Glucose transporter 1 (GLUT1) of anaerobic glycolysis as predictive and prognostic values in neoadjuvant chemoradiotherapy and laparoscopic surgery for locally advanced rectal cancer

Identification of SLC2A1 as a predictive biomarker for survival and response to immunotherapy in lung squamous cell carcinoma

BACKGROUND

As one of the common subtypes of non-small lung cancer, lung squamous cell carcinoma (LUSC) patients with advanced stage have few choices of treatment strategies. Therefore, it is urgent to discover genes that are associated with the survival and efficacy of immunotherapies.

METHOD

Differential gene expression analyses were conducted using TCGA LUSC bulk-sequencing and single-cell RNA-sequencing data. Prognostic genes were identified from the TCGA LUSC cohort. Protein expression validation and survival analyses were performed. Experiments were conducted to explore the underlying mechanisms. In addition, the correlation between gene expression and pathological response to adjuvant immunochemotherapy was also investigated.

RESULTS

After a series of bioinformatic analyses, solute carrier family 2 member 1(SLC2A1), encoding glucose transporter-1 (GLUT1), was found to be differentially expressed between tumor and normal tissues. GLUT1 was subsequently identified as an independent prognostic factor for LUSC. GSEA analysis revealed the glycolysis metabolism pathway of KEGG enriched in SLC2A1high tumor tissues. LASSO analyses revealed that tumor tissues with high expression of SLC2A1 were associated with high levels of protein lactylation. We found that SLC2A1 was preferentially expressed by SPP1+ macrophages in the tumor microenvironment, and the expression of SLC2A1 was associated with the abundance of SPP1+ macrophages. Immunofluorescence demonstrated GLUT1 and HIF1α colocalization in tumor-infiltrating macrophages. In vitro experiments showed HIF-1α-induced macrophage polarization under hypoxia, and GLUT1 inhibition blocked this polarization. In addition, SLC2A1 was negatively associated with the common immune checkpoint molecules, such as programmed cell death 1(PD-1), T cell immunoreceptor with Ig and ITIM domains (TIGIT), cytotoxic T-lymphocyte associated protein 4 (CTLA4) and lymphocyte activating 3 (LAG3), while showed a positive association with CD44. Finally, we observed that there was a significant correlation between pre-adjuvant-treatment GLUT1 expression and the pathological response.

CONCLUSION

SLC2A1 expression was differentially upregulated in tumor tissues, and elevated GLUT1 expression was associated with worse survival and poor pathological response to adjuvant immunochemotherapy. Upregulation of GLUT1 promoted macrophage polarization into the M2 phenotype. The findings will contribute to guiding the treatment selection for LUSC patients and providing personalized immunotherapy strategies.

An arrayed CRISPR knockout screen identifies genetic regulators of GLUT1 expression

Glucose, a primary fuel source under homeostatic conditions, is transported into cells by membrane transporters such as glucose transporter 1 (GLUT1). Due to its essential role in maintaining energy homeostasis, dysregulation of GLUT1 expression and function can adversely affect many physiological processes in the body. This has implications in a wide range of disorders such as Alzheimer's disease (AD) and several types of cancers. However, the regulatory pathways that govern GLUT1 expression, which may be altered in these diseases, are poorly characterized. To gain insight into GLUT1 regulation, we performed an arrayed CRISPR knockout screen using Caco-2 cells as a model cell line. Using an automated high content immunostaining approach to quantify GLUT1 expression, we identified more than 300 genes whose removal led to GLUT1 downregulation. Many of these genes were enriched along signaling pathways associated with G-protein coupled receptors, particularly the rhodopsin-like family. Secondary hit validation confirmed that removal of select genes, or modulation of the activity of a corresponding protein, yielded changes in GLUT1 expression. Overall, this work provides a resource and framework for understanding GLUT1 regulation in health and disease.

PI3K/mTOR inhibitors promote G6PD autophagic degradation and exacerbate oxidative stress damage to radiosensitize small cell lung cancer

Our previous study revealed that PI3K/AKT/mTOR signaling was associated with SCLC radioresistance. SBC2 cells were used as primary radioresistance models, while H446 cells were continuously exposed to ionizing radiation (IR) to develop acquired radioresistance. Cell viability and apoptosis assays were used to investigate synergistic effects of BEZ235/GSK2126458 and IR in vitro, while immunoblotting, metabolite quantitative analysis and bioinformatic analyses were utilized to explore the underlying mechanism. Both genetically engineered mouse models (GEMM) and subcutaneous tumor models were used to confirm the synergistic effect in vivo. Key molecules of PI3K/AKT/mTOR signaling were upregulated after IR, which was correlated with primary radioresistance, and they were more expressed in acquired radioresistant cells. BEZ235/GSK2126458 effectively enhanced the cytotoxic effects of IR. BEZ235/GSK2126458 plus IR elevated γ-H2AX and p-Nrf2 expression, suggesting DNA and oxidative stress damage were intensified. Mechanistically, BEZ235/GSK2126458 plus IR significantly reduced the expression of G6PD protein, the rate-limiting enzyme of the pentose phosphate pathway (PPP). In detail, PI3K/mTOR inhibitors reinforced interaction between G6PD and HSPA8/HSC70, and G6PD was degraded by chaperone-mediated autophagy processes. Their metabolites (NADPH and R-5P) were decreased, and ROS levels were indirectly elevated, both of which exacerbated cell death. PI3K/AKT/mTOR signaling activator, insulin, enhanced SCLC radioresistance, while the synergistic effect of BEZ235/GSK2126458 and IR can be attenuated by N-acetylcysteine, and enhanced by 6-amino niacinamide. GEMM and allograft transplantation assays further confirmed their synergistic effect in vivo. This study provided insights into the connection between PI3K/AKT/mTOR signaling and the PPP underlying radioresistance and provided evidence of mechanisms supporting PI3K/mTOR inhibitors as possible therapeutic strategies to abrogate SCLC radioresistance.

GLUT-1 may predict metastases and death in patients with locally advanced rectal cancer

Introduction

Glucose transporter-1 (GLUT-1) has been studied as a possible predictor for survival outcomes in locally advanced rectal cancer (LARC).

Methods

We aimed to investigate the prognostic role of GLUT-1 in LARC using the data of 208 patients with clinical T3-4 stage and/or node-positive rectal adenocarcinoma, all of whom underwent neoadjuvant chemoradiotherapy (CRT) and subsequent total mesorectal excision (TME). Both pre-CRT and post-CRT specimens were immunohistologically stained for GLUT-1. Patients were classified into GLUT-1-positive and GLUT-1-negative groups and distant metastasis-free survival (DMFS) and overall survival (OS) was analyzed and compared.

Results

At a median follow-up of 74 months, post-CRT GLUT-1 status showed a significant correlation with worse DMFS (p=0.027, HR 2.26) and OS (p=0.030, HR 2.30). When patients were classified into 4 groups according to yp stage II/III status and post-CRT GLUT-1 positivity [yp stage II & GLUT-1 (-), yp stage II & GLUT-1 (+), yp stage III & GLUT-1 (-), yp stage III & GLUT-1 (+)], the 5-year DMFS rates were 92.3%, 63.9%, 65.4%, and 46.5%, respectively (p=0.013). GLUT-1 (-) groups showed markedly better outcomes for both yp stage II and III patients compared to GLUT-1 (+) groups. A similar tendency was observed for OS.

Discussion

In conclusion, post-CRT GLUT-1 may serve as a prognostic marker in LARC.

PI3K/AKT/mTOR pathway, hypoxia, and glucose metabolism: Potential targets to overcome radioresistance in small cell lung cancer

Small cell lung cancer (SCLC) is a highly aggressive tumor type for which limited therapeutic progress has been made. Platinum-based chemotherapy with or without thoracic radiotherapy remains the backbone of treatment, but most patients with SCLC acquire therapeutic resistance. Given the need for more effective therapies, better elucidation of the molecular pathogenesis of SCLC is imperative. The phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway is frequently activated in SCLC and strongly associated with resistance to ionizing radiation in many solid tumors. This pathway is an important regulator of cancer cell glucose metabolism, and its activation probably effects radioresistance by influencing bioenergetic processes in SCLC. Glucose metabolism has three main branches-aerobic glycolysis, oxidative phosphorylation, and the pentose phosphate pathway-involved in radioresistance. The interaction between the PI3K/AKT/mTOR pathway and glucose metabolism is largely mediated by hypoxia-inducible factor 1 (HIF-1) signaling. The PI3K/AKT/mTOR pathway also influences glucose metabolism through other mechanisms to participate in radioresistance, including inhibiting the ubiquitination of rate-limiting enzymes of the pentose phosphate pathway. This review summarizes our understanding of links among the PI3K/AKT/mTOR pathway, hypoxia, and glucose metabolism in SCLC radioresistance and highlights promising research directions to promote cancer cell death and improve the clinical outcome of patients with this devastating disease.

An appraisal of the current status of inhibition of glucose transporters as an emerging antineoplastic approach: Promising potential of new pan-GLUT inhibitors

Neoplastic cells displayed altered metabolism with accelerated glycolysis. Therefore, these cells need a mammoth supply of glucose for which they display an upregulated expression of various glucose transporters (GLUT). Thus, novel antineoplastic strategies focus on inhibiting GLUT to intersect the glycolytic lifeline of cancer cells. This review focuses on the current status of various GLUT inhibition scenarios. The GLUT inhibitors belong to both natural and synthetic small inhibitory molecules category. As neoplastic cells express multiple GLUT isoforms, it is necessary to use pan-GLUT inhibitors. Nevertheless, it is also necessary that such pan-GLUT inhibitors exert their action at a low concentration so that normal healthy cells are left unharmed and minimal injury is caused to the other vital organs and systems of the body. Moreover, approaches are also emerging from combining GLUT inhibitors with other chemotherapeutic agents to potentiate the antineoplastic action. A new pan-GLUT inhibitor named glutor, a piperazine-one derivative, has shown a potent antineoplastic action owing to its inhibitory action exerted at nanomolar concentrations. The review discusses the merits and limitations of the existing GLUT inhibitory approach with possible future outcomes.

Molecular basis for inhibiting human glucose transporters by exofacial inhibitors

Human glucose transporters (GLUTs) are responsible for cellular uptake of hexoses. Elevated expression of GLUTs, particularly GLUT1 and GLUT3, is required to fuel the hyperproliferation of cancer cells, making GLUT inhibitors potential anticancer therapeutics. Meanwhile, GLUT inhibitor-conjugated insulin is being explored to mitigate the hypoglycemia side effect of insulin therapy in type 1 diabetes. Reasoning that exofacial inhibitors of GLUT1/3 may be favored for therapeutic applications, we report here the engineering of a GLUT3 variant, designated GLUT3exo, that can be probed for screening and validating exofacial inhibitors. We identify an exofacial GLUT3 inhibitor SA47 and elucidate its mode of action by a 2.3 Å resolution crystal structure of SA47-bound GLUT3. Our studies serve as a framework for the discovery of GLUTs exofacial inhibitors for therapeutic development.

Human glucose transporters (GLUTs), particularly GLUT1 and GLUT3, are potential anticancer therapy targets. Here, Nan Wang et al. use an engineered GLUT 3 variant to identify an exofacial GLUT3 inhibitor, SA47, and elucidate the drug’s inhibitory mechanism.

MFSD4A inhibits the malignant progression of nasopharyngeal carcinoma by targeting EPHA2

DNA Methylation can lead to abnormal gene expression. In the present study, we investigated whether the expression of methylated MFSD4A (major facilitator superfamily domain containing 4 A) was downregulated in nasopharyngeal carcinoma (NPC) and whether it is associated with malignant progression and poor prognosis of NPC. Bioinformatic analysis, bisulfite pyrosequencing, quantitative real-time reverse transcription PCR, and western blotting assays were performed to explore the relationship between hypermethylation of MFSD4A and its expression in NPC. The role of MFSD4A in NPC was verified by Cell Cycle Kit 8, transwell assays and flow cytometry in vitro and by animal experiments in vivo. Mass spectrometry, co-immunoprecipitation, and immunofluorescence assays were applied to explore the mechanism by which MFSD4A inhibits NPC. The prognostic significance of MFSD4A or EPHA2 was investigated by immunohistochemical analysis of clinical specimens. Hypermethylation of the promoter region of MFSD4A led to decreased expression of MFSD4A. When MFSD4A expression was upregulated or downregulated, the proliferation, apoptosis, migration, and invasion abilities of NPC cells were altered accordingly. Mechanistically, MFSD4A could specifically bind to and degrade EPH receptor A2 (EPHA2) by recruiting ring finger protein 149 (RNF149), which led to alterations in the EPHA2-mediated PI3K-AKT-ERK1/2 pathway and epithelial-mesenchymal transition (EMT), thereby affecting NPC progression. Clinically, high MFSD4A expression or low-EPHA2 expression was associated with better prognosis for patients with NPC. In all, reduced MFSD4A expression in NPC is caused by promoter hypermethylation. MFSD4A or EPHA2 expression is associated with the malignant biological behavior and prognosis of NPC. MFSD4A is a promising potential therapeutic target for NPC.

CCL2 activates AKT signaling to promote glycolysis and chemoresistance in glioma cells

The incidence of gliomas is increasing. Although great progress in glioma treatment has been made, the clinical outcome remains unsatisfactory. Chemokine (C-C motif) ligand 2 (CCL2) plays a key role in different types of cancers, including glioma. However, the function of CCL2 in glioma chemoresistance is not fully understood. In the current study, CCL2 was significantly upregulated in glioma. More importantly, CCL2 and CCR2 were significantly upregulated in temozolomide (TMZ)-resistant glioma. TMZ-resistant malignant glioblastoma cells (U251/TMZ) had higher expressions of CCL2 and CCR2 and a higher level of glycolysis as compared to its parental cell line U251. Silencing of CCL2 in U251/TMZ cells inhibited glycolysis. Overexpression of CCL2 reduced TMZ-induced apoptosis through activation of the AKT pathway and promotion of glycolysis. Moreover, overexpression of CCL2 significantly reduced the antitumor effect of TMZ in vivo. In conclusion, CCL2 overexpression reduced the antitumor effect of TMZ by enhancing glycolysis through activation of AKT signaling. The findings highlighted the importance of CCL2/CCR2/glycolysis and its potential value i developing new treatment for glioma. This article is protected by copyright. All rights reserved.

Gill and liver transcriptomic responses of Achirus lineatus (Neopterygii: Achiridae) exposed to water-accommodated fraction (WAF) of light crude oil reveal an onset of hypoxia-like condition

Crude oil is one of the most widespread pollutants released into the marine environment, and native species have provided useful information about the effect of crude oil pollution in marine ecosystems. We consider that the lined sole Achirus lineatus can be a useful monitor of the effect of crude oil in the Gulf of Mexico (GoM) because this flounder species has a wide distribution along the GoM, and its response to oil components is relevant. The objective of this study was to compare the transcriptomic changes in liver and gill of adults lined sole fish (Achirus lineatus) exposed to a sublethal acute concentration of water-accommodated fraction (WAF) of light crude oil for 48 h. RNA-Seq was performed to assess the transcriptional changes in both organs. A total of 1073 differentially expressed genes (DEGs) were detected in gills; 662 (61.69%) were upregulated, and 411 (38.30%) were downregulated whereas in liver, 515 DEGs; 306 (59.42%) were upregulated, and 209 (40.58%) were downregulated. Xenobiotic metabolism and redox metabolism, along with DNA repair mechanisms, were activated. The induction of hypoxia-regulated genes and the generalized regulation of multiple signaling pathways support the hypothesis that WAF exposition causes a hypoxia-like condition.

"Sweet tooth"-oriented SN38 prodrug delivery nanoplatform for targeted gastric cancer therapy

Most cancer cells employ overexpression of glucose transports (GLUTs) to satisfy glucose demand ("Sweet Tooth") for increased aerobic glycolysis rates. GLUT1, one of the most widely expressed GLUTs in numerous cancers, was identified as a prognosis-related biomarker of gastric cancer via tissue array analysis. Herein, a "Sweet Tooth"-oriented SN38 prodrug delivery nanoplatform (Glu-SNP) was developed for targeted gastric cancer therapy. For this purpose, a SN38-derived prodrug (PLA-SN38) was synthesized by tethering 7-ethyl-10-hydroxycamptothecin (SN38) to biocompatible polylactic acid (PLA) with the appropriate degree of polymerization (n = 44). The PLA-SN38 conjugate was further assembled with glycosylated amphiphilic lipid to obtain glucosamine-decorated nanoparticles (Glu-SNP). Glu-SNP exhibited potent antitumor efficiency both in vitro and in vivo through enhanced cancer cell-specific targeting associated with the overexpression of GLUT1, which provides a promising approach for gastric cancer therapy.

Predicting pathological response to chemoradiotherapy for rectal cancer: a systematic review

Introduction: Pathological complete response (pCR) rates of approximately 20% following neoadjuvant long-course chemoradiotherapy for rectal cancer have given rise to non-operative or watch-and-wait (W&W) management. To improve outcomes there has been significant research into predictors of response. The goal is to optimize selection for W&W, avoid chemoradiotherapy in those who won't benefit and improve treatment to maximize the clinical complete response (cCR) rate and the number of patients who can be considered for W&W.Areas covered: A systematic review of articles published 2008-2018 and indexed in PubMed, Embase or Medline was performed to identify predictors of pathological response (including pCR and recognized tumor regression grades) to fluoropyrimidine-based chemoradiotherapy in patients who underwent total mesorectal excision for rectal cancer. Evidence for clinical, biomarker and radiological predictors is discussed as well as potential future directions.Expert opinion: Our current ability to predict the response to chemoradiotherapy for rectal cancer is very limited. cCR of 40% has been achieved with total neoadjuvant therapy. If neoadjuvant treatment for rectal cancer continues to improve it is possible that the treatment for rectal cancer may eventually parallel that of anal squamous cell carcinoma, with surgery reserved for the minority of patients who don't respond to chemoradiotherapy.

Influences of galactose ligand on the uptake of TADF liposomes by HepG2 cells

Glucose is the main energy substance to drive the physiological events of the cell.. Malignant cells exhibit a much higher rate of glycolysis than healthy cells to relieve the increased needs of energy. The higher metabolic rate induces the over-expression of the Glucose Transporter (GLUT) to transport more glucose into malignant cells. Our research regarded overexpressive GLUT as a target of nanoparticles. Substrate of GLUT galactose conjugated Polyethylene glycol-Distearyl phosphatidyl ethanolamine (PEG-DSPE) as a kind of ligand was selected to modified liposome. Thermally activated delayed fluorescence (TADF) was encapsulated as fluorescent probe to evaluate its abilities of targeting malignant cells, and the results of confocal microscopy and flow cytometry demonstrated that Galactose-PEG-DSPE modified liposome had the stronger efficiency of cellular uptake by HepG2 cells compared with Blank-PEG-DSPE modified liposome. The effect of GLUT1 inhibitor on cellular uptake of Galactose-PEG-DSPE modified liposomes showed that the mechanism might be relative to Warburg effect causing GLUT overexpression.

Influences of different sugar ligands on targeted delivery of liposomes

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

Glucose Transporter-1 (GLUT-1) Expression is Associated with Tumor Size and Poor Prognosis in Locally Advanced Gastric Cancer

Background

The clinicopathological parameters associated with glucose transporter-1 (GLUT-1) expression in advanced gastric cancer are still controversial. This study aimed to determine the clinicopathological parameters and prognosis associated with GLUT-1 expression in advanced gastric cancer.

Material/Methods

The GLUT-1 expression level of 234 consecutive gastric cancer samples was detected by immunohistochemical staining and evaluated by semiquantitative analysis. The clinicopathological data and expression level of GLUT-1 of enrolled patients were retrospectively analyzed with univariate and multivariate analyses.

Results

Tumor size, depth of invasion, and Lauren classification were independent factors related to GLUT-1 expression (P<0.05). Within advanced gastric cancer, tumor size and Lauren type were independent factors associated with GLUT-1 (P=0.011, P<0.001, respectively). The mean survival time of GLUT-1-positive patients with stage M0 advanced gastric cancer who had undergone radical gastrectomy was shorter than that of GLUT-1-negative patients (61.26±6.12 versus 80.88±7.38, P=0.044). GLUT-1 was an independent prognosis factor in locally advanced gastric cancer patients who had undergone radical gastrectomy (hazard ratio [HR] 1.769, P=0.046). The mean survival time of adjuvant chemotherapy was significantly better than no adjuvant chemotherapy in the GLUT-1-positive group (71.10±6.88 versus 24.65±8.69, P<0.001) and in the GLUT-1 negative group (87.48±7.99 versus 49.39±11.71, P<0.001).

Conclusions

Tumor size and Lauren type independently affected GLUT-1 expression in advanced gastric cancer. GLUT-1 was not only related to poor prognosis but also predicted to be a metabolic biomarker for intestinal type in locally advanced gastric cancer. The relationship among GLUT-1, hepatic metastasis and chemotherapy regimens, and mechanism of chemotherapy responses related to GLUT-1 should be further investigated.

Glucose Metabolites Exert Opposing Roles in Tumor Chemoresistance

Reprogrammed glucose metabolism and increased glycolysis have been implicated in tumor chemoresistance. The aim was to investigate the distinct roles of the glucose metabolites pyruvate and ATP in chemoresistance mechanisms, including cell death and proliferation. Our data showed higher glucose transporters in colorectal cancer (CRC) from non-responsive patients than those responsive to chemotherapy. Human CRC cell lines exposed to 5-fluorouracil (5-FU) displayed elevated cell viability and larger tumors in xenograft mouse models if cultured in high-glucose medium. Glucose conferred resistance to 5-FU-induced necroptosis via pyruvate scavenging of mitochondrial free radicals, whereas ATP replenishment had no effect on cell death. Glucose attenuated the 5-FU-induced G0/G1 shift but not the S phase arrest. Opposing effects were observed by glucose metabolites; ATP increased while pyruvate decreased the G0/G1 shift. Lastly, 5-FU-induced tumor spheroid destruction was prevented by glucose and pyruvate, but not by ATP. Our finding argues against ATP as the main effector for glucose-mediated chemoresistance and supports a key role of glycolytic pyruvate as an antioxidant for dual modes of action: necroptosis reduction and a cell cycle shift to a quiescent state.

The prognostic value of hypoxia-inducible factor-1α in advanced cancer survivors: a meta-analysis with trial sequential analysis

Background:

Expression of hypoxia-inducible factors (HIFs) has been observed, but their prognostic role in advanced cancers remains uncertain. We conducted a meta-analysis to establish the prognostic effect of HIFs and to better guide treatment planning for advanced cancers.

Methods:

Pooled hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated. Trial sequential analysis (TSA) was also performed. The clinical outcomes included overall survival (OS), disease-free survival (DFS), progression-free survival (PFS), cancer-specific survival (CSS), relapse/recurrence-free survival (RFS), and metastasis-free survival (MFS) in patients with advanced tumors according to multivariate analysis.

Results:

A total of 31 studies including 3453 cases who received chemotherapy, radiotherapy, or chemoradiotherapy were identified. Pooled analyses revealed that HIF-1α expression was correlated with worse OS (HR = 1.61, p < 0.001), DFS (HR = 1.61, p < 0.001), PFS (HR = 1.49, p = 0.01), CSS (HR = 1.65, p = 0.056), RFS (HR = 2.10, p = 0.015), or MFS (HR = 2.36, p = 0.002) in advanced cancers. HIF-1α expression was linked to shorter OS in the digestive tract, epithelial ovarian, breast, non-small cell lung, and clear cell renal cell carcinomas. Subgroup analysis by study region showed that HIF-1α expression was correlated with poor OS in Europeans and Asians, while an analysis by histologic subtypes found that HIF-1α expression was not associated with OS in squamous cell carcinoma. No relationship was found between HIF-2α expression and OS, DFS, PFS, or CSS.

Conclusions:

Targeting HIF-1α may be a useful therapeutic approach to improve survival for advanced cancer patients. Based on TSA, more randomized controlled trials are strongly suggested.

Warburg effect, lactate dehydrogenase, and radio/chemo-therapy efficacy

The anaerobic metabolism of glucose by cancer cells, even under well-oxygenated conditions, has been documented by Otto Warburg as early as 1927. Micro-environmental hypoxia and intracellular pathways activating the hypoxia-related gene response, shift cancer cell metabolism to anaerobic pathways. In the current review, we focus on a major enzyme involved in anaerobic transformation of pyruvate to lactate, namely lactate dehydrogenase 5 (LDH5). The value of LDH5 as a marker of prognosis of cancer patients, as a predictor of response to radiotherapy (RT) and chemotherapy and, finally, as a major target for cancer treatment and radio-sensitization is reported and discussed. Clinical, translational and experimental data supporting the uniqueness of the LDHA gene and its product LDH5 isoenzyme are summarized and future directions for a metabolic treatment of cancer are highlighted.

Single glucose molecule transport process revealed by force tracing and molecular dynamics simulations

Transporting individual molecules across cell membranes is a fundamental process in cellular metabolism. Although the crystal diffraction technique has greatly contributed to our understanding of the structures of the involved transporters, a description of the dynamic transport mechanism at the single-molecule level has been extremely elusive. In this study, we applied atomic force microscopy (AFM)-based force tracing to directly monitor the transport of a single molecule, d-glucose, across living cell membranes. Our results show that the force to transport a single molecule of d-glucose across cell membranes is 37 ± 9 pN, and the corresponding transport interval is approximately 20 ms, while the average speed is approximately 0.3 μm s^-1. Furthermore, our calculated force profile from molecular dynamics simulations showed quantitatively good agreement with the force tracing observation and revealed detailed information regarding the glucose transport path, indicating that two salt bridges, K38/E299 and K300/E426, play critical roles during glucose transport across glucose transporter 1 (GLUT1). This role was further verified using biological experiments that disrupted these two bridges and measured the uptake of glucose into the cells. Our approaches led to the first unambiguous description of the glucose transport process across cell membranes at the single-molecule level and demonstrated the biological importance of the two salt bridges for transporting glucose across GLUT1.

Immunometabolic Determinants of Chemoradiotherapy Response and Survival in Head and Neck Squamous Cell Carcinoma

Tumor immune microenvironment and tumor metabolism are major determinants of chemoradiotherapy response. The interdependency and prognostic significance of specific immune and metabolic phenotypes in head and neck squamous cell carcinoma (HNSCC) were assessed and changes in reactive oxygen species were evaluated as a mechanism of treatment response in tumor spheroid/immunocyte co-cultures. Pretreatment tumor biopsies were immunohistochemically characterized in 73 HNSCC patients treated by definitive chemoradiotherapy and correlated with survival. The prognostic significance of CD8A, GLUT1, and COX5B gene expression was analyzed within The Cancer Genome Atlas database. HNSCC spheroids were co-cultured in vitro with peripheral blood mononuclear cells (PBMCs) in the presence of the glycolysis inhibitor 2-deoxyglucose and radiation treatment followed by PBMC chemotaxis determination via fluorescence microscopy. In the chemoradiotherapy-treated HNSCC cohort, mitochondrial-rich (COX5B) metabolism correlated with increased and glucose-dependent (GLUT1) metabolism with decreased intratumoral CD8/CD4 ratios. High CD8/CD4, together with mitochondrial-rich or glucose-independent metabolism, was associated with improved short-term survival. The Cancer Genome Atlas analysis confirmed that patients with a favorable immune and metabolic gene signature (high CD8A, high COX5B, low GLUT1) had improved short- and long-term survival. In vitro, 2-deoxyglucose and radiation synergistically up-regulated reactive oxygen species-dependent PBMC chemotaxis to HNSCC spheroids. These results suggest that glucose-independent tumor metabolism is associated with CD8-dominant antitumor immune infiltrate, and together, these contribute to improved chemoradiotherapy response in HNSCC.

GLUT-1 overexpression as an unfavorable prognostic biomarker in patients with colorectal cancer

Background

Glucose transporter-1 (GLUT-1) exhibits altered expression in colorectal cancer (CRC). The aim of this study was to explore the association between GLUT-1 and survival conditions, as well as clinical features in CRC by meta-analysis.

Materials and Methods

Relevant studies were searched through predefined strategies, hazard ratios (HRs), odds ratios (ORs), and their 95% confidence intervals (CIs) were used as effective measures.

Results

A total of 14 studies with 2,077 patients were included in this meta-analysis. The results showed that GLUT-1 was not significantly associated with overall survival (OS) (HR=1.28, 95% CI=0.86–1.91, p=0.22) or disease-free survival (DFS) (HR=1.71, 95% CI=0.78–3.72, p=0.179). However, subgroup analysis indicated that GLUT-1 was a significant biomarker for poor DFS in rectal cancer (HR=2.47, 95% CI=1.21–5.05, p=0.013). GLUT-1 expression was also found to be significantly correlated with the presence of lymph node metastasis (n=8, OR=2.14, 95% CI=1.66–2.75, p<0.001), T stage (n=6, OR=1.73, 95% CI=1.17–2.58, p=0.007), higher Dukes stage (n=5, OR=2.92, 95% CI=2.16–3.95, p<0.001), female sex (n=4, OR=2.92, 95% CI=2.16–3.95, p<0.001), and presence of liver metastasis (n=3, OR=1.82, 95% CI=1.06–3.12, p=0.03).

Conclusion

In conclusion, this meta-analysis showed that GLUT-1 was associated with poor DFS in rectal cancer (RC). Furthermore, GLUT-1 was also an indicator of aggressive clinical features in CRC.

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.

Glycogen metabolic reprogramming in hepatocellular carcinoma: An update

Hepatocellular carcinoma (HCC) is a highly prevalent malignant tumor. Abnormal glycogen metabolism, an important metabolism process in HCC, mainly results from the variant structure, function, and expression levels of the corresponding enzymes and proteins. This variation, also called metabolic reprogramming, can regulate glycogen metabolic pathway to promote HCC tumorigenesis. This review aims to summarize glycogen metabolism-regulated factors (including glucose transporters, glycogen synthase kinase 3β, and glycogen phosphorylase) involved in glycogen metabolic reprogramming in HCC

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

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

Mechanistic Study of Human Glucose Transport Mediated by GLUT1

The glucose transporter 1 (GLUT1) belongs to the major facilitator superfamily (MFS) and is responsible for the constant uptake of glucose. However, the molecular mechanism of sugar transport remains obscure. In this study, homology modeling and molecular dynamics (MD) simulations in lipid bilayers were performed to investigate the combination of the alternate and multisite transport mechanism of glucose with GLUT1 in atomic detail. To explore the substrate recognition mechanism, the outward-open state human GLUT1 homology model was generated based on the template of xylose transporter XylE (PDB ID: 4GBZ), which shares up to 29% sequence identity and 49% similarity with GLUT1. Through the MD simulation study of glucose across lipid bilayer with both the outward-open GLUT1 and the GLUT1 inward-open crystal structure, we investigated six different conformational states and identified four key binding sites in both exofacial and endofacial loops that are essential for glucose recognition and transport. The study further revealed that four flexible gates consisting of W65/Y292/Y293-M420/TM10b-W388 might play important roles in the transport cycle. The study showed that some side chains close to the central ligand binding site underwent larger position changes. These conformational interchanges formed gated networks within an S-shaped central channel that permitted staged ligand diffusion across the transporter. This study provides new inroads for the understanding of GLUT1 ligand recognition paradigm and configurational features which are important for molecular, structural, and physiological research of the MFS members, especially for GLUT1-targeted drug design and discovery.

GLUT, SGLT, and SWEET: Structural and mechanistic investigations of the glucose transporters

Glucose is the primary fuel to life on earth. Cellular uptake of glucose is a fundamental process for metabolism, growth, and homeostasis. Three families of secondary glucose transporters have been identified in human, including the major facilitator superfamily glucose facilitators GLUTs, the sodium-driven glucose symporters SGLTs, and the recently identified SWEETs. Structures of representative members or their prokaryotic homologs of all three families were obtained. This review focuses on the recent advances in the structural elucidation of the glucose transporters and the mechanistic insights derived from these structures, including the molecular basis for substrate recognition, alternating access, and stoichiometric coupling of co-transport.

An "imaging-biopsy" strategy for colorectal tumor reconfirmation by multipurpose paramagnetic quantum dots

Glucose transporter1 (Glut1) plays important roles in treatment of colorectal cancer (CRC) involving early-stage diagnosis, subtype, TNM stage, and therapeutic schedule. Currently, in situ marking and tracking of the tumor biomarkers via clinical imaging remains great challenges in early stage CRC diagnosis. In this study, we have developed a unique cell-targeted, paramagnetic-fluorescent double-signal molecular nanoprobe for CRC in vivo magnetic resonance imaging (MRI) diagnosis and subsequent biopsy. The unique molecular nanoprobe is composed of a fluorescent quantum dot (QD) core; a coating layer of paramagnetic DTPA-Gd coupled BSA ((Gd)DTPA∙BSA), and a surface targeting moiety of anti-Glut1 polyclonal antibody. The engineered (Gd)DTPA∙BSA@QDs-PcAb is 35 nm in diameter and colloidally stable under both basic and acidic conditions. It exhibits strong fluorescent intensities and high relaxivity (r1 and r2: 16.561 and 27.702 s(-1) per mM of Gd(3+)). Distribution and expression of Glut1 of CRC cells are investigated by in vitro cellular confocal fluorescent imaging and MR scanning upon treating with the (Gd)DTPA∙BSA@QDs-PcAb nanoprobes. In vivo MRI shows real-time imaging of CRC tumor on nude mice after intravenously injection of the (Gd)DTPA∙BSA@QDs-PcAb nanoprobes. Ex vivo biopsy is subsequently conducted for expression of Glut1 on tumor tissues. These nanoprobes are found biocompatible in vitro and in vivo. (Gd)DTPA∙BSA@QDs-PcAb targeted nanoprobe is shown to be a promising agent for CRC cancer in vivo MRI diagnosis and ex vivo biopsy analysis. The "imaging-biopsy" is a viable strategy for tumor reconfirmation with improved diagnostic accuracy and biopsy in personalized treatment.

GRP78 Protein Expression as Prognostic Values in Neoadjuvant Chemoradiotherapy and Laparoscopic Surgery for Locally Advanced Rectal Cancer

Purpose

We investigated the relationships between biomarkers related to endoplasmic reticulum stress proteins (glucose-regulated protein of molecular mass 78 [GRP78] and Cripto-1 [teratocarcinoma-derived growth factor 1 protein]), pathologic response, and prognosis in locally advanced rectal cancer.

Materials and Methods

All clinical stage II and III rectal cancer patients received 50.4 Gy over 5.5 weeks, plus 5-fluorouracil (400 mg/m²/day) and leucovorin (20 mg/m²/day) bolus on days 1 to 5 and 29 to 33, and surgery was performed at 7 to 10 weeks after completion of all therapies. Expression of GRP78 and Cripto-1 proteins was determined by immunohistochemistry and was assessed in 101 patients with rectal cancer treated with neoadjuvant chemoradiotherapy (CRT).

Results

High expression of GRP78 and Cripto-1 proteins was observed in 86 patients (85.1%) and 49 patients (48.5%), respectively. Low expression of GRP78 protein was associated with a significantly high rate of down staging (80.0% vs. 52.3%, respectively; p=0.046) and a significantly low rate of recurrence (0% vs. 33.7%, respectively; p=0.008) compared with high expression of GRP78 protein. Mean recurrence-free survival according to GRP78 expression could not be estimated because the low expression group did not develop recurrence events but showed a significant correlation with time to recurrence, based on the log rank method (p=0.007). GRP78 also showed correlation with overall survival, based on the log rank method (p=0.045).

Conclusion

GRP78 expression is a predictive and prognostic factor for down staging, recurrence, and survival in rectal cancer patients treated with 5-fluorouracil and leucovorin neoadjuvant CRT.

Nanoparticle-based targeted therapeutics in head-and-neck cancer

Head-and-neck cancer is a major form of the disease worldwide. Treatment consists of surgery, radiation therapy and chemotherapy, but these have not resulted in improved survival rates over the past few decades. Versatile nanoparticles, with selective tumor targeting, are considered to have the potential to improve these poor outcomes. Application of nanoparticle-based targeted therapeutics has extended into many areas, including gene silencing, chemotherapeutic drug delivery, radiosensitization, photothermal therapy, and has shown much promise. In this review, we discuss recent advances in the field of nanoparticle-mediated targeted therapeutics for head-and-neck cancer, with an emphasis on the description of targeting points, including future perspectives.

Crystal structure of the human glucose transporter GLUT1

The glucose transporter GLUT1 catalyses facilitative diffusion of glucose into erythrocytes and is responsible for glucose supply to the brain and other organs. Dysfunctional mutations may lead to GLUT1 deficiency syndrome, whereas overexpression of GLUT1 is a prognostic indicator for cancer. Despite decades of investigation, the structure of GLUT1 remains unknown. Here we report the crystal structure of human GLUT1 at 3.2 Å resolution. The full-length protein, which has a canonical major facilitator superfamily fold, is captured in an inward-open conformation. This structure allows accurate mapping and potential mechanistic interpretation of disease-associated mutations in GLUT1. Structure-based analysis of these mutations provides an insight into the alternating access mechanism of GLUT1 and other members of the sugar porter subfamily. Structural comparison of the uniporter GLUT1 with its bacterial homologue XylE, a proton-coupled xylose symporter, allows examination of the transport mechanisms of both passive facilitators and active transporters.