bims-mibica Biomed News
on Mitochondrial bioenergetics in cancer
Issue of 2023‒09‒24
twenty-one papers selected by
Kelsey Fisher-Wellman, East Carolina University
  1. Pathogenic mitochondrial DNA mutations inhibit melanoma metastasis.
  2. ABCC1 and glutathione metabolism limit the efficacy of BCL-2 inhibitors in acute myeloid leukemia.
  3. OXPHOS-targeting drugs in oncology: new perspectives.
  4. Manipulating mitochondrial electron flow enhances tumor immunogenicity.
  5. Reductive carboxylation epigenetically instructs T cell differentiation.
  6. PD-1 instructs a tumor-suppressive metabolic program that restricts glycolysis and restrains AP-1 activity in T cell lymphoma.
  7. Metabolic control of antitumor immunity.
  8. CPT1A-mediated fatty acid oxidation confers cancer cell resistance to immune-mediated cytolytic killing.
  9. EGR1-mediated metabolic reprogramming to oxidative phosphorylation contributes to ibrutinib resistance in B cell lymphoma.
  10. Mitochondrial transplantation strategies in multifaceted induction of cancer cell death.
  11. Nanosecond Pulsed Electric Fields (nsPEFs) Modulate Electron Transport in the Plasma Membrane and the Mitochondria.
  12. Fatty acid oxidation mediated by malonyl-CoA decarboxylase represses renal cell carcinoma progression.
  13. Metabolic modulation of mitochondrial mass during CD4+ T cell activation.
  14. Temporal landscape of mitochondrial proteostasis governed by the UPRmt.
  15. Structural insights into functional properties of the oxidized form of cytochrome c oxidase.
  16. Molecular basis for maternal inheritance of human mitochondrial DNA.
  17. Formate supplementation enhances anti-tumor CD8+ T cell fitness and efficacy of PD-1 blockade.
  18. Acetate acts as a metabolic immunomodulator by bolstering T-cell effector function and potentiating antitumor immunity in breast cancer.
  19. Tumor lipid metabolism: a mechanistic link between diet and cancer progression.
  20. Aging-Related Mitochondrial Dysfunction is Associated with Fibrosis in Benign Prostatic Hyperplasia.
  21. AIFM2 promotes hepatocellular carcinoma metastasis by enhancing mitochondrial biogenesis through activation of SIRT1/PGC-1α signaling.
  1. bioRxiv. 2023 Sep 05. pii: 2023.09.01.555986. [Epub ahead of print]
    Pathogenic mitochondrial DNA mutations inhibit melanoma metastasis.
    Spencer D Shelton, Sara House, Vijayashree Ramesh, Zhenkang Chen, Tao Wei, Xun Wang, Claire B Llamas, Siva Sai Krishna Venigalla, Cameron J Menezes, Zhiyu Zhao, Jennifer G Gill, Ralph J DeBerardinis, Sean J Morrison, Alpaslan Tasdogan, Prashant Mishra.
      Mitochondrial DNA (mtDNA) mutations are frequently observed in cancer, but their contribution to tumor progression is controversial. To evaluate the impact of mtDNA variants on tumor growth and metastasis, we created human melanoma cytoplasmic hybrid (cybrid) cell lines transplanted with wildtype mtDNA or pathogenic mtDNA encoding variants that partially or completely inhibit oxidative phosphorylation. Homoplasmic pathogenic mtDNA cybrids reliably established tumors despite dysfunctional oxidative phosphorylation. However, pathogenic mtDNA variants disrupted spontaneous metastasis of subcutaneous tumors and decreased the abundance of circulating melanoma cells in the blood. Pathogenic mtDNA did not induce anoikis or inhibit organ colonization of melanoma cells following intravenous injections. Instead, migration and invasion were reduced, indicating that limited circulation entry functions as a metastatic bottleneck amidst mtDNA dysfunction. Furthermore, analysis of selective pressure exerted on the mitochondrial genomes of heteroplasmic cybrid lines revealed a suppression of pathogenic mtDNA allelic frequency during melanoma growth. Collectively, these findings demonstrate that functional mtDNA is favored during melanoma growth and enables metastatic entry into the blood.
    DOI:  https://doi.org/10.1101/2023.09.01.555986
  2. Nat Commun. 2023 09 19. 14(1): 5709
    ABCC1 and glutathione metabolism limit the efficacy of BCL-2 inhibitors in acute myeloid leukemia.
    Jessica Ebner, Johannes Schmoellerl, Martin Piontek, Gabriele Manhart, Selina Troester, Bing Z Carter, Heidi Neubauer, Richard Moriggl, Gergely Szakács, Johannes Zuber, Thomas Köcher, Michael Andreeff, Wolfgang R Sperr, Peter Valent, Florian Grebien.
      The BCL-2 inhibitor Venetoclax is a promising agent for the treatment of acute myeloid leukemia (AML). However, many patients are refractory to Venetoclax, and resistance develops quickly. ATP-binding cassette (ABC) transporters mediate chemotherapy resistance but their role in modulating the activity of targeted small-molecule inhibitors is unclear. Using CRISPR/Cas9 screening, we find that loss of ABCC1 strongly increases the sensitivity of AML cells to Venetoclax. Genetic and pharmacologic ABCC1 inactivation potentiates the anti-leukemic effects of BCL-2 inhibitors and efficiently re-sensitizes Venetoclax-resistant leukemia cells. Conversely, ABCC1 overexpression induces resistance to BCL-2 inhibitors by reducing intracellular drug levels, and high ABCC1 levels predicts poor response to Venetoclax therapy in patients. Consistent with ABCC1-specific export of glutathionylated substrates, inhibition of glutathione metabolism increases the potency of BCL-2 inhibitors. These results identify ABCC1 and glutathione metabolism as mechanisms limiting efficacy of BCL-2 inhibitors, which may pave the way to development of more effective therapies.
    DOI:  https://doi.org/10.1038/s41467-023-41229-2
  3. Expert Opin Ther Targets. 2023 Sep 22.
    OXPHOS-targeting drugs in oncology: new perspectives.
    Balaraman Kalyanaraman, Gang Cheng, Micael Hardy, Ming You.
      INTRODUCTION: Drugs targeting mitochondria are emerging as promising antitumor therapeutics in preclinical models. However, a few of these drugs have shown clinical toxicity. Developing mitochondria-targeted modified natural compounds and US FDA-approved drugs with increased therapeutic index in cancer is discussed as an alternative strategy.AREAS COVERED: Triphenylphosphonium cation (TPP+)-based drugs selectively accumulate in the mitochondria of cancer cells due to their increased negative membrane potential, target the oxidative phosphorylation proteins, inhibit mitochondrial respiration, and inhibit tumor proliferation. TPP+-based drugs exert minimal toxic side effects in rodents and humans. These drugs can sensitize radiation and immunotherapies.
    EXPERT OPINION: TPP+-based drugs targeting the tumor mitochondrial electron transport chain are a new class of oxidative phosphorylation inhibitors with varying antiproliferative and antimetastatic potencies. Some of these TPP+-based agents, which are synthesized from naturally occurring molecules and FDA-approved drugs, have been tested in mice and did not show notable toxicity, including neurotoxicity, when used at doses under the maximally tolerated dose. Thus, more effort should be directed toward the clinical translation of TPP+-based OXPHOS-inhibiting drugs in cancer prevention and treatment.
    Keywords:  Mitochondrial targets; mitochondrial therapeutics; tumor cells; tumor metastasis; tumor xenografts
    DOI:  https://doi.org/10.1080/14728222.2023.2261631
  4. Science. 2023 Sep 22. 381(6664): 1316-1323
    Manipulating mitochondrial electron flow enhances tumor immunogenicity.
    Kailash Chandra Mangalhara, Siva Karthik Varanasi, Melissa A Johnson, Mannix J Burns, Gladys R Rojas, Pau B Esparza Moltó, Alva G Sainz, Nimesha Tadepalle, Keene L Abbott, Gaurav Mendiratta, Dan Chen, Yagmur Farsakoglu, Tenzin Kunchok, Filipe Araujo Hoffmann, Bianca Parisi, Mercedes Rincon, Matthew G Vander Heiden, Marcus Bosenberg, Diana C Hargreaves, Susan M Kaech, Gerald S Shadel.
      Although tumor growth requires the mitochondrial electron transport chain (ETC), the relative contribution of complex I (CI) and complex II (CII), the gatekeepers for initiating electron flow, remains unclear. In this work, we report that the loss of CII, but not that of CI, reduces melanoma tumor growth by increasing antigen presentation and T cell-mediated killing. This is driven by succinate-mediated transcriptional and epigenetic activation of major histocompatibility complex-antigen processing and presentation (MHC-APP) genes independent of interferon signaling. Furthermore, knockout of methylation-controlled J protein (MCJ), to promote electron entry preferentially through CI, provides proof of concept of ETC rewiring to achieve antitumor responses without side effects associated with an overall reduction in mitochondrial respiration in noncancer cells. Our results may hold therapeutic potential for tumors that have reduced MHC-APP expression, a common mechanism of cancer immunoevasion.
    DOI:  https://doi.org/10.1126/science.abq1053
  5. Nature. 2023 Sep 20.
    Reductive carboxylation epigenetically instructs T cell differentiation.
    Alison Jaccard, Tania Wyss, Noelia Maldonado-Pérez, Jan A Rath, Alessio Bevilacqua, Jhan-Jie Peng, Anouk Lepez, Christine Von Gunten, Fabien Franco, Kung-Chi Kao, Nicolas Camviel, Francisco Martín, Bart Ghesquière, Denis Migliorini, Caroline Arber, Pedro Romero, Ping-Chih Ho, Mathias Wenes.
      Protective immunity against pathogens or cancer is mediated by the activation and clonal expansion of antigen-specific naive T cells into effector T cells. To sustain their rapid proliferation and effector functions, naive T cells switch their quiescent metabolism to an anabolic metabolism through increased levels of aerobic glycolysis, but also through mitochondrial metabolism and oxidative phosphorylation, generating energy and signalling molecules1-3. However, how that metabolic rewiring drives and defines the differentiation of T cells remains unclear. Here we show that proliferating effector CD8+ T cells reductively carboxylate glutamine through the mitochondrial enzyme isocitrate dehydrogenase 2 (IDH2). Notably, deletion of the gene encoding IDH2 does not impair the proliferation of T cells nor their effector function, but promotes the differentiation of memory CD8+ T cells. Accordingly, inhibiting IDH2 during ex vivo manufacturing of chimeric antigen receptor (CAR) T cells induces features of memory T cells and enhances antitumour activity in melanoma, leukaemia and multiple myeloma. Mechanistically, inhibition of IDH2 activates compensating metabolic pathways that cause a disequilibrium in metabolites regulating histone-modifying enzymes, and this maintains chromatin accessibility at genes that are required for the differentiation of memory T cells. These findings show that reductive carboxylation in CD8+ T cells is dispensable for their effector response and proliferation, but that it mainly produces a pattern of metabolites that epigenetically locks CD8+ T cells into a terminal effector differentiation program. Blocking this metabolic route allows the increased formation of memory T cells, which could be exploited to optimize the therapeutic efficacy of CAR T cells.
    DOI:  https://doi.org/10.1038/s41586-023-06546-y
  6. Nat Cancer. 2023 Sep 18.
    PD-1 instructs a tumor-suppressive metabolic program that restricts glycolysis and restrains AP-1 activity in T cell lymphoma.
    Tim Wartewig, Jay Daniels, Miriam Schulz, Erik Hameister, Abhinav Joshi, Joonhee Park, Emma Morrish, Anuroop V Venkatasubramani, Filippo M Cernilogar, Frits H A van Heijster, Christian Hundshammer, Heike Schneider, Filippos Konstantinidis, Judith V Gabler, Christine Klement, Henry Kurniawan, Calvin Law, Yujin Lee, Sara Choi, Joan Guitart, Ignasi Forne, Jérôme Giustinani, Markus Müschen, Salvia Jain, David M Weinstock, Roland Rad, Nicolas Ortonne, Franz Schilling, Gunnar Schotta, Axel Imhof, Dirk Brenner, Jaehyuk Choi, Jürgen Ruland.
      The PDCD1-encoded immune checkpoint receptor PD-1 is a key tumor suppressor in T cells that is recurrently inactivated in T cell non-Hodgkin lymphomas (T-NHLs). The highest frequencies of PDCD1 deletions are detected in advanced disease, predicting inferior prognosis. However, the tumor-suppressive mechanisms of PD-1 signaling remain unknown. Here, using tractable mouse models for T-NHL and primary patient samples, we demonstrate that PD-1 signaling suppresses T cell malignancy by restricting glycolytic energy and acetyl coenzyme A (CoA) production. In addition, PD-1 inactivation enforces ATP citrate lyase (ACLY) activity, which generates extramitochondrial acetyl-CoA for histone acetylation to enable hyperactivity of activating protein 1 (AP-1) transcription factors. Conversely, pharmacological ACLY inhibition impedes aberrant AP-1 signaling in PD-1-deficient T-NHLs and is toxic to these cancers. Our data uncover genotype-specific vulnerabilities in PDCD1-mutated T-NHL and identify PD-1 as regulator of AP-1 activity.
    DOI:  https://doi.org/10.1038/s43018-023-00635-7
  7. Science. 2023 Sep 22. 381(6664): 1287-1288
    Metabolic control of antitumor immunity.
    Andromachi Pouikli, Christian Frezza.
      Mitochondrial metabolite reduces melanoma growth by boosting antigen presentation.
    DOI:  https://doi.org/10.1126/science.adk1785
  8. Proc Natl Acad Sci U S A. 2023 Sep 26. 120(39): e2302878120
    CPT1A-mediated fatty acid oxidation confers cancer cell resistance to immune-mediated cytolytic killing.
    Zheng Liu, Wenjie Liu, Wei Wang, Yibao Ma, Yufeng Wang, David L Drum, Jinyang Cai, Hallie Blevins, Eun Lee, Syed Shah, Paul B Fisher, Xinhui Wang, Xianjun Fang, Chunqing Guo, Xiang-Yang Wang.
      Although tumor-intrinsic fatty acid β-oxidation (FAO) is implicated in multiple aspects of tumorigenesis and progression, the impact of this metabolic pathway on cancer cell susceptibility to immunotherapy remains unknown. Here, we report that cytotoxicity of killer T cells induces activation of FAO and upregulation of carnitine palmitoyltransferase 1A (CPT1A), the rate-limiting enzyme of FAO in cancer cells. The repression of CPT1A activity or expression renders cancer cells more susceptible to destruction by cytotoxic T lymphocytes. Our mechanistic studies reveal that FAO deficiency abrogates the prosurvival signaling in cancer cells under immune cytolytic stress. Furthermore, we identify T cell-derived IFN-γ as a major factor responsible for induction of CPT1A and FAO in an AMPK-dependent manner, indicating a dynamic interplay between immune effector cells and tumor targets. While cancer growth in the absence of CPT1A remains largely unaffected, established tumors upon FAO inhibition become significantly more responsive to cellular immunotherapies including chimeric antigen receptor-engineered human T cells. Together, these findings uncover a mode of cancer resistance and immune editing that can facilitate immune escape and limit the benefits of immunotherapies.
    Keywords:  cancer metabolism; carnitine palmitoyltransferase 1A; cellular immunotherapy; fatty acid oxidation; therapeutic resistance
    DOI:  https://doi.org/10.1073/pnas.2302878120
  9. Blood. 2023 Sep 22. pii: blood.2023020142. [Epub ahead of print]
    EGR1-mediated metabolic reprogramming to oxidative phosphorylation contributes to ibrutinib resistance in B cell lymphoma.
    Yunxia Liu, Shuichi Kimpara, Nguyet-Minh M Hoang, Anusara Daenthanasanmak, Yangguang Li, Li Lu, Vu N Ngo, Paul Bates, Longzhen Song, Xiaoyue Gao, Samantha Bebel, Madelyn Chen, Ruoyu Chen, Xiyu Zhang, Paul E Selberg, Vaishalee P Kenkre, Christian M Capitini, Thomas Waldmann, Lixin Rui.
      The use of Bruton tyrosine kinase (BTK) inhibitors such as ibrutinib to block B cell receptor (BCR) signaling has achieved a remarkable clinical response in several B cell malignancies including mantle cell lymphoma (MCL) and diffuse large B cell lymphoma (DLBCL). Acquired drug resistance, however, is significant and impacts long-term survival of these patients. Here we demonstrate that the transcription factor EGR1 is involved in ibrutinib resistance. We found that EGR1 expression is elevated in ibrutinib-resistant activated B-cell-like subtype (ABC) DLBCL and MCL cells and can be further upregulated upon ibrutinib treatment. Genetic and pharmacological analyses revealed that overexpressed EGR1 mediates ibrutinib resistance. Mechanistically, TCF4 and EGR1 self-regulation induce EGR1 overexpression that mediates metabolic reprogramming to oxidative phosphorylation (OXPHOS) through transcriptional activation of PDP1, a phosphatase that dephosphorylates and activates the E1 component of the large pyruvate dehydrogenase complex. Therefore, EGR1-mediated PDP1 activation increases intracellular ATP production, leading to sufficient energy to enhance the proliferation and survival of ibrutinib-resistant lymphoma cells. Finally, we demonstrate that targeting OXPHOS with metformin or IM156, a newly developed OXPHOS inhibitor, inhibits the growth of ibrutinib-resistant lymphoma cells both in vitro and in a patient-derived xenograft mouse model. These findings suggest that targeting EGR1-mediated metabolic reprogramming to OXPHOS with metformin or IM156 provides a potential therapeutic strategy to overcome ibrutinib resistance in relapsed/refractory DLBCL or MCL.
    DOI:  https://doi.org/10.1182/blood.2023020142
  10. Life Sci. 2023 Sep 19. pii: S0024-3205(23)00733-6. [Epub ahead of print] 122098
    Mitochondrial transplantation strategies in multifaceted induction of cancer cell death.
    Alfredo Cruz-Gregorio, Ana Karina Aranda-Rivera, Isabel Amador-Martinez, Paola Maycotte.
      Otto Warburg hypothesized that some cancer cells reprogram their metabolism, favoring glucose metabolism by anaerobic glycolysis (Warburg effect) instead of oxidative phosphorylation, mainly because the mitochondria of these cells were damaged or dysfunctional. It should be noted that mitochondrial apoptosis is decreased because of the dysfunctional mitochondria. Strategies like mitochondrial transplantation therapy, where functional mitochondria are transplanted to cancer cells, could increase cell death, such as apoptosis because the intrinsic apoptosis mechanisms would be reactivated. In addition, mitochondrial transplantation is associated with the redox state, which could promote synergy with common anticancer treatments such as ionizing radiation, chemotherapy, or radiotherapy, increasing cell death due to the presence or decrease of oxidative stress. On the other hand, mitochondrial transfer, a natural process for sharing mitochondrial between cells, induces an increase in chemoresistance and invasiveness in cancer cells that receive mitochondria from cells of the tumor microenvironment (TME), which indicates an antitumor therapeutic target. This review focuses on understanding mitochondrial transplantation as a therapeutic outcome induced by a procedure in aspects including oxidative stress, metabolism shifting, mitochondrial function, auto-/mitophagy, invasiveness, and chemoresistance. It also explores how these mechanisms, such as apoptosis, necroptosis, and parthanatos, impact cell death pathways.
    Keywords:  Apoptosis; Autophagy; Induction of cancer death; Mitochondrial transfer; Mitochondrial transplantation; Necroptosis; Oxidative stress
    DOI:  https://doi.org/10.1016/j.lfs.2023.122098
  11. Bioelectrochemistry. 2023 Sep 09. pii: S1567-5394(23)00205-0. [Epub ahead of print]155 108568
    Nanosecond Pulsed Electric Fields (nsPEFs) Modulate Electron Transport in the Plasma Membrane and the Mitochondria.
    Kamal Asadipour, Maisoun Bani Hani, Lucas Potter, Brittney L Ruedlinger, Nicola Lai, Stephen J Beebe.
      Nanosecond pulsed electric fields (nsPEFs) are a pulsed power technology known for ablating tumors, but they also modulate diverse biological mechanisms. Here we show that nsPEFs regulate trans-plasma membrane electron transport (tPMET) rates in the plasma membrane redox system (PMRS) shown as a reduction of the cell-impermeable, WST-8 tetrazolium dye. At lower charging conditions, nsPEFs enhance, and at higher charging conditions inhibit tPMET in H9c2 non-cancerous cardiac myoblasts and 4T1-luc breast cancer cells. This biphasic nsPEF-induced modulation of tPMET is typical of a hormetic stimulus that is beneficial and stress-adaptive at lower levels and damaging at higher levels. NsPEFs also attenuated mitochondrial electron transport system (ETS) activity (O2 consumption) at Complex I when coupled and uncoupled to oxidative phosphorylation. NsPEFs generated more reactive oxygen species (ROS) in mitochondria (mROS) than in the cytosol (cROS) in non-cancer H9c2 heart cells but more cROS than mROS in 4T1-luc cancer cells. Under lower charging conditions, nsPEFs support glycolysis while under higher charging conditions, nsPEFs inhibit electron transport in the PMRS and the mitochondrial ETS producing ROS, ultimately causing cell death. The impact of nsPEF on ETS presents a new paradigm for considering nsPEF modulation of redox functions, including redox homeostasis and metabolism.
    Keywords:  Complex I; Electron Transport System (ETS); Glycolysis; Hormesis; Oxidative Phosphorylation (OxPhos); Oxygen Consumption; Reactive Oxygen Species; Redox Homeostasis; WST-8 tetrazolium dye; trans Plasma Membrane Electron Transport (tPMET)
    DOI:  https://doi.org/10.1016/j.bioelechem.2023.108568
  12. Cancer Res. 2023 Sep 20.
    Fatty acid oxidation mediated by malonyl-CoA decarboxylase represses renal cell carcinoma progression.
    Lijie Zhou, Yongbo Luo, Yuenan Liu, Youmiao Zeng, Junwei Tong, Mengting Li, Yaxin Hou, Kaixuan Du, Yabin Qi, Wenbang Pan, Yuanhao Liu, Rongli Wang, Fengyan Tian, Chaohui Gu, Ke Chen.
      Fatty acid metabolism reprogramming is a prominent feature of clear cell renal cell carcinoma (ccRCC). Increased lipid storage supports ccRCC progression, highlighting the importance of understanding the molecular mechanisms driving altered fatty acid synthesis in tumors. Here, we identified that malonyl-CoA decarboxylase (MLYCD), a key regulator of fatty acid anabolism, was downregulated in ccRCC, and low expression correlated with poor prognosis in patients. Restoring MLYCD expression in ccRCC cells decreased the content of malonyl CoA, which blocked de novo fatty acid synthesis and promoted fatty acid translocation into mitochondria for oxidation. Inhibition of lipid droplet accumulation induced by MLYCD-mediated fatty acid oxidation disrupted endoplasmic reticulum and mitochondrial homeostasis, increased reactive oxygen species levels, and induced ferroptosis. Moreover, overexpressing MLYCD reduced tumor growth and reversed resistance to sunitinib in vitro and in vivo. Mechanistically, HIF2α inhibited MLYCD translation by upregulating expression of eIF4G3 microexons. Together, this study demonstrates that fatty acid catabolism mediated by MLYCD disrupts lipid homeostasis to repress ccRCC progression. Activating MLYCD-mediated fatty acid metabolism could be a promising therapeutic strategy for treating ccRCC.
    DOI:  https://doi.org/10.1158/0008-5472.CAN-23-0969
  13. Cell Chem Biol. 2023 Aug 31. pii: S2451-9456(23)00280-5. [Epub ahead of print]
    Metabolic modulation of mitochondrial mass during CD4+ T cell activation.
    Kiran Kurmi, Dan Liang, Robert van de Ven, Peter Georgiev, Brandon Mark Gassaway, SeongJun Han, Giulia Notarangelo, Isaac S Harris, Cong-Hui Yao, Joon Seok Park, Song-Hua Hu, Jingyu Peng, Jefte M Drijvers, Sarah Boswell, Artem Sokolov, Stephanie K Dougan, Peter K Sorger, Steven P Gygi, Arlene H Sharpe, Marcia C Haigis.
      Mitochondrial biogenesis initiates within hours of T cell receptor (TCR) engagement and is critical for T cell activation, function, and survival; yet, how metabolic programs support mitochondrial biogenesis during TCR signaling is not fully understood. Here, we performed a multiplexed metabolic chemical screen in CD4+ T lymphocytes to identify modulators of metabolism that impact mitochondrial mass during early T cell activation. Treatment of T cells with pyrvinium pamoate early during their activation blocks an increase in mitochondrial mass and results in reduced proliferation, skewed CD4+ T cell differentiation, and reduced cytokine production. Furthermore, administration of pyrvinium pamoate at the time of induction of experimental autoimmune encephalomyelitis, an experimental model of multiple sclerosis in mice, prevented the onset of clinical disease. Thus, modulation of mitochondrial biogenesis may provide a therapeutic strategy for modulating T cell immune responses.
    Keywords:  CD4(+) T cells; T cell differentiation; high-throughput metabolic screen; mitochondrial biogenesis; pyruvate oxidation; pyrvinium pamoate
    DOI:  https://doi.org/10.1016/j.chembiol.2023.08.008
  14. Sci Adv. 2023 Sep 22. 9(38): eadh8228
    Temporal landscape of mitochondrial proteostasis governed by the UPRmt.
    Louise Uoselis, Runa Lindblom, Wai Kit Lam, Catharina J Küng, Marvin Skulsuppaisarn, Grace Khuu, Thanh N Nguyen, Danielle L Rudler, Aleksandra Filipovska, Ralf B Schittenhelm, Michael Lazarou.
      Breakdown of mitochondrial proteostasis activates quality control pathways including the mitochondrial unfolded protein response (UPRmt) and PINK1/Parkin mitophagy. However, beyond the up-regulation of chaperones and proteases, we have a limited understanding of how the UPRmt remodels and restores damaged mitochondrial proteomes. Here, we have developed a functional proteomics framework, termed MitoPQ (Mitochondrial Proteostasis Quantification), to dissect the UPRmt's role in maintaining proteostasis during stress. We find essential roles for the UPRmt in both protecting and repairing proteostasis, with oxidative phosphorylation metabolism being a central target of the UPRmt. Transcriptome analyses together with MitoPQ reveal that UPRmt transcription factors drive independent signaling arms that act in concert to maintain proteostasis. Unidirectional interplay between the UPRmt and PINK1/Parkin mitophagy was found to promote oxidative phosphorylation recovery when the UPRmt failed. Collectively, this study defines the network of proteostasis mediated by the UPRmt and highlights the value of functional proteomics in decoding stressed proteomes.
    DOI:  https://doi.org/10.1126/sciadv.adh8228
  15. Nat Commun. 2023 09 16. 14(1): 5752
    Structural insights into functional properties of the oxidized form of cytochrome c oxidase.
    Izumi Ishigami, Raymond G Sierra, Zhen Su, Ariana Peck, Cong Wang, Frederic Poitevin, Stella Lisova, Brandon Hayes, Frank R Moss, Sébastien Boutet, Robert E Sublett, Chun Hong Yoon, Syun-Ru Yeh, Denis L Rousseau.
      Cytochrome c oxidase (CcO) is an essential enzyme in mitochondrial and bacterial respiration. It catalyzes the four-electron reduction of molecular oxygen to water and harnesses the chemical energy to translocate four protons across biological membranes. The turnover of the CcO reaction involves an oxidative phase, in which the reduced enzyme (R) is oxidized to the metastable OH state, and a reductive phase, in which OH is reduced back to the R state. During each phase, two protons are translocated across the membrane. However, if OH is allowed to relax to the resting oxidized state (O), a redox equivalent to OH, its subsequent reduction to R is incapable of driving proton translocation. Here, with resonance Raman spectroscopy and serial femtosecond X-ray crystallography (SFX), we show that the heme a3 iron and CuB in the active site of the O state, like those in the OH state, are coordinated by a hydroxide ion and a water molecule, respectively. However, Y244, critical for the oxygen reduction chemistry, is in the neutral protonated form, which distinguishes O from OH, where Y244 is in the deprotonated tyrosinate form. These structural characteristics of O provide insights into the proton translocation mechanism of CcO.
    DOI:  https://doi.org/10.1038/s41467-023-41533-x
  16. Nat Genet. 2023 Sep 18.
    Molecular basis for maternal inheritance of human mitochondrial DNA.
    William Lee, Angelica Zamudio-Ochoa, Gina Buchel, Petar Podlesniy, Nuria Marti Gutierrez, Margalida Puigròs, Anna Calderon, Hsin-Yao Tang, Li Li, Aleksei Mikhalchenko, Amy Koski, Ramon Trullas, Shoukhrat Mitalipov, Dmitry Temiakov.
      Uniparental inheritance of mitochondrial DNA (mtDNA) is an evolutionary trait found in nearly all eukaryotes. In many species, including humans, the sperm mitochondria are introduced to the oocyte during fertilization1,2. The mechanisms hypothesized to prevent paternal mtDNA transmission include ubiquitination of the sperm mitochondria and mitophagy3,4. However, the causative mechanisms of paternal mtDNA elimination have not been defined5,6. We found that mitochondria in human spermatozoa are devoid of intact mtDNA and lack mitochondrial transcription factor A (TFAM)-the major nucleoid protein required to protect, maintain and transcribe mtDNA. During spermatogenesis, sperm cells express an isoform of TFAM, which retains the mitochondrial presequence, ordinarily removed upon mitochondrial import. Phosphorylation of this presequence prevents mitochondrial import and directs TFAM to the spermatozoon nucleus. TFAM relocalization from the mitochondria of spermatogonia to the spermatozoa nucleus directly correlates with the elimination of mtDNA, thereby explaining maternal inheritance in this species.
    DOI:  https://doi.org/10.1038/s41588-023-01505-9
  17. Cancer Discov. 2023 Sep 20.
    Formate supplementation enhances anti-tumor CD8+ T cell fitness and efficacy of PD-1 blockade.
    Jared H Rowe, Ilaria Elia, Osmaan Shahid, Emily F Gaudiano, Natalia E Sifnugel, Sheila Johnson, Amy G Reynolds, Megan E Fung, Shakchhi Joshi, Martin W LaFleur, Joon Seok Park, Kristen E Pauken, Joshua D Rabinowitz, Gordon J Freeman, Marcia C Haigis, Arlene H Sharpe.
      The tumor microenvironment (TME) restricts anti-tumor CD8+ T cell function and immunotherapy responses. Cancer cells compromise metabolic fitness of CD8+ T cells within the TME, but the mechanisms are largely unknown. Here we demonstrate one carbon (1C) metabolism is enhanced in T cells in an antigen-specific manner. Therapeutic supplementation of 1C metabolism using formate enhances CD8+ T cell fitness and anti-tumor efficacy of PD-1 blockade in B16-OVA tumors. Formate supplementation drives transcriptional alterations in CD8+ T cell metabolism and increases gene signatures for cellular proliferation and activation. Combined formate and anti-PD-1 therapy increases tumor-infiltrating CD8+ T cells, which are essential for the enhanced tumor control. Our data demonstrate formate provides metabolic support to CD8+ T cells reinvigorated by anti-PD-1 to overcome a metabolic vulnerability in 1C metabolism in the TME to further improve T cell function.
    DOI:  https://doi.org/10.1158/2159-8290.CD-22-1301
  18. Nat Cancer. 2023 Sep 18.
    Acetate acts as a metabolic immunomodulator by bolstering T-cell effector function and potentiating antitumor immunity in breast cancer.
    Katelyn D Miller, Seamus O'Connor, Katherine A Pniewski, Toshitha Kannan, Reyes Acosta, Gauri Mirji, Sara Papp, Michael Hulse, Dzmitry Mukha, Sabina I Hlavaty, Kelsey N Salcido, Fabrizio Bertolazzi, Yellamelli V V Srikanth, Steven Zhao, Kathryn E Wellen, Rahul S Shinde, Daniel T Claiborne, Andrew Kossenkov, Joseph M Salvino, Zachary T Schug.
      Acetate metabolism is an important metabolic pathway in many cancers and is controlled by acetyl-CoA synthetase 2 (ACSS2), an enzyme that catalyzes the conversion of acetate to acetyl-CoA. While the metabolic role of ACSS2 in cancer is well described, the consequences of blocking tumor acetate metabolism on the tumor microenvironment and antitumor immunity are unknown. We demonstrate that blocking ACSS2, switches cancer cells from acetate consumers to producers of acetate thereby freeing acetate for tumor-infiltrating lymphocytes to use as a fuel source. We show that acetate supplementation metabolically bolsters T-cell effector functions and proliferation. Targeting ACSS2 with CRISPR-Cas9 guides or a small-molecule inhibitor promotes an antitumor immune response and enhances the efficacy of chemotherapy in preclinical breast cancer models. We propose a paradigm for targeting acetate metabolism in cancer in which inhibition of ACSS2 dually acts to impair tumor cell metabolism and potentiate antitumor immunity.
    DOI:  https://doi.org/10.1038/s43018-023-00636-6
  19. Curr Opin Biotechnol. 2023 Sep 13. pii: S0958-1669(23)00103-9. [Epub ahead of print]84 102993
    Tumor lipid metabolism: a mechanistic link between diet and cancer progression.
    Yu-Jin Jeong, Thomas J Rogers, Carolyn E Anderson, Evan C Lien.
      The potential for 'anti-cancer' diets to markedly alter cancer risk and prognosis has captured the imagination of patients, physicians, and researchers alike, but many of these dietary recommendations come from correlative studies that attribute certain diets to altered cancer risk. While provocative, little is known about the molecular mechanisms behind how these dietary interventions impact cancer progression. Within this context, however, changes in tumor lipid metabolism are emerging as a key contributor. In this review, we examine the current understanding of lipid metabolism in the tumor microenvironment (TME), suggesting how diet-induced changes in lipid composition may regulate tumor progression and therapeutic efficacy. By dissecting various cellular pathways involved in lipid metabolism, we highlight how diet modulates the balance between saturated and unsaturated fatty acid (FA) species in tumors to impact cancer cell and stromal cell function. Finally, we describe how current cancer therapies may synergize with diet to improve therapeutic efficacy.
    DOI:  https://doi.org/10.1016/j.copbio.2023.102993
  20. J Gerontol A Biol Sci Med Sci. 2023 Sep 20. pii: glad222. [Epub ahead of print]
    Aging-Related Mitochondrial Dysfunction is Associated with Fibrosis in Benign Prostatic Hyperplasia.
    Alexis E Adrian, Teresa T Liu, Laura E Pascal, Scott R Bauer, Donald B DeFranco, William A Ricke.
      BACKGROUND: Age is the greatest risk factor for lower urinary tract symptoms attributed to benign prostatic hyperplasia (LUTS/BPH). While LUTS/BPH can be managed with pharmacotherapy, treatment failure has been putatively attributed to numerous pathological features of BPH (e.g., prostatic fibrosis, inflammation). Mitochondrial dysfunction is a hallmark of aging, however its impact on the pathological features of BPH remains unknown.METHODS: Publicly available gene array data was analyzed. Immunohistochemistry examined mitochondrial proteins in human prostate. The effect of complex I inhibition (rotenone) on a prostatic cell line was examined using qPCR, immunocytochemistry, and Seahorse assays. Oleic acid was tested as a bypass of complex I inhibition. Aged mice were treated with OA to examine its effects on urinary dysfunction. Voiding was assessed longitudinally, and a critical complex I protein measured.
    RESULTS: Mitochondrial function and fibrosis genes were altered in BPH. Essential mitochondrial proteins (i.e., VDAC1/2, PINK1 and NDUFS3) were significantly (P<0.05) decreased in BPH. Complex I inhibition in cultured cells resulted in decreased respiration, altered NDUFS3 expression, increased collagen deposition and gene expression. Oleic acid ameliorated these effects. Oleic acid treated aged mice had significantly (P<0.05) improved voiding function and higher prostatic NDUFS3 expression.
    CONCLUSION: Complex I dysfunction is a potential contributor to fibrosis and lower urinary tract dysfunction in aged mice. Oleic acid partially bypasses complex I inhibition and therefore should be further investigated as a mitochondrial modulator for treatment of LUTS/BPH. Hypotheses generated in this investigation offer a heretofore unexplored cellular target of interest for the management of LUTS/BPH.
    Keywords:  Lower urinary tract symptoms; complex I; oxidative phosphorylation; prostate; urology
    DOI:  https://doi.org/10.1093/gerona/glad222
  21. Oncogenesis. 2023 Sep 21. 12(1): 46
    AIFM2 promotes hepatocellular carcinoma metastasis by enhancing mitochondrial biogenesis through activation of SIRT1/PGC-1α signaling.
    Sanxing Guo, Fengying Li, Yixuan Liang, Yufei Zheng, Yingyi Mo, Deyao Zhao, Zhixiong Jiang, Mengmeng Cui, Lixia Qi, Jiaxing Chen, Lixin Wan, Guoyong Chen, Sidong Wei, Qi Yang, Junqi Liu.
      AIFM2 is a crucial NADH oxidase involved in the regulation of cytosolic NAD+. However, the role of AIFM2 in the progression of human cancers remains largely unexplored. Here, we elucidated the clinical implications, biological functions, and molecular mechanisms of AIFM2 in hepatocellular carcinoma (HCC). We found that AIFM2 is significantly upregulated in HCC, which is most probably caused by DNA hypomethylation and downregulation of miR-150-5p. High expression of AIFM2 is markedly associated with poor survival in patients with HCC. Knockdown of AIFM2 significantly impaired, while forced expression of AIFM2 enhanced the metastasis of HCC both in vitro and in vivo. Mechanistically, increased mitochondrial biogenesis and oxidative phosphorylation by activation of SIRT1/PGC-1α signaling contributed to the promotion of metastasis by AIFM2 in HCC. In conclusion, AIFM2 upregulation plays a crucial role in the promotion of HCC metastasis by activating SIRT1/PGC-1α signaling, which strongly suggests that AIFM2 could be targeted for the treatment of HCC.
    DOI:  https://doi.org/10.1038/s41389-023-00491-1
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