Metabolic transformation in cancer

Transcriptional regulation and post-translational modifications in the glycolytic pathway for targeted cancer therapy

Cancer cells largely rely on aerobic glycolysis or the Warburg effect to generate essential biomolecules and energy for their rapid growth. The key modulators in glycolysis including glucose transporters and enzymes, e.g. hexokinase 2, enolase 1, pyruvate kinase M2, lactate dehydrogenase A, play indispensable roles in glucose uptake, glucose consumption, ATP generation, lactate production, etc. Transcriptional regulation and post-translational modifications (PTMs) of these critical modulators are important for signal transduction and metabolic reprogramming in the glycolytic pathway, which can provide energy advantages to cancer cell growth. In this review we recapitulate the recent advances in research on glycolytic modulators of cancer cells and analyze the strategies targeting these vital modulators including small-molecule inhibitors and microRNAs (miRNAs) for targeted cancer therapy. We focus on the regulation of the glycolytic pathway at the transcription level (e.g., hypoxia-inducible factor 1, c-MYC, p53, sine oculis homeobox homolog 1, N6-methyladenosine modification) and PTMs (including phosphorylation, methylation, acetylation, ubiquitination, etc.) of the key regulators in these processes. This review will provide a comprehensive understanding of the regulation of the key modulators in the glycolytic pathway and might shed light on the targeted cancer therapy at different molecular levels.

TET3 is a positive regulator of mitochondrial respiration in Neuro2A cells

Ten-Eleven-Translocase (TET) enzymes contribute to the regulation of the methylome via successive oxidation of 5-methyl cytosine (5mC) to derivatives which can be actively removed by base-excision-repair (BER) mechanisms in the absence of cell division. This is particularly important in post-mitotic neurons where changes in DNA methylation are known to associate with changes in neural function. TET3, specifically, is a critical regulator of both neuronal differentiation in development and mediates dynamic changes in the methylome of adult neurons associated with cognitive function. While DNA methylation is understood to regulate transcription, little is known of the specific targets of TET3-dependent catalytic activity in neurons. We report the results of an unbiased transcriptome analysis of the neuroblastoma-derived cell line; Neuro2A, in which Tet3 was silenced. Oxidative phosphorylation (OxPhos) was identified as the most significantly down-regulated functional canonical pathway, and these findings were confirmed by measurements of oxygen consumption rate in the Seahorse bioenergetics analyser. The mRNA levels of both nuclear- and mitochondrial-encoded OxPhos genes were reduced by Tet3-silencing, but we found no evidence for differential (hydroxy)methylation deposition at these gene loci. However, the mRNA expression of genes known to be involved in mitochondrial quality control were also shown to be significantly downregulated in the absence of TET3. One of these genes; EndoG, was identified as a direct target of TET3-catalytic activity at non-CpG methylated sites within its gene body. Accordingly, we propose that aberrant mitochondrial homeostasis may contribute to the decrease in OxPhos, observed upon Tet3-downregulation in Neuro2A cells.

Glutamine addiction in tumor cell: oncogene regulation and clinical treatment

After undergoing metabolic reprogramming, tumor cells consume additional glutamine to produce amino acids, nucleotides, fatty acids, and other substances to facilitate their unlimited proliferation. As such, the metabolism of glutamine is intricately linked to the survival and progression of cancer cells. Consequently, targeting the glutamine metabolism presents a promising strategy to inhibit growth of tumor cell and cancer development. This review describes glutamine uptake, metabolism, and transport in tumor cells and its pivotal role in biosynthesis of amino acids, fatty acids, nucleotides, and more. Furthermore, we have also summarized the impact of oncogenes like C-MYC, KRAS, HIF, and p53 on the regulation of glutamine metabolism and the mechanisms through which glutamine triggers mTORC1 activation. In addition, role of different anti-cancer agents in targeting glutamine metabolism has been described and their prospective applications are assessed.

Molecular Insight into Iron Homeostasis of Acute Myeloid Leukemia Blasts

Acute myeloid leukemia (AML) remains a disease of gloomy prognosis despite intense efforts to understand its molecular foundations and to find efficient treatments. In search of new characteristic features of AML blasts, we first examined experimental conditions supporting the amplification of hematological CD34+ progenitors ex vivo. Both AML blasts and healthy progenitors heavily depended on iron availability. However, even if known features, such as easier engagement in the cell cycle and amplification factor by healthy progenitors, were observed, multiplying progenitors in a fully defined medium is not readily obtained without modifying their cellular characteristics. As such, we measured selected molecular data including mRNA, proteins, and activities right after isolation. Leukemic blasts showed clear signs of metabolic and signaling shifts as already known, and we provide unprecedented data emphasizing disturbed cellular iron homeostasis in these blasts. The combined quantitative data relative to the latter pathway allowed us to stratify the studied patients in two sets with different iron status. This categorization is likely to impact the efficiency of several therapeutic strategies targeting cellular iron handling that may be applied to eradicate AML blasts.

pH-sensitive tumor-tropism hybrid membrane-coated nanoparticles for reprogramming the tumor microenvironment and boosting the antitumor immunity

Metabolic dysregulation contributes not only to cancer development but also to a tumor immune microenvironment (TIME), which poses great challenges to chemo- and immunotherapy. Targeting metabolic reprogramming has recently emerged as a promising strategy for cancer treatment, but the lethality against solid tumors appears to be fairly restricted, partially due to the poor solubility of small molecule drugs. Herein, we construct a versatile biomimetic nanoplatform (referred to as HM-BPT) employing pH-sensitive tumor-tropism hybrid membrane-coated Manganese oxide (MnO2) nanoparticles for the delivery of BPTES, a glutamine metabolism inhibitor. Basically, hybrid membranes consisting of mesenchymal stem cell membranes (MSCm) and pH-sensitive liposomes (pSL) enable the biomimetic nanoplatform to target TME and escape from endo/lysosomes after endocytosis. The results reveal that HM-BPT treatment leads to remarkable tumor inhibition, cytotoxic T lymphocyte (CTL) infiltration, as well as M1 phenotype repolarization and stimulator of IFN genes (STING) pathway activation in macrophages in a 4T1 xenograft model. Furthermore, glutathione (GSH) depletion and oxygen (O2) supply synergistically ameliorate the immunosuppressive status of the TME, boosting potent antitumor immune responses. Overall, our study explores an integrated therapeutic platform for TME reprogramming and immune activation, offering tremendous promise for cancer combination therapy. STATEMENT OF SIGNIFICANCE: Metabolic abnormalities and the tumor immune microenvironment (TIME) lead to hyporesponsiveness to conventional therapies, ultimately resulting in refractory malignancies. In the current work, a biomimetic nanoplatform (HM-BPT) was developed for TME metabolic reprogramming in favor of immunotherapy. Particularly, hybrid membrane camouflage endowed the nanoplatform with TME targeting, endo/lysosomal escape, and sensitive release properties. The impact of hybrid membrane fusion ratio on cellular uptake and cell viability was explored, yielding beneficial references for the future development of bioactive nanomaterials. Intravenous administration of HM-BPT substantially relieved tumor burden and restored innate and acquired immune activation in 4T1 xenograft models. In conclusion, the created HM-BPT system has the potential to be a promising nanoplatform for combining cancer therapies.

Oxidative Stress Linking Obesity and Cancer: Is Obesity a 'Radical Trigger' to Cancer?

Obesity is on the rise worldwide, and consequently, obesity-related non-communicable diseases are as well. Nutritional overload induces metabolic adaptations in an attempt to restore the disturbed balance, and the byproducts of the mechanisms at hand include an increased generation of reactive species. Obesity-related oxidative stress causes damage to vulnerable systems and ultimately contributes to neoplastic transformation. Dysfunctional obese adipose tissue releases cytokines and induces changes in the cell microenvironment, promoting cell survival and progression of the transformed cancer cells. Other than the increased risk of cancer development, obese cancer patients experience higher mortality rates and reduced therapy efficiency as well. The fact that obesity is considered the second leading preventable cause of cancer prioritizes the research on the mechanisms connecting obesity to cancerogenesis and finding the solutions to break the link. Oxidative stress is integral at different stages of cancer development and advancement in obese patients. Hypocaloric, balanced nutrition, and structured physical activity are some tools for relieving this burden. However, the sensitivity of simultaneously treating cancer and obesity poses a challenge. Further research on the obesity-cancer liaison would offer new perspectives on prevention programs and treatment development.

NRF2 activation induces NADH-reductive stress, providing a metabolic vulnerability in lung cancer

Multiple cancers regulate oxidative stress by activating the transcription factor NRF2 through mutation of its negative regulator, KEAP1. NRF2 has been studied extensively in KEAP1-mutant cancers; however, the role of this pathway in cancers with wild-type KEAP1 remains poorly understood. To answer this question, we induced NRF2 via pharmacological inactivation of KEAP1 in a panel of 50+ non-small cell lung cancer cell lines. Unexpectedly, marked decreases in viability were observed in >13% of the cell lines-an effect that was rescued by NRF2 ablation. Genome-wide and targeted CRISPR screens revealed that NRF2 induces NADH-reductive stress, through the upregulation of the NAD+-consuming enzyme ALDH3A1. Leveraging these findings, we show that cells treated with KEAP1 inhibitors or those with endogenous KEAP1 mutations are selectively vulnerable to Complex I inhibition, which impairs NADH oxidation capacity and potentiates reductive stress. Thus, we identify reductive stress as a metabolic vulnerability in NRF2-activated lung cancers.

Therapy Resistance and Disease Progression in CML: Mechanistic Links and Therapeutic Strategies

PURPOSE OF REVIEW

Despite the adoption of tyrosine kinases inhibitors (TKIs) as molecular targeted therapy in chronic myeloid leukemia, some patients do not respond to treatment and even experience disease progression. This review aims to give a broad summary of advances in understanding of the mechanisms of therapy resistance, as well as management strategies that may overcome or prevent the emergence of drug resistance. Ultimately, the goal of therapy is the cure of CML, which will also require an increased understanding of the leukemia stem cell (LSC).

RECENT FINDINGS

Resistance to tyrosine kinase inhibitors stems from a range of possible causes. Mutations of the BCR-ABL1 fusion oncoprotein have been well-studied. Other causes range from cell-intrinsic factors, such as the inherent resistance of primitive stem cells to drug treatment, to mechanisms extrinsic to the leukemic compartment that help CML cells evade apoptosis. There exists heterogeneity in TKI response among different hematopoietic populations in CML. The abundances of these TKI-sensitive and TKI-insensitive populations differ from patient to patient and contribute to response heterogeneity. It is becoming clear that targeting the BCR-ABL1 kinase through TKIs is only one part of the equation, and TKI usage alone may not cure the majority of patients with CML. Considerable effort should be devoted to targeting the BCR-ABL1-independent mechanisms of resistance and persistence of CML LSCs.

Oncometabolism: A Paradigm for the Metabolic Remodeling of the Failing Heart

Heart failure is associated with profound alterations in cardiac intermediary metabolism. One of the prevailing hypotheses is that metabolic remodeling leads to a mismatch between cardiac energy (ATP) production and demand, thereby impairing cardiac function. However, even after decades of research, the relevance of metabolic remodeling in the pathogenesis of heart failure has remained elusive. Here we propose that cardiac metabolic remodeling should be looked upon from more perspectives than the mere production of ATP needed for cardiac contraction and relaxation. Recently, advances in cancer research have revealed that the metabolic rewiring of cancer cells, often coined as oncometabolism, directly impacts cellular phenotype and function. Accordingly, it is well feasible that the rewiring of cardiac cellular metabolism during the development of heart failure serves similar functions. In this review, we reflect on the influence of principal metabolic pathways on cellular phenotype as originally described in cancer cells and discuss their potential relevance for cardiac pathogenesis. We discuss current knowledge of metabolism-driven phenotypical alterations in the different cell types of the heart and evaluate their impact on cardiac pathogenesis and therapy.

Fructose milieu undermines the therapeutic effect of Tribulus terrestris extract on neuroblastoma cell line via maintaining mitochondrial function

Fructose overconsumption promotes tumor progression. Neuroblastoma is a common extracranial tumor with about 50% 5-year survival rate in high-risk children. The anti-tumor effect of Tribulus terrestris might bring new hope to neuroblastoma therapy. However, whether fructose disturbs the therapeutic effect of T. terrestris is currently unknown. In this study, the mouse neuroblastoma cell line, Neuro 2a (N2a) cells, was used to investigate the therapeutic effects of T. terrestris extract at various dosages (0.01, 1, 100 ng/ml) in regular EMEM medium or extra added fructose (20 mM) for 24 h. 100 ng/ml T. terrestris treatment significantly reduced the cell viability, whereas the cell viabilities were enhanced at the dosages of 0.01 or 1 ng/ml T. terrestris in the fructose milieu instead. The inhibition effect of T. terrestris on N2a migration was blunted in the fructose milieu. Moreover, T. terrestris effectively suppressed mitochondrial functions, including oxygen consumption rates, the activities of electron transport enzymes, the expressions of mitochondrial respiratory enzymes, and mitochondrial membrane potential. These suppressions were reversed in the fructose group. In addition, the T. terrestris-suppressed mitofusin and the T. terrestris-enhance mitochondrial fission 1 protein were maintained at basal levels in the fructose milieu. Together, these results demonstrated that T. terrestris extract effectively suppressed the survival and migration of neuroblastoma via inhibiting mitochondrial oxidative phosphorylation and disturbing mitochondrial dynamics. Whereas, the fructose milieu blunted the therapeutic effect of T. terrestris, particularly, when the dosage is reduced.

Relationship between metabolic reprogramming and drug resistance in breast cancer

Breast cancer is the leading cause of cancer death in women. At present, chemotherapy is the main method to treat breast cancer in addition to surgery and radiotherapy, but the process of chemotherapy is often accompanied by the development of drug resistance, which leads to a reduction in drug efficacy. Furthermore, mounting evidence indicates that drug resistance is caused by dysregulated cellular metabolism, and metabolic reprogramming, including enhanced glucose metabolism, fatty acid synthesis and glutamine metabolic rates, is one of the hallmarks of cancer. Changes in metabolism have been considered one of the most important causes of resistance to treatment, and knowledge of the mechanisms involved will help in identifying potential treatment deficiencies. To improve women’s survival outcomes, it is vital to elucidate the relationship between metabolic reprogramming and drug resistance in breast cancer. This review analyzes and investigates the reprogramming of metabolism and resistance to breast cancer therapy, and the results offer promise for novel targeted and cell-based therapies.

The crosstalk of the human microbiome in breast and colon cancer: A metabolomics analysis

The human microbiome's role in colon and breast cancer is described in this review. Understanding how the human microbiome and metabolomics interact with breast and colon cancer is the chief area of this study. First, the role of the gut and distal microbiome in breast and colon cancer is investigated, and the direct relationship between microbial dysbiosis and breast and colon cancer is highlighted. This work also focuses on the many metabolomic techniques used to locate prospective biomarkers, make an accurate diagnosis, and research new therapeutic targets for cancer treatment. This review clarifies the influence of anti-tumor medications on the microbiota and the proactive measures that can be taken to treat cancer using a variety of therapies, including radiotherapy, chemotherapy, next-generation biotherapeutics, gene-based therapy, integrated omics technology, and machine learning.

Different pancreatic cancer microenvironments convert iPSCs into cancer stem cells exhibiting distinct plasticity with altered gene expression of metabolic pathways

BACKGROUND

Cancer stem cells (CSCs) are generated under irregular microenvironment in vivo, of which mimic is quite difficult due to the lack of enough information of the factors responsible for cancer initiation. Here, we demonstrated that mouse induced pluripotent cells (miPSCs) reprogrammed from normal embryonic fibroblasts were susceptible to the microenvironment affected by cancer cells to convert into CSCs in vivo.

METHODS

Three different pancreatic cancer line cells, BxPC3, PANC1, and PK8 cells were mixed with miPSCs and subcutaneously injected into immunodeficient mice. Tumors were evaluated by histological analysis and cells derived from iPSCs were isolated and selected from tumors. The isolated cells were characterized for cancer stem cell characters in vitro and in vivo as well as their responses to anticancer drugs. The impact of co-injection of iPSCs with cancer cells on transcriptome and signaling pathways of iPSCs was investigated.

RESULTS

The injection of miPSCs mixed with human pancreatic cancer cells into immunodeficient mice maintained the stemness of miPSCs and changed their phenotype. The miPSCs acquired CSC characteristics of tumorigenicity and self-renewal. The drug responses and the metastatic ability of CSCs converted from miPSCs varied depending on the microenvironment of cancer cells. Interestingly, transcriptome profiles of these cells indicated that the pathways related with aggressiveness and energy production were upregulated from the levels of miPSCs.

CONCLUSIONS

Our result suggests that cancer-inducing microenvironment in vivo could rewire the cell signaling and metabolic pathways to convert normal stem cells into CSCs.

COVID-19 and its impact on cancer, HIV, and mentally ill patients

Severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) and its disease, COVID-19 is a global pandemic creating an unprecedented medical as well economic havoc across the world. Despite the wide spread global infection rates, the death rate is low for COVID-19. However, COVID-19 patients with other comorbid conditions face severe health complications irrespective of their gender or age. As the management of COVID-19 patients is taking up health resources, it is getting difficult to treat patients suffering from other dreadful diseases like cancer, HIV, and mental health issues. In this chapter, we discuss the effects of COVID-19 and management of cancer patients of main cancer subtypes (e.g., breast, lung, blood cancers), and patients affected with HIV and mental health issues. Finally, we also add a perspective on Ayurvedic treatment and its efficacy on COVID-19 patients.

Proline metabolism and redox; maintaining a balance in health and disease

Proline is a non-essential amino acid with key roles in protein structure/function and maintenance of cellular redox homeostasis. It is available from dietary sources, generated de novo within cells, and released from protein structures; a noteworthy source being collagen. Its catabolism within cells can generate ATP and reactive oxygen species (ROS). Recent findings suggest that proline biosynthesis and catabolism are essential processes in disease; not only due to the role in new protein synthesis as part of pathogenic processes but also due to the impact of proline metabolism on the wider metabolic network through its significant role in redox homeostasis. This is particularly clear in cancer proliferation and metastatic outgrowth. Nevertheless, the precise identity of the drivers of cellular proline catabolism and biosynthesis, and the overall cost of maintaining appropriate balance is not currently known. In this review, we explore the major drivers of proline availability and consumption at a local and systemic level with a focus on cancer. Unraveling the main factors influencing proline metabolism in normal physiology and disease will shed light on new effective treatment strategies.

Stationed or Relocating: The Seesawing EMT/MET Determinants from Embryonic Development to Cancer Metastasis

Epithelial and mesenchymal transition mechanisms continue to occur during the cell cycle and throughout human development from the embryo stage to death. In embryo development, epithelial-mesenchymal transition (EMT) can be divided into three essential steps. First, endoderm, mesoderm, and neural crest cells form, then the cells are subdivided, and finally, cardiac valve formation occurs. After the embryonic period, the human body will be subjected to ongoing mechanical stress or injury. The formation of a wound requires EMT to recruit fibroblasts to generate granulation tissues, repair the wound and re-create an intact skin barrier. However, once cells transform into a malignant tumor, the tumor cells acquire the characteristic of immortality. Local cell growth with no growth inhibition creates a solid tumor. If the tumor cannot obtain enough nutrition in situ, the tumor cells will undergo EMT and invade the basal membrane of nearby blood vessels. The tumor cells are transported through the bloodstream to secondary sites and then begin to form colonies and undergo reverse EMT, the so-called "mesenchymal-epithelial transition (MET)." This dynamic change involves cell morphology, environmental conditions, and external stimuli. Therefore, in this manuscript, the similarities and differences between EMT and MET will be dissected from embryonic development to the stage of cancer metastasis.

Combinatorial antitumor effects of amino acids and epigenetic modulations in hepatocellular carcinoma cell lines

Hepatocellular carcinoma (HCC) is a highly fatal form of liver cancer. Recently, the interest in using amino acids as therapeutic agents has noticeably grown. The present work aimed to evaluate the possible antiproliferative effects of selected amino acids supplementation or deprivation in human HCC cell lines and to investigate their effects on critical signaling molecules in HCC pathogenesis and the outcomes of their combination with the histone deacetylase inhibitor vorinostat. HepG2 and Huh7 cells were treated with different concentrations of L-leucine, L-glutamine, or L-methionine and cell viability was determined using MTT assay. Insulin-like growth factor 1 (IGF1), phosphorylated ribosomal protein S6 kinase (p70 S6K), p53, and cyclin D1 (CD1) protein levels were assayed using ELISA. Caspase-3 activity was assessed colorimetrically. L-leucine supplementation (0.8-102.4 mM) and L-glutamine supplementation (4-128 mM) showed dose-dependent antiproliferative effects in both cell lines but L-methionine supplementation (0.2-25.6 mM) only affected the viability of HepG2 cells. Glutamine or methionine deprivation suppressed the proliferation of HepG2 cells whereas leucine deprivation had no effect on cell viability in both cell lines. The combination between the effective antiproliferative changes in L-leucine, L-glutamine, and L-methionine concentrations greatly suppressed cell viability and increased the sensitivity to vorinostat in both cell lines. The growth inhibitory effects were paralleled with significant decreases in IGF-1, phospho p70 S6k, and CD1 levels and significant elevations in p53 and caspase-3 activity. Changes in amino acids concentrations could profoundly affect growth in HCC cell lines and their response to epigenetic therapy.

The functional roles of TCA cycle metabolites in cancer

The tricarboxylic acid cycle (TCA cycle) has been known for decades as a hub for generating cellular energy and precursors for biosynthetic pathways. Several cancers harbor mutations that affect the integrity of this cycle, mostly at the levels of isocitrate dehydrogenase (IDH), succinate dehydrogenase (SDH), and fumarate hydratase (FH). This results in dysregulation in the production of TCA cycle metabolites and is probably implicated in cancer initiation. By modulating cellular activities, including metabolism and signaling, TCA cycle intermediates are able to impact the processes of cancer development and progression. In this review, we discuss the functional roles of the TCA cycle intermediates in suppressing or promoting the progression of cancers. A further understanding of TCA metabolites' roles and molecular mechanisms in oncogenesis would prompt developing novel metabolite-based cancer therapy in the future.

Lymphatic Metastasis of NSCLC Involves Chemotaxis Effects of Lymphatic Endothelial Cells through the CCR7-CCL21 Axis Modulated by TNF-α

Metastasis and recurrence are the main causes of lung adenocarcinoma patients’ death. Lymphatic metastasis is the main way of non-small cell lung cancer (NSCLC) metastasis. C-C chemokine receptor type 7 (CCR7) overexpression has been demonstrated to mediate occurrence and progression of NSCLC. Moreover, Chemokine ligand 21 (CCL21) was used to activate CCR7. The CCR7–CCL21 axis is one of the most common “chemokine-receptor” modes of action in the development and metastasis of multiple tumors. However, the role of the CCR7–CCL21 axis in lymphatic metastasis of NSCLC is poorly understood. The study was conducted to investigate the molecular mechanism underlying CCR7–CCL21 axis-mediated lymphatic metastasis of NSCLC A549 cells. Tumor necrosis factor α (TNF-α) could regulate the tumor microenvironment balance by promoting chemokine secretion. Our study demonstrated that TNF-α promoted CCL21 production in human lymphatic endothelial cells (HLEC). Results further showed that TNF-α significantly activated the NF-κB pathway in HLEC. NF–κB pathway inhibition with ammonium pyrrolidinedithiocarbamate (PDTC) caused a significant decrease in CCL21 secretion, suggesting that TNF-α-induced CCL21 secretion in HLEC was through NF–κB pathway. Co-culture of A549 cells and TNF-α-treated HLEC confirmed that the metastasis of A549 cells was enhanced, meanwhile, apoptosis-related proteins were hardly affected. The data proved that a co-culture system prevented cell apoptosis while inducing the lymphatic metastasis of A549 cells. However, the situation was reversed after neutralizing CCL21 expression, suggesting that TNF-α-induced CCL21 secretion in HLEC is involved in A549 cells metastasis. Collectively, our finding demonstrated that NF-κB pathway-controlled CCL21 secretion of HLEC contributing to the lymphatic metastasis of A549 cells via the CCR7–CCL21 axis, validating the CCR7–CCL21 axis as a potential target to inhibit metastasis of NSCLC.

On the Origin of ATP Synthesis in Cancer

ATP is required for mammalian cells to remain viable and to perform genetically programmed functions. Maintenance of the ΔG′_ATP hydrolysis of −56 kJ/mole is the endpoint of both genetic and metabolic processes required for life. Various anomalies in mitochondrial structure and function prevent maximal ATP synthesis through OxPhos in cancer cells. Little ATP synthesis would occur through glycolysis in cancer cells that express the dimeric form of pyruvate kinase M2. Mitochondrial substrate level phosphorylation (mSLP) in the glutamine-driven glutaminolysis pathway, substantiated by the succinate-CoA ligase reaction in the TCA cycle, can partially compensate for reduced ATP synthesis through both OxPhos and glycolysis. A protracted insufficiency of OxPhos coupled with elevated glycolysis and an auxiliary, fully operational mSLP, would cause a cell to enter its default state of unbridled proliferation with consequent dedifferentiation and apoptotic resistance, i.e., cancer. The simultaneous restriction of glucose and glutamine offers a therapeutic strategy for managing cancer.

Factors affecting serum lactate in patients with intracranial tumors - A report of our series and review of the literature

Background

A hyperlactemia may occur in the presence of tissue hypoperfusion, in diseases affecting metabolism and in cases of malignant neoplasm. However, the factors affecting the serum lactate levels in patients submitted to craniotomy for the resection of an intracranial tumor have been investigated only marginally. Here, we assessed the factors possibly affecting the levels of serum lactate in intracranial tumors and carried out a thorough literature review on this topic.

Methods

All patients submitted to elective craniotomy from January 2017 to August 2018 for the resection of a glioblastoma (GBM; 101 cases) and a benign meningioma (WHO I; 105 cases) were included in this study. The sex, age, histological diagnosis, body mass index (BMI), and diabetes were assessed as possible factors affecting the level of the preoperative and postoperative serum lactate in these patients.

Results

We found that preoperative hyperlactemia (> 2 mmol/l) was more frequent in patients with GBM than in patients with meningioma (P = 0.0003). Moreover, a strong correlation between a preoperative lactemia and postoperative lactemia (P < 0.0001) was observed. On univariate analysis, we found increased preoperative serum lactate levels in GBM patients (P = 0.0022) and in patients with a BMI ≥30 (P = 0.0068). Postoperative serum lactate levels were significantly higher in GBM patients (P = 0.0003). On multivariate logistic regression analysis, a diagnosis of GBM was an independent factor for higher level of preoperative (P = 0.0005) and postoperative (P < 0.0001) serum lactate.

Conclusion

The malignant phenotype of GBM is the strongest factor associated with a pre- and postoperative hyperlactemia in patients submitted to craniotomy for the resection of an intracranial tumor.

NRF2 activation promotes the recurrence of dormant tumour cells through regulation of redox and nucleotide metabolism

The survival and recurrence of dormant tumour cells following therapy is a leading cause of death in cancer patients. The metabolic properties of these cells are likely distinct from those of rapidly growing tumours. Here we show that Her2 down-regulation in breast cancer cells promotes changes in cellular metabolism, culminating in oxidative stress and compensatory upregulation of the antioxidant transcription factor, NRF2. NRF2 is activated during dormancy and in recurrent tumours in animal models and breast cancer patients with poor prognosis. Constitutive activation of NRF2 accelerates recurrence, while suppression of NRF2 impairs it. In recurrent tumours, NRF2 signalling induces a transcriptional metabolic reprogramming to re-establish redox homeostasis and upregulate de novo nucleotide synthesis. The NRF2-driven metabolic state renders recurrent tumour cells sensitive to glutaminase inhibition, which prevents reactivation of dormant tumour cells in vitro, suggesting that NRF2-high dormant and recurrent tumours may be targeted. These data provide evidence that NRF2-driven metabolic reprogramming promotes the recurrence of dormant breast cancer.

Gene Expression Profiling of B Cell Lymphoma in Dogs Reveals Dichotomous Metabolic Signatures Distinguished by Oxidative Phosphorylation

Gene expression profiling has revealed molecular heterogeneity of diffuse large B cell lymphoma (DLBCL) in both humans and dogs. Two DLBCL subtypes based on cell of origin are generally recognized, germinal center B (GCB)-like and activated B cell (ABC)-like. A pilot study to characterize the transcriptomic phenotype of 11 dogs with multicentric BCL yielded two molecular subtypes distinguished on the basis of genes important in oxidative phosphorylation. We propose a metabolic classification of canine BCL that transcends cell of origin and shows parallels to a similar molecular phenotype in human DLBCL. We thus confirm the validity of this classification scheme across widely divergent mammalian taxa and add to the growing body of literature suggesting cellular and molecular similarities between human and canine non-Hodgkin lymphoma. Our data support a One Health approach to the study of DLBCL, including the advancement of novel therapies of relevance to both canine and human health.

Dichotomous role of the human mitochondrial Na+/Ca2+/Li+ exchanger NCLX in colorectal cancer growth and metastasis

Despite the established role of mitochondria in cancer, the mechanisms by which mitochondrial Ca²⁺ (mtCa²⁺) regulates tumorigenesis remain incompletely understood. The crucial role of mtCa²⁺ in tumorigenesis is highlighted by altered expression of proteins mediating mtCa²⁺ uptake and extrusion in cancer. Here, we demonstrate decreased expression of the mitochondrial Na⁺/Ca²⁺/Li⁺ exchanger NCLX (SLC8B1) in human colorectal tumors and its association with advanced-stage disease in patients. Downregulation of NCLX causes mtCa²⁺ overload, mitochondrial depolarization, decreased expression of cell-cycle genes and reduced tumor size in xenograft and spontaneous colorectal cancer mouse models. Concomitantly, NCLX downregulation drives metastatic spread, chemoresistance, and expression of epithelial-to-mesenchymal, hypoxia, and stem cell pathways. Mechanistically, mtCa²⁺ overload leads to increased mitochondrial reactive oxygen species, which activate HIF1α signaling supporting metastasis of NCLX-null tumor cells. Thus, loss of NCLX is a novel driver of metastasis, indicating that regulation of mtCa²⁺ is a novel therapeutic approach in metastatic colorectal cancer.

Tumour growth activation by the central nervous system-An integrative theory of cancer

The currently recognized mechanisms of the biology of cancer are not yet enough to explain the high incidence of the disease in industrialized countries. Survival and proliferation of cancer cells demand a well-orchestrated combination of functional capabilities, or hallmarks, which requires complex signalling networks that often exceed the tumour boundaries. Based on latest research on environmental health and aiming to provide cancer with a coherent set of organizing principles, we propose an integrative model of carcinogenesis founded on tumour growth activation by the central nervous system as an adaptive, allostatic response to both environmental and emotional challenges. In this way, chronicity of physical as well as psychological stressors may be directly involved in cancer genesis and progression, after an early inflammatory stage. The model also contemplates accidental activation of the tumour growth programme following direct DNA damage, but as a rare event that does not account for most cancers in humans. Bodily and cellular mechanisms designed to facilitate tumorigenesis may include exacerbation of the sympathetic activity, overexpression of membrane ion channels, promotion of selected mutations and methylations, degradation of the mitochondria and reprogramming of adult stem cells.

Knockdown of Pyruvate Kinase M Inhibits Cell Growth and Migration by Reducing NF-kB Activity in Triple-Negative Breast Cancer Cells

Altered genetic features in cancer cells lead to a high rate of aerobic glycolysis and metabolic reprogramming that is essential for increased cancer cell viability and rapid proliferation. Pyruvate kinase muscle (PKM) is a rate-limiting enzyme in the final step of glycolysis. Herein, we report that PKM is a potential therapeutic target in triple-negative breast cancer (TNBC) cells. We found that PKM1 or PKM2 is highly expressed in TNBC tissues or cells. Knockdown of PKM significantly suppressed cell proliferation and migration, and strongly reduced S phase and induced G2 phase cell cycle arrest by reducing phosphorylation of the CDC2 protein in TNBC cells. Additionally, knockdown of PKM significantly suppressed NF-kB (nuclear factor kappa-light-chain-enhancer of activated B cells) activity by reducing the phosphorylation of p65 at serine 536, and also decreased the expression of NF-kB target genes. Taken together, PKM is a potential target that may have therapeutic implications for TNBC cells.

Development of Novel Irreversible Pyruvate Kinase M2 Inhibitors

As cancer cells undergo metabolic reprogramming in the course of tumorigenesis, targeting energy metabolism represents a promising strategy in cancer therapy. Among various metabolic enzymes examined, pyruvate kinase M2 type (PKM2) has received much attention in light of its multifaceted function in promoting tumor growth and progression. In this study, we reported the development of a novel irreversible inhibitor of PKM2, compound 1, that exhibits a differential tumor-suppressive effect among an array of cancer cell lines. We further used a clickable activity-based protein profiling (ABPP) probe and SILAC coupled with LC-MS/MS to identify the Cys-317 and Cys-326 residues of PKM2 as the covalent binding sites. Equally important, compound 1 at 10 mg/kg was effective in suppressing xenograft tumor growth in nude mice without causing acute toxicity by targeting both metabolic and oncogenic functions. Together, these data suggest its translational potential to foster new strategies for cancer therapy.

The role of glycolysis and mitochondrial respiration in the formation and functioning of endothelial tip cells during angiogenesis

During sprouting angiogenesis, an individual endothelial tip cell grows out from a pre-existing vascular network and guides following and proliferating stalk cells to form a new vessel. Metabolic pathways such as glycolysis and mitochondrial respiration as the major sources of adenosine 5'-triphosphate (ATP) for energy production are differentially activated in these types of endothelial cells (ECs) during angiogenesis. Therefore, we studied energy metabolism during angiogenesis in more detail in tip cell and non-tip cell human umbilical vein ECs. Small interfering RNA was used to inhibit transcription of glycolytic enzymes PFKFB3 or LDHA and mitochondrial enzyme PDHA1 to test whether inhibition of these specific pathways affects tip cell differentiation and sprouting angiogenesis in vitro and in vivo. We show that glycolysis is essential for tip cell differentiation, whereas both glycolysis and mitochondrial respiration occur during proliferation of non-tip cells and in sprouting angiogenesis in vitro and in vivo. Finally, we demonstrate that inhibition of mitochondrial respiration causes adaptation of EC metabolism by increasing glycolysis and vice versa. In conclusion, our studies show a complex but flexible role of the different metabolic pathways to produce ATP in the regulation of tip cell and non-tip cell differentiation and functioning during sprouting angiogenesis.

Metformin prevents liver tumourigenesis by attenuating fibrosis in a transgenic mouse model of hepatocellular carcinoma

Metformin is a hypoglycaemic agent used to treat type 2 diabetes mellitus (DM2) patients, with a broad safety profile. Since previous epidemiological studies had shown that the incidence of hepatocellular carcinoma (HCC) decreased significantly in metformin treated DM2 patients, we hypothesised that intervention with metformin could reduce the risk of neoplastic transformation of hepatocytes. HCC is the most common primary liver malignancy and it generally originates in a background of liver fibrosis and cirrhosis. In the present study, we took advantage of a transgenic mouse (TG221) characterized by microRNA-221 overexpression, with cirrhotic liver background induced by chronic administration of carbon tetrachloride (CCl4). This mouse model develops fibrosis, cirrhosis and liver tumours that become visible in 100% of mice at 5-6 months of age. Our results demonstrated that metformin intervention improves liver function, inhibits hepatic stellate cell (HSC) activation, reduces liver fibrosis, depletes lipid accumulation in hepatocytes, halts progression to decompensated cirrhosis and abrogates development HCC in CCl4 challenged transgenic mouse model. The study establishes the rationale for investigating metformin in cirrhotic patients regardless of concomitant DM2 status.

Hepatocellular carcinoma serum derived exosomal HIF-1α induces phosphoinositide-3 kinase/protein kinase B signaling to induce the angiogenesis and proliferation of HCC

BACKGROUND

Tumor exosomes are nanovesicles mostly secreted by tumor cells that play roles of paracrine signaling during tumor progression, including tumor-stromal interactions, activation of proliferative pathways and inducing immunosuppression. The hypoxia-inducible factor (HIF) family serve role of the principal molecular mediators of hypoxia in physiological and pathophysiological course. HIF-1α excreted from tumor and stromal cells serves an important role in tumor angiogenesis, especially in hepatocellular carcinoma (HCC). However, exosomal HIF-1α from HCC serum has not been studied extensively. The present study aimed to determine role of HIF-1α derived from HCC serum exosomes in the development of HCC.

METHODS

We extracted exosomes from the serum of 48 patients suffering HCC and 24 healthy individuals. The exosomes were examined by transmission electron microscopy and nanoparticle tracking analysis. The concentrations of exosomal HIF-1α were measured by ELISA. In vitro experiments were performed to testify the exosomal role in human umbilical endothelial cells (HUVECs) and Huh-7 cells by tube formation, cell viability and western blotting analyses. Nude mouse xenograft Huh-7 tumors were generated by injecting HCC patient serum exosomes, healthy individuals' serum exosomes and PBS into nude mice. Tumors in vivo were isolated, weighed and subjected to immunohistochemical assays.

RESULTS

HCC patients exhibited a greater capacity to convert HIF-1α in serum exosomes than normal individuals (P=0.0007), and high serum exosomal HIF-1α levels were correlated with Barcelona Clinic Liver Cancer (BCLC) staging (P=0.031) and the phosphoinositide-3 kinase (PI3K)/protein kinase B (AKT) signaling pathway. The results of flow cytometry analysis demonstrated that the HUVECs cocultured with HCC exosomes turned down the percentage of HUVECs in the G1 phase but turned up the percentage of HUVECs in the S phase (P<0.05). HUVECs and Huh-7 cells cultured with HCC serum exosomes enhanced the proliferation of HUVECs and Huh-7 cells, and the tube formation of HUVECs, while exosomes from healthy individuals and the controls did not. The results demonstrated that serum exosomes from patients with HCC appeared to accelerate tumor growth compared to the control group (P<0.05) and immunohistochemical analysis revealed that the nude mice injected with exosomes from HCC patient serum exhibited higher microvessel density (MVD) (P<0.05).

CONCLUSIONS

HCC serum derived exosomes could induce angiogenesis and the proliferation of HCC potentially via the HIF-1α-PI3K/AKT signaling pathway, it making the prevention and treatment of HCC angiogenesis and proliferation available.

Endothelial tip cells in vitro are less glycolytic and have a more flexible response to metabolic stress than non-tip cells

Formation of new blood vessels by differentiated endothelial tip cells, stalk cells, and phalanx cells during angiogenesis is an energy-demanding process. How these specialized endothelial cell phenotypes generate their energy, and whether there are differences between these phenotypes, is unknown. This may be key to understand their functions, as (1) metabolic pathways are essentially involved in the regulation of angiogenesis, and (2) a metabolic switch has been associated with angiogenic endothelial cell differentiation. With the use of Seahorse flux analyses, we studied metabolic pathways in tip cell and non-tip cell human umbilical vein endothelial cell populations. Our study shows that both tip cells and non-tip cells use glycolysis as well as mitochondrial respiration for energy production. However, glycolysis is significantly lower in tip cells than in non-tip cells. Additionally, tip cells have a higher capacity to respond to metabolic stress. Finally, in non-tip cells, blocking of mitochondrial respiration inhibits endothelial cell proliferation. In conclusion, our data demonstrate that tip cells are less glycolytic than non-tip cells and that both endothelial cell phenotypes can adapt their metabolism depending on microenvironmental circumstances. Our results suggest that a balanced involvement of metabolic pathways is necessary for both endothelial cell phenotypes for proper functioning during angiogenesis.

High-throughput screening of novel pyruvate dehydrogenase kinases inhibitors and biological evaluation of their in vitro and in vivo antiproliferative activity

Overexpression of pyruvate dehydrogenase kinases (PDKs) has been widely noticed in a variety of human solid tumors, which could be regarded as an attractive therapeutic target for cancer therapy. In this paper, we present an enzymatic screening assay and multiple biological evaluations for the identification of potential PDKs, especially PDK1 inhibitors. We identified 9 potential PDKs inhibitors from the screening of an in-house small molecule library, all of the identified inhibitors reduced pyruvate dehydrogenase (PDH) complex phosphorylation. Among which, 4, 5, and 9 displayed the most potent PDKs inhibitory activities, with EC₅₀ values of 0.34, 1.4, and 1.6 μM in an enzymatic assay, respectively. A kinase inhibition assay suggested that 4, 5, and 9 were pan-isoform PDK inhibitors, but more sensitive to PDK1. Meanwhile, the three compounds inhibited HSP90, with IC₅₀ values of 0.78, 3.58, and 2.70 μM, respectively. The cell viability assay indicated that 4 inhibited all of the tested cancer cells proliferation, with a GC₅₀ value of 2.3 μM against NCIH1975 cell, but has little effect on human normal lung cell BEAS-2B cell. In the NCIH1975 xenograft models, 4 displayed strong antitumor activities at a dose of 10 and 20 mg/kg, but with no negative effect on the mice weight. In addition, 4 decreased the ECAR and lactate formation, increased OCR and ROS level in NCIH1975 cancer cell, which could be used as a promising modulator to reprogram the glucose metabolic pathways in NCIH1975 cancer cells.

DNA Damage Response in Prostate Cancer

Prostatic adenocarcinoma (PCa) remains a significant health concern. Although localized PCa can be effectively treated, disseminated disease remains uniformly fatal. PCa is reliant on androgen receptor (AR); as such, first-line therapy for metastatic PCa entails suppression of AR signaling. Although initially effective, recurrent tumors reactivate AR function, leading to a lethal stage of disease termed castration-resistant PCa (CRPC). Recent findings implicate AR signaling in control of DNA repair and show that alterations in DNA damage repair pathways are strongly associated with disease progression and poor outcome. This review will address the DNA repair alterations observed in the clinical setting, explore the anticipated molecular and cellular consequence of DNA repair dysfunction, and consider clinical strategies for targeting tumors with altered DNA repair.

Rapid Assessment of Mitochondrial Complex I Activity and Metabolic Phenotyping of Breast Cancer Cells by NAD(p)H Cytometry

Cancer cells are known to display a variety of metabolic reprogramming strategies to fulfill their own growth and proliferative agenda. With the advent of high resolution imaging strategies, metabolomics techniques, and so forth, there is an increasing appreciation of critical role that tumor cell metabolism plays in the overall breast cancer (BC) growth. In this report, we demonstrate a sensitive, flow-cytometry-based assay for rapidly assessing the metabolic phenotypes in isolated suspensions of breast cancer cells. By measuring the temporal variation of NAD(p)H signals in unlabeled, living cancer cells, and by measuring mitochondrial membrane potential {Δψ_m } in fluorescently labeled cells, we demonstrate that these signals can reliably distinguish the metabolic phenotype of human breast cancer cells and can track the cellular sensitivity to drug candidates. We further show the utility of this metabolic ratio {Δψ_m /NAD(p)H} in monitoring mitochondrial functional improvement as well as metabolic heterogeneity in primary murine tumor cells isolated from tumor biopsies. Together, these results demonstrate a novel possibility for rapid metabolic functional screening applications as well as a metabolic phenotyping tool for determining drug sensitivity in living cancer cells. © 2018 International Society for Advancement of Cytometry.

Circulating tumour DNA, microRNA and metabolites in cerebrospinal fluid as biomarkers for central nervous system malignancies

Central nervous system (CNS) malignancies can be difficult to diagnose and many do not respond satisfactorily to existing therapies. Monitoring patients with CNS malignancies for treatment response and tumour recurrence can be challenging because of the difficulty and risks of brain biopsies, and the low specificity and sensitivity of the less invasive methodologies that are currently available. Uncertainty about tumour diagnosis or whether a tumour has responded to treatment or has recurred can cause delays in therapeutic decisions that can impact patient outcome. Therefore, there is an urgent need to develop and validate reliable and minimally invasive biomarkers for CNS tumours that can be used alone or in combination with current clinical practices. Blood-based biomarkers can be informative in the diagnosis and monitoring of various types of cancer. However, blood-based biomarkers have proven suboptimal for analysis of CNS tumours. In contrast, circulating biomarkers in cerebrospinal fluid (CSF), including circulating tumour DNA, microRNAs and metabolites, hold promise for accurate and minimally invasive assessment of CNS tumours. This review summarises the current understanding of these three types of CSF biomarkers and their potential use in neuro-oncologic clinical practice.

Supplementation with α-ketoglutarate to a low-protein diet enhances amino acid synthesis in tissues and improves protein metabolism in the skeletal muscle of growing pigs

α-Ketoglutarate (AKG) is a crucial intermediate in the tricarboxylic acid (TCA) cycle and can be used for the production of ATP and amino acids in animal tissues. However, the effect of AKG on the expression patterns of genes involved in muscle protein metabolism is largely unknown, and the underlying mechanism remains to be elucidated. Therefore, we used young pigs to investigate the effects of a low crude protein (CP) diet and a low CP diet supplemented with AKG on protein accretion in their skeletal muscle. A total of 27 growing pigs with an initial body weight of 11.96 ± 0.18 kg were assigned randomly to one of the three diets: control (normal recommended 20% CP, NP), low CP (17% CP, LP), or low CP supplemented with 1% AKG (ALP). The pigs were fed their respective diets for 35 days. Free amino acid (AA) profile and hormone levels in the serum, and the expression of genes implicated in protein metabolism in skeletal muscle were examined. Results showed that compared with the control group or LP group, low-protein diets supplemented with AKG enhanced serum and intramuscular free AA concentrations, the mRNA abundances of AA transporters, and serum concentrations of insulin-like growth factor-1 (IGF-1), activated the mammalian target of rapamycin (mTOR) pathway, and decreased serum urea concentration and the mRNA levels for genes related to muscle protein degradation (P < 0.05). In conclusion, these results indicated that addition of AKG to a low-protein diet promotes amino acid synthesis in tissues and improves protein metabolism in skeletal muscle.

Common housekeeping proteins are upregulated in colorectal adenocarcinoma and hepatocellular carcinoma, making the total protein a better "housekeeper"

Housekeeping proteins are essential endogenous controls for normalization as they are expected to be stably expressed. However, the stability of the expression level of housekeeping proteins needs to be assessed considering various experimental conditions. Our study evaluated the degree of variability of 7 commonly used housekeeping proteins with regard to their potential utility as normalizers in 56 pairs of matched colorectal adenocarcinoma (CRC) tissue samples and 6 pairs of hepatocellular carcinoma (HCC) tissue samples using multiple reaction monitoring (MRM) and Western blot analyses. A comprehensive experimental design and strict statistical analysis revealed that the expression levels of these 7 housekeeping proteins were not as stable as expected and they all exhibited upregulations to varying degrees in both the CRC and the HCC tissue samples. Consequently, we verified that using the amount of total protein instead of that of an individual protein can serve as a preferable control for studies of protein expression that require normalization.

Aberrant lipid metabolism in cancer cells - the role of oncolipid-activated signaling

Metabolic activity of malignant cells is very different from that of their nontransformed equivalents, which establishes metabolic reprogramming as an important hallmark of every transformed cell. In particular, the current arena of research in this field aims to understand the regulatory effect of oncogenic signaling on metabolic rewiring in transformed cells in order to exploit this for therapeutic benefit. Alterations in lipid metabolism are one of the main aspects of metabolic rewiring of transformed cells. Up-regulation of several lipogenic enzymes has been reported to be a characteristic of various cancer types. Lysophosphatidic acid (LPA), a simple byproduct of the lipid biosynthesis pathway, has gained immense importance due to its elevated level in several cancers and associated growth-promoting activity. Importantly, a current study revealed its role in increased de novo lipid synthesis through up-regulation of sterol regulatory element-binding protein 1, a master regulator of lipid metabolism. This review summarizes the recent insights in the field of oncolipid LPA-mediated signaling in regard to lipid metabolism in cancers. Future work in this domain is required to understand the up-regulation of the de novo synthesis pathway and the role of its end products in malignant cells. This will open a new arena of research toward the development of specific metabolic inhibitors that can add to the pre-existing chemotherapeutics in order to increase the efficacy of clinical output in cancer patients.

Mitochondrial dysfunction is responsible for fatty acid synthase inhibition-induced apoptosis in breast cancer cells by PdpaMn

Targeting cellular metabolism is becoming a hallmark to overcome drug resistance in breast cancer treatment. Activation of fatty acid synthase (FASN) has been shown to promote breast cancer cell growth. However, there is no concrete report underlying the mechanism associated with mitochondrial dysfunction in relation to fatty acid synthase inhibition-induced apoptosis in breast cancer cells. The current study is aimed at exploring the effect of the novel manganese (Mn) complex, labeled as PdpaMn, on lipid metabolism and mitochondrial function in breast cancer cells. Herein, we observed that PdpaMn displayed strong cytotoxicity on breast cancer cell lines and selectively targeted the tumor without affecting the normal organs or cells in vivo. We also observed that PdpaMn could bind to TE domain of FASN and decrease the activity and the level of expression of FASN, which is an indication that FASN could serve as a target of PdpaMn. In addition, we demonstrated that PdpaMn increased intrinsic apoptosis in breast cancer cells relayed by a suppressed the level of expression of FASN, followed by the release of mitochondrial cytochrome c and the activation of caspases-9. Instigated by the above observations, we hypothesized that PdpaMn-induced apoptosis events are dependent on mitochondrial dysfunction. Indeed, we found that mitochondrial membrane potential (MMP) collapse, mitochondrial oxygen consumption reduction and adenosine triphosphate (ATP) release were deeply repressed. Furthermore, our results showed that PdpaMn significantly increased the reactive oxygen species (ROS) production, and the protection conferred by the free radical scavenger N-acetyl-cysteine (NAC) indicates that PdpaMn-induced apoptosis through an oxidative stress-associated mechanism. More so, the above results have demonstrated that mitochondrial dysfunction participated in FASN inhibition-induce apoptosis in breast cancer cells by PdpaMn. Therefore, PdpaMn may be considered as a good candidate for anti-breast cancer therapeutic option.

Molecular dynamics simulation reveals how phosphorylation of tyrosine 26 of phosphoglycerate mutase 1 upregulates glycolysis and promotes tumor growth

Phosphoglycerate mutase 1 (PGAM1) catalyzes the eighth step of glycolysis and is often found upregulated in cancer cells. To test the hypothesis that the phosphorylation of tyrosine 26 residue of PGAM1 greatly enhances its activity, we performed both conventional and steered molecular dynamics simulations on the binding and unbinding of PGAM1 to its substrates, with tyrosine 26 either phosphorylated or not. We analyzed the simulated data in terms of structural stability, hydrogen bond formation, binding free energy, etc. We found that tyrosine 26 phosphorylation enhances the binding of PGAM1 to its substrates through generating electrostatic environment and structural features that are advantageous to the binding. Our results may provide valuable insights into computer-aided design of drugs that specifically target cancer cells with PGAM1 tyrosine 26 phosphorylated.

Pretreatment serum lactate level as a prognostic biomarker in patients undergoing supratentorial primary brain tumor resection

Introduction

Malignant primary brain tumors are one of the most aggressive cancers. Pretreatment serum nonneuronal biomarkers closely associated with postoperative outcomes are of high clinical relevance. The present study aimed to identify potential pretreatment serum biomarkers that may influence oncological outcomes in patients with primary brain tumors.

Methods

A total of 74 patients undergoing supratentorial primary brain tumor resection were enrolled. Before tumor resection, serum neuronal biomarkers, namely neuron-specific enolase (NSE), S100β, and glial fibrillary acidic protein (GFAP), and serum nonneuronal biomarkers, namely neutrophil gelatinase-associated lipocalin (NGAL), lactate dehydrogenase (LDH), and lactate, were measured and associated postoperative oncological outcomes, including brain tumor grading, progression-free survival (PFS), and overall survival (OS), were compared.

Results

Patients with high-grade brain tumors had significantly higher pretreatment serum lactate levels (p = 0.011). By contrast, other biomarkers were comparable between patients with high-grade and low-grade brain tumors. Receiver operating characteristic curve analysis of serum lactate levels yielded an area under the curve of 0.71 for differentiating between high-grade and low-grade brain tumors. Kaplan–Meier survival analysis revealed patients with high serum lactate levels (≧2.0 mmol/L) had shorter PFS and OS (p = 0.021 and p = 0.093, respectively). In a multiple regression model, only elevated serum lactate levels were associated with poor PFS and OS (p = 0.021 and p = 0.048, respectively).

Conclusions

An elevated pretreatment serum lactate level is a prognostic biomarker of high-grade primary brain tumors and is significantly associated with poor PFS in patients with supratentorial brain tumors undergoing tumor resection. By contrast, other serum biomarkers are not significantly associated with oncological outcomes.

Spatiotemporal Analysis of a Glycolytic Activity Gradient Linked to Mouse Embryo Mesoderm Development

How metabolism is rewired during embryonic development is still largely unknown, as it remains a major technical challenge to resolve metabolic activities or metabolite levels with spatiotemporal resolution. Here, we investigated metabolic changes during development of organogenesis-stage mouse embryos, focusing on the presomitic mesoderm (PSM). We measured glycolytic labeling kinetics from ¹³C-glucose tracing experiments and detected elevated glycolysis in the posterior, more undifferentiated PSM. We found evidence that the spatial metabolic differences are functionally relevant during PSM development. To enable real-time quantification of a glycolytic metabolite with spatiotemporal resolution, we generated a pyruvate FRET-sensor reporter mouse line. We revealed dynamic changes in cytosolic pyruvate levels as cells transit toward a more anterior PSM state. Combined, our approach identifies a gradient of glycolytic activity across the PSM, and we provide evidence that these spatiotemporal metabolic changes are intrinsically linked to PSM development and differentiation.

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Identification of glycolytic activity gradient in mouse presomitic mesoderm

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Development of a pyruvate FRET-reporter mouse model

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Real-time imaging reveals pyruvate gradient dynamics

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Metabolic state is linked to presomitic mesoderm cell differentiation

The KISS1 metastasis suppressor appears to reverse the Warburg effect by shifting from glycolysis to mitochondrial beta-oxidation

The shift by cancer cells toward aerobic glycolysis (Warburg effect) confers selective advantages by utilizing nutrients (e.g., lipids, amino acids, and nucleotides) to build biomass. Lipogenesis is generally enhanced, and its inhibition diminishes proliferation and survival. Re-expression of the metastasis suppressor KISS1 in human melanoma cells results in greater mitochondrial biogenesis, inhibition of glycolysis, utilization of beta-oxidation to provide energy, elevated oxidation of exogenous fatty acids, and increased expression of early-phase lipogenesis genes at both mRNA and protein levels. Correspondingly, the energy sensor AMPKβ is phosphorylated, resulting in inhibitory phosphorylation of acetyl-CoA carboxylase (ACC), which is linked to enhanced beta-oxidation. Furthermore, PGC1α is required for KISS1-mediated phosphorylation of ACC and metastasis suppression. Collectively, these data further support the linkages between macromolecular metabolism and metastasis.

KEY MESSAGES

• KISS1 alters fatty acid metabolism. • There may be connections between metastasis and metabolism. • PGC1alpha appears to be downstream mediator of KISS1 metastasis suppression.

Mitochondrial Deficiencies in the Predisposition to Paraganglioma

Paragangliomas and pheochromocytomas are rare neuroendocrine tumours with a very strong genetic component. It is estimated that around 40% of all cases are caused by a germline mutation in one of the 13 predisposing genes identified so far. Half of these inherited cases are intriguingly caused by mutations in genes encoding tricarboxylic acid enzymes, namely SDHA, SDHB, SDHC, SDHD, and SDHAF2 genes, encoding succinate dehydrogenase and its assembly protein, FH encoding fumarate hydratase, and MDH2 encoding malate dehydrogenase. These mutations may also predispose to other type of cancers, such as renal cancer, leiomyomas, or gastro-intestinal stromal tumours. SDH, which is also the complex II of the oxidative respiratory chain, was the first mitochondrial enzyme to be identified having tumour suppressor functions, demonstrating that 80 years after his initial proposal, Otto Warburg may have actually been right when he hypothesized that low mitochondrial respiration was the origin of cancer. This review reports the current view on how such metabolic deficiencies may lead to cancer predisposition and shows that the recent data may lead to the development of innovative therapeutic strategies and establish precision medicine approaches for the management of patients affected by these rare diseases.

Strategies to Target Glucose Metabolism in Tumor Microenvironment on Cancer by Flavonoids

The imbalance between glucose metabolism and cancer cell growth in tumor microenvironment (TME), which are closely related with the occurrence and progression of cancer. Accumulating evidence has demonstrated that flavonoids exert many biological properties, including antioxidant and anticarcinogenic activities. Recently, the roles and applications of flavonoids, particularly in relation to glucose metabolism in cancers, have been highlighted. Thus, the identification of flavonoids targeting alternative glucose metabolism pathways in TME may represent an attractive approach to the more effective therapeutic strategies for cancer. In this review, we will focus on the roles of flavonoids in regulating glucose metabolism and cancer cell growth in TME, such as proliferation advantage, cell mobility, and chemoresistance to cancer, as well as modifiers of thermal sensitivity. Not only have such large-scale endeavors been useful in providing fundamental insights into natural and synthesized flavonoids that can prevent and treat cancer, but also have led to the discovery of potential targets for cancer therapy.

Identification of NCK1 as a novel downstream effector of STAT3 in colorectal cancer metastasis and angiogenesis

Signal transducer and activator of transcription 3 (STAT3) is known to activate targets associated with invasion, proliferation, and angiogenesis in a wide variety of cancers. The adaptor protein NCK1 is involved in cytoskeletal movement and was identified as a STAT3-associated target in human tumors. However, the underlying molecular mechanism associated with colorectal cancer (CRC) metastasis is not yet completely understood. In this study, we report a novel STAT3 to NCK1 signaling pathway in colorectal cancer (CRC). We investigated the expression of NCK1 and its potential clinical and biological significance in CRC. NCK1 was noticeably up-regulated in human CRC tissues. NCK1 was also significantly associated with serosal invasion, lymph metastasis, and tumor-node-metastasis classification but was inversely correlated with differentiation. Gain-of-function and loss-of-function studies have shown that ectopic expression of NCK1 enhanced metastasis and angiogenesis in CRC cells. By gene expression analyses, we revealed a high co-overexpression of STAT3 and NCK1 in CRC tissues. Ectopic overexpression of STAT3 in CRC cells induced the expression of NCK1, whereas STAT3 knockdown decreased the expression of NCK1. Promoter activation and binding analyses demonstrated that STAT3 promoted the expression of NCK1 via direct action on the NCK1 promoter. The knock down of NCK1 partially reduced the CRC cell metastasis and angiogenesis promoted by STAT3. Additionally, by co-immunoprecipitation assays, we verified that NCK1 interacted with PAK1, which resulted in the activation of the PAK1/ERK pathway. STAT3 induced the transcription of NCK1 and triggered a PAK1/ERK cascade in CRC. These findings suggest a novel STAT3 to NCK1 to PAK1/ERK signaling mechanism that is potentially critical for CRC metastasis and angiogenesis.

Tumor stroma interaction is mediated by monocarboxylate metabolism

Human breast tumors contain significant amounts of stromal cells. There exists strong evidence that these stromal cells support cancer development and progression by altering various pathways (e.g. downregulation of tumor suppressor genes or autocrine signaling loops). Here, we suggest that stromal carcinoma-associated fibroblasts (CAFs), shown to be generated from bone marrow-derived mesenchymal stem cells, may (i) recycle tumor-derived lactate for their own energetic requirements, thereby sparing glucose for neighboring glycolytic tumor cells, and (ii) subsequently secrete surplus energetically and biosynthetically valuable metabolites of lactate oxidation, such as pyruvate, to support tumor growth. Lactate, taken up by stromal CAFs, is converted to pyruvate, which is then utilized by CAFs for energy needs as well as excreted and shared with tumor cells. We have interrogated lactate oxidation in CAFs to determine what metabolites may be secreted, and how they may affect the metabolism and growth of MDA-MB-231 breast cancer cells. We found that CAFs secrete pyruvate as a metabolite of lactate oxidation. Further, we show that pyruvate is converted to lactate to promote glycolysis in MDA-MB-231 cells and helps to control elevated ROS levels in these tumor cells. Finally, we found that inhibiting or interfering with ROS management, using the naturally occurring flavonoid phloretin (found in apple tree leaves), adds to the cytotoxicity of the conventional chemotherapeutic agent doxorubicin. Our work demonstrates that a lactate-pyruvate, reciprocally-supportive metabolic relationship may be operative within the tumor microenvironment (TME) to support tumor growth, and may be a useful drug target.