bims-mibica 2024-10-20 papers

bims-mibica

Biomed News

on Mitochondrial bioenergetics in cancer

Issue of 2024‒10‒20
twenty-six papers selected by
Kelsey Fisher-Wellman, Wake Forest University

Venetoclax triggers sublethal apoptotic signaling in venetoclax-resistant acute myeloid leukemia cells and induces vulnerability to PARP inhibition and azacitidine.
Inhibition of BAK-mediated apoptosis by the BH3-only protein BNIP5.
Somatic mitochondrial DNA mutations are a source of heterogeneity among primary leukemic cells.
Direct mitochondrial import of lactate supports resilient carbohydrate oxidation.
Optogenetic Control of the Mitochondrial Protein Import in Mammalian Cells.
The Novel Anticancer Aryl-Ureido Fatty Acid CTU Increases Reactive Oxygen Species Production That Impairs Mitochondrial Fusion Mechanisms and Promotes MDA-MB-231 Cell Death.
Mitophagy as a guardian against cellular aging.
Comprehensive functional evaluation of head and neck squamous cell carcinoma with BH3-profiling demonstrates apoptotic competency and therapeutic efficacy of BH3-mimetics.
Autophagy adaptors mediate Parkin-dependent mitophagy by forming sheet-like liquid condensates.
Single-cell mitochondrial sequencing reveals low-frequency mitochondrial mutations in naturally aging mice.
Catabolism of extracellular glutathione supplies amino acids to support tumor growth.
Distinct roles for the domains of the mitochondrial aspartate/glutamate carrier citrin in organellar localization and substrate transport.
Targeting NAD+ Metabolism Vulnerability in FH-Deficient Hereditary Leiomyomatosis and Renal Cell Carcinoma with the novel NAMPT Inhibitor OT-82.
Analysis of Somatic Mutations in Senescent Cells Using Single-Cell Whole-Genome Sequencing.
Apoptosis-induced translocation of nesprin-2 from the nuclear envelope to mitochondria is associated with mitochondrial dysfunction.
Cardiolipin deficiency disrupts CoQ redox state and induces steatohepatitis.
Tumor microenvironment induced switch to mitochondrial metabolism promotes suppressive functions in immune cells.
Mitochondria's Role in the Maintenance of Cancer Stem Cells in Hepatocellular Carcinoma.
Ndufs4 knockout mice with isolated complex I deficiency engage a futile adaptive brain response.
A whole food, plant-based diet reduces amino acid levels in patients with metastatic breast cancer.
Molecular mechanisms of mitochondrial dynamics.
Regulation of CD8+ T cells by lipid metabolism in cancer progression.
Quantifying constraint in the human mitochondrial genome.
Defective ribosome assembly impairs leukemia progression in a murine model of acute myeloid leukemia.
Emerging roles of small extracellular vesicles in metabolic reprogramming and drug resistance in cancers.
Targetable treatment resistance in thyroid cancer with clonal hematopoiesis.

Cell Death Dis. 2024 Oct 16. 15(10): 750

Venetoclax triggers sublethal apoptotic signaling in venetoclax-resistant acute myeloid leukemia cells and induces vulnerability to PARP inhibition and azacitidine.

Mahesh Tambe, Sarah Unterberger, Mette C Kriegbaum, Ida Vänttinen, Ezgi June Olgac, Markus Vähä-Koskela, Mika Kontro, Krister Wennerberg, Caroline A Heckman.

Venetoclax plus azacitidine treatment is clinically beneficial for elderly and unfit acute myeloid leukemia (AML) patients. However, the treatment is rarely curative, and relapse due to resistant disease eventually emerges. Since no current clinically feasible treatments are known to be effective at the state of acquired venetoclax resistance, this is becoming a major challenge in AML treatment. Studying venetoclax-resistant AML cell lines, we observed that venetoclax induced sublethal apoptotic signaling and DNA damage even though cell survival and growth were unaffected. This effect could be due to venetoclax inducing a sublethal degree of mitochondrial outer membrane permeabilization. Based on these results, we hypothesized that the sublethal apoptotic signaling induced by venetoclax could constitute a vulnerability in venetoclax-resistant AML cells. This was supported by screens with a broad collection of drugs, where we observed a synergistic effect between venetoclax and PARP inhibition in venetoclax-resistant cells. Additionally, the venetoclax-PARP inhibitor combination prevented the acquisition of venetoclax resistance in treatment naïve AML cell lines. Furthermore, the addition of azacitidine to the venetoclax-PARP inhibitor combination enhanced venetoclax induced DNA damage and exhibited exceptional sensitivity and long-term responses in the venetoclax-resistant AML cell lines and samples from AML patients that had clinically relapsed under venetoclax-azacitidine therapy. In conclusion, we mechanistically identify a new vulnerability in acquired venetoclax-resistant AML cells and identify PARP inhibition as a potential therapeutic approach to overcome acquired venetoclax resistance in AML.

DOI: https://doi.org/10.1038/s41419-024-07140-4
Cell Death Differ. 2024 Oct 15.

Inhibition of BAK-mediated apoptosis by the BH3-only protein BNIP5.

Sebastian Rühl, Zhenrui Li, Shagun Srivastava, Luigi Mari, Clifford S Guy, Mao Yang, Tudor Moldoveanu, Douglas R Green.

BCL-2 family proteins regulate apoptosis by initiating mitochondrial outer membrane permeabilization (MOMP). Activation of the MOMP effectors BAX and BAK is controlled by the interplay of anti-apoptotic BCL-2 proteins (e.g., MCL-1) and pro-apoptotic BH3-only proteins (e.g., BIM). Using a genome-wide CRISPR-dCas9 transactivation screen we identified BNIP5 as an inhibitor of BAK-, but not BAX-induced apoptosis. BNIP5 blocked BAK activation in different cell types and in response to various cytotoxic therapies. The BH3 domain of BNIP5 was both necessary and sufficient to block BAK activation. Mechanistically, the BH3 domain of BNIP5 acts as a selective BAK activator, but a poor de-repressor of complexes between BAK and pro-survival BCL-2 family proteins. By promoting the binding of activated BAK to MCL-1 or BCL-xL, BNIP5 inhibits apoptosis when BAX is absent. Based on our observations, BNIP5 can act functionally as an anti-apoptotic BH3-only protein.

DOI: https://doi.org/10.1038/s41418-024-01386-3
medRxiv. 2024 Sep 27. pii: 2024.09.26.24314381. [Epub ahead of print]

Somatic mitochondrial DNA mutations are a source of heterogeneity among primary leukemic cells.

Kelly McCastlain, Catherine Welsh, Yonghui Ni, Liang Ding, Melissa Franco, Robert Autry, Besian Sejdiu, Ti-Cheng Chang, Wenan Chen, Huiyun Wu, Qingfei Pan, Veronica Gonzalez-Pena, Patrick Schreiner, Sasi Arunachalam, Joung Joo, Benshang Li, Shuhong Shen, Samuel Brady, Jinghui Zhang, Charles Gawad, William Evans, M Madan Babu, Konstantin Khrapko, Gang Wu, Jiyang Yu, Stanley Pounds, Mondira Kundu.

Somatic mitochondrial DNA (mtDNA) mutations are prevalent in tumors, yet defining their biological significance remains challenging due to the intricate interplay between selective pressure, heteroplasmy, and cell state. Utilizing bulk whole-genome sequencing data from matched tumor and normal samples from two cohorts of pediatric cancer patients, we uncover differences in the accumulation of synonymous and nonsynonymous mtDNA mutations in pediatric leukemias, indicating distinct selective pressures. By integrating single-cell sequencing (SCS) with mathematical modeling and network-based systems biology approaches, we identify a correlation between the extent of cell-state changes associated with tumor-enriched mtDNA mutations and the selective pressures shaping their distribution among individual leukemic cells. Our findings also reveal an association between specific heteroplasmic mtDNA mutations and cellular responses that may contribute to functional heterogeneity among leukemic cells and influence their fitness. This study highlights the potential of SCS strategies for distinguishing between pathogenic and passenger somatic mtDNA mutations in cancer.

DOI: https://doi.org/10.1101/2024.09.26.24314381
bioRxiv. 2024 Oct 08. pii: 2024.10.07.617073. [Epub ahead of print]

Direct mitochondrial import of lactate supports resilient carbohydrate oxidation.

Ahmad A Cluntun, Joseph R Visker, Jesse N Velasco-Silva, Marisa J Lang, Luis Cedeño-Rosario, Thirupura S Shankar, Rana Hamouche, Jing Ling, Ji Eon Kim, Ashish G Toshniwal, Hayden K Low, Corey N Cunningham, James Carrington, Jonathan Leon Catrow, Quentinn Pearce, Mi-Young Jeong, Alex J Bott, Álvaro J Narbona-Pérez, Claire E Stanley, Qing Li, David R Eberhardt, Jeffrey T Morgan, Tarun Yadav, Chloe E Wells, Dinesh K A Ramadurai, Wojciech I Swiatek, Dipayan Chaudhuri, Jeffery D Rothstein, Deborah M Muoio, Joao A Paulo, Steven P Gygi, Steven A Baker, Sutip Navankasattusas, James E Cox, Katsuhiko Funai, Stavros G Drakos, Jared Rutter, Gregory S Ducker.

Lactate is the highest turnover circulating metabolite in mammals. While traditionally viewed as a waste product, lactate is an important energy source for many organs, but first must be oxidized to pyruvate for entry into the tricarboxylic acid cycle (TCA cycle). This reaction is thought to occur in the cytosol, with pyruvate subsequently transported into mitochondria via the mitochondrial pyruvate carrier (MPC). Using 13 C stable isotope tracing, we demonstrated that lactate is oxidized in the myocardial tissue of mice even when the MPC is genetically deleted. This MPC-independent lactate import and mitochondrial oxidation is dependent upon the monocarboxylate transporter 1 (MCT1/ Slc16a1 ). Mitochondria isolated from the myocardium without MCT1 exhibit a specific defect in mitochondrial lactate, but not pyruvate, metabolism. The import and subsequent mitochondrial oxidation of lactate by mitochondrial lactate dehydrogenase (LDH) acts as an electron shuttle, generating sufficient NADH to support respiration even when the TCA cycle is disrupted. In response to diverse cardiac insults, animals with hearts lacking MCT1 undergo rapid progression to heart failure with reduced ejection fraction. Thus, the mitochondrial import and oxidation of lactate enables carbohydrate entry into the TCA cycle to sustain cardiac energetics and maintain myocardial structure and function under stress conditions.

DOI: https://doi.org/10.1101/2024.10.07.617073
Cells. 2024 Oct 09. pii: 1671. [Epub ahead of print]13(19):

Optogenetic Control of the Mitochondrial Protein Import in Mammalian Cells.

Lukas F J Althoff, Markus M Kramer, Benjamin Bührer, Denise Gaspar, Gerald Radziwill.

  Mitochondria provide cells with energy and regulate the cellular metabolism. Almost all mitochondrial proteins are nuclear-encoded, translated on ribosomes in the cytoplasm, and subsequently transferred to the different subcellular compartments of mitochondria. Here, we developed OptoMitoImport, an optogenetic tool to control the import of proteins into the mitochondrial matrix via the presequence pathway on demand. OptoMitoImport is based on a two-step process: first, light-induced cleavage by a TEV protease cuts off a plasma membrane-anchored fusion construct in close proximity to a mitochondrial targeting sequence; second, the mitochondrial targeting sequence preceding the protein of interest recruits to the outer mitochondrial membrane and imports the protein fused to it into mitochondria. Upon reaching the mitochondrial matrix, the matrix processing peptidase cuts off the mitochondrial targeting sequence and releases the protein of interest. OptoMitoImport is available as a two-plasmid system as well as a P2A peptide or IRES sequence-based bicistronic system. Fluorescence studies demonstrate the release of the plasma membrane-anchored protein of interest through light-induced TEV protease cleavage and its localization to mitochondria. Cell fractionation experiments confirm the presence of the peptidase-cleaved protein of interest in the mitochondrial fraction. The processed product is protected from proteinase K treatment. Depletion of the membrane potential across the inner mitochondria membrane prevents the mitochondrial protein import, indicating an import of the protein of interest by the presequence pathway. These data demonstrate the functionality of OptoMitoImport as a generic system with which to control the post-translational mitochondrial import of proteins via the presequence pathway.

Keywords:  CRY2; LOV domain; MTS; TEV; matrix peptidases; mitochondrial import; optogenetics

DOI:  https://doi.org/10.3390/cells13191671
Int J Mol Sci. 2024 Oct 01. pii: 10577. [Epub ahead of print]25(19):

The Novel Anticancer Aryl-Ureido Fatty Acid CTU Increases Reactive Oxygen Species Production That Impairs Mitochondrial Fusion Mechanisms and Promotes MDA-MB-231 Cell Death.

Stanton Tam, Balasubrahmanyam Umashankar, Md Khalilur Rahman, Hassan Choucair, Tristan Rawling, Michael Murray.

  Cancer cell mitochondria are functionally different from those in normal cells and could be targeted to develop novel anticancer agents. The aryl-ureido fatty acid CTU (16({[4-chloro-3-(trifluoromethyl)phenyl]-carbamoyl}amino)hexadecanoic acid) is the prototype of a new class of targeted agents that enhance the production of reactive oxygen species (ROS) that disrupt the outer mitochondrial membrane (OMM) and kill cancer cells. However, the mechanism by which CTU disrupts the inner mitochondrial membrane (IMM) and activates apoptosis is not clear. Here, we show that CTU-mediated ROS selectively dysregulated the OMA1/OPA1 fusion regulatory system located in the IMM. The essential role of ROS was confirmed in experiments with the lipid peroxyl scavenger α-tocopherol, which prevented the dysregulation of OMA1/OPA1 and CTU-mediated MDA-MB-231 cell killing. The disruption of OMA1/OPA1 and IMM fusion by CTU-mediated ROS accounted for the release of cytochrome c from the mitochondria and the activation of apoptosis. Taken together, these findings demonstrate that CTU depolarises the mitochondrial membrane, activates ROS production, and disrupts both the IMM and OMM, which releases cytochrome c and activates apoptosis. Mitochondrial-targeting agents like CTU offer a novel approach to the development of new therapeutics with anticancer activity.

Keywords:  anticancer agent; aryl-ureido fatty acids; mitochondrial fission and fusion; mitochondrial membrane; reactive oxygen species

DOI:  https://doi.org/10.3390/ijms251910577
Autophagy. 2024 Oct 14. 1-3

Mitophagy as a guardian against cellular aging.

Tetsushi Kataura, Niall Wilson, Gailing Ma, Viktor I Korolchuk.

  Mitophagy, the selective autophagic clearance of damaged mitochondria, is considered vital for maintaining mitochondrial quality and cellular homeostasis; however, its molecular mechanisms, particularly under basal conditions, and its role in cellular physiology remain poorly characterized. We recently demonstrated that basal mitophagy is a key feature of primary human cells and is downregulated by immortalization, suggesting its dependence on the primary cell state. Mechanistically, we demonstrated that the PINK1-PRKN-SQSTM1 pathway regulates basal mitophagy, with SQSTM1 sensing superoxide-enriched mitochondria through its redox-sensitive cysteine residues, which mediate SQSTM1 oligomerization and mitophagy activation. We developed STOCK1N-57534, a small molecule that targets and promotes this SQSTM1 activation mechanism. Treatment with STOCK1N-57534 reactivates mitophagy downregulated in senescent and naturally aged donor-derived primary cells, improving cellular senescence(-like) phenotypes. Our findings highlight that basal mitophagy is protective against cellular senescence and aging, positioning its pharmacological reactivation as a promising anti-aging strategy.Abbreviation: IR: ionizing radiation; ROS: reactive oxygen species; SARs: selective autophagy receptors.

Keywords:  Aging; SQSTM1/p62; autophagy; mitochondria; mitophagy; senescence

DOI:  https://doi.org/10.1080/15548627.2024.2414461
Oral Oncol. 2024 Oct 17. pii: S1368-8375(24)00387-7. [Epub ahead of print]159 107069

Comprehensive functional evaluation of head and neck squamous cell carcinoma with BH3-profiling demonstrates apoptotic competency and therapeutic efficacy of BH3-mimetics.

Daniel Li, Andrea Lopez, Nitisha Shrivastava, Wesley Chan, Carlos Thomas, Robert Burk, Jeff Segall, Stelby Augustine, Gregory Rosenblatt, Vikas Mehta, Bradley A Schiff, Richard V Smith, Michael B Prystowsky, Nicolas F Schlecht, Chandan Guha, Evripidis Gavathiotis, Thomas J Ow.

  Evasion of apoptosis promotes tumor survival and contributes to resistance to cancer therapeutics in head and neck squamous cell carcinoma (HNSCC). Our recent work has demonstrated that HNSCC's highly express pro-survival anti-apoptotic proteins Bcl-xL and Mcl-1. Nevertheless, the mechanism of HNSCC to evade apoptosis is still not well understood. We used BH3 profiling, a functional assay which measures mitochondrial depolarization in response to the introduction of BH3 peptides, to evaluate apoptosis competency and dependency upon BCL-2 family anti-apoptotic proteins in a panel of immortalized and patient-derived HNSCC lines. We assessed response to BH3 mimetics including ABT-263 (navitoclax), an inhibitor of Bcl-2/Bcl-xL/Bcl-w, and S63845, an inhibitor of Mcl-1, both as single agents and in combination. We demonstrate that apoptosis signaling appears to be intact in the majority of HNSCC cells, and they are co-dependent upon Bcl-xL and Mcl-1 for survival. We found the combination to be highly synergistic in 2D culture and in 3D organoid models of HHNSCC. Given our findings that co-dependency on Bcl-xL and Mcl-1 is common, and co-inhibition of these molecules is synergistic for growth suppression in HNSCC cells, these results elucidate the therapeutic potential of BCL-xL and MCL-1 inhibition in HNSCC.

Keywords:  Apoptosis; BCL-XL; Head and neck squamous cell carcinoma; MCL-1; Navitoclax

DOI:  https://doi.org/10.1016/j.oraloncology.2024.107069
EMBO J. 2024 Oct 17.

Autophagy adaptors mediate Parkin-dependent mitophagy by forming sheet-like liquid condensates.

Zi Yang, Saori R Yoshii, Yuji Sakai, Jing Zhang, Haruka Chino, Roland L Knorr, Noboru Mizushima.

  During PINK1- and Parkin-mediated mitophagy, autophagy adaptors are recruited to damaged mitochondria to promote their selective degradation. Autophagy adaptors such as optineurin (OPTN) and NDP52 facilitate mitophagy by recruiting the autophagy-initiation machinery, and assisting engulfment of damaged mitochondria through binding to ubiquitinated mitochondrial proteins and autophagosomal ATG8 family proteins. Here, we demonstrate that OPTN and NDP52 form sheet-like phase-separated condensates with liquid-like properties on the surface of ubiquitinated mitochondria. The dynamic and liquid-like nature of OPTN condensates is important for mitophagy activity, because reducing the fluidity of OPTN-ubiquitin condensates suppresses the recruitment of ATG9 vesicles and impairs mitophagy. Based on these results, we propose a dynamic liquid-like, rather than a stoichiometric, model of autophagy adaptors to explain the interactions between autophagic membranes (i.e., ATG9 vesicles and isolation membranes) and mitochondrial membranes during Parkin-mediated mitophagy. This model underscores the importance of liquid-liquid phase separation in facilitating membrane-membrane contacts, likely through the generation of capillary forces.

Keywords:  Autophagy; Liquid–Liquid Phase Separation; Mitophagy; Optineurin; Wetting

DOI:  https://doi.org/10.1038/s44318-024-00272-5
Aging Cell. 2024 Sep;23(9): e14242

Single-cell mitochondrial sequencing reveals low-frequency mitochondrial mutations in naturally aging mice.

Fuyan Liu, Xiaolin Sun, Cai Wei, Liu Ji, Yali Song, Chenlu Yang, Yue Wang, Xin Liu, Daqing Wang, Jingmin Kang.

  Mitochondria play a crucial role in numerous biological processes; however, limited methods and research have focused on revealing mitochondrial heterogeneity at the single-cell level. In this study, we optimized the DNBelab C4 single-cell ATAC (assay for transposase-accessible chromatin) sequencing workflow for single-cell mitochondrial sequencing (C4_mtscATAC-seq). We validated the effectiveness of our C4_mtscATAC-seq protocol by sequencing the HEK-293T cell line with two biological replicates, successfully capturing both mitochondrial content (~68% of total sequencing data) and open chromatin status simultaneously. Subsequently, we applied C4_mtscATAC-seq to investigate two mouse tissues, spleen and bone marrow, obtained from two mice aged 2 months and two mice aged 23 months. Our findings revealed higher mitochondrial DNA (mtDNA) content in young tissues compared to more variable mitochondrial content in aged tissues, consistent with higher activity scores of nuclear genes associated with mitochondrial replication and transcription in young tissues. We detected a total of 22, 15, and 21 mtDNA mutations in the young spleen, aged spleen, and bone marrow, respectively, with most variant allele frequencies (VAF) below 1%. Moreover, we observed a higher number of mtDNA mutations with higher VAF in aged tissues compared to young tissues. Importantly, we identified three mtDNA variations (m.9821A>T, m.15219T>C, and m.15984C>T) with the highest VAF in both aged spleen and aged bone marrow. By comparing cells with and without these mtDNA variations, we analyzed differential open chromatin status to identify potential genes associated with these mtDNA variations, including transcription factors such as KLF15 and NRF1. Our study presents an alternative single-cell mitochondrial sequencing method and provides crude insights into age-related single-cell mitochondrial variations.

Keywords:  ATAC; aging; mitochondrial DNA (mtDNA); mitochondrial mutation; single cell sequencing

DOI:  https://doi.org/10.1111/acel.14242
bioRxiv. 2024 Oct 11. pii: 2024.10.10.617667. [Epub ahead of print]

Catabolism of extracellular glutathione supplies amino acids to support tumor growth.

Fabio Hecht, Marco Zocchi, Emily T Tuttle, Nathan P Ward, Bradley Smith, Yun Pyo Kang, Juliana Cazarin, Zamira G Soares, Mete Emir Ozgurses, Huiping Zhao, Colin Sheehan, Fatemeh Alimohammadi, Lila D Munger, Dhvani Trivedi, Gloria Asantewaa, Sara K Blick-Nitko, Jason J Zoeller, Ying Chen, Vasilis Vasiliou, Bradley M Turner, Alexander Muir, Jonathan L Coloff, Joshua Munger, Gina M DeNicola, Isaac S Harris.

Restricting amino acids from tumors is an emerging therapeutic strategy with significant promise. While typically considered an intracellular antioxidant with tumor-promoting capabilities, glutathione (GSH) is a tripeptide of cysteine, glutamate, and glycine that can be catabolized, yielding amino acids. The extent to which GSH-derived amino acids are essential to cancers is unclear. Here, we find that GSH catabolism promotes tumor growth. We show that depletion of intracellular GSH does not perturb tumor growth, and extracellular GSH is highly abundant in the tumor microenvironment, highlighting the potential importance of GSH outside of tumors. We find supplementation with GSH can rescue cancer cell survival and growth in cystine-deficient conditions, and this rescue is dependent on the catabolic activity of γ-glutamyltransferases (GGTs). Finally, pharmacologic targeting of GGTs' activity prevents the breakdown of circulating GSH, lowers tumor cysteine levels, and slows tumor growth. Our findings indicate a non-canonical role for GSH in supporting tumors by acting as a reservoir of amino acids. Depriving tumors of extracellular GSH or inhibiting its breakdown is potentially a therapeutically tractable approach for patients with cancer. Further, these findings change our view of GSH and how amino acids, including cysteine, are supplied to cells.

DOI: https://doi.org/10.1101/2024.10.10.617667
Mol Metab. 2024 Oct 15. pii: S2212-8778(24)00178-9. [Epub ahead of print] 102047

Distinct roles for the domains of the mitochondrial aspartate/glutamate carrier citrin in organellar localization and substrate transport.

Sotiria Tavoulari, Denis Lacabanne, Gonçalo C Pereira, Chancievan Thangaratnarajah, Martin S King, Jiuya He, Roy Chowdhury, Lisa Tilokani, Shane M Palmer, Julien Prudent, John E Walker, Edmund R S Kunji.

  OBJECTIVE: Citrin, the mitochondrial aspartate/glutamate carrier isoform 2, is structurally and mechanistically the most complex SLC25 family member, because it consists of three-domains and forms a homodimer. Each protomer has an N-terminal calcium-binding domain with EF-hands, followed by a substrate-transporting carrier domain and a C-terminal domain with an amphipathic helix. The absence or dysfunction of citrin leads to citrin deficiency, a highly prevalent pan-ethnic mitochondrial disease. Here, we aim to understand the role of different citrin domains and how they contribute to pathogenic mechanisms in citrin deficiency.METHODS: We have employed structural modelling and functional reconstitution of purified proteins in proteoliposomes to assess the transport activity and calcium regulation of wild-type citrin and pathogenic variants associated with citrin deficiency. We have also developed a double knock-out of citrin and aralar (AGC1), the two paralogs of the mitochondrial aspartate/glutamate carrier, in HAP1 cells to perform mitochondrial imaging and to investigate mitochondrial localisation.
RESULTS: Using 33 pathogenic variants of citrin we clarify determinants of sub-cellular localization and transport mechanism. We identify crucial elements of the carrier domain that are required for transport, including those involved in substrate binding, network formation and dynamics. We show that the N-terminal domain is not involved in calcium regulation of transport, as previously thought, but when mutated causes a mitochondrial import defect.
CONCLUSIONS: Our work introduces a new role for the N-terminal domain of citrin and demonstrates that dysfunction of the different domains contributes to distinct pathogenic mechanisms in citrin deficiency.

Keywords:  SLC25; calcium regulation; citrin deficiency; transport; urea cycle disorders

DOI:  https://doi.org/10.1016/j.molmet.2024.102047
Mol Cancer Ther. 2024 Oct 14.

Targeting NAD+ Metabolism Vulnerability in FH-Deficient Hereditary Leiomyomatosis and Renal Cell Carcinoma with the novel NAMPT Inhibitor OT-82.

Susana S Najera, Christopher J Ricketts, Laura S Schmidt, Julia I Medina, Keita Saito, Lilia Ileva, Jeffrey R Brender, Amy M James, Cody J Peer, Brad Gouker, Baktiar O Karim, Olga Chernova, Catherine Wells, Ming-Hui Wei, Youfeng Yang, Xiaohu Zhang, Carleen Klumpp-Thomas, Jameson Travers, Lu Chen, Kelli M Wilson, Sameer H Issaq, William D Figg, Simone Difilippantonio, Joseph D Kalen, Murali C Krishna, Craig J Thomas, Michele Ceribelli, Christine M Heske, Daniel R Crooks, Jordan L Meier.

Hereditary Leiomyomatosis and Renal Cell Cancer (HLRCC) is an inherited cancer syndrome caused by germline pathogenic variants in the fumarate hydratase (FH) gene. Affected individuals are at risk for developing cutaneous and uterine leiomyomas and aggressive FH-deficient renal cell carcinoma (RCC) with a papillary histology. Due to a disrupted TCA cycle, FH-deficient kidney cancers rely on aerobic glycolysis for energy production, potentially creating compensatory metabolic vulnerabilities. This study conducted a high-throughput drug screen in HLRCC cell lines, which identified a critical dependency on nicotinamide adenine dinucleotide (NAD), a redox cofactor produced by the biosynthetic enzyme nicotinamide phosphoribosyltransferase (NAMPT). Human HLRCC tumors and HLRCC-derived cell lines exhibited elevated NAMPT expression compared to controls. FH-deficient HLRCC cells, but not FH-restored HLRCC or normal kidney cells, were sensitive to NAMPT inhibition. HLRCC cell line viability was significantly decreased in both 2D and 3D in vitro cultures in response to the clinically relevant NAMPT inhibitor OT-82. NAMPT inhibition in vitro significantly decreased the total amount of NAD+, NADH, NADP, NADPH, and PAR levels and the effects of NAMPT inhibition could be rescued by the downstream NAD precursor nicotinamide mononucleotide, confirming the on-target activity of OT-82. Moreover, NAMPT inhibition by OT-82 in two HLRCC xenograft models resulted in severely reduced tumor growth. OT-82 treatment of HLRCC xenograft tumors in vivo inhibited glycolytic flux as demonstrated by reduced lactate/pyruvate ratio in hyperpolarized 13C-pyruvate magnetic resonance spectroscopic imaging experiments. Overall, our data define NAMPT inhibition as a potential therapeutic approach for FH-deficient HLRCC-associated renal cell carcinoma.

DOI: https://doi.org/10.1158/1535-7163.MCT-24-0225
Aging Biol. 2023 ;pii: 20230005. [Epub ahead of print]1(1):

Analysis of Somatic Mutations in Senescent Cells Using Single-Cell Whole-Genome Sequencing.

Lei Zhang, Marco De Cecco, Moonsook Lee, Xiaoxiao Hao, Alexander Y Maslov, Cristina Montagna, Judith Campisi, Xiao Dong, John M Sedivy, Jan Vijg.

Somatic mutations accumulate in multiple organs and tissues during aging and are a known cause of cancer. Cellular senescence is a possible cause of functional decline in aging, yet also acts as an anticancer mechanism in vivo. Here, we compared somatic mutation burden between early passage and deeply senescent human fibroblasts using single-cell whole-genome sequencing. The results show that single-nucleotide variants (SNVs) and small insertions and deletions (INDELs) are increased in senescent cells by about twofold but have the same mutational signature as early passage cells. The increase in SNVs and INDELs can be explained by increased replication errors due to the increased number of cell divisions senescent cells are likely to have undergone. By contrast, a stark increase of aneuploidies was observed in deeply senescent cells, with about half of all senescent cells affected but none of the early passage cells analyzed. These results indicate that large chromosomal events rather than small base substitutions or insertions and deletions could be mechanistically linked to cellular senescence.

DOI: https://doi.org/10.59368/agingbio.20230005
Nucleus. 2024 Dec;15(1): 2413501

Apoptosis-induced translocation of nesprin-2 from the nuclear envelope to mitochondria is associated with mitochondrial dysfunction.

Hila Zohar, Liora Lindenboim, Oren Gozlan, Gregg G Gundersen, Howard J Worman, Reuven Stein.

  Accumulating evidence suggests that the nuclear envelope (NE) is not just a target, but also a mediator of apoptosis. We showed recently that the NE protein nesprin-2 has pro-apoptotic activity, which involves its subcellular redistribution and Bcl-2 proteins. Here we further characterize the pro-apoptotic activity of nesprin-2 focusing on its redistribution. We assessed the redistribution kinetics of endogenous nesprin-2 tagged with GFP relative to apoptosis-associated mitochondrial dysfunction. The results show apoptosis-induced GFP-nesprin-2G redistribution occurred by two different modes - complete and partial, both lead to appearance of nesprin-2G near the mitochondria. Moreover, GFP-nesprin-2 redistribution is associated with reduction in mitochondrial membrane potential and mitochondrial outer membrane permeabilization and precedes the appearance of morphological features of apoptosis. Our results show that nesprin-2G redistribution and translocation near mitochondria is an early apoptotic effect associated with mitochondrial dysfunction, which may be responsible for the pro-apoptotic function of nesprin-2.

Keywords:  Apoptosis; LINC complex; mitochondria; nesprin-2; nuclear envelope; nucleus

DOI:  https://doi.org/10.1080/19491034.2024.2413501
bioRxiv. 2024 Oct 10. pii: 2024.10.10.617517. [Epub ahead of print]

Cardiolipin deficiency disrupts CoQ redox state and induces steatohepatitis.

Marisa J Brothwell, Guoshen Cao, J Alan Maschek, Annelise M Poss, Alek D Peterlin, Liping Wang, Talia B Baker, Justin L Shahtout, Piyarat Siripoksup, Quentinn J Pearce, Jordan M Johnson, Fabian M Finger, Alexandre Prola, Sarah A Pellizzari, Gillian L Hale, Allison M Manuel, Shinya Watanabe, Edwin R Miranda, Kajsa E Affolter, Trevor S Tippetts, Linda S Nikolova, Ran Hee Choi, Stephen T Decker, Mallikarjun Patil, J Leon Catrow, William L Holland, Sara M Nowinski, Daniel S Lark, Kelsey H Fisher-Wellman, Patrice N Mimche, Kimberley J Evason, James E Cox, Scott A Summers, Zach Gerhart-Hines, Katsuhiko Funai.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a progressive disorder marked by lipid accumulation, leading to steatohepatitis (MASH). A key feature of the transition to MASH involves oxidative stress resulting from defects in mitochondrial oxidative phosphorylation (OXPHOS). Here, we show that pathological alterations in the lipid composition of the inner mitochondrial membrane (IMM) directly instigate electron transfer inefficiency to promote oxidative stress. Specifically, cardiolipin (CL) was downregulated across four mouse models of MASLD. Hepatocyte-specific CL synthase knockout (CLS-LKO) led to spontaneous MASH with elevated mitochondrial electron leak. Loss of CL interfered with the ability of coenzyme Q (CoQ) to transfer electrons, promoting leak primarily at sites II F and III Q0 . Data from human liver biopsies revealed a highly robust correlation between mitochondrial CL and CoQ, co-downregulated with MASH. Thus, reduction in mitochondrial CL promotes oxidative stress and contributes to pathogenesis of MASH.

DOI: https://doi.org/10.1101/2024.10.10.617517
Int Rev Cell Mol Biol. 2024 ;pii: S1937-6448(24)00103-5. [Epub ahead of print]389 67-103

Tumor microenvironment induced switch to mitochondrial metabolism promotes suppressive functions in immune cells.

Sanjay Pandey, Vandana Anang, Michelle M Schumacher.

  Understanding the intricacies of the metabolic phenotype in immune cells and its plasticity within the tumor microenvironment is pivotal in understanding the pathology and prognosis of cancer. Unfavorable conditions and cellular stress in the tumor microenvironment (TME) exert a profound impact on cellular functions in immune cells, thereby influencing both tumor progression and immune responses. Elevated AMP:ATP ratio, a consequence of limited glucose levels, activate AMP-activated protein kinase (AMPK) while concurrently repressing the activity of mechanistic target of rapamycin (mTOR) and hypoxia-inducible factor 1-alpha (HIF-1α). The intricate balance between AMPK, mTOR, and HIF-1α activities defines the metabolic phenotype of immune cells in the TME. These Changes in metabolic phenotype are strongly associated with immune cell functions and play a crucial role in creating a milieu conducive to tumor progression. Insufficiency of nutrient and oxygen supply leads to a metabolic shift in immune cells characterized by a decrease in glycolysis and an increase in oxidative phosphorylation (OXPHOS) and fatty acid oxidation (FAO) rates. In most cases, this shift in metabolism is accompanied by a compromise in the effector functions of these immune cells. This metabolic adaptation prompts immune cells to turn down their effector functions, entering a quiescent or immunosuppressive state that may support tumor growth. This article discusses how tumor microenvironment alters the metabolism in immune cells leading to their tolerance and tumor progression, with emphasis on mitochondrial metabolism (OXPHOS and FAO).

Keywords:  AMPK; CAR-T; Fatty acid oxidation; Glycolysis; HIF1α; MTOR; Metabolism; Mitochondrial dynamics; Mitochondrial fission; Mitochondrial fusion; Mitochondrial metabolism; OXPHOS; T cell exhaustion; T cell metabolism

DOI:  https://doi.org/10.1016/bs.ircmb.2024.07.003
Stem Cell Rev Rep. 2024 Oct 18.

Mitochondria's Role in the Maintenance of Cancer Stem Cells in Hepatocellular Carcinoma.

Manar A Elhinnawi, Michael Ibrahim Boushra, Donia Mohamed Hussien, Fatema Hesham Hussein, Islam Ahmed Abdelmawgood.

  Hepatocellular carcinoma (HCC) is the predominant form of liver cancer and is recognized as a major contributor to cancer-related mortality worldwide. Cancer stem cells (CSCs) are a tiny group of cancer cells that possess a significant ability to regenerate themselves, form tumors, and undergo differentiation. CSCs have a pivotal role in the initiation, spread, recurrence, and resistance to treatment of cancer. As a result, they are very susceptible to being targeted for therapeutic intervention. The potential to cure HCC may be achieved by efficiently targeting drugs that eradicate cancer stem cells. Mitochondria have a crucial function in granting drug resistance to cancer stem cells by means of mitochondrial metabolism, biogenesis, and dynamics. Dysfunction in mitochondrial metabolic processes, such as mitochondrial oxidative phosphorylation (OXPHOS), calcium signaling, and reactive oxygen species (ROS) generation, contributes to the initiation and progression of human malignancies, including HCC. ROS have both beneficial and detrimental effects depending on their concentration. Consequently, ROS have become a prominent subject in the study of the fundamental mechanisms of HCC. Furthermore, an imbalance in the process of creating new mitochondria is a characteristic feature of CSCs, and an increase in mitochondrial biogenesis is associated with the heightened resistance observed in CSCs. This article provides a detailed examination of the involvement of mitochondria in the preservation of CSCs, as well as the spread of HCC. A deeper understanding of how mitochondria participate in tumorigenesis and drug resistance could result in the discovery of novel cancer treatments.

Keywords:  Cancer; Cancer stem cell; Hepatocellular carcinoma; Mitochondria; Mitophagy

DOI:  https://doi.org/10.1007/s12015-024-10797-1
Biochim Biophys Acta Proteins Proteom. 2024 Oct 10. pii: S1570-9639(24)00062-1. [Epub ahead of print] 141055

Ndufs4 knockout mice with isolated complex I deficiency engage a futile adaptive brain response.

Melissa A E van de Wal, Cenna Doornbos, Janne Bibbe, Judith R Homberg, Clara van Karnebeek, Martijn A Huynen, Jaap Keijer, Evert M van Schothorst, Peter A C 't Hoen, Mirian C H Janssen, Merel J W Adjobo-Hermans, Mariusz R Wieckowski, Werner J H Koopman.

  Paediatric Leigh syndrome (LS) is an early-onset and fatal neurodegenerative disorder lacking treatment options. LS is frequently caused by mutations in the NDUFS4 gene, encoding an accessory subunit of mitochondrial complex I (CI), the first complex of the oxidative phosphorylation (OXPHOS) system. Whole-body Ndufs4 knockout (KO) mice (WB-KO mice) are widely used to study isolated CI deficiency, LS pathology and interventions. These animals develop a brain-specific phenotype via an incompletely understood pathomechanism. Here we performed a quantitative analysis of the sub-brain proteome in six-weeks old WB-KO mice vs. wildtype mice. Brain regions comprised of a brain slice (BrSl), cerebellum (CB), cerebral cortex (CC), hippocampus (HC), inferior colliculus (IC), and superior colliculus (SC). Proteome analysis demonstrated similarities between CC/HC, and between IC/SC, whereas BrSl and CB differed from these two groups and each other. All brain regions displayed greatly reduced levels of two CI structural subunits (NDUFS4, NDUFA12) and an increased level of the CI assembly factor NDUFAF2. The level of CI-Q module subunits was significantly more reduced in IC/SC than in BrSl/CB/CC/HC, whereas other OXPHOS complex levels were not reduced. Gene ontology and pathway analysis demonstrated specific and common proteome changes between brain regions. Across brain regions, upregulation of cold-shock-associated proteins, mitochondrial fatty acid (FA) oxidation and synthesis (mtFAS) were the most prominent. FA-related pathways were predominantly upregulated in CB and HC. Based upon these results, we argue that stimulation of these pathways is futile and pro-pathological and discuss alternative strategies for therapeutic intervention in LS. SIGNIFICANCE: The Ndufs4 knockout mouse model is currently the most relevant and most widely used animal model to study the brain-linked pathophysiology of human Leigh Syndrome (LS) and intervention strategies. We demonstrate that the Ndufs4 knockout brain engages futile and pro-pathological responses. These responses explain both negative and positive outcomes of intervention studies in Leigh Syndrome mice and patients, thereby guiding novel intervention opportunities.

Keywords:  Brain; Fatty acids; Leigh syndrome; Pathomechanism; Proteomics

DOI:  https://doi.org/10.1016/j.bbapap.2024.141055
medRxiv. 2024 Oct 09. pii: 2024.10.09.24315165. [Epub ahead of print]

A whole food, plant-based diet reduces amino acid levels in patients with metastatic breast cancer.

TashJaé Q Scales, Bradley Smith, Lisa M Blanchard, Nellie Wixom, Emily T Tuttle, Brian J Altman, Luke J Peppone, Joshua Munger, Thomas M Campbell, Erin K Campbell, Isaac S Harris.

Amino acids are critical to tumor survival. Tumors can acquire amino acids from the surrounding microenvironment, including the serum. Limiting dietary amino acids is suggested to influence their serum levels. Further, a plant-based diet is reported to contain fewer amino acids than an animal-based diet. Here, we investigated the impact of a whole food, plant-based diet on lowering the serum levels of amino acids in patients with cancer. Patients with metastatic breast cancer (n=18) were enrolled in clinical trial NCT03045289 . An ad libitum whole food, plant-based diet was implemented for 8 weeks without calorie or portion restriction. We found that a whole food, plant-based diet resulted in a lower intake of calories, fat, and amino acids and higher levels of fiber. Additionally, body weight, serum insulin, and IGF-1 were reduced in participants. The diet contained lower levels of essential and non-essential amino acids. Importantly, the lowered dietary intake of amino acids translated to reduced serum levels of amino acids in participants (5/9 essential amino acids; 4/11 non-essential amino acids). These findings provide a tractable approach to limiting amino acid levels in cancer patients. This data lays a foundation for studying the relationship between amino acids in patients and tumor progression. Further, a whole-food, plant-based diet has the potential to synergize with cancer therapies that exploit metabolic vulnerabilities.

DOI: https://doi.org/10.1101/2024.10.09.24315165
Nat Rev Mol Cell Biol. 2024 Oct 17.

Molecular mechanisms of mitochondrial dynamics.

Luis-Carlos Tábara, Mayuko Segawa, Julien Prudent.

Mitochondria not only synthesize energy required for cellular functions but are also involved in numerous cellular pathways including apoptosis, calcium homoeostasis, inflammation and immunity. Mitochondria are dynamic organelles that undergo cycles of fission and fusion, and these transitions between fragmented and hyperfused networks ensure mitochondrial function, enabling adaptations to metabolic changes or cellular stress. Defects in mitochondrial morphology have been associated with numerous diseases, highlighting the importance of elucidating the molecular mechanisms regulating mitochondrial morphology. Here, we discuss recent structural insights into the assembly and mechanism of action of the core mitochondrial dynamics proteins, such as the dynamin-related protein 1 (DRP1) that controls division, and the mitofusins (MFN1 and MFN2) and optic atrophy 1 (OPA1) driving membrane fusion. Furthermore, we provide an updated view of the complex interplay between different proteins, lipids and organelles during the processes of mitochondrial membrane fusion and fission. Overall, we aim to present a valuable framework reflecting current perspectives on how mitochondrial membrane remodelling is regulated.

DOI: https://doi.org/10.1038/s41580-024-00785-1
Cell Mol Immunol. 2024 Oct 14.

Regulation of CD8+ T cells by lipid metabolism in cancer progression.

Yong Tang, Ziqing Chen, Qianying Zuo, Yibin Kang.

  Dysregulation of lipid metabolism is a key characteristic of the tumor microenvironment, where tumor cells utilize lipids for proliferation, survival, metastasis, and evasion of immune surveillance. Lipid metabolism has become a critical regulator of CD8+ T-cell-mediated antitumor immunity, with excess lipids in the tumor microenvironment impeding CD8+ T-cell activities. Considering the limited efficacy of immunotherapy in many solid tumors, targeting lipid metabolism to enhance CD8+ T-cell effector functions could significantly improve immunotherapy outcomes. In this review, we examine recent findings on how lipid metabolic processes, including lipid uptake, synthesis, and oxidation, regulate CD8+ T cells within tumors. We also assessed the impact of different lipids on CD8+ T-cell-mediated antitumor immunity, with a particular focus on how lipid metabolism affects mitochondrial function in tumor-infiltrating CD8+ T cells. Furthermore, as cancer is a systemic disease, we examined systemic factors linking lipid metabolism to CD8+ T-cell effector function. Finally, we summarize current therapeutic approaches that target lipid metabolism to increase antitumor immunity and enhance immunotherapy. Understanding the molecular and functional interplay between lipid metabolism and CD8+ T cells offers promising therapeutic opportunities for cancer treatment.

Keywords:  CD8+T cells; Immunotherapy; Lipid metabolism; Mitochondria; Oxidative phosphorylation

DOI:  https://doi.org/10.1038/s41423-024-01224-z
Nature. 2024 Oct 16.

Quantifying constraint in the human mitochondrial genome.

Nicole J Lake, Kaiyue Ma, Wei Liu, Stephanie L Battle, Kristen M Laricchia, Grace Tiao, Daniela Puiu, Kenneth K Ng, Justin Cohen, Alison G Compton, Shannon Cowie, John Christodoulou, David R Thorburn, Hongyu Zhao, Dan E Arking, Shamil R Sunyaev, Monkol Lek.

Mitochondrial DNA (mtDNA) has an important yet often overlooked role in health and disease. Constraint models quantify the removal of deleterious variation from the population by selection and represent powerful tools for identifying genetic variation that underlies human phenotypes1-4. However, nuclear constraint models are not applicable to mtDNA, owing to its distinct features. Here we describe the development of a mitochondrial genome constraint model and its application to the Genome Aggregation Database (gnomAD), a large-scale population dataset that reports mtDNA variation across 56,434 human participants5. Specifically, we analyse constraint by comparing the observed variation in gnomAD to that expected under neutrality, which was calculated using a mtDNA mutational model and observed maximum heteroplasmy-level data. Our results highlight strong depletion of expected variation, which suggests that many deleterious mtDNA variants remain undetected. To aid their discovery, we compute constraint metrics for every mitochondrial protein, tRNA and rRNA gene, which revealed a range of intolerance to variation. We further characterize the most constrained regions within genes through regional constraint and identify the most constrained sites within the entire mitochondrial genome through local constraint, which showed enrichment of pathogenic variation. Constraint also clustered in three-dimensional structures, which provided insight into functionally important domains and their disease relevance. Notably, we identify constraint at often overlooked sites, including in rRNA and noncoding regions. Last, we demonstrate that these metrics can improve the discovery of deleterious variation that underlies rare and common phenotypes.

DOI: https://doi.org/10.1038/s41586-024-08048-x
Cell Rep. 2024 Oct 15. pii: S2211-1247(24)01215-4. [Epub ahead of print]43(11): 114864

Defective ribosome assembly impairs leukemia progression in a murine model of acute myeloid leukemia.

Daniel Sjövall, Sudip Ghosh, Narcis Fernandez-Fuentes, Talia Velasco-Hernandez, Anna Hogmalm, Pablo Menendez, Jenny Hansson, Carolina Guibentif, Pekka Jaako.

  Despite an advanced understanding of disease mechanisms, the current therapeutic regimen fails to cure most patients with acute myeloid leukemia (AML). In the present study, we address the role of ribosome assembly in leukemia cell function. We apply patient datasets and murine models to demonstrate that immature leukemia cells in mixed-lineage leukemia-rearranged AML are characterized by relatively high ribosome biogenesis and protein synthesis rates. Using a model with inducible regulation of ribosomal subunit joining, we show that defective ribosome assembly extends survival in mice with AML. Single-cell RNA sequencing and proteomic analyses reveal that leukemia cell adaptation to defective ribosome assembly is associated with an increase in ribosome biogenesis and deregulation of the transcription factor landscape. Finally, we demonstrate that defective ribosome assembly shows antileukemia efficacy in p53-deficient AML. Our study unveils the critical requirement of a high protein synthesis rate for leukemia progression and highlights ribosome assembly as a therapeutic target in AML.

Keywords:  AML; CP: Cancer; MLL; eIF6; leukemia; leukemia stem cell; mRNA translation; protein synthesis; ribosome; scRNA-seq

DOI:  https://doi.org/10.1016/j.celrep.2024.114864
Cancer Drug Resist. 2024 ;7 38

Emerging roles of small extracellular vesicles in metabolic reprogramming and drug resistance in cancers.

Jingcun Shi, Ying Shen, Jianjun Zhang.

  Studies of carcinogenic metabolism have shown that cancer cells have significant metabolic adaptability and that their metabolic dynamics undergo extensive reprogramming, which is a fundamental feature of cancer. The Warburg effect describes the preference of cancer cells for glycolysis over oxidative phosphorylation (OXPHOS), even under aerobic conditions. However, metabolic reprogramming in cancer cells involves not only glycolysis but also changes in lipid and amino acid metabolism. The mechanisms of these metabolic shifts are critical for the discovery of novel cancer therapeutic targets. Despite advances in the field of oncology, chemotherapy resistance, including multidrug resistance, remains a challenge. Research has revealed a correlation between metabolic reprogramming and anticancer drug resistance, but the underlying complex mechanisms are not fully understood. In addition, small extracellular vesicles (sEVs) may play a role in expanding metabolic reprogramming and promoting the development of drug resistance by mediating intercellular communication. The aim of this review is to assess the metabolic reprogramming processes that intersect with resistance to anticancer therapy, with particular attention given to the changes in glycolysis, lipid metabolism, and amino acid metabolism that accompany this phenomenon. In addition, the role of sEVs in disseminating metabolic reprogramming and promoting the development of drug-resistant phenotypes will be critically evaluated.

Keywords:  Small extracellular vesicles; amino acid metabolism; drug resistance; glycolysis; lipid metabolism; metabolic reprogramming; neoplasms

DOI:  https://doi.org/10.20517/cdr.2024.81
bioRxiv. 2024 Oct 11. pii: 2024.10.10.617685. [Epub ahead of print]

Targetable treatment resistance in thyroid cancer with clonal hematopoiesis.

Vera Tiedje, Pablo Sánchez Vela, Julie L Yang, Brian R Untch, Laura Boucai, Aaron J Stonestrom, Alberto Bueno Costa, Sebastià Franch Expósito, Avi Srivastava, Marina Kerpelev, Jillian Greenberg, Mathew Wereski, Amanda Kulick, Kevin Chen, Tianyue Qin, Soo-Yeon Im, Aishwarya Krishnan, Anthony R Martinez Benitez, Raquel Pluvinet, Merve Sahin, Kamal Menghrajani, Gnana P Krishnamoorthy, Elisa de Stanchina, Ahmet Zehir, Rahul Satija, Jeffrey Knauf, Robert L Bowman, Manel Esteller, Sean Devlin, Michael F Berger, Richard P Koche, James A Fagin, Ross L Levine.

Anaplastic thyroid cancer (ATC) is a clinically aggressive malignancy with a dismal prognosis. Combined BRAF/MEK inhibition offers significant therapeutic benefit in patients with BRAF V600E -mutant ATCs. However, relapses are common and overall survival remains poor. Compared with differentiated thyroid cancer, a hallmark of ATCs is significant infiltration with myeloid cells, particularly macrophages. ATCs are most common in the aging population, which also has an increased incidence of TET2 -mutant clonal hematopoiesis (CH). CH-mutant macrophages have been shown to accelerate CH-associated pathophysiology including atherosclerosis. However, the clinical and mechanistic contribution of CH-mutant clones to solid tumour biology, prognosis and therapeutic response has not been elucidated. Here we show that TET2 -mutant CH is enriched in the tumour microenvironment of patients with solid tumours and associated with adverse prognosis in ATC patients. We find that Tet2 -mutant macrophages selectively infiltrate mouse Braf V600E -mutant ATC and that their overexpression of Tgfβ-family ligands mediates resistance to BRAF/MEK inhibition. Importantly, inhibition of Tgfβ signaling restores sensitivity to MAPK pathway inhibition, opening a path for synergistic strategies to improve outcomes of patients with ATCs and concurrent CH.

DOI: https://doi.org/10.1101/2024.10.10.617685