GLUT1 as a therapeutic target in hepatocellular carcinoma

Simvastatin induces breast cancer cell death through oxidative stress up-regulating miR-140-5p

Statins, a class of hyperlipidemic drugs, are widely used cholesterol lowering drugs that selectively inhibit 3-hydroxy-3-methylglutaryl CoA reductase, which is the rate-limiting enzyme in cholesterol biosynthesis, leading to decreasing of cholesterol biosynthesis. Statins exert anti-tumoral effects on various cancer, including breast cancer. However, the molecular mechanisms for the actions were not fully elucidated. The purpose of this study was to elucidate the effects of statins on proliferation and apoptosis in the ER-negative breast cancer cell line MDA-MB-231. Our results showed that simvastatin increased the expression of miR-140-5p in a dose dependent manner via activating transcription factor NRF1, reduced cell proliferation and induced apoptosis, and we also found that SLC2A1 was a new target of miR-140-5p. In conclusion, data in this study shed light on the potential anti-tumoral effects of simvastatin in breast cancer and presents a highly promising therapeutic option, using drug and miRNA for combined treating cancers.

Synthesis of 2'-paclitaxel 2-deoxy-2-fluoro-glucopyranosyl carbonate for specific targeted delivery to cancer cells

A novel 2-fluorodeoxyglucose conjugated derivative of paclitaxel was efficiently synthesized using a linker between 2'-OH of paclitaxel and C1-hydroxyl group of 2-fluorodeoxyglucose. In preparation of the prodrug, allyl carbonates were selected as the protective group and the efficient one-step removal of allyloxycarbonyl groups at the end of the synthesis using palladium chemistry gave the target molecule in good yield. The prodrug not only improved the pharmaceutical properties of paclitaxel, such as solubility and stability, but also demonstrated enhanced cytotoxicity and selectivity for cancer cells and less toxicity toward normal HUVEC cells.

Glucose Transporter-1 Cooperating with AKT Signaling Promote Gastric Cancer Progression

Objective

High expression of GLUT1 has been observed in numerous solid cancers, facilitating glucose consumption for supporting tumor cell survival. The altered metabolic activity is regulated by series of signaling pathways, including AKT signaling that acts as a key role in glucose metabolism and shows close correlation with the malignant transformation. In this study, we aimed to elucidate the effect of GLUT1 on gastric cancer (GC) and to explore the relation between GLUT1 and AKT signaling.

Materials and Methods

GLUT1, p-AKT, and p-S6k1 expression were investigated by immunohistochemistry and semi-quantitative analysis in 57 paired-GC samples. The relationship of GLUT1 with clinical indexes in GC tissues was investigated. The effects of GLUT1 on the prognosis of GC patients and the underlying mechanism involved were studied by subgroup analysis.

Results

In GC tissues, an obvious increase in GLUT1 expression was observed when compared with that of normal tissues (P<0.001). Advanced clinicopathological factors (tumor size P=0.019, invasion depth P=0.002, lymph node metastasis P<0.001, differentiation P=0.024, neural invasion P=0.003, and TNM staging P=0.001) correlated with high GLUT1 levels. GLUT1 was an independent risk factor resulting in poor prognosis (P=0.002, HR=5.132). GLUT1 increased the activation ratio of p-AKT (P<0.01) and p-S6K1 (P<0.001) in GC. The expression of p-S6K1 and GLUT1 was positively correlated. (P=0.001, R=0.173). The survival probability of GC patients with GLUT1(+)/p-S6K1(+) was worse when compared to that of GLUT1(+)/p-S6K1(-) or GLUT1(-)/p-S6K1(+) (P<0.001).

Conclusion

High expression of GLUT1 facilitated GC progression, leading to poor prognosis. Overexpression of GLUT1 activated AKT-S6K1 axis, resulting in adverse outcomes of GC. GLUT1 is novel indicator of GC prognosis and GLUT1 targeted metabolic treatment that has potential therapeutic value.

The SLC Family Are Candidate Diagnostic and Prognostic Biomarkers in Clear Cell Renal Cell Carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most common lethal subtype of renal cancer, and changes in tumor metabolism play a key role in its development. Solute carriers (SLCs) are important in the transport of small molecules in humans, and defects in SLC transporters can lead to serious diseases. The expression patterns and prognostic values of SLC family transporters in the development of ccRCC are still unclear. The current study analyzed the expression levels of SLC family members and their correlation with prognosis in ccRCC patients with data from Oncomine, Gene Expression Profiling Interactive Analysis (GEPIA), The Cancer Genome Atlas (TCGA), cBioPortal, the Human Protein Atlas (HPA), the International Cancer Genome Consortium (ICGC), and the Gene Expression Omnibus (GEO). We found that the mRNA expression levels of SLC22A6, SLC22A7, SLC22A13, SLC25A4, SLC34A1, and SLC44A4 were significantly lower in ccRCC tissues than in normal tissues and the protein expression levels of SLC22A6, SLC22A7, SLC22A13, and SLC34A1 were also significantly lower. Except for SLC22A7, the expression levels of SLC22A6, SLC22A13, SLC25A4, SLC34A1, and SLC44A4 were correlated with the clinical stage of ccRCC patients. The lower the expression levels of SLC22A6, SLC22A13, SLC25A4, SLC34A1, and SLC44A4 were, the later the clinical stage of ccRCC patients was. Further experiments revealed that the expression levels of SLC22A6, SLC22A7, SLC22A13, SLC25A4, SLC34A1, and SLC44A4 were significantly associated with overall survival (OS) and disease-free survival (DFS) in ccRCC patients. High SLC22A6, SLC22A7, SLC22A13, SLC25A4, SLC34A1, and SLC44A4 expression predicted improved OS and DFS. Finally, GSE53757 and ICGC were used to revalidate the differential expression and clinical prognostic value. This study suggests that SLC22A6, SLC22A7, SLC22A13, SLC25A4, SLC34A1, and SLC44A4 may be potential targets for the clinical diagnosis, prognosis, and treatment of ccRCC patients.

Influences of different sugar ligands on targeted delivery of liposomes

Ligands are an important part of targeted drug delivery systems. Optimised lignads not only improve the target efficiency, but also enhance therapeutical effect of drugs. In our research, five sugar molecules (Mannose, Galactose, Glucose, Malt disaccharide, and Maltotriose) conjugated PEG₆₀₀-DSPE were synthesised, of which polysaccharides were first discovered by us as sugar ligands to modify liposomes, which interacts with over expressive GLUT on cancer cells. DiO was encapsulated as fluorescent probe to evaluate their cellular uptake abilities of targeting C6 glioma cells, and the distribution in different visceral organs of rats. The results demonstrated that Malt disaccharide and Glucose-PEG₆₀₀-DSPE had the strong efficiency of cellular uptake by C6 glioma cells. The distribution and accumulation of liposomes showed that different sugars modified liposomes could target different visceral organs in rats. It has provided a novel idea for ligand selectivity and optimisation of nanocarriers for tumour targeted therapy.

Role of Glucose Metabolism Reprogramming in the Pathogenesis of Cholangiocarcinoma

Cholangiocarcinoma (CCA) is one of the most lethal cancers, and its rate of occurrence is increasing annually. The diagnoses of CCA patients remain elusive due to the lack of early symptoms and is misdiagnosed as HCC in a considerable percentage of patients. It is crucial to explore the underlying mechanisms of CCA carcinogenesis and development to find out specific biomarkers for early diagnosis of CCA and new promising therapeutic targets. In recent times, the reprogramming of tumor cells metabolism has been recognized as a hallmark of cancer. The modification from the oxidative phosphorylation metabolic pathway to the glycolysis pathway in CCA meets the demands of cancer cell proliferation and provides a favorable environment for tumor development. The alteration of metabolic programming in cancer cells is complex and may occur via mutations and epigenetic modifications within oncogenes, tumor suppressor genes, signaling pathways, and glycolytic enzymes. Herein we review the altered metabolism in cancer and the signaling pathways involved in this phenomena as they may affect CCA development. Understanding the regulatory pathways of glucose metabolism such as Akt/mTOR, HIF1α, and cMyc in CCA may further develop our knowledge of this devastating disease and may offer relevant information in the exploration of new diagnostic biomarkers and targeted therapeutic approaches for CCA.

Uncovering the Underlying Mechanisms of Cancer Metabolism through the Landscapes and Probability Flux Quantifications

Cancer metabolism is critical for understanding the mechanism of tumorigenesis, yet the understanding is still challenging. We studied gene-metabolism regulatory interactions and quantified the global driving forces for cancer-metabolism dynamics as the underlying landscape and probability flux. We uncovered four steady-state attractors: a normal state attractor, a cancer OXPHOS state attractor, a cancer glycolysis state attractor, and an intermediate cancer state attractor. We identified the key regulatory interactions through global sensitivity analysis based on the landscape topography. Different landscape topographies of glycolysis switch between normal cells and cancer cells were identified. We uncovered that the normal state to cancer state transformation is associated with the peaks of the probability flux and the thermodynamic dissipation, giving dynamical and thermodynamic origin of cancer formation. We found that cancer metabolism oscillations consume more energy to support cancer malignancy. This study provides a quantitative understanding of cancer metabolism and suggests a metabolic therapeutic strategy.

Defying Multidrug Resistance! Modulation of Related Transporters by Flavonoids and Flavonolignans

Multidrug resistance (MDR) is a major challenge for the 21th century in both cancer chemotherapy and antibiotic treatment of bacterial infections. Efflux pumps and transport proteins play an important role in MDR. Compounds displaying inhibitory activity toward these proteins are prospective for adjuvant treatment of such conditions. Natural low-cost and nontoxic flavonoids, thanks to their vast structural diversity, offer a great pool of lead structures with broad possibility of chemical derivatizations. Various flavonoids were found to reverse both antineoplastic and bacterial multidrug resistance by inhibiting Adenosine triphosphate Binding Cassette (ABC)-transporters (human P-glycoprotein, multidrug resistance-associated protein MRP-1, breast cancer resistance protein, and bacterial ABC transporters), as well as other bacterial drug efflux pumps: major facilitator superfamily (MFS), multidrug and toxic compound extrusion (MATE), small multidrug resistance (SMR) and resistance-nodulation-cell-division (RND) transporters, and glucose transporters. Flavonoids and particularly flavonolignans are therefore highly prospective compounds for defying multidrug resistance.

A Newly Established Murine Cell Line as a Model for Hepatocellular Cancer in Non-Alcoholic Steatohepatitis

Non-alcoholic steatohepatitis (NASH) has become a major risk factor for hepatocellular cancer (HCC) due to the worldwide increasing prevalence of obesity. However, the pathophysiology of NASH and its progression to HCC is incompletely understood. Thus, the aim of this study was to generate a model specific NASH-derived HCC cell line. A murine NASH-HCC model was conducted and the obtained cancer cells (N-HCC25) were investigated towards chromosomal aberrations, the expression of cell type-specific markers, dependency on nutrients, and functional importance of mTOR. N-HCC25 exhibited several chromosomal aberrations as compared to healthy hepatocytes. Hepatocytic (HNF4), EMT (Twist, Snail), and cancer stem cell markers (CD44, EpCAM, CK19, Sox9) were simultaneously expressed in these cells. Proliferation highly depended on the supply of glucose and FBS, but not glutamine. Treatment with a second generation mTOR inhibitor (KU-0063794) resulted in a strong decrease of cell growth in a dose-dependent manner. In contrast, a first generation mTOR inhibitor (Everolimus) only slightly reduced cell proliferation. Cell cycle analyses revealed that the observed growth reduction was most likely due to G₁/G₀ cell cycle arrest. These results indicate that N-HCC25 is a highly proliferative HCC cell line from a NASH background, which might serve as a suitable in vitro model for future investigations of NASH-derived HCC.

Dual role of Endoplasmic Reticulum Stress-Mediated Unfolded Protein Response Signaling Pathway in Carcinogenesis

Cancer constitutes a grave problem nowadays in view of the fact that it has become one of the main causes of death worldwide. Poor clinical prognosis is presumably due to cancer cells metabolism as tumor microenvironment is affected by oxidative stress. This event triggers adequate cellular response and thereby creates appropriate conditions for further cancer progression. Endoplasmic reticulum (ER) stress occurs when the balance between an ability of the ER to fold and transfer proteins and the degradation of the misfolded ones become distorted. Since ER is an organelle relatively sensitive to oxidative damage, aforementioned conditions swiftly cause the activation of the unfolded protein response (UPR) signaling pathway. The output of the UPR, depending on numerous factors, may vary and switch between the pro-survival and the pro-apoptotic branch, and hence it displays opposing effects in deciding the fate of the cancer cell. The role of UPR-related proteins in tumorigenesis, such as binding the immunoglobulin protein (BiP) and inositol-requiring enzyme-1α (IRE1α), activating transcription factor 6 (ATF6) or the protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK), has already been specifically described so far. Nevertheless, due to the paradoxical outcomes of the UPR activation as well as gaps in current knowledge, it still needs to be further investigated. Herein we would like to elicit the actual link between neoplastic diseases and the UPR signaling pathway, considering its major branches and discussing its potential use in the development of a novel, anti-cancer, targeted therapy.

Enzymatic and nonenzymatic protein acetylations control glycolysis process in liver diseases

Impaired glycolysis has pathologic effects on the occurrence and progression of liver diseases, and it appears that glycolysis is increased to different degrees in different liver diseases. As an important post-translational modification, reversible lysine acetylation regulates almost all cellular processes, including glycolysis. Lysine acetylation can occur enzymatically with acetyltransferases or nonenzymatically with acetyl-coenzyme A. Accompanied by the progression of liver diseases, there seems to be a temporal and spatial variation between enzymatic and nonenzymatic acetylations in the regulation of glycolysis. Here, we summarize the most recent findings on the functions and targets of acetylation in controlling glycolysis in the different stages of liver diseases. In addition, we discuss the differences and causes between enzymatic and nonenzymatic acetylations in regulating glycolysis throughout the progression of liver diseases. Then, we review these new discoveries to provide the potential implications of these findings for therapeutic interventions in liver diseases.-Li, J., Wang, T., Xia, J., Yao, W., Huang, F. Enzymatic and nonenzymatic protein acetylations control glycolysis process in liver diseases.

Glut 1 in Cancer Cells and the Inhibitory Action of Resveratrol as A Potential Therapeutic Strategy

An important hallmark in cancer cells is the increase in glucose uptake. GLUT1 is an important target in cancer treatment because cancer cells upregulate GLUT1, a membrane protein that facilitates the basal uptake of glucose in most cell types, to ensure the flux of sugar into metabolic pathways. The dysregulation of GLUT1 is associated with numerous disorders, including cancer and metabolic diseases. There are natural products emerging as a source for inhibitors of glucose uptake, and resveratrol is a molecule of natural origin with many properties that acts as antioxidant and antiproliferative in malignant cells. In the present review, we discuss how GLUT1 is involved in the general scheme of cancer cell metabolism, the mechanism of glucose transport, and the importance of GLUT1 structure to understand the inhibition process. Then, we review the current state-of-the-art of resveratrol and other natural products as GLUT1 inhibitors, focusing on those directed at treating different types of cancer. Targeting GLUT1 activity is a promising strategy for the development of drugs aimed at treating neoplastic growth.

GLUT1-mediated effective anti-miRNA21 pompon for cancer therapy

Oncogenic microRNAs are essential components in regulating the gene expression of cancer cells. Especially miR21, which is a major player involved of tumor initiation, progression, invasion and metastasis in several cancers. The delivery of anti-miR21 sequences has significant potential for cancer treatment. Nevertheless, since anti-miR21 sequences are extremely unstable and they need to obtain certain concentration to function, it is intensely difficult to build an effective delivery system for them. The purpose of this work is to construct a self-assembled glutathione (GSH)-responsive system with tumor accumulation capacity for effective anti-miR21 delivery and cancer therapy. A novel drug delivery nanosphere carrying millions of anti-miR21 sequences was developed through the rolling circle transcription (RCT) method. GSH-responsive cationic polymer polyethyleneimine (pOEI) was synthesized to protect the nanosphere from degradation by Dicer or other RNase in normal cells and optimize the pompon-like nanoparticle to suitable size. Dehydroascorbic acid (DHA), a targeting molecule, which is a substrate of glucose transporter 1 (GLUT 1) and highly expressed on malignant tumor cells, was connected to pOEI through PEG, and then the polymer was used for contracting a RNA nanospheres into nanopompons. The anti-miR21 nanopompons showed its potential for effective cancer therapy.

Exosomes from activated hepatic stellate cells contain GLUT1 and PKM2: a role for exosomes in metabolic switch of liver nonparenchymal cells

The mechanism of exosomes derived from activated hepatic stellate cells (HSCs) involved in liver fibrosis is poorly understood. We previously reported that hypoxia-inducible factor 1 (Hif-1) regulated HSC activation, and, therefore, we investigated in current work whether Hif-1 regulates exosome secretion and the metabolic switch of HSCs, thus affecting the metabolism of liver nonparenchymal cells. In this study, the characteristics of exosomes from HSCs were assessed via electron microscopy, Western blot analysis, and acetylcholinesterase activity. Confocal microscopy was used to measure the uptake of exosomes by quiescent HSCs, Kupffer cells (KCs), and liver sinusoidal endothelial cells (LSECs). Hif-1α was inhibited via 2-ME or specific small interfering RNAs to investigate its role in exosomes derived from HSCs. It was determined that glucose transporter 1 and pyruvate kinase M2 were increasingly expressed in fibrotic liver samples, cell lysates, and exosomes derived from activated HSCs. Exosomes released from HSCs were associated with activation and glucose uptake of HSCs. Delivery of exosomes from activated HSCs induced glycolysis of quiescent HSCs, KCs, and LSECs. Disruption of Hif-1 expression suppressed the glycolysis effect delivered by exosomes. Conclusively, our results demonstrated that exosomes secreted by activated HSCs affect the metabolic switch of liver nonparenchymal cells via delivery of glycolysis-related proteins. These findings represent a novel mechanism that contributes to liver fibrosis and has significant implications for new diagnosis and treatment of liver diseases.-Wan, L., Xia, T., Du, Y., Liu, J., Xie, Y., Zhang, Y., Guan, F., Wu, J., Wang, X., Shi, C. Exosomes from activated hepatic stellate cells contain GLUT1 and PKM2: a role for exosomes in metabolic switch of liver nonparenchymal cells.

Acidic Microenvironment Up-Regulates Exosomal miR-21 and miR-10b in Early-Stage Hepatocellular Carcinoma to Promote Cancer Cell Proliferation and Metastasis

Rationale: The incidence of hepatocellular carcinoma is rising worldwide. It is predicted that nearly half of the early-stage hepatocellular carcinoma (E-HCC) patients will develop recurrence. Dysregulated pH, a hallmark of E-HCC, is correlated with poor prognosis. The acidic microenvironment has been shown to promote the release of exosomes, the membrane vesicles recognized as intercellular communicators associated with tumor progression, recurrence, and metastasis. We, therefore, aimed to identify exosomes induced by acidic microenvironment that may regulate E-HCC progression and to explore their mechanisms and clinical significance in E-HCCs.

Methods: miRNA microarray analysis and LASSO logistic statistic model were used to identify the main functional exosomal miRNAs. Invasion and scratch assays were performed to examine the migration and invasion of HCC cells. Immunoblotting and immunofluorescence were employed to detect the epithelial-to-mesenchymal transition (EMT) in HCC cells. Chromatin immunoprecipitation (ChIP) was used to analyze the binding of HIF-1α and HIF-2α to promoter regions of miR-21 and miR-10b.

Results: The acidic microenvironment in HCC was correlated with poor prognosis of patients. Exosomes from HCC cells cultured in the acidic medium could promote cell proliferation, migration, and invasion of recipient HCC cells. We identified miR-21 and miR-10b as the most important functional miRNAs in acidic HCC-derived exosomes. Also, the acidic microenvironment triggered the activation of HIF-1α and HIF-2α and stimulated exosomal miR-21 and miR-10b expression substantially promoting HCC cell proliferation, migration, and invasion both in vivo and in vitro. In E-HCC patients, serum exosomal miR-21 and miR-10b levels were associated with advanced tumor stage and HIF-1α and HIF-2α expression and were independent prognostic factors for disease-free survival of E-HCC patients. Most importantly, we developed a nano-drug to target exosomal miR-21 and/or miR-10b and examined its therapeutic effects against HCC in vivo.

Conclusion: Our findings suggested that the exosomal miR-21 and miR-10b induced by acidic microenvironment in HCC promote cancer cell proliferation and metastasis and may serve as prognostic molecular markers and therapeutic targets for HCC.

The Role of the ER-Induced UPR Pathway and the Efficacy of Its Inhibitors and Inducers in the Inhibition of Tumor Progression

Cancer is the second most frequent cause of death worldwide. It is considered to be one of the most dangerous diseases, and there is still no effective treatment for many types of cancer. Since cancerous cells have a high proliferation rate, it is pivotal for their proper functioning to have the well-functioning protein machinery. Correct protein processing and folding are crucial to maintain tumor homeostasis. Endoplasmic reticulum (ER) stress is one of the leading factors that cause disturbances in these processes. It is induced by impaired function of the ER and accumulation of unfolded proteins. Induction of ER stress affects many molecular pathways that cause the unfolded protein response (UPR). This is the way in which cells can adapt to the new conditions, but when ER stress cannot be resolved, the UPR induces cell death. The molecular mechanisms of this double-edged sword process are involved in the transition of the UPR either in a cell protection mechanism or in apoptosis. However, this process remains poorly understood but seems to be crucial in the treatment of many diseases that are related to ER stress. Hence, understanding the ER stress response, especially in the aspect of pathological consequences of UPR, has the potential to allow us to develop novel therapies and new diagnostic and prognostic markers for cancer.

Aberrant Metabolism in Hepatocellular Carcinoma Provides Diagnostic and Therapeutic Opportunities

Hepatocellular carcinoma (HCC) accounts for over 80% of liver cancer cases and is highly malignant, recurrent, drug-resistant, and often diagnosed in the advanced stage. It is clear that early diagnosis and a better understanding of molecular mechanisms contributing to HCC progression is clinically urgent. Metabolic alterations clearly characterize HCC tumors. Numerous clinical parameters currently used to assess liver functions reflect changes in both enzyme activity and metabolites. Indeed, differences in glucose and acetate utilization are used as a valid clinical tool for stratifying patients with HCC. Moreover, increased serum lactate can distinguish HCC from normal subjects, and serum lactate dehydrogenase is used as a prognostic indicator for HCC patients under therapy. Currently, the emerging field of metabolomics that allows metabolite analysis in biological fluids is a powerful method for discovering new biomarkers. Several metabolic targets have been identified by metabolomics approaches, and these could be used as biomarkers in HCC. Moreover, the integration of different omics approaches could provide useful information on the metabolic pathways at the systems level. In this review, we provided an overview of the metabolic characteristics of HCC considering also the reciprocal influences between the metabolism of cancer cells and their microenvironment. Moreover, we also highlighted the interaction between hepatic metabolite production and their serum revelations through metabolomics researches.

Oviductus ranae protein hydrolysate (ORPH) inhibits the growth, metastasis and glycolysis of HCC by targeting miR-491-5p/PKM2 axis

BACKGROUND

Oviductus Ranae (OR) is a valuable Chinese crude drug and has been reported to have a range of biological activities. Protein hydrolysate extracted from OR (ORPH) was previously found to have immune regulatory effect and anti-glioma activity. This study was aimed to investigate the effects of ORPH on hepatocellular carcinoma (HCC) progression.

METHODS

MTT, BrdU, colony formation and transwell assays were used to determine proliferation and mobility of HCC cells in vitro. Glucose consumption and lactate production assays were carried out to measure the glycolysis of HCC cells. The subcutaneous tumor model and lung metastasis model in nude mice were established to detect tumor growth and metastasis of HCC in vivo. The direct binding of miR-491-5p to 3'UTR of pyruvate kinase M2 (PKM2) was confirmed by luciferase reporter assay.

RESULTS

In vitro experiments showed that ORPH significantly inhibited proliferation, migration, invasion, epithelial-to-mesenchymal transition (EMT) and glycolysis of HCC cells. Moreover, ORPH treatment prominently suppressed HCC growth and metastasis in mice. We demonstrated that ORPH effectively decreased the expression of PKM2 in HCC cells. Forced expression of PKM2 abrogated the inhibitory effects of ORPH on HCC cells. Mechanically, ORPH reduced PKM2 expression in a post-transcriptional manner by up-regulating miR-491-5p. miR-491-5p exhibited a similar tumor suppressive effects with ORPH in HCC cells. Moreover, ORPH exerted its inhibitory effects on HCC cells through regulating miR-491-5p/PKM2 axis. Lastly, decreased miR-491-5p level and increased PKM2 expression were correlated with unfavorable clinical features and poor prognosis of HCC patients.

CONCLUSIONS

In all, this study reveals that ORPH inhibits the growth, metastasis and glycolysis of HCC cells by targeting miR-491-5p/PKM2 axis. ORPH may be a potential effective anti-tumor agent for HCC.

Transmembrane Exchange of Fluorosugars: Characterization of Red Cell GLUT1 Kinetics Using 19F NMR

We have developed a new approach, to our knowledge, to quantify the equilibrium exchange kinetics of carrier-mediated transmembrane transport of fluorinated substrates. The method is based on adapted kinetic theory that describes the concentration dependence of the transmembrane exchange rates of two competing, simultaneously transported species. Using the new approach, we quantified the kinetics of membrane transport of both anomers of three monofluorinated glucose analogs in human erythrocytes (red blood cells) using ¹⁹F NMR exchange spectroscopy. An inosine-based glucose-free medium was shown to promote survival and stable metabolism of red blood cells over the duration of the experiments (several hours). Earlier NMR studies only yielded the apparent rate constants and transmembrane fluxes of the anomeric species, whereas we could categorize the two anomers in terms of the catalytic activity (specificity constants) of the glucose transport protein GLUT1 toward them. Differences in the membrane permeability of the three glucose analogs were qualitatively interpreted in terms of local perturbations in the bonding of substrates to key amino acid residues in the active site of GLUT1. The methodology of this work will be applicable to studies of other carrier-mediated membrane transport processes, especially those with competition between simultaneously transported species. The GLUT1-specific results can be applied to the design of probes of glucose transport or inhibitors of glucose metabolism in cells, including those exhibiting the Warburg effect.

In vivo evaluation of the effects of simultaneous inhibition of GLUT-1 and HIF-1α by antisense oligodeoxynucleotides on the radiosensitivity of laryngeal carcinoma using micro 18F-FDG PET/CT

Purpose

Hypoxia-inducible factor 1α (HIF-1α) and glucose transporter-1 (GLUT-1) are two important hypoxic markers associated with the radioresistance of cancers including laryngeal carcinoma. We evaluated whether the simultaneous inhibition of GLUT-1 and HIF-1α expression improved the radiosensitivity of laryngeal carcinoma. We explored whether the expression of HIF-1α and GLUT-1 was correlated with 2′-deoxy-2’-[18F]fluoro-D-glucose (¹⁸F-FDG) uptake and whether ¹⁸F-FDG positron emission tomography-computed tomography (PET/CT) was appropriate for early evaluation of the response of laryngeal carcinoma to targeted treatment in vivo.

Materials and Methods

To verify the above hypotheses, an in vivo model was applied by subcutaneously injecting Hep-2 (2 × 107/mL × 0.2 mL) and Tu212 cells (2 × 107/mL × 0.2 mL) into nude mice. The effects of HIF-1α antisense oligodeoxynucleotides (AS-ODNs) (100 μg) and GLUT-1 AS-ODNs (100 μg) on the radiosensitivity of laryngeal carcinoma were assessed by tumor volume and weight, microvessel density (MVD), apoptosis index (AI) and necrosis in vivo based on a full factorial (2³) design. ¹⁸F-FDG-PET/CT was taken before and after the treatment of xenografts. The relationships between HIF-1α and GLUT-1 expression and ¹⁸F-FDG uptake in xenografts were estimated and the value of ¹⁸F-FDG-PET/CT was assessed after treating the xenografts.

Results

10 Gy X-ray irradiation decreased the weight of Hep-2 xenografts 8 and 12 days after treatment, and the weights of Tu212 xenografts 8 days after treatment. GLUT-1 AS-ODNs decreased the weight of Tu212 xenografts 12 days after treatment. There was a synergistic interaction among the three treatments (GLUT-1 AS-ODNs, HIF-1α AS-ODNs and 10Gy X-ray irradiation) in increasing apoptosis, decreasing MVD, and increasing necrosis in Hep-2 xenografts 8 days after treatment (p < 0.05) and in Tu212 xenografts 12 days after treatment (p < 0.001). Standardized uptake value (tumor/normal tissue)( SUVmaxT/N) did not show a statistically significant correlation with GLUT1 and HIF-1α expression and therapeutic effect (necrosis, apoptosis).

Conclusions

Simultaneous inhibition of HIF-1α and GLUT-1 expression might increase the radiosensitivity of laryngeal carcinoma, decreasing MVD, and promoting apoptosis and necrosis. ¹⁸F-FDG-PET/CT wasn't useful in evaluating the therapeutic effect on laryngeal cancer in this animal study.

Gene network analysis reveals a novel 22-gene signature of carbon metabolism in hepatocellular carcinoma

Although much progress has been made in understanding cancer cellular metabolism adaptation, the co-regulations between genes of metabolism and cancer pathways and their interactions remain poorly characterized. Here, we applied gene co-expression network analysis to 1509 metabolic gene expression data generated from 120 HCC and 180 non-tumor human liver tissues by microarray. Our analyses reveal that metabolism genes can be classified into different co-expression modules based on their associations with HCC related traits. The co-regulation mechanism of the carbon metabolism genes in normal liver tissues was interrupted during the processes of carcinogenesis. In parallel, we performed RNAseq analysis of HCC and non-tumor human liver tissues, and identified a unique 22-carbon-metabolism-gene-signature of increased expression. This gene signature was further verified in multiple microarray data sets, and its prognostic value was also proven by HCC patients' survival data from TCGA. Additionally, the tumorigenic function of two representative genes, CS and ACSS1, were validated experimentally by cell growth and spheroid formation assays. The current study provides evidence for the reprogramming of the co-regulation network between carbon metabolism and cancer pathway genes in HCC. In addition, this study also reveals a unique 22-carbon-metabolism-gene-expression-signature in HCC. Strategies targeting these genes may represent new therapeutic approaches for HCC treatment.

Identification of Key Pathways and Genes in the Dynamic Progression of HCC Based on WGCNA

Hepatocellular carcinoma (HCC) is a devastating disease worldwide. Though many efforts have been made to elucidate the process of HCC, its molecular mechanisms of development remain elusive due to its complexity. To explore the stepwise carcinogenic process from pre-neoplastic lesions to the end stage of HCC, we employed weighted gene co-expression network analysis (WGCNA) which has been proved to be an effective method in many diseases to detect co-expressed modules and hub genes using eight pathological stages including normal, cirrhosis without HCC, cirrhosis, low-grade dysplastic, high-grade dysplastic, very early and early, advanced HCC and very advanced HCC. Among the eight consecutive pathological stages, five representative modules are selected to perform canonical pathway enrichment and upstream regulator analysis by using ingenuity pathway analysis (IPA) software. We found that cell cycle related biological processes were activated at four neoplastic stages, and the degree of activation of the cell cycle corresponded to the deterioration degree of HCC. The orange and yellow modules enriched in energy metabolism, especially oxidative metabolism, and the expression value of the genes decreased only at four neoplastic stages. The brown module, enriched in protein ubiquitination and ephrin receptor signaling pathways, correlated mainly with the very early stage of HCC. The darkred module, enriched in hepatic fibrosis/hepatic stellate cell activation, correlated with the cirrhotic stage only. The high degree hub genes were identified based on the protein-protein interaction (PPI) network and were verified by Kaplan-Meier survival analysis. The novel five high degree hub genes signature that was identified in our study may shed light on future prognostic and therapeutic approaches. Our study brings a new perspective to the understanding of the key pathways and genes in the dynamic changes of HCC progression. These findings shed light on further investigations.

AKT-mediated phosphorylation of ATG4B impairs mitochondrial activity and enhances the Warburg effect in hepatocellular carcinoma cells

Phosphorylation is a major type of post-translational modification, which can influence the cellular physiological function. ATG4B, a key macroautophagy/autophagy-related protein, has a potential effect on the survival of tumor cells. However, the role of ATG4B phosphorylation in cancers is still unknown. In this study, we identified a novel phosphorylation site at Ser34 of ATG4B induced by AKT in HCC cells. The phosphorylation of ATG4B at Ser34 had little effect on autophagic flux, but promoted the Warburg effect including the increase of L-lactate production and glucose consumption, and the decrease of oxygen consumption in HCC cells. The Ser34 phosphorylation of ATG4B also contributed to the impairment of mitochondrial activity including the inhibition of F₁Fo-ATP synthase activity and the elevation of mitochondrial ROS in HCC cells. Moreover, the phosphorylation of ATG4B at Ser34 enhanced its mitochondrial location and the subsequent colocalization with F₁Fo-ATP synthase in HCC cells. Furthermore, recombinant human ATG4B protein suppressed the activity of F₁Fo-ATP synthase in MgATP submitochondrial particles from patient-derived HCC tissues in vitro. In brief, our results demonstrate for the first time that the phosphorylation of ATG4B at Ser34 participates in the metabolic reprogramming of HCC cells via repressing mitochondrial function, which possibly results from the Ser34 phosphorylation-induced mitochondrial enrichment of ATG4B and the subsequent inhibition of F₁Fo-ATP synthase activity. Our findings reveal a noncanonical working pattern of ATG4B under pathological conditions, which may provide a scientific basis for developing novel strategies for HCC treatment by targeting ATG4B and its Ser34 phosphorylation.

Comparative Study of Different Diets-Induced NAFLD Models of Zebrafish

Dietary composition has important impact on nonalcoholic fatty liver disease (NAFLD). The purpose of this study was to explore the relationship between NAFLD and major dietary components using zebrafish larvae fed different diets. Zebrafish larvae fed with high cholesterol (HC), high fructose (HF) and extra feeding (EF) diets for 10 days displayed varying degrees steatosis. The incidence and degree of steatosis were the most severe in the EF group. A HC diet severely promoted lipid deposits in the caudal vein. The triglyceride and glucose contents of zebrafish significantly increased in the HF and EF groups compared with the control group. Moreover, the mRNA expression of oxidative stress gene gpx1a, endoplasmic reticulum stress genes ddit3 and grp78, inflammatory genes tnfa, glucose metabolism genes irs2, glut1 and glut2, and lipid metabolism genes cidec, chrebp, ppara and cpt1a were significantly increased in the HF group. The HC diet was associated with upregulation of grp78, and downregulation of irs2, glut1 and glut2. The mRNA expression of lipogenesis and glucose metabolism associated genes were decreased in the EF group. In addition, the autophagy associated genes atg3, atg5, atg7, and atg12, and protein expression of ATG3 and LC3BII were reduced and P62 were elevated in the HC group. We also performed comparative transcriptome analysis of the four groups. A total of 2,492 differentially expressed genes were identified, and 24 statistically significant pathways were enriched in the diet treatment groups. This study extends our understanding of the relationships between diet ingredients and host factors that contribute to the pathogenesis of NAFLD, which may provide new ideas for the treatment of NAFLD.

Clear cell hepatocellular carcinoma: origin, metabolic traits and fate of glycogenotic clear and ground glass cells

Clear cell hepatocellular carcinoma (CCHCC) has hitherto been considered an uncommon, highly differentiated variant of hepatocellular carcinoma (HCC) with a relatively favorable prognosis. CCHCC is composed of mixtures of clear and/or acidophilic ground glass hepatocytes with excessive glycogen and/or fat and shares histology, clinical features and etiology with common HCCs. Studies in animal models of chemical, hormonal and viral hepatocarcinogenesis and observations in patients with chronic liver diseases prone to develop HCC have shown that the majority of HCCs are preceded by, or associated with, focal or diffuse excessive storage of glycogen (glycogenosis) which later may be replaced by fat (lipidosis/steatosis). In ground glass cells, the glycogenosis is accompanied by proliferation of the smooth endoplasmic reticulum, which is closely related to glycogen particles and frequently harbors the hepatitis B surface antigen (HBsAg). From the findings in animal models a sequence of changes has been established, commencing with preneoplastic glycogenotic liver lesions, often containing ground glass cells, and progressing to glycogen-poor neoplasms via various intermediate stages, including glycogenotic/lipidotic clear cell foci, clear cell hepatocellular adenomas (CCHCA) rich in glycogen and/or fat, and CCHCC. A similar process seems to take place in humans, with clear cells frequently persisting in CCHCC and steatohepatitic HCC, which presumably represent intermediate stages in the development rather than particular variants of HCC. During the progression of the preneoplastic lesions, the clear and ground glass cells transform into cells characteristic of common HCC. The sequential cellular changes are associated with metabolic aberrations, which start with an activation of the insulin signaling cascade resulting in pre-neoplastic hepatic glycogenosis. The molecular and metabolic changes underlying the glycogenosis/lipidosis are apparently responsible for the dramatic metabolic shift from gluconeogenesis to the pentose phosphate pathway and Warburg-type glycolysis, which provide precursors and energy for an ever increasing cell proliferation during progression.

Aminoglucose-functionalized, redox-responsive polymer nanomicelles for overcoming chemoresistance in lung cancer cells

Background

Chemotherapeutic drugs used for cancer therapy frequently encounter multiple-drug resistance (MDR). Nanoscale carriers that can target tumors to accumulate and release drugs intracellularly have the greatest potential for overcoming MDR. Glucose transporter-1 (GLUT-1) and glutathione (GSH) overexpression in cancer cells was exploited to assemble aminoglucose (AG)-conjugated, redox-responsive nanomicelles from a single disulfide bond-bridged block polymer of polyethylene glycol and polylactic acid (AG-PEG-SS-PLA). However, whether this dual functional vector can overcome MDR in lung cancer is unknown.

Results

In this experiment, AG-PEG-SS-PLA was synthetized successfully, and paclitaxel (PTX)-loaded AG-PEG-SS-PLA (AG-PEG-SS-PLA/PTX) nanomicelles exhibited excellent physical properties. These nanomicelles show enhanced tumor targeting as well as drug accumulation and retention in MDR cancer cells. Caveolin-dependent endocytosis is mainly responsible for nanomicelle internalization. After internalization, the disulfide bond of AG-PEG-SS-PLA is cleaved in the presence of high intracellular glutathione levels, causing the hydrophobic core to become a polar aqueous solution, which subsequently results in nanomicelle disassembly and the rapid release of encapsulated PTX. Reduced drug resistance was observed in cancer cells in vitro. The caspase-9 and caspase-3 cascade was activated by the AG-PEG-SS-PLA/PTX nanomicelles through upregulation of the pro-apoptotic proteins Bax and Bid and suppression of the anti-apoptotic protein Bcl-2, thereby increasing apoptosis. Furthermore, significantly enhanced tumor growth inhibition was observed in nude mice bearing A549/ADR xenograft tumors after the administration of AG-PEG-SS-PLA/PTX nanomicelles via tail injection.

Conclusions

These promising results indicate that AG-PEG-SS-PLA/PTX nanomicelles could provide the foundation for a paradigm shift in MDR cancer therapy.

Electronic supplementary material

The online version of this article (10.1186/s12951-017-0316-z) contains supplementary material, which is available to authorized users.

Essential role for non-canonical poly(A) polymerase GLD4 in cytoplasmic polyadenylation and carbohydrate metabolism

Regulation of gene expression at the level of cytoplasmic polyadenylation is important for many biological phenomena including cell cycle progression, mitochondrial respiration, and learning and memory. GLD4 is one of the non-canonical poly(A) polymerases that regulates cytoplasmic polyadenylation-induced translation, but its target mRNAs and role in cellular physiology is not well known. To assess the full panoply of mRNAs whose polyadenylation is controlled by GLD4, we performed an unbiased whole genome-wide screen using poy(U) chromatography and thermal elution. We identified hundreds of mRNAs regulated by GLD4, several of which are involved in carbohydrate metabolism including GLUT1, a major glucose transporter. Depletion of GLD4 not only reduced GLUT1 poly(A) tail length, but also GLUT1 protein. GLD4-mediated translational control of GLUT1 mRNA is dependent of an RNA binding protein, CPEB1, and its binding elements in the 3΄ UTR. Through regulating GLUT1 level, GLD4 affects glucose uptake into cells and lactate levels. Moreover, GLD4 depletion impairs glucose deprivation-induced GLUT1 up-regulation. In addition, we found that GLD4 affects glucose-dependent cellular phenotypes such as migration and invasion in glioblastoma cells. Our observations delineate a novel post-transcriptional regulatory network involving carbohydrate metabolism and glucose homeostasis mediated by GLD4.

Dehydroascorbic Acid and pGPMA Dual Modified pH-Sensitive Polymeric Micelles for Target Treatment of Liver Cancer

In clinical therapy, the poor prognosis of hepatocellular carcinoma (HCC) is mainly attributed to the failure of chemotherapeutical agents to accumulate in tumor as well as lack of potency of tumor penetration. In this work, we developed actively tumor-targeting micelles with pH-sensitive linker as a novel nanocarrier for HCC therapy. These micelles comprised biodegradable poly(ethylene glycol)-poly(aspartate) polymers, in which paclitaxel can be covalently conjugated to pAsp via an acid-labile acetal bond to form pH-responsive structures. In vitro drug release studies showed that these structures were stable in physiological condition, whereas collapsed once internalized into cells due to the mildly acidic environment in endo/lysosomes, resulting in facilitated intracellular paclitaxel release. In addition, dehydroascorbic acid and guanidinopropyl methacrylamide polymers were decorated on the surface of micelles to achieve specific tumor accumulation and tumor penetration. Cellular uptake and in vivo imaging studies proved that these micelles had remarkable targeting property toward hepatocarcinoma cells and tumor. Enhanced anti-HCC efficacy of the micelles was also confirmed both in vitro and in vivo. Therefore, this micellar system may be a potential platform of chemotherapeutics delivery for HCC therapy.

Expression of carbonic anhydrase IX is associated with poor prognosis through regulation of the epithelial‑mesenchymal transition in hepatocellular carcinoma

Carbonic anhydrase 9 (CA9) is a plasma membrane-associated isoenzyme that catalyzes pH regulation under hypoxic conditions. CA9 is transcriptionally regulated by hypoxia-inducible factor 1. Recent studies reported that hypoxia also promoted the epithelial-mesenchymal transition (EMT) in various cancers. In the present study, we evaluated the relationship between CA9 expression and EMT in vitro with two hepatoma cell lines. We also examined the clinical significance of CA9 expression in 117 consecutive patients that underwent hepatectomies for hepatocellular carcinoma (HCC). We evaluated CA9 expression and EMT induction under hypoxia with quantitative RT-PCR, western blot analysis and immunofluorescence staining, in HuH7 and HepG2 cells. We knocked down CA9 expression with small interfering RNA to evaluate the relationship between CA9 and EMT. We found that hypoxia induced CA9 expression in HCC cells and promoted EMT, evidenced by a loss of E-cadherin and an increase in N-cadherin. Twist, a transcriptional regulator of EMT, was also upregulated with hypoxia. The CA9 deficiency attenuated hypoxia-induced changes in E-cadherin and N-cadherin. Immunohistochemical evaluations of patient samples showed that CA9 was expressed in 50.4% of patients (59/117). However, patients with and without CA9 expression were not significantly different in clinicopathological factors. Nevertheless, a multivariate analysis showed that CA9 expression was an independent factor for both recurrence and prognosis among patients that underwent curative surgery for HCC. In conclusion, this study revealed that CA9 expression was a pivotal predictive factor for poor prognosis after radical surgery for HCC. Moreover, the CA9 regulation of the expression of EMT-related molecules represented a mechanism that enhanced malignant potential.

GLUT1 expression in pediatric adrenocortical tumors: a promising candidate to predict clinical behavior

Background

Discrimination between benign and malignant tumors is a challenging process in pediatric adrenocortical tumors. New insights in the metabolic profile of pediatric adrenocortical tumors may contribute to this distinction, predict prognosis, as well as identify new molecular targets for therapy. The aim of this work is to characterize the expression of the metabolism-related proteins MCT1, MCT2, MCT4, CD147, CD44, GLUT1 and CAIX in a series of pediatric adrenocortical tumors.

Methods

A total of 50 pediatric patients presenting adrenocortical tumors, including 41 clinically benign and 9 clinically malignant tumors, were included. Protein expression was evaluated using immunohistochemistry in samples arranged in tissue microarrays.

Results

The immunohistochemical analysis showed a significant increase in plasma membrane expression of GLUT1 in malignant lesions, when compared to benign lesions (p=0.004), being the expression of this protein associated with shorter overall and disease-free survival (p=0.004 and p=0.001, respectively). Although significant differences were not observed for proteins other than GLUT1, MCT1, MCT4 and CD147 were highly expressed in pediatric adrenocortical neoplasias (around 90%).

Conclusion

GLUT1 expression was differentially expressed in pediatric adrenocortical tumors, with higher expression in clinically malignant tumors, and associated with shorter survival, suggesting a metabolic remodeling towards a hyperglycolytic phenotype in this malignancy.

SLC transporters as a novel class of tumour suppressors: identity, function and molecular mechanisms

The role of plasma membrane transporters in cancer is receiving increasing attention in recent years. Several transporters for essential nutrients are up-regulated in cancer and serve as tumour promoters. Transporters could also function as tumour suppressors. To date, four transporters belonging to the SLC gene family have been identified as tumour suppressors. SLC5A8 is a Na(+)-coupled transporter for monocarboxylates. Among its substrates are the bacterial fermentation products butyrate and propionate and the ubiquitous metabolite pyruvate. The tumour-suppressive function of this transporter relates to the ability of butyrate, propionate and pyruvate to inhibit histone deacetylases (HDAC). SLC5A8 functions as a tumour suppressor in most tissues studied thus far, and provides a molecular link to Warburg effect, a characteristic feature in most cancers. It also links colonic bacteria and dietary fibre to the host. SLC26A3 as a tumour suppressor is restricted to colon; it is a Cl(-)/HCO(-) 3 exchanger, facilitating the efflux of HCO(-) 3 The likely mechanism for the tumour-suppressive function of SLC26A3 is related to intracellular pH regulation. SLC39A1 is a Zn(2+) transporter and its role in tumour suppression has been shown in prostate. Zn(2+) is present at high concentrations in normal prostate where it elicits its tumour-suppressive function. SLC22A18 is possibly an organic cation transporter, but the identity of its physiological substrates is unknown. As such, there is no information on molecular pathways responsible for the tumour-suppressive function of this transporter. It is likely that additional SLC transporters will be discovered as tumour suppressors in the future.

miR-148b inhibits glycolysis in gastric cancer through targeting SLC2A1

Although the molecular biology of GC has been well characterized, early diagnostic biomarkers and effective therapeutic options in gastric cancer are still under investigation. Here, we found that miR-148b expression decreased in human gastric cancer tissues compared with matched adjacent nontumor tissues by q-PCR analysis and in situ hybridization. Further investigation revealed that overexpression of miR-148b limited glycolysis including glucose consumption, lactate production in gastric cancer cell lines BGC-823 and MKN45. Bioinformatics prediction uncovered that a dedicated transporters solute carrier family 2 member 1 (SLC2A1), also called GLUT1, was the direct target of miR-148b. The target effects were further confirmed by luciferase assay and western blot analysis. Besides, a reverse correlation was observed between relative SLC2A1 and miR-148b expression in human GC tissues compared with matched adjacent nontumor tissues. Subsequently, SLC2A1 suppression by SLC2A1 siRNA or specific inhibitor restricted the reduced effects of glycolysis mediated by miR-148b while SLC2A1 overexpression abrogated the effect of miR-148b on glycolysis. Our findings provided new evidence of miR-148b in GC development through restraining glycolysis, highlighting the role of miR-148b as a new target for GC treatment.

An analysis of the polymorphisms of the GLUT1 gene in urothelial cell carcinomas of the bladder and its correlation with p53, Ki67 and GLUT1 expressions

Frequencies of two glucose transporter 1 (GLUT1) single-nucleotide polymorphisms (SNPs) (XbaI G>T and HaeIII T>C) were studied with urothelial cell carcinomas of the bladder (UCC) and 204 normal persons. And the expression of the p53, Ki67 and GLUT1 was assayed by immunohistochemistry. The frequency of the TT genotype and T allele of the XbaI G>T SNP was decreased in the patients with UCC. The frequency of the CC genotype and C allele of the HaeIII T>C SNP was decreased in the patients with UCC. The GLUT1 XbaI genotype GG was more frequent in higher tumor stage and higher tumor grade patients. In the XbaI G>T SNP, the GG genotype was significantly related to higher Remmele immunoreactive score (IRS) of Ki67 and higher IRS of GLUT1. In conclusion, the TT genotype in XbaI G>T SNP and CC genotype of HaeIII T>C SNP may have protective effect in the carcinogenesis process of UCC. In the XbaI G>T SNP, the GG genotype of was positively related to tumor proliferation, glucose metabolism, tumor grade and stage. Therefore, the variant might become a possible proliferation-related prognostic factor for UCC.

Dehydroascorbic Acids-modified Polymer Micelles Target Cancer Cells to Enhance Anti-tumor Efficacy of Paclitaxel

Paclitaxel (PTX), especially albumin-bound PTX in clinical, has displayed significant inhibition of tumor growth in patients. But the systemic distribution and poor water solubility of PTX often lead to severe side effects, consequently limiting the anti-tumor efficacy. In this study, we developed a novel PTX-loaded polymeric micelle drug delivery system. These self-assembled polymeric micelles from core to outside consisted of poly L-phenylalanine (pPhe), DTSSP linked poly L-lysine (pLys), poly ethylene glycol (PEG) and dehydroascorbic acids (DHA). pPhe formed the hydrophobic core to encapsulate PTX; DTSSPs on pLys covalently cross-linked and formed disulfide bond to stabilize PTX from loss in blood circulation; PEG improved solubility to lower toxicity of PTX for its high hydrophilicity; DHA targeted tumors by specifically recognizing GLUT1 mainly expressed on tumor cells. Thus, PTX would be precisely released into tumor cells with high dose of glutathione to break disulfide bond. Moreover, these PTX-loaded polymer micelles significantly suppressed tumor cell viability, proliferation, and migration in vitro, and also greatly inhibited tumor growth and prolonged survival in tumor-bearing mice without detectable side effects. Therefore, the new drug delivery system could reduce severe side effects and enhance anti-tumor efficacy of PTX via peripheral stabilization, low toxicity and tumor targeting.

ρ⁰ Cells Feature De-Ubiquitination of SLC Transporters and Increased Levels and Fluxes of Amino Acids

Solute carrier (SLC) transporters are a diverse group of membrane transporter proteins that regulate the cellular flux and distribution of endogenous and xenobiotic compounds. Post-translational modifications (PTMs), such as ubiquitination, have recently emerged as one of the major regulatory mechanisms in protein function and localization. Previously, we showed that SLC amino acid transporters were on average 6-fold de-ubiquitinated and increased amino acid levels were detected in ρ⁰ cells (lacking mitochondrial DNA, mtDNA) compared to parental cells. Here, we elucidated the altered functionality of SLC transporters and their dynamic ubiquitination status by measuring the uptake of several isotopically labeled amino acids in both human osteosarcoma 143B.TK- and ρ⁰ cells. Our pulse chase analysis indicated that de-ubiquitinated amino acid transporters in ρ⁰ cells were accompanied by an increased transport rate, which leads to higher levels of amino acids in the cell. Finding SLC transport enhancers is an aim of the pharmaceutical industry in order to compensate for loss of function mutations in these genes. Thus, the ubiquitination status of SLC transporters could be an indicator for their functionality, but evidence for a direct connection between de-ubiquitination and transporter activity has to be further elucidated.

ROS-Switchable Polymeric Nanoplatform with Stimuli-Responsive Release for Active Targeted Drug Delivery to Breast Cancer

Tumor microenvironment plays a vital role in the process of tumor development, proliferation, invasion, and metastasis. It is well acknowledged that reduction in pH, reactive oxygen species (ROS), and increased level of glucose transporter 1 (GLUT1) have become featured intracellular and extracellular biochemical markers of cancer owing to oncogenic transformation and abnormal metabolism. To establish a distinctive drug delivery system directed against the tumor microenvironment features, we develop a newly engineered polymeric nanoplatform for efficient doxorubicin (DOX) delivery with reduced systemic toxicity and high antitumor efficiency. A thioketal cross-linker is used to improve the formulation's stability during circulation and to foster quick intracellular drug release in response to tumor's ROS potential. Furthermore, the low drug loading efficiency of conventional micelles is ameliorated in this polymeric nanoplatform via a drug-conjugation strategy with an acid-labile chemical bond. The optimized formulation, MPLs-sB-DOX micelles, possesses a high drug-loading efficiency (31%) within nanosize diameter (37.8 nm). In addition, this formulation shows significant improvement in the pharmacokinetics and biodistribution profiles with a 2.69-fold increase of tumor accumulation, while with largely reduced systemic toxicity in comparison with free DOX. With advantages of efficient cellular uptake, preferential tumor accumulation, and controlled release behaviors, MPLs-sB-DOX micelles demonstrate good tumor-targeting ability with reduced systemic toxicity, proving to be a promising formulation for breast cancer therapy.

Regulation of Acetate Utilization by Monocarboxylate Transporter 1 (MCT1) in Hepatocellular Carcinoma (HCC)

Altered energy metabolism is a biochemical fingerprint of cancer cells. Hepatocellular carcinoma (HCC) shows reciprocal [18F]fluorodeoxyglucose (FDG) and [11C]acetate uptake, as revealed by positron emission tomography/computed tomography (PET/CT). Previous studies have focused on the role of FDG uptake in cancer cells. In this study, we evaluated the mechanism and roles of [11C]acetate uptake in human HCCs and cell lines. The expression of monocarboxylate transporters (MCTs) was assessed to determine the transporters of [11C]acetate uptake in HCC cell lines and human HCCs with different [11C]acetate uptake. Using two representative cell lines with widely different [11C]acetate uptake (HepG2 for high uptake and Hep3B for low uptake), changes in [11C]acetate uptake were measured after treatment with an MCT1 inhibitor or MCT1-targeted siRNA. To verify the roles of MCT1 in cells, oxygen consumption rate and the amount of lipid synthesis were measured. HepG2 cells with high [11C]acetate uptake showed higher MCT1 expression than other HCC cell lines with low [11C]acetate uptake. MCT1 expression was elevated in human HCCs with high [11C]acetate uptake compared to those with low [11C]acetate uptake. After blocking MCT1 with AR-C155858 or MCT1 knockdown, [11C]acetate uptake in HepG2 cells was significantly reduced. Additionally, inhibition of MCT1 suppressed mitochondrial oxidative phosphorylation, lipid synthesis, and cellular proliferation in HCC cells with high [11C]acetate uptake. MCT1 may be a new therapeutic target for acetate-dependent HCCs with high [11C]acetate uptake, which can be selected by [11C]acetate PET/CT imaging in clinical practice.

Molecular Pathogenesis of Hepatocellular Carcinoma

The pathogenesis of hepatocellular carcinoma (HCC) is a multistep process involving the progressive accumulation of molecular alterations pinpointing different molecular and cellular events. The next-generation sequencing technology is facilitating the global and systematic evaluation of molecular landscapes in HCC. There is emerging evidence supporting the importance of cancer metabolism and tumor microenvironment in providing a favorable and supportive niche to expedite HCC development. Moreover, recent studies have identified distinct surface markers of cancer stem cell (CSC) in HCC, and they also put forward the profound involvement of altered signaling pathways and epigenetic modifications in CSCs, in addition to the concomitant drug resistance and metastasis. Taken together, multiple key genetic and non-genetic factors, as well as liver CSCs, result in the development and progression of HCC.

Identification and Optimization of the First Highly Selective GLUT1 Inhibitor BAY-876

Despite the long‐known fact that the facilitative glucose transporter GLUT1 is one of the key players safeguarding the increase in glucose consumption of many tumor entities even under conditions of normal oxygen supply (known as the Warburg effect), only few endeavors have been undertaken to find a GLUT1‐selective small‐molecule inhibitor. Because other transporters of the GLUT1 family are involved in crucial processes, these transporters should not be addressed by such an inhibitor. A high‐throughput screen against a library of ∼3 million compounds was performed to find a small molecule with this challenging potency and selectivity profile. The N‐(1H‐pyrazol‐4‐yl)quinoline‐4‐carboxamides were identified as an excellent starting point for further compound optimization. After extensive structure–activity relationship explorations, single‐digit nanomolar inhibitors with a selectivity factor of >100 against GLUT2, GLUT3, and GLUT4 were obtained. The most promising compound, BAY‐876 [N⁴‐[1‐(4‐cyanobenzyl)‐5‐methyl‐3‐(trifluoromethyl)‐1H‐pyrazol‐4‐yl]‐7‐fluoroquinoline‐2,4‐dicarboxamide], showed good metabolic stability in vitro and high oral bioavailability in vivo.

ZnCl2 sustains the adriamycin-induced cell death inhibited by high glucose

Hyperglycemia, the condition of high blood glucose, is typical of diabetes and obesity and represents a significant clinical problem. The relationship between hyperglycemia and cancer risk has been established by several studies. Moreover, hyperglycemia has been shown to reduce cancer cell response to therapies, conferring resistance to drug-induced cell death. Therefore, counteracting the negative effects of hyperglycemia may positively improve the cancer cell death induced by chemotherapies. Recent studies showed that zinc supplementation may have beneficial effects on glycemic control. Here we aimed at evaluating whether ZnCl2 could counteract the high-glucose (HG) effects and consequently restore the drug-induced cancer cell death. At the molecular level we found that the HG-induced expression of genes known to be involved in chemoresistance (such as HIF-1α, GLUT1, and HK2 glycolytic genes, as well as NF-κB activity) was reduced by ZnCl2 treatment. In agreement, the adryamicin (ADR)-induced apoptotic cancer cell death was significantly impaired by HG and efficiently re-established by ZnCl2 cotreatment. Mechanistically, the ADR-induced c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) phosphorylation, inhibited by HG, was efficiently restored by ZnCl2. The JNK involvement in apoptotic cell death was assessed by the use of JNK dominant-negative expression vector that indeed impaired the ZnCl2 ability to restore drug-induced cell death in HG condition. Altogether, these findings indicate that ZnCl2 supplementation efficiently restored the drug-induced cancer cell death, inhibited by HG, by both sustaining JNK activation and counteracting the glycolytic pathway.

Specific protein 1 depletion attenuates glucose uptake and proliferation of human glioma cells by regulating GLUT3 expression

It has been reported previously that the expression of glucose transporter member 3 (GLUT3) is increased in malignant glioma cells compared with normal glial cells. However, the regulating mechanism that causes this phenomenon remains unknown. The present study investigated the regulating role of transcription factor specific protein 1 (Sp1) in GLUT3 expression in a human glioma cell line. In the present study, Sp1 was identified to directly bind to the GLUT3 5′-untranslated region in human glioma U251 cells. Small interfering RNA- and the Sp1-inhibitor mithramycin A-mediated Sp1 knockdown experiments revealed that Sp1 depletion decreased glucose uptake and inhibited cell growth and invasion of U251 cells by downregulating GLUT3 expression. Therefore Sp1 is an important positive regulator for the expression of GLUT3 in human glioma cells, and may explain the overexpression of GLUT3 in U251 cells. These results suggest that Sp1 may have a role in glioma treatment.

Mechanism of inhibition of human glucose transporter GLUT1 is conserved between cytochalasin B and phenylalanine amides

Cancerous cells have an acutely increased demand for energy, leading to increased levels of human glucose transporter 1 (hGLUT1). This up-regulation suggests hGLUT1 as a target for therapeutic inhibitors addressing a multitude of cancer types. Here, we present three inhibitor-bound, inward-open structures of WT-hGLUT1 crystallized with three different inhibitors: cytochalasin B, a nine-membered bicyclic ring fused to a 14-membered macrocycle, which has been described extensively in the literature of hGLUTs, and two previously undescribed Phe amide-derived inhibitors. Despite very different chemical backbones, all three compounds bind in the central cavity of the inward-open state of hGLUT1, and all binding sites overlap the glucose-binding site. The inhibitory action of the compounds was determined for hGLUT family members, hGLUT1-4, using cell-based assays, and compared with homology models for these hGLUT members. This comparison uncovered a probable basis for the observed differences in inhibition between family members. We pinpoint regions of the hGLUT proteins that can be targeted to achieve isoform selectivity, and show that these same regions are used for inhibitors with very distinct structural backbones. The inhibitor cocomplex structures of hGLUT1 provide an important structural insight for the design of more selective inhibitors for hGLUTs and hGLUT1 in particular.