bims-mibica 2024-04-21 papers

bims-mibica

Biomed News

on Mitochondrial bioenergetics in cancer

Issue of 2024‒04‒21
29 papers selected by
Kelsey Fisher-Wellman, East Carolina University

Enhanced ROS Production in Mitochondria from Prematurely Aging mtDNA Mutator Mice.
MARCH5 promotes aerobic glycolysis to facilitate ovarian cancer progression via ubiquitinating MPC1.
The emerging importance of the α-keto acid dehydrogenase complexes in serving as intracellular and intercellular signaling platforms for the regulation of metabolism.
Bisbiguanide analogs induce mitochondrial stress to inhibit lung cancer cell invasion.
De novo purine metabolism is a metabolic vulnerability of cancers with low p16 expression.
High-resolution In-situ Structures of Mammalian Mitochondrial Respiratory Supercomplexes in Reaction within Native Mitochondria.
The role of lipoylation in mitochondrial adaptation to methionine restriction.
Mcl-1 mediates intrinsic resistance to RAF inhibitors in mutant BRAF papillary thyroid carcinoma.
ULK1-dependent phosphorylation of PKM2 antagonizes O-GlcNAcylation and regulates the Warburg effect in breast cancer.
OMA1 clears traffic jam in TOM tunnel in mammals.
ABCG2 and SLC1A5 functionally interact to rewire metabolism and confer a survival advantage to cancer cells under oxidative stress.
Diet and Cancer Metabolism.
Rapid HPLC method reveals dynamic shifts in coenzyme Q redox state.
Deuterium metabolic imaging differentiates glioblastoma metabolic subtypes and detects early response to chemoradiotherapy.
Recharacterization of RSL3 reveals that the selenoproteome is a druggable target in colorectal cancer.
Iron regulates the quiescence of naive CD4 T cells by controlling mitochondria and cellular metabolism.
Nano-flow cytometry unveils mitochondrial permeability transition process and multi-pathway cell death induction for cancer therapy.
The selective prolyl hydroxylase inhibitor IOX5 stabilizes HIF-1α and compromises development and progression of acute myeloid leukemia.
Altered lactate/pyruvate ratio may be responsible for aging-associated intestinal barrier dysfunction in male rats.
SIRT3 suppression resulting from the enhanced β-catenin signaling drives glycolysis and promotes hypoxia-induced cell growth in hepatocellular carcinoma cells.
SIRT3 negatively regulates TFH cell differentiation in cancer.
Context-dependent roles for ubiquitous mitochondrial creatine kinase CKMT1 in breast cancer progression.
Identification of a novel form of caspase-independent cell death triggered by BH3-mimetics in diffuse large B-cell lymphoma cell lines.
Progression of herpesvirus infection remodels mitochondrial organization and metabolism.
Cross-link assisted spatial proteomics to map sub-organelle proteomes and membrane protein topologies.
Colorectal cancer cells with stably expressed SIRT3 demonstrate proliferating retardation by Wnt/β-catenin cascade inactivation.
Metabolic difference between patient-derived xenograft model of pancreatic ductal adenocarcinoma and corresponding primary tumor.
Inhibition of NRF2 signaling overcomes acquired resistance to arsenic trioxide in FLT3-mutated Acute Myeloid Leukemia.
The genetic landscape of a metabolic interaction.

Biochemistry (Mosc). 2024 Feb;89(2): 279-298

Enhanced ROS Production in Mitochondria from Prematurely Aging mtDNA Mutator Mice.

Irina G Shabalina, Daniel Edgar, Natalia Gibanova, Anastasia V Kalinovich, Natasa Petrovic, Mikhail Yu Vyssokikh, Barbara Cannon, Jan Nedergaard.

  An increase in mitochondrial DNA (mtDNA) mutations and an ensuing increase in mitochondrial reactive oxygen species (ROS) production have been suggested to be a cause of the aging process ("the mitochondrial hypothesis of aging"). In agreement with this, mtDNA-mutator mice accumulate a large amount of mtDNA mutations, giving rise to defective mitochondria and an accelerated aging phenotype. However, incongruously, the rates of ROS production in mtDNA mutator mitochondria have generally earlier been reported to be lower - not higher - than in wildtype, thus apparently invalidating the "mitochondrial hypothesis of aging". We have here re-examined ROS production rates in mtDNA-mutator mice mitochondria. Using traditional conditions for measuring ROS (succinate in the absence of rotenone), we indeed found lower ROS in the mtDNA-mutator mitochondria compared to wildtype. This ROS mainly results from reverse electron flow driven by the membrane potential, but the membrane potential reached in the isolated mtDNA-mutator mitochondria was 33 mV lower than that in wildtype mitochondria, due to the feedback inhibition of succinate oxidation by oxaloacetate, and to a lower oxidative capacity in the mtDNA-mutator mice, explaining the lower ROS production. In contrast, in normal forward electron flow systems (pyruvate (or glutamate) + malate or palmitoyl-CoA + carnitine), mitochondrial ROS production was higher in the mtDNA-mutator mitochondria. Particularly, even during active oxidative phosphorylation (as would be ongoing physiologically), higher ROS rates were seen in the mtDNA-mutator mitochondria than in wildtype. Thus, when examined under physiological conditions, mitochondrial ROS production rates are indeed increased in mtDNA-mutator mitochondria. While this does not prove the validity of the mitochondrial hypothesis of aging, it may no longer be said to be negated in this respect. This paper is dedicated to the memory of Professor Vladimir P. Skulachev.

Keywords:  ROS production; aging; membrane potential; mtDNA mutator mice; oxidative phosphorylation; succinate

DOI:  https://doi.org/10.1134/S0006297924020081
Apoptosis. 2024 Apr 13.

MARCH5 promotes aerobic glycolysis to facilitate ovarian cancer progression via ubiquitinating MPC1.

Ying Xu, Shuhua Zhao, Yujie Shen, Yuanfeng Li, Yinghui Dang, Fenfen Guo, Zhihao Chen, Jia Li, Hong Yang.

  MARCH5 is a ring-finger E3 ubiquitin ligase located in the outer membrane of mitochondria. A previous study has reported that MARCH5 was up-regulated and contributed to the migration and invasion of OC cells by serving as a competing endogenous RNA. However, as a mitochondrial localized E3 ubiquitin ligase, the function of MARCH5 in mitochondrial-associated metabolism reprogramming in human cancers remains largely unexplored, including OC. We first assessed the glycolysis effect of MARCH5 in OC both in vitro and in vivo. Then we analyzed the effect of MARCH5 knockdown or overexpression on respiratory activity by evaluating oxygen consumption rate, activities of OXPHOS complexes and production of ATP in OC cells with MARCH5. Co-immunoprecipitation, western-blot, and in vitro and vivo experiments were performed to investigate the molecular mechanisms underlying MARCH5-enhanced aerobic glycolysis s in OC. In this study, we demonstrate that the abnormal upregulation of MARCH5 is accompanied by significantly increased aerobic glycolysis in OC. Mechanistically, MARCH5 promotes aerobic glycolysis via ubiquitinating and degrading mitochondrial pyruvate carrier 1 (MPC1), which mediates the transport of cytosolic pyruvate into mitochondria by localizing on mitochondria outer membrane. In line with this, MPC1 expression is significantly decreased and its downregulation is closely correlated with unfavorable survival. Furthermore, in vitro and in vivo assays revealed that MARCH5 upregulation-enhanced aerobic glycolysis played a critical role in the proliferation and metastasis of OC cells. Taken together, we identify a MARCH5-regulated aerobic glycolysis mechanism by degradation of MPC1, and provide a rationale for therapeutic targeting of aerobic glycolysis via MARCH5-MPC1 axis inhibition.

Keywords:  Glycolysis; Growth; Membrane associated ring finger protein 5; Metastasis; OC

DOI:  https://doi.org/10.1007/s10495-024-01962-5
Redox Biol. 2024 Apr 10. pii: S2213-2317(24)00131-9. [Epub ahead of print]72 103155

The emerging importance of the α-keto acid dehydrogenase complexes in serving as intracellular and intercellular signaling platforms for the regulation of metabolism.

Ryan J Mailloux.

The α-keto acid dehydrogenase complex (KDHc) class of mitochondrial enzymes is composed of four members: pyruvate dehydrogenase (PDHc), α-ketoglutarate dehydrogenase (KGDHc), branched-chain keto acid dehydrogenase (BCKDHc), and 2-oxoadipate dehydrogenase (OADHc). These enzyme complexes occupy critical metabolic intersections that connect monosaccharide, amino acid, and fatty acid metabolism to Krebs cycle flux and oxidative phosphorylation (OxPhos). This feature also imbues KDHc enzymes with the heightened capacity to serve as platforms for propagation of intracellular and intercellular signaling. KDHc enzymes serve as a source and sink for mitochondrial hydrogen peroxide (mtH2O2), a vital second messenger used to trigger oxidative eustress pathways. Notably, deactivation of KDHc enzymes through reversible oxidation by mtH2O2 and other electrophiles modulates the availability of several Krebs cycle intermediates and related metabolites which serve as powerful intracellular and intercellular messengers. The KDHc enzymes also play important roles in the modulation of mitochondrial metabolism and epigenetic programming in the nucleus through the provision of various acyl-CoAs, which are used to acylate proteinaceous lysine residues. Intriguingly, nucleosomal control by acylation is also achieved through PDHc and KGDHc localization to the nuclear lumen. In this review, I discuss emerging concepts in the signaling roles fulfilled by the KDHc complexes. I highlight their vital function in serving as mitochondrial redox sensors and how this function can be used by cells to regulate the availability of critical metabolites required in cell signaling. Coupled with this, I describe in detail how defects in KDHc function can cause disease states through the disruption of cell redox homeodynamics and the deregulation of metabolic signaling. Finally, I propose that the intracellular and intercellular signaling functions of the KDHc enzymes are controlled through the reversible redox modification of the vicinal lipoic acid thiols in the E2 subunit of the complexes.

DOI: https://doi.org/10.1016/j.redox.2024.103155
iScience. 2024 Apr 19. 27(4): 109591

Bisbiguanide analogs induce mitochondrial stress to inhibit lung cancer cell invasion.

Christina M Knippler, Jamie L Arnst, Isaac E Robinson, Veronika Matsuk, Tala O Khatib, R Donald Harvey, Mala Shanmugam, Janna K Mouw, Haian Fu, Thota Ganesh, Adam I Marcus.

  Targeting cancer metabolism to limit cellular energy and metabolite production is an attractive therapeutic approach. Here, we developed analogs of the bisbiguanide, alexidine, to target lung cancer cell metabolism and assess a structure-activity relationship (SAR). The SAR led to the identification of two analogs, AX-4 and AX-7, that limit cell growth via G1/G0 cell-cycle arrest and are tolerated in vivo with favorable pharmacokinetics. Mechanistic evaluation revealed that AX-4 and AX-7 induce potent mitochondrial defects; mitochondrial cristae were deformed and the mitochondrial membrane potential was depolarized. Additionally, cell metabolism was rewired, as indicated by reduced oxygen consumption and mitochondrial ATP production, with an increase in extracellular lactate. Importantly, AX-4 and AX-7 impacted overall cell behavior, as these compounds reduced collective cell invasion. Taken together, our study establishes a class of bisbiguanides as effective mitochondria and cell invasion disrupters, and proposes bisbiguanides as promising approaches to limiting cancer metastasis.

Keywords:  Cancer; Cell biology; Cellular physiology

DOI:  https://doi.org/10.1016/j.isci.2024.109591
Cancer Res Commun. 2024 Apr 16.

De novo purine metabolism is a metabolic vulnerability of cancers with low p16 expression.

Naveen Kumar Tangudu, Raquel Buj, Hui Wang, Jiefei Wang, Aidan R Cole, Apoorva Uboveja, Richard Fang, Amandine Amalric, Baixue Yang, Adam Chatoff, Claudia V Crispim, Peter Sajjakulnukit, Maureen A Lyons, Kristine Cooper, Nadine Hempel, Costas A Lyssiotis, Uma R Chandran, Nathaniel W Snyder, Katherine M Aird.

p16 is a tumor suppressor encoded by the CDKN2A gene whose expression is lost in ~50% of all human cancers. In its canonical role, p16 inhibits the G1-S phase cell cycle progression through suppression of cyclin dependent kinases. Interestingly, p16 also has roles in metabolic reprogramming, and we previously published that loss of p16 promotes nucleotide synthesis via the pentose phosphate pathway. However, the broader impact of p16/CDKN2A loss on other nucleotide metabolic pathways and potential therapeutic targets remains unexplored. Using CRISPR KO libraries in isogenic human and mouse melanoma cell lines, we determined several nucleotide metabolism genes essential for the survival of cells with loss of p16/CDKN2A. Consistently, many of these genes are upregulated in melanoma cells with p16 knockdown or endogenously low CDKN2A expression. We determined that cells with low p16/CDKN2A expression are sensitive to multiple inhibitors of de novo purine synthesis, including anti-folates. Finally, tumors with p16 knockdown were more sensitive to the anti-folate methotrexate in vivo than control tumors. Together, our data provide evidence to reevaluate the utility of these drugs in patients with p16/CDKN2Alow tumors as loss of p16/CDKN2A may provide a therapeutic window for these agents.

DOI: https://doi.org/10.1158/2767-9764.CRC-23-0450
bioRxiv. 2024 Apr 03. pii: 2024.04.02.587796. [Epub ahead of print]

High-resolution In-situ Structures of Mammalian Mitochondrial Respiratory Supercomplexes in Reaction within Native Mitochondria.

Wan Zheng, Pengxin Chai, Jiapeng Zhu, Kai Zhang.

Mitochondria play a pivotal role in ATP energy production through oxidative phosphorylation, which occurs within the inner membrane via a series of respiratory complexes. Despite extensive in-vitro structural studies, revealing the atomic details of their molecular mechanisms in physiological states remains a major challenge, primarily because of the loss of the native environment during purification. Here, we directly image porcine mitochondria using an in-situ cryo-electron microscopy approach. This enables us to determine the structures of various high-order assemblies of respiratory supercomplexes in their native states, achieving up to 1.8-Å local resolution. We identify four major supercomplex organizations: I1III2IV1, I1III2IV2, I2III2IV2, and I2III4IV2, which can potentially expand into higher-order arrays on the inner membranes. The formation of these diverse supercomplexes is largely contributed by 'protein-lipids-protein' interactions, which in turn dramatically impact the local geometry of the surrounding membranes. Our in-situ structures also capture numerous reactive intermediates within these respiratory supercomplexes, shedding light on the dynamic processes of the ubiquinone/ubiquinol exchange mechanism in complex I and the Q-cycle in complex III. By comparing supercomplex structures from mitochondria treated under distinct conditions, we elucidate how conformational changes and ligand binding states interplay between complexes I and III in response to environmental redox alterations. Our approach, by preserving the native membrane environment, enables structural studies of mitochondrial respiratory supercomplexes in reaction at high resolution across multiple scales, spanning from atomic-level details to the broader subcellular context.

DOI: https://doi.org/10.1101/2024.04.02.587796
Bioessays. 2024 Apr 14. e2300218

The role of lipoylation in mitochondrial adaptation to methionine restriction.

Jingyuan Xue, Cunqi Ye.

  Dietary methionine restriction (MR) is associated with a spectrum of health-promoting benefits. Being conducive to prevention of chronic diseases and extension of life span, MR can activate integrated responses at metabolic, transcriptional, and physiological levels. However, how the mitochondria of MR influence metabolic phenotypes remains elusive. Here, we provide a summary of cellular functions of methionine metabolism and an overview of the current understanding of effector mechanisms of MR, with a focus on the aspect of mitochondria-mediated responses. We propose that mitochondria can sense and respond to MR through a modulatory role of lipoylation, a mitochondrial protein modification sensitized by MR.

Keywords:  cellular metabolism; lipidomics; metabolomics; methioinine metabolism; phospholipid

DOI:  https://doi.org/10.1002/bies.202300218
Cell Death Discov. 2024 Apr 15. 10(1): 175

Mcl-1 mediates intrinsic resistance to RAF inhibitors in mutant BRAF papillary thyroid carcinoma.

Maria R Cavallo, Jacob C Yo, Kayla C Gallant, Camille J Cunanan, Amirali Amirfallah, Marzieh Daniali, Alyssa B Sanders, Andrew E Aplin, Edmund A Pribitkin, Edward J Hartsough.

Papillary thyroid carcinoma (PTC) is the most frequent form of thyroid cancer. PTC commonly presents with mutations of the serine/threonine kinase BRAF (BRAFV600E), which drive ERK1/2 pathway activation to support growth and suppress apoptosis. PTC patients often undergo surgical resection; however, since the average age of PTC patients is under 50, adverse effects associated with prolonged maintenance therapy following total thyroidectomy are a concern. The development of mutant-selective BRAF inhibitors (BRAFi), like vemurafenib, has been efficacious in patients with metastatic melanoma, but the response rate is low for mutant BRAF PTC patients. Here, we assay the therapeutic response of BRAFi in a panel of human PTC cell lines and freshly biopsied patient samples. We observed heterogeneous responses to BRAFi, and multi-omic comparisons between susceptible and resistant mutant BRAF PTC revealed overrepresented stress response pathways and the absence of compensatory RTK activation - features that may underpin innate resistance. Importantly, resistant cell lines and patient samples had increased hallmarks of failed apoptosis; a cellular state defined by sublethal caspase activation and DNA damage. Further analysis suggests that the failed apoptotic phenotypes may have features of "minority mitochondrial outer membrane permeabilization (MOMP)" - a stress-related response characterized by fragmented and porous mitochondria known to contribute to cancer aggressiveness. We found that cells presenting with minority MOMP-like phenotypes are dependent on the apoptotic regulator, Mcl-1, as treatment with the Mcl-1 inhibitor, AZD5991, potently induced cell death in resistant cells. Furthermore, PI3K/AKT inhibitors sensitized resistant cells to BRAFi; an effect that was at least in part associated with reduced Mcl-1 levels. Together, these data implicate minority MOMP as a mechanism associated with intrinsic drug resistance and underscore the benefits of targeting Mcl-1 in mutant BRAF PTC.

DOI: https://doi.org/10.1038/s41420-024-01945-0
Oncogene. 2024 Apr 17.

ULK1-dependent phosphorylation of PKM2 antagonizes O-GlcNAcylation and regulates the Warburg effect in breast cancer.

Zibin Zhou, Xiyuan Zheng, Jianxin Zhao, Aiyun Yuan, Zhuan Lv, Guangcan Shao, Bin Peng, Meng-Qiu Dong, Quan Xu, Xingzhi Xu, Jing Li.

Pyruvate kinase M2 (PKM2) is a central metabolic enzyme driving the Warburg effect in tumor growth. Previous investigations have demonstrated that PKM2 is subject to O-linked β-N-acetylglucosamine (O-GlcNAc) modification, which is a nutrient-sensitive post-translational modification. Here we found that unc-51 like autophagy activating kinase 1 (ULK1), a glucose-sensitive kinase, interacts with PKM2 and phosphorylates PKM2 at Ser333. Ser333 phosphorylation antagonizes PKM2 O-GlcNAcylation, promotes its tetramer formation and enzymatic activity, and decreases its nuclear localization. As PKM2 is known to have a nuclear role in regulating c-Myc, we also show that PKM2-S333 phosphorylation inhibits c-Myc expression. By downregulating glucose consumption and lactate production, PKM2 pS333 attenuates the Warburg effect. Through mouse xenograft assays, we demonstrate that the phospho-deficient PKM2-S333A mutant promotes tumor growth in vivo. In conclusion, we identified a ULK1-PKM2-c-Myc axis in inhibiting breast cancer, and a glucose-sensitive phosphorylation of PKM2 in modulating the Warburg effect.

DOI: https://doi.org/10.1038/s41388-024-03035-y
J Cell Biol. 2024 May 06. pii: e202403190. [Epub ahead of print]223(5):

OMA1 clears traffic jam in TOM tunnel in mammals.

Shiori Sekine, Yusuke Sekine.

Using an engineered mitochondrial clogger, Krakowczyk et al. (https://doi.org/10.1083/jcb.202306051) identified the OMA1 protease as a critical component that eliminates import failure at the TOM translocase in mammalian cells, providing a novel quality control mechanism that is distinct from those described in yeast.

DOI: https://doi.org/10.1083/jcb.202403190
J Biol Chem. 2024 Apr 17. pii: S0021-9258(24)01800-3. [Epub ahead of print] 107299

ABCG2 and SLC1A5 functionally interact to rewire metabolism and confer a survival advantage to cancer cells under oxidative stress.

Jia Shi, Kirk Pabon, Rui Ding, Kathleen W Scotto.

ABCG2, a member of the ABC transporter superfamily, is overexpressed in many human tumors and has long been studied for its ability to export a variety of chemotherapeutic agents, thereby conferring a multidrug resistance (MDR) phenotype. However, several studies have shown that ABCG2 can also confer an MDR-independent survival advantage to tumor cells exposed to stress. While investigating the mechanism by which ABCG2 enhances survival in stressful milieus, we have identified a physical and functional interaction between ABCG2 and SLC1A5, a member of the solute transporter superfamily and the primary transporter of glutamine in cancer cells. This interaction was accompanied by increased glutamine uptake, increased glutaminolysis and rewired cellular metabolism, as evidenced by an increase in key metabolic enzymes and alteration of glutamine-dependent metabolic pathways. Specifically, we observed an increase in glutamine metabolites shuttled to the TCA cycle, an increase in the synthesis of glutathione, accompanied by a decrease in basal levels of reactive oxygen species and a marked increase in cell survival in the face of oxidative stress. Notably, knockdown of SLC1A5 or depletion of exogenous glutamine diminished ABCG2-enhanced autophagy flux, further implicating this solute transporter in ABCG2-mediated cell survival. This is, to our knowledge, the first report of a functionally significant physical interaction between members of the two major transporter superfamilies. Moreover, these observations may underlie the protective role of ABCG2 in cancer cells under duress and suggest a novel role for ABCG2 in the regulation of metabolism in normal and diseased states.

DOI: https://doi.org/10.1016/j.jbc.2024.107299
Cold Spring Harb Perspect Med. 2024 Apr 15. pii: a041549. [Epub ahead of print]

Diet and Cancer Metabolism.

Jason W Locasale, Marcus D Goncalves, Maira Di Tano, Guillermo Burgos-Barragan.

Diet and exercise are modifiable lifestyle factors known to have a major influence on metabolism. Clinical practice addresses diseases of altered metabolism such as diabetes or hypertension by altering these factors. Despite enormous public interest, there are limited defined diet and exercise regimens for cancer patients. Nevertheless, the molecular basis of cancer has converged over the past 15 years on an essential role for altered metabolism in cancer. However, our understanding of the molecular mechanisms that underlie the impact of diet and exercise on cancer metabolism is in its very early stages. In this work, we propose conceptual frameworks for understanding the consequences of diet and exercise on cancer cell metabolism and tumor biology and also highlight recent developments. By advancing our mechanistic understanding, we also discuss actionable ways that such interventions could eventually reach the mainstay of both medical oncology and cancer control and prevention.

DOI: https://doi.org/10.1101/cshperspect.a041549
J Biol Chem. 2024 Apr 17. pii: S0021-9258(24)01802-7. [Epub ahead of print] 107301

Rapid HPLC method reveals dynamic shifts in coenzyme Q redox state.

Victor Vitvitsky, Roshan Kumar, Jutta Diessl, David A Hanna, Ruma Banerjee.

Ubiquinol or coenzyme Q (CoQ) is a lipid-soluble electron carrier in the respiratory chain and an electron acceptor for various enzymes in metabolic pathways that intersect at this cofactor hub in the mitochondrial inner membrane. The reduced form of CoQ is an antioxidant, which protects against lipid peroxidation. In this study, we have optimized a UV-detected HPLC method for CoQ analysis from biological materials, which involves a rapid single-step extraction into n-propanol followed by direct sample injection onto a column. Using this method, we have measured the oxidized, reduced and total CoQ pools, and monitored shifts in the CoQ redox status in response to cell culture conditions and bioenergetic perturbations. We find that hypoxia or sulfide exposure induces a reductive shift in the intracellular CoQ pool. The effect of hypoxia is however, rapidly reversed by exposure to ambient air. Interventions at different loci in the electron transport chain can induce sizeable redox shifts in the oxidative or reductive direction, depending on whether they are up- or downstream of complex III. We have also used this method to confirm that CoQ levels are higher and more reduced in murine heart versus brain. In summary, the availability of a convenient HPLC-based method described herein, will facilitate studies on CoQ redox dynamics in response to environmental, nutritional and endogenous alterations.

DOI: https://doi.org/10.1016/j.jbc.2024.107301
Cancer Res. 2024 Apr 18.

Deuterium metabolic imaging differentiates glioblastoma metabolic subtypes and detects early response to chemoradiotherapy.

Jacob Chen Ming Low, Jianbo Cao, Friederike Hesse, Alan J Wright, Anastasia Tsyben, Islam Alshamleh, Richard Mair, Kevin M Brindle.

Metabolic subtypes of glioblastoma have different prognoses and responses to treatment. Deuterium metabolic imaging with 2H-labeled substrates is a potential approach to stratify patients into metabolic subtypes for targeted treatment. Here, we used 2H magnetic resonance spectroscopy (MRS) and spectroscopic imaging (MRSI) measurements of [6,6'-2H2]glucose metabolism to identify metabolic subtypes and their responses to chemoradiotherapy in patient-derived glioblastoma xenografts in vivo. The metabolism of patient-derived cells was first characterized in vitro by measuring the oxygen consumption rate, a marker of mitochondrial TCA cycle activity, as well as the extracellular acidification rate and 2H-labeled lactate production from [6,6'-2H2]glucose, which are markers of glycolytic activity. Two cell lines representative of a glycolytic subtype and two representative of a mitochondrial subtype were identified. 2H MRS and MRSI measurements showed similar concentrations of 2H-labeled glucose from [6,6'-2H2]glucose in all four tumor models when implanted orthotopically in mice. The glycolytic subtypes showed higher concentrations of 2H-labeled lactate than the mitochondrial subtypes and normal-appearing brain tissue, whereas the mitochondrial subtypes showed more glutamate/glutamine labeling, a surrogate for TCA cycle activity, than the glycolytic subtypes and normal-appearing brain tissue. The response of the tumors to chemoradiation could be detected within 24 hours of treatment completion, with the mitochondrial subtypes showing a decrease in both 2H-labeled glutamate/glutamine and lactate concentrations and glycolytic tumors showing a decrease in 2H-labeled lactate concentration. This technique has the potential to be used clinically for treatment selection and early detection of treatment response.

DOI: https://doi.org/10.1158/0008-5472.CAN-23-2552
bioRxiv. 2024 Apr 01. pii: 2024.03.29.587381. [Epub ahead of print]

Recharacterization of RSL3 reveals that the selenoproteome is a druggable target in colorectal cancer.

Stephen L DeAngelo, Sofia Dziechciarz, Sumeet Solanki, Myungsun Shin, Liang Zhao, Andrii Balia, Marwa O El-Derany, Nupur K Das, Cristina Castillo, Hannah N Bell, Joao A Paulo, Yuezhong Zhang, Nicholas J Rossiter, Elizabeth C McCulla, Jianping He, Indrani Talukder, Zachary T Schafer, Nouri Neamati, Joseph D Mancias, Markos Koutmos, Yatrik M Shah.

Ferroptosis is an iron-dependent, non-apoptotic form of cell death resulting from the accumulation of lipid peroxides. Colorectal cancer (CRC) accumulates high levels of intracellular iron and reactive oxygen species (ROS), thereby sensitizing cells to ferroptosis. The selenoprotein glutathione peroxidase (GPx4) is a key enzyme in the detoxification of lipid peroxides and can be inhibited by the compound (S)-RSL3 ([1S,3R]-RSL3). However, the stereoisomer (R)-RSL3 ([1R,3R]-RSL3), which does not inhibit GPx4, exhibits equipotent activity to (S)-RSL3 across a panel of CRC cell lines. Utilizing CRC cell lines with an inducible knockdown of GPx4, we demonstrate that (S)-RSL3 sensitivity does not align with GPx4 dependency. Subsequently, a biotinylated (S)-RSL3 was then synthesized to perform affinity purification-mass spectrometry (AP-MS), revealing that (S)-RSL3 acts as a pan-inhibitor of the selenoproteome, targeting both the glutathione and thioredoxin peroxidase systems as well as multiple additional selenoproteins. To investigate the therapeutic potential of broadly disrupting the selenoproteome as a therapeutic strategy in CRC, we employed further chemical and genetic approaches to disrupt selenoprotein function. The findings demonstrate that the selenoprotein inhibitor Auranofin can induce ferroptosis and/or oxidative cell death both in-vitro and in-vivo . Consistent with this data we observe that AlkBH8, a tRNA-selenocysteine methyltransferase required for the translational incorporation of selenocysteine, is essential for CRC growth. In summary, our research elucidates the complex mechanisms underlying ferroptosis in CRC and reveals that modulation of the selenoproteome provides multiple new therapeutic targets and opportunities in CRC.

DOI: https://doi.org/10.1101/2024.03.29.587381
Proc Natl Acad Sci U S A. 2024 Apr 23. 121(17): e2318420121

Iron regulates the quiescence of naive CD4 T cells by controlling mitochondria and cellular metabolism.

Ajay Kumar, Chenxian Ye, Afia Nkansah, Thomas Decoville, Garrett M Fogo, Peter Sajjakulnukit, Mack B Reynolds, Li Zhang, Osbourne Quaye, Young-Ah Seo, Thomas H Sanderson, Costas A Lyssiotis, Cheong-Hee Chang.

  In response to an immune challenge, naive T cells undergo a transition from a quiescent to an activated state acquiring the effector function. Concurrently, these T cells reprogram cellular metabolism, which is regulated by iron. We and others have shown that iron homeostasis controls proliferation and mitochondrial function, but the underlying mechanisms are poorly understood. Given that iron derived from heme makes up a large portion of the cellular iron pool, we investigated iron homeostasis in T cells using mice with a T cell-specific deletion of the heme exporter, FLVCR1 [referred to as knockout (KO)]. Our finding revealed that maintaining heme and iron homeostasis is essential to keep naive T cells in a quiescent state. KO naive CD4 T cells exhibited an iron-overloaded phenotype, with increased spontaneous proliferation and hyperactive mitochondria. This was evidenced by reduced IL-7R and IL-15R levels but increased CD5 and Nur77 expression. Upon activation, however, KO CD4 T cells have defects in proliferation, IL-2 production, and mitochondrial functions. Iron-overloaded CD4 T cells failed to induce mitochondrial iron and exhibited more fragmented mitochondria after activation, making them susceptible to ferroptosis. Iron overload also led to inefficient glycolysis and glutaminolysis but heightened activity in the hexosamine biosynthetic pathway. Overall, these findings highlight the essential role of iron in controlling mitochondrial function and cellular metabolism in naive CD4 T cells, critical for maintaining their quiescent state.

Keywords:  heme; iron; mitochondria; tonic signaling

DOI:  https://doi.org/10.1073/pnas.2318420121
Cell Death Discov. 2024 Apr 15. 10(1): 176

Nano-flow cytometry unveils mitochondrial permeability transition process and multi-pathway cell death induction for cancer therapy.

Liyun Su, Jingyi Xu, Cheng Lu, Kaimin Gao, Yunyun Hu, Chengfeng Xue, Xiaomei Yan.

Mitochondrial permeability transition (mPT)-mediated mitochondrial dysfunction plays a pivotal role in various human diseases. However, the intricate details of its mechanisms and the sequence of events remain elusive, primarily due to the interference caused by Bax/Bak-induced mitochondrial outer membrane permeabilization (MOMP). To address these, we have developed a methodology that utilizes nano-flow cytometry (nFCM) to quantitatively analyze the opening of mitochondrial permeability transition pore (mPTP), dissipation of mitochondrial membrane potential ( Δ Ψm), release of cytochrome c (Cyt c), and other molecular alternations of isolated mitochondria in response to mPT induction at the single-mitochondrion level. It was identified that betulinic acid (BetA) and antimycin A can directly induce mitochondrial dysfunction through mPT-mediated mechanisms, while cisplatin and staurosporine cannot. In addition, the nFCM analysis also revealed that BetA primarily induces mPTP opening through a reduction in Bcl-2 and Bcl-xL protein levels, along with an elevation in ROS content. Employing dose and time-dependent strategies of BetA, for the first time, we experimentally verified the sequential occurrence of mPTP opening and Δ Ψm depolarization prior to the release of Cyt c during mPT-mediated mitochondrial dysfunction. Notably, our study uncovers a simultaneous release of cell-death-associated factors, including Cyt c, AIF, PNPT1, and mtDNA during mPT, implying the initiation of multiple cell death pathways. Intriguingly, BetA induces caspase-independent cell death, even in the absence of Bax/Bak, thereby overcoming drug resistance. The presented findings offer new insights into mPT-mediated mitochondrial dysfunction using nFCM, emphasizing the potential for targeting such dysfunction in innovative cancer therapies and interventions.

DOI: https://doi.org/10.1038/s41420-024-01947-y
Nat Cancer. 2024 Apr 18.

The selective prolyl hydroxylase inhibitor IOX5 stabilizes HIF-1α and compromises development and progression of acute myeloid leukemia.

Hannah Lawson, James P Holt-Martyn, Vilma Dembitz, Yuka Kabayama, Lydia M Wang, Aarushi Bellani, Samanpreet Atwal, Nadia Saffoon, Jozef Durko, Louie N van de Lagemaat, Azzura L De Pace, Anthony Tumber, Thomas Corner, Eidarus Salah, Christine Arndt, Lennart Brewitz, Matthew Bowen, Louis Dubusse, Derek George, Lewis Allen, Amelie V Guitart, Tsz Kan Fung, Chi Wai Eric So, Juerg Schwaller, Paolo Gallipoli, Donal O'Carroll, Christopher J Schofield, Kamil R Kranc.

Acute myeloid leukemia (AML) is a largely incurable disease, for which new treatments are urgently needed. While leukemogenesis occurs in the hypoxic bone marrow, the therapeutic tractability of the hypoxia-inducible factor (HIF) system remains undefined. Given that inactivation of HIF-1α/HIF-2α promotes AML, a possible clinical strategy is to target the HIF-prolyl hydroxylases (PHDs), which promote HIF-1α/HIF-2α degradation. Here, we reveal that genetic inactivation of Phd1/Phd2 hinders AML initiation and progression, without impacting normal hematopoiesis. We investigated clinically used PHD inhibitors and a new selective PHD inhibitor (IOX5), to stabilize HIF-α in AML cells. PHD inhibition compromises AML in a HIF-1α-dependent manner to disable pro-leukemogenic pathways, re-program metabolism and induce apoptosis, in part via upregulation of BNIP3. Notably, concurrent inhibition of BCL-2 by venetoclax potentiates the anti-leukemic effect of PHD inhibition. Thus, PHD inhibition, with consequent HIF-1α stabilization, is a promising nontoxic strategy for AML, including in combination with venetoclax.

DOI: https://doi.org/10.1038/s43018-024-00761-w
Biogerontology. 2024 Apr 15.

Altered lactate/pyruvate ratio may be responsible for aging-associated intestinal barrier dysfunction in male rats.

Berrin Papila, Ayla Karimova, Ilhan Onaran.

  Some evidence points to a link between aging-related increased intestinal permeability and mitochondrial dysfunction in in-vivo models. Several studies have also demonstrated age-related accumulation of the of specific deletion 4834-bp of "common" mitochondrial DNA (mtDNA) in various rat tissues and suggest that this deletion may disrupt mitochondrial metabolism. The present study aimed to investigate possible associations among the mitochondrial DNA (mtDNA) common deletion, mitochondrial function, intestinal permeability, and aging in rats. The study was performed on the intestinal tissue from (24 months) and young (4 months) rats. mtDNA4834 deletion, mtDNA copy number, mitochondrial membrane potential, and ATP, lactate and pyruvate levels were analyzed in tissue samples. Zonulin and intestinal fatty acid-binding protein (I-FABP) levels were also evaluated in serum. Serum zonulin and I-FABP levels were significantly higher in 24-month-old rats than 4-month-old rats (p = 0.04, p = 0.026, respectively). There is not significant difference in mtDNA4834 copy levels was observed between the old and young intestinal tissues (p > 0.05). The intestinal mitochondrial DNA copy number was similar between the two age groups (p > 0.05). No significant difference was observed in ATP levels in the intestinal tissue lysates between old and young rats (p > 0.05). ATP levels in isolated mitochondria from both groups were also similar. Analysis of MMP using JC-10 in intestinal tissue mitochondria showed that mitochondrial membrane potentials (red/green ratios) were similar between the two age groups (p > 0.05). Pyruvate tended to be higher in the 24-month-old rat group and the L/P ratio was found to be approximately threefold lower in the intestinal tissue of the older rats compared to the younger rats (p < 0.002). The tissue lactate/pyruvate ratio (L/P) was three times lower in old rats than in young rats. Additionally, there were significant negative correlations between intestinal permeability parameters and L/P ratios. The intestinal tissues of aged rats are not prone to accumulate mtDNA common deletion, we suggest that this mutation does not explain the age-related increase in intestinal permeability. It seems to be more likely that altered glycolytic capacity could be a link to increased intestinal permeability with age. This observation strengthens assertions that the balance between glycolysis and mitochondrial metabolism may play a critical role in intestinal barrier functions.

Keywords:  Aging; Common deletion; Glycolysis; Intestinal permeability; Lactate; Mitochondria

DOI:  https://doi.org/10.1007/s10522-024-10102-0
Cell Cycle. 2024 Apr 16. 1-13

SIRT3 suppression resulting from the enhanced β-catenin signaling drives glycolysis and promotes hypoxia-induced cell growth in hepatocellular carcinoma cells.

Rong Ma, Qing-Yuan Gao, Zhi-Teng Chen, Guang-Hong Liao, Shu-Tai Li, Jie-Wen Cai, Nian-Sang Luo, Hao Chen, Hai-Feng Zhang.

  The precise mechanisms underlying the inhibitory effects of SIRT3, a mitochondrial sirtuin protein, on hepatocellular carcinoma (HCC) development, as well as its impact on mitochondrial respiration, remain poorly understood. We assessed sirtuins 3 (SIRT3) levels in HCC tissues and Huh7 cells cultured under hypoxic condition. We investigated the effects of SIRT3 on cell proliferation, glycolytic metabolism, mitochondrial respiration, mitophagy, and mitochondrial biogenesis in Huh7 cells. Besides, we explored the potential mechanisms regulating SIRT3 expression in hypoxically cultured Huh7 cells. Gradual reduction in SIRT3 expressions were observed in both adjacent tumor tissues and tumor tissues. Similarly, SIRT3 expressions were diminished in Huh7 cells cultured under hypoxic condition. Forced expression of SIRT3 attenuated the growth of hypoxically cultured Huh7 cells. SIRT3 overexpression led to a decrease in extracellular acidification rate while increasing oxygen consumption rate. SIRT3 downregulated the levels of hexokinase 2 and pyruvate kinase M2. Moreover, SIRT3 enhanced mitophagy signaling, as indicated by mtKeima, and upregulated key proteins involved in various mitophagic pathways while reducing intracellular reactive oxygen species levels. Furthermore, SIRT3 increased proxisome proliferator-activated receptor-gamma coactivator 1α levels and the amount of mitochondrial DNA in Huh7 cells. Notably, β-catenin expressions were elevated in Huh7 cells cultured under hypoxic condition. Antagonists and agonists of β-catenin respectively upregulated and downregulated SIRT3 expressions in hypoxically cultured Huh7 cells. The modulationsof glycolysis and mitochondrial respiration represent the primary mechanism through which SIRT3, suppressed by β-catenin, inhibits HCC cell proliferation.

Keywords:  Hepatocellular carcinoma; Sirtuins 3; glycolysis; mitochondria; β-catenin

DOI:  https://doi.org/10.1080/15384101.2024.2340864
Cancer Immunol Res. 2024 Apr 17.

SIRT3 negatively regulates TFH cell differentiation in cancer.

Yueru Hou, Yejin Cao, Ying He, Lin Dong, Longhao Zhao, Yingjie Dong, Ruiying Niu, Yujing Bi, Guangwei Liu.

Follicular helper T (TFH) cells are essential for inducing germinal center (GC) reactions to mediate humoral adaptive immunity in tumors, but the mechanisms underlying TFH cell differentiation remain unclear. Here, we found that the metabolism sensor sirtuin 3 (SIRT3) is critical for TFH cell differentiation and GC formation during tumor and viral infection. SIRT3 deficiency in CD4+ T cells intrinsically enhanced TFH cell differentiation and GC reactions during tumor and virus infection. Mechanistically, damaged oxidative phosphorylation (OXPHOS) compensatively triggered the NAD+-glycolysis pathway to provide a cellular energy supply, which was necessary for SIRT3 deficiency-induced TFH cell differentiation. Blocking NAD+ synthesis-glycolysis signaling or recovering OXPHOS activities reversed the TFH cell differentiation induced by SIRT3 deficiency. Moreover, the mTOR and HIF1α signaling axis was found to be responsible for TFH cell differentiation induced by SIRT3 deficiency. HIF1α directly interacted with and regulated the activity of the transcription factor Bcl-6. Thus, our findings identify a cellular energy compensatory mechanism, regulated by the mitochondrial sensor SIRT3, that triggers NAD+-dependent glycolysis during mitochondrial OXPHOS injuries and a mTOR-HIF1α-Bcl-6 pathway to reprogram TFH cell differentiation. These data have implications for future cancer immunotherapy research targeting SIRT3 in T cells.

DOI: https://doi.org/10.1158/2326-6066.CIR-23-0786
Cell Rep. 2024 Apr 12. pii: S2211-1247(24)00449-2. [Epub ahead of print]43(4): 114121

Context-dependent roles for ubiquitous mitochondrial creatine kinase CKMT1 in breast cancer progression.

Vinay Ayyappan, Nicole M Jenkinson, Caitlin M Tressler, Zheqiong Tan, Menglin Cheng, Xinyi Elaine Shen, Alejandro Guerrero, Kanchan Sonkar, Ruoqing Cai, Oluwatobi Adelaja, Sujayita Roy, Alan Meeker, Pedram Argani, Kristine Glunde.

  Metabolic reprogramming is a hallmark of cancer, enabling cancer cells to rapidly proliferate, invade, and metastasize. We show that creatine levels in metastatic breast cancer cell lines and secondary metastatic tumors are driven by the ubiquitous mitochondrial creatine kinase (CKMT1). We discover that, while CKMT1 is highly expressed in primary tumors and promotes cell viability, it is downregulated in metastasis. We further show that CKMT1 downregulation, as seen in breast cancer metastasis, drives up mitochondrial reactive oxygen species (ROS) levels. CKMT1 downregulation contributes to the migratory and invasive potential of cells by ROS-induced upregulation of adhesion and degradative factors, which can be reversed by antioxidant treatment. Our study thus reconciles conflicting evidence about the roles of metabolites in the creatine metabolic pathway in breast cancer progression and reveals that tight, context-dependent regulation of CKMT1 expression facilitates cell viability, cell migration, and cell invasion, which are hallmarks of metastatic spread.

Keywords:  CKMT1; CP: Cancer; CP: Metabolism; breast cancer; creatine; metabolism; metastasis; reactive oxygen species

DOI:  https://doi.org/10.1016/j.celrep.2024.114121
Cell Death Dis. 2024 Apr 15. 15(4): 266

Identification of a novel form of caspase-independent cell death triggered by BH3-mimetics in diffuse large B-cell lymphoma cell lines.

Nahide Yildirim, Lakshmi Sarojam, Victoria M Smith, Nadja M Pieper, Marius Anders, Ross A Jackson, Dominik C Fuhrmann, Vinzenz Särchen, Daniela Brücher, Andreas Weigert, Martin J S Dyer, Meike Vogler.

BH3-mimetics represent promising anti-cancer agents in tumors that rely on the anti-apoptotic function of B-Cell Lymphoma 2 (BCL2) proteins, particularly in leukemia and lymphoma cells primed for apoptosis. Mechanistically, BH3-mimetics may displace pro-apoptotic binding partners thus inducing BAX/BAK-mediated mitochondrial permeabilization followed by cytochrome c release, activation of the caspase cascade and apoptosis. Here, we describe a novel mode of caspase-independent cell death (CICD) induced by BH3-mimetics in a subset of diffuse large B-cell lymphoma (DLBCL) cells. Of note, rather than occurring via necroptosis, CICD induced immediately after mitochondrial permeabilization was associated with transcriptional reprogramming mediated by activation of c-Jun N-terminal Kinase (JNK) signaling and Activator Protein 1 (AP1). Thereby, CICD resulted in the JNK/AP1-mediated upregulation of inflammatory chemokines and increased migration of cytotoxic Natural Killer (NK) cells. Taken together, our study describes a novel mode of CICD triggered by BH3-mimetics that may alter the immune response towards dying cells.

DOI: https://doi.org/10.1038/s41419-024-06652-3
PLoS Pathog. 2024 Apr 15. 20(4): e1011829

Progression of herpesvirus infection remodels mitochondrial organization and metabolism.

Simon Leclerc, Alka Gupta, Visa Ruokolainen, Jian-Hua Chen, Kari Kunnas, Axel A Ekman, Henri Niskanen, Ilya Belevich, Helena Vihinen, Paula Turkki, Ana J Perez-Berna, Sergey Kapishnikov, Elina Mäntylä, Maria Harkiolaki, Eric Dufour, Vesa Hytönen, Eva Pereiro, Tony McEnroe, Kenneth Fahy, Minna U Kaikkonen, Eija Jokitalo, Carolyn A Larabell, Venera Weinhardt, Salla Mattola, Vesa Aho, Maija Vihinen-Ranta.

Viruses target mitochondria to promote their replication, and infection-induced stress during the progression of infection leads to the regulation of antiviral defenses and mitochondrial metabolism which are opposed by counteracting viral factors. The precise structural and functional changes that underlie how mitochondria react to the infection remain largely unclear. Here we show extensive transcriptional remodeling of protein-encoding host genes involved in the respiratory chain, apoptosis, and structural organization of mitochondria as herpes simplex virus type 1 lytic infection proceeds from early to late stages of infection. High-resolution microscopy and interaction analyses unveiled infection-induced emergence of rough, thin, and elongated mitochondria relocalized to the perinuclear area, a significant increase in the number and clustering of endoplasmic reticulum-mitochondria contact sites, and thickening and shortening of mitochondrial cristae. Finally, metabolic analyses demonstrated that reactivation of ATP production is accompanied by increased mitochondrial Ca2+ content and proton leakage as the infection proceeds. Overall, the significant structural and functional changes in the mitochondria triggered by the viral invasion are tightly connected to the progression of the virus infection.

DOI: https://doi.org/10.1371/journal.ppat.1011829
Nat Commun. 2024 Apr 17. 15(1): 3290

Cross-link assisted spatial proteomics to map sub-organelle proteomes and membrane protein topologies.

Ying Zhu, Kerem Can Akkaya, Julia Ruta, Nanako Yokoyama, Cong Wang, Max Ruwolt, Diogo Borges Lima, Martin Lehmann, Fan Liu.

The functions of cellular organelles and sub-compartments depend on their protein content, which can be characterized by spatial proteomics approaches. However, many spatial proteomics methods are limited in their ability to resolve organellar sub-compartments, profile multiple sub-compartments in parallel, and/or characterize membrane-associated proteomes. Here, we develop a cross-link assisted spatial proteomics (CLASP) strategy that addresses these shortcomings. Using human mitochondria as a model system, we show that CLASP can elucidate spatial proteomes of all mitochondrial sub-compartments and provide topological insight into the mitochondrial membrane proteome. Biochemical and imaging-based follow-up studies confirm that CLASP allows discovering mitochondria-associated proteins and revising previous protein sub-compartment localization and membrane topology data. We also validate the CLASP concept in synaptic vesicles, demonstrating its applicability to different sub-cellular compartments. This study extends the scope of cross-linking mass spectrometry beyond protein structure and interaction analysis towards spatial proteomics, and establishes a method for concomitant profiling of sub-organelle and membrane proteomes.

DOI: https://doi.org/10.1038/s41467-024-47569-x
Clin Exp Pharmacol Physiol. 2024 Jun;51(6): e13856

Colorectal cancer cells with stably expressed SIRT3 demonstrate proliferating retardation by Wnt/β-catenin cascade inactivation.

Tianyu Li, Leqi Fan, Yijiang Jia, Chen Xu, Wei Guo, Yuji Wang, Ye Li.

  Colorectal cancer (CRC) is a typical and lethal digestive system malignancy. In this study, we investigated the effect of sirtuin 3 (SIRT3) expression, a fidelity mitochondrial protein, on the proliferation of CRC cells and the mechanisms involved. Using the University of Alabama at Birmingham Cancer Data Analysis Portal database and the Clinical Proteomic Tumour Analysis Consortium database, we discovered that low expression of SIRT3 in CRC was a negative factor for survival prognosis (P < .05). Meanwhile, SIRT3 expression was correlated with distant metastasis and tumour, node, metastasis stage of CRC patients (P < .05). Subsequently, we observed that CRC cells with stable SIRT3 expression exhibited a significant decrease in proliferative capacities both in vitro and in vivo, compared to their counterparts (P < .05). Further investigation using western blot, immunoprecipitation and TOPflash/FOPflash assay showed the mechanism of growth retardation of these cells was highly associated with the degradation of β-catenin in cytosol, and the localization of β-catenin/α-catenin complex in the nucleus. In conclusion, our findings suggest that the inhibition of CRC cell proliferation by SIRT3 is closely associated with the inactivation of the Wnt/β-catenin signalling pathway.

Keywords:  SIRT3; Wnt/β‐catenin cascade; colorectal cancer; proliferation

DOI:  https://doi.org/10.1111/1440-1681.13856
BMC Cancer. 2024 Apr 17. 24(1): 485

Metabolic difference between patient-derived xenograft model of pancreatic ductal adenocarcinoma and corresponding primary tumor.

Shi Wen, Xianchao Lin, Wei Luo, Yu Pan, Fei Liao, Zhenzhao Wang, Bohan Zhan, Jianghua Feng, Heguang Huang.

BACKGROUND: Patients-derived xenograft (PDX) model have been widely used for tumor biological and pathological studies. However, the metabolic similarity of PDX tumor to the primary cancer (PC) is still unknown.METHODS: In present study, we established PDX model by engrafting primary tumor of pancreatic ductal adenocarcinoma (PDAC), and then compared the tumor metabolomics of PC, the first generation of PDX tumor (PDXG1), and the third generation of PDX tumor (PDXG3) by using 1H NMR spectroscopy. Then, we assessed the differences in response to chemotherapy between PDXG1 and PDXG3 and corresponding metabolomic differences in drug-resistant tumor tissues. To evaluate the metabolomic similarity of PDX to PC, we also compared the metabolomic difference of cell-derived xenograft (CDX) vs. PC and PDX vs. PC.
RESULTS: After engraftment, PDXG1 tumor had a low level of lactate, pyruvate, citrate and multiple amino acids (AAs) compared with PC. Metabolite sets enrichment and metabolic pathway analyses implied that glycolysis metabolisms were suppressed in PDXG1 tumor, and tricarboxylic acid cycle (TCA)-associated anaplerosis pathways, such as amino acids metabolisms, were enhanced. Then, after multiple passages of PDX, the altered glycolysis and TCA-associated anaplerosis pathways were partially recovered. Although no significant difference was observed in the response of PDXG1 and PDXG3 to chemotherapy, the difference in glycolysis and amino acids metabolism between PDXG1 and PDXG3 could still be maintained. In addition, the metabolomic difference between PC and CDX models were much larger than that of PDX model and PC, indicating that PDX model still retain more metabolic characteristics of primary tumor which is more suitable for tumor-associated metabolism research.
CONCLUSIONS: Compared with primary tumor, PDX models have obvious difference in metabolomic level. These findings can help us design in vivo tumor metabolomics research legitimately and analyze the underlying mechanism of tumor metabolic biology thoughtfully.

DOI: https://doi.org/10.1186/s12885-024-12193-x
Ann Hematol. 2024 Apr 17.

Inhibition of NRF2 signaling overcomes acquired resistance to arsenic trioxide in FLT3-mutated Acute Myeloid Leukemia.

Daniel Zechariah Paul Jebanesan, Raveen Stephen Stallon Illangeswaran, Bharathi M Rajamani, Rakhi Thalayattu Vidhyadharan, Saswati Das, Nayanthara K Bijukumar, Balaji Balakrishnan, Vikram Mathews, Shaji R Velayudhan, Poonkuzhali Balasubramanian.

  De novo acute myeloid leukemia (AML) patients with FMS-like tyrosine kinase 3 internal tandem duplications (FLT3-ITD) have worse treatment outcomes. Arsenic trioxide (ATO) used in the treatment of acute promyelocytic leukemia (APL) has been reported to be effective in degrading the FLT3 protein in AML cell lines and sensitizing non-APL AML patient samples in-vitro. We have previously reported that primary cells from FLT3-ITD mutated AML patients were sensitive to ATO in-vitro compared to other non-M3 AML and molecular/pharmacological inhibition of NF-E2 related factor 2 (NRF2), a master regulator of antioxidant response improved the chemosensitivity to ATO and daunorubicin even in non FLT3-ITD mutated cell lines and primary samples. We examined the effects of molecular/pharmacological suppression of NRF2 on acquired ATO resistance in the FLT3-ITD mutant AML cell line (MV4-11-ATO-R). ATO-R cells showed increased NRF2 expression, nuclear localization, and upregulation of bonafide NRF2 targets. Molecular inhibition of NRF2 in this resistant cell line improved ATO sensitivity in vitro. Digoxin treatment lowered p-AKT expression, abrogating nuclear NRF2 localization and sensitizing cells to ATO. However, digoxin and ATO did not sensitize non-ITD AML cell line THP1 with high NRF2 expression. Digoxin decreased leukemic burden and prolonged survival in MV4-11 ATO-R xenograft mice. We establish that altering NRF2 expression may reverse acquired ATO resistance in FLT3-ITD AML.

Keywords:  AML; Acquired chemoresistance; Arsenic trioxide; Digoxin; FLT3-ITD; NRF2

DOI:  https://doi.org/10.1007/s00277-024-05742-8
Nat Commun. 2024 Apr 18. 15(1): 3351

The genetic landscape of a metabolic interaction.

Thuy N Nguyen, Christine Ingle, Samuel Thompson, Kimberly A Reynolds.

While much prior work has explored the constraints on protein sequence and evolution induced by physical protein-protein interactions, the sequence-level constraints emerging from non-binding functional interactions in metabolism remain unclear. To quantify how variation in the activity of one enzyme constrains the biochemical parameters and sequence of another, we focus on dihydrofolate reductase (DHFR) and thymidylate synthase (TYMS), a pair of enzymes catalyzing consecutive reactions in folate metabolism. We use deep mutational scanning to quantify the growth rate effect of 2696 DHFR single mutations in 3 TYMS backgrounds under conditions selected to emphasize biochemical epistasis. Our data are well-described by a relatively simple enzyme velocity to growth rate model that quantifies how metabolic context tunes enzyme mutational tolerance. Together our results reveal the structural distribution of epistasis in a metabolic enzyme and establish a foundation for the design of multi-enzyme systems.

DOI: https://doi.org/10.1038/s41467-024-47671-0