Phosphorylation of PDHA by AMPK Drives TCA Cycle to Promote Cancer Metastasis

Cell Metabolomics Study on Synergistic anti-Hepatocellular Carcinoma Effect of Aidi Injection Combined with Doxorubicin

Hepatocellular carcinoma (HCC) is the sixth most common cancer worldwide and the second most common cause of cancer deaths. This study aimed to explore the inhibitory effect and mechanism of Aidi injection (ADI) combined with doxorubicin (DOX) in HCC treatment. The drug concentrations in combined threapy was determined by investigating the effect of various concentrations of ADI and DOX on the viability of H22 cells. The combination index (CI) was also calculated. A metabolomic strategy based on ultrahigh performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) platform was established to analyze the metabolites. As a result, the CI values were less than 1, indicating that the combination of ADI and DOX exerted a synergistic effect on HCC treatment. The combination of 40‰ ADI and 1 μmol/L DOX had the strongest inhibitory effect and was used for subsequent metabolomic analysis. A total of 19 metabolic markers were obtained in metabolomic analysis, including amino acids (L-glutamic acid, L-arginine, and L-tyrosine), organic acids (succinic acid and citric acid), adenosine, and hypoxanthine , etc. Compared with the treatment using DOX or ADI alone, the combined therapy further regulated the levels of metabolic markers in HCC, which may be the reason for the synergistic effect. Seven metabolic pathways were significantly enriched, including phenylalanine, tyrosine and tryptophan biosynthesis, D-glutamine and D-glutamate metabolism, alanine, aspartate and glutamate metabolism, phenylalanine metabolism, arginine biosynthesis, tricarboxylic acid (TCA) cycle, and purine metabolism. These findings demonstrated that ADI combined with DOX can effectively inhibit the viability of H22 cells, which may exert a synergistic anti-tumor effect by balancing the metabolism of amino acids and energy-related substances.

Arginine methylation of MTHFD1 by PRMT5 enhances anoikis resistance and cancer metastasis

Metastasis accounts for the major cause of cancer-related mortality. How disseminated tumor cells survive under suspension conditions and avoid anoikis is largely unknown. Here, using a metabolic enzyme-centered CRISPR-Cas9 genetic screen, we identified methylenetetrahydrofolate dehydrogenase, cyclohydrolase and formyltetrahydrofolate synthetase 1 (MTHFD1) as a novel suppressor of anoikis. MTHFD1 depletion obviously restrained the capacity of cellular antioxidant defense and inhibited tumor distant metastasis. Mechanistically, MTHFD1 was found to bind the protein arginine methyltransferase 5 (PRMT5) and then undergo symmetric dimethylation on R173 by PRMT5. Under suspension conditions, the interaction between MTHFD1 and PRMT5 was strengthened, which increased the symmetric dimethylation of MTHFD1. The elevated methylation of MTHFD1 largely augmented its metabolic activity to generate NADPH, therefore leading to anoikis resistance and distant organ metastasis. Therapeutically, genetic depletion or pharmacological inhibition of PRMT5 declined tumor distant metastasis. And R173 symmetric dimethylation status was associated with metastasis and prognosis of ESCC patients. In conclusion, our study uncovered a novel regulatory role and therapeutic implications of PRMT5/MTHFD1 axis in facilitating anoikis resistance and cancer metastasis.

Redox-dependent AMPK inactivation disrupts metabolic adaptation to glucose starvation in xCT-overexpressing cancer cells

Accelerated aerobic glycolysis is a distinctive metabolic property of cancer cells that confers dependency on glucose for survival. However, the therapeutic strategies targeting this vulnerability are still inefficient and have unacceptable side effects in clinical trials. Therefore, developing biomarkers to predict therapeutic efficacy would be essential to improve the selective targeting of cancer cells. Here, we found that the cell lines sensitive to glucose deprivation have high expression of cystine/glutamate antiporter xCT. We found that cystine uptake and glutamate export through xCT contributed to rapid NADPH depletion under glucose deprivation. This collapse of the redox system oxidized and inactivated AMPK, a major regulator of metabolic adaptation, resulting in a metabolic catastrophe and cell death. While this phenomenon was prevented by pharmacological or genetic inhibition of xCT, overexpression of xCT sensitized resistant cancer cells to glucose deprivation. Taken together, these findings suggest a novel cross-talk between AMPK and xCT for the metabolism and signal transduction and reveal a metabolic vulnerability in xCT-high expressing cancer cells to glucose deprivation.

Liensinine Inhibits Cell Growth and Blocks Autophagic Flux in Nonsmall-Cell Lung Cancer

Liensinine is a bioactive component of Plumula Nelumbinis extracted from the green embryo of the mature seeds of Nelumbonaceae and exhibits therapeutic functions and noteworthy anti-tumor effects in recent studies. However, the potential anti-tumor property and the underlying mechanisms of liensinine in nonsmall-cell lung cancer (NSCLC) have not been illustrated. In this study, we demonstrated that liensinine has the potential anti-tumor property, and it could inhibit growth of NSCLC in vitro and in vivo. In addition, we found that although it induced significant accumulation of autophagosomes, liensinine could quench them for degradation and blocked autophagic flux. Importantly, we observed that liensinine inhibited the normal function of mitochondrial energy supply and impaired the lysosomal function. This research firstly provides a possibility insight that liensinine could be a novel therapeutic strategy for NSCLC.

Methyl Gallate Suppresses the Migration, Invasion, and Epithelial-Mesenchymal Transition of Hepatocellular Carcinoma Cells via the AMPK/NF-κB Signaling Pathway in vitro and in vivo

Methyl gallate (MG), a polyphenolic compound found in plants, is widely used in traditional Chinese medicine. MG is known to alleviate several cancer symptoms. However, most studies that have reported the antitumor effects of MG have done so at the cellular level, and the inhibitory effect and therapeutic mechanism of MG in hepatocellular carcinoma (HCC) have not been extensively explored in vivo. We aimed to understand the therapeutic mechanism of MG in HCC in vitro and in vivo. MTT and colony formation assays were used to determine the impact of MG on the proliferation of a human HCC cell line, BEL-7402; wound healing and transwell assays were used to quantify the migration and invasion of HCC cells. Western blotting was used to quantify the expression of the AMPK/NF-κB signaling pathway proteins. In vivo tumor growth was measured in a xenograft tumor nude mouse model treated with MG, and hematoxylin-eosin staining and immunohistochemistry (IHC) were used to visualize the histological changes in the tumor tissue. We found that MG showed anti-proliferative effects both in vitro and in vivo. MG downregulated the protein expression of AMPK, NF-κB, p-NF-κB, and vimentin and upregulated the expression of E-cadherin in a dose-dependent manner. Additionally, MG inhibited the migration and invasion of HCC cells by decreasing MMP9 and MMP2 expression and increasing TIMP-2 expression. These were consistent with the results of IHC in vivo. MG inhibited the proliferation, migration, and invasion of HCC cells. This effect potentially involves the regulation of the AMPK/NF-κB pathway, which in turn impacts epithelial-mesenchymal transition and MMP expression.

Bone morphogenetic protein signaling regulation of AMPK and PI3K in lung cancer cells and C. elegans

BACKGROUND

Bone morphogenetic protein (BMP) is a phylogenetically conserved signaling pathway required for development that is aberrantly expressed in several age-related diseases including cancer, Alzheimer's disease, obesity, and cardiovascular disease. Aberrant BMP signaling in mice leads to obesity, suggesting it may alter normal metabolism. The role of BMP signaling regulating cancer metabolism is not known.

METHODS

To examine BMP regulation of metabolism, C. elegans harboring BMP gain-of-function (gof) and loss-of-function (lof) mutations were examined for changes in activity of catabolic and anabolic metabolism utilizing Western blot analysis and fluorescent reporters. AMP activated kinase (AMPK) gof and lof mutants were used to examine AMPK regulation of BMP signaling. H1299 (LKB1 wild-type), A549 (LKB1 lof), and A549-LKB1 (LKB1 restored) lung cancer cell lines were used to study BMP regulation of catabolic and anabolic metabolism. Studies were done using recombinant BMP ligands to activate BMP signaling, and BMP receptor specific inhibitors and siRNA to inhibit signaling.

RESULTS

BMP signaling in both C. elegans and cancer cells is responsive to nutrient conditions. In both C. elegans and lung cancer cell lines BMP suppressed AMPK, the master regulator of catabolism, while activating PI3K, a regulator of anabolism. In lung cancer cells, inhibition of BMP signaling by siRNA or small molecules increased AMPK activity, and this increase was mediated by activation of LKB1. BMP2 ligand suppressed AMPK activation during starvation. BMP2 ligand decreased expression of TCA cycle intermediates and non-essential amino acids in H1299 cells. Furthermore, we show that BMP activation of PI3K is mediated through BMP type II receptor. We also observed feedback signaling, as AMPK suppressed BMP signaling, whereas PI3K increased BMP signaling.

CONCLUSION

These studies show that BMP signaling suppresses catabolic metabolism and stimulates anabolic metabolism. We identified feedback mechanisms where catabolic induced signaling mediated by AMPK negatively regulates BMP signaling, whereas anabolic signaling produces a positive feedback regulation of BMP signing through Akt. These mechanisms were conserved in both lung cancer cells and C. elegans. These studies suggest that aberrant BMP signaling causes dysregulation of metabolism that is a potential mechanism by which BMP promotes survival of cancer cells.

Progress in understanding the mechanisms of resistance to BCL-2 inhibitors

Venetoclax is a new type of BH3 mimetic compound that can target the binding site in the BCL-2 protein and induce apoptosis in cancer cells by stimulating the mitochondrial apoptotic pathway. Venetoclax is especially used to treat haematological malignancies. However, with the recent expansion in the applications of venetoclax, some cases of venetoclax resistance have appeared, posing a major problem in clinical treatment. In this article, we explored several common mechanisms of venetoclax resistance. Increased expression of the antiapoptotic proteins MCL-1 and BCL-XL plays a key role in conferring cellular resistance to venetoclax. These proteins can bind to the released BIM in the context of venetoclax binding to BCL-2 and thus continue to inhibit mitochondrial apoptosis. Structural mutations in BCL-2 family proteins caused by genetic instability lead to decreased affinity for venetoclax and inhibit the intrinsic apoptosis pathway. Mutation or deletion of the BAX gene renders the BAX protein unable to anchor to the outer mitochondrial membrane to form pores. In addition to changes in BCL-2 family genes, mutations in other oncogenes can also confer resistance to apoptosis induced by venetoclax. TP53 mutations and the expansion of FLT3-ITD promote the expression of antiapoptotic proteins MCL-1 and BCL-XL through multiple signalling pathways, and interfere with venetoclax-mediated apoptosis processes depending on their affinity for BH3-only proteins. Finally, the level of mitochondrial oxidative phosphorylation in venetoclax-resistant leukaemia stem cells is highly abnormal. Not only the metabolic pathways but also the levels of important metabolic components are changed, and all of these alterations antagonize the venetoclax-mediated inhibition of energy metabolism and promote the survival and proliferation of leukaemia stem cells. In addition, venetoclax can change mitochondrial morphology independent of the BCL-2 protein family, leading to mitochondrial dysfunction. However, mitochondria resistant to venetoclax antagonize this effect, forming tighter mitochondrial cristae, which provide more energy for cell survival.

Protein post-translational modifications in the regulation of cancer hallmarks

Posttranslational modifications (PTMs) of proteins, the major mechanism of protein function regulation, play important roles in regulating a variety of cellular physiological and pathological processes. Although the classical PTMs, such as phosphorylation, acetylation, ubiquitination and methylation, have been well studied, the emergence of many new modifications, such as succinylation, hydroxybutyrylation, and lactylation, introduces a new layer to protein regulation, leaving much more to be explored and wide application prospects. In this review, we will provide a broad overview of the significant roles of PTMs in regulating human cancer hallmarks through selecting a diverse set of examples, and update the current advances in the therapeutic implications of these PTMs in human cancer.

Control of topoisomerase II activity and chemotherapeutic inhibition by TCA cycle metabolites

Topoisomerase II (topo II) is essential for disentangling newly replicated chromosomes. DNA unlinking involves the physical passage of one duplex through another and depends on the transient formation of double-stranded DNA breaks, a step exploited by frontline chemotherapeutics to kill cancer cells. Although anti-topo II drugs are efficacious, they also elicit cytotoxic side effects in normal cells; insights into how topo II is regulated in different cellular contexts is essential to improve their targeted use. Using chemical fractionation and mass spectrometry, we have discovered that topo II is subject to metabolic control through the TCA cycle. We show that TCA metabolites stimulate topo II activity in vitro and that levels of TCA flux modulate cellular sensitivity to anti-topo II drugs in vivo. Our work reveals an unanticipated connection between the control of DNA topology and cellular metabolism, a finding with ramifications for the clinical use of anti-topo II therapies.

The critical function of metabolic reprogramming in cancer metastasis

Cancer metastasis is the leading cause of cancer‐related death. It is a complex, inefficient, and multistep process related to poor prognosis and high mortality of patients. Increasing evidence has shown that metabolic programming is a recognized hallmarker of cancer, plays a critical role in cancer metastasis. Metabolism alterations of glucose, lipid, and amino acid provide cancer cells with energy and substances for biosynthesis, maintain biofunctions and significantly affect proliferation, invasion, and metastasis of cancer cells. Tumor microenvironment (TME) is a complex system formed by varieties of cellular and noncellular elements. Nontumor cells in TME also undergo metabolic reprogramming or respond to metabolites to promote migration and invasion of cancer cells. A comprehensive understanding of the regulatory mechanism in metastasis from the metabolic reprogramming aspect is required to develop new therapeutic strategies combatting cancer metastasis. This review illustrates the metabolic reprogramming and interaction of cancer cells and nontumor cells in the TME, and the development of treatment strategies targeting metabolism alterations.

MAPK signalling-induced phosphorylation and subcellular translocation of PDHE1α promotes tumour immune evasion

Tumour cells utilize multiple strategies to evade the immune system, but the underlying metabolic mechanisms remain poorly understood. The pyruvate dehydrogenase (PDH) complex converts pyruvate to acetyl-coenzyme A in mitochondria, thereby linking glycolysis to the ricarboxylic acid cycle. Here we show that the PDH complex E1 subunit α (PDHE1α) is also located in the cytosol. Cytosolic PDHE1α interacts with IKKβ and protein phosphatase 1B, thereby facilitating the inhibition of the NF-κB pathway. Cytosolic PDHE1α can be phosphorylated at S327 by ERK2 and translocated into mitochondria. Decreased cytosolic PDHE1α levels restore NF-κB signalling, whereas increased mitochondrial PDHE1α levels drive α-ketoglutarate production and promote reactive oxygen species detoxification. Synergistic activation of NF-κB and reactive oxygen species detoxification promotes tumour cell survival and enhances resistance to cytotoxic lymphocytes. Consistently, low levels of PDHE1α phosphorylation are associated with poor prognosis of patients with lung cancer. Our findings show a mechanism through which phosphorylation-dependent subcellular translocation of PDHE1α promotes tumour immune evasion.

The FoxQ1 transcription factor is a novel regulator of electron transport chain complex I subunits in human breast cancer cells

The FoxQ1 is an oncogenic transcription factor that is overexpressed in basal-like and luminal-type human breast cancers when compared to the normal mammary tissue. The FoxQ1 is implicated in mammary tumor progression. However, the mechanism by which FoxQ1 promotes mammary tumorigenesis is not fully understood. In this study, we present experimental evidence for a novel function of FoxQ1 in the regulation of complex I activity of the electron transport chain. The RNA-seq data from FoxQ1 overexpressing basal-like SUM159 cells revealed a statistically significant increase in the expression of complex I subunits NDUFS1 and NDUFS2 when compared to the empty vector (EV) transfected control cells. Consistent with these results, the basal and ATP-linked oxygen consumption rates were significantly increased by FoxQ1 overexpression in SUM159 and luminal-type MCF-7 cells. The FoxQ1 overexpression in both cell lines resulted in increased intracellular levels of pyruvate, lactate, and ATP that was associated with overexpression of pyruvate dehydrogenase and pyruvate carboxylase proteins. Activity and assembly of complex I were significantly enhanced by FoxQ1 overexpression in SUM159 and MCF-7 cells that correlated with increased mRNA and/or protein levels of complex I subunits NDUFS1, NDUFS2, NDUFV1, and NDUFV2. The chromatin immunoprecipitation assay revealed the recruitment of FoxQ1 at the promoters of both NDUFS1 and NDUFV1. The cell proliferation of SUM159 and MCF-7 cells was increased significantly by overexpression of NDUFS1 as well as NDUFV1 proteins. In conclusion, we propose that increased complex I-linked oxidative phosphorylation is partly responsible for oncogenic role of FoxQ1 at least in human breast cancer cells.

Stromal Fibroblasts Counteract the Caveolin-1-Dependent Radiation Response of LNCaP Prostate Carcinoma Cells

In prostate cancer (PCa), a characteristic stromal–epithelial redistribution of the membrane protein caveolin 1 (CAV1) occurs upon tumor progression, where a gain of CAV1 in the malignant epithelial cells is accompanied by a loss of CAV1 in the tumor stroma, both facts that were correlated with higher Gleason scores, poor prognosis, and pronounced resistance to therapy particularly to radiotherapy (RT). However, it needs to be clarified whether inhibiting the CAV1 gain in the malignant prostate epithelium or limiting the loss of stromal CAV1 would be the better choice for improving PCa therapy, particularly for improving the response to RT; or whether ideally both processes need to be targeted. Concerning the first assumption, we investigated the RT response of LNCaP PCa cells following overexpression of different CAV1 mutants. While CAV1 overexpression generally caused an increased epithelial-to-mesenchymal phenotype in respective LNCaP cells, effects that were accompanied by increasing levels of the 5′-AMP-activated protein kinase (AMPK), a master regulator of cellular homeostasis, only wildtype CAV1 was able to increase the three-dimensional growth of LNCaP spheroids, particularly following RT. Both effects could be limited by an additional treatment with the SRC inhibitor dasatinib, finally resulting in radiosensitization. Using co-cultured (CAV1-expressing) fibroblasts as an approximation to the in vivo situation of early PCa it could be revealed that RT itself caused an activated, more tumor-promoting phenotype of stromal fibroblats with an increased an increased metabolic potential, that could not be limited by combined dasatinib treatment. Thus, targeting fibroblasts and/or limiting fibroblast activation, potentially by limiting the loss of stromal CAV1 seems to be absolute for inhibiting the resistance-promoting CAV1-dependent signals of the tumor stroma.

The airway microbiota of non-small cell lung cancer patients and its relationship to tumor stage and EGFR gene mutation

BACKGROUND

Accumulating studies have suggested the airway microbiota in lung cancer patients is significantly different from that of healthy controls. However, little is known about the relationship between airway microbiota and important clinical parameters of lung cancer. In this study, we aimed to explore the association between sputum microbiota and lung cancer stage, lymph node metastasis, intrathoracic metastasis, and epidermal growth factor receptor (EGFR) gene mutation.

METHODS

The microbiota of sputum samples from 85 newly-diagnosed NSCLC patients were sequenced via 16S rRNA sequencing of the V3-V4 region. Sequencing reads were filtered using QIIME2 and clustered against UPARSE.

RESULTS

Alpha- and β-diversity was significantly different between patients in stages I to II (early stage, ES) and patients in stages III to IV (advanced stage, AS). Linear discriminant analysis Effect Size (LEfSe) identified that genera Granulicatella and Actinobacillus were significantly enriched in ES, and the genus Actinomyces was significantly enriched in AS. PICRUSt2 identified that the NAD salvage pathway was significantly enriched in AS, which was positively associated with Granulicatella. Patients with intrathoracic metastasis were associated with increased genus Peptostreptococcus and incomplete reductive TCA cycle, which was associated with increased Peptostreptococcus. Genera Parvimonas, Pseudomona and L-valine biosynthesis were positively associated with lymph node metastasis. L-valine biosynthesis was related with increased Pseudomona. Finally, the genus Parvimonas was significantly enriched in adenocarcinoma patients with EGFR mutation.

CONCLUSION

The taxonomy structure differed between different lung cancer stages. The tumor stage, intrathoracic metastasis, lymph node metastasis, and EGFR mutation were associated with alteration of specific airway genera and metabolic function of sputum microbiota.

Pyruvate dehydrogenase inactivation causes glycolytic phenotype in BAP1 mutant uveal melanoma

Effective therapeutic options are still lacking for uveal melanoma (UM) patients who develop metastasis. Metastatic traits of UM are linked to BRCA1-associated protein 1 (BAP1) mutations. Cell metabolism is re-programmed in UM with BAP1 mutant UM, but the underlying mechanisms and opportunities for therapeutic intervention remain unclear. BAP1 mutant UM tumors have an elevated glycolytic gene expression signature, with increased expression of pyruvate dehydrogenase (PDH) complex and PDH kinase (PDHK1). Furthermore, BAP1 mutant UM cells showed higher levels of phosphorylated PDHK1 and PDH that was associated with an upregulated glycolytic profile compared to BAP1 wild-type UM cells. Suppressing PDHK1-PDH phosphorylation decreased glycolytic capacity and cell growth, and induced cell cycle arrest of BAP1 mutant UM cells. Our results suggest that PDHK1-PDH phosphorylation is a causative factor of glycolytic phenotypes found in BAP1 mutant UM and propose a therapeutic opportunity for BAP1 mutant UM patients.

Drug evaluation based on phosphomimetic PDHA1 reveals the complexity of activity-related cell death in A549 non-small cell lung cancer cells

Cancer cells predominantly generate energy via glycolysis, even in the presence of oxygen, to support abnormal cell proliferation. Suppression of PDHA1 by PDK1 prevents the conversion of cytoplasmic pyruvate into Acetyl-CoA. Several PDK inhibitors have been identified, but their clinical applications have not been successful for unclear reasons. In this study, endogenous PDHA1 in A549 cells was silenced by the CRISPR/Cas9 system, and PDHA1^WT and PDHA1^3SD were transduced. Since PDHA1^3SD cannot be phosphorylated by PDKs, it was used to evaluate the specific activity of PDK inhibitors. This study highlights that PDHA1^WT and PDHA1^3SD A549 cells can be used as a cell-based PDK inhibitor-distinction system to examine the relationship between PDH activity and cell death by established PDK inhibitors. Leelamine, huzhangoside A and otobaphenol induced PDH activity-dependent apoptosis, whereas AZD7545, VER-246608 and DCA effectively enhanced PDHA1 activity but little toxic to cancer cells. Furthermore, the activity of phosphomimetic PDHA1 revealed the complexity of its regulation, which requires further in-depth investigation.

AMPK adapts metabolism to developmental energy requirement during dendrite pruning in Drosophila

To reshape neuronal connectivity in adult stages, Drosophila sensory neurons prune their dendrites during metamorphosis using a genetic degeneration program that is induced by the steroid hormone ecdysone. Metamorphosis is a nonfeeding stage that imposes metabolic constraints on development. We find that AMP-activated protein kinase (AMPK), a regulator of energy homeostasis, is cell-autonomously required for dendrite pruning. AMPK is activated by ecdysone and promotes oxidative phosphorylation and pyruvate usage, likely to enable neurons to use noncarbohydrate metabolites such as amino acids for energy production. Loss of AMPK or mitochondrial deficiency causes specific defects in pruning factor translation and the ubiquitin-proteasome system. Our findings distinguish pruning from pathological neurite degeneration, which is often induced by defects in energy production, and highlight how metabolism is adapted to fit energy-costly developmental transitions.

Epigallocatechin-3-gallate pretreatment alleviates doxorubicin-induced ferroptosis and cardiotoxicity by upregulating AMPKα2 and activating adaptive autophagy

Reports indicate that the mechanism of doxorubicin (Dox)-induced cardiotoxicity is very complex, involving multiple regulatory cell death forms. Furthermore, the clinical intervention effect is not ideal. Iron dependence, abnormal lipid metabolism, and excess reactive oxygen species generation, three characteristics of ferroptosis, are potential therapeutic intervention targets. Here, we confirmed in vitro and in vivo that at least autophagy, apoptosis, and ferroptosis are involved in Dox cardiotoxicity-induced damage. When the neonatal rat cardiomyocytes and H9C2 cells or C57BL/6 mice were subjected to Dox-induced cardiotoxicity, epigallocatechin-3-gallate pretreatment could effectively decrease iron accumulation, inhibit oxidative stress and abnormal lipid metabolism, and thereby alleviate Dox cardiotoxicity-induced ferroptosis and protect the myocardium according to multiple functional, enzymatic, and morphological indices. The underlying mechanism was verified to involve the upregulation and activation of AMP-activated protein kinase α2, which promoted adaptive autophagy, increased energy supply, and maintained mitochondrial function. We believe that epigallocatechin-3-gallate is a candidate phytochemical against Dox-induced cardiotoxicity.

Pan-Cancer Analysis Reveals FH as a Potential Prognostic and Immunological Biomarker in Lung Adenocarcinoma

Fumarate hydratase (FH) is an important enzymatic component in the tricarboxylic acid cycle. Studies have reported that FH plays an important role in hereditary leiomyomatosis and renal cell cancer (HLRCC). However, the role of FH in human different cancers remains unknown. This study is aimed at analyzing the prognostic value of FH and demonstrating the correlation between FH expression and tumor immunity. Results showed that FH was mutated or copy number varied in 27 types of cancer. FH mRNA was abnormally upregulated across various cancers. Survival analysis suggested high expression of FH was associated with poor prognosis in many cancer types, including lung adenocarcinoma (LUAD). Additionally, FH expression was associated with immune infiltration, including B cells, CD4⁺ T cells, CD8⁺ T cells, neutrophils, macrophages, and dendritic cells, especially in liver hepatocellular carcinoma (LIHC), LUAD, and lung squamous cell carcinoma (LUSC). Moreover, FH expression showed a strong correlation with immune checkpoint markers in LUAD and testicular germ cell tumors (TGCT). These results indicate that FH is an immunotherapeutic target and a potential prognostic biomarker in LUAD.

Extracellular Matrix Signals as Drivers of Mitochondrial Bioenergetics and Metabolic Plasticity of Cancer Cells During Metastasis

The role of metabolism in tumor growth and chemoresistance has received considerable attention, however, the contribution of mitochondrial bioenergetics in migration, invasion, and metastasis is recently being understood. Migrating cancer cells adapt their energy needs to fluctuating changes in the microenvironment, exhibiting high metabolic plasticity. This occurs due to dynamic changes in the contributions of metabolic pathways to promote localized ATP production in lamellipodia and control signaling mediated by mitochondrial reactive oxygen species. Recent evidence has shown that metabolic shifts toward a mitochondrial metabolism based on the reductive carboxylation, glutaminolysis, and phosphocreatine-creatine kinase pathways promote resistance to anoikis, migration, and invasion in cancer cells. The PGC1a-driven metabolic adaptations with increased electron transport chain activity and superoxide levels are essential for metastasis in several cancer models. Notably, these metabolic changes can be determined by the composition and density of the extracellular matrix (ECM). ECM stiffness, integrins, and small Rho GTPases promote mitochondrial fragmentation, mitochondrial localization in focal adhesion complexes, and metabolic plasticity, supporting enhanced migration and metastasis. Here, we discuss the role of ECM in regulating mitochondrial metabolism during migration and metastasis, highlighting the therapeutic potential of compounds affecting mitochondrial function and selectively block cancer cell migration.

Adiponectin receptor agonist AdipoRon blocks skin inflamm-ageing by regulating mitochondrial dynamics

Introduction

Skin is susceptible to senescence‐associated secretory phenotype (SASP) and inflamm‐ageing partly owing to the degeneration of mitochondria. AdipoRon (AR) has protective effects on mitochondria in metabolic diseases such as diabetes. We explored the role of AR on mitochondria damage induced by skin inflamm‐ageing and its underlying mechanism.

Methods

Western blot, immunofluorescence and TUNEL staining were used to detect inflammatory factors and apoptosis during skin ageing. Transmission electron microscopy, ATP determination kit, CellLight Mitochondria GFP (Mito‐GFP), mitochondrial stress test, MitoSOX and JC‐1 staining were used to detect mitochondrial changes. Western blot was applied to explore the underlying mechanism. Flow cytometry, scratch test, Sulforhodamine B assay and wound healing test were used to detect the effects of AR on cell apoptosis, migration and proliferation.

Results

AR attenuated inflammatory factors and apoptosis that increased in aged skin, and improved mitochondrial morphology and function. This process at least partly depended on the suppression of dynamin‐related protein 1 (Drp1)‐mediated excessive mitochondrial division. More specifically, AR up‐regulated the phosphorylation of Drp1 at Serine 637 by activating AMP‐activated protein kinase (AMPK), thereby inhibiting the mitochondrial translocation of Drp1. Moreover, AR reduced mitochondrial fragmentation and the production of superoxide, preserved the membrane potential and permeability of mitochondria and accelerated wound healing in aged skin.

Conclusion

AR rescues the mitochondria in aged skin by suppressing its excessive division mediated by Drp1.

The mitochondrially-localized nucleoside diphosphate kinase D (NME4) is a novel metastasis suppressor

Background

Mitochondrial nucleoside diphosphate kinase (NDPK-D, NME4, NM23-H4) is a multifunctional enzyme mainly localized in the intermembrane space, bound to the inner membrane.

Results

We constructed loss-of-function mutants of NDPK-D, lacking either NDP kinase activity or membrane interaction and expressed mutants or wild-type protein in cancer cells. In a complementary approach, we performed depletion of NDPK-D by RNA interference. Both loss-of-function mutations and NDPK-D depletion promoted epithelial-mesenchymal transition and increased migratory and invasive potential. Immunocompromised mice developed more metastases when injected with cells expressing mutant NDPK-D as compared to wild-type. This metastatic reprogramming is a consequence of mitochondrial alterations, including fragmentation and loss of mitochondria, a metabolic switch from respiration to glycolysis, increased ROS generation, and further metabolic changes in mitochondria, all of which can trigger pro-metastatic protein expression and signaling cascades. In human cancer, NME4 expression is negatively associated with markers of epithelial-mesenchymal transition and tumor aggressiveness and a good prognosis factor for beneficial clinical outcome.

Conclusions

These data demonstrate NME4 as a novel metastasis suppressor gene, the first localizing to mitochondria, pointing to a role of mitochondria in metastatic dissemination.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-021-01155-5.

The Interplay Between Prostate Cancer Genomics, Metabolism, and the Epigenome: Perspectives and Future Prospects

Prostate cancer is a high-incidence cancer, often detected late in life. The prostate gland is an accessory gland that secretes citrate; an impaired citrate secretion reflects imbalances in the activity of enzymes in the TCA Cycle in mitochondria. Profiling studies on prostate tumours have identified significant metabolite, proteomic, and transcriptional modulations with an increased mitochondrial metabolic activity associated with localised prostate cancer. Here, we focus on the androgen receptor, c-Myc, phosphatase and tensin Homolog deleted on chromosome 10 (PTEN), and p53 as amongst the best-characterised genomic drivers of prostate cancer implicated in metabolic dysregulation and prostate cancer progression. We outline their impact on metabolic function before discussing how this may affect metabolite pools and in turn chromatin structure and the epigenome. We reflect on some recent literature indicating that mitochondrial mutations and OGlcNAcylation may also contribute to this crosstalk. Finally, we discuss the technological challenges of assessing crosstalk given the significant differences in the spatial sensitivity and throughput of genomic and metabolomic profiling approaches.

Therapeutic Interaction of Apatinib and Chidamide in T-Cell Acute Lymphoblastic Leukemia through Interference with Mitochondria Associated Biogenesis and Intrinsic Apoptosis

T-cell acute lymphoblastic leukemia (T-ALL) shows poor clinical outcome and has limited therapeutic options, indicating that new treatment approaches for this disease are urgently required. Our previous study demonstrated that apatinib, an orally selective VEGFR-2 antagonist, is highly effective in T-ALL. Additionally, chidamide, a histone deacetylase inhibitor, has proven to be cytotoxic against T-ALL in preclinical and clinical settings. However, whether the therapeutic interaction of apatinib and chidamide in T-ALL remains unknown. In this study, apatinib and chidamide acted additively to decrease cell viability and induce apoptosis in T-ALL in vitro. Notably, compared with apatinib or chidamide alone, the combinational regimen was more efficient in abrogating the leukemia burden in the spleen and bone marrow of T-ALL patient-derived xenograft (PDX) models. Mechanistically, the additive antileukemia effect of apatinib and chidamide was associated with suppression of mitochondrial respiration and downregulation of the abundance levels of several rate-limiting enzymes that are involved in the citric acid cycle and oxidative phosphorylation (OXPHOS). In addition, apatinib enhanced the antileukemia effect of chidamide on T-ALL via activation of the mitochondria-mediated apoptosis pathway and impediment of mitochondrial biogenesis. Taken together, the study provides a potential role for apatinib in combination with chidamide in the management of T-ALL and warrants further clinical evaluations of this combination in patients with T-ALL.

A Novel Integrated Metabolism-Immunity Gene Expression Model Predicts the Prognosis of Lung Adenocarcinoma Patients

Background: Although multiple metabolic pathways are involved in the initiation, progression, and therapy of lung adenocarcinoma (LUAD), the tumor microenvironment (TME) for immune cell infiltration that is regulated by metabolic enzymes has not yet been characterized.

Methods: 517 LUAD samples and 59 non-tumor samples were obtained from The Cancer Genome Atlas (TCGA) database as the training cohort. Kaplan-Meier analysis and Univariate Cox analysis were applied to screen the candidate metabolic enzymes for their role in relation to survival rate in LUAD patients. A prognostic metabolic enzyme signature, termed the metabolic gene risk score (MGRS), was established based on multivariate Cox proportional hazards regression analysis and was verified in an independent test cohort, GSE31210. In addition, we analyzed the immune cell infiltration characteristics in patients grouped by their Risk Score. Furthermore, the prognostic value of these four enzymes was verified in another independent cohort by immunohistochemistry and an optimized model of the metabolic-immune protein risk score (MIPRS) was constructed.

Results: The MGRS model comprising 4 genes (TYMS, NME4, LDHA, and SMOX) was developed to classify patients into high-risk and low-risk groups. Patients with a high-risk score had a poor prognosis and exhibited activated carbon and nucleotide metabolism, both of which were associated with changes to TME immune cell infiltration characteristics. In addition, the optimized MIPRS model showed more accurate predictive power in prognosis of LUAD.

Conclusion: Our study revealed an integrated metabolic enzyme signature as a reliable prognostic tool to accurately predict the prognosis of LUAD.

Advances in the study of cancer metastasis and calcium signaling as potential therapeutic targets

Metastasis is still the primary cause of cancer-related mortality. However, the underlying mechanisms of cancer metastasis are not yet fully understood. Currently, the epithelial-mesenchymal transition, metabolic remodeling, cancer cell intercommunication and the tumor microenvironment including diverse stromal cells, are reported to affect the metastatic process of cancer cells. Calcium ions (Ca²⁺) are ubiquitous second messengers that manipulate cancer metastasis by affecting signaling pathways. Diverse transporter/pump/channel-mediated Ca²⁺ currents form Ca²⁺ oscillations that can be decoded by Ca²⁺-binding proteins, which are promising prognostic biomarkers and therapeutic targets of cancer metastasis. This paper presents a review of the advances in research on the mechanisms underlying cancer metastasis and the roles of Ca²⁺-related signals in these events.

Identification of PDHX as a metabolic target for esophageal squamous cell carcinoma

The metabolism in tumors is reprogrammed to meet its energetic and substrate demands. However, this metabolic reprogramming creates metabolic vulnerabilities, providing new opportunities for cancer therapy. Metabolic vulnerability as a therapeutic target in esophageal squamous cell carcinoma (ESCC) has not been adequately clarified. Here, we identified pyruvate dehydrogenase (PDH) component X (PDHX) as a metabolically essential gene for the cell growth of ESCC. PDHX expression was required for the maintenance of PDH activity and the production of ATP, and its knockdown inhibited the proliferation of cancer stem cells (CSCs) and in vivo tumor growth. PDHX was concurrently upregulated with the CD44 gene, a marker of CSCs, by co-amplification at 11p13 in ESCC tumors and these genes coordinately functioned in cancer stemness. Furthermore, CPI-613, a PDH inhibitor, inhibited the proliferation of CSCs in vitro and the growth of ESCC xenograft tumors in vivo. Thus, our study provides new insights related to the development of novel therapeutic strategies for ESCC by targeting the PDH complex-associated metabolic vulnerability.

Therapeutic potential of AMPK signaling targeting in lung cancer: Advances, challenges and future prospects

Lung cancer (LC) is a leading cause of death worldwide with high mortality and morbidity. A wide variety of risk factors are considered for LC development such as smoking, air pollution and family history. It appears that genetic and epigenetic factors are also potential players in LC development and progression. AMP-activated protein kinase (AMPK) is a signaling pathway with vital function in inducing energy balance and homeostasis. An increase in AMP:ATP and ADP:ATP ratio leads to activation of AMPK signaling by upstream mediators such as LKB1 and CamKK. Dysregulation of AMPK signaling is a common finding in different cancers, particularly LC. AMPK activation can significantly enhance LC metastasis via EMT induction. Upstream mediators such as PLAG1, IMPAD1, and TUFM can regulate AMPK-mediated metastasis. AMPK activation can promote proliferation and survival of LC cells via glycolysis induction. In suppressing LC progression, anti-tumor compounds including metformin, ginsenosides, casticin and duloxetine dually induce/inhibit AMPK signaling. This is due to double-edged sword role of AMPK signaling in LC cells. Furthermore, AMPK signaling can regulate response of LC cells to chemotherapy and radiotherapy that are discussed in the current review.

Early Heat Exposure Effects on Proteomic Changes of the Broiler Liver under Acute Heat Stress

Simple Summary

Early heat exposure have been studied in the poultry industry as a method of reducing heat stress (HS) on poultry. However, the results of each study are inconsistent, and it has not been confirmed which mechanisms reduce HS by early heat exposure. Therefore, we tried to confirm the relaxation mechanism through proteomic analysis after applying early and acute heat exposure to broilers. The broilers were divided into three treatments, followed by CC (control group), CH (acute HS at the 35th day), and HH (early heat exposure at the fifth day and acute HS at the 35th day. Liver samples were collected and analyzed for proteomics and functional analysis. Proteins related to various functions, such as carbohydrate metabolism, fatty acid metabolism, energy metabolism, and the oxidation–reduction process, which were dramatically changed by acute HS, and were alleviated similar to the control group by early heat exposure. Through these results, the mechanism by which early heat exposure induces homeostasis during acute HS, and the possibility of the early heat exposure as a method of reducing HS were confirmed.

Abstract

As environmental temperatures continue to rise, heat stress (HS) is having a negative effect on the livestock industry. In order to solve this problem, many studies have been conducted to reduce HS. Among them, early heat exposure has been suggested as a method for reducing HS in poultry. In this study, we analyzed proteomics and tried to identify the metabolic mechanisms of early heat exposure on acute HS. A total of 48 chicks were separated into three groups: CC (control groups raised at optimum temperature), CH (raised with CC but exposed acute HS at the 35th day), and HH (raised with CC but exposed early heat at the fifth day and acute HS at the 35th day). After the whole period, liver samples were collected for proteomic analysis. A total of 97 differentially expressed proteins were identified by acute HS. Of these, 62 proteins recovered their expression levels by early heat exposure. We used these 62 proteins to determine the protective effects of early heat exposure. Of the various protein-related terms, we focused on the oxidative phosphorylation, fatty acid metabolism, carbohydrate metabolism, and energy production metabolism. Our findings suggest the possibility of early heat exposure effects in acute HS that may be useful in breeding or management techniques for producing broilers with high heat resistance.

Mitochondrial Ca2+ and cell cycle regulation

It has been demonstrated for more than 40 years that intracellular calcium (Ca²⁺) controls a variety of cellular functions, including mitochondrial metabolism and cell proliferation. Cytosolic Ca²⁺ fluctuation during key stages of the cell cycle can lead to mitochondrial Ca²⁺ uptake and subsequent activation of mitochondrial oxidative phosphorylation and a range of signaling. However, the relationship between mitochondrial Ca²⁺ and cell cycle progression has long been neglected because the molecule responsible for Ca²⁺ uptake has been unknown. Recently, the identification of the mitochondrial Ca²⁺ uniporter (MCU) has led to key advances. With improved Ca²⁺ imaging and detection, effects of MCU-mediated mitochondrial Ca²⁺ have been observed at different stages of the cell cycle. Elevated Ca²⁺ signaling boosts ATP and ROS production, remodels cytosolic Ca²⁺ pathways and reprograms cell fate-determining networks. These findings suggest that manipulating mitochondrial Ca²⁺ signaling may serve as a potential strategy in the control of many crucial biological events, such as tumor development and cell division in hematopoietic stem cells (HSCs). In this review, we summarize the current understanding of the role of mitochondrial Ca²⁺ signaling during different stages of the cell cycle and highlight the potential physiological and pathological significance of mitochondrial Ca²⁺ signaling.

Rheb mediates neuronal-activity-induced mitochondrial energetics through mTORC1-independent PDH activation

Neuronal activity increases energy consumption and requires balanced production to maintain neuronal function. How activity is coupled to energy production remains incompletely understood. Here, we report that Rheb regulates mitochondrial tricarboxylic acid cycle flux of acetyl-CoA by activating pyruvate dehydrogenase (PDH) to increase ATP production. Rheb is induced by synaptic activity and lactate and dynamically trafficked to the mitochondrial matrix through its interaction with Tom20. Mitochondria-localized Rheb protein is required for activity-induced PDH activation and ATP production. Cell-type-specific gain- and loss-of-function genetic models for Rheb reveal reciprocal changes in PDH phosphorylation/activity, acetyl-CoA, and ATP that are not evident with genetic or pharmacological manipulations of mTORC1. Mechanistically, Rheb physically associates with PDH phosphatase (PDP), enhancing its activity and association with the catalytic E1α-subunit of PDH to reduce PDH phosphorylation and increase its activity. Findings identify Rheb as a nodal point that balances neuronal activity and neuroenergetics via Rheb-PDH axis.

Metabolic requirements of pulmonary fibrosis: role of fibroblast metabolism

Fibrosis is a pathologic condition characterized by excessive deposition of extracellular matrix and chronic scaring that can affect every organ system. Organ fibrosis is associated with significant morbidity and mortality, contributing to as many as 45% of all deaths in the developed world. In the lung, many chronic lung diseases may lead to fibrosis, the most devastating being idiopathic pulmonary fibrosis (IPF), which affects approximately 3 million people worldwide and has a median survival of 3.8 years. Currently approved therapies for IPF do not significantly extend lifespan, and thus, there is pressing need for novel therapeutic strategies to treat IPF and other fibrotic diseases. At the heart of pulmonary fibrosis are myofibroblasts, contractile cells with characteristics of both fibroblasts and smooth muscle cells, which are the primary cell type responsible for matrix deposition in fibrotic diseases. Much work has centered around targeting the extracellular growth factors and intracellular signaling regulators of myofibroblast differentiation. Recently, metabolic changes associated with myofibroblast differentiation have come to the fore as targetable mechanisms required for myofibroblast function. In this review, we will discuss the metabolic changes associated with myofibroblast differentiation, as well as the mechanisms by which these changes promote myofibroblast function. We will then discuss the potential for this new knowledge to lead to the development of novel therapies for IPF and other fibrotic diseases.

Construction and Validation of a Nomogram for the Preoperative Prediction of Lymph Node Metastasis in Gastric Cancer

BACKGROUND

Increasing evidence indicated that the tumor microenvironment (TME) plays a critical role in tumor progression. This study aimed to identify and evaluate mRNA signature involved in lymph node metastasis (LNM) in TME for gastric cancer (GC).

METHODS

Gene expression and clinical data were downloaded from The Cancer Genome Atlas (TCGA). The ESTIMATE algorithm was used to evaluate the TME of GC. The heatmap and Venn plots were applied for visualizing and screening out intersect differentially expressed genes (DEGs) involved in LNM in TME. Functional enrichment analysis, gene set enrichment analysis (GSEA) and protein-protein interaction (PPI) network were also conducted. Furthermore, binary logistic regression analysis were employed to develop a 4-mRNAs signature for the LNM prediction. ROC curves were applied to validate the LNM predictive ability of the riskscore. Nomogram was constructed and calibration curve was plotted to verify the predictive power of nomogram.

RESULTS

A total of 88 LNM related DEGs were identified. Functional enrichment analysis and GSEA implied that those genes were associated with some biological processes, such as ion transportation, lipid metabolism and thiolester hydrolase activity. After univariate and multivariate logistic regression analysis, 4 mRNAs (RASSF2, MS4A2, ANKRD33B and ADH1B) were eventually screened out to develop a predictive model. ROC curves manifested the good performance of the 4-mRNAs signature. The proportion of patients with LNM in high-risk group was significantly higher than that in low-risk group. The C-index of nomogram from training and test cohorts were 0.865 and 0.765, and the nomogram was well calibrated.

CONCLUSIONS

In general, we identified a 4-mRNAs signature that effectively predicted LNM in GC patients. Moreover, the 4-mRNAs signature and nomogram provide a guidance for the preoperative evaluation and postoperative treatment of GC patients.

The Tumor Microenvironment-A Metabolic Obstacle to NK Cells' Activity

NK cells have unique capabilities of recognition and destruction of tumor cells, without the requirement for prior immunization of the host. Maintaining tolerance to healthy cells makes them an attractive therapeutic tool for almost all types of cancer. Unfortunately, metabolic changes associated with malignant transformation and tumor progression lead to immunosuppression within the tumor microenvironment, which in turn limits the efficacy of various immunotherapies. In this review, we provide a brief description of the metabolic changes characteristic for the tumor microenvironment. Both tumor and tumor-associated cells produce and secrete factors that directly or indirectly prevent NK cell cytotoxicity. Here, we depict the molecular mechanisms responsible for the inhibition of immune effector cells by metabolic factors. Finally, we summarize the strategies to enhance NK cell function for the treatment of tumors.