Targeting glucose metabolism to suppress cancer progression: prospective of anti-glycolytic cancer therapy

Long non-coding RNA-based glycolysis-targeted cancer therapy: feasibility, progression and limitations

Metabolism reprogramming is one of the hallmarks of cancer cells, especially glucose metabolism, to promote their proliferation, metastasis and drug resistance. Cancer cells tend to depend on glycolysis for glucose utilization rather than oxidative phosphorylation, which is called the Warburg effect. Genome instability of oncogenes and tumor-inhibiting factors is the culprits for this anomalous glycolytic fueling, which results in dysregulating metabolism-related enzymes and metabolic signaling pathways. It has been extensively demonstrated that protein-coding genes are involved in this process; therefore, glycolysis-targeted therapy has been widely used in anti-tumor combined therapy via small molecular inhibitors of key enzymes and regulatory molecular. The long non-coding RNA, which is a large class of regulatory RNA with longer than 200 nucleotides, is the novel and significant regulator of various biological processes, including metabolic reprogramming. RNA interference and synthetic antisense oligonucleotide for RNA reduction have developed rapidly these years, which presents potent anti-tumor effects both in vitro and in vivo. However, lncRNA-based glycolysis-targeted cancer therapy, as the highly specific and less toxic approach, is still under the preclinical phase. In this review, we highlight the role of lncRNA in glucose metabolism and dissect the feasibility and limitations of this clinical development, which may provide potential targets for cancer therapy.

CDK9 Inhibitor Induces the Apoptosis of B-Cell Acute Lymphocytic Leukemia by Inhibiting c-Myc-Mediated Glycolytic Metabolism

B-cell acute lymphocytic leukemia (B-ALL), a common blood cancer in children, leads to high mortality. Cyclin-dependent kinase 9 inhibitor (CDK9i) effectively attenuates acute myeloid leukemia and chronic lymphoblastic leukemia by inducing apoptosis and inhibiting cell proliferation. However, the effect of CDK9i on B-ALL cells and the underlying mechanisms remain unclear. In this study, we showed that CDK9i induced the apoptosis of B-ALL cells in vitro by activating the apoptotic pathways. In addition, CDK9i restrained the glycolytic metabolism of B-ALL cells, and CDK9i-induced apoptosis was enhanced by co-treatment with glycolysis inhibitors. Furthermore, CDK9i restained the glycolysis of B-ALL cell lines by markedly downregulating the expression of glucose transporter type 1 (GLUT1) and the key rate-limiting enzymes of glycolysis, such as hexokinase 2 (HK2) and lactate dehydrogenase A (LDHA). Moreover, cell apoptosis was rescued in B-ALL cells with over-expressed c-Myc after treatment with CDK9i, which is involved in the enhancement of glycolytic metabolism. In summary, our findings suggest that CDK9 inhibitors induce the apoptosis of B-ALL cells by inhibiting c-Myc-mediated glycolytic metabolism, thus providing a new strategy for the treatment of B-ALL.

Vitamin D regulation of energy metabolism in cancer

Vitamin D exerts anti-cancer effects in recent clinical trials and preclinical models. The actions of vitamin D are primarily mediated through its hormonal form, 1,25-dihydroxyvitamin D (1,25(OH)₂ D). Previous literature describing in vitro studies has predominantly focused on the anti-tumourigenic effects of the hormone, such as proliferation and apoptosis. However, recent evidence has identified 1,25(OH)₂ D as a regulator of energy metabolism in cancer cells, where requirements for specific energy sources at different stages of progression are dramatically altered. The literature suggests that 1,25(OH)₂ D regulates energy metabolism, including glucose, glutamine and lipid metabolism during cancer progression, as well as oxidative stress protection, as it is closely associated with energy metabolism. Mechanisms involved in energy metabolism regulation are an emerging area in which vitamin D may inhibit multiple stages of cancer progression.

Linking Metabolic Reprogramming, Plasticity and Tumor Progression

Simple Summary

In the present review, we discuss the role of metabolic reprogramming which occurs in malignant cells. The process of metabolic reprogramming is also known as one of the “hallmarks of cancer”. Due to several reasons, including the origin of cancer, tumor microenvironment, and the tumor progression stage, metabolic reprogramming can be heterogeneous and dynamic. In this review, we provide evidence that the usage of metabolic drugs is a promising approach to treat cancer. However, because these drugs can damage not only malignant cells but also normal rapidly dividing cells, it is important to understand the exact metabolic changes which are elicited by particular drivers in concrete tissue and are specific for each stage of cancer development, including metastases. Finally, the review highlights new promising targets for the development of new metabolic drugs.

Abstract

The specific molecular features of cancer cells that distinguish them from the normal ones are denoted as “hallmarks of cancer”. One of the critical hallmarks of cancer is an altered metabolism which provides tumor cells with energy and structural resources necessary for rapid proliferation. The key feature of a cancer-reprogrammed metabolism is its plasticity, allowing cancer cells to better adapt to various conditions and to oppose different therapies. Furthermore, the alterations of metabolic pathways in malignant cells are heterogeneous and are defined by several factors including the tissue of origin, driving mutations, and microenvironment. In the present review, we discuss the key features of metabolic reprogramming and plasticity associated with different stages of tumor, from primary tumors to metastases. We also provide evidence of the successful usage of metabolic drugs in anticancer therapy. Finally, we highlight new promising targets for the development of new metabolic drugs.

Gene editing and synthetically accessible inhibitors reveal role for TPC2 in HCC cell proliferation and tumor growth

The role of two-pore channel 2 (TPC2), one of the few cation channels localized on endolysosomal membranes, in cancer remains poorly understood. Here, we report that TPC2 knockout reduces proliferation of cancer cells in vitro, affects their energy metabolism, and successfully abrogates tumor growth in vivo. Concurrently, we have developed simplified analogs of the alkaloid tetrandrine as potent TPC2 inhibitors by screening a library of synthesized benzyltetrahydroisoquinoline derivatives. Removal of dispensable substructures of the lead molecule tetrandrine increases antiproliferative properties against cancer cells and impairs proangiogenic signaling of endothelial cells to a greater extent than tetrandrine. Simultaneously, toxic effects on non-cancerous cells are reduced, allowing in vivo administration and revealing a TPC2 inhibitor with antitumor efficacy in mice. Hence, our study unveils TPC2 as valid target for cancer therapy and provides easily accessible tetrandrine analogs as a promising option for effective pharmacological interference.

CPNE1 Enhances Colorectal Cancer Cell Growth, Glycolysis, and Drug Resistance Through Regulating the AKT-GLUT1/HK2 Pathway

Introduction

Colorectal cancer (CRC) is a major cause of cancer-related mortality worldwide. Copines-1 (CPNE1) has been shown to be overexpressed in various cancers; however, the role of CPNE1 in CRC remains unknown. Therefore, it is of great importance to elucidate the role of CPNE1 in CRC and its underlying mechanism of action.

Methods

CPNE1 expression in CRC tissues was measured by quantitative real-time PCR and immunohistochemical (IHC) staining. CPNE1 was knocked down (KD) or overexpressed using small inferring RNAs or lentiviral transduction in CRC cells. The proliferation, apoptosis, glycolysis, and mitochondrial respiration of CRC cells were assessed by cell counting kit-8, flow cytometry, and Xfe24 extracellular flux analyzer assays, respectively. The role of CPNE1 in tumor growth and chemoresistance was further confirmed in xenograft and patient-derived tumor xenograft models, respectively.

Results

CPNE1 mRNA and protein were upregulated in CRC tissues. CPNE1 promoted proliferation, inhibited apoptosis, increased mitochondrial respiration, enhanced aerobic glycolysis by activating AKT signaling, upregulated glucose transporter 1 (GLUT1) and hexokinase 2 (HK2), and downregulated the production of cleaved Caspase-3 (c-Caspase 3). CPNE1 also contributed to chemoresistance in CRC cells. CPNE1 KD inhibited tumor growth and increased the sensitivity of tumors to oxaliplatin in vivo.

Conclusion

CPNE1 promotes CRC progression by activating the AKT-GLUT1/HK2 cascade and enhances chemoresistance.

Beyond the Warburg Effect: Oxidative and Glycolytic Phenotypes Coexist within the Metabolic Heterogeneity of Glioblastoma

Glioblastoma (GBM) is the most aggressive primary brain tumor, with a median survival at diagnosis of 16-20 months. Metabolism represents a new attractive therapeutic target; however, due to high intratumoral heterogeneity, the application of metabolic drugs in GBM is challenging. We characterized the basal bioenergetic metabolism and antiproliferative potential of metformin (MF), dichloroacetate (DCA), sodium oxamate (SOD) and diazo-5-oxo-L-norleucine (DON) in three distinct glioma stem cells (GSCs) (GBM18, GBM27, GBM38), as well as U87MG. GBM27, a highly oxidative cell line, was the most resistant to all treatments, except DON. GBM18 and GBM38, Warburg-like GSCs, were sensitive to MF and DCA, respectively. Resistance to DON was not correlated with basal metabolic phenotypes. In combinatory experiments, radiomimetic bleomycin exhibited therapeutically relevant synergistic effects with MF, DCA and DON in GBM27 and DON in all other cell lines. MF and DCA shifted the metabolism of treated cells towards glycolysis or oxidation, respectively. DON consistently decreased total ATP production. Our study highlights the need for a better characterization of GBM from a metabolic perspective. Metabolic therapy should focus on both glycolytic and oxidative subpopulations of GSCs.

Anti-Warburg Effect of Melatonin: A Proposed Mechanism to Explain its Inhibition of Multiple Diseases

Glucose is an essential nutrient for every cell but its metabolic fate depends on cellular phenotype. Normally, the product of cytosolic glycolysis, pyruvate, is transported into mitochondria and irreversibly converted to acetyl coenzyme A by pyruvate dehydrogenase complex (PDC). In some pathological cells, however, pyruvate transport into the mitochondria is blocked due to the inhibition of PDC by pyruvate dehydrogenase kinase. This altered metabolism is referred to as aerobic glycolysis (Warburg effect) and is common in solid tumors and in other pathological cells. Switching from mitochondrial oxidative phosphorylation to aerobic glycolysis provides diseased cells with advantages because of the rapid production of ATP and the activation of pentose phosphate pathway (PPP) which provides nucleotides required for elevated cellular metabolism. Molecules, called glycolytics, inhibit aerobic glycolysis and convert cells to a healthier phenotype. Glycolytics often function by inhibiting hypoxia-inducible factor-1α leading to PDC disinhibition allowing for intramitochondrial conversion of pyruvate into acetyl coenzyme A. Melatonin is a glycolytic which converts diseased cells to the healthier phenotype. Herein we propose that melatonin's function as a glycolytic explains its actions in inhibiting a variety of diseases. Thus, the common denominator is melatonin's action in switching the metabolic phenotype of cells.

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.

Fucoidan Structure and Its Impact on Glucose Metabolism: Implications for Diabetes and Cancer Therapy

Fucoidans are complex polysaccharides derived from brown seaweeds which consist of considerable proportions of L-fucose and other monosaccharides, and sulphated ester residues. The search for novel and natural bioproduct drugs (due to toxicity issues associated with chemotherapeutics) has led to the extensive study of fucoidan due to reports of it having several bioactive characteristics. Among other fucoidan bioactivities, antidiabetic and anticancer properties have received the most research attention in the past decade. However, the elucidation of the fucoidan structure and its biological activity is still vague. In addition, research has suggested that there is a link between diabetes and cancer; however, limited data exist where dual chemotherapeutic efforts are elucidated. This review provides an overview of glucose metabolism, which is the central process involved in the progression of both diseases. We also highlight potential therapeutic targets and show the relevance of fucoidan and its derivatives as a candidate for both cancer and diabetes therapy.

Dichloroacetate and Pyruvate Metabolism: Pyruvate Dehydrogenase Kinases as Targets Worth Investigating for Effective Therapy of Toxoplasmosis

Toxoplasmosis, a protozoan infection caused by Toxoplasma gondii, is estimated to affect around 2.5 billion people worldwide. Nevertheless, the side effects of drugs combined with the long period of therapy usually result in discontinuation of the treatment. New therapies should be developed by exploring peculiarities of the parasite's metabolic pathways, similarly to what has been well described in cancer cell metabolism. An example is the switch in the metabolism of cancer that blocks the conversion of pyruvate into acetyl coenzyme A in mitochondria. In this context, dichloroacetate (DCA) is an anticancer drug that reverts the tumor proliferation by inhibiting the enzymes responsible for this switch: the pyruvate dehydrogenase kinases (PDKs). DCA has also been used in the treatment of certain symptoms of malaria; however, there is no evidence of how this drug affects apicomplexan species. In this paper, we studied the metabolism of T. gondii and demonstrate that DCA also inhibits T. gondii's in vitro infection with no toxic effects on host cells. DCA caused an increase in the activity of pyruvate dehydrogenase followed by an unbalanced mitochondrial activity. We also observed morphological alterations frequently in mitochondria and in a few apicoplasts, essential organelles for parasite survival. To date, the kinases that potentially regulate the activity of pyruvate metabolism in both organelles have never been described. Here, we confirmed the presence in the genome of two putative kinases (T. gondii PDK [TgPDK] and T. gondii branched-chain α-keto acid dehydrogenase kinase [TgBCKDK]), verified their cellular localization in the mitochondrion, and provided in silico data suggesting that they are potential targets of DCA.IMPORTANCE Currently, the drugs used for toxoplasmosis have severe toxicity to human cells, and the treatment still lacks effective and safer alternatives. The search for novel drug targets is timely. We report here that the treatment of T. gondii with an anticancer drug, dichloroacetate (DCA), was effective in decreasing in vitro infection without toxicity to human cells. It is known that PDK is the main target of DCA in mammals, and this inactivation increases the conversion of pyruvate into acetyl coenzyme A and reverts the proliferation of tumor cells. Moreover, we verified the mitochondrial localization of two kinases that possibly regulate the activity of pyruvate metabolism in T. gondii, which has never been studied. DCA increased pyruvate dehydrogenase (PDH) activity in T. gondii, followed by an unbalanced mitochondrial activity, in a manner similar to what was previously observed in cancer cells. Thus, we propose the conserved kinases as potential regulators of pyruvate metabolism and interesting targets for new therapies.

18F-FDG PET/CT Scans Can Identify Sub-Groups of NSCLC Patients with High Glucose Uptake in the Majority of Their Tumor Lesions

Background: Reprogrammed glucose metabolism is a hallmark of cancer making it an attractive therapeutic target, especially in cancers with high glucose uptake such as non-small cell lung cancer (NSCLC). Tools to select patients with high glucose uptake in the majority of tumor lesions are essential in the development of anti-cancer drugs targeting glucose metabolism. Type 2 diabetes mellitus (T2DM) patients may have tumors highly dependent on glucose uptake. Surprisingly, this has not been systematically studied. Therefore, we aimed to determine which patient and tumor characteristics, including concurrent T2DM, are related to high glucose uptake in the majority of tumor lesions in NSCLC patients as measured by 2-deoxy-2-[fluorine-18]fluoro-D-glucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) scans.

Methods: Routine primary diagnostic ¹⁸F-FDG PET/CT scans of consecutive NSCLC patients were included. Mean standardized uptake value (SUVmean) of ¹⁸F-FDG was determined for all evaluable tumor lesions and corrected for serum glucose levels according to the European Association of Nuclear Medicine Research Ltd guidelines. Patient characteristics potentially determining degree of tumor lesion glucose uptake in the majority of tumor lesions per patient were investigated.

Results: The cohort consisted of 102 patients, 28 with T2DM and 74 without T2DM. The median SUVmean per patient ranged from 0.8 to 35.2 (median 4.2). T2DM patients had higher median glucose uptake in individual tumor lesions and per patient compared to non-diabetic NSCLC patients (SUVmean 4.3 vs 2.8, P < 0.001 and SUVmean 5.4 vs 3.7, P = 0.009, respectively). However, in multivariable analysis, high tumor lesion glucose uptake was only independently determined by number of tumor lesions ≥1 mL per patient (odds ratio 0.8, 95% confidence interval 0.7-0.9).

Conclusions:¹⁸F-FDG PET/CT scans can identify sub-groups of NSCLC patients with high glucose uptake in the majority of their tumor lesions. T2DM patients had higher tumor lesion glucose uptake than non-diabetic patients. However, this was not independent of other factors such as the histological subtype and number of tumor lesions per patient.

LINC00839 Regulates Proliferation, Migration, Invasion, Apoptosis and Glycolysis in Neuroblastoma Cells Through miR-338-3p/GLUT1 Axis

BACKGROUND

Long noncoding RNAs (lncRNAs) are related to the development and treatment of neuroblastoma. The lncRNA LINC00839 is dysregulated in neuroblastoma, while its function and mechanism in neuroblastoma development remain largely unclear.

METHODS

The tumor and adjacent noncancerous tissues were collected from 48 neuroblastoma patients. LINC00839, glucose transporter 1 (GLUT1) and microRNA-338-3p (miR-338-3p) abundances were examined via quantitative reverse transcription polymerase chain reaction or Western blot. Cell proliferation, apoptosis, migration, invasion and glycolysis were assessed via Cell Counting Kit-8, colony formation, flow cytometry, wound healing, transwell, glucose uptake and lactate production. The target relationship of miR-338-3p and LINC00839 or GLUT1 was tested via dual-luciferase reporter analysis and RNA immunoprecipitation. The function of LINC00839 on neuroblastoma cell growth in vivo was tested via a xenograft model.

RESULTS

LINC00839 and GLUT1 abundances were increased in neuroblastoma tissues and cell lines. The high expression of LINC00839 and GLUT1 indicated the lower overall survival. LINC00839 interference constrained neuroblastoma cell proliferation, migration, invasion and glycolysis, and facilitated apoptosis. GLUT1 overexpression or miR-338-3p knockdown could mitigate the influence of LINC00839 silence on neuroblastoma cell processes. LINC00839 could regulate GLUT1 expression via miR-338-3p. LINC00839 knockdown reduced neuroblastoma cell growth in xenograft model.

CONCLUSION

LINC00839 silence repressed neuroblastoma cell proliferation, migration, invasion and glycolysis and promoted apoptosis via regulating miR-338-3p/GLUT1 axis.

Balanophorin B inhibited glycolysis with the involvement of HIF-1α

AIMS

Cancer cells exhibit a metabolic change called aerobic glycolysis compared with normal cells. Balanophorin B is a terpenoid ingredient reported from the genus Balanophora. In this research, we studied the effect of balanophorin B on glycolysis of HepG2 cells and Huh-7 cells under hypoxia.

MAIN METHODS

The Warburg effect was monitored by assessing glucose uptake, oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). Key enzymes in the glycolytic pathway and HIF-1α protein expression and degradation were analyzed by real-time PCR and western blotting. The anti-cancer effect of balanophorin B in vivo was also investigated.

KEY FINDINGS

Balanophorin B inhibited the proliferation, glucose uptake, and ECAR in both HepG2 cells and Huh-7 cells. In addition, balanophorin B inhibited the protein level of HIF-1α and its downstream targets LDHA and HKII under hypoxia, whereas HIF-1α mRNA level did not change after balanophorin B treatment. The HIF-1α plasmid reversed the inhibition of balanophorin B on glycolysis, and the proteasome inhibitor MG132 attenuated the effect of balanophorin B on HIF-1α protein expression, suggesting that balanophorin B might post-transcriptionally affect HIF-1α. Moreover, balanophorin B increased the expression of VHL and PHD2. HIF-1α siRNA also greatly attenuated the inhibitory effect of balanophorin B on HepG2 cells glucose uptake. Balanophorin B significantly inhibited tumor growth in vivo, without causing obvious toxicity to mice.

SIGNIFICANCE

These data suggest that balanophorin B inhibits glycolysis probably via an HIF-1α-dependent pathway, and the ubiquitin-proteasome pathway was greatly involved in the induction of balanophorin B on HIF-1α degradation.

ANTs and cancer: Emerging pathogenesis, mechanisms, and perspectives

Adenine nucleotide translocases (ANTs) are a class of transporters located in the inner mitochondrial membrane that not only couple processes of cellular productivity and energy expenditure, but are also involved in the composition of the mitochondrial membrane permeability transition pore (mPTP). The function of ANTs has been found to be most closely related to their own conformational changes. Notably, as multifunctional proteins, ANTs play a key role in oncogenesis, which provides building blocks for tumor anabolism, control oxidative phosphorylation and glycolysis homeostasis, and govern cell death. Thus, ANTs constitute promising targets for the development of novel anticancer agents. Here, we review the recent findings regarding ANTs and their important mechanisms in cancer, with a focus on the therapeutic potential of targeting ANTs for cancer therapy.

MicroRNA-16-1-3p Represses Breast Tumor Growth and Metastasis by Inhibiting PGK1-Mediated Warburg Effect

The Warburg effect (aerobic glycolysis) is a hallmark of cancer and is becoming a promising target for diagnosis and therapy. Phosphoglycerate kinase 1 (PGK1) is the first adenosine triphosphate (ATP)-generating glycolytic enzyme in the aerobic glycolysis pathway and plays an important role in cancer development and progression. However, how microRNAs (miRNAs) regulate PGK1-mediated aerobic glycolysis remains unknown. Here, we show that miR-16-1-3p inhibits PGK1 expression by directly targeting its 3′-untranslated region. Through inhibition of PGK1, miR-16-1-3p suppressed aerobic glycolysis by decreasing glucose uptake, lactate and ATP production, and extracellular acidification rate, and increasing oxygen consumption rate in breast cancer cells. Aerobic glycolysis regulated by the miR-16-1-3p/PGK1 axis is critical for modulating breast cancer cell proliferation, migration, invasion and metastasis in vitro and in vivo. In breast cancer patients, miR-16-1-3p expression is negatively correlated with PGK1 expression and breast cancer lung metastasis. Our findings provide clues regarding the role of miR-16-1-3p as a tumor suppressor in breast cancer through PGK1 suppression. Targeting PGK1 through miR-16-1-3p could be a promising strategy for breast cancer therapy.

Lactate Dehydrogenase Inhibition With Oxamate Exerts Bone Anabolic Effect

Cellular bioenergetics is a promising new therapeutic target in aging, cancer, and diabetes because these pathologies are characterized by a shift from oxidative to glycolytic metabolism. We have previously reported such glycolytic shift in aged bone as a major contributor to bone loss in mice. We and others also showed the importance of oxidative phosphorylation (OxPhos) for osteoblast differentiation. It is therefore reasonable to propose that stimulation of OxPhos will have bone anabolic effect. One strategy widely used in cancer research to stimulate OxPhos is inhibition of glycolysis. In this work, we aimed to evaluate the safety and efficacy of pharmacological inhibition of glycolysis to stimulate OxPhos and promote osteoblast bone-forming function and bone anabolism. We tested a range of glycolytic inhibitors including 2-deoxyglucose, dichloroacetate, 3-bromopyruvate, and oxamate. Of all the studied inhibitors, only a lactate dehydrogenase (LDH) inhibitor, oxamate, did not show any toxicity in either undifferentiated osteoprogenitors or osteoinduced cells in vitro. Oxamate stimulated both OxPhos and osteoblast differentiation in osteoprogenitors. In vivo, oxamate improved bone mineral density, cortical bone architecture, and bone biomechanical strength in both young and aged C57BL/6J male mice. Oxamate also increased bone formation by osteoblasts without affecting bone resorption. In sum, our work provided a proof of concept for the use of anti-glycolytic strategies in bone and identified a small molecule LDH inhibitor, oxamate, as a safe and efficient bone anabolic agent. © 2020 American Society for Bone and Mineral Research (ASBMR).

Microfluidic Tumor-on-a-Chip Model to Study Tumor Metabolic Vulnerability

Tumor-specific metabolic adaptations offer an interesting therapeutic opportunity to selectively destroy cancer cells. However, solid tumors also present gradients of nutrients and waste products across the tumor mass, forcing tumor cells to adapt their metabolism depending on nutrient availability in the surrounding microenvironment. Thus, solid tumors display a heterogenous metabolic phenotype across the tumor mass, which complicates the design of effective therapies that target all the tumor populations present. In this work, we used a microfluidic device to study tumor metabolic vulnerability to several metabolic inhibitors. The microdevice included a central chamber to culture tumor cells in a three-dimensional (3D) matrix, and a lumen in one of the chamber flanks. This design created an asymmetric nutrient distribution across the central chamber, generating gradients of cell viability. The results revealed that tumor cells located in a nutrient-enriched environment showed low to no sensitivity to metabolic inhibitors targeting glycolysis, fatty acid oxidation, or oxidative phosphorylation. Conversely, when cell density inside of the model was increased, compromising nutrient supply, the addition of these metabolic inhibitors disrupted cellular redox balance and led to tumor cell death.

Cancer cell metabolism: Rewiring the mitochondrial hub

To adapt to tumoral environment conditions or even to escape chemotherapy, cells rapidly reprogram their metabolism to handle adversities and survive. Given the rapid rise of studies uncovering novel insights and therapeutic opportunities based on the role of mitochondria in tumor metabolic programing and therapeutics, this review summarizes most significant developments in the field. Taking in mind the key role of mitochondria on carcinogenesis and tumor progression due to their involvement on tumor plasticity, metabolic remodeling, and signaling re-wiring, those organelles are also potential therapeutic targets. Among other topics, we address the recent data intersecting mitochondria as of prognostic value and staging in cancer, by mitochondrial DNA (mtDNA) determination, and current inhibitors developments targeting mtDNA, OXPHOS machinery and metabolic pathways. We contribute for a holistic view of the role of mitochondria metabolism and directed therapeutics to understand tumor metabolism, to circumvent therapy resistance, and to control tumor development.

Lipid Regulatory Proteins as Potential Therapeutic Targets for Ovarian Cancer in Obese Women

Obesity has become a recognized global epidemic that is associated with numerous comorbidities including type II diabetes, cardiovascular disease, hypertension, and cancer incidence and progression. Ovarian cancer (OvCa) has a unique mechanism of intra-peritoneal metastasis, already present in 80% of women at the time of diagnosis, making it the fifth leading cause of death from gynecological malignancy. Meta-analyses showed that obesity increases the risk of OvCa progression, leads to enhanced overall and organ-specific tumor burden, and adversely effects survival of women with OvCa. Recent data discovered that tumors grown in mice fed on a western diet (40% fat) have elevated lipid levels and a highly increased expression level of sterol regulatory element binding protein 1 (SREBP1). SREBP1 is a master transcription factor that regulates de novo lipogenesis and lipid homeostasis, and induces lipogenic reprogramming of tumor cells. Elevated SREBP1 levels are linked to cancer cell proliferation and metastasis. This review will summarize recent findings to provide a current understanding of lipid regulatory proteins in the ovarian tumor microenvironment with emphasis on SREBP1 expression in the obese host, the role of SREBP1 in cancer progression and metastasis, and potential therapeutic targeting of SREBPs and SREBP-pathway genes in treating cancers, particularly in the context of host obesity.

Extracellular ATP: A Feasible Target for Cancer Therapy

Adenosine triphosphate (ATP) is one of the main biochemical components of the tumor microenvironment (TME), where it can promote tumor progression or tumor suppression depending on its concentration and on the specific ecto-nucleotidases and receptors expressed by immune and cancer cells. ATP can be released from cells via both specific and nonspecific pathways. A non-regulated release occurs from dying and damaged cells, whereas active release involves exocytotic granules, plasma membrane-derived microvesicles, specific ATP-binding cassette (ABC) transporters and membrane channels (connexin hemichannels, pannexin 1 (PANX1), calcium homeostasis modulator 1 (CALHM1), volume-regulated anion channels (VRACs) and maxi-anion channels (MACs)). Extracellular ATP acts at P2 purinergic receptors, among which P2X7R is a key mediator of the final ATP-dependent biological effects. Over the years, P2 receptor- or ecto-nucleotidase-targeting for cancer therapy has been proposed and actively investigated, while comparatively fewer studies have explored the suitability of TME ATP as a target. In this review, we briefly summarize the available evidence suggesting that TME ATP has a central role in determining tumor fate and is, therefore, a suitable target for cancer therapy.

Dithiolation indolizine exerts viability suppression effects on A549 cells via triggering intrinsic apoptotic pathways and inducing G2/M phase arrest

Indolizine derivatives have been reported for the treatment of numerous diseases. However, few studies were carried out for non-small cell lung cancer (NSCLC). We synthesized series of indolizine compounds. The results of MTT assay showed compound 8 (C8) markedly inhibited the proliferation of A549 cells, however, C8 (15, 30 μg/mL) had little cytotoxicity in other cell lines (SH-SY5Y, HepG2, and BEAS-2B cells), Hoechst staining and JC-1 staining showed that C8 induced changes in the nucleus morphology, increased the loss in mitochondrial membrane potential in A549 cells. The results of flow cytometry manifested that cell cycle of the cells was arrested in the G2 / M phase by C8, ROS levels and the proportion of apoptosis of cells increased. We performed western blotting analysis to detect the expression levels of apoptosis and cycle-related proteins. These results validated that the apoptosis of cells was triggered by endoplasmic reticulum stress (ERS) and the PI3K/Akt-mediated mitochondrial pathway collaboratively. Besides, the utilization of PI3K/Akt inhibitors and p53 inhibitors further proves the above argument and C8-induced cycle arrest of A549 cells is majorly regulated by p53. C8 induced the accumulation of ROS contents involved in mitochondrial damage. The proliferation of A549 cells was inhibited after treatment with the compound, which induced apoptosis and cycle arrest of cells. It is suggested that C8(dithiolation indolizine) is a potential candidate compound against non-small cell lung cancer.

Cytochrome P450 1A2 overcomes nuclear factor kappa B-mediated sorafenib resistance in hepatocellular carcinoma

Sorafenib resistance has become the main obstacle in the effective treatment of advanced hepatocellular carcinoma (HCC) patients. Activation of nuclear factor kappa B (NF-κB) is a newly identified mechanism that contributes to desensitized sorafenib. Cytochrome P450 1A2 (CYP1A2) functions as a tumor suppressor in HCC and its expression is negatively associated with NF-κB in the liver. This study aimed to study whether CYP1A2 could overcome sorafenib resistance. To investigate whether CYP1A2 and NF-κB p65 played roles in sorafenib desensitization, we established sorafenib-resistant (SR) HCC cells. SR cells decreased the expression of CYP1A2 along with the upregulation of NF-κB p65. CYP1A2 overexpression attenuated SR cell proliferation, increased sorafenib sensitivity, and inhibited the NF-κB pathway, whereas CYP1A2 silence showed opposite effects. Sorafenib, in combination with omeprazole, a CYP1A2 inducer, significantly hindered the growth and invasion of SR cells in vitro as well as decreased the tumor growth in vivo. The combination treatment markedly increased CYP1A2 expression and inhibited the sorafenib-induced NF-κB signaling. In addition, the overexpression of NF-κB p65 stimulated the SR cell growth and desensitized sorafenib in SR cells, where CYP1A2 overexpression reversed the phenomenon. Lastly, the majority of HCC tissue samples displayed decreased CYP1A2 but increased NF-κB p65 protein expression. Collectively, CYP1A2 can sensitize SR cells to sorafenib via inhibiting NF-κB p65 axis. Omeprazole in combination with sorafenib exerts a synergistic effect in alleviating acquired sorafenib resistance.

Metformin inhibits epithelial-mesenchymal transition of oral squamous cell carcinoma via the mTOR/HIF-1α/PKM2/STAT3 pathway

Epithelial-mesenchymal transition (EMT) serves an important role in the formation and development of various types of cancer, including oral squamous cell carcinoma (OSCC). Metformin, used for treating type 2 diabetes, has been revealed to exert an anticancer effect in various types of cancer, including liver, breast and colorectal cancer. However, its role in the EMT of OSCC has been rarely reported. Therefore, the present study aimed to investigate the effects of metformin on EMT and to identify its underlying mechanism in OSCC. Firstly, EMT was induced in CAL-27 cells using CoCl₂. Subsequently, the effects of metformin on cell viability, migration and xenograft growth were evaluated in vitro and in vivo. Reverse transcription-quantitative PCR was performed to detect the expression levels of E-cadherin, vimentin, snail family transcriptional repressor 1, mTOR, hypoxia inducible factor 1α, pyruvate kinase M2 and STAT3. The results demonstrated that metformin abolished CoCl₂-induced cell proliferation, migration, invasion and EMT. Moreover, metformin reversed EMT in OSCC by inhibiting the mTOR-associated HIF-1α/PKM2/STAT3 signaling pathway. Overall, the present findings characterized a novel mechanism via which metformin modulated EMT in OSCC.

Long Noncoding RNA LINC00551 Suppresses Glycolysis and Tumor Progression by Regulating c-Myc-Mediated PKM2 Expression in Lung Adenocarcinoma

Background

Lung adenocarcinoma (LUAD) is a leading cause of mortality associated with cancer globally. Thus, it is essential to elucidate its tumorigenesis and prognosis. Accumulating evidence shows that long noncoding RNAs (lncRNAs) play important roles in the occurrence and progression of tumors by regulating their glucose metabolism.

Methods

Bioinformatics analysis was performed to explore the expression of LINC00551 in LUAD. The level of LINC00551 in LUAD cells and tissues was detected by RT-qPCR. CCK-8, colony formation, EDU and transwell assays were conducted to evaluate the cell growth and migration of LUAD cells (A549 and PC9). High throughput sequencing was used to discover the downstream genes of LINC00551. The metabolic function of LUAD cells was identified by glucose uptake and lactate production assays. Furthermore, tumor xenografts were established to investigate the effects of LINC00551 on tumor growth in vivo.

Results

Herein, we found that LINC00551 was low-expressed in LUAD, and its level correlated with clinical prognosis. Ectopic expression of LINC00551 inhibited the proliferation and migration of LUAD cells (A549 and PC9). High throughput sequencing and gene enrichment analysis revealed that LINC0551 may be involved in metabolic pathway. Glucose uptake and lactate production assays suggested that LINC00551 suppressed glycolysis of LUAD cells. Mechanistically, our work revealed that LINC00551 inhibited glycolysis in LUAD cells by impairing c-Myc-mediated transcription of an important glycolysis-related enzyme PKM2.

Conclusion

In summary, our study identifies LINC00551 as a tumor suppressor in LUAD and implicates the LINC00551/c-Myc/PKM2 axis in the glycolytic remodeling of LUAD.

Circular RNA circSEMA5A promotes bladder cancer progression by upregulating ENO1 and SEMA5A expression

Bladder cancer (BC) is one of the most commonly diagnosed urologic carcinomas, with high recurrence and death rates. Circular RNAs (circRNAs) are a class of noncoding RNAs which are anomalously expressed in cancers and involved in the progression of cancers. In this study, we found that circSEMA5A was upregulated in BC tissues and cell lines. The overexpressed circSEMA5A was correlated with malignant characteristics of BC. In vitro data indicated that circSEMA5A promoted proliferation, suppressed apoptosis, facilitated migration, accelerated invasion, enhanced angiogenesis and promotes glycolysis of BC. Mechanistically, circSEMA5A served as a miRNA sponge for miR-330-5p to upregulates Enolase 1 (ENO1) expression and facilitated the activation of Akt and β-catenin signaling pathways. Then, we showed that circSEMA5A exerted its biological functions partially via miR-330-5p/ENO1 signaling. Moreover, circSEMA5A raised SEMA5A expression by recruiting EIF4A3 to enhance the mRNA stability of SEMA5A, and thereby accelerated BC angiogenesis. To sum up, circSEMA5A is upregulated in BC and facilitates BC progression by mediating miR-330-5p/ENO1 signaling and upregulating SEMA5A expression.

Glycolytic competence in gastric adenocarcinomas negatively impacts survival outcomes of patients treated with salvage paclitaxel-ramucirumab

INTRODUCTION

For energy production, cancer cells maintain a high rate of glycolysis instead of oxidative phosphorylation converting glucose into lactic acid. This metabolic shift is useful to survive in unfavorable microenvironments. We investigated whether a positive glycolytic profile (PGP) in gastric adenocarcinomas may be associated with unfavorable outcomes under an anticancer systemic therapy, including the anti-angiogenic ramucirumab.

MATERIALS AND METHODS

Normal mucosa (NM) and primary tumor (PT) of 40 metastatic gastric adenocarcinomas patients who received second-line paclitaxel-ramucirumab (PR) were analyzed for mRNA expression of the following genes: HK-1, HK-2, PKM-2, LDH-A, and GLUT-1. Patients were categorized with PGP when at least a doubling of mRNA expression (PT vs. NM) in all glycolytic core enzymes (HK-1 or HK-2, PKM-2, LDH-A) was observed. PGP was also related to TP53 mutational status.

RESULTS

Mean LDH-A, HK-2, PKM-2 mRNA expression levels were significantly higher in PT compared with NM. 18 patients were classified as PGP, which was associated with significantly worse progression-free and overall survival times. No significant association was observed between PGP and clinical-pathologic features, including TP53 positive mutational status, in 28 samples.

CONCLUSIONS

Glycolytic proficiency may negatively affect survival outcomes of metastatic gastric cancer patients treated with PR systemic therapy. TP53 mutational status alone does not seem to explain such a metabolic shift.

STIP1 down-regulation inhibits glycolysis by suppressing PKM2 and LDHA and inactivating the Wnt/β-catenin pathway in cervical carcinoma cells

AIMS

Glycolysis is an important process for cervical carcinoma development. Previous studies have indicated that stress-induced phosphoprotein 1 (STIP1) is associated with development of multiple tumors. Nevertheless, the role and mechanism of STIP1 in glycolysis of cervical carcinoma remain unclear.

MAIN METHODS

The association between STIP1 and survival probability and the correlation between STIP1 expression and pyruvate kinase M2 (PKM2) as well as lactate dehydrogenase isoform A (LDHA) levels in cervical carcinoma were analyzed via The Cancer Genome Atlas (TCGA). The expression of STIP1, PKM2, LDHA, and cytochrome c (Cyt C) was measured via western blot or quantitative reverse transcription polymerase chain reaction. Cell viability and apoptosis were examined via cell counting kit 8 and flow cytometry, respectively. Glycolysis was assessed via detection of glucose consumption and lactate production. The protein involved in the Wnt/β-catenin pathway was measured via western blot.

KEY FINDINGS

STIP1 abundance was elevated in cervical carcinoma cells. High expression of STIP1 indicated poor survival probability. Knockdown of STIP1 inhibited cervical carcinoma cell viability and promoted apoptosis. STIP1 expression was positively correlated with PKM2 and LDHA levels in cervical carcinoma. Silence of STIP1 inhibited glycolysis and decreased PKM2 and LDHA expression. Down-regulation of STIP1 repressed the Wnt/β-catenin pathway. Overexpression of β-catenin reversed the effect of STIP1 silence on viability, apoptosis, glycolysis, and levels of PKM2 and LDHA.

SIGNIFICANCE

STIP1 knockdown suppressed glycolysis in cervical carcinoma by inhibiting PKM2 and LDHA expression and activation of the Wnt/β-catenin pathway.

The not-so-sweet side of sugar: Influence of the microenvironment on the processes that unleash cancer

The role of "aerobic glycolysis" in cancer has been examined often in the past. Results from those studies, most of which were performed on two dimensional conditions (2D, tissue culture plastic), demonstrate that aerobic glycolysis occurs as a consequence of oncogenic events. These oncogenic events often drive malignant cell growth and survival. Although 2D based experiments are useful in elucidating the molecular mechanisms of oncogenesis, they fail to take contributions of the extracellular microenvironment into account. Indeed we, and others, have shown that the cellular microenvironment is essential in regulating processes that induce and/or suppress the malignant phenotype/properties. This regulation between the cell and its microenvironment is both dynamic and reciprocal and involves the integration of cellular signaling networks in the right context. Therefore, given our previous demonstration of the effect of the microenvironment including tissue architecture and media composition on gene expression and the integration of signaling events observed in three-dimension (3D), we hypothesized that glucose uptake and metabolism must also be essential components of the tissue's signal "integration plan" - that is, if uptake and metabolism of glucose were hyperactivated, the canonical oncogenic pathways should also be similarly activated. This hypothesis, if proven true, suggests that direct inhibition of glucose metabolism in cancer cells should either suppress or revert the malignant phenotype in 3D. Here, we review the up-to-date progress that has been made towards understanding the role that glucose metabolism plays in oncogenesis and re-establishing basally polarized acini in malignant human breast cells.

Hypoxia-inducible hexokinase-2 enhances anti-apoptotic function via activating autophagy in multiple myeloma

Multiple myeloma (MM) is an incurable hematopoietic neoplasm derived from plasma cells, and existing in the bone marrow. Recent developments in the field of myeloma onco-biology have enabled the use of proteasome inhibitors (PIs) as key drugs for MM. PIs can increase cell sensitivity to endoplasmic reticulum stress, leading to apoptosis of myeloma cells. PI cannot kill all myeloma cells, however; one reason of this might be activation of autophagy via hypoxic stress in the bone marrow microenvironment. Hypoxia-inducible gene(s) that regulate autophagy may be novel therapeutic target(s) for PI-resistant myeloma cells. Here, a hypoxia-inducible glycolytic enzyme hexokinase-2 (HK2) was demonstrated to contribute by autophagy activation to the acquisition of an anti-apoptotic phenotype in myeloma cells. We found that hypoxic stress led to autophagy activation accompanied by HK2 upregulation in myeloma cells. Under hypoxic conditions, HK2 knockdown inhibited glycolysis and impaired autophagy, inducing apoptosis. The cooperative effects of a PI (bortezomib) against immunodeficient mice inoculated with HK2-knocked down myeloma cells were examined and significant tumor reduction was observed. An HK2 inhibitor, 3-bromopyruvate (3-BrPA), also induced apoptosis under hypoxic rather than normoxic conditions. Further examination of the cooperative effects between 3-BrPA and bortezomib on myeloma cells revealed a significant increase in apoptotic myeloma cells. These results strongly suggested that HK2 regulates the activation of autophagy in hypoxic myeloma cells. Cooperative treatment using PI against a dominant fraction, and HK2 inhibitor against a minor fraction, adapted to the bone marrow microenvironment, may lead to deeper remission for refractory MM.

Alteration of plasma metabolites associated with chemoradiosensitivity in esophageal squamous cell carcinoma via untargeted metabolomics approach

BACKGROUND

To investigate the differences in plasma metabolomic characteristics between pathological complete response (pCR) and non-pCR patients and identify biomarker candidates for predicting the response to neoadjuvant chemoradiotherapy (nCRT) in esophageal squamous cell carcinoma (ESCC).

METHODS

A total of 46 ESCC patients were included in this study. Gas chromatography time-of- flight mass spectrometry (GC-TOF/MS) technology was applied to detect the plasma samples collected before nCRT via untargeted metabolomics analysis.

RESULTS

Five differentially expressed metabolites (out of 109) was found in plasma between pCR and non-pCR groups. Compared with non-pCR group, isocitric acid (p = 0.0129), linoleic acid (p = 0.0137), citric acid (p = 0.0473) were upregulated, while L-histidine (p = 0.0155), 3'4 dihydroxyhydrocinnamic acid (p = 0.0339) were downregulated in the pCR plasma samples. Pathway analyses unveiled that citrate cycle (TCA cycle), glyoxylate and dicarboxylate metabolic pathway were associated with ESCC chemoradiosensitivity.

CONCLUSION

The present study provided supporting evidence that GC-TOF/MS based metabolomics approach allowed identification of metabolite differences between pCR and non-pCR patients in plasma levels, and the systemic metabolic status of patients may reflect the response of ESCC patient to neoadjuvant chemoradiotherapy.

Hypoxia Predicts Poor Prognosis in Neuroblastoma Patients and Associates with Biological Mechanisms Involved in Telomerase Activation and Tumor Microenvironment Reprogramming

The biological and clinical heterogeneity of neuroblastoma (NB) demands novel biomarkers and therapeutic targets in order to drive the most appropriate treatment for each patient. Hypoxia is a condition of low-oxygen tension occurring in poorly vascularized tumor tissues. In this study, we aimed to assess the role of hypoxia in the pathogenesis of NB and at developing a new clinically relevant hypoxia-based predictor of outcome. We analyzed the gene expression profiles of 1882 untreated NB primary tumors collected at diagnosis and belonging to four existing data sets. Analyses took advantage of machine learning methods. We identified NB-hop, a seven-gene hypoxia biomarker, as a predictor of NB patient prognosis, which is able to discriminate between two populations of patients with unfavorable or favorable outcome on a molecular basis. NB-hop retained its prognostic value in a multivariate model adjusted for established risk factors and was able to additionally stratify clinically relevant groups of patients. Tumors with an unfavorable NB-hop expression showed a significant association with telomerase activation and a hypoxic, immunosuppressive, poorly differentiated, and apoptosis-resistant tumor microenvironment. NB-hop defines a new population of NB patients with hypoxic tumors and unfavorable prognosis and it represents a critical factor for the stratification and treatment of NB patients.

ROS-Mediated Therapeutic Strategy in Chemo-/Radiotherapy of Head and Neck Cancer

Head and neck cancer is a highly genetic and metabolic heterogeneous collection of malignancies of the lip, oral cavity, salivary glands, pharynx, esophagus, paranasal sinuses, and larynx with five-year survival rates ranging from 12% to 93%. Patients with head and neck cancer typically present with advanced stage III, IVa, or IVb disease and are treated with comprehensive modality including chemotherapy, radiotherapy, and surgery. Despite advancements in treatment modality and technique, noisome recurrence, invasiveness, and resistance as well as posttreatment complications severely influence survival rate and quality of life. Thus, new therapeutic strategies are urgently needed that offer enhanced efficacy with less toxicity. ROS in cancer cells plays a vital role in regulating cell death, DNA repair, stemness maintenance, metabolic reprogramming, and tumor microenvironment, all of which have been implicated in resistance to chemo-/radiotherapy of head and neck cancer. Adjusting ROS generation and elimination to reverse the resistance of cancer cells without impairing normal cells show great hope in improving the therapeutic efficacy of chemo-/radiotherapy of head and neck cancer. In the current review, we discuss the pivotal and targetable redox-regulating system including superoxide dismutases (SODs), tripeptide glutathione (GSH), thioredoxin (Trxs), peroxiredoxins (PRXs), nuclear factor erythroid 2-related factor 2/Kelch-like ECH-associated protein 1 (Nrf2/keap1), and mitochondria electron transporter chain (ETC) complexes and their roles in regulating ROS levels and their clinical significance implicated in chemo-/radiotherapy of head and neck cancer. We also summarize several old drugs (referred to as the non-anti-cancer drugs used in other diseases for a long time) and small molecular compounds as well as natural herbs which effectively modulate cellular ROS of head and neck cancer to synergize the efficacy of conventional chemo-/radiotherapy. Emerging interdisciplinary techniques including photodynamic, nanoparticle system, and Bio-Electro-Magnetic-Energy-Regulation (BEMER) therapy are promising measures to broaden the potency of ROS modulation for the benefit of chemo-/radiotherapy in head and neck cancer.

Harnessing nanomedicine to overcome the immunosuppressive tumor microenvironment

Cancer immunotherapy has received extensive attention due to its ability to activate the innate or adaptive immune systems of patients to combat tumors. Despite a few clinical successes, further endeavors are still needed to tackle unresolved issues, including limited response rates, development of resistance, and immune-related toxicities. Accumulating evidence has pinpointed the tumor microenvironment (TME) as one of the major obstacles in cancer immunotherapy due to its detrimental impacts on tumor-infiltrating immune cells. Nanomedicine has been battling with the TME in the past several decades, and the experience obtained could be exploited to improve current paradigms of immunotherapy. Here, we discuss the metabolic features of the TME and its influence on different types of immune cells. The recent progress in nanoenabled cancer immunotherapy has been summarized with a highlight on the modulation of immune cells, tumor stroma, cytokines and enzymes to reverse the immunosuppressive TME.

Identification of a competing endogenous RNA network associated with prognosis of pancreatic adenocarcinoma

Background

Emerging evidence suggests that competing endogenous RNAs plays a crucial role in the development and progress of pancreatic adenocarcinoma (PAAD). The objective was to identify a new lncRNA-miRNA-mRNA network as prognostic markers, and develop and validate a multi-mRNAs-based classifier for predicting overall survival (OS) in PAAD.

Methods

Data on pancreatic RNA expression and clinical information of 445 PAAD patients and 328 normal subjects were downloaded from The Cancer Genome Atlas (TCGA), International Cancer Genome Consortium (ICGC) and Genotype-Tissue Expression (GTEx). The weighted correlation network analysis (WGCNA) was used to analyze long non-coding RNA (lncRNA) and mRNA, clustering genes with similar expression patterns. MiRcode was used to predict the sponge microRNAs (miRNAs) corresponding to lncRNAs. The downstream targeted mRNAs of miRNAs were identified by starBase, miRDB, miRTarBase and Targetscan. A multi-mRNAs-based classifier was develop using least absolute shrinkage and selection operator method (LASSO) COX regression model, which was tested in an independent validation cohort.

Results

A lncRNA-miRNA-mRNA co-expression network which consisted of 60 lncRNAs, 3 miRNAs and 3 mRNAs associated with the prognosis of patients with PAAD was established. In addition, we constructed a 14-mRNAs-based classifier based on a training cohort composed of 178 PAAD patients, of which the area under receiver operating characteristic (AUC) in predicting 1-year, 3-year, and 5-year OS was 0.719, 0.806 and 0.794, respectively. The classifier also shown good prediction function in independent verification cohorts, with the AUC of 0.604, 0.639 and 0.607, respectively.

Conclusions

A novel competitive endogenous RNA (ceRNA) network associated with progression of PAAD could be used as a reference for future molecular biology research.

Effect of low dose of berberine on the radioresistance of cervical cancer cells via a PI3K/HIF-1 pathway under nutrient-deprived conditions

Purpose: Radiotherapy (RT) is one of the major treatments of cervical cancer. Although the prognosis of clinical cervical cancer becomes better in recent years, some patients still suffer from the recurrence and metastasis. Insufficiency of glucose and oxygen supply could increase the radioresistance of cervical cancer cells through regulating hypoxia-inducible factor 1 (HIF-1) in tumor microenvironment and glucose metabolism. And, berberine can regulate HIF-1. However, how berberine regulates tumor microenvironment and radioresistance through HIF-1 remains to be elucidated.Materials and methods: The human HeLa cervical cancer cells were treated with berberine and radiation under the high and low concentrations of glucose and oxygen, respectively. The survival of cells was tested by CCK-8 assay and colony formation assay. We investigated the PI3K- and IDH3α-related pathway molecules that may regulate HIF-1α by qPCR and western blot. Differentially expressed genes (DEGs) were identified by integrating five related cohort profile datasets. Protein-protein interaction (PPI) network analyses of DEGs related to HIF-1α were conducted by using the STRING database and Cytoscape software.Results: Berberine dramatically damaged HeLa cells under hypoxic and low-glucose conditions compared with the normoxic and high-glucose conditions. The clonogenic assay indicated that the application of berberine decreased the number of colony counts compared to the negative control. Low doses of berberine might decrease the level of phospho-PI3K and HIF-1α under the nutrient-deprived conditions. Moreover, we found that most of the differentially expressed genes which were related to CDKN1B were the downstream molecules regulated by HIF-1α.Conclusion: The results indicated that berberine could dramatically overcome the low-glucose and hypoxia-induced radioresistance. And the regulation berberine on nutrition-deficient conditions might involve in PI3K/HIF-1 pathway. Thus, the interference of glucose metabolism by berberine might be an attractive method to eliminate radioresistant cells and improve radiotherapy efficacy.

Connexin 30 mediated rewiring of glucose metabolism in rat C6 xenograft and grades of glioma

Connexin 30 (Cx30), a tumour-suppressive gap junctional protein, impacts on insulin-like growth factor receptor 1-mediated progression and stemness of glioma. Of late, metabolic reprogramming, a recently adjudged hall mark of malignancy, could reasonably associated with the changes in gap junctional communication in glioma. This newly recognized hallmark of reprogramming of metabolism to maintain the rapid proliferation necessitates further probing to establish the stronger hall marks. Hence, the current study attempted to link the association between the expression of Cx30 with glucose uptake and glucose metabolism in glioma. We have transfected Cx30 in C6 glioma cells, characterized by a low level of intercellular communication and developed xenografts to study the status of glucose transporters (GLUTs), hexokinase 2 and Pyruvate dehydrogenase kinase 1 (PDK 1) along with human glioma tissues by RT-PCR and immunoblotting. The results showed a significant increase in the levels of GLUTs, hexokinase 2 and PDK 1 in C6-implanted rat xenografts and high grades compared to their respective controls, whereas Cx30-transfected C6-implanted rat xenograft and low grades show no significant change compared to that of controls supporting the association between Gap junctional communications and glucose metabolism. We strongly speculate the impact of Cx30 over the glucose metabolism that might provide therapeutic prospects and challenges for anti-glycolytic cancer therapy.

Targeting Cellular Metabolism in Acute Myeloid Leukemia and The Role of Patient Heterogeneity

Acute myeloid leukemia (AML) is an aggressive blood cancer resulting in accumulation of immature, dysfunctional blood cells in the bone marrow. Changes in cell metabolism are features of many cancers, including AML and this may be exploited as a therapeutic target. In this study we investigated the in vitro antileukemic effects of seven metabolic inhibitors that target different metabolic pathways. The metabolic inhibitors were tested on AML cells derived from 81 patients using proliferation and viability assays; we also compared global gene expression and proteomic profiles for various patient subsets. Metformin, 2DG, 6AN, BPTES and ST1326 had strong antiproliferative and proapoptotic effects for most patients, whereas lonidamine and AZD3965 had an effect only for a minority. Antiproliferative effects on AML cells were additive when combined with the chemotherapeutic agent AraC. Using unsupervised hierarchical clustering, we identified a strong antiproliferative effect on AML cells after treatment with metabolic inhibitors for a subset of 29 patients. Gene expression and proteomic studies suggested that this subset was characterized by altered metabolic and transcriptional regulation. In addition, the Bcl-2 inhibitor venetoclax, in combination with 2DG or 6AN, increased the antiproliferative effects of these metabolic inhibitors on AML cells. Therapeutic targeting of cellular metabolism may have potential in AML, but the optimal strategy will likely differ between patients.

Metabolic alterations in the tumor microenvironment and their role in oncogenesis

Metabolic reprogramming is a characteristic feature of both cancer cells and their neighbouring cells in the tumor microenvironment (TME). The latter include stroma fibroblasts and adipocytes, that respectively differentiate to become cancer associated fibroblasts (CAFs) and cancer associated adipocytes (CAAs), and infiltrated immune cells, that collaborate with the stromal cells to provide the tumor a pro-tumorigenic niche. Here we discuss the association between the reprogramming of glucose metabolism in the TME and oncogenic signaling and its reflection in the non-canonical functions of metabolic enzymes. We also discuss the non-canonical actions of oncometabolites and the contribution to oncogenesis of external metabolites that accumulate in the TME as result of crosstalk between the tumor and the TME. Special emphasis is given in this regard to lysophosphatidic acid (LPA) and adenosine, two powerful metabolites, the concentrations of which rise in the TME due to altered metabolism of the tumor and its surrounding cells, allowing their action as external signals.

Targeting putative components of the mitochondrial permeability transition pore for novel therapeutics

Few discoveries have influenced drug discovery programs more than the finding that mitochondrial membranes undergo swings in permeability in response to cellular perturbations. The conductor of these permeability changes is the aptly named mitochondrial permeability transition pore which, although not yet precisely defined, is comprised of several integral proteins that differentially act to regulate the flux of ions, proteins and metabolic byproducts during the course of cellular physiological functions but also pathophysiological insults. Pursuit of the pore's exact identity remains a topic of keen interest, but decades of research have unearthed provocative functions for the integral proteins leading to their evaluation to develop novel therapeutics for a wide range of clinical indications. Chief amongst these targeted, integral proteins have been the Voltage Dependent Anion Channel (VDAC) and the F₁F_O ATP synthase. Research associated with the roles and ligands of VDAC has been extensive and we will expand upon 3 examples of ligand:VDAC interactions for consideration of drug discovery projects: Tubulin:VDAC1, Hexokinase I/II:VDAC1 and olesoxime:VDAC1. The discoveries that cyclosporine blocks mitochondrial permeability transition via binding to cyclophilin D, and that cyclophilin D is an important component of F₁F_O ATP synthase, has heightened interest in the F₁F_O ATP synthase as a focal point for drug discovery, and we will discuss 2 plausible campaigns associated with disease indications. To date no drug has emerged from prospective targeting these integral proteins; however, continued exploration such as the approaches suggested in this Commentary will increase the likelihood of providing important therapeutics for severely unmet medical needs.

Identification Six Metabolic Genes as Potential Biomarkers for Lung Adenocarcinoma

Metabolic genes have been reported to act as crucial roles in tumor progression. Lung adenocarcinoma (LUAD) is one of the most common cancers worldwide. This study aimed to predict the potential mechanism and novel markers of metabolic signature in LUAD. The gene expression profiles and the clinical parameters were obtained from The Cancer Genome Atlas-Lung adenocarcinoma (TCGA-LUAD) and Gene Expression Omnibus data set (GSE72094). A total of 105 differentially expressed metabolic genes of intersect expression in TCGA-LUAD and GSE72094 were screened by R language. Univariate Cox regression model found 18 survival-related genes and then the least absolute shrinkage and selection operator model was successfully constructed. Six significant genes prognostic model was validated though independent prognosis analysis. The model revealed high values for prognostic biomarkers by time-dependent receiver operating characteristic (ROC) analysis, risk score, Heatmap, and nomogram. In addition, Gene Set Enrichment Analysis showed that multiplex metabolism pathways correlated with LUAD. Furthermore, we found the six genes aberrantly expressed in LUAD samples. Our study showed that metabolism pathways play important roles in LUAD progression. The six metabolic genes could predict potential prognostic and diagnostic biomarkers in LUAD.

EMT Factors and Metabolic Pathways in Cancer

The epithelial-mesenchymal transition (EMT) represents a biological program during which epithelial cells lose their cell identity and acquire a mesenchymal phenotype. EMT is normally observed during organismal development, wound healing and tissue fibrosis. However, this process can be hijacked by cancer cells and is often associated with resistance to apoptosis, acquisition of tissue invasiveness, cancer stem cell characteristics, and cancer treatment resistance. It is becoming evident that EMT is a complex, multifactorial spectrum, often involving episodic, transient or partial events. Multiple factors have been causally implicated in EMT including transcription factors (e.g., SNAIL, TWIST, ZEB), epigenetic modifications, microRNAs (e.g., miR-200 family) and more recently, long non-coding RNAs. However, the relevance of metabolic pathways in EMT is only recently being recognized. Importantly, alterations in key metabolic pathways affect cancer development and progression. In this review, we report the roles of key EMT factors and describe their interactions and interconnectedness. We introduce metabolic pathways that are involved in EMT, including glycolysis, the TCA cycle, lipid and amino acid metabolism, and characterize the relationship between EMT factors and cancer metabolism. Finally, we present therapeutic opportunities involving EMT, with particular focus on cancer metabolic pathways.

Dual inhibition of glycolysis and autophagy as a therapeutic strategy in the treatment of Ehrlich ascites carcinoma

Cancer cells have extra biosynthetic demands to sustain cell growth and redox homeostasis. Glycolysis and autophagy are crucial to fuel and recycle these biosynthetic demands. This plasticity of cancer cell metabolism participates in therapy resistances. The current study was designed to assess the therapeutic efficacy of dual targeting of glycolysis and autophagy in cancer. Using 3-bromopyruvate (3-BP; antiglycolytic inhibitor) and hydroxychloroquine (HCQ; autophagy inhibitor), we demonstrate their antitumor activity in Ehrlich ascites carcinoma (EAC)-bearing mice. A combination of 3-BP and HCQ significantly decreases tumor ascitic volume and cell count as compared with the EAC group and individual treatment groups. The enhanced antitumor activity is accompanied by hexokinase inactivation, inhibition of cellular protective autophagy, elevated antioxidant activity, and reduced oxidative stress levels. Together, these results suggest targeting both pathways in cancer as an effective therapeutic strategy. Further studies are required to validate this strategy in different cancer models and preclinical trials.

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.

Loss of Rb1 Enhances Glycolytic Metabolism in Kras-Driven Lung Tumors In Vivo

Dysregulated metabolism is a hallmark of cancer cells and is driven in part by specific genetic alterations in various oncogenes or tumor suppressors. The retinoblastoma protein (pRb) is a tumor suppressor that canonically regulates cell cycle progression; however, recent studies have highlighted a functional role for pRb in controlling cellular metabolism. Here, we report that loss of the gene encoding pRb (Rb1) in a transgenic mutant Kras-driven model of lung cancer results in metabolic reprogramming. Our tracer studies using bolus dosing of [U-¹³C]-glucose revealed an increase in glucose carbon incorporation into select glycolytic intermediates. Consistent with this result, Rb1-depleted tumors exhibited increased expression of key glycolytic enzymes. Interestingly, loss of Rb1 did not alter mitochondrial pyruvate oxidation compared to lung tumors with intact Rb1. Additional tracer studies using [U-¹³C,¹⁵N]-glutamine and [U-¹³C]-lactate demonstrated that loss of Rb1 did not alter glutaminolysis or utilization of circulating lactate within the tricarboxylic acid cycle (TCA) in vivo. Taken together, these data suggest that the loss of Rb1 promotes a glycolytic phenotype, while not altering pyruvate oxidative metabolism or glutamine anaplerosis in Kras-driven lung tumors.

Targeting Glucose Transporters for Breast Cancer Therapy: The Effect of Natural and Synthetic Compounds

Reprogramming of cellular energy metabolism is widely accepted to be a cancer hallmark. The deviant energetic metabolism of cancer cells-known as the Warburg effect-consists in much higher rates of glucose uptake and glycolytic oxidation coupled with the production of lactic acid, even in the presence of oxygen. Consequently, cancer cells have higher glucose needs and thus display a higher sensitivity to glucose deprivation-induced death than normal cells. So, inhibitors of glucose uptake are potential therapeutic targets in cancer. Breast cancer is the most commonly diagnosed cancer and a leading cause of cancer death in women worldwide. Overexpression of facilitative glucose transporters (GLUT), mainly GLUT1, in breast cancer cells is firmly established, and the consequences of GLUT inhibition and/or knockout are under investigation. Herein we review the compounds, both of natural and synthetic origin, found to interfere with uptake of glucose by breast cancer cells, and the consequences of interference with that mechanism on breast cancer cell biology. We will also present data where the interaction with GLUT is exploited in order to increase the efficiency or selectivity of anticancer agents, in breast cancer cells.