Targeting TRPM2 Channels Impairs Radiation‐Induced Cell Cycle Arrest and Fosters Cell Death of T Cell Leukemia Cells in a Bcl‐2‐Dependent Manner

Klumpp, Dominik; Misovic, Milan; Szteyn, Kalina; Shumilina, Ekaterina; Rudner, Justine; Huber, Stephan M.

doi:10.1155/2016/8026702

Cited by 59 publications

(66 citation statements)

References 49 publications

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“…Our findings are consistent with the reports that HIF-1/2␣ promotes a more aggressive phenotype including disseminated disease and poor outcome in neuroblastoma patients (46,47,58). They are also consistent with a recent report that targeting the TRPM2 channel fostered cell death in T cell leukemia (59). The second important finding here is that mitochondrial function is significantly impaired by TRPM2 depletion; mitochondrial proteins including BNIP3 and COX4.1/4.2, oxygen consumption rate, and ATP levels after doxorubicin were all significantly reduced in the knock-out.…”

Section: Discussionsupporting

confidence: 93%

Depletion of the Human Ion Channel TRPM2 in Neuroblastoma Demonstrates Its Key Role in Cell Survival through Modulation of Mitochondrial Reactive Oxygen Species and Bioenergetics

Bao

Chen

Conrad

et al. 2016

Journal of Biological Chemistry

113

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Edited by Xiao-Fan WangTransient receptor potential melastatin 2 (TRPM2) ion channel has an essential function in modulating cell survival following oxidant injury and is highly expressed in many cancers including neuroblastoma. Here, in xenografts generated from neuroblastoma cells in which TRPM2 was depleted with CRISPR/Cas9 technology and in in vitro experiments, tumor growth was significantly inhibited and doxorubicin sensitivity increased. The hypoxia-inducible transcription factor 1/2␣ (HIF-1/2␣) signaling cascade including proteins involved in oxidant stress, glycolysis, and mitochondrial function was suppressed by TRPM2 depletion. TRPM2-depleted SH-SY5Y neuroblastoma cells demonstrated reduced oxygen consumption and ATP production after doxorubicin, confirming impaired cellular bioenergetics. In cells in which TRPM2 was depleted, mitochondrial superoxide production was significantly increased, particularly following doxorubicin. Ectopic expression of superoxide dismutase 2 (SOD2) reduced ROS and preserved viability of TRPM2-depleted cells, however, failed to restore ATP levels. Mitochondrial reactive oxygen species (ROS) were also significantly increased in cells in which TRPM2 function was inhibited by TRPM2-S, and pretreatment of these cells with the antioxidant MitoTEMPO significantly reduced ROS levels in response to doxorubicin and protected cell viability. Expression of the TRPM2 pore mutant E960D, in which calcium entry through TRPM2 is abolished, also resulted in significantly increased mitochondrial ROS following doxorubicin treatment, showing the critical role of TRPM2-mediated calcium entry. These findings demonstrate the important function of TRPM2 in modulation of cell survival through mitochondrial ROS, and the potential of targeted inhibition of TRPM2 as a therapeutic approach to reduce cellular bioenergetics, tumor growth, and enhance susceptibility to chemotherapeutic agents.

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Section: Discussionsupporting

confidence: 93%

Depletion of the Human Ion Channel TRPM2 in Neuroblastoma Demonstrates Its Key Role in Cell Survival through Modulation of Mitochondrial Reactive Oxygen Species and Bioenergetics

Bao

Chen

Conrad

et al. 2016

Journal of Biological Chemistry

113

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“…3). This is consistent with reports in neuroblastoma 31 , T-cell ALL 40 , and gastric cancer 38 in which TRPM2 depletion reduced malignant cell survival. It differs from a report examining AML generated on a Trpm2-/-genetic background in murine hematopoietic cells induced by retroviral introduction of MLL-AF9 or BCR-ABL-GFP and NUP98-HOXA9-YFP 41 .…”

Section: Discussionsupporting

confidence: 93%

Transient receptor potential ion channel TRPM2 promotes AML proliferation and survival through modulation of mitochondrial function, ROS, and autophagy

et al. 2020

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Transient receptor potential melastatin 2 (TRPM2) ion channel has an essential function in maintaining cell survival following oxidant injury. Here, we show that TRPM2 is highly expressed in acute myeloid leukemia (AML). The role of TRPM2 in AML was studied following depletion with CRISPR/Cas9 technology in U937 cells. In in vitro experiments and in xenografts, depletion of TRPM2 in AML inhibited leukemia proliferation, and doxorubicin sensitivity was increased. Mitochondrial function including oxygen consumption rate and ATP production was reduced, impairing cellular bioenergetics. Mitochondrial membrane potential and mitochondrial calcium uptake were significantly decreased in depleted cells. Mitochondrial reactive oxygen species (ROS) were significantly increased, and Nrf2 was decreased, reducing the antioxidant response. In TRPM2-depleted cells, ULK1, Atg7, and Atg5 protein levels were decreased, leading to autophagy inhibition. Consistently, ATF4 and CREB, two master transcription factors for autophagosome biogenesis, were reduced in TRPM2-depleted cells. In addition, Atg13 and FIP200, which are known to stabilize ULK1 protein, were decreased. Reconstitution with TRPM2 fully restored proliferation, viability, and autophagy; ATF4 and CREB fully restored proliferation and viability but only partially restored autophagy. TRPM2 expression reduced the elevated ROS found in depleted cells. These data show that TRPM2 has an important role in AML proliferation and survival through regulation of key transcription factors and target genes involved in mitochondrial function, bioenergetics, the antioxidant response, and autophagy. Targeting TRPM2 may represent a novel therapeutic approach to inhibit myeloid leukemia growth and enhance susceptibility to chemotherapeutic agents through multiple pathways.

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“…CaMKII, in turn, has been reported to regulate the cell cycle via inactivation of cdc25 isoforms and subsequent inactivation of cdc2 (CDK1) [39-42]. To define putative Ca 2+ -mediated VPA effects on cell cycle, VPA (0 or 750 µM for 48 h)-treated U251 cells were probed against cdc25A, -B, -C and cdc2 as well as against the phosphorylated forms of these proteins by immunoblotting.…”

Section: Resultsmentioning

confidence: 99%

Cellular Effects of the Antiepileptic Drug Valproic Acid in Glioblastoma

Eckert

Klumpp

Huber

2017

Cell Physiol Biochem

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Background/Aims: Valproic acid (VPA), an anticonvulsant and mood-stabilizing drug is used to treat epileptic seizure of glioblastoma patients. Besides its antiepileptic activity, VPA has been attributed further functions that improve the clinical outcome of glioblastoma patients. Those comprise the inhibition of some histone deacetylase (HDAC) isoforms which reportedly may result in radiosensitization. Retrospective analysis of patient data, however, could not unequivocally confirm a prolonged survival of glioblastoma patients receiving VPA. The present study aimed to identify potential VPA targets at the cellular level. Methods: To this end, the effect of VPA on metabolism, Ca²⁺-, biochemical and electro-signaling, cell-cycling, clonogenic survival and transfilter migration was analyzed in three human glioblastoma lines (T98G, U-87MG, U251) by MTT assay, Ca²⁺ imaging, immunoblotting, patch-clamp recording, flow cytometry, delayed plating colony formation and modified Boyden chamber assays, respectively. In addition, the effect of VPA on clonogenic survival of primary glioblastoma spheroid cultures treated with temozolomide and fractionated radiation was assessed by limited dilution assay. Results: In 2 of 3 glioblastoma lines, clinical relevant concentrations of VPA slightly slowed down cell cycle progression and decreased clonogenic survival. Furthermore, VPA induced Ca²⁺ signaling which was accompanied by pronounced K⁺ channel activity and transfilter cell migration. VPA did not affect metabolic NAD(P)H formation or radioresistance of the glioblastoma lines. Finally, VPA did not impair clonogenic survival or radioresistance of temozolomide-treated primary spheroid cultures. Conclusions: Combined, our in vitro data do not propose a general use of VPA as a radiosensitizer in anti-glioblastoma therapy.

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Targeting TRPM2 Channels Impairs Radiation‐Induced Cell Cycle Arrest and Fosters Cell Death of T Cell Leukemia Cells in a Bcl‐2‐Dependent Manner

Cited by 59 publications

References 49 publications

Depletion of the Human Ion Channel TRPM2 in Neuroblastoma Demonstrates Its Key Role in Cell Survival through Modulation of Mitochondrial Reactive Oxygen Species and Bioenergetics

Depletion of the Human Ion Channel TRPM2 in Neuroblastoma Demonstrates Its Key Role in Cell Survival through Modulation of Mitochondrial Reactive Oxygen Species and Bioenergetics

Transient receptor potential ion channel TRPM2 promotes AML proliferation and survival through modulation of mitochondrial function, ROS, and autophagy

Cellular Effects of the Antiepileptic Drug Valproic Acid in Glioblastoma

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