Glucose transporter-1 as a new therapeutic target in laryngeal carcinoma

Identification of new head and neck squamous cell carcinoma molecular imaging targets

OBJECTIVES

Intraoperative fluorescence imaging (FI) of head and neck squamous cell carcinoma (HNSCC) is performed to identify tumour-positive surgical margins, currently using epidermal growth factor receptor (EGFR) as imaging target. EGFR, not exclusively present in HNSCC, may result in non-specific tracer accumulation in normal tissues. We aimed to identify new potential HNSCC FI targets.

MATERIALS AND METHODS

Publicly available transcriptomic data were collected, and a biostatistical method (Transcriptional Adaptation to Copy Number Alterations (TACNA)-profiling) was applied. TACNA-profiling captures downstream effects of CNAs on mRNA levels, which may translate to protein-level overexpression. Overexpressed genes were identified by comparing HNSCC versus healthy oral mucosa. Potential targets, selected based on overexpression and plasma membrane expression, were immunohistochemically stained. Expression was compared to EGFR on paired biopsies of HNSCC, adjacent macroscopically suspicious mucosa, and healthy mucosa.

RESULTS

TACNA-profiling was applied on 111 healthy oral mucosa and 410 HNSCC samples, comparing expression levels of 19,635 genes. The newly identified targets were glucose transporter-1 (GLUT-1), placental cadherin (P-cadherin), monocarboxylate transporter-1 (MCT-1), and neural/glial antigen-2 (NG2), and were evaluated by IHC on samples of 31 patients. GLUT-1 was expressed in 100 % (median; range: 60-100 %) of tumour cells, P-cadherin in 100 % (50-100 %), EGFR in 70 % (0-100 %), MCT-1 in 30 % (0-100 %), and NG2 in 10 % (0-70 %). GLUT-1 and P-cadherin showed higher expression than EGFR (p < 0.001 and p = 0.015).

CONCLUSIONS

The immunohistochemical confirmation of TACNA-profiling results showed significantly higher GLUT-1 and P-cadherin expression than EGFR, warranting further investigation as HNSCC FI targets.

Deciphering the Mysterious Relationship between the Cross-Pathogenetic Mechanisms of Neurodegenerative and Oncological Diseases

The relationship between oncological pathologies and neurodegenerative disorders is extremely complex and is a topic of concern among a growing number of researchers around the world. In recent years, convincing scientific evidence has accumulated that indicates the contribution of a number of etiological factors and pathophysiological processes to the pathogenesis of these two fundamentally different diseases, thus demonstrating an intriguing relationship between oncology and neurodegeneration. In this review, we establish the general links between three intersecting aspects of oncological pathologies and neurodegenerative disorders, i.e., oxidative stress, epigenetic dysregulation, and metabolic dysfunction, examining each process in detail to establish an unusual epidemiological relationship. We also focus on reviewing the current trends in the research and the clinical application of the most promising chemical structures and therapeutic platforms that have a modulating effect on the above processes. Thus, our comprehensive analysis of the set of molecular determinants that have obvious cross-functional pathways in the pathogenesis of oncological and neurodegenerative diseases can help in the creation of advanced diagnostic tools and in the development of innovative pharmacological strategies.

The Effect of GLUT1 and HIF-1α Expressions on Glucose Uptake and Patient Survival in Non-Small-Cell Lung Carcinoma

Lung cancer is the second-most-common cancer while being the leading cause of cancer deaths worldwide. It has been found that glucose transporter 1 (GLUT1) and hypoxia-inducible factor 1α (HIF-1α) are overexpressed in various malignancies and that they correlate with the maximum standard uptake values (SUVmax) on 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG PET/CT) and poor prognosis. In this study, we aim to evaluate the relationship between the SUVmax, GLUT1, and HIF-1α expression with primary tumor size, histological type, lymph node metastases, and patient survival. Of the 48 patients with non-small-cell lung cancer, those with squamous cell carcinomas (SCCs) had significantly higher GLUT1 and HIF-1α immunohistochemical expressions in comparison to adenocarcinomas (ACs), while there was no statistically significant difference in FDG accumulation between them. No significant correlation was noted between either GLUT1 or HIF-1α protein expression and FDG uptake and overall survival. However, an analysis of tumor transcriptomics showed a significant difference in overall survival depending on mRNA expression; patients with SCC and high HIF-1α levels survived longer compared to those with low HIF-1α levels, while patients with AC and low GLUT1 levels had a higher average survival time than those with high GLUT1 levels. Further studies are needed to determine the prognostic value of the expression of these factors depending on the histologic type.

GLUT1 and PKM2 may be useful prognostic predictors in patients with non‑small cell lung cancer following curative R0 resection

Lung cancer has a poor prognosis despite recent progresses being made regarding its treatment. In addition, there is a paucity of reliable and independent prognostic predictors for non-small cell lung cancer (NSCLC) following curative resection. Glycolysis is associated with the malignancy and proliferation of cancer cells. Glucose transporter 1 (GLUT1) promotes glucose uptake, whereas pyruvate kinase M2 (PKM2) promotes anaerobic glycolysis. The present study aimed to evaluate the relationship between the expression of GLUT1 and PKM2 and the clinicopathological features of patients with NSCLC, and to identify a reliable prognostic factor for NSCLC following curative resection. Patients with NSCLC who underwent curative surgery were retrospectively enrolled to the present study. GLUT1 and PKM2 expression was assessed using immunohistochemistry. Subsequently, the association between the clinicopathological features of patients with NSCLC and the expression of GLUT1 and PKM2 was assessed. Of the 445 patients with NSCLC included in the present study, 65 (15%) were positive for both GLUT1 and PKM2 expression (G+/P+ group). GLUT1 and PKM2 positivity was significantly associated with sex, absence of adenocarcinoma, lymphatic invasion and pleural invasion. Furthermore, patients with NSCLC in the G+/P+ group presented significantly poorer survival rates than those expressing other markers. G+/P+ expression was significantly associated with poor disease-free survival. In conclusion, the findings of the present study indicated that the combination of GLUT1 and PKM2 may be considered a reliable prognostic factor for patients with NSCLC following curative resection, especially in patients with stage I NSCLC.

Usefulness of pyruvate dehydrogenase-E1α expression to determine SUVmax cut-off value of [18F]FDG-PET for predicting lymph node metastasis in lung cancer

A more accurate cut-off value of maximum standardized uptake value (SUVmax) in [¹⁸F]fluorodeoxyglucose positron emission tomography/computed tomography ([¹⁸F]FDG-PET/CT) is necessary to improve preoperative nodal staging in patients with lung cancer. Overall, 223 patients with lung cancer who had undergone [¹⁸F]FDG-PET/CT within 2 months before surgery were enrolled. The expression of glucose transporter-1, pyruvate kinase-M2, pyruvate dehydrogenase-E1α (PDH-E1α), and carbonic anhydrase-9 was evaluated by immunohistochemistry. Clinicopathological background was retrospectively investigated. According to PDH-E1α expression in primary lesion, a significant difference (p = 0.021) in SUVmax of metastatic lymph nodes (3.0 with PDH-positive vs 4.5 with PDH-negative) was found, but not of other enzymes. When the cut-off value of SUVmax was set to 2.5, the sensitivity and specificity were 0.529 and 0.562, respectively, and the positive and negative predictive values were 0.505 and 0.586, respectively. However, when the cut-off value of SUVmax was set according to PDH-E1α expression (2.7 with PDH-positive and 3.2 with PDH-negative), the sensitivity and specificity were 0.441 and 0.868, respectively, and the positive and negative predictive values were 0.738 and 0.648, respectively. The SUVmax cut-off value for metastatic lymph nodes depends on PDH-E1α expression in primary lung cancer. The new SUVmax cut-off value according to PDH-E1α expression showed higher specificity for [¹⁸F]FDG-PET in the diagnosis of lymph node metastasis.

Warburg Effect Revisited: Embodiment of Classical Biochemistry and Organic Chemistry. Current State and Prospects

The Nobel Prize Winner (1931) Dr. Otto H. Warburg had established that the primary energy source of the cancer cell is aerobic glycolysis (the Warburg effect). He also postulated the hypothesis about "the prime cause of cancer", which is a matter of debate nowadays. Contrary to the hypothesis, his discovery was recognized entirely. However, the discovery had almost vanished in the heat of battle about the hypothesis. The prime cause of cancer is essential for the prevention and diagnosis, yet the effects that influence tumor growth are more important for cancer treatment. Due to the Warburg effect, a large amount of data has been accumulated on biochemical changes in the cell and the organism as a whole. Due to the Warburg effect, the recovery of normal biochemistry and oxygen respiration and the restoration of the work of mitochondria of cancer cells can inhibit tumor growth and lead to remission. Here, we review the current knowledge on the inhibition of abnormal glycolysis, neutralization of its consequences, and normalization of biochemical parameters, as well as recovery of oxygen respiration of a cancer cell and mitochondrial function from the point of view of classical biochemistry and organic chemistry.

Ubiquitination regulation of aerobic glycolysis in cancer

Aerobic glycolysis, or the Warburg effect, is regarded as a critical part of metabolic reprogramming and plays a crucial role in the occurrence and development of tumours. Ubiquitination and deubiquitination, essential post-translational modifications, have attracted increasing attention with regards to the regulation of metabolic reprogramming in cancer. However, the mechanism of ubiquitination in glycolysis remains unclear. In this review, we discuss the roles of ubiquitination and deubiquitination in regulating glycolysis, and their involvement in regulating important signalling pathways, enzymes, and transcription factors. Focusing on potential mechanisms may provide novel strategies for cancer treatment.

The Expression and Survival Significance of Glucose Transporter-1 in Pancreatic Cancer: Meta-Analysis, Bioinformatics Analysis and Retrospective Study

To explore the expression profile and prognostic relevance of GLUT-1 in pancreatic cancer, a meta-analysis, bioinformatics analysis based on Gene Expression Omnibus (GEO), Oncomine dataset and The Cancer Genome Atlas (TCGA) database, and immunohistochemistry in tumor and normal tissue from 88 pancreatic ductal adenocarcinoma (PDAC) patients were performed. GLUT-1 was significantly overexpressed in pancreatic cancer but it could not be a significant biomarker for prognosis. TNM stage and pathological grade could be biomarker of poor prognosis of patients with pancreatic cancer.

Effect of GLUT1 Inhibition and Autophagy Modulation on the Growth and Migration of Laryngeal Carcinoma Stem Cells Under Hypoxic and Low-Glucose Conditions

Background

Enhanced glucose uptake and autophagy are means by which cells adapt to stressful microenvironments. In this study, we investigated the roles of glucose transporter-1 (GLUT-1) and autophagy in laryngeal carcinoma stem cells under hypoxic and low-glucose conditions.

Materials and Methods

CD133-positive Tu212 laryngeal carcinoma stem cells were purified by magnetic-activated cell sorting and subjected to hypoxic and/or low-glucose conditions. Proliferation was evaluated using a cell-counting kit and a clone-formation assay, and migration capability was measured through a Transwell assay. Autophagy was assessed using transmission electron microscopy. Gene silencing was monitored using shRNA technology and autophagy regulation was manipulated using rapamycin, 3-MA, or chloroquine. Gene expression levels were evaluated by quantitative reverse transcription-polymerase chain reaction and protein levels were assessed via Western blotting.

Results

Compared to CD133-negative cells, CD133-positive cells showed increased proliferation and migration capabilities, and reduced apoptosis, under hypoxic or low-glucose conditions. CD133-positive cells also showed increased expression of GLUT-1 and autophagy activity. Finally, GLUT-1 knockdown or autophagy inhibition reduced the proliferation and migration of CD133-positive laryngeal carcinoma stem cells.

Conclusion

Enhanced glucose uptake and autophagy maintain the tumor behaviors of CD133-positive laryngeal carcinoma stem cells under hypoxic and low-glucose conditions.

Improving the therapeutic ratio of radiotherapy against radioresistant cancers: Leveraging on novel artificial intelligence-based approaches for drug combination discovery

Despite numerous advances in cancer radiotherapy, tumor radioresistance remain one of the major challenges limiting treatment efficacy of radiotherapy. Conventional strategies to overcome radioresistance involve understanding the underpinning molecular mechanisms, and subsequently using combinatorial treatment strategies involving radiation and targeted drug combinations against these radioresistant tumors. These strategies exploit and target the molecular fingerprint and vulnerability of the radioresistant clones to achieve improved efficacy in tumor eradication. However, conventional drug-screening approaches for the discovery of new drug combinations have been proven to be inefficient, limited and laborious. With the increasing availability of computational resources in recent years, novel approaches such as Quadratic Phenotypic Optimization Platform (QPOP), CURATE.AI and Drug Combination and Prediction and Testing (DCPT) platform have emerged to aid in drug combination discovery and the longitudinally optimized modulation of combination therapy dosing. These platforms could overcome the limitations of conventional screening approaches, thereby facilitating the discovery of more optimal drug combinations to improve the therapeutic ratio of combinatorial treatment. The use of better and more accurate models and methods with rapid turnover can thus facilitate a rapid translation in the clinic, hence, resulting in a better patient outcome. Here, we reviewed the clinical observations, molecular mechanisms and proposed treatment strategies for tumor radioresistance and discussed how novel approaches may be applied to enhance drug combination discovery, with the aim to further improve the therapeutic ratio and treatment efficacy of radiotherapy against radioresistant cancers.

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.

Roles of GLUT-1 and HK-II expression in the biological behavior of head and neck cancer

The Warburg effect plays an important role in the proliferation and invasion of malignant tumors. Glucose transporter 1 and hexokinase II are two key energy transporters involved in mediating the Warburg effect. This review will analyze the mechanisms of these two markers in their effects on the biological behavior of head and neck cancer.

Construction of a GLUT-1 and HIF-1α gene knockout cell model in HEp-2 cells using the CRISPR/Cas9 technique

Background

Glucose transporter (GLUT)-mediated glucose uptake is an important process in the development of laryngeal carcinoma, one of the most common malignancies of the head and neck. GLUT-1, together with HIF-1α, is also an indicator of hypoxia. Both proteins play a critical role in glucose uptake and glycolysis in laryngeal carcinoma cells under hypoxic stress. A double gene knockout model in which HIF-1α and GLUT-1 are no longer expressed can provide important information about carcinogenesis in laryngeal carcinoma.

Purpose

In this study we used the CRISPR/Cas 9 system to induce HIF-1α and GLUT-1 double gene knockout in HEp-2 cells and then used the knocked-out cells to study the role of these markers in laryngeal carcinoma, including in chemoradioresistance.

Methods

High-grade small-guide RNAs (sgRNAs) of HIF-1α and GLUT-1 were designed using an online tool and inserted into the pUC57-T7-gRNA vector. The recombinant plasmids were transfected into HEp-2 cells and positive cells were screened using the dilution method. Gene mutation and expression were determined by sequence analysis and immunoblotting.

Results

In HIF-1α and GLUT-1 double gene knockout HEp-2 cells, a 171-bp deletion in the HIF-1α genomic sequence was detected, whereas multiple base insertions resulted in frameshift mutations in the GLUT-1 gene. Neither HIF-1α nor GLUT-1 protein was expressed in positive cells. The proliferation, migration, and invasion of HEp-2 cells were significantly decreased afterward. The possible mechanism may be that the inhibition PI3K/AKT/mTOR pathway by HIF-1α and GLUT-1 double gene knockout using CRISPR/Cas9 technique lead to reduction of glucose uptake and lactic acid generation.

Conclusion

Our HIF-1α and GLUT-1 double gene knockout HEp-2 cell model, obtained using a CRISPR/Cas9-based system, may facilitate studies of the pathogenesis of laryngeal carcinoma.

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.

Role of metabolism in cancer cell radioresistance and radiosensitization methods

BACKGROUND

Radioresistance is a major factor leading to the failure of radiotherapy and poor prognosis in tumor patients. Following the application of radiotherapy, the activity of various metabolic pathways considerably changes, which may result in the development of resistance to radiation.

MAIN BODY

Here, we discussed the relationships between radioresistance and mitochondrial and glucose metabolic pathways, aiming to elucidate the interplay between the tumor cell metabolism and radiotherapy resistance. In this review, we additionally summarized the potential therapeutic targets in the metabolic pathways.

SHORT CONCLUSION

The aim of this review was to provide a theoretical basis and relevant references, which may lead to the improvement of the sensitivity of radiotherapy and prolong the survival of cancer patients.

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.

Poly((D,L)lactic-glycolic)acid-star glucose nanoparticles for glucose transporter and hypoglycemia-mediated tumor targeting

Poly((D,L)lactic-glycolic)acid-star glucose (PLGA-Glc) polymer-based nanoparticles (NPs) were fabricated for tumor-targeted delivery of docetaxel (DCT). NPs with an approximate mean diameter of 241 nm, narrow size distribution, negative zeta potential, and spherical shape were prepared. A sustained drug release pattern from the developed NPs was observed for 13 days. Moreover, drug release from PLGA-Glc NPs at acidic pH (endocytic compartments and tumor regions) was significantly improved compared with that observed at physiological pH (normal tissues and organs). DCT-loaded PLGA-Glc NPs (DCT/PLGA-Glc NPs) exhibited an enhanced antiproliferation efficiency rather than DCT-loaded PLGA NPs (DCT/PLGA NPs) in Hep-2 cells, which can be regarded as glucose transporters (GLUTs)-positive cells, at ≥50 ng/mL DCT concentration range. Under glucose-deprived (hypoglycemic) conditions, the cellular uptake efficiency of the PLGA-Glc NPs was higher in Hep-2 cells compared to that observed in PLGA NPs. Cy5.5-loaded NPs were prepared and injected into a Hep-2 tumor-xenografted mouse model for in vivo near-infrared fluorescence imaging. The PLGA-Glc NPs group exhibited higher fluorescence intensity in the tumor region than the PLGA NPs group. These results imply that the PLGA-Glc NPs have active tumor targeting abilities based on interactions with GLUTs and the hypoglycemic conditions in the tumor region. Therefore, the developed PLGA-Glc NPs may represent a promising tumor-targeted delivery system for anticancer drugs.

Differential Expression of Glycolysis-Related Proteins in Follicular Neoplasms versus Hürthle Cell Neoplasms: A Retrospective Analysis

Purpose

Although currently classified as variants of follicular neoplasms (FNs), Hürthle cell neoplasms (HCNs) exhibit distinct biological characteristics. Hence, the metabolism of both neoplasms may also be different. The aims of this study were to investigate and compare the expression of glycolysis-related proteins in HCNs and FNs and to determine the clinical implications of such expression.

Methods

Tissue microarrays were constructed with 265 samples of FNs (112 follicular carcinomas (FCs) and 153 follicular adenomas (FAs)) as well as 108 samples of HCNs (27 Hürthle cell carcinomas (HCCs) and 81 Hürthle cell adenomas (HCAs)). Immunohistochemical staining for the glycolysis-related molecules Glut-1, hexokinase II, CAIX, and MCT4 was performed.

Results

The expression levels of Glut-1, hexokinase II, CAIX, and MCT4 were significantly higher in HCNs than in FNs (p < 0.001). Glut-1, hexokinase II, CAIX, and MCT4 expression levels were highest in HCC, followed by HCA, FC, and FA (all p < 0.001). In HCC, hexokinase II positivity was associated with large tumor size (>4 cm) (p = 0.046), CAIX positivity with vascular invasion (p = 0.005), and MCT4 positivity with extrathyroidal extension (p = 0.030).

Conclusion

The expression levels of the glycolysis-related proteins Glut-1, hexokinase II, CAIX, and MCT4 were higher in HCNs than in FNs and in HCCs than in HCAs.

Interplay Between Metabolism and Oncogenic Process: Role of microRNAs

Cancer is a complex disease that arises from the alterations in the composition and regulation of several genes leading to the disturbances in signaling pathways, resulting in the dysregulation of cell proliferation and death as well as the ability of transformed cells to invade the host tissue and metastasize. It is increasingly becoming clear that metabolic reprograming plays a critical role in tumorigenesis and metastasis. Therefore, targeting this phenotype is considered as a promising approach for the development of therapeutics and adjuvants. The process of metabolic reprograming is linked to the activation of oncogenes and/or suppression of tumor suppressor genes, which are further regulated by microRNAs (miRNAs) that play important roles in the interplay between oncogenic process and metabolic reprograming. Looking at the advances made in the recent past, it appears that the translation of knowledge from research in the areas of metabolism, miRNA, and therapeutic response will lead to paradigm shift in the management of this disease.

Co-Inhibition of GLUT-1 Expression and the PI3K/Akt Signaling Pathway to Enhance the Radiosensitivity of Laryngeal Carcinoma Xenografts In Vivo

In the present study, we investigated the role of GLUT-1 and PI3K/Akt signaling in radioresistance of laryngeal carcinoma xenografts. Volume, weight, radiosensitization, and the rate of inhibition of tumor growth in the xenografts were evaluated in different groups. Apoptosis was evaluated by TUNEL assay. In addition, mRNA and protein levels of GLUT-1, p-Akt, and PI3K in the xenografts were measured. Treatment with LY294002, wortmannin, wortmannin plus GLUT-1 AS-ODN, and LY294002 plus GLUT-1 AS-ODN after X-ray irradiation significantly reduced the size and weight of the tumors, rate of tumor growth, and apoptosis in tumors compared to that observed in the 10-Gy group (p<0.05). In addition, mRNA and protein expression of GLUT-1, p-Akt, and PI3K was downregulated. The E/O values of LY294002, LY294002 plus GLUT-1 AS-ODN, wortmannin, and wortmannin plus GLUT-1 AS-ODN were 2.7, 1.1, 1.8, and 1.8, respectively. Taken together, these data indicate that GLUT-1 AS-ODN as well as the inhibitors of PI3K/Akt signaling may act as radiosensitizers of laryngeal carcinoma in vivo.

Inhibiting GLUT-1 expression and PI3K/Akt signaling using apigenin improves the radiosensitivity of laryngeal carcinoma in vivo

Hypoxia is an important factor in radioresistance of laryngeal carcinoma. Glucose transporter-1 (GLUT-1) is an important hypoxic marker in malignant tumors, including laryngeal carcinoma. Apigenin is a natural phytoestrogen flavonoid that has potential anticancer effects. Various studies have reported that the effects of apigenin on lowering GLUT-1 expression were involved in downregulation of the PI3K/Akt pathway. Thus, apigenin may improve the radiosensitivity of laryngeal carcinoma by suppressing the expression of GLUT-1 via the PI3K/Akt pathway. The effect of GLUT-1 and PI3K/Akt pathway-related factor expressions by apigenin or antisense oligonucleotides (AS-ODNs) on the radiosensitivity of laryngeal carcinoma in vivo was assessed. The xenograft volume, xenograft weight and apoptosis detection were performed to determine radiosensitivity. The results showed that apigenin or apigenin plus GLUT-1 AS-ODNs improved the radiosensitivity of xenografts. Apigenin or apigenin plus GLUT-1 reduced the expression of GLUT-1, Akt, and PI3K mRNA after X-ray radiation. We found similar results at the protein level. The results suggest that the effects of apigenin on inhibiting xenograft growth and enhancing xenograft radiosensitivity may be associated with suppressing the expression of GLUT-1 via the PI3K/Akt pathway. In addition, apigenin may enhance the effects of GLUT-1 AS-ODNs via the same mechanism.

Distribution of Hypoxia-Inducible Factor-1α and Glucose Transporter-1 in Human Tongue Cancers

PURPOSE

Oral squamous cell carcinomas have the potential for rapid and unlimited growth. Therefore, hypoxic tissue areas are common in these malignant tumors and contribute to cancer progression, therapy resistance, and poor outcomes. The aim of the present study was to analyze the gene product distribution of hypoxia-inducible factor-1α (HIF-1α) and glucose transporter-1 (GLUT-1) in cases of tongue squamous cell carcinoma (TSCC) and to identify a preliminary correlation between these proteins and clinical staging and Brynes's histologic grading system (HGS).

MATERIALS AND METHODS

The sample included 57 cases of TSCC. Histologic sections of 3 μm were submitted to the immunoperoxidase method and semiquantitative analysis. The association between HIF-1α and GLUT-1 expression in TSCC and the clinical stage and the HGS of Bryne (1998) was evaluated using the χ(2) test, with the significance level set at 0.05 (α = 0.05).

RESULTS

HIF-1α was mainly expressed in the nucleus/cytoplasm of neoplastic cells, most specimens exhibited diffuse staining in neoplastic cells (84.2%), and focal staining was only observed in perinecrotic areas (15.8%). GLUT-1 was expressed in the cytoplasm and membrane of malignant cells, and diffuse staining was observed in all cases. The intensity of HIF-1α expression correlated significantly with clinical stage (P = .011) and HGS (P = .002). A significant association was observed between the distribution of HIF-1α expression and metastasis (P = .040). Immunoexpression of GLUT-1 correlated significantly with clinical stage (P = .002) and HGS (P = .000). GLUT-1 expression in the peripheral island was predominant in most low-grade tumors (78.6%); in the high-grade cases, the expression prevailed in the location center/periphery (55.8%). Comparison of the location of the tumor island in the different histologic grades showed a statistically significant difference (P = .025).

CONCLUSION

The expression of HIF and GLUT proteins within TSCC appears to be associated with disease stage, grade, and the presence of metastases. Additional studies are needed to evaluate the diagnostic and prognostic uses of these proteins in the treatment of TSCC.

Does expression of glucose transporter protein-1 relate to prognosis and angiogenesis in osteosarcoma?

BACKGROUND

The survival of patients who present with nonmetastatic extremity osteosarcoma has dramatically improved, but there are some patients who do not respond to chemotherapy. The ability to identify patients with a poorer prognosis might allow us to target different therapy for these patients. Glucose transporter protein-1 (Glut-1), one of the key factors in glucose metabolism, has been reported to be an independent prognostic factor in various tumors. However, little is known about the role of the Glut-1 pathway in osteosarcoma.

QUESTIONS/PURPOSES

We asked (1) if Glut-1 expression is a prognostic marker for survival in patients with osteosarcoma, and (2) if there is a relationship between Glut-1 expression and tumor angiogenesis.

PATIENTS AND METHODS

Thirty-seven patients with resectable high-grade osteosarcomas treated between 1982 and 2007 were reviewed retrospectively. Patients were excluded if representative biopsy material and followup data were not available. The expression of Glut-1 and the number of CD34-positive microvessels for angiogenic activity were measured immunohistochemically. The median followup was 6 years 6 months (range, 11-211 months). Survival analyses were evaluated using the Kaplan-Meier method and the Cox proportional hazards model. The association between Glut-1 expression and microvessel density was analyzed using Student's t-test and chi-square test. For 12 (32.4%) of 37 patients with osteosarcoma, the expression of Glut-1 was positive, with four patients (10.8%) showing strong expression of Glut-1 protein.

RESULTS

The expression of Glut-1 correlated with a shorter disease-free survival period (relative risk, 20.13; 95% CI, 1.77-229.3; p=0.0016). The microvessel density mean value of positive Glut-1 expression (mean±SD, 26.5±19.4) was lower than that of negative expression (mean±SD, 46.4±35.3; Student's t-test, p=0.038). When more than 50 was defined as a high microvessel density, positive expression of Glut-1 was significantly associated with low microvessel density (chi-square test, p=0.049).

CONCLUSIONS

These findings indicate that Glut-1 is a potential predictor of survival in patients with osteosarcoma and that glucose metabolism may be negatively associated with angiogenesis. If substantiated in larger numbers of patients, these findings might stimulate the development of novel treatments for patients with a poorer prognosis.

LEVEL OF EVIDENCE

Level III, prognostic study. See the Instructions for Authors for a complete description of levels of evidence.

Roles of glucose transporter-1 and the phosphatidylinositol 3‑kinase/protein kinase B pathway in cancer radioresistance (review)

The mechanisms underlying cancer radioresistance remain unclear. Several studies have found that increased glucose transporter‑1 (GLUT‑1) expression is associated with radioresistance. Recently, the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway was reported to be involved in the control of GLUT‑1 trafficking and activity. Activation of the PI3K/Akt pathway may itself be associated with cancer radioresistance. Thus, increasing attention has been devoted to the effects of modifying the expression of GLUT‑1 and the PI3K/Akt pathway on the increase in the radiosensitivity of cancer cells. This review discusses the importance of the association between elevated expression of GLUT‑1 and activation of the PI3K/Akt pathway in the development of radioresistance in cancer.

Contribution of TIP30 to chemoresistance in laryngeal carcinoma

Laryngeal squamous cell carcinoma (LSCC) is one of the most common carcinomas of the head and neck. Despite advances in diagnosis and treatment, the survival of patients with LSCC has not improved in the past two decades. TIP30, a newly identified tumour suppressor, appears to be involved in multiple processes during tumour development. Here, we investigated the involvement of TIP30 in chemoresistance of LSCC in vitro and in vivo. We showed that TIP30 expression decreased significantly in drug-selected cells (DSCs) of laryngeal carcinoma. Suppressing TIP30 enhanced resistance capability to multiple chemotherapy drugs, cell proliferation and self-renewal in Hep2 cells. Additionally, decreased self-renewal capacity and chemotherapeutic resistance were observed in DSCs overexpressing TIP30. Furthermore, TIP30 negatively regulated tumourigenesis and chemoresistance in LSCC cells subcutaneously transplanted into nude mice. Moreover, decreased TIP30 expression contributed to chemoresistance, self-renewal and proliferation of LSCC cells via nuclearlisation of β-catenin, a cell–cell adhesion and stem cell renewal regulator. Consistently, Kaplan–Meier and Cox proportional hazards regression modelling analyses showed that decreased TIP30 expression independently predicted poor survival in patients with LSCC. Taken together, our results reveal that TIP30 has a crucial role in chemoresistance of LSCC through the AKT/glycogen synthase kinase-3β/β-catenin signalling pathway and may be a promising candidate for improving LSCC chemotherapy.

Anticancer mechanism of apigenin and the implications of GLUT-1 expression in head and neck cancers

Apigenin, a natural phytoestrogen flavonoid, has potential biological effects, including antioxidative, anti-inflammatory and anticancer activities. The mechanisms of anticancer activities of apigenin are unknown. Some studies have found that apigenin inhibits GLUT-1 mRNA and protein expression in cancer cells. Thus, we hypothesized that apigenin exerts similar effects on head and neck cancers through its inhibition of GLUT-1 expression. In this article, we review the anticancer mechanism of apigenin and the implications of GLUT-1 expression in head and neck cancers. In addition, we describe the current state of knowledge about the relationship between apigenin and GLUT-1 expression in head and neck cancers.

Fluorodeoxyglucose uptake in laryngeal carcinoma is associated with the expression of glucose transporter-1 and hypoxia-inducible-factor-1α and the phosphoinositide 3-kinase/protein kinase B pathway

High fluorodeoxyglucose (FDG) uptake by human carcinomas, including head and neck cancers, is associated with a poor prognosis. Glucose transporter-1 (Glut-1) is believed to be an intrinsic marker of hypoxia in malignant tumors. The expression of hypoxia-inducible factor-1α (HIF-1α) and correlated target genes, including Glut-1, is regulated by the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) pathway. However, it remains unclear whether the PI3K/Akt signaling pathway is involved in regulating FDG uptake directly. In the present study, 24 consecutive patients with laryngeal carcinoma were examined pre-operatively and the standardized uptake values (SUV) of the laryngeal carcinomas were determined. Glut-1, HIF-1α, PI3K and phosphorylated-Akt (p-Akt) expression was detected by immunohistochemical staining of paraffin sections from the tumor specimens. Associations among SUV_max, Glut-1, HIF-1α, PI3K and p-Akt protein expression and the other clinical parameters were analyzed. The univariate analyses revealed a significantly shorter survival time along with higher HIF-1α (P=0.018) and PI3K (P=0.008) expression, but the survival time was not significantly correlated with Glut-1 or p-Akt expression. The multivariate analysis demonstrated that higher SUV_max (P=0.043) and PI3K expression (P=0.012) were significantly correlated with a poor survival time. Spearman’s rank analysis showed significant correlations between SUV_max and HIF-1α (r=0.577; P=0.003), PI3K (r=1.0; P<0.0001) and p-Akt (r=0.577; P=0.003) expression. PI3K was associated with poorly- and moderately-differentiated laryngeal carcinoma (P=0.012). In conclusion, a high SUV_max indicates a poor prognosis for laryngeal carcinoma. Also, a high SUV_max may be associated with the increased expression of Glut-1, HIF-1α, PI3K and p-Akt.

Glucose transporters in cancer metabolism

PURPOSE OF REVIEW

Transformed cells exhibit a high rate of glucose consumption beyond that necessary for ATP synthesis. Glucose aids in the generation of biomass and regulates cellular signaling critical for oncogenic progression. A key rate-limiting step in glucose utilization is the transport of glucose across the plasma membrane. This review will highlight key glucose transporters (GLUTs) and current therapies targeting this class of proteins.

RECENT FINDINGS

GLUTs, enabling the facilitative entry of glucose into a cell, are increasingly found to be deregulated in cancer. Although cancer-specific expression patterns for GLUTs are being identified, comprehensive analyses substantiating a role for individual GLUTs are still required. Studies defining GLUTs as being rate-limiting in specific tumor contexts, the identification of GLUT1 inhibitors via synthetic lethality screens, novel engagement of the insulin-responsive GLUT4 in myeloma and identification of GLUT9 being a urate transporter, are key advances underscoring the need for continued investigation of this large and enigmatic class of proteins.

SUMMARY

Tumor cells exhibit elevated levels of glucose uptake, a phenomenon that has been capitalized upon for the prognostic and diagnostic imaging of a wide range of cancers using radio-labeled glucose analogs. We have, however, not yet been able to target glucose entry in a tumor cell-specific manner for therapy. GLUTs have been identified as rate-limiting in specific tumor contexts. The identification and targeting of tumor-specific GLUTs provide a promising approach to block glucose-regulated metabolism and signaling more comprehensively.

Clinicopathological implications of the expression of hypoxia-related proteins in gastric cancer

OBJECTIVES

Tumor hypoxia confers poor prognosis of a wide range of solid tumors due to increased malignancy, increased likelihood of metastasis and treatment resistance. The aim of this study was to assess the significance of the expression of HIF-1α and HIF-1α-inducible proteins in gastric cancer and their impact on prognosis.

MATERIALS AND METHODS

The expression of HIF-1α, GLUT-1, CA-9, and iNOS proteins was analyzed by immunohistochemistry in 193 gastric adenocarcinomas (GAs) and 20 normal gastric mucosa.

RESULTS

HIF-1α, GLUT-1, CA-9 and iNOS were expressed in 52.3%, 43.0%, 57.0%, and 43.0% of GAs, respectively, which are higher than the normal counterparts except for CA-9. HIF-1α expression was positively correlated with the expression of GLUT-1, CA-9 and iNOS. GLUT-1 expression was higher in the intestinal type (p = 0.012); however, iNOS expression was higher in the less-differentiated type and the diffuse type (p = 0.006, p = 0.032, respectively). The expression of HIF-1α and GLUT-1 was significantly correlated with lymph node metastasis (p = 0.009, p = 0.008, respectively), while the expression of GLUT-1 and iNOS was significantly correlated with the depth of invasion and advanced stage (p = 0.044, p = 0.004; p = 0.009, p = 0.008, respectively). Overall survival was shorter in patients with GLUT-1 expression than in those without GLUT-1 expression, which was statistically significant by univariate analysis (p = 0.042). On multivariate analysis, however, stage was determined as the only independent prognostic marker (p < 0.001).

CONCLUSIONS

Our data suggest that overexpression of HIF-1α, GLUT-1, and iNOS may play an important role in gastric cancer progression. GLUT-1 is a potential candidate for predicting patient survival.

Effect of antisense oligodeoxynucleotides glucose transporter-1 on enhancement of radiosensitivity of laryngeal carcinoma

PURPOSE

Laryngeal carcinomas always resist to radiotherapy. Hypoxia is an important factor in radioresistance of laryngeal carcinoma. Glucose transporter-1 (GLUT-1) is considered to be a possible intrinsic marker of hypoxia in malignant tumors. We speculated that the inhibition of GLUT-1 expression might improve the radiosensitivity of laryngeal carcinoma.

METHODS

We assessed the effect of GLUT-1 expression on radioresistance of laryngeal carcinoma and the effect of GLUT-1 expressions by antisense oligodeoxynucleotides (AS-ODNs) on the radiosensitivity of laryngeal carcinoma in vitro and in vivo.

RESULTS

After transfection of GLUT-1 AS-ODNs: MTS assay showed the survival rates of radiation groups were reduced with the prolongation of culture time (p<0.05); Cell survival rates were significantly reduced along with the increasing of radiation dose (p<0.05). There was significant difference in the expression of GLUT-1mRNA and protein in the same X-ray dose between before and after X-ray radiation (p<0.05). In vivo, the expressions of GLUT-1 mRNA and protein after 8Gy radiation plus transfection of GLUT-1 AS-ODNs were significant decreased compared to 8Gy radiation alone (p<0.001).

CONCLUSION

Radioresistance of laryngeal carcinoma may be associated with increased expression of GLUT-1 mRNA and protein. GLUT-1 AS-ODNs may enhance the radiosensitivity of laryngeal carcinoma mainly by inhibiting the expression of GLUT-1.

Alpha B-crystallin is a new prognostic marker for laryngeal squamous cell carcinoma

Background

Alpha B-crystallin (αB-crystallin) has been suggested to play an important role in the development of solid tumors. However, the association between αB-crystallin expression and clinicopathological characteristics of human laryngeal carcinoma is not well defined. This study aimed to examine the expression of αB-crystallin in human laryngeal squamous cell carcinoma (LSCC) and investigate the relationship between its expression and the prognosis of LSCC.

Methods

Real-time polymerase chain reaction (six LSCC samples, six tumor-adjacent normal samples) and immunohistochemistry by tissue microarrays (109 LSCC samples and 28 tumor-adjacent normal samples) were performed to characterize expression of the αB-crystallin gene in LSCC. Kaplan-Meier survival and Cox regression analyses were carried out to evaluate the prognosis of LSCC.

Results

Real-time polymerase chain reaction and immunohistochemistry analysis showed that the expression of αB-crystallin in LSCC was significantly higher than that in tumor-adjacent normal tissues. Moreover, the expression level of αB-crystallin protein in LSCC was significantly related to alcohol consumption (P = 0.022), tumor differentiation (P = 0.007), pTNM stage (P = 0.041) and 5 years’ survival (P =0.030). COX multi-factor analysis showed that αB-crystallin (P = 0.013), as well as pTNM stage (P =0.027) and lymphatic metastasis (P = 0.015) were independent prognosis factors for LSCC.

Conclusions

The data suggest that αB-crystallin expression is correlated with malignant phenotypes of LSCC and it may serve as a novel prognostic factor for LSCC.

Expression and significance of hypoxia-inducible factor-1α and glucose transporter-1 in laryngeal carcinoma

Malignant cells show increased glucose uptake in vitro and in vivo. This process is considered to be mediated by glucose transporters (GLUTs). Hypoxia-inducible factor-1α (HIF-1α) may upregulate GLUT-1 expression. Little is known about the correlation between HIF-1α and GLUT-1 expression in laryngeal carcinoma. The current study investigated this correlation immunohistochemically, according to various clinical and pathological features, in 49 paraffin-embedded archival tissue blocks from patients with laryngeal squamous cell carcinoma. HIF-1α and GLUT-1 expression was detected in 63.3 (31/49) and 55.1% (27/49) of the tumour samples, respectively. HIF-1α expression was significantly correlated with lymph node classification (P=0.018), recurrence (P=0.02) and metastasis (P=0.031). GLUT-1A expression was significantly associated with recurrence (P=0.02) and metastasis (P=0.01). Univariate analyses revealed that HIF-1α (χ(2)=8.2; P=0.004) and GLUT-1 expression (χ(2)=9.0; P=0.003) were significantly associated with a poorer survival rate. In a multivariate analysis, GLUT-1 expression (P=0.006) was a significant predictor of poor survival rate, as well as the primary tumour site, lymph node invasion and distant metastasis. Based on Spearman's analysis, GLUT-1 expression and phosphatidylinositol 3-kinase (PI3K) expression were significantly correlated (r=0.504; P=0.000). This is the first study to demonstrate a significant correlation between GLUT-1 and HIF-1α expression in laryngeal carcinoma and to show increased GLUT-1 expression as an independent survival rate predictor. These results suggest that GLUT-1 is a potential new therapeutic target for laryngeal carcinoma.

Dysregulation of glucose transport, glycolysis, TCA cycle and glutaminolysis by oncogenes and tumor suppressors in cancer cells

A common set of functional characteristics of cancer cells is that cancer cells consume a large amount of glucose, maintain high rate of glycolysis and convert a majority of glucose into lactic acid even in the presence of oxygen compared to that of normal cells (Warburg's Effects). In addition, cancer cells exhibit substantial alterations in several energy metabolism pathways including glucose transport, tricarboxylic acid (TCA) cycle, glutaminolysis, mitochondrial respiratory chain oxidative phosphorylation and pentose phosphate pathway (PPP). In the present work, we focused on reviewing the current knowledge about the dysregulation of the proteins/enzymes involved in the key regulatory steps of glucose transport, glycolysis, TCA cycle and glutaminolysis by several oncogenes including c-Myc and hypoxia inducible factor-1 (HIF-1) and tumor suppressor, p53, in cancer cells. The dysregulation of glucose transport and energy metabolism pathways by oncogenes and lost functions of the tumor suppressors have been implicated as important biomarkers for cancer detection and as valuable targets for the development of new anticancer therapies.