The HK2 Dependent "Warburg Effect" and Mitochondrial Oxidative Phosphorylation in Cancer: Targets for Effective Therapy with 3-Bromopyruvate

Polychlorinated biphenyl quinone exposure promotes breast cancer aerobic glycolysis: An in vitro and in vivo examination

Polychlorinated biphenyls (PCBs) were classified as group I carcinogenic to humans, as their toxicological mechanisms have been associated with cancer initiation and promotion. However, whether PCBs have effects on cancer progression are still largely veiled. Here, we for the first time discovered that a PCB quinone-type metabolite, namely PCB29-pQ, exposure significantly promoted aerobic glycolysis, a hallmark property of metabolic reprogramming in cancer progression. PCB29-pQ exposure activated corresponding glucose transporter type 1 (GLUT1)/integrin β1/Src/focal adhesion kinase (FAK) signaling pathway in breast cancer MDA-MB-231 cells. Conversely, the inhibition of GLUT1 reversed this effect, as well as the ability of migration and invasion of MDA-MB-231 cells. In addition, PCB29-pQ-induced breast cancer metastasis in 4T1-luc cell inoculated nude mice is repressed by GLUT1 inhibition. Overall, our results demonstrated a novel mechanism that PCB29-pQ exposure promotes aerobic glycolysis in both in vitro and in vivo breast cancer models in a GLUT1-dependent fashion, which may provide a strategy to prevent breast cancer cell spread.

Altered Basal Lipid Metabolism Underlies the Functional Impairment of Naive CD8+ T Cells in Elderly Humans

Aging is associated with functional deficits in the naive T cell compartment, which compromise the generation of de novo immune responses against previously unencountered Ags. The mechanisms that underlie this phenomenon have nonetheless remained unclear. We found that naive CD8+ T cells in elderly humans were prone to apoptosis and proliferated suboptimally in response to stimulation via the TCR. These abnormalities were associated with dysregulated lipid metabolism under homeostatic conditions and enhanced levels of basal activation. Importantly, reversal of the bioenergetic anomalies with lipid-altering drugs, such as rosiglitazone, almost completely restored the Ag responsiveness of naive CD8+ T cells. Interventions that favor lipid catabolism may therefore find utility as adjunctive therapies in the elderly to promote vaccine-induced immunity against targetable cancers and emerging pathogens, such as seasonal influenza viruses and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Quantitative Proteome Analysis in Response to Glucose Concentration in C2C12 Myotubes

Glucose is important for the maintenance of muscle function; however, it is still unclear how changes in glucose concentration affect muscle. Here, we analyzed the effect of glucose concentration on protein expression under different glucose concentration media in C2C12 myotubes. First, we performed proteome analysis in C2C12 myotubes cultured in Low (1.0 g/L), Medium (2.0 g/L), and High (4.5 g/L) glucose media. Proteome analysis revealed 113 proteins were significantly changed in group cultured in Low or Medium glucose media compared to group cultured in High glucose media. Furthermore, glycolysis, oxidative phosphorylation, and fatty acid metabolism were increased in the Medium and Low groups. Among these pathways, HK2, PFKP, NDUFA11, and FABP3 were especially upregulated proteins in Low and Medium groups. In this context, ATP production in C2C12 myotubes cultured in Low and Medium glucose media was increased. There was no significant change in myotubes morphology and myogenic differentiation factors in all groups. Finally, we examined the effect on glucose concentration in culture media on myosin isoforms expression by qRT-PCR. As a result, Myh2 and Myh4 were significantly increased in Low and Medium conditions. Altogether, Low and Medium glucose conditions induced Myh expression probably via enhancement glucose utilization.

Exosome-delivered circular RNA DLGAP4 induces chemoresistance via miR-143-HK2 axis in neuroblastoma

Accumulating evidence validates that aerobic glycolysis is involved in chemotherapy resistance in human malignant tumors. In the present study, we explored the role of exosome-delivered circular RNA DLGAP4 (circDLGAP4), a novel identified circRNAs, in the chemoresistance of neuroblastoma (NB) cells. Our study demonstrated that doxorubicin-resistant cells expressed higher HK2, accompanied with enhanced glycolysis. In addition, circDLGAP4 was validated to act as a sponge for the HK2-targeting miR-143. As a molecular cargo, exosomes were found to deliver circDLGAP4 from doxorubicin-resistant cells to the sensitive cells. Functionally, exosomal circDLGAP4 enhanced glycolysis and drug resistance via regulating miR-143 and HK2 in NB cells. Consistently, upregulation of HK2 induced by circDLGAP4 or miR-143 inhibitors produced the similar malignant transformation in NB cells. However, knockdown of circDLGA P4 could reversed the drug resistance in the recipient cells. In conclusion, these findings demonstrate that exosome-delivered circDLGAP4 promotes the glycolysis, proliferation, and invasion of sensitive NB cells by regulating miR-143 and HK2, providing a novel link between drug resistance and circDLGAP4/miR-143/HK2 axis in drug-resistant NB.

Immunometabolism at the service of traditional Chinese medicine

To enhance therapeutic efficacy and reduce adverse effects, ancient practitioners of traditional Chinese medicine (TCM) prescribe combinations of plant species/animal species and minerals designated "TCM formulae" developed based on TCM theory and clinical experience. TCM formulae have been shown to exert curative effects on complex diseases via immune regulation but the underlying mechanisms remain unknown at present. Considerable progress in the field of immunometabolism, referring to alterations in the intracellular metabolism of immune cells that regulate their function, has been made over the past decade. The core context of immunometabolism is regulation of the allocation of metabolic resources supporting host defense and survival, which provides a critical additional dimension and emerging insights into how the immune system and metabolism influence each other during disease progression. This review summarizes research findings on the significant association between the immune function and metabolic remodeling in health and disease as well as the therapeutic modulatory effects of TCM formulae on immunometabolism. Progressive elucidation of the immunometabolic mechanisms involved during the course of TCM treatment continues to aid in the identification of novel potential targets against pathogenicity. In this report, we have provided a comprehensive overview of the benefits of TCM based on regulation of immunometabolism that are potentially applicable for the treatment of modern diseases.

Targeting glucose metabolism to develop anticancer treatments and therapeutic patents

INTRODUCTION

One of the most distinctive hallmarks of cancer cells is increased glucose consumption for aerobic glycolysis which is named the Warburg effect. In recent decades, extensive research has been carried out to exploit this famous phenomenon, trying to detect promising targetable vulnerabilities in altered metabolism to fight cancer. Targeting aberrant glucose metabolism can perturb cancer malignant proliferation and even induce programmed cell death.

AREAS COVERED

This review covered the recent patents which focused on targeting key glycolytic enzymes including hexokinase, pyruvate dehydrogenase kinases and lactate dehydrogenase for cancer treatment.

EXPERT OPINION

Compared with the conventional cancer treatment, specifically targeting the well-known Achilles heel Warburg effect has attracted considerable attention. Although there is still no single glycolytic agent for clinical cancer treatment, the combination of glycolytic inhibitor with conventional anticancer drug or the combined use of multiple glycolytic inhibitors are being investigated extensively in recent years, which could emerge as attractive anticancer strategies.

Ru(III) Complexes with Lonidamine-Modified Ligands

A series of bifunctional Ru(III) complexes with lonidamine-modified ligands (lonidamine is a selective inhibitor of aerobic glycolysis in cancer cells) was described. Redox properties of Ru(III) complexes were characterized by cyclic voltammetry. An easy reduction suggested a perspective for these agents as their whole mechanism of action seems to be based on activation by metal atom reduction. New compounds demonstrated a more pronounced antiproliferative potency than the parental drug; individual new agents were more cytotoxic than cisplatin. Stability studies showed an increase in the stability of complexes along with the linker length. A similar trend was noted for antiproliferative activity, cellular uptake, apoptosis induction, and thioredoxin reductase inhibition. Finally, at concentrations that did not alter water solubility, the selected new complex evoked no acute toxicity in Balb/c mice.

Hsa_circ_0001806 promotes glycolysis and cell progression in hepatocellular carcinoma through miR-125b/HK2

OBJECTIVE

Hepatocellular carcinoma (HCC) is one of the most common malignant tumours and a leading cause of cancer death. Circular RNA (circRNA) has been demonstrated to play an important role in regulating tumour development. The current study aims to explore the specific role of hsa_circ_0001806 during HCC progression.

METHODS

The expression of hsa_circ_0001806 in HCC tissues and cells was measured through qRT-PCR. Cell proliferation, apoptosis and migration were measured using CCK-8 and Annexin V/PI staining kits, and Transwell assay. Bioinformatics prediction and dual-luciferase reporter assay were adopted to explore the mechanism underlying the cell function of hsa_circ_0001806 in HCC cells. In addition, glycolysis was assessed by measuring the glucose uptake, lactate production and ATP level using a glucose assay kit, fluorometric lactate assay kit and ATP detection assay kit.

RESULTS

Hsa_circ_0001806 was up-regulated in HCC tissues and cells and positively associated with the advanced TNM stage, metastasis and poor overall survival. The overexpression of hsa_circ_0001806 promoted HCC cell proliferation, migration and glycolysis and inhibited cell apoptosis, while the silence of hsa_circ_0001806 showed an opposite effect. Furthermore, hsa_circ_0001806 acted as a sponge of miR-125b to up-regulate hexokinase II (HK2) expression. In addition, the inhibition of miR-125b and HK2 overexpression partly reversed the inhibitory effect of hsa_circ_0001806 silencing on HCC cell proliferation, migration and glycolysis.

CONCLUSION

The inhibition of hsa_circ_0001806 suppressed HCC cell proliferation, migration and glycolysis through mediating miR-125b/HK2 axis.

Hexokinases II-mediated glycolysis governs susceptibility to crizotinib in ALK-positive non-small cell lung cancer

Background

Activation of ALK leads to a high level of aerobic glycolysis related to crizotinib insensitivity in anaplastic lymphoma kinase‐positive non‐small cell lung cancer (ALK⁺ NSCLC). The strategy and mechanism of glycolysis inhibition in sensitizing ALK⁺ NSCLC cells to crizotinib requires further investigation.

Methods

The levels of glycolysis in H3122 and H2228 cells were evaluated through detection of glucose consumption and lactate production. MTT assay was used to explore the effects of glycolytic inhibitors on crizotinib sensitivity, and the potential mechanism of action were detected by colony formation, Ki67 incorporation assay, transwell assay, small interfering RNA technology and western blot analysis.

Results

ALK⁺ NSCLC cells exhibited significantly higher levels of glycolysis compared to ALK⁻ NSCLC cells. Long‐term exposure to crizotinib could decrease the sensitivity of ALK⁺ NSCLC cells to crizotinib via increasing the levels of glycolysis related to hexokinases II (HK2). Crizotinib in combination with glycolysis inhibitor 2‐deoxy‐D‐glucose (2DG) synergistically inhibited proliferation, glycolysis, colony formation and invasion ability of ALK⁺ NSCLC cells. 2DG sensitization crizotinib might be associated with the inhibition of HK2‐mediated glycolysis and P‐ALK/AKT/mTOR signaling pathway in H3122 and H2228 cells.

Conclusions

These results indicate that HK2‐mediated glycolysis plays a crucial role in the increased tolerance of ALK⁺ NSCLC cells to crizotinib. 2DG may sensitize ALK⁺ NSCLC to crizotinib via suppression of HK2‐mediated glycolysis and the AKT/mTOR signaling pathway.

Dosing metric in cellular experiments: The mol/cell metric has its limitations

It has been argued that the mol/cell metric is more universal than concentration of the toxic agent since in many cases the effect of dose expressed as mol/cell is independent of ex-perimental setup. We confirmed it for hemolysis of erythrocytes in phosphate-buffered saline induced by hypochlorite where the amount of femtomoles/cell of hypochlorite needed for 50% hemolysis was independent of erythrocyte concentration. However, in the presence of blood plasma this metric became dependent on cell concentration. Similarly, the effect of 3-bromopyruvic acid (3-BP) on PEO1 cells as a function of mol/cell ratio depended on the volume of the 3-BP containing medium, due to the reaction of 3-BP with components of the medium. Hemolytic amounts of sodium dodecyl sulfate and Triton X-100 expressed as mol/cell decreased with increasing cell concentration while the effect of DMSO on the viability of a constant number of fibroblasts was independent of the volume of DMSO-containing medium. These results demonstrate that the mol/cell metric is still dependent on experimental conditions when the toxic agent interacts with components of the medium or when its physical state is modified by the target cells, and the effect is independent of the mol/per cell ratio for high excess of a cell damaging agent.

KLK6 mediates stemness and metabolism of gastric carcinoma cells via the PI3K/AKT/mTOR signaling pathway

Gastric cancer is a common tumor of the digestive system, which can occur in any part of the stomach. Kallikrein 6 (KLK6) is a trypsin-like serine protease and has been found to be involved in extracellular matrix remodeling, tumor invasion and nervous system plasticity. Our previous study reported that KLK6 suppressed HGC-27 gastric cancer cell growth by inhibiting epithelial-mesenchymal transition; however, the mechanism of action underlying the effect of KLK6 still remains unclear. The aim of the present study was to investigate the effect and the underlying mechanism of KLK6 on stem cell-like properties and metabolism in gastric carcinoma cells. The HGC-27 cell line was transfected with KLK6 overexpression (OV-KLK6) and interference (short hairpin-KLK6) vectors, then the transfection efficiency was confirmed using western blot analysis and reverse transcription-quantitative PCR. The percentage of CD133⁺ and CD44⁺ cells was detected using flow cytometry, while the protein expression levels of the stem-associated genes, Nanog, Oct-4, SOX2 and Notch1, the metabolic markers, hexokinase (HK)1, HK2, GLUT1, and the proteins within the PI3K signaling pathway, phosphorylated (p)-PI3K, p-AKT and p-mTOR, were determined using western blot analysis. Biochemical kits were used to measure ATP production, lactic acid content and glucose uptake. A tumorigenicity assay was performed with nude mice to detect gastric tumor volume, and the protein expression level of Oct-4, Nanog, HK1, HK2 and GLUT1, and the mRNA expression level of KLK6 was also determined in gastric tumor tissues of mice. Compared with that in the control group, KLK6 protein and mRNA expression levels were significantly decreased in the four sh-RNA groups (P<0.05). Among them, sh-RNA-3 induced the lowest KLK6 expression and was used to silence KLK6 in subsequent experiments. Compared with that in the control and negative control groups, the percentage of CD133⁺ and CD44⁺ cells, the protein expression level of Oct-4, Nanog, HK1, HK2, GLUT1, p-PI3K, p-AKT and p-mTOR, and ATP content, lactic acid production, glucose uptake and gastric tumor volume were significantly decreased by sh-KLK6 (P<0.05), whereas KLK6 overexpression induced the opposite effect (P<0.05). In conclusion, KLK6 modulated stemness properties and cell metabolic profile in gastric carcinoma cells and the mechanism may be associated with the PI3K/AKT/mTOR signaling pathway.

IL13Rα1 prevents a castration resistant phenotype of prostate cancer by targeting hexokinase 2 for ubiquitin-mediated degradation

OBJECTIVE

Androgen deprivation therapy (ADT) is still the principal treatment option for prostate cancer (PCa). In addition to reactivation of androgen receptor signaling, the resistance of PCa to apoptosis during ADT also contributes to castration resistant PCa (CRPC). A previous study reported that gene transfer of IL-13Rα2 into PCa cells sensitized the cells to the IL-13R-targeted cytotoxin IL13Rα1, leading to apoptosis. Compared with IL-13Rα2, IL13Rα1 is more constitutively expressed in PCa cells, but its function in PCa remains to be established.

METHODS

We determined the role and expression of IL13Rα1 in PCa cancer cells using western blotting, flow cytometry, and cell proliferation assays. Co-immunoprecipitation and mass spectrometry were used to identify the proteins that interacted with IL13Rα1, to elucidate its function.

RESULTS

In this study, we showed that IL13Rα1 was selectively suppressed in androgen-deprived PCa cells and that its suppression tended to be associated with poor prognoses of PCa patients. IL13Rα1 overexpression promoted apoptosis and inhibited tumor growth under androgen-deprived or castrated conditions (P < 0.01). Mechanistically, IL13Rα1 recruited and facilitated ubiquitin protein ligase E3C-mediated ubiquitination and degradation of hexokinase 2 (HK2), resulting in glycolytic inhibition and eventually leading to PCa cell apoptosis. Furthermore, our data revealed that mutated ataxia-telangiectasia kinase phosphorylated and facilitated the selective ubiquitin proteasome-mediated degradation of HK2. Notably, IL13Rα1-overexpressing PCa cells were more susceptible to apoptosis and exhibited reduced tumor growth after exposure to the HK2 inhibitor, 2-deoxy-D-glucose (P < 0.01).

CONCLUSIONS

Our data identified a tumor suppressor role for IL13Rα1 in preventing the resistance of PCa cells to apoptosis during androgen deprivation by inhibiting glycolysis. IL13Rα1-mediated signaling involving HK2 may therefore provide a novel treatment target and strategy for CRPC.

Quantitative proteomics analysis reveals novel insights into mechanisms of action of disulfiram (DSF)

PURPOSE

Disulfiram (DSF) has been proven safe and shows the promising antitumor effect in preclinical studies. However, the precise mechanism of DSF on tumor is rarely reported. This study aims to fully understand the mechanism of action of DSF with a systems perspective in anticancer effects.

EXPERIMENTAL DESIGN

SILAC-based quantitative proteomics strategy was used to systematically identify differential expression proteins (DEPs) after DSF treatment in HeLa cells. Bioinformatical analysis (PANTHER, DAVID, and STRING) were performed to characterize biological functions of DEPs. Functional studies were performed to explore underlying mechanisms of DSF in cancer cells.

RESULTS

In total, 201 proteins were dysregulated significantly after DSF exposure. Functional studies of hexokinase 2 (HK2), which catalyzed the first irreversible enzymatic step in glucose metabolism, revealed that various phenotypic effects observed after DSF treatment in cancer cells, at least partly, through the regulation of HK2 expression.

CONCLUSIONS AND CLINICAL RELEVANCE

By correlating the proteomics data with these functional studies, the current results provided novel insights into the mechanism underlying DSF function in cancer cells. Meanwhile, these provided theoretical basis for the new use of old drugs in clinical therapy.

Clinical Targeting of Altered Metabolism in High-Grade Glioma

ABSTRACT

High-grade gliomas are among the deadliest of all cancers despite standard treatments, and new therapeutic strategies are needed to improve patient outcome. Targeting the altered metabolic state of tumors with traditional chemotherapeutic agents has a history of success, and our increased understanding of cellular metabolism in the past 2 decades has reinvigorated the concept of novel metabolic therapies in brain tumors. Here we highlight metabolic alterations in advanced gliomas and their translation into clinical trials using both novel agents and already established drugs repurposed for cancer treatment in an effort to improve outcome for these deadly diseases.

Methylation-associated silencing of miR-9-1 promotes nasopharyngeal carcinoma progression and glycolysis via HK2

Characteristically, cancer cells metabolize glucose through aerobic glycolysis, known as the Warburg effect. Accumulating evidence suggest that during cancer formation, microRNAs (miRNAs) could regulate such metabolic reprogramming. In the present study, miR‐9‐1 was identified as significantly hypermethylated in nasopharyngeal carcinoma (NPC) cell lines and clinical tissues. Ectopic expression of miR‐9‐1 inhibited NPC cell growth and glycolytic metabolism, including reduced glycolysis, by reducing lactate production, glucose uptake, cellular glucose‐6‐phosphate levels, and ATP generation in vitro and tumor proliferation in vivo. HK2 (encoding hexokinase 2) was identified as a direct target of miR‐9‐1 using luciferase reporter assays and Western blotting. In NPC cells, hypermethylation regulates miR‐9‐1 expression and inhibits HK2 translation by directly targeting its 3' untranslated region. MiR‐9‐1 overexpression markedly reduced HK2 protein levels. Restoration of HK2 expression attenuated the inhibitory effect of miR‐9‐1 on NPC cell proliferation and glycolysis. Fluorescence in situ hybridization results indicated that miR‐9‐1 expression was an independent prognostic factor in NPC. Our findings revealed the role of the miR‐9‐1/HK2 axis in the metabolic reprogramming of NPC, providing a potential therapeutic strategy for NPC.

Targeting hexokinase 2 increases the sensitivity of oxaliplatin by Twist1 in colorectal cancer

Colorectal cancer (CRC) is the third most malignant tumour worldwide, with high mortality and recurrence. Chemoresistance is one of the main factors leading to metastasis and poor prognosis in advanced CRC patients. By analysing the Gene Expression Omnibus data set, we found higher hexokinase 2 (HK2) expression levels in patients with metastatic CRC than in those with primary CRC. Moreover, we observed higher enrichment in oxaliplatin resistance‐related gene sets in metastatic CRC than in primary CRC. However, the underlying relationship has not yet been elucidated. In our study, HK2 expression was significantly elevated in CRC patients. Gene set enrichment analysis (GSEA) revealed multi‐drug resistance and epithelial‐mesenchymal transition (EMT) pathways related to high HK2 expression. Our results showed that knockdown of HK2 significantly inhibited vimentin and Twist1 expression and promoted TJP1 and E‐cadherin expression in CRC cells. Additionally, transcriptional and enzymatic inhibition of HK2 by 3‐bromopyruvate (3‐bp) impaired oxaliplatin resistance in vitro and in vivo. Mechanistically, HK2 interacts with and stabilized Twist1 by preventing its ubiquitin‐mediated degradation, which is related to oxaliplatin resistance, in CRC cells. Overexpression of Twist1 reduced the apoptosis rate by HK2 knockdown in CRC cells. Collectively, we discovered that HK2 is a crucial regulator that mediates oxaliplatin resistance through Twist1. These findings identify HK2 and Twist1 as promising drug targets for CRC chemoresistance.

Metabolic Strategies for Inhibiting Cancer Development

The tumor microenvironment is a complex mix of cancerous and noncancerous cells (especially immune cells and fibroblasts) with distinct metabolisms. These cells interact with each other and are influenced by the metabolic disorders of the host. In this review, we discuss how metabolic pathways that sustain biosynthesis in cancer cells could be targeted to increase the effectiveness of cancer therapies by limiting the nutrient uptake of the cell, inactivating metabolic enzymes (key regulatory ones or those linked to cell cycle progression), and inhibiting ATP production to induce cell death. Furthermore, we describe how the microenvironment could be targeted to activate the immune response by redirecting nutrients toward cytotoxic immune cells or inhibiting the release of waste products by cancer cells that stimulate immunosuppressive cells. We also examine metabolic disorders in the host that could be targeted to inhibit cancer development. To create future personalized therapies for targeting each cancer tumor, novel techniques must be developed, such as new tracers for positron emission tomography/computed tomography scan and immunohistochemical markers to characterize the metabolic phenotype of cancer cells and their microenvironment. Pending personalized strategies that specifically target all metabolic components of cancer development in a patient, simple metabolic interventions could be tested in clinical trials in combination with standard cancer therapies, such as short cycles of fasting or the administration of sodium citrate or weakly toxic compounds (such as curcumin, metformin, lipoic acid) that target autophagy and biosynthetic or signaling pathways.

Indispensable Role of HIF-1α Signaling in Post-implantation Survival and Angio-/Vasculogenic Properties of SHED

Objectives

Post-implantation survival and timely vascularization of stem-cell based constructs are critical factors in achieving successful outcomes in tissue regeneration approaches. Hypoxia inducible factor-1α (HIF-1α) is known to mediate adaptive functions to ischemic stress in many different cell types. The current study aimed to explore the role of HIF-1α in post-implantation survival and angio-/vasculogenesis of stem cells from human exfoliated deciduous teeth (SHED).

Methods

HIF-1α in SHED was suppressed using siRNA or chemical inhibitor (YC-1) and used in Matrigel plug assay conducted on severe combined immunodeficient mice. The plugs were retrieved on day 3 or 7 post-injection and analyzed for hypoxia status, ki67 expression, DNA fragmentation (TUNEL), cellularity, and vascularization by histology and immunohistochemistry for CD31, HIF-1α, pyruvate dehydrogenase kinase-1 (PDK1), hexokinase 2 (HK2), and glucose transporter 1 (Glut1). Cell viability of HIF-1α silenced SHED under different stress conditions (hypoxia, H₂O₂, and low glucose) in vitro was measured by CCK-8 assay. CM-H₂DCFDA and MitoSOX Red were used to detect cellular and mitochondrial reactive oxygen species (ROS) levels, respectively. PDK1, HK2, and Glut1 expression were measured by western blotting and immunofluorescence. Secretory protein levels of vascular endothelial growth factor (VEGF) and the respective paracrine effects on endothelial cell proliferation and migration were detected by ELISA, CCK-8 assay, and trans-well assay, respectively.

Results

Histological analysis of Matrigel plugs showed significantly reduced cell survival in HIF-1α silenced or chemically inhibited SHED groups, which could be attributed to diminished metabolic adaptations as shown by decreased PDK1, HK2, and Glut1 expression. HIF-1α inhibition in SHED also resulted in significantly low blood vessel formation as observed by a low number of perfused and non-perfused vessels of human or mouse CD31 origin. The viability of HIF-1α silenced SHED was significantly affected under hypoxia, H₂O₂, and low-glucose conditions in vitro, which was reflected in increased cytoplasmic and mitochondrial ROS levels. Significantly reduced levels of VEGF in HIF-1α silenced SHED resulted in decreased paracrine angiogenic effects as shown by low proliferation and migration of endothelial cells.

Conclusion

HIF-1α plays an indispensable role in post-implantation survival and angio-/vasculogenic properties of SHED by maintaining ROS homeostasis, inducing metabolic adaptations, and VEGF secretion.

Silencing of circHIPK3 Sensitizes Paclitaxel-Resistant Breast Cancer Cells to Chemotherapy by Regulating HK2 Through Targeting miR-1286

Background

Resistance development to paclitaxel (PTX) has become a major obstacle in the successful treatment of breast cancer (BC). Circular RNAs (circRNAs) have been identified as essential regulators in PTX resistance of BC. Here, we explored the precise roles of circRNA homeodomain interacting protein kinase 3 (circHIPK3, circ_0000284) in PTX resistance of BC.

Methods

The expression levels of circHIPK3, microRNA (miR)-1286, and hexokinase 2 (HK2) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot. Ribonuclease R (RNase R) assay was used to confirm the stability of circHIPK3. Cellular localization of circHIPK3 was assessed by subcellular localization assay. The half maximal inhibitory concentration (IC₅₀) value for PTX was measured by Cell Counting Kit-8 (CCK-8) assay. Cell colony formation, cell cycle distribution, and apoptosis were gauged by colony formation assay and flow cytometry, respectively. Animal studies were performed to evaluate the role of circHIPK3 in vivo. The direct relationship between miR-1286 and circHIPK3 or HK2 was verified by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays.

Results

Our results showed that circHIPK3 was up-regulated in PTX-resistant BC tissues and cells compared with the sensitive counterparts. The silencing of circHIPK3 promoted PTX sensitivity of PTX-resistant BC cells in vitro and in vivo. CircHIPK3 directly targeted miR-1286, and miR-1286 acted as a downstream mediator of circHIPK3 function in vitro. HK2 was a direct target of miR-1286, and circHIPK3 modulated HK2 expression through miR-1286. The increased expression of miR-1286 sensitized PTX-resistant BC cells to PTX in vitro by down-regulating HK2.

Conclusion

Our findings demonstrated that the silencing of circHIPK3 sensitized PTX-resistant BC cells to PTX therapy at least in part via the regulation of the miR-1286/HK2 axis.

SLC45A4 promotes glycolysis and prevents AMPK/ULK1-induced autophagy in TP53 mutant pancreatic ductal adenocarcinoma

Background

Somatic mutations of the TP53 gene occur frequently in pancreatic ductal adenocarcinoma (PDA). Solute carrier family 45 member A4 (SLC45A4) is a H⁺‐dependent sugar cotransporter. The role of SLC45A4 in PDA, especially in TP53 mutant PDA, remains poorly understood.

Methods

We explored the TCGA datasets to identify oncogenes in TP53 mutant PDA. MTS [3‐(4,5‐dimethylthiazol‐2‐yl)‐5‐(3‐carboxymethoxyphenyl)‐2‐(4‐sulfophenyl)‐2H‐tetrazolium], colony formation and 5‐ethynyl‐2′‐deoxyuridine (Edu) assays were performed to investigate the function of SLC45A4 in vitro. Glucose consumption, lactate production and ATP production were detected to evaluate glucose utilization. Extracellular acidification rate and oxygen consumption rate assays were used to evaluate glycolysis and oxidative phosphorylation. The subcutaneous xenotransplantation models were conducted to explore the function of SLC45A4 in vivo. RNA‐sequencing and gene set enrichment analysis were employed to explore the biological alteration caused by SLC45A4 knockdown. Western blotting was performed to evaluate the activation of glycolysis, as well as the AMPK pathway and autophagy.

Results

SLC45A4 was overexpressed in PDA for which the expression was significantly higher in TP53 mutant PDA than that in wild‐type PDA tissues. Moreover, high level of SLC45A4 expression was tightly associated with poor clinical outcomes in PDA patients. Silencing SLC45A4 inhibited proliferation in TP53 mutant PDA cells. Knockdown of SLC45A4 reduced glucose uptake and ATP production, which led to activation of autophagy via AMPK/ULK1 pathway. Deleting SLC45A4 in TP53 mutant HPAF‐II cells inhibited the growth of xenografts in nude mice.

Conclusions

The present study found that SLC45A4 prevents autophagy via AMPK/ULK1 axis in TP53 mutant PDA, which may be a promising biomarker and therapeutic target in TP53 mutant PDA.

Tissue-Specific Warburg Effect in Breast Cancer and Cancer-Associated Adipose Tissue-Relationship between AMPK and Glycolysis

Simple Summary

Specific metabolic phenotypes of breast cancer result from local interactions such as cancer-adipocyte cross-talk and systemic metabolic influences such as obesity. Here we examined key regulatory enzymes involved in glucose metabolism in breast cancer tissue and cancer-associated adipose tissue of normal-weight and overweight/obese premenopausal women in comparison to benign breast tumor tissue and adipose tissue of weight-matched women. We show a simultaneous increase in 5′-AMP-activated protein kinase (AMPK) protein expression with glucose utilization favoring glycolysis and pentose phosphate pathway in breast cancer tissue. In parallel, we show an increased AMPK protein expression with glucose utilization favoring the pentose phosphate pathway in cancer-associated adipose tissue. Moreover, specific features of cancer tissue glycolysis and glycogen metabolism differ between normal-weight and overweight/obese women. The results suggest context-dependent induction of tissue-specific Warburg effect in breast cancer and cancer-associated adipose tissue.

Abstract

Typical features of the breast malignant phenotype rely on metabolic reprogramming of cancer cells and their interaction with surrounding adipocytes. Obesity is strongly associated with breast cancer mortality, yet the effects of obesity on metabolic reprogramming of cancer and cancer-associated adipose tissue remain largely unknown. Paired biopsies of breast tumor tissue and adipose tissue from premenopausal women were divided according to pathohistological analyses and body mass index on normal-weight and overweight/obese with benign or malignant tumors. We investigated the protein expression of key regulatory enzymes of glycolysis, pentose phosphate pathway (PPP), and glycogen synthesis. Breast cancer tissue showed a simultaneous increase in 5′-AMP-activated protein kinase (AMPK) protein expression with typical features of the Warburg effect, including hexokinase 2 (HK 2) overexpression and its association with mitochondrial voltage-dependent anion-selective channel protein 1, associated with an overexpression of rate-limiting enzymes of glycolysis (phosphofructokinase 1—PFK-1) and pentose phosphate pathway (glucose-6-phosphate dehydrogenase—G6PDH). In parallel, cancer-associated adipose tissue showed increased AMPK protein expression with overexpression of HK 2 and G6PDH in line with increased PPP activity. Moreover, important obesity-associated differences in glucose metabolism were observed in breast cancer tissue showing prominent glycogen deposition and higher glycogen synthase kinase-3 protein expression in normal-weight women and higher PFK-1 and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) protein expression in overweight/obese women. In conclusion, metabolic reprogramming of glycolysis contributes to tissue-specific Warburg effect in breast cancer and cancer-associated adipose tissue.

Exploiting the metabolic energy demands of drug efflux pumps provides a strategy to overcome multidrug resistance in cancer

BACKGROUND

P-glycoprotein (P-gp) is a prevalent resistance mediator and it requires considerable cellular energy to ensure ATP dependent efflux of anticancer drugs. The glycolytic pathway generates the majority of catabolic energy in cancer cells; however, the high rates of P-gp activity places added strain on its inherently limited capacity to generate ATP. This is particularly relevant for compounds such as verapamil that are believed to trap P-gp in a futile transport process that requires continuing ATP consumption. Ultimately, this leads to cell death and the hypersensitivity of resistant cells to verapamil is termed collateral sensitivity.

RESULTS

We show that the addition of verapamil to resistant cells produces a prominent reduction in ATP levels that supports the idea of disrupted energy homeostasis. Even in the absence of verapamil, P-gp expressing cells display near maximal rates of glycolysis and oxidative phosphorylation, which prevents an adequate response to the demand for ATP to sustain transport activity. Moreover, the near perpetually maximal rate of oxidative phosphorylation in the presence of verapamil resulted in elevated levels of reactive oxygen species that affect cell survival and underscore collateral sensitivity.

CONCLUSIONS

Our results demonstrate that the strained metabolic profiles of P-gp expressing resistant cancer cells can be overwhelmed by additional ATP demands.

GENERAL SIGNIFICANCE

Consequently, collateral sensitising drugs may overcome the resistant phenotype by exploiting, rather than inhibiting, the energy demanding activity of pumps such as P-gp.

Streptococcus thermophilus Inhibits Colorectal Tumorigenesis Through Secreting β-Galactosidase

BACKGROUND & AIMS

Streptococcus thermophilus was identified to be depleted in patients with colorectal cancer (CRC) by shotgun metagenomic sequencing of 526 multicohort fecal samples. Here, we aim to investigate whether this bacterium could act as a prophylactic for CRC prevention.

METHODS

The antitumor effects of S thermophilus were assessed in cultured colonic epithelial cells and in 2 murine models of intestinal tumorigenesis. The tumor-suppressive protein produced by S thermophilus was identified by mass spectrometry and followed by β-galactosidase activity assay. The mutant strain of S thermophilus was constructed by homologous recombination. The effect of S thermophilus on the gut microbiota composition was assessed by shotgun metagenomic sequencing.

RESULTS

Oral gavage of S thermophilus significantly reduced tumor formation in both Apc^min/+ and azoxymethane-injected mice. Coincubation with S thermophilus or its conditioned medium decreased the proliferation of cultured CRC cells. β-Galactosidase was identified as the critical protein produced by S thermophilus by mass spectrometry screening and β-galactosidase activity assay. β-Galactosidase secreted by S thermophilus inhibited cell proliferation, lowered colony formation, induced cell cycle arrest, and promoted apoptosis of cultured CRC cells and retarded the growth of CRC xenograft. The mutant S thermophilus without functional β-galactosidase lost its tumor-suppressive effect. Also, S thermophilus increased the gut abundance of known probiotics, including Bifidobacterium and Lactobacillus via β-galactosidase. β-Galactosidase-dependent production of galactose interfered with energy homeostasis to activate oxidative phosphorylation and downregulate the Hippo pathway kinases, which partially mediated the anticancer effects of S thermophilus.

CONCLUSION

S thermophilus is a novel prophylactic for CRC prevention in mice. The tumor-suppressive effect of S thermophilus is mediated at least by the secretion of β-galactosidase.

Prognostic value of glycolysis markers in head and neck squamous cell carcinoma: a meta-analysis

Glycolysis markers including glucose transporter 1 (GLUT1), monocarboxylate transporter 4 (MCT4), hexokinase 2 (HK2), pyruvate kinase M2 (PKM2) and glucose transporter 4 (GLUT4) play vital roles in head and neck squamous cell carcinoma (HNSCC). However, their prognostic value in HNSCC is still controversial. In this meta-analysis, we searched the PubMed, Web of Science and Cochrane Library databases and included thirty-seven studies (3272 patients) that met the inclusion criteria. Higher expression levels of the glycolysis markers in tumor tissues correlated with poorer overall survival (OS; P < 0.001), disease-free survival (DFS; P = 0.03) and recurrence-free survival (RFS; P < 0.001) of HNSCC patients. Subgroup and sensitivity analyses demonstrated that higher expression levels of GLUT1 (P < 0.001), MCT4 (P = 0.002), HK2 (P = 0.002) and PKM2 (P < 0.001) correlated with poorer OS among HNSCC patients. Higher expression of MCT4 (P < 0.001) and PKM2 (P = 0.008) predicted poorer DFS among HNSCC patients. However, GLUT4 expression levels did not associate with clinical outcomes in HNSCC patients. These results demonstrate that glycolysis markers, such as GLUT1, MCT4, HK2 and PKM2, are potential prognostic predictors and therapeutic targets in HNSCC.

Investigation of glucose catabolism in hypoxic Mcf 7 breast cancer culture

Hypoxia plays an important role in tumor phenotype and progression and alters glycolysis, with changes in signaling pathways that develop in response to hypoxia. In this study, the effects of oxygen (normoxia/hypoxia) and of glucose levels on the glucose metabolism was investigated in MCF-7 cancer cells. Under either normoxia or hypoxia conditions, the cells were exposed to glucose at different concentrations (0, 5.5, 15 or 55 mM) for either 3, 6, 12, 24 or 48 h. In all groups, cell viability, levels of key enzymes reflecting glycolytic metabolism in cell lysates, glucose consumed in the medium and extracellular lactate levels and wound closure percentages were determined. In hypoxic cells, intracellular consumption of glucose, and extracellular lactate levels due to increased glucose concentration were observed to be higher (compared to normoxia) and as a result of prolonged exposure to hypoxia, cells were observed to develop resistance to the prolonged exposure to hypoxia. The number of glycolytic enzymes obtained at different levels proved that cells had different potential capacities and changing mechanisms for the metabolic needs of the cell depending on the glucose amount in the medium and time in adapting to the oxygen tension. This study showed that there was an important interaction between hypoxia and glucose metabolism in general, and it was concluded that metabolic processes activated by hypoxia could offer new therapeutic targets.

Mitochondrial miR-181a-5p promotes glucose metabolism reprogramming in liver cancer by regulating the electron transport chain

Liver cancer and other malignant tumor cells rely on the glycolytic pathway to obtain energy (i.e. the Warburg effect); however, the underlying mechanism is unclear. Mitochondria are sites of oxidative phosphorylation and adenosine triphosphate (ATP) production. The 13 constituent respiratory chain proteins encoded by the mitochondrial genome (namely, mtDNA) play essential roles. We found that in human hepatocellular carcinoma (HCC) tissues, 11 out of the 13 mtDNA-encoded genes exhibited decreased mRNA levels and 5 genes displayed decreased protein levels, including the cytochrome B (mt-CYB) and cytochrome C oxidase II (mt-CO2) genes. Mitochondrial gene sequencing revealed abnormalities in the levels of a large number of mitochondrial miRNAs (mitomiRs). MicroRNA-181a-5p (mir-181a-5p), which potentially targets genes encoding mt-CYB and mt-CO2 protein, was screened out from 549 downregulated mitomiRs via bioinformatic analysis. After overexpression of mitomiR-181a-5p, mt-CYB and mt-CO2 levels were reduced in HCC cells, and the mitochondrial membrane potential (MMP) maintained by the electron transport chain (ETC) was decreased. Furthermore, the expression of hexokinase 2 (HK2) and glucose transporter type 1 (GLUT1) was upregulated, accompanied by elevated glucose, lactic acid release, and activity of lactate dehydrogenase (LDH). In vivo experiments confirmed that constitutive mitomiR-181a-5p expression caused reprogramming of glucose metabolism and promoted tumor growth and early lung metastasis in liver cancer. In summary, the present study reveals the important role of mitomiRs in glucose metabolism reprogramming in liver cancer, which is of considerable value in exploring new therapeutic targets for HCC.

Metabolic Reprogramming Induces Immune Cell Dysfunction in the Tumor Microenvironment of Multiple Myeloma

Tumor cells rewire metabolism to meet their increased nutritional demands, allowing the maintenance of tumor survival, proliferation, and expansion. Enhancement of glycolysis and glutaminolysis is identified in most, if not all cancers, including multiple myeloma (MM), which interacts with a hypoxic, acidic, and nutritionally deficient tumor microenvironment (TME). In this review, we discuss the metabolic changes including generation, depletion or accumulation of metabolites and signaling pathways, as well as their relationship with the TME in MM cells. Moreover, we describe the crosstalk among metabolism, TME, and changing function of immune cells during cancer progression. The overlapping metabolic phenotype between MM and immune cells is discussed. In this sense, targeting metabolism of MM cells is a promising therapeutic approach. We propose that it is important to define the metabolic signatures that may regulate the function of immune cells in TME in order to improve the response to immunotherapy.

Delphinidin Increases the Sensitivity of Ovarian Cancer Cell Lines to 3-Bromopyruvate

3-Bromopyruvic acid (3-BP) is a promising anticancer compound. Two ovary cancer (OC) cell lines, PEO1 and SKOV3, showed relatively high sensitivity to 3-BP (half maximal inhibitory concentration (IC₅₀) of 18.7 and 40.5 µM, respectively). However, the further sensitization of OC cells to 3-BP would be desirable. Delphinidin (D) has been reported to be cytotoxic for cancer cell lines. We found that D was the most toxic for PEO1 and SKOV3 cells from among several flavonoids tested. The combined action of 3-BP and D was mostly synergistic in PEO1 cells and mostly weakly antagonistic in SKOV3 cells. The viability of MRC-5 fibroblasts was not affected by both compounds at concentrations of up to 100 µM. The combined action of 3-BP and D decreased the level of ATP and of dihydroethidium (DHE)-detectable reactive oxygen species (ROS), cellular mobility and cell staining with phalloidin and Mitotracker Red in both cell lines but increased the 2’,7’-dichlorofluorescein (DCFDA)-detectable ROS level and decreased the mitochondrial membrane potential and mitochondrial mass only in PEO1 cells. The glutathione level was increased by 3-BP+D only in SKOV3 cells. These differences may contribute to the lower sensitivity of SKOV3 cells to 3-BP+D. Our results point to the possibility of sensitization of at least some OC cells to 3-BP by D.

VEGFR2 inhibition hampers breast cancer cell proliferation via enhanced mitochondrial biogenesis

Objective:

Vascular endothelial growth factor (VEGF), apart from its predominant roles in angiogenesis, can enhance cancer cell proliferation, but its mechanisms remain elusive. The purpose of the present study was therefore to identify how VEGF regulates cancer cell proliferation.

Methods:

VEGF effects on cancer cell proliferation were investigated with the VEGF receptor 2 inhibitor, Ki8751, and the breast cancer cell lines, MCF-7 and MDA-MB-231, using flow cytometry, mass spectrometry, immunoblotting, and confocal microscopy. Data were analyzed using one-way analysis of variance followed by Tukey’s multiple comparison test.

Results:

VEGF blockade by Ki8751 significantly reduced cancer cell proliferation, and enhanced breast cancer cell apoptosis. Mass spectrometric analyses revealed that Ki8751 treatment significantly upregulated the expression of mitochondrial proteins, suggesting the involvement of mitochondrial biogenesis. Confocal microscopy and flow cytometric analyses showed that Ki8751 treatment robustly increased the mitochondrial masses of both cancer cells, induced endomitosis, and arrested cancer cells in the high aneuploid phase. VEGFR2 knockdown by shRNAs showed similar effects to those of Ki8751, confirming the specificity of Ki8751 treatment. Enhanced mitochondrial biogenesis increased mitochondrial oxidative phosphorylation and stimulated reactive oxygen species (ROS) production, which induced cancer cell apoptosis. Furthermore, Ki8751 treatment downregulated the phosphorylation of Akt and PGC1α, and translocated PGC1α into the nucleus. The PGC1α alterations increased mitochondrial transcription factor A (TFAM) expression and subsequently increased mitochondrial biogenesis.

Conclusions:

VEGF enhances cancer cell proliferation by decreasing Akt-PGC1α-TFAM signaling-mediated mitochondrial biogenesis, ROS production, and cell apoptosis. These findings suggested the anticancer potential of Ki8751 via increased mitochondrial biogenesis and ROS production.

The efficacy of the anticancer 3-bromopyruvate is potentiated by antimycin and menadione by unbalancing mitochondrial ROS production and disposal in U118 glioblastoma cells

Metabolic reprogramming of tumour cells sustains cancer progression. Similar to other cancer cells, glioblastoma cells exhibit an increased glycolytic flow, which encourages the use of antiglycolytics as an effective complementary therapy. We used the antiglycolytic 3-bromopyruvate (3BP) as a metabolic modifier to treat U118 glioblastoma cells and investigated the toxic effects and the conditions to increase drug effectiveness at the lowest concentration. Cellular vitality was not affected by 3BP concentrations lower than 40 μM, although p-Akt dephosphorylation, p53 degradation, and ATP reduction occurred already at 30 μM 3BP. ROS generated in mitochondria were enhanced at 30 μM 3BP, possibly by unbalancing their generation and their disposal because of glutathione peroxidase inhibition. ROS triggered JNK and ERK phosphorylation, and cyt c release outside mitochondria, not accompanied by caspases-9 and -3 activation, probably due to 3BP-dependent alkylation of cysteine residues at caspase-9 catalytic site. To explore the possibility of sensitizing cells to 3BP treatment, we exploited 3BP effects on mitochondria by using 30 μM 3BP in association with antimycin A or menadione concentrations that in themselves exhibit poor toxicity. 3BP effect on cyt c release and cell vitality loss was potentiated due the greater oxidative stress induced by antimycin or menadione association with 3BP, supporting a preeminent role of mitochondrial ROS in 3BP toxicity. Indeed, the scavenger of mitochondrial superoxide MitoTEMPO counteracted 3BP-induced cyt c release and weakened the potentiating effect of 3BP/antimycin association. In conclusion, the biochemical mechanisms leading U118 glioblastoma cells to viability loss following 3BP treatment rely on mitochondrial ROS-dependent pathways. Their potentiation at low 3BP concentrations is consistent with the goal to minimize the toxic effect of the drug towards non-cancer cells.

CircCDKN2B-AS1 interacts with IMP3 to stabilize hexokinase 2 mRNA and facilitate cervical squamous cell carcinoma aerobic glycolysis progression

Background

Circular RNAs (circRNAs) have been reported to play key roles in the development of various cancers. However, the biological functions and clinical significance of most circRNAs are still elusive. The purpose of this study was to explore the function and mechanism of a certain circRNA named circCDKN2B-AS1 in cervical cancer development and its potential value in the clinic.

Methods

qRT-PCR was used to verify the expression level of circCDKN2B-AS1. CCK-8, Transwell, and flow cytometry (FCM) assays were performed to detect cellular proliferation, migration, and apoptosis, respectively. A Seahorse XFe96 Analyzer was used to measure glycolysis metabolism level. RNA pull-down, RNA immunoprecipitation (RIP), actinomycin-D addition assays and Western blotting were used to screen and elucidate the potential mechanisms involved. BALB/c nude mice and zebrafish embryos (AB, WT) were used as animal models to investigate tumorigenesis capability. ¹⁸FDG-microPET/CT imaging and lactic acid (LA) and pyruvic acid (PA) content detection assays were used to detect the level of glucose metabolism in subcutaneous tumors from nude mice.

Results

CircCDKN2B-AS1, a circular isoform of the long noncoding RNA (lncRNA) CDKN2B-AS1, was upregulated in cervical cancer and precancerous tissues. We found that circCDKN2B-AS1 associated with the IMP3 protein depending on a specific binding site and regulated the stability of Hexokinase 2 (HK2) mRNA, the rate-limiting enzyme of the aerobic glycolysis pathway. The expression level of circCDKN2B-AS1 fated the binding of IMP3 to the 3′ untranslated region (UTR) of HK2 mRNA, consequently affecting the malignant cell phenotype and aerobic glycolysis in cervical cancer in vitro and in vivo. Mutant circCDKN2B-AS1, lacking the IMP3 binding site, did not have such effects. Utilization of an inhibitory peptide to block the interaction between circCDKN2B-AS1 and the IMP3 protein impeded the binding of IMP3 to the 3’UTR of HK2 mRNA and suppressed aerobic glycolysis in cervical cancer cells.

Conclusions

Our findings demonstrate that circCDKN2B-AS1 facilitates aerobic glycolysis by sponging the IMP3 protein to stabilize HK2 mRNA, consequently promoting the malignant phenotype in cervical cancer, which may provide a potential approach for cervical cancer therapeutics.

Profiling Analysis Reveals the Crucial Role of the Endogenous Peptides in Bladder Cancer Progression

Background

Peptide drugs provide promising regimes in bladder cancer. In order to identify potential bioactive peptides involved in bladder cancer, we performed the present study.

Methods

Liquid chromatography/mass spectrometry assay was used to compare the endogenous peptides between bladder cancer and normal control. The potential biological functions of these dysregulated peptides are assessed by GO analysis and KEGG pathway analysis of their precursors. The SMART and UniProt databases are used to identify the sequences of the dysregulated peptides located in the functional domains. The Open Targets Platform database was used to investigate the precursors related to metabolic diseases.

Results

A total of 9 up-regulated peptides and 110 down-regulated peptides in bladder cancer compared with normal control were identified (fold change > 1.2, P < 0.05). The MW of these dysregulated peptides ranged from 500 Da to 2500 Da and the MW of all identified peptides was below 3500 Da. The GO and KEGG pathway analysis indicated that these dysregulated peptides could play an important role in bladder cancer. Our further analysis revealed that ⁴⁵HFNPRFNAHGDAN ⁵⁷ derived from LGALS1 and those peptides derived from P4HB and SERPINA1 might be the promising diagnostic biomarkers and therapeutic targets of bladder cancer.

Conclusion

In the present study, we have identified the profile of the peptides significantly dysregulated in bladder cancer. Moreover, using bioinformatic analysis, we found the peptides derived from LGALS1, P4HB and SERPINA1 could be the promising diagnostic biomarkers and therapeutic targets of bladder cancer.

Knockdown of circ-TTBK2 Inhibits Glioma Progression by Regulating miR-1283 and CHD1

Background

Dysregulated circular RNAs (circRNAs) are involved in the development of glioma. This paper aims to analyze the role and mechanism of circRNA tau tubulin kinase 2 (circ-TTBK2) in glioma progression.

Methods

The glioma samples and normal brain tissues were collected. The levels of circ-TTBK2, microRNA-1283 (miR-1283) and chromodomain helicase DNA-binding protein 1 (CHD1) were examined via quantitative reverse transcription polymerase chain reaction or Western blot. Cell proliferation, migration, invasion and glycolysis were determined via 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide, transwell assay, Western blot, glucose and lactate assay kits. The target relationship was analyzed via dual-luciferase reporter assay. The xenograft model was established using U251 cells.

Results

circ-TTBK2 expression was increased in glioma tissues and cells. circ-TTBK2 knockdown suppressed glioma cell proliferation, migration, invasion and glycolysis. circ-TTBK2 was a sponge for miR-1283, and knockdown of miR-1283 reversed the effect of circ-TTBK2 silence on glioma progression. CHD1 was targeted via miR-1283, and miR-1283 repressed glioma cell proliferation, migration, invasion and glycolysis via decreasing CHD1. Knockdown of circ-TTBK2-reduced CHD1 expression by mediating miR-1283. Silence of circ-TTBK2 reduced xenograft tumor growth.

Conclusion

Down-regulation of circ-TTBK2 suppressed glioma development by regulating miR-1283 and CHD1, providing a new mechanism for understanding glioma pathogenesis.

3-Bromopyruvate alleviates the development of monocrotaline-induced rat pulmonary arterial hypertension by decreasing aerobic glycolysis, inducing apoptosis, and suppressing inflammation

BACKGROUND

Pulmonary arterial hypertension (PH) is a progressive disease with limited therapeutic options, ultimately leading to right heart failure and death. Recent findings indicate the role of the Warburg effect (aerobic glycolysis) in the development of PH. However, the effect of the glycolysis inhibitor 3-bromopyruvate (3-BrPA) on the pathogenesis of PH has not been well investigated. This study aimed to determine whether 3-BrPA inhibits PH and its possible mechanism.

METHODS

PH was induced in adult Sprague-Dawley rats by a single intraperitoneal injection of monocrotaline (MCT). 3-BrPA, or phosphate-buffered saline (PBS) was administered via intraperitoneal injection every other day from the first day of MCT-injection to 4 weeks of follow-up, and indices such as right ventricular systolic pressure (RVSP), right ventricular hypertrophy index (RVHI), pulmonary arteriolar remodeling indicated by percent media thickness (% MT), lactate levels and glucose consumption, were evaluated. Pulmonary arteriolar remodeling and right ventricular hypertrophy were observed in hematoxylin-eosin-stained lung sections. Western blotting, immunohistochemistry, and/or immunofluorescence analyses were used to measure the expression of relevant proteins. A cytochrome C release apoptosis assay and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling staining were used to measure cell apoptosis.

RESULTS

MCT-induced PH showed a significant increase in glucose consumption (0 vs. 4 weeks: 0.87 ± 0.23 vs. 2.94 ± 0.47, P = 0.0042) and lactate production (0 vs. 4 weeks: 4.19 ± 0.34 vs. 8.06 ± 0.67, P = 0.0004). Treatment with 3-BrPA resulted in a concomitant reduction in glucose consumption (1.10 ± 0.35 vs. 3.25 ± 0.47, P = 0.0063), lactate production (5.09 ± 0.55 vs. 8.06 ± 0.67, P = 0.0065), MCT-induced increase in RVSP (39.70 ± 2.94 vs. 58.85 ± 2.32, P = 0.0004), pulmonary vascular remodeling (% MT, 43.45% ± 1.41% vs. 63.66% ± 1.78%, P < 0.0001), and right ventricular hypertrophy (RVHI, 38.57% ± 2.69% vs. 62.61% ± 1.57%, P < 0.0001) when compared with those of the PBS-treated group. 3-BrPA, a hexokinase 2 inhibitor, exerted its beneficial effect on PH by decreasing aerobic glycolysis and was also associated with inhibiting the expression of glucose transporter protein-1, inducing apoptosis, and suppressing inflammation.

CONCLUSIONS

3-BrPA might have a potential beneficial effect on the PH treatment.

CircHIPK3/miR-381-3p axis modulates proliferation, migration, and glycolysis of lung cancer cells by regulating the AKT/mTOR signaling pathway

Lung cancer is a lethal malignancy. Plenty of circular RNAs (circRNAs) have been identified to be the vital regulators in lung cancer development. Here, we intended to clarify the functional role of circRNA HIPK3 (circHIPK3, also called hsa_circ_0021593) and its underlying mechanism of action. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was employed to evaluate the levels of circHIPK3 and miR-381-3p. Cell viability and apoptosis rate were monitored by Cell Counting Kit-8 assay and flow cytometry, respectively. Cell migration was estimated through the Transwell assay. To assess glycolysis, commercial kits were utilized to measure the levels of glucose and lactate and the enzyme activity of hexokinase-2 (HK2). Expression of related proteins was detected via western blot analysis. The target connection between circHIPK3 and miR-381-3p was validated by dual-luciferase reporter, RIP, and pull-down assays. The role of circHIPK3 in vivo was determined via the xenograft assay. CircHIPK3 was upregulated, while miR-381-3p was downregulated in lung cancer tissues and cells. And circHIPK3 deficiency inhibited lung cancer progression by lowering cell proliferation, migration, glycolysis, and promoting apoptosis of lung cancer cells in vitro. MiR-381-3p was a target of circHIPK3, and miR-381-3p interference alleviated circHIPK3 knockdown-induced lung cancer progression inhibition. CircHIPK3 could activate the protein kinase B/mammalian target of rapamycin (AKT/mTOR) signaling pathway. Moreover, circHIPK3 knockdown suppressed tumor growth in vivo by inactivating the AKT/mTOR signaling pathway. In conclusion, the silencing of circHIPK3 inhibited lung cancer progression, at least in part, by sponging miR-381-3p and inactivating the AKT/mTOR signaling pathway.

Nf1-Mutant Tumors Undergo Transcriptome and Kinome Remodeling after Inhibition of either mTOR or MEK

Loss of the tumor suppressor NF1 leads to activation of RAS effector pathways, which are therapeutically targeted by inhibition of mTOR (mTORi) or MEK (MEKi). However, therapeutic inhibition of RAS effectors leads to the development of drug resistance and ultimately disease progression. To investigate molecular signatures in the context of NF1 loss and subsequent acquired drug resistance, we analyzed the exomes, transcriptomes, and kinomes of Nf1-mutant mouse tumor cell lines and derivatives of these lines that acquired resistance to either MEKi or mTORi. Biochemical comparisons of this unique panel of tumor cells, all of which arose in Nf1^+/- mice, indicate that loss of heterozygosity of Nf1 as an initial genetic event does not confer a common biochemical signature or response to kinase inhibition. Although acquired drug resistance by Nf1-mutant tumor cells was accompanied by altered kinomes and irreversibly altered transcriptomes, functionally in multiple Nf1-mutant tumor cell lines, MEKi resistance was a stable phenotype, in contrast to mTORi resistance, which was reversible. Collectively, these findings demonstrate that Nf1-mutant tumors represent a heterogeneous group biochemically and undergo broader remodeling of kinome activity and gene expression in response to targeted kinase inhibition.

Analysis of Key Genes Regulating the Warburg Effect in Patients with Gastrointestinal Cancers and Selective Inhibition of This Metabolic Pathway in Liver Cancer Cells

Objective

The Warburg effect, also known as aerobic glycolysis, plays a dominant role in the development of gastrointestinal (GI) cancers. In this study, we analyzed the expression of key genes involved in the Warburg effect in GI cancers and investigated the effect of suppressing the Warburg effect in vitro in liver cancer cell lines.

Methods

The Cancer Genome Atlas (TCGA) RNA-Seq data were used to determine gene expression levels, which were analyzed with GraphPad Prism 7.00. Genetic alterations were queried with cBioPortal. The influence of the Warburg effect on liver cancer cell viability, migration and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity was determined by means of MTT, transwell and GAPDH activity assays.

Results

The levels of expression of genes associated with the Warburg effect were increased in tumors. To our knowledge, this is the first report of upregulated expression of CUEDC2, HMGB2, PFKFB4, PFKP and SIX1 in liver cancer. Clinically, overexpression of these genes was associated with significantly worse overall survival of liver cancer patients. In vitro, selective inhibition of GADPH suppressed the growth and metastasis of Huh-7, Bel7404 and Hep3B hepatocellular carcinoma cell lines.

Conclusion

The Warburg effect may play an important role in GI cancers, especially in liver cancer.

Circ-PVT1/miR-106a-5p/HK2 axis regulates cell growth, metastasis and glycolytic metabolism of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the most commonly diagnosed oral cavity malignancy. A handful of circular RNAs (circRNAs) have recently shown to act as crucial regulators in OSCC, including circRNA plasmacytoma variant translocation 1 (circ-PVT1). However, further exploration is still needed for the underlying functional mechanism behind circ-PVT1 in OSCC. The levels of circ-PVT1, microRNA-106a-5p (miR-106a-5p) and hexokinase II (HK2) were all examined applying with quantitative real-time polymerase chain reaction (qRT-PCR). Cellular analyses (cell viability, apoptosis, metastasis and glycolysis) in vitro were performed via cell counting kit-8 (CCK-8), flow cytometry, transwell migration/invasion assays and glycolysis-related indications (glucose consumption, lactate production and ATP/ADP ratio). HK2 protein level was measured through western blot. Dual-luciferase reporter assay was conducted to study the interplay between miR-106a-5p and circ-PVT1 or HK2. Xenografts in mice were used for analyzing circ-PVT1 in vivo. Circ-PVT1 was expressed with abnormal high level while miR-106a-5p was down-regulated in OSCC tissues and cells. Circ-PVT1 knockdown reduced OSCC cell growth, metastasis and glycolysis. Moreover, circ-PVT1 acted in OSCC by functioning as a miR-106a-5p sponge. HK2 was a target of miR-106a-5p and miR-106a-5p played an anti-tumor role in OSCC by inhibiting HK2. Furthermore, HK2 could be regulated by circ-PVT1 via targeting miR-106a-5p. In xenograft models of mice, down-regulation of circ-PVT1 retarded tumorigenesis via the miR-106a-5p/HK2 axis. Our works suggested that circ-PVT1 directly combined with miR-106a-5p to mediate HK2 level, consequently regulating cellular behaviors in OSCC as a tumor promoter.

Emerging roles and the regulation of aerobic glycolysis in hepatocellular carcinoma

Liver cancer has become the sixth most diagnosed cancer and the fourth leading cause of cancer death worldwide. Hepatocellular carcinoma (HCC) is responsible for up to 75–85% of primary liver cancers, and sorafenib is the first targeted drug for advanced HCC treatment. However, sorafenib resistance is common because of the resultant enhancement of aerobic glycolysis and other molecular mechanisms. Aerobic glycolysis was firstly found in HCC, acts as a hallmark of liver cancer and is responsible for the regulation of proliferation, immune evasion, invasion, metastasis, angiogenesis, and drug resistance in HCC. The three rate-limiting enzymes in the glycolytic pathway, including hexokinase 2 (HK2), phosphofructokinase 1 (PFK1), and pyruvate kinases type M2 (PKM2) play an important role in the regulation of aerobic glycolysis in HCC and can be regulated by many mechanisms, such as the AMPK, PI3K/Akt pathway, HIF-1α, c-Myc and noncoding RNAs. Because of the importance of aerobic glycolysis in the progression of HCC, targeting key factors in its pathway such as the inhibition of HK2, PFK or PKM2, represent potential new therapeutic approaches for the treatment of HCC.

Glycolysis inhibition and apoptosis induction in human prostate cancer cells by FV-429-mediated regulation of AR-AKT-HK2 signaling network

Prostate cancer (PCa) depends on androgen receptor (AR) signaling to regulate cell metabolism, including glycolysis, and thereby promotes tumor growth. Glycolysis is overactive in PCa and associated with poor prognosis, but the therapeutic efficacy of glycolysis inhibitors has thus far been limited by their inability to induce cell death. FV-429, a flavonoid derivative of Wogonin, is a glycolysis inhibitor that has shown anti-cancer promise. In this study, we used FV-429 as an anti-PCa agent and investigated its mechanisms of action. In vitro, both the glycolytic ability and the viability of PCa cells were inhibited by FV-429. We found that FV-429 could induce mitochondrial dysfunction and apoptosis, with AKT-HK2 signaling pathway playing a key role. In addition, FV-429 had a pro-apoptotic effect on human prostate cancer cells that relied on the inhibition of AR expression and activity. In vivo, FV-429 exerted significant tumor-repressing activity with high safety in the xenograft model using LNCaP cells. In summary, we demonstrated that FV-429 induced glycolysis inhibition and apoptosis in human prostate cancer cells by downregulating the AR-AKT-HK2 signaling network, making FV-429 a promising candidate as one therapeutic agent for advanced PCa.

Downregulation of PER2 Promotes Tumor Progression by Enhancing Glycolysis via the Phosphatidylinositol 3-Kinase/Protein Kinase B Pathway in Oral Squamous Cell Carcinoma

PURPOSE

PER2 gene expression is downregulated in oral squamous cell carcinoma (OSCC) and may have a pivotal role in tumor suppression. However, the biological function and mechanism of action of PER2 in OSCC remain unclear. In this study, the biological functions and anticancer mechanisms of PER2 in OSCC were investigated.

MATERIALS AND METHODS

Both stably overexpressed and silenced PER2 OSCC cells were established as an experimental group; empty vector lentivirus and scramble short hairpin RNA lentivirus transfected-cells, as negative control groups; and untreated OSCC cells, as a blank group. Cell proliferation, apoptosis, and glycolysis potential assays were conducted. In addition, the expression of phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), phosphorylation of protein kinase B, hexokinase 2 (HK2), pyruvate kinase M (PKM2), and lactate dehydrogenase A (LDHA) was quantified by real-time quantitative polymerase chain reaction and Western blotting. Rescue experiments were performed by the addition of AKT activators in the overexpressed cell line and by the addition of glycolysis inhibitor in the silenced cell line. These findings were verified in vivo using stably transfected OSCC cells overexpressing PER2 implanted in nude mice.

RESULTS

PER2 overexpression significantly inhibited OSCC cell proliferation and glycolysis, promoted cell apoptosis, and reduced the expression of PI3K, phosphorylation of protein kinase B, HK2, PKM2, and LDHA. The converse was observed in PER2-silenced OSCC cells. After the addition of AKT activator to cultures of PER2-overexpressed OSCC cells, reduced glucose uptake, lactic acid production, and cell proliferation, combined with increased apoptosis, were substantially reversed. In addition, after the addition of HK2 inhibitor to PER2-silenced OSCC cells to inhibit glycolysis, the reduction in apoptosis and increased proliferation were significantly countermanded. Tumorigenesis experiments in vivo also confirmed that PER2 overexpression suppressed OSCC growth and decreased the expression of HK2, PKM2, and LDHA.

CONCLUSIONS

PER2 heightened glycolysis via the PI3K/AKT pathway, heightened cell proliferation and inhibited apoptosis via glycolysis, thereby promoting the development of OSCC.

3-Bromopyruvate ameliorates pulmonary arterial hypertension by improving mitochondrial metabolism

AIMS

Abnormal mitochondrial metabolism is an essential factor for excessive proliferation of pulmonary artery smooth muscle cells (PASMCs), which drives the pathological process of pulmonary arterial hypertension (PAH). 3-Bromopyruvate (3-BrPA) is an effective glycolytic inhibitor that improves mitochondrial metabolism, thereby repressing anomalous cell proliferation.

MAIN METHODS

An experimental PAH model was established by injection of monocrotaline (MCT) in male Sprague Dawley rats, following which rats were assigned to three groups: control, MCT, and 3-BrPA groups. Three days post injection of MCT, rats were treated with 3-BrPA or vehicle for 4 weeks. At the end of the study, hemodynamic data were measured to confirm PAH condition. Indicators of pulmonary arterial and right ventricular (RV) remodeling as well as the proliferative ability of PASMCs were assayed. Additionally, mitochondrial morphology and function, and antiglycolytic and antiproliferative pathways and genes were analyzed.

KEY FINDINGS

Treatment with 3-BrPA effectively improved pulmonary vascular remodeling and right ventricular function, inhibited PASMC proliferation, and preserved mitochondrial morphology and function. Besides, 3-BrPA treatment inhibited the PI3K/AKT/mTOR pathway and regulated the expression of antiproliferative genes in PASMCs. However, bloody ascites, bloating, and cirrhosis of organs were observed in some 3-BrPA treated rats.

SIGNIFICANCE

3-BrPA acts as an important glycolytic inhibitor to improve energy metabolism and reverse the course of PAH. However, 3-BrPA is associated with side effects in MCT-induced rats, indicating that it should be caution in drug delivery dosage, and further studies are needed to evaluate this toxicological mechanism.

Identification of Key Biological Processes, Pathways, Networks, and Genes with Potential Prognostic Values in Hepatocellular Carcinoma Using a Bioinformatics Approach

Aim: Hepatocellular carcinoma (HCC), as one primary liver cancer type, accounts for 75%-85% of liver cancer cases. HCC is the second leading cause of cancer death in East Asia and sub-Saharan Africa and the sixth most common in western countries. Identification of key genes would facilitate the development of therapies and improve the prognosis outcomes of HCC patients. This study was to identify the key biological processes, pathways, and key genes in HCC. Methods: Data were downloaded from Broad GDAC. Differentially expressed genes (DEGs) and weighted gene coexpression network (WGCNA) were analyzed by DESeq2 and WGCNA, respectively. Gene ontology (GO) and KEGG enrichment analyses were performed on all DEGs and the coexpressed genes in two significant modules. Kaplan-Meier plotter online database was used to identify the potential prognostic genes in HCC. Finally, GEO database was used to validate the analysis of gene expression of Broad GDAC data. Results: The authors identified the dark gray and red modules as the significant modules in HCC based on WGCNA. GO and KEGG enrichment of the two significant modules identified the mitochondrion-mediated metabolic processes and pathways, and the cell cycle as the key biological processes and pathways in HCC. Subsequently, 28 hub genes were screened out by constructing protein-protein interaction network using Metascape. Finally, three genes (NDUFAF6, CKAP5, and DSN1 genes) were identified to be potential prognostic and key genes in HCC based on Kaplan-Meier survival analysis, GEO dataset validation, and literature review. Conclusions: The authors found that mitochondrion-mediated metabolic processes and the cell cycle were the key biological processes and pathways in HCC. NDUFAF6, CKAP5, and DSN1 genes were valuable genes with the potential to be prognosis biomarkers and targeted therapies in HCC.

ATG12 deficiency leads to tumor cell oncosis owing to diminished mitochondrial biogenesis and reduced cellular bioenergetics

In contrast to the "Warburg effect" or aerobic glycolysis earlier generalized as a phenomenon in cancer cells, more and more recent evidence indicates that functional mitochondria are pivotal for ensuring the energy supply of cancer cells. Here, we report that cancer cells with reduced autophagy-related protein 12 (ATG12) expression undergo an oncotic cell death, a phenotype distinct from that seen in ATG5-deficient cells described before. In addition, using untargeted metabolomics with ATG12-deficient cancer cells, we observed a global reduction in cellular bioenergetic pathways, such as β-oxidation (FAO), glycolysis, and tricarboxylic acid cycle activity, as well as a decrease in mitochondrial respiration as monitored with Seahorse experiments. Analyzing the biogenesis of mitochondria by quantifying mitochondrial DNA content together with several mitochondrion-localizing proteins indicated a reduction in mitochondrial biogenesis in ATG12-deficient cancer cells, which also showed reduced hexokinase II expression and the upregulation of uncoupling protein 2. ATG12, which we observed in normal cells to be partially localized in mitochondria, is upregulated in multiple types of solid tumors in comparison with normal tissues. Strikingly, mouse xenografts of ATG12-deficient cells grew significantly slower as compared with vector control cells. Collectively, our work has revealed a previously unreported role for ATG12 in regulating mitochondrial biogenesis and cellular energy metabolism and points up an essential role for mitochondria as a failsafe mechanism in the growth and survival of glycolysis-dependent cancer cells. Inducing oncosis by imposing an ATG12 deficiency in solid tumors might represent an anticancer therapy preferable to conventional caspase-dependent apoptosis that often leads to undesirable consequences, such as incomplete cancer cell killing and a silencing of the host immune system.

Mitochondria in cancer

The rediscovery and reinterpretation of the Warburg effect in the year 2000 occulted for almost a decade the key functions exerted by mitochondria in cancer cells. Until recent times, the scientific community indeed focused on constitutive glycolysis as a hallmark of cancer cells, which it is not, largely ignoring the contribution of mitochondria to the malignancy of oxidative and glycolytic cancer cells, being Warburgian or merely adapted to hypoxia. In this review, we highlight that mitochondria are not only powerhouses in some cancer cells, but also dynamic regulators of life, death, proliferation, motion and stemness in other types of cancer cells. Similar to the cells that host them, mitochondria are capable to adapt to tumoral conditions, and probably to evolve to ‘oncogenic mitochondria' capable of transferring malignant capacities to recipient cells. In the wider quest of metabolic modulators of cancer, treatments have already been identified targeting mitochondria in cancer cells, but the field is still in infancy.

The Anticancer Drug 3-Bromopyruvate Induces DNA Damage Potentially Through Reactive Oxygen Species in Yeast and in Human Cancer Cells

3-bromopyruvate (3-BP) is a small molecule with anticancer and antimicrobial activities. 3-BP is taken up selectively by cancer cells’ mono-carboxylate transporters (MCTs), which are highly overexpressed by many cancers. When 3-BP enters cancer cells it inactivates several glycolytic and mitochondrial enzymes, leading to ATP depletion and the generation of reactive oxygen species. While mechanisms of 3-BP uptake and its influence on cell metabolism are well understood, the impact of 3-BP at certain concentrations on DNA integrity has never been investigated in detail. Here we have collected several lines of evidence suggesting that 3-BP induces DNA damage probably as a result of ROS generation, in both yeast and human cancer cells, when its concentration is sufficiently low and most cells are still viable. We also demonstrate that in yeast 3-BP treatment leads to generation of DNA double-strand breaks only in S-phase of the cell cycle, possibly as a result of oxidative DNA damage. This leads to DNA damage, checkpoint activation and focal accumulation of the DNA response proteins. Interestingly, in human cancer cells exposure to 3-BP also induces DNA breaks that trigger H2A.X phosphorylation. Our current data shed new light on the mechanisms by which a sufficiently low concentration of 3-BP can induce cytotoxicity at the DNA level, a finding that might be important for the future design of anticancer therapies.

Kruppel-like factor 2 disturb non-small cell lung cancer energy metabolism by inhibited glutamine consumption

OBJECTIVES

Metabolic reprogramming is well accepted as a hallmark of cancer. This study aimed to explore the role of Kruppel-like factor 2 (KLF2) in aerobic glycolysis and glutamine consumption of energy metabolism in non-small cell lung cancer (NSCLC) cells.

METHODS

Two different NSCLC cells, A549 and NCI-H1299, were used to investigate the role of KLF2 in glycolysis and glutamine consumption by tracer technique and KLF2 transfection.

KEY FINDINGS

The results showed that overexpression KLF could inhibit the energy metabolism and proliferation of NSCLC cells, but had no significant effect on glycolysis reaction and only affected the glutamine consumption of NSCLC cells. In NSCLC cells exposed to glutamine deprivation, the effect of overexpression of KLF2 on cell proliferation and energy metabolism disappeared. It was found that KLF2 could inhibit the expression of glutaminase (GLS) by metabolite tracing technique and so on. However, when GLS inhibitors were given to overexpressing KLF2 NSCLC cells, the intervention effect of KLF2 disappeared.

CONCLUSIONS

Kruppel-like factor 2 could decrease the level of glutamine, participate in the consumption of glutamine by cancer cells, and then inhibit the energy metabolism of cancer cells.

Pathological Mechanistic Studies of Osimertinib Resistance in Non-Small-Cell Lung Cancer Cells Using an Integrative Metabolomics-Proteomics Analysis

Background

Osimertinib is the first-line therapeutic option for the T790M-mutant non-small-cell lung cancer and the acquired resistance obstructs its application. It is an urgent challenge to identify the potential mechanisms of osimertinib resistance for uncovering some novel therapeutic approaches.

Methods

In the current study, the cell metabolomics based on ultra-high-performance liquid chromatography coupled with linear ion trap-Orbitrap mass spectrometry and the qualitative and tandem mass tags quantitative proteomics were performed.

Results

54 differential metabolites and 195 differentially expressed proteins were, respectively, identified. The amino acids metabolisms were significantly altered. HIF-1 signaling pathway modulating P-glycoproteins expression, PI3K-Akt pathway regulating survivin expression, and oxidative phosphorylation were upregulated, while arginine and proline metabolism regulating NO production and glycolysis/gluconeogenesis were downregulated during osimertinib resistance.

Conclusion

The regulation of HIF-1 and PI3K-Akt signaling pathway, energy supply process, and amino acids metabolism are the promising therapeutic tactics for osimertinib resistance.

Elevated Glutathione Peroxidase 2 Expression Promotes Cisplatin Resistance in Lung Adenocarcinoma

The aim of this study was to explore the roles of GPX2, a member of the glutathione peroxidase family (GPXs, GSH-Px), in cisplatin (DDP) resistance in lung adenocarcinoma (LUAD). GPX2 was found to be the most significantly upregulated gene in a DDP-resistant A549/DDP cell line compared with the parental A549 cell line by RNA sequencing. The knockdown of GPX2 expression in A549/DDP cells inhibited cell proliferation in vitro and in vivo, decreased the IC₅₀ values of DDP, induced apoptosis, inhibited the activities of GSH-Px and superoxide dismutase (SOD), inhibited ATP production and glucose uptake, and increased malondialdehyde (MDA) and reactive oxygen species (ROS) production; while GPX2 overexpression in A549 cells resulted in the opposite effects. Using gene set enrichment analysis (GSEA), we found that GPX2 may be involved in DDP resistance through mediating drug metabolism, the cell cycle, DNA repair and energy metabolism, and the regulation of an ATP-binding cassette (ABC) transporters member ABCB6, which is one of the hallmark genes in glycolysis. Moreover, immunohistochemistry revealed that GPX2 was upregulated in 58.6% (89/152) of LUAD cases, and elevated GPX2 expression was correlated with high expression of ABCB6, high 18-fluorodeoxyglucose (18F-FDG) uptake, and adverse disease-free survival (DFS) in our cohort. The Cancer Genome Atlas (TCGA) data also indicated that GPX2 expression was higher in LUAD than it was in normal lung tissues, and the mRNA expression levels of GPX2 and ABCB6 were positively correlated. In conclusion, our study demonstrates that GPX2 acts as oncogene in LUAD and promotes DDP resistance by regulating oxidative stress and energy metabolism.

Regulatory Role of Hexokinase 2 in Modulating Head and Neck Tumorigenesis

To support great demand of cell growth, cancer cells preferentially obtain energy and biomacromolecules by glycolysis over mitochondrial oxidative phosphorylation (OxPhos). Among all glycolytic enzymes, hexokinase (HK), a rate-limiting enzyme at the first step of glycolysis to catalyze cellular glucose into glucose-6-phosphate, is herein emphasized. Four HK isoforms, HK1-HK4, were discovered in nature. It was shown that HK2 expression is enriched in many tumor cells and correlated with poorer survival rates in most neoplastic cells. HK2-mediated regulations for cell malignancy and mechanistic cues in regulating head and neck tumorigenesis, however, are not fully elucidated. Cellular malignancy index, such as cell growth, cellular motility, and treatment sensitivity, and molecular alterations were determined in HK2-deficient head and neck squamous cell carcinoma (HNSCC) cells. By using various cancer databases, HK2, but not HK1, positively correlates with HNSCC progression in a stage-dependent manner. A high HK2 expression was detected in head and neck cancerous tissues compared with their normal counterparts, both in mouse and human subjects. Loss of HK2 in HNSCC cells resulted in reduced cell (in vitro) and tumor (in vivo) growth, as well as decreased epithelial-mesenchymal transition–mediated cell movement; in contrast, HK2-deficient HNSCC cells exhibited greater sensitivity to chemotherapeutic drugs cisplatin and 5-fluorouracil but are more resistant to photodynamic therapy, indicating that HK2 expression could selectively define treatment sensitivity in HNSCC cells. At the molecular level, it was found that HK2 alteration drove metabolic reprogramming toward OxPhos and modulated oncogenic Akt and mutant TP53-mediated signals in HNSCC cells. In summary, the present study showed that HK2 suppression could lessen HNSCC oncogenicity and modulate therapeutic sensitivity, thereby being an ideal therapeutic target for HNSCCs.