Biosynthesis and Significance of Fatty Acids, Glycerophospholipids, and Triacylglycerol in the Processes of Glioblastoma Tumorigenesis

The Warburg hypothesis and the emergence of the mitochondrial metabolic theory of cancer

Otto Warburg originally proposed that cancer arose from a two-step process. The first step involved a chronic insufficiency of mitochondrial oxidative phosphorylation (OxPhos), while the second step involved a protracted compensatory energy synthesis through lactic acid fermentation. His extensive findings showed that oxygen consumption was lower while lactate production was higher in cancerous tissues than in non-cancerous tissues. Warburg considered both oxygen consumption and extracellular lactate as accurate markers for ATP production through OxPhos and glycolysis, respectively. Warburg's hypothesis was challenged from findings showing that oxygen consumption remained high in some cancer cells despite the elevated production of lactate suggesting that OxPhos was largely unimpaired. New information indicates that neither oxygen consumption nor lactate production are accurate surrogates for quantification of ATP production in cancer cells. Warburg also did not know that a significant amount of ATP could come from glutamine-driven mitochondrial substrate level phosphorylation in the glutaminolysis pathway with succinate produced as end product, thus confounding the linkage of oxygen consumption to the origin of ATP production within mitochondria. Moreover, new information shows that cytoplasmic lipid droplets and elevated aerobic lactic acid fermentation are both biomarkers for OxPhos insufficiency. Warburg's original hypothesis can now be linked to a more complete understanding of how OxPhos insufficiency underlies dysregulated cancer cell growth. These findings can also address several questionable assumptions regarding the origin of cancer thus allowing the field to advance with more effective therapeutic strategies for a less toxic metabolic management and prevention of cancer.

Fatty acid synthase inhibitor cerulenin attenuates glioblastoma progression by reducing EMT and stemness phenotypes, inducing oxidative and ER stress response, and targeting PI3K/AKT/NF-κB axis

Targeting cellular metabolism is becoming a critical approach for stopping cancer progression. Limited information is available regarding the effects of inhibiting the lipogenic enzyme fatty acid synthase (FASN) in glioblastoma (GB) cells (grade-IV-astrocytoma), which have high invasion and low response to standard treatments. Herein, we used cerulenin (CER) to inhibit FASN. CER treatments (3.6 μg/mL/48 h and 5.55 μg/mL/48 h indicate IC20 and IC50 values, respectively) led to a dose- and time-dependent decrease in the viability of the U-87MG human GB cells. A significant decrease was detected in the levels of fatty acids, including palmitic acid, determined by GS-MS analysis. FASN inhibition attenuated cell motility, 2D and 3D-clonogenic survival, and cell differentiation characteristics (related markers of epithelial-mesenchymal transition/EMT and stemness). Moreover, treatments caused mitochondrial membrane potential (MMP) collapse and increased intracellular reactive oxygen species (ROS) levels. Protein aggregates and ER stress in the cells also increased. Remarkably, despite increased Hsp70 and p-HSF1 levels against induced cellular stress, CER promoted markedly autophagy and apoptosis. The network pharmacology approach revealed that protein and lipid kinases are crucial targets in cell signaling, and PI3K, AKT, and NF-κB levels were confirmed by immunoblotting. The results demonstrated for the first time that inhibiting FA production and FASN function induces cell death through ROS generation and ER stress while simultaneously reducing the motility and aggressiveness of U-87MG human glioblastoma cells by attenuating EMT and stemness phenotypes. Therefore, blocking lipid metabolism using CER may be considered as a good candidate for GB therapeutic option.

Fatty acid metabolism-related enzymes in colorectal cancer metastasis: from biological function to molecular mechanism

Colorectal cancer (CRC) is a highly aggressive and life-threatening malignancy that metastasizes in ~50% of patients, posing significant challenges to patient survival and treatment. Fatty acid (FA) metabolism regulates proliferation, immune escape, metastasis, angiogenesis, and drug resistance in CRC. FA metabolism consists of three pathways: de novo synthesis, uptake, and FA oxidation (FAO). FA metabolism-related enzymes promote CRC metastasis by regulating reactive oxygen species (ROS), matrix metalloproteinases (MMPs), angiogenesis and epithelial-mesenchymal transformation (EMT). Mechanistically, the PI3K/AKT/mTOR pathway, wnt/β-catenin pathway, and non-coding RNA signaling pathway are regulated by crosstalk of enzymes related to FA metabolism. Given the important role of FA metabolism in CRC metastasis, targeting FA metabolism-related enzymes and their signaling pathways is a potential strategy to treat CRC metastasis.

Serum and urine metabolomics based on UPLC-QTOF/MS reveal the effect and potential mechanism of "schisandra-evodia" herb pair in the treatment of Alzheimer's disease

The "schisandra-evodia" herb pair (S-E) is a herbal preparation to treat Alzheimer's disease (AD). This study aims to investigate the therapeutic efficacy and potential mechanism of S-E in AD rats, utilizing pharmacodynamic assessments and serum- and urine-based metabolomic analyses. Pharmacodynamic assessments included Morris water maze test, hematoxylin-eosin staining and immunohistochemistry experiments. The results of the study showed that the AD model was successful; the S-E significantly enhanced long-term memory and spatial learning in AD rats. Meanwhile, S-E notably ameliorated Aβ25-35-induced cognitive impairment, improved hippocampal neuron morphology, decreased Aβ deposition in the hippocampus and mitigated inflammatory damage. We then analyzed serum and urine samples using UPLC-MS/MS to identify potential biomarkers and metabolic pathways. Metabolomic analysis revealed alterations in 40 serum metabolites and 38 urine metabolites following S-E treatment, predominantly affecting pathways related to taurine and hypotaurine metabolism, linoleic acid metabolism, α-linolenic acid metabolism, glycerophospholipid metabolism and arachidonic acid metabolism. This study elucidates the biochemical mechanism underlying AD and the metabolic pathway influenced by S-E, laying the groundwork for future clinical applications.

Metabolic Contrasts: Fatty Acid Oxidation and Ketone Bodies in Healthy Brains vs. Glioblastoma Multiforme

The metabolism of glucose and lipids plays a crucial role in the normal homeostasis of the body. Although glucose is the main energy substrate, in its absence, lipid metabolism becomes the primary source of energy. The main means of fatty acid oxidation (FAO) takes place in the mitochondrial matrix through β-oxidation. Glioblastoma (GBM) is the most common form of primary malignant brain tumor (45.6%), with an incidence of 3.1 per 100,000. The metabolic changes found in GBM cells and in the surrounding microenvironment are associated with proliferation, migration, and resistance to treatment. Tumor cells show a remodeling of metabolism with the use of glycolysis at the expense of oxidative phosphorylation (OXPHOS), known as the Warburg effect. Specialized fatty acids (FAs) transporters such as FAT, FABP, or FATP from the tumor microenvironment are overexpressed in GBM and contribute to the absorption and storage of an increased amount of lipids that will provide sufficient energy used for tumor growth and invasion. This review provides an overview of the key enzymes, transporters, and main regulatory pathways of FAs and ketone bodies (KBs) in normal versus GBM cells, highlighting the need to develop new therapeutic strategies to improve treatment efficacy in patients with GBM.

Effect of feeding fermented distiller's grains diets on immune status and metabolomics of spleen and mesenteric lymph nodes in finishing cattle

To explore the effect of feeding fermented distiller's grains (FDG) diets on spleen and mesenteric lymph nodes (MLN) immune status and metabolomics in finishing cattle, eighteen Guanling crossbred cattle (18 months old, 250.0 ± 25 kg) were randomly divided into 3 groups: a basal diet (Control) group, an FDG-15% group, and an FDG-30% group (containing 0%, 15% and 30% FDG to partially replace the concentrates, respectively). After 75 days, the spleens and MLN were collected for detection of relative spleen weight, immune parameters, and metabolomic analysis. Compared with the Control group, FDG-30% group significantly increased (P<0.05) the relative spleen weight. In addition, the level of IL-17A in the spleen of the FDG-30% group was significantly higher than that of the FDG-15% group. Metabolomic analysis showed that differential metabolites (VIP＞1, P＜0.05) of spleen and MLN in FDG-15% and FDG-30% groups are mostly lipids and lipid molecules. KEGG analysis illustrated that choline metabolism in cancer, glycerophospholipid metabolism, biosynthesis of unsaturated fatty acids and insulin resistance were metabolic pathways in spleen shared by FDG-15% group vs.Control group and FDG-30% group vs.Control group, and choline metabolism in cancer was a metabolic pathway in MLN shared by FDG-15% group vs.Control group and FDG-30% group vs.Control group. These results suggest that feeding FDG may promote spleen development by regulating choline metabolism in cancer, glycerophospholipid metabolism, biosynthesis of unsaturated fatty acids and insulin resistance. Additionally, it may affect MLN development by regulating choline metabolism in cancer. SIGNIFICANCE: Fermented distiller's grains (FDG) is a high quality alternative to feed because it is rich in beneficial microorganisms and nutrients. The spleen and mesenteric lymph nodes (MLN) are important peripheral immune organs in animals, whose status reflects the health of the animal. However, there are few reports on the effect of feeding FDG diets on spleen and MLN immune status and metabolomics in domestic animals. In this study, we found that feeding FDG may promote spleen development by regulating choline metabolism in cancer, glycerophospholipid metabolism, biosynthesis of unsaturated fatty acids and insulin resistance metabolic pathways, and may affect MLN development by regulating choline metabolism in cancer. This study extends our understanding of the metabolomics of the spleen and MLN in FDG and helps to further understand of the immunomodulatory effects of the FDG diet.

Transcriptome and Metabolome Analyses Reveal the Mechanism of Corpus Luteum Cyst Formation in Pigs

Corpus luteum cysts are a serious reproductive disorder that affects the reproductive performance of sows. In this study, transcriptome and metabolome datasets of porcine normal and cyst luteal granulosa cells were generated to explore the molecular mechanism of luteal cyst formation. We obtained 28.9 Gb of high-quality transcriptome data from luteum tissue samples and identified 1048 significantly differentially expressed genes between the cyst and normal corpus luteum samples. Most of the differentially expressed genes were involved in cancer and immune signaling pathways. Furthermore, 22,622 information-containing positive and negative ions were obtained through gas chromatography-mass spectrometry, and 1106 metabolites were successfully annotated. Important differentially abundant metabolites and pathways were identified, among which abnormal lipid and choline metabolism were involved in the formation of luteal cysts. The relationships between granulosa cells of luteal cysts and cancer, immune-related signaling pathways, and abnormalities of lipid and choline metabolism were elaborated, providing new entry points for studying the pathogenesis of porcine luteal cysts.

Identification of Diagnostic Metabolic Signatures in Thyroid Tumors Using Mass Spectrometry Imaging

"Gray zone" thyroid follicular tumors are difficult to diagnose, especially when distinguishing between benign follicular thyroid adenoma (FTA) and malignant carcinoma (FTC). Thus, proper classification of thyroid follicular diseases may improve clinical prognosis. In this study, the diagnostic performance of metabolite enzymes was evaluated using imaging mass spectrometry to distinguish FTA from FTC and determine the association between metabolite enzyme expression with thyroid follicular borderline tumor diagnosis. Air flow-assisted desorption electrospray ionization mass spectrometry imaging (AFAIDESI-MSI) was used to build a classification model for thyroid follicular tumor characteristics among 24 samples. We analyzed metabolic enzyme marker expression in an independent validation set of 133 cases and further evaluated the potential biological behavior of 19 thyroid borderline lesions. Phospholipids and fatty acids (FAs) were more abundant in FTA than FTC (p < 0.001). The metabolic enzyme panel, which included FA synthase and Ca2+-independent PLA2, was further validated in follicular thyroid tumors. The marker combination showed optimal performance in the validation group (area under the ROC, sensitivity, and specificity: 73.6%, 82.1%, and 60.6%, respectively). The findings indicate that AFAIDESI-MSI, in combination with low metabolic enzyme expression, could play a role in the diagnosis of thyroid follicular borderline tumors for strict follow-up.