bims-mibica 2024-05-05 papers

bims-mibica

Biomed News

on Mitochondrial bioenergetics in cancer

Issue of 2024–05–05
24 papers selected by
Kelsey Fisher-Wellman, East Carolina University

A novel inhibitor of the mitochondrial respiratory complex I with uncoupling properties exerts potent antitumor activity.
Inhibition of mammalian mtDNA transcription acts paradoxically to reverse diet-induced hepatosteatosis and obesity.
Mitochondrial genome transfer drives metabolic reprogramming in adjacent colonic epithelial cells promoting TGFβ1-mediated tumor progression.
A dynamin superfamily-like pseudoenzyme coordinates with MICOS to promote cristae architecture.
Characterizing OXPHOS inhibitor-mediated alleviation of hypoxia using high-throughput live cell-imaging.
An aldehyde-crosslinking mitochondrial probe for STED imaging in fixed cells.
OTUB2 silencing promotes ovarian cancer via mitochondrial metabolic reprogramming and can be synthetically targeted by CA9 inhibition.
Dual targeting of glutamine and serine metabolism in acute myeloid leukemia.
Assessment of Mitochondrial Oxygen Consumption Using a Plate Reader-based Fluorescent Assay.
Cycling back to folate metabolism in cancer.
Tumor mitochondrial oxidative phosphorylation stimulated by the nuclear receptor RORγ represents an effective therapeutic opportunity in osteosarcoma.
Unprocessed genomic uracil as a source of DNA replication stress in cancer cells.
NLRX1: a key regulator in mitochondrial respiration and colorectal cancer progression.
Mitochondria and Cancer.
Key residues in the VDAC2-BAK complex can be targeted to modulate apoptosis.
Dietary dicarboxylic acids provide a non-storable alternative fat source that protects mice against obesity.
Metabolic signature and response to glutamine deprivation are independent of p53 status in B cell malignancies.
Discovery of the Clinical Candidate Sonrotoclax (BGB-11417), a Highly Potent and Selective Inhibitor for Both WT and G101V Mutant Bcl-2.
The mitochondrial multi-omic response to exercise training across rat tissues.
PARKIN is not required to sustain OXPHOS function in adult mammalian tissues.
ONC212 enhances YM155 cytotoxicity by triggering SLC35F2 expression and NOXA-dependent MCL1 degradation in acute myeloid leukemia cells.
Hallmarks of cancer stemness.
Acetate reprogrammes tumour metabolism and promotes PD-L1 expression and immune evasion by upregulating c-Myc.
Efficacy of Venetoclax and Azacitidine in Acute Myeloid Leukemia Compared to Azacitidine Monotherapy: Real-World Experience.

Cell Death Dis. 2024 May 02. 15(5): 311

A novel inhibitor of the mitochondrial respiratory complex I with uncoupling properties exerts potent antitumor activity.

Alaa Al Assi, Solène Posty, Frédéric Lamarche, Amel Chebel, Jérôme Guitton, Cécile Cottet-Rousselle, Renaud Prudent, Laurence Lafanechère, Stéphane Giraud, Patrick Dallemagne, Peggy Suzanne, Aurélie Verney, Laurent Genestier, Marie Castets, Eric Fontaine, Marc Billaud, Martine Cordier-Bussat.

Cancer cells are highly dependent on bioenergetic processes to support their growth and survival. Disruption of metabolic pathways, particularly by targeting the mitochondrial electron transport chain complexes (ETC-I to V) has become an attractive therapeutic strategy. As a result, the search for clinically effective new respiratory chain inhibitors with minimized adverse effects is a major goal. Here, we characterize a new OXPHOS inhibitor compound called MS-L6, which behaves as an inhibitor of ETC-I, combining inhibition of NADH oxidation and uncoupling effect. MS-L6 is effective on both intact and sub-mitochondrial particles, indicating that its efficacy does not depend on its accumulation within the mitochondria. MS-L6 reduces ATP synthesis and induces a metabolic shift with increased glucose consumption and lactate production in cancer cell lines. MS-L6 either dose-dependently inhibits cell proliferation or induces cell death in a variety of cancer cell lines, including B-cell and T-cell lymphomas as well as pediatric sarcoma. Ectopic expression of Saccharomyces cerevisiae NADH dehydrogenase (NDI-1) partially restores the viability of B-lymphoma cells treated with MS-L6, demonstrating that the inhibition of NADH oxidation is functionally linked to its cytotoxic effect. Furthermore, MS-L6 administration induces robust inhibition of lymphoma tumor growth in two murine xenograft models without toxicity. Thus, our data present MS-L6 as an inhibitor of OXPHOS, with a dual mechanism of action on the respiratory chain and with potent antitumor properties in preclinical models, positioning it as the pioneering member of a promising drug class to be evaluated for cancer therapy. MS-L6 exerts dual mitochondrial effects: ETC-I inhibition and uncoupling of OXPHOS. In cancer cells, MS-L6 inhibited ETC-I at least 5 times more than in isolated rat hepatocytes. These mitochondrial effects lead to energy collapse in cancer cells, resulting in proliferation arrest and cell death. In contrast, hepatocytes which completely and rapidly inactivated this molecule, restored their energy status and survived exposure to MS-L6 without apparent toxicity.

DOI: https://doi.org/10.1038/s41419-024-06668-9
Nat Metab. 2024 Apr 30.

Inhibition of mammalian mtDNA transcription acts paradoxically to reverse diet-induced hepatosteatosis and obesity.

Shan Jiang, Taolin Yuan, Florian A Rosenberger, Arnaud Mourier, Nathalia R V Dragano, Laura S Kremer, Diana Rubalcava-Gracia, Fynn M Hansen, Melissa Borg, Mara Mennuni, Roberta Filograna, David Alsina, Jelena Misic, Camilla Koolmeister, Polyxeni Papadea, Martin Hrabe de Angelis, Lipeng Ren, Olov Andersson, Anke Unger, Tim Bergbrede, Raffaella Di Lucrezia, Rolf Wibom, Juleen R Zierath, Anna Krook, Patrick Giavalisco, Matthias Mann, Nils-Göran Larsson.

The oxidative phosphorylation system1 in mammalian mitochondria plays a key role in transducing energy from ingested nutrients2. Mitochondrial metabolism is dynamic and can be reprogrammed to support both catabolic and anabolic reactions, depending on physiological demands or disease states. Rewiring of mitochondrial metabolism is intricately linked to metabolic diseases and promotes tumour growth3-5. Here, we demonstrate that oral treatment with an inhibitor of mitochondrial transcription (IMT)6 shifts whole-animal metabolism towards fatty acid oxidation, which, in turn, leads to rapid normalization of body weight, reversal of hepatosteatosis and restoration of normal glucose tolerance in male mice on a high-fat diet. Paradoxically, the IMT treatment causes a severe reduction of oxidative phosphorylation capacity concomitant with marked upregulation of fatty acid oxidation in the liver, as determined by proteomics and metabolomics analyses. The IMT treatment leads to a marked reduction of complex I, the main dehydrogenase feeding electrons into the ubiquinone (Q) pool, whereas the levels of electron transfer flavoprotein dehydrogenase and other dehydrogenases connected to the Q pool are increased. This rewiring of metabolism caused by reduced mtDNA expression in the liver provides a principle for drug treatment of obesity and obesity-related pathology.

DOI: https://doi.org/10.1038/s42255-024-01038-3
Nat Commun. 2024 Apr 30. 15(1): 3653

Mitochondrial genome transfer drives metabolic reprogramming in adjacent colonic epithelial cells promoting TGFβ1-mediated tumor progression.

Bingjie Guan, Youdong Liu, Bowen Xie, Senlin Zhao, Abudushalamu Yalikun, Weiwei Chen, Menghua Zhou, Qi Gu, Dongwang Yan.

Although nontumor components play an essential role in colon cancer (CC) progression, the intercellular communication between CC cells and adjacent colonic epithelial cells (CECs) remains poorly understood. Here, we show that intact mitochondrial genome (mitochondrial DNA, mtDNA) is enriched in serum extracellular vesicles (EVs) from CC patients and positively correlated with tumor stage. Intriguingly, circular mtDNA transferred via tumor cell-derived EVs (EV-mtDNA) enhances mitochondrial respiration and reactive oxygen species (ROS) production in CECs. Moreover, the EV-mtDNA increases TGFβ1 expression in CECs, which in turn promotes tumor progression. Mechanistically, the intercellular mtDNA transfer activates the mitochondrial respiratory chain to induce the ROS-driven RelA nuclear translocation in CECs, thereby transcriptionally regulating TGFβ1 expression and promoting tumor progression via the TGFβ/Smad pathway. Hence, this study highlights EV-mtDNA as a major driver of paracrine metabolic crosstalk between CC cells and adjacent CECs, possibly identifying it as a potential biomarker and therapeutic target for CC.

DOI: https://doi.org/10.1038/s41467-024-48100-y
Curr Biol. 2024 Apr 24. pii: S0960-9822(24)00468-8. [Epub ahead of print]

A dynamin superfamily-like pseudoenzyme coordinates with MICOS to promote cristae architecture.

Abhishek Kumar, Mehmet Oguz Gok, Kailey N Nguyen, Olivia M Connor, Michael L Reese, Jeremy G Wideman, Sergio A Muñoz-Gómez, Jonathan R Friedman.

  Mitochondrial cristae architecture is crucial for optimal respiratory function of the organelle. Cristae shape is maintained in part by the mitochondrial contact site and cristae organizing system (MICOS) complex. While MICOS is required for normal cristae morphology, the precise mechanistic role of each of the seven human MICOS subunits, and how the complex coordinates with other cristae-shaping factors, has not been fully determined. Here, we examine the MICOS complex in Schizosaccharomyces pombe, a minimal model whose genome only encodes for four core subunits. Using an unbiased proteomics approach, we identify a poorly characterized inner mitochondrial membrane protein that interacts with MICOS and is required to maintain cristae morphology, which we name Mmc1. We demonstrate that Mmc1 works in concert with MICOS to promote normal mitochondrial morphology and respiratory function. Mmc1 is a distant relative of the dynamin superfamily of proteins (DSPs), GTPases, which are well established to shape and remodel membranes. Similar to DSPs, Mmc1 self-associates and forms high-molecular-weight assemblies. Interestingly, however, Mmc1 is a pseudoenzyme that lacks key residues required for GTP binding and hydrolysis, suggesting that it does not dynamically remodel membranes. These data are consistent with the model that Mmc1 stabilizes cristae architecture by acting as a scaffold to support cristae ultrastructure on the matrix side of the inner membrane. Our study reveals a new class of proteins that evolved early in fungal phylogeny and is required for the maintenance of cristae architecture. This highlights the possibility that functionally analogous proteins work with MICOS to establish cristae morphology in metazoans.

Keywords:  MICOS; cristae; dynamin; fission yeast; membrane remodeling; mitochondria; pseudoenzyme

DOI:  https://doi.org/10.1016/j.cub.2024.04.028
Cancer Metab. 2024 May 03. 12(1): 13

Characterizing OXPHOS inhibitor-mediated alleviation of hypoxia using high-throughput live cell-imaging.

Anne P M Beerkens, Daan F Boreel, James A Nathan, Jiri Neuzil, Gang Cheng, Balaraman Kalyanaraman, Micael Hardy, Gosse J Adema, Sandra Heskamp, Paul N Span, Johan Bussink.

   BACKGROUND: Hypoxia is a common feature of many solid tumors and causes radiotherapy and immunotherapy resistance. Pharmacological inhibition of oxidative phosphorylation (OXPHOS) has emerged as a therapeutic strategy to reduce hypoxia. However, the OXPHOS inhibitors tested in clinical trials caused only moderate responses in hypoxia alleviation or trials were terminated due to dose-limiting toxicities. To improve the therapeutic benefit, FDA approved OXPHOS inhibitors (e.g. atovaquone) were conjugated to triphenylphosphonium (TPP+) to preferentially target cancer cell's mitochondria. In this study, we evaluated the hypoxia reducing effects of several mitochondria-targeted OXPHOS inhibitors and compared them to non-mitochondria-targeted OXPHOS inhibitors using newly developed spheroid models for diffusion-limited hypoxia.
METHODS: B16OVA murine melanoma cells and MC38 murine colon cancer cells expressing a HIF-Responsive Element (HRE)-induced Green Fluorescent Protein (GFP) with an oxygen-dependent degradation domain (HRE-eGFP-ODD) were generated to assess diffusion-limited hypoxia dynamics in spheroids. Spheroids were treated with IACS-010759, atovaquone, metformin, tamoxifen or with mitochondria-targeted atovaquone (Mito-ATO), PEGylated mitochondria-targeted atovaquone (Mito-PEG-ATO) or mitochondria-targeted tamoxifen (MitoTam). Hypoxia dynamics were followed and quantified over time using the IncuCyte Zoom Live Cell-Imaging system.
RESULTS: Hypoxic cores developed in B16OVA.HRE and MC38.HRE spheroids within 24 h hours after seeding. Treatment with IACS-010759, metformin, atovaquone, Mito-PEG-ATO and MitoTam showed a dose-dependent reduction of hypoxia in both B16OVA.HRE and MC38.HRE spheroids. Mito-ATO only alleviated hypoxia in MC38.HRE spheroids while tamoxifen was not able to reduce hypoxia in any of the spheroid models. The mitochondria-targeted OXPHOS inhibitors demonstrated stronger anti-hypoxic effects compared to the non-mito-targeted OXPHOS inhibitors.
CONCLUSIONS: We successfully developed a high-throughput spheroid model in which hypoxia dynamics can be quantified over time. Using this model, we showed that the mitochondria-targeted OXPHOS inhibitors Mito-ATO, Mito-PEG-ATO and MitoTam reduce hypoxia in tumor cells in a dose-dependent manner, potentially sensitizing hypoxic tumor cells for radiotherapy.

Keywords:  Hypoxia; Live cell imaging; Metabolic reprogramming; Mitochondria-targeting; OXPHOS inhibitors; Spheroids

DOI:  https://doi.org/10.1186/s40170-024-00342-6
Proc Natl Acad Sci U S A. 2024 May 07. 121(19): e2317703121

An aldehyde-crosslinking mitochondrial probe for STED imaging in fixed cells.

Jingting Chen, Till Stephan, Felix Gaedke, Tianyan Liu, Yiyan Li, Astrid Schauss, Peng Chen, Veronika Wulff, Stefan Jakobs, Christian Jüngst, Zhixing Chen.

  Fluorescence labeling of chemically fixed specimens, especially immunolabeling, plays a vital role in super-resolution imaging as it offers a convenient way to visualize cellular structures like mitochondria or the distribution of biomolecules with high detail. Despite the development of various distinct probes that enable super-resolved stimulated emission depletion (STED) imaging of mitochondria in live cells, most of these membrane-potential-dependent fluorophores cannot be retained well in mitochondria after chemical fixation. This lack of suitable mitochondrial probes has limited STED imaging of mitochondria to live cell samples. In this study, we introduce a mitochondria-specific probe, PK Mito Orange FX (PKMO FX), which features a fixation-driven cross-linking motif and accumulates in the mitochondrial inner membrane. It exhibits high fluorescence retention after chemical fixation and efficient depletion at 775 nm, enabling nanoscopic imaging both before and after aldehyde fixation. We demonstrate the compatibility of this probe with conventional immunolabeling and other strategies commonly used for fluorescence labeling of fixed samples. Moreover, we show that PKMO FX facilitates correlative super-resolution light and electron microscopy, enabling the correlation of multicolor fluorescence images and transmission EM images via the characteristic mitochondrial pattern. Our probe further expands the mitochondrial toolkit for multimodal microscopy at nanometer resolutions.

Keywords:  CLEM; fixation; mitochondrial imaging; super-resolution imaging

DOI:  https://doi.org/10.1073/pnas.2317703121
Proc Natl Acad Sci U S A. 2024 May 07. 121(19): e2315348121

OTUB2 silencing promotes ovarian cancer via mitochondrial metabolic reprogramming and can be synthetically targeted by CA9 inhibition.

Yabing Nan, Xiaowei Wu, Qingyu Luo, Wan Chang, Pengfei Zhao, Lingqiang Zhang, Zhihua Liu.

  Ovarian cancer is an aggressive gynecological tumor characterized by a high relapse rate and chemoresistance. Ovarian cancer exhibits the cancer hallmark of elevated glycolysis, yet effective strategies targeting cancer cell metabolic reprogramming to overcome therapeutic resistance in ovarian cancer remain elusive. Here, we revealed that epigenetic silencing of Otubain 2 (OTUB2) is a driving force for mitochondrial metabolic reprogramming in ovarian cancer, which promotes tumorigenesis and chemoresistance. Mechanistically, OTUB2 silencing destabilizes sorting nexin 29 pseudogene 2 (SNX29P2), which subsequently prevents hypoxia-inducible factor-1 alpha (HIF-1α) from von Hippel-Lindau tumor suppressor-mediated degradation. Elevated HIF-1α activates the transcription of carbonic anhydrase 9 (CA9) and drives ovarian cancer progression and chemoresistance by promoting glycolysis. Importantly, pharmacological inhibition of CA9 substantially suppressed tumor growth and synergized with carboplatin in the treatment of OTUB2-silenced ovarian cancer. Thus, our study highlights the pivotal role of OTUB2/SNX29P2 in suppressing ovarian cancer development and proposes that targeting CA9-mediated glycolysis is an encouraging strategy for the treatment of ovarian cancer.

Keywords:  chemoresistance; metabolic reprogramming; ovarian cancer; tumorigenesis; ubiquitination

DOI:  https://doi.org/10.1073/pnas.2315348121
Front Oncol. 2024 ;14 1326754

Dual targeting of glutamine and serine metabolism in acute myeloid leukemia.

Kanwal M Hameed, Dominique R Bollino, Amol C Shetty, Brandon Carter-Cooper, Rena G Lapidus, Ashkan Emadi.

  Acute myeloid leukemia (AML) is a heterogeneous hematological malignancy characterized by disrupted blood cell production and function. Recent investigations have highlighted the potential of targeting glutamine metabolism as a promising therapeutic approach for AML. Asparaginases, enzymes that deplete circulating glutamine and asparagine, are approved for the treatment of acute lymphoblastic leukemia, but are also under investigation in AML, with promising results. We previously reported an elevation in plasma serine levels following treatment with Erwinia-derived asparaginase (also called crisantaspase). This led us to hypothesize that AML cells initiate the de novo serine biosynthesis pathway in response to crisantaspase treatment and that inhibiting this pathway in combination with crisantaspase would enhance AML cell death. Here we report that in AML cell lines, treatment with the clinically available crisantaspase, Rylaze, upregulates the serine biosynthesis enzymes phosphoglycerate dehydrogenase (PHGDH) and phosphoserine aminotransferase (PSAT1) through activation of the Amino Acid Response (AAR) pathway, a cellular stress response mechanism that regulates amino acid metabolism and protein synthesis under conditions of nutrient limitation. Inhibition of serine biosynthesis through CRISPR-Cas9-mediated knockout of PHGDH resulted in a ~250-fold reduction in the half-maximal inhibitory concentration (IC50) for Rylaze, indicating heightened sensitivity to crisantaspase therapy. Treatment of AML cells with a combination of Rylaze and a small molecule inhibitor of PHGDH (BI4916) revealed synergistic anti-proliferative effects in both cell lines and primary AML patient samples. Rylaze-BI4916 treatment in AML cell lines led to the inhibition of cap-dependent mRNA translation and protein synthesis, as well as a marked decrease in intracellular glutathione levels, a critical cellular antioxidant. Collectively, our results highlight the clinical potential of targeting serine biosynthesis in combination with crisantaspase as a novel therapeutic strategy for AML.

Keywords:  asparaginase; cancer metabolism; glutamine; leukemia; serine

DOI:  https://doi.org/10.3389/fonc.2024.1326754
J Vis Exp. 2024 Apr 12.

Assessment of Mitochondrial Oxygen Consumption Using a Plate Reader-based Fluorescent Assay.

Victoria Del Gaizo Moore, Gregory Haenel, Aiofe Judge.

Mitochondria serve many important functions, including cellular respiration, ATP production, controlling apoptosis, and acting as a central hub of metabolic pathways. Therefore, experimentally assessing mitochondrial functionality can provide insight into variations among different populations or disease states. Additionally, it is valuable to assess whether isolated mitochondria are healthy enough to proceed with experiments. One characteristic often used to compare mitochondrial function in different samples is the rate of oxygen consumption. Oxygen consumption and subsequent calculation of the respiratory control ratio in either intact cells or mitochondria isolated from tissue can serve all three purposes. Using mitochondria isolated from the livers of brush lizards in conjunction with a phosphorescent probe that is sensitive to the fluctuations in oxygen concentration of a solution, we measured oxygen consumption using a fluorescent plate reader. This method is not only quick and efficient but also can be conducted with a small amount of mitochondria and without the need for specialized equipment. The step-by-step protocol described here increases the accessibility of mitochondrial functional assessment to researchers.

DOI: https://doi.org/10.3791/65760
Nat Cancer. 2024 May 02.

Cycling back to folate metabolism in cancer.

Younghwan Lee, Karen H Vousden, Marc Hennequart.

Metabolic changes contribute to cancer initiation and progression through effects on cancer cells, the tumor microenvironment and whole-body metabolism. Alterations in serine metabolism and the control of one-carbon cycles have emerged as critical for the development of many tumor types. In this Review, we focus on the mitochondrial folate cycle. We discuss recent evidence that, in addition to supporting nucleotide synthesis, mitochondrial folate metabolism also contributes to metastasis through support of antioxidant defense, mitochondrial protein synthesis and the overflow of excess formate. These observations offer potential therapeutic opportunities, including the modulation of formate metabolism through dietary interventions and the use of circulating folate cycle metabolites as biomarkers for cancer detection.

DOI: https://doi.org/10.1038/s43018-024-00739-8
Cell Rep Med. 2024 Apr 24. pii: S2666-3791(24)00188-5. [Epub ahead of print] 101519

Tumor mitochondrial oxidative phosphorylation stimulated by the nuclear receptor RORγ represents an effective therapeutic opportunity in osteosarcoma.

Jianwei Zheng, Qianqian Wang, Jianghe Chen, Guodi Cai, Zhenhua Zhang, Hongye Zou, June X Zou, Qianqian Liu, Shufeng Ji, Guoli Shao, Hong Li, Sheng Li, Hong-Wu Chen, LinLin Lu, Yanqiu Yuan, Peiqing Liu, Junjian Wang.

Osteosarcoma (OS) is the most common malignant bone tumor with a poor prognosis. Here, we show that the nuclear receptor RORγ may serve as a potential therapeutic target in OS. OS exhibits a hyperactivated oxidative phosphorylation (OXPHOS) program, which fuels the carbon source to promote tumor progression. We found that RORγ is overexpressed in OS tumors and is linked to hyperactivated OXPHOS. RORγ induces the expression of PGC-1β and physically interacts with it to activate the OXPHOS program by upregulating the expression of respiratory chain component genes. Inhibition of RORγ strongly inhibits OXPHOS activation, downregulates mitochondrial functions, and increases ROS production, which results in OS cell apoptosis and ferroptosis. RORγ inverse agonists strongly suppressed OS tumor growth and progression and sensitized OS tumors to chemotherapy. Taken together, our results indicate that RORγ is a critical regulator of the OXPHOS program in OS and provides an effective therapeutic strategy for this deadly disease.

DOI: https://doi.org/10.1016/j.xcrm.2024.101519
Mol Cell. 2024 Apr 22. pii: S1097-2765(24)00282-X. [Epub ahead of print]

Unprocessed genomic uracil as a source of DNA replication stress in cancer cells.

Sneha Saxena, Christopher S Nabel, Turner W Seay, Parasvi S Patel, Ajinkya S Kawale, Caroline R Crosby, Helene Tigro, Eugene Oh, Matthew G Vander Heiden, Aaron N Hata, Zucai Suo, Lee Zou.

  Alterations of bases in DNA constitute a major source of genomic instability. It is believed that base alterations trigger base excision repair (BER), generating DNA repair intermediates interfering with DNA replication. Here, we show that genomic uracil, a common type of base alteration, induces DNA replication stress (RS) without being processed by BER. In the absence of uracil DNA glycosylase (UNG), genomic uracil accumulates to high levels, DNA replication forks slow down, and PrimPol-mediated repriming is enhanced, generating single-stranded gaps in nascent DNA. ATR inhibition in UNG-deficient cells blocks the repair of uracil-induced gaps, increasing replication fork collapse and cell death. Notably, a subset of cancer cells upregulates UNG2 to suppress genomic uracil and limit RS, and these cancer cells are hypersensitive to co-treatment with ATR inhibitors and drugs increasing genomic uracil. These results reveal unprocessed genomic uracil as an unexpected source of RS and a targetable vulnerability of cancer cells.

Keywords:  ATR; BER; PrimPol; UNG; cancer therapy; gaps; lung cancer; permetrexed; replication fork; replication stress; ssDNA gaps; synthetic lethality; uracil

DOI:  https://doi.org/10.1016/j.molcel.2024.04.004
Med Oncol. 2024 Apr 29. 41(6): 131

NLRX1: a key regulator in mitochondrial respiration and colorectal cancer progression.

Yaxin Ding, Wenjie Sun, Mingwei Han, Ziyu Liu, Huarui Kang, Xiaohan Ma, Jiayu Wang, Hongrui Mu, Yuxiao Huang, Shiyuan Hou, Danni Sun, Xing Shen, Xingan Wu, Rongrong Liu.

  Colorectal cancer (CRC) is a prevalent and aggressive malignancy with high mortality rates and significant risks to human well-being. Population-wide screening for tumor suppressor genes and oncogenes shows promise for reducing the incidence and fatality of CRC. Recent studies have suggested that NLRX1, an innate immunity suppressor, may play a role in regulating chronic inflammation and tumorigenesis. However, further investigation is needed to understand the specific role of NLRX1 in CRC. To evaluate the impact of NLRX1 on migration, invasion, and metastasis, two human colon cancer cell lines were studied in vitro. Additionally, a knockout mouse tumor-bearing model was used to validate the inhibitory effect of NLRX1 on tumor emergence and progression. The Seahorse XF96 technology was employed to assess mitochondrial function and glycolysis in colorectal cancer cells overexpressing NLRX1. Moreover, public databases were consulted to analyze gene and protein expression levels of NLRX1. Finally, the results were validated using a series of CRC patient samples. Our findings demonstrate that downregulation of NLRX1 enhances proliferation, colony formation, and tumor-forming capacity in HCT116 and LoVo cells. Conversely, overexpression of NLRX1 negatively impacts basal respiration and mitochondrial ATP-linked respiration in both cell lines, resulting in a notable decrease in maximal respiration during the standard mitochondrial stress test. Furthermore, analysis of data from the TCGA database reveals a significant reduction in NLRX1 expression in colon and rectal cancer tissues compared to normal tissues. This result was validated using clinical samples, where immunohistochemistry staining and western blotting demonstrated a notable reduction in NLRX1 protein levels in CRC compared to adjacent normal tissues. The decreased expression of NLRX1 may serve as a significant prognostic indicator and diagnostic biomarker for CRC patients.

Keywords:  Colorectal cancer; Diagnostic biomarker; NLRX1; Oxidative medicine

DOI:  https://doi.org/10.1007/s12032-024-02364-y
Cold Spring Harb Perspect Med. 2024 May 01. pii: a041534. [Epub ahead of print]

Mitochondria and Cancer.

Timothy C Kenny, Kıvanç Birsoy.

Mitochondria are semiautonomous organelles with diverse metabolic and cellular functions including anabolism and energy production through oxidative phosphorylation. Following the pioneering observations of Otto Warburg nearly a century ago, an immense body of work has examined the role of mitochondria in cancer pathogenesis and progression. Here, we summarize the current state of the field, which has coalesced around the position that functional mitochondria are required for cancer cell proliferation. In this review, we discuss how mitochondria influence tumorigenesis by impacting anabolism, intracellular signaling, and the tumor microenvironment. Consistent with their critical functions in tumor formation, mitochondria have become an attractive target for cancer therapy. We provide a comprehensive update on the numerous therapeutic modalities targeting the mitochondria of cancer cells making their way through clinical trials.

DOI: https://doi.org/10.1101/cshperspect.a041534
PLoS Biol. 2024 May 02. 22(5): e3002617

Key residues in the VDAC2-BAK complex can be targeted to modulate apoptosis.

Zheng Yuan, Mark F van Delft, Mark Xiang Li, Fransisca Sumardy, Brian J Smith, David C S Huang, Guillaume Lessene, Yelena Khakam, Ruitao Jin, Sitong He, Nicholas A Smith, Richard W Birkinshaw, Peter E Czabotar, Grant Dewson.

BAK and BAX execute intrinsic apoptosis by permeabilising the mitochondrial outer membrane. Their activity is regulated through interactions with pro-survival BCL-2 family proteins and with non-BCL-2 proteins including the mitochondrial porin VDAC2. VDAC2 is important for bringing both BAK and BAX to mitochondria where they execute their apoptotic function. Despite this important function in apoptosis, while interactions with pro-survival family members are well characterised and have culminated in the development of drugs that target these interfaces to induce cancer cell apoptosis, the interaction between BAK and VDAC2 remains largely undefined. Deep scanning mutagenesis coupled with cysteine linkage identified key residues in the interaction between BAK and VDAC2. Obstructive labelling of specific residues in the BH3 domain or hydrophobic groove of BAK disrupted this interaction. Conversely, mutating specific residues in a cytosol-exposed region of VDAC2 stabilised the interaction with BAK and inhibited BAK apoptotic activity. Thus, this VDAC2-BAK interaction site can potentially be targeted to either inhibit BAK-mediated apoptosis in scenarios where excessive apoptosis contributes to disease or to promote BAK-mediated apoptosis for cancer therapy.

DOI: https://doi.org/10.1371/journal.pbio.3002617
J Clin Invest. 2024 Apr 30. pii: e174186. [Epub ahead of print]

Dietary dicarboxylic acids provide a non-storable alternative fat source that protects mice against obesity.

Eric S Goetzman, Bob B Zhang, Yuxun Zhang, Sivakama S Bharathi, Joanna Bons, Jacob Rose, Samah Shah, Keaton J Solo, Alexandra V Schmidt, Adam C Richert, Steven J Mullett, Stacy L Gelhaus, Krithika S Rao, Sruti S Shiva, Katherine E Pfister, Anne Silva Barbosa, Sunder Sims-Lucas, Steven F Dobrowolski, Birgit Schilling.

  Dicarboxylic fatty acids are generated in the liver and kidney in a minor pathway called fatty acid ω-oxidation. The effects of consuming dicarboxylic fatty acids as an alternative source of dietary fat have not been explored. Here, we fed dodecanedioic acid, a 12-carbon dicarboxylic (DC12), to mice at 20% of daily caloric intake for nine weeks. DC12 increased metabolic rate, reduced body fat, reduced liver fat, and improved glucose tolerance. We observed DC12-specific breakdown products in liver, kidney, muscle, heart, and brain, indicating that oral DC12 escaped first-pass liver metabolism and was utilized by many tissues. In tissues expressing the "a" isoform of acyl-CoA oxidase-1 (ACOX1), a key peroxisomal fatty acid oxidation enzyme, DC12 was chain shortened to the TCA cycle intermediate succinyl-CoA. In tissues with low peroxisomal fatty acid oxidation capacity, DC12 was oxidized by mitochondria. In vitro, DC12 was catabolized even by adipose tissue and was not stored intracellularly. We conclude that DC12 and other dicarboxylic acids may be useful for combatting obesity and for treating metabolic disorders.

Keywords:  Fatty acid oxidation; Metabolism; Mitochondria; Obesity

DOI:  https://doi.org/10.1172/JCI174186
iScience. 2024 May 17. 27(5): 109640

Metabolic signature and response to glutamine deprivation are independent of p53 status in B cell malignancies.

Chiara Montironi, Zhenghao Chen, Ingrid A M Derks, Gaspard Cretenet, Esmée A Krap, Eric Eldering, Helga Simon-Molas.

  The tumor suppressor p53 has been described to control various aspects of metabolic reprogramming in solid tumors, but in B cell malignancies that role is as yet unknown. We generated pairs of p53 functional and knockout (KO) clones from distinct B cell malignancies (acute lymphoblastic leukemia, chronic lymphocytic leukemia, diffuse large B cell lymphoma, and multiple myeloma). Metabolomics and isotope tracing showed that p53 loss did not drive a common metabolic signature. Instead, cell lines segregated according to cell of origin. Next, we focused on glutamine as a crucial energy source in the B cell tumor microenvironment. In both TP53 wild-type and KO cells, glutamine deprivation induced cell death through the integrated stress response, via CHOP/ATF4. Lastly, combining BH3 mimetic drugs with glutamine starvation emerged as a possibility to target resistant clones. In conclusion, our analyses do not support a common metabolic signature of p53 deficiency in B cell malignancies and suggest therapeutic options for exploration based on glutamine dependency.

Keywords:  Cancer; Cell biology; Metabolomics; Microenvironment

DOI:  https://doi.org/10.1016/j.isci.2024.109640
J Med Chem. 2024 May 02.

Discovery of the Clinical Candidate Sonrotoclax (BGB-11417), a Highly Potent and Selective Inhibitor for Both WT and G101V Mutant Bcl-2.

Yunhang Guo, Hai Xue, Nan Hu, Ye Liu, Hanzi Sun, Desheng Yu, Ling Qin, Gongyin Shi, Fan Wang, Lei Xin, Weihua Sun, Fan Zhang, Xiaomin Song, Shuran Li, Qiang Wei, Ying Guo, Yong Li, Xiaoxin Liu, Shuaishuai Chen, Taichang Zhang, Yue Wu, Dan Su, Yutong Zhu, Aiying Xu, Haipeng Xu, Shasha Yang, Zhijun Zheng, Junhua Liu, Xuefei Yang, Xi Yuan, Yuan Hong, Xuebing Sun, Yin Guo, Changyou Zhou, Xuesong Liu, Lai Wang, Zhiwei Wang.

The approval of venetoclax, a B-cell lymphoma-2 (Bcl-2) selective inhibitor, for the treatment of chronic lymphocytic leukemia demonstrated that the antiapoptotic protein Bcl-2 is a druggable target for B-cell malignancies. However, venetoclax's limited potency cannot produce a strong, durable clinical benefit in other Bcl-2-mediated malignancies (e.g., diffuse large B-cell lymphomas) and multiple recurrent Bcl-2 mutations (e.g., G101V) have been reported to mediate resistance to venetoclax after long-term treatment. Herein, we described novel Bcl-2 inhibitors with increased potency for both wild-type (WT) and mutant Bcl-2. Comprehensive structure optimization led to the clinical candidate BGB-11417 (compound 12e, sonrotoclax), which exhibits strong in vitro and in vivo inhibitory activity against both WT Bcl-2 and the G101V mutant, as well as excellent selectivity over Bcl-xL without obvious cytochrome P450 inhibition. Currently, BGB-11417 is undergoing phase II/III clinical assessments as monotherapy and combination treatment.

DOI: https://doi.org/10.1021/acs.jmedchem.4c00027
Cell Metab. 2024 Apr 15. pii: S1550-4131(23)00472-2. [Epub ahead of print]

The mitochondrial multi-omic response to exercise training across rat tissues.

MoTrPAC Study Group

  Mitochondria have diverse functions critical to whole-body metabolic homeostasis. Endurance training alters mitochondrial activity, but systematic characterization of these adaptations is lacking. Here, the Molecular Transducers of Physical Activity Consortium mapped the temporal, multi-omic changes in mitochondrial analytes across 19 tissues in male and female rats trained for 1, 2, 4, or 8 weeks. Training elicited substantial changes in the adrenal gland, brown adipose, colon, heart, and skeletal muscle. The colon showed non-linear response dynamics, whereas mitochondrial pathways were downregulated in brown adipose and adrenal tissues. Protein acetylation increased in the liver, with a shift in lipid metabolism, whereas oxidative proteins increased in striated muscles. Exercise-upregulated networks were downregulated in human diabetes and cirrhosis. Knockdown of the central network protein 17-beta-hydroxysteroid dehydrogenase 10 (HSD17B10) elevated oxygen consumption, indicative of metabolic stress. We provide a multi-omic, multi-tissue, temporal atlas of the mitochondrial response to exercise training and identify candidates linked to mitochondrial dysfunction.

Keywords:  HSD17B10; acetylome; aerobic; exercise; metabolism; metabolomics; mitochondria; multi-omics; proteomics; transcriptomics

DOI:  https://doi.org/10.1016/j.cmet.2023.12.021
NPJ Parkinsons Dis. 2024 Apr 29. 10(1): 93

PARKIN is not required to sustain OXPHOS function in adult mammalian tissues.

Roberta Filograna, Jule Gerlach, Hae-Na Choi, Giovanni Rigoni, Michela Barbaro, Mikael Oscarson, Seungmin Lee, Katarina Tiklova, Markus Ringnér, Camilla Koolmeister, Rolf Wibom, Sara Riggare, Inger Nennesmo, Thomas Perlmann, Anna Wredenberg, Anna Wedell, Elisa Motori, Per Svenningsson, Nils-Göran Larsson.

Loss-of-function variants in the PRKN gene encoding the ubiquitin E3 ligase PARKIN cause autosomal recessive early-onset Parkinson's disease (PD). Extensive in vitro and in vivo studies have reported that PARKIN is involved in multiple pathways of mitochondrial quality control, including mitochondrial degradation and biogenesis. However, these findings are surrounded by substantial controversy due to conflicting experimental data. In addition, the existing PARKIN-deficient mouse models have failed to faithfully recapitulate PD phenotypes. Therefore, we have investigated the mitochondrial role of PARKIN during ageing and in response to stress by employing a series of conditional Parkin knockout mice. We report that PARKIN loss does not affect oxidative phosphorylation (OXPHOS) capacity and mitochondrial DNA (mtDNA) levels in the brain, heart, and skeletal muscle of aged mice. We also demonstrate that PARKIN deficiency does not exacerbate the brain defects and the pro-inflammatory phenotype observed in mice carrying high levels of mtDNA mutations. To rule out compensatory mechanisms activated during embryonic development of Parkin-deficient mice, we generated a mouse model where loss of PARKIN was induced in adult dopaminergic (DA) neurons. Surprisingly, also these mice did not show motor impairment or neurodegeneration, and no major transcriptional changes were found in isolated midbrain DA neurons. Finally, we report a patient with compound heterozygous PRKN pathogenic variants that lacks PARKIN and has developed PD. The PARKIN deficiency did not impair OXPHOS activities or induce mitochondrial pathology in skeletal muscle from the patient. Altogether, our results argue that PARKIN is dispensable for OXPHOS function in adult mammalian tissues.

DOI: https://doi.org/10.1038/s41531-024-00707-0
Biochem Pharmacol. 2024 Apr 26. pii: S0006-2952(24)00225-9. [Epub ahead of print]224 116242

ONC212 enhances YM155 cytotoxicity by triggering SLC35F2 expression and NOXA-dependent MCL1 degradation in acute myeloid leukemia cells.

Jing-Ting Chiou, Long-Sen Chang.

  Although the anticancer activity of ONC212 has been reported, the precise mechanism underlying its apoptotic effects remains unclear. In this study, we investigated the apoptotic mechanism of ONC212 in acute myeloid leukemia (AML) cells. ONC212 induces apoptosis, MCL1 downregulation, and mitochondrial depolarization in AML U937 cells. Ectopic MCL1 expression alleviates mitochondria-mediated apoptosis in ONC212-treated U937 cells. ONC212 triggers AKT phosphorylation, inducing NOX4-dependent ROS production and promoting HuR transcription. HuR-mediated ATF4 mRNA stabilization stimulates NOXA and SLC35F2 expression; ONC212-induced upregulation of NOXA leads to MCL1 degradation. The synergistic effect of ONC212 on YM155 cytotoxicity was dependent on increased SLC35F2 expression. In addition, YM155 feedback facilitated the activation of the ONC212-induced signaling pathway. A similar mechanism explains ONC212- and ONC212/YM155-induced AML HL-60 cell death. The continuous treatment of U937 cells with the benzene metabolite hydroquinone (HQ) generated U937/HQ cells, exhibiting enhanced responsiveness to the cytotoxic effects of ONC212. In U937/HQ cells, ONC212 triggered apoptosis through NOXA-mediated MCL1 downregulation, enhancing YM155 cytotoxicity. Collectively, our data suggested that ONC212 upregulated SLC35F2 expression and triggered NOXA-mediated MCL1 degradation in U937, U937/HQ, and HL-60 cells by activating the AKT/NOX4/HuR/ATF4 pathway. The ONC212-induced signaling pathway showed anti-AML activity and enhanced YM155 cytotoxicity.

Keywords:  Acute myeloid leukemia; NOXA-dependent MCL1 degradation; ONC212; SLC35F2; Synergistic cytotoxicity of YM155

DOI:  https://doi.org/10.1016/j.bcp.2024.116242
Cell Stem Cell. 2024 May 02. pii: S1934-5909(24)00131-0. [Epub ahead of print]31(5): 617-639

Hallmarks of cancer stemness.

Jia-Jian Loh, Stephanie Ma.

  Cancer stemness is recognized as a key component of tumor development. Previously coined "cancer stem cells" (CSCs) and believed to be a rare population with rigid hierarchical organization, there is good evidence to suggest that these cells exhibit a plastic cellular state influenced by dynamic CSC-niche interplay. This revelation underscores the need to reevaluate the hallmarks of cancer stemness. Herein, we summarize the techniques used to identify and characterize the state of these cells and discuss their defining and emerging hallmarks, along with their enabling and associated features. We also highlight potential future directions in this field of research.

Keywords:  cancer cell plasticity; cancer stem cells; cancer stemness; immunosuppression; metastasis; self-renewal; tumor microenvironment; tumor recurrence; tumor-initiating cells

DOI:  https://doi.org/10.1016/j.stem.2024.04.004
Nat Metab. 2024 May 03.

Acetate reprogrammes tumour metabolism and promotes PD-L1 expression and immune evasion by upregulating c-Myc.

Juhong Wang, Yannan Yang, Fei Shao, Ying Meng, Dong Guo, Jie He, Zhimin Lu.

Acetate, a precursor of acetyl-CoA, is instrumental in energy production, lipid synthesis and protein acetylation. However, whether acetate reprogrammes tumour metabolism and plays a role in tumour immune evasion remains unclear. Here, we show that acetate is the most abundant short-chain fatty acid in human non-small cell lung cancer tissues, with increased tumour-enriched acetate uptake. Acetate-derived acetyl-CoA induces c-Myc acetylation, which is mediated by the moonlighting function of the metabolic enzyme dihydrolipoamide S-acetyltransferase. Acetylated c-Myc increases its stability and subsequent transcription of the genes encoding programmed death-ligand 1, glycolytic enzymes, monocarboxylate transporter 1 and cell cycle accelerators. Dietary acetate supplementation promotes tumour growth and inhibits CD8+ T cell infiltration, whereas disruption of acetate uptake inhibits immune evasion, which increases the efficacy of anti-PD-1-based therapy. These findings highlight a critical role of acetate promoting tumour growth beyond its metabolic role as a carbon source by reprogramming tumour metabolism and immune evasion, and underscore the potential of controlling acetate metabolism to curb tumour growth and improve the response to immune checkpoint blockade therapy.

DOI: https://doi.org/10.1038/s42255-024-01037-4
Anticancer Res. 2024 May;44(5): 2003-2007

Efficacy of Venetoclax and Azacitidine in Acute Myeloid Leukemia Compared to Azacitidine Monotherapy: Real-World Experience.

Yuta Baba, Noriko Hida, Takehiko Sambe, Maasa Abe, Nobuyuki Kabasawa, Hirotaka Sakai, Kiyoshi Yoshimura, Tetsuya Fukuda.

   BACKGROUND/AIM: The combination of venetoclax (VEN) and azacitidine (AZA) (VEN+AZA) leads to higher complete remission rates and longer overall survival (OS) in patients with untreated acute myeloid leukemia (AML) who are ineligible for intensive combination chemotherapy. In practice, the doses of VEN and AZA are reduced at the attending physician's discretion to avoid adverse events; however, the impact of dose and duration reductions has not been fully clarified. We analyzed whether the efficacy was maintained with reduced VEN+AZA compared to AZA monotherapy in the real world.
PATIENTS AND METHODS: A total of 33 patients were included; 17 (10 newly diagnosed, 7 primary refractory or relapsed) received VEN+AZA, and 16 (7 newly diagnosed, 9 primary refractory or relapsed) received AZA. We analyzed complete remission (CR) and CR with incomplete hematologic recovery (CRi) rates, OS, and the incidence of adverse events.
RESULTS: CR/CRi were achieved in 7/17 (41.2%) and 11/17 (64.7%) patients in the VEN+AZA group and 0/15 (0%) and 2/15 (6.7%) patients in the AZA group, respectively. The CR/CRi rate was higher in the VEN+AZA group than in the AZA group (p=0.001). OS was longer in the VEN+AZA group than in the AZA group (p=0.03), with a median of 506 days [95% confidence interval (CI)=234-585 days] and 208 days (95% CI=52-343 days), respectively.
CONCLUSION: The doses of the VEN+AZA combination were reduced at the attending physician's discretion, resulting in a higher CR/CRi rate and longer OS than AZA monotherapy and is considered useful for AML in the real world.

Keywords:  Venetoclax; acute myeloid leukemia; azacitidine; real-world experience; reduction rate

DOI:  https://doi.org/10.21873/anticanres.17003