2-Deoxy-d-glucose Suppresses the In Vivo Antitumor Efficacy of Erlotinib in Head and Neck Squamous Cell Carcinoma Cells

2-Deoxy-D-glucose simultaneously targets glycolysis and Wnt/β-catenin signaling to inhibit cervical cancer progression

Cervical cancer is one of the most common female malignant tumors, with typical cancer metabolism characteristics of increased glycolysis flux and lactate accumulation. 2-Deoxy-D-glucose (2-DG) is a glycolysis inhibitor that acts on hexokinase, the first rate-limiting enzyme in the glycolysis pathway. In this research, we demonstrated that 2-DG effectively reduced glycolysis and impaired mitochondrial function in cervical cancer cell lines HeLa and SiHa. Cell function experiments revealed that 2-DG significantly inhibited cell growth, migration, and invasion, and induced G0/G1 phase arrest at non-cytotoxic concentrations. In addition, we found that 2-DG down-regulated Wingless-type (Wnt)/β-catenin signaling. Mechanistically, 2-DG accelerated the degradation of β-catenin protein, which resulted in the decrease of β-catenin expression in both nucleus and cytoplasm. The Wnt agonist lithium chloride and β-catenin overexpression vector could partially reverse the inhibition of malignant phenotype by 2-DG. These data suggested that 2-DG exerted its anti-cancer effects on cervical cancer by co-targeting glycolysis and Wnt/β-catenin signaling. As expected, the combination of 2-DG and Wnt inhibitor synergistically inhibited cell growth. It is noteworthy that, down-regulation of Wnt/β-catenin signaling also inhibited glycolysis, indicating a similar positive feedback regulation between glycolysis and Wnt/β-catenin signaling. In conclusion, we investigated the molecular mechanism by which 2-DG inhibits the progression of cervical cancer in vitro, elucidated the interregulation between glycolysis and Wnt/β-catenin signaling, and preliminarily explored the effect of combined targeting of glycolysis and Wnt/β-catenin signaling on cell proliferation, which provides more possibilities for the formulation of subsequent clinical treatment strategies.

Targeting Mitochondrial Metabolism to Reverse Radioresistance: An Alternative to Glucose Metabolism

Radiotherapy failure and poor tumor prognosis are primarily attributed to radioresistance. Improving the curative effect of radiotherapy and delaying cancer progression have become difficult problems for clinicians. Glucose metabolism has long been regarded as the main metabolic process by which tumor cells meet their bioenergetic and anabolic needs, with the complex interactions between the mitochondria and tumors being ignored. This misconception was not dispelled until the early 2000s; however, the cellular molecules and signaling pathways involved in radioresistance remain incompletely defined. In addition to being a key metabolic site that regulates tumorigenesis, mitochondria can influence the radiation effects of malignancies by controlling redox reactions, participating in oxidative phosphorylation, producing oncometabolites, and triggering apoptosis. Therefore, the mitochondria are promising targets for the development of novel anticancer drugs. In this review, we summarize the internal relationship and related mechanisms between mitochondrial metabolism and cancer radioresistance, thus exploring the possibility of targeting mitochondrial signaling pathways to reverse radiation insensitivity. We suggest that attention should be paid to the potential value of mitochondria in prolonging the survival of cancer patients.

The Wnt Signaling Pathway Inhibitors Improve the Therapeutic Activity of Glycolysis Modulators against Tongue Cancer Cells

Excessive glucose metabolism and disruptions in Wnt signaling are important molecular changes present in oral cancer cells. The aim of this study was to evaluate the effects of the combinatorial use of glycolysis and Wnt signaling inhibitors on viability, cytotoxicity, apoptosis induction, cell cycle distribution and the glycolytic activity of tongue carcinoma cells. CAL 27, SCC-25 and BICR 22 tongue cancer cell lines were used. Cells were treated with inhibitors of glycolysis (2-deoxyglucose and lonidamine) and of Wnt signaling (PRI-724 and IWP-O1). The effects of the compounds on cell viability and cytotoxicity were evaluated with MTS and CellTox Green tests, respectively. Apoptosis was evaluated by MitoPotential Dye staining and cell cycle distribution by staining with propidium iodide, followed by flow cytometric cell analysis. Glucose and lactate concentrations in a culture medium were evaluated luminometrically. Combinations of 2-deoxyglucose and lonidamine with Wnt pathway inhibitors were similarly effective in the impairment of oral cancer cells’ survival. However, the inhibition of the canonical Wnt pathway by PRI-724 was more beneficial, based on the glycolytic activity of the cells. The results point to the therapeutic potential of the combination of low concentrations of glycolytic modulators with Wnt pathway inhibitors in oral cancer cells.

Metabolic Reprogramming of Thyroid Cancer Cells and Crosstalk in Their Microenvironment

Metabolism differs significantly between tumor and normal cells. Metabolic reprogramming in cancer cells and metabolic interplay in the tumor microenvironment (TME) are important for tumor formation and progression. Tumor cells show changes in both catabolism and anabolism. Altered aerobic glycolysis, known as the Warburg effect, is a well-recognized characteristic of tumor cell energy metabolism. Compared with normal cells, tumor cells consume more glucose and glutamine. The enhanced anabolism in tumor cells includes de novo lipid synthesis as well as protein and nucleic acid synthesis. Although these forms of energy supply are uneconomical, they are required for the functioning of cancer cells, including those in thyroid cancer (TC). Increasing attention has recently focused on alterations of the TME. Understanding the metabolic changes governing the intricate relationship between TC cells and the TME may provide novel ideas for the treatment of TC.

Laminar Flow on Endothelial Cells Suppresses eNOS O-GlcNAcylation to Promote eNOS Activity

[Figure: see text].

Lactate secreted by PKM2 upregulation promotes Galectin-9-mediated immunosuppression via inhibiting NF-κB pathway in HNSCC

Pyruvate kinase M2 as a key rate-limiting enzyme in glycolysis, it plays a critical role in metabolic reprogramming and carcinogenesis. However, whether PKM2 can promote immunosuppressive microenvironment formation remains unknown in head and neck squamous cell carcinoma (HNSCC). PKM2 expression was detected using immunohistochemical staining. The biological functions of PKM2 were investigated in vitro and in vivo. Lactate production and the expression of Galectin-9, a critical immunosuppression molecule, were detected after PKM2 knockdown and overexpression in HNSCC cells. The mechanism of lactate regulating Galectin-9 expression through NF-κB signaling was explored in vitro. Overexpression of PKM2 correlates with poor prognosis in HNSCC patients. Silencing PKM2 markedly inhibits proliferation and metastasis capacity in vivo and in vitro, and vice versa. The glycolysis and glycolytic capacity are significantly decreased after PKM2 silencing. Lactate secretion induced by PKM2 significantly promotes migration and invasion capacity. Furthermore, a positive correlation between PKM2 and Galectin-9 expression is observed in HNSCC tissues. The induction of Galectin-9 expression by PKM2 can be affected by a lactate transporter inhibitor. Mechanically, lactate impeded the suppressive transcriptional complex formation of NF-κB and histone deacetylase 3 (HDAC3), which released the transcription of Galectin-9 mediated by NF-κB signaling. Our findings demonstrate that lactate produced by PKM2 upregulation promotes tumor progression and Galectin-9-mediated immunosuppression via NF-κB signaling inhibition in HNSCC, which bridges metabolism and immunosuppression. The novel PKM2-lactate-Galectin-9 axis might be a potential therapeutic target in HNSCC.

Changes in Protein Glycosylation in Head and Neck Squamous Cell Carcinoma

Glycosylation is an important posttranslational modification of proteins, and it has a profound influence on diverse life processes. An abnormal polysaccharide structure and mutation of the glycosylation pathway are closely correlated with human cancer progression. Glycoproteins such as EGFR, E-cadherin, CD44, PD-1/PD-L1, B7-H3 and Muc1 play important roles in the progression of head and neck squamous cell carcinoma (HNSCC), and their levels of glycosylation and changes in glycosyl structure are closely linked to HNSCC progression and malignant transformation. The regulation of protein glycosylation in HNSCC provides potential strategies to control cancer stem cell (CSC) subgroup expansion, epithelial-mesenchymal transition (EMT), tumor-related immunity escape and autophagy. Glycoproteins with altered glycosylation can be used as biomarkers for the early diagnosis, monitoring and prognostication of HNSCC. However, the glycobiology of cancer is still a new field that needs to be deeply studied, especially in HNSCC.

Metabolic Profiling of Human Gastric Cancer Cells Treated With Salazosulfapyridine

PURPOSE

The adhesion molecule cluster of differentiation 44v9 interacts with and stabilizes the cystine/glutamate exchanger protein, which functions as a transporter of cystine. Stabilized cystine/glutamate exchanger increases extracellular cystine uptake and enhances glutathione production. Augmented levels of reduced glutathione mitigate reactive oxygen species and protect cancer cells from apoptosis. Salazosulfapyridine blocks cystine/glutamate exchanger activity and mitigates the supply of cystine to increase intracellular ROS production, thereby increasing cell susceptibility to apoptosis. This enhances the effect of anticancer drugs such as cisplatin. Currently, salazosulfapyridine is being developed as a promising anticancer agent. In the present study, we elucidated the molecular mechanism associated with salazosulfapyridine by investigating the salazosulfapyridine-induced changes in glutathione metabolism in cultured gastric cancer cell lines.

METHODS

The effect of salazosulfapyridine treatment on glutathione metabolism was investigated in 4 gastric cancer (AGS, MKN1, MKN45, and MKN74) and 2 colorectal cancer (HCT15 and HCT116) cell lines using metabolomic analyses. In addition, the effect of inhibition of the reduced form of nicotinamide adenine dinucleotide phosphate by 2-deoxyglucose on glutathione metabolism was evaluated.

RESULTS

Under hypoxia, enhanced glycolysis resulted in lactate accumulation with an associated reduction in nicotinamide adenine dinucleotide phosphate. Salazosulfapyridine treatment decreased the cysteine content and inhibited the formation of glutathione. Combined treatment with salazosulfapyridine and 2-deoxyglucose significantly inhibited cell proliferation. 2-Deoxyglucose, an inhibitor of glycolysis, depleted nicotinamide adenine dinucleotide phosphate required for the formation of glutathione.

CONCLUSIONS

Our results indicate that in cancer cells having a predominant glycolytic pathway, metabolomic analyses under hypoxic conditions enable the profiling of global metabolism. In addition, inhibiting the supply of nicotinamide adenine dinucleotide phosphate by blocking glycolysis is a potential treatment strategy for cancer, in addition to cystine blockade by salazosulfapyridine.

TIPRL potentiates survival of lung cancer by inducing autophagy through the eIF2α-ATF4 pathway

Autophagy, an intracellular system of degrading damaged organelles and misfolded proteins, is essential for cancer cell survival. Despite the progress made towards understanding the mechanism, identification of novel autophagy regulators presents a major obstacle in developing anticancer therapies. Here, we examine the association between the TOR signaling pathway regulator-like (TIPRL) protein and autophagy in malignant transformation of tumors. We show that TIPRL upregulation in non-small cell lung cancer (NSCLC) potentiated autophagy activity and enabled autophagic clearance of metabolic and cellular stress, conferring a survival advantage to cancer cells. Importantly, the interaction of TIPRL with eukaryotic initiation factor 2α (eIF2α) led to eIF2α phosphorylation and activation of the eIF2α-ATF4 pathway, thereby inducing autophagy. Conversely, TIPRL depletion increased apoptosis by reducing autophagic clearance, which was markedly enhanced in TIPRL-depleted A549 xenografts treated with 2-deoxy-D-glucose. Overall, the study indicated that TIPRL is a potential regulator of autophagy and an important drug target for lung cancer therapy.

Impact and Relevance of the Unfolded Protein Response in HNSCC

Head and neck squamous cell carcinomas (HNSCC) encompass a heterogeneous group of solid tumors that arise from the upper aerodigestive tract. The tumor cells face multiple challenges including an acute demand of protein synthesis often driven by oncogene activation, limited nutrient and oxygen supply and exposure to chemo/radiotherapy, which forces them to develop adaptive mechanisms such as the Unfolded Protein Response (UPR). It is now well documented that the UPR, a homeostatic mechanism, is induced at different stages of cancer progression in response to intrinsic (oncogenic activation) or extrinsic (microenvironment) perturbations. This review will discuss the role of the UPR in HNSCC as well as in the key processes that characterize the physiology of HNSCC. The role of the UPR in the clinical context of HNSCC will also be addressed.

Targeting the unfolded protein response in head and neck and oral cavity cancers

Many FDA-approved anti-cancer therapies, targeted toward a wide array of molecular targets and signaling networks, have been demonstrated to activate the unfolded protein response (UPR). Despite a critical role for UPR signaling in the apoptotic execution of cancer cells by many of these compounds, the authors are currently unaware of any instance whereby a cancer drug was developed with the UPR as the intended target. With the essential role of the UPR as a driving force in the genesis and maintenance of the malignant phenotype, a great number of pre-clinical studies have surged into the medical literature describing the ability of dozens of compounds to induce UPR signaling in a myriad of cancer models. The focus of the current work is to review the literature and explore the role of the UPR as a mediator of chemotherapy-induced cell death in squamous cell carcinomas of the head and neck (HNSCC) and oral cavity (OCSCC), with an emphasis on preclinical studies.

[2-deoxyglucose inhibits angiogenesis of rheumatoid arthritis via activating AMPK pathway]

OBJECTIVE

To observe the effects of 2-deoxyglucose inhibiting synovial pannus of adjuvant arthritis rats and to explore its potential mechanism of inhibiting angiogenesis by investigating proliferation, migration and matrigel tube formation assay in vitro.

METHODS

The effect of 2-DG on synovial pannus was evaluated by histopathology of HE staining; HUVEC proliferation was determined by CCK-8 method; migration of FLS were determined by transwell; In vitro matrigel tube formation assay was made for assessing tube number of HUVEC; p-AMPK and Bcl-2 were detected by Western blot assay; AMPK signaling pathway in HUVEC was inhibited by compound C, which is an inhibitor of AMPK activation.

RESULTS

2-DG (200 mg/kg) obviously decreased appearance of synovial pannus (P < 0.01); in vitro, 2-DG (0.5 mmol/L and/or 5 mmol/L) obviously inhibited proliferation, migration and tube number of HUVEC (P < 0.01 or P < 0.001), and its effects on HUVEC were reversed by using AMPK antagonist (Compound C); Western blot showed that 2-DG (5 mmol/L) increased expression of p-AMPK and decreased expression of Bcl-2 (P < 0.05).

CONCLUSIONS

Activating AMPK pathway and decreasing expression of Bcl-2 may the potential mechanism by which 2-DG contributes to anti-angiogenesis and effects of inhibiting proliferation, migration and tube number of HUVEC.

SG2NA is a regulator of endoplasmic reticulum (ER) homeostasis as its depletion leads to ER stress

SG2NA belongs to a three-member striatin subfamily of WD40 repeat superfamily of proteins. It has multiple protein-protein interaction domains involved in assembling supramolecular signaling complexes. Earlier, we had demonstrated that there are at least five variants of SG2NA generated by alternative splicing, intron retention, and RNA editing. Such versatile and dynamic mode of regulation implicates it in tissue development. In order to shed light on its role in cell physiology, total proteome analysis was performed in NIH3T3 cells depleted of 78 kDa SG2NA, the only isoform expressing therein. A number of ER stress markers were among those modulated after knockdown of SG2NA. In cells treated with the ER stressors thapsigargin and tunicamycin, expression of SG2NA was increased at both mRNA and protein levels. The increased level of SG2NA was primarily in the mitochondria and the microsomes. A mouse injected with thapsigargin also had an increase in SG2NA in the liver but not in the brain. Cell cycle analysis suggested that while loss of SG2NA reduces the level of cyclin D1 and retains a population of cells in the G1 phase, concurrent ER stress facilitates their exit from G1 and traverse through subsequent phases with concomitant cell death. Thus, SG2NA is a component of intrinsic regulatory pathways that maintains ER homeostasis.

Overexpression of the human DEK oncogene reprograms cellular metabolism and promotes glycolysis

The DEK oncogene is overexpressed in many human malignancies including at early tumor stages. Our reported in vitro and in vivo models of squamous cell carcinoma have demonstrated that DEK contributes functionally to cellular and tumor survival and to proliferation. However, the underlying molecular mechanisms remain poorly understood. Based on recent RNA sequencing experiments, DEK expression was necessary for the transcription of several metabolic enzymes involved in anabolic pathways. This identified a possible mechanism whereby DEK may drive cellular metabolism to enable cell proliferation. Functional metabolic Seahorse analysis demonstrated increased baseline and maximum extracellular acidification rates, a readout of glycolysis, in DEK-overexpressing keratinocytes and squamous cell carcinoma cells. DEK overexpression also increased the maximum rate of oxygen consumption and therefore increased the potential for oxidative phosphorylation (OxPhos). To detect small metabolites that participate in glycolysis and the tricarboxylic acid cycle (TCA) that supplies substrate for OxPhos, we carried out NMR-based metabolomics studies. We found that high levels of DEK significantly reprogrammed cellular metabolism and altered the abundances of amino acids, TCA cycle intermediates and the glycolytic end products lactate, alanine and NAD+. Taken together, these data support a scenario whereby overexpression of the human DEK oncogene reprograms keratinocyte metabolism to fulfill energy and macromolecule demands required to enable and sustain cancer cell growth.