Predictive value of glucose transporter-1 and glucose transporter-3 for survival of cancer patients: A meta-analysis

Prognostic value of hypoxia-responsive gene expression profile in patients diagnosed with head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a disease associated with a severe mortality and high risk of distant metastasis and local recurrence. Currently, surgery and radiotherapy are the main treatment modes, however, therapeutic efficacy of radiotherapy is linked to tumor resistance. Hypoxia has been shown to affect outcome of radiotherapy in HNSCC patients. The aim of this study was to verify the expression of the previously identified hypoxia-responsive genes (CA9, CASP14, LOX, GLUT3, SERPINE1, AREG, EREG, CCNB1 and KIF14) in HNSCC patient material as well as assess their prognostic potential. Tumor biopsies obtained before start of radiotherapy from 32 HNSCC patients classified as responders or non-responders were investigated in this study. The mRNA expression was quantified using RT-qPCR. The mRNA expression of CA9, SERPINE1 and KIF14 was significantly higher in the analyzed patient material compared with the non-cancerous oral tissue. Moreover, the KIF14 mRNA expression was significantly higher in the responder group compared to non-responders. Further studies demonstrated that knockdown of KIF14 reverses its radiosensitizing capability. Additionally, low expression of KIF14 mRNA correlated with significantly shorter OS (overall survival). In conclusion, our results suggest that KIF14 might be a useful prognostic and predictive marker in HNSCC.

Oxidative stress regulation and related metabolic pathways in epithelial-mesenchymal transition of breast cancer stem cells

Epithelial-mesenchymal transition (EMT) is a cell remodeling process in which epithelial cells undergo a reversible phenotype switch via the loss of adhesion capacity and acquisition of mesenchymal characteristics. In other words, EMT activation can increase invasiveness and metastatic properties, and prevent the sensitivity of tumor cells to chemotherapeutics, as mesenchymal cells have a higher resistance to chemotherapy and immunotherapy. EMT is orchestrated by a complex and multifactorial network, often linked to episodic, transient, or partial events. A variety of factors have been implicated in EMT development. Based on this concept, multiple metabolic pathways and master transcription factors, such as Snail, Twist, and ZEB, can drive the EMT. Emerging evidence suggests that oxidative stress plays a significant role in EMT induction. One emerging theory is that reducing mitochondrial-derived reactive oxygen species production may contribute to EMT development. This review describes how metabolic pathways and transcription factors are linked to EMT induction and addresses the involvement of signaling pathways.

[Features of expression of GLUT-1 and Ki-67 proteins in various components of mixed variants of ameloblastoma]

THE AIM OF THE STUDY

The aim was to study the metabolic and proliferative activity of the components of ameloblastoma of mixed histological structure. To assess the impact of individual components of mixed variants of ameloblastoma on treatment results and the risk of relapse.

MATERIAL AND METHODS

The study included 21 histological specimens of mixed ameloblastoma. To study proliferative and metabolic activity, histological preparations were immunohistochemically stained. To assess the proliferation of tumor components, histological preparations were stained for the presence of antigens to Ki-67, and the level of metabolic activity was assessed by the expression level of the glucose transporter GLUT-1. Statistical analysis was performed using the Mann-Whitney test, statistical significance was determined using the Chi-square test, and correlation analysis was performed using Spearman's.

RESULTS

Among the samples of mixed ameloblastoma included in the study, a non-uniform distribution of proliferation and intensity of metabolic activity among the components was obtained. So, among all the components, the plexiform and basal cell variants are distinguished by the greatest proliferative activity. The metabolic activity of these components of mixed ameloblastoma is also increased.

CONCLUSIONS

The data obtained allow us to conclude that it is necessary to take into account plexiform and basal cell components of mixed ameloblastoma, as this can affect the effectiveness of treatment and the risk of relapse.

MicroRNAs-mediated regulation of glucose transporter (GLUT) expression in glioblastoma

Current knowledge about the role of microRNAs (miRNAs) in tumor glucose metabolism is growing, and a number of studies regularly confirm the impact miRNAs can have on glucose metabolism reprogramming in tumors. However, there remains a lack of understanding of the broader perspective on the role of miRNAs in energy reprogramming in glioblastoma. An important role in the metabolism of glucose is played by carrier proteins that ensure its transmembrane movement. Carrier proteins in mammalian cells are glucose transporters (GLUTs). In total, 12 types of GLUTs are distinguished, differing in localization, affinity for glucose and ability to regulate. The fact of increased consumption of glucose in tumors compared to non-proliferating normal tissues is known. Tumor cells need glucose to ensure their survival and growth, so the type of transport proteins like GLUT are critical for them. Previous studies have shown that GLUT-1 and GLUT-3 may play an important role in the development of some types of malignant tumors, including glioblastoma. In addition, there is evidence of how GLUT-1 and GLUT-3 expression is regulated by miRNAs in glioblastoma. Thus, the aim of this study is to highlight the role of specific miRNAs in modulating GLUT levels in order to take into account the use of miRNAs expression modulators as a useful strategy to increase the sensitivity of glioblastoma to current therapies.

An Update on the Metabolic Landscape of Oncogenic Viruses

Viruses play an important role in cancer development as about 12% of cancer types are linked to viral infections. Viruses that induce cellular transformation are known as oncoviruses. Although the mechanisms of viral oncogenesis differ between viruses, all oncogenic viruses share the ability to establish persistent chronic infections with no obvious symptoms for years. During these prolonged infections, oncogenic viruses manipulate cell signaling pathways that control cell cycle progression, apoptosis, inflammation, and metabolism. Importantly, it seems that most oncoviruses depend on these changes for their persistence and amplification. Metabolic changes induced by oncoviruses share many common features with cancer metabolism. Indeed, viruses, like proliferating cancer cells, require increased biosynthetic precursors for virion production, need to balance cellular redox homeostasis, and need to ensure host cell survival in a given tissue microenvironment. Thus, like for cancer cells, viral replication and persistence of infected cells frequently depend on metabolic changes. Here, we draw parallels between metabolic changes observed in cancers or induced by oncoviruses, with a focus on pathways involved in the regulation of glucose, lipid, and amino acids. We describe whether and how oncoviruses depend on metabolic changes, with the perspective of targeting them for antiviral and onco-therapeutic approaches in the context of viral infections.

Metabolic Pathways in Breast Cancer Reprograming: An Insight to Non-Coding RNAs

Cancer cells reprogram their metabolisms to achieve high energetic requirements and produce precursors that facilitate uncontrolled cell proliferation. Metabolic reprograming involves not only the dysregulation in glucose-metabolizing regulatory enzymes, but also the enzymes engaging in the lipid and amino acid metabolisms. Nevertheless, the underlying regulatory mechanisms of reprograming are not fully understood. Non-coding RNAs (ncRNAs) as functional RNA molecules cannot translate into proteins, but they do play a regulatory role in gene expression. Moreover, ncRNAs have been demonstrated to be implicated in the metabolic modulations in breast cancer (BC) by regulating the metabolic-related enzymes. Here, we will focus on the regulatory involvement of ncRNAs (microRNA, circular RNA and long ncRNA) in BC metabolism, including glucose, lipid and glutamine metabolism. Investigation of this aspect may not only alter the approaches of BC diagnosis and prognosis, but may also open a new avenue in using ncRNA-based therapeutics for BC treatment by targeting different metabolic pathways.

Crosstalk between Hypoxia and Extracellular Matrix in the Tumor Microenvironment in Breast Cancer

Even though breast cancer is the most diagnosed cancer among women, treatments are not always successful in preventing its progression. Recent studies suggest that hypoxia and the extracellular matrix (ECM) are important in altering cell metabolism and tumor metastasis. Therefore, the aim of this review is to study the crosstalk between hypoxia and the ECM and to assess their impact on breast cancer progression. The findings indicate that hypoxic signaling engages multiple mechanisms that directly contribute to ECM remodeling, ultimately increasing breast cancer aggressiveness. Second, hypoxia and the ECM cooperate to alter different aspects of cell metabolism. They mutually enhance aerobic glycolysis through upregulation of glucose transport, glycolytic enzymes, and by regulating intracellular pH. Both alter lipid and amino acid metabolism by stimulating lipid and amino acid uptake and synthesis, thereby providing the tumor with additional energy for growth and metastasis. Third, YAP/TAZ signaling is not merely regulated by the tumor microenvironment and cell metabolism, but it also regulates it primarily through its target c-Myc. Taken together, this review provides a better understanding of the crosstalk between hypoxia and the ECM in breast cancer. Additionally, it points to a role for the YAP/TAZ mechanotransduction pathway as an important link between hypoxia and the ECM in the tumor microenvironment, driving breast cancer progression.

Identification of stromal microenvironment characteristics and key molecular mining in pancreatic cancer

PURPOSE

Pancreatic cancer is one of the deadliest cancers worldwide. The extracellular matrix (ECM) microenvironment affects the drug sensitivity and prognosis of pancreatic cancer patients. This study constructed an 8-genes pancreatic ECM scoring (PECMS) model, to classify the ECM features of pancreatic cancer, analyze the impact of ECM features on survival and drug sensitivity, and mine key molecules that influence ECM features in pancreatic cancer.

METHODS

GSVA score calculation and clustering were performed in TCGA-PAAD patients. Lasso regression was used to construct the PECMS model. The association between PECMS and patient survival was analyzed and validated in the CPTAC-3 dataset of TCGA and our single-center retrospective cohort. The relationships between PECMS and features of the matrix microenvironment were analyzed. Finally, PECMS feature genes were screened and verified in pancreatic cancer specimens to select key genes associated with the ECM microenvironment.

RESULT

The survival of the PECMS-high group was significantly worse. The PECMS-high group showed higher oxidative stress levels, lower levels of antigen presentation- and MHC-I molecule-related pathways, and less immune effector cell infiltration. Data from IMvigor-210 cohort suggested that PECMS-low group patients were more sensitive to immune checkpoint blockers. The PECMS score was negatively correlated with chemotherapy drug sensitivity. The negative association of PECMS with survival and drug sensitivity was validated in our retrospective cohort. KLHL32 expression predicted lower oxidative stress level and more immune cells infiltrate in pancreatic cancer.

CONCLUSION

PECMS is an effective predictor of prognosis and drug sensitivity in pancreatic cancer patients. KLHL32 may play an important role in the construction of ECM, and the mechanism is worth further study.

Glucose transporters as markers of diagnosis and prognosis in cancer diseases

The primary metabolic substrate for cells is glucose, which acts as both a source of energy and a substrate in several processes. However, being lipophilic, the cell membrane is impermeable to glucose and specific carrier proteins are needed to allow transport. In contrast to normal cells, cancer cells are more likely to generate energy by glycolysis; as this process generates fewer molecules of adenosine triphosphate (ATP) than complete oxidative breakdown, more glucose molecules are needed. The increased demand for glucose in cancer cells is satisfied by overexpression of a number of glucose transporters, and decreased levels of others. As specific correlations have been observed between the occurrence of cancer and the expression of glucose carrier proteins, the presence of changes in expression of glucose transporters may be treated as a marker of diagnosis and/or prognosis for cancer patients.

Androgen-Dependent Prostate Cancer Cells Reprogram Their Metabolic Signature upon GLUT1 Upregulation by Manganese Superoxide Dismutase

Prostate cancer is the second leading cause of cancer in men across the globe. The prostate gland accounts for some unique glycolytic metabolic characteristics, which causes the metabolic features of prostate tumor initiation and progression to remain poorly characterized. The mitochondrial superoxide dismutase (SOD2) is one of the major redox metabolism regulators. This study points out SOD2 as one major regulator for both redox and glycolytic metabolism in prostate cancer. SOD2 overexpression increases glucose transporter GLUT-1 and glucose uptake. This is not an insulin-mediated effect and seems to be sex-dependent, being present in male mice only. This event concurs with a series of substantial metabolic rearrangements at cytoplasmic and mitochondrial level. A concomitant decrease in glycolytic and pentose phosphate activity, and an increase in electron transfer in the mitochondrial electronic chain, were observed. The Krebs Cycle is altered to produce amino-acid intermediates by decreasing succinate dehydrogenase. This in turn generates a 13-fold increase in the oncometabolite succinate. The protein energy sensor AMPK is decreased at basal and phosphorylated levels in response to glucose deprivation. Finally, preliminary results in prostate cancer patients indicate that glandular areas presenting high levels of SOD2 show a very strong correlation with GLUT-1 protein levels (R² = 0.287 p-value < 0.0001), indicating that in patients there may exist an analogous phenomenon to those observed in cell culture and mice.

Tumor Microenvironment Features and Chemoresistance in Pancreatic Ductal Adenocarcinoma: Insights into Targeting Physicochemical Barriers and Metabolism as Therapeutic Approaches

Currently, the median overall survival of PDAC patients rarely exceeds 1 year and has an overall 5-year survival rate of about 9%. These numbers are anticipated to worsen in the future due to the lack of understanding of the factors involved in its strong chemoresistance. Chemotherapy remains the only treatment option for most PDAC patients; however, the available therapeutic strategies are insufficient. The factors involved in chemoresistance include the development of a desmoplastic stroma which reprograms cellular metabolism, and both contribute to an impaired response to therapy. PDAC stroma is composed of immune cells, endothelial cells, and cancer-associated fibroblasts embedded in a prominent, dense extracellular matrix associated with areas of hypoxia and acidic extracellular pH. While multiple gene mutations are involved in PDAC initiation, this desmoplastic stroma plays an important role in driving progression, metastasis, and chemoresistance. Elucidating the mechanisms underlying PDAC resistance are a prerequisite for designing novel approaches to increase patient survival. In this review, we provide an overview of the stromal features and how they contribute to the chemoresistance in PDAC treatment. By highlighting new paradigms in the role of the stromal compartment in PDAC therapy, we hope to stimulate new concepts aimed at improving patient outcomes.

GLUT1, GLUT3 Expression and 18FDG-PET/CT in Human Malignant Melanoma: What Relationship Exists? New Insights and Perspectives

BACKGROUND

Malignant melanoma is the most aggressive of skin cancers and the 19th most common cancer worldwide, with an estimated age-standardized incidence rate of 2.8-3.1 per 100,000; although there have been clear advances in therapeutic treatment, the prognosis of MM patients with Breslow thickness greater than 1 mm is still quite poor today. The study of how melanoma cells manage to survive and proliferate by consuming glucose has been partially addressed in the literature, but some rather interesting results are starting to be present.

METHODS

A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and a search of PubMed and Web of Sciences (WoS) databases was performed until 27 September 2021 using the terms: glucose transporter 1 and 3 and GLUT1/3 in combination with each of the following: melanoma, neoplasm and immunohistochemistry.

RESULTS

In total, 46 records were initially identified in the literature search, of which six were duplicates. After screening for eligibility and inclusion criteria, 16 publications were ultimately included.

CONCLUSIONS

the results discussed regarding the role and expression of GLUT are still far from definitive, but further steps toward understanding and stopping this mechanism have, at least in part, been taken. New studies and new discoveries should lead to further clarification of some aspects since the various mechanisms of glucose uptake by neoplastic cells are not limited to the transporters of the GLUT family alone.

Expression of Glucose Metabolism-Related Proteins in Adrenal Neoplasms

PURPOSE

The aim of this study was to investigate the expression patterns of glucose metabolism-related proteins and their clinicopathologic implications in adrenal cortical neoplasms (ACN) and pheochromocytoma (PCC).

METHODS

Immunohistochemical staining was performed to evaluate glucose metabolism-related proteins (GLUT1, CAIX, hexokinase II, G6PDH, PHGDH, and SHMT1) in 132 ACN cases (115 adrenal cortical adenoma [ACA] and 17 adrenal cortical carcinoma [ACC]) and 189 PCC cases.

RESULTS

Expression levels of GLUT1 in tumor cells ([T]; p < 0.001), GLUT1 in stromal cells ([S]; p < 0.001), G6PDH (p < 0.001), and SHMT1 (p = 0.002) were higher in ACN than in PCC. GLUT1 (T; p = 0.045) and PHGDH (p = 0.043) levels were higher in ACC than in ACA. In a univariate analysis of ACN, GLUT1 (T; p = 0.017), CAIX (S; p = 0.003), and PHGDH (p = 0.009) levels were correlated with a shorter overall survival (OS). GLUT1 (T; p = 0.001) and PHGDH (p < 0.001) were related to a shorter OS in PCC. GLUT1 (T) positivity (p = 0.043) in ACN predicted a poor OS in a multivariate Cox analysis. In PCC, high GAPP score (p = 0.026), GLUT1 (T; p = 0.002), and PHGDH (p < 0.001) were independent prognostic factors for poor OS.

CONCLUSIONS

The adrenal gland tumors ACN and PCC had different expression patterns of glucose metabolism-related proteins (GLUT1, G6PDH, and SHMT1), with higher expression levels in ACN than in PCC. GLUT1 and PHGDH were significant prognostic factors in these adrenal neoplasms.

Involvement of GLUT1 and GLUT3 in the growth of canine melanoma cells

The rate of glucose uptake dramatically increases in cancer cells even in the presence of oxygen and fully functioning mitochondria. Cancer cells produce ATP by glycolysis rather than oxidative phosphorylation under aerobic conditions, a process termed as the “Warburg effect.” In the present study, we treated canine melanoma cells with the glucose analog 2-deoxy-D-glucose (2-DG) and investigated its effect on cell growth. 2-DG attenuated cell growth in a time- and dose-dependent manner. Cell growth was also inhibited following treatment with the glucose transporter (GLUT) inhibitor WZB-117. The treatment of 2-DG and WZB-117 attenuated the glucose consumption, lactate secretion and glucose uptake of the cells. The mRNA expression of the subtypes of GLUT was examined and GLUT1 and GLUT3 were found to be expressed in melanoma cells. The growth, glucose consumption and lactate secretion of melanoma cells transfected with siRNAs of specific for GLUT1 and GLUT3 was suppressed. These findings suggest that glucose uptake via GLUT1 and GLUT3 plays a crucial role for the growth of canine melanoma cells.

Potential Role of Glucose Transporter-1 Expression in Gastric Cancer: A Meta-Analysis and Systematic Review

Background:

Glucose transporter-1 (GLUT-1) has been differentially expressed in various malignancies including gastric cancer (GC). Several previous meta-analyses of GLUT-1 have some significant limitations, such as researching the association between GLUT-1 and various cancer types with no specificity, not studying clinicopathological parameters with GLUT-1, existing conspicuous heterogeneity and so forth. Therefore, we performed a meta-analysis to evaluate the association between GLUT-1 expression and survival of gastric cancer patients, as well as clinicopathological characteristics.

Methods:

We systematically searched PubMed, Embase, Web of Science and China National Knowledge Infrastructure for relevant studies in accordance with the applicable criteria up to Aug 2017. Hazard ratios (HRs) and odds ratios (ORs) with their 95% confidence intervals (CIs) were used as the effective measures.

Results:

A total of 13 studies involving 1972 patients were included in this meta-analysis. The results demonstrated that there was a significant association between GLUT-1 expression and overall survival (OS) (HR=1.45, 95% CI=1.13–1.87) or disease-free survival (DFS) (HR=2.18, 95% CI=1.46–3.25). Moreover, GLUT-1 expression was significantly correlated with worse tumor nodes metastases (TNM) stage (OR=0.34, 95% CI=0.28–0.43), presence of lymph node metastasis (OR=2.88, 95% CI=1.34–6.19), intestinal type of Lauren classification (OR=3.84, 95% CI=2.57–5.74) and invasion of serosa (OR=0.25, 95% CI=0.18–0.35).

Conclusion:

Our meta-analysis showed that GLUT-1 was significantly correlated with poor OS and DFS in gastric cancer. Additionally, GLUT-1 was also a potential prognostic indicator of aggressive clinicopathological parameters in gastric cancer.

Vitamin C in combination with inhibition of mutant IDH1 synergistically activates TET enzymes and epigenetically modulates gene silencing in colon cancer cells

Mutations in the enzyme isocitrate dehydrogenase 1 (IDH1) lead to metabolic alterations and a sustained formation of 2-hydroxyglutarate (2-HG). 2-HG is an oncometabolite as it inhibits the activity of α-ketoglutarate-dependent dioxygenases such as ten-eleven translocation (TET) enzymes. Inhibitors of mutant IDH enzymes, like ML309, are currently tested in order to lower the levels of 2-HG. Vitamin C (VC) is an inducer of TET enzymes. To test a new therapeutic avenue of synergistic effects, the anti-neoplastic activity of inhibition of mutant IDH1 via ML309 in the presence of VC was investigated in the colon cancer cell line HCT116 IDH1R132H/+ (harbouring a mutated IDH1 allele) and the parental cells HCT116 IDH1+/+ (wild type IDH1). Measurement of the oncometabolite indicated a 56-fold higher content of 2-HG in mutated cells compared to wild type cells. A significant reduction of 2-HG was observed in mutated cells after treatment with ML 309, whereas VC produced only minimally changes of the oncometabolite. However, combinatorial treatment with both, ML309 and VC, in mutated cells induced pronounced reduction of 2-HG leading to levels comparable to those in wild type cells. The decreased level of 2-HG in mutated cells after combinatorial treatment was accompanied by an enhanced global DNA hydroxymethylation and an increased gene expression of certain tumour suppressors. Moreover, mutated cells showed an increased percentage of apoptotic cells after treatment with non-cytotoxic concentrations of ML309 and VC. These results suggest that combinatorial therapy is of interest for further investigation to rescue TET activity and treatment of IDH1/2 mutated cancers.

Sustain, Adapt, and Overcome-Hypoxia Associated Changes in the Progression of Lymphatic Neoplasia

Irregular perfusion and related tissue hypoxia is a common feature of solid tumors the role of which in the survival and progression cancer has been gradually recognized. Adaptation and selection mechanisms in hypoxic areas in solid tumors are regulated by Hypoxia Inducible transcriptional factor 1 (HIF1) and other hypoxia mediators and are associated with aggressive clinical behavior in a large spectrum of malignancies. Aggressive forms of lymphatic neoplasias present with solid tumor-like features, also including rapid cell growth, necrosis and angiogenesis, the clinical potential of which is still underestimated. While the role of regional hypoxia in normal B-cell maturation and malignant transformation is becoming evident, the impact of tissue hypoxia on their behavior is not well-understood. Compared to some of the common solid cancer types data for some of the key regulators, such as HIF1 and HIF2, and for their downstream effectors are available in a limited fashion. In the current review we aim to overview the physiological aspects of major hypoxia pathways during B-cell maturation and adaptation-related changes reported in lymphatic neoplasia covering important targets, such as carbonic anhydrases IX and XII (CAIX, CAXII), glucose transporter 1 (GLUT-1) and vascular endothelial growth factor (VEGF). In conclusion, experimental and clinical results direct to important but currently unexploited role of hypoxia-driven resistance mechanisms especially in aggressive forms of B-cell neoplasia.

Associations between GLUT expression and SUV values derived from FDG-PET in different tumors-A systematic review and meta analysis

PURPOSE

Fluorodeoxyglucose-Positron-emission tomography (FDG-PET), quantified by standardized uptake values (SUV), is one of the most used functional imaging modality in clinical routine. It is widely acknowledged to be strongly associated with Glucose-transporter family (GLUT)-expression in tumors, which mediates the glucose uptake into cells. The present systematic review sought to elucidate the association between GLUT 1 and 3 expression with SUV values in various tumors.

METHODS

MEDLINE library was screened for associations between FDG-PET parameters and GLUT correlation cancer up to October 2018.

RESULTS

There were 53 studies comprising 2291 patients involving GLUT 1 expression and 11 studies comprising 405 patients of GLUT 3 expression. The pooled correlation coefficient for GLUT 1 was r = 0.46 (95% CI 0.40-0.52), for GLUT 3 was r = 0.35 (95%CI 0.24-0.46). Thereafter, subgroup analyses were performed. The highest correlation coefficient for GLUT 1 was found in pancreatic cancer r = 0.60 (95%CI 0.46-0.75), the lowest was identified in colorectal cancer with r = 0.21 (95% CI -0.57-0.09).

CONCLUSION

An overall only moderate association was found between GLUT 1 expression and SUV values derived from FDG-PET. The correlation coefficient with GLUT 3 was weaker. Presumably, the underlying mechanisms of glucose hypermetabolism in tumors are more complex and not solely depended on the GLUT expression.

SLC5A1 promotes growth and proliferation of pancreatic carcinoma via glucose-dependent AMPK/mTOR signaling

Background: Accumulating studies have reported that aberrant expression of SLC5A1 is a negative prognostic factor to various cancer patients.

Purpose: Pancreatic cancer tissue has also shown to harbor higher expression of SLC5A1, however how SLC5A1 mediates pancreatic cancer cells growth remains unclear.

Methods: In this study, we examined the mRNA and protein expressions of SLC5A1 in human pancreatic tissue and various cell lines. The in vitro and in vivo roles of SLC5A1 in pancreatic cancer were investigated through stably transfected pancreatic cells with shRNA plasmid targeting SLC5A1.

Results: Our results observed SLC5A1 was over-expressed in human pancreatic cancer tissues as well as most pancreatic cancer cell lines. Both in vitro and in vivo inhibition of SLC5A1 retarded pancreatic cancer cell growth and progression. The SLC5A1 knockdown mediated growth suppression is mainly regulated by reduced cellular glucose uptake by pancreatic cancer cells. Our further mechanistic observation showed that inhibition of SLC5A1 induced AMPK-dependent mTOR suppression and pharmacological inhibition of AMPK rescued the effect of SLC5A1 blockade. Further protein-protein interaction analysis showed association of SLC5A1 with EGFR and knockdown of EGFR also showed decreased cellular survival and glucose uptake by pancreatic cancer cells.

Conclusion: Our findings postulated SLC5A1/EGFR as the potential therapeutic target of pancreatic cancer patients.

Targeting cancer metabolism through synthetic lethality-based combinatorial treatment strategies

PURPOSE OF REVIEW

Targeting cancer metabolism for therapy has received much attention over the last decade with various small molecule inhibitors entering clinical trials. The present review highlights the latest strategies to target glucose and glutamine metabolism for cancer therapy with a particular emphasis on novel combinatorial treatment approaches.

RECENT FINDINGS

Inhibitors of glucose, lactate, and glutamine transport and the ensuing metabolism are in preclinical to clinical trial stages of investigation. Recent advances in our understanding of cell-intrinsic and cell-extrinsic factors that dictate dependence on these targets have informed the development of rational, synthetic lethality-based strategies to exploit these metabolic vulnerabilities.

SUMMARY

Cancer cells exhibit a number of metabolic alterations with functional consequences beyond that of sustaining cellular energetics and biosynthesis. Elucidating context-specific metabolic dependencies and their connections to oncogenic signaling and epigenetic programs in tumor cells represents a promising approach to identify new metabolic drug targets for cancer therapy.

Hypoxia-Modified Cancer Cell Metabolism

While oxygen is critical to the continued existence of complex organisms, extreme levels of oxygen within a system, known as hypoxia (low levels of oxygen) and hyperoxia (excessive levels of oxygen), potentially promote stress within a defined biological environment. The consequences of tissue hypoxia, a result of a defective oxygen supply, vary in response to the gravity, extent and environment of the malfunction. Persistent pathological hypoxia is incompatible with normal biological functions, and as a result, multicellular organisms have been compelled to develop both organism-wide and cellular-level hypoxia solutions. Both direct, including oxidative phosphorylation down-regulation and inhibition of fatty-acid desaturation, and indirect processes, including altered hypoxia-sensitive transcription factor expression, facilitate the metabolic modifications that occur in response to hypoxia. Due to the dysfunctional vasculature associated with large areas of some cancers, sections of these tumors continue to develop in hypoxic environments. Crucial to drug development, a robust understanding of the significance of these metabolism changes will facilitate our understanding of cancer cell survival. This review defines our current knowledge base of several of the hypoxia-instigated modifications in cancer cell metabolism and exemplifies the correlation between metabolic change and its support of the hypoxic-adapted malignancy.

Glucose and Lactate Transport in Pancreatic Cancer: Glycolytic Metabolism Revisited

Membrane transporters fulfill essential roles in maintaining normal cellular function in health. In cancer, transporters likewise facilitate the aberrant characteristics typical of proliferating tumor cells. Pancreatic ductal adenocarcinoma is remarkable in its aggressiveness, and its metabolism is supported by a variety of membrane transporters. Glucose transporter 1 is upregulated in pancreatic cancer, enables rapid cellular uptake of glucose, and contributes to the invasiveness and metastatic ability of the disease. Likewise, the machinery of glycolysis, enzymes such as pyruvate kinase type M2 and hexokinase 2, is particularly active and ultimately leads to both lactate and tumor formation. Lactic acid channels and transporters include monocarboxylate transporters 1 and 4, connexin43, and CD147. In conjunction with glucose transporters and glycolytic metabolism, lactic acid transport helps perpetuate tumor cell metabolism and contributes to the formation of the unique tumor microenvironment in pancreatic cancer. These transporters may serve as potential therapeutic targets.

Inhibition of GLUT-1 expression and the PI3K/Akt pathway to enhance the chemosensitivity of laryngeal carcinoma cells in vitro

Background

The mechanism of chemoresistance remains unknown. Here, we investigated if glucose transporter-1 (GLUT-1) and PI3K/Akt pathways are associated with the sensitivity to cisplatin in Hep-2 laryngeal carcinoma cells and whether the inhibition of GLUT-1 and the PI3K/Akt pathways enhances the chemosensitivity of Hep-2 cells.

Method

The effects of inhibiting GLUT-1 by a GLUT-1 siRNA, and PI3K/Akt by Ly294002, on cisplatin-induced effects were assessed in vitro.

Results

GLUT-1 siRNA and cisplatin showed a synergistic effect in inhibiting the proliferation of Hep-2. LY294002 and cisplatin also showed a synergistic effect in inhibiting the proliferation of Hep-2. GLUT-1 siRNA, LY294002 and cisplatin effectively inhibited the mRNA expressions and protein expressions of GLUT-1, Akt, PI3k and HIF-1α in Hep-2 cells. Furthermore, GLUT-1 siRNA and cisplatin demonstrated a synergism to inhibit the mRNA expression of HIF-1α. Moreover, it was found in this study that GLUT-1 siRNA, LY294002 and cisplatin induced the suppression of the cell cycle at G1/G2 and the increasing of apoptosis in Hep-2 cells.

Conclusion

This study showed that inhibiting GLUT-1, by a GLUT-1 siRNA and inhibiting PI3K/Akt by Ly294002, could suppress the proliferation of Hep-2 alone and together with cisplatin synergistically, which demonstrated the potentials to treat laryngeal carcinoma in the future therapy. Additionally, the synergistic effect between LY294002 and cisplatin to suppress the proliferation of Hep-2 might not be from GLUT-1, Akt, PI3k and HIF-1α; the synergistic effect between GLUT-1 siRNA and cisplatin to suppress the proliferation of Hep-2 might not be from GLUT-1, Akt and PI3k and might be more or less related to HIF-1α.

Clinicopathological and prognostic significance of GLUT1 in breast cancer: A meta-analysis

BACKGROUND

Previous studies examining the prognostic value of glucose transporter 1 in breast cancer have yielded inconsistent results. We, therefore, performed a meta-analysis to clarify this issue.

METHODS

The research was reported according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Relevant studies were retrieved from PubMed, Web of Science, EMBASE, and Cochrane library.

RESULTS

A total of 7 reports with 1861 patients were finally chosen. GLUT1 overexpression was found to be associated with high histological grade (OR = 3.74, 95% CI = 2.45-5.69, P < .001), negative PR status (OR = 0.33, 95% CI = 0.22-0.49, P < .001), and negative estrogen receptor (ER) status (OR = 0.27, 95% CI = 0.17-0.42, P < .001). However, no significant correlation was seen between GLUT1 levels and presence of lymph node metastasis, tumor size or the status of human epidermal growth factor receptor 2 (HER2). Overexpression of GLUT1 also correlated with a poor overall survival (hazard ratio [HR] = 1.65, 95% confidence interval [CI] = 1.17-2.31, P = .004) and disease-free survival (HR = 2.35, 95% CI = 1.4-3.94, P < .001). No evidence of significant publication bias was found.

CONCLUSION

This meta-analysis indicates that GLUT1 expression is associated with poor prognostic and a series of clinicopathological features in breast cancer. GLUT1 might be a potential biomarker and therapeutic target in breast cancer.

Marked accumulation of fluorodeoxyglucose and inflammatory cells expressing glucose transporter-3 in immunoglobulin G4-related autoimmune hepatitis

Immunoglobulin (Ig)G4-related autoimmune hepatitis (AIH) is a recently proposed subtype that responds well to steroid treatment; however, its pathogenesis remains unclear. We report here a 65-year-old Japanese woman with skin itching and lip swelling. She had liver injury with jaundice, which persisted despite stopping anti-allergic agents. Blood chemistry revealed highly elevated serum IgG and IgG4 (535 mg/dL) levels, and positive anti-nuclear antibody. The diagnosis of AIH was based on liver biopsy. Notably, the IgG4⁺ /IgG⁺ cell ratio was 85%. On fluorodeoxyglucose (FDG) positron emission tomography/computed tomography, robust signal intensity was found in the liver, and in enlarged lymph nodes and salivary glands with confirmed IgG4⁺ cell infiltration. Immunofluorescence analysis of the liver biopsy specimen indicated clear expression of glucose transporter-3 (Glut-3) in IgG4⁺ inflammatory cells infiltrating into the portal area. This is the first report of simultaneous strong accumulation of FDG and Glut-3 expression in IgG4-related AIH, which might aid in elucidating the pathogenesis of this disease.

CDK8 Kinase Activity Promotes Glycolysis

Aerobic glycolysis, also known as the Warburg effect, is a hallmark of cancerous tissues. Despite its importance in cancer development, our understanding of mechanisms driving this form of metabolic reprogramming is incomplete. We report here an analysis of colorectal cancer cells engineered to carry a single point mutation in the active site of the Mediator-associated kinase CDK8, creating hypomorphic alleles sensitive to bulky ATP analogs. Transcriptome analysis revealed that CDK8 kinase activity is required for the expression of many components of the glycolytic cascade. CDK8 inhibition impairs glucose transporter expression, glucose uptake, glycolytic capacity and reserve, as well as cell proliferation and anchorage-independent growth, both in normoxia and hypoxia. Importantly, CDK8 impairment sensitizes cells to pharmacological glycolysis inhibition, a result reproduced with Senexin A, a dual inhibitor of CDK8/CDK19. Altogether, these results contribute to our understanding of CDK8 as an oncogene, and they justify investigations to target CDK8 in highly glycolytic tumors.

The prognostic value of GLUT1 in cancers: a systematic review and meta-analysis

Increased glycolysis is one of the hallmarks of cancer. The abnormal expression of glucose transporter 1 (GLUT1) was reported to be associated with resistance to current therapy and poor prognosis. Numerous studies have investigated the correlation between GLUT1 expression and prognosis in cancers, but the conclusions are still controversial. Here, we conducted a meta-analysis to explore the association between GLUT1 and survival in human cancers. PubMed, Springer, Medline, and Cochrane Library were searched carefully to identify eligible studies evaluating prognostic value of GLUT1 in cancers. Twenty-seven studies with 4079 patients were included in the present study. Our pooled results identified that increased expression of GLUT1 was associated with unfavorable overall survival (HR = 1.780, 95% CI = 1.574–.013, p < 0.001)) and poorer disease-free survival (HR = 1.95, 95% CI = 1.229–3.095, p = 0.003). Furthermore, overexpression of GLUT1 linked with poor differentiated tumors (RR = 1.380, 95% CI = 1.086–1.755, p = 0.009; I² = 72.0%, p < 0.001), positive lymph node metastasis (RR = 1.395, 95% CI = 1.082–1.799, p = 0.010; I² = 70.8%, p = 0.002) and larger tumor size (RR = 1.405, 95% CI = 1.231–1.603, p < 0.001; I² = 37.3%, p = 0.093). This systematic review and meta-analysis indicated that the GLUT1 may serve as an ideal prognostic biomarker in various cancers.

How the Warburg effect supports aggressiveness and drug resistance of cancer cells?

Cancer cells employ both conventional oxidative metabolism and glycolytic anaerobic metabolism. However, their proliferation is marked by a shift towards increasing glycolytic metabolism even in the presence of O₂ (Warburg effect). HIF1, a major hypoxia induced transcription factor, promotes a dissociation between glycolysis and the tricarboxylic acid cycle, a process limiting the efficient production of ATP and citrate which otherwise would arrest glycolysis. The Warburg effect also favors an intracellular alkaline pH which is a driving force in many aspects of cancer cell proliferation (enhancement of glycolysis and cell cycle progression) and of cancer aggressiveness (resistance to various processes including hypoxia, apoptosis, cytotoxic drugs and immune response). This metabolism leads to epigenetic and genetic alterations with the occurrence of multiple new cell phenotypes which enhance cancer cell growth and aggressiveness. In depth understanding of these metabolic changes in cancer cells may lead to the development of novel therapeutic strategies, which when combined with existing cancer treatments, might improve their effectiveness and/or overcome chemoresistance.

Glucose transporter-1 as an independent prognostic marker for cancer: a meta-analysis

Objective

Glucose transporter-1 (GLUT-1) as the major glucose transporter present in human cells is found overexpressed in a proportion of human malignancies. This meta-analysis is attempted to assess the prognostic significance of GLUT-1 for survival in various cancers.

Materials and Methods

We conducted an electronic search using the databases PubMed, Embase and Web of Science, from inception to Oct 20th, 2016. Pooled hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated.

Results

Fourty-one studies with a total of 4794 patients were included. High GLUT-1 expression was significantly associated with poorer prognosis [overall survival: HR = 1.833 (95% CI: 1.597–2.069, P < 0.0001); disease-free survival: HR = 1.838 (95% CI: 1.264–2.673, P < 0.0001); progression-free survival: HR = 2.451 (95% CI: 1.668–3.233, P < 0.0001); disease specific survival: HR = 1.96 (95% CI: 1.05–2.871, P < 0.0001)].

Conclusions

High GLUT-1 expression may be an independent prognostic marker to predict poor survival in various types of cancers. Further clinical trials with high quality need to be conducted to confirm our conclusion.