bims-mibica 2024-12-01 papers

bims-mibica

Biomed News

on Mitochondrial bioenergetics in cancer

Issue of 2024–12–01
twenty-two papers selected by
Kelsey Fisher-Wellman, Wake Forest University

ACSS1-dependent acetate utilization rewires mitochondrial metabolism to support AML and melanoma tumor growth and metastasis.
Rotenone adaptation promotes migration and invasion of p53-wild-type colon cancer through lipid metabolism.
UGT8 mediated sulfatide synthesis modulates BAX localization and dictates apoptosis sensitivity of colorectal cancer.
PGC-1α drives small cell neuroendocrine cancer progression toward an ASCL1-expressing subtype with increased mitochondrial capacity.
Glucose limitation protects cancer cells from apoptosis induced by pyrimidine restriction and replication inhibition.
13C Stable Isotope Tracing Reveals Distinct Fatty Acid Oxidation Pathways in Proliferative vs. Oxidative Cells.
Tissue-specific adaptations to cytochrome c oxidase deficiency shape physiological outcomes.
Decreased mitochondrial transcription factor A and mitochondrial DNA copy number promote cyclin-dependent kinase inhibitor 1A expression and reduce tumorigenic properties of colorectal cancer cells.
BCL2i-Based Therapies and Emerging Resistance in Chronic Lymphocytic Leukemia.
Structure and function of the human mitochondrial MRS2 channel.
Mitochondria-localized MBD2c facilitates mtDNA transcription and drug resistance.
Human mitochondrial peroxiredoxin Prdx3 is dually localized in the intermembrane space and matrix subcompartments.
Prospective feasibility of a minimal BH3 profiling assay in acute myeloid leukemia.
My path to citrin deficiency.
Cancer Therapies Targeting Cellular Metabolism.
Branched-chain amino acid catabolism promotes M2 macrophage polarization.
Metabolomics and 13C labelled glucose tracing to identify carbon incorporation into aberrant cell membrane glycans in cancer.
Decoding Acute Myeloid Leukemia: A Clinician's Guide to Functional Profiling.
Mitochondrial Nicotinamide Nucleotide Transhydrogenase: Role in Energy Metabolism, Redox Homeostasis, and Cancer.
Oxidative Phosphorylation as a Predictive Biomarker of Oxaliplatin Response in Colorectal Cancer.
Venetoclax plus D-CAG (decitabine, cytarabine, aclarubicin, G-CSF) for elderly or unfit patients with newly diagnosed acute myeloid leukemia: a multicenter, prospective study.
Oral azacitidine maintenance after intensive chemotherapy versus venetoclax and azacitidine: real world outcomes in newly diagnosed acute myeloid leukemia.

Cell Rep. 2024 Nov 21. pii: S2211-1247(24)01339-1. [Epub ahead of print]43(12): 114988

ACSS1-dependent acetate utilization rewires mitochondrial metabolism to support AML and melanoma tumor growth and metastasis.

Sabina I Hlavaty, Kelsey N Salcido, Katherine A Pniewski, Dzmitry Mukha, Weili Ma, Toshitha Kannan, Joel Cassel, Yellamelli V V Srikanth, Qin Liu, Andrew Kossenkov, Joseph M Salvino, Qing Chen, Zachary T Schug.

  Cancer cells often use alternative nutrient sources to support their metabolism and proliferation. One important alternative nutrient source for many cancers is acetate. Acetate is metabolized into acetyl-coenzyme A (CoA) by acetyl-CoA synthetases 1 and 2 (ACSS1 and ACSS2), which are found in the mitochondria and cytosol, respectively. We show that ACSS1 and ACSS2 are differentially expressed in cancer. Melanoma, breast cancer, and acute myeloid leukemia cells expressing ACSS1 readily use acetate for acetyl-CoA biosynthesis and to fuel mitochondrial metabolism. ACSS1-dependent acetate metabolism decreases the relative contributions of glucose and glutamine to the tricarboxylic acid (TCA) cycle and alters the pentose phosphate pathway and redox state of cancer cells. ACSS1 knockdown decreases acute myeloid leukemia burden in vivo and inhibits melanoma tumor and metastatic growth. Our study highlights a key role for ACSS1-dependent acetate metabolism for cancer growth, raising the potential for ACSS1-targeting therapies in cancer.

Keywords:  ACSS1; ACSS2; ACSS2 inhibitor; AML; CP: Cancer; CP: Metabolism; acetate; cancer; melanoma; metabolism; metastasis

DOI:  https://doi.org/10.1016/j.celrep.2024.114988
Clin Transl Oncol. 2024 Nov 29.

Rotenone adaptation promotes migration and invasion of p53-wild-type colon cancer through lipid metabolism.

Yingying Shi, Zhen Cao, Ling Ge, Lin Lei, Dan Tao, Juan Zhong, Dan Xu, Tao Geng, Xuetao Li, Ziwei Li, Shuaishuai Xing, Xinyu Wu, Zhongxu Wang, Linjun Li.

   BACKGROUND: The association between mitochondrial dysfunction and multiple metabolic adaptations is increasingly being proven. We previously elucidated that mitochondrial complex I deficiency can promote glycolysis in mut-p53 SW480 cells. However, studies have revealed a phenotype with attenuated glycolysis but enhanced fatty acid oxidation (FAO) in invasive tumors. The interplay between complex I and FAO in carcinogenesis remains obscure.
METHODS: The p53 wild-type RKO cells were exposed to rotenone over at least 2 months to acquire rotenone adaptation cells. Then the transwell invasion assays and expression of metabolic enzymes were first detected in rotenone adaptation cells to illustrate whether rotenone adaptation is correlated with the invasion and FAO. The levels of epithelial-to-mesenchymal transition (EMT)-related proteins and acetyl-CoA in rotenone adaptation cells treated with etomoxir (ETO) and acetate were evaluated to verify the role of CPT1A in regulating invasion. Finally, the levels of reactive oxygen species (ROS) were detected. Meanwhile, the invasiveness and histone acetylation levels of rotenone adaptation cells were observed after adding an ROS inhibitor (N-acetyl-L-cysteine NAC) to demonstrate the molecular connection between FAO and invasion during rotenone adaptation.
RESULTS: We found long-term exposure to rotenone (a mitochondrial complex I inhibitor) led to EMT and high CPT1A expression in wt-p53 colon cancer. The inhibition of CPT1A suppressed the invasion and reduced histone acetylation, which was rescued by supplementing with acetate. Mechanistically, ROS is crucial for lipid metabolism remodeling.
CONCLUSION: Our study provides a novel understanding of the role of complex I in lipid reprogramming facilitating colon cancer invasion and metastasis.

Keywords:  CPT1A; Histone acetylation; Migration and invasion; Mitochondrial complex I; Rotenone

DOI:  https://doi.org/10.1007/s12094-024-03785-x
Cell Death Differ. 2024 Nov 23.

UGT8 mediated sulfatide synthesis modulates BAX localization and dictates apoptosis sensitivity of colorectal cancer.

Le Zhang, Prashanthi Ramesh, Lidia Atencia Taboada, Rebecca Roessler, Dick W Zijlmans, Michiel Vermeulen, Daisy I Picavet-Havik, Nicole N van der Wel, Frédéric M Vaz, Jan Paul Medema.

Elevated de novo lipid synthesis is a remarkable adaptation of cancer cells that can be exploited for therapy. However, the role of altered lipid metabolism in the regulation of apoptosis is still poorly understood. Using thermal proteome profiling, we identified Manidipine-2HCl, targeting UGT8, a key enzyme in the synthesis of sulfatides. In agreement, lipidomic analysis indicated that sulfatides are strongly reduced in colorectal cancer cells upon treatment with Manidipine-2HCl. Intriguingly, this reduction led to severe mitochondrial swelling and a strong synergism with BH3 mimetics targeting BCL-XL, leading to the activation of mitochondria-dependent apoptosis. Mechanistically, Manidipine-2HCl enhanced mitochondrial BAX localization in a sulfatide-dependent fashion, facilitating its activation by BH3 mimetics. In conclusion, our data indicates that UGT8 mediated synthesis of sulfatides controls mitochondrial homeostasis and BAX localization, dictating apoptosis sensitivity of colorectal cancer cells.

DOI: https://doi.org/10.1038/s41418-024-01418-y
Proc Natl Acad Sci U S A. 2024 Dec 03. 121(49): e2416882121

PGC-1α drives small cell neuroendocrine cancer progression toward an ASCL1-expressing subtype with increased mitochondrial capacity.

Grigor Varuzhanyan, Chia-Chun Chen, Jack Freeland, Tian He, Wendy Tran, Kai Song, Liang Wang, Donghui Cheng, Shili Xu, Gabriella A Dibernardo, Favour N Esedebe, Vipul Bhatia, Mingqi Han, Evan R Abt, Jung Wook Park, Sanaz Memarzadeh, David B Shackelford, John K Lee, Thomas G Graeber, Orian S Shirihai, Owen N Witte.

  Adenocarcinomas from multiple tissues can converge to treatment-resistant small cell neuroendocrine (SCN) cancers composed of ASCL1, POU2F3, NEUROD1, and YAP1 subtypes. We investigated how mitochondrial metabolism influences SCN cancer (SCNC) progression. Extensive bioinformatics analyses encompassing thousands of patient tumors and human cancer cell lines uncovered enhanced expression of proliferator-activatedreceptor gamma coactivator 1-alpha (PGC-1α), a potent regulator of mitochondrial oxidative phosphorylation (OXPHOS), across several SCNCs. PGC-1α correlated tightly with increased expression of the lineage marker Achaete-scute homolog 1, (ASCL1) through a positive feedback mechanism. Analyses using a human prostate tissue-based SCN transformation system showed that the ASCL1 subtype has heightened PGC-1α expression and OXPHOS activity. PGC-1α inhibition diminished OXPHOS, reduced SCNC cell proliferation, and blocked SCN prostate tumor formation. Conversely, PGC-1α overexpression enhanced OXPHOS, validated by small-animal Positron Emission Tomography mitochondrial imaging, tripled the SCN prostate tumor formation rate, and promoted commitment to the ASCL1 lineage. These results establish PGC-1α as a driver of SCNC progression and subtype determination, highlighting metabolic vulnerabilities in SCNCs across different tissues.

Keywords:  ASCL1; PGC-1a; lung cancer; oxidative phosphorylation; prostate cancer

DOI:  https://doi.org/10.1073/pnas.2416882121
Nat Metab. 2024 Nov 26.

Glucose limitation protects cancer cells from apoptosis induced by pyrimidine restriction and replication inhibition.

Minwoo Nam, Wenxin Xia, Abdul Hannan Mir, Alexandra Jerrett, Jessica B Spinelli, Tony T Huang, Richard Possemato.

Cancer cells often experience nutrient-limiting conditions because of their robust proliferation and inadequate tumour vasculature, which results in metabolic adaptation to sustain proliferation. Most cancer cells rapidly consume glucose, which is severely reduced in the nutrient-scarce tumour microenvironment. In CRISPR-based genetic screens to identify metabolic pathways influenced by glucose restriction, we find that tumour-relevant glucose concentrations (low glucose) protect cancer cells from inhibition of de novo pyrimidine biosynthesis, a pathway that is frequently targeted by chemotherapy. We identify two mechanisms to explain this result, which is observed broadly across cancer types. First, low glucose limits uridine-5-diphosphate-glucose synthesis, preserving pyrimidine nucleotide availability and thereby prolonging the time to replication fork stalling. Second, low glucose directly modulates apoptosis downstream of replication fork stalling by suppressing BAK activation and subsequent cytochrome c release, key events that activate caspase-9-dependent mitochondrial apoptosis. These results indicate that the low glucose levels frequently observed in tumours may limit the efficacy of specific chemotherapeutic agents, highlighting the importance of considering the effects of the tumour nutrient environment on cancer therapy.

DOI: https://doi.org/10.1038/s42255-024-01166-w
Am J Physiol Cell Physiol. 2024 Nov 29.

13C Stable Isotope Tracing Reveals Distinct Fatty Acid Oxidation Pathways in Proliferative vs. Oxidative Cells.

Julia Ritterhoff, Timothy McMillen, Hanna Foundas, Roland Palkovacs, Gernot Poschet, Arianne Caudal, Yaxin Liu, Patrick Most, Matthew Walker, Rong Tian.

  The TCA cycle serves as a central hub to balance catabolic and anabolic needs of the cell, where carbon moieties can either contribute to oxidative metabolism or support biosynthetic reactions. This differential TCA cycle engagement for glucose-derived carbon has been extensively studied in cultured cells, but the fate of fatty acid (FA)-derived carbons is poorly understood. To fill the knowledge gap, we have developed a strategy to culture cells with long-chain FAs without altering cell viability. By tracing 13C-FA we show that FA oxidation (FAO) is robust in both proliferating and oxidative cells while the metabolic pathway after citrate formation is distinct. In proliferating cells, a significant portion of carbon derived from FAO exits canonical TCA cycle as citrate and converts to unlabeled malate in cytosol. Increasing FA supply or b-oxidation does not change the partition of FA-derived carbon between cytosol and mitochondria. Oxidation of glucose competes with FA derived carbon for the canonical TCA pathway thus promoting FA carbon flowing into the alternative TCA pathway. Moreover, the coupling between FAO and the canonical TCA pathway changes with the state of oxidative energy metabolism.

Keywords:  13C stable isotope tracing; FAO; TCA cycle; oxygen consumption rate

DOI:  https://doi.org/10.1152/ajpcell.00611.2023
Biochim Biophys Acta Mol Basis Dis. 2024 Nov 27. pii: S0925-4439(24)00561-1. [Epub ahead of print] 167567

Tissue-specific adaptations to cytochrome c oxidase deficiency shape physiological outcomes.

Milica Popovic, Lea Isermann, Simon Geißen, Katharina Senft, Theodoros Georgomanolis, Stephan Baldus, Christian Frezza, Aleksandra Trifunovic.

It becomes increasingly clear that the tissue specificity of mitochondrial diseases might in part rely on their ability to compensate for mitochondrial defects, contributing to the heterogeneous nature of mitochondrial diseases. Here, we investigated tissue-specific responses to cytochrome c oxidase (CIV or COX) deficiency using a mouse model with heart and skeletal muscle-specific depletion of the COX assembly factor COX10. At three weeks of age, both tissues exhibit pronounced CIV depletion but respond differently to oxidative phosphorylation (OXPHOS) impairment. Heart-specific COX10 depletion caused severe dilated cardiomyopathy, while skeletal muscle experiences less damage. Cardiac CIV deficiency triggered extensive metabolic remodelling and stress response activation, potentially worsening cardiomyopathy, whereas skeletal muscle showed no stress response or significant metabolic changes. Our findings highlight distinct tissue capacities for managing CIV deficiency, explaining how identical primary defects can lead to different phenotypic outcomes and contribute to the heterogeneous progression of mitochondrial diseases.

DOI: https://doi.org/10.1016/j.bbadis.2024.167567
Discov Oncol. 2024 Nov 24. 15(1): 701

Decreased mitochondrial transcription factor A and mitochondrial DNA copy number promote cyclin-dependent kinase inhibitor 1A expression and reduce tumorigenic properties of colorectal cancer cells.

Jessika Buchwaldt, Tania Fritsch, Monika Hartmann, Hagen Roland Witzel, Michael Kloth, Wilfried Roth, Katrin E Tagscherer, Nils Hartmann.

   PURPOSE: Colorectal cancer is one of the most common and deadliest cancer types worldwide. In the last years, changes in the mitochondrial DNA (mtDNA) copy number have been described to correlate with the prognostic outcome for colorectal cancer patients by impacting different tumorigenic properties. One key regulator of mtDNA is the mitochondrial transcription factor A (TFAM) that acts as a limiting factor of mtDNA copy number. Here, we investigated the effect of TFAM deficiency on mtDNA and tumorigenic properties in the human colorectal cancer cell line SW480.
METHODS: TFAM expression was stably downregulated in the colorectal cancer cell line SW480 using the CRISPR-Cas9 approach. To dissect the molecular alterations induced by deletion of TFAM, RNA sequencing and gene set enrichment analysis was performed on TFAM-wild-type and TFAM-deficient SW480 cells. Functional consequences of TFAM downregulation were assessed in cellular assays.
RESULTS: We showed that TFAM deficiency leads to decreased mtDNA copy number and reduced expression of mtDNA-encoded genes. TFAM-deficient cells also revealed higher activity of senescence-associated β-galactosidase and decreased cell growth parameters. Moreover, RNA sequencing showed that the expression of cyclin dependent kinase inhibitor 1A (CDKN1A/p21) is significantly increased in TFAM-deficient cells.
CONCLUSION: Our results suggest that TFAM-induced changes of the mitochondrial genome lead to upregulated CDKN1A/p21 expression in colorectal cancer cells identifying p21 as a new possible linker between mitochondria and nucleus.

Keywords:  Cell proliferation; Colon cancer; Cyclin-dependent kinase inhibitor 1A (CDKN1A/p21); Mitochondria; Mitochondrial DNA (mtDNA); Senescence; Transcription factor A mitochondrial (TFAM)

DOI:  https://doi.org/10.1007/s12672-024-01538-4
Cells. 2024 Nov 20. pii: 1922. [Epub ahead of print]13(22):

BCL2i-Based Therapies and Emerging Resistance in Chronic Lymphocytic Leukemia.

Wing Fai Li, Eleftheria Atalla, Jiaxin Dong, Marina Konopleva.

  Overexpression of the anti-apoptotic protein BCL-2 is a key factor in the pathogenesis of chronic lymphocytic leukemia (CLL) and is associated with poor clinical outcomes. Therapeutic activation of apoptosis in cancer cells using the BCL-2 inhibitor (BCL2i) venetoclax has shown remarkable efficacy in clinical trials, both as monotherapy and combination regimens. However, patients with CLL experience a highly variable clinical course, facing significant challenges in advanced stages due to disease relapse and the emergence of resistant clones. Resistance mechanisms include acquired BCL-2 mutations, alteration of pro-apoptotic and anti-apoptotic proteins, metabolic reprogramming, epigenetic changes, and aberrant signaling pathways. To address this complex disease and improve progression-free survival, strategies targeting multiple signaling pathways and mechanisms have been explored. Randomized clinical trials of venetoclax in combination with Bruton tyrosine kinase (BTK) inhibitors or CD20 monoclonal antibodies have significantly outperformed traditional chemoimmunotherapy in both treatment-naïve and relapsed patients, achieving undetectable minimal residual disease (uMRD) and durable remissions. This review explores the intricate balance between BCL-2 family proteins and their role in the intrinsic apoptosis pathway, discusses venetoclax resistance mechanisms, and highlights the evolving role of venetoclax and other BCL2i-based combination therapies in CLL treatment.

Keywords:  BCL2i; chronic lymphocytic leukemia; clinical trials; drug resistance; venetoclax

DOI:  https://doi.org/10.3390/cells13221922
Nat Struct Mol Biol. 2024 Nov 28.

Structure and function of the human mitochondrial MRS2 channel.

Zhihui He, Yung-Chi Tu, Chen-Wei Tsai, Jonathan Mount, Jingying Zhang, Ming-Feng Tsai, Peng Yuan.

The human mitochondrial RNA splicing 2 protein (MRS2) has been implicated in Mg2+ transport across mitochondrial inner membranes, thus having an important role in Mg2+ homeostasis critical for mitochondrial integrity and function. However, the molecular mechanisms underlying its fundamental channel properties such as ion selectivity and regulation remain unclear. Here we present a structural and functional investigation of MRS2. Cryo-electron microscopy structures in various ionic conditions reveal a pentameric channel architecture and the molecular basis of ion permeation and potential regulation mechanisms. Electrophysiological analyses demonstrate that MRS2 is a Ca2+-regulated, nonselective channel permeable to Mg2+, Ca2+, Na+ and K+, which contrasts with its prokaryotic ortholog, CorA, operating as a Mg2+-gated Mg2+ channel. Moreover, a conserved arginine ring within the pore of MRS2 functions to restrict cation movements, thus preventing the channel from collapsing the proton motive force that drives mitochondrial adenosine triphosphate synthesis. Together, our results provide a molecular framework for further understanding MRS2 in mitochondrial function and disease.

DOI: https://doi.org/10.1038/s41594-024-01420-5
Nat Chem Biol. 2024 Nov 28.

Mitochondria-localized MBD2c facilitates mtDNA transcription and drug resistance.

Yijie Hao, Zilong Zhou, Rui Liu, Shengqi Shen, Haiying Liu, Yingli Zhou, Yuchen Sun, Qiankun Mao, Tong Zhang, Shi-Ting Li, Zhaoji Liu, Yiyang Chu, Linchong Sun, Ping Gao, Huafeng Zhang.

Mitochondria contain a 16-kb double stranded DNA genome encoding 13 proteins essential for respiration, but the mechanisms regulating transcription and their potential role in cancer remain elusive. Although methyl-CpG-binding domain (MBD) proteins are essential for nuclear transcription, their role in mitochondrial DNA (mtDNA) transcription is unknown. Here we report that the MBD2c splicing variant translocates into mitochondria to mediate mtDNA transcription and increase mitochondrial respiration in triple-negative breast cancer (TNBC) cells. In particular, MBD2c binds the noncoding region in mtDNA and interacts with SIRT3, which in turn deacetylates and activates TFAM, a primary mitochondrial transcription factor, leading to enhanced mtDNA transcription. Furthermore, MBD2c recovered the decreased mitochondrial gene expression caused by the DNA synthesis inhibitor cisplatin, preserving mitochondrial respiration and consequently enhancing drug resistance and proliferation in TNBC cells. These data collectively demonstrate that MBD2c positively regulates mtDNA transcription, thus connecting epigenetic regulation by deacetylation with cancer cell metabolism, suggesting druggable targets to overcome resistance.

DOI: https://doi.org/10.1038/s41589-024-01776-1
Redox Biol. 2024 Nov 21. pii: S2213-2317(24)00414-2. [Epub ahead of print]78 103436

Human mitochondrial peroxiredoxin Prdx3 is dually localized in the intermembrane space and matrix subcompartments.

Fernando Gomes, Helena Turano, Luciana A Haddad, Luis E S Netto.

  Peroxiredoxin 3 (Prdx3) is the major sink for H2O2 and other hydroperoxides within mitochondria, yet the mechanisms guiding the import of its cytosolic precursor into mitochondrial sub-compartments remain elusive. Prdx3 is synthesized in the cytosol as a precursor with an N-terminal cleavable presequence, which is frequently proposed to target the protein exclusively to the mitochondrial matrix. Here, we present a comprehensive analysis of the human Prdx3 biogenesis, using highly purified mitochondria from HEK293T cells. Subfractionation and probing for specific mitochondrial markers confirmed Prdx3 localization in the matrix, while unexpectedly revealed its presence in the mitochondrial intermembrane space (IMS). Both matrix and IMS isoforms were found to be soluble proteins, as demonstrated by alkaline carbonate extraction. By combining in silico analysis, in organello import assays and heterologous expression in yeast, we found that Prdx3 undergoes sequential proteolytic processing steps by mitochondrial processing peptidase (MPP) and mitochondrial intermediate peptidase (MIP) during its import into the matrix. Additionally, heterologous expression of Prdx3 in yeast revealed that its sorting to the IMS is dependent on the inner membrane peptidase (IMP) complex. Collectively, these findings uncover a complex submitochondrial distribution of Prdx3, supporting its multifaceted role in mitochondrial H2O2 metabolism.

Keywords:  Intermembrane space (IMS); Matrix; Mitochondria; Peroxiredoxin; Prdx3

DOI:  https://doi.org/10.1016/j.redox.2024.103436
Cytometry B Clin Cytom. 2024 Nov 27.

Prospective feasibility of a minimal BH3 profiling assay in acute myeloid leukemia.

Kim Pacchiardi, Victoire de Marcellus, Tony Huynh, Sofiane Fodil, Rathana Kim, Reinaldo Dal Bello, Morgane Fontaine, Catherine Lonchamp, Laureen Chat, Lorea Aguinaga, Etienne Lengliné, Marie Sébert, Emmanuel Raffoux, Lionel Adès, Hervé Dombret, Emmanuelle Clappier, Alexandre Puissant, Stéphanie Mathis, Clémentine Chauvel, Raphael Itzykson.

  BH3 profiling can assess global mitochondrial priming and dependence of leukemic cells on specific BH3 anti-apoptotic proteins such as BCL-2. In acute myeloid leukemia (AML), proof-of-concept prognostic studies have been performed on archived samples variably accounting for molecular genetics. We undertook a single-center feasibility study of a simplified flow-based assay to determine the absolute mitochondrial priming and BCL-2 dependence in consecutive AML patients. When possible, results on the leukemic fraction were normalized to the cognate lymphocyte population (relative priming and BCL-2 dependence). Samples from 97 (89.8%) of the 108 referred patients were successfully processed. Relative priming and BCL-2 dependence could be determined in 62 (67.4%) and 67 (62.0%) samples, respectively. Absolute mitochondrial priming was lower in patients having previously failed intensive chemotherapy compared to chemotherapy-naïve patients (p = 0.01), but its prognostic impact was limited. Conversely, relative BCL-2 independence tended to predict worse EFS (HR = 2.51, p = 0.07) and OS (HR = 2.79, p = 0.10) independently of adverse genetic risk. Our results show that simplified BH3 profiling can be prospectively assessed in AML patients but that its prognostic use may require internal normalization. Future studies should compare its relevance with other functional assays such as ex vivo drug testing or BH3 protein expression.

Keywords:  BH3 profiling; acute myeloid leukemia; mitochondrial priming; prognosis

DOI:  https://doi.org/10.1002/cyto.b.22217
J Inherit Metab Dis. 2024 Nov 24.

My path to citrin deficiency.

John E Walker.

  Citrin belongs to the SLC25 transport protein family found mostly in inner mitochondrial membranes. The family prototype, the ADP-ATP carrier, delivers ATP made inside mitochondria to the cellular cytoplasm and returns ADP to the mitochondrion for resynthesis of ATP. In pre-genomic 1981, I noticed that the protein sequence of the bovine ADP-ATP carrier consists of three related sequences, each containing two transmembrane α-helices traveling in opposite senses. Colleagues and I demonstrated that two other mitochondrial carriers had similar features. From emergent genomic sequences, it became apparent that they represented a large family of transport proteins with the same characteristic threefold repeats. The human genome encodes 53 members, but the functions of many were unknown. So, colleagues and I determined how to make these proteins in Escherichia coli and introduce them into liposomes to allow exploration of their transport functions. The 27 human family members to have been thus identified include citrin and the closely related protein aralar. Both exchange aspartate from the mitochondrial matrix for cytosolic glutamate plus a proton. Citrin is expressed predominantly in liver and non-excitable tissues, whereas aralar is the dominant form in the brain. Each has a membrane extrinsic N-terminal Ca2+-binding domain, a transport domain, and a C-terminal amphipathic α-helix. Human mutations in citrin impair the urea cycle, malate-aspartate shuttle, gluconeogenesis, amino acid breakdown, and energy metabolism leading to citrin deficiency. Currently, the complex etiology of this condition is poorly understood and new knowledge would help to improve diagnosis, therapies, and finding a cure. My aims are to seek a basic understanding of the etiology of citrin deficiency and to use that knowledge in improving diagnostic procedures and in developing new treatments and a cure.

Keywords:  citrin deficiency; cure; diagnosis; mitochondria; treatment; urea cycle

DOI:  https://doi.org/10.1002/jimd.12818
Cold Spring Harb Perspect Med. 2024 Nov 25. pii: a041657. [Epub ahead of print]

Cancer Therapies Targeting Cellular Metabolism.

Benjamin Morris, Alejandro Gutierrez.

Cancer is caused by mutations that drive aberrant growth, proliferation, and invasion, thus overriding regulatory mechanisms that normally link these processes to organismal needs and cellular physiology. This imposes demands for the production of energy and biomass and for survival in microenvironments that are often nonphysiologic and nutrient-poor, which are met by rewiring of cellular metabolism. The resultant dependence of tumor cells on altered metabolism can induce sensitivity to specific metabolic perturbations that can be exploited for cancer therapy. Some cancers are caused by mutations that impart a novel function to metabolic enzymes, leading to the production of a tumor-promoting metabolite that is dispensable in normal cells, representing an ideal therapeutic target. Tumors can also exploit metabolic regulation of cellular immunity to evade antitumor immune responses, and deciphering this biology has revealed potential targets for therapeutic intervention. Here, we discuss a number of illustrative examples highlighting the therapeutic potential and the challenges of targeting metabolism for cancer therapy.

DOI: https://doi.org/10.1101/cshperspect.a041657
Front Immunol. 2024 ;15 1469163

Branched-chain amino acid catabolism promotes M2 macrophage polarization.

Manxi Lu, Da Luo, Zixuan Zhang, Feng Ouyang, Yihong Shi, Changyong Hu, Hang Su, Yining Li, Jiayi Zhang, Qian Gui, Tian-Shu Yang.

   Introduction: During an immune response, macrophages undergo systematic metabolic rewiring tailored to support their functions. Branched-chain amino acid (BCAA) metabolism has been reported to modulate macrophage function; however, its role in macrophage alternative activation remain unclear. We aimed to investigate the role of BCAA metabolism in macrophage alternative activation.
Method: The metabolomics of BMDM-derived M0 and M2 macrophages were analyzed using LC-MS. BCAAs were supplemented and genes involved in BCAA catabolism were inhibited during M2 macrophage polarization. The expression of M2 marker genes was assessed through RT-qPCR, immunofluorescence, and flow cytometry.
Results and discussion: Metabolomic analysis identified increased BCAA metabolism as one of the most significantly rewired pathways upon alternative activation. M2 macrophages had significantly lower BCAA levels compared to controls. BCAA supplementation promoted M2 macrophage polarization both in vitro and in vivo and increased oxidative phosphorylation in M2 macrophages. Blocking BCAA entry into mitochondria by knockdown of SLC25A44 inhibited M2 macrophage polarization. Furthermore, M2 macrophages polarization was suppressed by knockdown of Branched-chain amino-acid transaminase 2 (BCAT2) and branched chain keto acid dehydrogenase E1 subunit alpha (BCKDHA), both of which are key enzymes involved in BCAA oxidation. Overall, our findings suggest that BCAA catabolism plays an important role in polarization toward M2 macrophages.

Keywords:  BCAA; BCAT2; BCKDHA; M2 macrophages; SLC25A44

DOI:  https://doi.org/10.3389/fimmu.2024.1469163
Commun Biol. 2024 Nov 26. 7(1): 1576

Metabolomics and 13C labelled glucose tracing to identify carbon incorporation into aberrant cell membrane glycans in cancer.

Alfredo Reyes-Oliveras, Abigail E Ellis, Ryan D Sheldon, Brian Haab.

Cell membrane glycans contribute to immune recognition, signaling, and cellular adhesion and migration, and altered membrane glycosylation is a feature of cancer cells that contributes to cancer progression. The uptake and metabolism of glucose and other nutrients essential for glycan synthesis could underlie altered membrane glycosylation, but the relationship between shifts in nutrient metabolism and the effects on glycans have not been directly examined. We developed a method that combines stable isotope tracing with metabolomics to enable direct observations of glucose allocation to nucleotide sugars and cell-membrane glycans. We compared the glucose allocation to membrane glycans of two pancreatic cancer cell lines that are genetically identical but have differing energy requirements. The 8988-S cells had higher glucose allocation to membrane glycans and intracellular pathways relating to glycan synthesis, but the 8988-T cells had higher glucose uptake and commitment of glucose to non-glycosylation pathways. The cell lines differed in the requirements of glucose for energy production, resulting in differences in glucose bioavailability for glycan synthesis. The workflow demonstrated here enables studies on the effects of metabolic shifts on the commitment of nutrients to cell-membrane glycans. The results suggest that cell-membrane glycans are remodeled through shifts in glucose commitment to non-glycosylation pathways.

DOI: https://doi.org/10.1038/s42003-024-07277-0
Diagnostics (Basel). 2024 Nov 14. pii: 2560. [Epub ahead of print]14(22):

Decoding Acute Myeloid Leukemia: A Clinician's Guide to Functional Profiling.

Prasad Iyer, Shaista Shabbir Jasdanwala, Yuhan Wang, Karanpreet Bhatia, Shruti Bhatt.

  Acute myeloid leukemia (AML) is a complex clonal disorder characterized by clinical, genetic, metabolomic, and epigenetic heterogeneity resulting in the uncontrolled proliferation of aberrant blood-forming precursor cells. Despite advancements in the understanding of the genetic, metabolic, and epigenetic landscape of AML, it remains a significant therapeutic challenge. Functional profiling techniques, such as BH3 profiling (BP), gene expression profiling (GEP), proteomics, metabolomics, drug sensitivity/resistance testing (DSRT), CRISPR/Cas9, and RNAi screens offer valuable insights into the functional behavior of leukemia cells. BP evaluates the mitochondrial response to pro-apoptotic BH3 peptides, determining a cell's apoptotic threshold and its reliance on specific anti-apoptotic proteins. This knowledge can pinpoint vulnerabilities in the mitochondria-mediated apoptotic pathway in leukemia cells, potentially informing treatment strategies and predicting therapeutic responses. GEP, particularly RNA sequencing, evaluates the transcriptomic landscape and identifies gene expression alterations specific to AML subtypes. Proteomics and metabolomics, utilizing mass spectrometry and nuclear magnetic resonance (NMR), provide a detailed view of the active proteins and metabolic pathways in leukemia cells. DSRT involves exposing leukemia cells to a panel of chemotherapeutic and targeted agents to assess their sensitivity or resistance profiles and potentially guide personalized treatment strategies. CRISPR/Cas9 and RNAi screens enable systematic disruption of genes to ascertain their roles in leukemia cell survival and proliferation. These techniques facilitate precise disease subtyping, uncover novel biomarkers and therapeutic targets, and provide a deeper understanding of drug-resistance mechanisms. Recent studies utilizing functional profiling have identified specific mutations and gene signatures associated with aggressive AML subtypes, aberrant signaling pathways, and potential opportunities for drug repurposing. The integration of multi-omics approaches, advances in single-cell sequencing, and artificial intelligence is expected to refine the precision of functional profiling and ultimately improve patient outcomes in AML. This review highlights the diverse landscape of functional profiling methods and emphasizes their respective advantages and limitations. It highlights select successes in how these methods have further advanced our understanding of AML biology, identifies druggable targets that have improved outcomes, delineates challenges associated with these techniques, and provides a prospective view of the future where these techniques are likely to be increasingly incorporated into the routine care of patients with AML.

Keywords:  BH3 profiling; acute myeloid leukemia; drug sensitivity/resistance testing; functional profiling; gene expression profiling; metabolomics; proteomics

DOI:  https://doi.org/10.3390/diagnostics14222560
Antioxid Redox Signal. 2024 Nov;41(13-15): 927-956

Mitochondrial Nicotinamide Nucleotide Transhydrogenase: Role in Energy Metabolism, Redox Homeostasis, and Cancer.

Zhuohui Gan, Inge van der Stelt, Weiwei Li, Liangyu Hu, Jingyi Song, Sander Grefte, Els van de Westerlo, Deli Zhang, Evert M van Schothorst, Hedi L Claahsen-van der Grinten, Katja J Teerds, Merel J W Adjobo-Hermans, Jaap Keijer, Werner J H Koopman.

  Significance: Dimeric nicotinamide nucleotide transhydrogenase (NNT) is embedded in the mitochondrial inner membrane and couples the conversion of NADP+/NADH into NADPH/NAD+ to mitochondrial matrix proton influx. NNT was implied in various cancers, but its physiological role and regulation still remain incompletely understood. Recent Advances: NNT function was analyzed by studying: (1) NNT gene mutations in human (adrenal) glucocorticoid deficiency 4 (GCCD4), (2) Nnt gene mutation in C57BL/6J mice, and (3) the effect of NNT knockdown/overexpression in (cancer) cells. In these three models, altered NNT function induced both common and differential aberrations. Critical Issues: Information on NNT protein expression in GCCD4 patients is still scarce. Moreover, NNT expression levels are tissue-specific in humans and mice and the functional consequences of NNT deficiency strongly depend on experimental conditions. In addition, data from intact cells and isolated mitochondria are often unsuited for direct comparison. This prevents a proper understanding of NNT-linked (patho)physiology in GCCD4 patients, C57BL/6J mice, and cancer (cell) models, which complicates translational comparison. Future Directions: Development of mice with conditional NNT deletion, cell-reprogramming-based adrenal (organoid) models harboring specific NNT mutations, and/or NNT-specific chemical inhibitors/activators would be useful. Moreover, live-cell analysis of NNT substrate levels and mitochondrial/cellular functioning with fluorescent reporter molecules might provide novel insights into the conditions under which NNT is active and how this activity links to other metabolic and signaling pathways. This would also allow a better dissection of local signaling and/or compartment-specific (i.e., mitochondrial matrix, cytosol, nucleus) effects of NNT (dys)function in a cellular context. Antioxid. Redox Signal. 41, 927-956.

Keywords:  NNT; bioenergetics; cancer; experimental models; mitochondria; redox homeostasis

DOI:  https://doi.org/10.1089/ars.2024.0694
Biomolecules. 2024 Oct 25. pii: 1359. [Epub ahead of print]14(11):

Oxidative Phosphorylation as a Predictive Biomarker of Oxaliplatin Response in Colorectal Cancer.

Toni Martinez-Bernabe, Daniel G Pons, Jordi Oliver, Jorge Sastre-Serra.

  Oxaliplatin is successfully used on advanced colorectal cancer to eradicate micro-metastasis, whereas its benefits in the early stages of colorectal cancer remains controversial since approximately 30% of patients experience unexpected relapses. Herein, we evaluate the efficacy of oxidative phosphorylation as a predictive biomarker of oxaliplatin response in colorectal cancer. We found that non-responding patients exhibit low oxidative phosphorylation activity, suggesting a poor prognosis. To reach this conclusion, we analyzed patient samples of individuals treated with oxaliplatin from the GSE83129 dataset, and a set of datasets validated using ROCplotter, selecting them based on their response to the drug. By analyzing multiple oxaliplatin-resistant and -sensitive cell lines, we identified oxidative phosphorylation KEGG pathways as a valuable predictive biomarker of oxaliplatin response with a high area under the curve (AUC = 0.843). Additionally, some oxidative phosphorylation-related biomarkers were validated in primary- and metastatic-derived tumorspheres, confirming the results obtained in silico. The low expression of these biomarkers is clinically relevant, indicating poor prognosis with decreased overall and relapse-free survival. This study proposes using oxidative phosphorylation-related protein expression levels as a predictor of responses to oxaliplatin-based treatments to prevent relapse and enable a more personalized therapy approach. Our results underscore the value of oxidative phosphorylation as a reliable marker for predicting the response to oxaliplatin treatment in colorectal cancer.

Keywords:  biomarkers; colorectal cancer; oxaliplatin; oxidative phosphorylation; resistance

DOI:  https://doi.org/10.3390/biom14111359
Ann Hematol. 2024 Nov 26.

Venetoclax plus D-CAG (decitabine, cytarabine, aclarubicin, G-CSF) for elderly or unfit patients with newly diagnosed acute myeloid leukemia: a multicenter, prospective study.

Hongbing Ma, Yiwen Du, Jianjun Li, Jin Rao, Yong Guo, YunFan Yang, Duanzhong Zhang, Jia Wang, Yi Liao, Yuping Gong.

  Induction regimens with satisfactory remission rates are limited for patients with acute myeloid leukemia (AML) who are elderly or ineligible for intensive chemotherapy. This study is a single-arm, multicenter, prospective phase I/II study (registered with the Chinese Clinical Trial Registry as ChiCTR 2200059694 on May 8, 2022), aiming to evaluate the efficacy and safety of venetoclax plus decitabine, cytarabine, aclarubicin, and granulocyte colony-stimulating factor (VD-CAG) for newly diagnosed AML patients who are elderly or ineligible for intensive chemotherapy. The primary endpoint was composite complete remission (CRc) after 1 cycle of induction chemotherapy. The secondary endpoints were measurable residual disease (MRD) by flow cytometry and adverse events. Forty patients(n = 40) received 1 cycle of the VD-CAG regimen for induction chemotherapy. The median age of the patients was 64 (55-81) years, and 10 patients (25%) had secondary AML. Our results showed that 1 cycle of VD-CAG had a high overall response rate of 97.5% and CRc of 95%, and all 10 patients with secondary AML achieved CRc. Moreover, the patients who achieved CRc had deep remission, with MRD-negativity of 71.1% and 54.2% by flow cytometry and molecular assessment, respectively. In addition, blood cell recovery was quick, with a median time to absolute neutrophil count ≥ 1.0 × 109/L and platelet count ≥ 100 × 109/L at 19 days and 15.5 days, respectively. In conclusion, VD-CAG demonstrates high efficacy as an induction treatment for elderly or unfit patients with newly diagnosed AML, and it could be an alternative upfront therapy for this subpopulation, Trials with large-scale subjects are needed for further validation, especially for secondary AML.

Keywords:  Aclarubicin; Acute myeloid leukemia; Decitabine; Induction chemotherapy; Venetoclax

DOI:  https://doi.org/10.1007/s00277-024-06097-w
Leuk Lymphoma. 2024 Nov 28. 1-9

Oral azacitidine maintenance after intensive chemotherapy versus venetoclax and azacitidine: real world outcomes in newly diagnosed acute myeloid leukemia.

Alice Mims, Zhuoer Xie, Ravi Potluri, David Rotter, Manoj Chevli, Thomas Prebet, Lona Gaugler, Maria Strocchia, Alberto Vasconcelos, Jan Sieluk.

  Oral azacitidine (Oral-AZA) is recommended as maintenance therapy for patients with newly diagnosed acute myeloid leukemia (ND AML) achieving remission with intensive chemotherapy (IC) but not transplant candidates; venetoclax plus injectable azacitidine (VEN-AZA) is recommended for patients ineligible for IC. Some patients may be considered candidates for either regimen. This retrospective study used Flatiron Health's database to compare treatment patterns and clinical outcomes with Oral-AZA maintenance after IC (IC🡪Oral-AZA) versus frontline VEN-AZA. Relapse-free survival (RFS) and overall survival (OS) were analyzed at 4 different time points, including from Oral-AZA initiation (IC🡪Oral-AZA cohort) or from remission (VEN-AZA cohort) in the Core Analysis. Median RFS was 14.9 and 8.1 months for IC🡪Oral-AZA and VEN-AZA propensity score-matched cohorts, in the Core Analysis (n = 32 in each; p = 0.027); median OS was 18.7 and 15.2 months (p = 0.034). In patients with AML, IC🡪Oral-AZA significantly improved RFS and OS compared with VEN-AZA.

Keywords:  Acute myeloid leukemia; health outcomes research; oral azacitidine; real-world evidence

DOI:  https://doi.org/10.1080/10428194.2024.2425792