation model, we previously reported that treatment with BL-8040 killed T-ALL cells through a non-apoptotic mechanism. Transcriptome sequencing revealed that BL-8040 induced alterations in genes involved in oxidative phosphorylation and carbohydrate metabolism. Indeed, seahorse experiments show that BL-8040 markedly reduced both oxidative phosphorylation and glycolysis. However, metabolic tracing studies using 13C-labeled glucose show that BL-8040 treatment does not have a major effect on the contribution of glucose to either glycolysis or the citric acid cycle. Instead, the major alteration observed is the reduced entry of glucose into the pentose phosphate pathway (PPP). A major function of the PPP pathway is to generate NADPH, which regulates reactive oxygen species (ROS) by producing reduced glutathione (GSH). Indeed, BL-8040 treatment resulted in a significant decrease in the ratio of reduced glutathione to oxidized glutathione. Together, these data suggest that BL-8040 induces oxidative stress by inhibiting GSH production. One mechanism utilized by cancer cells to regulate GSH levels and oxidative stress is the system xc- amino acid antiporter that mediates the exchange of extracellular L-cystine and intracellular l-glutamate across the plasma membrane, resulting in the production of GSH and oxidative protection. We measured L-cystine levels in the media of T-ALL cells cultured for 24 hours with or without BL-8040. A significant decrease in L-cystine in the media was observed. These data, along with increased expression of the xc- transporter (SLC7A11), suggested that increased system xc- activity was compensating for the loss of GSH induced by BL-8040. To test this possibility, we cultured T-ALL cells in L-cystine deficient media. Loss of L-cystine in the media resulted in a modest decrease in T-ALL cell viability that was markedly increased, in a synergistic fashion, upon treatment with BL-8040. Interestingly, caspase 3 was not activated, suggesting that, similar to in vivo results, BL-8040 induces a non-apoptotic cell death. This observation, coupled with the reduction in GSH, suggested the hypothesis that BL-8040 induces ferroptosis. Consistent with the hypothesis, treatment of T-ALL cells with ACXT-3102, a novel system xc- inhibitor, significantly enhanced BL-8040 killing of T-ALL cells in vitro. Collectively, these data suggest that T-ALL cells are sensitive to perturbations of the glutathione axis. Combined inhibition of CXCR4 signaling and system xc- activity exploits this vulnerability and presents a promising new therapeutic approach for T-ALL. Disclosures Uy: Astellas Pharma: Honoraria; Jazz Pharmaceuticals: Consultancy; Genentech: Consultancy; Agios: Consultancy; Pfizer: Consultancy; Daiichi Sankyo: Consultancy. Sorani:BiolineRx Ltd: Current Employment. Vainstein:BiolineRx Ltd: Current Employment. Davish:BiolineRx Ltd: Current Employment. Hawkins:Accuronix Therapeutics: Membership on an entity's Board of Directors or advisory committees.

scholarly journals Programmed Non-Apoptotic Cell Death in Hereditary Retinal Degeneration: Crosstalk between cGMP-Dependent Pathways and PARthanatos?

2021 ◽  
Vol 22 (19) ◽  
pp. 10567
Author(s):  
Jie Yan ◽  
Yiyi Chen ◽  
Yu Zhu ◽  
François Paquet-Durand
Keyword(s):  
Cell Death ◽  
Retinal Degeneration ◽  
Apoptotic Cell ◽  
Gene Mutations ◽  
Therapeutic Interventions ◽  
Cellular Mechanisms ◽  
Cgmp Signaling ◽  
Dependent Cell ◽  
A Cell ◽  
Hereditary Retinal Degeneration

Programmed cell death (PCD) is a highly regulated process that results in the orderly destruction of a cell. Many different forms of PCD may be distinguished, including apoptosis, PARthanatos, and cGMP-dependent cell death. Misregulation of PCD mechanisms may be the underlying cause of neurodegenerative diseases of the retina, including hereditary retinal degeneration (RD). RD relates to a group of diseases that affect photoreceptors and that are triggered by gene mutations that are often well known nowadays. Nevertheless, the cellular mechanisms of PCD triggered by disease-causing mutations are still poorly understood, and RD is mostly still untreatable. While investigations into the neurodegenerative mechanisms of RD have focused on apoptosis in the past two decades, recent evidence suggests a predominance of non-apoptotic processes as causative mechanisms. Research into these mechanisms carries the hope that the knowledge created can eventually be used to design targeted treatments to prevent photoreceptor loss. Hence, in this review, we summarize studies on PCD in RD, including on apoptosis, PARthanatos, and cGMP-dependent cell death. Then, we focus on a possible interplay between these mechanisms, covering cGMP-signaling targets, overactivation of poly(ADP-ribose)polymerase (PARP), energy depletion, Ca2+-permeable channels, and Ca2+-dependent proteases. Finally, an outlook is given into how specific features of cGMP-signaling and PARthanatos may be targeted by therapeutic interventions.

scholarly journals MEK1 Inhibitor Selumetinib Sensitizes Precursor B-Cell Acute Lymphoblastic Leukemia Cells (B-ALL) to Dexamethasone through Modulation of mTOR Activity and Stimulation of Autophagy

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 4917-4917
Author(s):  
Anna Polak ◽  
Przemyslaw Kiliszek ◽  
Tomasz Sewastianik ◽  
Maciej Szydlowski ◽  
Ewa Jablonska ◽  
...  
Keyword(s):  
Cell Death ◽  
Acute Lymphoblastic Leukemia ◽  
B Cell ◽  
Molecular Mechanisms ◽  
Apoptotic Cell ◽  
Lymphoblastic Leukemia ◽  
Apoptotic Cell Death ◽  
Leukemia Cells ◽  
Erk Pathway ◽  
Cell Acute Lymphoblastic Leukemia

Abstract Glucocorticoids (GC) have been used for decades in the treatment of B-cell acute lymphoblastic leukemia (B-ALL) in children and adults. Induction of apoptosis is thought to be the principal effector mechanism of GC's action, but recent studies highlight the role of autophagy upstream of apoptotic cell death (Laane et al 2009). Resistance to GCs is a major adverse prognostic factor, however the molecular mechanisms leading to GC resistance are not completely understood. Herein, we sought to elucidate the molecular mechanisms driving GC-resistance in precursor B-cell acute lymphoblastic leukemia cells and in vitro characterize the therapeutic potential of targeted intervention in these mechanisms. To identify molecular mechanisms involved in GC resistance, we performed gene set enrichment analysis of gene expression profiles GC-sensitive and -resistant B-ALL blasts using publicly available datasets and GenePattern program. Resistant cells exhibited significantly higher expression of MAPK/ERK pathway components (p<.002, FDR=0.13). To validate these findings, we assessed DEX sensitivity in ALL cells with high (SEMK2) or undetectable (RS4;11) activity of MAPK/ERK pathway. SEMK2 cells were resistant to DEX, whereas RS4;11 were highly sensitive to this drug. In GC-resistant cell line SEMK2, inhibition of MEK1 kinase with SEL completely abrogated ERK and p90RSK phosphorylation and increased sensitivity to GC by 1.8-2.6-fold. Similar pattern was observed in primary ALL blasts from 19 of 23 tested patients. Overexpression of a constitutively active MEK mutant in GC-sensitive cells (RS4;11) reversed sensitivity of these cells to DEX. Since GC in leukemic cells induce autophagic cell death, we assessed LC3 processing, MDC staining (a dye of autophagolysosomes) and GFP-LC3 relocalization in cells incubated with either DEX, SEL or combination of drugs. Either drug alone caused only marginal change in the level of these markers, but their combination markedly increased autophagic flux. Since mTORC1 is the critical regulator of autophagy, we assessed the activity of mTORC1 following DEX/SEL co-treatment and found that the combination resulted in a marked decrease of p4E-BP1, an mTORC1 substrate. Finally, to assess whether induction of autophagy is required for the observed synergy between SEL and DEX we used an shRNA approach to silence beclin-1 (BCN1), a gene required for autophagosome formation, and assessed cellular responses to DEX/SEL co-treatment. In control cells transduced with non-targeting shRNA, SEL sensitized cells to DEX, but in BCN1-deficient cells, the synergy of DEX and SEL was markedly decreased. Taken together, we show that MEK1 inhibitor selumetinib enhances DEX toxicity in GC-resistant B-ALL cells. The underlying mechanism of this interaction involves inhibition of mTORC1 signaling pathway and induction of autophagy that leads to apoptotic cell death. Disclosures No relevant conflicts of interest to declare.

Melatonin enhances hyperthermia-induced apoptotic cell death in human leukemia cells

2016 ◽  
Vol 61 (3) ◽  
pp. 381-395 ◽  
Author(s):  
Carlos Quintana ◽  
Javier Cabrera ◽  
Juan Perdomo ◽  
Francisco Estévez ◽  
Juan F. Loro ◽  
...  
Keyword(s):  
Cell Death ◽  
Apoptotic Cell ◽  
Apoptotic Cell Death ◽  
Leukemia Cells ◽  
Human Leukemia ◽  
Human Leukemia Cells

scholarly journals Iron toxicity, lipid peroxidation and ferroptosis after intracerebral haemorrhage

2019 ◽  
Vol 4 (2) ◽  
pp. 93-95 ◽  
Author(s):  
Jieru Wan ◽  
Honglei Ren ◽  
Jian Wang
Keyword(s):  
Lipid Peroxidation ◽  
Cell Death ◽  
Intracerebral Haemorrhage ◽  
Neuronal Death ◽  
Molecular Mechanisms ◽  
Apoptotic Cell ◽  
Iron Toxicity ◽  
Secondary Brain Injury

Intracerebral haemorrhage (ICH) is a devastating type of stroke with high mortality and morbidity. However, we have few options for ICH therapy and limited knowledge about post-ICH neuronal death and related mechanisms. In the aftermath of ICH, iron overload within the perihaematomal region can induce lethal reactive oxygen species (ROS) production and lipid peroxidation, which contribute to secondary brain injury. Indeed, iron chelation therapy has shown efficacy in preclinical ICH studies. Recently, an iron-dependent form of non-apoptotic cell death known as ferroptosis was identified. It is characterised by an accumulation of iron-induced lipid ROS, which leads to intracellular oxidative stress. The ROS cause damage to nucleic acids, proteins and lipid membranes, and eventually cell death. Recently, we and others discovered that ferroptosis does occur after haemorrhagic stroke in vitro and in vivo and contributes to neuronal death. Inhibition of ferroptosis is beneficial in several in vivo and in vitro ICH conditions. This minireview summarises current research on iron toxicity, lipid peroxidation and ferroptosis in the pathomechanisms of ICH, the underlying molecular mechanisms of ferroptosis and the potential for combined therapeutic strategies. Understanding the role of ferroptosis after ICH will provide a vital foundation for cell death-based ICH treatment and prevention.

Deletion of the Impg2 gene causes the degeneration of rod and cone cells in mice

2020 ◽  
Vol 29 (10) ◽  
pp. 1624-1634
Author(s):  
Huijuan Xu ◽  
Chao Qu ◽  
Li Gan ◽  
Kuanxiang Sun ◽  
Junkai Tan ◽  
...  
Keyword(s):  
Cell Death ◽  
Er Stress ◽  
Molecular Mechanisms ◽  
Histopathological Examination ◽  
Apoptotic Cell ◽  
Macular Dystrophy ◽  
Cone Cell ◽  
Rod Cells ◽  
Cone Cells

Abstract Variants in interphotoreceptor matrix proteoglycans (IMPG2) have been reported in retinitis pigmentosa (RP) and vitelliform macular dystrophy (VMD) patients. However, the underlying molecular mechanisms remain elusive due to a lack of suitable disease models. We developed two independent Impg2 knockout (KO) mouse models using the CRISPR/Cas9 technique to assess the in vivo functions of Impg2 in the retina. Impg2 ablation in mice recapitulated the RP phenotypes of patients, including an attenuated electroretinogram (ERG) response and the progressive degeneration of photoreceptors. The histopathological examination of Impg2-KO mice revealed irregularly arranged rod cells and mislocalized rhodopsin protein in the inner segment at 6 months of age. In addition to the pathological changes in rod cells, cone cells were also affected in KO retinas. KO retinas exhibited progressive cone cell death and impaired cone cell elongation. Further immunoblotting analysis revealed increased levels of endoplasmic reticulum (ER) stress-related proteins, including C/EBP homologous protein (CHOP), immunoglobulin heavy-chain-binding protein (BIP) and protein disulfide isomerase (PDI), in Impg2-KO mouse retinas. Increased gliosis and apoptotic cell death were also observed in the KO retinas. As autophagy is closely associated with ER stress, we then checked whether autophagy was disturbed in Impg2-KO mouse retinas. The results showed that autophagy was impaired in KO retinas, as revealed by the increased accumulation of SQSTM1 and other proteins involved in autophagy. Our results demonstrate the essential roles of Impg2 in the retina, and this study provides novel models for mechanistic investigations and development of therapies for RP caused by IMPG2 mutations.

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