bims-mibica 2024-08-11 papers

bims-mibica

Biomed News

on Mitochondrial bioenergetics in cancer

Issue of 2024‒08‒11
23 papers selected by
Kelsey Fisher-Wellman, Wake Forest University

SLC25A48 controls mitochondrial choline import and metabolism.
Mitochondrial proteome analysis reveals that an augmented cytochrome c oxidase assembly and activity potentiates respiratory capacity in sarcoma.
Metabolic and transcriptomic reprogramming during contact inhibition-induced quiescence is mediated by YAP-dependent and YAP-independent mechanisms.
Purinosomes spatially co-localize with mitochondrial transporters.
The polyunsaturated fatty acid docosahexaenoic affects mitochondrial function in prostate cancer cells.
Targeting fatty acid oxidation enhances response to HER2-targeted therapy.
Real-time assessment of mitochondrial DNA heteroplasmy dynamics at the single-cell level.
Glycosphingolipid synthesis mediates immune evasion in KRAS-driven cancer.
BCAA-producing Clostridium symbiosum promotes colorectal tumorigenesis through the modulation of host cholesterol metabolism.
Epigenetic repression of de novo cysteine synthetases induces intra-cellular accumulation of cysteine in hepatocarcinoma by up-regulating the cystine uptake transporter xCT.
Identification of mitochondrial ATP synthase as the cellular target of Ru-polypyridyl-β-carboline complexes by affinity-based protein profiling.
LP-118 is a novel B-cell lymphoma 2 / extra-large inhibitor that demonstrates efficacy in models of venetoclax-resistant chronic lymphocytic leukemia.
Regulation of cancer cell lipid metabolism and oxidative phosphorylation by microenvironmental acidosis.
Nrf2 as a regulator of energy metabolism and mitochondrial function.
Glutamine withdrawal leads to the preferential activation of lipid metabolism in metastatic colorectal cancer.
Regulation of the hematopoietic stem cell pool by C-Kit-associated trogocytosis.
Iron Overloading Potentiates the Antitumor Activity of 5-Fluorouracil by Promoting Apoptosis and Ferroptosis in Colorectal Cancer Cells.
Sphingosine-1 phosphate receptor 1 (S1PR1) expression maintains stemness of acute myeloid leukemia stem cells.
Discovery of a Myeloid Cell Leukemia 1 (Mcl-1) Inhibitor That Demonstrates Potent In Vivo Activities in Mouse Models of Hematological and Solid Tumors.
LARP1, an RNA-binding protein, participates in ovarian cancer cell survival by regulating mitochondrial oxidative phosphorylation in response to the influence of the PI3K/mTOR pathway.
Discovery of Novel Mcl-1 Inhibitors with a 3-Substituted-1H-indole-1-yl Moiety Binding to the P1-P3 Pockets to Induce Apoptosis in Acute Myeloid Leukemia Cells.
Remodeling of the bone marrow microenvironment during acute myeloid leukemia progression.
Synergistic Effects of Glutamine Deprivation and Metformin in Acute Myeloid Leukemia.

Cell Metab. 2024 Aug 01. pii: S1550-4131(24)00281-X. [Epub ahead of print]

SLC25A48 controls mitochondrial choline import and metabolism.

Anthony R P Verkerke, Xu Shi, Mark Li, Yusuke Higuchi, Tadashi Yamamuro, Daisuke Katoh, Hiroshi Nishida, Christopher Auger, Ichitaro Abe, Robert E Gerszten, Shingo Kajimura.

  Choline is an essential nutrient for the biosynthesis of phospholipids, neurotransmitters, and one-carbon metabolism with a critical step being its import into mitochondria. However, the underlying mechanisms and biological significance remain poorly understood. Here, we report that SLC25A48, a previously uncharacterized mitochondrial inner-membrane carrier protein, controls mitochondrial choline transport and the synthesis of choline-derived methyl donors. We found that SLC25A48 was required for brown fat thermogenesis, mitochondrial respiration, and mitochondrial membrane integrity. Choline uptake into the mitochondrial matrix via SLC25A48 facilitated the synthesis of betaine and purine nucleotides, whereas loss of SLC25A48 resulted in increased production of mitochondrial reactive oxygen species and imbalanced mitochondrial lipids. Notably, human cells carrying a single nucleotide polymorphism on the SLC25A48 gene and cancer cells lacking SLC25A48 exhibited decreased mitochondrial choline import, increased oxidative stress, and impaired cell proliferation. Together, this study demonstrates that SLC25A48 regulates mitochondrial choline catabolism, bioenergetics, and cell survival.

Keywords:  bioenergetics; brown adipose tissue; cancer metabolism; choline; mitochondria; purine nucleotides

DOI:  https://doi.org/10.1016/j.cmet.2024.07.010
Biochem Biophys Res Commun. 2024 Aug 05. pii: S0006-291X(24)01037-4. [Epub ahead of print]736 150501

Mitochondrial proteome analysis reveals that an augmented cytochrome c oxidase assembly and activity potentiates respiratory capacity in sarcoma.

Minakshi Bedi, Surajit Das, Jagannath Das, Soumyajit Mukherjee, Abhimanyu Basu, Sudipto Saha, Alok Ghosh.

  Mitochondrial oxidative phosphorylation (OXPHOS) is an obligatory process in sarcoma. Despite that, the metabolic programming of sarcoma mitochondria is still unknown. To obtain a comprehensive metabolic insight of mitochondria, we developed a mouse fibrosarcoma model by injecting 3-methylcholanthrene and compared mitochondrial proteomes between sarcoma and its contralateral normal muscle using mass spectrometry. Our study identified ∼449 proteins listed in the SwissProt databases, and all the data sets are available via ProteomeXchange with the identifier PXD044903. In sarcoma, 49 mitochondrial proteins were found differentially expressed, including 36 proteins up-regulated and 13 proteins down-regulated, with the significance of p-value <0.05 and the log2[fold change] > 1 and < -1 as compared to normal muscle. Our data revealed that various anaplerotic reactions actively replenish the TCA cycle in sarcoma. The comparative expression profile and Western blotting analysis of OXPHOS subunits showed that complex-IV subunits, MT-CO3 and COX6A1, were significantly up-regulated in sarcoma vs. normal muscle. Further, biochemical and physiological assays confirmed enhanced complex-IV specific enzymatic and supercomplex activities with a concomitant increase of oxygen consumption rate in sarcoma mitochondria compared to normal muscle. Validation with human post-operative sarcoma tissues also confirms an increased MT-CO3 expression compared to normal tissue counterparts. Thus, our data comprehensively analyses the mitochondrial proteome and identifies augmented complex-IV assembly and activity in sarcoma.

Keywords:  Differential proteomics; Mitochondrial complex-IV; OXPHOS; Sarcoma

DOI:  https://doi.org/10.1016/j.bbrc.2024.150501
Nat Commun. 2024 Aug 08. 15(1): 6777

Metabolic and transcriptomic reprogramming during contact inhibition-induced quiescence is mediated by YAP-dependent and YAP-independent mechanisms.

Soeun Kang, Maciek R Antoniewicz, Nissim Hay.

Metabolic rewiring during the proliferation-to-quiescence transition is poorly understood. Here, using a model of contact inhibition-induced quiescence, we conducted 13C-metabolic flux analysis in proliferating (P) and quiescent (Q) mouse embryonic fibroblasts (MEFs) to investigate this process. Q cells exhibit reduced glycolysis but increased TCA cycle flux and mitochondrial respiration. Reduced glycolytic flux in Q cells correlates with reduced glycolytic enzyme expression mediated by yes-associated protein (YAP) inhibition. The increased TCA cycle activity and respiration in Q cells is mediated by induced mitochondrial pyruvate carrier (MPC) expression, rendering them vulnerable to MPC inhibition. The malate-to-pyruvate flux, which generates NADPH, is markedly reduced by modulating malic enzyme 1 (ME1) dimerization in Q cells. Conversely, the malate dehydrogenase 1 (MDH1)-mediated oxaloacetate-to-malate flux is reversed and elevated in Q cells, driven by high mitochondrial-derived malate levels, reduced cytosolic oxaloacetate, elevated MDH1 levels, and a high cytoplasmic NAD+/NADH ratio. Transcriptomic analysis revealed large number of genes are induced in Q cells, many of which are associated with the extracellular matrix (ECM), while YAP-dependent and cell cycle-related genes are repressed. The results suggest that high TCA cycle flux and respiration in Q cells are required to generate ATP and amino acids to maintain de-novo ECM protein synthesis and secretion.

DOI: https://doi.org/10.1038/s41467-024-51117-y
J Biol Chem. 2024 Aug 02. pii: S0021-9258(24)02121-5. [Epub ahead of print] 107620

Purinosomes spatially co-localize with mitochondrial transporters.

Zhou Sha, Stephen J Benkovic.

  In this study, we advance our understanding of the spatial relationship between the purinosome, a liquid condensate consisting of six enzymes involved in de novo purine biosynthesis, and mitochondria. Previous research has shown that purinosomes move along tubulin toward mitochondria, suggesting a direct uptake of glycine from mitochondria. Here, we propose that the purinosome is located proximally to the mitochondrial transporters SLC25A13 and SLC25A38, facilitating the uptake of glycine, aspartate, and glutamate, essential factors for purine synthesis. We utilized the proximity ligation assay (PLA) and APEX proximity labeling to investigate the association between purinosome proteins and mitochondrial transporters. Our results indicate that purinosome assembly occurs close to the mitochondrial membrane under purine-deficient conditions, with the transporters migrating to be adjacent to the purinosome. Furthermore, both targeted and non-targeted analyses suggest that the SLC25A13-APEX2-V5 probe accurately reflects endogenous cellular status. These findings provide insights into the spatial organization of purine biosynthesis and lay the groundwork for further investigations into additional proteins involved in this pathway.

Keywords:  APEX; Purinosomes; de novo purine biosynthesis; mitochondrial transporter; proximity ligation assay (PLA)

DOI:  https://doi.org/10.1016/j.jbc.2024.107620
Cancer Metab. 2024 Aug 07. 12(1): 24

The polyunsaturated fatty acid docosahexaenoic affects mitochondrial function in prostate cancer cells.

Guilherme Henrique Tamarindo, Caroline Fidalgo Ribeiro, Alana Della Torre Silva, Alex Castro, Ícaro Putinhon Caruso, Fátima Pereira Souza, Sebastião Roberto Taboga, Massimo Loda, Rejane Maira Góes.

  BACKGROUND: Prostate cancer (PCa) shows a rewired metabolism featuring increased fatty acid uptake and synthesis via de novo lipogenesis, both sharply related to mitochondrial physiology. The docosahexaenoic acid (DHA) is an omega-3 polyunsaturated fatty acid (PUFA) that exerts its antitumoral properties via different mechanisms, but its specific action on mitochondria in PCa is not clear. Therefore, we investigated whether the DHA modulates mitochondrial function in PCa cell lines.METHODS: Here, we evaluated mitochondrial function of non-malignant PNT1A and the castration-resistant (CRPC) prostate 22Rv1 and PC3 cell lines in response to DHA incubation. For this purpose, we used Seahorse extracellular flux assay to assess mitochondria function, [14C]-glucose to evaluate its oxidation as well as its contribution to fatty acid synthesis, 1H-NMR for metabolite profile determination, MitoSOX for superoxide anion production, JC-1 for mitochondrial membrane polarization, mass spectrometry for determination of phosphatidylglycerol levels and composition, staining with MitoTracker dye to assess mitochondrial morphology under super-resolution in addition to Transmission Electron Microscopy, In-Cell ELISA for COX-I and SDH-A protein expression and flow cytometry (Annexin V and 7-AAD) for cell death estimation.
RESULTS: In all cell lines DHA decreased basal respiratory activity, ATP production, and the spare capacity in mitochondria. Also, the omega-3 induced mitochondrial hyperpolarization, ROS overproduction and changes in membrane phosphatidylglycerol composition. In PNT1A, DHA led to mitochondrial fragmentation and it increased glycolysis while in cancer cells it stimulated glucose oxidation, but decreased de novo lipogenesis specifically in 22Rv1, indicating a metabolic shift. In all cell lines, DHA modulated several metabolites related to energy metabolism and it was incorporated in phosphatidylglycerol, a precursor of cardiolipin, increasing the unsaturation index in the mitochondrial membrane. Accordingly, DHA triggered cell death mainly in PNT1A and 22Rv1.
CONCLUSION: In conclusion, mitochondrial metabolism is significantly affected by the PUFA supplementation to the point that cells are not able to proliferate or survive under DHA-enriched condition. Moreover, combination of DHA supplementation with inhibition of metabolism-related pathways, such as de novo lipogenesis, may be synergistic in castration-resistant prostate cancer.

Keywords:  Docosahexaenoic acid; Lipid metabolism; Mitochondria; Omega-3 polyunsaturated fatty acids; Prostate cancer cells

DOI:  https://doi.org/10.1186/s40170-024-00348-0
Nat Commun. 2024 Aug 03. 15(1): 6587

Targeting fatty acid oxidation enhances response to HER2-targeted therapy.

Ipshita Nandi, Linjia Ji, Harvey W Smith, Daina Avizonis, Vasilios Papavasiliou, Cynthia Lavoie, Alain Pacis, Sherif Attalla, Virginie Sanguin-Gendreau, William J Muller.

Metabolic reprogramming, a hallmark of tumorigenesis, involves alterations in glucose and fatty acid metabolism. Here, we investigate the role of Carnitine palmitoyl transferase 1a (Cpt1a), a key enzyme in long-chain fatty acid (LCFA) oxidation, in ErbB2-driven breast cancers. In ErbB2+ breast cancer models, ablation of Cpt1a delays tumor onset, growth, and metastasis. However, Cpt1a-deficient cells exhibit increased glucose dependency that enables survival and eventual tumor progression. Consequently, these cells exhibit heightened oxidative stress and upregulated nuclear factor erythroid 2-related factor 2 (Nrf2) activity. Inhibiting Nrf2 or silencing its expression reduces proliferation and glucose consumption in Cpt1a-deficient cells. Combining the ketogenic diet, composed of LCFAs, or an anti-ErbB2 monoclonal antibody (mAb) with Cpt1a deficiency significantly perturbs tumor growth, enhances apoptosis, and reduces lung metastasis. Using an immunocompetent model, we show that Cpt1a inhibition promotes an antitumor immune microenvironment, thereby enhancing the efficacy of anti-ErbB2 mAbs. Our findings underscore the importance of targeting fatty acid oxidation alongside HER2-targeted therapies to combat resistance in HER2+ breast cancer patients.

DOI: https://doi.org/10.1038/s41467-024-50998-3
EMBO J. 2024 Aug 05.

Real-time assessment of mitochondrial DNA heteroplasmy dynamics at the single-cell level.

Rodaria Roussou, Dirk Metzler, Francesco Padovani, Felix Thoma, Rebecca Schwarz, Boris Shraiman, Kurt M Schmoller, Christof Osman.

  Mitochondrial DNA (mtDNA) is present in multiple copies within cells and is required for mitochondrial ATP generation. Even within individual cells, mtDNA copies can differ in their sequence, a state known as heteroplasmy. The principles underlying dynamic changes in the degree of heteroplasmy remain incompletely understood, due to the inability to monitor this phenomenon in real time. Here, we employ mtDNA-based fluorescent markers, microfluidics, and automated cell tracking, to follow mtDNA variants in live heteroplasmic yeast populations at the single-cell level. This approach, in combination with direct mtDNA tracking and data-driven mathematical modeling reveals asymmetric partitioning of mtDNA copies during cell division, as well as limited mitochondrial fusion and fission frequencies, as critical driving forces for mtDNA variant segregation. Given that our approach also facilitates assessment of segregation between intact and mutant mtDNA, we anticipate that it will be instrumental in elucidating the mechanisms underlying the purifying selection of mtDNA.

Keywords:  Heteroplasmy; Mathematical Modeling; Mitochondria; Mitochondrial Fission; mtDNA

DOI:  https://doi.org/10.1038/s44318-024-00183-5
Nature. 2024 Aug 07.

Glycosphingolipid synthesis mediates immune evasion in KRAS-driven cancer.

Mariluz Soula, Gokhan Unlu, Rachel Welch, Aleksey Chudnovskiy, Beste Uygur, Vyom Shah, Hanan Alwaseem, Paul Bunk, Vishvak Subramanyam, Hsi-Wen Yeh, Artem Khan, Søren Heissel, Hani Goodarzi, Gabriel D Victora, Semir Beyaz, Kıvanç Birsoy.

Cancer cells frequently alter their lipids to grow and adapt to their environment1-3. Despite the critical functions of lipid metabolism in membrane physiology, signalling and energy production, how specific lipids contribute to tumorigenesis remains incompletely understood. Here, using functional genomics and lipidomic approaches, we identified de novo sphingolipid synthesis as an essential pathway for cancer immune evasion. Synthesis of sphingolipids is surprisingly dispensable for cancer cell proliferation in culture or in immunodeficient mice but required for tumour growth in multiple syngeneic models. Blocking sphingolipid production in cancer cells enhances the anti-proliferative effects of natural killer and CD8+ T cells partly via interferon-γ (IFNγ) signalling. Mechanistically, depletion of glycosphingolipids increases surface levels of IFNγ receptor subunit 1 (IFNGR1), which mediates IFNγ-induced growth arrest and pro-inflammatory signalling. Finally, pharmacological inhibition of glycosphingolipid synthesis synergizes with checkpoint blockade therapy to enhance anti-tumour immune response. Altogether, our work identifies glycosphingolipids as necessary and limiting metabolites for cancer immune evasion.

DOI: https://doi.org/10.1038/s41586-024-07787-1
Cell Host Microbe. 2024 Aug 01. pii: S1931-3128(24)00271-3. [Epub ahead of print]

BCAA-producing Clostridium symbiosum promotes colorectal tumorigenesis through the modulation of host cholesterol metabolism.

Yi-Meng Ren, Zi-Yan Zhuang, Yuan-Hong Xie, Peng-Jie Yang, Tian-Xue Xia, Yi-Le Xie, Zhu-Hui Liu, Zi-Ran Kang, Xiao-Xu Leng, Shi-Yuan Lu, Lu Zhang, Jin-Xian Chen, Jia Xu, En-Hao Zhao, Zheng Wang, Ming Wang, Yun Cui, Juan Tan, Qiang Liu, Wei-Hong Jiang, Hua Xiong, Jie Hong, Ying-Xuan Chen, Hao-Yan Chen, Jing-Yuan Fang.

  Identification of potential bacterial players in colorectal tumorigenesis has been a focus of intense research. Herein, we find that Clostridium symbiosum (C. symbiosum) is selectively enriched in tumor tissues of patients with colorectal cancer (CRC) and associated with higher colorectal adenoma recurrence after endoscopic polypectomy. The tumorigenic effect of C. symbiosum is observed in multiple murine models. Single-cell transcriptome profiling along with functional assays demonstrates that C. symbiosum promotes the proliferation of colonic stem cells and enhances cancer stemness. Mechanistically, C. symbiosum intensifies cellular cholesterol synthesis by producing branched-chain amino acids (BCAAs), which sequentially activates Sonic hedgehog signaling. Low dietary BCAA intake or blockade of cholesterol synthesis by statins could partially abrogate the C. symbiosum-induced cell proliferation in vivo and in vitro. Collectively, we reveal C. symbiosum as a bacterial driver of colorectal tumorigenesis, thus identifying a potential target in CRC prediction, prevention, and treatment.

Keywords:  Clostridium symbiosum; Hedgehog signaling; branched-chain amino acids; cholesterol metabolism; colorectal cancer; mTORC1 signaling; stemness

DOI:  https://doi.org/10.1016/j.chom.2024.07.012
Cancer Metab. 2024 Aug 07. 12(1): 23

Epigenetic repression of de novo cysteine synthetases induces intra-cellular accumulation of cysteine in hepatocarcinoma by up-regulating the cystine uptake transporter xCT.

Tomoaki Yamauchi, Yumi Okano, Daishu Terada, Sai Yasukochi, Akito Tsuruta, Yuya Tsurudome, Kentaro Ushijima, Naoya Matsunaga, Satoru Koyanagi, Shigehiro Ohdo.

  BACKGROUND: The metabolic reprogramming of amino acids is critical for cancer cell growth and survival. Notably, intracellular accumulation of cysteine is often observed in various cancers, suggesting its potential role in alleviating the oxidative stress associated with rapid proliferation. The liver is the primary organ for cysteine biosynthesis, but much remains unknown about the metabolic alterations of cysteine and their mechanisms in hepatocellular carcinoma cells.METHODS: RNA-seq data from patients with hepatocarcinoma were analyzed using the TNMplot database. The underlying mechanism of the oncogenic alteration of cysteine metabolism was studied in mice implanted with BNL 1ME A.7 R.1 hepatocarcinoma.
RESULTS: Database analysis of patients with hepatocellular carcinoma revealed that the expression of enzymes involved in de novo cysteine synthesis was down-regulated accompanying with increased expression of the cystine uptake transporter xCT. Similar alterations in gene expression have also been observed in a syngeneic mouse model of hepatocarcinoma. The enhanced expression of DNA methyltransferase in murine hepatocarcinoma cells caused methylation of the upstream regions of cysteine synthesis genes, thereby repressing their expression. Conversely, suppression of de novo cysteine synthesis in healthy liver cells induced xCT expression by up-regulating the oxidative-stress response factor NRF2, indicating that reduced de novo cysteine synthesis repulsively increases cystine uptake via enhanced xCT expression, leading to intracellular cysteine accumulation. Furthermore, the pharmacological inhibition of xCT activity decreased intracellular cysteine levels and suppressed hepatocarcinoma tumor growth in mice.
CONCLUSIONS: Our findings indicate an underlying mechanism of the oncogenic alteration of cysteine metabolism in hepatocarcinoma and highlight the efficacy of alteration of cysteine metabolism as a viable therapeutic target in cancer.

Keywords:  Cysteine metabolism; DNA methylation; Erastin; Hepatocarcinoma; NRF2; de novo cysteine synthesis; xCT

DOI:  https://doi.org/10.1186/s40170-024-00352-4
Natl Sci Rev. 2024 Aug;11(8): nwae234

Identification of mitochondrial ATP synthase as the cellular target of Ru-polypyridyl-β-carboline complexes by affinity-based protein profiling.

Wen-Jin Wang, Yu-Yi Ling, Yin Shi, Xiao-Wen Wu, Xuxian Su, Zheng-Qiu Li, Zong-Wan Mao, Cai-Ping Tan.

  Ruthenium polypyridyl complexes are promising anticancer candidates, while their cellular targets have rarely been identified, which limits their clinical application. Herein, we design a series of Ru(II) polypyridyl complexes containing bioactive β-carboline derivatives as ligands for anticancer evaluation, among which Ru5 shows suitable lipophilicity, high aqueous solubility, relatively high anticancer activity and cancer cell selectivity. The subsequent utilization of a photo-clickable probe, Ru5a, serves to validate the significance of ATP synthase as a crucial target for Ru5 through photoaffinity-based protein profiling. Ru5 accumulates in mitochondria, impairs mitochondrial functions and induces mitophagy and ferroptosis. Combined analysis of mitochondrial proteomics and RNA-sequencing shows that Ru5 significantly downregulates the expression of the chloride channel protein, and influences genes related to ferroptosis and epithelial-to-mesenchymal transition. Finally, we prove that Ru5 exhibits higher anticancer efficacy than cisplatin in vivo. We firstly identify the molecular targets of ruthenium polypyridyl complexes using a photo-click proteomic method coupled with a multiomics approach, which provides an innovative strategy to elucidate the anticancer mechanisms of metallo-anticancer candidates.

Keywords:  ATPase inhibitor; anticancer agents; bimolecular targets; chemical proteomics; ferroptosis

DOI:  https://doi.org/10.1093/nsr/nwae234
Haematologica. 2024 Aug 08.

LP-118 is a novel B-cell lymphoma 2 / extra-large inhibitor that demonstrates efficacy in models of venetoclax-resistant chronic lymphocytic leukemia.

Janani Ravikrishnan, Daisy Y Diaz-Rohena, Elizabeth Muhowski, Xiaokui Mo, Tzung-Huei Lai, Shrilekha Misra, Charmelle D Williams, John Sanchez, Andrew Mitchell, Suresh Satpati, Elizabeth Perry, Tierney Kaufman, Chaomei Liu, Arletta Lozanski, Gerard Lozanski, KerryA Rogers, Adam S Kittai, Seema A Bhat, Mary C Collins, Matthew S Davids, Nitin Jain, William G Wierda, Rosa Lapalombella, John C Byrd, Fenlai Tan, Yi Chen, Yu Chen, Yue Shen, Stephen P Anthony, Jennifer A Woyach, Deepa Sampath.

Patients with chronic lymphocytic leukemia (CLL) respond well to initial treatment with the Bcell lymphoma 2 (BCL2) inhibitor venetoclax. Upon relapse, they often retain sensitivity to BCL2 targeting, but durability of response remains a concern. We hypothesize that targeting both BCL2 and B-cell lymphoma-extra large (BCLXL) will be a successful strategy to treat CLL, including for patients who relapse on venetoclax. To test this hypothesis, we conducted a pre-clinical investigation of LP-118, a highly potent inhibitor of BCL2 with moderate BCLXL inhibition to minimize platelet toxicity. This study demonstrated that LP-118 induces efficient BAK activation, cytochrome C release, and apoptosis in both venetoclax naïve and resistant CLL cells. Significantly, LP-118 is effective in cell lines expressing the BCL2 G101V mutation and in cells expressing BCLXL but lacking BCL2 dependence. Using an immunocompetent mouse model, Eμ-TCL1, LP-118 demonstrates low platelet toxicity, which hampered earlier BCLXL inhibitors. Finally, LP-118 in the RS4;11 and OSU-CLL xenograft models results in decreases in tumor burden and survival advantage, respectively. These results provide a mechanistic rationale for the evaluation of LP-118 for the treatment of venetoclax responsive and relapsed CLL.

DOI: https://doi.org/10.3324/haematol.2023.284353
Am J Physiol Cell Physiol. 2024 Aug 05.

Regulation of cancer cell lipid metabolism and oxidative phosphorylation by microenvironmental acidosis.

Michala G Rolver, Marc Severin, Stine F Pedersen.

  The expansion of cancer cell mass in solid tumors generates a harsh environment characterized by dynamically varying levels of acidosis, hypoxia and nutrient deprivation. Because acidosis inhibits glycolytic metabolism and hypoxia inhibits oxidative phosphorylation, cancer cells that survive and grow in these environments must rewire their metabolism and develop a high degree of metabolic plasticity to meet their energetic and biosynthetic demands. Cancer cells frequently upregulate pathways enabling the uptake and utilization of lipids and other nutrients derived from dead or recruited stromal cells, and in particular lipid uptake is strongly enhanced in acidic microenvironments. The resulting lipid accumulation and increased reliance on β-oxidation and mitochondrial metabolism increases susceptibility to oxidative stress, lipotoxicity and ferroptosis, in turn driving changes that may mitigate such risks. The spatially and temporally heterogeneous tumor microenvironment thus selects for invasive, metabolically flexible, and resilient cancer cells capable of exploiting their local conditions as well as of seeking out more favorable surroundings. This phenotype relies on the interplay between metabolism, acidosis and oncogenic mutations, driving metabolic signaling pathways such as peroxisome proliferator-activated receptors (PPARs). Understanding the particular vulnerabilities of such cells may uncover novel therapeutic liabilities of the most aggressive cancer cells.

Keywords:  ferroptosis; lipid metabolism; mitochondria; oxidative phosphorylation; peroxisomes

DOI:  https://doi.org/10.1152/ajpcell.00429.2024
FEBS Lett. 2024 Aug 08.

Nrf2 as a regulator of energy metabolism and mitochondrial function.

Alina Luchkova, Ana Mata, Susana Cadenas.

  Nuclear factor erythroid-2-related factor 2 (Nrf2) is essential for the control of cellular redox homeostasis. When activated, Nrf2 elicits cytoprotective effects through the expression of several genes encoding antioxidant and detoxifying enzymes. Nrf2 can also improve antioxidant defense via the pentose phosphate pathway by increasing NADPH availability to regenerate glutathione. Microarray and genome-wide localization analyses have identified many Nrf2 target genes beyond those linked to its redox-regulatory capacity. Nrf2 regulates several intermediary metabolic pathways and is involved in cancer cell metabolic reprogramming, contributing to malignant phenotypes. Nrf2 also modulates substrate utilization for mitochondrial respiration. Here we review the experimental evidence supporting the essential role of Nrf2 in the regulation of energy metabolism and mitochondrial function.

Keywords:  Nrf2; energy metabolism; metabolic reprogramming; mitochondria; oxidative stress; redox signaling

DOI:  https://doi.org/10.1002/1873-3468.14993
Transl Oncol. 2024 Aug 06. pii: S1936-5233(24)00205-5. [Epub ahead of print]48 102078

Glutamine withdrawal leads to the preferential activation of lipid metabolism in metastatic colorectal cancer.

Aliye Ezgi Güleç Taşkıran, Diren Arda Karaoğlu, Cemil Can Eylem, Çağdaş Ermiş, İsmail Güderer, Emirhan Nemutlu, Seçil Demirkol Canlı, Sreeparna Banerjee.

  INTRODUCTION: Glutamine is a non-essential amino acid that is critical for cell growth. However, the differential metabolism of l-glutamine in metastatic versus primary colorectal cancer (CRC) has not been evaluated adequately.MATERIALS AND METHODS: Differential expression of glutamine-related genes was determined in primary versus metastatic CRC. Univariate Cox regression and hierarchical clustering were used to generate a gene signature for prognostication. Untargeted metabolomics and 18O based fluxomics were used to identify differential metabolite levels and energy turnover in the paired primary (SW480) and metastatic (SW620) CRC cells. Western blot and qRT-PCR were used to validate differential gene expression. Subcellular localization of E-cadherin was determined by immunocytochemistry. Lipid droplets were visualized with Nile Red.
RESULTS: The GO term "Glutamine metabolism" was significantly enriched in metastatic versus primary tumors. Supporting this, SW620 cells showed decreased membrane localization of E-cadherin and increased motility upon l-Glutamine withdrawal. A glutamine related signature associated with worse prognosis was identified and validated in multiple datasets. A fluxomics assay revealed a slower TCA cycle in SW480 and SW620 cells upon l-Glutamine withdrawal. SW620 cells, however, could maintain high ATP levels. Untargeted metabolomics indicated the preferential metabolism of fatty acids in SW620 but not SW480 cells. Lipids were mainly obtained from the environment rather than by de novo synthesis.
CONCLUSIONS: Metastatic CRC cells can display aberrant glutamine metabolism. We show for the first time that upon l-glutamine withdrawal, SW620 (but not SW480) cells were metabolically plastic and could metabolize lipids for survival and cellular motility.

Keywords:  Colorectal cancer; L-Glutamine; Lipid metabolism; Metabolic plasticity

DOI:  https://doi.org/10.1016/j.tranon.2024.102078
Science. 2024 Aug 09. 385(6709): eadp2065

Regulation of the hematopoietic stem cell pool by C-Kit-associated trogocytosis.

Xin Gao, Randall S Carpenter, Philip E Boulais, Dachuan Zhang, Christopher R Marlein, Huihui Li, Matthew Smith, David J Chung, Maria Maryanovich, Britta Will, Ulrich Steidl, Paul S Frenette.

Hematopoietic stem cells (HSCs) are routinely mobilized from the bone marrow (BM) to the blood circulation for clinical transplantation. However, the precise mechanisms by which individual stem cells exit the marrow are not understood. This study identified cell-extrinsic and molecular determinants of a mobilizable pool of blood-forming stem cells. We found that a subset of HSCs displays macrophage-associated markers on their cell surface. Although fully functional, these HSCs are selectively niche-retained as opposed to stem cells lacking macrophage markers, which exit the BM upon forced mobilization. Macrophage markers on HSCs could be acquired through direct transfer by trogocytosis, regulated by receptor tyrosine-protein kinase C-Kit (CD117), from BM-resident macrophages in mouse and human settings. Our study provides proof of concept that adult stem cells utilize trogocytosis to rapidly establish and activate function-modulating molecular mechanisms.

DOI: https://doi.org/10.1126/science.adp2065
Cell Biochem Biophys. 2024 Aug 04.

Iron Overloading Potentiates the Antitumor Activity of 5-Fluorouracil by Promoting Apoptosis and Ferroptosis in Colorectal Cancer Cells.

Bilal Rah, Jasmin Shafarin, Asima Karim, Khuloud Bajbouj, Mawieh Hamad, Jibran Sualeh Muhammad.

  Resistance to 5-fluorouracil (5-FU) remains a significant challenge in colorectal cancer (CRC) treatment. Ferric ammonium citrate (FAC) is commonly used as an iron supplement due to its food-fortification properties; however, its potential role as a chemosensitizer in cancer therapy has not been studied. In this study, we explored the ability of FAC to sensitize CRC cells and increase their susceptibility to 5-FU-mediated anticancer effects. We assessed cell viability, cell cycle progression, apoptosis, mitochondrial membrane potential (MMP), reactive oxygen species (ROS) levels, ferroptosis, and iron metabolism-related protein expression using two CRC cell lines. Additionally, we conducted in silico analyses to compare iron markers in normal colon and CRC tumor tissues. Compared to controls, CRC cells pretreated with FAC and then treated with 5-FU exhibited significantly reduced growth and viability, along with increased ROS-mediated ferroptosis. Mechanistically, FAC-pretreated then 5-FU-treated CRC cells showed enhanced apoptosis, increased Bak/Bax expression, MMP depolarization, and decreased antiapoptotic protein levels (Bcl-2 and Bcl-xL). This combined treatment also led to G2/M cell cycle arrest, upregulation of p21 and p27, and downregulation of cyclin D1, c-Myc, survivin, and GPX4. Analysis of human colon tumor tissue revealed decreased expression of IRP-1, HMOX-1, and FTH1 but increased HAMP expression. In contrast, FAC-pretreated/5-FU-treated CRC cells exhibited a reverse pattern, suggesting that FAC-induced chemosensitization enhances 5-FU-mediated anticancer activity in CRC by disrupting iron homeostasis. These findings highlight the potential of iron overload as a chemosensitization strategy for improving CRC chemotherapy.

Keywords:  Apoptosis; Chemosensitivity; Colorectal cancer; Ferric ammonium citrate; Ferroptosis; Iron overload

DOI:  https://doi.org/10.1007/s12013-024-01463-x
Cancer Lett. 2024 Aug 05. pii: S0304-3835(24)00553-6. [Epub ahead of print] 217158

Sphingosine-1 phosphate receptor 1 (S1PR1) expression maintains stemness of acute myeloid leukemia stem cells.

Yu-Qing Wang, Yue Ren, Robert Peter Gale, Li-Ting Niu, Xiao-Jun Huang.

  Acute myeloid leukemia (AML) arises from leukemia stem cells (LSCs) and is maintained by cells which have acquired features of stemness. We compared transcription profiles of AML cells with/without stem cell features defined as in vitro clonogenicity and serial engraftment in immune-deficient mice xenograft model. We used multi-parameter flow cytometry (MPFC) to separate CD34+ bone marrow-derived leukemia cells into sphingosine-1 phosphate receptor 1 (S1PR1)+ and S1PR1- fractions. Cells in the S1PR1+ fraction demonstrated significantly higher clonogenicity and higher engraftment potential compared with those in the S1PR1- fraction. In contrast, CD34+ bone marrow cells from normal samples showed reduced clonogenicity in the S1PR1+ fraction compared with the S1PR1- fraction. Inhibition of S1PR1 expression in an AML cell line reduced the colony-forming potential of KG1 cells. Transcriptomic analyses and rescue experiments indicated PI3K/AKT pathway and MYBL2 are downstream mediators of S1PR1-associated stemness. These findings implicate S1PR1 as a functional biomarker of LSCs and suggest its potential as a therapeutic target in AML treatment.

Keywords:  Acute myeloid leukemia; Leukemia stem cells; S1PR1

DOI:  https://doi.org/10.1016/j.canlet.2024.217158
J Med Chem. 2024 Aug 05.

Discovery of a Myeloid Cell Leukemia 1 (Mcl-1) Inhibitor That Demonstrates Potent In Vivo Activities in Mouse Models of Hematological and Solid Tumors.

James C Tarr, James M Salovich, Martin Aichinger, KyuOk Jeon, Nagarathanam Veerasamy, John L Sensintaffar, Heribert Arnhof, Matthias Samwer, Plamen P Christov, Kwangho Kim, Tobias Wunberg, Norbert Schweifer, Francesca Trapani, Allison Arnold, Florian Martin, Bin Zhao, Nagaraju Miriyala, Danielle Sgubin, Stuart Fogarty, William J Moore, Gordon M Stott, Edward T Olejniczak, Harald Engelhardt, Dorothea Rudolph, Taekyu Lee, Darryl B McConnell, Stephen W Fesik.

Myeloid cell leukemia 1 (Mcl-1) is a key regulator of the intrinsic apoptosis pathway. Overexpression of Mcl-1 is correlated with high tumor grade, poor survival, and both intrinsic and acquired resistance to cancer therapies. Herein, we disclose the structure-guided design of a small molecule Mcl-1 inhibitor, compound 26, that binds to Mcl-1 with subnanomolar affinity, inhibits growth in cell culture assays, and possesses low clearance in mouse and dog pharmacokinetic (PK) experiments. Evaluation of 26 as a single agent in Mcl-1 sensitive hematological and solid tumor xenograft models resulted in regressions. Co-treatment of Mcl-1-sensitive and Mcl-1 insensitive lung cancer derived xenografts with 26 and docetaxel or topotecan, respectively, resulted in an enhanced tumor response. These findings support the premise that pro-apoptotic priming of tumor cells by other therapies in combination with Mcl-1 inhibition may significantly expand the subset of cancers in which Mcl-1 inhibitors may prove beneficial.

DOI: https://doi.org/10.1021/acs.jmedchem.4c01188
Biochim Biophys Acta Mol Basis Dis. 2024 Aug 05. pii: S0925-4439(24)00446-0. [Epub ahead of print] 167453

LARP1, an RNA-binding protein, participates in ovarian cancer cell survival by regulating mitochondrial oxidative phosphorylation in response to the influence of the PI3K/mTOR pathway.

Jiaoyan Ma, Delu Dong, Hang Qi, Jiaxin Li, Huimei Yu, Xiaoqing Hu, Liankun Sun, Luyan Shen.

  Targeting the PI3K/mTOR pathway and modulating mitochondrial adaptation is expected to be a critical approach for cancer therapy. Although the regulation of mitochondria by the PI3K/mTOR pathway has been investigated, it is not well understood due to the complexity of its regulatory mechanisms. RNA-binding proteins (RBPs) selectively regulate gene expression through post-transcriptional modulation, playing a key role in cancer progression. LARP1, a downstream RBP of the mTOR pathway, is involved in mitochondria-mediated BCL-2 cell survival. Therefore, exploring the involvement of LARP1 in PI3K/mTOR-mediated translational regulation of mitochondria-associated proteins in ovarian cancer cells could help elucidate the role of mitochondria in the PI3K/mTOR pathway. We found that, unlike SKOV3 cells, the mitochondrial function of A2780 cells was not affected, which were insensitive to the dual PI3K/mTOR inhibitor PKI-402, suggesting that cell survival may be related to mitochondrial function. Knockdown of the LARP1 gene after PKI-402 treatment resulted in impaired mitochondrial function in A2780 cells, possibly due to decreased mRNA stability and reduced protein translation of the mitochondrial transcription initiation factor, TFB2M, and the respiratory chain complex II subunit, SDHB. LARP1 affects protein translation by binding to TFB2M mRNA, regulating mitochondrial DNA-encoded genes, or indirectly regulating the nuclear DNA-encoded SDHB gene, ultimately interfering with mitochondrial oxidative phosphorylation and leading to apoptosis. Therefore, LARP1 may be an important mediator in the PI3K/mTOR pathway for regulating mRNA translation and mitochondrial function. Targeting RBPs such as LARP1 downstream of the mTOR pathway may provide new insights and potential therapeutic approaches for ovarian cancer treatment.

Keywords:  LARP1; Mitochondrial; OXPHOS; PI3K/mTOR; Translation; mRNA stability

DOI:  https://doi.org/10.1016/j.bbadis.2024.167453
J Med Chem. 2024 Aug 09.

Discovery of Novel Mcl-1 Inhibitors with a 3-Substituted-1H-indole-1-yl Moiety Binding to the P1-P3 Pockets to Induce Apoptosis in Acute Myeloid Leukemia Cells.

Hongguang Deng, Jingyi Zhang, Liang Liu, Hong Zhang, Yu Han, Linlin Wu, Yongkui Jing, Min Huang, Linxiang Zhao.

Mcl-1 is a main antiapoptotic protein in acute myeloid leukemia (AML) and is used as a target to develop inhibitors. Currently, potent Mcl-1 inhibitors primarily interact with the P2-P4 pockets of Mcl-1, but pharmacological modulation by targeting the P1 pocket is less explored. We designed a series of 1H-indole-2-carboxylic acid compounds as novel Mcl-1 inhibitors occupying the P1-P3 pockets and evaluated their Mcl-1 inhibition and apoptosis induction in AML cells. Two-dimensional 15N-HSQC spectroscopy indicated that 47 (Ki = 24 nM) bound to the BH3 binding groove, occupied the P1 pocket in Mcl-1, and formed interactions with Lys234 and Val249. 47 exhibited good microsomal stability and pharmacokinetic profiles, with low potential risk of cardiotoxicity. 47 inhibited tumor growth in HL-60 and THP-1 xenograft models with growth inhibition rate of 63.7% and 57.4%, respectively. Collectively, 47 represents a novel Mcl-1 inhibitor targeting the P1-P3 pockets with excellent antileukemia effects.

DOI: https://doi.org/10.1021/acs.jmedchem.4c00643
Ann Transl Med. 2024 Aug 01. 12(4): 63

Remodeling of the bone marrow microenvironment during acute myeloid leukemia progression.

Amog P Urs, Chinmayee Goda, Rohan Kulkarni.

  Hematopoiesis requires a complex interplay between the hematopoietic stem and progenitor cells and the cells of the bone marrow microenvironment (BMM). The BMM is heterogeneous, with different regions having distinct cellular, molecular, and metabolic composition and function. Studies have shown that this niche is disrupted in patients with acute myeloid leukemia (AML), which plays a crucial role in disease progression. This review provides a comprehensive overview of the components of vascular and endosteal niches and the molecular mechanisms by which they regulate normal hematopoiesis. We also discuss how these niches are modified in the context of AML, into a disease-promoting niche and how the modified niches in turn regulate AML blast survival and proliferation. We focus on mechanisms of modifications in structural and cellular components of the bone marrow (BM) niche by the AML cells and its impact on leukemic progression and patient outcome. Finally, we also discuss mechanisms by which the altered BM niche protects AML blasts from treatment agents, thereby causing therapy resistance in AML patients. We also summarize ongoing clinical trials that target various BM niche components in the treatment of AML patients. Hence, the BM niche represents a promising target to treat AML and promote normal hematopoiesis.

Keywords:  Bone marrow niche (BM niche); acute myeloid leukemia (AML); hematopoietic stem cells (HSC); leukemia; leukemic stem cells (LSC)

DOI:  https://doi.org/10.21037/atm-23-1824
Curr Med Sci. 2024 Aug 03.

Synergistic Effects of Glutamine Deprivation and Metformin in Acute Myeloid Leukemia.

Tong-Yuan Liu, Xing Fu, Ying Yang, Jia Gu, Min Xiao, Deng-Ju Li.

  OBJECTIVE: The metabolic reprogramming of acute myeloid leukemia (AML) cells is a compensatory adaptation to meet energy requirements for rapid proliferation. This study aimed to examine the synergistic effects of glutamine deprivation and metformin exposure on AML cells.METHODS: SKM-1 cells (an AML cell line) were subjected to glutamine deprivation and/or treatment with metformin or bis-2-(5-phenylacetamido-1,2,4-thiadiazol-2-yl) ethyl sulfide (BPTES, a glutaminase inhibitor) or cytarabine. Cell viability was detected by Cell Counting Kit-8 (CCK-8) assay, and cell apoptosis and reactive oxygen species (ROS) by flow cytometry. Western blotting was conducted to examine the levels of apoptotic proteins, including cleaved caspase-3 and poly(ADP-ribose) polymerase (PARP). Moreover, the human long noncoding RNA (lncRNA) microarray was used to analyze gene expression after glutamine deprivation, and results were confirmed with quantitative RT-PCR (qRT-PCR). The expression of metallothionein 2A (MT2A) was suppressed using siRNA. Cell growth and apoptosis were further detected by CCK-8 assay and flow cytometry, respectively, in cells with MT2A knockdown.
RESULTS: Glutamine deprivation or treatment with BPTES inhibited cell growth and induced apoptosis in SKM-1 cells. The lncRNA microarray result showed that the expression of MT family genes was significantly upregulated after glutamine deprivation. MT2A knockdown increased apoptosis, while proliferation was not affected in SKM-1 cells. In addition, metformin inhibited cell growth and induced apoptosis in SKM-1 cells. Both glutamine deprivation and metformin enhanced the sensitivity of SKM-1 cells to cytarabine. Furthermore, the combination of glutamine deprivation with metformin exhibited synergistic antileukemia effects on SKM-1 cells.
CONCLUSION: Targeting glutamine metabolism in combination with metformin is a promising new therapeutic strategy for AML.

Keywords:  acute myeloid leukemia; glutamine; metallothionein; metformin

DOI:  https://doi.org/10.1007/s11596-024-2913-z