bims-mibica 2024-01-07 papers

bims-mibica

Biomed News

on Mitochondrial bioenergetics in cancer

Issue of 2024–01–07
29 papers selected by
Kelsey Fisher-Wellman, East Carolina University

Structural insights into respiratory complex I deficiency and assembly from the mitochondrial disease-related ndufs4-/- mouse.
H+-slip correlated to rotor free-wheeling as cause of F1 FO -ATPase dysfunction in primary mitochondrial disorders.
Metabolic reprogramming by histone deacetylase inhibition preferentially targets NRF2-activated tumors.
TMIGD2 is an orchestrator and therapeutic target on human acute myeloid leukemia stem cells.
Dual regulation of SLC25A39 by AFG3L2 and iron controls mitochondrial glutathione homeostasis.
Alterations in mitochondria isolated from peripheral blood mononuclear cells and tumors of patients with epithelial ovarian cancers.
Metabolic switch regulates lineage plasticity and induces synthetic lethality in triple-negative breast cancer.
Glycine homeostasis requires reverse SHMT flux.
Mitochondrial isocitrate dehydrogenase impedes CAR T cell function by restraining antioxidant metabolism and histone acetylation.
MTCH2 cooperates with MFN2 and lysophosphatidic acid synthesis to sustain mitochondrial fusion.
The consequence of ATP synthase dimer angle on mitochondrial morphology studied by cryo-electron tomography.
Acylspermidines are conserved mitochondrial sirtuin-dependent metabolites.
Hypoxia induces mitochondrial protein lactylation to limit oxidative phosphorylation.
The biology of mitochondrial carrier homolog 2.
p32 regulates glycometabolism and TCA cycle to inhibit ccRCC progression via copper-induced DLAT lipoylation oligomerization.
Mitochondrial Esterase Activity Measured at the Single Organelle Level by Nano-flow Cytometry.
Metformin Increases the Response of Cholangiocarcinoma Cells to Gemcitabine by Suppressing Pyruvate Kinase M2 to Activate Mitochondrial Apoptosis.
The solute carrier SLC25A17 sustains peroxisomal redox homeostasis in diverse mammalian cell lines.
Cell cycle arrest induces lipid droplet formation and confers ferroptosis resistance.
Fatty acid synthesis suppresses dietary polyunsaturated fatty acid use.
Blocking methionine catabolism induces senescence and confers vulnerability to GSK3 inhibition in liver cancer.
Fission-independent compartmentalization of mitochondria during budding yeast cell division.
OXCT1 functions as a succinyltransferase, contributing to hepatocellular carcinoma via succinylating LACTB.
Amino acid intake strategies define pluripotent cell states.
FLT3 tyrosine kinase inhibition modulates PRC2 and promotes differentiation in acute myeloid leukemia.
Bcl-xL targeting eliminates ageing tumor-promoting neutrophils and inhibits lung tumor growth.
Caloric restriction and metformin selectively improved LKB1-mutated NSCLC tumor response to chemo- and chemo-immunotherapy.
Treatment of relapsed or refractory FLT-3 acute myelogenous leukemia with a triplet regimen of hypomethylating agent, venetoclax, and gilteritinib.
KRAS allelic imbalance drives tumour initiation yet suppresses metastasis in colorectal cancer in vivo.

EMBO J. 2024 Jan 02.

Structural insights into respiratory complex I deficiency and assembly from the mitochondrial disease-related ndufs4-/- mouse.

Zhan Yin, Ahmed-Noor A Agip, Hannah R Bridges, Judy Hirst.

  Respiratory complex I (NADH:ubiquinone oxidoreductase) is essential for cellular energy production and NAD+ homeostasis. Complex I mutations cause neuromuscular, mitochondrial diseases, such as Leigh Syndrome, but their molecular-level consequences remain poorly understood. Here, we use a popular complex I-linked mitochondrial disease model, the ndufs4-/- mouse, to define the structural, biochemical, and functional consequences of the absence of subunit NDUFS4. Cryo-EM analyses of the complex I from ndufs4-/- mouse hearts revealed a loose association of the NADH-dehydrogenase module, and discrete classes containing either assembly factor NDUFAF2 or subunit NDUFS6. Subunit NDUFA12, which replaces its paralogue NDUFAF2 in mature complex I, is absent from all classes, compounding the deletion of NDUFS4 and preventing maturation of an NDUFS4-free enzyme. We propose that NDUFAF2 recruits the NADH-dehydrogenase module during assembly of the complex. Taken together, the findings provide new molecular-level understanding of the ndufs4-/- mouse model and complex I-linked mitochondrial disease.

Keywords:  Complex I; Cryo-EM; Leigh Syndrome; Mitochondria; NADH:Ubiquinone Oxidoreductase

DOI:  https://doi.org/10.1038/s44318-023-00001-4
Med Res Rev. 2024 Jan 03.

H+-slip correlated to rotor free-wheeling as cause of F1 FO -ATPase dysfunction in primary mitochondrial disorders.

Salvatore Nesci, Giovanni Romeo.

  Inborn errors of metabolism are related to mitochondrial disorders caused by dysfunction of the oxidative phosphorylation (OXPHOS) system. Congenital hypermetabolism in the infant is a rare disease belonging to Luft syndrome, nonthyroidal hypermetabolism, arising from a singular example of a defect in OXPHOS. The mitochondria lose coupling of mitochondrial substrates oxidation from the ADP phosphorylation. Since Luft syndrome is due to uncoupled cell respiration responsible for deficient in ATP production that originates in the respiratory complexes, a de novo heterozygous variant in the catalytic subunit of mitochondrial F1 FO -ATPase arises as the main cause of an autosomal dominant syndrome of hypermetabolism associated with dysfunction in ATP production, which does not involve the respiratory complexes. The F1 FO -ATPase works as an embedded molecular machine with a rotary action using two different motor engines. The FO , which is an integral domain in the membrane, dissipates the chemical potential difference for H+ , a proton motive force (Δp), across the inner membrane to generate a torsion. The F1 domain-the hydrophilic portion responsible for ATP turnover-is powered by the molecular rotary action to synthesize ATP. The structural and functional coupling of F1 and FO domains support the energy transduction for ATP synthesis. The dissipation of Δp by means of an H+ slip correlated to rotor free-wheeling of the F1 FO -ATPase has been discovered to cause enzyme dysfunction in primary mitochondrial disorders. In this insight, we try to offer commentary and analysis of the molecular mechanism in these impaired mitochondria.

Keywords:  ATP synthase; bioenergetic failure; congenital hypermetabolism; de novo mutation; mitochondria

DOI:  https://doi.org/10.1002/med.22013
Cell Rep. 2023 Dec 30. pii: S2211-1247(23)01640-6. [Epub ahead of print]43(1): 113629

Metabolic reprogramming by histone deacetylase inhibition preferentially targets NRF2-activated tumors.

Dimitris Karagiannis, Warren Wu, Albert Li, Makiko Hayashi, Xiao Chen, Michaela Yip, Vaibhav Mangipudy, Xinjing Xu, Francisco J Sánchez-Rivera, Yadira M Soto-Feliciano, Jiangbin Ye, Thales Papagiannakopoulos, Chao Lu.

  The interplay between metabolism and chromatin signaling is implicated in cancer progression. However, whether and how metabolic reprogramming in tumors generates chromatin vulnerabilities remain unclear. Lung adenocarcinoma (LUAD) tumors frequently harbor aberrant activation of the NRF2 antioxidant pathway, which drives aggressive and chemo-resistant disease. Using a chromatin-focused CRISPR screen, we report that NRF2 activation sensitizes LUAD cells to genetic and chemical inhibition of class I histone deacetylases (HDACs). This association is observed across cultured cells, mouse models, and patient-derived xenografts. Integrative epigenomic, transcriptomic, and metabolomic analysis demonstrates that HDAC inhibition causes widespread redistribution of H4ac and its reader protein, which transcriptionally downregulates metabolic enzymes. This results in reduced flux into amino acid metabolism and de novo nucleotide synthesis pathways that are preferentially required for the survival of NRF2-active cancer cells. Together, our findings suggest NRF2 activation as a potential biomarker for effective repurposing of HDAC inhibitors to treat solid tumors.

Keywords:  CP: Cancer; HDAC inhibitors; NRF2 pathway; cancer epigenetics; cancer metabolism; cancer targeted therapy; epigenetic reprogramming; lung cancer

DOI:  https://doi.org/10.1016/j.celrep.2023.113629
Nat Commun. 2024 Jan 02. 15(1): 11

TMIGD2 is an orchestrator and therapeutic target on human acute myeloid leukemia stem cells.

Hao Wang, R Alejandro Sica, Gurbakhash Kaur, Phillip M Galbo, Zhixin Jing, Christopher D Nishimura, Xiaoxin Ren, Ankit Tanwar, Bijan Etemad-Gilbertson, Britta Will, Deyou Zheng, David Fooksman, Xingxing Zang.

Acute myeloid leukemia (AML) is initiated and sustained by a hierarchy of leukemia stem cells (LSCs), and elimination of this cell population is required for curative therapies. Here we show that transmembrane and immunoglobulin domain containing 2 (TMIGD2), a recently discovered co-stimulatory immune receptor, is aberrantly expressed by human AML cells, and can be used to identify and enrich functional LSCs. We demonstrate that TMIGD2 is required for the development and maintenance of AML and self-renewal of LSCs but is not essential for normal hematopoiesis. Mechanistically, TMIGD2 promotes proliferation, blocks myeloid differentiation and increases cell-cycle of AML cells via an ERK1/2-p90RSK-CREB signaling axis. Targeting TMIGD2 signaling with anti-TMIGD2 monoclonal antibodies attenuates LSC self-renewal and reduces leukemia burden in AML patient-derived xenograft models but has negligible effect on normal hematopoietic stem/progenitor cells. Thus, our studies reveal the function of TMIGD2 in LSCs and provide a promising therapeutic strategy for AML.

DOI: https://doi.org/10.1038/s41467-023-43843-6
Mol Cell. 2023 Dec 20. pii: S1097-2765(23)01027-4. [Epub ahead of print]

Dual regulation of SLC25A39 by AFG3L2 and iron controls mitochondrial glutathione homeostasis.

Xiaojian Shi, Marisa DeCiucis, Kariona A Grabinska, Jean Kanyo, Adam Liu, Tukiet T Lam, Hongying Shen.

  Organelle transporters define metabolic compartmentalization, and how this metabolite transport process can be modulated is poorly explored. Here, we discovered that human SLC25A39, a mitochondrial transporter critical for mitochondrial glutathione uptake, is a short-lived protein under dual regulation at the protein level. Co-immunoprecipitation mass spectrometry and CRISPR knockout (KO) in mammalian cells identified that mitochondrial m-AAA protease AFG3L2 is responsible for degrading SLC25A39 through the matrix loop 1. SLC25A39 senses mitochondrial iron-sulfur cluster using four matrix cysteine residues and inhibits its degradation. SLC25A39 protein regulation is robust in developing and mature neurons. This dual transporter regulation, by protein quality control and metabolic sensing, allows modulating mitochondrial glutathione level in response to iron homeostasis, opening avenues for exploring regulation of metabolic compartmentalization. Neuronal SLC25A39 regulation connects mitochondrial protein quality control, glutathione, and iron homeostasis, which were previously unrelated biochemical features in neurodegeneration.

Keywords:  AFG3L2; SLC25A39; glutathione; iron; mitochondrial transporter; protein quality control

DOI:  https://doi.org/10.1016/j.molcel.2023.12.008
Sci Rep. 2024 01 02. 14(1): 15

Alterations in mitochondria isolated from peripheral blood mononuclear cells and tumors of patients with epithelial ovarian cancers.

Kittipat Charoenkwan, Nattayaporn Apaijai, Sirawit Sriwichaiin, Nipon Chattipakorn, Siriporn C Chattipakorn.

Metabolic alterations play an essential role in ovarian carcinogenesis. The flexibility of mitochondrial functions facilitates cellular adaptation to the tough environment associated with carcinogenesis. An understanding of the differences in mitochondrial functions in normal ovaries and cancers could provide a basis for further exploration of future mitochondria-based screening, diagnosis, prognostic prediction, and targeted therapy for epithelial ovarian cancers. The main objective of this study was to assess mitochondrial function profiles measured from PBMCs and ovarian tissues of epithelial ovarian cancers in comparison with normal ovaries. A total of 36 patients were recruited for the study, all of whom underwent primary surgical treatment for malignant epithelial ovarian neoplasm. Of these, 20 patients were in the early stage and 16 patients were in the advanced stage. Additionally, 21 patients who had pelvic surgery for benign gynecologic conditions, with normal ovaries incidentally removed, were recruited as controls. At the time of surgery, a blood sample was collected from each participant for PBMC isolation, and ovarian tissue was retained for molecular studies. These studies included the examination of oxidative stress, mitochondrial mass, mitochondrial respiration, mitochondrial reactive oxygen species (ROS), mitochondrial membrane potential (MMP) changes, and mitochondrial swelling. Clinical and histopathological data were also collected and compared between different stages of epithelial ovarian cancers: early-stage (group 1), advanced-stage (group 2), and normal ovaries (group 3). The levels of cellular oxidative stress, mitochondrial mass, and mitochondrial biogenesis in the peripheral blood mononuclear cells (PBMCs) of participants with ovarian cancer were significantly lower than those of the control group. However, the mitochondrial respiratory parameters measured from the PBMCs were similar across all three groups. Furthermore, mitochondrial membrane depolarization and mitochondrial swelling were observed in ovarian tissues of both early-stage and advanced-stage cancer groups. We demonstrated the dynamic nature of mitochondrial ROS production, biogenesis, and respiratory function in response to epithelial ovarian carcinogenesis. The flexibility of mitochondrial functions under diverse conditions may make it a challenging therapeutic target for ovarian cancer.

DOI: https://doi.org/10.1038/s41598-023-51009-z
Cell Metab. 2024 Jan 02. pii: S1550-4131(23)00455-2. [Epub ahead of print]36(1): 193-208.e8

Metabolic switch regulates lineage plasticity and induces synthetic lethality in triple-negative breast cancer.

Yingsheng Zhang, Meng-Ju Wu, Wan-Chi Lu, Yi-Chuan Li, Chun Ju Chang, Jer-Yen Yang.

  Metabolic reprogramming is key for cancer development, yet the mechanism that sustains triple-negative breast cancer (TNBC) cell growth despite deficient pyruvate kinase M2 (PKM2) and tumor glycolysis remains to be determined. Here, we find that deficiency in tumor glycolysis activates a metabolic switch from glycolysis to fatty acid β-oxidation (FAO) to fuel TNBC growth. We show that, in TNBC cells, PKM2 directly interacts with histone methyltransferase EZH2 to coordinately mediate epigenetic silencing of a carnitine transporter, SLC16A9. Inhibition of PKM2 leads to impaired EZH2 recruitment to SLC16A9, and in turn de-represses SLC16A9 expression to increase intracellular carnitine influx, programming TNBC cells to an FAO-dependent and luminal-like cell state. Together, these findings reveal a new metabolic switch that drives TNBC from a metabolically heterogeneous-lineage plastic cell state to an FAO-dependent-lineage committed cell state, where dual targeting of EZH2 and FAO induces potent synthetic lethality in TNBC.

Keywords:  EZH2; PKM2; SLC16A9; induced synthetic lethality; lineage plasticity; metabolic reprogramming

DOI:  https://doi.org/10.1016/j.cmet.2023.12.003
Cell Metab. 2024 Jan 02. pii: S1550-4131(23)00452-7. [Epub ahead of print]36(1): 103-115.e4

Glycine homeostasis requires reverse SHMT flux.

Matthew J McBride, Craig J Hunter, Zhaoyue Zhang, Tara TeSlaa, Xincheng Xu, Gregory S Ducker, Joshua D Rabinowitz.

  The folate-dependent enzyme serine hydroxymethyltransferase (SHMT) reversibly converts serine into glycine and a tetrahydrofolate-bound one-carbon unit. Such one-carbon unit production plays a critical role in development, the immune system, and cancer. Using rodent models, here we show that the whole-body SHMT flux acts to net consume rather than produce glycine. Pharmacological inhibition of whole-body SHMT1/2 and genetic knockout of liver SHMT2 elevated circulating glycine levels up to eight-fold. Stable-isotope tracing revealed that the liver converts glycine to serine, which is then converted by serine dehydratase into pyruvate and burned in the tricarboxylic acid cycle. In response to diets deficient in serine and glycine, de novo biosynthetic flux was unaltered, but SHMT2- and serine-dehydratase-mediated catabolic flux was lower. Thus, glucose-derived serine synthesis is largely insensitive to systemic demand. Instead, circulating serine and glycine homeostasis is maintained through variable consumption, with liver SHMT2 a major glycine-consuming enzyme.

Keywords:  SHMT; amino acid metabolism; folate cycle; glycine; hepatic clearance; homeostasis; serine

DOI:  https://doi.org/10.1016/j.cmet.2023.12.001
Cell Metab. 2024 Jan 02. pii: S1550-4131(23)00461-8. [Epub ahead of print]36(1): 176-192.e10

Mitochondrial isocitrate dehydrogenase impedes CAR T cell function by restraining antioxidant metabolism and histone acetylation.

Xiaohui Si, Mi Shao, Xinyi Teng, Yue Huang, Ye Meng, Longyuan Wu, Jieping Wei, Lianxuan Liu, Tianning Gu, Junzhe Song, Ruirui Jing, Xingyuan Zhai, Xin Guo, Delin Kong, Xiujian Wang, Bohan Cai, Ying Shen, Zhaoru Zhang, Dongrui Wang, Yongxian Hu, Pengxu Qian, Gang Xiao, He Huang.

  The efficacy of chimeric antigen receptor (CAR) T cell therapy is hampered by relapse in hematologic malignancies and by hyporesponsiveness in solid tumors. Long-lived memory CAR T cells are critical for improving tumor clearance and long-term protection. However, during rapid ex vivo expansion or in vivo tumor eradication, metabolic shifts and inhibitory signals lead to terminal differentiation and exhaustion of CAR T cells. Through a mitochondria-related compound screening, we find that the FDA-approved isocitrate dehydrogenase 2 (IDH2) inhibitor enasidenib enhances memory CAR T cell formation and sustains anti-leukemic cytotoxicity in vivo. Mechanistically, IDH2 impedes metabolic fitness of CAR T cells by restraining glucose utilization via the pentose phosphate pathway, which alleviates oxidative stress, particularly in nutrient-restricted conditions. In addition, IDH2 limits cytosolic acetyl-CoA levels to prevent histone acetylation that promotes memory cell formation. In combination with pharmacological IDH2 inhibition, CAR T cell therapy is demonstrated to have superior efficacy in a pre-clinical model.

Keywords:  chimeric antigen receptor T cell; enasidenib; exhaustion; histone acetylation; isocitrate dehydrogenase 2; memory T cell formation; nutrient-restricted conditions; pentose phosphate pathway

DOI:  https://doi.org/10.1016/j.cmet.2023.12.010
EMBO Rep. 2023 Dec 14.

MTCH2 cooperates with MFN2 and lysophosphatidic acid synthesis to sustain mitochondrial fusion.

Andres Goldman, Michael Mullokandov, Yehudit Zaltsman, Limor Regev, Smadar Levin-Zaidman, Atan Gross.

  Fusion of the outer mitochondrial membrane (OMM) is regulated by mitofusin 1 (MFN1) and 2 (MFN2), yet the differential contribution of each of these proteins is less understood. Mitochondrial carrier homolog 2 (MTCH2) also plays a role in mitochondrial fusion, but its exact function remains unresolved. MTCH2 overexpression enforces MFN2-independent mitochondrial fusion, proposedly by modulating the phospholipid lysophosphatidic acid (LPA), which is synthesized by glycerol-phosphate acyl transferases (GPATs) in the endoplasmic reticulum (ER) and the OMM. Here we report that MTCH2 requires MFN1 to enforce mitochondrial fusion and that fragmentation caused by loss of MTCH2 can be specifically counterbalanced by overexpression of MFN2 but not MFN1, partially independent of its GTPase activity and mitochondrial localization. Pharmacological inhibition of GPATs (GPATi) or silencing ER-resident GPATs suppresses MFN2's ability to compensate for the loss of MTCH2. Loss of either MTCH2, MFN2, or GPATi does not impair stress-induced mitochondrial fusion, whereas the combined loss of MTCH2 and GPATi or the combined loss of MTCH2 and MFN2 does. Taken together, we unmask two cooperative mechanisms that sustain mitochondrial fusion.

Keywords:  LPA; MFN2; MTCH2; Mitochondria-ER Communication; Mitochondrial Fusion

DOI:  https://doi.org/10.1038/s44319-023-00009-1
Biochem J. 2024 Jan 02. pii: BCJ20230450. [Epub ahead of print]

The consequence of ATP synthase dimer angle on mitochondrial morphology studied by cryo-electron tomography.

Emma Buzzard, Mathew McLaren, Piotr Bragoszewski, Andrea Brancaccio, Holly Ford, Bertram Daum, Patricia Kuwabara, Ian Collinson, Vicki Gold.

  Mitochondrial ATP synthases form rows of dimers, which induce membrane curvature to give cristae their characteristic lamellar or tubular morphology. The angle formed between the central stalks of ATP synthase dimers varies between species. Using cryo-electron tomography and sub-tomogram averaging, we determined the structure of the ATP synthase dimer from the nematode worm C. elegans and show that the dimer angle differs from previously determined structures. The consequences of this species-specific difference at the dimer interface were investigated by comparing C. elegans and S. cerevisiae mitochondrial morphology. We reveal that C. elegans has a larger ATP synthase dimer angle with more lamellar (flatter) cristae when compared to yeast. The underlying cause of this difference was investigated by generating an atomic model of the C. elegans ATP synthase dimer by homology modelling. A comparison of our C. elegans model to an existing S. cerevisiae structure reveals the presence of extensions and rearrangements in C. elegans subunits associated with maintaining the dimer interface. We speculate that increasing dimer angles could provide an advantage for species that inhabit variable-oxygen environments by forming flatter more energetically efficient cristae.

Keywords:  alphafold; atp synthase; cryo-electron microscopy; mitochondria; sub-tomogram averaging

DOI:  https://doi.org/10.1042/BCJ20230450
Nat Chem Biol. 2024 Jan 02.

Acylspermidines are conserved mitochondrial sirtuin-dependent metabolites.

Bingsen Zhang, James Mullmann, Andreas H Ludewig, Irma R Fernandez, Tyler R Bales, Robert S Weiss, Frank C Schroeder.

Sirtuins are nicotinamide adenine dinucleotide (NAD+)-dependent protein lysine deacylases regulating metabolism and stress responses; however, characterization of the removed acyl groups and their downstream metabolic fates remains incomplete. Here we employed untargeted comparative metabolomics to reinvestigate mitochondrial sirtuin biochemistry. First, we identified N-glutarylspermidines as metabolites downstream of the mitochondrial sirtuin SIR-2.3 in Caenorhabditis elegans and demonstrated that SIR-2.3 functions as a lysine deglutarylase and that N-glutarylspermidines can be derived from O-glutaryl-ADP-ribose. Subsequent targeted analysis of C. elegans, mouse and human metabolomes revealed a chemically diverse range of N-acylspermidines, and formation of N-succinylspermidines and/or N-glutarylspermidines was observed downstream of mammalian mitochondrial sirtuin SIRT5 in two cell lines, consistent with annotated functions of SIRT5. Finally, N-glutarylspermidines were found to adversely affect C. elegans lifespan and mammalian cell proliferation. Our results indicate that N-acylspermidines are conserved metabolites downstream of mitochondrial sirtuins that facilitate annotation of sirtuin enzymatic activities in vivo and may contribute to sirtuin-dependent phenotypes.

DOI: https://doi.org/10.1038/s41589-023-01511-2
Cell Res. 2024 Jan;34(1): 13-30

Hypoxia induces mitochondrial protein lactylation to limit oxidative phosphorylation.

Yunzi Mao, Jiaojiao Zhang, Qian Zhou, Xiadi He, Zhifang Zheng, Yun Wei, Kaiqiang Zhou, Yan Lin, Haowen Yu, Haihui Zhang, Yineng Zhou, Pengcheng Lin, Baixing Wu, Yiyuan Yuan, Jianyuan Zhao, Wei Xu, Shimin Zhao.

Oxidative phosphorylation (OXPHOS) consumes oxygen to produce ATP. However, the mechanism that balances OXPHOS activity and intracellular oxygen availability remains elusive. Here, we report that mitochondrial protein lactylation is induced by intracellular hypoxia to constrain OXPHOS. We show that mitochondrial alanyl-tRNA synthetase (AARS2) is a protein lysine lactyltransferase, whose proteasomal degradation is enhanced by proline 377 hydroxylation catalyzed by the oxygen-sensing hydroxylase PHD2. Hypoxia induces AARS2 accumulation to lactylate PDHA1 lysine 336 in the pyruvate dehydrogenase complex and carnitine palmitoyltransferase 2 (CPT2) lysine 457/8, inactivating both enzymes and inhibiting OXPHOS by limiting acetyl-CoA influx from pyruvate and fatty acid oxidation, respectively. PDHA1 and CPT2 lactylation can be reversed by SIRT3 to activate OXPHOS. In mouse muscle cells, lactylation is induced by lactate oxidation-induced intracellular hypoxia during exercise to constrain high-intensity endurance running exhaustion time, which can be increased or decreased by decreasing or increasing lactylation levels, respectively. Our results reveal that mitochondrial protein lactylation integrates intracellular hypoxia and lactate signals to regulate OXPHOS.

DOI: https://doi.org/10.1038/s41422-023-00864-6
Mitochondrion. 2023 Dec 27. pii: S1567-7249(23)00117-4. [Epub ahead of print]75 101837

The biology of mitochondrial carrier homolog 2.

Xiaohe Zheng, Binxiang Chu.

  The mitochondrial carrier system is in charge of small molecule transport between the mitochondria and the cytoplasm as well as being an integral portion of the core mitochondrial function. One member of the mitochondrial carrier family of proteins, mitochondrial carrier homolog 2 (MTCH2), is characterized as a critical mitochondrial outer membrane protein insertase participating in mitochondrial homeostasis. Accumulating evidence demonstrate that MTCH2 is integrally linked to cell death and mitochondrial metabolism, and its genetic alterations cause a variety of disease phenotypes, ranging from obesity, Alzheimer's disease, and tumor. To provide a comprehensive insight into the current understanding of MTCH2, we present a detailed description of the physiopathological functions of MTCH2, ranging from apoptosis, mitochondrial dynamics, and metabolic homeostasis regulation. Moreover, we summarized the impact of MTCH2 in human diseases, and highlighted tumors, to assess the role of MTCH2 mutations or variable expression on pathogenesis and target therapeutic options.

Keywords:  Apoptosis; Lipid metabolism; MTCH2; Mitochondria; Tumor

DOI:  https://doi.org/10.1016/j.mito.2023.101837
Int J Biol Sci. 2024 ;20(2): 516-536

p32 regulates glycometabolism and TCA cycle to inhibit ccRCC progression via copper-induced DLAT lipoylation oligomerization.

Shaoping Tian, Rui Wang, Yiting Wang, Ruibing Chen, Tianyu Lin, Xuesong Xiao, Xinyu Liu, Justin Eze Ideozu, Hua Geng, Yong Wang, Dan Yue.

  A key player in mitochondrial respiration, p32, often referred to as C1QBP, is mostly found in the mitochondrial matrix. Previously, we showed that p32 interacts with DLAT in the mitochondria. Here, we found that p32 expression was reduced in ccRCC and suppressed progression and metastasis in ccRCC animal models. We observed that increasing p32 expression led to an increase in oxidative phosphorylation by interacting with DLAT, thus, regulating the activation of the pyruvate dehydrogenase complex (PDHc). Mechanistically, reduced p32 expression, in concert with DLAT, suppresses PDHc activity and the TCA cycle. Furthermore, our research discovered that p32 has a direct binding affinity for copper, facilitating the copper-induced oligomerization of lipo-DLAT specifically in ccRCC cells. This finding reveals an innovative function of the p32/DLAT/copper complex in regulating glycometabolism and the TCA cycle in ccRCC. Importantly, our research provides important new understandings of the underlying molecular processes causing the abnormal mitochondrial metabolism linked to this cancer.

Keywords:  Clear cell renal cell carcinoma; Copper; DLAT; glycometabolism; p32; tricarboxylic acid cycle

DOI:  https://doi.org/10.7150/ijbs.84399
Anal Chem. 2024 Jan 04.

Mitochondrial Esterase Activity Measured at the Single Organelle Level by Nano-flow Cytometry.

Liyun Su, Kaimin Gao, Ye Tian, Xu Xiao, Cheng Lu, Jingyi Xu, Xiaomei Yan.

Monitoring mitochondrial esterase activity is crucial not only for investigating mitochondrial metabolism but also for assessing the effectiveness of mitochondrial-targeting prodrugs. However, accurately detecting esterase activity within mitochondria poses challenges due to its ubiquitous presence in cells and the uncontrolled localization of fluorogenic probes. To overcome this hurdle and reveal variations among different mitochondria, we isolated mitochondria and preserved their activity and functionality in a buffered environment. Subsequently, we utilized a laboratory-built nano-flow cytometer in conjunction with an esterase-responsive calcein-AM fluorescent probe to measure the esterase activity of individual mitochondria. This approach enabled us to investigate the influence of temperature, pH, metal ions, and various compounds on the mitochondrial esterase activity without any interference from other cellular constituents. Interestingly, we observed a decline in the mitochondrial esterase activity following the administration of mitochondrial respiratory chain inhibitors. Furthermore, we found that mitochondrial esterase activity was notably higher in the presence of a high concentration of ATP compared to that of ADP and AMP. Additionally, we noticed a correlation between elevated levels of complex IV and increased mitochondrial esterase activity. These findings suggest a functional connection between the mitochondrial respiratory chain and mitochondrial esterase activity. Moreover, we detected an upsurge in mitochondrial esterase activity during the early stages of apoptosis, while cellular esterase activity decreased. This highlights the significance of analyzing enzyme activity within specific organelle subregions. In summary, the integration of a nano-flow cytometer and fluorescent dyes introduces a novel method for quantifying mitochondrial enzyme activity with the potential to uncover the alterations and unique functions of other mitochondrial enzymes.

DOI: https://doi.org/10.1021/acs.analchem.3c04321
Dig Dis Sci. 2024 Jan 03.

Metformin Increases the Response of Cholangiocarcinoma Cells to Gemcitabine by Suppressing Pyruvate Kinase M2 to Activate Mitochondrial Apoptosis.

Haishan Deng, Xiaomei Qian, Yongtao Zhang, Wenlong Yu, Ping Yang.

   BACKGROUND: Cholangiocarcinoma (CCA) is a malignant tumor with a high mortality rate. Resistance to chemotherapy remains a major challenge related to cancer treatment, and increasing the sensitivity of cancer cells to therapeutic drugs is a major focus of cancer treatment.
AIMS: We purposed to explore the role of Metformin in CCA involved in chemotherapeutic sensitivity and Pyruvate kinase M2 (PKM2) through regulating mitochondrial apoptosis in the present study.
METHODS: CCA cell lines of HCC9810 and RBE were treated with Metformin companied with antagonists or agonists of PKM2, cells sensitivity to Gemcitabine, cell migration and invasion along with apoptosis, which is mediated by JC-1 and LDH were assayed.
RESULTS: Our results indicated that Metformin and Gemcitabine exhibit synergistic effect on inhibition of cholangiocarcinoma cell viability, cell migration and invasion as well as promotion apoptosis of cholangiocarcinoma cells. In vivo, Metformin combined with Gemcitabine has cooperation in inhibiting the growth of cholangiocarcinoma cell-derived tumors. Moreover, Metformin and Gemcitabine inhibited expression of PKM2 and PDHB in HCC9810 and RBE.
CONCLUSION: Our study suggested that Metformin may increase the response of cholangiocarcinoma cells to Gemcitabine by suppressing PKM2 to activate mitochondrial apoptosis.

Keywords:  Chemosensitivity; Cholangiocarcinoma; Gemcitabine; Metformin; Mitochondrial apoptosis; PKM2

DOI:  https://doi.org/10.1007/s10620-023-08210-x
Free Radic Biol Med. 2023 Dec 29. pii: S0891-5849(23)01191-7. [Epub ahead of print]212 241-254

The solute carrier SLC25A17 sustains peroxisomal redox homeostasis in diverse mammalian cell lines.

Cláudio F Costa, Celien Lismont, Serhii Chornyi, Janet Koster, Hongli Li, Mohamed A F Hussein, Paul P Van Veldhoven, Hans R Waterham, Marc Fransen.

  Despite the crucial role of peroxisomes in cellular redox maintenance, little is known about how these organelles transport redox metabolites across their membrane. In this study, we sought to assess potential associations between the cellular redox landscape and the human peroxisomal solute carrier SLC25A17, also known as PMP34. This carrier has been reported to function as a counter-exchanger of adenine-containing cofactors such as coenzyme A (CoA), dephospho-CoA, flavin adenine dinucleotide, nicotinamide adenine dinucleotide (NAD+), adenosine 3',5'-diphosphate, flavin mononucleotide, and adenosine monophosphate. We found that inactivation of SLC25A17 resulted in a shift toward a more reductive state in the glutathione redox couple (GSSG/GSH) across HEK-293 cells, HeLa cells, and SV40-transformed mouse embryonic fibroblasts, with variable impact on the NADPH levels and the NAD+/NADH redox couple. This phenotype could be rescued by the expression of Candida boidinii Pmp47, a putative SLC25A17 orthologue reported to be essential for the metabolism of medium-chain fatty acids in yeast peroxisomes. In addition, we provide evidence that the alterations in the redox state are not caused by changes in peroxisomal antioxidant enzyme expression, catalase activity, H2O2 membrane permeability, or mitochondrial fitness. Furthermore, treating control and ΔSLC25A17 cells with dehydroepiandrosterone, a commonly used glucose-6-phosphate dehydrogenase inhibitor affecting NADPH regeneration, revealed a kinetic disconnection between the peroxisomal and cytosolic glutathione pools. Additionally, these experiments underscored the impact of SLC25A17 loss on peroxisomal NADPH metabolism. The relevance of these findings is discussed in the context of the still ambiguous substrate specificity of SLC25A17 and the recent observation that the mammalian peroxisomal membrane is readily permeable to both GSH and GSSG.

Keywords:  CoA; Glutathione; Metabolite transport; NADPH; PMP34; Peroxisomes; Redox compartmentalization; SLC25A17

DOI:  https://doi.org/10.1016/j.freeradbiomed.2023.12.035
Nat Commun. 2024 Jan 02. 15(1): 79

Cell cycle arrest induces lipid droplet formation and confers ferroptosis resistance.

Hyemin Lee, Amber Horbath, Lavanya Kondiparthi, Jitendra Kumar Meena, Guang Lei, Shayani Dasgupta, Xiaoguang Liu, Li Zhuang, Pranavi Koppula, Mi Li, Iqbal Mahmud, Bo Wei, Philip L Lorenzi, Khandan Keyomarsi, Masha V Poyurovsky, Kellen Olszewski, Boyi Gan.

How cells coordinate cell cycling with cell survival and death remains incompletely understood. Here, we show that cell cycle arrest has a potent suppressive effect on ferroptosis, a form of regulated cell death induced by overwhelming lipid peroxidation at cellular membranes. Mechanistically, cell cycle arrest induces diacylglycerol acyltransferase (DGAT)-dependent lipid droplet formation to sequester excessive polyunsaturated fatty acids (PUFAs) that accumulate in arrested cells in triacylglycerols (TAGs), resulting in ferroptosis suppression. Consequently, DGAT inhibition orchestrates a reshuffling of PUFAs from TAGs to phospholipids and re-sensitizes arrested cells to ferroptosis. We show that some slow-cycling antimitotic drug-resistant cancer cells, such as 5-fluorouracil-resistant cells, have accumulation of lipid droplets and that combined treatment with ferroptosis inducers and DGAT inhibitors effectively suppresses the growth of 5-fluorouracil-resistant tumors by inducing ferroptosis. Together, these results reveal a role for cell cycle arrest in driving ferroptosis resistance and suggest a ferroptosis-inducing therapeutic strategy to target slow-cycling therapy-resistant cancers.

DOI: https://doi.org/10.1038/s41467-023-44412-7
Nat Commun. 2024 Jan 02. 15(1): 45

Fatty acid synthesis suppresses dietary polyunsaturated fatty acid use.

Anna Worthmann, Julius Ridder, Sharlaine Y L Piel, Ioannis Evangelakos, Melina Musfeldt, Hannah Voß, Marie O'Farrell, Alexander W Fischer, Sangeeta Adak, Monica Sundd, Hasibullah Siffeti, Friederike Haumann, Katja Kloth, Tatjana Bierhals, Markus Heine, Paul Pertzborn, Mira Pauly, Julia-Josefine Scholz, Suman Kundu, Marceline M Fuh, Axel Neu, Klaus Tödter, Maja Hempel, Uwe Knippschild, Clay F Semenkovich, Hartmut Schlüter, Joerg Heeren, Ludger Scheja, Christian Kubisch, Christian Schlein.

Dietary polyunsaturated fatty acids (PUFA) are increasingly recognized for their health benefits, whereas a high production of endogenous fatty acids - a process called de novo lipogenesis (DNL) - is closely linked to metabolic diseases. Determinants of PUFA incorporation into complex lipids are insufficiently understood and may influence the onset and progression of metabolic diseases. Here we show that fatty acid synthase (FASN), the key enzyme of DNL, critically determines the use of dietary PUFA in mice and humans. Moreover, the combination of FASN inhibition and PUFA-supplementation decreases liver triacylglycerols (TAG) in mice fed with high-fat diet. Mechanistically, FASN inhibition causes higher PUFA uptake via the lysophosphatidylcholine transporter MFSD2A, and a diacylglycerol O-acyltransferase 2 (DGAT2)-dependent incorporation of PUFA into TAG. Overall, the outcome of PUFA supplementation may depend on the degree of endogenous DNL and combining PUFA supplementation and FASN inhibition might be a promising approach to target metabolic disease.

DOI: https://doi.org/10.1038/s41467-023-44364-y
Nat Cancer. 2024 Jan 02.

Blocking methionine catabolism induces senescence and confers vulnerability to GSK3 inhibition in liver cancer.

Fuming Li, Pingyu Liu, Wen Mi, Liucheng Li, Nicole M Anderson, Nicholas P Lesner, Michelle Burrows, Jacqueline Plesset, Ariana Majer, Guanlin Wang, Jinyang Li, Lingzhi Zhu, Brian Keith, M Celeste Simon.

Availability of the essential amino acid methionine affects cellular metabolism and growth, and dietary methionine restriction has been implicated as a cancer therapeutic strategy. Nevertheless, how liver cancer cells respond to methionine deprivation and underlying mechanisms remain unclear. Here we find that human liver cancer cells undergo irreversible cell cycle arrest upon methionine deprivation in vitro. Blocking methionine adenosyl transferase 2A (MAT2A)-dependent methionine catabolism induces cell cycle arrest and DNA damage in liver cancer cells, resulting in cellular senescence. A pharmacological screen further identified GSK3 inhibitors as senolytics that selectively kill MAT2A-inhibited senescent liver cancer cells. Importantly, combined treatment with MAT2A and GSK3 inhibitors therapeutically blunts liver tumor growth in vitro and in vivo across multiple models. Together, methionine catabolism is essential for liver tumor growth, and its inhibition can be exploited as an improved pro-senescence strategy for combination with senolytic agents to treat liver cancer.

DOI: https://doi.org/10.1038/s43018-023-00671-3
J Cell Biol. 2024 Mar 04. pii: e202211048. [Epub ahead of print]223(3):

Fission-independent compartmentalization of mitochondria during budding yeast cell division.

Saori R Yoshii, Yves Barral.

Lateral diffusion barriers compartmentalize membranes to generate polarity or asymmetrically partition membrane-associated macromolecules. Budding yeasts assemble such barriers in the endoplasmic reticulum (ER) and the outer nuclear envelope at the bud neck to retain aging factors in the mother cell and generate naïve and rejuvenated daughter cells. However, little is known about whether other organelles are similarly compartmentalized. Here, we show that the membranes of mitochondria are laterally compartmentalized at the bud neck and near the cell poles. The barriers in the inner mitochondrial membrane are constitutive, whereas those in the outer membrane form in response to stresses. The strength of mitochondrial diffusion barriers is regulated positively by spatial cues from the septin axis and negatively by retrograde (RTG) signaling. These data indicate that mitochondria are compartmentalized in a fission-independent manner. We propose that these diffusion barriers promote mitochondrial polarity and contribute to mitochondrial quality control.

DOI: https://doi.org/10.1083/jcb.202211048
Mol Cell. 2023 Dec 28. pii: S1097-2765(23)01019-5. [Epub ahead of print]

OXCT1 functions as a succinyltransferase, contributing to hepatocellular carcinoma via succinylating LACTB.

Wenhao Ma, Yuchen Sun, Ronghui Yan, Pinggen Zhang, Shengqi Shen, Hui Lu, Zilong Zhou, Zetan Jiang, Ling Ye, Qiankun Mao, Nanchi Xiong, Weidong Jia, Linchong Sun, Ping Gao, Huafeng Zhang.

  Metabolic reprogramming is an important feature of cancers that has been closely linked to post-translational protein modification (PTM). Lysine succinylation is a recently identified PTM involved in regulating protein functions, whereas its regulatory mechanism and possible roles in tumor progression remain unclear. Here, we show that OXCT1, an enzyme catalyzing ketone body oxidation, functions as a lysine succinyltransferase to contribute to tumor progression. Mechanistically, we find that OXCT1 functions as a succinyltransferase, with residue G424 essential for this activity. We also identified serine beta-lactamase-like protein (LACTB) as a main target of OXCT1-mediated succinylation. Extensive succinylation of LACTB K284 inhibits its proteolytic activity, resulting in increased mitochondrial membrane potential and respiration, ultimately leading to hepatocellular carcinoma (HCC) progression. In summary, this study establishes lysine succinyltransferase function of OXCT1 and highlights a link between HCC prognosis and LACTB K284 succinylation, suggesting a potentially valuable biomarker and therapeutic target for further development.

Keywords:  LACTB; OXCT1; hepatocellular carcinoma; succinylation

DOI:  https://doi.org/10.1016/j.molcel.2023.11.042
Nat Metab. 2024 Jan 03.

Amino acid intake strategies define pluripotent cell states.

Pavlina K Todorova, Benjamin T Jackson, Vidur Garg, Katrina I Paras, Julia S Brunner, Anna E Bridgeman, Yanyang Chen, Sanjeethan C Baksh, Jielin Yan, Anna-Katerina Hadjantonakis, Lydia W S Finley.

Mammalian preimplantation development is associated with marked metabolic robustness, and embryos can develop under a wide variety of nutrient conditions, including even the complete absence of soluble amino acids. Here we show that mouse embryonic stem cells (ESCs) capture the unique metabolic state of preimplantation embryos and proliferate in the absence of several essential amino acids. Amino acid independence is enabled by constitutive uptake of exogenous protein through macropinocytosis, alongside a robust lysosomal digestive system. Following transition to more committed states, ESCs reduce digestion of extracellular protein and instead become reliant on exogenous amino acids. Accordingly, amino acid withdrawal selects for ESCs that mimic the preimplantation epiblast. More broadly, we find that all lineages of preimplantation blastocysts exhibit constitutive macropinocytic protein uptake and digestion. Taken together, these results highlight exogenous protein uptake and digestion as an intrinsic feature of preimplantation development and provide insight into the catabolic strategies that enable embryos to sustain viability before implantation.

DOI: https://doi.org/10.1038/s42255-023-00940-6
Leukemia. 2024 Jan 05.

FLT3 tyrosine kinase inhibition modulates PRC2 and promotes differentiation in acute myeloid leukemia.

Pamela J Sung, Murugan Selvam, Simone S Riedel, Hongbo M Xie, Katie Bryant, Bryan Manning, Gerald B Wertheim, Katarzyna Kulej, Lucie Pham, Robert L Bowman, Jennifer Peresie, Michael J Nemeth, Ross L Levine, Benjamin A Garcia, Sara E Meyer, Simone Sidoli, Kathrin M Bernt, Martin Carroll.

Internal tandem duplication mutations in fms-like tyrosine kinase 3 (FLT3-ITD) are recurrent in acute myeloid leukemia (AML) and increase the risk of relapse. Clinical responses to FLT3 inhibitors (FLT3i) include myeloid differentiation of the FLT3-ITD clone in nearly half of patients through an unknown mechanism. We identified enhancer of zeste homolog 2 (EZH2), a component of polycomb repressive complex 2 (PRC2), as a mediator of this effect using a proteomic-based screen. FLT3i downregulated EZH2 protein expression and PRC2 activity on H3K27me3. FLT3-ITD and loss-of-function mutations in EZH2 are mutually exclusive in human AML. We demonstrated that FLT3i increase myeloid maturation with reduced stem/progenitor cell populations in murine Flt3-ITD AML. Combining EZH1/2 inhibitors with FLT3i increased terminal maturation of leukemic cells and reduced leukemic burden. Our data suggest that reduced EZH2 activity following FLT3 inhibition promotes myeloid differentiation of FLT3-ITD leukemic cells, providing a mechanistic explanation for the clinical observations. These results demonstrate that in addition to its known cell survival and proliferation signaling, FLT3-ITD has a second, previously undefined function to maintain a myeloid stem/progenitor cell state through modulation of PRC2 activity. Our findings support exploring EZH1/2 inhibitors as therapy for FLT3-ITD AML.

DOI: https://doi.org/10.1038/s41375-023-02131-4
EMBO Mol Med. 2023 Dec 20.

Bcl-xL targeting eliminates ageing tumor-promoting neutrophils and inhibits lung tumor growth.

Anita Bodac, Abdullah Mayet, Sarika Rana, Justine Pascual, Amber D Bowler, Vincent Roh, Nadine Fournier, Ligia Craciun, Pieter Demetter, Freddy Radtke, Etienne Meylan.

  Elevated peripheral blood and tumor-infiltrating neutrophils are often associated with a poor patient prognosis. However, therapeutic strategies to target these cells are difficult to implement due to the life-threatening risk of neutropenia. In a genetically engineered mouse model of lung adenocarcinoma, tumor-associated neutrophils (TAN) demonstrate tumor-supportive capacities and have a prolonged lifespan compared to circulating neutrophils. Here, we show that tumor cell-derived GM-CSF triggers the expression of the anti-apoptotic Bcl-xL protein and enhances neutrophil survival through JAK/STAT signaling. Targeting Bcl-xL activity with a specific BH3 mimetic, A-1331852, blocked the induced neutrophil survival without impacting their normal lifespan. Specifically, oral administration with A-1331852 decreased TAN survival and abundance, and reduced tumor growth without causing neutropenia. We also show that G-CSF, a drug used to combat neutropenia in patients receiving chemotherapy, increased the proportion of young TANs and augmented the anti-tumor effect resulting from Bcl-xL blockade. Finally, our human tumor data indicate the same role for Bcl-xL on pro-tumoral neutrophil survival. These results altogether provide preclinical evidence for safe neutrophil targeting based on their aberrant intra-tumor longevity.

Keywords:  Bcl-xL; Lung Adenocarcinoma; Mouse Models of Lung Cancer; Tumor-associated Neutrophils

DOI:  https://doi.org/10.1038/s44321-023-00013-x
J Exp Clin Cancer Res. 2024 Jan 02. 43(1): 6

Caloric restriction and metformin selectively improved LKB1-mutated NSCLC tumor response to chemo- and chemo-immunotherapy.

Gloriana Ndembe, Ilenia Intini, Massimo Moro, Chiara Grasselli, Andrea Panfili, Nicolò Panini, Augusto Bleve, Mario Occhipinti, Cristina Borzi, Marina Chiara Garassino, Mirko Marabese, Simone Canesi, Eugenio Scanziani, Gabriella Sozzi, Massimo Broggini, Monica Ganzinelli.

   BACKGROUND: About 10% of NSCLCs are mutated in KRAS and impaired in STK11/LKB1, a genetic background associated with poor prognosis, caused by an increase in metastatic burden and resistance to standard therapy. LKB1 is a protein involved in a number of biological processes and is particularly important for its role in the regulation of cell metabolism. LKB1 alterations lead to protein loss that causes mitochondria and metabolic dysfunction that makes cells unable to respond to metabolic stress. Different studies have shown how it is possible to interfere with cancer metabolism using metformin and caloric restriction (CR) and both modify the tumor microenvironment (TME), stimulating the switch from "cold" to "hot". Given the poor therapeutic response of KRASmut/LKB1mut patients, and the role of LKB1 in cell metabolism, we examined whether the addition of metformin and CR enhanced the response to chemo or chemo-immunotherapy in LKB1 impaired tumors.
METHODS: Mouse cell lines were derived from lung nodules of transgenic mice carrying KRASG12D with either functional LKB1 (KRASG12D/LKB1wt) or mutated LKB1 (KRASG12D/LKB1mut). Once stabilized in vitro, these cell lines were inoculated subcutaneously and intramuscularly into immunocompetent mice. Additionally, a patient-derived xenograft (PDX) model was established by directly implanting tumor fragments from patient into immunocompromised mice. The mice bearing these tumor models were subjected to treatment with chemotherapy or chemo-immunotherapy, both as standalone regimens and in combination with metformin and CR.
RESULTS: Our preclinical results indicate that in NSCLC KRASmut/LKB1mut tumors, metformin and CR do enhance the response to chemo and chemo-immunotherapy, inducing a metabolic stress condition that these tumors are not able to overcome. Analysis of immune infiltrating cells did not bring to light any strong correlation between the TME immune-modulation and the tumor response to metformin and CR.
CONCLUSION: Our in vitro and in vivo preliminary studies confirm our hypothesis that the addition of metformin and CR is able to improve the antitumor activity of chemo and chemoimmunotherapy in LKB1 impaired tumors, exploiting their inability to overcome metabolic stress.

Keywords:  Caloric restriction; Cancer metabolism; KRAS; LKB1; Metformin; NSCLC

DOI:  https://doi.org/10.1186/s13046-023-02933-5
Leuk Lymphoma. 2024 Jan 02. 1-6

Treatment of relapsed or refractory FLT-3 acute myelogenous leukemia with a triplet regimen of hypomethylating agent, venetoclax, and gilteritinib.

Dat Ngo, Jose Tinajero, Shanpeng Li, Joycelynne Palmer, Hoda Pourhassan, Ahmed Aribi, Ryotaro Nakamura, Anthony Stein, Guido Marcucci, Amandeep Salhotra, Karamjeet Sandhu, Vinod Pullarkat, Brian Ball, Paul Koller.

  Relapsed or refractory (R/R) acute myeloid leukemia (AML) with FMS-like tyrosine kinase 3 (FLT3) mutations remains a difficult and hard to treat entity. Gilteritinib is a potent oral FLT-3 inhibitor that improves overall survival in R/R AML, but studies are limited in combining gilteritinib with a hypomethylating agent and venetoclax treatment backbone (HMA-VEN-GILT). Here we report our experience with HMA-VEN-GILT for 22 R/R FLT3 AML patients. HMA-VEN-GILT yielded an ORR of 77.3% (17/22), CR 4.5% (1/22), CRi 13.6% (3/22), MLFS 59.1% (13/22). Median follow-up was 10.4 months with a relapse rate of 29.4% (5/17), median time to relapse of 69 days (range 35-298 days), 6-month overall survival of 84%, and median OS of 10.1 months. Additionally, 36.4% (8/22) of patients proceeded to hematopoietic stem cell transplant. In conclusion, HMA-VEN-GILT for the treatment of R/R FLT3 AML is feasible and can be used as a bridge to allogeneic transplantation.

Keywords:  FLT-3 AML; FLT-3 inhibitor; gilteritinib; refractory AML; relapsed AML

DOI:  https://doi.org/10.1080/10428194.2023.2292473
Nat Commun. 2024 Jan 02. 15(1): 100

KRAS allelic imbalance drives tumour initiation yet suppresses metastasis in colorectal cancer in vivo.

Arafath K Najumudeen, Sigrid K Fey, Laura M Millett, Catriona A Ford, Kathryn Gilroy, Nuray Gunduz, Rachel A Ridgway, Eve Anderson, Douglas Strathdee, William Clark, Colin Nixon, Jennifer P Morton, Andrew D Campbell, Owen J Sansom.

Oncogenic KRAS mutations are well-described functionally and are known to drive tumorigenesis. Recent reports describe a significant prevalence of KRAS allelic imbalances or gene dosage changes in human cancers, including loss of the wild-type allele in KRAS mutant cancers. However, the role of wild-type KRAS in tumorigenesis and therapeutic response remains elusive. We report an in vivo murine model of colorectal cancer featuring deletion of wild-type Kras in the context of oncogenic Kras. Deletion of wild-type Kras exacerbates oncogenic KRAS signalling through MAPK and thus drives tumour initiation. Absence of wild-type Kras potentiates the oncogenic effect of KRASG12D, while incidentally inducing sensitivity to inhibition of MEK1/2. Importantly, loss of the wild-type allele in aggressive models of KRASG12D-driven CRC significantly alters tumour progression, and suppresses metastasis through modulation of the immune microenvironment. This study highlights the critical role for wild-type Kras upon tumour initiation, progression and therapeutic response in Kras mutant CRC.

DOI: https://doi.org/10.1038/s41467-023-44342-4