bims-medica 2024-02-04 papers

bims-medica

Biomed News

on Metabolism and diet in cancer

Issue of 2024–02–04
seventeen papers selected by
Brett Chrest, East Carolina University

Should the standard model of cellular energy metabolism be reconsidered? Possible coupling between the pentose phosphate pathway, glycolysis and extra-mitochondrial oxidative phosphorylation.
Lactate utilization enables metabolic escape to confer resistance to BET inhibition in acute myeloid leukemia.
Copper drives remodeling of metabolic state and progression of clear cell renal cell carcinoma.
Mitochondrial dynamics and colorectal cancer biology: mechanisms and potential targets.
The striking differences in the bioenergetics of brain and liver mitochondria are enhanced in mitochondrial disease.
A Potential "Anti-Warburg Effect" in Circulating Tumor Cell-mediated Metastatic Progression?
KLF8 Promotes the Survival of Lung Adenocarcinoma During Nutrient Deprivation by Regulating the Pentose Phosphate Pathway through SIRT2.
The opposite role of lactate dehydrogenase a (LDHA) in cervical cancer under energy stress conditions.
Bioengineered in vitro three-dimensional tumor models in endocrine cancers.
Fibroblasts in orchestrating colorectal tumorigenesis and progression.
Impact of the ketogenic diet on body fat, muscle mass, and exercise performance: a review.
Enhancement of de novo lipogenesis by the IDH1 and IDH2-dependent reverse TCA cycle maintains the growth and angiogenic capacity of bone marrow-derived endothelial progenitor cells under hypoxia.
In-vivo tracking of deuterium metabolism in mouse organs using LC-MS/MS.
Targeting cancer stem cell OXPHOS with tailored ruthenium complexes as a new anti-cancer strategy.
The effect of the ketogenic diet on resistance training load management: a repeated-measures clinical trial in trained participants.
Decreased pyruvate dehydrogenase activity in Tafazzin-deficient cells is caused by dysregulation of pyruvate dehydrogenase phosphatase 1 (PDP1).
A universal metabolite repair enzyme removes a strong inhibitor of the TCA cycle.

Biochimie. 2024 Jan 31. pii: S0300-9084(24)00036-1. [Epub ahead of print]

Should the standard model of cellular energy metabolism be reconsidered? Possible coupling between the pentose phosphate pathway, glycolysis and extra-mitochondrial oxidative phosphorylation.

Alessandro Maria Morelli, Felix Scholkmann.

  The process of cellular respiration occurs for energy production through catabolic reactions, generally with glucose as the first process step. In the present work, we introduce a novel concept for understanding this process, based on our conclusion that glucose metabolism is coupled to the pentose phosphate pathway (PPP) and extra-mitochondrial oxidative phosphorylation in a closed-loop process. According to the current standard model of glycolysis, glucose is first converted to glucose 6-phosphate (glucose 6-P) and then to fructose 6-phosphate, glyceraldehyde 3-phosphate and pyruvate, which then enters the Krebs cycle in the mitochondria. However, it is more likely that the pyruvate will be converted to lactate. In the PPP, glucose 6-P is branched off from glycolysis and used to produce NADPH and ribulose 5-phosphate (ribulose 5-P). Ribulose 5-P can be converted to fructose 6-P and glyceraldehyde 3-P. In our view, a circular process can take place in which the ribulose 5-P produced by the PPP enters the glycolysis pathway and is then retrogradely converted to glucose 6-P. This process is repeated several times until the complete degradation of glucose 6-P. The role of mitochondria in this process is to degrade lipids by beta-oxidation and produce acetyl-CoA; the function of producing ATP appears to be only secondary. This proposed new concept of cellular bioenergetics allows the resolution of some previously unresolved controversies related to cellular respiration and provides a deeper understanding of metabolic processes in the cell, including a new insights into the Warburg effect.

Keywords:  Cancer metabolism; Cellular respiration; Endoplasmic reticulum; Extra-mitochondrial OXPHOS; Glycolysis; Pentose phosphate pathway

DOI:  https://doi.org/10.1016/j.biochi.2024.01.018
Cancer Res. 2024 Jan 29.

Lactate utilization enables metabolic escape to confer resistance to BET inhibition in acute myeloid leukemia.

Andrew J Monteith, Haley E Ramsey, Alexander J Silver, Donovan Brown, Dalton Greenwood, Brianna N Smith, Ashley D Wise, Juan Liu, Sarah D Olmstead, Jackson Watke, Maria P Arrate, Agnieszka E Gorska, Londa Fuller, Jason W Locasale, Matthew C Stubbs, Jeffrey C Rathmell, Michael R Savona.

Impairing the BET-family co-activator BRD4 with small molecule inhibitors (BETi) showed encouraging pre-clinical activity in treating acute myeloid leukemia (AML). However, dose-limiting toxicities and limited clinical activity dampened the enthusiasm for BETi as a single agent. BETi resistance in AML myeloblasts was found to correlate with maintaining mitochondrial respiration, suggesting that identifying the metabolic pathway sustaining mitochondrial integrity could help develop approaches to improve BETi efficacy. Herein, we demonstrated that mitochondria-associated lactate dehydrogenase allows AML myeloblasts to utilize lactate as a metabolic bypass to fuel mitochondrial respiration and maintain cellular viability. Pharmacologically and genetically impairing lactate utilization rendered resistant myeloblasts susceptible to BET inhibition. Low-dose combinations of BETi and oxamate, a lactate dehydrogenase inhibitor, reduced in vivo expansion of BETi-resistant AML in cell line and patient-derived murine models. These results elucidate how AML myeloblasts metabolically adapt to BETi by consuming lactate and demonstrate that combining BETi with inhibitors of lactate utilization may be useful in AML treatment.

DOI: https://doi.org/10.1158/0008-5472.CAN-23-0291
bioRxiv. 2024 Jan 19. pii: 2024.01.16.575895. [Epub ahead of print]

Copper drives remodeling of metabolic state and progression of clear cell renal cell carcinoma.

Megan E Bischoff, Behrouz Shamsaei, Juechen Yang, Dina Secic, Bhargav Vemuri, Julie A Reisz, Angelo D'Alessandro, Caterina Bartolacci, Rafal Adamczak, Lucas Schmidt, Jiang Wang, Amelia Martines, Jacek Biesiada, Katherine E Vest, Pier P Scaglioni, David R Plas, Krushna C Patra, Shuchi Gulati, Julio A Landero Figueroa, Jarek Meller, J Tom Cunningham, Maria F Czyzyk-Krzeska.

Copper (Cu) is an essential trace element required for mitochondrial respiration. Late-stage clear cell renal cell carcinoma (ccRCC) accumulates Cu and allocates it to mitochondrial cytochrome c oxidase. We show that Cu drives coordinated metabolic remodeling of bioenergy, biosynthesis and redox homeostasis, promoting tumor growth and progression of ccRCC. Specifically, Cu induces TCA cycle-dependent oxidation of glucose and its utilization for glutathione biosynthesis to protect against H 2 O 2 generated during mitochondrial respiration, therefore coordinating bioenergy production with redox protection. scRNA-seq determined that ccRCC progression involves increased expression of subunits of respiratory complexes, genes in glutathione and Cu metabolism, and NRF2 targets, alongside a decrease in HIF activity, a hallmark of ccRCC. Spatial transcriptomics identified that proliferating cancer cells are embedded in clusters of cells with oxidative metabolism supporting effects of metabolic states on ccRCC progression. Our work establishes novel vulnerabilities with potential for therapeutic interventions in ccRCC. Accumulation of copper is associated with progression and relapse of ccRCC and drives tumor growth.Cu accumulation and allocation to cytochrome c oxidase (CuCOX) remodels metabolism coupling energy production and nucleotide biosynthesis with maintenance of redox homeostasis.Cu induces oxidative phosphorylation via alterations in the mitochondrial proteome and lipidome necessary for the formation of the respiratory supercomplexes. Cu stimulates glutathione biosynthesis and glutathione derived specifically from glucose is necessary for survival of Cu Hi cells. Biosynthesis of glucose-derived glutathione requires activity of glutamyl pyruvate transaminase 2, entry of glucose-derived pyruvate to mitochondria via alanine, and the glutamate exporter, SLC25A22. Glutathione derived from glucose maintains redox homeostasis in Cu-treated cells, reducing Cu-H 2 O 2 Fenton-like reaction mediated cell death. Progression of human ccRCC is associated with gene expression signature characterized by induction of ETC/OxPhos/GSH/Cu-related genes and decrease in HIF/glycolytic genes in subpopulations of cancer cells. Enhanced, concordant expression of genes related to ETC/OxPhos, GSH, and Cu characterizes metabolically active subpopulations of ccRCC cells in regions adjacent to proliferative subpopulations of ccRCC cells, implicating oxidative metabolism in supporting tumor growth.

DOI: https://doi.org/10.1101/2024.01.16.575895
Cell Commun Signal. 2024 Feb 01. 22(1): 91

Mitochondrial dynamics and colorectal cancer biology: mechanisms and potential targets.

Zihong Wu, Chong Xiao, Jing Long, Wenbo Huang, Fengming You, Xueke Li.

  Colorectal cancer (CRC) is a significant public health concern, and its development is associated with mitochondrial dysfunction. Mitochondria can adapt to the high metabolic demands of cancer cells owing to their plasticity and dynamic nature. The fusion-fission dynamics of mitochondria play a crucial role in signal transduction and metabolic functions of CRC cells. Enhanced mitochondrial fission promotes the metabolic reprogramming of CRC cells, leading to cell proliferation, metastasis, and chemoresistance. Excessive fission can also trigger mitochondria-mediated apoptosis. In contrast, excessive mitochondrial fusion leads to adenosine triphosphate (ATP) overproduction and abnormal tumor proliferation, whereas moderate fusion protects intestinal epithelial cells from oxidative stress-induced mitochondrial damage, thus preventing colitis-associated cancer (CAC). Therefore, an imbalance in mitochondrial dynamics can either promote or inhibit CRC progression. This review provides an overview of the mechanism underlying mitochondrial fusion-fission dynamics and their impact on CRC biology. This revealed the dual role of mitochondrial fusion-fission dynamics in CRC development and identified potential drug targets. Additionally, this study partially explored mitochondrial dynamics in immune and vascular endothelial cells in the tumor microenvironment, suggesting promising prospects for targeting key fusion/fission effector proteins against CRC.

Keywords:  Colorectal cancer; Drug targets; Fusion–fission; Mitochondrial dynamics

DOI:  https://doi.org/10.1186/s12964-024-01490-4
Biochim Biophys Acta Mol Basis Dis. 2024 Jan 26. pii: S0925-4439(24)00018-8. [Epub ahead of print]1870(3): 167033

The striking differences in the bioenergetics of brain and liver mitochondria are enhanced in mitochondrial disease.

Valeria Balmaceda, Timea Komlódi, Marten Szibor, Erich Gnaiger, Anthony L Moore, Erika Fernandez-Vizarra, Carlo Viscomi.

  Mitochondrial disorders are hallmarked by the dysfunction of oxidative phosphorylation (OXPHOS) yet are highly heterogeneous at the clinical and genetic levels. Striking tissue-specific pathological manifestations are a poorly understood feature of these conditions, even if the disease-causing genes are ubiquitously expressed. To investigate the functional basis of this phenomenon, we analyzed several OXPHOS-related bioenergetic parameters, including oxygen consumption rates, electron transfer system (ETS)-related coenzyme Q (mtCoQ) redox state and production of reactive oxygen species (ROS) in mouse brain and liver mitochondria fueled by different substrates. In addition, we determined how these functional parameters are affected by ETS impairment in a tissue-specific manner using pathologically relevant mouse models lacking either Ndufs4 or Ttc19, leading to Complex I (CI) or Complex III (CIII) deficiency, respectively. Detailed OXPHOS analysis revealed striking differences between brain and liver mitochondria in the capacity of the different metabolic substrates to fuel the ETS, reduce the ETS-related mtCoQ, and to induce ROS production. In addition, ETS deficiency due to either CI or CIII dysfunction had a much greater impact on the intrinsic bioenergetic parameters of brain compared with liver mitochondria. These findings are discussed in terms of the still rather mysterious tissue-specific manifestations of mitochondrial disease.

Keywords:  Coenzyme Q redox state; Complex I deficiency; Complex III deficiency; Isolated mitochondria; Oxygen consumption; Reactive oxygen species

DOI:  https://doi.org/10.1016/j.bbadis.2024.167033
Aging Dis. 2024 Jan 11.

A Potential "Anti-Warburg Effect" in Circulating Tumor Cell-mediated Metastatic Progression?

Zhuofeng Jiang, Jiapeng He, Binyu Zhang, Liping Wang, Chunhao Long, Boxi Zhao, Yufan Yang, Longxiang Du, Weiren Luo, Jianyang Hu, Xin Hong.

Metabolic reprogramming is a defining hallmark of cancer metastasis, warranting thorough exploration. The tumor-promoting function of the "Warburg Effect", marked by escalated glycolysis and restrained mitochondrial activity, is widely acknowledged. Yet, the functional significance of mitochondria-mediated oxidative phosphorylation (OXPHOS) during metastasis remains controversial. Circulating tumor cells (CTCs) are considered metastatic precursors that detach from primary or secondary sites and harbor the potential to seed distant metastases through hematogenous dissemination. A comprehensive metabolic characterization of CTCs faces formidable obstacles, including the isolation of these rare cells from billions of blood cells, coupled with the complexities of ex vivo-culturing of CTC lines or the establishment of CTC-derived xenograft models (CDX). This review summarized the role of the "Warburg Effect" in both tumorigenesis and CTC-mediated metastasis. Intriguingly, bioinformatic analysis of single-CTC transcriptomic studies unveils a potential OXPHOS dominance over Glycolysis signature genes across several important cancer types. From these observations, we postulate a potential "Anti-Warburg Effect" (AWE) in CTCs-a metabolic shift bridging primary tumors and metastases. The observed AWE could be clinically important as they are significantly correlated with therapeutic response in melanoma and prostate patients. Thus, unraveling dynamic metabolic regulations within CTC populations might reveal an additional layer of regulatory complexities of cancer metastasis, providing an avenue for innovative anti-metastasis therapies.

DOI: https://doi.org/10.14336/AD.2023.1227
Front Biosci (Landmark Ed). 2024 Jan 18. 29(1): 27

KLF8 Promotes the Survival of Lung Adenocarcinoma During Nutrient Deprivation by Regulating the Pentose Phosphate Pathway through SIRT2.

Qiaohong Bai, Wenfang Jin, Futao Chen, Jiang Zhu, Lifeng Cao, Yang Yang, Fukuan Zhong, Li Li.

   BACKGROUND: The pentose phosphate pathway (PPP) is a critical metabolic pathway that generates NADPH and ribose-5-phosphate for nucleotide biosynthesis and redox homeostasis. In this study, we investigated a potential regulatory role for Krüppel-like factor 8 (KLF8) in the control of PPP in lung adenocarcinoma (LUAD) cells.
METHODS: Based on a comprehensive set of experimental approaches, including cell culture, molecular techniques, and functional assays, we revealed a novel mechanism by which KLF8 promotes the activation of glucose-6-phosphate dehydrogenase (G6PD), a component enzyme in the PPP.
RESULTS: Our findings demonstrate that KLF8 inhibits the acetylation of G6PD, leading to its increased enzymatic activity. Additionally, we observed that KLF8 activates the transcription of SIRT2, which has been implicated in regulating G6PD acetylation. These results highlight the interplay between KLF8, G6PD, and protein acetylation in the regulation of PPP in LUAD.
CONCLUSIONS: Understanding the intricate molecular mechanisms underlying the metabolic reprogramming driven by KLF8 in lung cancer provides valuable insights into potential therapeutic strategies targeting the PPP. This study emphasizes the significance of KLF8 as a key modulator of metabolic pathways and indicates the potential of targeting the KLF8-G6PD axis for lung cancer treatment.

Keywords:  KLF8; nutrient deprivation; pentose phosphate pathway; tumor metabolism

DOI:  https://doi.org/10.31083/j.fbl2901027
Free Radic Biol Med. 2024 Jan 31. pii: S0891-5849(24)00051-0. [Epub ahead of print]

The opposite role of lactate dehydrogenase a (LDHA) in cervical cancer under energy stress conditions.

Chaoran Jia, Yulun Wu, Feng Gao, Wei Liu, Na Li, Yao Chen, Luguo Sun, Shuyue Wang, Chunlei Yu, Yongli Bao, Zhenbo Song.

  Due to insufficient and defective vascularization, the tumor microenvironment is often nutrient-depleted. LDHA has been demonstrated to play a tumor-promoting role by facilitating the glycolytic process. However, whether and how LDHA regulates cell survival in the nutrient-deficient tumor microenvironment are still unclear. Here, we sought to investigate the role and mechanism of LDHA in regulating cell survival and proliferation under energy stress conditions. Our results showed that the aerobic glycolysis levels, cell survival and proliferation of cervical cancer cells decreased significantly after inhibition of LDHA under normal culture condition while LDHA deficiency greatly inhibited glucose starvation-induced ferroptosis and promoted cell proliferation and tumor formation under energy stress conditions. Mechanistic studies suggested that glucose metabolism shifted from aerobic glycolysis to mitochondrial OXPHOS under energy stress conditions and LDHA knockdown increased accumulation of pyruvate in the cytosol, which entered the mitochondria and upregulated the level of oxaloacetate by phosphoenolpyruvate carboxylase (PC). Importantly, the increase in oxaloacetate production after absence of LDHA remarkably activated AMP-activated protein kinase (AMPK), which increased mitochondrial biogenesis and mitophagy, promoted mitochondrial homeostasis, thereby decreasing ROS level. Moreover, repression of lipogenesis by activation of AMPK led to elevated levels of reduced nicotinamide adenine dinucleotide phosphate (NADPH), which effectively resisted ROS-induced cell ferroptosis and enhanced cell survival under energy stress conditions. These results suggested that LDHA played an opposing role in survival and proliferation of cervical cancer cells under energy stress conditions, and inhibition of LDHA may not be a suitable treatment strategy for cervical cancer.

Keywords:  AMPK; Cervical cancer; Energy stress; Ferroptosis; LDHA

DOI:  https://doi.org/10.1016/j.freeradbiomed.2024.01.043
Endocr Relat Cancer. 2024 Jan 01. pii: ERC-23-0344. [Epub ahead of print]

Bioengineered in vitro three-dimensional tumor models in endocrine cancers.

Aleksander Skardal, Hemamylammal Sivakumar, Marco Rodriguez, Liudmila Popova, Priya Dedhia.

Endocrine tumors are a heterogeneous cluster of malignancies that originate from cells that can secrete hormones. Examples include, but are not limited to, thyroid cancer, adrenocortical carcinoma, and neuroendocrine tumors. Many endocrine tumors are relatively slow to proliferate, and as such, they often do not respond well to common anti-proliferative chemotherapies. Therefore, increasing attention has been given to targeted therapies and immunotherapies in these diseases. However, in contrast to other cancers, many endocrine tumors are relatively rare, and as a result, less is understood about their biology, including specific targets for intervention. Our limited understanding of such tumors is in part due to a limitations in model systems that accurately recapitulate and enable mechanistic exploration of these tumors. While mouse models and two-dimensional (2D) cell cultures exist for some endocrine tumors, these models often may not accurately model nuances of human endocrine tumors. Mice differ from human endocrine physiology and 2D cell cultures fail to recapitulate the heterogeneity and 3D architectures of in vivo tumors. To complement these traditional cancer models, bioengineered 3D tumor models, such as organoids and tumor-on-a-chip systems, have advanced rapidly in the past decade. However, these technologies have only recently been applied to most endocrine tumors. In this review we provide descriptions of these platforms, focusing on thyroid, adrenal, and neuroendocrine tumors and how they have been and are being applied in the context of endocrine tumors.

DOI: https://doi.org/10.1530/ERC-23-0344
Cell Mol Gastroenterol Hepatol. 2024 Jan 31. pii: S2352-345X(24)00013-4. [Epub ahead of print]

Fibroblasts in orchestrating colorectal tumorigenesis and progression.

Subinuer Abudukelimu, Noel F C C de Miranda, Lukas J A C Hawinkels.

  Cancer-associated fibroblasts (CAFs) are an abundant component of the tumor microenvironment and have been shown to possess critical functions in tumor progression. While their roles have been predominantly described as tumor-promoting, more recent findings have identified subsets of CAFs with tumor-restraining functions. Accumulating evidence underscores large heterogeneity in fibroblasts subsets where distinct subsets differentially impact the initiation, progression and metastasis of colorectal cancer (CRC). In this review, we summarize and discuss the evolving role of CAFs in CRC, highlighting the ongoing controversies regarding their distinct origins and multifaceted functions. In addition, we explore how CAFs can confer resistance to current therapies and the challenges of developing effective CAF-directed therapies. Taken together, we believe that, in this rapidly evolving field, it is crucial to first comprehensively understand the CAF dynamics and to bridge existing knowledge gaps regarding CAF heterogeneity and plasticity, before further exploring the clinical targeting of CAFs.

Keywords:  Colorectal cancer; adenoma-to-carcinoma transition; cancer-associated fibroblast; heterogeneity

DOI:  https://doi.org/10.1016/j.jcmgh.2024.01.013
Phys Act Nutr. 2023 Dec;27(4): 1-7

Impact of the ketogenic diet on body fat, muscle mass, and exercise performance: a review.

Nana Chung.

   PURPOSE: The purpose of this review was to investigate the effects of the ketogenic diet (KD), on body fat, muscle mass, and exercise performance. As the KD is a subject of ongoing debate, we also present the existing evidence regarding its potential benefits in the aforementioned areas of body fat, muscle mass, and exercise performance.
METHODS: A literature search was conducted using the keywords "ketogenic diet, low-carbohydrate diet, high-fat diet, body fat, muscle mass, and exercise performance" in PubMed, Web of Science, and Google Scholar.
RESULTS: The KD effectively reduced body fat in the short term and, preserved muscle mass during weight loss, however, its impact on exercise performance remains inconclusive owing to various factors.
CONCLUSION: While controversial, it is undeniable that the KD has the potential to affect body fat, muscle mass, and exercise performance. Consequently, additional research is required to elucidate the underlying mechanisms across various populations, optimize their implementation, and understand their long-term effects.

Keywords:  body fat; exercise performance; ketogenic diet; low-carbohydrate high-fat diet; muscle mass

DOI:  https://doi.org/10.20463/pan.2023.0031
Free Radic Biol Med. 2024 Jan 26. pii: S0891-5849(24)00036-4. [Epub ahead of print]213 327-342

Enhancement of de novo lipogenesis by the IDH1 and IDH2-dependent reverse TCA cycle maintains the growth and angiogenic capacity of bone marrow-derived endothelial progenitor cells under hypoxia.

Qiwei He, Tiantian Yu, Junxiong Chen, Jianli Liang, Dongni Lin, Kaihao Yan, Zijing Xie, Yuqi Song, Zhenzhou Chen.

   BACKGROUND: Bone marrow-derived endothelial progenitor cells (EPCs) play a dynamic role in maintaining the structure and function of blood vessels. But how these cells maintain their growth and angiogenic capacity under bone marrow hypoxic niche is still unclear. This study aims to explore the mechanisms from a perspective of cellular metabolism.
METHODS: XFe96 Extracellular Flux Analyzer was used to analyze the metabolic status of EPCs. Gas Chromatography-Mass Spectrometry (GC-MS) was used to trace the carbon movement of 13C-labeled glucose and glutamine under 1 % O2 (hypoxia) and ∼20 % O2 (normoxia). Moreover, RNA interference, targeting isocitrate dehydrogenase-1 (IDH1) and IDH2, was used to inhibit the reverse tricarboxylic acid (TCA) cycle and analyze metabolic changes via isotope tracing as well as changes in cell growth and angiogenic potential under hypoxia. The therapeutic potential of EPCs under hypoxia was investigated in the ischemic hindlimb model.
RESULTS: Compared with normoxic cells, hypoxic cells showed increased glycolysis and decreased mitochondrial respiration. Isotope metabolic tracing revealed that under hypoxia, the forward TCA cycle was decreased and the reverse TCA cycle was enhanced, mediating the conversion of α-ketoglutarate (α-KG) into isocitrate/citrate, and de novo lipid synthesis was promoted. Downregulation of IDH1 or IDH2 under hypoxia suppressed the reverse TCA cycle, attenuated de novo lipid synthesis (DNL), elevated α-KG levels, and decreased the expression of hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor A (VEGFA), eventually inhibiting the growth and angiogenic capacity of EPCs. Importantly, the transplantation of hypoxia-cultured EPCs in a mouse model of limb ischemia promoted new blood vessel regeneration and blood supply recovery in the ischemic area better than the transplantation of normoxia-cultured EPCs.
CONCLUSIONS: Under hypoxia, the IDH1- and IDH2-mediated reverse TCA cycle promotes glutamine-derived de novo lipogenesis and stabilizes the expression of α-KG and HIF-1α, thereby enhancing the growth and angiogenic capacity of EPCs.

Keywords:  Endothelial progenitor cells; HIF-1α; Hypoxia; Lipid synthesis; Reverse TCA cycle

DOI:  https://doi.org/10.1016/j.freeradbiomed.2024.01.028
J Chromatogr A. 2024 Jan 28. pii: S0021-9673(24)00064-5. [Epub ahead of print]1717 464691

In-vivo tracking of deuterium metabolism in mouse organs using LC-MS/MS.

Siva Swapna Kasarla, Vera Flocke, Nay Min Thaw Saw, Antonia Fecke, Albert Sickmann, Matthias Gunzer, Ulrich Flögel, Prasad Phapale.

  Mass spectrometry-based metabolomics with stable isotope labeling (SIL) is an established tool for sensitive and precise analyses of tissue metabolism, its flux, and pathway activities in diverse models of physiology and disease. Despite the simplicity and broad applicability of deuterium (2H)-labeled precursors for tracing metabolic pathways with minimal biological perturbations, they are rarely employed in LC-MS/MS-guided metabolomics. In this study, we have developed a LC-MS/MS-guided workflow to trace deuterium metabolism in mouse organs following 2H7 -glucose infusion. The workflow includes isotopically labeled glucose infusion, mouse organ isolation and metabolite extraction, zwitterion-based hydrophilic interaction liquid chromatography (HILIC) coupled to high-resolution tandem mass spectrometry, targeted data acquisition for sensitive detection of deuterated metabolites, a spectral library of over 400 metabolite standards, and multivariate data analysis with pathway mapping. The optimized method was validated for matrix effects, normalization, and quantification to provide both tissue metabolomics and tracking the in-vivo metabolic fate of deuterated glucose through key metabolic pathways. We quantified more than 100 metabolites in five major mouse organ tissues (liver, kidney, brain, brown adipose tissue, and heart). Furthermore, we mapped isotopologues of deuterated metabolites from glycolysis, tricarboxylic acid (TCA) cycle, and amino acid pathways, which are significant for studying both health and various diseases. This study will open new avenues in LC-MS based analysis of 2H-labeled tissue metabolism research in animal models and clinical settings.

Keywords:  Deuterium tracing; LC-MS; Metabolic flux; Metabolomics; Tissue metabolism

DOI:  https://doi.org/10.1016/j.chroma.2024.464691
J Exp Clin Cancer Res. 2024 Jan 27. 43(1): 33

Targeting cancer stem cell OXPHOS with tailored ruthenium complexes as a new anti-cancer strategy.

Sonia Alcalá, Lara Villarino, Laura Ruiz-Cañas, José R Couceiro, Miguel Martínez-Calvo, Adrián Palencia-Campos, Diego Navarro, Pablo Cabezas-Sainz, Iker Rodriguez-Arabaolaza, Alfonso Cordero-Barreal, Lucia Trilla-Fuertes, Juan A Rubiolo, Sandra Batres-Ramos, Mireia Vallespinos, Cristina González-Páramos, Jéssica Rodríguez, Angelo Gámez-Pozo, Juan Ángel Fresno Vara, Sara Fra Fernández, Amparo Benito Berlinches, Nicolás Moreno-Mata, Ana María Torres Redondo, Alfredo Carrato, Patrick C Hermann, Laura Sánchez, Susana Torrente, Miguel Ángel Fernández-Moreno, José L Mascareñas, Bruno Sainz.

   BACKGROUND: Previous studies by our group have shown that oxidative phosphorylation (OXPHOS) is the main pathway by which pancreatic cancer stem cells (CSCs) meet their energetic requirements; therefore, OXPHOS represents an Achille's heel of these highly tumorigenic cells. Unfortunately, therapies that target OXPHOS in CSCs are lacking.
METHODS: The safety and anti-CSC activity of a ruthenium complex featuring bipyridine and terpyridine ligands and one coordination labile position (Ru1) were evaluated across primary pancreatic cancer cultures and in vivo, using 8 patient-derived xenografts (PDXs). RNAseq analysis followed by mitochondria-specific molecular assays were used to determine the mechanism of action.
RESULTS: We show that Ru1 is capable of inhibiting CSC OXPHOS function in vitro, and more importantly, it presents excellent anti-cancer activity, with low toxicity, across a large panel of human pancreatic PDXs, as well as in colorectal cancer and osteosarcoma PDXs. Mechanistic studies suggest that this activity stems from Ru1 binding to the D-loop region of the mitochondrial DNA of CSCs, inhibiting OXPHOS complex-associated transcription, leading to reduced mitochondrial oxygen consumption, membrane potential, and ATP production, all of which are necessary for CSCs, which heavily depend on mitochondrial respiration.
CONCLUSIONS: Overall, the coordination complex Ru1 represents not only an exciting new anti-cancer agent, but also a molecular tool to dissect the role of OXPHOS in CSCs. Results indicating that the compound is safe, non-toxic and highly effective in vivo are extremely exciting, and have allowed us to uncover unprecedented mechanistic possibilities to fight different cancer types based on targeting CSC OXPHOS.

Keywords:  Anti-cancer agents; Cancer stem cells; Colon cancer; Mitochondrial DNA; Oxidative phosphorylation; Pancreatic ductal adenocarcinoma; Patient-derived xenografts; Ruthenium complexes

DOI:  https://doi.org/10.1186/s13046-023-02931-7
J Int Soc Sports Nutr. 2024 Dec;21(1): 2306308

The effect of the ketogenic diet on resistance training load management: a repeated-measures clinical trial in trained participants.

Salvador Vargas-Molina, Manuel García-Sillero, Diego A Bonilla, Jorge L Petro, Jerónimo García-Romero, Javier Benítez-Porres.

   BACKGROUND: The effect of low-carbohydrate high-fat dietary manipulation, such as the ketogenic diet (KD), on muscle strength assessment in resistance-training (RT) participants has focused on the one-repetition maximum test (1-RM). However, a pre-specified 1-RM value during an exercise training program disregards several confounding factors (i.e. sleep, diet, and training-induced fatigue) that affect the exerciser's "true" load and daily preparedness. We aimed to evaluate the effect of a 6-week RT program on load control-related variables in trained subjects following a KD intervention.
METHODS: Fourteen resistance-trained individuals (3F, 11 M; 30.1 [6.2] years; 174.2 [7.6] cm; 75.7 [10.8] kg; BMI 24.8 [2.1] kg·m-2) completed this single-arm repeated-measures clinical trial. Load management variables included volume load, number of repetitions, perceived exertion (RPE), movement velocity loss, and exertion index. These primary outcomes were assessed weekly before, during, and at the end of a 6-week RT program that included traditional RT exercises (bench press, femoral lying down, lat pulldown, leg extension, and back squat).
RESULTS: There was a significant difference in RPE between weeks (p = 0.015, W = 0.19) with a slight trend in decreasing RPE. We found differences in the volume load per week (p < 0.001; W = 0.73 and p < 0.001, W = 0.81, respectively), with an increase in the last weeks. In the control of the load based on movement velocity, we did not find significant differences between weeks (p = 0.591, W = 0.06), although significant differences were found in the effort index (p = 0.026, W = 0.17).
CONCLUSIONS: A KD diet in recreational strength participants does not appear to lead to performance losses during a RT program aimed at improving body composition. However, the lack of adherence and familiarity with the ketogenic diet must be considered specially during first weeks.

Keywords:  Ketosis; movement velocity; muscle strength; physical exertion; workload

DOI:  https://doi.org/10.1080/15502783.2024.2306308
J Biol Chem. 2024 Jan 30. pii: S0021-9258(24)00073-5. [Epub ahead of print] 105697

Decreased pyruvate dehydrogenase activity in Tafazzin-deficient cells is caused by dysregulation of pyruvate dehydrogenase phosphatase 1 (PDP1).

Zhuqing Liang, Tyler Ralph-Epps, Michael W Schmidtke, Vikalp Kumar, Miriam L Greenberg.

Cardiolipin (CL), the signature lipid of the mitochondrial inner membrane, is critical for maintaining optimal mitochondrial function and bioenergetics. Disruption of CL metabolism, caused by mutations in the CL remodeling enzyme TAFAZZIN, results in the rare and life-threatening disorder Barth syndrome (BTHS). While the clinical manifestations of BTHS, such as dilated cardiomyopathy and skeletal myopathy, point to defects in mitochondrial bioenergetics, the disorder is also characterized by broad metabolic dysregulation, including abnormal levels of metabolites associated with the tricarboxylic acid (TCA) cycle. In line with this, recent studies have identified inhibition of pyruvate dehydrogenase (PDH), the gatekeeper enzyme for TCA cycle carbon influx, as a key deficiency in various BTHS model systems. However, the molecular mechanisms linking aberrant CL remodeling, particularly the primary, direct consequence of reduced tetralinoleoyl-CL (TLCL) levels, to PDH activity deficiency are not yet understood. This knowledge gap has limited our understanding of lipid-mediated metabolic regulation in BTHS and hindered the development of effective treatment strategies. In the current study, we provide evidence that remodeled TLCL promotes PDH function by directly binding to and enhancing the activity of PDH phosphatase 1 (PDP1). This is supported by our findings that TLCL uniquely activates PDH in a dose-dependent manner, TLCL binds to PDP1 in vitro, TLCL-mediated PDH activation is attenuated in the presence of phosphatase inhibitor, and PDP1 activity is decreased in Tafazzin-knockout (TAZ-KO) C2C12 myoblasts. Additionally, we observed decreased mitochondrial calcium levels in TAZ-KO cells, which may affect the calcium-sensitive activity of PDP1. Treating TAZ-KO cells with calcium lactate (CaLac) increases mitochondrial calcium and restores PDH activity and mitochondrial oxygen consumption rate. Based on our findings, we conclude that reduced mitochondrial calcium levels and decreased binding of PDP1 to TLCL contribute to decreased PDP1 activity in TAZ-KO cells.

DOI: https://doi.org/10.1016/j.jbc.2024.105697
Nat Commun. 2024 Jan 29. 15(1): 846

A universal metabolite repair enzyme removes a strong inhibitor of the TCA cycle.

Anthony J Zmuda, Xiaojun Kang, Katie B Wissbroecker, Katrina Freund Saxhaug, Kyle C Costa, Adrian D Hegeman, Thomas D Niehaus.

A prevalent side-reaction of succinate dehydrogenase oxidizes malate to enol-oxaloacetate (OAA), a metabolically inactive form of OAA that is a strong inhibitor of succinate dehydrogenase. We purified from cow heart mitochondria an enzyme (OAT1) with OAA tautomerase (OAT) activity that converts enol-OAA to the physiological keto-OAA form, and determined that it belongs to the highly conserved and previously uncharacterized Fumarylacetoacetate_hydrolase_domain-containing protein family. From all three domains of life, heterologously expressed proteins were shown to have strong OAT activity, and ablating the OAT1 homolog caused significant growth defects. In Escherichia coli, expression of succinate dehydrogenase was necessary for OAT1-associated growth defects to occur, and ablating OAT1 caused a significant increase in acetate and other metabolites associated with anaerobic respiration. OAT1 increased the succinate dehydrogenase reaction rate by 35% in in vitro assays with physiological concentrations of both succinate and malate. Our results suggest that OAT1 is a universal metabolite repair enzyme that is required to maximize aerobic respiration efficiency by preventing succinate dehydrogenase inhibition.

DOI: https://doi.org/10.1038/s41467-024-45134-0