Hexokinase II promotes the Warburg effect by phosphorylating alpha subunit of pyruvate dehydrogenase

Salvia miltiorrhiza inhibited lung cancer through aerobic glycolysis suppression

Lung cancer causes the most cancer deaths and needs new treatment strategies urgently. Salvia miltiorrhiza is a classical Chinese herb and a strong candidate for tumor treatment. The study found that the aqueous extract of Salvia miltiorrhiza (DSAE), ethanol extract of Salvia miltiorrhiza (DSEE), and its active components danshensu (DSS) and dihydrotanshinone I (DHI), exhibited antineoplastic effects in vivo and in vitro. Meanwhile, DSAE, DSEE, DSS, and DHI reduced glycolysis metabolites (ATP, lactate, and pyruvate contents) production, decreased aerobic glycolysis enzymes, and inhibited Seahorse indexes (OCR and ECAR) in Lewis lung cancer cells (LLC). Data suggests that aerobic glycolysis could be inhibited by Salvia miltiorrhiza and its components. The administration of DSS and DHI further reduced the level of HKII in lung cancer cell lines that had been inhibited with HK-II antagonists (2-deoxyglucose, 2-DG; 3-bromo-pyruvate, 3-BP) or knocked down with siRNA, thereby exerting an anti-lung cancer effect. Although DSS and DHI decreased the level of HKII in HKII-Knock-In lung cancer cell line, their anti-lung cancer efficacy remained limited due to the persistent overexpression of HKII in these cells. Reiterating the main points, we have discovered that the anti-lung cancer effects of Salvia miltiorrhiza may be attributed to its ability to regulate HKII expression levels, thereby inhibiting aerobic glycolysis. This study not only provides a new research paradigm for the treatment of cancer by Salvia miltiorrhiza, but also highlights the important link between glucose metabolism and the effect of Salvia Miltiorrhiza.

Exploring the mystery of tumor metabolism: Warburg effect and mitochondrial metabolism fighting side by side

The metabolic reconfiguration of tumor cells constitutes a pivotal aspect of tumor proliferation and advancement. This study delves into two primary facets of tumor metabolism: the Warburg effect and mitochondrial metabolism, elucidating their contributions to tumor dominance. The Warburg effect facilitates efficient energy acquisition by tumor cells through aerobic glycolysis and lactic acid fermentation, offering metabolic advantages conducive to growth and proliferation. Simultaneously, mitochondrial metabolism, serving as the linchpin of sustained tumor vitality, orchestrates the tricarboxylic acid cycle and electron transport chain, furnishing a steadfast and dependable wellspring of biosynthesis for tumor cells. Regarding targeted therapy, this discourse examines extant strategies targeting tumor glycolysis and mitochondrial metabolism, underscoring their potential efficacy in modulating tumor metabolism while envisaging future research trajectories and treatment paradigms in the realm of tumor metabolism. By means of a thorough exploration of tumor metabolism, this study aspires to furnish crucial insights into the regulation of tumor metabolic processes, thereby furnishing valuable guidance for the development of novel therapeutic modalities. This comprehensive deliberation is poised to catalyze advancements in tumor metabolism research and offer novel perspectives and pathways for the formulation of cancer treatment strategies in the times ahead.

Mitochondrion: Main organelle in orchestrating cancer escape from chemotherapy

BACKGROUND

Chemoresistance is a challenging barrier to cancer therapy, and in this context, the role of mitochondria is significant. We put emphasis on key biological characteristics of mitochondria, contributing to tumor escape from various therapies, to find the "Achilles' Heel" of cancer cells for future drug design.

RECENT FINDINGS

The mitochondrion is a dynamic organelle, and its existence is important for tumor growth. Its metabolites also cooperate with cell signaling in tumor proliferation and drug resistance.

CONCLUSION

Biological characteristics of this organelle, such as redox balance, DNA depletion, and metabolic reprogramming, provide flexibility to cancer cells to cope with therapy-induced stress.

Real-time resolution studies of the regulation of pyruvate-dependent lactate metabolism by hexokinases in single cells

Lactate is a mitochondrial substrate for many tissues including neuron, muscle, skeletal and cardiac, as well as many cancer cells, however little is known about the processes that regulate its utilization in mitochondria. Based on the close association of Hexokinases (HK) with mitochondria, and the known cardio-protective role of HK in cardiac muscle, we have investigated the regulation of lactate and pyruvate metabolism by hexokinases (HKs), utilizing wild-type HEK293 cells and HEK293 cells in which the endogenous HKI and/or HKII have been knocked down to enable overexpression of wild type and mutant HKs. To assess the real-time changes in intracellular lactate levels the cells were transfected with a lactate specific FRET probe. In the HKI/HKII double knockdown cells, addition of extracellular pyruvate caused a large and sustained decrease in lactate. This decrease was rapidly reversed upon inhibition of the malate aspartate shuttle by aminooxyacetate, or inhibition of mitochondrial oxidative respiration by NaCN. These results suggest that in the absence of HKs, pyruvate-dependent activation of the TCA cycle together with the malate aspartate shuttle facilitates lactate transformation into pyruvate and its utilization by mitochondria. With replacement by overexpression of HKI or HKII the cellular response to pyruvate and NaCN was modified. With either hexokinase present, both the decrease in lactate due to the addition of pyruvate and the increase following addition of NaCN were either transient or suppressed altogether. Blockage of the pentose phosphate pathway with the inhibitor 6-aminonicotinamide (6-AN), abolished the effects of HK replacement. These results suggest that blocking of the malate aspartate shuttle by HK may involve activation of the pentose phosphate pathway and increased NADPH production.

Formyl-peptide receptor 2 signalling triggers aerobic metabolism of glucose through Nox2-dependent modulation of pyruvate dehydrogenase activity

The human formyl-peptide receptor 2 (FPR2) is activated by an array of ligands. By phospho-proteomic analysis we proved that FPR2 stimulation induces redox-regulated phosphorylation of many proteins involved in cellular metabolic processes. In this study, we investigated metabolic pathways activated in FPR2-stimulated CaLu-6 cells. The results showed an increased concentration of metabolites involved in glucose metabolism, and an enhanced uptake of glucose mediated by GLUT4, the insulin-regulated member of GLUT family. Accordingly, we observed that FPR2 transactivated IGF-IRβ/IRβ through a molecular mechanism that requires Nox2 activity. Since cancer cells support their metabolism via glycolysis, we analysed glucose oxidation and proved that FPR2 signalling promoted kinase activity of the bifunctional enzyme PFKFB2 through FGFR1/FRS2- and Akt-dependent phosphorylation. Furthermore, FPR2 stimulation induced IGF-IRβ/IRβ-, PI3K/Akt- and Nox-dependent inhibition of pyruvate dehydrogenase activity, thus preventing the entry of pyruvate in the tricarboxylic acid cycle. Consequently, we observed an enhanced FGFR-dependent lactate dehydrogenase (LDH) activity and lactate production in FPR2-stimulated cells. As LDH expression is transcriptionally regulated by c-Myc and HIF-1, we demonstrated that FPR2 signalling promoted c-Myc phosphorylation and Nox-dependent HIF-1α stabilization. These results strongly indicate that FPR2-dependent signalling can be explored as a new therapeutic target in treatment of human cancers.

Experimental evidence and clinical implications of Warburg effect in the skeletal muscle of Fabry disease

Skeletal muscle (SM) pain and fatigue are common in Fabry disease (FD). Here, we undertook the investigation of the energetic mechanisms related to FD-SM phenotype. A reduced tolerance to aerobic activity and lactate accumulation occurred in FD-mice and patients. Accordingly, in murine FD-SM we detected an increase in fast/glycolytic fibers, mirrored by glycolysis upregulation. In FD-patients, we confirmed a high glycolytic rate and the underutilization of lipids as fuel. In the quest for a tentative mechanism, we found HIF-1 upregulated in FD-mice and patients. This finding goes with miR-17 upregulation that is responsible for metabolic remodeling and HIF-1 accumulation. Accordingly, miR-17 antagomir inhibited HIF-1 accumulation, reverting the metabolic-remodeling in FD-cells. Our findings unveil a Warburg effect in FD, an anaerobic-glycolytic switch under normoxia induced by miR-17-mediated HIF-1 upregulation. Exercise-intolerance, blood-lactate increase, and the underlying miR-17/HIF-1 pathway may become useful therapeutic targets and diagnostic/monitoring tools in FD.

Cuproptosis-Related Genes Are Associated with Cell Cycle and Serve as the Prognostic Signature for Clear Cell Renal Cell Carcinoma

Cuproptosis is a newly discovered type of cell death. The role and potential mechanism of Cuproptosis-related genes (CRGs) in the prognosis of cancer patients are not fully understood. In this study, we included two cohorts of clear cell renal cell carcinoma patients, TCGA and E-MTAB-1980. The TCGA cohort is used as a training set to construct a CRG signature using the LASSO-cox regression analysis, and E-MTAB-1980 is used as a cohort for verification. A total of eight genes (FDX1, LIAS, LIPT1, DLAT, PDHA1, MTF1, GLS, CDKN2A) were screened to construct a prognostic model in the TCGA cohort. There is a significant difference in OS (p < 0.0001) between the high and low cuproptosis score group, and a similar difference is also observed in the OS (p = 0.0054) of the E-MTAB-1980 cohort. The area under the ROC curves (AUC) were 0.87, 0.82, and 0.78 at 1, 3, and 5 years in the TCGA cohort, respectively. Finally, gene set enrichment analysis revealed that CRGs were associated with cell cycle and mitotic signaling pathways.

Pyruvate Dehydrogenase Contributes to Drug Resistance of Lung Cancer Cells Through Epithelial Mesenchymal Transition

Recently, there has been a growing interest on the role of mitochondria in metastatic cascade. Several reports have shown the preferential utilization of glycolytic pathway instead of mitochondrial respiration for energy production and the pyruvate dehydrogenase (PDH) has been considered to be a contributor to this switch in some cancers. Since epithelial mesenchymal transition (EMT) is proposed to be one of the significant mediators of metastasis, the molecular connections between cancer cell metabolism and EMT may reveal underlying mechanisms and improve our understanding on metastasis. In order to explore a potential role for PDH inhibition on EMT and associated drug resistance, we took both pharmacological and genetic approaches, and selectively inhibited or knocked down PDHA1 by using Cpi613 and shPDHA1, respectively. We found that both approaches triggered morphological changes and characteristics of EMT (increase in mesenchymal markers). This change was accompanied by enhanced wound healing and an increase in migration. Interestingly, cells were more resistant to many of the clinically used chemotherapeutics following PDH inhibition or PDHA1 knockdown. Furthermore, the TGFβRI (known as a major inducer of the EMT) inhibitor (SB-431542) together with the PDHi, was effective in reversing EMT. In conclusion, interfering with PDH induced EMT, and more importantly resulted in chemoresistance. Therefore, our study demonstrates the need for careful consideration of PDH-targeting approaches in cancer treatment.

A Comprehensive Proteome and Acetyl-Proteome Atlas Reveals Molecular Mechanisms Adapting to the Physiological Changes From Pre-laying to Peak-Laying Stage in Liver of Hens (Gallus gallus)

Along with sexual maturity, the liver undergoes numerous metabolic processes to adapt the physiological changes associated with egg-laying in hens. However, mechanisms regulating the processes were unclear. In this study, comparative hepatic proteome and acetyl-proteome between pre- and peak-laying hens were performed. The results showed that the upregulated proteins were mainly related to lipid and protein biosynthesis, while the downregulated proteins were mainly involved in pyruvate metabolism and were capable of inhibiting gluconeogenesis and lactate synthesis in peak-laying hens compared with that in pre-laying hens. With unchanged expression level, the significant acetylated proteins were largely functioned on activation of polyunsaturated fatty acid oxidation in peroxisome, while the significant deacetylated proteins were principally used to elevate medium and short fatty acid oxidation in mitochondria and oxidative phosphorylation. Most of the proteins which involved in gluconeogenesis, lipid transport, and detoxification were influenced by both protein expression and acetylation. Taken overall, a novel mechanism wherein an alternate source of acetyl coenzyme A was produced by activation of FA oxidation and pyruvate metabolism to meet the increased energy demand and lipid synthesis in liver of laying hens was uncovered. This study provides new insights into molecular mechanism of adaptation to physiological changes in liver of laying hens.

Long non-coding RNA SLC2A1-AS1 induced by GLI3 promotes aerobic glycolysis and progression in esophageal squamous cell carcinoma by sponging miR-378a-3p to enhance Glut1 expression

BACKGROUND

Emerging evidence demonstrates that lncRNAs play pivotal roles in tumor energy metabolism; however, the detailed mechanisms of lncRNAs in the regulation of tumor glycolysis remain largely unknown.

METHODS

The expression of SLC2A1-AS1 was investigated by TCGA, GEO dataset and qRT-PCR. The binding of GLI3 to SLC2A1-AS1 promoter was detected by Luciferase Reporter Assay System and Ago2-RIP assay. FISH was performed to determine the localization of SLC2A1-AS1 in ESCC cells. Double Luciferase Report assay was used to investigate the interaction of miR-378a-3p with SLC2A1-AS1 and Glut1. Gain-of-function and Loss-of-function assay were performed to dissect the function of SLC2A1-AS1/miR-378a-3p/Glut1 axis in ESCC progression in vitro and in vivo.

RESULTS

We identified a novel lncRNA SLC2A1-AS1 in ESCC. SLC2A1-AS1 was frequently overexpressed in ESCC tissues and cells, and its overexpression was associated with TNM stage, lymph node metastasis and poor prognosis of ESCC patients. Importantly, GLI3 and SLC2A1-AS1 formed a regulatory feedback loop in ESCC cells. SLC2A1-AS1 promoted cell growth in vitro and in vivo, migration and invasion, and suppressed apoptosis, leading to EMT progression and increased glycolysis in ESCC cells. SLC2A1-AS1 functioned as ceRNA for sponging miR-378a-3p, resulting in Glut1 overexpression in ESCC cells. MiR-378a-3p inhibited cell proliferation and invasion as well as induced apoptosis, resulting in reduced glycolysis, which was partly reversed by SLC2A1-AS1 or Glut1 overexpression in ESCC cells.

CONCLUSION

SLC2A1-AS1 plays important roles in ESCC development and progression by regulating glycolysis, and SLC2A1-AS1/miR-378a-3p/Glut1 regulatory axis may be a novel therapeutic target in terms of metabolic remodeling of ESCC patients.

Sputum-Based Tumor Fluid Biopsy: Isolation and High-Throughput Single-Cell Analysis of Exfoliated Tumor Cells for Lung Cancer Diagnosis

Timely and effective diagnosis is of great significance for improving the survival rate of lung cancer patients. Although histopathology is the main diagnostic tool among the existing methods for lung cancer diagnosis, it is not suitable for high-risk groups, early lung cancer patients, patients with advanced-stage disease, and other situations wherein tumor tissues cannot be obtained. In view of this, we proposed an innovative lung cancer diagnosis method employing for the first time a microfluidic technology for high-efficiency isolation and high-throughput single-cell analysis of exfoliated tumor cells (ETCs) in sputum. This method fully combines the advantages of traditional sputum cytology and microfluidic technology and realizes the diagnosis of lung cancer by using a small amount of repeatable ETCs instead of the tumor tissue. This method is expected to provide a practical strategy for the non-invasive detection of lung cancer patients and lung cancer screening for high-risk groups.

Breast cancer fibroblasts and cross-talk

The breast tumor microenvironment is one of the crucial elements supporting breast cancer tumor progression and metastasis. The fibroblasts are the chief cellular component of the stromal microenvironment and are pathologically activated and differentiated into breast cancer-associated fibroblasts (CAFs). The catabolic phenotype of breast CAFs arises due to metabolic reprogramming of these fibroblasts under pseudo-hypoxic conditions. The metabolic intermediates and ATP produced by the breast CAFs are exploited by the neighboring cancer cells for energy generation. The growth factors, cytokines, and chemokines secreted by the CAFs help fuel tumor growth, invasion, and dissemination. Moreover, the interplay between breast CAFs and cancer cells, mediated by the growth factors, ROS, metabolic intermediates, exosomes, and catabolite transporters, aids in building a favorable microenvironment that promotes cancer cell proliferation, tumor progression, and metastasis. Therefore, identifying effective means to target the reprogrammed metabolism of the breast CAFs and the cross-communication between CAFs and cancer cells serve as promising strategies to develop anti-cancer therapeutics. Henceforth, the scope of the present review ranges from discussing the underlying characteristics of breast CAFs, mechanisms of metabolic reprogramming in breast CAFs, and the nature of interactions between breast CAFs and cancer cells to studying the intricacies of reprogrammed metabolism targeted cancer therapy.

CRKL promotes hepatocarcinoma through enhancing glucose metabolism of cancer cells via activating PI3K/Akt

Abnormal glucose metabolism may contribute to cancer progression. As a member of the CRK (v-crk sarcoma virus CT10 oncogene homologue) adapter protein family, CRKL (CRK-like) associated with the development and progression of various tumours. However, the exact role and underlying mechanism of CRKL on energy metabolism remain unknown. In this study, we investigated the effect of CRKL on glucose metabolism of hepatocarcinoma cells. CRKL and PI3K were found to be overexpressed in both hepatocarcinoma cells and tissues; meanwhile, CRKL up-regulation was positively correlated with PI3K up-regulation. Functional investigations revealed that CRKL overexpression promoted glucose uptake, lactate production and glycogen synthesis of hepatocarcinoma cells by up-regulating glucose transporters 1 (GLUT1), hexokinase II (HKII) expression and down-regulating glycogen synthase kinase 3β (GSK3β) expression. Mechanistically, CRKL promoted glucose metabolism of hepatocarcinoma cells via enhancing the CRKL-PI3K/Akt-GLUT1/HKII-glucose uptake, CRKL-PI3K/Akt-HKII-glucose-lactate production and CRKL-PI3K/Akt-Gsk3β-glycogen synthesis. We demonstrate CRKL facilitates HCC malignancy via enhancing glucose uptake, lactate production and glycogen synthesis through PI3K/Akt pathway. It provides interesting fundamental clues to CRKL-related carcinogenesis through glucose metabolism and offers novel therapeutic strategies for hepatocarcinoma.

Vitamin C activates pyruvate dehydrogenase (PDH) targeting the mitochondrial tricarboxylic acid (TCA) cycle in hypoxic KRAS mutant colon cancer

Background: In hypoxic tumors, positive feedback between oncogenic KRAS and HIF-1α involves impressive metabolic changes correlating with drug resistance and poor prognosis in colorectal cancer. Up to date, designed KRAS-targeting molecules do not show clear benefits in patient overall survival (POS) so pharmacological modulation of aberrant tricarboxylic acid (TCA) cycle in hypoxic cancer has been proposed as a metabolic vulnerability of KRAS-driven tumors. Methods: Annexin V-FITC and cell viability assays were carried out in order to verify vitamin C citotoxicity in KRAS mutant SW480 and DLD1 as well as in Immortalized Human Colonic Epithelial Cells (HCEC). HIF1a expression and activity were determined by western blot and functional analysis assays. HIF1a direct targets GLUT1 and PDK1 expression was checked using western blot and qRT-PCR. Inmunohistochemical assays were perfomed in tumors derived from murine xenografts in order to validate previous observations in vivo. Vitamin C dependent PDH expression and activity modulation were detected by western blot and colorimetric activity assays. Acetyl-Coa levels and citrate synthase activity were assessed using colorimetric/fluorometric activity assays. Mitochondrial membrane potential (Δψ) and cell ATP levels were assayed using fluorometric and luminescent test. Results: PDK-1 in KRAS mutant CRC cells and murine xenografts was downregulated using pharmacological doses of vitamin C through the proline hydroxylation (Pro402) of the Hypoxia inducible factor-1(HIF-1)α, correlating with decreased expression of the glucose transporter 1 (GLUT-1) in both models. Vitamin C induced remarkable ATP depletion, rapid mitochondrial Δψ dissipation and diminished pyruvate dehydrogenase E1-α phosphorylation at Serine 293, then boosting PDH and citrate synthase activity. Conclusion: We report a striking and previously non reported role of vitamin C in the regulation of the pyruvate dehydrogenase (PDH) activity, then modulating the TCA cycle and mitochondrial metabolism in KRAS mutant colon cancer. Potential impact of vitamin C in the clinical management of anti-EGFR chemoresistant colorectal neoplasias should be further considered.

Holothuria scabra Extract Induces Cell Apoptosis and Suppresses Warburg Effect by Down-Regulating Akt/mTOR/HIF-1 Axis in MDA-MB-231 Breast Cancer Cells

INTRODUCTION

Cancer cells utilize the modified glucose metabolism known as Warburg effect, with lactate production as the end product. In the search for alternative therapy, the body wall of sea cucumbers contains various substances with pharmacological activities. Herein, we investigate the effect of Holothuria scabra extract on the viability and Warburg effect of aggressive breast cancer cells.

METHODS

Body wall of H. scabra was extracted using 95% ethanol. Triple-negative breast cancer cells, MDA-MB-231, were treated with the extract at various concentrations under normoglycemic and hyperglycemic conditions. Cytotoxicity test was performed using MTT assay. Apoptotic proteins were quantified using Western blot. Apoptotic cells were stained with Hoechst 33342. Lactate production was determined using L-lactate assay kit.

RESULTS

By MTT assay, H. scabra extract suppressed the viability of breast cancer cells in a dose-dependent and time-dependent manner by enhancing apoptosis, indicated by a marked increase of proapoptotic Bax and pro-caspase three expressions, and decreased expression of anti-apoptotic Bcl-2. The extract could reduce hexokinase II expression, leading to reduced lactate production by blocking the Akt/mTOR/HIF-1 axis.

DISCUSSION

Overall findings indicated that H. scabra extract could be a possible therapeutic against breast cancer progression in patients with hyperglycemia, for instance, diabetes mellitus.

New drugs are not enough‑drug repositioning in oncology: An update

Drug repositioning refers to the concept of discovering novel clinical benefits of drugs that are already known for use treating other diseases. The advantages of this are that several important drug characteristics are already established (including efficacy, pharmacokinetics, pharmacodynamics and toxicity), making the process of research for a putative drug quicker and less costly. Drug repositioning in oncology has received extensive focus. The present review summarizes the most prominent examples of drug repositioning for the treatment of cancer, taking into consideration their primary use, proposed anticancer mechanisms and current development status.

SREBP-1 inhibitor Betulin enhances the antitumor effect of Sorafenib on hepatocellular carcinoma via restricting cellular glycolytic activity

Lipid metabolism that correlates tightly to the glucose metabolic regulation in malignant cells includes hepatocellular carcinoma (HCC) cells. The transcription factor Sterol Regulatory Element Binding Protein 1 (SREBP-1), a regulator of fatty acid synthesis, has been shown to pivotally regulate the proliferation and metastasis of HCC cells. However, the intrinsic mechanism by which SREBP-1 regulates the survival of HCC cells remains unclear. In this study, among HCC patients who had dismal responses to Sorafenib, a high SREBP-1 level was found in the tumors and correlated to poor survival. This observation suggested the negative role of SREBP-1 in clinical HCC prognosis. Our mechanistical studies reveal that the inhibition of SREBP-1 via its inhibitor Betulin suppresses cellular glucose metabolism. In addition to the reduced glycolytic activity, a thwarted metastatic potential was observed in HCC cells upon Betulin administration. Moreover, our data show that SREBP-1 inhibition facilitated the antitumor effects of Sorafenib on HCC cells and xenograft tumors.