CSIG-23. ELONGATION CONTROL OF mRNA TRANSLATION DRIVES GROUP 3 MEDULLOBLASTOMA ADAPTATION TO NUTRIENT DEPRIVATION

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi38-vi38
Author(s):  
Alberto Delaidelli ◽  
Gian Luca Negri ◽  
Betty Yao ◽  
Que Xi Wang ◽  
Yue Zhou Huang ◽  
...  
Keyword(s):  
Cell Death ◽  
Mitochondrial Membrane ◽  
Large Scale ◽  
Metabolic Stress ◽  
Mrna Translation ◽  
Nutrient Deprivation ◽  
Mrna Levels ◽  
Metabolic Demand ◽  
Translation Elongation ◽  
Group 3

Abstract Group 3 affiliation and MYC genetic amplification are associated with poor life expectancy and substantial morbidity in children suffering from medulloblastoma (MB). However, the high metabolic demand induced by MYC-driven transformation sensitizes MYC-overexpressing MB to cell death under conditions of nutrient deprivation (ND). Additionally, MYC-driven transformation is known to promote mitochondrial oxidative phosphorylation (OXPHOS). We previously reported that eukaryotic Elongation Factor Kinase 2 (eEF2K), the master regulator of mRNA translation elongation, promotes survival of MYC-overexpressing tumors under ND. Interestingly, eEF2K is overexpressed in MYC-driven MB and our preliminary proteomics data highlight large-scale alterations in OXPHOS components affecting eEF2K deficient MB cells. We therefore hypothesized that eEF2K activity is required for the selective translation of mRNAs needed for efficient OXPHOS, and for the progression of MYC-driven MB. We pefrormed Multiplexed enhanced Protein Dynamic Mass Spectrometry in eEF2K knockdown MYC-overexpressing D425 MB cells to identify mRNAs selectively translated upon eEF2K activation. Messenger RNAs encoding multiple (9 out of 10 detected) components of the mitochondrial OXPHOS pathway are selectively translated upon eEF2K activation. Inactivation of eEF2K by genetic KO leads to the disassembly of electron transport chain (ETC) complexes I-IV without affecting mRNA levels of their respective components. Consistently, eEF2K KO MB cells display decreased mitochondrial membrane potential and 20% increased proton leak thorough the mitochondrial membrane. In addition, eEF2K inactivation results in increased Group 3 MB cell death under ND and doubles survival of MB bearing mice fed with calorie restricted diets (p< 0.05). Control of mRNA translation elongation by eEF2K is critical for mitochondrial ETC complex assembly and efficient OXPHOS in MYC-overexpressing MB, likely representing an adaptive response by which MYC-driven MB cells cope with acute metabolic stress. Future therapeutic studies will aim to combine eEF2K inhibition with caloric restriction mimetic drugs as eEF2K activity appears critical under metabolic stress conditions.

scholarly journals EMBR-20. ELONGATION CONTROL OF MRNA TRANSLATION DRIVES GROUP 3 MEDULLOBLASTOMA

2021 ◽  
Vol 23 (Supplement_1) ◽  
pp. i10-i10
Author(s):  
Alberto Delaidelli ◽  
Gian Luca Negri ◽  
Que Xi Wang ◽  
Albert Huang ◽  
Simran Sidhu ◽  
...  
Keyword(s):  
Binding Site ◽  
Elongation Factor ◽  
Metabolic Stress ◽  
Mrna Translation ◽  
Nutrient Deprivation ◽  
Myc Oncogene ◽  
Protein Levels ◽  
Cellular Mrnas ◽  
Group 3 ◽  
Potential Binding Site

Abstract Medulloblastoma (MB) is the most common pediatric intracranial tumor and leading cause of childhood related cancer deaths. Group 3 affiliation and genetic amplifications of the MYC oncogene are predictors of adverse outcome in MB, underscoring a dire need for novel and more effective therapeutic approaches. The let-7 family of small non-coding RNAs (miRNAs) is known to inhibit tumor progression and regulate metabolism by targeting and degrading several cellular mRNAs, including MYC. Indeed, let-7 miRNAs are frequently repressed in several cancer types, including in MYC-driven MB. We previously reported that the mRNA translation elongation regulator eukaryotic Elongation Factor-2 Kinase (eEF2K) is a pivotal mediator of cancer cell adaptation to nutrient deprivation. In the current work, we identified a potential binding site for let-7 miRNAs on the eEF2K 3’ untranslated region (UTR). In addition, eEF2K mRNA and let-7 miRNA expressions negatively correlate in MB, suggesting a potential regulation of the former by the latter. Let-7 miRNAs transfection decreases eEF2K mRNA and protein levels (by ~40–50%). Down-regulation of luciferase activity by let-7 miRNAs is impaired upon mutation of the let-7 binding site on the eEF2K 3’UTR. Inhibition of eEF2K significantly reduces survival of MYC-amplified MB cell lines under nutrient deprivation, altering their mRNA translation rates. Knockout of eEF2K increases survival of MYC-amplified MB xenografts when mice are kept under calorie restricted diets. We conclude that let-7 miRNAs degrade the eEF2K mRNA by binding to its 3’UTR, indicating that let-7 repression in MYC-driven MB is partially responsible for increased eEF2K levels. Moreover, the let-7-eEF2K axis constitutes a critical mechanism for MYC-driven MB adaptation to acute metabolic stress, representing a promising therapeutic target. Future therapeutic studies will aim to combine eEF2K inhibition with caloric restriction mimetic drugs, as eEF2K activity appears critical under metabolic stress conditions.

scholarly journals Metabolic demand regulates selective cell death in Parkinson′s Disease

2021 ◽  
Author(s):  
Ishaan S Nanal ◽  
Linxi Wang ◽  
Luke Y Zhao ◽  
Andrew Looka ◽  
Marianne Bezaire
Keyword(s):  
Cell Death ◽  
Single Neuron ◽  
Therapeutic Strategy ◽  
Calcium Influx ◽  
Metabolic Stress ◽  
Selective Vulnerability ◽  
Substantia Nigra Pars Compacta ◽  
Metabolic Demand ◽  
Channel Inhibition ◽  
The World

Parkinson′s Disease (PD) is a debilitating neurodegenerative condition that affects over 10 million people across the world, causing tremors and muscle weakness. Its mechanisms are unknown, but one key feature is selective cell death: neurons in the Substantia Nigra Pars Compacta (SNc) die, but their neighbors, the cells in the Ventral Tegmental Area (VTA), remain healthy. To study this phenomenon, we used an established single neuron model of the SNc, adapting its biophysical and bioenergetic properties to match that of the VTA. We discovered that reducing calcium influx correlates with higher ATP and lower ROS concentrations in the cell, suggesting in silico the importance of calcium influx in metabolic stress and selective vulnerability for Parkinson′s Disease. Future efforts may target calcium channel inhibition as a therapeutic strategy, although caution is needed with potential metabolic side effects.

Grape Seed Proanthocyanidins Protect N2a Cells against Ischemic Injury via Endoplasmic Reticulum Stress and Mitochondrial-associated Pathways

2019 ◽  
Vol 18 (4) ◽  
pp. 334-341 ◽  
Author(s):  
Kun Fu ◽  
Liqiang Chen ◽  
Lifeng Miao ◽  
Yan Guo ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Cell Viability ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Grape Seed ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Grape Seed Proanthocyanidins ◽  
N2a Cells ◽  
Caspase 12

Background/Objective: Grape seed proanthocyanidins (GSPs) are a group of polyphenolic bioflavonoids, which possess a variety of biological functions and pharmacological properties. We studied the neuroprotective effects of GSP against oxygen-glucose deprivation/reoxygenation (OGD/R) injury and the potential mechanisms in mouse neuroblastoma N2a cells. Methods: OGD/R was conducted in N2a cells. Cell viability was evaluated by CCK-8 and LDH release assay. Apoptosis was assessed by TUNEL staining and flow cytometry. Protein levels of cleaved caspase-3, Bax and Bcl-2 were detected by Western blotting. CHOP, GRP78 and caspase-12 mRNA levels were assessed by real-time PCR. JC-1 dying was used to detect mitochondrial membrane potential. ROS levels, activities of endogenous antioxidant enzymes and ATP production were examined to evaluate mitochondrial function. Results: GSP increased cell viability after OGD/R injury in a dose-dependent manner. Furthermore, GSP inhibited cell apoptosis, reduced the mRNA levels of CHOP, GRP78 and caspase-12 (ER stressassociated genes), restored mitochondrial membrane potential and ATP generation, improved activities of endogenous anti-oxidant ability (T-AOC, GXH-Px, and SOD), and decreased ROS level. Conclusion: Our findings suggest that GSP can protect N2a cells from OGD/R insult. The mechanism of anti-apoptotic effects of GSP may involve attenuating ER stress and mitochondrial dysfunction.

scholarly journals MicroRNA-513b-5p targets COL1A1 and COL1A2 associated with the formation and rupture of intracranial aneurysm

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zheng Zheng ◽  
Yan Chen ◽  
Yinzhou Wang ◽  
Yongkun Li ◽  
Qiong Cheng
Keyword(s):  
Cell Death ◽  
Intracranial Aneurysm ◽  
Luciferase Reporter Assay ◽  
Luciferase Reporter ◽  
Control Group ◽  
Type I ◽  
Mrna Levels ◽  
Reporter Assay ◽  
Over Expression ◽  
Tnf Α

AbstractCollagen-type I alpha 1 chain (COL1A1) and COL1A2 are abnormally expressed in intracranial aneurysm (IA), but their mechanism of action remains unclear. This study was performed to investigate the mechanism of COL1A1 and COL1A2 affecting the occurrence and rupture of IA. Quantitative real-time polymerase chain reaction was used to measure the expression of hsa-miR-513b-5p, COL1A1, COL1A2, TNF-α, IL-6, MMP2, MMP3, MMP9 and TIMP4 in patients with ruptured IA (RA) (n = 100), patients with un-ruptured IA (UA) (n = 100), and controls (n = 100). Then, human vascular smooth muscle cells (HASMCs) were cultured, and dual luciferase reporter assay was performed to analyse the targeting relationship between miR-513b-5p and COL1A1 or COL1A2. The effects of the miR-513b-5p mimic and inhibitor on the proliferation, apoptosis, and death of HASMC and the RIP1-RIP3-MLKL and matrix metalloproteinase pathways were also explored. The effect of silencing and over-expression of COL1A1 and COL1A2 on the role of miR-513b-5p were also evaluated. Finally, the effects of TNF-α on miR-513b-5p targeting COL1A1 and COL1A2 were tested. Compared with those in the control group, the serum mRNA levels of miR-513b-5p, IL-6 and TIMP4 were significantly decreased in the RA and UA groups, but COL1A1, COL1A2, TNF-α, IL-1β, MMP2, MMP3 and MMP9 were significantly increased (p < 0.05). Compared with those in the UA group, the expression of COL1A1, COL1A2, TNF-α, IL-1β and MMP9 was significantly up-regulated in the RA group (p < 0.05). Results from the luciferase reporter assay showed that COL1A1 and COL1A were the direct targets of miR-513b-5p. Further studies demonstrated that miR-513b-5p targeted COL1A1/2 to regulate the RIP1-RIP3-MLKL and MMP pathways, thereby enhancing cell death and apoptosis. Over-expression of COL1A1 or COL1A2, rather than silencing COL1A1/2, could improve the inhibitory effect of miR-513b-5p on cell activity by regulating the RIP1-RIP3-MLKL and MMP pathways. Furthermore, over-expression of miR-513b-5p and/or silencing COL1A1/2 inhibited the TNF-α-induced cell proliferation and enhanced the TNF-α-induced cell death and apoptosis. The mechanism may be related to the inhibition of collagen I and TIMP4 expression and promotion of the expression of RIP1, p-RIP1, p-RIP3, p-MLKL, MMP2 and MMP9. MiR-513b-5p targeted the inhibition of COL1A1/2 expression and affected HASMC viability and extracellular mechanism remodelling by regulating the RIP1-RIP3-MLKL and MMP pathways. This process might be involved in the formation and rupture of IA.

scholarly journals MBRS-48. IDENTIFICATION OF NOVEL THERAPEUTIC APPROACHES FOR MYC-DRIVEN MEDULLOBLASTOMA

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii406-iii406
Author(s):  
Kübra Taban ◽  
David Pauck ◽  
Mara Maue ◽  
Viktoria Marquardt ◽  
Hua Yu ◽  
...  
Keyword(s):  
New Drugs ◽  
Current Therapy ◽  
Cancer Drug ◽  
Mrna Levels ◽  
Cell Models ◽  
Therapeutic Approaches ◽  
Group 3 ◽  
Novel Therapeutic

Abstract Medulloblastoma (MB) is the most common malignant brain tumor in children and is frequently metastatic at diagnosis. Treatment with surgery, radiation and multi-agent chemotherapy may leave survivors of these brain tumors with long-term deficits as a consequence. One of the four consensus molecular subgroups of MB is the MYC-driven group 3 MB, which is the most malignant type and has a poor prognosis under current therapy. Thus, it is important to discover more effective targeted therapeutic approaches. We conducted a high-throughput drug screening to identify novel compounds showing efficiency in group 3 MB using both clinically established inhibitors (n=196) and clinically-applicable compounds (n=464). More than 20 compounds demonstrated a significantly higher anti-tumoral effect in MYChigh (n=7) compared to MYClow (n=4) MB cell models. Among these compounds, Navitoclax and Clofarabine showed the strongest effect in inducing cell cycle arrest and apoptosis in MYChigh MB models. Furthermore, we show that Navitoclax, an orally bioavailable and blood-brain barrier passing anti-cancer drug, inhibits specifically Bcl-xL proteins. In line, we found a significant correlation between BCL-xL and MYC mRNA levels in 763 primary MB patient samples (Data source: “R2 https://hgserver1.amc.nl”). In addition, Navitoclax and Clofarabine have been tested in cells obtained from MB patient-derived-xenografts, which confirmed their specific efficacy in MYChigh versus MYClow MB. In summary, our approach has identified promising new drugs that significantly reduce cell viability in MYChigh compared to MYClow MB cell models. Our findings point to novel therapeutic vulnerabilities for MB that need to be further validated in vitro and in vivo.

scholarly journals Apoptosis-like cell death upon kinetoplastid induction by compounds isolated from the brown algae Dictyota spiralis

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Olfa Chiboub ◽  
Ines Sifaoui ◽  
Manef Abderrabba ◽  
Mondher Mejri ◽  
José J. Fernández ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Cell Death ◽  
Mitochondrial Membrane ◽  
Brown Seaweed ◽  
Cell Permeability ◽  
Oxygen Species ◽  
Potential Drug ◽  
Concentration Cell ◽  
Drug Candidates

Abstract Background The in vitro activity of the brown seaweed Dictyota spiralis against both Leishmania amazonensis and Trypanosoma cruzi was evaluated in a previous study. Processing by bio-guided fractionation resulted in the isolation of three active compounds, classified as diterpenes. In the present study, we performed several assays to detect clinical features associated to cell death in L. amazonensis and T. cruzi with the aim to elucidate the mechanism of action of these compounds on parasitic cells. Methods The aims of the experiments were to detect and evaluate specific events involved in apoptosis-like cell death in the kinetoplastid, including DNA condensation, accumulation of reactive oxygen species and changes in ATP concentration, cell permeability and mitochondrial membrane potential, respectively, in treated cells. Results The results demonstrated that the three isolated diterpenes could inhibit the tested parasites by inducing an apoptosis-like cell death. Conclusions These results encourage further investigation on the isolated compounds as potential drug candidates against both L. amazonensis and T. cruzi. Graphic abstract

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