bims-mibica 2022-08-14 papers

bims-mibica

Biomed News

on Mitochondrial bioenergetics in cancer

Issue of 2022‒08‒14
35 papers selected by
Kelsey Fisher-Wellman, East Carolina University

Loss of Mitochondrial Fatty Acid β-Oxidation Protein Short Chain Enoyl-CoA Hydratase Disrupts Oxidative Phosphorylation Protein Complex Stability and Function.
Effect of metformin on intact mitochondria from liver and brain: Concept revisited.
Balanced mitochondrial and cytosolic translatomes underlie the biogenesis of human respiratory complexes.
Nicotinamide riboside alleviates exercise intolerance in ANT1-deficient mice.
Rapid and selective generation of H2S within mitochondria protects against cardiac ischemia-reperfusion injury.
Impact of Aging and Lifelong Exercise Training on Mitochondrial Function and Network Connectivity in Human Skeletal Muscle.
The mitochondrial enzyme FAHD1 regulates complex II activity in breast cancer cells and is indispensable for basal BT-20 cells in vitro.
Lipid droplets promote efficient mitophagy.
Mammalian RNase H1 directs RNA primer formation for mtDNA replication initiation and is also necessary for mtDNA replication completion.
Lactate is an epigenetic metabolite that drives survival in model systems of glioblastoma.
A Proof-of-Concept Inhibitor of Endothelial Lipase Suppresses Triple-Negative Breast Cancer Cells by Hijacking the Mitochondrial Function.
AXL Promotes Metformin-Induced Apoptosis Through Mediation of Autophagy by Activating ROS-AMPK-ULK1 Signaling in Human Esophageal Adenocarcinoma.
Different platforms for mitomiRs in mitochondria: Emerging facets in regulation of mitochondrial functions.
Inner Mitochondrial Membrane Sensitivity to Na+ Reveals Partially Segmented Functional CoQ Pools.
Blocking ActRIIB and restoring appetite reverses cachexia and improves survival in mice with lung cancer.
Refining the Role of Pyruvate Dehydrogenase Kinases in Glioblastoma Development.
Mitochondrial ROS drive resistance to chemotherapy and immune-killing in hypoxic non-small cell lung cancer.
Stressed to death: Mitochondrial stress responses connect respiration and apoptosis in cancer.
Metabolic Reprogramming Helps to Define Different Metastatic Tropisms in Colorectal Cancer.
The metabolic addiction of cancer stem cells.
Phosphoproteomics of primary AML patient samples reveals rationale for AKT combination therapy and p53 context to overcome selinexor resistance.
Age-related increase of mitochondrial content in human memory CD4+ T cells contributes to ROS-mediated increased expression of proinflammatory cytokines.
Pan-Cancer Analysis of Voltage-Dependent Anion Channel (VDAC1) as a Cancer Therapeutic Target or Diagnostic Biomarker.
The Mitochondrial NAD Kinase Functions as a Major Metabolic Regulator Upon Increased Energy Demand.
Mutated FANCA Gene Role in the Modulation of Energy Metabolism and Mitochondrial Dynamics in Head and Neck Squamous Cell Carcinoma.
Inhibition of LPAR6 overcomes sorafenib resistance by switching glycolysis into oxidative phosphorylation in hepatocellular carcinoma.
Impact of metabolic stress induced by diets, aging and fasting on tissue oxygen consumption.
Impaired mitochondria promote aging-associated sebaceous gland dysfunction and pathology.
MYC sensitises cells to apoptosis by driving energetic demand.
High-throughput sequencing analysis of nuclear-encoded mitochondrial genes reveals a genetic signature of human longevity.
Cold atmospheric plasma induces apoptosis in human colon and lung cancer cells through modulating mitochondrial pathway.
Peripheral blood leukocyte mitochondrial DNA content and risk of lung cancer.
Glutamine deprivation impairs function of infiltrating CD8+ T cells in hepatocellular carcinoma by inducing mitochondrial damage and apoptosis.
DHODH is an independent prognostic marker and potent therapeutic target in neuroblastoma.
Histone lysine demethylase inhibition reprograms prostate cancer metabolism and mechanics.

FEBS J. 2022 Aug 13.

Loss of Mitochondrial Fatty Acid β-Oxidation Protein Short Chain Enoyl-CoA Hydratase Disrupts Oxidative Phosphorylation Protein Complex Stability and Function.

Harrison Burgin, Alice J Sharpe, Shuai Nie, Mark Ziemann, Jordan J Crameri, Diana Stojanovski, James Pitt, Akira Ohtake, Kei Murayama, Matthew McKenzie.

  Short chain enoyl-CoA hydratase 1 (ECHS1) is involved in the second step of mitochondrial fatty acid β-oxidation (FAO), catalysing the hydration of short chain enoyl-CoA esters to short chain 3-hyroxyl-CoA esters. Genetic deficiency in ECHS1 (ECHS1D) is associated with a specific subset of Leigh Syndrome, a disease typically caused by defects in oxidative phosphorylation (OXPHOS). Here, we examined the molecular pathogenesis of ECHS1D using a CRISPR/Cas9 edited human cell 'knockout' model and fibroblasts from ECHS1D patients. Transcriptome analysis of ECHS1 'knockout' cells showed reductions in key mitochondrial pathways, including the TCA cycle, receptor mediated mitophagy and nucleotide biosynthesis. Subsequent proteomic analyses confirmed these reductions and revealed additional defects in mitochondrial oxidoreductase activity and fatty acid β-oxidation. Functional analysis of ECHS1 'knockout' cells showed reduced mitochondrial oxygen consumption rates when metabolising glucose or OXPHOS complex I-linked substrates, as well as decreased complex I and complex IV enzyme activities. ECHS1 'knockout' cells also exhibited decreased OXPHOS protein complex steady-state levels (complex I, complex III2 , complex IV, complex V and supercomplexes CIII2 /CIV and CI/CIII2 /CIV), which were associated with a defect in complex I assembly. Patient fibroblasts exhibit varied reduction of mature OXPHOS complex steady-state levels, with defects detected in CIII2 , CIV, CV and the CI/CIII2 /CIV supercomplex. Overall, these findings highlight the contribution of defective OXPHOS function, in particular complex I deficiency, to the molecular pathogenesis of ECHS1D.

Keywords:  ECHS1 deficiency; OXPHOS; fatty acid oxidation; mitochondria; mitochondrial disease; short chain enoyl-CoA hydratase

DOI:  https://doi.org/10.1111/febs.16595
Eur J Pharmacol. 2022 Aug 04. pii: S0014-2999(22)00438-1. [Epub ahead of print] 175177

Effect of metformin on intact mitochondria from liver and brain: Concept revisited.

Belem Yoval-Sánchez, Fariha Ansari, Dmitry Lange, Alexander Galkin.

  Metformin is an antihyperglycemic drug which is being examined as a repurposed treatment for cardiovascular disease for individuals without diabetes mellitus. Despite evidence that mitochondrial respiratory complex I is a target of metformin and inhibition of the enzyme is one of the mechanisms of its therapeutic actions, no systematic studies of the metformin effect on intact mitochondria have been reported. In the presented paper, we described the effect of metformin on respiration and ROS release by intact mitochondria from the liver and brain. By comparing the effect of metformin on mitochondria oxidizing different substrates, we found direct inhibition of respiration and stimulation of ROS release when complex I-based respiration is measured (forward electron transfer). Metformin had no effect on respiration rates but inhibited ROS release when mitochondria oxidize succinate or glycerol 3-phosphate in conditions of reverse electron transfer in complex I. In addition, we found that metformin is a weak effector of the active/deactive (A/D) transition of mitochondrial complex I. At high concentrations, metformin increases the rate of spontaneous deactivation of complex I (A→D transition). The results obtained are consistent with the concept of metformin inhibition of complex I and that it can either stimulate or inhibit mitochondrial ROS production depending on the preferential respiratory substrate. This is relevant during the reperfusion process, to counteract the damage produced by ROS when a high level of reverse electron transfer substrates is generated after an ischemic event.

Keywords:  A/D transition; Metformin; Mitochondrial complex I; ROS production; Respiration

DOI:  https://doi.org/10.1016/j.ejphar.2022.175177
Genome Biol. 2022 Aug 09. 23(1): 170

Balanced mitochondrial and cytosolic translatomes underlie the biogenesis of human respiratory complexes.

Iliana Soto, Mary Couvillion, Katja G Hansen, Erik McShane, J Conor Moran, Antoni Barrientos, L Stirling Churchman.

BACKGROUND: Oxidative phosphorylation (OXPHOS) complexes consist of nuclear and mitochondrial DNA-encoded subunits. Their biogenesis requires cross-compartment gene regulation to mitigate the accumulation of disproportionate subunits. To determine how human cells coordinate mitochondrial and nuclear gene expression processes, we tailored ribosome profiling for the unique features of the human mitoribosome.RESULTS: We resolve features of mitochondrial translation initiation and identify a small ORF in the 3' UTR of MT-ND5. Analysis of ribosome footprints in five cell types reveals that average mitochondrial synthesis levels correspond precisely to cytosolic levels across OXPHOS complexes, and these average rates reflect the relative abundances of the complexes. Balanced mitochondrial and cytosolic synthesis does not rely on rapid feedback between the two translation systems, and imbalance caused by mitochondrial translation deficiency is associated with the induction of proteotoxicity pathways.
CONCLUSIONS: Based on our findings, we propose that human OXPHOS complexes are synthesized proportionally to each other, with mitonuclear balance relying on the regulation of OXPHOS subunit translation across cellular compartments, which may represent a proteostasis vulnerability.

DOI: https://doi.org/10.1186/s13059-022-02732-9
Mol Metab. 2022 Aug 06. pii: S2212-8778(22)00129-6. [Epub ahead of print] 101560

Nicotinamide riboside alleviates exercise intolerance in ANT1-deficient mice.

Patrick M Schaefer, Jessica Huang, Arrienne Butic, Caroline Perry, Tal Yardeni, Wendy Tan, Ryan Morrow, Joseph A Baur, Douglas C Wallace.

  OBJECTIVE: Mitochondrial disorders are often characterized by muscle weakness and fatigue. Null mutations in the heart-muscle adenine nucleotide translocator isoform 1 (ANT1) of both humans and mice cause cardiomyopathy and myopathy associated with exercise intolerance and muscle weakness. Here we decipher the molecular underpinnings of ANT1-deficiency-mediated exercise intolerance.METHODS: This was achieved by correlating exercise physiology, mitochondrial function and metabolomics of mice deficient in ANT1 and comparing this to control mice.
RESULTS: We demonstrate a peripheral limitation of skeletal muscle mitochondrial respiration and a reduced complex I respiration in ANT1-deficient mice. Upon exercise, this results in a lack of NAD+ leading to a substrate limitation and stalling of the TCA cycle and mitochondrial respiration, further limiting skeletal muscle mitochondrial respiration. Treatment of ANT1-deficient mice with nicotinamide riboside increased NAD+ levels in skeletal muscle and liver, which increased the exercise capacity and the mitochondrial respiration.
CONCLUSION: Increasing NAD + levels with nicotinamide riboside can alleviate the exercise intolerance associated to ANT1-deficiency, indicating the therapeutic potential of NAD+-stimulating compounds in mitochondrial myopathies.

Keywords:  Exercise; Mitochondrial disorder; NAD(+)/NADH; Nicotinamide riboside

DOI:  https://doi.org/10.1016/j.molmet.2022.101560
Redox Biol. 2022 Aug 05. pii: S2213-2317(22)00201-4. [Epub ahead of print]55 102429

Rapid and selective generation of H2S within mitochondria protects against cardiac ischemia-reperfusion injury.

Jan Lj Miljkovic, Nils Burger, Justyna M Gawel, John F Mulvey, Abigail A I Norman, Takanori Nishimura, Yoshiyuki Tsujihata, Angela Logan, Olga Sauchanka, Stuart T Caldwell, Jordan L Morris, Tracy A Prime, Stefan Warrington, Julien Prudent, Georgina R Bates, Dunja Aksentijević, Hiran A Prag, Andrew M James, Thomas Krieg, Richard C Hartley, Michael P Murphy.

  Mitochondria-targeted H2S donors are thought to protect against acute ischemia-reperfusion (IR) injury by releasing H2S that decreases oxidative damage. However, the rate of H2S release by current donors is too slow to be effective upon administration following reperfusion. To overcome this limitation here we develop a mitochondria-targeted agent, MitoPerSulf that very rapidly releases H2S within mitochondria. MitoPerSulf is quickly taken up by mitochondria, where it reacts with endogenous thiols to generate a persulfide intermediate that releases H2S. MitoPerSulf is acutely protective against cardiac IR injury in mice, due to the acute generation of H2S that inhibits respiration at cytochrome c oxidase thereby preventing mitochondrial superoxide production by lowering the membrane potential. Mitochondria-targeted agents that rapidly generate H2S are a new class of therapy for the acute treatment of IR injury.

Keywords:  Hydrogen sulfide donors; Ischemia-reperfusion injury; Mitochondria; Mitochondria targeting; Reverse electron transport (RET)

DOI:  https://doi.org/10.1016/j.redox.2022.102429
J Gerontol A Biol Sci Med Sci. 2022 Aug 12. pii: glac164. [Epub ahead of print]

Impact of Aging and Lifelong Exercise Training on Mitochondrial Function and Network Connectivity in Human Skeletal Muscle.

Stine Ringholm, Anders Gudiksen, Jens Frey Halling, Albina Qoqaj, Philip Meizner Rasmussen, Clara Prats, Peter Plomgaard, Henriette Pilegaard.

  Aging is associated with metabolic decline and reduction in mitochondrial function in skeletal muscle which can be delayed by physical activity. Moreover, exercise training has been shown to prevent age-associated decline in mitochondrial function and fragmentation of the mitochondrial network in mouse skeletal muscle. However, whether lifelong endurance exercise training exerts the same effects in human skeletal muscle is still not clear. Therefore, the aim of the present study was to examine the effect of volume-dependent lifelong endurance exercise training on mitochondrial function and network connectivity in older human skeletal muscle. Skeletal muscle complex I+II-linked mitochondrial respiration per tissue mass was higher, but intrinsic complex I+II-linked mitochondrial respiration was lower in highly trained older than in young untrained, older untrained and older moderately trained men. Mitochondrial volume and connectivity were higher in highly trained older than in untrained and moderately trained older subjects. Furthermore, protein content of the ADP/ATP exchangers ANT1 + 2 and VDAC was higher and of the mitophagic marker Parkin lower in skeletal muscle from the highly trained older than from untrained and moderately trained older subjects. In contrast, H2O2 emission in skeletal muscle was not affected by either age or exercise training, but SOD2 protein content was higher in highly trained older than in untrained and moderately trained older subjects. This suggests that healthy aging does not induce oxidative stress or mitochondrial network fragmentation in human skeletal muscle, but high-volume exercise training increases mitochondrial volume and network connectivity, thereby increasing oxidative capacity in older human skeletal muscle.

Keywords:  Mitochondria; mitophagy; physical activity; respirometry; skeletal muscle

DOI:  https://doi.org/10.1093/gerona/glac164
FEBS Lett. 2022 Aug 02.

The mitochondrial enzyme FAHD1 regulates complex II activity in breast cancer cells and is indispensable for basal BT-20 cells in vitro.

Max Holzknecht, Lena Guerrero-Navarro, Michele Petit, Eva Albertini, Elisabeth Damisch, Anna Simonini, Fernando Schmitt, Walther Parson, Heidelinde Fiegl, Alexander Weiss, Pidder Jansen-Duerr.

  The mitochondrial enzyme fumarylacetoacetate hydrolase domain-containing protein 1 (FAHD1) was identified to be upregulated in breast cancer tissues. Here, we show that FAHD1 is indispensable for the survival of BT-20 cells, representing the basal breast cancer cell type. A lentiviral knock-down of FAHD1 in the breast cancer cell lines MCF-7 and BT-20 results in lower succinate dehydrogenase (complex II) activity. In luminal MCF-7 cells, this leads to reduced proliferation when cultured in medium containing only glutamine as the carbon source. Of note, both cell lines show attenuated protein levels of the enzyme glutaminase (GLS) which activates programmed cell death in BT-20. These findings demonstrate that FAHD1 is crucial for the functionality of complex II in breast cancer cells and acts on glutaminolysis in the mitochondria.

Keywords:  FAHD1; MCF-7; TNBC; glutaminase; oxaloacetate; succinate dehydrogenase

DOI:  https://doi.org/10.1002/1873-3468.14462
Autophagy. 2022 Aug 08. 1-2

Lipid droplets promote efficient mitophagy.

Maeve Long, Thomas G McWilliams.

  Mitophagy neutralizes defective mitochondria via lysosomal elimination. Increased levels of mitophagy hallmark metabolic transitions and are induced by iron depletion, yet its metabolic basis has not been studied in-depth. How mitophagy integrates with different homeostatic mechanisms to support metabolic integrity is incompletely understood. We examined metabolic adaptations in cells treated with deferiprone (DFP), a therapeutic iron chelator known to induce PINK1-PRKN-independent mitophagy. We found that iron depletion profoundly rewired the cellular metabolome, remodeling lipid metabolism within minutes of treatment. DGAT1-dependent lipid droplet biosynthesis occurs upstream of mitochondrial turnover, with many LDs bordering mitochondria upon iron chelation. Surprisingly, DGAT1 inhibition restricts mitophagy in vitro by lysosomal dysfunction. Genetic depletion of mdy/DGAT1 in vivo impairs neuronal mitophagy and locomotor function in Drosophila, demonstrating the physiological relevance of our findings.

Keywords:  DGAT1; iron; lipid droplet; metabolism; mitophagy

DOI:  https://doi.org/10.1080/15548627.2022.2089956
Nucleic Acids Res. 2022 Aug 10. pii: gkac661. [Epub ahead of print]

Mammalian RNase H1 directs RNA primer formation for mtDNA replication initiation and is also necessary for mtDNA replication completion.

Jelena Misic, Dusanka Milenkovic, Ali Al-Behadili, Xie Xie, Min Jiang, Shan Jiang, Roberta Filograna, Camilla Koolmeister, Stefan J Siira, Louise Jenninger, Aleksandra Filipovska, Anders R Clausen, Leonardo Caporali, Maria Lucia Valentino, Chiara La Morgia, Valerio Carelli, Thomas J Nicholls, Anna Wredenberg, Maria Falkenberg, Nils-Göran Larsson.

The in vivo role for RNase H1 in mammalian mitochondria has been much debated. Loss of RNase H1 is embryonic lethal and to further study its role in mtDNA expression we characterized a conditional knockout of Rnaseh1 in mouse heart. We report that RNase H1 is essential for processing of RNA primers to allow site-specific initiation of mtDNA replication. Without RNase H1, the RNA:DNA hybrids at the replication origins are not processed and mtDNA replication is initiated at non-canonical sites and becomes impaired. Importantly, RNase H1 is also needed for replication completion and in its absence linear deleted mtDNA molecules extending between the two origins of mtDNA replication are formed accompanied by mtDNA depletion. The steady-state levels of mitochondrial transcripts follow the levels of mtDNA, and RNA processing is not altered in the absence of RNase H1. Finally, we report the first patient with a homozygous pathogenic mutation in the hybrid-binding domain of RNase H1 causing impaired mtDNA replication. In contrast to catalytically inactive variants of RNase H1, this mutant version has enhanced enzyme activity but shows impaired primer formation. This finding shows that the RNase H1 activity must be strictly controlled to allow proper regulation of mtDNA replication.

DOI: https://doi.org/10.1093/nar/gkac661
Mol Cell. 2022 Aug 09. pii: S1097-2765(22)00647-5. [Epub ahead of print]

Lactate is an epigenetic metabolite that drives survival in model systems of glioblastoma.

Consuelo Torrini, Trang Thi Thu Nguyen, Chang Shu, Angeliki Mela, Nelson Humala, Aayushi Mahajan, Erin Heather Seeley, Guoan Zhang, Mike-Andrew Westhoff, Georg Karpel-Massler, Jeffrey N Bruce, Peter Canoll, Markus D Siegelin.

  Lactate accumulates to a significant amount in glioblastomas (GBMs), the most common primary malignant brain tumor with an unfavorable prognosis. However, it remains unclear whether lactate is metabolized by GBMs. Here, we demonstrated that lactate rescued patient-derived xenograft (PDX) GBM cells from nutrient-deprivation-mediated cell death. Transcriptome analysis, ATAC-seq, and ChIP-seq showed that lactate entertained a signature of oxidative energy metabolism. LC/MS analysis demonstrated that U-13C-lactate elicited substantial labeling of TCA-cycle metabolites, acetyl-CoA, and histone protein acetyl-residues in GBM cells. Lactate enhanced chromatin accessibility and histone acetylation in a manner dependent on oxidative energy metabolism and the ATP-citrate lyase (ACLY). Utilizing orthotopic PDX models of GBM, a combined tracer experiment unraveled that lactate carbons were substantially labeling the TCA-cycle metabolites. Finally, pharmacological blockage of oxidative energy metabolism extended overall survival in two orthotopic PDX models in mice. These results establish lactate metabolism as a novel druggable pathway for GBM.

Keywords:  ATAC-seq; ChIP-seq; glioblastoma; lactate; metabolic flux analysis; tumor metabolism

DOI:  https://doi.org/10.1016/j.molcel.2022.06.030
Cancers (Basel). 2022 Aug 02. pii: 3763. [Epub ahead of print]14(15):

A Proof-of-Concept Inhibitor of Endothelial Lipase Suppresses Triple-Negative Breast Cancer Cells by Hijacking the Mitochondrial Function.

Rongze Yang, Shuyan Han, Joseph Clayton, Mahan Haghighatian, Cheng-Chieh Tsai, Yuan Yao, Pingping Li, Jana Shen, Qun Zhou.

  Triple-negative breast cancer (TNBC) cells reprogram their metabolism to provide metabolic flexibility for tumor cell growth and survival in the tumor microenvironment. While our previous findings indicated that endothelial lipase (EL/LIPG) is a hallmark of TNBC, the precise mechanism through which LIPG instigates TNBC metabolism remains undefined. Here, we report that the expression of LIPG is associated with long non-coding RNA DANCR and positively correlates with gene signatures of mitochondrial metabolism-oxidative phosphorylation (OXPHOS). DANCR binds to LIPG, enabling tumor cells to maintain LIPG protein stability and OXPHOS. As one mechanism of LIPG in the regulation of tumor cell oxidative metabolism, LIPG mediates histone deacetylase 6 (HDAC6) and histone acetylation, which contribute to changes in IL-6 and fatty acid synthesis gene expression. Finally, aided by a relaxed docking approach, we discovered a new LIPG inhibitor, cynaroside, that effectively suppressed the enzyme activity and DANCR in TNBC cells. Treatment with cynaroside inhibited the OXPHOS phenotype of TNBC cells, which severely impaired tumor formation. Taken together, our study provides mechanistic insights into the LIPG modulation of mitochondrial metabolism in TNBC and a proof-of-concept that targeting LIPG is a promising new therapeutic strategy for the treatment of TNBC.

Keywords:  EL/LIPG; TNBC; a new LIPG inhibitor cynaroside; histone deacetylase HDAC6; long non-coding RNA DANCR; metabolism

DOI:  https://doi.org/10.3390/cancers14153763
Front Oncol. 2022 ;12 903874

AXL Promotes Metformin-Induced Apoptosis Through Mediation of Autophagy by Activating ROS-AMPK-ULK1 Signaling in Human Esophageal Adenocarcinoma.

Jun Hong, Selma Maacha, Nataliya Pidkovka, Andreia Bates, Safia N Salaria, Mary K Washington, Abbes Belkhiri.

  AXL receptor tyrosine kinase promotes an invasive phenotype and chemotherapy resistance in esophageal adenocarcinoma (EAC). AXL has been implicated in the regulation of autophagy, but the underlying molecular mechanism remains poorly understood. Herein, we investigate the mechanistic role of AXL in autophagy as well as metformin-induced effects on the growth and survival of EAC. We demonstrate that AXL mediates autophagic flux through activation of AMPK-ULK1 signaling in a reactive oxygen species (ROS)-dependent mechanism by glucose starvation. AXL positively regulates basal cellular ROS levels without significantly affecting mitochondrial ROS production in EAC cells. Pharmacological inhibition of cellular ROS using Trolox abrogates glucose starvation-induced AMPK signaling and autophagy. We demonstrate that AXL expression is required for metformin-induced apoptosis in EAC cells in vitro. The apoptosis induction by metformin is markedly attenuated by inhibition of autophagy through genetic silencing of Beclin1 or ATG7 autophagy mediators, thereby confirming the requirement of intact autophagy for enhancing metformin-induced apoptosis in EAC cells. Our data indicate that metformin-induced autophagy displays a pro-apoptotic function in EAC cells. We show that the metformin-induced suppression of tumor growth in vivo is highly dependent on AXL expression in a tumor xenograft mouse model of EAC. We demonstrate that AXL promotes metformin-induced apoptosis through activation of autophagy in EAC. AXL may be a valuable biomarker to identify tumors that are sensitive to metformin. Therefore, AXL expression could inform the selection of patients for future clinical trials to evaluate the therapeutic efficacy of metformin in EAC.

Keywords:  AMPK; ATG7; Barrett’s esophagus; Beclin1; autophagic flux; glucose starvation; proliferation; reactive oxygen species

DOI:  https://doi.org/10.3389/fonc.2022.903874
Mitochondrion. 2022 Aug 06. pii: S1567-7249(22)00072-1. [Epub ahead of print]

Different platforms for mitomiRs in mitochondria: Emerging facets in regulation of mitochondrial functions.

Dhruv Gohel, Rajesh Singh.

  Mitochondria are one of the central organelles involved in cellular energy metabolism and play a regulatory role in various human pathologies ranging from inborn errors of metabolism, cancer, inflammation, and infections. Mitochondrial DNA encodes limited number of genes that is not sufficient for its optimal functioning. Hence, mitochondria import ∼1500 of proteins and ncRNAs from the nucleus depending on energy requirement of cell, tissue size, complexity and diversity of functions. Mitochondrial outer membrane can serve as a platform for regulation of local translation of nuclear-encoded mRNAs for mitochondrial proteins (nmRNAmp); however, underlying molecular mechanism for translational regulation of nmRNAmp at mitochondria is unexplored. Emerging evidence now suggest that mitochondria are enriched with specific miRNAs known as mitomiRs, which may be nuclear or mitochondrial DNA encoded. MitomiRs may modulate mitochondrial function and metabolism by fine-tuning protein levels related to mitochondria. The discovery of mitomiRs raised the questions of elucidating molecular pathways for their biogenesis, translocation, action sites and mechanism of action. Here, we have reviewed the existing reports describing the role of mitomiRs in sub mitochondrial compartments and discussed possible molecular mechanisms of mitomiRs in the regulation of nmRNAmp and mito-genome encoded transcripts. Further understanding of mitomiRs will uncover their implication in various pathophysiological conditions associated with mitochondria.

Keywords:  Ago2; Mitochondria; MitomiRs; RISC; nmRNAmp

DOI:  https://doi.org/10.1016/j.mito.2022.08.003
J Vis Exp. 2022 Jul 20.

Inner Mitochondrial Membrane Sensitivity to Na+ Reveals Partially Segmented Functional CoQ Pools.

Pablo Hernansanz-Agustín, José Antonio Enríquez.

Ubiquinone (CoQ) pools in the inner mitochondrial membrane (IMM) are partially segmented to either complex I or FAD-dependent enzymes. Such subdivision can be easily assessed by a comparative assay using NADH or succinate as electron donors in frozen-thawed mitochondria, in which cytochrome c (cyt c) reduction is measured. The assay relies on the effect of Na+ on the IMM, decreasing its fluidity. Here, we present a protocol to measure NADH-cyt c oxidoreductase activity and succinate-cyt c oxidoreductase activities in the presence of NaCl or KCl. The reactions, which rely on the mixture of reagents in a cuvette in a stepwise manner, are measured spectrophotometrically during 4 min in the presence of Na+ or K+. The same mixture is performed in parallel in the presence of the specific enzyme inhibitors in order to subtract the unspecific change in absorbance. NADH-cyt c oxidoreductase activity does not decrease in the presence of any of these cations. However, succinate-cyt c oxidoreductase activity decreases in the presence of NaCl. This simple experiment highlights: 1) the effect of Na+ in decreasing IMM fluidity and CoQ transfer; 2) that supercomplex I+III2 protects ubiquinone (CoQ) transfer from being affected by lowering IMM fluidity; 3) that CoQ transfer between CI and CIII is functionally different from CoQ transfer between CII and CIII. These facts support the existence of functionally differentiated CoQ pools in the IMM and show that they can be regulated by the changing Na+ environment of mitochondria.

DOI: https://doi.org/10.3791/63729
Nat Commun. 2022 Aug 08. 13(1): 4633

Blocking ActRIIB and restoring appetite reverses cachexia and improves survival in mice with lung cancer.

Andre Lima Queiroz, Ezequiel Dantas, Shakti Ramsamooj, Anirudh Murthy, Mujmmail Ahmed, Elizabeth R M Zunica, Roger J Liang, Jessica Murphy, Corey D Holman, Curtis J Bare, Gregory Ghahramani, Zhidan Wu, David E Cohen, John P Kirwan, Lewis C Cantley, Christopher L Axelrod, Marcus D Goncalves.

Cancer cachexia is a common, debilitating condition with limited therapeutic options. Using an established mouse model of lung cancer, we find that cachexia is characterized by reduced food intake, spontaneous activity, and energy expenditure accompanied by muscle metabolic dysfunction and atrophy. We identify Activin A as a purported driver of cachexia and treat with ActRIIB-Fc, a decoy ligand for TGF-β/activin family members, together with anamorelin (Ana), a ghrelin receptor agonist, to reverse muscle dysfunction and anorexia, respectively. Ana effectively increases food intake but only the combination of drugs increases lean mass, restores spontaneous activity, and improves overall survival. These beneficial effects are limited to female mice and are dependent on ovarian function. In agreement, high expression of Activin A in human lung adenocarcinoma correlates with unfavorable prognosis only in female patients, despite similar expression levels in both sexes. This study suggests that multimodal, sex-specific, therapies are needed to reverse cachexia.

DOI: https://doi.org/10.1038/s41467-022-32135-0
Cancers (Basel). 2022 Aug 02. pii: 3769. [Epub ahead of print]14(15):

Refining the Role of Pyruvate Dehydrogenase Kinases in Glioblastoma Development.

Claire M Larrieu, Simon Storevik, Joris Guyon, Antonio C Pagano Zottola, Cyrielle L Bouchez, Marie-Alix Derieppe, Tuan Zea Tan, Hrvoje Miletic, James Lorens, Karl Johan Tronstad, Thomas Daubon, Gro Vatne Røsland.

  Glioblastoma (GB) are the most frequent brain cancers. Aggressive growth and limited treatment options induce a median survival of 12-15 months. In addition to highly proliferative and invasive properties, GB cells show cancer-associated metabolic characteristics such as increased aerobic glycolysis. Pyruvate dehydrogenase (PDH) is a key enzyme complex at the crossroads between lactic fermentation and oxidative pathways, finely regulated by PDH kinases (PDHKs). PDHKs are often overexpressed in cancer cells to facilitate high glycolytic flux. We hypothesized that targeting PDHKs, by disturbing cancer metabolic homeostasis, would alter GB progression and render cells vulnerable to additional cancer treatment. Using patient databases, distinct expression patterns of PDHK1 and PDHK2 in GB tissues were obvious. To disturb protumoral glycolysis, we modulated PDH activity through the genetic or pharmacological inhibition of PDHK in patient-derived stem-like spheroids. Striking effects of PDHKs inhibition using dichloroacetate were observed in vitro on cell morphology and metabolism, resulting in increased intracellular ROS levels and decreased proliferation and invasion. In vivo findings confirmed a reduction in tumor size and better survival of mice implanted with PDHK1 and PDHK2 knockout cells. Adding a radiotherapeutic protocol further resulted in a reduction in tumor size and improved mouse survival in our model.

Keywords:  DCA; glioblastoma; invasion; lactate; pyruvate dehydrogenase kinases

DOI:  https://doi.org/10.3390/cancers14153769
J Exp Clin Cancer Res. 2022 Aug 11. 41(1): 243

Mitochondrial ROS drive resistance to chemotherapy and immune-killing in hypoxic non-small cell lung cancer.

Iris C Salaroglio, Dimas Carolina Belisario, Muhlis Akman, Sofia La Vecchia, Martina Godel, Dario Pasquale Anobile, Giacomo Ortone, Sabrina Digiovanni, Simona Fontana, Costanzo Costamagna, Menachem Rubinstein, Joanna Kopecka, Chiara Riganti.

  BACKGROUND: Solid tumors subjected to intermittent hypoxia are characterized by resistance to chemotherapy and immune-killing by effector T-lymphocytes, particularly tumor-infiltrating Vγ9Vδ2 T-lymphocytes. The molecular circuitries determining this double resistance are not known.METHODS: We analyzed a panel of 28 human non-small cell lung cancer (NSCLC) lines, using an in vitro system simulating continuous and intermittent hypoxia. Chemosensitivity to cisplatin and docetaxel was evaluated by chemiluminescence, ex vivo Vγ9Vδ2 T-lymphocyte expansion and immune-killing by flow cytometry. Targeted transcriptomics identified efflux transporters and nuclear factors involved in this chemo-immuno-resistance. The molecular mechanism linking Hypoxia-inducible factor-1α (HIF-1α), CCAAT/Enhancer Binding Protein-β (C/EBP-β) isoforms LAP and LIP, ABCB1, ABCC1 and ABCA1 transporters were evaluated by immunoblotting, RT-PCR, RNA-IP, ChIP. Oxidative phosphorylation, mitochondrial ATP, ROS, depolarization, O2 consumption were monitored by spectrophotometer and electronic sensors. The role of ROS/HIF-1α/LAP axis was validated in knocked-out or overexpressing cells, and in humanized (Hu-CD34+NSG) mice bearing LAP-overexpressing tumors. The clinical meaning of LAP was assessed in 60 NSCLC patients prospectively enrolled, treated with chemotherapy.
RESULTS: By up-regulating ABCB1 and ABCC1, and down-regulating ABCA1, intermittent hypoxia induced a stronger chemo-immuno-resistance than continuous hypoxia in NSCLC cells. Intermittent hypoxia impaired the electron transport chain and reduced O2 consumption, increasing mitochondrial ROS that favor the stabilization of C/EBP-β mRNA mediated by HIF-1α. HIF-1α/C/EBP-β mRNA binding increases the splicing of C/EBP-β toward the production of LAP isoform that transcriptionally induces ABCB1 and ABCC1, promoting the efflux of cisplatin and docetaxel. LAP also decreases ABCA1, limiting the efflux of isopentenyl pyrophosphate, i.e. the endogenous activator of Vγ9Vδ2 T-cells, and reducing the immune-killing. In NSCLC patients subjected to cisplatin-based chemotherapy, C/EBP-β LAP was abundant in hypoxic tumors and was associated with lower response to treatment and survival. LAP-overexpressing tumors in Hu-CD34+NSG mice recapitulated the patients' chemo-immuno-resistant phenotype. Interestingly, the ROS scavenger mitoquinol chemo-immuno-sensitized immuno-xenografts, by disrupting the ROS/HIF-1α/LAP cascade.
CONCLUSIONS: The impairment of mitochondrial metabolism induced by intermittent hypoxia increases the ROS-dependent stabilization of HIF-1α/LAP complex in NSCLC, producing chemo-immuno-resistance. Clinically used mitochondrial ROS scavengers may counteract such double resistance. Moreover, we suggest C/EBP-β LAP as a new predictive and prognostic factor in NSCLC patients.

Keywords:  CCAAT/enhancer binding protein-β; Chemo-immuno-resistance; Intermittent hypoxia; Mitochondrial ROS; Non-small cell lung cancer

DOI:  https://doi.org/10.1186/s13046-022-02447-6
Mol Cell. 2022 Aug 09. pii: S1097-2765(22)00708-0. [Epub ahead of print]

Stressed to death: Mitochondrial stress responses connect respiration and apoptosis in cancer.

Jacob M Winter, Tarun Yadav, Jared Rutter.

  Mitochondrial energetics and respiration have emerged as important factors in how cancer cells respond to or evade apoptotic signals. The study of the functional connection between these two processes may provide insight into following questions old and new: how might we target respiration or downstream signaling pathways to amplify apoptotic stress in the context of cancer therapy? Why are respiration and apoptotic regulation housed in the same organelle? Here, we briefly review mitochondrial respiration and apoptosis and then focus on how the intersection of these two processes is regulated by cytoplasmic signaling pathways such as the integrated stress response.

Keywords:  CRISPR; apoptosis; cancer; electron transport chain; integrated stress response; leukemia; mitochondria; oncology; oxidative phosphorylation; respiration; stress; venetoclax

DOI:  https://doi.org/10.1016/j.molcel.2022.07.012
Front Oncol. 2022 ;12 903033

Metabolic Reprogramming Helps to Define Different Metastatic Tropisms in Colorectal Cancer.

Ana Montero-Calle, Marta Gómez de Cedrón, Adriana Quijada-Freire, Guillermo Solís-Fernández, Victoria López-Alonso, Isabel Espinosa-Salinas, Alberto Peláez-García, María Jesús Fernández-Aceñero, Ana Ramírez de Molina, Rodrigo Barderas.

  Approximately 25% of colorectal cancer (CRC) patients experience systemic metastases, with the most frequent target organs being the liver and lung. Metabolic reprogramming has been recognized as one of the hallmarks of cancer. Here, metabolic and functional differences between two CRC cells with different metastatic organotropisms (metastatic KM12SM CRC cells to the liver and KM12L4a to the lung when injected in the spleen and in the tail vein of mice) were analysed in comparison to their parental non-metastatic isogenic KM12C cells, for a subsequent investigation of identified metabolic targets in CRC patients. Meta-analysis from proteomic and transcriptomic data deposited in databases, qPCR, WB, in vitro cell-based assays, and in vivo experiments were used to survey for metabolic alterations contributing to their different organotropism and for the subsequent analysis of identified metabolic markers in CRC patients. Although no changes in cell proliferation were observed between metastatic cells, KM12SM cells were highly dependent on oxidative phosphorylation at mitochondria, whereas KM12L4a cells were characterized by being more energetically efficient with lower basal respiration levels and a better redox management. Lipid metabolism-related targets were found altered in both cell lines, including LDLR, CD36, FABP4, SCD, AGPAT1, and FASN, which were also associated with the prognosis of CRC patients. Moreover, CD36 association with lung metastatic tropism of CRC cells was validated in vivo. Altogether, our results suggest that LDLR, CD36, FABP4, SCD, FASN, LPL, and APOA1 metabolic targets are associated with CRC metastatic tropism to the liver or lung. These features exemplify specific metabolic adaptations for invasive cancer cells which stem at the primary tumour.

Keywords:  CRC (colorectal cancer); fatty acids (FA); metabolic reprograming; obesity; organotropism; tropism of metastasis

DOI:  https://doi.org/10.3389/fonc.2022.903033
Front Oncol. 2022 ;12 955892

The metabolic addiction of cancer stem cells.

Om Saswat Sahoo, Karthikeyan Pethusamy, Tryambak P Srivastava, Joyeeta Talukdar, Mohammed S Alqahtani, Mohamed Abbas, Ruby Dhar, Subhradip Karmakar.

  Cancer stem cells (CSC) are the minor population of cancer originating cells that have the capacity of self-renewal, differentiation, and tumorigenicity (when transplanted into an immunocompromised animal). These low-copy number cell populations are believed to be resistant to conventional chemo and radiotherapy. It was reported that metabolic adaptation of these elusive cell populations is to a large extent responsible for their survival and distant metastasis. Warburg effect is a hallmark of most cancer in which the cancer cells prefer to metabolize glucose anaerobically, even under normoxic conditions. Warburg's aerobic glycolysis produces ATP efficiently promoting cell proliferation by reprogramming metabolism to increase glucose uptake and stimulating lactate production. This metabolic adaptation also seems to contribute to chemoresistance and immune evasion, a prerequisite for cancer cell survival and proliferation. Though we know a lot about metabolic fine-tuning in cancer, what is still in shadow is the identity of upstream regulators that orchestrates this process. Epigenetic modification of key metabolic enzymes seems to play a decisive role in this. By altering the metabolic flux, cancer cells polarize the biochemical reactions to selectively generate "onco-metabolites" that provide an added advantage for cell proliferation and survival. In this review, we explored the metabolic-epigenetic circuity in relation to cancer growth and proliferation and establish the fact how cancer cells may be addicted to specific metabolic pathways to meet their needs. Interestingly, even the immune system is re-calibrated to adapt to this altered scenario. Knowing the details is crucial for selective targeting of cancer stem cells by choking the rate-limiting stems and crucial branch points, preventing the formation of onco-metabolites.

Keywords:  cancer stem cells; cross talks; epigenetics; metabolism; oncometabolites

DOI:  https://doi.org/10.3389/fonc.2022.955892
Cell Rep. 2022 Aug 09. pii: S2211-1247(22)00990-1. [Epub ahead of print]40(6): 111177

Phosphoproteomics of primary AML patient samples reveals rationale for AKT combination therapy and p53 context to overcome selinexor resistance.

Kristina B Emdal, Nicolàs Palacio-Escat, Caroline Wigerup, Akihiro Eguchi, Helén Nilsson, Dorte B Bekker-Jensen, Lars Rönnstrand, Julhash U Kazi, Alexandre Puissant, Raphaël Itzykson, Julio Saez-Rodriguez, Kristina Masson, Peter Blume-Jensen, Jesper V Olsen.

  Acute myeloid leukemia (AML) is a heterogeneous disease with variable patient responses to therapy. Selinexor, an inhibitor of nuclear export, has shown promising clinical activity for AML. To identify the molecular context for monotherapy sensitivity as well as rational drug combinations, we profile selinexor signaling responses using phosphoproteomics in primary AML patient samples and cell lines. Functional phosphosite scoring reveals that p53 function is required for selinexor sensitivity consistent with enhanced efficacy of selinexor in combination with the MDM2 inhibitor nutlin-3a. Moreover, combining selinexor with the AKT inhibitor MK-2206 overcomes dysregulated AKT-FOXO3 signaling in resistant cells, resulting in synergistic anti-proliferative effects. Using high-throughput spatial proteomics to profile subcellular compartments, we measure global proteome and phospho-proteome dynamics, providing direct evidence of nuclear translocation of FOXO3 upon combination treatment. Our data demonstrate the potential of phosphoproteomics and functional phosphorylation site scoring to successfully pinpoint key targetable signaling hubs for rational drug combinations.

Keywords:  CP: Cancer; CP: Molecular biology; MK-2206; acute myeloid leukemia; combination therapy; drug resistance; functional scoring; mass spectrometry; nutlin-3a; phosphoproteomics; selinexor; subcellular proteomics

DOI:  https://doi.org/10.1016/j.celrep.2022.111177
Front Immunol. 2022 ;13 911050

Age-related increase of mitochondrial content in human memory CD4+ T cells contributes to ROS-mediated increased expression of proinflammatory cytokines.

Yuling Chen, Yuanchun Ye, Pierre-Louis Krauß, Pelle Löwe, Moritz Pfeiffenberger, Alexandra Damerau, Lisa Ehlers, Thomas Buttgereit, Paula Hoff, Frank Buttgereit, Timo Gaber.

  Cellular metabolism modulates effector functions in human CD4+ T (Th) cells by providing energy and building blocks. Conversely, cellular metabolic responses are modulated by various influences, e.g., age. Thus, we hypothesized that metabolic reprogramming in human Th cells during aging modulates effector functions and contributes to "inflammaging", an aging-related, chronic, sterile, low-grade inflammatory state characterized by specific proinflammatory cytokines. Analyzing the metabolic response of human naive and memory Th cells from young and aged individuals, we observed that memory Th cells exhibit higher glycolytic and mitochondrial fluxes than naive Th cells. In contrast, the metabolism of the latter was not affected by donor age. Memory Th cells from aged donors showed a higher respiratory capacity, mitochondrial content, and intracellular ROS production than those from young donors without altering glucose uptake and cellular ATP levels, which finally resulted in higher secreted amounts of proinflammatory cytokines, e.g., IFN-γ, IP-10 from memory Th cells taken from aged donors after TCR-stimulation which were sensitive to ROS inhibition. These findings suggest that metabolic reprogramming in human memory Th cells during aging results in an increased expression of proinflammatory cytokines through enhanced ROS production, which may contribute to the pathogenesis of inflammaging.

Keywords:  ROS; aging; cytokines; memory Th cells; metabolism; proliferation

DOI:  https://doi.org/10.3389/fimmu.2022.911050
Dis Markers. 2022 ;2022 5946110

Pan-Cancer Analysis of Voltage-Dependent Anion Channel (VDAC1) as a Cancer Therapeutic Target or Diagnostic Biomarker.

Zhitong Wang, Yinchu Cheng, Zaiwei Song, Rongsheng Zhao.

The voltage-dependent anion channel 1 (VDAC1), a pore protein located in the outer mitochondrial membrane, has been confirmed to be related to cancer in cell or animal evidence. However, there is no available pan-cancer analysis of VDAC1. Herein, we investigated the potential roles of VDAC1 in tumorigenesis and progression based on the Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), and Clinical Proteomic Tumor Analysis Consortium (CPTAC) datasets. The expression of VDAC1 increased in most cancers, and the upregulation of VDAC1 distinctly correlated with the poor prognosis in patients, including breast invasive carcinoma, cervical squamous cell carcinoma, pancreatic adenocarcinoma, lung adenocarcinoma, and skin cutaneous melanoma. We also found VDAC1 S104 phosphorylation raised in various cancers, such as breast cancer, colon cancer, and lung adenocarcinoma. Moreover, the expression of VDAC1 was related to the estimated infiltration value of cancer-associated fibroblasts in bladder urothelial carcinoma, colon adenocarcinoma, kidney renal papillary cell carcinoma, and testicular germ cell tumors. At last, we showed that VDAC1-related oxidative phosphorylation and metabolic regulation may partially explain its association with tumorigenesis and progression. Taken together, this pan-cancer analysis provides relatively comprehensive information on the potential value of VDAC1 as a prognostic biomarker and therapeutic target.

DOI: https://doi.org/10.1155/2022/5946110
Mol Metab. 2022 Aug 06. pii: S2212-8778(22)00131-4. [Epub ahead of print] 101562

The Mitochondrial NAD Kinase Functions as a Major Metabolic Regulator Upon Increased Energy Demand.

Hyunbae Kim, Zhiyao Fu, Zhao Yang, Zhenfeng Song, El Hussain Shamsa, Thangal Yumnamcha, Shengyi Sun, Wanqing Liu, Ahmed S Ibrahim, Nathan R Qi, Ren Zhang, Kezhong Zhang.

The mitochondrial nicotinamide adenine dinucleotide (NAD) kinase (MNADK) mediates de novo mitochondrial NADP biosynthesis by catalyzing the phosphorylation of NAD to yield NADP. In this study, we investigated the function and mechanistic basis by which MNADK regulates metabolic homeostasis. Generalized gene-set analysis by aggregating human patient genomic databases indicated that human MNADK common gene variants or decreased expression of the gene are significantly associated with the occurrence of type-2 diabetes, non-alcoholic fatty liver disease (NAFLD), or hepatocellular carcinoma (HCC). Ablation of the MNADK gene in mice led to decreased fat oxidation, coincident with increased respiratory exchange ratio (RER) and decreased energy expenditure upon energy demand triggered by endurance exercise or fasting. On an atherogenic high-fat diet (HFD), MNADK-null mice exhibited hepatic insulin resistance and glucose intolerance, indicating a type-2 diabetes-like phenotype in the absence of MNADK. Further investigation revealed that MNADK deficiency led to a decrease in mitochondrial NADP(H) but an increase in cellular reactive oxygen species (ROS) in mouse livers. Consistently, protein levels of the major metabolic regulators or enzymes were decreased, while their acetylation modifications were increased in the livers of MNADK-null mice. Further, feeding mice with a HFD caused S-nitrosylation (SNO) modification, a posttranslational modification that represses protein activities, on MNADK protein in the liver. Reconstitution of an SNO-resistant MNADK variant, MNADK-S193, into MNADK-null mice mitigated hepatic steatosis induced by HFD. In summary, our studies define that MNADK, the only known mammalian mitochondrial NAD kinase, plays important roles in preserving energy homeostasis to mitigate the risk of metabolic disorders.

DOI: https://doi.org/10.1016/j.molmet.2022.101562
Cells. 2022 Jul 30. pii: 2353. [Epub ahead of print]11(15):

Mutated FANCA Gene Role in the Modulation of Energy Metabolism and Mitochondrial Dynamics in Head and Neck Squamous Cell Carcinoma.

Nadia Bertola, Paolo Degan, Enrico Cappelli, Silvia Ravera.

  Fanconi Anaemia (FA) is a rare recessive genetic disorder characterized by a defective DNA repair mechanism. Although aplastic anaemia is the principal clinical sign in FA, patients develop a head and neck squamous cell carcinoma (HNSCC) with a frequency 500-700 folds higher than the general population, which appears more aggressive, with survival of under two years. Since FA gene mutations are also associated with a defect in the aerobic metabolism and an increased oxidative stress accumulation, this work aims to evaluate the effect of FANCA mutation on the energy metabolism and the relative mitochondrial quality control pathways in an HNSCC cellular model. Energy metabolism and cellular antioxidant capacities were evaluated by oximetric, luminometric, and spectrophotometric assays. The dynamics of the mitochondrial network, the quality of mitophagy and autophagy, and DNA double-strand damage were analysed by Western blot analysis. Data show that the HNSCC cellular model carrying the FANCA gene mutation displays an altered electron transport between respiratory Complexes I and III that does not depend on the OxPhos protein expression. Moreover, FANCA HNSCC cells show an imbalance between fusion and fission processes and alterations in autophagy and mitophagy pathways. Together, all these alterations associated with the FANCA gene mutation cause cellular energy depletion and a metabolic switch to glycolysis, exacerbating the Warburg effect in HNSCC cells and increasing the growth rate. In addition, the altered DNA repair due to the FANCA mutation causes a higher accumulation of DNA damage in the HNSCC cellular model. In conclusion, changes in energy metabolism and mitochondrial dynamics could explain the strict correlation between HNSCC and FA genes, helping to identify new therapeutic targets.

Keywords:  Fanconi Anaemia; HNSCC; anaerobic glycolysis; antioxidant defences; autophagy; double-strand DNA damage; mitochondrial fusion and fission; mitophagy; oxidative phosphorylation; oxidative stress

DOI:  https://doi.org/10.3390/cells11152353
Biochimie. 2022 Aug 08. pii: S0300-9084(22)00192-4. [Epub ahead of print]

Inhibition of LPAR6 overcomes sorafenib resistance by switching glycolysis into oxidative phosphorylation in hepatocellular carcinoma.

Davide Gnocchi, Agata Kurzyk, Antonella Mintrone, Giovanni Lentini, Carlo Sabbà, Antonio Mazzocca.

  Hepatocellular carcinoma (HCC) is one of the most threatening tumours in the world today. Pharmacological treatments for HCC mainly rely on protein kinase inhibitors, such as sorafenib and regorafenib. Even so, these approaches exhibit side effects and acquired drug resistance, which is an obstacle to HCC treatment. We have previously shown that selective lysophosphatidic acid receptor 6 (LPAR6) chemical antagonists inhibit HCC growth. Here, we investigated whether LPAR6 mediates resistance to sorafenib by affecting energy metabolism in HCC. To uncover the role of LPAR6 in drug resistance and cancer energy metabolism, we utilized gain-of-function and loss-of-function in vitro models in 2D tissue culture and 3D spheroids. LPAR6 was ectopically expressed in HLE cells (HLE-LPAR6) and knocked down in HepG2 (HepG2 LPAR6-shRNA). Measurements of oxygen consumption and lactate and pyruvate production were performed to assess the energy metabolism response of HCC cells to sorafenib treatment. We found that LPAR6 mediates the resistance of HCC cells to sorafenib by promoting lactic acid fermentation at the expense of oxidative phosphorylation (OXPHOS) and that the selective LPAR6 antagonist 9-xanthenyl acetate (XAA) can effectively overcome this resistance. Our study shows for the first time that an LPAR6-mediated metabolic mechanism supports sorafenib resistance in HCC and proposes a pharmacological approach to overcome it.

Keywords:  Energy metabolism; Hepatocellular carcinoma (HCC); Lysophosphatidic acid receptor 6 (LPAR6); Oxidative phosphorylation (OXPHOS); Sorafenib resistance

DOI:  https://doi.org/10.1016/j.biochi.2022.07.016
Mol Metab. 2022 Aug 06. pii: S2212-8778(22)00132-6. [Epub ahead of print] 101563

Impact of metabolic stress induced by diets, aging and fasting on tissue oxygen consumption.

Olena Mackert, Eva Katrin Wirth, Rongwan Sun, Jennifer Winkler, Aoxue Liu, Kostja Renko, Séverine Kunz, Joachim Spranger, Sebastian Brachs.

  OBJECTIVE: Alterations in mitochondrial function play an important role in the development of various diseases, such as obesity, insulin resistance, steatohepatitis, atherosclerosis and cancer. However, accurate assessment of mitochondrial respiration ex vivo is limited and remains highly challenging. Using our novel method, we measured mitochondrial oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) of metabolically relevant tissues ex vivo to investigate the impact of different metabolic stressors on mitochondrial function.METHODS: Comparative analysis of OCR and ECAR in young mice fed either 12 weeks high-fat (HFD), high-sucrose (HSD), or western diet (WD), a HFD in matured mice, 2 years prolonged aging on standard-control diet (STD), as well as fasting in tissue biopsies.
RESULTS: While diets had only marginal effects on mitochondrial respiration, respiratory chain complexes II and IV were reduced. Moreover, matured HFD-fed mice showed a decreased hepatic metabolic flexibility and prolonged aging increased OCR in brown adipose tissue. Interestingly, fasting boosted pancreatic and hepatic OCR while decreasing weight of those organs. Furthermore, ECAR measurements in adipose tissue could indicate its lipolytic capacity.
CONCLUSION: Using ex vivo tissue measurements, we could extensively analyze mitochondrial function of liver, adipose tissue, pancreas and heart revealing effects of metabolic stress, especially aging.

Keywords:  age; diet; fasting; metabolic stress; mitochondrial respiration; oxygen consumption rate

DOI:  https://doi.org/10.1016/j.molmet.2022.101563
Am J Pathol. 2022 Aug 07. pii: S0002-9440(22)00214-0. [Epub ahead of print]

Impaired mitochondria promote aging-associated sebaceous gland dysfunction and pathology.

Noha S Ahmed, Jeremy B Foote, Keshav K Singh.

  Mitochondrial dysfunction is one of the hallmarks of aging. Changes in sebaceous gland function and sebum production have been reported during aging. Here we report the direct effects of mitochondrial dysfunction on sebaceous gland morphology and function. We utilized a mitochondrial DNA depleter mouse as a model for introducing mitochondrial dysfunction in the whole animal. We characterized the effects on skin sebaceous glands and modified sebaceous glands of the eyelid, lip, clitoral and preputial glands. The mtDNA depleter mice show gross morphologic and histopathologic changes in sebaceous glands associated with increased infiltration by mast cells, neutrophils, and polarized macrophages. Consistently, there was increased expression of proinflammatory cytokines. The inflammatory changes were associated with abnormal sebocyte accumulation of lipid, defective sebum delivery at the skin surface, and the upregulation of key lipogenesis regulating genes and androgen receptor. The mitochondrial DNA depleter mice expressed aging-associated senescent marker. We also observed increased sebocyte proliferation and aberrant expression of stem cell markers. These studies provide for the first time a causal link between mitochondrial dysfunction and abnormal sebocyte function within sebaceous and modified sebaceous glands throughout the whole body of the animal. Our studies suggest that mitochondrial DNA depleter mouse may serve as a novel tool to develop targeted therapeutics to address sebaceous gland disorders in aging humans.

Keywords:  Aging; Inflammation; Mitochondrial DNA; Mitochondrial dysfunction; Modified sebaceous glands; Sebaceous glands

DOI:  https://doi.org/10.1016/j.ajpath.2022.07.006
Nat Commun. 2022 Aug 09. 13(1): 4674

MYC sensitises cells to apoptosis by driving energetic demand.

Joy Edwards-Hicks, Huizhong Su, Maurizio Mangolini, Kubra K Yoneten, Jimi Wills, Giovanny Rodriguez-Blanco, Christine Young, Kevin Cho, Heather Barker, Morwenna Muir, Ania Naila Guerrieri, Xue-Feng Li, Rachel White, Piotr Manasterski, Elena Mandrou, Karen Wills, Jingyu Chen, Emily Abraham, Kianoosh Sateri, Bin-Zhi Qian, Peter Bankhead, Mark Arends, Noor Gammoh, Alex von Kriegsheim, Gary J Patti, Andrew H Sims, Juan Carlos Acosta, Valerie Brunton, Kamil R Kranc, Maria Christophorou, Erika L Pearce, Ingo Ringshausen, Andrew J Finch.

The MYC oncogene is a potent driver of growth and proliferation but also sensitises cells to apoptosis, which limits its oncogenic potential. MYC induces several biosynthetic programmes and primary cells overexpressing MYC are highly sensitive to glutamine withdrawal suggesting that MYC-induced sensitisation to apoptosis may be due to imbalance of metabolic/energetic supply and demand. Here we show that MYC elevates global transcription and translation, even in the absence of glutamine, revealing metabolic demand without corresponding supply. Glutamine withdrawal from MRC-5 fibroblasts depletes key tricarboxylic acid (TCA) cycle metabolites and, in combination with MYC activation, leads to AMP accumulation and nucleotide catabolism indicative of energetic stress. Further analyses reveal that glutamine supports viability through TCA cycle energetics rather than asparagine biosynthesis and that TCA cycle inhibition confers tumour suppression on MYC-driven lymphoma in vivo. In summary, glutamine supports the viability of MYC-overexpressing cells through an energetic rather than a biosynthetic mechanism.

DOI: https://doi.org/10.1038/s41467-022-32368-z
Geroscience. 2022 Aug 10.

High-throughput sequencing analysis of nuclear-encoded mitochondrial genes reveals a genetic signature of human longevity.

Brenda Gonzalez, Archana Tare, Seungjin Ryu, Simon C Johnson, Gil Atzmon, Nir Barzilai, Matt Kaeberlein, Yousin Suh.

  Mitochondrial dysfunction is a well-known contributor to aging and age-related diseases. The precise mechanisms through which mitochondria impact human lifespan, however, remain unclear. We hypothesize that humans with exceptional longevity harbor rare variants in nuclear-encoded mitochondrial genes (mitonuclear genes) that confer resistance against age-related mitochondrial dysfunction. Here we report an integrated functional genomics study to identify rare functional variants in ~ 660 mitonuclear candidate genes discovered by target capture sequencing analysis of 496 centenarians and 572 controls of Ashkenazi Jewish descent. We identify and prioritize longevity-associated variants, genes, and mitochondrial pathways that are enriched with rare variants. We provide functional gene variants such as those in MTOR (Y2396Lfs*29), CPS1 (T1406N), and MFN2 (G548*) as well as LRPPRC (S1378G) that is predicted to affect mitochondrial translation. Taken together, our results suggest a functional role for specific mitonuclear genes and pathways in human longevity.

Keywords:  Aging; Centenarian; Genetic variant; Longevity; Mitochondria

DOI:  https://doi.org/10.1007/s11357-022-00634-z
Front Cell Dev Biol. 2022 ;10 915785

Cold atmospheric plasma induces apoptosis in human colon and lung cancer cells through modulating mitochondrial pathway.

Yanhong Wang, Xinyu Mang, Xuran Li, Zhengyu Cai, Fei Tan.

  Cold atmospheric plasma (CAP) is an emerging and promising oncotherapy with considerable potential and advantages that traditional treatment modalities lack. The objective of this study was to investigate the effect and mechanism of plasma-inhibited proliferation and plasma-induced apoptosis on human lung cancer and colon cancer cells in vitro and in vivo. Piezobrush® PZ2, a handheld CAP unit based on the piezoelectric direct discharge technology, was used to generate and deliver non-thermal plasma. Firstly, CAPPZ2 treatment inhibited the proliferation of HT29 colorectal cancer cells and A549 lung cancer cells using CCK8 assay, caused morphological changes at the cellular and subcellular levels using transmission electron microscopy, and suppressed both types of tumor cell migration and invasion using the Transwell migration and Matrigel invasion assay. Secondly, we confirmed plasma-induced apoptosis in the HT29 and A549 cells using the AO/EB staining coupled with flow cytometry, and verified the production of apoptosis-related proteins, such as cytochrome c, PARP, cleaved caspase-3 and caspase-9, Bcl-2 and Bax, using western blotting. Finally, the aforementioned in vitro results were tested in vivo using cell-derived xenograft mouse models, and the anticancer effect was confirmed and attributed to CAP-mediated apoptosis. The immunohistochemical analysis revealed that the expression of cleaved caspase-9, caspase-3, PARP and Bax were upregulated whereas that of Bcl-2 downregulated after CAP treatment. These findings collectively suggest that the activation of the mitochondrial pathway is involved during CAPPZ2-induced apoptosis of human colon and lung cancer cells in vitro and in vivo.

Keywords:  apoptosis; caspase; cold atmospheric plasma; mitochondria; reactive oxygen species

DOI:  https://doi.org/10.3389/fcell.2022.915785
Transl Lung Cancer Res. 2022 Jul;11(7): 1268-1278

Peripheral blood leukocyte mitochondrial DNA content and risk of lung cancer.

Gregory T Kennedy, Nandita Mitra, Trevor M Penning, Alexander S Whitehead, Anil Vachani.

  Background: Previous studies of peripheral blood leukocyte mitochondrial DNA (mtDNA) content and risk of lung cancer have yielded inconsistent results, and no studies have evaluated the association between mtDNA content and post-resection lung cancer outcomes.Methods: Using a case-control study design, we evaluated the association between mtDNA content and risk of lung cancer in 465 cases and 378 controls. We also evaluated the association between mtDNA content and survival in 189 cases with surgically resected non-small cell lung cancer (NSCLC). Relative mtDNA content was measured using a quantitative real-time polymerase chain reaction (PCR) assay in peripheral blood genomic DNA. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) using multivariable logistic regression, adjusting for age, gender, race, and smoking history.
Results: mtDNA content was lower in cases compared to controls, with medians of 1.26 [interquartile range (IQR), 0.98-1.70)] and 1.79 (IQR, 1.34-2.10; P<0.001), respectively. Compared to the quartile of subjects with the highest mtDNA content, there was significantly higher likelihood of lung cancer in the second lowest quartile (OR 3.44; 95% CI: 2.06-5.75) and the lowest quartile (OR 6.36; 95% CI: 3.86-10.47). In patients with resected NSCLC, there was no association between lower mtDNA content and recurrence-free survival (RFS) [hazard ratio (HR) 0.89; 95% CI: 0.47-1.66] or overall survival (OS) (HR 0.71; 95% CI: 0.35-1.46).
Conclusions: Thus, our results counter previous studies and find that lower mtDNA content is associated with lung cancer risk. Our results suggest that mtDNA content could potentially serve as a risk biomarker, but is not associated with survival outcomes in NSCLC.

Keywords:  Lung cancer; mitochondrial DNA (mtDNA); risk biomarker

DOI:  https://doi.org/10.21037/tlcr-21-979
World J Gastrointest Oncol. 2022 Jun 15. 14(6): 1124-1140

Glutamine deprivation impairs function of infiltrating CD8+ T cells in hepatocellular carcinoma by inducing mitochondrial damage and apoptosis.

Wei Wang, Meng-Nan Guo, Ning Li, De-Quan Pang, Jing-Hua Wu.

  BACKGROUND: The functions of infiltrating CD8+ T cells are often impaired due to tumor cells causing nutrient deprivation in the tumor microenvironment. Thus, the mechanisms of CD8+ T cell dysfunction have become a hot research topic, and there is increased interest on how changes in metabolomics correlate with CD8+ T cell dysfunction.AIM: To investigate whether and how glutamine metabolism affects the function of infiltrating CD8+ T cells in hepatocellular carcinoma.
METHODS: Immunohistochemical staining and immunofluorescence were performed on surgically resected liver tissues from patients. Differentially expressed genes in infiltrating CD8+ T cells in hepatocellular carcinoma were detected using RNA sequencing. Activated CD8+ T cells were co-cultured with Huh-7 cells for 3 d. The function and mitochondrial status of CD8+ T cells were analyzed by flow cytometry, quantitative real-time polymerase chain reaction, and transmission electron microscopy. Next, CD8+ T cells were treated with the mitochondrial protective and damaging agents. Functional alterations in CD8+ T cells were detected by flow cytometry. Then, complete medium without glutamine was used to culture cells and their functional changes and mitochondrial status were detected.
RESULTS: There were a large number of infiltrating PD-1+CD8+ T cells in liver cancer tissues. Next, we co-cultured CD8+ T cells and Huh-7 cells to explore the regulatory effect of hepatoma cells on CD8+ T cells. Flow cytometry results revealed increased PD-1 expression and decreased secretion of perforin (PRF1) and granzyme B (GZMB) by CD8+ T cells in the co-culture group. Meanwhile, JC-1 staining was decreased and the levels of reactive oxygen species and apoptosis were increased in CD8+ T cells of the co-culture group; additionally, the mitochondria of these cells were swollen. When CD8+ T cells were treated with the mitochondrial protective and damaging agents, their function was restored and inhibited, respectively, through the mitochondrial damage and apoptotic pathways. Subsequently, complete medium without glutamine was used to culture cells. As expected, CD8+ T cells showed functional downregulation, mitochondrial damage, and apoptosis.
CONCLUSION: Glutamine deprivation impairs the function of infiltrating CD8+ T cells in hepatocellular carcinoma through the mitochondrial damage and apoptotic pathways.

Keywords:  CD8+ T cells; Glutamine; Hepatocellular carcinoma; Mitochondrial damage; T cell function

DOI:  https://doi.org/10.4251/wjgo.v14.i6.1124
JCI Insight. 2022 Aug 09. pii: e153836. [Epub ahead of print]

DHODH is an independent prognostic marker and potent therapeutic target in neuroblastoma.

Thale Kristin Olsen, Cecilia Dyberg, Bethel Tesfai Embaie, Adele M Alchahin, Jelena Milosevic, Jane Ding, Jörg Otte, Conny Tümmler, Ida Hed Myrberg, Ellen M Westerhout, Jan Koster, Rogier Versteeg, Han-Fei Ding, Per Kogner, John Inge Johnsen, David B Sykes, Ninib Baryawno.

  Despite intensive therapy, children with high-risk neuroblastoma are at risk of treatment failure. We applied a multi-omic system approach to evaluate metabolic vulnerabilities in human neuroblastoma. We combined metabolomics, CRISPR screening and transcriptomic data across >700 solid tumor cell lines and identified dihydroorotate dehydrogenase (DHODH), a critical enzyme in pyrimidine synthesis, as a potential treatment target. Of note, DHODH inhibition is currently under clinical investigation in patients with hematologic malignancies. In neuroblastoma, DHODH expression was identified as an independent risk factor for aggressive disease, and high DHODH levels correlated to worse overall and event-free survival. A subset of tumors with the highest DHODH expression was associated with a dismal prognosis, with a 5-year survival of <10%. In xenograft and transgenic neuroblastoma mouse models treated with the DHODH inhibitor brequinar, tumor growth was dramatically reduced, and survival was extended. Furthermore, brequinar treatment was shown to reduce the expression of MYC targets in three different neuroblastoma models in vivo. A combination of brequinar and temozolomide was curative in the majority of transgenic TH-MYCN neuroblastoma mice, indicating a highly active clinical combination therapy. Overall, DHODH inhibition combined with temozolomide has therapeutic potential in neuroblastoma and we propose this combination for clinical testing.

Keywords:  Cancer; Oncology; Therapeutics

DOI:  https://doi.org/10.1172/jci.insight.153836
Mol Metab. 2022 Aug 06. pii: S2212-8778(22)00130-2. [Epub ahead of print] 101561

Histone lysine demethylase inhibition reprograms prostate cancer metabolism and mechanics.

Ugo Chianese, Chiara Papulino, Eugenia Passaro, Tom Mj Evers, Mehrad Babaei, Antonella Toraldo, Tommaso De Marchi, Emma Niméus, Vincenzo Carafa, Maria Maddalena Nicoletti, Nunzio Del Gaudio, Nunzia Iaccarino, Antonio Randazzo, Dante Rotili, Antonello Mai, Salvatore Cappabianca, Alireza Mashaghi, Fortunato Ciardiello, Lucia Altucci, Rosaria Benedetti.

  OBJECTIVE: Aberrant activity of androgen receptor (AR) is the primary cause underlying development and progression of prostate cancer (PCa) and castration-resistant PCa (CRPC). Androgen signaling regulates gene transcription and lipid metabolism, facilitating tumor growth and therapy resistance in early and advanced PCa. Although direct AR signaling inhibitors exist, AR expression and function can also be epigenetically regulated. Specifically, lysine (K)-specific demethylases (KDMs), which are often overexpressed in PCa and CRPC phenotypes, regulate the AR transcriptional program.METHODS: We investigated LSD1/UTX inhibition, two KDMs, in PCa and CRPC using a multi-omics approach. We first performed a mitochondrial stress test to evaluate respiratory capacity after treatment with MC3324, a dual KDM-inhibitor, and then carried out lipidomic, proteomic, and metabolic analyses. We also investigated mechanical cellular properties with acoustic force spectroscopy.
RESULTS: MC3324 induced a global increase in H3K4me2 and H3K27me3 accompanied by significant growth arrest and apoptosis in androgen-responsive and -unresponsive PCa systems. LSD1/UTX inhibition downregulated AR at both transcriptional and non-transcriptional level, showing cancer selectivity, indicating its potential use in resistance to androgen deprivation therapy. Since MC3324 impaired metabolic activity, by modifying the protein and lipid content in PCa and CRPC cell lines. Epigenetic inhibition of LSD1/UTX disrupted mitochondrial ATP production and mediated lipid plasticity, which affected the phosphocholine class, an important structural element for the cell membrane in PCa and CRPC associated with changes in physical and mechanical properties of cancer cells.
CONCLUSIONS: Our data suggest a network in which epigenetics, hormone signaling, metabolite availability, lipid content, and mechano-metabolic process are closely related. This network may be able to identify additional hotspots for pharmacological intervention and underscores the key role of KDM-mediated epigenetic modulation in PCa and CRPC.

Keywords:  AR; KDMs; PCa; cell stiffness; lipid; metabolism

DOI:  https://doi.org/10.1016/j.molmet.2022.101561