bims-mibica 2024-06-16 papers

bims-mibica

Biomed News

on Mitochondrial bioenergetics in cancer

Issue of 2024–06–16
thirty-one papers selected by
Kelsey Fisher-Wellman, East Carolina University

Electron transport chain inhibition increases cellular dependence on purine transport and salvage.
RESPIRATION DEFECTS LIMIT SERINE SYNTHESIS REQUIRED FOR LUNG CANCER GROWTH AND SURVIVAL.
MTFP1 controls mitochondrial fusion to regulate inner membrane quality control and maintain mtDNA levels.
The Bioenergetic Landscape of Cancer.
Molecular mechanism of the ischemia-induced regulatory switch in mammalian complex I.
About metformin and its action on the mitochondrial respiratory chain in prostate cancer.
Dry molten globule conformational state of CYP11A1 (SCC) regulates the first step of steroidogenesis in the mitochondrial matrix.
Aberrant ER-mitochondria communication is a common pathomechanism in mitochondrial disease.
Metabolic inflexibility promotes mitochondrial health during liver regeneration.
Nanobiopsy investigation of the subcellular mtDNA heteroplasmy in human tissues.
Serine Depletion Promotes Anti-Tumor Immunity by Activating Mitochondrial DNA-mediated cGAS-STING Signaling.
Malate dehydrogenase (MDH) in cancer: a promiscuous enzyme, a redox regulator, and a metabolic co-conspirator.
Thyroid hormone enhances efficacy of cisplatin in lung cancer patients via down-regulating GLUT1 expression and reversing the Warburg effect.
Understanding mitochondrial potassium channels: 33 years after discovery.
MYG1 drives glycolysis and colorectal cancer development through nuclear-mitochondrial collaboration.
The rate and nature of mitochondrial DNA mutations in human pedigrees.
High-Resolution Fluorespirometry to Assess Dynamic Changes in Mitochondrial Membrane Potential in Human Immune Cells.
Mitochondrial Calcium Signaling Regulates Branched-Chain Amino Acid Catabolism in Fibrolamellar Carcinoma.
The multi-kinase inhibitor CG-806 exerts anti-cancer activity against acute myeloid leukemia by co-targeting FLT3, BTK, and aurora kinases.
Functional implications of fumarate-induced cysteine succination.
Mitochondrial transfer from Adipose stem cells to breast cancer cells drives multi-drug resistance.
Alternative magnetic field exposure suppresses tumor growth via metabolic reprogramming.
Proteomic profiling reveals ACSS2 facilitating metabolic support in acute myeloid leukemia.
Combined activation of artificial and natural ion channels for disrupting mitochondrial ion homeostasis towards effective postoperative tumor recurrence and metastasis suppression.
SIRT7 promotes lung cancer progression by destabilizing the tumor suppressor ARF.
Venetoclax resistance leads to broad resistance to standard-of-care anti-MM agents, but not to immunotherapies.
Targeting metabolic reprogramming to overcome drug resistance in advanced bladder cancer: insights from gemcitabine- and cisplatin-resistant models.
Metabolic Signaling in Cancer.
Overview of BH3 mimetics in ovarian cancer.
CRISPR activation screens identify the SWI/SNF ATPases as suppressors of ferroptosis.
The mitochondrial calcium uniporter: Balancing tumourigenic and anti-tumourigenic responses.

Cell Metab. 2024 Jun 07. pii: S1550-4131(24)00190-6. [Epub ahead of print]

Electron transport chain inhibition increases cellular dependence on purine transport and salvage.

Zheng Wu, Divya Bezwada, Feng Cai, Robert C Harris, Bookyung Ko, Varun Sondhi, Chunxiao Pan, Hieu S Vu, Phong T Nguyen, Brandon Faubert, Ling Cai, Hongli Chen, Misty Martin-Sandoval, Duyen Do, Wen Gu, Yuanyuan Zhang, Yuannyu Zhang, Bailey Brooks, Sherwin Kelekar, Lauren G Zacharias, K Celeste Oaxaca, Joao S Patricio, Thomas P Mathews, Javier Garcia-Bermudez, Min Ni, Ralph J DeBerardinis.

  Mitochondria house many metabolic pathways required for homeostasis and growth. To explore how human cells respond to mitochondrial dysfunction, we performed metabolomics in fibroblasts from patients with various mitochondrial disorders and cancer cells with electron transport chain (ETC) blockade. These analyses revealed extensive perturbations in purine metabolism, and stable isotope tracing demonstrated that ETC defects suppress de novo purine synthesis while enhancing purine salvage. In human lung cancer, tumors with markers of low oxidative mitochondrial metabolism exhibit enhanced expression of the salvage enzyme hypoxanthine phosphoribosyl transferase 1 (HPRT1) and high levels of the HPRT1 product inosine monophosphate. Mechanistically, ETC blockade activates the pentose phosphate pathway, providing phosphoribosyl diphosphate to drive purine salvage supplied by uptake of extracellular bases. Blocking HPRT1 sensitizes cancer cells to ETC inhibition. These findings demonstrate how cells remodel purine metabolism upon ETC blockade and uncover a new metabolic vulnerability in tumors with low respiration.

Keywords:  HPRT1; NAD(+):NADH ratio; electron transport chain; metabolomics; purine metabolism; stable isotopes

DOI:  https://doi.org/10.1016/j.cmet.2024.05.014
bioRxiv. 2024 Jun 02. pii: 2024.05.28.596339. [Epub ahead of print]

RESPIRATION DEFECTS LIMIT SERINE SYNTHESIS REQUIRED FOR LUNG CANCER GROWTH AND SURVIVAL.

Eduardo Cararo Lopes, Fuqian Shi, Akshada Sawant, Maria Ibrahim, Maria Gomez-Jenkins, Zhixian Hu, Pranav Manchiraju, Vrushank Bhatt, Wenping Wang, Christian S Hinrichs, Douglas C Wallace, Xiaoyang Su, Joshua D Rabinowitz, Chang S Chan, Jessie Yanxiang Guo, Shridar Ganesan, Edmund C Lattime, Eileen White.

Mitochondrial function is important for both energetic and anabolic metabolism. Pathogenic mitochondrial DNA (mtDNA) mutations directly impact these functions, resulting in the detrimental consequences seen in human mitochondrial diseases. The role of pathogenic mtDNA mutations in human cancers is less clear; while pathogenic mtDNA mutations are observed in some cancer types, they are almost absent in others. We report here that the proofreading mutant DNA polymerase gamma ( PolG D256A ) induced a high mtDNA mutation burden in non-small-cell lung cancer (NSCLC), and promoted the accumulation of defective mitochondria, which is responsible for decreased tumor cell proliferation and viability and increased cancer survival. In NSCLC cells, pathogenic mtDNA mutations increased glycolysis and caused dependence on glucose. The glucose dependency sustained mitochondrial energetics but at the cost of a decreased NAD+/NADH ratio that inhibited de novo serine synthesis. Insufficient serine synthesis, in turn, impaired the downstream synthesis of GSH and nucleotides, leading to impaired tumor growth that increased cancer survival. Unlike tumors with intact mitochondrial function, NSCLC with pathogenic mtDNA mutations were sensitive to dietary serine and glycine deprivation. Thus, mitochondrial function in NSCLC is required specifically to sustain sufficient serine synthesis for nucleotide production and redox homeostasis to support tumor growth, explaining why these cancers preserve functional mtDNA.
In brief: High mtDNA mutation burden in non-small-cell lung cancer (NSCLC) leads to the accumulation of respiration-defective mitochondria and dependency on glucose and glycolytic metabolism. Defective respiratory metabolism causes a massive accumulation of cytosolic nicotinamide adenine dinucleotide + hydrogen (NADH), which impedes serine synthesis and, thereby, glutathione (GSH) and nucleotide synthesis, leading to impaired tumor growth and increased survival.
Highlights: Proofreading mutations in Polymerase gamma led to a high burden of mitochondrial DNA mutations, promoting the accumulation of mitochondria with respiratory defects in NSCLC.Defective respiration led to reduced proliferation and viability of NSCLC cells increasing survival to cancer.Defective respiration caused glucose dependency to fuel elevated glycolysis.Altered glucose metabolism is associated with high NADH that limits serine synthesis, leading to impaired GSH and nucleotide production.Mitochondrial respiration defects sensitize NSCLC to dietary serine/glycine starvation, further increasing survival.
Abstract Figure:

DOI: https://doi.org/10.1101/2024.05.28.596339
Cell. 2024 Jun 05. pii: S0092-8674(24)00526-9. [Epub ahead of print]

MTFP1 controls mitochondrial fusion to regulate inner membrane quality control and maintain mtDNA levels.

Luis Carlos Tábara, Stephen P Burr, Michele Frison, Suvagata R Chowdhury, Vincent Paupe, Yu Nie, Mark Johnson, Jara Villar-Azpillaga, Filipa Viegas, Mayuko Segawa, Hanish Anand, Kasparas Petkevicius, Patrick F Chinnery, Julien Prudent.

  Mitochondrial dynamics play a critical role in cell fate decisions and in controlling mtDNA levels and distribution. However, the molecular mechanisms linking mitochondrial membrane remodeling and quality control to mtDNA copy number (CN) regulation remain elusive. Here, we demonstrate that the inner mitochondrial membrane (IMM) protein mitochondrial fission process 1 (MTFP1) negatively regulates IMM fusion. Moreover, manipulation of mitochondrial fusion through the regulation of MTFP1 levels results in mtDNA CN modulation. Mechanistically, we found that MTFP1 inhibits mitochondrial fusion to isolate and exclude damaged IMM subdomains from the rest of the network. Subsequently, peripheral fission ensures their segregation into small MTFP1-enriched mitochondria (SMEM) that are targeted for degradation in an autophagic-dependent manner. Remarkably, MTFP1-dependent IMM quality control is essential for basal nucleoid recycling and therefore to maintain adequate mtDNA levels within the cell.

Keywords:  IMM quality control; IMM remodeling; MTFP1; autophagy; fission and fusion; mitochondria; mitochondrial dynamics; mitophagy; mtDNA

DOI:  https://doi.org/10.1016/j.cell.2024.05.017
Mol Metab. 2024 Jun 12. pii: S2212-8778(24)00097-8. [Epub ahead of print] 101966

The Bioenergetic Landscape of Cancer.

Elizabeth R M Zunica, Christopher L Axelrod, L Anne Gilmore, Erich Gnaiger, John P Kirwan.

  Bioenergetic remodeling of core energy metabolism is essential to the initiation, survival, and progression of cancer cells through exergonic supply of adenosine triphosphate (ATP) and metabolic intermediates, as well as control of redox homeostasis. Mitochondria are evolutionarily conserved organelles that mediate cell survival by conferring energetic plasticity and adaptive potential. Mitochondrial ATP synthesis is coupled to the oxidation of a variety of substrates generated through diverse metabolic pathways. As such, inhibition of the mitochondrial bioenergetic system by restricting metabolite availability, direct inhibition of the respiratory Complexes, altering organelle structure, or coupling efficiency may restrict carcinogenic potential and cancer progression. Here, we review the role of bioenergetics as the principal conductor of energetic functions and carcinogenesis while highlighting the therapeutic potential of targeting mitochondrial functions.

Keywords:  Bioenergetics; Cancer; Cell Survival; Energy Transformation; Mitochondria

DOI:  https://doi.org/10.1016/j.molmet.2024.101966
Science. 2024 Jun 14. 384(6701): 1247-1253

Molecular mechanism of the ischemia-induced regulatory switch in mammalian complex I.

Daniel N Grba, John J Wright, Zhan Yin, William Fisher, Judy Hirst.

Respiratory complex I is an efficient driver for oxidative phosphorylation in mammalian mitochondria, but its uncontrolled catalysis under challenging conditions leads to oxidative stress and cellular damage. Ischemic conditions switch complex I from rapid, reversible catalysis into a dormant state that protects upon reoxygenation, but the molecular basis for the switch is unknown. We combined precise biochemical definition of complex I catalysis with high-resolution cryo-electron microscopy structures in the phospholipid bilayer of coupled vesicles to reveal the mechanism of the transition into the dormant state, modulated by membrane interactions. By implementing a versatile membrane system to unite structure and function, attributing catalytic and regulatory properties to specific structural states, we define how a conformational switch in complex I controls its physiological roles.

DOI: https://doi.org/10.1126/science.ado2075
Transl Androl Urol. 2024 May 31. 13(5): 909-914

About metformin and its action on the mitochondrial respiratory chain in prostate cancer.

Bernard Gallez, Barbara Mathieu, Pierre Sonveaux.



Keywords:  Mitochondria; cancer metabolism; electron transport chain (ETC); metformin; reactive oxygen species (ROS)

DOI:  https://doi.org/10.21037/tau-23-602
iScience. 2024 Jun 21. 27(6): 110039

Dry molten globule conformational state of CYP11A1 (SCC) regulates the first step of steroidogenesis in the mitochondrial matrix.

Himangshu S Bose.

  Multiple metabolic events occur in mitochondria. Mitochondrial protein translocation from the cytoplasm across compartments depends on the amino acid sequence within the precursor. At the mitochondria associated-ER membrane, misfolding of a mitochondrial targeted protein prior to import ablates metabolism. CYP11A1, cytochrome P450 cholesterol side chain cleavage enzyme (SCC), is imported from the cytoplasm to mitochondrial matrix catalyzing cholesterol to pregnenolone, an essential step for metabolic processes and mammalian survival. Multiple steps regulate the availability of an actively folded SCC; however, the mechanism is unknown. We identified that a dry molten globule state of SCC exists in the matrix by capturing intermediate protein folding steps dictated by its C-terminus. The intermediate dry molten globule state in the mitochondrial matrix of living cells is stable with a limited network of interaction and is inactive. The dry molten globule is activated with hydrogen ions availability, triggering cleavage of cholesterol sidechain, and initiating steroidogenesis.

Keywords:  functional aspects of cell biology; properties of biomolecules; protein folding

DOI:  https://doi.org/10.1016/j.isci.2024.110039
Cell Death Dis. 2024 Jun 10. 15(6): 405

Aberrant ER-mitochondria communication is a common pathomechanism in mitochondrial disease.

Patricia Morcillo, Khushbu Kabra, Kevin Velasco, Hector Cordero, Sarah Jennings, Taekyung D Yun, Delfina Larrea, H Orhan Akman, Eric A Schon.

Genetic mutations causing primary mitochondrial disease (i.e those compromising oxidative phosphorylation [OxPhos]) resulting in reduced bioenergetic output display great variability in their clinical features, but the reason for this is unknown. We hypothesized that disruption of the communication between endoplasmic reticulum (ER) and mitochondria at mitochondria-associated ER membranes (MAM) might play a role in this variability. To test this, we assayed MAM function and ER-mitochondrial communication in OxPhos-deficient cells, including cybrids from patients with selected pathogenic mtDNA mutations. Our results show that each of the various mutations studied indeed altered MAM functions, but notably, each disorder presented with a different MAM "signature". We also found that mitochondrial membrane potential is a key driver of ER-mitochondrial connectivity. Moreover, our findings demonstrate that disruption in ER-mitochondrial communication has consequences for cell survivability that go well beyond that of reduced ATP output. The findings of a "MAM-OxPhos" axis, the role of mitochondrial membrane potential in controlling this process, and the contribution of MAM dysfunction to cell death, reveal a new relationship between mitochondria and the rest of the cell, as well as providing new insights into the diagnosis and treatment of these devastating disorders.

DOI: https://doi.org/10.1038/s41419-024-06781-9
Science. 2024 Jun 14. 384(6701): eadj4301

Metabolic inflexibility promotes mitochondrial health during liver regeneration.

Xun Wang, Cameron J Menezes, Yuemeng Jia, Yi Xiao, Siva Sai Krishna Venigalla, Feng Cai, Meng-Hsiung Hsieh, Wen Gu, Liming Du, Jessica Sudderth, Dohun Kim, Spencer D Shelton, Claire B Llamas, Yu-Hsuan Lin, Min Zhu, Salma Merchant, Divya Bezwada, Sherwin Kelekar, Lauren G Zacharias, Thomas P Mathews, Gerta Hoxhaj, R Max Wynn, Uttam K Tambar, Ralph J DeBerardinis, Hao Zhu, Prashant Mishra.

Mitochondria are critical for proper organ function and mechanisms to promote mitochondrial health during regeneration would benefit tissue homeostasis. We report that during liver regeneration, proliferation is suppressed in electron transport chain (ETC)-dysfunctional hepatocytes due to an inability to generate acetyl-CoA from peripheral fatty acids through mitochondrial β-oxidation. Alternative modes for acetyl-CoA production from pyruvate or acetate are suppressed in the setting of ETC dysfunction. This metabolic inflexibility forces a dependence on ETC-functional mitochondria and restoring acetyl-CoA production from pyruvate is sufficient to allow ETC-dysfunctional hepatocytes to proliferate. We propose that metabolic inflexibility within hepatocytes can be advantageous by limiting the expansion of ETC-dysfunctional cells.

DOI: https://doi.org/10.1126/science.adj4301
Sci Rep. 2024 Jun 14. 14(1): 13789

Nanobiopsy investigation of the subcellular mtDNA heteroplasmy in human tissues.

Alexander Bury, Angela Pyle, Amy E Vincent, Paolo Actis, Gavin Hudson.

Mitochondrial function is critical to continued cellular vitality and is an important contributor to a growing number of human diseases. Mitochondrial dysfunction is typically heterogeneous, mediated through the clonal expansion of mitochondrial DNA (mtDNA) variants in a subset of cells in a given tissue. To date, our understanding of the dynamics of clonal expansion of mtDNA variants has been technically limited to the single cell-level. Here, we report the use of nanobiopsy for subcellular sampling from human tissues, combined with next-generation sequencing to assess subcellular mtDNA mutation load in human tissue from mitochondrial disease patients. The ability to map mitochondrial mutation loads within individual cells of diseased tissue samples will further our understanding of mitochondrial genetic diseases.

DOI: https://doi.org/10.1038/s41598-024-64455-0
Cancer Res. 2024 Jun 11.

Serine Depletion Promotes Anti-Tumor Immunity by Activating Mitochondrial DNA-mediated cGAS-STING Signaling.

Suchandrima Saha, Monisankar Ghosh, Jinyu Li, Asher Wen, Lorenzo Galluzzi, Luis A Martinez, David C Montrose.

Serine is critical for supporting cancer metabolism, and depriving malignant cells of this non-essential amino acid exerts anti-neoplastic effects, in large part, through disrupting metabolic pathways. Given the intricate relationship between cancer metabolism and the immune system, the metabolic defects imposed by serine deprivation might impact tumor-targeting immunity. Here, we demonstrated that restricting endogenous and exogenous sources of serine in colorectal cancer (CRC) cells results in mitochondrial dysfunction, leading to mitochondrial DNA (mtDNA) accumulation in the cytosol and consequent cGAS-STING1-driven type I interferon (IFN) secretion. Depleting mtDNA or blocking its release attenuated cGAS-STING1 activation during serine deprivation. In vivo studies revealed that serine deprivation limits tumor growth, accompanied by enhanced type I IFN signaling and intratumoral infiltration of immune effector cells. Notably, the tumor-suppressive and immune-enhancing effects of serine restriction were impaired by T cell depletion and IFN receptor blockade. Moreover, disrupting cGAS-STING1 signaling in CRC cells limited the immunostimulatory and tumor-suppressive effects of serine deprivation. Lastly, serine depletion increased the sensitivity of tumors to an immune checkpoint inhibitor targeting PD-1. Taken together, these findings reveal a role for serine as a suppressor of anti-tumor immunity, suggesting that serine deprivation may be employed to enhance tumor immunogenicity and improve responsiveness to immune checkpoint inhibitors.

DOI: https://doi.org/10.1158/0008-5472.CAN-23-1788
Essays Biochem. 2024 Jun 12. pii: EBC20230088. [Epub ahead of print]

Malate dehydrogenase (MDH) in cancer: a promiscuous enzyme, a redox regulator, and a metabolic co-conspirator.

Betsy Leverett, Shane Austin, Jason Tan-Arroyo.

  Malate dehydrogenase (MDH) is an essential enzyme in the tricarboxylic acid cycle that functions in cellular respiration and redox homeostasis. Recent studies indicate that MDH facilitates metabolic plasticity in tumor cells, catalyzing the formation of an oncometabolite, contributing to altered epigenetics, and maintaining redox capacity to support the rewired energy metabolism and biosynthesis that enables cancer progression. This minireview summarizes current findings on the unique supporting roles played by MDH in human cancers and provides an update on targeting MDH in cancer chemotherapy.

Keywords:  cancer; malate dehydrogenase; metabolomics; oncometabolism; redox balance

DOI:  https://doi.org/10.1042/EBC20230088
Mitochondrion. 2024 Jun 12. pii: S1567-7249(24)00077-1. [Epub ahead of print] 101919

Thyroid hormone enhances efficacy of cisplatin in lung cancer patients via down-regulating GLUT1 expression and reversing the Warburg effect.

Chenchen Fan, Yanbei Ren, Wen Zhang, Jing Wen, Wenjia Zhang, Shumeng Lin, Yidong Bai, Tiansheng Zheng, Baigenzhin Abay, Ming Li, Lihong Fan.

  Cisplatin (CDDP) is a standard non-small cell lung cancer (NSCLC) chemotherapy, but its efficacy is hampered by resistance, partly due to the Warburg effect. This study investigates how thyroid hormones enhance the Warburg effect, increasing sensitivity to cisplatin in lung cancer. Clinical data from advanced NSCLC patients were analyzed based on thyroid hormone levels, categorizing patients into high and low groups. Cellular experiments involved Control, 10uM CDDP, 10uM CDDP + 0.1uM T3, and 10uM CDDP + 0.1uM T4 categories. Parameters were measured in A549 and PC9 lung cancer cells, including proliferation, apoptosis, mitochondrial membrane potential, ROS production, glycolysis enzyme activity, lactic acid level, and ATP content. Gene and protein expressions were assessed using qPCR and Western Blot. Analysis revealed higher FT3 levels correlated with prolonged progression-free survival before chemotherapy (median PFS: high FT3 group = 12.67 months, low FT3 group = 7.03 months, p = 0.01). Cellular experiments demonstrated that thyroid hormones increase lung cancer cell sensitivity to cisplatin, inhibiting proliferation and enhancing efficacy. The mechanism involves thyroid hormones and cisplatin jointly down-regulating MSI1/AKT/GLUT1 expression, reducing lactic acid and glycolysis. This Warburg effect reversal boosts ATP levels, elevates ROS, and decreases MMP, enhancing cisplatin effectiveness in A549 and PC9 cells. In conclusion, elevated free T3 levels in advanced NSCLC patients correlate with prolonged progression-free survival under cisplatin chemotherapy. Cellular experiments reveal that thyroid hormones enhance lung cancer cell sensitivity to cisplatin by reversing the Warburg effect, providing a mechanistic basis for improved therapeutic outcomes.

Keywords:  Cisplatin; Lung cancer; Mitochondria; Thyroid hormones; Tumor metabolism; Warburg effect

DOI:  https://doi.org/10.1016/j.mito.2024.101919
Acta Biochim Pol. 2024 ;71 13126

Understanding mitochondrial potassium channels: 33 years after discovery.

Adam Szewczyk.

  Mitochondrial investigations have extended beyond their traditional functions, covering areas such as ATP synthesis and metabolism. Mitochondria are now implicated in new functional areas such as cytoprotection, cellular senescence, tumor function and inflammation. The basis of these new areas still relies on fundamental biochemical/biophysical mitochondrial functions such as synthesis of reactive oxygen species, mitochondrial membrane potential, and the integrity of the inner mitochondrial membrane i.e., the passage of various molecules through the mitochondrial membranes. In this view transport of potassium cations, known as the potassium cycle, plays an important role. It is believed that K+ influx is mediated by various potassium channels present in the inner mitochondrial membrane. In this article, we present an overview of the key findings and characteristics of mitochondrial potassium channels derived from research of many groups conducted over the past 33 years. We propose a list of six fundamental observations and most important ideas dealing with mitochondrial potassium channels. We also discuss the contemporary challenges and future prospects associated with research on mitochondrial potassium channels.

Keywords:  cytoprotection; mitochondria; potassium channel openers; potassium channels; reactive oxygen species

DOI:  https://doi.org/10.3389/abp.2024.13126
Nat Commun. 2024 Jun 11. 15(1): 4969

MYG1 drives glycolysis and colorectal cancer development through nuclear-mitochondrial collaboration.

Jianxiong Chen, Shiyu Duan, Yulu Wang, Yuping Ling, Xiaotao Hou, Sijing Zhang, Xunhua Liu, Xiaoli Long, Jiawen Lan, Miao Zhou, Huimeng Xu, Haoxuan Zheng, Jun Zhou.

Metabolic remodeling is a strategy for tumor survival under stress. However, the molecular mechanisms during the metabolic remodeling of colorectal cancer (CRC) remain unclear. Melanocyte proliferating gene 1 (MYG1) is a 3'-5' RNA exonuclease and plays a key role in mitochondrial functions. Here, we uncover that MYG1 expression is upregulated in CRC progression and highly expressed MYG1 promotes glycolysis and CRC progression independent of its exonuclease activity. Mechanistically, nuclear MYG1 recruits HSP90/GSK3β complex to promote PKM2 phosphorylation, increasing its stability. PKM2 transcriptionally activates MYC and promotes MYC-medicated glycolysis. Conversely, c-Myc also transcriptionally upregulates MYG1, driving the progression of CRC. Meanwhile, mitochondrial MYG1 on the one hand inhibits oxidative phosphorylation (OXPHOS), and on the other hand blocks the release of Cyt c from mitochondria and inhibits cell apoptosis. Clinically, patients with KRAS mutation show high expression of MYG1, indicating a high level of glycolysis and a poor prognosis. Targeting MYG1 may disturb metabolic balance of CRC and serve as a potential target for the diagnosis and treatment of CRC.

DOI: https://doi.org/10.1038/s41467-024-49221-0
Cell. 2024 Jun 03. pii: S0092-8674(24)00531-2. [Epub ahead of print]

The rate and nature of mitochondrial DNA mutations in human pedigrees.

Erla R Árnadóttir, Kristján H S Moore, Valdís B Guðmundsdóttir, S Sunna Ebenesersdóttir, Kamran Guity, Hákon Jónsson, Kári Stefánsson, Agnar Helgason.

  We examined the rate and nature of mitochondrial DNA (mtDNA) mutations in humans using sequence data from 64,806 contemporary Icelanders from 2,548 matrilines. Based on 116,663 mother-child transmissions, 8,199 mutations were detected, providing robust rate estimates by nucleotide type, functional impact, position, and different alleles at the same position. We thoroughly document the true extent of hypermutability in mtDNA, mainly affecting the control region but also some coding-region variants. The results reveal the impact of negative selection on viable deleterious mutations, including rapidly mutating disease-associated 3243A>G and 1555A>G and pre-natal selection that most likely occurs during the development of oocytes. Finally, we show that the fate of new mutations is determined by a drastic germline bottleneck, amounting to an average of 3 mtDNA units effectively transmitted from mother to child.

Keywords:  germline bottleneck; germline selection; hypermutability; mitochondria; mitochondrial bottleneck; mtDNA; mutation rate; negative selection; pathogenic mutations; pedigrees

DOI:  https://doi.org/10.1016/j.cell.2024.05.022
J Vis Exp. 2024 May 24.

High-Resolution Fluorespirometry to Assess Dynamic Changes in Mitochondrial Membrane Potential in Human Immune Cells.

Ana P Valencia, Gavin Pharaoh, Arthur F Brandao, David J Marcinek.

Peripheral mononuclear cells (PBMCs) exhibit robust changes in mitochondrial respiratory capacity in response to health and disease. While these changes do not always reflect what occurs in other tissues, such as skeletal muscle, these cells are an accessible and valuable source of viable mitochondria from human subjects. PBMCs are exposed to systemic signals that impact their bioenergetic state. Thus, expanding our tools to interrogate mitochondrial metabolism in this population will elucidate mechanisms related to disease progression. Functional assays of mitochondria are often limited to using respiratory outputs following maximal substrate, inhibitor, and uncoupler concentrations to determine the full range of respiratory capacity, which may not be achievable in vivo. The conversion of adenosine diphosphate (ADP) to adenosine triphosphate (ATP) by ATP-synthase results in a decrease in mitochondrial membrane potential (mMP) and an increase in oxygen consumption. To provide a more integrated analysis of mitochondrial dynamics, this article describes the use of high-resolution fluorespirometry to measure the simultaneous response of oxygen consumption and mitochondrial membrane potential (mMP) to physiologically relevant concentrations of ADP. This technique uses tetramethylrhodamine methylester (TMRM) to measure mMP polarization in response to ADP titrations following maximal hyperpolarization with complex I and II substrates. This technique can be used to quantify how changes in health status, such as aging and metabolic disease, affect the sensitivity of mitochondrial response to energy demand in PBMCs, T-cells, and monocytes from human subjects.

DOI: https://doi.org/10.3791/66863
bioRxiv. 2024 May 28. pii: 2024.05.27.596106. [Epub ahead of print]

Mitochondrial Calcium Signaling Regulates Branched-Chain Amino Acid Catabolism in Fibrolamellar Carcinoma.

Nicole M Marsh, Melissa J S MacEwen, Jane Chea, Heidi L Kenerson, Albert A Kwong, Timothy M Locke, Francisco Javier Miralles, Tanmay Sapre, Natasha Gozali, G Ekin Atilla-Gokcumen, Shao-En Ong, John D Scott, Raymond S Yeung, Yasemin Sancak.

Metabolic adaptations in response to changes in energy supply and demand are essential for survival. The mitochondrial calcium uniporter coordinates metabolic homeostasis by regulating TCA cycle activation, mitochondrial fatty acid oxidation and cellular calcium signaling. However, a comprehensive analysis of uniporter-regulated mitochondrial metabolic pathways has remained unexplored. Here, we investigate the metabolic consequences of uniporter loss- and gain-of-function, and identify a key transcriptional regulator that mediates these effects. Using gene expression profiling and proteomic, we find that loss of uniporter function increases the expression of proteins in the branched-chain amino acid (BCAA) catabolism pathway. Activity is further augmented through phosphorylation of the enzyme that catalyzes this pathway's committed step. Conversely, in the liver cancer fibrolamellar carcinoma (FLC)-which we demonstrate to have high mitochondrial calcium levels- expression of BCAA catabolism enzymes is suppressed. We also observe uniporter-dependent suppression of the transcription factor KLF15, a master regulator of liver metabolic gene expression, including those involved in BCAA catabolism. Notably, loss of uniporter activity upregulates KLF15, along with its transcriptional target ornithine transcarbamylase (OTC), a component of the urea cycle, suggesting that uniporter hyperactivation may contribute to the hyperammonemia observed in FLC patients. Collectively, we establish that FLC has increased mitochondrial calcium levels, and identify an important role for mitochondrial calcium signaling in metabolic adaptation through the transcriptional regulation of metabolism.

DOI: https://doi.org/10.1101/2024.05.27.596106
Leuk Lymphoma. 2024 Jun 13. 1-16

The multi-kinase inhibitor CG-806 exerts anti-cancer activity against acute myeloid leukemia by co-targeting FLT3, BTK, and aurora kinases.

Guopan Yu, Weiguo Zhang, Mahesh Basyal, Yuki Nishida, Hideaki Mizumo, Charlie Ly, Hongying Zhang, William G Rice, Michael Andreeff.

  Despite the development of several Fms-like tyrosine kinase 3 (FLT3) inhibitors that have improved outcomes in patients with FLT3-mutant acute myeloid leukemia (AML), drug resistance is frequently observed, which may be associated with the activation of additional pro-survival pathways, such as those regulated by BTK, aurora kinases (AuroK), and potentially others, in addition to acquired tyrosine kinase domain (TKD) mutations of FLT3 gene. FLT3 may not always be a driver mutation. We evaluated the anti-leukemia efficacy of the novel multi-kinase inhibitor CG-806, which targets FLT3 and other kinases, to circumvent drug resistance and target FLT3 wild-type (WT) cells. The anti-leukemia activity of CG-806 was investigated by measuring apoptosis induction and analyzing the cell cycle using flow cytometry in vitro. CG-806 demonstrated superior anti-leukemia efficacy compared to commercially available FLT3 inhibitors, both in vitro and in vivo, regardless of FLT3 mutational status. The mechanism of action of CG-806 may involve its broad inhibitory profile against FLT3, BTK, and AuroK. In FLT3 mutant cells, CG-806 induced G1 phase blockage, whereas in FLT3 WT cells, it resulted in G2/M phase arrest. Targeting FLT3 and Bcl-2 and/or Mcl-1 simultaneously results in a synergistic pro-apoptotic effect in FLT3 mutant leukemia cells. The results of this study suggest that CG-806 is a promising multi-kinase inhibitor with anti-leukemic efficacy regardless of FLT3 mutational status. A phase 1 clinical trial of CG-806 for the treatment of AML has been initiated (NCT04477291).Key pointsThe multi-kinase inhibitor CG-806 exerts superior anti-leukemic activity in AML, regardless of its FLT3 status.CG-806 triggered G1 arrest in FLT3 mutated cells and G2/M arrest in FLT3 WT cells through the suppression of FLT3/BTK and aurora kinases.Concomitantly targeting FLT3 and Bcl-2 and/or Mcl-1 exerted synergistic pro-apoptotic effects on both FLT3 WT and mutated AML cells.

Keywords:  CG-806; FLT3; Multi-kinase inhibitor; acute myeloid leukemia

DOI:  https://doi.org/10.1080/10428194.2024.2364839
Trends Biochem Sci. 2024 Jun 13. pii: S0968-0004(24)00113-0. [Epub ahead of print]

Functional implications of fumarate-induced cysteine succination.

Iva Guberovic, Christian Frezza.

  Mutations in metabolic enzymes are associated with hereditary and sporadic forms of cancer. For example, loss-of-function mutations affecting fumarate hydratase (FH), the tricarboxylic acid (TCA) cycle enzyme, result in the accumulation of millimolar levels of fumarate that cause an aggressive form of kidney cancer. A distinct feature of fumarate is its ability to spontaneously react with thiol groups of cysteines in a chemical reaction termed succination. Although succination of a few proteins has been causally implicated in the molecular features of FH-deficient cancers, the stoichiometry, wider functional consequences, and contribution of succination to disease development remain largely unexplored. We discuss the functional implications of fumarate-induced succination in FH-deficient cells, the available methodologies, and the current challenges in studying this post-translational modification.

Keywords:  2-(succino)cysteine (2SC); biomarker; fumarate; hereditary leiomyomatosis and renal cell carcinoma (HLRCC); metabolic rewiring; oncometabolite

DOI:  https://doi.org/10.1016/j.tibs.2024.05.003
J Exp Clin Cancer Res. 2024 Jun 14. 43(1): 166

Mitochondrial transfer from Adipose stem cells to breast cancer cells drives multi-drug resistance.

Vitale Del Vecchio, Ayesha Rehman, Sameer Kumar Panda, Martina Torsiello, Martina Marigliano, Maria Maddalena Nicoletti, Giuseppe Andrea Ferraro, Vincenzo De Falco, Rosamaria Lappano, Eva Lieto, Francesca Pagliuca, Carlo Caputo, Marcella La Noce, Gianpaolo Papaccio, Virginia Tirino, Nirmal Robinson, Vincenzo Desiderio, Federica Papaccio.

   BACKGROUND: Breast cancer (BC) is a complex disease, showing heterogeneity in the genetic background, molecular subtype, and treatment algorithm. Historically, treatment strategies have been directed towards cancer cells, but these are not the unique components of the tumor bulk, where a key role is played by the tumor microenvironment (TME), whose better understanding could be crucial to obtain better outcomes.
METHODS: We evaluated mitochondrial transfer (MT) by co-culturing Adipose stem cells with different Breast cancer cells (BCCs), through MitoTracker assay, Mitoception, confocal and immunofluorescence analyses. MT inhibitors were used to confirm the MT by Tunneling Nano Tubes (TNTs). MT effect on multi-drug resistance (MDR) was assessed using Doxorubicin assay and ABC transporter evaluation. In addition, ATP production was measured by Oxygen Consumption rates (OCR) and Immunoblot analysis.
RESULTS: We found that MT occurs via Tunneling Nano Tubes (TNTs) and can be blocked by actin polymerization inhibitors. Furthermore, in hybrid co-cultures between ASCs and patient-derived organoids we found a massive MT. Breast Cancer cells (BCCs) with ASCs derived mitochondria (ADM) showed a reduced HIF-1α expression in hypoxic conditions, with an increased ATP production driving ABC transporters-mediated multi-drug resistance (MDR), linked to oxidative phosphorylation metabolism rewiring.
CONCLUSIONS: We provide a proof-of-concept of the occurrence of Mitochondrial Transfer (MT) from Adipose Stem Cells (ASCs) to BC models. Blocking MT from ASCs to BCCs could be a new effective therapeutic strategy for BC treatment.

Keywords:  Adipose Stem cells; Breast Cancer; Mitoception; Mitochondrial transfer; Multi-drug resistance; Tunneling nanotubes

DOI:  https://doi.org/10.1186/s13046-024-03087-8
Cancer Sci. 2024 Jun 15.

Alternative magnetic field exposure suppresses tumor growth via metabolic reprogramming.

Taisuke Akimoto, Md Rafikul Islam, Akane Nagasako, Kazuhito Kishi, Rina Nakakaji, Makoto Ohtake, Hisashi Hasumi, Takashi Yamaguchi, Shigeki Yamada, Tetsuya Yamamoto, Yoshihiro Ishikawa, Masanari Umemura.

  Application of physical forces, ranging from ultrasound to electric fields, is recommended in various clinical practice guidelines, including those for treating cancers and bone fractures. However, the mechanistic details of such treatments are often inadequately understood, primarily due to the absence of comprehensive study models. In this study, we demonstrate that an alternating magnetic field (AMF) inherently possesses a direct anti-cancer effect by enhancing oxidative phosphorylation (OXPHOS) and thereby inducing metabolic reprogramming. We observed that the proliferation of human glioblastoma multiforme (GBM) cells (U87 and LN229) was inhibited upon exposure to AMF within a specific narrow frequency range, including around 227 kHz. In contrast, this exposure did not affect normal human astrocytes (NHA). Additionally, in mouse models implanted with human GBM cells in the brain, daily exposure to AMF for 30 min over 21 days significantly suppressed tumor growth and prolonged overall survival. This effect was associated with heightened reactive oxygen species (ROS) production and increased manganese superoxide dismutase (MnSOD) expression. The anti-cancer efficacy of AMF was diminished by either a mitochondrial complex IV inhibitor or a ROS scavenger. Along with these observations, there was a decrease in the extracellular acidification rate (ECAR) and an increase in the oxygen consumption rate (OCR). This suggests that AMF-induced metabolic reprogramming occurs in GBM cells but not in normal cells. Our results suggest that AMF exposure may offer a straightforward strategy to inhibit cancer cell growth by leveraging oxidative stress through metabolic reprogramming.

Keywords:  alternating magnetic field (AMF); glioblastoma multiforme (GBM); metabolic reprogramming; mitochondria; oxidative phosphorylation (OXPHOS); reactive oxygen species (ROS)

DOI:  https://doi.org/10.1111/cas.16243
Cancer Gene Ther. 2024 Jun 08.

Proteomic profiling reveals ACSS2 facilitating metabolic support in acute myeloid leukemia.

Liliana H Mochmann, Denise Treue, Michael Bockmayr, Patricia Silva, Christin Zasada, Guido Mastrobuoni, Safak Bayram, Martin Forbes, Philipp Jurmeister, Sven Liebig, Olga Blau, Konstanze Schleich, Bianca Splettstoesser, Thierry M Nordmann, Eva K von der Heide, Konstandina Isaakidis, Veronika Schulze, Caroline Busch, Hafsa Siddiq, Cornelia Schlee, Svenja Hester, Lars Fransecky, Martin Neumann, Stefan Kempa, Frederick Klauschen, Claudia D Baldus.

Acute myeloid leukemia (AML) is a heterogeneous disease characterized by genomic aberrations in oncogenes, cytogenetic abnormalities, and an aberrant epigenetic landscape. Nearly 50% of AML cases will relapse with current treatment. A major source of therapy resistance is the interaction of mesenchymal stroma with leukemic cells resulting in therapeutic protection. We aimed to determine pro-survival/anti-apoptotic protein networks involved in the stroma protection of leukemic cells. Proteomic profiling of cultured primary AML (n = 14) with Hs5 stroma cell line uncovered an up-regulation of energy-favorable metabolic proteins. Next, we modulated stroma-induced drug resistance with an epigenetic drug library, resulting in reduced apoptosis with histone deacetylase inhibitor (HDACi) treatment versus other epigenetic modifying compounds. Quantitative phosphoproteomic probing of this effect further revealed a metabolic-enriched phosphoproteome including significant up-regulation of acetyl-coenzyme A synthetase (ACSS2, S30) in leukemia-stroma HDACi treated cocultures compared with untreated monocultures. Validating these findings, we show ACSS2 substrate, acetate, promotes leukemic proliferation, ACSS2 knockout in leukemia cells inhibits leukemic proliferation and ACSS2 knockout in the stroma impairs leukemic metabolic fitness. Finally, we identify ACSS1/ACSS2-high expression AML subtype correlating with poor overall survival. Collectively, this study uncovers the leukemia-stroma phosphoproteome emphasizing a role for ACSS2 in mediating AML growth and drug resistance.

DOI: https://doi.org/10.1038/s41417-024-00785-5
Theranostics. 2024 ;14(8): 3282-3299

Combined activation of artificial and natural ion channels for disrupting mitochondrial ion homeostasis towards effective postoperative tumor recurrence and metastasis suppression.

Panqin Ma, Zheng Luo, Qi Wang, Ying Chen, Feng Liu, Changliang Ren, Caisheng Wu, Zibiao Li, Yun-Long Wu.

  Rationale: Pharmacological targeting of mitochondrial ion channels is developing as a new direction in cancer therapy. The opening or closing of these channels can impact mitochondrial function and structure by interfering with intracellular ion homeostasis, thereby regulating cell fate. Nevertheless, their abnormal expression or regulation poses challenges in eliminating cancer cells, and further contributes to metastasis, recurrence, and drug resistance. Methods: We developed an engineered mitochondrial targeted delivery system with self-reinforcing potassium ion (K+) influx via amphiphilic mitochondrial targeting polymer (TMP) as carriers to co-deliver natural K+ channel agonists (Dinitrogen oxide, DZX) and artificial K+ channel molecules (5F8). Results: Using this method, DZX specifically activated natural K+ channels, whereas 5F8 assembled artificial K+ channels on the mitochondrial membrane, leading to mitochondrial K+ influx, as well as oxidative stress and activation of the mitochondrial apoptotic pathway. Conclusion: The synergistic effect of 5F8 and DZX presents greater effectiveness in killing cancer cells than DZX alone, and effectively inhibited tumor recurrence and lung metastasis following surgical resection of breast cancer tumors in animal models. This strategy innovatively integrates antihypertensive drugs with artificial ion channel molecules for the first time to effectively inhibit tumor recurrence and metastasis by disrupting intracellular ion homeostasis, which will provide a novel perspective for postoperative tumor therapy.

Keywords:  artificial K+ channels; mitochondrial homeostasis; mitochondrial ion channels; synergistic effect; tumor recurrence and metastasis

DOI:  https://doi.org/10.7150/thno.94855
Proc Natl Acad Sci U S A. 2024 Jun 18. 121(25): e2409269121

SIRT7 promotes lung cancer progression by destabilizing the tumor suppressor ARF.

Poonam Kumari, Shahriar Tarighi, Eva Fuchshuber, Luhan Li, Irene Fernández-Duran, Meilin Wang, Joshua Ayoson, Jose Manuel Castelló-García, Andrés Gámez-García, Maria Espinosa-Alcantud, Krishnamoorthy Sreenivasan, Stefan Guenther, Mireia Olivella, Rajkumar Savai, Shijing Yue, Alejandro Vaquero, Thomas Braun, Alessandro Ianni.

  Sirtuin 7 (SIRT7) is a member of the mammalian family of nicotinamide adenine dinucleotide (NAD+)-dependent histone/protein deacetylases, known as sirtuins. It acts as a potent oncogene in numerous malignancies, but the molecular mechanisms employed by SIRT7 to sustain lung cancer progression remain largely uncharacterized. We demonstrate that SIRT7 exerts oncogenic functions in lung cancer cells by destabilizing the tumor suppressor alternative reading frame (ARF). SIRT7 directly interacts with ARF and prevents binding of ARF to nucleophosmin, thereby promoting proteasomal-dependent degradation of ARF. We show that SIRT7-mediated degradation of ARF increases expression of protumorigenic genes and stimulates proliferation of non-small-cell lung cancer (NSCLC) cells both in vitro and in vivo in a mouse xenograft model. Bioinformatics analysis of transcriptome data from human lung adenocarcinomas revealed a correlation between SIRT7 expression and increased activity of genes normally repressed by ARF. We propose that disruption of SIRT7-ARF signaling stabilizes ARF and thus attenuates cancer cell proliferation, offering a strategy to mitigate NSCLC progression.

Keywords:  ARF; SIRT7; Sirtuins; lung cancer; nucleophosmin

DOI:  https://doi.org/10.1073/pnas.2409269121
Blood Adv. 2024 Jun 11. pii: bloodadvances.2023012298. [Epub ahead of print]

Venetoclax resistance leads to broad resistance to standard-of-care anti-MM agents, but not to immunotherapies.

Shuhui Deng, Sanika Derebail, Vera Joy Weiler, Jessica Fong Ng, Elena Maroto-Martin, Madhumouli Chatterjee, Giulia Giorgetti, Chandraditya Chakraborty, Poonam Kalhotra, Ting Du, Yao Yao, Rao H Prabhala, Masood A Shammas, Annamaria Gulla, Anil Aktas Samur, Mehmet K Samur, Lugui Qiu, Kenneth C Anderson, Mariateresa Fulciniti, Nikhil C Munshi.

Venetoclax is the first example of personalized medicine for multiple myeloma (MM), with meaningful clinical activity as a monotherapy and in combination in myeloma patients harboring the t(11:14) translocation. However, despite the high response rates and prolonged PFS, a significant proportion of patients eventually relapse. Here, we aimed to study adaptive molecular responses after the acquisition of venetoclax resistance in sensitive t(11:14) MM cell models. We therefore generated single-cell venetoclax-resistant t(11:14) MM cell lines and investigated the mechanisms contributing to resistance as well as the cells' sensitivity to other treatments. Our data suggests that acquired resistance to venetoclax is characterized by reduced mitochondrial priming and changes in BCL-2 family proteins' expression in MM cells, conferring broad resistance to standard-of-care anti-myeloma drugs. However, our results show that the resistant cells are still sensitive to immunotherapeutic treatments, highlighting the need to consider appropriate sequencing of these treatments following venetoclax-based regimens.

DOI: https://doi.org/10.1182/bloodadvances.2023012298
Mol Oncol. 2024 Jun 14.

Targeting metabolic reprogramming to overcome drug resistance in advanced bladder cancer: insights from gemcitabine- and cisplatin-resistant models.

Ichiro Kawahara, Hirofumi Yoshino, Wataru Fukumoto, Junya Arima, Saeki Saito, Gang Li, Ikumi Fukuda, Akihiko Mitsuke, Takashi Sakaguchi, Satoru Inoguchi, Ryosuke Matsushita, Masayuki Nakagawa, Shuichi Tatarano, Yasutoshi Yamada, Hideki Enokida.

  Gemcitabine plus cisplatin (GC) combination chemotherapy is the primary treatment for advanced bladder cancer (BC) with unresectable or metastatic disease. However, most cases develop resistance to this therapy. We investigated whether drug resistance could be targeted through metabolic reprogramming therapies. Metabolomics analyses in our lab's gemcitabine- and cisplatin-resistant cell lines revealed increased phosphoglycerate dehydrogenase (PHGDH) expression in gemcitabine-resistant cells compared with parental cells. Isocitrate dehydrogenase 2 (IDH2) gain of function stabilized hypoxia-inducible factor1α (HIF1α) expression, stimulating aerobic glycolysis. In gemcitabine-resistant cells, elevated fumaric acid suppressed prolyl hydroxylase domain-containing protein 2/Egl nine homolog 1 (PHD2) and stabilized HIF1α expression. PHGDH downregulation or inhibition in gemcitabine-resistant BC cells inhibited their proliferation, migration, and invasion. Cisplatin-resistant cells showed elevated fatty acid metabolism, upregulating fatty acid synthase (FASN) downstream of tyrosine kinase. Using the fibroblast growth factor receptor (FGFR) tyrosine kinase inhibitor erdafitinib, we inhibited malonyl-CoA production, which is crucial for fatty acid synthesis, and thereby suppressed upregulated HIF1α expression. Combination treatment with NCT503 and erdafitinib synergistically suppressed tumor cell proliferation and induced apoptosis in vitro and in vivo. Understanding these mechanisms could enable innovative BC therapeutic strategies to be developed.

Keywords:  FASN; FGFR; HIF1α; PHGDH; erdefitinib; metabolism

DOI:  https://doi.org/10.1002/1878-0261.13684
Cold Spring Harb Perspect Med. 2024 Jun 10. pii: a041544. [Epub ahead of print]

Metabolic Signaling in Cancer.

Laura V Pinheiro, Pedro Costa-Pinheiro, Kathryn E Wellen.

Metabolic reprogramming in cancer allows cells to survive in harsh environments and sustain macromolecular biosynthesis to support proliferation. In addition, metabolites play crucial roles as signaling molecules. Metabolite fluctuations are detected by various sensors in the cell to regulate gene expression, metabolism, and signal transduction. Metabolic signaling mechanisms contribute to tumorigenesis by altering the physiology of cancer cells themselves, as well as that of neighboring cells in the tumor microenvironment. In this review, we discuss principles of metabolic signaling and provide examples of how cancer cells take advantage of metabolic signals to promote cell proliferation and evade the immune system, thereby contributing to tumor growth and progression.

DOI: https://doi.org/10.1101/cshperspect.a041544
Cancer Treat Rev. 2024 May 24. pii: S0305-7372(24)00099-9. [Epub ahead of print]129 102771

Overview of BH3 mimetics in ovarian cancer.

Donatella Del Bufalo, Giovanna Damia.

  Ovarian carcinoma is the leading cause of gynecological cancer-related death, still with a dismal five-year prognosis, mainly due to late diagnosis and the emergence of resistance to cytotoxic and targeted agents. Bcl-2 family proteins have a key role in apoptosis and are associated with tumor development/progression and response to therapy in different cancer types, including ovarian carcinoma. In tumors, evasion of apoptosis is a possible mechanism of resistance to therapy. BH3 mimetics are small molecules that occupy the hydrophobic pocket on pro-survival proteins, allowing the induction of apoptosis, and are currently under study as single agents and/or in combination with cytotoxic and targeted agents in solid tumors. Here, we discuss recent advances in targeting anti-apoptotic proteins of the Bcl-2 family for the treatment of ovarian cancer, focusing on BH3 mimetics, and how these approaches could potentially offer an alternative/complementary way to treat patients and overcome or delay resistance to current treatments.

Keywords:  BH3 mimetics; Cancer therapy; Clinical trials; Inhibitors of anti-apoptotic Bcl-2 family members; Ovarian cancer; Preclinical models

DOI:  https://doi.org/10.1016/j.ctrv.2024.102771
Cell Rep. 2024 Jun 11. pii: S2211-1247(24)00673-9. [Epub ahead of print]43(6): 114345

CRISPR activation screens identify the SWI/SNF ATPases as suppressors of ferroptosis.

Kamakoti P Bhat, Jinchu Vijay, Caroline K Vilas, Jyoti Asundi, Jun Zou, Ted Lau, Xiaoyu Cai, Musaddeque Ahmed, Michal Kabza, Julie Weng, Jean-Philippe Fortin, Aaron Lun, Steffen Durinck, Marc Hafner, Michael R Costa, Xin Ye.

  Ferroptosis is an iron-dependent cell death mechanism characterized by the accumulation of toxic lipid peroxides and cell membrane rupture. GPX4 (glutathione peroxidase 4) prevents ferroptosis by reducing these lipid peroxides into lipid alcohols. Ferroptosis induction by GPX4 inhibition has emerged as a vulnerability of cancer cells, highlighting the need to identify ferroptosis regulators that may be exploited therapeutically. Through genome-wide CRISPR activation screens, we identify the SWI/SNF (switch/sucrose non-fermentable) ATPases BRM (SMARCA2) and BRG1 (SMARCA4) as ferroptosis suppressors. Mechanistically, they bind to and increase chromatin accessibility at NRF2 target loci, thus boosting NRF2 transcriptional output to counter lipid peroxidation and confer resistance to GPX4 inhibition. We further demonstrate that the BRM/BRG1 ferroptosis connection can be leveraged to enhance the paralog dependency of BRG1 mutant cancer cells on BRM. Our data reveal ferroptosis induction as a potential avenue for broadening the efficacy of BRM degraders/inhibitors and define a specific genetic context for exploiting GPX4 dependency.

Keywords:  CP: Cancer; CP: Molecular biology

DOI:  https://doi.org/10.1016/j.celrep.2024.114345
J Physiol. 2024 Jun 10.

The mitochondrial calcium uniporter: Balancing tumourigenic and anti-tumourigenic responses.

Danielle M Colussi, Peter B Stathopulos.

  Increased malignancy and poor treatability associated with solid tumour cancers have commonly been attributed to mitochondrial calcium (Ca2+) dysregulation. The mitochondrial Ca2+ uniporter complex (mtCU) is the predominant mode of Ca2+ uptake into the mitochondrial matrix. The main components of mtCU are the pore-forming mitochondrial Ca2+ uniporter (MCU) subunit, MCU dominant-negative beta (MCUb) subunit, essential MCU regulator (EMRE) and the gatekeeping mitochondrial Ca2+ uptake 1 and 2 (MICU1 and MICU2) proteins. In this review, we describe mtCU-mediated mitochondrial Ca2+ dysregulation in solid tumour cancer types, finding enhanced mtCU activity observed in colorectal cancer, breast cancer, oral squamous cell carcinoma, pancreatic cancer, hepatocellular carcinoma and embryonal rhabdomyosarcoma. By contrast, decreased mtCU activity is associated with melanoma, whereas the nature of mtCU dysregulation remains unclear in glioblastoma. Furthermore, we show that numerous polymorphisms associated with cancer may alter phosphorylation sites on the pore forming MCU and MCUb subunits, which cluster at interfaces with EMRE. We highlight downstream/upstream biomolecular modulators of MCU and MCUb that alter mtCU-mediated mitochondrial Ca2+ uptake and may be used as biomarkers or to aid in the development of novel cancer therapeutics. Additionally, we provide an overview of the current small molecule inhibitors of mtCU that interact with the Asp residue of the critical Asp-Ile-Met-Glu motif or through other allosteric regulatory mechanisms to block Ca2+ permeation. Finally, we describe the relationship between MCU- and MCUb-mediating microRNAs and mitochondrial Ca2+ uptake that should be considered in the discovery of new treatment approaches for cancer.

Keywords:  MCU; MCU dominant negative beta subunit; MCUb; cancer; miRNA; mitochondrial calcium uniporter; mutation; phosphorylation

DOI:  https://doi.org/10.1113/JP285515