Fumarate hydratase (FH) and cancer: a paradigm of oncometabolism

Role of mitochondria in physiological activities, diseases, and therapy

Mitochondria are generally considered essential for life in eukaryotic organisms because they produce most of the energy or adenosine triphosphate (ATP) needed by the cell. Beyond energy production, it is now widely accepted that mitochondria also play a pivotal role in maintaining cellular homeostasis and signaling. The two core processes of mitochondrial dynamics, fission and fusion, serve as crucial foundations for maintaining mitochondrial morphology, distribution, and quantity, thereby ensuring cellular homeostasis. Mitochondrial autophagy (mitophagy) ensures the selective degradation of damaged mitochondria, maintaining quality control. Mitochondrial transport and communication further enhance their role in cellular processes. In addition, mitochondria are susceptible to damage, resulting in dysfunction and disruption of intracellular homeostasis, which is closely associated with the development of numerous diseases. These include mitochondrial diseases, neurodegenerative diseases, cardiovascular diseases (CVDs) and stroke, metabolic disorders such as diabetes mellitus, cancer, infectious diseases, and the aging process. Given the central role of mitochondria in disease pathology, there is a growing need to understand their mechanisms and develop targeted therapies. This review aims to provide a comprehensive overview of mitochondrial structure and functions, with a particular focus on their roles in disease development and the current therapeutic strategies targeting mitochondria. These strategies include mitochondrial-targeted antioxidants, modulation of mitochondrial dynamics and quality control, mitochondrial genome editing and genetic therapy, and mitochondrial transplantation. We also discuss the challenges currently facing mitochondrial research and highlight potential future directions for development. By summarizing the latest advancements and addressing gaps in knowledge, this review seeks to guide future research and clinical efforts in the field of mitochondrial medicine.

Mitochondrial fumarate inhibits Parkin-mediated mitophagy

Here, we explore the potential involvement of fumarate, a metabolite generated from the TCA cycle, as a key regulator of PINK1-Parkin-mediated mitophagy. Fumarate engages in a process called succination, forming S-(2-succino) cysteine with protein cysteine residues. Our research demonstrates that this modification specifically targets the sulfhydryl group of cysteine 323 and 451 residues of human Parkin, leading to the inhibition of its mitochondrial localization and E3 ligase activity, thereby impeding PINK1-Parkin-mediated mitophagy. Notably, our investigation reveals that the succinatable cysteines in human Parkin are not conserved in invertebrates, including Drosophila. To assess the functional impact of Parkin succination, we generate Parkin knockin flies with succinatable cysteines. These flies exhibit robust Parkinson's disease (PD)-related phenotypes when exposed to elevated fumarate levels. Collectively, our findings underscore the significance of fumarate as an endogenous regulator of PINK1-Parkin-mediated mitophagy, offering insights into the intricate interplay between mitochondrial metabolic activities and PD pathology.

ATRX loss in adult gliomas lacking H3 alterations or IDH mutations, an exceptional situation for exceptional diagnoses: the experience of Sainte-Anne hospital

ATRX immunostaining constitutes a routinely used biomarker for the practice of neuropathology. The loss of ATRX expression correlating with ATRX gene alterations is implicated in a wide variety of pediatric and adult gliomas, and has been indexed as a desirable or essential diagnostic criterion for four tumor types featured in the latest world health organization classification of central nervous system Tumors. In adult-type diffuse glioma, the loss of ATRX expression is a hallmark of astrocytoma, IDH-mutant. Recently, novel tumor types and alterations have been referenced in the literature. These include the high-grade astrocytoma with piloid features (HGAP), for which no consistent clinicopathological features have been defined, and the presence of other alterations in the Krebs cycle genes (variants of the Fumarate hydratase -FH- gene) found in gliomas resembling astrocytomas, IDH-mutant. Because of this rapidly evolving classification and histomolecular landscape, we retrospectively analyzed adult gliomas diagnosed over a four consecutive year period to identify supratentorial gliomas, lacking H3 alterations or IDH mutations and harboring a loss of ATRX expression, in order to update their diagnoses in terms of histopathology, genetics and epigenetics. Four specimens (from 620 adult gliomas, 0.7%) were reclassified at the end of the molecular workup, as: 1/ one HGAP, 2/ one malignant transformation with a primitive neuronal component of an astrocytoma, IDH-mutant which lost the IDH2 mutation at recurrence, 3/ a glioma, FH-mutant for which the histopathological and epigenetic features were similar to an astrocytoma, IDH-mutant, and 4/ a glioblastoma, IDH-wildtype. To conclude, these exceptional cases extend the spectrum of ATRX loss in gliomas, beyond the astrocytoma, IDH-mutant and the diffuse hemispheric glioma, H3 G34-mutant.

Cell death and cancer: Metabolic interconnections

Recent findings in the cell death field have transformed our understanding of the interplay between metabolism and cell death in the context of cancer. In this review, we discuss the relationships between metabolism and the cell death pathways of apoptosis, necroptosis, pyroptosis, and ferroptosis, with a particular focus on recent advancements. We will also explore the regulation of metabolism by the BCL-2 family and the participation of oncometabolites in the regulation of cell death. Finally, we examine the emerging links between cell death signaling and cellular persistence. As we highlight in this review, the intersection of metabolic and cell death pathways has implications for cancer cell survival, treatment resistance, and the tumor microenvironment.

Oncogenic role of fumarate hydratase in breast cancer: metabolic reprogramming and mechanistic insights

Breast cancer remains the most prevalent malignancy among women globally, with its complexity linked to genetic variations and metabolic alterations within tumor cells. This study investigates the role of fumarate hydratase (FH), a key enzyme in the tricarboxylic acid (TCA) cycle, in breast cancer progression. Our findings reveal that FH mRNA and protein levels are significantly upregulated in breast cancer tissues and correlate with poor patient prognosis and aggressive tumor characteristics. Using in vitro and in vivo models, we demonstrate that FH overexpression enhances breast cancer cell proliferation, migration, and invasion through metabolic reprogramming and by increasing reactive oxygen species (ROS) production. Furthermore, we identify matrix metalloproteinase 1 (MMP1) as a downstream effector of FH, linked to p21 downregulation, elucidating a novel regulatory pathway influencing tumor behavior. Interestingly, unlike its tumor-suppressing role in other cancer types, this study highlights FH's oncogenic potential in breast cancer. Our results suggest that FH enhances cancer cell viability and aggressiveness via both catalytic and non-catalytic mechanisms. This work not only underscores the metabolic adaptations of breast cancer cells but also proposes FH as a potential biomarker and therapeutic target for breast cancer management.

Fumarate hydratase in cancer research: scientific trends and findings over 22 years

OBJECTIVE

Fumarate hydratase (FH) is a key enzyme in the Krebs cycle and cellular energy metabolism, playing a crucial role in tumorigenesis. It is considered a prognostic, diagnostic, and therapeutic target for many types of cancer. Therefore, FH is a popular scientific subject in cancer research. The current study aimed to identify cancer research in the WoS database and examine studies conducted on FH molecules using bibliometric indicators.

METHODS

The keywords "fumarate hydratase" OR fumarase" AND "cancer OR tumor OR neoplasm" were used to search the WoS database. This search was performed using abstracts, titles, and keywords. The "Article" and "Review" options were used to access the data of papers published between 2002 and March 2024.

RESULTS

A total of 840 publications (616 articles and 224 reviews) were published by the end of March 2024. Research output on FH and cancer has significantly increased recently, with the highest number of publications in 2020 (n = 69, 8.214%). The most commonly used language was English (n = 823, 97.976%), and the USA led in productivity, contributing 306 studies (36.429%). The University of Helsinki is the most productive affiliation with 138 published articles. The researcher who conducted most studies (n = 58, 6.904%) was also the most-cited author, with 1562 citations. In the current bibliometric study, "hereditary leiomyomatosis", "mutations", and "renal-cell cancer" were frequently included in publications.

CONCLUSION

This bibliometric study provides a quantitative overview of FH research in oncology and presents the most recent FH status in cancer research.

Multi-omics analysis unraveling stemness features associated with oncogenic dedifferentiation in 12 cancers

Tumorigenesis is typically accompanied by cellular dedifferentiation and the acquisition of stem cell-like attributes. However, few studies have comprehensively evaluated the putative relationships between these characteristics and various cancers. Here, we integrated gene expression and DNA methylation quantitative trait loci (cis-eQTL and cis-mQTL) data from the blood to perform multi-omics Mendelian randomization analysis. Our analyses revealed 967 stem cell-associated genes (P<0.05) and 11,262 methylation sites (P<0.01) significantly related to 12 cancers. SMAD7 (cg14321542) in colon cancer, IGF2 (cg13508136) in prostate cancer, and FADS1 (cg07005513) in rectal cancer were prioritized as candidate causal genes and regulatory elements. Notably, using cis-eQTL data from the corresponding tissue sites, we detected 16 stem cell-associated genes dramatically causally associated with six cancers (FDR<0.2). The gene THBS3 was particularly common in both blood and stomach tissues and exhibited prognostic significance. Furthermore, it was markedly associated with one microbial metabolic pathway and four immunophenotypes. Functional validation using the ECC12 gastric cancer cell line revealed that the inhibition of its expression could accelerate oxidative phosphorylation and reactive oxygen species production, reduce clonal proliferation ability, and promote the apoptosis of stomach tumor cells. Additionally, based on spatial transcriptomic data from gastrointestinal cancers, the results demonstrated the clusters enriched with the most stem cell-associated genes exhibited significantly enhanced tumor-promoting potency, and the THBS3-expressing cells displayed suppressed oxidative phosphorylation. Overall, this study enhances our understanding of tumorigenic mechanisms and aids in the identification of therapeutic targets.

Assessing the long-term impact of incorporating GAC and Fe&G mediators for enhancing phenol containing simulated wastewater treatment in UASB reactor

Phenol containing wastewater (PCW) is highly toxic and difficult to be treated by traditional methods. This study utilized granular activated carbon (GAC) and Fe (Sponge iron) &GAC (Fe&G) in a laboratory-scale UASB reactor to mitigate the toxicity of phenol containing simulated wastewater (PCSW) and enhance treatment performance. Compared with GAC, Fe&G mediators achieves approximately 7 % and 24 % higher removal rates for COD and phenolic compounds, respectively. The methane accumulation in Fe&G group was about 10 % higher than that in GAC group and 22 % higher than that in blank group. Microbial analysis showed that compared with GAC, Fe&G mediators could enrich Petronas and Methanothrix to intensify Direct Interspecies Electron Transfer (DIET) to augment PCSW treatment and boost methane production. PICRUSt analysis showed that these mediators enriched key genes such as TCA cycle and CO2 methanogenesis pathway to improve microbial resistance to PCSW toxicity and enhance microbial metabolism. This study provides a new method for anaerobic treatment of highly polluted industrial wastewater.

P4HB, a novel succinated protein, is essential for fumarate-induced cancer metastasis

Fumarate hydratase (FH) catalyzes the conversion of fumarate to malate in the tricarboxylic acid cycle. Its deficiency leads to fumarate accumulation, which is associated with kidney cancer metastasis, though the exact mechanisms remain unclear. Here, we identify prolyl 4-hydroxylase beta (P4HB) as a novel fumarate target in FH-deficient cancer cells that promotes migration and invasion. FH knockdown in human renal cancer cells significantly enhanced migratory and invasive capacities by 10- and 8-fold, respectively. Mechanistically, fumarate-induced succination stabilizes P4HB, promoting type I collagen production and enhancing tumor metastasis. P4HB knockdown markedly suppresses FH deficiency-induced metastasis in xenograft models. Fluorescence intensity in the FH knockdown group was about 10-fold higher, and tumor-bearing liver weight was approximately 1.5-fold greater than that in the FH and P4HB co-knockdown group. These results underscore the pivotal role of P4HB in metastasis. Additionally, we reveal NDP52 as a specific autophagy receptor that recognizes and binds to P4HB, mediating its degradation through the autophagy-lysosome pathway. However, succination of P4HB disrupts this recognition, interaction, and degradation, stabilizing P4HB. Together, these findings provide new insights into how fumarate-mediated succination affects P4HB protein stability and cancer metastasis, and suggest that P4HB could serve as a potential therapeutic target in FH-deficient cancers.

Exploring the Genetic and Clinical Landscape of Dedifferentiated Endometrioid Carcinoma

Dedifferentiated endometrioid carcinoma (DDEC) is rare, has a poor prognosis, and the genes responsible for dedifferentiation remain unclear. This study aimed to clarify the characteristics of DDEC in Japanese patients and develop treatment strategies. Eighteen DDEC cases were included; their clinicopathological features and prognoses were analyzed and compared to those of other histological subtypes. The samples were divided into well-differentiated and undifferentiated components; immunostaining and whole-exome sequencing (n = 3 cases) were conducted. The incidence of DDEC was 2.0% among endometrial cancers. The 5-year progression-free survival and the 5-year overall survival for DDEC was approximately 40% and 30%, respectively. Immunohistochemistry showed that 66.7% of patients were mismatch repair deficient. The rate of p53 mutations was higher than that reported in previous studies, and patients with p53 mutations in the undifferentiated components had a poor prognosis. Whole-exome sequencing revealed different gene mutations and mutation signatures between well-differentiated and undifferentiated components. New genetic mutations in undifferentiated regions were uncommon in all three cases. One case (case 1) exhibited homologous recombination deficiency, whereas the other two showed microsatellite instability-high and hypermutator phenotypes. Genetic analysis suggests that immune checkpoint and poly (ADP-ribose) polymerase inhibitors and drugs targeting the p53 pathway may be effective against DDEC.

Fumarate integrates metabolism and immunity in diseases

Fumarate is a key metabolite produced primarily by the tricarboxylic acid (TCA) and urea cycles. In addition to having a metabolic role, its electrophilicity enables it to covalently modify cysteines; moreover, because of its α-ketoglutarate (α-KG)-like structure, it can also act as a competitive inhibitor of α-KG-dependent dioxygenases for epigenetic remodeling. Recent advances have broadened the role of fumarate as a bridge between metabolism and both innate and adaptive immunity, suggesting potentially important functions in anticancer immunity and autoimmune diseases. Here we review the connections between fumarate metabolism and immunity; we describe the mechanisms of fumarate regulation in cancer, autoimmunity, and other diseases; and we explore the clinical implications of fumarate and its esters for immunotherapy.

Timely recognition of a probably life-threatening genodermatosis: familial case report of hereditary leiomyomatosis and renal cell cancer

Background

Autosomal dominant genodermatoses with a predisposition for cancer make up a well-described disease group with unique cutaneous alterations in each. This should urge dermatologists to think of other consequences beyond the skin. Histological examination serves as the gold standard, and it is an effective tool for the first investigation, even nowadays in the "next-generation genetic" era. Multiple appearances of benign tumours histologically proved to be cutaneous leiomyomatosis suggest a rare disorder with germline heterozygous pathogen variant in the FH gene. The encoded fumarate hydratase is a Krebs cycle enzyme, and has a role in catalysing the transition from fumarate to malate.

Case presentation

Years before the easy accessibility of the complete genetic workup in Hungary, a yearly abdominal MRI check-up was suggested preventively for a middle-aged man with multiplex cutaneous leiomyomata. During the follow-up period papillary type 2 renal cell carcinoma was diagnosed in the left kidney at an early stage, and a successful operation saved his life without the need for aggressive chemotherapy or immunotherapy. Immunohistochemistry of tumour tissue proved FH-deficient renal cell cancer. We discuss in short the current knowledge of pathophysiology and accessible therapies regarding this aggressive malignant tumour type in the kidney, which is usually detected in the advanced stage with early metastasis. We also highlight an early sign, i.e., solitary cystic alteration in the kidney, which can be preliminarily observed before malignant transformation, which was also described in mouse models. Sanger sequencing and Multiplex-Ligation-Dependent Probe Amplification (MLPA) analysis of the FH gene was completed in the affected son of the original proband, and Hereditary Leiomyomatosis and Renal Cell Cancer (HLRCC) was confirmed by demonstrating a large germline deletion in this family after years of observation.

Conclusion

Regular observation of individuals with hereditary leiomyomatosis may prevent a serious sequelae of untreatable renal malignancy.

Evaluation of an IDH1/2 Mutation FastTrack Assay for Patients with Cholangiocarcinoma

BACKGROUND

Cholangiocarcinoma, a malignancy originating from the bile ducts, poses significant treatment challenges due to its typically late diagnosis and limited therapeutic options. However, recent advances in molecular genetics enable more personalized treatment approaches. A notable breakthrough in this context is the identification of isocitrate dehydrogenase (IDH) mutations, particularly IDH1 and IDH2, which occur in a subset of cholangiocarcinoma patients. Those with IDH1/2 mutations may benefit from targeted therapies. For instance, Ivosidenib, an IDH1 inhibitor, has shown efficacy in clinical trials, offering a new therapeutic option for patients with IDH1-mutant cholangiocarcinoma. Developing and implementing standardized protocols for testing and reporting mutation status are crucial for consistency and accuracy in clinical practice. Both the Idylla™ IDH1-2 Mutation Assay Kit as a FastTrack method and Next-Generation Sequencing (NGS) panels play critical roles in molecular characterization of cholangiocarcinoma.

METHODS

Under this aspect, a set of cholangiocarcinomas was tested using the Idylla™ platform regarding the respective recommended guidelines and standards of DIN EN ISO:17020 and DIN EN ISO:15198.

RESULTS

Overall, 25 clinically diagnosed intrahepatic cholangiocarcinomas or Adeno-CUPs were analyzed. IDH1/2 mutations were identified in 68% (17/25) of cases using both methods, with high concordance between NGS and Idylla™ results. Discrepancies were observed in two samples, where Idylla™ detected no mutations, but NGS reported IDH1 and IDH2 mutations, respectively.

CONCLUSIONS

IdyllaTM offers a rapid, user-friendly, and specific method for detecting IDH1/2 mutations, ideal for immediate clinical needs. NGS, while more time-consuming and costly, provides comprehensive genetic profiles valuable for personalized medicine and research. The choice between these methods should be guided by the clinical context, resource availability, and individual patient needs. For routine diagnostics, we recommend an algorithmic approach starting with the FastTrack method followed by NGS for wildtype cases.

Exploration of the mutational landscape of cutaneous leiomyoma confirms FH as a driver gene and identifies targeting purine metabolism as a potential therapeutic strategy

To comprehensively explore the mutational landscape of cutaneous leiomyoma (cLM) and identify candidate driver events, we performed a retrospective, multi-institutional, whole-exome sequencing and RNA sequencing study. We confirmed that a large proportion of patients with cLM have germline FH variants and additionally showed that somatic alteration of FH also drives cLM, with biallelic inactivation of FH being a frequent event. Treatment of Fh1-proficient and -deficient cell lines with the purine antagonist and chemotherapeutic agent, mercaptopurine, significantly decreased growth/colony formation; however, the addition of nucleosides was able to rescue only the Fh1-proficient cells, suggesting that purine metabolism is a targetable vulnerability for FH-deficient cLMs.

[Molecularly defined renal cell carcinomas]

BACKGROUND

The latest edition of the WHO classification of urinary and male genital tumours was published in 2022. The revision was based on the newest scientific literature. This article summarizes the updated recommendations regarding the classification of molecularly defined tumours.

RESULTS AND CONCLUSIONS

The current edition of the WHO classification of tumours introduced the new category of molecularly defined tumours. This category includes TFE3-rearranged RCC, TFEB-altered RCC, ELOC-mutated RCC, FH-deficient RCC, SDH-deficient RCC, ALK-rearranged RCC and SMARCB1-deficient RCC. The change reflects the importance of the respective alterations with regard to tumour biology and future treatment options. Simultaneously, the diagnosis of these tumours, which sometimes can show equivocal morphologies, is facilitated.

The fundamental role of mitochondria-endoplasmic reticulum contacts in ageing and declining healthspan

This open question research article highlights mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs), which have emerged as crucial cellular structures that challenge our traditional understanding of organelle function. This review highlights the critical importance of MAMs as a frontier in cell biology with far-reaching implications for health, disease and ageing. MAMs serve as dynamic communication hubs between the ER and mitochondria, orchestrating essential processes such as calcium signalling, lipid metabolism and cellular stress responses. Recent research has implicated MAM dysfunction in a wide array of conditions, including neurodegenerative diseases, metabolic disorders, cardiovascular diseases and cancer. The significant lack of biological knowledge behind MAM function emphasizes the need to study these enigmatic subcellular sites in greater detail. Key open questions include the mechanisms controlling MAM formation and disassembly, the full complement of MAM-associated proteins and how MAMs contribute to cellular decision-making and ageing processes. Advancing our understanding of MAMs through interdisciplinary approaches and cutting-edge technologies promises to reveal new insights into fundamental cellular signalling pathways and potentially lead to innovative therapeutic strategies for a range of diseases. As such, MAM research represents a critical open question in biology with the potential to transform our understanding of cellular life and human health.

The molecular code of kidney cancer: A path of discovery for gene mutation and precision therapy

Renal cell carcinoma (RCC) is a malignant tumor with highly heterogeneous and complex molecular mechanisms. Through systematic analysis of TCGA, COSMIC and other databases, 24 mutated genes closely related to RCC were screened, including VHL, PBRM1, BAP1 and SETD2, which play key roles in signaling pathway transduction, chromatin remodeling and DNA repair. The PI3K/AKT/mTOR signaling pathway is particularly important in the pathogenesis of RCC. Mutations in genes such as PIK3CA, MTOR and PTEN are closely associated with metabolic abnormalities and tumor cell proliferation. Clinically, mTOR inhibitors and VEGF-targeted drugs have shown significant efficacy in personalized therapy. Abnormal regulation of metabolic reprogramming, especially glycolysis and glutamine metabolic pathways, provides tumor cells with continuous energy supply and survival advantages, and GLS1 inhibitors have shown promising results in preclinical studies. This paper also explores the potential of immune checkpoint inhibitors in combination with other targeted drugs, as well as the promising application of nanotechnology in drug delivery and targeted therapy. In addition, unique molecular mechanisms are revealed and individualized therapeutic strategies are explored for specific subtypes such as TFE3, TFEB rearrangement type and SDHB mutant type. The review summarizes the common gene mutations in RCC and their molecular mechanisms, emphasizes their important roles in tumor diagnosis, treatment and prognosis, and looks forward to the application prospects of multi-pathway targeted therapy, metabolic targeted therapy, immunotherapy and nanotechnology in RCC treatment, providing theoretical support and clinical guidance for individualized treatment and new drug development.

Noncanonical TCA cycle fosters canonical TCA cycle and mitochondrial integrity in acute myeloid leukemia

Cancer cells rely on mitochondrial oxidative phosphorylation (OXPHOS) and the noncanonical tricarboxylic acid (TCA) cycle. In this paper, we shed light on the vital role played by the noncanonical TCA cycle in a host-side concession to mitochondria, especially in highly energy-demanding malignant tumor cells. Inhibition of ATP-citrate lyase (ACLY), a key enzyme in the noncanonical TCA cycle, induced apoptosis by increasing reactive oxygen species levels and DNA damage while reducing mitochondrial membrane potential. The mitochondrial membrane citrate transporter inhibitor, CTPI2, synergistically enhanced these effects. ACLY inhibition reduced cytosolic citrate levels and CTPI2 lowered ACLY activity, suggesting that the noncanonical TCA cycle is sustained by a positive feedback mechanism. These inhibitions impaired ATP production, particularly through OXPHOS. Metabolomic analysis of mitochondrial and cytosolic fractions revealed reduced levels of glutathione pathway-related and TCA cycle-related metabolite, except fumarate, in mitochondria following noncanonical TCA cycle inhibition. Despite the efficient energy supply to the cell by mitochondria, this symbiosis poses challenges related to reactive oxygen species and mitochondrial maintenance. In conclusion, the noncanonical TCA cycle is indispensable for the canonical TCA cycle and mitochondrial integrity, contributing to mitochondrial domestication.

Integrative analysis of toxicometabolomics and toxicoproteomics data: new molecular insights into thiazolidinedione-induced cardiotoxicity

INTRODUCTION

Despite the well-established efficacy of thiazolidinediones (TZDs), including pioglitazone and rosiglitazone, in type II diabetes management, their potential contribution to heart failure risk remains a significant area of uncertainty. This incomplete understanding, which persists despite decades of clinical use of TZDs, has generated ongoing controversy and unanswered questions regarding their safety profiles, ultimately limiting their broader clinical application.

OBJECTIVE AND METHODS

This study presented a multi-omics approach, integrating toxicoproteomics and toxicometabolomics data with the goal of uncovering novel mechanistic insights into TZD cardiotoxicity and identifying molecular signatures predictive of side effect progression.

RESULTS

Network analysis of proteo-metabolomic data revealed a distinct fingerprint of disrupted biochemical pathways, which were primarily related to energy metabolism. Downregulation of oxidative phosphorylation and fatty acid synthesis was coupled with increased activity in anaerobic glycolysis, the pentose phosphate pathway, and amino acid and purine metabolism. This suggests a potential metabolic shift in AC16 cells from fatty acid oxidation towards anaerobic glycolysis, potentially contributing to observed cardiotoxicity. Additionally, the study identified a marked disruption in the glutathione system, indicating an imbalanced redox state triggered by TZD exposure. Importantly, our analysis identified key molecular signatures across omics datasets, including prominent signatures of amino acids like L-ornithine, L-tyrosine and glutamine, which are evidently associated with heart failure, supporting their potential use for the early prediction of cardiotoxicity progression.

CONCLUSION

By uncovering a novel mechanistic explanation for TZD cardiotoxicity, this study simultaneously illuminates potential therapeutic interventions, opening avenues for future research to improve the safety profile of TZD agents. (250 words).

Oncometabolites at the crossroads of genetic, epigenetic and ecological alterations in cancer

By the time a tumor reaches clinical detectability, it contains around 108-109 cells. However, during tumor formation, significant cell loss occurs due to cell death. In some estimates, it could take up to a thousand cell generations, over a ~ 20-year life-span of a tumor, to reach clinical detectability, which would correspond to a "theoretical" generation of ~1030 cells. These rough calculations indicate that cancers are under negative selection. The fact that they thrive implies that they "evolve", and that their evolutionary trajectories are shaped by the pressure of the environment. Evolvability of a cancer is a function of its heterogeneity, which could be at the genetic, epigenetic, and ecological/microenvironmental levels [1]. These principles were summarized in a proposed classification in which Evo (evolutionary) and Eco (ecological) indexes are used to label cancers [1]. The Evo index addresses cancer cell-autonomous heterogeneity (genetic/epigenetic). The Eco index describes the ecological landscape (non-cell-autonomous) in terms of hazards to cancer survival and resources available. The reciprocal influence of Evo and Eco components is critical, as it can trigger self-sustaining loops that shape cancer evolvability [2]. Among the various hallmarks of cancer [3], metabolic alterations appear unique in that they intersect with both Evo and Eco components. This is partly because altered metabolism leads to the accumulation of oncometabolites. These oncometabolites have traditionally been viewed as mediators of non-cell-autonomous alterations in the cancer microenvironment. However, they are now increasingly recognized as inducers of genetic and epigenetic modifications. Thus, oncometabolites are uniquely positioned at the crossroads of genetic, epigenetic and ecological alterations in cancer. In this review, the mechanisms of action of oncometabolites will be summarized, together with their roles in the Evo and Eco phenotypic components of cancer evolvability. An evolutionary perspective of the impact of oncometabolites on the natural history of cancer will be presented.

Metabolomics and proteomics in pheochromocytoma and paraganglioma: Translating biochemistry and biology to bedside

The complexity of omes - the key cellular ensembles (genome and epigenome, transcriptome, proteome, and metabolome) - is becoming increasingly understood in terms of big-data analysis, the omics. Amongst these, proteomics provides a global description of quantitative and qualitative alterations of protein expression (or protein abundance in body fluids) in response to physiologic or pathologic processes while metabolomics offers a functional portrait of the physiological state by quantifying metabolite abundances in biological samples. Here, we summarize how different techniques of proteomic and metabolic analysis can be used to define key biochemical characteristics of pheochromocytomas/paragangliomas (PPGL). The significance of omics in understanding features of PPGL biology that might translate to improved diagnosis and treatment will be highlighted.

Targeting mitochondrial metabolism with CPI-613 in chemoresistant ovarian tumors

BACKGROUND

There is evidence indicating that chemoresistance in tumor cells is mediated by the reconfiguration of the tricarboxylic acid cycle, leading to heightened mitochondrial activity and oxidative phosphorylation (OXPHOS). Previously, we have shown that ovarian cancer cells that are resistant to chemotherapy display increased OXPHOS, mitochondrial function, and metabolic flexibility. To exploit this weakness in chemoresistant ovarian cancer cells, we examined the effectiveness of the mitochondrial inhibitor CPI-613 in treating preclinical ovarian cancer.

METHODS

Chemosensitive OVCAR3, and chemoresistant CAOV3 and F2 ovarian cancer cells lines and their xenografts in nude mice were used. Functional metabolic studies were performed using Seahorse instrument. Metabolite quantification was performed using LC/MS/MS.

RESULTS

Mice treated with CPI-613 exhibited a notable increase in overall survival and a reduction in tumor development and burden in OVCAR3, F2, and CAOV3 xenografts. CPI-613 suppressed the activity of pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase complex, which are two of its targets. This led to a reduction in OXPHOS and tricarboxylic acid cycle activity in all 3 xenografts. The addition of CPI-613 enhanced the responsiveness of chemotherapy in the chemoresistant F2 and CAOV3 tumors, resulting in a notable improvement in survival rates and a reduction in tumor size as compared to using chemotherapy alone. CPI-613 reduced the chemotherapy-induced OXPHOS in chemoresistant tumors. The study revealed that the mechanism by which CPI-613 inhibits tumor growth is through mitochondrial collapse. This is evidenced by an increase in superoxide production within the mitochondria, a decrease in ATP generation, and the release of cytochrome C, which triggers mitochondria-induced apoptosis.

CONCLUSION

Our study demonstrates the translational potential of CPI-613 against chemoresistant ovarian tumors.

Altered metabolism in cancer: insights into energy pathways and therapeutic targets

Cancer cells undergo significant metabolic reprogramming to support their rapid growth and survival. This study examines important metabolic pathways like glycolysis, oxidative phosphorylation, glutaminolysis, and lipid metabolism, focusing on how they are regulated and their contributions to the development of tumors. The interplay between oncogenes, tumor suppressors, epigenetic modifications, and the tumor microenvironment in modulating these pathways is examined. Furthermore, we discuss the therapeutic potential of targeting cancer metabolism, presenting inhibitors of glycolysis, glutaminolysis, the TCA cycle, fatty acid oxidation, LDH, and glucose transport, alongside emerging strategies targeting oxidative phosphorylation and lipid synthesis. Despite the promise, challenges such as metabolic plasticity and the need for combination therapies and robust biomarkers persist, underscoring the necessity for continued research in this dynamic field.

Functional implications of fumarate-induced cysteine succination

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

Exploring the impact of flavin homeostasis on cancer cell metabolism

Flavins and their associated proteins have recently emerged as compelling players in the landscape of cancer biology. Flavins, encompassing flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), serve as coenzymes in a multitude of cellular processes, such as metabolism, apoptosis, and cell proliferation. Their involvement in oxidative phosphorylation, redox homeostasis, and enzymatic reactions has long been recognized. However, recent research has unveiled an extended role for flavins in the context of cancer. In parallel, riboflavin transporters (RFVTs), FAD synthase (FADS), and riboflavin kinase (RFK) have gained prominence in cancer research. These proteins, responsible for riboflavin uptake, FAD biosynthesis, and FMN generation, are integral components of the cellular machinery that governs flavin homeostasis. Dysregulation in the expression/function of these proteins has been associated with various cancers, underscoring their potential as diagnostic markers, therapeutic targets, and key determinants of cancer cell behavior. This review embarks on a comprehensive exploration of the multifaceted role of flavins and of the flavoproteins involved in nucleus-mitochondria crosstalk in cancer. We journey through the influence of flavins on cancer cell energetics, the modulation of RFVTs in malignant transformation, the diagnostic and prognostic significance of FADS, and the implications of RFK in drug resistance and apoptosis. This review also underscores the potential of these molecules and processes as targets for novel diagnostic and therapeutic strategies, offering new avenues for the battle against this relentless disease.

Tumor Metabolism: A New Field for the Treatment of Glioma

The clinical treatment of glioma remains relatively immature. Commonly used clinical treatments for gliomas are surgery combined with chemotherapy and radiotherapy, but there is a problem of drug resistance. In addition, immunotherapy and targeted therapies also suffer from the problem of immune evasion. The advent of metabolic therapy holds immense potential for advancing more efficacious and tolerable therapies against this aggressive disease. Metabolic therapy alters the metabolic processes of tumor cells at the molecular level to inhibit tumor growth and spread, and lead to better outcomes for patients with glioma that are insensitive to conventional treatments. Moreover, compared with conventional therapy, it has less impact on normal cells, less toxicity and side effects, and higher safety. The objective of this review is to examine the changes in metabolic characteristics throughout the development of glioma, enumerate the current methodologies employed for studying tumor metabolism, and highlight the metabolic reprogramming pathways of glioma along with their potential molecular mechanisms. Importantly, it seeks to elucidate potential metabolic targets for glioblastoma (GBM) therapy and summarize effective combination treatment strategies based on various studies.

Cytotoxicity and toxicoproteomics analysis of thiazolidinedione exposure in human-derived cardiomyocytes

Thiazolidinediones (TZDs) (e.g. pioglitazone and rosiglitazone), known insulin sensitiser agents for type II diabetes mellitus, exhibit controversial effects on cardiac tissue. Despite consensus on their association with increased heart failure risk, limiting TZD use in diabetes management, the underlying mechanisms remain uncharacterised. Herein, we report a comprehensive in vitro investigation utilising a novel toxicoproteomics pipeline coupled with cytotoxicity assays in human adult cardiomyocytes to elucidate mechanistic insights into TZD cardiotoxicity. The cytotoxicity assay findings showed a significant loss of mitochondrial adenosine triphosphate production upon exposure to either TZD agents, which may underpin TZD cardiotoxicity. Our toxicoproteomics analysis revealed that mitochondrial dysfunction primarily stems from oxidative phosphorylation impairment, with distinct signalling mechanisms observed for both agents. The type of cell death differed strikingly between the two agents, with rosiglitazone exhibiting features of caspase-dependent apoptosis and pioglitazone implicating mitochondrial-mediated necroptosis, as evidenced by the protein upregulation in the phosphoglycerate mutase family 5-dynamin-related protein 1 axis. Furthermore, our analysis revealed additional mechanistic aspects of cardiotoxicity, showcasing drug specificity. The downregulation of various proteins involved in protein machinery and protein processing in the endoplasmic reticulum was observed in rosiglitazone-treated cells, implicating proteostasis in the rosiglitazone cardiotoxicity. Regarding pioglitazone, the findings suggested the potential activation of the interplay between the complement and coagulation systems and the disruption of the cytoskeletal architecture, which was primarily mediated through the integrin-signalling pathways responsible for pioglitazone-induced myocardial contractile failure. Collectively, this study unlocks substantial mechanistic insight into TZD cardiotoxicity, providing the rationale for future optimisation of antidiabetic therapies.

Metabolic dialogues: regulators of chimeric antigen receptor T cell function in the tumor microenvironment

Tumor-infiltrating lymphocytes (TILs) and chimeric antigen receptor (CAR) T cells have demonstrated remarkable success in the treatment of relapsed/refractory melanoma and hematological malignancies, respectively. These treatments have marked a pivotal shift in cancer management. However, as "living drugs," their effectiveness is dependent on their ability to proliferate and persist in patients. Recent studies indicate that the mechanisms regulating these crucial functions, as well as the T cell's differentiation state, are conditioned by metabolic shifts and the distinct utilization of metabolic pathways. These metabolic shifts, conditioned by nutrient availability as well as cell surface expression of metabolite transporters, are coupled to signaling pathways and the epigenetic landscape of the cell, modulating transcriptional, translational, and post-translational profiles. In this review, we discuss the processes underlying the metabolic remodeling of activated T cells, the impact of a tumor metabolic environment on T cell function, and potential metabolic-based strategies to enhance T cell immunotherapy.

Case report: successful response to bevacizumab combined with erlotinib for a novel FH gene mutation hereditary leiomyoma and renal cell carcinoma

FH-deficient Renal Cell Carcinoma (FH-deficient RCC) are inherited tumors caused by mutations in the fumarate hydratase (FH) gene, which plays a role in the tricarboxylic acid cycle. These mutations often result in aggressive forms of renal cell carcinoma (RCC) and other tumors. Here, we present a case of FH-deficient RCC in a 43-year-old woman with a history of uterine fibroids. She exhibited a new heterozygous mutation in exon six of the FH gene (c.799_803del, c.781_796del). The patient had multiple bone metastases and small subcutaneous nodules in various areas such as the shoulders, back, and buttocks. Biopsy of a subcutaneous nodule on the right side revealed positive expression of 2-succinate-cysteine (2SC), and FH staining indicated FH expression deletion. The patient underwent treatment with a combination of erlotinib and bevacizumab, which resulted in significant efficacy with moderate side effects. This treatment combination may be recommended as a standard regimen. This case underscores the importance of genetic testing in patients with advanced renal cancer to enhance diagnostic accuracy. Furthermore, it provides insights into potential treatment approaches for FH-deficient RCC.

Stage-Specific Alteration and Prognostic Relationship of Serum Fumarate Hydratase Autoantibodies in Gastric Cancer

The relationship between energy production and cancer is attracting attention. This study aimed to investigate the clinicopathological significance of fumarate hydratase (FH), a tricarboxylic acid cycle enzyme, in gastric cancer using autoantibodies as biomarkers. The study analyzed 116 patients who underwent gastric cancer surgery and 96 healthy controls. Preoperative serum FH autoantibody (s-FH-Ab) titers were analyzed using an immunosorbent assay with an amplified luminescent proximity homogeneous assay. Receiver operating characteristic analysis was used to determine the cutoff s-FH-Ab titer. Clinicopathological factors and prognosis were compared between the high and low s-FH-Ab groups. The s-FH-Ab levels were significantly higher in the gastric cancer group than in the control group (p = 0.01). Levels were elevated even in patients with stage I gastric cancer compared with healthy controls (p = 0.02). A low s-FH-Ab level was significantly associated with distant metastasis (p = 0.01), peritoneal dissemination (p < 0.05), and poor overall survival (p < 0.01). Multivariate analysis revealed that low s-FH-Ab levels were an independent risk factor for poor prognosis (p < 0.01). Therefore, s-FH-Ab levels may be a useful biomarker for early diagnosis and the prediction of prognosis in patients with gastric cancer.

Metabolic regulation of type I interferon production

Over the past decade, there has been a surge in discoveries of how metabolic pathways regulate immune cell function in health and disease, establishing the field of immunometabolism. Specifically, pathways such as glycolysis, the tricarboxylic acid (TCA) cycle, and those involving lipid metabolism have been implicated in regulating immune cell function. Viral infections cause immunometabolic changes which lead to antiviral immunity, but little is known about how metabolic changes regulate interferon responses. Interferons are critical cytokines in host defense, rapidly induced upon pathogen recognition, but are also involved in autoimmune diseases. This review summarizes how metabolic change impacts interferon production. We describe how glycolysis, lipid metabolism (specifically involving eicosanoids and cholesterol), and the TCA cycle-linked intermediates itaconate and fumarate impact type I interferons. Targeting these metabolic changes presents new therapeutic possibilities to modulate type I interferons during host defense or autoimmune disorders.

Fumarate Hydratase Enhances the Therapeutic Effect of PD-1 Antibody in Colorectal Cancer by Regulating PCSK9

Despite the notable achievements of programmed death 1 (PD-1) antibodies in treating various cancers, the overall efficacy remains limited in the majority of colorectal cancer (CRC) cases. Metabolism reprogramming of tumors inhibits the tricarboxylic acid (TCA) cycle, leading to down-regulation of fumarate hydratase (FH), which is related to poor prognosis in CRC patients. By establishing a tumor-bearing mouse model of CRC with Fh1 expression deficiency, we confirmed that the therapeutic effect of PD-1 antibodies alone was suboptimal in mice with low Fh1 expression, which was improved by combination with a protein invertase subtilisin/kexin 9 (PCSK9) inhibitor. Mechanistically, FH binds to Ras-related nucleoprotein (RAN), which inhibits the nuclear import of the PCSK9 transcription factor SREBF1/2, thus reducing the expression of PCSK9. This leads to increased clonal expansion of CD8+ T cells while the number of Tregs remains unchanged, and the expression of PD-L1 does not change significantly, thus enhancing the immunotherapy response. On the contrary, the expression of PCSK9 increased in CRC cells with low FH expression, which antagonized the effects of immunotherapy. Overall, CRC patients with low FH expression may benefit from combinatorial therapy with PD-1 antibodies and PCSK9 inhibitors to enhance the curative effect.

Cancer metabolism and carcinogenesis

Metabolic reprogramming is an emerging hallmark of cancer cells, enabling them to meet increased nutrient and energy demands while withstanding the challenging microenvironment. Cancer cells can switch their metabolic pathways, allowing them to adapt to different microenvironments and therapeutic interventions. This refers to metabolic heterogeneity, in which different cell populations use different metabolic pathways to sustain their survival and proliferation and impact their response to conventional cancer therapies. Thus, targeting cancer metabolic heterogeneity represents an innovative therapeutic avenue with the potential to overcome treatment resistance and improve therapeutic outcomes. This review discusses the metabolic patterns of different cancer cell populations and developmental stages, summarizes the molecular mechanisms involved in the intricate interactions within cancer metabolism, and highlights the clinical potential of targeting metabolic vulnerabilities as a promising therapeutic regimen. We aim to unravel the complex of metabolic characteristics and develop personalized treatment approaches to address distinct metabolic traits, ultimately enhancing patient outcomes.

Basic Mechanisms of Immunometabolites in Shaping the Immune Response

BACKGROUND

Innate immune cells play a crucial role in responding to microbial infections, but their improper activation can also drive inflammatory disease. For this reason, their activation state is governed by a multitude of factors, including the metabolic state of the cell and, more specifically, the individual metabolites which accumulate intracellularly and extracellularly. This relationship is bidirectional, as innate immune cell activation by pathogen-associated molecular patterns causes critical changes in cellular metabolism.

SUMMARY

In this review, we describe the emergence of various "immunometabolites." We outline the general characteristics of these immunometabolites, the conditions under which they accumulate, and their subsequent impact on immune cells. We delve into well-studied metabolites of recent years, such as succinate and itaconate, as well as newly emerging immunometabolites, such as methylglyoxal.

KEY MESSAGES

We hope that this review may be used as a framework for further studies dissecting the mechanisms by which immunometabolites regulate the immune system and provide an outlook to harnessing these mechanisms in the treatment of inflammatory diseases.