Myc-dependent mitochondrial generation of acetyl-CoA contributes to fatty acid biosynthesis and histone acetylation during cell cycle entry

Molecular mechanisms of viral oncogenesis in haematological malignancies: perspectives from metabolic reprogramming, epigenetic regulation and immune microenvironment remodeling

Haematological malignancies are one of the most common tumors, with a rising incidence noted over recent decades. Viral infections play significant roles in the pathogenesis of these malignancies globally. This review delves into the contributions of various known viruses-specifically Epstein-Barr virus (EBV), human immunodeficiency virus (HIV), human T-cell leukemia virus type 1 (HTLV-1), Kaposi's sarcoma-associated herpesvirus (KSHV), human cytomegalovirus (HCMV), hepatitis B virus (HBV), hepatitis C virus (HCV), and human papillomavirus (HPV)-in the development of haematological malignancies. These viruses are shown to drive tumorigenesis through mechanisms, such as metabolic reprogramming, epigenetic modifications, and remodeling of the immune microenvironment. By directly disrupting fundamental cellular functions and altering metabolic and epigenetic pathways, these viruses foster an immune milieu that supports both viral persistence and tumor growth. A thorough understanding of these viral oncogenic processes is crucial not only for etiological discovery but also for developing targeted interventions. This review emphasizes the need for continued research into the specific ways these viruses manipulate the host cell's metabolic and epigenetic environments, aiming to provide insights that could guide future advancements in treatment modalities.

Mitochondria - the CEO of the cell

As we have learned more about mitochondria over the past decades, including about their essential cellular roles and how altered mitochondrial biology results in disease, it has become apparent that they are not just powerplants pumping out ATP at the whim of the cell. Rather, mitochondria are dynamic information and energy processors that play crucial roles in directing dozens of cellular processes and behaviors. They provide instructions to enact programs that regulate various cellular operations, such as complex metabolic networks, signaling and innate immunity, and even control cell fate, dictating when cells should divide, differentiate or die. To help current and future generations of cell biologists incorporate the dynamic, multifaceted nature of mitochondria and assimilate modern discoveries into their scientific framework, mitochondria need a 21st century 'rebranding'. In this Opinion article, we argue that mitochondria should be considered as the 'Chief Executive Organelle' - the CEO - of the cell.

Myc family proteins: Molecular drivers of tumorigenesis and resistance in neuroendocrine tumors

Neuroendocrine cancers are a diverse and poorly understood collection of malignancies derived from neuroendocrine cells throughout the body. These cancers uniquely exhibit properties of both the nervous and endocrine systems. Only a limited number of genetic driver mutations have been identified in neuroendocrine cancers, however the mechanisms of how these genetic aberrations alter tumor biology remain elusive. Recent studies have implicated the MYC family of transcription factors as important oncogenic factors in neuroendocrine tumors. We take a systematic approach to understand the roles of the MYC family (c-MYC, n-MYC, l-MYC) in the tumorigenesis of neuroendocrine cancers of the lung, GI tract, pancreas, kidney, prostate, pediatric neuroblastoma, and adrenal glands. Reflecting the complexity of neuroendocrine cancers, we highlight the roles of the MYC family in deregulating the cell cycle and transcriptional networks, invoking cellular plasticity, affecting proliferation capacity, aiding in chromatin remodeling, angiogenesis, metabolic changes, and resistance mechanisms. Depicting the diversity of neuroendocrine cancers, we suggest new approaches in understanding the underlying tumorigenic processes of neuroendocrine cancers from the perspective of MYC.

Solute Carrier Family 35 A2 (SLC35A2) Promotes Tumor Progression through MYC-Mediated Pathways in Colorectal Cancer

Colorectal cancer (CRC) is one of the most prevalent cancers, posing a significant threat to human life. Although therapeutic approaches for advanced-stage patients have improved in recent years, there is still room for enhancing treatment response. Recent evidence suggests that dysregulation of nucleotide sugar transporters (NSTs) is associated with the development and progression of tumors. Therefore, this study aims to explore the potential therapeutic and prognostic implications of the solute carrier family 35 A (SLC35A) members in CRC. To achieve this, we performed integrative bioinformatics analysis using various publicly available databases, including GENT2, TCGA, UALCAN, cBioPortal, Kaplan-Meier plotter, The ROC plotter, GDSC, TISIDB, and TIMER. We compared gene expression profiles between CRC tumors and adjacent normal tissues, revealing that only SLC35A2 exhibited significant upregulation in tumors, while the other family members were downregulated. Additionally, higher SLC35A2 expression was found in microsatellite stable (MSS) colorectal tumors. Further analysis of TCGA and GEO datasets showed that patients with high SLC35A2 expression experienced poorer relapse-free survival. Next, we conducted gene set enrichment analysis (GSEA), and the results indicated that the upregulation of SLC35A2 is linked to cellular metabolism pathways, such as MYC Targets V2, Steroid Biosynthesis, Pentose Phosphate Pathway, and TCA Cycle. Furthermore, our CRC cell models revealed the tumor-promoting role of SLC35A2 and discovered that the upregulation of SLC35A2 is associated with chemoresistance against irinotecan. Additionally, we observed a negative correlation between SLC35A2 expression and the infiltration of immune cells, particularly cytotoxic CD8+ T cells and B cells. This suggests the immunomodulatory role of SLC35A2. In summary, SLC35A2 is abnormally upregulated in CRC, and patients with high SLC35A2 expression tend to have poor relapse-free survival. This may be due to its involvement in regulating cancer cell metabolic reprogramming, promoting tumor progression, modulating the immune landscape, and influencing treatment response. Consequently, SLC35A2 could serve as a significant prognostic factor and a potential therapeutic target in CRC.

Brain Plasticity and Cell Competition: Immediate Early Genes Are the Focus

Brain plasticity is at the basis of many cognitive functions, including learning and memory. It includes several mechanisms of synaptic and extrasynaptic changes, neurogenesis, and the formation and elimination of synapses. The plasticity of synaptic transmission involves the expression of immediate early genes (IEGs) that regulate neuronal activity, thereby supporting learning and memory. In addition, IEGs are involved in the regulation of brain cells' metabolism, proliferation, and survival, in the establishment of multicellular ensembles, and, presumably, in cell competition in the tissue. In this review, we analyze the current understanding of the role of IEGs (c-Fos, c-Myc, Arg3.1/Arc) in controlling brain plasticity in physiological and pathological conditions, including brain aging and neurodegeneration. This work might inspire new gene therapy strategies targeting IEGs to regulate synaptic plasticity, and potentially prevent or mitigate neurodegenerative diseases.

Hematological and Biochemical Characteristics Associated with Cytogenetic Findern Alterations in Adult Patients with Acute Lymphoblastic Leukemia (ALL) from the Northern Region of Brazil

Acute lymphoblastic leukemia (ALL) is an aggressive neoplasm derived from B and/or T cell lineage (B-ALL; T-ALL). For the first time, this study describes, cytogenetically, the karyotypic alterations in adults with ALL in the northern region of Brazil and their relationship with hematological and biochemical characteristics. Through banding analyses, immunophenotyping, as well as hematological and biochemical examination data obtained directly from patients' records, we found that chromosome 21 aneuploidy was the most frequent. The cytogenetic structural alterations observed with the highest incidence among the patients were: t(9;22), t(4;11), t(1;19), del(6q), and del(9p). In patients presenting with chromosome alterations, we verified that patients with t(4;11) have elevated red blood cell levels and patients with del(9p) presented with distinct and high values of hematological parameters compared to other patients. Regarding biochemical alterations, we observed that patients with translocations (4;11) and del(6q) presented with elevated urea levels compared to other patients, highlighting its relationship to kidney changes and patient prognosis. Thus, our study highlights that variations in hematological and biochemical data are associated with specific cytogenetic changes and other factors, which may impact the prognosis of adult patients with ALL.

Challenges of Spatially Resolved Metabolism in Cancer Research

Stable isotope-resolved metabolomics comprises a critical set of technologies that can be applied to a wide variety of systems, from isolated cells to whole organisms, to define metabolic pathway usage and responses to perturbations such as drugs or mutations, as well as providing the basis for flux analysis. As the diversity of stable isotope-enriched compounds is very high, and with newer approaches to multiplexing, the coverage of metabolism is now very extensive. However, as the complexity of the model increases, including more kinds of interacting cell types and interorgan communication, the analytical complexity also increases. Further, as studies move further into spatially resolved biology, new technical problems have to be overcome owing to the small number of analytes present in the confines of a single cell or cell compartment. Here, we review the overall goals and solutions made possible by stable isotope tracing and their applications to models of increasing complexity. Finally, we discuss progress and outstanding difficulties in high-resolution spatially resolved tracer-based metabolic studies.

Plasma metabolites in childhood Burkitt lymphoma cases and cancer-free controls in Uganda

INTRODUCTION

Burkitt lymphoma (BL) is an aggressive non-Hodgkin lymphoma associated with Plasmodium falciparum and Epstein-Barr virus, both of which affect metabolic pathways. The metabolomic patterns of BL is unknown.

MATERIALS AND METHODS

We measured 627 metabolites in pre-chemotherapy treatment plasma samples from 25 male children (6-11 years) with BL and 25 cancer-free area- and age-frequency-matched male controls from the Epidemiology of Burkitt Lymphoma in East African Children and Minors study in Uganda using liquid chromatography-tandem mass spectrometry. Unconditional, age-adjusted logistic regression analysis was used to estimate odds ratios (ORs) and their 95% confidence intervals (CIs) for the BL association with 1-standard deviation increase in the log-metabolite concentration, adjusting for multiple comparisons using false discovery rate (FDR) thresholds and Bonferroni correction.

RESULTS

Compared to controls, levels for 42 metabolite concentrations differed in BL cases (FDR < 0.001), including triacylglyceride (18:0_38:6), alpha-aminobutyric acid (AABA), ceramide (d18:1/20:0), phosphatidylcholine ae C40:6 and phosphatidylcholine C38:6 as the top signals associated with BL (ORs = 6.9 to 14.7, P < 2.4✕10- 4). Two metabolites (triacylglyceride (18:0_38:6) and AABA) selected using stepwise logistic regression discriminated BL cases from controls with an area under the curve of 0.97 (95% CI: 0.94, 1.00).

CONCLUSION

Our findings warrant further examination of plasma metabolites as potential biomarkers for BL risk/diagnosis.

Effect of low ethanol concentration in maturation medium on developmental ability, mitochondria, and gene expression profile in mouse oocytes

Ethanol affects pre-conceptional oocyte quality in women. In this study, we examined the effect of low ethanol concentrations on mouse oocytes. Oocytes were collected from the ovaries of 9-10 week old mice and allowed to mature in vitro in the presence of low concentrations of ethanol (0.1% and 0.2% v/v) for 24 h. Treatment of oocytes with ethanol (0.2%) during maturation decreased the mitochondrial DNA content and membrane potential compared to that in untreated ones, whereas the ATP content did not differ between the groups. Both 0.1% and 0.2% ethanol reduced the lipid content in the oocytes. In addition, immunostaining revealed that oocytes cultured in maturation medium containing ethanol (0.2%) had reduced levels of global DNA methylation and DNMT3A compared with untreated oocytes, and decreased rate of blastocyst development with low mitochondrial protein levels (TOMM40) in embryo. RNA-sequencing of the ethanol-treated (0.2%) and untreated oocytes revealed that mitochondria were a major target of ethanol. In conclusion, treatment of oocytes with low concentration of ethanol reduces the developmental rate to the blastocyst stage, with a lower total cell number and global DNA methylation. In addition, ethanol affected mitochondrial function and mitochondria-related gene expression.

Targeting DNMT3A-mediated oxidative phosphorylation to overcome ibrutinib resistance in mantle cell lymphoma

The use of Bruton tyrosine kinase (BTK) inhibitors such as ibrutinib achieves a remarkable clinical response in mantle cell lymphoma (MCL). Acquired drug resistance, however, is significant and affects long-term survival of MCL patients. Here, we demonstrate that DNA methyltransferase 3A (DNMT3A) is involved in ibrutinib resistance. We find that DNMT3A expression is upregulated upon ibrutinib treatment in ibrutinib-resistant MCL cells. Genetic and pharmacological analyses reveal that DNMT3A mediates ibrutinib resistance independent of its DNA-methylation function. Mechanistically, DNMT3A induces the expression of MYC target genes through interaction with the transcription factors MEF2B and MYC, thus mediating metabolic reprogramming to oxidative phosphorylation (OXPHOS). Targeting DNMT3A with low-dose decitabine inhibits the growth of ibrutinib-resistant lymphoma cells both in vitro and in a patient-derived xenograft mouse model. These findings suggest that targeting DNMT3A-mediated metabolic reprogramming to OXPHOS with decitabine provides a potential therapeutic strategy to overcome ibrutinib resistance in relapsed/refractory MCL.

MYC Oncogene: A Druggable Target for Treating Cancers with Natural Products

Various diseases, including cancers, age-associated disorders, and acute liver failure, have been linked to the oncogene, MYC. Animal testing and clinical trials have shown that sustained tumor volume reduction can be achieved when MYC is inactivated, and different combinations of therapeutic agents including MYC inhibitors are currently being developed. In this review, we first provide a summary of the multiple biological functions of the MYC oncoprotein in cancer treatment, highlighting that the equilibrium points of the MYC/MAX, MIZ1/MYC/MAX, and MAD (MNT)/MAX complexes have further potential in cancer treatment that could be used to restrain MYC oncogene expression and its functions in tumorigenesis. We also discuss the multifunctional capacity of MYC in various cellular cancer processes, including its influences on immune response, metabolism, cell cycle, apoptosis, autophagy, pyroptosis, metastasis, angiogenesis, multidrug resistance, and intestinal flora. Moreover, we summarize the MYC therapy patent landscape and emphasize the potential of MYC as a druggable target, using herbal medicine modulators. Finally, we describe pending challenges and future perspectives in biomedical research, involving the development of therapeutic approaches to modulate MYC or its targeted genes. Patients with cancers driven by MYC signaling may benefit from therapies targeting these pathways, which could delay cancerous growth and recover antitumor immune responses.

Prostate lineage-specific metabolism governs luminal differentiation and response to antiandrogen treatment

Lineage transitions are a central feature of prostate development, tumourigenesis and treatment resistance. While epigenetic changes are well known to drive prostate lineage transitions, it remains unclear how upstream metabolic signalling contributes to the regulation of prostate epithelial identity. To fill this gap, we developed an approach to perform metabolomics on primary prostate epithelial cells. Using this approach, we discovered that the basal and luminal cells of the prostate exhibit distinct metabolomes and nutrient utilization patterns. Furthermore, basal-to-luminal differentiation is accompanied by increased pyruvate oxidation. We establish the mitochondrial pyruvate carrier and subsequent lactate accumulation as regulators of prostate luminal identity. Inhibition of the mitochondrial pyruvate carrier or supplementation with exogenous lactate results in large-scale chromatin remodelling, influencing both lineage-specific transcription factors and response to antiandrogen treatment. These results establish reciprocal regulation of metabolism and prostate epithelial lineage identity.

Lessons in aging from Myc knockout mouse models

Despite MYC being among the most intensively studied oncogenes, its role in normal development has not been determined as Myc-/- mice do not survival beyond mid-gestation. Myc ± mice live longer than their wild-type counterparts and are slower to accumulate many age-related phenotypes. However, Myc haplo-insufficiency likely conceals other important phenotypes as many high-affinity Myc targets genes continue to be regulated normally. By delaying Myc inactivation until after birth it has recently been possible to study the consequences of its near-complete total body loss and thus to infer its normal function. Against expectation, these "MycKO" mice lived significantly longer than control wild-type mice but manifested a marked premature aging phenotype. This seemingly paradoxical behavior was potentially explained by a >3-fold lower lifetime incidence of cancer, normally the most common cause of death in mice and often Myc-driven. Myc loss accelerated the accumulation of numerous "Aging Hallmarks", including the loss of mitochondrial and ribosomal structural and functional integrity, the generation of reactive oxygen species, the acquisition of genotoxic damage, the detrimental rewiring of metabolism and the onset of senescence. In both mice and humans, normal aging in many tissues was accompaniued by the downregulation of Myc and the loss of Myc target gene regulation. Unlike most mouse models of premature aging, which are based on monogenic disorders of DNA damage recognition and repair, the MycKO mouse model directly impacts most Aging Hallmarks and may therefore more faithfully replicate the normal aging process of both mice and humans. It further establishes that the strong association between aging and cancer can be genetically separated and is maintained by a single gene.

Spotlight on New Therapeutic Opportunities for MYC-Driven Cancers

MYC can be considered to be one of the most pressing and important targets for the development of novel anti-cancer therapies. This is due to its frequent dysregulation in tumors and due to the wide-ranging impact this dysregulation has on gene expression and cellular behavior. As a result, there have been numerous attempts to target MYC over the last few decades, both directly and indirectly, with mixed results. This article reviews the biology of MYC in the context of cancers and drug development. It discusses strategies aimed at targeting MYC directly, including those aimed at reducing its expression and blocking its function. In addition, the impact of MYC dysregulation on cellular biology is outlined, and how understanding this can underpin the development of approaches aimed at molecules and pathways regulated by MYC. In particular, the review focuses on the role that MYC plays in the regulation of metabolism, and the therapeutic avenues offered by inhibiting the metabolic pathways that are essential for the survival of MYC-transformed cells.

Maternal obesity and ovarian failure: is leptin the culprit?

At the time of its discovery and characterization in 1994, leptin was mostly considered a metabolic hormone able to regulate body weight and energy homeostasis. However, in recent years, a great deal of literature has revealed leptin's pleiotropic nature, through its involvement in numerous physiological contexts including the regulation of the female reproductive tract and ovarian function. Obesity has been largely associated with infertility, and leptin signalling is known to be dysregulated in the ovaries of obese females. Hence, the disruption of ovarian leptin signalling was shown to contribute to the pathophysiology of ovarian failure in obese females, affecting transcriptional programmes in the gamete and somatic cells. This review attempts to uncover the underlying mechanisms contributing to female infertility associated with obesity, as well as to shed light on the role of leptin in the metabolic dysregulation within the follicle, the effects on the oocyte epigenome, and the potential long-term consequence to embryo programming.

The "Superoncogene" Myc at the Crossroad between Metabolism and Gene Expression in Glioblastoma Multiforme

The concept of the Myc (c-myc, n-myc, l-myc) oncogene as a canonical, DNA-bound transcription factor has consistently changed over the past few years. Indeed, Myc controls gene expression programs at multiple levels: directly binding chromatin and recruiting transcriptional coregulators; modulating the activity of RNA polymerases (RNAPs); and drawing chromatin topology. Therefore, it is evident that Myc deregulation in cancer is a dramatic event. Glioblastoma multiforme (GBM) is the most lethal, still incurable, brain cancer in adults, and it is characterized in most cases by Myc deregulation. Metabolic rewiring typically occurs in cancer cells, and GBM undergoes profound metabolic changes to supply increased energy demand. In nontransformed cells, Myc tightly controls metabolic pathways to maintain cellular homeostasis. Consistently, in Myc-overexpressing cancer cells, including GBM cells, these highly controlled metabolic routes are affected by enhanced Myc activity and show substantial alterations. On the other hand, deregulated cancer metabolism impacts Myc expression and function, placing Myc at the intersection between metabolic pathway activation and gene expression. In this review paper, we summarize the available information on GBM metabolism with a specific focus on the control of the Myc oncogene that, in turn, rules the activation of metabolic signals, ensuring GBM growth.

Metabolic Pathways, Enzymes, and Metabolites: Opportunities in Cancer Therapy

Metabolic reprogramming enables cancer cells to proliferate and produce tumor biomass under a nutrient-deficient microenvironment and the stress of metabolic waste. A cancer cell adeptly undergoes a variety of adaptations in metabolic pathways and differential expression of metabolic enzyme genes. Metabolic adaptation is mainly determined by the physiological demands of the cancer cell of origin and the host tissue. Numerous metabolic regulators that assist cancer cell proliferation include uncontrolled anabolism/catabolism of glucose metabolism, fatty acids, amino acids metabolism, nucleotide metabolism, tumor suppressor genes, microRNAs, and many regulatory enzymes and genes. Using this paradigm, we review the current understanding of metabolic reprogramming in tumors and discuss the new strategies of cancer metabolomics that can be tapped into for cancer therapeutics.

Targeting metabolic reprogramming in chronic lymphocytic leukemia

Metabolic reprogramming, fundamentally pivotal in carcinogenesis and progression of cancer, is considered as a promising therapeutic target against tumors. In chronic lymphocytic leukemia (CLL) cells, metabolic abnormalities mediate alternations in proliferation and survival compared with normal B cells. However, the role of metabolic reprogramming is still under investigation in CLL. In this review, the critical metabolic processes of CLL were summarized, particularly glycolysis, lipid metabolism and oxidative phosphorylation. The effects of T cells and stromal cells in the microenvironment on metabolism of CLL were also elucidated. Besides, the metabolic alternation is regulated by some oncogenes and tumor suppressor regulators, especially TP53, MYC and ATM. Thus, the agents targeting metabolic enzymes or signal pathways may impede the progression of CLL. Both the inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) statins and the lipoprotein lipase inhibitor orlistat induce the apoptosis of CLL cells. In addition, a series of oxidative phosphorylation inhibitors play important roles in decreasing the proliferation of CLL cells. We epitomized recent advancements in metabolic reprogramming in CLL and discussed their clinical potentiality for innovative therapy options. Metabolic reprogramming plays a vital role in the initiation and progression of CLL. Therapeutic approaches targeting metabolism have their advantages in improving the survival of CLL patients. This review may shed novel light on the metabolism of CLL, leading to the development of targeted agents based on the reshaping metabolism of CLL cells.

Obesity, the other pandemic: linking diet and carcinogenesis by epigenetic mechanisms

Both obesity and cancer are complex medical conditions that are considered public health problems. The influence of obesity on the predisposition to develop various types of cancer has been observed in a wide variety of studies. Due to their importance as public health problems, and the close relationship between both conditions, it is important to be able to understand and associate them mechanistically. In this review article, we intend to go a little further, by finding relationships between lifestyle, which can lead a person to develop obesity, and how it influences at the cellular and molecular level, affecting gene expression to favor signaling pathways or transcriptional programs involved in cancer. We describe how products of metabolism and intermediate metabolism can affect chromatin structure, participating in the regulation (or dysregulation) of gene expression, and we show an analysis of genes that are responsive to diets high in sugar and fat, and how their epigenetic landscape is altered.

Metabolic control of oocyte development

Well balanced and timed metabolism is essential for oocyte development. The effects of extrinsic nutrients on oocyte maturation have been widely reported. In contrast, intrinsic control of oogenesis by intracellular metabolites and metabolic enzymes has received little attention. The comprehensive characterization of metabolic patterns could lead to more complete understanding of regulatory mechanisms underlying oocyte development. A cell's metabolic state is integrated with epigenetic regulation. Epigenetic modifications in germ cells are therefore sensitive to parental environmental exposures. Nevertheless, direct genetic evidence for metabolites involvement in epigenetic establishment during oocyte development is still lacking. Moreover, metabolic disorder-induced epigenetic perturbations during oogenesis might mediate the inter/transgenerational effects of environmental insults. The molecular mechanisms responsible for this deserve further investigation. Here, we summarize the findings on metabolic regulation in oocyte maturation, and how it contributes to oocyte epigenetic modification. Finally, we propose a mouse model that metabolic disorder in oocyte serves as a potential factor mediating the maternal environment effects on offspring health.

Cancer cell metabolism connects epigenetic modifications to transcriptional regulation

Adaptation of cellular function with the nutrient environment is essential for survival. Failure to adapt can lead to cell death and/or disease. Indeed, energy metabolism alterations are a major contributing factor for many pathologies, including cancer, cardiovascular disease, and diabetes. In particular, a primary characteristic of cancer cells is altered metabolism that promotes survival and proliferation even in the presence of limited nutrients. Interestingly, recent studies demonstrate that metabolic pathways produce intermediary metabolites that directly influence epigenetic modifications in the genome. Emerging evidence demonstrates that metabolic processes in cancer cells fuel malignant growth, in part, through epigenetic regulation of gene expression programs important for proliferation and adaptive survival. In this review, recent progress toward understanding the relationship of cancer cell metabolism, epigenetic modification, and transcriptional regulation will be discussed. Specifically, the need for adaptive cell metabolism and its modulation in cancer cells will be introduced. Current knowledge on the emerging field of metabolite production and epigenetic modification will also be reviewed. Alterations of DNA (de)methylation, histone modifications, such as (de)methylation and (de)acylation, as well as chromatin remodeling, will be discussed in the context of cancer cell metabolism. Finally, how these epigenetic alterations contribute to cancer cell phenotypes will be summarized. Collectively, these studies reveal that both metabolic and epigenetic pathways in cancer cells are closely linked, representing multiple opportunities to therapeutically target the unique features of malignant growth.

Post-translational modifications on mitochondrial metabolic enzymes in cancer

Mitochondrion is the powerhouse of the cell. The research of nearly a century has expanded our understanding of mitochondrion, far beyond the view that mitochondrion is an important energy generator of cells. During the initiation, growth and survival of tumor cells, significant mitochondrial metabolic changes have taken place in the important enzymes of respiratory chain and tricarboxylic acid cycle, mitochondrial biogenesis and dynamics, oxidative stress regulation and molecular signaling. Therefore, mitochondrial metabolic proteins are the key mediators of tumorigenesis. Post-translational modification is the molecular switch that regulates protein function. Understanding how these mitochondria-related post-translational modification function during tumorigenesis will bring new ideas for the next generation of cancer treatment.

Metabolic Regulation of Lysine Acetylation: Implications in Cancer

Lysine acetylation is the second most well-studied post-translational modification after phosphorylation. While phosphorylation regulates signaling cascades, one of the most significant roles of acetylation is regulation of chromatin structure. Acetyl-coenzyme A (acetyl-CoA) serves as the acetyl group donor for acetylation reactions mediated by lysine acetyltransferases (KATs). On the other hand, NAD+ serves as the cofactor for lysine deacetylases (KDACs). Both acetyl-CoA and NAD+ are metabolites integral to energy metabolism, and therefore, their metabolic flux can regulate the activity of KATs and KDACs impacting the epigenome. In this chapter, we review our current understanding of how metabolic pathways regulate lysine acetylation in normal and cancer cells.

Mannose and phosphomannose isomerase regulate energy metabolism under glucose starvation in leukemia

Diverse metabolic changes are induced by various driver oncogenes during the onset and progression of leukemia. By upregulating glycolysis, cancer cells acquire a proliferative advantage over normal hematopoietic cells; in addition, these changes in energy metabolism contribute to anticancer drug resistance. Because leukemia cells proliferate by consuming glucose as an energy source, an alternative nutrient source is essential when glucose levels in bone marrow are insufficient. We profiled sugar metabolism in leukemia cells and found that mannose is an energy source for glycolysis, the tricarboxylic acid (TCA) cycle, and the pentose phosphate pathway. Leukemia cells express high levels of phosphomannose isomerase (PMI), which mobilizes mannose to glycolysis; consequently, even mannose in the blood can be used as an energy source for glycolysis. Conversely, suppression of PMI expression or a mannose load exceeding the processing capacity of PMI inhibited transcription of genes related to mitochondrial metabolism and the TCA cycle, therefore suppressing the growth of leukemia cells. High PMI expression was also a poor prognostic factor for acute myeloid leukemia. Our findings reveal a new mechanism for glucose starvation resistance in leukemia. Furthermore, the combination of PMI suppression and mannose loading has potential as a novel treatment for driver oncogene-independent leukemia.

Is There a Histone Code for Cellular Quiescence?

Many of the cells in our bodies are quiescent, that is, temporarily not dividing. Under certain physiological conditions such as during tissue repair and maintenance, quiescent cells receive the appropriate stimulus and are induced to enter the cell cycle. The ability of cells to successfully transition into and out of a quiescent state is crucial for many biological processes including wound healing, stem cell maintenance, and immunological responses. Across species and tissues, transcriptional, epigenetic, and chromosomal changes associated with the transition between proliferation and quiescence have been analyzed, and some consistent changes associated with quiescence have been identified. Histone modifications have been shown to play a role in chromatin packing and accessibility, nucleosome mobility, gene expression, and chromosome arrangement. In this review, we critically evaluate the role of different histone marks in these processes during quiescence entry and exit. We consider different model systems for quiescence, each of the most frequently monitored candidate histone marks, and the role of their writers, erasers and readers. We highlight data that support these marks contributing to the changes observed with quiescence. We specifically ask whether there is a quiescence histone “code,” a mechanism whereby the language encoded by specific combinations of histone marks is read and relayed downstream to modulate cell state and function. We conclude by highlighting emerging technologies that can be applied to gain greater insight into the role of a histone code for quiescence.

Unlocking the Role of Exercise on CD4+ T Cell Plasticity

A hallmark of T cell ageing is a loss of effector plasticity. Exercise delays T cell ageing, yet the mechanisms driving the effects of exercise on T cell biology are not well elucidated. T cell plasticity is closely linked with metabolism, and consequently sensitive to metabolic changes induced by exercise. Mitochondrial function is essential for providing the intermediate metabolites necessary to generate and modify epigenetic marks in the nucleus, thus metabolic activity and epigenetic mechanisms are intertwined. In this perspective we propose a role for exercise in CD4+ T cell plasticity, exploring links between exercise, metabolism and epigenetic reprogramming.

Effect of docosahexaenoic acid on in vitro growth of bovine oocytes

PURPOSE

The present study investigated the effects of docosahexaenoic acid (DHA) on the growth of bovine oocytes.

METHODS

Oocytes and granulosa cell complexes (OGCs) were collected from early antral follicles (0.4-0.7 mm) on the surface of ovaries harvested from a slaughterhouse. The OGCs were cultured with 0, 1, and 10 μmol/L docosahexanoic acid (DHA) for 16 days.

RESULTS

Antrum formation of the OGCs and the number of granulosa cells (GCs) surrounding the oocytes were comparable among groups, whereas supplementation of 0.1 μmol/L of DHA significantly improved oocyte growth. Oocytes grown with DHA had a higher fertilization rate, acetylation levels of H4K12, and ATP contents, as well as a lower lipid content compared with those grown without DHA. In addition, GCs surrounding OGCs grown with DHA had low lipid content compared with vehicle counterparts. Furthermore, when GCs were cultured in vitro, DHA increased ATP production, mitochondrial membrane potential, and reduced lipid content and levels of reactive oxygen species. RNA-seq of GCs revealed that DHA increased CPT1A expression levels and affect genes associated with focal adhesion, oxidative phosphorylation, and PI3K-AKT etc.

CONCLUSION

The results suggest that DHA supplementation affects granulosa cell characteristics and supports oocyte growth in vitro.

Effect of disease progression on the podocyte cell cycle in Alport Syndrome

Progression of glomerulosclerosis is associated with loss of podocytes with subsequent glomerular tuft instability. It is thought that a diminished number of podocytes may be able to preserve tuft stability through cell hypertrophy associated with cell cycle reentry. At the same time, reentry into the cell cycle risks podocyte detachment if podocytes cross the G1/S checkpoint and undergo abortive cytokinesis. In order to study cell cycle dynamics during chronic kidney disease (CKD) development, we used a FUCCI model (fluorescence ubiquitination-based cell cycle indicator) of mice with X-linked Alport Syndrome. This model exhibits progressive CKD and expresses fluorescent reporters of cell cycle stage exclusively in podocytes. With the development of CKD, an increasing fraction of podocytes in vivo were found to be in G1 or later cell cycle stages. Podocytes in G1 and G2 were hypertrophic. Heterozygous female mice, with milder manifestations of CKD, showed G1 fraction numbers intermediate between wild-type and male Alport mice. Proteomic analysis of podocytes in different cell cycle phases showed differences in cytoskeleton reorganization and metabolic processes between G0 and G1 in disease. Additionally, in vitro experiments confirmed that damaged podocytes reentered the cell cycle comparable to podocytes in vivo. Importantly, we confirmed the upregulation of PDlim2, a highly expressed protein in podocytes in G1, in a patient with Alport Syndrome, confirming our proteomics data in the human setting. Thus, our data showed that in the Alport model of progressive CKD, podocyte cell cycle distribution is altered, suggesting that cell cycle manipulation approaches may have a role in the treatment of various progressive glomerular diseases characterized by podocytopenia.

Metabolic Profiling during Acute Myeloid Leukemia Progression Using Paired Clinical Bone Marrow Serum Samples

Cellular metabolic changes reflect the characteristics of patients with acute myeloid leukemia (AML) caused by genetic variations, which are important in establishing AML treatment. However, little is known about the metabolic profile of patients with genetic variation-induced AML. Furthermore, the metabolites differ with disease progression. Here, metabolites in the bone marrow serum of ten patients with AML and healthy individuals were analyzed using gas chromatography–mass spectrometry. Compared with that in healthy individuals, expression of most metabolites decreased in patients with AML; hydroxylamine, 2-hydroxybutyric acid, monomethylphosphate, and ethylphosphate expression was unusually increased in the patients. We further examined serial metabolite changes across the initial diagnosis, postremission, and relapse phases. Patients with relapse showed increased metabolite expression compared with those in the diagnostic phase, confirming that patients with AML had aggressively modified leukemic cells. However, a clear difference in metabolite distribution was not observed between the diagnosis and complete remission phases, suggesting that the metabolic microenvironment did not change significantly despite complete remission. Interestingly, metabolite profiles differed with genetic variations in leukemic cells. Our results, which were obtained using paired samples collected during AML progression, provide valuable insights for identifying vulnerable targets in the AML metabolome and developing new treatment strategies.

Epigenetic and metabolic interplay in cutaneous squamous cell carcinoma

With the ageing of the population and increased levels of recreational sun exposure and immunosuppression, cutaneous squamous cell carcinoma (cSCC), is both an enormous and expanding clinical and economic issue. Despite advances in therapy, up to 5000-8000 people are estimated to die every year from cSCC in the U.S., highlighting the need for both better prevention and treatments. Two emerging areas of scientific discovery that may offer new therapeutic approaches for cSCC are epigenetics and metabolism. Importantly, these disciplines display extensive crosstalk, with metabolic inputs contributing to the chromatin landscape, while the dynamic epigenome shapes transcriptional and cellular responses that feedback into cellular metabolism. Recent evidence suggests that indeed, epigenetic and metabolic dysregulation may be critical contributors to cSCC pathogenesis. Here, we synthesize the latest findings from these fast-moving fields, including how they may drive cSCC, yet also be harnessed for therapy.

Metabolic Reprogramming: A Friend or Foe to Cancer Therapy?

Drug resistance is a major cause of cancer treatment failure, effectively driven by processes that promote escape from therapy-induced cell death. The mechanisms driving evasion of apoptosis have been widely studied across multiple cancer types, and have facilitated new and exciting therapeutic discoveries with the potential to improve cancer patient care. However, an increasing understanding of the crosstalk between cancer hallmarks has highlighted the complexity of the mechanisms of drug resistance, co-opting pathways outside of the canonical "cell death" machinery to facilitate cell survival in the face of cytotoxic stress. Rewiring of cellular metabolism is vital to drive and support increased proliferative demands in cancer cells, and recent discoveries in the field of cancer metabolism have uncovered a novel role for these programs in facilitating drug resistance. As a key organelle in both metabolic and apoptotic homeostasis, the mitochondria are at the forefront of these mechanisms of resistance, coordinating crosstalk in the event of cellular stress, and promoting cellular survival. Importantly, the appreciation of this role metabolism plays in the cytotoxic response to therapy, and the ability to profile metabolic adaptions in response to treatment, has encouraged new avenues of investigation into the potential of exploiting metabolic addictions to improve therapeutic efficacy and overcome drug resistance in cancer. Here, we review the role cancer metabolism can play in mediating drug resistance, and the exciting opportunities presented by imposed metabolic vulnerabilities.

Restoration of the molecular clock is tumor suppressive in neuroblastoma

MYCN activation is a hallmark of advanced neuroblastoma (NB) and a known master regulator of metabolic reprogramming, favoring NB adaptation to its microenvironment. We found that the expression of the main regulators of the molecular clock loops is profoundly disrupted in MYCN-amplified NB patients, and this disruption independently predicts poor clinical outcome. MYCN induces the expression of clock repressors and downregulates the one of clock activators by directly binding to their promoters. Ultimately, MYCN attenuates the molecular clock by suppressing BMAL1 expression and oscillation, thereby promoting cell survival. Reestablishment of the activity of the clock activator RORα via its genetic overexpression and its stimulation through the agonist SR1078, restores BMAL1 expression and oscillation, effectively blocks MYCN-mediated tumor growth and de novo lipogenesis, and sensitizes NB tumors to conventional chemotherapy. In conclusion, reactivation of RORα could serve as a therapeutic strategy for MYCN-amplified NBs by blocking the dysregulation of molecular clock and cell metabolism mediated by MYCN.

Local production of lactate, ribose phosphate, and amino acids within human triple-negative breast cancer

BACKGROUND

Upregulated glucose metabolism is a common feature of tumors. Glucose can be broken down by either glycolysis or the oxidative pentose phosphate pathway (oxPPP). The relative usage within tumors of these catabolic pathways remains unclear. Similarly, the extent to which tumors make biomass precursors from glucose, versus take them up from the circulation, is incompletely defined.

METHODS

We explore human triple negative breast cancer (TNBC) metabolism by isotope tracing with [1,2-13C]glucose, a tracer that differentiates glycolytic versus oxPPP catabolism and reveals glucose-driven anabolism. Patients enrolled in clinical trial NCT03457779 and received IV infusion of [1,2-13C]glucose during core biopsy of their primary TNBC. Tumor samples were analyzed for metabolite labeling by liquid chromatography-mass spectrometry (LC-MS). Genomic and proteomic analyses were performed and related to observed metabolic fluxes.

FINDINGS

TNBC ferments glucose to lactate, with glycolysis dominant over the oxPPP. Most ribose phosphate is nevertheless produced by oxPPP. Glucose also feeds amino acid synthesis, including of serine, glycine, aspartate, glutamate, proline and glutamine (but not asparagine). Downstream in glycolysis, tumor pyruvate and lactate labeling exceeds that found in serum, indicating that lactate exchange via monocarboxylic transporters is less prevalent in human TNBC compared with most normal tissues or non-small cell lung cancer.

CONCLUSIONS

Glucose directly feeds ribose phosphate, amino acid synthesis, lactate, and the TCA cycle locally within human breast tumors.

Metabolic reprogramming and epigenetic modifications on the path to cancer

Metabolic rewiring and epigenetic remodeling, which are closely linked and reciprocally regulate each other, are among the well-known cancer hallmarks. Recent evidence suggests that many metabolites serve as substrates or cofactors of chromatin-modifying enzymes as a consequence of the translocation or spatial regionalization of enzymes or metabolites. Various metabolic alterations and epigenetic modifications also reportedly drive immune escape or impede immunosurveillance within certain contexts, playing important roles in tumor progression. In this review, we focus on how metabolic reprogramming of tumor cells and immune cells reshapes epigenetic alterations, in particular the acetylation and methylation of histone proteins and DNA. We also discuss other eminent metabolic modifications such as, succinylation, hydroxybutyrylation, and lactylation, and update the current advances in metabolism- and epigenetic modification-based therapeutic prospects in cancer.

Metabolic Control by DNA Tumor Virus-Encoded Proteins

Viruses co-opt a multitude of host cell metabolic processes in order to meet the energy and substrate requirements for successful viral replication. However, due to their limited coding capacity, viruses must enact most, if not all, of these metabolic changes by influencing the function of available host cell regulatory proteins. Typically, certain viral proteins, some of which can function as viral oncoproteins, interact with these cellular regulatory proteins directly in order to effect changes in downstream metabolic pathways. This review highlights recent research into how four different DNA tumor viruses, namely human adenovirus, human papillomavirus, Epstein-Barr virus and Kaposi's associated-sarcoma herpesvirus, can influence host cell metabolism through their interactions with either MYC, p53 or the pRb/E2F complex. Interestingly, some of these host cell regulators can be activated or inhibited by the same virus, depending on which viral oncoprotein is interacting with the regulatory protein. This review highlights how MYC, p53 and pRb/E2F regulate host cell metabolism, followed by an outline of how each of these DNA tumor viruses control their activities. Understanding how DNA tumor viruses regulate metabolism through viral oncoproteins could assist in the discovery or repurposing of metabolic inhibitors for antiviral therapy or treatment of virus-dependent cancers.

MYC Enhances Cholesterol Biosynthesis and Supports Cell Proliferation Through SQLE

Oncogene c-Myc (referred in this report as MYC) promotes tumorigenesis in multiple human cancers. MYC regulates numerous cellular programs involved in cell growth and cell metabolism. Tumor cells exhibit obligatory dependence on cholesterol metabolism, which provides essential membrane components and metabolites to support cell growth. To date, how cholesterol biosynthesis is delicately regulated to promote tumorigenesis remains unclear. Here, we show that MYC enhances cholesterol biosynthesis and promotes cell proliferation. Through transcriptional upregulation of SQLE, a rate-limiting enzyme in cholesterol synthesis pathway, MYC increases cholesterol production and promotes tumor cell growth. SQLE overexpression restores the cellular cholesterol levels in MYC-knockdown cells. More importantly, in SQLE-depleted cells, enforced expression of MYC has no effect on cholesterol levels. Therefore, our findings reveal that SQLE is critical for MYC-mediated cholesterol synthesis, and further demonstrate that SQLE may be a potential therapeutic target in MYC-amplified cancers.

Inhibition of fatty acid synthesis induces differentiation and reduces tumor burden in childhood neuroblastoma

Many metabolic pathways, including lipid metabolism, are rewired in tumors to support energy and biomass production and to allow adaptation to stressful environments. Neuroblastoma is the second deadliest solid tumor in children. Genetic aberrations, as the amplification of the MYCN-oncogene, correlate strongly with disease progression. Yet, there are only a few molecular targets successfully exploited in the clinic. Here we show that inhibition of fatty acid synthesis led to increased neural differentiation and reduced tumor burden in neuroblastoma xenograft experiments independently of MYCN-status. This was accompanied by reduced levels of the MYCN or c-MYC oncoproteins and activation of ERK signaling. Importantly, the expression levels of genes involved in de novo fatty acid synthesis showed prognostic value for neuroblastoma patients. Our findings demonstrate that inhibition of de novo fatty acid synthesis is a promising pharmacological intervention strategy for the treatment of neuroblastoma independently of MYCN-status.

Autophagy activation and SREBP-1 induction contribute to fatty acid metabolic reprogramming by leptin in breast cancer cells

Leptin, a hormone predominantly derived from adipose tissue, is well known to induce growth of breast cancer cells. However, its underlying mechanisms remain unclear. In this study, we examined the role of reprogramming of lipid metabolism and autophagy in leptin-induced growth of breast cancer cells. Herein, leptin induced significant increase in fatty acid oxidation-dependent ATP production in estrogen receptor-positive breast cancer cells. Furthermore, leptin induced both free fatty acid release and intracellular lipid accumulation, indicating a multifaceted effect of leptin in fatty acid metabolism. These findings were further validated in an MCF-7 tumor xenograft mouse model. Importantly, all the aforementioned metabolic effects of leptin were mediated via autophagy activation. In addition, SREBP-1 induction driven by autophagy and fatty acid synthase induction, which is mediated by SREBP-1, plays crucial roles in leptin-stimulated metabolic reprogramming and are required for growth of breast cancer cell, suggesting a pivotal contribution of fatty acid metabolic reprogramming to tumor growth by leptin. Taken together, these results highlighted a crucial role of autophagy in leptin-induced cancer cell-specific metabolism, which is mediated, at least in part, via SREBP-1 induction.

Metabolic Effects of Recurrent Genetic Aberrations in Multiple Myeloma

Oncogene activation and malignant transformation exerts energetic, biosynthetic and redox demands on cancer cells due to increased proliferation, cell growth and tumor microenvironment adaptation. As such, altered metabolism is a hallmark of cancer, which is characterized by the reprogramming of multiple metabolic pathways. Multiple myeloma (MM) is a genetically heterogeneous disease that arises from terminally differentiated B cells. MM is characterized by reciprocal chromosomal translocations that often involve the immunoglobulin loci and a restricted set of partner loci, and complex chromosomal rearrangements that are associated with disease progression. Recurrent chromosomal aberrations in MM result in the aberrant expression of MYC, cyclin D1, FGFR3/MMSET and MAF/MAFB. In recent years, the intricate mechanisms that drive cancer cell metabolism and the many metabolic functions of the aforementioned MM-associated oncogenes have been investigated. Here, we discuss the metabolic consequences of recurrent chromosomal translocations in MM and provide a framework for the identification of metabolic changes that characterize MM cells.

Cancer Metabolism: Phenotype, Signaling and Therapeutic Targets

Aberrant metabolism is a major hallmark of cancer. Abnormal cancer metabolism, such as aerobic glycolysis and increased anabolic pathways, has important roles in tumorigenesis, metastasis, drug resistance, and cancer stem cells. Well-known oncogenic signaling pathways, such as phosphoinositide 3-kinase (PI3K)/AKT, Myc, and Hippo pathway, mediate metabolic gene expression and increase metabolic enzyme activities. Vice versa, deregulated metabolic pathways contribute to defects in cellular signal transduction pathways, which in turn provide energy, building blocks, and redox potentials for unrestrained cancer cell proliferation. Studies and clinical trials are being performed that focus on the inhibition of metabolic enzymes by small molecules or dietary interventions (e.g., fasting, calorie restriction, and intermittent fasting). Similar to genetic heterogeneity, the metabolic phenotypes of cancers are highly heterogeneous. This heterogeneity results from diverse cues in the tumor microenvironment and genetic mutations. Hence, overcoming metabolic plasticity is an important goal of modern cancer therapeutics. This review highlights recent findings on the metabolic phenotypes of cancer and elucidates the interactions between signal transduction pathways and metabolic pathways. We also provide novel rationales for designing the next-generation cancer metabolism drugs.

Nutrient Sensing by Histone Marks: Reading the Metabolic Histone Code Using Tracing, Omics, and Modeling

Several metabolites serve as substrates for histone modifications and communicate changes in the metabolic environment to the epigenome. Technologies such as metabolomics and proteomics have allowed us to reconstruct the interactions between metabolic pathways and histones. These technologies have shed light on how nutrient availability can have a dramatic effect on various histone modifications. This metabolism-epigenome cross talk plays a fundamental role in development, immune function, and diseases like cancer. Yet, major challenges remain in understanding the interactions between cellular metabolism and the epigenome. How the levels and fluxes of various metabolites impact epigenetic marks is still unclear. Discussed herein are recent applications and the potential of systems biology methods such as flux tracing and metabolic modeling to address these challenges and to uncover new metabolic-epigenetic interactions. These systems approaches can ultimately help elucidate how nutrients shape the epigenome of microbes and mammalian cells.

Mitochondria Are Fundamental for the Emergence of Metazoans: On Metabolism, Genomic Regulation, and the Birth of Complex Organisms

Out of many intracellular bacteria, only the mitochondria and chloroplasts abandoned their independence billions of years ago and became endosymbionts within the host eukaryotic cell. Consequently, one cannot grow eukaryotic cells without their mitochondria, and the mitochondria cannot divide outside of the cell, thus reflecting interdependence. Here, we argue that such interdependence underlies the fundamental role of mitochondrial activities in the emergence of metazoans. Several lines of evidence support our hypothesis: (a) Differentiation and embryogenesis rely on mitochondrial function; (b) mitochondrial metabolites are primary precursors for epigenetic modifications (such as methyl and acetyl), which are critical for chromatin remodeling and gene expression, particularly during differentiation and embryogenesis; and (c) mitonuclear coregulation adapted to accommodate both housekeeping and tissue-dependent metabolic needs. We discuss the evolution of the unique mitochondrial genetic system, mitochondrial metabolites, mitonuclear coregulation, and their critical roles in the emergence of metazoans and in human disorders.

Aldehyde dehydrogenase ALDH3F1 involvement in flowering time regulation through histone acetylation modulation on FLOWERING LOCUS C

Flowering time regulation is one of the most important processes in the whole life of flowering plants and FLOWERING LOCUS C (FLC) is a central repressor of flowering time. However, whether metabolic acetate level affects flowering time is unknown. Here we report that ALDEHYDE DEHYDROGENASE ALDH3F1 plays essential roles in floral transition via FLC-dependent pathway. In the aldh3f1-1 mutant, the flowering time was significant earlier than Col-0 and the FLC expression level was reduced. ALDH3F1 had aldehyde dehydrogenase activity to affect the acetate level in plants, and the amino acids of E214 and C252 are essential for its catalytic activity. Moreover, aldh3f1 mutation reduced acetate level and the total acetylation on histone H3. The H3K9Ac level on FLC locus was decreased in aldh3f1-1, which reduced FLC expression. Expression of ALDH3F1 could rescue the decreased H3K9Ac level on FLC, FLC expression and also the early-flowering phenotype of aldh3f1-1, however ALDH3F1^E214A or ALDH3F1^C252A could not. Our findings demonstrate that ALDH3F1 participates in flowering time regulation through modulating the supply of acetate for acetyl-CoA, which functions as histone acetylation donor to modulate H3K9Ac on FLC locus.

Metabolomics of Milk Reflects a Negative Energy Balance in Cows

Dairy cows can experience a negative energy balance (NEB) in early lactation when feed intake is too low to meet the energy requirements for body maintenance and milk production. Metabolic changes occur in mammary gland cells of animals experiencing a negative energy balance. We studied these metabolic changes in milk samples from dairy cows in relation to energy balance status using liquid chromatography–mass spectrometry (QQQ-LC–MS) and nuclear magnetic resonance (¹H NMR). NMR and LC–MS techniques are complementary techniques that enabled a comprehensive overview of milk metabolites in our study. Energy balance and milk samples were obtained from 87 dairy cows. A total of 55 milk metabolites were reliably detected, of which 15 metabolites were positively correlated to energy balance and 20 were negatively correlated to energy balance. Cows in NEB produced more milk with increased milk fat yield and higher concentrations of citrate, cis-aconitate, creatinine, glycine, phosphocreatine, galactose-1-phosphate, glucose-1-phosphate, UDP-N-acetyl-galactosamine, UDP-N-acetyl-glucosamine, and phosphocholine but lower concentrations of choline, ethanolamine, fucose, N-acetyl-neuraminic acid, N-acetyl-glucosamine, and N-acetyl-galactosamine. During NEB, we observed an increased leakage of cellular content, increased synthesis of nucleic acids and cell membrane phospholipids, an increase in one-carbon metabolic processes, and an increase in lipid-triglyceride anabolism. Overall, both apoptosis combined with cellular renewal is paramount in the mammary gland in cows in NEB.

Role of Mitochondria-Cytoskeleton Interactions in the Regulation of Mitochondrial Structure and Function in Cancer Stem Cells

Despite the promise of cancer medicine, major challenges currently confronting the treatment of cancer patients include chemoresistance and recurrence. The existence of subpopulations of cancer cells, known as cancer stem cells (CSCs), contributes to the failure of cancer therapies and is associated with poor clinical outcomes. Of note, one of the recently characterized features of CSCs is augmented mitochondrial function. The cytoskeleton network is essential in regulating mitochondrial morphology and rearrangement, which are inextricably linked to its functions, such as oxidative phosphorylation (OXPHOS). The interaction between the cytoskeleton and mitochondria can enable CSCs to adapt to challenging conditions, such as a lack of energy sources, and to maintain their stemness. Cytoskeleton-mediated mitochondrial trafficking and relocating to the high energy requirement region are crucial steps in epithelial-to-mesenchymal transition (EMT). In addition, the cytoskeleton itself interplays with and blocks the voltage-dependent anion channel (VDAC) to directly regulate bioenergetics. In this review, we describe the regulation of cellular bioenergetics in CSCs, focusing on the cytoskeleton-mediated dynamic control of mitochondrial structure and function.

Mitochondrial dynamics and metabolism in induced pluripotency

Somatic cells can be reprogrammed to pluripotency by either ectopic expression of defined factors or exposure to chemical cocktails. During reprogramming, somatic cells undergo dramatic changes in a wide range of cellular processes, such as metabolism, mitochondrial morphology and function, cell signaling pathways or immortalization. Regulation of these processes during cell reprograming lead to the acquisition of a pluripotent state, which enables indefinite propagation by symmetrical self-renewal without losing the ability of reprogrammed cells to differentiate into all cell types of the adult. In this review, recent data from different laboratories showing how these processes are controlled during the phenotypic transformation of a somatic cell into a pluripotent stem cell will be discussed.

Lipid desaturation-associated endoplasmic reticulum stress regulates MYCN gene expression in hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths worldwide due to its high rate of recurrence, in part because of cancer stem cell (CSC)-dependent “field cancerization”. Recently, we identified that the oncogene v-myc avian myelocytomatosis viral oncogene neuroblastoma derived homolog (MYCN) marked CSC-like subpopulations in heterogeneous HCC and served as a therapeutic target and prognostic marker for HCC. In this study, we explored the molecular basis of upregulated MYCN gene expression in HCC cells. Liquid chromatograph time-of-flight mass spectrometry-based metabolome analysis demonstrated that the content of unsaturated fatty acids was increased in MYCN high expression (MYCN^high) CSC-like HCC cells. Inhibition of lipid desaturation using either the chemical inhibitor or siRNA/shRNA against stearoyl-CoA desaturase-1 (SCD1) suppressed cell proliferation as well as MYCN gene expression in MYCN^high HCC cells, grown as both monolayer and spheres. Further mechanistic study using RNA-seq based transcriptome analysis revealed that endoplasmic reticulum (ER) stress related signaling networks such as endocannabinoid cancer inhibition pathway were under the control of SCD1 in MYCN^high HCC cells. Furthermore, the expression of ER stress-inducible transcription suppressor cyclic AMP-dependent transcription factor (ATF3) was downregulated in MYCN^high CSC-like HCC cells and CSC-rich spheroids, which was upregulated by inhibition of lipid desaturation or treatment with acyclic retinoid (ACR). Lipid profiling using NMR spectroscopy revealed that the ACR dramatically reduced the content of unsaturated fatty acids in HCC cells. The chemical inducer of ER stress inhibited MYCN gene expression, while the chemical inhibitor of ER stress or knockdown of ATF3 gene expression partially rescued the suppression of MYCN gene expression by ACR in MYCN^high HCC cells. These data suggested that lipid desaturation-mediated ER stress signaling regulates MYCN gene expression in HCC cells and serves as a promising therapeutic target for the treatment and prevention of HCC.

MYCN and PRC1 cooperatively repress docosahexaenoic acid synthesis in neuroblastoma via ELOVL2

Background

The MYCN amplification is a defining hallmark of high-risk neuroblastoma. Due to irregular oncogenes orchestration, tumor cells exhibit distinct fatty acid metabolic features from non-tumor cells. However, the function of MYCN in neuroblastoma fatty acid metabolism reprogramming remains unknown.

Methods

Gas Chromatography-Mass Spectrometer (GC-MS) was used to find the potential target fatty acid metabolites of MYCN. Real-time PCR (RT-PCR) and clinical bioinformatics analysis was used to find the related target genes. The function of the identified target gene ELOVL2 on cell growth was detected through CCK-8 assay, Soft agar colony formation assay, flow Cytometry assay and mouse xenograft. Chromatin immunoprecipitation (ChIP) and Immunoprecipitation-Mass Spectrometer (IP-MS) further identified the target gene and the co-repressor of MYCN.

Results

The fatty acid profile of MYCN-depleted neuroblastoma cells identified docosahexaenoic acid (DHA), an omega-3 polyunsaturated fatty acid with anti-tumor activity, significantly increased after MYCN depletion. Compared with MYCN single-copy neuroblastoma cells, DHA level was significantly lower in MYCN-amplified neuroblastoma cells. RT-PCR and clinical bioinformatics analysis discovered that MYCN interfered DHA accumulation via ELOVL fatty acid elongase 2 (ELOVL2) which is a rate-limiting enzyme of cellular DHA synthesis. Enforced ELOVL2 expression in MYCN-amplified neuroblastoma cells led to decreased cell growth and counteracted the growth-promoting effect of MYCN overexpression both in vitro and vivo. ELOVL2 Knockdown showed the opposite effect in MYCN single-copy neuroblastoma cells. In primary neuroblastoma, high ELOVL2 transcription correlated with favorable clinical tumor biology and patient survival. The mechanism of MYCN-mediated ELOVL2 inhibition contributed to epigenetic regulation. MYCN recruited PRC1 (Polycomb repressive complex 1), catalysed H2AK119ub (histone 2A lysine 119 monoubiquitination) and inhibited subsequent ELOVL2 transcription.

Conclusions

The tumor suppressive properties of DHA and ELOVL2 are repressed by the MYCN and PRC1 jointly, which suggests a new epigenetic mechanism of MYCN-mediated fatty acid regulation and indicates PRC1 inhibition as a potential novel strategy to activate ELOVL2 suppressive functions.

ATP citrate lyase: A central metabolic enzyme in cancer

ACLY links energy metabolism provided by catabolic pathways to biosynthesis. ACLY, which has been found to be overexpressed in many cancers, converts citrate into acetyl-CoA and OAA. The first of these molecules supports protein acetylation, in particular that of histone, and de novo lipid synthesis, and the last one sustains the production of aspartate (required for nucleotide and polyamine synthesis) and the regeneration of NADPH,H⁺(consumed in redox reaction and biosynthesis). ACLY transcription is promoted by SREBP1, its activity is stabilized by acetylation and promoted by AKT phosphorylation (stimulated by growth factors and glucose abundance). ACLY plays a pivotal role in cancer metabolism through the potential deprivation of cytosolic citrate, a process promoting glycolysis through the enhancement of the activities of PFK 1 and 2 with concomitant activation of oncogenic drivers such as PI3K/AKT which activate ACLY and the Warburg effect in a feed-back loop. Pending the development of specific inhibitors and tailored methods for identifying which specific metabolism is involved in the development of each tumor, ACLY could be targeted by inhibitors such as hydroxycitrate and bempedoic acid. The administration of citrate at high level mimics a strong inhibition of ACLY and could be tested to strengthen the effects of current therapies.

Metabolic dependencies and vulnerabilities in leukemia

In this Review, Rashkovan et al. discuss the role of cancer metabolic circuitries feeding anabolism and redox potential in leukemia development and recent progress in translating these important findings to the clinic.

Leukemia cell proliferation requires up-regulation and rewiring of metabolic pathways to feed anabolic cell growth. Oncogenic drivers directly and indirectly regulate metabolic pathways, and aberrant metabolism is central not only for leukemia proliferation and survival, but also mediates oncogene addiction with significant implications for the development of targeted therapies. This review explores leukemia metabolic circuitries feeding anabolism, redox potential, and energy required for tumor propagation with an emphasis on emerging therapeutic opportunities.