bims-mibica 2023-07-09 papers

bims-mibica

Biomed News

on Mitochondrial bioenergetics in cancer

Issue of 2023‒07‒09
33 papers selected by
Kelsey Fisher-Wellman, East Carolina University

Pyruvate transamination and NAD biosynthesis enable proliferation of succinate dehydrogenase-deficient cells by supporting aerobic glycolysis.
Uncharacterized protein C17orf80: A novel interactor of human mitochondrial nucleoids.
Arf1 coordinates fatty acid metabolism and mitochondrial homeostasis.
Viability of HepG2 and MCF-7 cells is not correlated with mitochondrial bioenergetics.
SLC25A51 promotes tumor growth through sustaining mitochondria acetylation homeostasis and proline biogenesis.
CISD3 is required for Complex I function, mitochondrial integrity, and skeletal muscle maintenance.
Respiratory complex I in mitochondrial membrane catalyzes oversized ubiquinones.
An Improved Method to Isolate Mitochondrial Contact Sites.
Mitochondria- and ER-associated actin are required for mitochondrial fusion.
Regulation of glucose and glutamine metabolism to overcome cisplatin resistance in intrahepatic cholangiocarcinoma.
Metastatic pattern of ovarian cancer delineated by tracing the evolution of mitochondrial DNA mutations.
Fatty acid oxidation supports melanoma cell migration through autophagy regulation.
Dasatinib and Trametinib Promote Anti-Tumor Metabolic Activity.
Depleted Hexokinase1 and lack of AMPKα activation favor OXPHOS-dependent energetics in Retinoblastoma tumors.
Mitochondrial DNA is a target of HBV integration.
Loss of the large conductance calcium-activated potassium channel causes an increase in mitochondrial reactive oxygen species in glioblastoma cells.
N-acetylcysteine modulates rotenone-induced mitochondrial Complex I dysfunction in THP-1 cells.
DMT1 differentially regulates mitochondrial complex activities to reduce glutathione loss and mitigate ferroptosis.
FOXA2 controls the anti-oxidant response in FH-deficient cells.
Synthesis and biological evaluation of novel pyrazole amides as potent mitochondrial complex I inhibitors.
Proximity-labeling chemoproteomics defines the subcellular cysteinome and inflammation-responsive mitochondrial redoxome.
Effective magnetic hyperthermia induced by mitochondria-targeted nanoparticles modified with triphenylphosphonium-containing phospholipid polymers.
Oxygen-consumption based quantification of chemogenetic H2O2 production in live human cells.
Regulation of electron transfer in the terminal step of the respiratory chain.
Mitochondria-targeted metformin (mitomet) inhibits lung cancer in cellular models and in mice by enhancing the generation of reactive oxygen species.
Cytosolic malic enzyme and glucose-6-phosphate dehydrogenase modulate redox balance in NSCLC with acquired drug resistance.
HOXC13-driven TIMM13 overexpression promotes osteosarcoma cell growth.
ROR1-STAT3 signaling contributes to ovarian cancer intra-tumor heterogeneity.
NRF1-mediated mitochondrial biogenesis antagonizes innate antiviral immunity.
Metformin sensitizes AML cells to venetoclax through endoplasmic reticulum stress-CHOP pathway.
Luteolin induces apoptosis by impairing mitochondrial function and targeting the intrinsic apoptosis pathway in gastric cancer cells.
SLC25A40 facilitates anticancer drug resistance in human leukemia K562 cells.
Blood-based bioenergetics: a liquid biopsy of mitochondrial dysfunction in disease.

Cell Death Dis. 2023 Jul 06. 14(7): 403

Pyruvate transamination and NAD biosynthesis enable proliferation of succinate dehydrogenase-deficient cells by supporting aerobic glycolysis.

Luisa Ricci, Federico Uchenna Stanley, Tanja Eberhart, Francesco Mainini, David Sumpton, Simone Cardaci.

Succinate dehydrogenase (SDH) is the mitochondrial enzyme converting succinate to fumarate in the tricarboxylic acid (TCA) cycle. SDH acts as a tumor suppressor with germline loss-of-function mutations in its encoding genes predisposing to aggressive familial neuroendocrine and renal cancer syndromes. Lack of SDH activity disrupts the TCA cycle, imposes Warburg-like bioenergetic features, and commits cells to rely on pyruvate carboxylation for anabolic needs. However, the spectrum of metabolic adaptations enabling SDH-deficient tumors to cope with a dysfunctional TCA cycle remains largely unresolved. By using previously characterized Sdhb-deleted kidney mouse cells, here we found that SDH deficiency commits cells to rely on mitochondrial glutamate-pyruvate transaminase (GPT2) activity for proliferation. We showed that GPT2-dependent alanine biosynthesis is crucial to sustain reductive carboxylation of glutamine, thereby circumventing the TCA cycle truncation determined by SDH loss. By driving the reductive TCA cycle anaplerosis, GPT2 activity fuels a metabolic circuit maintaining a favorable intracellular NAD+ pool to enable glycolysis, thus meeting the energetic demands of SDH-deficient cells. As a metabolic syllogism, SDH deficiency confers sensitivity to NAD+ depletion achieved by pharmacological inhibition of nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme of the NAD+ salvage pathway. Beyond identifying an epistatic functional relationship between two metabolic genes in the control of SDH-deficient cell fitness, this study disclosed a metabolic strategy to increase the sensitivity of tumors to interventions limiting NAD availability.

DOI: https://doi.org/10.1038/s41419-023-05927-5
J Cell Sci. 2023 Jul 04. pii: jcs.260822. [Epub ahead of print]

Uncharacterized protein C17orf80: A novel interactor of human mitochondrial nucleoids.

Alisa Potter, Anu Hangas, Steffi Goffart, Martijn A Huynen, Alfredo Cabrera-Orefice, Johannes N Spelbrink.

  Molecular functions of many human proteins remain unstudied, despite the demonstrated association with diseases or pivotal molecular structures, such as mitochondrial DNA (mtDNA). This small genome is crucial for proper functioning of mitochondria, the energy-converting organelles. In mammals, mtDNA is arranged into macromolecular complexes called nucleoids that serve as functional stations for its maintenance and expression. Here, we aimed to explore an uncharacterized protein C17orf80, which was previously detected close to the nucleoid components by proximity-labelling mass spectrometry. To investigate the subcellular localization and function of C17orf80, we took an advantage of immunofluorescence microscopy, interaction proteomics and several biochemical assays. We demonstrate that C17orf80 is a mitochondrial membrane-associated protein that interacts with nucleoids even when mtDNA replication is inhibited. In addition, we show that C17orf80 is not essential for mtDNA maintenance and mitochondrial gene expression in cultured human cells. These results provide a basis for uncovering the molecular function of C17orf80 and the nature of its association with nucleoids, possibly leading to new insights about mtDNA and its expression.

Keywords:  2'; 3'-dideoxycytidine; C17orf80; Mitochondria; Mitochondrial nucleoid; mtDNA

DOI:  https://doi.org/10.1242/jcs.260822
Nat Cell Biol. 2023 Jul 03.

Arf1 coordinates fatty acid metabolism and mitochondrial homeostasis.

Ludovic Enkler, Viktoria Szentgyörgyi, Mirjam Pennauer, Cristina Prescianotto-Baschong, Isabelle Riezman, Aneta Wiesyk, Reut Ester Avraham, Martin Spiess, Einat Zalckvar, Roza Kucharczyk, Howard Riezman, Anne Spang.

Lipid mobilization through fatty acid β-oxidation is a central process essential for energy production during nutrient shortage. In yeast, this catabolic process starts in the peroxisome from where β-oxidation products enter mitochondria and fuel the tricarboxylic acid cycle. Little is known about the physical and metabolic cooperation between these organelles. Here we found that expression of fatty acid transporters and of the rate-limiting enzyme involved in β-oxidation is decreased in cells expressing a hyperactive mutant of the small GTPase Arf1, leading to an accumulation of fatty acids in lipid droplets. Consequently, mitochondria became fragmented and ATP synthesis decreased. Genetic and pharmacological depletion of fatty acids phenocopied the arf1 mutant mitochondrial phenotype. Although β-oxidation occurs in both mitochondria and peroxisomes in mammals, Arf1's role in fatty acid metabolism is conserved. Together, our results indicate that Arf1 integrates metabolism into energy production by regulating fatty acid storage and utilization, and presumably organelle contact sites.

DOI: https://doi.org/10.1038/s41556-023-01180-2
Sci Rep. 2023 07 04. 13(1): 10822

Viability of HepG2 and MCF-7 cells is not correlated with mitochondrial bioenergetics.

Judit Doczi, Noemi Karnok, David Bui, Victoria Azarov, Gergely Pallag, Sara Nazarian, Bence Czumbel, Thomas N Seyfried, Christos Chinopoulos.

Alterations in metabolism are a hallmark of cancer. It is unclear if oxidative phosphorylation (OXPHOS) is necessary for tumour cell survival. In this study, we investigated the effects of severe hypoxia, site-specific inhibition of respiratory chain (RC) components, and uncouplers on necrotic and apoptotic markers in 2D-cultured HepG2 and MCF-7 tumour cells. Comparable respiratory complex activities were observed in both cell lines. However, HepG2 cells exhibited significantly higher oxygen consumption rates (OCR) and respiratory capacity than MCF-7 cells. Significant non-mitochondrial OCR was observed in MCF-7 cells, which was insensitive to acute combined inhibition of complexes I and III. Pre-treatment of either cell line with RC inhibitors for 24-72 h resulted in the complete abolition of respective complex activities and OCRs. This was accompanied by a time-dependent decrease in citrate synthase activity, suggesting mitophagy. High-content automated microscopy recordings revealed that the viability of HepG2 cells was mostly unaffected by any pharmacological treatment or severe hypoxia. In contrast, the viability of MCF-7 cells was strongly affected by inhibition of complex IV (CIV) or complex V (CV), severe hypoxia, and uncoupling. However, it was only moderately affected by inhibition of complexes I, II, and III. Cell death in MCF-7 cells induced by inhibition of complexes II, III, and IV was partially abrogated by aspartate. These findings indicate that OXPHOS activity and viability are not correlated in these cell lines, suggesting that the connection between OXPHOS and cancer cell survival is dependent on the specific cell type and conditions.

DOI: https://doi.org/10.1038/s41598-023-37677-x
Cell Death Differ. 2023 Jul 07.

SLC25A51 promotes tumor growth through sustaining mitochondria acetylation homeostasis and proline biogenesis.

Yutong Li, Juntao Bie, Long Zhao, Chen Song, Tianzhuo Zhang, Meiting Li, Changjiang Yang, Jianyuan Luo.

Solute carrier family 25 member 51 (SLC25A51) was recently identified as the mammalian mitochondrial NAD+ transporter essential for mitochondria functions. However, the role of SLC25A51 in human disease, such as cancer, remains undefined. Here, we report that SLC25A51 is upregulated in multiple cancers, which promotes cancer cells proliferation. Loss of SLC25A51 elevates the mitochondrial proteins acetylation levels due to SIRT3 dysfunctions, leading to the impairment of P5CS enzymatic activity, which is the key enzyme in proline biogenesis, and the reduction in proline contents. Notably, we find fludarabine phosphate, an FDA-approved drug, is able to bind with and inhibit SLC25A51 functions, causing mitochondrial NAD+ decrease and proteins hyperacetylation, which could further synergize with aspirin to reinforce the anti-tumor efficacy. Our study reveals that SLC25A51 is an attractive anti-cancer target, and provides a novel drug combination of fludarabine phosphate with aspirin as a potential cancer therapy strategy.

DOI: https://doi.org/10.1038/s41418-023-01185-2
bioRxiv. 2023 Jun 04. pii: 2023.06.03.543558. [Epub ahead of print]

CISD3 is required for Complex I function, mitochondrial integrity, and skeletal muscle maintenance.

Henri-Baptiste Marjault, Ola Karmi, Linda Rowland, Thi Thao Nguyen, DeAna Grant, Camila Manrique-Acevedo, Rachel Nechushtai, Ron Mittler.

Mitochondria play a central role in muscle metabolism and function. In skeletal muscles, a unique family of iron-sulfur proteins, termed CISD proteins, support mitochondrial function. The abundance of these proteins declines with aging leading to muscle degeneration. Although the function of the outer mitochondrial proteins CISD1 and CISD2 has been defined, the role of the inner mitochondrial protein CISD3, is currently unknown. Here we show that CISD3 deficiency in mice results in muscle atrophy that shares proteomic features with Duchenne Muscular Dystrophy. We further reveal that CISD3 deficiency impairs the function and structure of skeletal muscle mitochondria, and that CISD3 interacts with, and donates its clusters to, Complex I respiratory chain subunit NDUFV2. These findings reveal that CISD3 is important for supporting the biogenesis and function of Complex I, essential for muscle maintenance and function. Interventions that target CISD3 could therefore impact muscle degeneration syndromes, aging, and related conditions.

DOI: https://doi.org/10.1101/2023.06.03.543558
J Biol Chem. 2023 Jun 30. pii: S0021-9258(23)02029-X. [Epub ahead of print] 105001

Respiratory complex I in mitochondrial membrane catalyzes oversized ubiquinones.

Ryo Ikunishi, Ryohei Otani, Takahiro Masuya, Kyoko Shinzawa-Itoh, Tomoo Shiba, Masatoshi Murai, Hideto Miyoshi.

  NADH-ubiquinone (UQ) oxidoreductase (complex I) couples electron transfer from NADH to UQ with proton translocation in its membrane part. The UQ reduction step is key to triggering proton translocation. Structural studies have identified a long, narrow, tunnel-like cavity within complex I, through which UQ may access a deep reaction site. To elucidate the physiological relevance of this UQ-accessing tunnel, we previously investigated whether a series of oversized UQs (OS-UQs), whose tail moiety is too large to enter and transit the narrow tunnel, can be catalytically reduced by complex I using the native enzyme in bovine heart submitochondrial particles (SMPs) and the isolated enzyme reconstituted into liposomes. Nevertheless, the physiological relevance remained unclear because some amphiphilic OS-UQs were reduced in SMPs but not in proteoliposomes, and investigation of extremely hydrophobic OS-UQs was not possible in SMPs. To uniformly assess the electron transfer activities of all OS-UQs with the native complex I, here we present a new assay system using SMPs, which were fused with liposomes incorporating OS-UQ and supplemented with a parasitic quinol oxidase to recycle reduced OS-UQ. In this system, all OS-UQs tested were reduced by the native enzyme, and the reduction was coupled with proton translocation. This finding does not support the canonical tunnel model. We propose that the UQ reaction cavity is flexibly open in the native enzyme to allow OS-UQs to access the reaction site, but their access is obstructed in the isolated enzyme as the cavity is altered by detergent-solubilizing from the mitochondrial membrane.

Keywords:  bioenergetics; chemical biology; complex I; respiratory enzymes; ubiquinone

DOI:  https://doi.org/10.1016/j.jbc.2023.105001
J Vis Exp. 2023 06 16.

An Improved Method to Isolate Mitochondrial Contact Sites.

Siavash Khosravi, Johanna Frickel, Max E Harner.

Mitochondria are present in virtually all eukaryotic cells and perform essential functions that go far beyond energy production, for instance, the synthesis of iron-sulfur clusters, lipids, or proteins, Ca2+ buffering, and the induction of apoptosis. Likewise, mitochondrial dysfunction results in severe human diseases such as cancer, diabetes, and neurodegeneration. In order to perform these functions, mitochondria have to communicate with the rest of the cell across their envelope, which consists of two membranes. Therefore, these two membranes have to interact constantly. Proteinaceous contact sites between the mitochondrial inner and outer membranes are essential in this respect. So far, several contact sites have been identified. In the method described here, Saccharomyces cerevisiae mitochondria are used to isolate contact sites and, thus, identify candidates that qualify for contact site proteins. We used this method to identify the mitochondrial contact site and cristae organizing system (MICOS) complex, one of the major contact site-forming complexes in the mitochondrial inner membrane, which is conserved from yeast to humans. Recently, we further improved this method to identify a novel contact site consisting of Cqd1 and the Por1-Om14 complex.

DOI: https://doi.org/10.3791/65444
bioRxiv. 2023 Jun 13. pii: 2023.06.13.544768. [Epub ahead of print]

Mitochondria- and ER-associated actin are required for mitochondrial fusion.

Priya Gatti, Cara Schiavon, Uri Manor, Marc Germain.

Mitochondria play a crucial role in the regulation of cellular metabolism and signalling. Mitochondrial activity is modulated by the processes of mitochondrial fission and fusion, which are required to properly balance respiratory and metabolic functions, transfer material between mitochondria, and remove damaged or defective mitochondria. Mitochondrial fission occurs at sites of contact between the endoplasmic reticulum (ER) and mitochondria, and is dependent on the formation of mitochondria- and ER-associated actin filaments that drive the recruitment and activation of the fission GTPase DRP1. On the other hand, the role of mitochondria- and ER-associated actin filaments in mitochondrial fusion remains unknown. Here we show that preventing the formation of actin filaments on either mitochondria or the ER using organelle-targeted Disassembly-promoting, encodable Actin tools (DeActs) blocks both mitochondrial fission and fusion. We show that fusion but not fission is dependent on Arp2/3, and both fission and fusion are dependent on INF2 formin-dependent actin polymerization. Together, our work introduces a novel method for perturbing organelle-associated actin filaments, and demonstrates a previously unknown role for mitochondria- and ER-associated actin in mitochondrial fusion.

DOI: https://doi.org/10.1101/2023.06.13.544768
BMB Rep. 2023 Jul 04. pii: 5877. [Epub ahead of print]

Regulation of glucose and glutamine metabolism to overcome cisplatin resistance in intrahepatic cholangiocarcinoma.

So Mi Yang, Jueun Kim, Ji-Yeon Lee, Jung-Shin Lee, Ji Min Lee.

Intrahepatic cholangiocarcinoma (ICC) is one of the bile duct cancers and a rare malignant tumor with a poor prognosis owing to a lack of early diagnosis and resistance to conventional chemotherapy. A combination of gemcitabine and cisplatin is a treatment approach typically being attempted for the first line. However, its underlying mechanism of resistance to chemotherapy is poorly understood. We addressed this by studying the dynamics in the human ICC SCK cell line. Here, we report that the regulation of glucose and glutamine metabolism is a key factor in overcoming cisplatin resistance of SCK. Through RNA sequencing analysis, we discovered that the cell cycle-related gene set exhibits a high enrichment score in cisplatin-resistant SCK (SCK-R) cells rather than parental SCK (SCK WT) cells. Cell cycle progression correlates with increased nutrient requirement and cancer proliferation or metastasis. Commonly, cancer cells are dependent upon glucose and glutamine availability for survival and proliferation. Indeed, we observed increased expression of GLUT (glucose transporter), ASCT2 (glutamine transporter), and cancer progression markers in SCK-R cells. Thus, we inhibited enhanced metabolic reprogramming in SCK-R cells through nutrient starvation. Especially under glucose starvation, SCK-R cells are sensitized to cisplatin. Moreover, glutaminase-1 (GLS1), which is a mitochondrial enzyme involved in tumorigenesis and progression in cancer cells was upregulated in SCK-R cells. Targeting GLS1 with the GLS1 inhibitor CB-839 (telaglenastat) effectively reduced the expression of cancer progression markers. Taken together, our study suggests that a combination of GLUT inhibition, which mimics glucose starvation, and GLS1 inhibition could be a therapeutic strategy to increase the chemosensitivity of ICC.
Exp Mol Med. 2023 Jul 03.

Metastatic pattern of ovarian cancer delineated by tracing the evolution of mitochondrial DNA mutations.

Zhiyang Xu, Kaixiang Zhou, Zhenni Wang, Yang Liu, Xingguo Wang, Tian Gao, Fanfan Xie, Qing Yuan, Xiwen Gu, Shujuan Liu, Jinliang Xing.

Ovarian cancer (OC) is the most lethal gynecologic tumor and is characterized by a high rate of metastasis. Challenges in accurately delineating the metastatic pattern have greatly restricted the improvement of treatment in OC patients. An increasing number of studies have leveraged mitochondrial DNA (mtDNA) mutations as efficient lineage-tracing markers of tumor clonality. We applied multiregional sampling and high-depth mtDNA sequencing to determine the metastatic patterns in advanced-stage OC patients. Somatic mtDNA mutations were profiled from a total of 195 primary and 200 metastatic tumor tissue samples from 35 OC patients. Our results revealed remarkable sample-level and patient-level heterogeneity. In addition, distinct mtDNA mutational patterns were observed between primary and metastatic OC tissues. Further analysis identified the different mutational spectra between shared and private mutations among primary and metastatic OC tissues. Analysis of the clonality index calculated based on mtDNA mutations supported a monoclonal tumor origin in 14 of 16 patients with bilateral ovarian cancers. Notably, mtDNA-based spatial phylogenetic analysis revealed distinct patterns of OC metastasis, in which a linear metastatic pattern exhibited a low degree of mtDNA mutation heterogeneity and a short evolutionary distance, whereas a parallel metastatic pattern showed the opposite trend. Moreover, a mtDNA-based tumor evolutionary score (MTEs) related to different metastatic patterns was defined. Our data showed that patients with different MTESs responded differently to combined debulking surgery and chemotherapy. Finally, we observed that tumor-derived mtDNA mutations were more likely to be detected in ascitic fluid than in plasma samples. Our study presents an explicit view of the OC metastatic pattern, which sheds light on efficient treatment for OC patients.

DOI: https://doi.org/10.1038/s12276-023-01011-2
Biochem Biophys Res Commun. 2023 Jun 29. pii: S0006-291X(23)00845-8. [Epub ahead of print]674 124-132

Fatty acid oxidation supports melanoma cell migration through autophagy regulation.

Seungmin Shin, Seungyeon Yang, Minjoong Kim, Eun Kyung Lee, Soojung Claire Hur, Seung Min Jeong.

Metastasis is one of the most malignant characteristics of cancer cells, in which metabolic reprogramming is crucial for promoting and sustaining multi-steps of metastasis, including invasion, migration and infiltration. Recently, it has been shown that melanoma cells undergo a metabolic switching toward the upregulation of fatty acid oxidation (FAO) during metastasis. However, the underlying mechanisms by which FAO contributes to metastasis of melanoma cells remain obscure. Here, we report that FAO contributes to melanoma cell migration and invasion by regulating the formation of autophagosomes. Pharmacological or genetic inhibition of FAO impairs migration of melanoma cells, which seems not to be linked to energy production or redox homeostasis. Importantly, we reveal that acetyl-CoA production by FAO contributes to melanoma cell migration through autophagy regulation. Mechanistically, FAO inhibition results in increased autophagosome formation, which suppresses migration and invasion properties of melanoma cells. Our results underscore the crucial role of FAO in melanoma cell migration and support the potential therapeutic relevance of modulating cellular acetyl-CoA levels to inhibit cancer metastasis.

DOI: https://doi.org/10.1016/j.bbrc.2023.06.090
Cells. 2023 May 12. pii: 1374. [Epub ahead of print]12(10):

Dasatinib and Trametinib Promote Anti-Tumor Metabolic Activity.

Eric L Bolf, Thomas C Beadnell, Madison M Rose, Angelo D'Alessandro, Travis Nemkov, Kirk C Hansen, Rebecca E Schweppe.

  Thyroid cancer is the most common endocrine neoplasm, and despite its overall high survival rate, patients with metastatic disease or tumors that resist radioactive iodine experience a significantly worse prognosis. Helping these patients requires a better understanding of how therapeutics alter cellular function. Here, we describe the change in metabolite profiles after treating thyroid cancer cells with the kinase inhibitors dasatinib and trametinib. We reveal alterations to glycolysis, the TCA cycle, and amino acid levels. We also highlight how these drugs promote short-term accumulation of the tumor-suppressive metabolite 2-oxoglutarate, and demonstrate that it reduces the viability of thyroid cancer cells in vitro. These results show that kinase inhibition profoundly alters the metabolome of cancer cells and highlight the need to better understand how therapeutics reprogram metabolic processes, and ultimately, cancer cell behavior.

Keywords:  MAPK; Src; combination; dasatinib; metabolism; metabolomics; thyroid cancer; trametinib

DOI:  https://doi.org/10.3390/cells12101374
Transl Res. 2023 Jul 05. pii: S1931-5244(23)00108-1. [Epub ahead of print]

Depleted Hexokinase1 and lack of AMPKα activation favor OXPHOS-dependent energetics in Retinoblastoma tumors.

Vishnu Suresh Babu, Ashwin Mallipatna, Gagan Dudeja, Rohit Shetty, Archana Padmanabhan Nair, Sai Bo Bo Tun, Candice Ee Hua Ho, Shyam S Chaurasia, Shomi S Bhattacharya, Navin Kumar Verma, Rajamani Lakshminarayanan, Nilanjan Guha, Stephane Heymans, Veluchamy Amutha Barathi, Arkasubhra Ghosh.

  Lack of retinoblastoma protein (Rb) causes aggressive intraocular retinal tumors in children. Recently, Rb tumors have been shown to have a distinctly altered metabolic phenotype, such as reduced expression of glycolytic pathway proteins alongside altered pyruvate and fatty acid levels. In this study, we demonstrate that loss of Hexokinase 1(HK1) in tumor cells rewires their metabolism allowing enhanced oxidative phosphorylation-dependent energy production. We show that rescuing HK1 or RB1 in these retinoblastoma cells reduced cancer hallmarks such as proliferation, invasion, spheroid formation and increased their sensitivity to chemotherapy drugs. Induction of HK1 was accompanied by a metabolic shift of the cells to glycolysis and a reduction in mitochondrial mass. Cytoplasmic HK1 bound Liver Kinase B1 (LKB1) and phosphorylated AMP-activated kinase-α (AMPKα Thr172), thereby reducing mitochondria-dependent energy production. We validated these findings in tumor samples from Rb patients compared to age-matched healthy retinae. HK1 or RB1 expression in Rb-/- cells led to a reduction in their respiratory capacity and glycolytic proton flux. HK1 overexpression reduced tumor burden in an intraocular tumor xenograft model. AMPKα activation by AICAR also enhanced the tumoricidal effects of the chemotherapeutic drug topotecan in vivo. Therefore, enhancing HK1 or AMPKα activity can reprogram cancer metabolism and sensitize retinoblastoma tumors to lower doses of existing treatments, a potential therapeutic modality for retinoblastoma.

Keywords:  AMPKα; Hexokinase-1; Retinoblastoma; cancer; glycolysis; oxidative phosphorylation

DOI:  https://doi.org/10.1016/j.trsl.2023.07.001
Commun Biol. 2023 07 03. 6(1): 684

Mitochondrial DNA is a target of HBV integration.

Domenico Giosa, Daniele Lombardo, Cristina Musolino, Valeria Chines, Giuseppina Raffa, Francesca Casuscelli di Tocco, Deborah D'Aliberti, Giuseppe Caminiti, Carlo Saitta, Angela Alibrandi, Riccardo Aiese Cigliano, Orazio Romeo, Giuseppe Navarra, Giovanni Raimondo, Teresa Pollicino.

Hepatitis B virus (HBV) may integrate into the genome of infected cells and contribute to hepatocarcinogenesis. However, the role of HBV integration in hepatocellular carcinoma (HCC) development remains unclear. In this study, we apply a high-throughput HBV integration sequencing approach that allows sensitive identification of HBV integration sites and enumeration of integration clones. We identify 3339 HBV integration sites in paired tumour and non-tumour tissue samples from 7 patients with HCC. We detect 2107 clonally expanded integrations (1817 in tumour and 290 in non-tumour tissues), and a significant enrichment of clonal HBV integrations in mitochondrial DNA (mtDNA) preferentially occurring in the oxidative phosphorylation genes (OXPHOS) and D-loop region. We also find that HBV RNA sequences are imported into the mitochondria of hepatoma cells with the involvement of polynucleotide phosphorylase (PNPASE), and that HBV RNA might have a role in the process of HBV integration into mtDNA. Our results suggest a potential mechanism by which HBV integration may contribute to HCC development.

DOI: https://doi.org/10.1038/s42003-023-05017-4
Pflugers Arch. 2023 Jul 04.

Loss of the large conductance calcium-activated potassium channel causes an increase in mitochondrial reactive oxygen species in glioblastoma cells.

Bogusz Kulawiak, Monika Żochowska, Piotr Bednarczyk, Andrzej Galuba, David A Stroud, Adam Szewczyk.

  Mitochondrial potassium (mitoK) channels play an important role in cellular physiology. These channels are expressed in healthy tissues and cancer cells. Activation of mitoK channels can protect neurons and cardiac tissue against injury induced by ischemia-reperfusion. In cancer cells, inhibition of mitoK channels leads to an increase in mitochondrial reactive oxygen species, which leads to cell death. In glioma cell activity of the mitochondrial, large conductance calcium-activated potassium (mitoBKCa) channel is regulated by the mitochondrial respiratory chain. In our project, we used CRISPR/Cas9 technology in human glioblastoma U-87 MG cells to generate knockout cell lines lacking the α-subunit of the BKCa channel encoded by the KCNMA1 gene, which also encodes cardiac mitoBKCa. Mitochondrial patch-clamp experiments showed the absence of an active mitoBKCa channel in knockout cells. Additionally, the absence of this channel resulted in increased levels of mitochondrial reactive oxygen species. However, analysis of the mitochondrial respiration rate did not show significant changes in oxygen consumption in the cell lines lacking BKCa channels compared to the wild-type U-87 MG cell line. These observations were reflected in the expression levels of selected mitochondrial genes, organization of the respiratory chain, and mitochondrial morphology, which did not show significant differences between the analyzed cell lines. In conclusion, we show that in U-87 MG cells, the pore-forming subunit of the mitoBKCa channel is encoded by the KCNMA1 gene. Additionally, the presence of this channel is important for the regulation of reactive oxygen species levels in mitochondria.

Keywords:  Glioblastoma; Mitochondria; Mitochondrial potassium channels; Mitochondrial respiration; Reactive oxygen species

DOI:  https://doi.org/10.1007/s00424-023-02833-9
Mitochondrion. 2023 Jul 05. pii: S1567-7249(23)00056-9. [Epub ahead of print]

N-acetylcysteine modulates rotenone-induced mitochondrial Complex I dysfunction in THP-1 cells.

Winston Tse-Hou Kwok, Haejin Angela Kwak, Ana Cristina Andreazza.

  Mitochondrial Complex I dysfunction and oxidative stress have been part of the pathophysiology of several diseases ranging from mitochondrial disease to chronic diseases such as diabetes, mood disorders and Parkinson's Disease. Nonetheless, to investigate the potential of mitochondria-targeted therapeutic strategies for these conditions, there is a need further our understanding on how cells respond and adapt in the presence of Complex I dysfunction. In this study, we used low doses of rotenone, a classical inhibitor of mitochondrial complex I, to mimic peripheral mitochondrial dysfunction in THP-1 cells, a human monocytic cell line, and explored the effects of N-acetylcysteine on preventing this rotenone-induced mitochondrial dysfunction. Our results show that in THP-1 cells, rotenone exposure led to increases in mitochondrial superoxide, levels of cell-free mitochondrial DNA, and protein levels of the NDUFS7 subunit. N-acetylcysteine (NAC) pre-treatment ameliorated the rotenone-induced increase of cell-free mitochondrial DNA and NDUFS7 protein levels, but not mitochondrial superoxide. Furthermore, rotenone exposure did not affect protein levels of the NDUFV1 subunit but induced NDUFV1 glutathionylation. In summary, NAC may help to mitigate the effects of rotenone on Complex I and preserve the normal function of mitochondria in THP-1 cells.

Keywords:  Cell model; Complex I; Mitochondrial; N-acetylcysteine; Reactive oxygen species; Rotenone

DOI:  https://doi.org/10.1016/j.mito.2023.07.001
Free Radic Biol Med. 2023 Jul 05. pii: S0891-5849(23)00511-7. [Epub ahead of print]

DMT1 differentially regulates mitochondrial complex activities to reduce glutathione loss and mitigate ferroptosis.

Qing Tan, Xiaoqian Zhang, Shuxiang Li, Wenbin Liu, Jiaqi Yan, Siqi Wang, Feng Cui, Dan Li, Jun Li.

  Mitochondria are vital for energy production and Redox homeostasis, yet knowledge of relevant mechanisms remains limited. Here, through a genome-wide CRISPR-Cas9 knockout screening, we have identified DMT1 as a major regulator of mitochondria membrane potential. Our findings demonstrate that DMT1 deficiency increased the activity of mitochondrial complex I and reduced that of complex III. Enhanced complex I activity leads to increased NAD+ production, which activates IDH2 by promoting its deacetylation via SIRT3, This results in higher levels of NADPH and GSH, which improve antioxidant capacity during Erastin-induced ferroptosis. Meanwhile, loss of complex III activity impairs mitochondrial biogenesis and promotes mitophagy, contributing to suppression of ferroptosis. Thus, DMT1 differentially regulates activities of mitochondrial complex I and III to cooperatly suppress Erastin-induced ferroptosis. Furthermore, NMN, an alternative method of increasing mitochondrial NAD+, exhibits similar protective effects against ferroptosis by boosting GSH in a manner similar to DMT1 deficiency, shedding a light on potential therapeutic strategy for ferroptosis-related pathologies.

Keywords:  DMT1; Ferroptosis; Mitochondria NAD(+); REDOX homeostasis

DOI:  https://doi.org/10.1016/j.freeradbiomed.2023.06.023
Cell Rep. 2023 Jul 04. pii: S2211-1247(23)00762-3. [Epub ahead of print]42(7): 112751

FOXA2 controls the anti-oxidant response in FH-deficient cells.

Connor Rogerson, Marco Sciacovelli, Lucas A Maddalena, Andromachi Pouikli, Marc Segarra-Mondejar, Lorea Valcarcel-Jimenez, Christina Schmidt, Ming Yang, Elena Ivanova, Joshua Kent, Ariane Mora, Danya Cheeseman, Jason S Carroll, Gavin Kelsey, Christian Frezza.

  Hereditary leiomyomatosis and renal cell cancer (HLRCC) is a cancer syndrome caused by inactivating germline mutations in fumarate hydratase (FH) and subsequent accumulation of fumarate. Fumarate accumulation leads to profound epigenetic changes and the activation of an anti-oxidant response via nuclear translocation of the transcription factor NRF2. The extent to which chromatin remodeling shapes this anti-oxidant response is currently unknown. Here, we explored the effects of FH loss on the chromatin landscape to identify transcription factor networks involved in the remodeled chromatin landscape of FH-deficient cells. We identify FOXA2 as a key transcription factor that regulates anti-oxidant response genes and subsequent metabolic rewiring cooperating without direct interaction with the anti-oxidant regulator NRF2. The identification of FOXA2 as an anti-oxidant regulator provides additional insights into the molecular mechanisms behind cell responses to fumarate accumulation and potentially provides further avenues for therapeutic intervention for HLRCC.

Keywords:  CP: Cancer; CP: Molecular biology; FOXA2; NRF2; anti-oxidant response; fumarate hydratase

DOI:  https://doi.org/10.1016/j.celrep.2023.112751
Eur J Med Chem. 2023 Jun 17. pii: S0223-5234(23)00542-1. [Epub ahead of print]258 115576

Synthesis and biological evaluation of novel pyrazole amides as potent mitochondrial complex I inhibitors.

Yang Zhou, Jiao Zou, Xi Zhong, Jing Xu, Kun Gou, Xia Zhou, Yue Zhou, Xinyu Yang, Xinqi Guan, Yu Zhang, Donglin Chen, Xiaobo Cen, Youfu Luo, Yinglan Zhao.

  Targeting mitochondrial complex I (CI) is emerging as an attractive anticancer strategy, and CI inhibitor IACS-010759 has achieved breakthrough success. However, the narrow therapeutic index of IACS-010759 seriously hinders its further application. In this study, a series of novel pyrazole amides were designed and optimized based on IACS-010759, and their potential CI inhibitory effects were biologically evaluated. Among them, the maximum tolerated dose (MTD) values of SCAL-255 (compound 5q) and SCAL-266 (compound 6f) were 68 mg/kg, which was nearly 10 times that of IACS-010759 (6 mg/kg), showing good safety. In addition, SCAL-255 and SCAL-266 significantly inhibited the proliferation of HCT116 and KG-1 cells in vitro and exerted satisfactory inhibitory activity against KG-1 cells in vivo. These results suggested that the optimized compounds might serve as promising CI inhibitors against oxidative phosphorylation (OXPHOS)-dependent cancer, which merits further study.

Keywords:  Antitumor; Mitochondrial complex I; Pyrazole amides

DOI:  https://doi.org/10.1016/j.ejmech.2023.115576
Cell Chem Biol. 2023 Jun 22. pii: S2451-9456(23)00186-1. [Epub ahead of print]

Proximity-labeling chemoproteomics defines the subcellular cysteinome and inflammation-responsive mitochondrial redoxome.

Tianyang Yan, Ashley R Julio, Miranda Villanueva, Anthony E Jones, Andréa B Ball, Lisa M Boatner, Alexandra C Turmon, Kaitlyn B Nguyễn, Stephanie L Yen, Heta S Desai, Ajit S Divakaruni, Keriann M Backus.

  Proteinaceous cysteines function as essential sensors of cellular redox state. Consequently, defining the cysteine redoxome is a key challenge for functional proteomic studies. While proteome-wide inventories of cysteine oxidation state are readily achieved using established, widely adopted proteomic methods such as OxICAT, Biotin Switch, and SP3-Rox, these methods typically assay bulk proteomes and therefore fail to capture protein localization-dependent oxidative modifications. Here we establish the local cysteine capture (Cys-LoC) and local cysteine oxidation (Cys-LOx) methods, which together yield compartment-specific cysteine capture and quantitation of cysteine oxidation state. Benchmarking of the Cys-LoC method across a panel of subcellular compartments revealed more than 3,500 cysteines not previously captured by whole-cell proteomic analysis. Application of the Cys-LOx method to LPS-stimulated immortalized murine bone marrow-derived macrophages (iBMDM), revealed previously unidentified, mitochondrially localized cysteine oxidative modifications upon pro-inflammatory activation, including those associated with oxidative mitochondrial metabolism.

Keywords:  TurboID; chemoproteomics; cysteine; cysteine oxidation; lipopolysaccharide; macrophages; mitochondria; proximity labeling

DOI:  https://doi.org/10.1016/j.chembiol.2023.06.008
Cancer Sci. 2023 Jul 06.

Effective magnetic hyperthermia induced by mitochondria-targeted nanoparticles modified with triphenylphosphonium-containing phospholipid polymers.

Masahiro Kaneko, Hiroto Yamazaki, Takahiro Ono, Masanobu Horie, Akira Ito.

  Magnetic hyperthermia (MHT) is a promising cancer treatment because tumor tissue can be specifically damaged by utilizing the heat generated by nano-heaters such as magnetite nanoparticles (MNPs) under an alternating magnetic field. MNPs are taken up by cancer cells, enabling intracellular MHT. Subcellular localization of MNPs can affect the efficiency of intracellular MHT. In this study, we attempted to improve the therapeutic efficacy of MHT by using mitochondria-targeting MNPs. Mitochondria-targeting MNPs were prepared by the modification of carboxyl phospholipid polymers containing triphenylphosphonium (TPP) moieties that accumulate in mitochondria. The mitochondrial localization of polymer-modified MNPs was supported by transmission electron microscopy observations of murine colon cancer CT26 cells treated with polymer-modified MNPs. In vitro and in vivo MHT using polymer-modified MNPs revealed that the therapeutic effects were enhanced by introducing TPP. Our results indicate the validity of mitochondria targeting in enhancing the therapeutic outcome of MHT. These findings will pave the way for developing a new strategy for the surface design of MNPs and therapeutic strategies for MHT.

Keywords:  cancer therapy; hyperthermia; magnetic nanoparticles; mitochondria; phospholipid polymers

DOI:  https://doi.org/10.1111/cas.15895
Free Radic Biol Med. 2023 Jun 29. pii: S0891-5849(23)00517-8. [Epub ahead of print]206 134-142

Oxygen-consumption based quantification of chemogenetic H2O2 production in live human cells.

Wytze T F den Toom, Daan M K van Soest, Paulien E Polderman, Miranda H van Triest, Lucas J M Bruurs, Sasha De Henau, Boudewijn M T Burgering, Tobias B Dansen.

  Reactive Oxygen Species (ROS) in the form of H2O2 can act both as physiological signaling molecules as well as damaging agents, depending on their concentration and localization. The downstream biological effects of H2O2 were often studied making use of exogenously added H2O2, generally as a bolus and at supraphysiological levels. But this does not mimic the continuous, low levels of intracellular H2O2 production by for instance mitochondrial respiration. The enzyme d-Amino Acid Oxidase (DAAO) catalyzes H2O2 formation using d-amino acids, which are absent from culture media, as a substrate. Ectopic expression of DAAO has recently been used in several studies to produce inducible and titratable intracellular H2O2. However, a method to directly quantify the amount of H2O2 produced by DAAO has been lacking, making it difficult to assess whether observed phenotypes are the result of physiological or artificially high levels of H2O2. Here we describe a simple assay to directly quantify DAAO activity by measuring the oxygen consumed during H2O2 production. The oxygen consumption rate (OCR) of DAAO can directly be compared to the basal mitochondrial respiration in the same assay, to estimate whether the ensuing level of H2O2 production is within the range of physiological mitochondrial ROS production. In the tested monoclonal RPE1-hTERT cells, addition of 5 mM d-Ala to the culture media amounts to a DAAO-dependent OCR that surpasses ∼5% of the OCR that stems from basal mitochondrial respiration and hence produces supra-physiological levels of H2O2. We show that the assay can also be used to select clones that express differentially localized DAAO with the same absolute level of H2O2 production to be able to discriminate the effects of H2O2 production at different subcellular locations from differences in total oxidative burden. This method therefore greatly improves the interpretation and applicability of DAAO-based models, thereby moving the redox biology field forward.

Keywords:  H(2)O(2); HyPer7; Oxygen consumption rate; d-amino acid oxidase

DOI:  https://doi.org/10.1016/j.freeradbiomed.2023.06.030
Biochem Soc Trans. 2023 Jul 06. pii: BST20221449. [Epub ahead of print]

Regulation of electron transfer in the terminal step of the respiratory chain.

Wataru Sato, Koichiro Ishimori.

  In mitochondria, electrons are transferred along a series of enzymes and electron carriers that are referred to as the respiratory chain, leading to the synthesis of cellular ATP. The series of the interprotein electron transfer (ET) reactions is terminated by the reduction in molecular oxygen at Complex IV, cytochrome c oxidase (CcO) that is coupled with the proton pumping from the matrix to the inner membrane space. Unlike the ET reactions from Complex I to Complex III, the ET reaction to CcO, mediated by cytochrome c (Cyt c), is quite specific in that it is irreversible with suppressed electron leakage, which characterizes the ET reactions in the respiratory chain and is thought to play a key role in the regulation of mitochondrial respiration. In this review, we summarize the recent findings regarding the molecular mechanism of the ET reaction from Cyt c to CcO in terms of specific interaction between two proteins, a molecular breakwater, and the effects of the conformational fluctuation on the ET reaction, conformational gating. Both of these are essential factors, not only in the ET reaction from Cyt c to CcO, but also in the interprotein ET reactions in general. We also discuss the significance of a supercomplex in the terminal ET reaction, which provides information on the regulatory factors of the ET reactions that are specific to the mitochondrial respiratory chain.

Keywords:  breakwater; complex IV; conformational gating; cytochrome c; electron transfer; supercomplex

DOI:  https://doi.org/10.1042/BST20221449
Mol Carcinog. 2023 Jul 04.

Mitochondria-targeted metformin (mitomet) inhibits lung cancer in cellular models and in mice by enhancing the generation of reactive oxygen species.

Mohammad Shameem, Alireza Jian Bagherpoor, Ali Nakhi, Peter Dosa, Gunda Georg, Fekadu Kassie.

  Lung cancer is the leading cause of cancer-related mortality in the United States. Although some epidemiological studies have shown an inverse relationship between the use of metformin, a widely used antidiabetic drug, and the incidence of lung cancer, the real benefits of the drug are unclear as the efficacy is low and the outcomes are quite heterogeneous. To develop a more potent form of metformin, we synthesized mitochondria-targeted metformin (mitomet) and tested its efficacy in in vitro and in vivo models of lung cancer. Mitomet was cytotoxic to transformed bronchial cells and several non-small cell lung cancer (NSCLC) cell lines but relatively safe to normal bronchial cells, and these effects were mediated mainly via induction of mitochondrial reactive oxygen species. Studies using isogenic A549 cells showed that mitomet was selectively toxic to those cells deficient in the tumor suppressor gene LKB1, which is widely mutated in NSCLC. Mitomet also significantly reduced the multiplicity and size of lung tumors induced by a tobacco smoke carcinogen in mice. Overall, our findings showed that mitomet, which was about 1000 and 100 times more potent than metformin, in killing NSCLC cells and reducing the multiplicity and size of lung tumors in mice, respectively, is a promising candidate for the chemoprevention and treatment of lung cancer, in particular against LKB1-deficient lung cancers which are known to be highly aggressive.

Keywords:  4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK); lung tumor; metformin; mitochondria-targeted metformin (mitomet); non-small cell lung cancer (NSCLC); reactive oxygen species (ROS)

DOI:  https://doi.org/10.1002/mc.23603
FEBS J. 2023 Jul 06.

Cytosolic malic enzyme and glucose-6-phosphate dehydrogenase modulate redox balance in NSCLC with acquired drug resistance.

Maoxin Ran, Yan Zhou, Yizhen Guo, Ding Huang, Shao-Lin Zhang, Kin Yip Tam.

  Lung cancer cells often show elevated levels of reactive oxygen species (ROS) and nicotinamide adenine dinucleotide phosphate (NADPH). However, the connections between deregulated redox homeostasis in different subtypes of lung cancer and acquired drug resistance in lung cancer have not yet been fully established. Herein, we analyzed different subtypes of lung cancer data reported in the Cancer Cell Line Encyclopedia database, the Cancer Genome Atlas program, and the sequencing data obtained from a gefitinib-resistant non-small cell lung cancer (NSCLC) cell line (H1975GR). Using flux balance analysis model integrated with multi-omics data and gene expression profiles, we identified cytosolic malic enzyme 1 and glucose-6-phosphate dehydrogenase as the major contributors to the significantly upregulated NADPH flux in NSCLC tissues as compared with normal lung tissues, and gefitinib-resistant NSCLC cell line as compared with the parental cell line. Silencing the gene expression of either of these two enzymes in two osimertinib-resistant NSCLC cell lines (H1975OR and HCC827OR) exhibited strong anti-proliferative effects. Our findings not only underscored the pivotal roles of cytosolic malic enzyme 1 and glucose-6-phosphate dehydrogenase in regulating redox states in NSCLC cells but also provided novel insights into their potential roles in drug-resistant NSCLC cells with disturbed redox states.

Keywords:  Acquired drug resistance; Glucose-6-phosphate dehydrogenase; Malic enzyme 1; Non-small cell lung cancer; Redox homeostasis

DOI:  https://doi.org/10.1111/febs.16897
Cell Death Dis. 2023 Jul 05. 14(7): 398

HOXC13-driven TIMM13 overexpression promotes osteosarcoma cell growth.

Qicai Han, Penghui Yan, Ruipeng Song, Feifei Liu, Qing Tian.

TIMM13 (translocase of inner mitochondrial membrane 13) located at the mitochondrial intermembrane space is vital for the integrity and function of mitochondria. We found that the mitochondrial protein TIMM13 is upregulated in human OS tissues and cells. In patient-derived primary OS cells and established cell lines, TIMM13 shRNA or knockout provoked mitochondrial dysfunction, causing mitochondrial depolarization, reactive oxygen species production, and oxidative injury, as well as lipid peroxidation, DNA damage, and ATP depletion. Moreover, TIMM13 depletion provoked OS cell apoptosis and inhibited cell proliferation and migration. Conversely, ectopic TIMM13 overexpression increased ATP contents, enhancing OS cell proliferation and migration. Moreover, we discovered that Akt-mTOR activation was inhibited with TIMM13 depletion in primary OS cells. Further studies revealed that HOXC13 (Homeobox C13)-dependent TIMM13 transcription was significantly increased in OS tissues and cells. Whereas TIMM13 transcription and expression were decreased following HOXC13 silencing in primary OS cells. In vivo, TIMM13 KO potently inhibited OS xenograft growth in the proximal tibia of nude mice. TIMM13 KO also induced Akt-mTOR inactivation, ATP depletion, oxidative injury, and apoptosis in the in situ OS tumors. Together, upregulation of the mitochondrial protein TIMM13 is important for OS cell growth, representing a novel and promising therapeutic target.

DOI: https://doi.org/10.1038/s41419-023-05910-0
Cell Death Discov. 2023 Jul 03. 9(1): 222

ROR1-STAT3 signaling contributes to ovarian cancer intra-tumor heterogeneity.

Emilia Piki, Alice Dini, Juuli Raivola, Kari Salokas, Kaiyang Zhang, Markku Varjosalo, Teijo Pellinen, Katja Välimäki, Kristina Tabor Veskimäe, Synnöve Staff, Sampsa Hautaniemi, Astrid Murumägi, Daniela Ungureanu.

Wnt pathway dysregulation through genetic and non-genetic alterations occurs in multiple cancers, including ovarian cancer (OC). The aberrant expression of the non-canonical Wnt signaling receptor ROR1 is thought to contribute to OC progression and drug resistance. However, the key molecular events mediated by ROR1 that are involved in OC tumorigenesis are not fully understood. Here, we show that ROR1 expression is enhanced by neoadjuvant chemotherapy, and Wnt5a binding to ROR1 can induce oncogenic signaling via AKT/ERK/STAT3 activation in OC cells. Proteomics analysis of isogenic ROR1-knockdown OC cells identified STAT3 as a downstream effector of ROR1 signaling. Transcriptomics analysis of clinical samples (n = 125) revealed that ROR1 and STAT3 are expressed at higher levels in stromal cells than in epithelial cancer cells of OC tumors, and these findings were corroborated by multiplex immunohistochemistry (mIHC) analysis of an independent OC cohort (n = 11). Our results show that ROR1 and its downstream STAT3 are co-expressed in epithelial as well as stromal cells of OC tumors, including cancer-associated fibroblasts or CAFs. Our data provides the framework to expand the clinical utility of ROR1 as a therapeutic target to overcome OC progression.

DOI: https://doi.org/10.1038/s41420-023-01527-6
EMBO J. 2023 Jul 06. e113258

NRF1-mediated mitochondrial biogenesis antagonizes innate antiviral immunity.

Tian Zhao, Jiaojiao Zhang, Hong Lei, Yuanyuan Meng, Hongcheng Cheng, Yanping Zhao, Guangfeng Geng, Chenglong Mu, Linbo Chen, Qiangqiang Liu, Qian Luo, Chuanmei Zhang, Yijia Long, Jingyi Su, Yinhao Wang, Zhuoya Li, Jiaxing Sun, Guo Chen, Yanjun Li, Xudong Liao, Yingli Shang, Gang Hu, Quan Chen, Yushan Zhu.

  Mitochondrial biogenesis is the process of generating new mitochondria to maintain cellular homeostasis. Here, we report that viruses exploit mitochondrial biogenesis to antagonize innate antiviral immunity. We found that nuclear respiratory factor-1 (NRF1), a vital transcriptional factor involved in nuclear-mitochondrial interactions, is essential for RNA (VSV) or DNA (HSV-1) virus-induced mitochondrial biogenesis. NRF1 deficiency resulted in enhanced innate immunity, a diminished viral load, and morbidity in mice. Mechanistically, the inhibition of NRF1-mediated mitochondrial biogenesis aggravated virus-induced mitochondrial damage, promoted the release of mitochondrial DNA (mtDNA), increased the production of mitochondrial reactive oxygen species (mtROS), and activated the innate immune response. Notably, virus-activated kinase TBK1 phosphorylated NRF1 at Ser318 and thereby triggered the inactivation of the NRF1-TFAM axis during HSV-1 infection. A knock-in (KI) strategy that mimicked TBK1-NRF1 signaling revealed that interrupting the TBK1-NRF1 connection ablated mtDNA release and thereby attenuated the HSV-1-induced innate antiviral response. Our study reveals a previously unidentified antiviral mechanism that utilizes a NRF1-mediated negative feedback loop to modulate mitochondrial biogenesis and antagonize innate immune response.

Keywords:  NRF1; TBK1; innate immunity; mitochondrial biogenesis

DOI:  https://doi.org/10.15252/embj.2022113258
Br J Haematol. 2023 Jul 06.

Metformin sensitizes AML cells to venetoclax through endoplasmic reticulum stress-CHOP pathway.

Lei Hua, Nianhui Yang, Yue Li, Kexiu Huang, Xinya Jiang, Fangshu Liu, Zhi Yu, Jie Chen, Jing Lai, Juan Du, Hui Zeng.

  Venetoclax inhibits acute myeloid leukaemia by inhibiting BCL-2 targeting, and a combination regimen with venetoclax has been explored. Although these regimens produce better clinical results, the vast majority of patients still suffer from disease recurrence or primary drug resistance. Metformin has been demonstrated to induce apoptosis in cancer cells. However, whether it can synergize with venetoclax and the underlying mechanisms of metformin-induced apoptosis are not fully understood. In this study, we investigated the effect of metformin and venetoclax on the growth of AML cells in vitro and in vivo. In both Molm13 and THP-1 cell lines, metformin and venetoclax synergistically inhibited the proliferation and induced apoptosis of leukaemia cells. Most importantly, the combination of metformin and venetoclax treatment significantly increased the expression levels of the endoplasmic reticulum (ER) stress-related marker CHOP, for example, in AML cell lines. Knockdown of CHOP markedly attenuated the metformin- and venetoclax-induced cell apoptosis. Moreover, the combination of metformin and venetoclax demonstrated prominent anti-leukaemia effects in xenograft models and bone marrow samples from AML patients. In summary, the combination of metformin and venetoclax showed enhanced anti-leukaemia activity with acceptable safety in AML patients, representing a new combinatorial strategy worth further clinical investigation to treat AML.

Keywords:  CHOP; acute myeloid leukaemia; apoptosis; endoplasmic reticulum stress; metformin

DOI:  https://doi.org/10.1111/bjh.18968
Oncol Lett. 2023 Aug;26(2): 327

Luteolin induces apoptosis by impairing mitochondrial function and targeting the intrinsic apoptosis pathway in gastric cancer cells.

Jun Ma, Zhaohai Pan, Hongchao Du, Xiaojie Chen, Xuejie Zhu, Wenjin Hao, Qiusheng Zheng, Xuexi Tang.

  Gastric cancer is one of the most lethal cancers worldwide. Research has focused on exploring natural medicines to improve the systematic chemotherapy for gastric cancer. Luteolin, a natural flavonoid, possesses anticancer activities. Nevertheless, the mechanism of the anticancer effects of luteolin is still not clear. The present study aimed to verify the inhibitory effect of luteolin on gastric cancer HGC-27, MFC and MKN-45 cells and to explore the underlying mechanism. A Cell Counting Kit-8 cell viability assay, flow cytometry, western blot, an ATP content assay and an enzyme activity testing assay were used. Luteolin inhibited the proliferation of gastric cancer HGC-27, MFC and MKN-45 cells. Further, it impaired mitochondrial integrity and function by destroying the mitochondrial membrane potential, downregulating the activities of mitochondrial electron transport chain complexes (mainly complexes I, III and V), and unbalancing the expression of B cell lymphoma-2 family member proteins, eventually leading to apoptosis of gastric cancer HGC-27, MFC and MKN-45 cells. The intrinsic apoptosis pathway was involved in luteolin's anti-gastric cancer effects. Furthermore, mitochondria were the main target in luteolin-induced gastric cancer apoptosis. The present study may provide a theoretical basis for the research on the effect of luteolin on the mitochondrial metabolism in cancer cells, and pave the way for its practical application in the future.

Keywords:  B cell lymphoma-2 family; apoptosis; gastric cancer cell; luteolin; mitochondria; mitochondrial electron transport chain

DOI:  https://doi.org/10.3892/ol.2023.13913
Biol Pharm Bull. 2023 Jul 06.

SLC25A40 facilitates anticancer drug resistance in human leukemia K562 cells.

Nodoka Kudo, Rikuma Kouno, Yoshihiko Shibayama.

  The chronic myelogenous leukemia cell line, K562/ADM is derived from the K562 cell line, which is resistant to doxorubicin (alias, adriamycin: ADM). P-glycoprotein levels are significantly higher in K562/ADM cells than in K562 cells. The overexpression of p-glycoprotein has been shown to cause drug resistance. Therefore, the present study investigated a novel mechanism underlying the drug resistance of K562/ADM cells. A gene ontology analysis demonstrated that the expression of solute carrier (SLC)-mediated transmembrane transport genes was significantly higher in K562/ADM cells than in K562 cells. The expression level of a member of the SLC family, SLC25A40 was higher in K562/ADM cells than in K562 cells. SLC25A40 is located near the ABCB1 gene. A real-time PCR analysis showed that the expression of SLC25A40, ABCB4, and ADAM22 was up-regulated. These genes are located close to SLC25A40. The down-regulation of SLC25A40 significantly decreased the mitochondrial concentration of glutathione and cell proliferation. Collectively, the present results demonstrated that the expression of SLC25A40 was up-regulated in K562/ADM cells, which enhanced to cell proliferation, and that the expression of SLC25A40 affected drug resistance to ADM.

Keywords:  Buthionine sulfoximine; Drug resistance; Glutathione; K562/ADM; SLC25A40

DOI:  https://doi.org/10.1248/bpb.b23-00293
Trends Endocrinol Metab. 2023 Jul 04. pii: S1043-2760(23)00115-7. [Epub ahead of print]

Blood-based bioenergetics: a liquid biopsy of mitochondrial dysfunction in disease.

Mia S Wilkinson, Kimberly J Dunham-Snary.

  Mitochondria operate as hubs of cellular metabolism that execute important regulatory functions. Damaged/dysfunctional mitochondria are recognized as major pathogenic contributors to many common human diseases. Assessment of mitochondrial function relies upon invasive tissue biopsies; peripheral blood cells, specifically platelets, have emerged as an ideal candidate for mitochondrial function assessment. Accessibility and documented pathology-related dysfunction have prompted investigation into the role of platelets in disease, the contribution of platelet mitochondria to pathophysiology, and the capacity of platelets to reflect systemic mitochondrial health. Platelet mitochondrial bioenergetics are being investigated in neurodegenerative and cardiopulmonary diseases, infection, diabetes, and other (patho)physiological states such as aging and pregnancy. Early findings support the use of platelets as a biomarker for mitochondrial functional health.

Keywords:  bioenergetics; biomarker; metabolism; mitochondria; platelet

DOI:  https://doi.org/10.1016/j.tem.2023.06.004