bims-mibica 2023-12-17 papers

bims-mibica

Biomed News

on Mitochondrial bioenergetics in cancer

Issue of 2023‒12‒17
25 papers selected by
Kelsey Fisher-Wellman, East Carolina University

The mitochondrial ATP synthase is a negative regulator of the mitochondrial permeability transition pore.
Mitochondrial temperature homeostasis resists external metabolic stresses.
Targeting Metabolic Vulnerabilities to Overcome Prostate Cancer Resistance: Dual Therapy with Apalutamide and Complex I Inhibition.
Multivariate modeling of metabolic state vulnerabilities across diverse cancer contexts reveals synthetically lethal associations.
Phenotypic profiling of solute carriers characterizes serine transport in cancer.
Enhancing anti-AML activity of venetoclax by isoflavone ME-344 through suppression of OXPHOS and/or purine biosynthesis in vitro.
NOX4 alleviates breast cancer cell aggressiveness by co-ordinating mitochondrial turnover through PGC1α/Drp1 axis.
Mitochondria transfer by platelet-derived microparticles regulates breast cancer bioenergetic states and malignant features.
GRAF1 integrates PINK1-Parkin signaling and actin dynamics to mediate cardiac mitochondrial homeostasis.
The assembly of the Mitochondrial Complex I Assembly complex uncovers a redox pathway coordination.
NDUFA8 is transcriptionally regulated by EP300/H3K27ac and promotes mitochondrial respiration to support proliferation and inhibit apoptosis in cervical cancer.
The interplay of the circadian clock and metabolic tumorigenesis.
Human frataxin, the Friedreich ataxia deficient protein, interacts with mitochondrial respiratory chain.
Phospholipids are imported into mitochondria by VDAC, a dimeric beta barrel scramblase.
IDH1-mutant preleukemic hematopoietic stem cells can be eliminated by inhibition of oxidative phosphorylation.
Treatment with the PPARα agonist fenofibrate improves the efficacy of CD8+ T cell therapy for melanoma.
Supraphysiological glutamine as a means of depleting intracellular amino acids to enhance pancreatic cancer chemosensitivity.
CMT2A-linked MFN2 mutation, T206I promotes mitochondrial hyperfusion and predisposes cells towards mitophagy.
Cells use multiple mechanisms for cell-cycle arrest upon withdrawal of individual amino acids.
Sequence differences between BAX and BAK core domains manifest as differences in their interactions with lipids.
Lipidomics Profiling Reveals Differential Alterations after FAS Inhibition in 3D Colon Cancer Cell Culture Models.
Fasting regulates mitochondrial function through lncRNA PRKCQ-AS1-mediated IGF2BPs in papillary thyroid carcinoma.
Unexpected Differences in the Speed of Non-Malignant versus Malignant Cell Migration Reveal Differential Basal Intracellular ATP Levels.
MYC protein helps cancer to take its vitamins.
Targeting glutamine dependence with DRP-104 inhibits proliferation and tumor growth of castration-resistant prostate cancer.

Proc Natl Acad Sci U S A. 2023 Dec 19. 120(51): e2303713120

The mitochondrial ATP synthase is a negative regulator of the mitochondrial permeability transition pore.

Ryan Pekson, Felix G Liang, Joshua L Axelrod, Jaehoon Lee, Dongze Qin, Andre J H Wittig, Victor M Paulino, Min Zheng, Pablo M Peixoto, Richard N Kitsis.

  The mitochondrial permeability transition pore (mPTP) is a channel in the inner mitochondrial membrane whose sustained opening in response to elevated mitochondrial matrix Ca2+ concentrations triggers necrotic cell death. The molecular identity of mPTP is unknown. One proposed candidate is the mitochondrial ATP synthase, whose canonical function is to generate most ATP in multicellular organisms. Here, we present mitochondrial, cellular, and in vivo evidence that, rather than serving as mPTP, the mitochondrial ATP synthase inhibits this pore. Our studies confirm previous work showing persistence of mPTP in HAP1 cell lines lacking an assembled mitochondrial ATP synthase. Unexpectedly, however, we observe that Ca2+-induced pore opening is markedly sensitized by loss of the mitochondrial ATP synthase. Further, mPTP opening in cells lacking the mitochondrial ATP synthase is desensitized by pharmacological inhibition and genetic depletion of the mitochondrial cis-trans prolyl isomerase cyclophilin D as in wild-type cells, indicating that cyclophilin D can modulate mPTP through substrates other than subunits in the assembled mitochondrial ATP synthase. Mitoplast patch clamping studies showed that mPTP channel conductance was unaffected by loss of the mitochondrial ATP synthase but still blocked by cyclophilin D inhibition. Cardiac mitochondria from mice whose heart muscle cells we engineered deficient in the mitochondrial ATP synthase also demonstrate sensitization of Ca2+-induced mPTP opening and desensitization by cyclophilin D inhibition. Further, these mice exhibit strikingly larger myocardial infarctions when challenged with ischemia/reperfusion in vivo. We conclude that the mitochondrial ATP synthase does not function as mPTP and instead negatively regulates this pore.

Keywords:  mitochondrial ATP synthase; mitochondrial permeability transition pore; necrosis

DOI:  https://doi.org/10.1073/pnas.2303713120
Elife. 2023 Dec 11. pii: RP89232. [Epub ahead of print]12

Mitochondrial temperature homeostasis resists external metabolic stresses.

Mügen Terzioglu, Kristo Veeroja, Toni Montonen, Teemu O Ihalainen, Tiina S Salminen, Paule Bénit, Pierre Rustin, Young-Tae Chang, Takeharu Nagai, Howard T Jacobs.

  Based on studies with a fluorescent reporter dye, Mito Thermo Yellow (MTY), and the genetically encoded gTEMP ratiometric fluorescent temperature indicator targeted to mitochondria, the temperature of active mitochondria in four mammalian and one insect cell line was estimated to be up to 15°C above that of the external environment to which the cells were exposed. High mitochondrial temperature was maintained in the face of a variety of metabolic stresses, including substrate starvation or modification, decreased ATP demand due to inhibition of cytosolic protein synthesis, inhibition of the mitochondrial adenine nucleotide transporter and, if an auxiliary pathway for electron transfer was available via the alternative oxidase, even respiratory poisons acting downstream of oxidative phosphorylation (OXPHOS) complex I. We propose that the high temperature of active mitochondria is an inescapable consequence of the biochemistry of OXPHOS and is homeostatically maintained as a primary feature of mitochondrial metabolism.

Keywords:  D. melanogaster; OXPHOS; biochemistry; bioenergetics; cell biology; chemical biology; human; mitochondria; mouse; organelle; temperature; thermogenesis

DOI:  https://doi.org/10.7554/eLife.89232
Cancers (Basel). 2023 Nov 28. pii: 5612. [Epub ahead of print]15(23):

Targeting Metabolic Vulnerabilities to Overcome Prostate Cancer Resistance: Dual Therapy with Apalutamide and Complex I Inhibition.

Valentin Baumgartner, Dominik Schaer, Daniel Eberli, Souzan Salemi.

  Prostate cancer (PCa) often becomes drug-treatment-resistant, posing a significant challenge to effective management. Although initial treatment with androgen deprivation therapy can control advanced PCa, subsequent resistance mechanisms allow tumor cells to continue growing, necessitating alternative approaches. This study delves into the specific metabolic dependencies of different PCa subtypes and explores the potential synergistic effects of combining androgen receptor (AR) inhibition (ARN with mitochondrial complex I inhibition (IACS)). We examined the metabolic behaviors of normal prostate epithelial cells (PNT1A), androgen-sensitive cells (LNCaP and C4-2), and androgen-independent cells (PC-3) when treated with ARN, IACS, or a combination. The results uncovered distinct mitochondrial activities across PCa subtypes, with androgen-dependent cells exhibiting heightened oxidative phosphorylation (OXPHOS). The combination of ARN and IACS significantly curbed cell proliferation in multiple PCa cell lines. Cellular bioenergetics analysis revealed that IACS reduced OXPHOS, while ARN hindered glycolysis in certain PCa cells. Additionally, galactose supplementation disrupted compensatory glycolytic mechanisms induced by metabolic reprogramming. Notably, glucose-deprived conditions heightened the sensitivity of PCa cells to mitochondrial inhibition, especially in the resistant PC-3 cells. Overall, this study illuminates the intricate interplay between AR signaling, metabolic adaptations, and treatment resistance in PCa. The findings offer valuable insights into subtype-specific metabolic profiles and propose a promising strategy to target PCa cells by exploiting their metabolic vulnerabilities.

Keywords:  IACS-010759; apalutamide; metabolism; mitochondria; prostate cancer

DOI:  https://doi.org/10.3390/cancers15235612
bioRxiv. 2023 Nov 29. pii: 2023.11.28.569098. [Epub ahead of print]

Multivariate modeling of metabolic state vulnerabilities across diverse cancer contexts reveals synthetically lethal associations.

Cara Abecunas, Mohammad Fallahi-Sichani.

Targeting the distinct metabolic needs of tumor cells has recently emerged as a promising strategy for cancer therapy. The heterogeneous, context-dependent nature of cancer cell metabolism, however, poses challenges in identifying effective therapeutic interventions. Here, we utilize various unsupervised and supervised multivariate modeling approaches to systematically pinpoint recurrent metabolic states within hundreds of cancer cell lines, elucidate their association with tissue lineage and growth environments, and uncover vulnerabilities linked to their metabolic states across diverse genetic and tissue contexts. We validate key findings using data from an independent set of cell lines, pharmacological screens, and via single-cell analysis of patient-derived tumors. Our analysis uncovers new synthetically lethal associations between the tumor metabolic state (e.g., oxidative phosphorylation), driver mutations (e.g., loss of tumor suppressor PTEN), and actionable biological targets (e.g., mitochondrial electron transport chain). Investigating these relationships could inform the development of more precise and context-specific, metabolism-targeted cancer therapies.

DOI: https://doi.org/10.1101/2023.11.28.569098
Nat Metab. 2023 Dec 08.

Phenotypic profiling of solute carriers characterizes serine transport in cancer.

Vasileios Papalazarou, Alice C Newman, Alejandro Huerta-Uribe, Nathalie M Legrave, Mattia Falcone, Tong Zhang, Lynn McGarry, Dimitris Athineos, Emma Shanks, Karen Blyth, Karen H Vousden, Oliver D K Maddocks.

Serine is a vital amino acid in tumorigenesis. While cells can perform de novo serine synthesis, most transformed cells rely on serine uptake to meet their increased biosynthetic requirements. Solute carriers (SLCs), a family of transmembrane nutrient transport proteins, are the gatekeepers of amino acid acquisition and exchange in mammalian cells and are emerging as anticancer therapeutic targets; however, the SLCs that mediate serine transport in cancer cells remain unknown. Here we perform an arrayed RNAi screen of SLC-encoding genes while monitoring amino acid consumption and cell proliferation in colorectal cancer cells using metabolomics and high-throughput imaging. We identify SLC6A14 and SLC25A15 as major cytoplasmic and mitochondrial serine transporters, respectively. We also observe that SLC12A4 facilitates serine uptake. Dual targeting of SLC6A14 and either SLC25A15 or SLC12A4 diminishes serine uptake and growth of colorectal cancer cells in vitro and in vivo, particularly in cells with compromised de novo serine biosynthesis. Our results provide insight into the mechanisms that contribute to serine uptake and intracellular handling.

DOI: https://doi.org/10.1038/s42255-023-00936-2
Biochem Pharmacol. 2023 Dec 09. pii: S0006-2952(23)00574-9. [Epub ahead of print] 115981

Enhancing anti-AML activity of venetoclax by isoflavone ME-344 through suppression of OXPHOS and/or purine biosynthesis in vitro.

Katie H Hurrish, Yongwei Su, Shraddha Patel, Cassandra L Ramage, Jianlei Zhao, Brianna R Temby, Jenna L Carter, Holly Edwards, Steven A Buck, Sandra E Wiley, Maik Hüttemann, Lisa Polin, Juiwanna Kushner, Sijana H Dzinic, Kathryn White, Xun Bao, Jing Li, Jay Yang, Julie Boerner, Zhanjun Hou, Gheath Al-Atrash, Sergej N Konoplev, Jonathan Busquets, Stefano Tiziani, Larry H Matherly, Jeffrey W Taub, Marina Konopleva, Yubin Ge, Natalia Baran.

  Venetoclax (VEN), in combination with low dose cytarabine (AraC) or a hypomethylating agent, is FDA approved to treat acute myeloid leukemia (AML) in patients who are over the age of 75 or cannot tolerate standard chemotherapy. Despite high response rates to these therapies, most patients succumb to the disease due to relapse and/or drug resistance, providing an unmet clinical need for novel therapies to improve AML patient survival. ME-344 is a potent isoflavone with demonstrated inhibitory activity toward oxidative phosphorylation (OXPHOS) and clinical activity in solid tumors. Given that OXPHOS inhibition enhances VEN antileukemic activity against AML, we hypothesized that ME-344 could enhance the anti-AML activity of VEN. Here we report that ME-344 enhanced VEN to target AML cell lines and primary patient samples while sparing normal hematopoietic cells. Cooperative suppression of OXPHOS was detected in a subset of AML cell lines and primary patient samples. Metabolomics analysis revealed a significant reduction of purine biosynthesis metabolites by ME-344. Further, lometrexol, a purine biosynthesis inhibitor, synergistically enhanced VEN-induced apoptosis in AML cell lines. Interestingly, AML cells with acquired AraC resistance showed significantly increased purine biosynthesis metabolites and sensitivities to ME-344. Furthermore, synergy between ME-344 and VEN was preserved in these AraC-resistant AML cells. In vivo studies revealed significantly prolonged survival upon combination therapy of ME-344 and VEN in NSGS mice bearing parental or AraC-resistant MV4-11 leukemia compared to the vehicle control. This study demonstrates that ME-344 enhances VEN antileukemic activity against preclinical models of AML by suppressing OXPHOS and/or purine biosynthesis.

Keywords:  Acute myeloid leukemia; ME-344; Oxidative phosphorylation; Purine biosynthesis; Venetoclax

DOI:  https://doi.org/10.1016/j.bcp.2023.115981
Cell Signal. 2023 Dec 11. pii: S0898-6568(23)00423-0. [Epub ahead of print] 111008

NOX4 alleviates breast cancer cell aggressiveness by co-ordinating mitochondrial turnover through PGC1α/Drp1 axis.

Deepali Bhadane, Dinisha Kamble, Mangesh Deval, Subhajit Das, Sandhya Sitasawad.

  Triple Negative Breast Cancer (TNBC) is a highly aggressive form of breast cancer, with few treatment options. This study investigates the complex molecular mechanism by which NADPH oxidase 4 (NOX4), a major ROS producer in mitochondria, affects the aggressiveness of luminal and triple-negative breast cancer cells (TNBCs). We found that NOX4 expression was differentially regulated in luminal and TNBC cells, with a positive correlation to their epithelial characteristics. Time dependent analysis revealed that TNBCs exhibits higher steady-state ROS levels than luminal cells, but NOX4 silencing increased ROS levels in luminal breast cancer cells and enhanced their ability to migrate and invade. In contrast, NOX4 over expression in TNBCs had the opposite effect. The mouse tail-vein experiment showed that the group injected with NOX4 silenced luminal cells had a higher number of lung metastases compared to the control group. Mechanistically, NOX4 enhanced PGC1α dependent mitochondrial biogenesis and attenuated Drp1-mediated mitochondrial fission in luminal breast cancer cells, leading to an increased mitochondrial mass and elongated mitochondrial morphology. Interestingly, NOX4 silencing increased mitochondrial ROS (mtROS) levels without affecting mitochondrial (Δψm) and cellular integrity. Inhibition of Drp1-dependent fission with Mdivi1 reversed the effect of NOX4-dependent mitochondrial biogenesis, dynamics, and migration of breast cancer cells. Our findings suggest that NOX4 expression diminishes from luminal to a triple negative state, accompanied by elevated ROS levels, which may modulate mitochondrial turnover to attain an aggressive phenotype. The study provides potential insights for targeted therapies for TNBCs.

Keywords:  Breast cancer aggressiveness; Drp1; NOX4; PGC1α; ROS; TNBC

DOI:  https://doi.org/10.1016/j.cellsig.2023.111008
Mol Cancer Res. 2023 Dec 12.

Mitochondria transfer by platelet-derived microparticles regulates breast cancer bioenergetic states and malignant features.

Vanessa Veilleux, Nicolas Pichaud, Luc H Boudreau, Gilles A Robichaud.

An increasing number of studies show that platelets as well as platelet-derived microparticles (PMPs) play significant roles in cancer malignancy and disease progression. Particularly, PMPs have the capacity to interact and internalize within target cells resulting in the transfer of their bioactive cargo, which can modulate the signaling and activation processes of recipient cells. We recently identified a new subpopulation of these vesicles (termed mitoMPs), which contain functional mitochondria. Given the predominant role of mitochondria in cancer cell metabolism and disease progression, we set out to investigate the impact of mitoMPs on breast cancer metabolic reprograming and phenotypic processes leading to malignancy. Interestingly, we observed that recipient cell permeability to PMP internalization varied among the breast cancer cell types evaluated in our study. Specifically, cells permissive to mitoMPs acquire mitochondrial-dependent functions, which stimulate increased cellular oxygen consumption rates and intracellular ATP production. In addition, cancer cells co-incubated with PMPs display enhanced malignant features in terms of migration and invasion. Most importantly, the cancer aggressive processes and notable metabolic plasticity induced by PMPs were highly dependent on the functional status of the mitoMP-packaged mitochondria. These findings characterize a new mechanism by which breast cancer cells acquire foreign mitochondria resulting in the gain of metabolic processes and malignant features. A better understanding of these mechanisms may provide therapeutic opportunities through PMP blockade to deprive cancer cells from resources vital in disease progression. Implications: We show that the transfer of foreign mitochondria by microparticles modulates recipient cancer cell metabolic plasticity, leading to greater malignant processes.

DOI: https://doi.org/10.1158/1541-7786.MCR-23-0329
Nat Commun. 2023 Dec 11. 14(1): 8187

GRAF1 integrates PINK1-Parkin signaling and actin dynamics to mediate cardiac mitochondrial homeostasis.

Qiang Zhu, Matthew E Combs, Juan Liu, Xue Bai, Wenbo B Wang, Laura E Herring, Jiandong Liu, Jason W Locasale, Dawn E Bowles, Ryan T Gross, Michelle Mendiola Pla, Christopher P Mack, Joan M Taylor.

The serine/threonine kinase, PINK1, and the E3 ubiquitin ligase, Parkin, are known to facilitate LC3-dependent autophagosomal encasement and lysosomal clearance of dysfunctional mitochondria, and defects in this process contribute to a variety of cardiometabolic and neurological diseases. Although recent evidence indicates that dynamic actin remodeling plays an important role in PINK1/Parkin-mediated mitochondrial autophagy (mitophagy), the underlying signaling mechanisms remain unknown. Here, we identify the RhoGAP GRAF1 (Arhgap26) as a PINK1 substrate that regulates mitophagy. GRAF1 promotes the release of damaged mitochondria from F-actin anchors, regulates mitochondrial-associated Arp2/3-mediated actin remodeling and facilitates Parkin-LC3 interactions to enhance mitochondria capture by autophagosomes. Graf1 phosphorylation on PINK1-dependent sites is dysregulated in human heart failure, and cardiomyocyte-restricted Graf1 depletion in mice blunts mitochondrial clearance and attenuates compensatory metabolic adaptations to stress. Overall, we identify GRAF1 as an enzyme that coordinates cytoskeletal and metabolic remodeling to promote cardioprotection.

DOI: https://doi.org/10.1038/s41467-023-43889-6
Nat Commun. 2023 Dec 12. 14(1): 8248

The assembly of the Mitochondrial Complex I Assembly complex uncovers a redox pathway coordination.

Lindsay McGregor, Samira Acajjaoui, Ambroise Desfosses, Melissa Saïdi, Maria Bacia-Verloop, Jennifer J Schwarz, Pauline Juyoux, Jill von Velsen, Matthew W Bowler, Andrew A McCarthy, Eaazhisai Kandiah, Irina Gutsche, Montserrat Soler-Lopez.

The Mitochondrial Complex I Assembly (MCIA) complex is essential for the biogenesis of respiratory Complex I (CI), the first enzyme in the respiratory chain, which has been linked to Alzheimer's disease (AD) pathogenesis. However, how MCIA facilitates CI assembly, and how it is linked with AD pathogenesis, is poorly understood. Here we report the structural basis of the complex formation between the MCIA subunits ECSIT and ACAD9. ECSIT binding induces a major conformational change in the FAD-binding loop of ACAD9, releasing the FAD cofactor and converting ACAD9 from a fatty acid β-oxidation (FAO) enzyme to a CI assembly factor. We provide evidence that ECSIT phosphorylation downregulates its association with ACAD9 and is reduced in neuronal cells upon exposure to amyloid-β (Aβ) oligomers. These findings advance our understanding of the MCIA complex assembly and suggest a possible role for ECSIT in the reprogramming of bioenergetic pathways linked to Aβ toxicity, a hallmark of AD.

DOI: https://doi.org/10.1038/s41467-023-43865-0
Biochem Biophys Res Commun. 2023 Dec 10. pii: S0006-291X(23)01468-7. [Epub ahead of print]693 149374

NDUFA8 is transcriptionally regulated by EP300/H3K27ac and promotes mitochondrial respiration to support proliferation and inhibit apoptosis in cervical cancer.

Huaguo Xiang, Hongping Tang, Qingqing He, Junfang Sun, Yihui Yang, Lingyue Kong, Yingzhen Wang.

  Cervical cancer, a common malignancy in women, poses a significant health burden worldwide. In this study, we aimed to investigate the expression, function, and potential mechanisms of NADH: ubiquinone oxidoreductase subunit A8 (NDUFA8) in cervical cancer. The Gene Expression Profiling Interactive Analysis (GEPIA) database and immunohistochemical scoring were used to analyze NDUFA8 expression in cervical cancer tissues and normal tissues. Quantitative real-time PCR and Western blot analyses were performed to assess the expression level of NDUFA8 in cervical cancer cell lines. NDUFA8 knockdown or overexpression experiments were conducted to evaluate its impact on cell proliferation and apoptosis. The mitochondrial respiratory status was analyzed by measuring cellular oxygen consumption, adenosine triphosphate (ATP) levels, and the expression levels of Mitochondrial Complex I activity, and Mitochondrial Complex IV-associated proteins Cytochrome C Oxidase Subunit 5B (COX5B) and COX6C. NDUFA8 exhibited high expression levels in cervical cancer tissues, and these levels were correlated with reduced survival rates. A significant upregulation of NDUFA8 expression was observed in cervical cancer cell lines compared to normal cells. Silencing NDUFA8 hindered cell proliferation, promoted apoptosis, and concurrently suppressed cellular mitochondrial respiration, resulting in decreased levels of available ATP. Conversely, NDUFA8 overexpression induced the opposite effects. Herein, we also found that E1A Binding Protein P300 (EP300) overexpression facilitated Histone H3 Lysine 27 (H3K27) acetylation enrichment, enhancing the activity of the NDUFA8 promoter region. NDUFA8, which is highly expressed in cervical cancer, is regulated by transcriptional control via EP300/H3K27 acetylation. By promoting mitochondrial respiration, NDUFA8 contributes to cervical cancer cell proliferation and apoptosis. These findings provide novel insights into NDUFA8 as a therapeutic target in cervical cancer.

Keywords:  Cervical cancer; EP300/H3K27ac; Mitochondrial respiration; NDUFA8

DOI:  https://doi.org/10.1016/j.bbrc.2023.149374
Trends Cell Biol. 2023 Dec 06. pii: S0962-8924(23)00237-4. [Epub ahead of print]

The interplay of the circadian clock and metabolic tumorigenesis.

Zheng Wang, Leina Ma, Ying Meng, Jing Fang, Daqian Xu, Zhimin Lu.

  The circadian clock and cell metabolism are both dysregulated in cancer cells through intrinsic cell-autonomous mechanisms and external influences from the tumor microenvironment. The intricate interplay between the circadian clock and cancer cell metabolism exerts control over various metabolic processes, including aerobic glycolysis, de novo nucleotide synthesis, glutamine and protein metabolism, lipid metabolism, mitochondrial metabolism, and redox homeostasis in cancer cells. Importantly, oncogenic signaling can confer a moonlighting function on core clock genes, effectively reshaping cellular metabolism to fuel cancer cell proliferation and drive tumor growth. These interwoven regulatory mechanisms constitute a distinctive feature of cancer cell metabolism.

Keywords:  cancer metabolism; dysregulated circadian clock; moonlighting function

DOI:  https://doi.org/10.1016/j.tcb.2023.11.004
Cell Death Dis. 2023 Dec 08. 14(12): 805

Human frataxin, the Friedreich ataxia deficient protein, interacts with mitochondrial respiratory chain.

Doni Davide, Cavion Federica, Bortolus Marco, Baschiera Elisa, Muccioli Silvia, Tombesi Giulia, d'Ettorre Federica, Daniele Ottaviani, Marchesan Elena, Leanza Luigi, Greggio Elisa, Ziviani Elena, Russo Antonella, Bellin Milena, Sartori Geppo, Carbonera Donatella, Salviati Leonardo, Costantini Paola.

Friedreich ataxia (FRDA) is a rare, inherited neurodegenerative disease caused by an expanded GAA repeat in the first intron of the FXN gene, leading to transcriptional silencing and reduced expression of frataxin. Frataxin participates in the mitochondrial assembly of FeS clusters, redox cofactors of the respiratory complexes I, II and III. To date it is still unclear how frataxin deficiency culminates in the decrease of bioenergetics efficiency in FRDA patients' cells. We previously demonstrated that in healthy cells frataxin is closely attached to the mitochondrial cristae, which contain both the FeS cluster assembly machinery and the respiratory chain complexes, whereas in FRDA patients' cells with impaired respiration the residual frataxin is largely displaced in the matrix. To gain novel insights into the function of frataxin in the mitochondrial pathophysiology, and in the upstream metabolic defects leading to FRDA disease onset and progression, here we explored the potential interaction of frataxin with the FeS cluster-containing respiratory complexes I, II and III. Using healthy cells and different FRDA cellular models we found that frataxin interacts with these three respiratory complexes. Furthermore, by EPR spectroscopy, we observed that in mitochondria from FRDA patients' cells the decreased level of frataxin specifically affects the FeS cluster content of complex I. Remarkably, we also found that the frataxin-like protein Nqo15 from T. thermophilus complex I ameliorates the mitochondrial respiratory phenotype when expressed in FRDA patient's cells. Our data point to a structural and functional interaction of frataxin with complex I and open a perspective to explore therapeutic rationales for FRDA targeted to this respiratory complex.

DOI: https://doi.org/10.1038/s41419-023-06320-y
Nat Commun. 2023 Dec 08. 14(1): 8115

Phospholipids are imported into mitochondria by VDAC, a dimeric beta barrel scramblase.

Helene Jahn, Ladislav Bartoš, Grace I Dearden, Jeremy S Dittman, Joost C M Holthuis, Robert Vácha, Anant K Menon.

Mitochondria are double-membrane-bounded organelles that depend critically on phospholipids supplied by the endoplasmic reticulum. These lipids must cross the outer membrane to support mitochondrial function, but how they do this is unclear. We identify the Voltage Dependent Anion Channel (VDAC), an abundant outer membrane protein, as a scramblase-type lipid transporter that catalyzes lipid entry. On reconstitution into membrane vesicles, dimers of human VDAC1 and VDAC2 catalyze rapid transbilayer translocation of phospholipids by a mechanism that is unrelated to their channel activity. Coarse-grained molecular dynamics simulations of VDAC1 reveal that lipid scrambling occurs at a specific dimer interface where polar residues induce large water defects and bilayer thinning. The rate of phospholipid import into yeast mitochondria is an order of magnitude lower in the absence of VDAC homologs, indicating that VDACs provide the main pathway for lipid entry. Thus, VDAC isoforms, members of a superfamily of beta barrel proteins, moonlight as a class of phospholipid scramblases - distinct from alpha-helical scramblase proteins - that act to import lipids into mitochondria.

DOI: https://doi.org/10.1038/s41467-023-43570-y
Blood Cancer Discov. 2023 Dec 13.

IDH1-mutant preleukemic hematopoietic stem cells can be eliminated by inhibition of oxidative phosphorylation.

Niklas Landberg, Thomas Köhnke, Yang Feng, Yusuke Nakauchi, Amy C Fan, Miles H Linde, Daiki Karigane, Kelly Lim, Rahul Sinha, Luca Malcovati, Daniel Thomas, Ravindra Majeti.

Rare preleukemic hematopoietic stem cells (pHSCs) harboring only the initiating mutations can be detected at the time of AML diagnosis. pHSCs are the origin of leukemia and a potential reservoir for relapse. Using primary human samples and gene-editing to model isocitrate dehydrogenase 1 (IDH1) mutant pHSCs, we show epigenetic, transcriptional, and metabolic differences between pHSCs and healthy hematopoietic stem cells (HSCs). We confirm that IDH1 driven clonal hematopoiesis is associated with cytopenia, suggesting an inherent defect to fully reconstitute hematopoiesis. Despite giving rise to multilineage engraftment, IDH1-mutant pHSCs exhibited reduced proliferation, blocked differentiation, downregulation of MHC Class II genes, and reprogramming of oxidative phosphorylation metabolism. Critically, inhibition of oxidative phosphorylation resulted in complete eradication of IDH1-mutant pHSCs but not IDH2-mutant pHSCs or wildtype HSCs. Our results indicate that IDH1-mutant preleukemic clones can be targeted with complex I inhibitors, offering a potential strategy to prevent development and relapse of leukemia.

DOI: https://doi.org/10.1158/2643-3230.BCD-23-0195
Mol Ther Oncolytics. 2023 Dec 19. 31 100744

Treatment with the PPARα agonist fenofibrate improves the efficacy of CD8+ T cell therapy for melanoma.

Mohadeseh Hasanpourghadi, Arezki Chekaoui, Sophia Kurian, Raj Kurupati, Robert Ambrose, Wynetta Giles-Davis, Amara Saha, Xu Xiaowei, Hildegund C J Ertl.

  Adoptive transfer of tumor antigen-specific CD8+ T cells can limit tumor progression but is hampered by the T cells' rapid functional impairment within the tumor microenvironment (TME). This is in part caused by metabolic stress due to lack of oxygen and glucose. Here, we report that fenofibrate treatment of human ex vivo expanded tumor-infiltrating lymphocytes (TILs) improves their ability to limit melanoma progression in a patient-derived xenograft (PDX) mouse model. TILs treated with fenofibrate, a peroxisome proliferator receptor alpha (PPARα) agonist, switch from glycolysis to fatty acid oxidation (FAO) and increase the ability to slow the progression of autologous melanomas in mice with freshly transplanted human tumor fragments or injected with tumor cell lines established from the patients' melanomas and ex vivo expanded TILs.

Keywords:  PDX mouse model; PPARα agonist treatment; T cell metabolism; melanoma; tumor antigen-specific T cells

DOI:  https://doi.org/10.1016/j.omto.2023.100744
Res Sq. 2023 Nov 30. pii: rs.3.rs-3647514. [Epub ahead of print]

Supraphysiological glutamine as a means of depleting intracellular amino acids to enhance pancreatic cancer chemosensitivity.

Neil Bhowmick, Hayato Muranaka, Sandrine Billet, Carlos Cruz-Hernández, Johanna Ten Hoeve, Gabrielle Gonzales, Omer Elmadbouh, Le Zhang, Bethany Smith, Mourad Tighiouart, Sungyong You, Mouad Edderkaoui, Andrew Hendifar, Stephen Pandol, Jun Gong.

Limited efficacy of systemic therapy for pancreatic ductal adenocarcinoma (PDAC) patients contributes to high mortality. Cancer cells develop strategies to secure nutrients in nutrient-deprived conditions and chemotherapy treatment. Despite the dependency of PDAC on glutamine (Gln) for growth and survival, strategies designed to suppress Gln metabolism have limited effects. Here, we demonstrated that supraphysiological concentrations of glutamine (SPG) could produce paradoxical responses leading to tumor growth inhibition alone and in combination with chemotherapy. Integrated metabolic and transcriptomic analysis revealed that the growth inhibitory effect of SPG was the result of a decrease in intracellular amino acid and nucleotide pools. Mechanistically, disruption of the sodium gradient, plasma membrane depolarization, and competitive inhibition of amino acid transport mediated amino acid deprivation. Among standard chemotherapies given to PDAC patients, gemcitabine treatment resulted in a significant enrichment of amino acid and nucleoside pools, exposing a metabolic vulnerability to SPG-induced metabolic alterations. Further analysis highlighted a superior anticancer effect of D-glutamine, a non-metabolizable enantiomer of the L-glutamine, by suppressing both amino acid uptake and glutaminolysis, in gemcitabine-treated preclinical models with no apparent toxicity. Our study suggests supraphysiological glutamine could be a means of inhibiting amino acid uptake and nucleotide biosynthesis, potentiating gemcitabine sensitivity in PDAC.

DOI: https://doi.org/10.21203/rs.3.rs-3647514/v1
Mitochondrion. 2023 Dec 11. pii: S1567-7249(23)00105-8. [Epub ahead of print] 101825

CMT2A-linked MFN2 mutation, T206I promotes mitochondrial hyperfusion and predisposes cells towards mitophagy.

Rajdeep Das, Sebabrata Maity, Palamou Das, Izaz Monir Kamal, Saikat Chakrabarti, Oishee Chakrabarti.

Mutations in Mitofusin2 (MFN2) associated with the pathology of the debilitating neuropathy Charcot-Marie-Tooth type 2A (CMT2A) are known to alter mitochondrial morphology. Previously, such mutations have been shown to elicit two diametrically opposite phenotypes - while some mutations have been causally linked to enhanced mitochondrial fragmentation, others have been shown to induce hyperfusion. Our study identifies one such MFN2 mutant, T206I that causes mitochondrial hyperfusion. Cells expressing this MFN2 mutant have elongated and interconnected mitochondria. T206I-MFN2 mutation in the GTPase domain increases MFN2 stability and renders cells susceptible to stress. We show that cells expressing T206I-MFN2 have a higher predisposition towards mitophagy under conditions of serum starvation. We also detect increased DRP1 recruitment onto the outer mitochondrial membrane, though the total DRP1 protein level remains unchanged. Here we have characterized a lesser studied CMT2A-linked MFN2 mutant to show that its presence affects mitochondrial morphology and homeostasis.

DOI: https://doi.org/10.1016/j.mito.2023.101825
Cell Rep. 2023 Dec 07. pii: S2211-1247(23)01551-6. [Epub ahead of print]42(12): 113539

Cells use multiple mechanisms for cell-cycle arrest upon withdrawal of individual amino acids.

Yao Rong, Alicia M Darnell, Kiera M Sapp, Matthew G Vander Heiden, Sabrina L Spencer.

  Amino acids are required for cell growth and proliferation, but it remains unclear when and how amino acid availability impinges on the proliferation-quiescence decision. Here, we used time-lapse microscopy and single-cell tracking of cyclin-dependent kinase 2 (CDK2) activity to assess the response of individual cells to withdrawal of single amino acids and found strikingly different cell-cycle effects depending on the amino acid. For example, upon leucine withdrawal, MCF10A cells complete two cell cycles and then enter a CDK2-low quiescence, whereas lysine withdrawal causes immediate cell-cycle stalling. Methionine withdrawal triggers a restriction point phenotype similar to serum starvation or Mek inhibition: upon methionine withdrawal, cells complete their current cell cycle and enter a CDK2-low quiescence after mitosis. Modulation of restriction point regulators p21/p27 or cyclin D1 enables short-term rescue of proliferation under methionine and leucine withdrawal, and to a lesser extent lysine withdrawal, revealing a checkpoint connecting nutrient signaling to cell-cycle entry.

Keywords:  CDK2; CP: Cell biology; amino acid withdrawal; cyclin D1; leucine; lysine; methionine; p21; p27; proliferation-quiescence decision; restriction point

DOI:  https://doi.org/10.1016/j.celrep.2023.113539
FEBS J. 2023 Dec 13.

Sequence differences between BAX and BAK core domains manifest as differences in their interactions with lipids.

Michelle S Miller, Angus D Cowan, Jason M Brouwer, Sean T Smyth, Liuyu Peng, Ahmad Z Wardak, Rachel T Uren, Cindy Luo, Michael J Roy, Sayali Shah, Ziwen Tan, Gavin E Reid, Peter M Colman, Peter E Czabotar.

  The B-cell lymphoma 2 (BCL2) family members, BCL2-associated protein X (BAX) and BCL2 homologous antagonist killer (BAK), are required for programmed cell death via the mitochondrial pathway. When cells are stressed, damaged or redundant, the balance of power between the BCL2 family of proteins shifts towards BAX and BAK, allowing their transition from an inactive, monomeric state to a membrane-active oligomeric form that releases cytochrome c from the mitochondrial intermembrane space. That oligomeric state has an essential intermediate, a symmetric homodimer of BAX or BAK. Here we describe crystal structures of dimers of the core domain of BAX, comprising its helices α2-α5. These structures provide an atomic resolution description of the interactions that drive BAX homo-dimerisation and insights into potential interaction between core domain dimers and membrane lipids. The previously identified BAK lipid-interacting sites are not conserved with BAX and are likely to determine the differences between them in their interactions with lipids. We also describe structures of heterodimers of BAK/BAX core domains, yielding further insight into the differences in lipid binding between BAX and BAK.

Keywords:  BAK; BAX; BCL2; apoptosis; lipid binding

DOI:  https://doi.org/10.1111/febs.17031
J Proteome Res. 2023 Dec 08.

Lipidomics Profiling Reveals Differential Alterations after FAS Inhibition in 3D Colon Cancer Cell Culture Models.

Brian D Fries, Fernando Tobias, Yijia Wang, Joseph H Holbrook, Amanda B Hummon.

  Cancerous cells synthesize most of their lipids de novo to keep up with their rapid growth and proliferation. Fatty acid synthase (FAS) is a key enzyme in the lipogenesis pathway that is upregulated in many cancers and has gained popularity as a druggable target of interest for cancer treatment. The first FAS inhibitor discovered, cerulenin, initially showed promise for chemotherapeutic purposes until it was observed that it had adverse side effects in mice. TVB-2640 (Denifanstat) is part of the newer generation of inhibitors. With multiple generations of FAS inhibitors being developed, it is vital to understand their distinct molecular downstream effects to elucidate potential interactions in the clinic. Here, we profile the lipidome of two different colorectal cancer (CRC) spheroids treated with a generation 1 inhibitor (cerulenin) or a generation 2 inhibitor (TVB-2640). We observe that the cerulenin causes drastic changes to the spheroid morphology as well as alterations to the lipid droplets found within CRC spheroids. TVB-2640 causes higher abundances of polyunsaturated fatty acids (PUFAs) whereas cerulenin causes a decreased abundance of PUFAs. The increase in PUFAs in TVB-2640 exposed spheroids indicates it is causing cells to die via a ferroptotic mechanism rather than a conventional apoptotic or necrotic mechanism.

Keywords:  FAS inhibition; apoptosis; colon cancer; ferroptosis; lipidomics; spheroids

DOI:  https://doi.org/10.1021/acs.jproteome.3c00593
Cell Death Dis. 2023 Dec 14. 14(12): 827

Fasting regulates mitochondrial function through lncRNA PRKCQ-AS1-mediated IGF2BPs in papillary thyroid carcinoma.

Xiaoping Zhang, Yong Zhong, Lin Liu, Chengyou Jia, Haidong Cai, Jianshe Yang, Bo Wu, Zhongwei Lv.

Recurring evidence suggests that fasting has extensive antitumor effects in various cancers, including papillary thyroid carcinoma (PTC). However, the underlying mechanism of this relationship with PTC is unknown. In this study, we study the effect of fasting on glycolysis and mitochondrial function in PTC. We find that fasting impairs glycolysis and reduces mitochondrial dysfunction in vitro and in vivo and also fasting in vitro and fasting mimicking diets (FMD) in vivo significantly increase the expression of lncRNA-protein kinase C theta antisense RNA 1 (PRKCQ-AS1), during the inhibition of TPC cell glycolysis and mitochondrial function. Moreover, lncRNA PRKCQ-AS1 was significantly lower in PTC tissues and cells. In addition, PRKCQ-AS1 overexpression increased PTC cell glycolysis and mitochondrial function; PRKCQ-AS1 knockdown has the opposite effect. On further mechanistic analysis, we identified that PRKCQ-AS1 physically interacts with IGF2BPs and enhances protein arginine methyltransferases 7 (PRMT7) mRNA, which is the key player in regulating glycolysis and mitochondrial function in PTC. Hence, PRKCQ-AS1 inhibits tumor growth while regulating glycolysis and mitochondrial functions via IGF2BPs/PRMT7 signaling. These results indicate that lncRNA PRKCQ-AS1 is a key downstream target of fasting and is involved in PTC metabolic reprogramming. Further, the PRKCQ-AS1/IGF2BPs/PRMT7 axis is an ideal therapeutic target for PTC diagnosis and treatment.

DOI: https://doi.org/10.1038/s41419-023-06348-0
Cancers (Basel). 2023 Nov 22. pii: 5519. [Epub ahead of print]15(23):

Unexpected Differences in the Speed of Non-Malignant versus Malignant Cell Migration Reveal Differential Basal Intracellular ATP Levels.

Bareun Kim, Anthony T Lopez, Indhujah Thevarajan, Maria F Osuna, Monica Mallavarapu, Boning Gao, Jihan K Osborne.

  Cellular locomotion is required for survival, fertility, proper embryonic development, regeneration, and wound healing. Cell migration is a major component of metastasis, which accounts for two-thirds of all solid tumor deaths. While many studies have demonstrated increased energy requirements, metabolic rates, and migration of cancer cells compared with normal cells, few have systematically compared normal and cancer cell migration as well as energy requirements side by side. Thus, we investigated how non-malignant and malignant cells migrate, utilizing several cell lines from the breast and lung. Initial screening was performed in an unbiased high-throughput manner for the ability to migrate/invade on collagen and/or Matrigel. We unexpectedly observed that all the non-malignant lung cells moved significantly faster than cells derived from lung tumors regardless of the growth media used. Given the paradigm-shifting nature of our discovery, we pursued the mechanisms that could be responsible. Neither mass, cell doubling, nor volume accounted for the individual speed and track length of the normal cells. Non-malignant cells had higher levels of intracellular ATP at premigratory-wound induction stages. Meanwhile, cancer cells also increased intracellular ATP at premigratory-wound induction, but not to the levels of the normal cells, indicating the possibility for further therapeutic investigation.

Keywords:  cancer cell migration; cell migration; normal epithelial cell motility

DOI:  https://doi.org/10.3390/cancers15235519
Nature. 2023 Dec;624(7991): 258-260

MYC protein helps cancer to take its vitamins.

Martina Wallace.



Keywords:  Cancer; Medical research; Metabolism

DOI:  https://doi.org/10.1038/d41586-023-03764-2
Prostate. 2023 Dec 12.

Targeting glutamine dependence with DRP-104 inhibits proliferation and tumor growth of castration-resistant prostate cancer.

David Moon, J Spencer Hauck, Xue Jiang, Holly Quang, Lingfan Xu, Fan Zhang, Xia Gao, Robert Wild, Jeffrey I Everitt, Everardo Macias, Yiping He, Jiaoti Huang.

  BACKGROUND: Prostate cancer (PCa) continues to be one of the leading causes of cancer deaths in men. While androgen deprivation therapy is initially effective, castration-resistant PCa (CRPC) often recurs and has limited treatment options. Our previous study identified glutamine metabolism to be critical for CRPC growth. The glutamine antagonist 6-diazo-5-oxo-l-norleucine (DON) blocks both carbon and nitrogen pathways but has dose-limiting toxicity. The prodrug DRP-104 is expected to be preferentially converted to DON in tumor cells to inhibit glutamine utilization with minimal toxicity. However, CRPC cells' susceptibility to DRP-104 remains unclear.METHODS: Human PCa cell lines (LNCaP, LAPC4, C4-2/MDVR, PC-3, 22RV1, NCI-H660) were treated with DRP-104, and effects on proliferation and cell death were assessed. Unbiased metabolic profiling and isotope tracing evaluated the effects of DRP-104 on glutamine pathways. Efficacy of DRP-104 in vivo was evaluated in a mouse xenograft model of neuroendocrine PCa, NCI-H660.
RESULTS: DRP-104 inhibited proliferation and induced apoptosis in CRPC cell lines. Metabolite profiling showed decreases in the tricarboxylic acid cycle and nucleotide synthesis metabolites. Glutamine isotope tracing confirmed the blockade of both carbon pathway and nitrogen pathways. DRP-104 treated CRPC cells were rescued by the addition of nucleosides. DRP-104 inhibited neuroendocrine PCa xenograft growth without detectable toxicity.
CONCLUSIONS: The prodrug DRP-104 blocks glutamine carbon and nitrogen utilization, thereby inhibiting CRPC growth and inducing apoptosis. Targeting glutamine metabolism pathways with DRP-104 represents a promising therapeutic strategy for CRPC.

Keywords:  DRP-104; cancer metabolism; castration-resistant

DOI:  https://doi.org/10.1002/pros.24654